TW202118848A - Alignment agent, diamine compound, alignment film and liquid crystal display device - Google Patents

Abstract

An alignment agent includes a first polymer including a side chain structure. The side chain structure includes a piperazinyl group and a structure represented by formula (1), wherein a terminal of the side chain structure is a monovalent organic group having aligning force. In the formula (1), ring A is a divalent organic group having at least one aromatic ring.

Description

Alignment agent, diamine compound, alignment film and liquid crystal display Display element

The present invention relates to an alignment agent, a diamine compound, an alignment film and a liquid crystal display element, and in particular to an alignment agent containing a piperazinyl structure, an alignment film containing the alignment agent, and a liquid crystal display containing the alignment film element.

In a liquid crystal display (liquid crystal display), an alignment film (alignment film) can arrange the liquid crystal molecules into a uniform pre-tilt angle (PTA) alignment. Therefore, the control of the pretilt angle is very important in the liquid crystal display. A liquid crystal display without a pretilt angle is not only prone to abnormal alignment such as underline, black dots, etc., but also has the problem of long liquid crystal response time (RT), which are key factors that affect display quality. For example, Multi-domain Vertical Alignment (MVA) displays use protrusions to adjust the pretilt angle, while Polymer Stabilized Alignment (PSA) displays use reactive liquid crystals ( Reactive The curing process of Mesogen; RM) controls the pretilt angle.

In the past, the industry used the brush film method to generate the alignment ability of the alignment film, but the friction method often affected the yield due to static electricity, fine dust or uneven alignment caused by the friction; then developed the use of polarized light to specific A non-brush-type alignment technology that irradiates the alignment film in the direction of the alignment film to produce alignment capabilities. In an optically aligned vertical liquid crystal display, the alignment film not only needs to provide stable vertical alignment, but also needs to maintain a stable pretilt angle of the liquid crystal after subsequent processes such as applying voltage. Therefore, whether the optical alignment type alignment film can continuously provide a stable pretilt angle under deteriorating conditions is one of the important factors affecting the quality of this type of display. Based on this, providing a photo-alignment film that can continuously provide a stable pretilt angle is currently a subject of active research by those skilled in the art.

According to various embodiments of the present invention, there is provided an alignment agent including a first polymer, which includes a side chain structure, wherein the side chain structure includes a piperazinyl group and a structure represented by formula (1):

且側鏈結構的末端為具有配向力之一價有機基；在式(1)中，環A為含有至少一個芳香環之二價有機基。

And the end of the side chain structure is a monovalent organic group with alignment force; in formula (1), ring A is a divalent organic group containing at least one aromatic ring.

According to various embodiments of the present invention, there is provided a diamine compound having a structure as shown in formula (4) or formula (5):

在式(4)及式(5)中，環A為含有至少一個芳香環之二價有機基；R₇為H或甲基；R₈為單鍵或-CO-；R₉、R₁₁、R₁₂各自獨立為單鍵、-CO-、-O-、-O-CO-、-NH-CO-、-CO-NH-、-O-CO-NH、二價芳香族基、C₁-C₆的伸烷基或二價脂環族基，其中C₁-C₆的伸烷基及二價脂環族基為未取代、或其中不相鄰的-CH₂-基團可各自獨立地被-O-、-CO-、-COO-、-OCO-、NHCO-、-CONH-或S的二價基取代；R₁₀、R₁₃可各自獨立為一價有機基。

In formula (4) and formula (5), ring A is a divalent organic group containing at least one aromatic ring; R ₇ is H or methyl; R ₈ is a single bond or -CO-; R ₉ , R ₁₁ , R _{12 is} each independently a single bond, -CO-, -O-, -O-CO-, -NH-CO-, -CO-NH-, -O-CO-NH, divalent aromatic group, C _1- C ₆ alkylene or divalent alicyclic group, wherein C ₁ -C ₆ alkylene and divalent alicyclic group are unsubstituted or non-adjacent -CH ₂ -groups may be independent of each other Ground is substituted by a divalent group of -O-, -CO-, -COO-, -OCO-, NHCO-, -CONH- or S; R ₁₀ and R ₁₃ may each independently be a monovalent organic group.

According to various embodiments of the present invention, there is provided an alignment film formed by the above-mentioned alignment agent.

According to various embodiments of the present invention, there is provided a liquid crystal display device including the above-mentioned alignment film.

In order to make the description of the present disclosure more detailed and complete, the following provides an illustrative description for the implementation aspects and specific embodiments of the present invention; this is not the only way to implement or use the specific embodiments of the present invention. The embodiments disclosed below can be combined or substituted with each other under beneficial circumstances, and other embodiments can also be added to an embodiment without further description or description.

In this article, unless the article is specifically limited in the context, "一" and "the" can generally refer to one or more. It will be further understood that the terms "include", "include", "have" and similar words used herein indicate the recorded features, regions, integers, steps, operations, elements and/or components, but do not exclude The described or additional one or more other features, regions, integers, steps, operations, elements, components, and/or groups thereof.

In addition, in this article, if it is not specifically specified whether a certain group is substituted, the group can mean a substituted or unsubstituted group. For example, "alkyl" may refer to substituted or unsubstituted alkyl. In addition, when a group is described with "Cx", it means that the main chain of the group has X carbon atoms.

