TWI808279B - Liquid crystal alignment agent, liquid crystal alignment film and liquid crystal display element - Google Patents

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 includes a polymer (A) and a solvent (B). The polymer (A) includes a first polymer (A1). The first polymer (A1) is manufactured by reacting a specific tetracarboxylic acid dianhydride component (a1) with a specific diamine component (b1). The liquid crystal alignment film is formed form the liquid crystal alignment agent, and the liquid crystal display element containing the liquid crystal alignment agent has good capability of eliminating accumulated charges after exposure to light.

Description

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

The invention relates to a liquid crystal alignment agent, a liquid crystal alignment film and a liquid crystal display element, in particular to a liquid crystal display element with good charge elimination and light resistance by using the liquid crystal alignment agent.

For liquid crystal display elements used in liquid crystal televisions, liquid crystal displays, etc., a liquid crystal alignment film for controlling the alignment state of liquid crystals is usually provided inside the element. At present, the most common method in the industry is to rub cotton, nylon, polyester and other cloth materials along one direction on the surface of the film formed by polyamic acid and/or imidized polyimide on the electrode substrate, and perform so-called rubbing treatment to prepare the liquid crystal alignment film.

During the alignment process of the liquid crystal alignment film, rubbing the surface of the film is a method that is relatively easy to produce in industry. However, as the requirements for high performance, high precision, and large-scale liquid crystal display elements are getting higher and higher, when the rubbing process is performed, damage to the surface of the alignment film, flying dust, influences due to mechanical and electrostatic forces, and unevenness on the alignment surface, etc. The problem becomes more pronounced.

As a method instead of the rubbing treatment, there is known a photo-alignment method in which alignment energy is imparted to liquid crystals by irradiation of polarized ultraviolet rays. The so-called liquid crystal alignment treatment of the photo-alignment method refers to substances that utilize photoisomerization reactions, substances that utilize photocrosslinking reactions, substances that utilize photodecomposition reactions, etc. in terms of reaction mechanism. Furthermore, JP-A-9-297313 proposes to use a polyimide film having an alicyclic structure such as cyclobutane in the main chain in the photo-alignment method. When polyimide is used as an alignment film for photo-alignment, the heat resistance of this alignment film is higher than other types of alignment films, so the applicability of this alignment film is optimistic.

The optical alignment method is a method without rubbing alignment treatment, which not only has the advantage of being able to be manufactured with a simple manufacturing process in industry, but is expected to improve the contrast and viewing angle characteristics of the liquid crystal display element when using the liquid crystal alignment film obtained by the above-mentioned optical alignment method compared with the liquid crystal alignment film obtained by the rubbing method in the drive mode of the transverse electric field effect technology (In-Plane-Switching: IPS) and the drive mode of the fringe field switching wide-viewing angle technology (Fringe Field Switching: FFS). , so the photo-alignment method is a promising liquid crystal alignment treatment method that has attracted much attention.

However, when the liquid crystal alignment film prepared by the photo-alignment method is applied to a liquid crystal display device, there is still the problem of poor charge elimination and light resistance, that is, the accumulated charge of the liquid crystal display device manufactured after the liquid crystal alignment film is illuminated by light is eliminated slowly, resulting in excessive residual charge, and then the problem of image sticking. It can be seen from the above that in order to meet the requirements of the current photo-alignment IPS liquid crystal display industry, a liquid crystal display element capable of forming charge elimination and light fastness is provided. Crystal alignment agents are the goal of research by those skilled in the art.

One aspect of the present invention is to provide a liquid crystal alignment agent, which includes a polymer (A) and a solvent (B).

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.

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

Liquid crystal alignment agent

Polymer (A)

The polymer (A) of the present invention comprises a first polymer (A1), and the first polymer (A1) is prepared by reacting a tetracarboxylic dianhydride component (a1) with a diamine component (b1). Furthermore, the polymer (A) may optionally contain a second polymer (A2).

Preferable specific examples of the aforementioned polymer (A1) are polyamic acid polymers, polyimide polymers, polyimide-based block copolymers, or combinations thereof. Among them, preferred specific examples of polyimide-based block copolymers are polyamic acid block copolymers, polyimide block copolymers, polyamic acid-polyimide block copolymers, or any combination thereof.

First polymer (A1)

Tetracarboxylic dianhydride component (a1)

Tetracarboxylic dianhydride compound (a1-1)

The tetracarboxylic dianhydride component (a1) of the present invention comprises at least one tetracarboxylic Carboxylic acid dianhydride compound (a1-1), which has a structure shown in the following formula (I):

In formula (I), R ₁ to R ₄ 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 containing fluorine atoms and having 1 to 6 carbon atoms, or a phenyl group, R ₁ to R ₄ may be the same or different, and at least one of R ₁ , R ₂ , R ₃ and R ₄ is not a hydrogen atom.

When R ₁ , R ₂ , R ₃ and R ₄ have a steric barrier structure, the liquid crystal alignment of the liquid crystal alignment agent will be poor. Therefore, R ₁ , R ₂ , R ₃ and R ₄ are preferably hydrogen atoms, methyl or ethyl, among which methyl is more preferred.

Specific examples of the tetracarboxylic dianhydride compound (a1-1) having the structure represented by formula (I) may be, for example, compounds represented by the following formula (I-1) to formula (I-8). For liquid crystal alignment, formula (I-1) is preferred.

The said tetracarboxylic dianhydride compound (a1-1) can be used individually by 1 type or in mixture of plural types.

Based on the total usage amount of the tetracarboxylic dianhydride component (a1) being 100 moles, the usage amount of the tetracarboxylic dianhydride compound (a1-1) is 20 moles to 100 moles, preferably 30 moles to 100 moles, and more preferably 40 moles to 100 moles.

If the tetracarboxylic dianhydride component (a1) does not contain the tetracarboxylic dianhydride compound (a1-1), the resulting liquid crystal display device has the defect of poor charge elimination and light resistance.

Other tetracarboxylic dianhydride compounds (a1-2)

The tetracarboxylic dianhydride component (a1) of the present invention may further contain other tetracarboxylic dianhydride compounds (a1-2). Other tetracarboxylic dianhydride compounds (a1-2) Preferred specific examples are (1) aliphatic tetracarboxylic dianhydride compounds, (2) alicyclic tetracarboxylic dianhydride compounds, (3) aromatic tetracarboxylic dianhydride compounds, or (4) tetracarboxylic dianhydride compounds represented by formulas (1-1) to (1-6).

The (1) aliphatic tetracarboxylic dianhydride compound of the present invention includes, but not limited to, aliphatic tetracarboxylic dianhydride compounds such as ethane tetracarboxylic dianhydride or butane tetracarboxylic dianhydride.

