TWI849179B - 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) is manufactured by reacting a specific tetracarboxylic acid dianhydride component (a) with a specific diamine component (b). The liquid crystal alignment film is formed form the liquid crystal alignment agent, and the liquid crystal display element including the liquid crystal alignment film has a lower flicker level after the element is driven.

Description

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

The present invention relates to a liquid crystal alignment agent, a liquid crystal alignment film and a liquid crystal display element, and in particular to a liquid crystal display element that utilizes the liquid crystal alignment agent to produce a liquid crystal display element with a better degree of flickering immediately after being driven.

Liquid crystal display elements used in liquid crystal televisions, liquid crystal displays, etc. usually have a liquid crystal alignment film inside the element to control the arrangement of the liquid crystal. The most common method in the industry at present is to rub the surface of the film formed by polyamide and/or imide formed on the electrode substrate with cotton, nylon, polyester and other fabrics in one direction, and perform the so-called friction treatment to produce this liquid crystal alignment film.

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

As a method to replace the friction treatment, it is known that there is a photo-alignment method that uses polarized ultraviolet light to give liquid crystal alignment energy. The so-called photo-alignment method is a liquid crystal alignment treatment that uses a substance that uses a photoisomerization reaction, a substance that uses a photocrosslink reaction, a substance that uses a photodecomposition reaction, etc. in the reaction mechanism. Furthermore, Japanese Patent Publication No. 9-297313 proposes that the photo-alignment method uses a polyimide film with an alicyclic structure such as cyclobutane in the main chain. When using polyimide as an alignment film for photo-alignment, because this alignment film has higher heat resistance than other types of alignment films, the applicability of this alignment film is promising.

The optical alignment method is a method of non-rubbing alignment treatment. It has the advantage of being manufactured using a simple process in the industry. In the liquid crystal display elements of the In-Plane-Switching (IPS) driving method and the Fringe Field Switching (FFS) driving method, the liquid crystal alignment film obtained by the optical alignment method is expected to improve the contrast and viewing angle characteristics of the liquid crystal display element compared to the liquid crystal alignment film obtained by the rubbing treatment method. Therefore, the optical alignment method is a promising and highly anticipated liquid crystal alignment treatment method.

However, when the liquid crystal alignment film produced by the photo-alignment method is applied to a liquid crystal display element, the produced liquid crystal display element still has the problem of poor flicker immediately after driving, that is, the accumulated charge of the liquid crystal alignment film after being illuminated is slowly eliminated, resulting in excessive residual charge, and then generating the problem of residual image. From the above, it can be seen that in order to meet the requirements of the current photo-aligned IPS type liquid crystal display industry, providing a liquid crystal alignment agent that can form a liquid crystal display element with better flicker immediately after driving is the goal of the research efforts of the technical field.

One aspect of the present invention is to provide a liquid crystal alignment agent, which includes a polymer (A) and a solvent (B). This liquid crystal alignment agent can improve the flicker level of the liquid crystal display element produced immediately after being driven. In addition, the liquid crystal alignment agent of the present invention can optionally include an additive (C).

Another aspect of the present invention is to provide a liquid crystal alignment film, which is formed 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.

According to the above aspects of the present invention, a liquid crystal alignment agent is proposed, and the liquid crystal alignment agent comprises a polymer (A) and a solvent (B), which is described below.

Polymer (A)

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

Preferred specific examples of the aforementioned polymer (A) may be polyamic acid polymers, polyimide polymers, polyimide-based block copolymers or combinations thereof. 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 (a)

Tetracarboxylic dianhydride compound (a-1)

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

In formula (I), _R1 to _R4 each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, a monovalent organic group having 1 to 6 carbon atoms and containing a fluorine atom, or a phenyl group, _R1 to _R4 may be the same or different, and at least one of _R1 , _R2 , _R3 and _R4 is not a hydrogen atom.

When R ₁ , R ₂ , R ₃ and R ₄ have a stereo-blocking structure, the liquid crystal alignment agent produced will cause the formed liquid crystal display element to have poor flickering immediately after being driven. Therefore, R ₁ , R ₂ , R ₃ and R ₄ are preferably hydrogen atoms, methyl groups or ethyl groups, and methyl groups are more preferred.

Specific examples of the tetracarboxylic dianhydride compound (a-1) as shown in formula (I) may be compounds shown in formula (I-1) to formula (I-8) below. In terms of the degree of flash immediately after driving, formula (I-1) is preferred.

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

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

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

Other tetracarboxylic dianhydride compounds (a-2)

The tetracarboxylic dianhydride component (a) of the present invention may optionally contain other tetracarboxylic dianhydride compounds (a-2). Preferred specific examples of other tetracarboxylic dianhydride compounds (a-2) may be (1) aliphatic tetracarboxylic dianhydride compounds, (2) alicyclic tetracarboxylic dianhydride compounds, (3) aromatic tetracarboxylic dianhydride compounds or (4) tetracarboxylic dianhydride compounds shown in the following formulas (V-1) to (V-6), etc.

