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

Abstract

This invention provides a liquid crystal alignment agent, a liquid crystal alignment film, and a liquid crystal display element. The resulting liquid crystal display element exhibits low flicker after being driven. The liquid crystal alignment agent comprises a polymer (A) and a solvent (B). The polymer (A) is prepared by polymerization of a mixture comprising a tetracarboxylic dianhydride component (a) and a diamine component (b), and has a structure as shown in formula (I).

Description

Technical Field

[0001] This invention relates to a liquid crystal alignment agent, a liquid crystal alignment film, and a liquid crystal display element, and more particularly to a liquid crystal display element with better flicker after being driven, using the liquid crystal alignment agent. Background Technology

[0002] Liquid crystal display elements used in LCD TVs, LCD monitors, etc., typically have a liquid crystal alignment film inside the element to control the alignment of the liquid crystals. Currently, the most common industrial method is to produce this liquid crystal alignment film by rubbing a cloth such as cotton, nylon, or polyester on the surface of a film formed by polyamic acid and / or imidized polyimide on an electrode substrate in one direction, and performing a so-called friction treatment.

[0003] Friction treatment of the film surface during the alignment process of liquid crystal alignment film is a relatively easy method to produce industrially. However, with the increasing demands for high efficiency, high precision, and large size of liquid crystal display elements, various problems such as damage to the alignment film surface, dust, the effects of mechanical and electrostatic forces, and non-uniformity on the alignment surface have become more prominent during friction treatment.

[0004] As an alternative to friction treatment, photoalignment, which utilizes ultraviolet irradiation with polarized light to impart alignment energy to liquid crystals, is currently known. The liquid crystal alignment treatment in photoalignment includes substances that utilize photoisomerization, photocrosslinking, or photodecomposition reactions in terms of reaction mechanism. Furthermore, Japanese Patent Application Publication No. 9-297313 proposes a photoalignment method using a polyimide film with an alicyclic structure such as cyclobutane in its main chain. When using polyimide as an alignment film for photoalignment, its heat resistance is higher than other types of alignment films, making its application promising.

[0005] Photoalignment is a non-frictional alignment process. Industrially, it not only has the advantage of being manufactured using a simple process, but also, in liquid crystal display elements driven by In-Plane-Switching (IPS) and Fringe Field Switching (FFS) technologies, compared to liquid crystal alignment films obtained by frictional processes, the liquid crystal alignment film obtained by photoalignment is expected to improve the contrast and viewing angle characteristics of the liquid crystal display element. Therefore, photoalignment is a promising and highly anticipated liquid crystal alignment process.

[0006] However, when liquid crystal alignment films prepared by photoalignment are applied to liquid crystal display elements, the resulting liquid crystal display elements still suffer from poor flicker after driving. As mentioned above, in order to meet the requirements of current manufacturers of photoaligned IPS liquid crystal displays, providing a liquid crystal alignment agent that can form liquid crystal display elements with better flicker after driving is the goal of research in this field. Summary of the Invention

[0007] In view of this, the present invention provides a liquid crystal alignment agent that can improve the above-mentioned problem of poor flicker after driving.

[0008] This invention provides a liquid crystal alignment agent, comprising: a polymer (A) and a solvent (B). The polymer (A) is prepared by polymerization of a mixture comprising a tetracarboxylic dianhydride component (a) and a diamine component (b), and has a structure as shown in formula (I) below:

[0009]

[0010] In formula (I), Y 1 X represents a protecting group that is replaced by a hydrogen atom through heat. 1 X 2 Each represents a divalent organic group independently, and * indicates a bond.

[0011] In one embodiment of the present invention, in formula (I) above, Y 1 Represents a group as shown in formula (II) below:

[0012]

[0013] In equation (II), Y 2 The symbol represents a straight-chain hydrocarbon group with 1 to 20 carbon atoms, a branched hydrocarbon group with 3 to 20 carbon atoms, or a cyclic hydrocarbon group with 3 to 20 carbon atoms. * indicates a bond.

[0014] In one embodiment of the present invention, the diamine component (b) comprises a diamine compound (b1) having a structure as shown in the following formula (b-1):

[0015]

[0016] In equation (b-1), Y 1 Y in equation (I) 1 X 3 X 4 Each independently represents an alkylene group having 1 to 3 carbon atoms, X 5 X 6 Each can be used independently to represent a single bond, -O-, -S-, -OCO-, or -COO-.

[0017] In one embodiment of the present invention, the above-mentioned tetracarboxylic dianhydride component (a) comprises a tetracarboxylic dianhydride compound (a1) having the structure shown in the following formula (a-1):

[0018]

[0019] In equation (a-1), R 1 To R 4 Each of these 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 monovalent organic group containing a fluorine atom and having 1 to 6 carbon atoms, or a phenyl group, R. 1 To R 4 For the same or different, and R 1 R 2 R 3 and R 4 At least one of them is not a hydrogen atom.

[0020] In one embodiment of the present invention, the diamine component (b) comprises a diamine compound (b2) having a structure as shown in the following formula (b-2):

[0021]

[0022] In equation (b-2), Ar represents the aromatic ring, and X... 11 X represents an alkylene group having 1 to 5 carbon atoms. 12 It represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

[0023] In one embodiment of the present invention, the amount of tetracarboxylic dianhydride component (a) used is 100 moles, and the amount of tetracarboxylic dianhydride compound (a1) used is 10 to 100 moles.

[0024] In one embodiment of the present invention, the amount of diamine component (b) used is 100 moles, and the amount of diamine compound (b1) used is from 0.5 moles to 50 moles.

[0025] In one embodiment of the present invention, the amount of diamine component (b) used is 100 moles, and the amount of diamine compound (b2) used is from 1 mole to 99.5 moles.

[0026] In one embodiment of the present invention, the amount of polymer (A) used is 100 parts by weight, and the amount of solvent (B) used is 800 to 4000 parts by weight.

[0027] The present invention further provides a liquid crystal alignment film formed using a liquid crystal alignment agent as described above.

[0028] The present invention further provides a liquid crystal display element, including the liquid crystal alignment film as described above.

[0029] Based on the above, the liquid crystal alignment agent of the present invention uses a polymer (A) with a specific structure, and therefore, the liquid crystal alignment agent can improve the technical problem of poor flicker after driving in the prior art.

[0030] To make the above features and advantages of the present invention more apparent and understandable, specific embodiments are described below in conjunction with the accompanying drawings. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of the liquid crystal display element of the present invention.

[0032] Explanation of reference numerals in the attached figures

[0033] 100: Liquid Crystal Display Element

[0034] 110: Unit 1

[0035] 112: First substrate

[0036] 114: First conductive film

[0037] 116: First liquid crystal alignment film

[0038] 120: Unit 2

[0039] 122: Second substrate

[0040] 126: Second liquid crystal alignment film

[0041] 130: Liquid Crystal Unit Detailed Implementation

[0042] Liquid crystal alignment agent

[0043] This invention provides a liquid crystal alignment agent comprising a polymer (A) and a solvent (B), and optionally an additive (C). The polymer (A) is prepared by polymerization of a mixture comprising a tetracarboxylic dianhydride component (a) and a diamine component (b), and has a structure as shown in formula (I). The various components of the liquid crystal alignment agent used in this invention will be described in detail below.

[0044] [Polymer(A)]

[0045] Polymer (A) is prepared by polymerization of a mixture comprising a tetracarboxylic dianhydride component (a) and a diamine component (b), and has a structure as shown in formula (I) below:

[0046]

[0047] In formula (I), Y 1 X represents a protecting group that is replaced by a hydrogen atom through heat. 1 X2 Each represents a divalent organic group independently, and * indicates a bond.