The (2) alicyclic tetracarboxylic dianhydride compound of the present invention includes but not limited to 1,2,3,4-cyclobutane tetracarboxylic dianhydride, 1,2-dimethyl-1,2,3,4-cyclobutane tetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutane tetracarboxylic dianhydride, 1,3-dichloro-1,2,3,4-cyclobutane tetracarboxylic dianhydride, 1,2,3,4-tetramethyl-1,2 ,3,4-cyclobutane tetracarboxylic dianhydride, 1,2,3,4-cyclopentane tetracarboxylic dianhydride, 1,2,4,5-cyclohexane tetracarboxylic dianhydride, 3,3',4,4'-dicyclohexyl tetracarboxylic dianhydride, cis-3,7-dibutylcycloheptyl-1,5-diene-1,2,5,6-tetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentyl acetic dianhydride or bicyclo[2 .2.2] Alicyclic tetracarboxylic dianhydride compounds such as -oct-7-ene-2,3,5,6-tetracarboxylic dianhydride.

Specific examples of (3) aromatic tetracarboxylic dianhydride compounds of the present invention may 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'-biphenylene 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)diphenylene dianhydride, 4,4'-bis(3,4-dicarboxyphenoxy)diphenylpropane dianhydride, 3,3',4,4'-perfluoroisopropylidene diphthalic 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'-diphenylether 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-tetrahydrofuran tetracarboxylic 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-dipentoxy-3-furyl)-naphtho[1,2-c]-furan-1,3-dione, 1,3,3a,4,5,9b-hexahydro-7-methyl-5-(tetrahydro-2,5-dipentoxy-3-furyl)-naphtho[1,2- c]-furan-1,3-dione, 1,3,3a,4,5,9b-hexahydro-7-ethyl-5-(tetrahydro-2,5-dipentoxy-3-furyl)-naphtho[1,2-c]-furan-1,3-dione, 1,3,3a,4,5,9b-hexahydro-8-methyl-5-(tetrahydro-2,5-dipentoxy-3-furyl)-naphtho[1, 2-c]-furan-1,3-dione, 1,3,3a,4,5,9b-hexahydro-8-ethyl-5-(tetrahydro-2,5-dioxo-3-furyl)-naphtho[1,2-c]-furan-1,3-dione, 1,3,3a,4,5,9b-hexahydro-5,8-dimethyl-5-(tetrahydro-2,5-dioxo-3-furyl)-naphtho[1,2-c]-furan-1,3-dione, 5-(2,5-dioxotetrahydrofuranyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic dianhydride, etc.

(4) according to the present invention has a tetracarboxylic dianhydride compound represented by formula (1-1) to formula (1-6), and is described in detail as follows.

In formula (1-5), A ₁ represents a divalent group containing an aromatic ring; r represents an integer from 1 to 2; A ₂ and A ₃ may be the same or different, and may represent a hydrogen atom or an alkyl group respectively. Preferably, the tetracarboxylic dianhydride compound shown in formula (1-5) can be selected from the compounds shown in formula (1-5-1) to formula (1-5-3).

In formula (1-6), A ₄ represents a divalent group containing an aromatic ring; A ₅ and A ₆ may be the same or different, and represent a hydrogen atom or an alkyl group respectively. Preferably, the tetracarboxylic dianhydride compound represented by the formula (1-6) can be selected from the compounds represented by the following formula (1-6-1).

The other tetracarboxylic dianhydride compound (a1-2) mentioned above can be used individually by 1 type or in mixture of plural types.

Based on the total usage of the tetracarboxylic dianhydride component (a1) being 100 moles, the usage of other tetracarboxylic dianhydride compounds (a1-2) is from 0 moles to 80 moles, preferably from 0 moles to 70 moles, and more preferably from 0 moles to 60 moles.

Based on 100 moles of the diamine component (b1), the usage amount of the tetracarboxylic dianhydride component (a1) ranges from 20 moles to 200 moles; preferably 30 moles to 120 moles.

Diamine component (b1)

Diamine compound (b1-1)

The diamine component (b1) of the present invention comprises at least one diamine compound (b1-1), which has the structure shown in the following formula (II):

In formula (II ₎ , X ₁ represents O, COO, OCO, CONH or NHCO; Ring X ₂ represents a benzene ring or cyclohexane;

Specifically, the above-mentioned diamine compound having the structure of formula (II) Compound (b1-1) can be, for example, compounds represented by the following formula (2-1) to formula (2-35):

The said diamine compound (b1-1) can be used individually by 1 type or in mixture of several types.

Based on the total usage amount of the diamine component (b1) being 100 moles, the usage amount of the diamine compound (b1-1) is 1 to 20 moles, preferably 1 to 15 moles, and more preferably 1 to 10 moles.

If the diamine component (b1) in the liquid crystal alignment agent does not use the diamine compound (b1-1), the formed liquid crystal display device will have poor charge elimination and light resistance.

In addition, if X ₃ in the formula (II) represents a branched chain alkyl group having 3 to 10 carbon atoms, the charge-eliminating light resistance of the formed liquid crystal display device can be further improved.

Other diamine compounds (b1-2)

The diamine component (b1) of the present invention may further contain other diamine compounds (b1-2).

Other diamine compounds (b1-2) 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, tricyclic (6.2. 1.02,7)-undecenedimethyldiamine, 4,4'-methylene bis(cyclohexylamine), 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylethane, 4,4'-diaminodiphenylene, 4,4'-diaminobenzamide, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 1,5-diaminonaphthalene, 5-amine 1-(4'-aminophenyl)-1,3,3-trimethylhydroindene, 6-amino-1-(4'-aminophenyl)-1,3,3-trimethylhydroindene, hexahydro-4,7-methyleneindenyl dimethylenediamine, 3,3'-diaminobenzophenone, 3,4'-diaminobenzophenone, 4,4'-diaminobenzophenone, 2,2-bis[4-(4-aminophenyl oxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2-bis(4-aminophenoxy)hexafluoropropane, 2,2-bis[4-(4-aminophenoxy)phenyl]pyridine, 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-hydroanthracene, 9,10-bis(4-aminophenyl)anthracene [9,10-bis(4-aminophenyl)anthracene], 2,7-diaminophenylene, 9,9-bis(4-aminophenyl) fluorine, 4,4'-methylene-bis(2-chloro Aniline), 4,4'-(p-phenyleneisopropylidene)bisaniline, 4,4'-(m-phenyleneisopropylidene)bisaniline, 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 others shown in the following formula (3-1) to formula (3-29) diamine compound.

、

、

、

或

，且Z₂代表含甾基團、三氟甲基、氟基、碳數為2至30之烷基或衍生自吡啶、嘧啶、三嗪、哌啶及哌嗪等含氮原子環狀結構的一價基團。 In formula (3-1), Z ₁ represents -O-,

,

,

,

or

, and _Z represents a sterol-containing group, a trifluoromethyl group, a fluoro group, an alkyl group with a carbon number of 2 to 30, or a monovalent group derived from a nitrogen-atom-containing ring structure such as pyridine, pyrimidine, triazine, piperidine, and piperazine.

Other diamine compounds represented by the above formula (3-1) are preferably 2,4-diaminophenyl ethyl formate (2,4-diaminophenyl ethyl formate), 3,5-diaminophenyl ethyl formate (3,5-diaminophenyl ethyl formate), 2,4-diaminophenyl propyl formate (2,4-diaminophenyl propyl formate), 3,5-diaminophenyl formic acid propyl formate (3, or (3-1-1) to Other diamine compounds represented by formula (3-1-6).