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

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

Specific examples of the (3) aromatic tetracarboxylic dianhydride compounds of the present invention include, but are not limited to, 3,4-dicarboxy-1,2,3,4-tetrahydronaphthalene-1-succinic dianhydride, pyromellitic dianhydride, 2,2',3,3'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-biphenyl tetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 3,4-dicarboxy-1,2,3,4-tetrahydronaphthalene-1-succinic dianhydride, 2,2',3,3'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 2,2',3,3'-benzophenonetetracarboxylic dianhydride, 2,3,6,7-naphthalene ...2',3,3'-benzophenonetetracarboxylic ,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)diphenylsulfone dianhydride, 4,4'-bis(3,4-dicarboxyphenoxy)diphenylpropane dianhydride, 3,3',4,4'-perfluoroisopropylidene diphthalic acid dianhydride, 2,2',3,3'-diphenyltetracarboxylic dianhydride, 2,3,3',4'-diphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenyltetracarboxylic dianhydride anhydride, bis(phthalic acid) phenylphosphine oxide dianhydride, p-phenylene-bis(triphenylphthalic acid) dianhydride, m-phenylene-bis(triphenylphthalic acid) dianhydride, bis(triphenylphthalic acid)-4,4'-diphenyl ether dianhydride, bis(triphenylphthalic acid)-4,4'-diphenylmethane dianhydride, ethylene glycol-bis(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 dianhydride, 1,3,3a,4,5,9b-hexahydro-5-(tetrahydro-2,5-dioxo-3-furanyl)-naphtho[1,2-c]-furan-1,3-dione, 1,3,3a,4,5,9b-hexahydro-5-methyl-5-( 1,3-dione, 1,3,3a,4,5,9b-hexahydro-5-ethyl-5-(tetrahydro-2,5-dioxo-3-furyl)-naphtho[1,2-c]-furan-1,3-dione, 1,3,3a,4,5,9b-hexahydro-7-methyl-5-(tetrahydro-2,5-dioxo-3-furyl)-naphtho[1,2-c]-furan-1,3-dione -furan-1,3-dione, 1,3,3a,4,5,9b-hexahydro-7-ethyl-5-(tetrahydro-2,5-dioxo-3-furanyl)-naphtho[1,2-c]-furan-1,3-dione, 1,3,3a,4,5,9b-hexahydro-8-methyl-5-(tetrahydro-2,5-dioxo-3-furanyl)-naphtho[1,2-c]-furan-1,3-dione, 1,3,3a,4,5,9b-hexahydro- 8-ethyl-5-(tetrahydro-2,5-dioxo-3-furanyl)-naphtho[1,2-c]-furan-1,3-dione, 1,3,3a,4,5,9b-hexahydro-5,8-dimethyl-5-(tetrahydro-2,5-dioxo-3-furanyl)-naphtho[1,2-c]-furan-1,3-dione, 5-(2,5-dioxo-tetrahydrofuranyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic dianhydride, etc.

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

In formula (V-5), _N1 represents a divalent group containing an aromatic ring; r represents an integer from 1 to 2; _N2 and _N3 may be the same or different and may represent a hydrogen atom or an alkyl group, respectively. Preferably, the tetracarboxylic dianhydride compound represented by formula (V-5) may be selected from the compounds represented by the following formulas (V-5-1) to (V-5-3).

In formula (V-6), _N4 represents a divalent group containing an aromatic ring; _N5 and _N6 may be the same or different and represent a hydrogen atom or an alkyl group, respectively. Preferably, the tetracarboxylic dianhydride compound represented by formula (V-6) can be selected from the compounds represented by formula (V-6-1) below.

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

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

Based on the usage of 100 mol of the diamine component (b), the usage of the tetracarboxylic dianhydride component (a) ranges from 20 mol to 200 mol, and preferably from 30 mol to 120 mol.

Diamine component (b)

The diamine component (b) of the present invention may include a diamine compound (b-1) as shown in the following formula (II).

HN ₂ -X ₁ -M ₁ -AM ₂ -X ₂ -NH ₂ (II)

In formula (II), _M1 and _M2 each independently represent a single bond, -O-, -S-, _-NM3- , an ester group, an amide group, a thioester group, a urea group, a carbonate group or a carbamate group, wherein _M3 represents a hydrogen atom or a methyl group, and _M1 and _M2 may be the same or different; A represents an alkylene group having a carbon number of 2 to 20; _X1 and _X2 each independently represent a divalent organic group as shown in the following formulas (III-1) to (III-19), and _X1 and _X2 are selected from two different structures in formulas (III-1) to (III-19), wherein at least one of _X1 and _X2 represents a structure as shown in formula (III-17), formula (III-18) or formula (III-19).

In formula (III-2), _X3 represents an alkylene group having 1 to 5 carbon atoms; in formula (III-14), _X4 represents a hydrogen atom, a halogen atom, a methyl group, a hydroxyl group or a methoxy group; in formula (III-17), _X5 and _X6 each independently represent a halogen atom, a methyl group, a hydroxyl group or a methoxy group; in formula (III-18), _X7 and _X8 each independently represent a hydrogen atom, a halogen atom, a methyl group, a hydroxyl group or a methoxy group, and at least one of _X7 and _X8 is not a hydrogen atom.