[0048] Preferred examples of polymer (A) are polyamic acid polymers, polyimide polymers, polyimide-based block copolymers, or combinations thereof. Among these, preferred examples of polyimide-based block copolymers are polyamic acid block copolymers, polyimide block copolymers, polyamic acid-polyimide block copolymers, or any combination thereof.

[0049] As X in equation (I) 1 X 2 The divalent organic groups represented can be categorized as groups having structures derived from monomer skeletons used in polymer synthesis.

[0050] Y in equation (I) 1 The protecting group represented by this term, which is replaced by hydrogen atoms through heat, is a thermally desorbable group. More specifically, Y 1 Since it is an amine protecting group, its structure is not particularly limited as long as it is a protecting group that is replaced by hydrogen atoms through heat. From the viewpoint of the storage stability of liquid crystal alignment agents, this protecting group Y... 1 Preferably, the protective group is one that does not detach at room temperature; more preferably, it is one that detaches at temperatures above 80°C; even more preferably, it is one that detaches at temperatures above 100°C; and particularly preferably, it is one that detaches at temperatures above 120°C. Protective group Y 1 The detachment temperature is preferably below 250°C, more preferably below 230°C. If the detachment temperature is too high, it may cause polymer decomposition.

[0051] Y in equation (I) 1 Preferably, it represents a group as shown in the following formula (II):

[0052]

[0053] In equation (II), Y 2 The symbol represents a straight-chain hydrocarbon group with 1 to 20 carbon atoms, a branched hydrocarbon group with 3 to 20 carbon atoms, or a cyclic hydrocarbon group with 3 to 20 carbon atoms. * indicates a bond.

[0054] Based on the viewpoint of raw material availability, Y 2 Preferably, it can be, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, benzoyl, n-hexadecyl, or 9-pyromethyl. Based on the viewpoint of polymer solubility and thermal dissociation, Y 2 Preferred, for example, is tert-butyl.

[0055] When the polymer (A) in the liquid crystal alignment agent does not contain the structure shown in formula (I), the resulting liquid crystal display element has poor post-drive flicker.

[0056] [Tetracarboxylic dianhydride component (a)]

[0057] The tetracarboxylic dianhydride component (a) includes a tetracarboxylic dianhydride compound (a1) having the structure shown in formula (a-1) and other tetracarboxylic dianhydride compounds (a2).

[0058] [Tetracarboxylic dianhydride compound (a1)]

[0059] The tetracarboxylic acid dianhydride compound (a1) has the structure shown in the following formula (a-1):

[0060]

[0061] In equation (a-1), R 1 To R 4 Each of these 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 monovalent organic group containing a fluorine atom and having 1 to 6 carbon atoms, or a phenyl group, R. 1 To R 4 For the same or different, and R 1 R 2 R 3 and R 4 At least one of them is not a hydrogen atom.

[0062] R1, R2, R3, and R4 are preferably constructs with the least possible steric hindrance. Specifically, they are preferably hydrogen atoms, methyl groups, or ethyl groups, with methyl groups being more preferred.

[0063] Specific examples of tetracarboxylic dianhydride compounds (a1) having the structure shown in formula (a-1) are listed below as compounds shown in formulas (a-1-1) to (a-1-8). Formula (a-1-1) is preferred for the purpose of improving the scintillation after actuation.

[0064]

[0065] Tetracarboxylic dianhydride compounds (a1) can be used alone or in combination.

[0066] The total amount of tetracarboxylic dianhydride component (a) used is 100 moles, and the amount of tetracarboxylic dianhydride compound (a1) used is 10 to 100 moles, preferably 15 to 80 moles, and more preferably 20 to 70 moles.

[0067] If the tetracarboxylic acid dianhydride component (a) contains a tetracarboxylic acid dianhydride compound (a1), the flicker after driving of the formed liquid crystal display element can be further reduced.

[0068] [Other tetracarboxylic dianhydride compounds (a2)]

[0069] Other preferred examples of tetracarboxylic dianhydride compounds (a2) include: (1) aliphatic tetracarboxylic dianhydride compounds, (2) alicyclic tetracarboxylic dianhydride compounds, (3) aromatic tetracarboxylic dianhydride compounds, or (4) tetracarboxylic dianhydride compounds represented by formulas (a-2-1) to (a-2-6), etc.

[0070] (1) Aliphatic tetracarboxylic dianhydride compounds include, but are not limited to, aliphatic tetracarboxylic dianhydride compounds such as ethane tetracarboxylic dianhydride or butane tetracarboxylic dianhydride.

[0071] (2) Alicyclic tetracarboxylic dianhydrides 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... Alicyclic tetracarboxylic anhydride compounds such as 3,4-cyclopentanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 3,3',4,4'-dicyclohexyltetracarboxylic dianhydride, cis-3,7-dibutylcycloheptyl-1,5-diene-1,2,5,6-tetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic dianhydride, or bicyclo[2.2.2]-oct-7-ene-2,3,5,6-tetracarboxylic dianhydride.

[0072] (3) Specific examples of aromatic tetracarboxylic dianhydrides may include, but are not limited to, 3,4-dicarboxy-1,2,3,4-tetrahydronaphthalene-1-succinic dianhydride, benzopyrene 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, and 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride. 3,3',4,4'-Diphenyl ether tetracarboxylic acid dianhydride, 4,4'-bis(3,4-dicarboxyphenoxy)diphenyl sulfide dianhydride, 2,3,3',4'-diphenyl sulfide tetracarboxylic acid dianhydride, 3,3',4,4'-diphenyl sulfide tetracarboxylic acid dianhydride, 4,4'-bis(3,4-dicarboxyphenoxy)diphenyl sulfone dianhydride, 4,4'-bis(3,4-dicarboxyphenoxy)diphenylpropane dianhydride, 3,3',4,4'-perfluoroisopropyl phthalic acid dianhydride, 2,2',3,3'-diphenyltetracarboxylic acid dianhydride, 2,3,3',4'-diphenyltetracarboxylic acid dianhydride, 3,3',4,4'-diphenyltetracarboxylic acid dianhydride, bis(phthalic acid)phenylphosphine oxide dianhydride, p-phenylene-bis(triphenylphthalic acid) dianhydride, m-phenylene Benzyl-bis(triphenylphthalic acid) dianhydride, bis(triphenylphthalic acid)-4,4'-diphenyl ether dianhydride, bis(triphenylphthalic acid)-4,4'-diphenylmethane dianhydride, ethylene glycol-bis(dehydrated trimellitate), propylene glycol-bis(dehydrated trimellitate), 1,4-butanediol-bis(dehydrated trimellitate), 1,6-hexanediol-bis(dehydrated trimellitate), 1,8-octanediol-bis(dehydrated trimellitate), 2,2-bis(4-hydroxyphenyl)propane-bis(dehydrated trimellitate), 2,3,4,5-tetrahydrofurantetracarboxylic acid dianhydride, 1,3,3a,4,5,9b-hexahydro-5-(tetrahydro-2,5-disideoxy-3-furanyl)-naphtho[1,2-c]-furan-1,3-dione, 1 3,3a,4,5,9b-Hexahydro-5-methyl-5-(tetrahydro-2,5-dioxy-3-furanyl)-naphtho[1,2-c]-furan-1,3-dione, 1,3,3a,4,5,9b-Hexahydro-5-ethyl-5-(tetrahydro-2,5-dioxy-3-furanyl)-naphtho[1,2-c]-furan-1,3-dione, 1,3,3a,4,5,9b-Hexahydro-7-methyl-5-(tetrahydro-2,5-dioxy-3-furanyl)-naphtho[1,2-c]-furan-1,3-dione, 1,3,3a,4,5,9b-Hexahydro-7-ethyl-5-(tetrahydro-2,5-dioxy-3-furanyl)-naphtho[1,2-c]-furan-1,3-Diketone, 1,3,3a,4,5,9b-hexahydro-8-methyl-5-(tetrahydro-2,5-dioxy-3-furanyl)-naphtho[1,2-c]-furan-1,3-diketone, 1,3,3a,4,5,9b-hexahydro-8-ethyl-5-(tetrahydro-2,5-dioxy-3-furanyl)-naphtho[1,2-c]-furan-1,3-diketone, 1,3,3a,4,5,9b-hexahydro-5,8-dimethyl-5-(tetrahydro-2,5-dioxy-3-furanyl)-naphtho[1,2-c]-furan-1,3-diketone, 5-(2,5-dioxytetrahydrofuranyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic acid dianhydride, etc.

