TWI417317B - Aromatic diamine compound, polyamic acid and polyimide prepared using the same and liquid crystal alignment agent - Google Patents

Description

Aromatic diamine compound, polylysine prepared by using the aromatic diamine compound, polyimine and liquid crystal alignment agent

The present invention relates to an aromatic diamine compound, a polyamic acid prepared by using the aromatic diamine compound, a polyimine (PI), and a liquid crystal alignment agent, and particularly relates to a kind An aromatic diamine compound which can improve the performance of a liquid crystal display element, a polyphthalic acid prepared from the aromatic diamine compound, a polyimine, and a liquid crystal alignment agent.

Liquid crystal display (liquid crystal display) is a display that utilizes photoelectric change of liquid crystal. It has the advantages of small size, light weight, low power consumption and good display quality, and thus has become the mainstream of flat panel display in recent years.

The development of liquid crystal displays, with the expansion of screen size, high saturation of color, high contrast and increased response speed, by twisted nematic (TN) liquid crystal display, super twisted nematic (STN) Liquid crystal displays, until now, have developed TFT-type liquid crystal displays with thin filmed tanstor (TFT) in every pixel. In recent years, the driving method of the TFT type liquid crystal display has been continuously improved. For example, in terms of improving the viewing angle, a vertical alignment (VA) method or an in-plane switching (IPS) method has been developed. In addition, an optically compensated bend (OCB) method has been developed which can improve the response speed of the corresponding animation.

In a liquid crystal display, a twisted nematic (TN) electric field effect type liquid crystal display is typically used which uses a positive dielectric anisotropic nematic liquid crystal. In general, liquid crystal molecules are placed between a pair of substrates containing electrodes, and the alignment directions of the two substrates are perpendicular to each other, and the arrangement of the liquid crystal molecules can be controlled via a control electric field. In the case of this type of liquid crystal display, it is important to make the alignment of the long-axis direction of the liquid crystal molecules with the substrate surface having a uniform tilt angle. A material that aligns liquid crystal molecules into a uniform pre-tilt angle alignment is generally referred to as an alignment film.

There are currently two typical methods of preparing alignment films in the industry. The first method is to form an inorganic substance into an inorganic film by vapor deposition. For example, cerium oxide is vapor-deposited on a substrate to form a thin film, and liquid crystal molecules are aligned in the vapor deposition direction. However, although the above method can obtain a uniform alignment, it is less industrially advantageous. In the second method, an organic film is coated on the surface of the substrate, and then rubbed with a soft cloth of cotton, nylon or polyester to orient the surface of the organic film so that the liquid crystal molecules are aligned in the rubbing direction. Since this method is relatively simple and relatively easy to obtain uniform alignment, it is generally applied on an industrial scale. The polymer capable of forming an organic film is, for example, polyvinyl alcohol (PVA), polyethylene oxide (PEO), polyamide (PA) or polyimine, wherein the polyimine has chemistry. Properties such as stability and thermal stability are therefore most commonly utilized as alignment film materials.

In the prior art, when a voltage is applied to the liquid crystal display, the generated ionic charge is adsorbed by the liquid crystal alignment film, and even after the applied voltage is released, it is difficult to separate the ionic charge from the liquid crystal alignment film. , thus causing a problem of residual images on the screen. Therefore, the development of recent alignment film materials has been the primary issue of improving afterimage problems.

The present invention provides a liquid crystal alignment agent which forms a liquid crystal alignment film having an effect of increasing a pretilt angle.

The present invention further provides an aromatic diamine compound which can enhance the performance of a liquid crystal display element.

The present invention further provides a polyaminic acid which can enhance the performance of a liquid crystal display element.

The present invention further provides a polyimine which can enhance the performance of a liquid crystal display element.

The present invention provides a liquid crystal alignment agent which is suitable for use in a display. The liquid crystal alignment agent includes a polyimine obtained by polymerizing a diamine compound and a tetracarboxylic acid or a dianhydride compound thereof. The diamine compound contains an aromatic diamine compound represented by the formula (I).