One aspect of the present invention provides an alignment agent including a first polymer; the first polymer includes a side chain structure, and the side chain structure includes a piperazinyl group and a structure represented by formula (1), wherein the side chain structure is The end is a univalent organic group with alignment power.

In formula (1), ring A is a divalent organic group containing at least one aromatic ring. Specifically, it can be a monocyclic or condensed ring. The carbon element in the aforementioned aromatic ring can also be replaced by a non-carbon element ( Such as oxygen, nitrogen, sulfur), for example, ring A can be benzene ring, naphthalene ring, indane ring (indane), indole, isoindole, benzothiophene, benzimidazole, quinoline, benzo Dioxane or indene, and non-adjacent -CH ₂ -groups in ring A may each be independently substituted with -O- or -C=O-.

In some embodiments, the first polymer includes at least one selected from the group consisting of polyacrylic acid, poly(meth)acrylic acid, polyamide, polyamide acid, polyimide, and copolymers thereof.

In some embodiments, the side chain structure of the first polymer includes at least one of the structures shown in formula (2) and formula (3):

In formula (2) and formula (3), the dotted line indicates the position of the bond to the main chain of the first polymer, wherein R ₁ is a single bond or -CO-. R ₂ , R ₄ , and R ₅ are each independently a single bond, -CO-, -O-, -O-CO-, -NH-CO-, -CO-NH-, -O-CO-NH, divalent aromatic Group, C ₁ -C ₆ alkylene group or divalent alicyclic group, wherein C ₁ -C ₆ alkylene group and divalent alicyclic group are unsubstituted or non-adjacent among them -CH ₂ -The groups can each be independently substituted with a divalent group of -O-, -CO-, -COO-, -OCO-, NHCO-, -CONH- or S; R ₃ is a monovalent organic group; R ₆ is one Valence organic base.

When the side chain structure of the aforementioned first polymer has a certain sufficient length, the alignment film can be irradiated to generate alignment force. In some examples, _{the chain length of R 3} in formula (2) is greater than 5 Å, and formula ( 3) _{The chain length of R 6 is} greater than 9Å. Specifically, the chain length referred to here is to draw the structure of formula (2) or formula (3) into Chemdraw software, and then use the software to convert it into a 3D structure, and calculate the first of R ₃ or R ₆ The distance from the carbon atom to the most terminal carbon atom.

_{In some examples, R 3} in formula (2) or formula (3) may be a monovalent organic group containing alkyl, ether, aliphatic, and aromatic groups with a chain length greater than 5 Å, preferably including A monovalent organic group with a liquid crystal structure; R ₆ can be a monovalent organic group containing alkyl, ether, aliphatic, and aromatic groups with a chain length greater than 9Å, preferably a monovalent organic group containing a liquid crystal structure Base, can provide better liquid crystal compatibility and alignment. Specifically, the mesogenic unit structure refers to the structure that can promote the liquid crystallinity of the molecules in the molecular structure. For example, the mesogenic unit may include multiple five-membered rings or multiple six-membered rings; five-membered rings For example, furan, tetrahydrofuran, cyclopentane, pyrrole, tetrahydropyrrole, thiophene, tetrahydrothiophene, etc.; six-membered ring such as cyclohexane, benzene ring, heteroatom-substituted cyclohexane or benzene ring, etc.; the above-mentioned ring It can be directly combined with the ring, such as naphthalene ring, indene ring, 2,5-benzofuran, dioxa-saturated indene ring, hexahydroindene, dioxa-saturated naphthalene ring, bicyclo[3.3.0]oct-7- Alkenes, dioxa-bicyclo[2.2.2]octane, trioxa-bicyclo[2.2.2]octane, etc. In addition, the ring and the ring can be connected through a linking group. The linking group is, for example, a single bond, a C ₁ -C ₄ alkylene group, a C ₂ -C ₄ alkenylene group, and a C ₂ -C ₄ alkynylene group. , -O-CO-, -CO-O-, -CF ₂ O- or -OCF ₂ -. Generally speaking, the liquid crystal group may include two to five ring structure units, preferably two to four rings, and these rings may have the same or different structures.

In some embodiments, the first polymer is obtained by reacting a diamine compound with a tetracarboxylic dianhydride compound, and the first polymer includes At least one of the group consisting of polyamide acid, polyimide and their copolymers, wherein the diamine compound includes at least one of the first diamine compounds represented by formula (4) and formula (5) One:

In formula (4) and formula (5), ring A is a divalent organic group containing at least one aromatic ring; R ₇ is H or methyl; R ₈ is a single bond or -CO-; R ₉ , R ₁₁ , R _{12 is} each independently a single bond, -CO-, -O-, -O-CO-, -NH-CO-, -CO-NH-, -O-CO-NH, divalent aromatic group, C _1- C ₆ alkylene or divalent alicyclic group, wherein C ₁ -C ₆ alkylene and divalent alicyclic group are unsubstituted or non-adjacent -CH ₂ -groups may be independent of each other Ground is substituted by a divalent group of -O-, -CO-, -COO-, -OCO-, NHCO-, -CONH- or S; R ₁₀ and R ₁₃ may each independently be a monovalent organic group.