It should be noted that the two different structures selected from formula (III-1) to formula (III-19) by _X1 and _X2 refer to _X1 and _X2 having different main structures (i.e., structures shown in formula (III-1) to formula (III-19)), rather than just the difference in functional groups. In other words, if _X1 and _X2 have the same main structure and their main structures have different functional groups, although their chemical structures have the difference in functional groups, these diamine compounds do not belong to the diamine compound (b-1) of the present invention. In formula (II), when _X1 and _X2 are selected from the same structural formula among formula (III-1) to formula (III-19) (i.e., the same main structure, and the functional groups bonded to the main structure are the same or different), the liquid crystal alignment agent prepared will cause the formed liquid crystal display element to have poor flicker immediately after being driven.

In formula (II), _M1 and _M2 are preferably single bonds, -O-, -S-, _-NM3- , ester groups or amide groups, and more preferably -O-. Next, from the viewpoint of liquid crystal alignment, A preferably represents an alkylene group having 2 to 6 carbon atoms, and more preferably an alkylene group having 2 to 4 carbon atoms.

In formula (III-2), X ₃ preferably represents an alkylene group having 1 to 3 carbon atoms, and in formula (III-14), X ₄ preferably represents a hydrogen atom or a methyl group.

In formula (II), if at least one of _X1 and _X2 does not represent a structure as shown in formula (III-17), formula (III-18) or formula (III-19), the liquid crystal alignment agent prepared will cause the formed liquid crystal display element to have poor flicker immediately after being driven.

In some embodiments, the diamine compound (b-1) can be selected from the diamine compounds shown in the following formula (II-1-1) to formula (II-1-3).

In formula (II-1-1) to formula (II-1-3), A, M ₁ , M ₂ , X ₅ , X ₆ , X ₇ and X ₈ are as defined above.

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

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

In formula (II-2-16) and formula (II-2-24), the definition of M ₃ is as described above and will not be further described here.

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

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

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

Diamine compound (b-2)

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

In formula (IV), _Z1 and _Z5 each independently represent a _single bond, _-CH2- or _-CH2CH2- ; _Z2 and _Z4 each independently represent _-CH2- or _-CH2CH2- ; _Z3 represents an alkylene group or a cyclohexylene group having 1 to 6 carbon atoms; _Y1 and _Y2 each independently represent a single bond, -O-, -NH-, -N( _CH3 )-, -C(=O)-, -C(=O)O- _, -C(=O)NH-, -C(=O)N( _CH3 )-, -OC(=O)-, -NHC(=O)- or N( _CH3 )C(=O)-; Y ₃ represents a linear alkyl group having 1 to 20 carbon atoms, a branched alkyl group having 3 to 20 carbon atoms, or a cyclic alkyl group having 3 to 20 carbon atoms; and a represents 0 or 1.

In formula (IV), _Z1 and _Z5 preferably represent a single bond or _-CH2- ; _Z2 and _Z4 preferably represent _-CH2- . When _Z1 and _Z5 are the same, _Z2 and _Z4 are preferably different. When _Z1 and _Z5 are different, _Z2 and _Z4 are preferably the same.

In formula (IV), _Y1 and _Y2 preferably represent a single bond, -O-, -C(=O)-, -C(=O)O-, -C(=O)NH-, -C(=O)N( _CH3 )-, -OC(=O)-, -NHC(=O)- or N( _CH3 )C(=O)-, and more preferably independently represent a single bond or -O-. When _Y1 and _Y2 independently represent a single bond or -O-, the resulting liquid crystal alignment agent can further reduce the flicker level of the formed liquid crystal display element immediately after being driven.

From the viewpoint of availability of raw materials, Y ₃ is preferably, for example, methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, benzyl, n-hexadecyl or 9-fluorenylmethyl.

From the perspective of ease of synthesis, a is preferably 0.

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

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

The aforementioned diamine compound (b-2) can be used alone or in combination of two or more.

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

When the diamine component (b) contains the diamine compound (b-2), the resulting liquid crystal alignment agent can further reduce the flicker level of the formed liquid crystal display element immediately after being driven.