Wherein R ₁ to R ₅ are each a primary amine group, and the others are each independently a hydrogen atom or a monovalent substituent other than the primary amine group; R ₆ is a C1 to C20 alkyl group, and a C3 to C40 monovalent alicyclic ring a substituent of a group, a monovalent aromatic substituent of C6 to C51 or a monovalent heterocyclic substituent; X ₁ and X ₂ are each independently a single bond or are selected from the group consisting of an ether group, a ketone group, an ester group, a decyl group and a secondary group. A binding group of a group of amine groups; X ₃ and X ₄ are each independently a C1 to C3 linear alkylene group.

In the liquid crystal alignment agent according to the embodiment of the present invention, the content of the aromatic diamine compound used in the polymerization of the polyimine is, for example, at least 1 mol% based on the total amount of the diamine compound.

In the liquid crystal alignment agent according to the embodiment of the present invention, the content of the aromatic diamine compound used in the polymerization of the polyimine is, for example, at least 10 mol% based on the total amount of the diamine compound.

The liquid crystal alignment agent according to the embodiment of the present invention has a content of the aromatic diamine compound used in the polymerization of the polyimine, for example, at least 50 mol%, based on the total amount of the diamine compound.

The liquid crystal alignment agent according to the embodiment of the present invention may further include a polyamic acid obtained by polymerizing a diamine compound and a tetracarboxylic acid or a dianhydride compound thereof.

In the liquid crystal alignment agent according to the embodiment of the present invention, the content of the aromatic diamine compound used in the polymerization of the polyaminic acid is, for example, at least 1 mol% based on the total amount of the diamine compound.

In the liquid crystal alignment agent according to the embodiment of the present invention, the content of the aromatic diamine compound used in the polymerization of the polyamic acid is, for example, at least 10 mol% based on the total amount of the diamine compound.

In the liquid crystal alignment agent according to the embodiment of the present invention, the content of the aromatic diamine compound used in the polymerization of the polyamic acid is, for example, at least 50 mol% based on the total amount of the diamine compound.

The liquid crystal alignment agent according to an embodiment of the present invention may further include a solvent.

The present invention further provides an aromatic diamine compound represented by the formula (I).

Wherein R ₁ to R ₅ are each a primary amine group, and the others are each independently a hydrogen atom or a monovalent substituent other than the primary amine group; R ₆ is a C1 to C20 alkyl group, and a C3 to C40 monovalent alicyclic ring a substituent of a group, a monovalent aromatic substituent of C6 to C51 or a monovalent heterocyclic substituent; X ₁ and X ₂ are each independently a single bond or are selected from the group consisting of an ether group, a ketone group, an ester group, a decyl group and a secondary group. a divalent binding group of a group consisting of an amine group; each of X ₃ and X _{4 is} independently a linear alkyl group of C1 to C3.

The present invention further provides a polyaminic acid obtained by polymerization of a tetracarboxylic acid or a dianhydride compound thereof and a diamine compound, wherein the diamine compound contains the above aromatic diamine compound.

The polyaminic acid according to the embodiment of the present invention has a content of the above aromatic diamine compound of, for example, at least 1 mol% based on the total amount of the diamine compound.

The polyaminic acid according to the embodiment of the present invention has a content of the above aromatic diamine compound of, for example, at least 10 mol% based on the total amount of the diamine compound.

The polyaminic acid according to the embodiment of the present invention has a content of the above aromatic diamine compound of, for example, at least 50 mol% based on the total amount of the diamine compound.

The present invention further provides a polyimine which is obtained by polymerization of a tetracarboxylic acid or a dianhydride compound thereof and a diamine compound, wherein the diamine compound contains the above aromatic diamine compound.

The polyiminoimine according to the embodiment of the present invention has a content of the above aromatic diamine compound of, for example, at least 1 mol% based on the total amount of the diamine compound.