In some embodiments, the equivalent ratio of the diamine compound to the tetracarboxylic dianhydride compound described in paragraph [0018] is about 0.5 to 2, preferably 0.7 to 1.5; wherein the first diamine compound accounts for all The proportion of all diamine compounds in the polymer is at least 5 mol%, preferably 5 mol% to 50 mol%.

In some embodiments, the cyclization rate (imination rate) of the first polymer described in paragraph [0018] is 10% or more, preferably 40% or more, more preferably 60% or more, and most preferably More than 80%.

In some embodiments, the above-mentioned tetracarboxylic dianhydride compound may It includes at least one of the tetracarboxylic dianhydride compounds 6-1 to 6-6 shown in Table 1 below, but the present invention is not limited thereto.

In some embodiments, in addition to the first diamine compound represented by the above formula (4) and formula (5), the diamine compound may further include the second diamine compound 7 shown in Table 2 below as necessary. -1~7-8, at least one of C, but the present invention is not limited to this.

In some embodiments, the alignment agent further includes a second polymer, and the second polymer does not have the side chain structure represented by the above formula (2) and formula (3). In other embodiments, the aforementioned second polymer can be obtained by reacting a diamine compound with a tetracarboxylic dianhydride compound, and the aforementioned diamine compound does not include the second polymer shown in the aforementioned formulas (4) and (5). A diamine compound.

In some embodiments, the tetracarboxylic dianhydride compound that is reacted with the diamine compound to obtain the second polymer may include any tetracarboxylic dianhydride compound, for example, the tetracarboxylic dianhydride compound shown in Table 1 above At least one of 6-1 to 6-6, but the present invention is not limited thereto.

In some embodiments, the above-mentioned diamine compound reacted with the tetracarboxylic dianhydride compound to obtain the second polymer may include in addition to the above-mentioned formula (4) And any diamine compounds other than the first diamine compound represented by formula (5), for example, at least one of the second diamine compounds 7-1 to 7-8 and C shown in Table 2 above, but The present invention is not limited to this.

Specifically, the first polymer may include polyamide acid, polyimine, polyamide acid, and polyamide, depending on the degree of polymerization reaction and dehydration and ring-closure reaction of the diamine compound and the tetracarboxylic dianhydride compound in an organic solvent. A copolymer of polyimide, or a mixture of polyimide and polyimide. In other words, in addition to the polymerization reaction of the diamine compound and the tetracarboxylic dianhydride compound, the subsequent dehydration ring-closure reaction may also be included.

In some embodiments, the synthesis of polyamide acid and polyimide is completed by reaction in an organic solvent, and the organic solvent used is divided into organic solvents with higher solubility and lower solubility. Organic solvents with better solubility for polyamide acid and polyimine include N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl Base caprolactam, dimethyl sulfide, tetramethylurea, hexamethylphosphoramide, γ -butyrolactone, pyridine, etc., and the above solvents can be used in combination of two or more. It should be understood that the solvent is not limited to the above, as long as the solvent can dissolve polyamide acid and polyimide can be used.

Solvents with low solubility of polyimide and polyimide can also be used in combination with the aforementioned organic solvents, and their use is limited to the fact that polyimide and polyimide will not be separated out. Solvents with lower solubility include methanol, ethanol, isopropanol, n-butanol, cyclohexanol, ethylene glycol, ethylene glycol methyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethyl Glycol dimethyl ether, ethylene glycol diethyl ether, diethyl ether, acetone, methyl ethyl ketone, cyclohexanone, acetic acid Methyl ester, ethyl acetate, tetrahydrofuran, dichloromethane, chloroform, 1,2-dichloroethane, benzene, toluene, xylene, n-hexane, n-heptane, n-octane, etc.

In detail, the formation of polyimine requires a dehydration ring-closure reaction, and the dehydration ring-closure reaction can be carried out by directly heating the dehydration ring-closing reaction, or adding a dehydrating agent and a catalyst to perform the dehydration ring-closure reaction, as described below.

The reaction temperature for heating, dehydration and ring closure is about 50 to 300°C, preferably about 100 to 250°C. When the reaction temperature is lower than 50°C, the dehydration and ring closure reaction will not proceed.

The reaction temperature of adding dehydrating agent and catalyst for dehydration and ring closure is about -20 to 150°C, preferably 0 to 120°C. As the dehydrating agent, acid anhydride or alkylbenzene, such as toluene, acetic anhydride, propionic anhydride, and trifluoroacetic anhydride, can be used. The amount of dehydrating agent depends on the required ring-closure rate. Among them, it is better to use 0.01-20 moles of dehydrating agent per 1 mole of polyimide-polyamide acid reproduction unit; the catalyst can use tertiary amine, Such as triethylamine, pyridine, and lutidine. The amount of catalyst is preferably 0.01-10 mol of catalyst per 1 mol of dehydrating agent.

The purification of polyimine, polyamic acid, copolymers or mixtures thereof is to pour the reaction solvent of polyimine and polyamic acid into a large amount of solvents with poor solubility to obtain a precipitate. Afterwards, it is dried under reduced pressure to obtain polyimide, polyamide acid, copolymers or mixtures thereof. Dissolve polyimide, polyamide acid, copolymers or mixtures thereof in an organic solvent, and perform precipitation with a solvent with poor solubility. This step can be performed one or more times to purify polyimide, polyamide acid, copolymers or mixtures thereof. Finally, the solubility is better The solvent dissolves polyimide, polyamic acid, their copolymers or mixtures.