、

、

、

或

，Z₄及Z₅代表伸脂肪族環、伸芳香族環或伸雜環基團，且Z₆代表碳數為3至18之烷基、碳數為3至18之烷氧基、碳數為1至5之氟烷基、碳數為1至5之氟烷氧基、氰基或鹵素原子。 In formula (3-2), Z ₃ represents -O-,

,

,

,

or

, _Z4 and _Z5 represent extended aliphatic ring, extended aromatic ring or heterocyclic group, and _Z6 represents an alkyl group with a carbon number of 3 to 18, an alkoxy group with a carbon number of 3 to 18, a fluoroalkyl group with a carbon number of 1 to 5, a fluoroalkoxy group with a carbon number of 1 to 5, a cyano group or a halogen atom.

Other diamine compounds represented by the above formula (3-2) are preferably diamine compounds represented by the following formulas (3-2-1) to (3-2-13):

In formula (3-2-10) to formula (3-2-13), s may represent an integer of 3 to 12.

In formula (3-3), Z ₇ represents a hydrogen atom, an acyl group with 1 to 5 carbons, an alkyl group with 1 to 5 carbons, an alkoxy group with 1 to 5 carbons, or a halogen. P1 represents an integer of 1 to 3. When P1 is greater than 1, the plurality of Z ₇ may be the same or different.

The diamine compound represented by the above formula (3-3) is preferably selected from (1) P1 is 1: p-diaminobenzene, m-diaminobenzene, o-diaminobenzene or 2,5-diaminotoluene, etc.; (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, 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., 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.

In the above formula (3-4), P2 represents an integer of 1 to 5. The structure represented by formula (3-4) is preferably selected from 4,4'-diaminodiphenyl sulfide.

In formula (3-5), Z ₈ and Z ₁₀ may be the same or different, and represent divalent organic groups respectively, and Z ₉ represents divalent groups derived from ring structures containing nitrogen atoms such as pyridine, pyrimidine, triazine, piperidine and piperazine.

In formula (3-6), Z ₁₁ , Z ₁₂ , Z ₁₃ and Z ₁₄ may be the same or different, and may represent a hydrocarbon group with 1 to 12 carbons. P3 represents an integer of 1 to 3, and P4 represents an integer of 1 to 20.

In formula (3-7), Z ₁₅ represents -O- or cyclohexylene, Z ₁₆ represents -CH ₂ -, Z ₁₇ represents phenylene or cyclohexylene, and Z ₁₈ represents a hydrogen atom or heptyl.

The diamine compound represented by the above formula (3-7) is preferably selected from the diamine compounds represented by the following formula (3-7-1) and formula (3-7-2).

Other diamine compounds represented by formula (3-8) to formula (3-29) are as follows:

In formula (3-16) to formula (3-19), Z ₁₉ is preferably an alkyl group having 1 to 10 carbons or an alkoxy group having 1 to 10 carbons. In formula (3-20) to formula (3-24), Z ₂₀ is preferably a hydrogen atom, an alkyl group with 1 to 10 carbons or an alkoxy group with 1 to 10 carbons.

Other diamine compounds (b1-2) 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, ethyl 2,4-diaminobenzoate, p-diaminobenzene, m-diaminobenzene, o-diaminobenzene, formula (3-1-1), formula (3-1-2), formula (3-1-5), formula (3-2-1), formula (3-2-11), formula (3-7-1), formula (3-25) or formula (3- 28) The compound represented.

The other diamine compounds (b1-2) in the aforementioned diamine component (b1) can be used alone or in combination.

Based on the total amount of diamine component (b1) being 100 moles, the amount of other diamine compounds (b1-2) is 80 to 99 moles, preferably 85 to 99 moles, and more preferably 90 to 99 moles.

The preparation method of the first polymer (A1)

The preparation of polyamic acid polymer of the present invention can be general method, preferably, the preparation method of aforementioned polyamic acid polymer comprises the following steps Steps: dissolving the mixture of tetracarboxylic dianhydride component (a1) and diamine component (b1) in a solvent, performing polycondensation reaction at a temperature of 0°C to 100°C and reacting for 1 hour to 24 hours, and then performing vacuum distillation on the above reaction solution with an evaporator to obtain a polyamic acid polymer, or pouring the above reaction solution into a large amount of poor solvent to obtain a precipitate, and then drying the above precipitate by a reduced pressure drying method to obtain a polyamide Amino acid polymer.

The solvent used in the polycondensation reaction may be the same as or different from the solvent in the liquid crystal alignment agent described below, and the solvent used in the polycondensation reaction is not particularly limited as long as it can dissolve the reactants and products. Preferably, the solvents include but are not limited to (1) aprotic polar solvents, such as: N-methyl-2-pyrrolidinone (N-methyl-2-pyrrolidinone; NMP), N,N-dimethylacetamide, N,N-dimethylformamide, dimethylsulfoxide, γ-butyrolactone, tetramethyl urea or hexamethylphosphoric triamine, etc.; (2) phenolic solvents, such as m-formaldehyde Phenol-based solvents such as phenol, 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, more preferably 300 to 1800 parts by weight.

In particular, in the polycondensation reaction, the solvent can be combined with an appropriate amount of poor solvent, wherein the poor solvent will not cause the polyamic acid polymer to precipitate. Poor solvents can be used alone or in combination, and include but are 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, 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, etc.; (5) halogenated hydrocarbons (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 (b1), the used amount of the poor solvent is preferably 0 to 60 parts by weight, more preferably 0 to 50 parts by weight.

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 the tetracarboxylic dianhydride component (a1) and the diamine component (b1), and carries out a polymerization reaction to form a polyamic acid polymer. Then, in the presence of a dehydrating agent and a catalyst, further heating, and a dehydration ring-closing reaction is carried out, so that the amide acid functional group in the polyamic acid polymer is converted into an imide functional group through a dehydration ring-closure reaction (i.e., imidization), and a polyimide polymer is obtained.

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

In order to obtain a better degree of imidization of the polyamic acid polymer, the operating temperature of the dehydration ring closure reaction is preferably from 40°C to 200°C, more preferably from 40°C to 150°C. If the operating temperature of the dehydration ring-closing reaction is lower than 40° C., the imidization reaction will not be complete, and the degree of imidization of the polyamic acid polymer will be reduced. 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 relatively low.

The dehydrating agent used in the dehydration ring-closing reaction can be selected from acid anhydride compounds, for example, acid anhydride compounds such as acetic anhydride, propionic anhydride or trifluoroacetic anhydride. Based on 1 mole of the polyamide acid polymer, the amount of the dehydrating agent is 0.01 mole to 20 mole. The catalyst used in the dehydration ring-closing reaction can be selected from (1) pyridine compounds, such as pyridine compounds such as pyridine, collidine or lutidine; (2) tertiary amine compounds, such as triethylamine and other tertiary amine compounds. Based on the usage amount of the dehydrating agent being 1 mole, the usage amount of the catalyst is 0.5 mole to 10 mole.