The polyiminoimine according to the embodiment of the present invention has a content of the above aromatic diamine compound of, for example, at least 10 mol% based on the total amount of the diamine compound.

The polyiminoimine according to the embodiment of the present invention has a content of the above aromatic diamine compound of, for example, at least 50 mol% based on the total amount of the diamine compound.

Based on the above, since the liquid crystal alignment agent contains a polyimine or a polyimine obtained by polymerization of the aromatic diamine compound of the present invention and a tetracarboxylic acid or a dianhydride compound thereof, it is formed. The liquid crystal alignment film can have the effect of increasing the pretilt angle, and can cause the liquid crystal display element to have a lower residual DC charge to enhance the performance of the liquid crystal display element.

The above described features and advantages of the present invention will be more apparent from the following description.

The present invention provides a liquid crystal alignment agent which is suitable for use in a display. The display is, for example, a liquid crystal display. The liquid crystal alignment agent includes a polyimine obtained by polymerizing a diamine compound and a tetracarboxylic acid or a dianhydride compound thereof. The diamine compound contains an aromatic diamine compound represented by the formula (I).

Wherein R ₁ to R ₅ are each a primary amine group, and the others are each independently a hydrogen atom or a monovalent substituent other than the primary amine group; R ₆ is a C1 to C20 alkyl group, and a C3 to C40 monovalent alicyclic ring a substituent of a group, a monovalent aromatic substituent of C6 to C51 or a monovalent heterocyclic substituent; X ₁ and X ₂ are each independently a single bond or are selected from the group consisting of an ether group, a ketone group, an ester group, a decyl group and a secondary group. a divalent binding group of a group consisting of an amine group; each of X ₃ and X _{4 is} independently a linear alkyl group of C1 to C3.

In an embodiment of the present invention, the aromatic diamine compound represented by the formula (I) may be 1-(2,4-diaminophenyl)-4-ethyl-piperazine (1-(2,4) -diaminophenyl)-4-ethyl-piperazine), 1-(3,5-diaminobenzoguanidine)-4-ethyl-piperazine (1-(3,5-diaminobenzoyl)-4-ethyl-piperazine) , 1-(2,4-Diaminophenyl)-4-phenyl-piperazine, 1-(3,5-diaminobenzene Methionine 4-phenyl-piperazine (1-(3,5-diaminobenzoyl)-4-phenyl-piperazine) and the like.

The aromatic diamine compound represented by the formula (I) can be synthesized by the following steps: First, the dinitrobenzene compound represented by the formula (II) and the formula (III) are present in the presence of a base and an organic solvent. The illustrated piperazine compound is reacted to obtain a compound represented by the formula (IV) wherein Y is -F, -Cl, -Br, -COCl, -COOH or the like.

Then, the compound represented by the formula (IV) is subjected to a hydrogenation reaction to obtain an aromatic diamine compound compound represented by the formula (I).

In the above synthesis method, a substitution reaction is carried out mainly in the presence of a dinitrobenzene represented by the formula (II) in the presence of a base and an organic solvent, followed by a reduction reaction (hydrogenation reaction) to obtain a formula. The aromatic diamine compound shown by (I). The base added has the effect of a catalyst which increases the rate of the synthesis reaction and lowers the reaction temperature.

The base suitable for use in the synthesis method may be selected from the group consisting of a basic compound of a Group IA and a Group IIA metal, preferably a carbonate selected from the group consisting of Group IA and Group IIA metals. Alternatively, the base suitable for use in this synthetic method may be a tertiary amine (e.g., trimethylamine, triethylamine, triisopropylethylenediamine, and the like).

The organic solvent suitable for use in the synthesis method may be an alkyl halide (such as dichloromethane, dichloroethane, chloroform, etc.), a ketone (such as acetone, methyl ethyl ketone, etc.), N-methyl-2- Pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl alum, and the like.