_{The viscosity (η ln} ) of the alignment agent of the present invention is derived from the viscosity of an N-methyl-2-pyrrolidone solution with a concentration of 0.5 g/100 ml measured at 30° C. with the following formula (A).

The solid content of the alignment agent of the present invention selected according to viscosity and volatility can be 1-30% by weight, preferably 1-15% by weight. The alignment agent of the present invention is coated on a substrate to form a film, which is an alignment film. When the solid content of the alignment agent is less than 1% by weight, the coating thickness of the alignment film is too thin, which reduces the alignment of the liquid crystal; and when the solid content of the alignment agent is higher than 15% by weight, the coating will be affected. Quality: The temperature for preparing the alignment agent of the present invention is preferably about 0~150°C, more preferably 20~50°C.

In some embodiments, the alignment agent further comprises an organic solvent, including N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-propyl-2-pyrrolidone, and N-isopropyl-2-pyrrolidone , N-cyclohexyl-2-pyrrolidone, N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide, N-methylcaprolactone Amine, dimethyl sulfide, γ-butyrolactone, γ-butyrolactone, propylene carbonate, 3-methoxy-N,N-dimethylpropanamide, 3-propoxy-N, N-dimethyl acrylamide, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-n-propyl ether, ethylene glycol monobutyl ether, etc. The above solvents can be mixed with two or more Use; In addition to the above solvents, as long as it can dissolve polyimide, polyamide acid, their copolymers or mixtures can be used.

In addition, in some embodiments, the alignment agent may optionally contain other components, such as organosilicon (oxy) alkane compounds, epoxy compounds, or polysiloxanes.

The organosilicon (oxy)alkane compound is not particularly limited, and may be, for example, aminopropyltrimethoxysilane, aminopropyltriethylsilane, vinylmethylsilane, N-(2-aminoethyl) -3-Aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, vinyltriethoxysilane, 3-methylpropene Glyoxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxy Cyclohexyl) ethyl trimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-ethoxycarbonyl-3-aminopropyltrimethoxysilane , N-ethoxycarbonyl-3-aminopropyl triethoxyamine silane, N-triethoxysilylpropyl triethylenetriamine, N-trimethoxysilylpropyl triethylene Ethyl triamine, N-bis(oxyethylene)-3-aminopropyltrimethoxysilane, N-bis(oxyethylene)-3-aminopropyltriethylsilane, etc.; the foregoing The addition of organosilicon (oxy) alkane compound to the alignment agent can improve the adhesion of the alignment film to the surface of the substrate without affecting the required characteristics of the alignment film; the concentration of the organosilicon (oxy) alkane compound of the alignment agent of the present invention , Relative to the weight of all polymers in the alignment agent, 0.01~5 wt% is preferred, and 0.1~3 wt% is particularly preferred.

The epoxy compound is not particularly limited, and may be, for example, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene 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 - inter - benzene, xylene, 1,3-bis (N, N- diglycidyl aminomethyl) cyclohexane, N, N, N ', N' - tetraglycidyl-4,4 '- diamino diphenyl methane, Epiclon series (e.g., N-695, N-740, EXA4850, HP-4710, HP-6000), 3- (N- -allyl - N-glycidyl)aminopropyltrimethoxysilane, 3-(N,N-diglycidyl)aminopropyltrimethoxysilane; the aforementioned alignment agent of the present invention may optionally be added with epoxy compounds, The concentration of addition relative to the total weight of the alignment agent is preferably 0.01 to 3% by weight, and particularly preferably 0.1 to 2% by weight. The addition of the aforementioned epoxy compound to the alignment agent can improve the adhesion of the alignment film to the surface of the substrate and increase the hardness of the alignment film without affecting the required characteristics and compatibility of the alignment film.

The polysiloxane is not particularly limited. For example, it may have a chemical formula of _{R 1} R ₂ R ₃ SiR _{4 , wherein R 1} -R ₄ may include but are not limited to alkyl, alkoxy, and hydroxyl. , Aromatic group, aliphatic group, alicyclic group, aliphatic aromatic group, epoxy group, epoxy heterocyclic group or liquid crystal group, etc.; the polysiloxane concentration of the alignment agent of the present invention is relative to the alignment agent The total weight is preferably 0.05 to 5% by weight, more preferably 0.1 to 1% by weight. The above content of polysiloxane in the alignment agent can improve the coating characteristics of the alignment film on the surface of the substrate or the electrical properties of the liquid crystal cell, without affecting the characteristics and compatibility required by the alignment film.

Another aspect of the present invention provides an alignment film, which is formed by any of the alignment agents in the above-mentioned embodiments; the alignment film can be made by coating the aforementioned alignment agent on a substrate and heating and baking it. .

Another aspect of the present invention provides a liquid crystal display device including the above-mentioned alignment film; the liquid crystal display device can be manufactured by the following method.