Other diamine compounds (b-3)

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

Other diamine compounds (b-3) may include but are not limited to 1,2-diaminoethane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 4,4'-diaminoheptane, 1,3-diamino-2,2-dimethylpropane, 1,6-diamino-2,5-diamino methylhexane, 1,7-diamino-2,5-dimethylheptane, 1,7-diamino-4,4-dimethylheptane, 1,7-diamino-3-methylheptane, 1,9-diamino-5-methylnonane, 2,11-diaminododecane, 1,12-diaminooctadecane, 1,2-bis(3-aminopropoxy)ethane, 4,4'-diaminodicyclohexylmethane, 4,4'-diamino-3,3'-dimethyldicyclohexylamine, 1,3 -Diaminocyclohexane, 1,4-diaminocyclohexane, isophoronediamine, tetrahydrodicyclopentadienediamine, tricyclo[6.2.1.0(2,7)]-undecenedimethyldiamine, 4,4'- methylenebis(cyclohexylamine), 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylethane, 4,4'-diaminodiphenylsulfone, 4,4'-diaminobenzanilide, 4,4'-diaminodiphenylether, 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-methylenediamine, 3,3'-diaminobenzophenone, 3,4'-diaminobenzophenone, 4,4'-diaminobenzophenone, 2,2-bis[4-(4-aminophenoxy)phenyl] ] propane, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2-bis(4-aminophenyl)hexafluoropropane, 2,2-bis[4-(4-aminophenoxy)phenyl]sulfone, 1,4-bis(4-aminophenoxy)cyclohexane, 1,5-bis(4-aminophenoxymethylene)adamantane, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy) Benzene, 9,9-bis(4-aminophenyl)-10-hydroanthracene, 9,10-bis(4-aminophenyl)anthracene, 2,7-diaminofluorene, 9,9-bis(4-aminophenyl)fluorene, 4,4'-methylene-bis(2-chloroaniline), 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, 1,1-bis[4-(4-aminophenoxy)phenyl]-4-(4-ethylphenyl)cyclohexane, or other diamine compounds represented by the following formulas (VI-1) to (VI-29).

、

、

、

或

，且F₂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 (VI-1), _F1 represents -O-,

,

,

,

or

, and F ₂ represents a steryl group, a trifluoromethyl group, a fluoro group, an alkyl group having 2 to 30 carbon atoms, or a monovalent group derived from a nitrogen atom-containing cyclic structure such as pyridine, pyrimidine, triazine, piperidine and piperazine.

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

、

、

、

或

，F₄及F₅代表伸脂肪族環、伸 芳香族環或伸雜環基團，且F₆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 (VI-2), F ₃ represents -O-,

,

,

,

or

, _F4 and _F5 represent an aliphatic ring-extended, aromatic ring-extended or heterocyclic group, and _F6 represents an alkyl group having 3 to 18 carbon atoms, an alkoxy group having 3 to 18 carbon atoms, a fluoroalkyl group having 1 to 5 carbon atoms, a fluoroalkoxy group having 1 to 5 carbon atoms, a cyano group or a halogen atom.

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

In formula (VI-2-10) to formula (VI-2-13), s can represent an integer from 3 to 12.

In formula (VI-3), _F7 represents a hydrogen atom, an acyl group having 1 to 5 carbon atoms, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or a halogen. P1 represents an integer from 1 to 3. When P1 is greater than 1, a plurality of _F7s may be the same or different.

The diamine compound represented by the above formula (VI-3) is preferably selected from (1) P1 is 1: p-diaminobenzene, m-diaminobenzene, o-diaminobenzene or 2,5-diaminotoluene; (2) P1 is 2: 4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 2,2'-dichloro-4,4'-diaminobiphenyl, 3,3'-dichloro-4,4'-diaminobiphenyl, benzene, 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., 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 (VI-4), P2 represents an integer from 1 to 5. The structure represented by formula (VI-4) is preferably selected from 4,4'-diaminodiphenyl sulfide.

In formula (VI-5), _F8 and _F10 may be the same or different and each represent a divalent organic group, and _F9 represents a divalent group derived from a nitrogen atom-containing cyclic structure such as pyridine, pyrimidine, triazine, piperidine and piperazine.

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

In formula (VI-7), _F15 represents -O- or a cyclohexylene group, _F16 represents _-CH2- , _F17 represents a phenylene group or a cyclohexylene group, and _F18 represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.

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

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

In formula (VI-16) to formula (VI-19), _F19 is preferably an alkyl group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms. In formula (VI-20) to formula (VI-24), _F20 is preferably a hydrogen atom, an alkyl group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms.

Other diamine compounds (b-3) 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)benzene, [(4-(4-ethylphenyl)cyclohexane]-4-(4-ethylphenyl)cyclohexane, ethyl 2,4-diaminophenylcarboxylate, p-diaminobenzene, m-diaminobenzene, o-diaminobenzene, a compound represented by formula (VI-1-1), formula (VI-1-2), formula (VI-1-5), formula (VI-2-1), formula (VI-2-11), formula (VI-7-1), formula (VI-25) or formula (VI-28).

The aforementioned other diamine compounds (b-3) can be used alone or in combination of two or more.