In the above reduction reaction (hydrogenation reaction), it can be carried out by a generally known hydrogenation reaction method. For example, a metal catalyst such as platinum (Pt), palladium (Pd) or Raney-Ni is used for the reduction reaction with hydrogen or a hydrazine at a suitable pressure and temperature. Alternatively, the reduction reaction is carried out with concentrated hydrochloric acid using a reducing agent such as tin dichloride (SnCl ₂ ) or iron (Fe). Alternatively, the reaction is carried out in an aprotic solvent using a reducing agent such as LiAlH ₄ .

Further, the liquid crystal alignment agent of the present invention may contain, in addition to the polyimine obtained by polymerization of the above diamine compound and a tetracarboxylic acid or a dianhydride compound thereof, the above diamine compound and tetracarboxylic acid or Polylysine obtained by polymerization of a dianhydride compound thereof, and a solvent.

The above polyimine and polylysine can be dissolved in an organic polar solvent (such as N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide) , N-methyl caprolactam, dimethyl hydrazine, γ-butyrolactone, etc.), and then coated on a glass substrate or a transparent plastic film substrate having a transparent electrode. The solvent is subjected to heat treatment to evaporate at a temperature of from 120 ° C to 350 ° C to form a film. After the film is subjected to directional rubbing treatment, a liquid crystal alignment film can be obtained, which can provide liquid crystal molecules with a stable pretilt angle and a high voltage holding ratio.

The above tetracarboxylic acid is usually not particularly limited and may be an aromatic tetracarboxylic acid (e.g., 1,2,4,5-benzenetetracarboxylic acid, 3,3',4,4'-diphenyltetracarboxylic acid). , 2,3,3',4-diphenyltetracarboxylic acid, bis(3,4-dicarboxyphenyl)ether, 3,3'4,4'-benzophenonetetracarboxylic acid, bis (3 , 4-dicarboxyphenyl) anthracene, bis(3,4-dicarboxyphenyl)methane, 2,2-bis(3,4-dicarboxyphenyl)propane, 1,1,1,3,3 ,3-hexafluoro-2,2-bis(3,4-dicarboxyphenyl)propane, bis(3,4-dicarboxyphenyl)dimethylnonane, bis(3,4-dicarboxyphenyl) Diphenyl decane, 2,3,4,5-pyridinetetracarboxylic acid, 2,6-bis(3,4-dicarboxyphenyl)pyridine, dianhydride and dicarboxylic acid derived from the above aromatic tetracarboxylic acid Dihalogenated halogen compounds, etc.), aliphatic cyclic tetracarboxylic acids (such as cyclobutane tetracarboxylic acid, cyclopentane tetracarboxylic acid, cyclohexane tetracarboxylic acid, 1,3,5-tricarboxycyclopentyl acetic acid) , 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic anhydride, dianhydride derived from the above aliphatic cyclic tetracarboxylic acid, divalent halogen compound of dicarboxylic acid, etc.) Or an aliphatic tetracarboxylic acid (such as butane tetracarboxylic acid and its derived dianhydride and dicarboxylic acid divalent halogen compound). The above tetracarboxylic acid and its dianhydride and the dicarboxylic acid divalent halogen compound may be used singly or in combination of two or more kinds.

Further, in carrying out the polymerization reaction of the above diamine compound with a tetracarboxylic acid or a dianhydride compound thereof, the diamine compound may contain other diamine compounds in addition to the aromatic diamine compound represented by the formula (I). .