[0073] (4) The tetracarboxylic acid dianhydride compounds represented by formulas (a-2-1) to (a-2-6) are shown below.

[0074]

[0075] In formula (a-2-5), A1 represents a divalent group containing an aromatic ring; r represents an integer from 1 to 2; A2 and A3 may be the same or different, and may each independently represent a hydrogen atom or an alkyl group. Specific examples of tetracarboxylic dianhydride compounds represented by formula (a-2-5) include at least one of the compounds represented by formulas (a-2-5-1) to (a-2-5-3).

[0076]

[0077] In formula (a-2-6), A4 represents a divalent group containing an aromatic ring; A5 and A6 may be the same or different, and each independently represents a hydrogen atom or an alkyl group. The tetracarboxylic acid dianhydride compound represented by formula (a-2-6) is preferably a compound represented by formula (a-2-6-1).

[0078]

[0079] Other tetracarboxylic dianhydride compounds (a2) can be used alone or in combination.

[0080] The total amount of tetracarboxylic dianhydride component (a) used is 100 moles, and the amount of other tetracarboxylic dianhydride compounds (a2) used is 0 to 90 moles, preferably 20 to 85 moles, and more preferably 30 to 80 moles.

[0081] The total amount of diamine component (b) used is 100 moles, and the total amount of tetracarboxylic acid dianhydride component (a) used is 20 to 200 moles, preferably 30 to 120 moles.

[0082] [Diamine component (b)]

[0083] The diamine component (b) includes a diamine compound (b1) having the structure shown in formula (b-1), a diamine compound (b2) having the structure shown in formula (b-2), and other diamine compounds (b3).

[0084] [Diamine compound (b1)]

[0085] The diamine compound (b1) has the structure shown in the following formula (b-1):

[0086]

[0087] In equation (b-1), Y 1 Y in equation (I) 1 X 3 X 4 Each independently represents an alkylene group having 1 to 3 carbon atoms, X 5 X 6 Each can be used independently to represent a single bond, -O-, -S-, -OCO-, or -COO-.

[0088] X 3 X 4 Each alkyl group independently represents an alkylene group having 1 to 3 carbon atoms. The alkylene group can be linear or branched. Specific examples include methylene, ethylene, propylene, 1-methylethylene, 2-methylethylene, etc. Preferably, it has a structure with as many free rotational sites as possible and minimal steric hindrance. Specifically, methylene, ethylene, and propylene are preferred.

[0089] X 5 X 6 Each can be independently represented as a single bond, -O-, -S-, -OCO-, or -COO-. Preferably, the construct is as flexible as possible and has minimal dimensional barriers. Specifically, single bonds, -O-, and -S- are preferred.

[0090] Specific examples of diamine compounds (b1) having the structure shown in formula (b-1) can be listed as compounds shown in formulas (b-1-1) to (b-1-11).

[0091]

[0092]

[0093] Diamine compounds (b1) can be used alone or in combination.

[0094] The total amount of diamine component (b) used is 100 moles, and the amount of diamine compound (b1) used is 0.5 moles to 50 moles, preferably 0.5 moles to 40 moles, and more preferably 0.5 moles to 30 moles.

[0095] If the diamine component (b) does not contain diamine compound (b1), the resulting liquid crystal display element will have poor flicker after being driven.

[0096] [Synthetic methods for diamine compound (b1)]

[0097] The synthesis method of diamine compound (b1) is not particularly limited. As a general synthesis method, it can be produced by reducing the dinitro compound Cpd.2 of diamine compound Cpd.1, as shown below. Furthermore, X 3 X 4 X 5 X 6 The meaning of X as described in equation (b-1) 3 X 4 X 5 X 6 The meanings are the same.

[0098]

[0099] The reduction reactions described above include hydrogenation reactions in the presence of a catalyst, reduction reactions in the presence of protons, reduction reactions using formic acid as a hydrogen source, and reduction reactions using hydrazine as a hydrogen source, and these reduction reactions can also be combined. Considering the structure of the dinitro compound Cpd.2 and the reactivity of the reduction reaction, hydrogenation reactions are preferred.

[0100] For catalysts used in reduction reactions, metals supported on activated carbon that are commercially available are preferred; examples include palladium-activated carbon, platinum-activated carbon, and rhodium-activated carbon. Furthermore, metal catalysts that do not necessarily require activated carbon support, such as palladium hydroxide, platinum dioxide, and Raney nickel, are also acceptable. Palladium-activated carbon, which is widely used, is preferred due to its good results.

[0101] To make the reduction reaction more effective, it can be carried out in the presence of activated carbon. The amount of activated carbon used is not particularly limited, but for the dinitro compound Cpd.2, 1–20% by mass is preferred, and 5–10% by mass is even more desirable.

[0102] For the same reason, there are also cases where the reaction is carried out under pressure. In this case, to avoid the reduction of the benzene ring, the reaction can be carried out at a pressure range of up to 20 atmospheres. Preferably, the reaction is carried out at a pressure range of up to 10 atmospheres.

[0103] For reduction reactions, it is best to use a solvent, which is only a solvent that does not react with the raw materials and can be used without restriction.

[0104] For example, aprotic polar organic solvents can be used (DMF (N,N-dimethylformamide), DMSO (dimethyl sulfoxide), DMAc (dimethylacetamide), NMP (N-methyl-2-pyrrolidone), etc.); ethers (Et2O (diethyl ether), i-Pr2O (diisopropyl ether), TBME (methyl tert-butyl ether), CPME (cyclopentylmethyl ether), THF (tetrahydrofuran), dioxane, etc.); aliphatic hydrocarbons (pentane, hexane, heptane, petroleum ether, etc.); aromatic hydrocarbons (benzene, toluene, xylene, trimethylbenzene, chlorobenzene, dichlorobenzene, nitrobenzene, tetrahydronaphthalene, etc.); halogenated hydrocarbons (chloroform, dichloromethane, carbon tetrachloride, dichloroethane, etc.); lower fatty acid esters (methyl acetate, ethyl acetate, butyl acetate, methyl propionate, etc.); nitriles (acetonitrile, propionitrile, butyronitrile, etc.). These solvents should be selected based on their low reactivity; one or more can be used alone or in combination. Appropriate dehydrating agents or drying agents can be used to dry the solvent if necessary, and it can also be used as a non-aqueous solvent.

[0105] There is no particular limitation on the amount of solvent used (reaction concentration), but for the dinitro compound Cpd.2, it is 0.1 to 100 times by mass. Preferably, it is 0.5 to 30 times by mass, and more preferably 1 to 10 times by mass.