A preferred specific example of the polyimide-based block copolymer of the present invention is a polyamic acid block copolymer, a polyimide block copolymer, a polyamic acid-polyimide block copolymer, or any combination thereof.

The preparation of the polyimide-based block copolymer of the present invention can be a general method. Preferably, the preparation method of the polyimide-based block copolymer first dissolves the starting material in a solvent, and carries out polycondensation reaction, wherein the starting material includes the above-mentioned at least one polyamic acid polymer and/or the above-mentioned at least one polyimide polymer, and may further include a tetracarboxylic dianhydride component (a1) and a diamine component (b1).

Tetracarboxylic dianhydride component (a1) and diamine group in the aforementioned starting material Part (b1) is the same as the tetracarboxylic dianhydride component (a1) and the diamine component (b1) used in the above-mentioned 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, and will not be repeated here.

Based on 100 parts by weight of the aforementioned starting material, 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 from 0°C to 200°C, and more preferably from 0°C to 100°C.

Preferably, the starting materials include but are not limited to (1) two polyamic acid polymers with different terminal groups and different structures; (2) two polyimide polymers with different terminal groups and different structures; (3) polyamic acid polymers and polyimide polymers with different terminal groups and different structures; The structures of the tetracarboxylic dianhydride component (a1) and the diamine component (b1) used to form the polyamic acid polymer are different; (5) the polyimide polymer, the tetracarboxylic dianhydride compound and the diamine compound, wherein, at least one of the tetracarboxylic dianhydride compound and the diamine compound is different from the structure of the tetracarboxylic dianhydride component (a1) and the diamine component (b1) used to form the polyimide polymer; (6) the polyimide polymer, Polyimide polymer, tetracarboxylic dianhydride compound and diamine compound, wherein, at least one of tetracarboxylic dianhydride compound and diamine is different from the structure of tetracarboxylic dianhydride component (a1) and diamine component (b1) used to form polyamic acid polymer or polyimide polymer; (7) two kinds of polyamic acid polymers with different structures, tetracarboxylic dianhydride compounds and diamine compounds; (8) two kinds of polyimide polymers with different structures , Tetracarboxylic dianhydride compounds and diamine compounds; (9) The two terminal groups are acid anhydride groups (10) Two kinds of polyamic acid polymers and tetracarboxylic dianhydride compounds whose end groups are amine groups and have different structures; (11) Two kinds of polyimide polymers and diamine compounds whose end groups are anhydride groups and have different structures; (12) Two kinds of polyimide polymers and tetracarboxylic dianhydride compounds whose end groups are amine groups and have different structures.

Within the scope of not affecting the efficacy of the present invention, preferably, the aforementioned polyamic acid polymer, the aforementioned polyimide polymer and the aforementioned polyimide-based block copolymer may be end-modified polymers that are first adjusted in molecular weight. By using terminal-modified polymers, the coating performance of the liquid crystal alignment agent can be improved. The method of preparing the above-mentioned end-modified polymer can be obtained by adding a monofunctional compound while the polyamic acid polymer undergoes a polycondensation reaction. The monofunctional compound includes but is not limited to (1) monobasic 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-pentadecylamine, n-hexadecylamine, n-heptadecylamine, n-octadecylamine or n-eicosylamine;

The first polymer (A1) 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.

Second polymer (A2)

The polymer (A) of the present invention may further comprise a second polymer (A2), and the second polymer (A2) is prepared by reacting a tetracarboxylic dianhydride component (a2) with a diamine component (b2).

Preferred specific examples of the above-mentioned polymer (A2) are polyamic acid polymers, polyimide polymers, polyimide-based block copolymers, or combinations thereof. Among them, preferred specific examples of polyimide-based block copolymers are polyamic acid block copolymers, polyimide block copolymers, polyamic acid-polyimide block copolymers, or any combination thereof.

Tetracarboxylic dianhydride component (a2)

Specific examples of the aforementioned tetracarboxylic dianhydride component (a2) may include (1) aliphatic tetracarboxylic dianhydride compounds, (2) alicyclic tetracarboxylic dianhydride compounds, (3) aromatic tetracarboxylic dianhydride compounds or (4) tetracarboxylic dianhydride compounds having the structures shown in the aforementioned formula (1-1) to formula (1-6). These tetracarboxylic dianhydride compounds are the same as the aforementioned other tetracarboxylic dianhydride compounds (a1-2), so they will not be repeated here.

The aforementioned tetracarboxylic dianhydride component (a2) may be used alone or in combination of plural kinds.

Diamine component (b2)

Diamine compound (b2-1)

The diamine component (b2) of the present invention may comprise at least one diamine compound (b2-1), which has a structure shown in the following formula (III):

In formula (III), W ₁ each independently represents a hydrogen atom, an alkyl group with a carbon number of 1 to 10, an alkoxy group or acetamido group with a carbon number of 1 to 10, a fluorine atom, a chlorine atom or a bromine atom; W ₂ each independently represent an alkyl group with a carbon number of 1 to 3; each m1 independently represents an integer of 0 to 3; and m2 represents an integer of 0 to 4.

In formula (III), W ₁ preferably each independently represent a hydrogen atom, an alkyl group with 1 to 10 carbons, an alkoxy group with 1 to 10 carbons, or an acetamide group. When W ₁ each independently represents a hydrogen atom, an alkyl group with a carbon number of 1 to 10, an alkoxy group with a carbon number of 1 to 10, or an acetamide group, the resulting liquid crystal display device has better charge elimination and light resistance.

Specific examples of the diamine compound (b2-1) shown in formula (III) may include but not limited to diamine compounds shown in the following formula (III-1) to formula (III-28):

The above-mentioned diamine compound (b2-1) can be used individually by 1 type or in mixture of several types.

Based on the total usage amount of diamine component (b2) being 100 mol, the usage amount of diamine compound (b2-1) is 5 mol to 75 mol, preferably 5 mol to 60 mol, and more preferably 5 mol to 50 mol.

In addition, if the diamine component (b2) contains the diamine compound (b2-1), the charge-eliminating light resistance of the formed liquid crystal display device can be further improved.

Diamine compound containing carboxylic acid group (b2-2)

The diamine component (b2) of the present invention may further include a carboxylic acid group-containing diamine compound (b2-2), which has a structure represented by the following formula (IV):

In formula (IV), Y represents an organic group containing an aromatic ring having 6 to 30 carbons, and n represents an integer of 1 to 4.

The above-mentioned carboxylic acid group-containing diamine compound (b2-2) is not particularly limited as long as it has a carboxylic acid group, and the above-mentioned carboxylic acid group-containing diamine compound (b2-2) may include but not limited to aliphatic diamine, alicyclic diamine, aromatic diamine or diaminoorganosiloxane. The above-mentioned diamine compound (b2-2) containing carboxylic acid groups is preferably an alicyclic diamine or an aromatic diamine, more preferably an aromatic diamine.