The above-mentioned alignment agent is applied to a glass substrate with a patterned transparent conductive film by a method such as a roller coating method, a spin coating method, or a spray printing method. Then, a thin film is formed by heating and baking. The organic solvent in the alignment agent can be removed by heating and baking, and the polyamide acid is promoted to undergo dehydration and ring-closing reaction. The heating and baking temperature is 80~300℃, with 100~240℃ being the best. The thickness of the formed film is preferably 0.005~0.5 microns.

The formed thin film can be irradiated with light to promote the occurrence of photo-alignment to obtain a photo-alignment film. This step is to enable the film to provide the alignment of liquid crystal molecules. The photo-alignment is described in detail as follows.

(1) The light source of the photo-alignment can be UV light, but the wavelength is not particularly limited, as long as the photoreaction can be promoted; the wavelength of the light source is preferably 280nm-400nm, preferably 300, without damaging or degrading the film. -360nm.

(2) The light source of optical alignment is mainly incident in the normal direction of the inclined film, and the incident angle is not limited. The incident angle is preferably 30-60 degrees, and 40-50 degrees is better.

(3) There is no specific restriction on the directivity of the light source for optical alignment, and the use of a linearly polarized light source has better results.

After that, apply sealant on a substrate with the aforementioned alignment film, spray spacers on the other substrate with the aforementioned alignment film, and then combine the two alignment film substrates in a photo-alignment perpendicular to each other or parallel to each other, and Liquid crystal is injected into the gap, and then the injection hole is sealed to form a liquid crystal display element.

Instance

The following embodiments are used to describe specific aspects of the present invention, and to enable those skilled in the art to which the present invention belongs to implement the present invention. However, the following examples should not be used to limit the present invention.

Synthesis of the first diamine compound A1

The synthesis of the first diamine compound A1 includes the following steps.

Synthesis of compound a-1:

The equivalent of 1-fluoro-2,4-dinitrobenzene (DNFB) and 4-(1-piperazinyl)phenol (4-(1-Piperazinyl)phenol; PPOH) was reacted under Dimethylacetamide (DMAc), and triethylamine (TEA) (1.2eq) was added. After 16 hours of reaction, all volatiles were removed, water was added to wash the solid, and ethyl acetate was added. After (EA) extraction, concentration, and recrystallization, compound a-1 can be obtained as an orange solid.

Synthesis of compound a-2:

Add p-(4-n-pentyl-cyclohexyl)-bromobenzene (p-(4-n-pentyl-cyclohexyl)-bromobenzene; 5CPBr) (1.0eq), palladium chloride (PdCl ₂ ) (0.01 eq), Tri-o-tolyl phosphine (Tri-o-tolyl phosphine; P-(o-tol) ₃ ) (0.02eq), followed by deoxygenated toluene, triethylamine (TEA) (4eq) , Acrylic acid (AA) (1.5eq) was added to the reaction flask. Heat to reflux, after reacting for 6 hours, add 1N HCl to adjust the pH to weak acidity, and extract with tetrahydrofuran (THF). Collect the organic layer and wash with saturated experimental water. After drying with anhydrous magnesium sulfate, the volatiles are drained. Later, compound a-2 can be obtained as a white solid.

Synthesis of compound a-3:

Compound a-2 (1.0eq), N,N-dimethylformamide (DMF) (catalyst) were dissolved in dichloromethane (DCM), and ethylenedichloride (COCl) ₂ was slowly added under ice bath. Drop in and return to room temperature naturally. After reacting for 2 hours, the reaction solution was slowly dropped into the DCM solution of compound a-1 (1.0 eq) and TEA (3.0 eq) under an ice bath, and reacted for 16 hours. Water was added for extraction, and the organic layer was collected. After all volatiles were drained, the solid was rinsed with methanol (MeOH) and dried to obtain compound a-3 as an orange solid.

Synthesis of the first diamine compound A1:

Put compound a-3 (1.0 eq) and ammonium chloride (5.0 eq, 50% aqueous solution) into the reaction flask, and add a mixed solution of tetrahydrofuran/methanol (THF/EtOH) (2/1). Under nitrogen, zinc powder (20eq) was added and stirred for 16 hours. Filter and collect the filtrate, wash the filtrate with water, and drain the filtrate to obtain the first diamine compound A1.

Synthesis of the first diamine compound A2

The method of synthesizing the first diamine compound A2 is the same as the method of synthesizing the first diamine compound A1 described above. The difference is that p-(4-propyl-cyclohexyl)-bromobenzene (p-(4-propyl-cyclohexyl)-bromobenzene; 3CPBr) is used to synthesize the first diamine compound A1. ) Substituting p-(4-n-pentylcyclohexyl)bromobenzene (5CPBr) to form compound a-4, substituting compound a-4 for compound a-2 to form compound a-5, and substituting compound a-5 for compound a-3 forms the first diamine compound A2, and its structure is shown below.

Synthesis of the first diamine compound A3

The method of synthesizing the first diamine compound A3 is the same as the method of synthesizing the first diamine compound A1 above. The difference is that 4-[4-(4-propylcyclohexyl)cyclohexyl]bromobenzene (4-[4-(4 -Propylcyclohexyl)cyclohexyl]-bromobenzene; 3CCPBr) replaces p-(4-n-pentylcyclohexyl)bromobenzene (5CPBr) to form compound a-6, and replace compound a-2 with compound a-6 The compound a-7 is formed, and the compound a-3 is substituted with the compound a-7 to form the first diamine compound A3, the structure of which is shown below.