[0106] The reaction temperature is not particularly limited, but is preferably in the range of -100°C to the boiling point of the solvent used, and more preferably -50 to 150°C. The reaction time is usually 0.05 to 350 hours, preferably 0.5 to 100 hours.

[0107] On the other hand, there are no particular limitations on the synthesis method of the dinitro compound Cpd.2, and it can be synthesized by any method. As a specific example, the dinitro compound Cpd.3 is reacted with di-tert-butyl dicarbonate in a solvent in the presence of a base as desired.

[0108]

[0109] For the carboxyl equivalent of the dinitro compound Cpd.3, it is preferable to use 1 to 5 equivalents, and more preferably 1.3 to 2.5 equivalents of ditert-butyl dicarbonate. By setting the reaction conditions such as the equivalent number, the number of Boc groups introduced can be controlled.

[0110] The presence of a base in the reaction is not necessary, but when using a base, inorganic bases such as sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium bicarbonate, potassium bicarbonate, potassium phosphate, sodium carbonate, potassium carbonate, lithium carbonate, and cesium carbonate can be used; amines such as trimethylamine, triethylamine, tripropylamine, triisopropylamine, tributylamine, diisopropylethylamine, pyridine, dimethylaminopyridine, imidazole, quinoline, and ceftriaxone can be used; and bases such as sodium hydride, potassium hydride, sodium tert-butoxy, and potassium tert-butoxy can be used.

[0111] For the solvent in this reaction, any solvent that does not react with the reactants can be used. This can be the same solvent described in the synthesis of diamine compound Cpd.1 from the dinitro compound Cpd.2, aprotic polar organic solvents, ethers, aliphatic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, lower fatty acid esters, etc. These solvents can be appropriately selected considering factors such as the likelihood of inducing reaction; one or more solvents can be used alone. If necessary, appropriate dehydrating agents or drying agents can be used to dry the solvent, making it a non-aqueous solvent.

[0112] The amount of solvent used is not particularly limited; for the dinitro compound Cpd.3, 0.1 to 100 times the mass of the solvent can be used. Preferably, it is 0.5 to 30 times the mass, more preferably 1 to 10 times the mass. The reaction temperature is not particularly limited; it can be used in the range from -100°C to the boiling point of the solvent used, preferably in the range of -50 to 150°C. The reaction time is typically 0.05 to 200 hours, preferably 0.5 to 100 hours.

[0113] [Diamine compound (b2)]

[0114] The diamine compound (b2) has the structure shown in the following formula (b-2):

[0115]

[0116] In equation (b-2), Ar represents the aromatic ring, and X... 11 X represents an alkylene group having 1 to 5 carbon atoms. 12 It represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

[0117] Ar is the site used to place the aromatic amine moiety on a diamine having a secondary amine at the polymerization reaction site; therefore, it is not particularly limited as long as it is an aromatic ring. From the viewpoints of raw material availability, ease of synthesis, and liquid crystal orientation, Ar is preferably phenylene or naphthyl, and from the viewpoint of general applicability, phenylene is preferred. When Ar is phenylene, i.e., when H2N-Ar is aminobenzene, X 11 The replacement position should preferably be intermediate or anti-intermediate.

[0118] X 11 Indicates an alkylene group having 1 to 5 carbon atoms. X 11 Within this carbon number range, it can be either branched or cyclic, preferably a straight chain, and particularly preferably an alkylene group with 1 or 2 carbon atoms.

[0119] X 12 The group represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. The alkyl group can be straight-chain or branched. Preferably, the group is as small as possible, and particularly preferably a hydrogen atom, methyl, or ethyl group.

[0120] Specific examples of diamine compounds (b2) having the structure shown in formula (b-2) can be listed as compounds shown in formulas (b-2-1) to (b-2-12).

[0121]

[0122] Diamine compounds (b2) can be used alone or in combination.

[0123] The total amount of diamine component (b) used is 100 moles, and the amount of diamine compound (b2) used is from 1 mole to 99.5 moles, preferably from 2 moles to 80 moles, and more preferably from 3 moles to 70 moles.

[0124] If the diamine component (b) contains a diamine compound (b2), the flicker after driving of the formed liquid crystal display element can be further reduced.

[0125] [Other diamine compounds (b3)]

[0126] Other diamine compounds (b3) include (1) aliphatic diamine compounds, (2) alicyclic diamine compounds, (3) aromatic diamine compounds, (4) diamine compounds represented by formulas (b-3-1) to (b-3-29), or combinations thereof.

[0127] (1) Specific examples of aliphatic diamine compounds 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, and 1,3-diamino-2,2-dimethyl Propane, 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, or combinations thereof.

[0128] (2) Specific examples of alicyclic diamine compounds include, but are not limited to, 4,4'-diaminodicyclohexylmethane, 4,4'-diamino-3,3'-dimethyldicyclohexylamine, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, isophorone diamine, tetrahydrodicyclopentadiene diamine, and tricyclic [6.2.1.0] 2,7 ]-Undecenedimethyldiamine, 4,4'-methylenebis(cyclohexylamine), or a combination of the above compounds.

[0129] (3) Specific examples of aromatic diamine compounds include, but are not limited to, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylethane, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminobenzoylaniline, 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-methylhydroindenedimethyldiamine, 3,3'-diaminobenzophenone, and 3,4'-diamine. Benzyl ketone, 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)benzene, 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- Anthracene hydroanthracene, 9,10-bis(4-aminophenyl)anthracene, 2,7-diaminophen, 9,9-bis(4-aminophenyl)anthracene, 4,4'-methylene-bis(2-chloroaniline), 4,4'-(p-phenylene isopropyl)bisaniline, 4,4'-(m-phenylene isopropyl)bisaniline, 2,2'-bis[4-(4-amino-2-trifluoromethylphenoxy)phenyl]hexafluoropropane, 4,4'-bis[(4-amino-2-trifluoromethyl)phenoxy]octafluorobiphenyl, 5-[4-(4-n-pentanyl)-[ ... [alkylcyclohexyl]phenyl-methylene-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 combinations thereof.

[0130] (4) The diamine compounds represented by formulas (b-3-1) to (b-3-29) are shown below.

[0131]

[0132] In equation (b-3-1), B 1 express or B 2 This indicates a group having a steroid (cholesterol) skeleton, a trifluoromethyl group, a fluoro group, an alkyl group having 2 to 30 carbon atoms, or a monovalent group derived from a nitrogen-containing cyclic structure such as pyridine, pyrimidine, triazine, piperidine, or piperazine.

[0133] Specific examples of compounds represented by formula (b-3-1) include, but are not limited to, ethyl 2,4-diaminophenyl formate, ethyl 3,5-diaminophenyl formate, propyl 2,4-diaminophenyl formate, propyl 3,5-diaminophenyl formate, 1-dodecoxy-2,4-diaminobenzene, 1-hexadecoxy-2,4-diaminobenzene, 1-octadecoxy-2,4-diaminobenzene, at least one of the compounds represented by formulas (b-3-1-1) to (b-3-1-6), or combinations of the above compounds.

[0134] The compounds represented by formulas (b-3-1-1) to (b-3-1-6) are shown below.

[0135]

[0136]

[0137] In equation (b-3-2), B 1 With B in equation (b-3-1) 1 Same, B 3 and B 4 Each can independently represent a divalent aliphatic ring, a divalent aromatic ring, or a divalent heterocyclic group; B 5 It refers to 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.

[0138] Specific examples of compounds represented by formula (b-3-2) include at least one of the compounds represented by formulas (b-3-2-1) to (b-3-2-13).