The aforementioned carboxylic acid group-containing diamine compound (b2-2) may have 1 to 4 carboxylic acid groups, preferably may have 1 or 2 carboxylic acid groups.

The aforementioned carboxylic acid group-containing diamine compound (b2-2) is at least one selected from the group consisting of the following formula (IV-1) to formula (IV-5):

In formula (IV-1) to formula (IV-5), Y₁and Y₃Each independently represents a single bond, -CH₂-, -C₂h₄-, -C(CH₃)₂-, -CF₂-, -C(CF₃)₂-, -O-, -CO-, -NH-, -N(CH₃)-, -CONH-, -NHCO-, -CH₂O-, -OCH₂-, -COO-, -OCO-, -CON(CH₃)-or-N(CH₃) CO-; Y₂Represents a straight-chain alkyl group with a carbon number of 1 to 5 or a branched chain alkyl group with a carbon number of 1 to 5; n1 and n7 each independently represent an integer from 1 to 4; n2 and n3 each independently represent an integer from 0 to 4, and the sum of n2 and n3 is an integer from 1 to 4; and n4, n5 and n6 each independently represent an integer from 1 to 5.

Preferably, in formula (IV-1), n1 can represent an integer _of 1 or 2; in formula (IV-2), Y1 represents a single bond, -CH2- _{, -C2H4-, -C(CH3)2-, -O-, -CO-, -NH-, -N(CH3)-, -CONH-, -NHCO-, -COO- or -OCO-, and n2 and n3 are 1 at the same time; In formula (IV-5), Y 3 represents a single bond, -CH 2 - , -O- , -CO- ,} -NH-, -CONH-, -NHCO-, -CH ₂ O-, -OCH _{2 -} , -COO- or -OCO-, and n7 represents an integer of 1 or 2.

Specific examples of the aforementioned carboxylic acid group-containing diamine compound (b2-2) may include, but are not limited to, the diamine compounds shown in the following formula (IV-6) to formula (IV-16):

In the aforementioned formula (IV-14) and formula (IV-15), A may represent a single bond, -CH ₂ -, -O-, -CO-, -NH-, -CONH-, -NHCO-, -CH ₂ O-, -OCH ₂ -, -COO- or -OCO-.

When the carboxylic acid group-containing diamine compound ((b2-2) is at least one of the aforementioned formula (IV-1) to formula (IV-5), the formed liquid crystal display device can have better charge elimination and light resistance.

The said carboxylic acid group containing diamine compound (b2-2) can be used individually by 1 type or in mixture of several types.

Based on the total usage amount of the diamine component (b2) being 100 moles, the usage amount of the diamine compound (b2-2) containing carboxylic acid group is 25 moles to 95 moles, preferably 40 moles to 95 moles, and more preferably 50 moles to 95 moles.

In addition, if the diamine component (b2) contains the diamine compound (b2-2), the charge-eliminating light resistance of the formed liquid crystal display device can be further improved.

Other diamine compounds (b2-3)

The diamine component (b2) of the present invention may further contain other diamine compounds (b2-3).

The other diamine compounds (b2-3) are the same as the above-mentioned other diamine compounds (b1-2), so they will not be repeated here.

The preparation method of the second polymer (A2)

The preparation method of the second polymer (A2) of the present invention is the same as the preparation method of the aforementioned first polymer (A1), except that the second polymer (A2) is prepared by reacting the aforementioned tetracarboxylic dianhydride component (a2) and diamine component (b2), so the preparation method of the second polymer (A2) will not be repeated here.

Based on the total amount of the polymer (A) being 100 parts by weight, the amount of the first polymer (A1) is 10 to 90 parts by weight, and the amount of the second polymer (A2) is 90 to 10 parts by weight.

When the usage-amount of the first polymer (A1) and the usage-amount of the second polymer (A2) are in the aforementioned range, the charge-eliminating light resistance of the formed liquid crystal display element can be further improved.

solvent (B)

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 without reacting with it.

Specific examples of solvent (B) include but are not limited to N-methyl-2-pyrrolidone (N-methyl-2-pyrrolidone, NMP), γ-butyrolactone, γ-butyrolactam, 4-hydroxy-4-methyl-2-pentanone, ethylene glycol monomethyl ether, butyl lactate, butyl acetate, methyl methoxy propionate, ethyl ethoxy propionate, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol n-propyl ether, ethyl 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-dimethylethyl ether Amide (N,N-dimethyl acetamide), etc.

A solvent (B) can be used individually by 1 type or in mixture of several types.

Based on the polymer (A) used in an amount of 100 parts by weight, the solvent (B) used in an amount of 800 to 4000 parts by weight, preferably 900 to 3500 parts by weight, and more preferably 1000 to 3000 parts by weight.

Additive (C)

Within the scope of not affecting the efficacy of the present invention, the liquid crystal alignment agent of the present invention may optionally contain additive (C), and additive (C) may be epoxy Compounds or silane compounds with functional groups, etc. The function of the additive (C) is to improve the adhesion between the aforementioned liquid crystal alignment film and the surface of the substrate. Additives (C) may be used alone or in combination.

The aforementioned epoxy compounds may include but 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'-tetraglycidyl-m-xylylenediamine, 1,3-bis(N,N-diecidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane, N,N-epoxypropyl-p-glycidoxyaniline, 3-(N-allyl-N-epoxypropyl)aminopropyltrimethoxysilane, 3-(N , N-diepoxypropyl) aminopropyl trimethoxysilane and so on.

Based on 100 parts by weight of the polymer (A), the usage of the epoxy compound is generally less than 40 parts by weight, and preferably 0.1 to 30 parts by weight.

The above-mentioned silane compounds with functional groups may include but not limited to 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane Alkane (3-ureidopropyltrimethoxysilane), 3-ureidopropyltriethoxysilane, N-ethoxycarbonyl-3-aminopropyltrimethoxysilane, N-ethoxycarbonyl-3-aminopropyltriethoxysilane, N-triethoxysilane Propyltriethylenetriamine, N-trimethoxysilylpropyltriethylenetriamine, 10-trimethoxysilyl-1,4,7-triazidecane, 10-triethoxysilyl-1,4,7-triazidecane, 9-trimethoxysilyl-3,6-diazinonyl acetate, 9-triethoxysilyl-3,6-diazinonyl acetate, N-benzyl-3-aminopropyltrimethoxysilane, N-phenyl Methyl-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, N-bis(oxyethylene)-3-aminopropyltrimethoxysilane, N-bis(oxyethylene)-3-aminopropyltriethoxysilane, etc.

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

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.

Preparation method of liquid crystal alignment agent

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 (a1) and the diamine component (b1) uniformly to react to form the polymer (A) containing the first polymer (A1). Next, add the solvent (B) and the additive (C) to the polymer (A) at a temperature of 0° C. to 200° C., and continue stirring with a stirring device until it dissolves. Preferably, the polymer (A) and the additive (C) are added to the solvent (B) at a temperature of 20°C to 60°C. In addition, the polymer (A) may also optionally contain a second polymer (A2) prepared by reacting the tetracarboxylic dianhydride component (a2) and the diamine component (b2).