Synthesis of the first diamine compound A4

The method of synthesizing the first diamine compound A4 is the same as the method of synthesizing the first diamine compound A1 above, the difference is that compound a-8 is substituted for compound a-1 to form compound a-9, and compound a-9 is substituted for compound a- 3 to form the first diamine compound A4.

The synthesis of compound a-8 is as follows. The equivalent of DNFB was reacted with N-(2-hydroxyethyl)piperazine (P2OH) in THF, and TEA (1.2eq) was added. After 16 hours of reaction, all volatilization was removed After adding water to wash the solid, and extracting with EA, after concentration and recrystallization, compound a-8 can be obtained as a yellow solid, the structure of which is shown below.

Synthesis of the first diamine compound B1

The synthesis of the first diamine compound B1 includes the following steps, and its structure is shown below.

Synthesis of compound b-1: Place 1-Phenylpiperazine (PP) (1.1eq) and DCM in the reaction flask In an ice bath, 1-Bromo-2,5-pyrrolidinedione (1-Bromo-2,5-pyrrolidinedione; NBS) (1.0 eq) in DCM was slowly dropped into the solution and reacted for 16 hours. The solid was collected by filtration, and the solid was washed with DCM several times. After the solid was sucked dry, compound b-1 was obtained as a pale yellow solid.

Synthesis of compound b-2: the same as the synthesis procedure of compound a-1 above, the difference is that compound b-1 is substituted for PPOH to obtain compound b-2 as a yellow solid.

Synthesis of compound b-3: Place 4-(4-propylcyclohexyl)cyclohexanol (4-(4-propylcyclohexyl)cyclohexanol; 3CCOH) (1.0eq), TEA (2.0eq) into the reaction flask, and Join DCM. Acryloyl chloride (AACl) (2.0 eq) was slowly dropped in an ice bath, returned to room temperature naturally, and reacted for 8 hours. After adding water for extraction, the organic layer is collected, concentrated and recrystallized to obtain compound b-3 as a beige solid.

Synthesis of compound b-4: the same as the synthesis procedure of compound a-2 above, the difference is that compound b-2 is substituted for p-(4-n-pentylcyclohexyl)bromobenzene (5CPBr) and compound b-3 is substituted AA, compound b-4 can be obtained as a dark yellow solid.

Synthesis of the first diamine compound B1: the same as the above-mentioned synthesis step of the first diamine compound A1, the difference is that compound b-4 is substituted for compound a-3.

Synthesis of the second diamine compound C

The synthesis of the second diamine compound C includes the following steps, and its structure is shown below.

Synthesis of compound c-1: The equivalent of DNFB and 2-Benzylaminoethanol (N2OH) were reacted in THF, and TEA (1.2eq) was added. After 16 hours of reaction, all volatiles were removed and added The solid was washed with water, extracted with EA, concentrated and recrystallized to obtain compound c-1 as a yellow solid.

Synthesis of compound c-2: same as the synthesis procedure of compound a-3 above, the difference is that compound c-1 is substituted for compound a-1.

Synthesis of the second diamine compound C: the same as the above-mentioned synthesis step of the first diamine compound A1, the difference is that compound c-2 is substituted for compound a-3.

Polymer 1~20

Combine the tetracarboxylic dianhydride compounds 6-1~6-6 shown in Table 1 above and the second diamine compounds 7-1~7-8, C shown in Table 2 and the above first diamine compounds A1~A4 , B1 is added to N-methyl-2-pyrrolidone in sequence according to the molar equivalent shown in Table 3 to prepare a solution with a solid content of 15% by weight, and react at 40°C for 5-6 hours to obtain Polyamide acid. If necessary, after diluting the polyamide acid solution, add appropriate proportions of reagents, such as but not limited to pyridine and acetic anhydride, and perform dehydration/cyclization reaction at 100~110℃ for 3~4 hours; or add Proper proportion of azeotropic solvent, such as toluene or xylene, etc., carry out dehydration/cyclization reaction at the azeotropic temperature of water and azeotropic solvent for 3~4 hours, and then remove the catalyst or azeotropic solvent to obtain the polymer Imine. The regulation method of the cyclization rate is a technique well known in the art, and will not be repeated here. Of Afterwards, the solution can be poured into ethanol for precipitation, washed and purified with ethanol, and finally the solid is collected and dried under reduced pressure to obtain the target polymer.

Examples 1 to 19 and Comparative Examples 1 to 2

Dissolve the above polymer in solvents such as N-methyl-2-pyrrolidone and ethylene glycol monobutyl ether according to the weight percentages shown in Table 4 below to prepare a solution with a solid content of 6% by weight, with a diameter of 1 micron The filter is filtered, and the collected filtrate is the alignment agent of the present invention.

The alignment agent of the above-mentioned examples and comparative examples was applied on the patterned transparent electrode substrate by a spin coater, and dried at 90°C/120 seconds, and cured at 230°C/30 minutes to form a thickness of 1000± 100Å alignment film. The film is optically aligned with a linearly polarized light, incident obliquely 50 degrees according to the normal direction of the film, a light source with a wavelength of 313 nm and an exposure energy of 20 mJ to form a liquid crystal alignment film.