[0139]

[0140]

[0141] In equations (b-3-2-1) to (b-3-2-13), s represents an integer from 3 to 12.

[0142]

[0143] In equation (b-3-3), B 6 Each of the repeating units independently 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 atom, and each repeating unit contains a B. 6 They can be the same or different; u represents an integer from 1 to 3.

[0144] Specific examples of compounds represented by formula (b-3-3) include, when u is 1: p-diaminebenzene, m-diaminebenzene, o-diaminebenzene, or 2,5-diaminotoluene, etc.; when u 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, 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.; or when u is 3: 1,4-bis(4'-aminophenyl)benzene, etc.

[0145] Specific examples of compounds represented by formula (b-3-3) are preferably p-diaminobenzene, 2,5-diaminotoluene, 4,4'-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 1,4-bis(4'-aminophenyl)benzene, or combinations thereof.

[0146]

[0147] In formula (b-3-4), w represents an integer from 1 to 5. The compound represented by formula (b-3-4) is preferably 4,4'-diamino-diphenyl sulfide.

[0148]

[0149] In equation (b-3-5), B 7 and B 9 Each independently represents a divalent organic group, and B 7 and B 9 They can be the same or different; B 8It represents a divalent group derived from a nitrogen-containing cyclic structure such as pyridine, pyrimidine, triazine, piperidine, or piperazine.

[0150]

[0151] In equation (b-3-6), B 10 B 11 B 12 and B 13 Each can be independently represented by a hydrocarbon group having 1 to 12 carbon atoms, and B 10 B 11 B 12 and B 13 They can be the same or different; X1 independently represents integers from 1 to 3; X2 represents integers from 1 to 20.

[0152]

[0153] In equation (b-3-7), B 14 Indicates an oxygen atom or a cyclohexylene group; B 15 B represents methylene (-CH2-); 16 Indicates phenylene or cyclohexene; B 17 It represents a hydrogen atom or a heptyl group.

[0154] Specific examples of compounds represented by formula (b-3-7) include compounds represented by formula (b-3-7-1), compounds represented by formula (b-3-7-2), or combinations thereof.

[0155]

[0156] The compounds represented by formulas (b-3-8) to (b-3-29) are shown below.

[0157]

[0158]

[0159]

[0160]

[0161] In equations (b-3-16) to (b-3-24), B 18 Preferably, it represents an alkyl group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms; B 19 Preferably, it represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms.

[0162] Other diamine compounds (b3) can be used alone or in combination.

[0163] Specific examples of other diamine compounds (b3) are preferably including, but 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, and 1,1-bis[4-(4-aminophenoxy]... Compounds represented by [phenyl]-4-(4-ethylphenyl)cyclohexane, ethyl 2,4-diaminophenylformate, p-diaminebenzene, m-diaminebenzene, o-diaminebenzene, formula (b-3-1-1), formula (b-3-1-2), formula (b-3-1-5), formula (b-3-2-1), formula (b-3-2-11), formula (b-3-7-1), formula (b-3-25), or formula (b-3-28).

[0164] The total amount of diamine component (b) used is 100 moles, and the amount of other diamine compound (b3) used is from 0 moles to 98.5 moles, preferably from 0 moles to 97.5 moles, and more preferably from 0 moles to 96.5 moles.

[0165] [Method for preparing polymer (A)]

[0166] Polymer (A) may include at least one of polyamic acid and polyimide. Additionally, polymer (A) may also include a polyimide-based block copolymer. The preparation methods of the various polymers described above are further explained below.

[0167] [Methods for preparing polyamic acid]

[0168] The method for preparing polyamic acid involves first dissolving a mixture comprising a tetracarboxylic dianhydride component (a) and a diamine component (b) in a solvent, and then carrying out a polycondensation reaction at a temperature of 0°C to 100°C. After reacting for 1 to 24 hours, the reaction solution is distilled under reduced pressure using an evaporator to obtain polyamic acid. Alternatively, the reaction solution can be poured into a large amount of lean solvent to obtain a precipitate. The precipitate is then dried under reduced pressure to obtain polyamic acid.

[0169] 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 are no particular limitations on the solvent used in the polycondensation reaction, as long as it can dissolve the reactants and products. The solvent is preferably including, but not limited to, (1) aprotic polar solvents, such as: N-methyl-2-pyrrolidinone (NMP), N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, tetramethylurea or hexamethylphosphonic triamine, etc.; or (2) phenolic solvents, such as: m-cresol, xylenol, phenol or halogenated phenols, etc. Based on a total amount of 100 parts by weight of the mixture, the amount of solvent used in the polycondensation reaction is preferably 200 parts by weight to 2000 parts by weight, and more preferably 300 parts by weight to 1800 parts by weight.

[0170] It is worth noting that in the polycondensation reaction, a suitable amount of lean solvent can be used in combination, where the lean solvent will not cause polyamic acid precipitation. The lean solvent can be used alone or in combination, 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, etc.; (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 halogenated hydrocarbons such as dichloromethane, 1,2-dichloroethane, 1,4-dichlorobutane, trichloroethane, chlorobenzene, or o-dichlorobenzene; or (6) hydrocarbons, such as hydrocarbons such as tetrahydrofuran, hexane, heptane, octane, benzene, toluene, or xylene, or any combination of the above solvents. Based on the amount of diamine component (a2) used being 100 parts by weight, the amount of lean solvent used is preferably 0 to 60 parts by weight, and more preferably 0 to 50 parts by weight.

[0171] [Methods for preparing polyimide]

[0172] The method for preparing polyimide involves heating the polyamic acid prepared by the above-described method in the presence of a dehydrating agent and a catalyst. During the heating process, the amic acid functional groups in the polyamic acid can be converted into imide functional groups via a dehydration and ring-closing reaction (i.e., imidization).

[0173] The solvent used in the dehydration and ring-closing reaction can be the same as the solvent (B) in the liquid crystal alignment agent, so it will not be described again here. Based on the amount of polyamic acid used being 100 parts by weight, the amount of solvent used in the dehydration and ring-closing reaction is preferably 200 to 2000 parts by weight, and more preferably 300 to 1800 parts by weight.

[0174] To obtain a preferred degree of imidization of the polyamic acid, the operating temperature of the dehydration ring-closure reaction is preferably 40°C to 200°C, more preferably 40°C to 150°C. If the operating temperature of the dehydration ring-closure reaction is below 40°C, the imidization reaction is incomplete, thus reducing the degree of imidization of the polyamic acid. However, if the operating temperature of the dehydration ring-closure reaction is above 200°C, the weight average molecular weight of the resulting polyimide is lower.

[0175] The dehydrating agent used in the dehydration ring-closing reaction can be selected from acid anhydride compounds, specifically, acid anhydride compounds such as acetic anhydride, propionic anhydride, or trifluoroacetic anhydride. Based on 1 mole of polyamic acid, the amount of 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; and (2) tertiary amine compounds, such as triethylamine. Based on 1 mole of dehydrating agent used, the amount of catalyst used can be 0.5 mole to 10 moles.

[0176] [Method for preparing polyimide block copolymers]

[0177] The polyimide-based block copolymer is selected from polyamic acid block copolymers, polyimide block copolymers, polyamic acid-polyimide block copolymers, or any combination of the above polymers.

[0178] The preferred method for preparing polyimide-based block copolymers is to first dissolve the starting material in a solvent and then carry out a polycondensation reaction, wherein the starting material includes at least one polyamic acid and / or at least one polyimide, and may further include a carboxylic anhydride component and a diamine component.