Method for forming liquid crystal alignment film

The liquid crystal alignment film of the present invention is a film prepared by coating the liquid crystal alignment agent formed above on a substrate, drying and baking.

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 (Pileus glass), quartz glass, polyethylene terephthalate, polybutylene terephthalate, polyether phthalate, polycarbonate, etc. used in liquid crystal display devices. It is preferable to use ITO electrodes for liquid crystal driving that have been formed on the substrate to simplify the process. Furthermore, for a reflective liquid crystal display with only one side substrate, the aforementioned substrate can be made of opaque materials such as silicon wafers, and the electrodes in this case can be formed of light-reflecting materials such as aluminum. The coating method of the liquid crystal alignment agent of the present invention can be, for example, spin coating method, printing method, inkjet method and the like.

The liquid crystal alignment agent of the present invention can choose any temperature and time, and carry out the drying and baking process after coating. Generally speaking, in order to fully remove the contained organic solvent, it needs to be dried at 50° C. to 120° C. for 1 minute to 10 minutes. After that, baking is performed at 150° C. to 300° C. for 5 minutes to 120 minutes. The thickness of the coating film after baking is not particularly limited, but a coating film that is too thin will deteriorate the reliability of the liquid crystal display. Therefore, the thickness of the coating film is preferably 5nm to 300nm, and more preferably 10nm to 200nm.

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

A specific example of the photo-alignment treatment method may be, for example: irradiating the surface of the aforementioned coating film with radiation polarized in a specific direction, and then performing heat treatment at a temperature of 150° C. to 250° C. to impart liquid crystal alignment to the aforementioned coating film. Among them, ultraviolet rays or visible light with a wavelength of 100nm to 800nm can be used as the radiation, and ultraviolet rays with a wavelength of 100nm to 400nm are preferred, and those with a wavelength of 200nm to 400nm are more preferable. Furthermore, in order to improve liquid crystal alignment, the coated substrate may be irradiated with radiation while heating the coated substrate at 50° C. to 250° C. The exposure dose of the aforementioned radiation is preferably 1 mJ/cm ² to 10,000 mJ/cm ² , more preferably 100 mJ/cm ² to 5,000 mJ/cm ² . The liquid crystal alignment film prepared in the above manner can stably align the liquid crystal molecules in a certain direction.

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

Manufacturing method of liquid crystal display element

The present invention further provides a liquid crystal display element, which comprises the aforementioned liquid crystal alignment film.

The fabrication methods of liquid crystal display elements are well known to those skilled in the art, therefore, only a brief description is given below.

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 opposite to the first unit 110, and the liquid crystal unit 130 is arranged between the first unit 110 and the second unit 120.

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.

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 .

The first substrate 112 and the second substrate 122 are selected from transparent materials and the like, wherein the transparent materials include but are not limited to alkali-free glass, soda lime glass, hard glass (Pileus glass), quartz glass, polyethylene terephthalate, polybutylene terephthalate, polyether sulfate, polycarbonate, etc. used in liquid crystal display devices. The material of the electrode 114 is selected from transparent electrodes such as tin oxide (SnO ₂ ), indium oxide-tin oxide (In ₂ O ₃ —SnO ₂ ), or metal electrodes such as chromium.

The first liquid crystal alignment film 116 and the second liquid crystal alignment film 126 are the above-mentioned liquid crystal alignment films respectively, and their function is to make the liquid crystal unit 130 form a pretilt angle, and the liquid crystal unit 130 can be driven by the parallel electric field generated by the electrode 114 .

The liquid crystals used in the liquid crystal unit 130 can be used alone or in combination. The liquid crystals include but are not limited to diaminobenzene liquid crystals, pyridazine liquid crystals, Schiff base liquid crystals, azoxy liquid crystals, biphenyl liquid crystals, phenylcyclohexane liquid crystals, biphenyl liquid crystals, phenylcyclohexane liquid crystals, ester liquid crystals, terphine liquid crystals, and terphenyl liquid crystals. enyl), biphenylcyclohexane liquid crystals, pyrimidine liquid crystals, dioxane liquid crystals, bicyclooctane liquid crystals, cubane liquid crystals, etc., and optional additions such as cholesterol chloride, cholesterol nonanoate, cholesterol carbonate, etc. Cholesteric liquid crystals, or under the trade name "C-15", A chiral agent such as "CB-15" (manufactured by Merck), or a ferroelectric liquid crystal such as p-decyloxybenzylidene-p-amino-2-methylbutyl cinnamate.

The liquid crystal display elements produced by the liquid crystal alignment agent of the present invention are suitable for various types of nematic liquid crystals, such as TN, STN, TFT, VA, IPS and other liquid crystal display elements. In addition, depending on the selected liquid crystal, it can also be used in liquid crystal display elements having different ferroelectric properties, anti-ferroelectric properties, and the like. Among the above-mentioned liquid crystal display elements, the IPS type liquid crystal display element is particularly suitable.

The following examples are used to describe the present invention in detail, but it does not mean that the present invention is limited to the content disclosed in these examples.

100‧‧‧LCD display element

110‧‧‧Unit 1

112‧‧‧The first substrate

114‧‧‧The first conductive film

116‧‧‧The first liquid crystal alignment film

120‧‧‧Unit 2

122‧‧‧Second Substrate

126‧‧‧The second liquid crystal alignment film

130‧‧‧LCD unit

In order to make the above and other objects, features, advantages and embodiments of the present invention more comprehensible, the detailed description of the accompanying drawings is as follows:

[ FIG. 1 ] is a schematic diagram showing the structure of a liquid crystal display element according to an embodiment of the present invention.

Synthetic polymers (A1)

Synthesis Example A1-1-1

A nitrogen inlet, a stirrer, a condenser and a thermometer were installed on a four-neck conical flask with a volume of 500 ml, and nitrogen was introduced. Then, add 0.107 gram (0.0005 mol) of diamine compound (b1-1-7) shown in formula (2-1), 5.353 gram (0.0495 mol) of p-diaminobenzene (b1-2-1) and 80 grams of N-methyl-2-pyrrolidone (hereinafter referred to as NMP), and stirred at room temperature until dissolved. Then, 1.68 grams (0.0075 moles) of compound (a1-1-1), 9.27 grams (0.0425 moles) of pyromellitic dianhydride (a1-2-1) and 20 grams of NMP were added and reacted at room temperature for 2 hours. After the reaction, the reaction solution was poured into 1500 ml of water to precipitate the polymer, and the obtained polymer was filtered, and the steps of washing and filtering were repeated three times with methanol. Afterwards, the product was placed in a vacuum oven and dried at a temperature of 60° C. to obtain the polymer (A1-1-1), whose formula is shown in Table 1.

Synthesis Examples A1-1-2 to A1-1-10 and Synthesis Comparative Examples A1'-1-1 to A1'-1-2

Synthesis Examples A1-1-2 to A1-1-10 and Comparative Synthesis Examples A1'-1-1 to A1'-1-2 use the same preparation method as the preparation method of the polymer (A1-1-1) in Synthesis Example A1-1-1, the difference is that Synthesis Examples A1-1-2 to A1-1-10 and Comparative Synthesis Examples A1'-1-1 to A1'-1-2 change the types and usage amounts of raw materials in the polymer. repeat.