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

Preparation method of polymer (A)

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

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

In particular, in the polycondensation reaction, the solvent may be used together with an appropriate amount of a poor solvent, wherein the poor solvent does not cause the polyamine polymer to precipitate. The poor solvent may 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; (3) esters, such as methyl acetate, ethyl acetate, butyl acetate, diethyl oxalate, diethyl malonate or ethylene glycol ethyl ether acetate; (4) ethers, For example: ethers such as diethyl ether, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol n-propyl ether, ethylene glycol isopropyl ether, ethylene glycol n-butyl ether, ethylene glycol dimethyl ether or diethylene glycol dimethyl ether; (5) halogenated hydrocarbons such as dichloromethane, 1,2-dichloroethane, 1,4-dichlorobutane, trichloroethane, chlorobenzene or o-dichlorobenzene; (6) hydrocarbons such as tetrahydrofuran, hexane, heptane, octane, benzene, toluene or xylene or any combination of the above solvents. Based on the usage of the diamine component (b) being 100 parts by weight, the usage of the poor solvent is preferably 0 to 60 parts by weight, and 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 the mixture in a solution, wherein the mixture includes a tetracarboxylic dianhydride component (a) and a diamine component (b), and performs a polymerization reaction to form a polyimide polymer. Then, in the presence of a dehydrating agent and a catalyst, further heating is performed and a dehydration ring-closing reaction is performed, so that the amide functional group in the polyimide polymer is converted into an imide functional group (i.e., imidization) through a dehydration ring-closing reaction, and a polyimide polymer is obtained.

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

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

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

Preferred examples of the polyimide block copolymers of the present invention are polyamic acid block copolymers, polyimide block copolymers, polyamic acid-polyimide block copolymers, or any combination thereof.

The preparation of the polyimide block copolymer of the present invention can be a general method. Preferably, the preparation method of the polyimide block copolymer is to first dissolve the starting material in a solvent and perform a polycondensation reaction, wherein the starting material comprises at least one polyamic acid polymer and/or at least one polyimide polymer as described above, and may further comprise a tetracarboxylic dianhydride component (a) and a diamine component (b).

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

Based on the usage of 100 parts by weight of the aforementioned starting material, the usage of the solvent in the polycondensation reaction is preferably 200 parts by weight to 2000 parts by weight, more preferably 300 parts by weight to 1800 parts by weight. The operating temperature of the polycondensation reaction is preferably 0°C to 200°C, and more preferably 0°C to 100°C.

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; (4) polyamic acid polymers, tetracarboxylic dianhydride compounds and diamine compounds, wherein at least one of the tetracarboxylic dianhydride compounds and the diamine compounds is oxidized to form (5) a polyimide polymer, a tetracarboxylic dianhydride compound and a diamine compound, wherein at least one of the tetracarboxylic dianhydride compound and the diamine compound has a structure different from that of the tetracarboxylic dianhydride component (a) and the diamine component (b) used to form the polyimide polymer; (6) a polyimide polymer, a polyimide polymer, A tetracarboxylic dianhydride compound and a diamine compound, wherein at least one of the tetracarboxylic dianhydride compound and the diamine has a structure different from that of the tetracarboxylic dianhydride component (a) and the diamine component (b) used to form the polyamic acid polymer or the polyimide polymer; (7) two polyamic acid polymers, tetracarboxylic dianhydride compounds and diamine compounds having different structures; (8) two polyimide polymers, tetracarboxylic dianhydride compounds and diamine compounds having different structures Compounds; (9) two polyamic acid polymers with different structures and an anhydride group at the end and a diamine compound; (10) two polyamic acid polymers with different structures and an amine group at the end and a tetracarboxylic dianhydride compound; (11) two polyimide polymers with different structures and an anhydride group at the end and a diamine compound; (12) two polyimide polymers with different structures and an amine group at the end and a tetracarboxylic dianhydride compound.

Without affecting the efficacy of the present invention, preferably, the aforementioned polyamic acid polymer, the aforementioned polyimide polymer and the aforementioned polyimide-based block copolymer can be terminal-modified polymers after molecular weight adjustment. By using terminal-modified polymers, the coating performance of the liquid crystal alignment agent can be improved. The method for preparing the aforementioned terminal-modified polymer can be prepared by adding a monofunctional compound to the polyamic acid polymer during the polycondensation reaction. The monofunctional compound includes but is not limited to (1) monobasic acid anhydrides, such as maleic anhydride, phthalic anhydride, itaconic anhydride, n-decylsuccinic anhydride, n-dodecylsuccinic anhydride, n-tetradecylsuccinic anhydride or n-hexadecylsuccinic anhydride; (2) monoamine (3) Monoisocyanate compounds, for example, 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; (4) Monoisocyanate compounds, for example, monoisocyanate compounds such as phenyl isocyanate or naphthyl isocyanate.

The polymer (A) of the present invention has a 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 in terms of polystyrene.

Solvent (B)

There is no particular limitation on the solvent used in the liquid crystal alignment agent of the present invention, as long as it can dissolve the polymer (A) and any other components and does not react with them. It is preferably the same solvent used in the aforementioned synthesis of polyamine. At the same time, the poor solvent used in the synthesis of the aforementioned polyamine can also be used in combination.

Specific examples of the solvent (B) include but are not limited to N-methyl-2-pyrrolidone (NMP), γ-butyrolactone, γ-butyrolactamide, 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, etc.

The aforementioned solvent (B) can be used alone or in combination of two or more.