[0179] The carboxylic anhydride and diamine components in the starting material can be the same as the tetracarboxylic dianhydride (a) and diamine (b) components used in the method for preparing polyamic acid, and the solvent used in the polycondensation reaction can be the same as the solvent (B) in the liquid crystal alignment agent described below, which will not be elaborated here.

[0180] Based on the amount of starting material used being 100 parts by weight, the amount of solvent used in the polycondensation reaction is preferably from 200 parts by weight to 2000 parts by weight, and more preferably from 300 parts by weight to 1800 parts by weight. The operating temperature of the polycondensation reaction is preferably from 0°C to 200°C, and more preferably from 0°C to 100°C.

[0181] The starting materials are preferably including, but not limited to: (1) two polyamic acids with different terminal groups and different structures; (2) two polyimides with different terminal groups and different structures; (3) polyamic acid and polyimide with different terminal groups and different structures; (4) polyamic acid, a carboxylic anhydride component, and a diamine component, wherein at least one of the carboxylic anhydride component and the diamine component has a different structure from the carboxylic anhydride component and the diamine component used to form the polyamic acid; (5) polyimide, a carboxylic anhydride component, and a diamine component, wherein at least one of the carboxylic anhydride component and the diamine component has a different structure from the carboxylic anhydride component and the diamine component used to form the polyimide; (6) polyamic acid, polyimide, a carboxylic anhydride component, and (7) Two structurally different polyamic acid, carboxylic anhydride and diamine components; (8) Two structurally different polyimide, carboxylic anhydride and diamine components; (9) Two structurally different polyamic acid and diamine components with an anhydride end group; (10) Two structurally different polyamic acid and carboxylic anhydride end group; (11) Two structurally different polyimide and diamine components with an anhydride end group; or (12) Two structurally different polyimide and carboxylic anhydride end group.

[0182] Within the scope of not affecting the efficacy of the present invention, polyamic acid, polyimide, and polyimide-based block copolymers are preferably end-modified polymers after prior molecular weight adjustment. Using end-modified polymers can improve the coating performance of liquid crystal alignment agents. End-modified polymers can be prepared by adding a monofunctional compound during the polycondensation reaction of polyamic acid.

[0183] Specific examples of monofunctional compounds include, but are not limited to, (1) monocarboxylic anhydrides, such as maleic anhydride, phthalic anhydride, itaconic anhydride, n-decyl succinic anhydride, n-dodecyl succinic anhydride, n-tetradecyl succinic anhydride or n-hexadecyl succinic 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-pentadecanylamine, n-hexadecylamine, n-heptadecylamine, n-octadecylamine or n-eicosylamine; or (3) monoisocyanate compounds, such as phenyl isocyanate or naphthyl isocyanate.

[0184] The polymer (A) of the present invention, as determined by gel permeation chromatography (GPC), has a weight-average molecular weight converted from polystyrene of 10,000 to 90,000, preferably 12,000 to 75,000, and more preferably 15,000 to 60,000.

[0185] [Solvent (B)]

[0186] The solvent (B) 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 without reacting with them. Preferably, it is the same solvent used in the synthesis of polyamic acid as described above. At the same time, the lean solvent used in the synthesis of polyamic acid as described above can also be used.

[0187] Specific examples of 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.

[0188] Solvent (B) can be used alone or in combination.

[0189] The amount of polymer (A) used is 100 parts by weight, and 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.

[0190] [Additive (C)]

[0191] Without affecting the effectiveness of the present invention, the liquid crystal alignment agent of the present invention may selectively include an additive (C), and the additive (C) may be an epoxy compound or a silane compound having functional groups, etc. The function of the additive (C) is to improve the adhesion of the aforementioned liquid crystal alignment film to the substrate surface. The additive (C) may be used alone or in combination.

[0192] The aforementioned epoxy compounds may include, but are 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-dibromonepentyl glycol diglycidyl ether, 1,3,5,6-tetracyclooxypropyl-2,4-hexanediol, N,N N',N'-Tetracyclooxypropyl-m-xylenediamine, 1,3-bis(N,N-dicyclooxypropylaminomethyl)cyclohexane, N,N,N',N'-tetracyclooxypropyl-4,4'-diaminodiphenylmethane, N,N-epoxypropyl-p-epoxypropoxyaniline, 3-(N-allyl-N-epoxypropyl)aminopropyltrimethoxysilane, 3-(N,N-dicyclooxypropyl)aminopropyltrimethoxysilane, etc.

[0193] Based on the amount of polymer (A) used being 100 parts by weight, the amount of epoxy compound used is generally less than 40 parts by weight, and preferably from 0.1 parts by weight to 30 parts by weight.

[0194] The aforementioned silane compounds with functional groups may include, but are 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, and N-triethoxysilyl Propyltriethylenetriamine, N-trimethoxysilylpropyltriethylenetriamine, 10-trimethoxysilyl-1,4,7-triacryldecane, 10-triethoxysilyl-1,4,7-triacryldecane, 9-trimethoxysilyl-3,6-diacrylnonyl acetate, 9-triethoxysilyl-3,6-diacrylnonyl 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.

[0195] Based on the amount of polymer (A) used being 100 parts by weight, the amount of silane compound used is generally less than 10 parts by weight, and preferably from 0.5 parts by weight to 10 parts by weight.

[0196] Based on the amount of polymer (A) used being 100 parts by weight, the amount of additive (C) used can be from 0.5 parts by weight to 50 parts by weight, and preferably from 1 part by weight to 45 parts by weight.

[0197] <Method for manufacturing liquid crystal alignment agent>

[0198] The manufacturing 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) uniformly to react and form a polymer (A). Then, the polymer (A) is added to the solvent (B) and 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 additive (C) are added to the solvent (B) at a temperature of 20°C to 60°C.

[0199] <Manufacturing Method of Liquid Crystal Alignment Film>

[0200] The liquid crystal alignment film of the present invention is a film obtained by coating the liquid crystal alignment agent formed above onto a substrate and then drying and baking it.

[0201] The substrate coated with the liquid crystal alignment agent of the present invention is selected from transparent materials. These transparent materials include, but are not limited to, alkali-free glass, soda-lime glass, hard glass (Pellegrino glass), quartz glass, polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, polycarbonate, etc., used in liquid crystal display devices. Preferably, the substrate can be a substrate on which ITO electrodes for liquid crystal driving are already formed, thus simplifying the manufacturing process. Furthermore, for reflective liquid crystal displays with only a single-sided substrate, the aforementioned substrate can be an opaque material such as a silicon wafer. In this case, the electrodes can be formed using a light-reflecting material such as aluminum. The coating method for the liquid crystal alignment agent of the present invention can be, for example, spin coating, printing, inkjet printing, etc.

[0202] The liquid crystal alignment agent of this invention can be applied at any temperature and for any time for drying and baking processes. Generally, to fully remove the contained organic solvents, drying at 50°C to 120°C for 1 to 10 minutes is required. Afterward, baking at 150°C to 300°C for 5 to 120 minutes is performed. There is no particular limitation on the thickness of the coating after baking, but an excessively thin coating can degrade the reliability of the liquid crystal display; therefore, a coating thickness of 5 nm to 300 nm is preferable, and 10 nm to 200 nm is even more preferred.

[0203] While the liquid crystal alignment agent of the present invention can be subjected to known rubbing alignment treatment, it is more effective when using photoalignment treatment.