The other diamine compound described above is, for example, a primary diamine compound which may be an aromatic diamine compound (e.g., p-phenylenediamine, diamine diphenylmethane, diamine diphenyl ether, 2,2-diamine phenyl). Propane, bis(3,5-diethyl-4-aminophenyl)methane, diamine diphenyl hydrazine, diaminobenzophenone, diaminonaphthalene, 1,4-bis(4-amine Phenoxy group) benzene, 1,3-bis(4-aminophenoxy)benzene, 4,4-bis(4-aminophenoxy)diphenylanthracene, 2,2-bis(4, 4-aminophenoxyphenyl)propane, 2,2-bis(4-aminophenyl)hexafluoropropane and 2,2-bis(4,4-aminophenoxyphenyl)hexafluoropropane Etc.), an aliphatic cyclic diamine compound (such as bis(4-aminocyclohexyl)methane, bis(4-amino-3-methylcyclohexyl)methane, etc.) or an aliphatic diamine compound (such as Butanediamine or hexamethylenediamine). The above other diamine compounds may be used singly or in combination of two or more.

In an embodiment of the invention, the aromatic diamine compound is present in an amount of at least 1 mol%, preferably at least 10 mol%, more preferably at least 50, based on the total of the diamine compound used. Moer%.

When the polymerization of the above diamine compound with a tetracarboxylic acid or a dianhydride compound thereof is carried out, the degree of polymerization of the product is preferably from a reduced viscosity of from 0.05 dl/g to 3.0 dl/g. The above specific viscosity was measured at a concentration of 0.5 g/dl of N-methyl-2-pyrrolidone at a temperature of 30 °C.

The polymerization method of the diamine compound and the tetracarboxylic acid or its dianhydride compound is not particularly limited and can be carried out by a generally known method. For example, the diamine compound is first dissolved in an organic polar solvent (eg, N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl Aachen). Then, a tetracarboxylic acid or a dianhydride compound thereof is added to the solvent to carry out a polymerization reaction to obtain a solution of a polyimine or a copolymer of a polyimine and a poly-proline. The temperature at which the polymerization is carried out is, for example, between -20 ° C and 150 ° C, preferably -5 ° C to 100 ° C. The polymerization time is usually from 5 minutes to 24 hours, preferably from 10 minutes to 8 hours.

Further, when the polymerization reaction is carried out, the solid content (weight percentage relative to the solvent) of the formed polyimine or the copolymer of the polyimine and the polyaminic acid should be between 10% by weight and 30% by weight. . .

In order to obtain a suitable molecular weight of the polyimine or the copolymer of polyimine and polyphthalic acid, the molar ratio of the tetracarboxylic acid or its dianhydride compound to the diamine compound is, for example, between 0.8 and 1.2. When the molar ratio of the tetracarboxylic acid or its dianhydride compound to the diamine compound is closer to 1, the molecular weight is larger and the viscosity is higher. When the molar ratio of the tetracarboxylic acid or its dianhydride compound to the diamine compound is less than 1, an appropriate amount of end cap functional group may be added to reduce the end caused by the molar ratio not equal to 1. The oxidation of functional groups. Suitable terminal blocking functional groups are, for example, phthalic anhydride, maleic anhydride, aniline, cyclohexane amine and the like.

After the polymerization reaction, the copolymerization degree of the obtained polyimine or polyimine and polyphthalic acid is, for example, 10 to 5,000 (preferably 16 to 250), and the weight average molecular weight is, for example, 5,000 to 5,000. 2500000 (preferably 8000 to 125000).

Further, in order to increase the degree of polymerization of the above polymerization reaction and to reduce the reaction time, a catalyst may be added during the reaction. Suitable catalysts are, for example, triethylamine, diethylamine, n-butylamine, pyridine and the like. The above catalyst also has the function of adjusting the pH of the solution.