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

Additives (C)

Within the scope of not affecting the efficacy of the present invention, the liquid crystal alignment agent of the present invention may optionally include an additive (C), and the additive (C) may be an epoxy compound or a silane compound with a functional group. The function of the additive (C) is to improve the adhesion between the aforementioned liquid crystal alignment film and the substrate surface. The additive (C) can be used alone or in combination.

The epoxy compound mentioned above may include but is not limited to ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerol diglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether, 1,3,5,6-tetraglycidyl-2,4-hexanediol, N,N, N',N'-tetracycloxypropyl-m-xylene diamine, 1,3-bis(N,N-dicycloxypropylaminomethyl)cyclohexane, N,N,N',N'-tetracycloxypropyl-4,4'-diaminodiphenylmethane, N,N-cycloxypropyl-p-cycloxypropyloxyaniline, 3-(N-allyl-N-cycloxypropyl)aminopropyltrimethoxysilane, 3-(N,N-dicycloxypropyl)aminopropyltrimethoxysilane, etc.

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

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

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

Based on the usage of polymer (A) being 100 parts by weight, the usage of additive (C) can be 0.5 parts by weight to 50 parts by weight, and preferably 1 part by weight 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. General mixing methods can be used, such as first mixing the tetracarboxylic dianhydride component (a) and the diamine component (b) evenly to react and form a polymer (A). Then, the polymer (A) is added with a solvent (B) and an additive (C) at a temperature of 0°C to 200°C, and stirred continuously with a stirring device until dissolved. Preferably, the polymer (A) and the additive (C) are added to the solvent (B) at a temperature of 20°C to 60°C.

Method for forming liquid crystal alignment film

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

The substrate on which the liquid crystal alignment agent of the present invention is applied is selected from transparent materials, wherein the transparent materials include but are not limited to alkali-free glass, sodium calcium glass, hard glass (Pyles glass), quartz glass, polyethylene terephthalate, polybutylene terephthalate, polyether sulfide, polycarbonate, etc. used in liquid crystal display devices. It is preferred to use the ITO electrode for liquid crystal driving that has been formed on the substrate to simplify the process. Furthermore, for a reflective liquid crystal display with only a single-sided substrate, the aforementioned substrate can use an opaque material such as a silicon wafer. In this case, the electrode can be formed using a material that reflects light such as aluminum. The coating method of the liquid crystal alignment agent of the present invention can be, for example, a spin coating method, a printing method, an inkjet method, etc.

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

Although the liquid crystal alignment agent of the present invention can be subjected to the known rubbing alignment treatment, the effect is better when using the photoalignment treatment method.

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

The liquid crystal alignment agent of the present invention is subjected to pre-baking, post-baking and photo-alignment treatment to form a liquid crystal alignment film, 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 also provides a liquid crystal display element, which includes the aforementioned liquid crystal alignment film.

The manufacturing method of liquid crystal display elements is well known to those in the art, so the following is only briefly described.

Referring to FIG. 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 disposed 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 serrated 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, wherein the transparent materials include but are not limited to alkali-free glass, sodium calcium glass, hard glass (Pyles glass), quartz glass, polyethylene terephthalate, polybutylene terephthalate, polyether sulfide, 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, which function to form a pre-tilt angle for the liquid crystal unit 130, and the liquid crystal unit 130 can be driven by the parallel electric field generated by the electrode 114.

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

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

The following examples are used to illustrate the application of the present invention, but they are not used to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention.

100: Liquid crystal display element

110: Unit 1

112: First substrate

114: Electrode

116: First liquid crystal alignment film

120: Unit 2

122: Second substrate

126: Second liquid crystal alignment film

130: Liquid crystal unit

In order to have a more complete understanding of the embodiments of the present invention and its advantages, please refer to the following description and the corresponding drawings. It must be emphasized that the various features are not drawn to scale and are only for illustration purposes. The contents of the relevant drawings are described as follows: Figure 1 is a schematic diagram of the structure of a liquid crystal display element according to one embodiment of the present invention.

Preparation of polymer (A-1)

Synthesis Example A-1-1

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

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

Synthesis Examples A-1-2 to A-1-15 and Comparative Synthesis Examples A'-1-1 to A'-1-4 use the same preparation method as the preparation method of the polymer (A-1-1) of Synthesis Example A-1-1. The difference is that Synthesis Examples A-1-2 to A-1-15 and Comparative Synthesis Examples A'-1-1 to A'-1-4 change the type and amount of raw materials in the polymer. The formula is shown in Table 1 and is not further described here.