[0204] Specific examples of the photo-alignment treatment method include: irradiating the surface of the aforementioned coating film with radiation polarized in a specific direction, and then subjecting it to heat treatment at a temperature of 150°C to 250°C, as appropriate, to impart liquid crystal alignment energy to the coating film. Ultraviolet or visible light with wavelengths from 100 nm to 800 nm can be used as the radiation, with ultraviolet light with wavelengths from 100 nm to 400 nm being preferred, and wavelengths from 200 nm to 400 nm being more preferred. Furthermore, to improve liquid crystal alignment, the coating substrate can be heated at 50°C to 250°C while simultaneously irradiating it with radiation. The preferred irradiation dose of the aforementioned radiation is 1 mJ / cm². 2 Up to 10,000 mJ / cm 2 And with 100mJ / cm 2 Up to 5,000 mJ / cm 2 Even better. The liquid crystal alignment film prepared in the above manner can stably align liquid crystal molecules in a certain direction.

[0205] The liquid crystal alignment agent of the present invention is subjected to pre-baking treatment, post-baking treatment and photo-alignment treatment to form a liquid crystal alignment film, wherein the pretilt angle of the liquid crystal alignment film is 0° to 3°.

[0206] <Manufacturing Method of Liquid Crystal Display Components>

[0207] The present invention also provides a liquid crystal display element comprising the aforementioned liquid crystal alignment film.

[0208] The manufacturing method of liquid crystal display elements is well known to those skilled in the art, therefore, it will only be briefly described below.

[0209] See 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.

[0210] 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 pectin patterned manner, and the first liquid crystal alignment film 116 is formed on the surface of the electrode 114.

[0211] 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 the surface of the second substrate 122.

[0212] The first substrate 112 and the second substrate 122 are selected from transparent materials, including but 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 electrode 114 is made of transparent electrodes such as tin oxide (SnO2) and indium oxide-tin oxide (In2O3-SnO2); or metal electrodes such as chromium.

[0213] The first liquid crystal alignment film 116 and the second liquid crystal alignment film 126 are the liquid crystal alignment films mentioned above. Their function is to enable the liquid crystal cell 130 to form a pretilt angle, and the liquid crystal cell 130 can be driven by the parallel electric field generated by the electrode 114.

[0214] The liquid crystal used in the liquid crystal unit 130 can be used alone or in combination. The liquid crystals include, but are not limited to, diaminobenzene-based liquid crystals, pyridazine-based liquid crystals, Schiff base-based liquid crystals, azooxy-based liquid crystals, biphenyl-based liquid crystals, phenylcyclohexane-based liquid crystals, biphenyl-based liquid crystals, ester-based liquid crystals, terphenyl-based liquid crystals, biphenylcyclohexane-based liquid crystals, pyrimidine-based liquid crystals, dioxane-based liquid crystals, bicyclooctane-based liquid crystals, and cubane-based liquid crystals. Furthermore, depending on requirements, additional substances such as cholesterol chloride, cholesterol nonanoate, and cholesterol carbonate can be added. Cholesterol-type liquid crystals such as carbonate, or chiral agents with trade names such as "C-15" or "CB-15" (manufactured by Merck), or ferroelectric liquid crystals such as p-decoxybenzyl methylene-p-amino-2-methylbutyl cinnamate.

[0215] The liquid crystal alignment agent of this invention is suitable for liquid crystal display elements made of various nematic liquid crystals, such as TN, STN, TFT, VA, and IPS liquid crystal display elements. Furthermore, depending on the selected liquid crystal, it can also be used for liquid crystal display elements with strong or negative strong conductivity. Among the aforementioned liquid crystal display elements, it is particularly suitable for IPS-type liquid crystal display elements.

[0216] The present invention will be further described with reference to the following embodiments, but it should be understood that these embodiments are merely illustrative and should not be construed as limiting the implementation of the present invention.

[0217] <Example>

[0218] [Example of polymer (A) synthesis]

[0219] The following is an example of the synthesis of polymer (A):

[0220] Synthesis Example A-1-1

[0221] A nitrogen inlet, stirrer, condenser, and thermometer were installed on a 500 mL four-necked conical flask, and nitrogen gas was introduced. Then, 0.096 g (0.00025 mol) of the diamine compound of formula (b-1-1) (hereinafter referred to as b-1-1), 6.078 g (0.04975 mol) of the diamine compound of formula (b-2-1) (hereinafter referred to as b-2-1), and 80 g of N-methyl-2-pyrrolidone (hereinafter referred to as NMP) were added, and the mixture was stirred at room temperature until dissolved. Next, 1.12 g (0.005 mol) of the tetracarboxylic dianhydride compound of formula (a-1-1) (hereinafter referred to as a-1-1), 9.815 g (0.045 mol) of benzo[a]pyrro ... 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 steps were repeated three times with methanol. Then, 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 formulation of which is shown in Table 1.

[0222] Synthetic Examples A-1-2 to A-1-15 and Comparative Synthetic Examples A'-1-1 to A'-1-3

[0223] Synthetic Examples A-1-2 to A-1-15 and Comparative Synthetic Examples A'-1-1 to A'-1-3 used the same preparation method as the polymer (A-1-1) of Synthetic Example A-1-1. The difference was that the types and amounts of raw materials in the polymer were changed in Synthetic Examples A-1-2 to A-1-15 and Comparative Synthetic Examples A'-1-1 to A'-1-3. Their formulations are shown in Tables 1 and 2, and will not be described again here.

[0224] Synthesis Example A-2-1

[0225] A nitrogen inlet, stirrer, condenser, and thermometer were installed on a 500 mL four-necked conical flask, and nitrogen gas was introduced. Then, 0.096 g (0.00025 mol) of the diamine compound of formula (b-1-1) (hereinafter referred to as b-1-1), 6.078 g (0.04975 mol) of the diamine compound of formula (b-2-1) (hereinafter referred to as b-2-1), and 80 g of N-methyl-2-pyrrolidone (hereinafter referred to as NMP) were added, and the mixture was stirred at room temperature until dissolved. Next, 1.12 g (0.005 mol) of the tetracarboxylic dianhydride compound of formula (a-1-1) (hereinafter referred to as a-1-1), 9.815 g (0.045 mol) of benzo[a]pyrro ... 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 mixture was heated to 60 °C and stirred continuously for 2 hours to carry out the imidization reaction. After the reaction was completed, the reaction solution was poured into 1500 mL of water to allow the polymer to precipitate. The obtained polymer was then filtered, and the washing and filtration with methanol were repeated three times. The polymer was then placed in a vacuum oven and dried at 60 °C to obtain polymer (A-2-1), the formulation of which is shown in Table 2.

[0226] Synthetic Examples A-2-2 to A-2-5 and Comparative Synthetic Example A'-2-1

[0227] Synthetic Examples A-2-2 to A-2-5 and Comparative Synthetic Example A'-2-1 used the same preparation method as the polymer (A-2-1) of Synthetic Example A-2-1. The difference was that the types and amounts of raw materials in the polymer were changed in Synthetic Examples A-2-2 to A-2-5 and Comparative Synthetic Example A'-2-1. Their formulations are shown in Table 2 and will not be described again here.

[0228] In addition, the compounds corresponding to the abbreviations in Tables 1 and 2 are shown below.

[0229]

[0230]

[0231]

[0232]

[0233] [Table 1]

[0234]

[0235] [Table 2]

[0236]

[0237] [Examples of liquid crystal alignment agents, liquid crystal alignment films, and liquid crystal display elements]

[0238] Example 1

[0239] Weigh 100 parts by weight of the polymer obtained from Synthesis Example A-1-1 (hereinafter referred to as A-1-1) and 800 parts by weight of N-methyl-2-pyrrolidone (NMP, hereinafter referred to as B-1), and mix them at room temperature to obtain the liquid crystal alignment agent of Example 1.