Afterwards, apply sealant on the substrate of the aforementioned liquid crystal alignment film, spray spacers on the other substrate of the aforementioned liquid crystal alignment film, and continue to combine the two liquid crystal alignment film substrates perpendicular to each other in the alignment direction, and in the gap Inject liquid crystal and seal the injection hole to form a liquid crystal display element. Liquid crystal obtained The display element uses the following characteristics as evaluation indicators, the evaluation method is described as follows, and the results are shown in Table 5 below.

(1) Orientation evaluation: Place the liquid crystal display element between polarizers perpendicular to each other, and apply voltage to observe the uniformity of the display screen. The brightness is even better. If there is poor alignment or dark spots, Is bad.

(2) Pretilt angle (PTA) measurement method: Use a pretilt angle measuring instrument (model Autronic TBA-107) to evaluate the pretilt angle of the liquid crystal display element with different phase differences. If the pretilt angle is 90±2 degrees, It means that the liquid crystal display element has good vertical alignment ability.

(3) Ion density (ID) measurement method: the liquid crystal display element is measured with a liquid crystal material parameter tester (model ALCT-IV1, manufactured by Instec), which uses a liquid crystal material parameter tester to apply a triangular waveform Measure the ion density of the liquid crystal display element placed in a 60°C oven. When the ID is less than or equal to 5000pC, it can meet the demand.

(4) Measuring method of voltage holding rate (VHR-1V) under 1V: connect the liquid crystal display element to AC with a voltage of 1V and a frequency of 0.6Hz, and measure the attenuation rate of the voltage in each half-cycle by area calculation , When VHR-1V is greater than or equal to 85%, the demand can be met.

(5) Measuring method of voltage holding rate (VHR-5V) under 5V: connect the liquid crystal display element with alternating current with a voltage of 5V and a frequency of 0.6Hz, and measure the attenuation rate of the voltage in each half cycle by area calculation , When VHR-5V is greater than or equal to 95%, the demand can be met.

(6) Measuring method of residual DC voltage (RDC): Place the liquid crystal display element in an oven at 60℃, apply a 5V DC voltage for 1 hour, and then After discharging for 1 second, record the residual DC voltage value after 10 minutes. When the RDC is less than or equal to 100mV, it can meet the demand.

(7) Reliability evaluation method: The liquid crystal display element is placed in a high temperature and high humidity environment with a temperature of 121°C and a humidity of 100% for 6 hours to conduct a deterioration test, and measure the voltage retention rate. The measurement method is the same as the voltage retention rate measurement. Method of measurement.

(8) The evaluation methods of optical alignment stability include:

(a) Measuring the response time (RT) of the liquid crystal display element: At 60°C, the liquid crystal display element was subjected to a deterioration test with a voltage of 20V and a frequency of 60 Hz for 72 hours, and the response time (RT) change was evaluated. When the response time changes less than 1.5ms, the demand can be met.

(b) Measure the pretilt angle. At 60°C, an alternating current with a voltage of 20V and a frequency of 60Hz was applied to the liquid crystal display element for 72 hours to perform a deterioration test, and the change in the pretilt angle (PTA) was evaluated. When the PTA change is less than 0.3 degrees, the demand can be met.

In Table 5 above, Examples 1 to 3 are further compared. It can be seen from Table 5 that when the first polymer of the alignment agent is the same, the performance of the second polymer synthesized using the second diamine compound 7-3 (Example 2) is slightly better than that of using the second diamine compound 7 -2 (Example 1) and the second diamine compound 7-8 (Example 3).

Further compare Examples 1, 4, and 5. It can be seen from Table 5 that when the second polymer of the alignment agent is the same, the performance of the first polymer using the first diamine compound A1 (Example 1) is better than that of using the first diamine compound A4 (Example 4). In addition, in the performance of rising response time (T on), the use of the first diamine compound A1 (Example 1) is better than the use of the first diamine compound A4 (Example 4), and the use of the first diamine compound A4 ( Example 4) is superior to the first diamine compound B1 (Example 5).

Further compare Examples 3, 6-9, 13, and 14. It can be seen from Table 5 that when the second polymer of the alignment agent is the same, in the performance of photo-alignment and photo-alignment stability, the first polymer using the first diamine compound A3 (Example 9) is better than Use the first diamine compound A1 (Example 3, 6, 7), the first diamine compound A2 (Example 8). Therefore, the first polymer containing the 3CC structure (that is, the terminal structure of the first diamine compound A3) can improve the performance of rising response time (T on).

Further compare Examples 7, 15-19. It can be seen from Table 5 that Examples 15-19 with high cyclization rate (60%) have better performance.

Further compare Example 1 and Comparative Example 1. It can be seen from Table 5 that when the second polymer of the alignment agent is the same, the first polymer with a piperazinyl structure of the present invention (Example 1) has both performance in rising response time (T on) and photo alignment stability. It is significantly better than Comparative Example 1 which does not have a piperazinyl structure.