Synthesis Example A1-2-1

A nitrogen inlet, a stirrer, a heater, a condenser, and a thermometer were arranged on a four-necked conical flask with a volume of 500 milliliters, and nitrogen was introduced. Then, add 0.107 grams (0.0005 moles) of diamine compound (b1-1-7) shown in formula (2-1), 5.35 grams (0.0495 moles) of p-diaminobenzene (b1-2-1) and 80 grams of NMP, and stir at room temperature until dissolved. Then, 2.24 g (0.01 mol) of compound (a1-1-1) represented by formula (I-1), 8.72 g (0.04 mol) of pyromellitic dianhydride (a1-2-1) and 20 g of NMP were added. reaction at room temperature 6 hours later. After the reaction, 97 g of NMP, 2.55 g of acetic anhydride, and 19.75 g of pyridine were added to the aforementioned reaction solution, the temperature was raised to 60° C., and the stirring was continued for 2 hours to carry out the imidization reaction. After the reaction, the reaction solution was poured into 1500 ml of water to precipitate the polymer, and the obtained polymer was filtered, and the steps of washing and filtering were repeated three times with methanol. Afterwards, the product was placed in a vacuum oven and dried at a temperature of 60° C. to obtain the polymer (A1-2-1), whose formula is shown in Table 1.

Synthesis Examples A1-2-2 to A1-2-4 and Synthesis Comparative Example A1'-2-1

Synthesis Examples A1-2-2 to A1-2-4 and Comparative Synthesis Example A1'-2-1 use the same preparation method as that of the polymer (A1-2-1) in Synthesis Example A1-2-1. The difference is that Synthesis Examples A1-2-2 to A1-2-4 and Comparative Synthesis Example A1'-2-1 change the types and amounts of raw materials in the polymer. The formulations are shown in Table 1 and will not be repeated here.

Synthetic polymers (A2)

Synthesis Examples A2-1-1 to A2-1-6

Synthesis Examples A2-1-1 to A2-1-6 use the same preparation method as that of the polymer (A1-1-1) in Synthesis Example A1-1-1. The difference is that Synthesis Examples A2-1-1 to A2-1-6 change the types and amounts of raw materials in the polymer. The formulations are shown in Table 2, and will not be repeated here.

Synthesis Examples A2-2-1 to A2-2-3

Synthesis Examples A2-2-1 to A2-2-3 use the same preparation method as that of the polymer (A1-2-1) in Synthesis Example A1-2-1. The difference lies in that Synthesis Examples A2-2-1 to A2-2-3 change the types and amounts of raw materials in the polymer. The formulations are shown in Table 2, and will not be repeated here.

Example 1

Preparation of liquid crystal alignment agent

The liquid crystal alignment agent of Example 1 was prepared by weighing 100 parts by weight of the polymer (A1-1-1) of Synthesis Example A1-1-1 and 1050 parts by weight of NMP, and stirring and mixing at room temperature.

Preparation of liquid crystal alignment film and liquid crystal display element

The prepared liquid crystal alignment agent was spin-coated on a glass substrate, wherein a pixel electrode was formed on the glass substrate, wherein the pixel electrode was an IPS driving electrode having a pair of ITO electrodes (electrode width: 10 μm, electrode spacing: 10 μm, electrode height: 50 nm), the pair of ITO electrodes respectively had a comb-shaped shape, and the comb-shaped parts of each other were arranged in a manner of separating and occluding. Afterwards, the glass substrate coated with the liquid crystal alignment agent was dried on a hot plate at 80° C. for 5 minutes, and then 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.

Through a polarizing plate, irradiate the surface of the coating film with ultraviolet rays with a wavelength of 254nm to prepare a substrate with a liquid crystal alignment film. Next, similarly, a coating film was formed on an opposite substrate, which is a glass substrate with no electrodes formed but columnar spacers with a height of 4 μm, and subjected to alignment treatment.

The above two substrates form a set, one of which is printed with a sealant, and the other is bonded to face the liquid crystal alignment film with an alignment direction of 0°, and then the sealant is hardened to form an empty unit cell. The empty unit cell was injected into liquid crystal MLC-2041 (manufactured by Merck) by a depressurized injection method, and the injection port was sealed to obtain the liquid crystal display element of Example 1.

The liquid crystal display element of embodiment 1 was evaluated in the following manner The evaluation was carried out, and the results are shown in Table 3.

Examples 2 to 26 and Comparative Examples 1 to 5

Examples 2 to 26 and Comparative Examples 1 to 5 use the same preparation method as the liquid crystal alignment agent of Example 1. The difference lies in that the types and usage amounts of the raw materials in the liquid crystal alignment agent are changed in Examples 2 to 26 and Comparative Examples 1 to 5. The formulations and evaluation results are shown in Table 3 and Table 4 respectively, and will not be repeated here.

Evaluation method

Charge Elimination Light Fastness

Apply a DC voltage of 3 volts to the aligned liquid crystal display elements prepared in Examples 1 to 26 and Comparative Examples 1 to 5 and irradiated with ultraviolet light having a wavelength of 254 nm for 30 minutes, then use an electrical measuring machine (manufactured by TOYO Corporation, model Model 6254) to measure the accumulated voltage (V _R1 ) of the liquid crystal display element after the voltage is released and the accumulated voltage (V _R2 ) 15 minutes after the voltage is released, and the accumulated charge elimination slope is calculated by the following formula (1) (V _S ), and the charge erasing light resistance was evaluated on the basis of the following criteria. Among them, the higher the accumulated charge elimination slope after irradiating ultraviolet rays with a wavelength of 254nm, the better the charge elimination and light resistance of the liquid crystal display element:

※: 75%<V _S

◎: 70%<V _S ≦75%

○: 65%<V _S ≦70%

△: 60%<V _S ≦65%

×: V _S ≦60%.

Pretilt

According to the method described on page 2013 of the 19th issue of Journal of Applied Physics (J.Appl.Phys.) published by T.J. Scheffer (T.J.Scheffer) et al. in 1980, the pretilt angle of the center point of the liquid crystal display elements prepared in Examples 1 to 26 and Comparative Examples 1 to 5 was measured by the crystal rotation method of He-Ne laser light. The results are shown in Table 3 and Table 4.

According to Table 3 and Table 4, if the first polymer (A1) included in the polymer (A) in the liquid crystal alignment agent is not synthesized using a specific tetracarboxylic dianhydride component (a1) and diamine component (b1), the resulting liquid crystal display device has poor charge elimination and light resistance.

Further, when the diamine compound (b1-1) in the diamine component (b1) has a structure as shown in formula (II), and X in formula ( _II ) represents a branched chain alkyl group with a carbon number of 3 to 10, the charge elimination and light resistance of the liquid crystal display element can be further improved.