[0240] The liquid crystal alignment agent prepared in Example 1 was spin-coated onto a glass substrate having pixel electrodes. The pixel electrodes were IPS driving electrodes with a pair of ITO electrodes (electrode width: 10 μm, electrode spacing: 10 μm, electrode height: 50 nm). The pair of ITO electrodes each had a serrated shape, and the serrated portions were arranged in a separated yet interlocking manner. The glass substrate coated with the liquid crystal alignment agent was then dried on a heating plate at 80°C for 5 minutes, followed by baking in a hot air circulating oven at 250°C for 60 minutes to form a coating with a thickness of 100 nm.

[0241] A substrate with a liquid crystal alignment film is prepared by irradiating the coated surface with ultraviolet light at a wavelength of 254 nm using a polarizing plate, and then baking the substrate at 230°C for 30 minutes. Next, a coating is formed on a counter substrate, which is a glass substrate without electrodes but with columnar spacers of 4 μm in height, and then subjected to an alignment treatment.

[0242] The two substrates are grouped together. A sealant is printed on one substrate, and the other substrate is bonded to the other substrate with the liquid crystal alignment film facing each other and the alignment direction at 0°. The sealant is then cured to obtain an empty cell. Subsequently, liquid crystal MLC-2041 (manufactured by Merck) is injected into the empty cell using a reduced pressure injection method, and the injection port is sealed to obtain the liquid crystal display element of Example 1.

[0243] Examples 2 to 20 and Comparative Examples 1 to 4

[0244] Examples 2 to 20 and Comparative Examples 1 to 4 were manufactured using the same method as the liquid crystal alignment agent, liquid crystal alignment film and liquid crystal display element of Example 1. The difference was that the types and amounts of raw materials in the liquid crystal alignment agent were changed. The formulations and evaluation results are shown in Tables 3 and 4, respectively, and will not be described again here.

[0245] In addition, the compounds corresponding to the abbreviations in Tables 3 and 4 are shown below.

[0246]

[0247] [Table 3]

[0248]

[0249] [Table 4]

[0250]

[0251] [Evaluation Method]

[0252] [Flickering intensity after driver activation]

[0253] The fabricated liquid crystal display element was placed between two polarizing plates arranged perpendicularly to each other. The LED backlight was lit without any applied voltage, and the arrangement angle of the liquid crystal display element was adjusted to minimize the brightness of the transmitted light. Next, an AC voltage of 30Hz was applied to the liquid crystal display element, and the VT curve (voltage-transmittance curve) was simultaneously measured. The AC voltage with a relative transmittance of 23% was calculated and used as the driving voltage.

[0254] The method for measuring flicker after driving is as follows: Under the condition that the temperature of the liquid crystal display element is 23°C, the illuminated LED backlight is turned off, and after 72 hours of light-shielding, it is turned on again. Simultaneously with the start of backlight illumination, an AC voltage of 30Hz with a relative transmittance of 23% is applied to drive the liquid crystal display element for 60 minutes, and the flicker amplitude is tracked. The flicker amplitude is measured using a data acquisition / data recording switching device 34970A (manufactured by Agilent Technologies) connected to a photodiode and an IV converter, reading the brightness value passing through two polarizing plates and the liquid crystal display element between them. Flicker (FL) is calculated according to the following formula (III). A lower flicker indicates a better quality liquid crystal display element made with the liquid crystal alignment agent.

[0255]

[0256] In equation (III), z is the brightness value read when the device 34970A described above is driven by an AC voltage of 30 Hz at a frequency of 23% relative transmittance.

[0257] ◎: FL < 3%

[0258] ○: 4% > FL ≥ 3%

[0259] Δ: 5% > FL ≥ 4%

[0260] X: FL ≥ 5%.

[0261] [Evaluation Results]

[0262] As shown in Tables 3 and 4, compared with liquid crystal display elements (Examples 1 to 20) made of liquid crystal alignment agents containing polymer (A) having the structure shown in Formula (I), liquid crystal display elements of Comparative Examples 1-4 that do not contain polymer (A) having the structure shown in Formula (I) have the problem of poor instantaneous flicker.

[0263] Furthermore, when the diamine component (b) in polymer (A) contains 0.5 mol% to 50 mol% of diamine compound (b1) (Examples 1, 3-14, 16-20), the post-drive flicker of the formed liquid crystal display element can be further reduced.

[0264] Furthermore, when the diamine component (b) in polymer (A) contains more diamine compound (b2) (Examples 1, 3-6, 11-14, 16, 17, 19), the post-drive flicker of the formed liquid crystal display element can be further reduced.

[0265] In summary, the liquid crystal alignment agent of the present invention uses a polymer (A) with a specific structure, and therefore, the liquid crystal alignment agent can improve the technical problem of poor instantaneous flicker in the prior art.

[0266] Furthermore, when the diamine component (b) in polymer (A) contains a specific amount of diamine compound (b1) or diamine compound (b2), the flicker after driving of the formed liquid crystal display element can be further reduced.

[0267] 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 comprising: a polymer (A); and a solvent (B), the polymer (A) is produced by a polymerization reaction from a mixture comprising a tetracarboxylic dianhydride component (a) and a diamine component (b), and has a structure represented by the following formula (I):

2. The liquid crystal alignment agent according to claim 1, wherein Formula (I) In formula (I), Y 1 represents a group represented by the following formula (II), X 1 , X 2 each independently represents a divalent organic group, represents a bond, Formula (II) In formula (II), Y 2 represents a linear hydrocarbon group having 1 to 20 carbons, a branched hydrocarbon group having 3 to 20 carbons, or a cyclic hydrocarbon group having 3 to 20 carbons, represents a bond. the diamine component (b) comprises a diamine compound (bl) having a structure represented by the following formula (b-1):

3. The liquid crystal alignment agent according to claim 1, wherein Formula (b-1) In formula (b-1), Y 1 is Y in the formula (I) 1 , X 3 , X 4 each independently represents an alkylene group having 1 to 3 carbons, X 5 , X 6 each independently represents a single bond, -O-, -S-, -OCO-, or -COO-. the tetracarboxylic dianhydride component (a) comprises a tetracarboxylic dianhydride compound (al) having a structure represented by the following formula (a-1):

4. The liquid crystal alignment agent according to claim 1, wherein Formula (a-1) In formula (a-1), R 1 to R 4 each independently represents 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 monovalent organic group having a carbon number of 1 to 6 and containing a fluorine atom, or a phenyl group, R 1 to R 4 are the same or different, and R 1 , R 2 , R 3 , and R 4 are not a hydrogen atom. the diamine component (b) comprises a diamine compound (b2) having a structure represented by the following formula (b-2):

5. The liquid crystal alignment agent according to claim 3, wherein Equation (b-2) In formula (b-2), Ar represents an aromatic ring, X 11 represents an alkylene group having 1 to 5 carbons, X 12 represents a hydrogen atom or an alkyl group having 1 to 4 carbons. the amount of use of the tetracarboxylic dianhydride compound (al) is 10 to 100 moles based on 100 moles of the tetracarboxylic dianhydride component (a).

6. The liquid crystal alignment agent according to claim 1, wherein the amount of use of the diamine compound (bl) is 0.5 to 50 moles based on 100 moles of the diamine component (b).

7. The liquid crystal alignment agent according to claim 4, wherein the amount of use of the diamine compound (b2) is 1 to 99.5 moles based on 100 moles of the diamine component (b).

8. The liquid crystal alignment agent according to claim 1, wherein the amount of use of the solvent (B) is 800 to 4000 parts by weight based on 100 parts by weight of the polymer (A).

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

10. A liquid crystal display element comprising the liquid crystal alignment film according to claim 9. ​

Images