Furthermore, Example 7 and Comparative Example 2 are compared. It can be seen from Table 5 that when the second polymer of the alignment agent is the same, the performance of the first polymer having a piperazinyl structure of the present invention (Example 7) in the rising response time (T on) and photo-alignment stability Both are significantly better than Comparative Example 2 which does not have a piperazinyl structure.

As described above, according to an embodiment of the present invention, the alignment agent of the present invention includes a first polymer whose side chain structure includes a piperazinyl structure. Under severe deteriorating conditions, compared with the general carbon chain structure, the cyclic structure of piperazine is more restricted in movement under the conditions of heat or applied electric field, and has higher stability. It still has better pretilt angle stability under deteriorating conditions, and can maintain stable pretilt angle and response time. The alignment film formed by the alignment agent can make the liquid crystal display device have good vertical alignment ability, alignment (photoalignment), voltage retention, and lower residual DC voltage. In addition, the liquid crystal display element of the present invention also has Good electrical properties, short response time and excellent stability, etc., have good display quality.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention. Anyone who is familiar with the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection of the present invention The scope shall be subject to the definition of the attached patent application scope.

Claims (13)

A aligning agent containing: A first polymer comprising a side chain structure, the side chain structure comprising a piperazinyl group and a structure represented by formula (1), wherein the end of the side chain structure is a monovalent organic group with alignment force,

In formula (1), ring A is a divalent organic group containing at least one aromatic ring. The alignment agent of claim 1, wherein the side chain structure includes at least one of the structures shown in formula (2) and formula (3):

In formula (2) and formula (3), the dotted line indicates the position of the main chain of the first polymer; R ₁ is a single bond or -CO-; R ₂ , R ₄ , and R ₅ are each independently a single bond, -CO-, -O-, -O-CO-, -NH-CO-, -CO-NH-, -O-CO-NH, divalent aromatic Group, C ₁ -C ₆ alkylene group or divalent alicyclic group, wherein C ₁ -C ₆ alkylene group and divalent alicyclic group are unsubstituted or non-adjacent among them -CH ₂ -The groups can each be independently substituted by a divalent group of -O-, -CO-, -COO-, -OCO-, NHCO-, -CONH- or S; R ₃ is a monovalent organic group; and R ₆ is a monovalent organic group. The alignment agent of claim 2, wherein in formula (2), R ₃ and R ₆ are each independently a monovalent organic group including a liquid crystal group structure. Such as the alignment agent of claim 2, wherein in formula (2), R ₃ has a chain length greater than 5 Å, and in formula (3), R ₆ has a chain length greater than 9 Å. The alignment agent of claim 1, wherein the first polymer is selected from the group consisting of polyacrylic acid, poly(meth)acrylic acid, polyamide, polyamide acid, polyimide and copolymers thereof At least one of. The alignment agent of claim 5, wherein the first polymer is selected from the group consisting of polyamides, polyimines and copolymers thereof obtained by reacting a diamine compound with a tetracarboxylic dianhydride compound At least one of The diamine compound includes at least one of the first diamine compounds represented by formula (4) and formula (5):

In formula (4) and formula (5), R ₇ is H or methyl; R ₈ is a single bond or -CO-; R ₉ , R ₁₁ , and R ₁₂ are each independently a single bond, -CO-, -O-, -O-CO-, -NH-CO-, -CO-NH-, -O-CO-NH, divalent aromatic Group, C ₁ -C ₆ alkylene group or divalent alicyclic group, wherein C ₁ -C ₆ alkylene group and divalent alicyclic group are unsubstituted or non-adjacent among them -CH ₂ -The groups can each be independently substituted by a divalent group of -O-, -CO-, -COO-, -OCO-, NHCO-, -CONH- or S; R ₁₀ is a monovalent organic group; and R ₁₃ is a monovalent organic group. The alignment agent of claim 6, wherein the equivalent ratio of the first diamine compound to the tetracarboxylic dianhydride compound is about 0.5-2. The alignment agent of claim 6, wherein the cyclization rate of the first polymer is more than 10%. Such as the alignment agent of claim 1, further comprising a second polymer, and the second polymer does not have the side chain structure shown in formula (2) and formula (3). The alignment agent of claim 9, wherein the second polymer is obtained by reacting a second diamine compound with a tetracarboxylic dianhydride compound, and the second diamine compound does not include formulas (4) and (5) First diamine shown Compound. A diamine compound having a structure as shown in formula (4) or formula (5):

In formula (4) and formula (5), ring A is a divalent organic group containing at least one aromatic ring; R ₇ is H or methyl; R ₈ is a single bond or -CO-; R ₉ , R ₁₁ , and R ₁₂ are each independently a single bond, -CO-, -O-, -O-CO-, -NH-CO-, -CO-NH-, -O-CO-NH, divalent aromatic Group, C ₁ -C ₆ alkylene group or divalent alicyclic group, wherein C ₁ -C ₆ alkylene group and divalent alicyclic group are unsubstituted or non-adjacent among them -CH ₂ -The groups can each be independently substituted by a divalent group of -O-, -CO-, -COO-, -OCO-, NHCO-, -CONH- or S; R ₁₀ is a monovalent organic group; and R ₁₃ is a monovalent organic group. An alignment film formed by the alignment agent according to any one of claim 1 to claim 10. A liquid crystal display element comprising the alignment film according to claim 12.