In addition, when the polymer (A) in the liquid crystal alignment agent contains the second polymer (A2) prepared by the reaction of the specific tetracarboxylic dianhydride component (a2) and the diamine component (b2), the charge-eliminating light resistance of the liquid crystal display element can be further improved. Furthermore, when the diamine component (b2) has a carboxylic acid group-containing diamine compound (b2-1), the charge-eliminating light resistance of the liquid crystal display device can be further improved.

In addition, when the diamine component (b2) has a carboxylic acid group-containing diamine compound (b2-2), the charge-eliminating light resistance of the liquid crystal display device can be further improved.

Although the present invention has been disclosed as above with several embodiments, it is not intended to limit the present invention. Those who are knowledgeable can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be defined by the scope of the appended patent application.

100‧‧‧LCD display element

110‧‧‧Unit 1

112‧‧‧The first substrate

114‧‧‧The first conductive film

116‧‧‧The first liquid crystal alignment film

120‧‧‧Unit 2

122‧‧‧Second Substrate

126‧‧‧The second liquid crystal alignment film

130‧‧‧LCD unit

Claims (17)

A liquid crystal alignment agent, comprising: The polymer (A) comprises a first polymer (A1), and the first polymer (A1) is prepared by reacting a tetracarboxylic dianhydride component (a1) and a diamine component (b1), wherein the tetracarboxylic dianhydride component (a1) comprises at least one tetracarboxylic dianhydride compound (a1-1) represented by the following formula (I):

In the formula (I), R ₁ to R ₄ each independently represent a hydrogen atom, a halogen atom, an alkyl group with a carbon number of 1 to 6, an alkenyl group with a carbon number of 2 to 6, an alkynyl group with a carbon number of 2 to 6, a monovalent organic group or a phenyl group containing a fluorine atom and a carbon number of 1 to 6, R ₁ to R ₄ are the same or different, and at least one of R ₁ , R ₂ , R ₃ and R ₄ is not a hydrogen atom; and wherein the diamine component (b1) contains at least one diamine compound (b1-1) represented by the following formula (II):

In this formula (II), X ₁ represents O, COO, OCO, CONH or NHCO, ring X ₂ represents a benzene ring or cyclohexane, and X ₃ represents a straight-chain alkyl group with a carbon number of 1 to 10 or a branched chain alkyl group with a carbon number of 3 to 10; and - Solvent (B). The liquid crystal alignment agent as described in claim 1, wherein in the formula (II), X ₃ represents a branched chain alkyl group with 3 to 10 carbon atoms. The liquid crystal alignment agent as described in claim 1, wherein the polymer (A) includes a second polymer (A2), and the second polymer (A2) is prepared by reacting a tetracarboxylic dianhydride component (a2) with a diamine component (b2). The liquid crystal alignment agent described in claim 3 of the patent application, wherein the diamine component (b2) contains at least one diamine compound (b2-1) represented by the following formula (III):

In the formula (III), _W1 each independently represents a hydrogen atom, an alkyl group having a carbon number of 1 to 10, an alkoxy group or an acetamide group having a carbon number of 1 to 10, a fluorine atom, a chlorine atom or a bromine atom, W2 _each independently represents an alkyl group having a carbon number of 1 to 3, each m1 independently represents an integer of 0 to 3, and m2 represents an integer of 0 to 4. The liquid crystal alignment agent described in claim 3, wherein the diamine component (b2) contains at least one carboxylic acid group-containing diamine compound (b2-2). The liquid crystal alignment agent described in item 4 of the scope of the patent application, wherein in the formula (III), W ₁ each independently represent a hydrogen atom, an alkyl group with 1 to 10 carbons, an alkoxy group with 1 to 10 carbons, or an acetamide group. The liquid crystal alignment agent as described in item 5 of the scope of the patent application, wherein the carboxylic acid group-containing diamine compound (b2-2) includes a compound represented by the following formula (IV):

In the formula (IV), Y represents an organic group having an aromatic ring having 6 to 30 carbons, and n represents an integer of 1 to 4. The liquid crystal alignment agent described in claim 7 of the patent application, wherein the carboxylic acid group-containing diamine compound (b2-2) is at least one member selected from the group consisting of the following formula (IV-1) to formula (IV-5):

In the formula (IV-1) to the formula (IV-5), Y ₁ and Y ₃ each independently represent a single bond, -CH ₂ -, -C ₂ H ₄ -, -C(CH 3 ) ₂ -, -CF ₂ -, -C(CF ₃ ) ₂ -, -O-, -CO-, -NH-, -N(CH ₃ )-, -CONH-, -NHCO-, -CH ₂ O-, -OCH ₂ -, -COO-, -OCO-, -CON(CH ₃ )- or -N( _{CH 3 )} CO-; _Y represents a straight-chain alkyl group with 1 to 5 carbons or a branched chain alkyl group with 1 to 5 carbons; n1 and n7 each independently represent an integer from 1 to 4; n2 and n3 each independently represent an integer of 0 to 4, and the sum of n2 and n3 is an integer of 1 to 4; and n4, n5, and n6 each independently represent an integer of 1 to 5. The liquid crystal alignment agent as described in item 1 of the scope of the patent application, wherein based on the total usage amount of the tetracarboxylic dianhydride component (a1) being 100 moles, the usage amount of the tetracarboxylic dianhydride compound (a1-1) represented by the formula (I) is 20 moles to 100 moles. The liquid crystal alignment agent as described in item 1 of the scope of the patent application, wherein the total usage amount of the diamine component (b1) is 100 moles, the The diamine compound (b1-1) represented by the formula (II) is used in an amount of 1 mol to 20 mol. The liquid crystal alignment agent described in claim 4 of the patent application, wherein based on the total usage amount of the diamine component (b2) is 100 moles, the usage amount of the diamine compound (b2-1) represented by the formula (III) is 5 moles to 75 moles. The liquid crystal alignment agent as described in item 5 of the patent application, wherein based on the total usage amount of the diamine component (b2) being 100 moles, the usage amount of the carboxylic acid group-containing diamine compound (b2-2) is 25 moles to 95 moles. The liquid crystal alignment agent as described in item 3 of the patent application, wherein based on the total usage amount of the polymer (A) being 100 parts by weight, the usage amount of the first polymer (A1) is 10 parts by weight to 90 parts by weight, and the usage amount of the second polymer (A2) is 10 parts by weight to 90 parts by weight. The liquid crystal alignment agent as described in claim 1, wherein the amount of the solvent (B) is 800 to 4000 parts by weight based on 100 parts by weight of the polymer (A). The liquid crystal alignment agent described in item 1 of the scope of the patent application, wherein the liquid crystal alignment agent forms a liquid crystal alignment film after a pre-baking treatment, a post-baking treatment and a photo-alignment treatment, and the pre-tilt angle of the liquid crystal alignment film is 0° to 3°. A liquid crystal alignment film is formed by using the liquid crystal alignment agent described in any one of the first to fifteenth items of the scope of the patent application. A liquid crystal display element, including the liquid crystal alignment film described in item 16 of the scope of application.

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