Preparation of polymer (A-2)

Synthesis Example A-2-1

A nitrogen inlet, a stirrer, a condenser and a thermometer were installed on a 500 ml four-necked conical flask, and nitrogen was introduced. Then, 0.87 g (0.0025 mol) of the diamine compound (b-1-4) represented by formula (II-2-12), 0.235 g (0.0005 mol) of the diamine compound (b-2-1) represented by formula (IV-3), 5.076 g (0.047 mol) of p-diaminobenzene (b-3-1) and 80 g of N-methyl-2-pyrrolidone (hereinafter referred to as NMP) were added, and stirred at room temperature until dissolved. Then, 11.2 g (0.05 mol) of the compound (a-1-1) represented by formula (I-1) and 20 g of NMP were added. After reacting at room temperature for 6 hours, 97 grams of NMP, 2.55 grams of acetic anhydride and 19.75 grams of pyridine were added, the temperature was raised to 60°C, and stirring was continued 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 precipitate the polymer. Then, the obtained polymer was filtered, and washed and filtered with methanol three times repeatedly, placed in a vacuum oven, and dried at a temperature of 60°C to obtain polymer (A-2-1), whose formula is shown in Table 1.

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

Synthesis Examples A-2-2 to A-2-5 and Comparative Synthesis Examples A'-2-1 to A'-2-3 use the same preparation method as the preparation method of the polymer (A-2-1) in Synthesis Example A-2-1. The difference is that the types and usage amounts of raw materials in the polymers are changed in Synthesis Examples A-2-2 to A-2-5 and Comparative Synthesis Examples A'-2-1 to A-2-3. The formula is shown in Table 1 and will not be described here.

a-1-1 The compound represented by formula (I-1)

a-1-2 The compound represented by formula (I-2)

a-1-3 The compound represented by formula (I-3)

a-1-4 The compound represented by formula (I-5)

a-1-5 The compound represented by formula (I-8)

a-2-1 Pyromellitic dianhydride

a-2-2 2,3,5-tricarboxycyclopentylacetic acid dianhydride

a-2-3 3,4-dicarboxy-1,2,3,4-tetrahydronaphthalene-1-succinic dianhydride

b-1-1 The compound represented by formula (II-2-1)

b-1-2 The compound represented by formula (II-2-8)

b-1-3 The compound represented by formula (II-2-11)

b-1-4 The compound shown in formula (II-2-12)

b-1-5 The compound represented by formula (II-2-14)

b-1-6 The compound shown in formula (II-2-18)

b-1-7 The compound represented by formula (II-2-19)

b-1-8 The compound represented by formula (II-2-22)

b-1-9 The compound shown in formula (II-2-27)

b-1-10 The compound represented by formula (II-2-28)

b'-1-1

b'-1-2

b'-1-3

b'-1-4

b-2-1 The compound represented by formula (IV-3)

b-2-2 The compound represented by formula (IV-14)

b-2-3 The compound represented by formula (IV-18)

b-2-4 The compound represented by formula (IV-29)

b-2-5 The compound shown in formula (IV-45

b-2-6 The compound represented by formula (IV-46)

b-3-1 p-diaminobenzene

b-3-2 4,4'-diaminodiphenylmethane

b-3-3 1,3-Bis(3-aminophenoxy)benzene

Preparation of liquid crystal alignment agents, liquid crystal alignment films and liquid crystal display elements

Implementation Example 1

Weigh 100 parts by weight of the polymer (A-1-1) prepared in Synthesis Example A-1-1 and 800 parts by weight of NMP (B-1), and stir and mix them at room temperature to prepare the liquid crystal alignment agent of Example 1.

The liquid crystal alignment agent prepared in the above-mentioned Example 1 is rotationally coated on a glass substrate, and the glass substrate has a pixel electrode, wherein the pixel electrode is an IPS driving electrode having a pair of ITO electrodes (electrode width: 10μm, electrode spacing: 10μm, electrode height: 50nm), and the pair of ITO electrodes are respectively in a comb-shaped shape, and the comb-shaped parts of each other are configured in a separated and interlocking manner. Then, the glass substrate coated with the liquid crystal alignment agent is dried on a heating plate at 80°C, and after 5 minutes, it is baked in a hot air circulation oven at 250°C for 60 minutes to form a coating with a film thickness of 100nm.

Through a polarizing plate, the coated surface is irradiated with ultraviolet light of a wavelength of 254nm to produce a substrate with a liquid crystal alignment film. Then, similarly, a coating is formed on the opposite substrate and an alignment treatment is applied. The opposite substrate is a glass substrate without an electrode but with a columnar spacer with a height of 4μm.

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

The obtained liquid crystal display element was evaluated by the following evaluation method, and the results are shown in Table 2. The method for testing the flicker level immediately after driving will be described later.

Examples 2 to 20 and Comparative Examples 1 to 7

Examples 2 to 20 and Comparative Examples 1 to 7 use the same preparation method of the liquid crystal alignment agent, liquid crystal alignment film and liquid crystal display element as Example 1. The difference is that Examples 2 to 20 and Comparative Examples 1 to 7 change the type and amount of raw materials in the liquid crystal alignment agent. The formula and evaluation results are shown in Tables 2 and 3 respectively, and will not be described here.

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

Evaluation method

The flashing degree immediately after driving

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

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

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

※：FL<2%.

◎: 3%>FL≧2%.

○: 4%>FL≧3%.

△: 5%>FL≧4%.

×: FL≧5%.

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

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

In addition, when the diamine component (b) of the liquid crystal alignment agent of the present invention contains a diamine compound (b-2) as shown in formula (IV), the flickering degree of the liquid crystal display element formed immediately after being driven can be further reduced.

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

Although the present invention has been disclosed in the form of implementation as above, it is not intended to limit the present invention. Anyone with common knowledge in the technical field to which the present invention belongs 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 shall be subject to the scope of the patent application attached hereto.

100: Liquid crystal display element

110: Unit 1

112: First substrate

114: Electrode

116: First liquid crystal alignment film

120: Unit 2

122: Second substrate

126: Second liquid crystal alignment film

130: Liquid crystal unit

Claims (10)

A liquid crystal alignment agent comprises: a polymer (A) obtained by a polymerization reaction of a tetracarboxylic dianhydride component (a) and a diamine component (b), wherein the tetracarboxylic dianhydride component (a) comprises at least one tetracarboxylic dianhydride compound (a-1) represented by the following formula (I), and the diamine component (b) comprises a diamine compound (b-1) represented by the following formula (II):

In the formula (I), _R1 to _R4 each independently represents 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, _R1 to _R4 are the same or different, and at least one of _R1 , _R2 , _R3 and _R4 is not a hydrogen atom; _HN2 - _X1 - _M1 - _AM2 - _X2 - _NH2 (II) In the formula (II), _M1 and _M2 each independently represent a single bond, -O-, -S-, _-NM3- , an ester group, an amide group, a thioester group, a urea group, a carbonate group or a carbamate group, wherein _M3 represents a hydrogen atom or a methyl group, and _M1 and M2 are not a hydrogen atom. ₂ may be the same or different; A represents an alkylene group having 2 to 20 carbon atoms; _X1 and _X2 each independently represent a divalent organic group as shown in the following formula (III-1) to (III-19), and _X1 and _X2 are selected from two different structures in formula (III-1) to (III-19), wherein at least one of _X1 and _X2 represents a structure as shown in formula (III-17), formula (III-18) or formula (III-19):

In the formula (III-2), X ₃ represents an alkylene group having 1 to 5 carbon atoms; in the formula (III-14), X ₄ represents a hydrogen atom, a halogen atom, a methyl group, a hydroxyl group or a methoxy group; in the formula (III-17), X ₅ and X ₆ each independently represent a halogen atom, a methyl group, a hydroxyl group or a methoxy group; in the formula (III-18), X ₇ and X ₈ each independently represent a halogen atom, a methyl group, a hydroxyl group or a methoxy group; and a solvent (B). The liquid crystal alignment agent as described in claim 1, wherein the diamine compound (b-1) is selected from the diamine compounds represented by the following formulas (II-1-1) to (II-1-3):

In the formula (II-1-1) to the formula (II-1-3), A, M ₁ , M ₂ , X ₅ , X ₆ , X ₇ and X ₈ are as defined above. The liquid crystal alignment agent as described in claim 1, wherein the diamine component (b) comprises a diamine compound (b-2) represented by the following formula (IV):

In the formula (IV), _Z1 and _Z5 each independently represent a single bond, _-CH2- or _-CH2CH2- ; _Z2 and _Z4 each independently represent _-CH2- or _{-CH2CH2- ; Z3} represents an alkylene group or a cyclohexylene group having 1 to 6 carbon atoms; _Y1 and _Y2 each independently represent a single bond, -O-, -NH-, -N( _CH3 )-, -C(=O)-, -C(=O)O-, -C(=O)NH-, _-C (=O)N( _CH3 )-, -OC(=O)-, -NHC(=O)- or N( _CH3 )C(=O)-; Y ₃ represents a linear alkyl group having 1 to 20 carbon atoms, a branched alkyl group having 3 to 20 carbon atoms, or a cyclic alkyl group having 3 to 20 carbon atoms; and a represents 0 or 1. A liquid crystal alignment agent as described in claim 3, wherein _Y1 and _Y2 independently represent a single bond or -O-. A liquid crystal alignment agent as described in claim 3, wherein a represents 0. The liquid crystal alignment agent as described in claim 1, wherein the amount of the tetracarboxylic dianhydride compound (a-1) used is 10 mol to 100 mol based on the total amount of the tetracarboxylic dianhydride component (a) used is 100 mol, and the amount of the diamine compound (b-1) used is 5 mol to 50 mol based on the total amount of the diamine component (b) used is 100 mol. The liquid crystal alignment agent as described in claim 3, wherein the total usage amount of the diamine component (b) is 100 mol, and the usage amount of the diamine compound (b-2) is 1 mol to 10 mol. The liquid crystal alignment agent as described in claim 1, wherein the total amount of the polymer (A) used is 100 parts by weight, and the amount of the solvent (B) used is 800 parts by weight to 4000 parts by weight. A liquid crystal alignment film formed using a liquid crystal alignment agent as described in any one of claims 1 to 8. A liquid crystal display element, comprising a liquid crystal alignment film as described in claim 9.