In addition, in other embodiments, the liquid crystal alignment agent may further contain an organic sulfonium (oxy) alkane compound, which may be aminopropyltrimethoxydecane, aminopropyltriethyldecane, vinylmethylnonane, N -(2-Aminoethyl)-3-aminopropylmethyldimethoxydecane, N-(2-aminoethyl)-3-aminopropyltrimethoxydecane, vinyl triethyl Oxydecane, 3-methacryloxypropyltrimethoxydecane, 3-glycidoxypropyltrimethoxydecane, 3-glycidoxypropylmethyldimethoxydecane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxydecane, 3-ureidopropyltrimethoxydecane, 3-ureidopropyltriethoxydecane, N-ethoxycarbonyl-3 -Aminopropyltrimethoxydecane, N-ethoxycarbonyl-3-aminopropyltriethoxyamine decane, N-triethoxycarbenylpropyltriethylamine, N-Trimethyl Oxymethyl methacrylate propyl triethylamine, N-bis(oxyethyl)-3-aminopropyltrimethoxydecane, N-bis(oxyethyl)-3-aminopropyl Triethyl decane and the like. The content of the organic quinone (oxy) alkane compound is such that the desired characteristics of the liquid crystal alignment film are not affected and the adhesion of the liquid crystal alignment film to the surface of the substrate can be improved. When the content of the organic hydrazine (oxy) alkane compound is too high, the formed liquid crystal alignment film is liable to cause poor alignment; if the content of the organic oxime (oxy) alkane compound is too low, the formed liquid crystal alignment film is likely to generate a brush. Poor and powder cutting phenomenon. Therefore, the content of the organic oxime (oxy)ane compound is, for example, from 0.01% by weight to 5% by weight, based on the total weight of all the polymers in the liquid crystal alignment agent, preferably from 0.1% by weight to 3% by weight.

Furthermore, in other embodiments, the liquid crystal alignment agent may further contain an epoxy compound, which may be 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-m-phenylene, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N ' ,N ' -tetraglycidyl-4,4 ' -diaminodiphenylmethane, 3-(N-allyl-N-glycidyl)aminopropyltrimethoxy Decane, 3-(N,N-diglycidyl)aminopropyltrimethoxydecane. The content of the epoxy compound is such that the desired characteristics of the liquid crystal alignment film are not affected and the adhesion of the liquid crystal alignment film to the surface of the substrate can be improved. When the content of the epoxy compound is too high, the formed liquid crystal alignment film is liable to cause poor alignment; if the content of the epoxy compound is too low, the formed liquid crystal alignment film is liable to cause brushing failure and excessive powdering. . Therefore, the content of the epoxy compound is, for example, from 0.01% by weight to 3% by weight, based on the total weight of the alignment film material, preferably from 0.1% by weight to 2% by weight.

In order to match the processability of the liquid crystal alignment film, the solid content of the formed polyimine or the copolymer of polyimine and polyglycolic acid can be adjusted to 3 to 10% by weight in an organic solvent to adjust the viscosity. In order to control the film thickness and coating properties, and to facilitate the subsequent alignment film processing process. Suitable organic solvents are, for example, N-methyl-2-pyrrolidone, m-cresol, γ-butyrolactone, N,N-dimethylacetamide, N,N-dimethylformamide or mixture. Alternatively, a solvent which does not have the ability to dissolve polyimine may be added as long as it does not cause poor solubility of the polyimine in other solvents. Such solvents are, for example, ethylene glycol monoethyl ether, ethylene glycol monobuthyl ether, diethylene glycol monobuthyl ether, diethyl Diethylene glycol monoethyl ether, butyl carbitol, ethyl carbitol acetate, ethylene glycol or a mixture thereof. The content of such a solvent is preferably controlled to be 90% or less of the total weight of the solvent.

A method of synthesizing polyimine is, for example, heating poly-proline to perform dehydration ring closure to form a polyimine. The heating temperature is, for example, between 100 ° C and 350 ° C, preferably between 120 ° C and 320 ° C. The reaction time is, for example, from 3 minutes to 6 hours.

There are two main methods for synthesizing a copolymer of polyimine and polyaminic acid. The first method is to obtain a copolymer by controlling the ratio of the number of dehydrated moles. In the second method, after a part of the diamine compound and the dianhydride compound are subjected to dehydration cyclization at a specific ratio, the remaining diamine compound and the dianhydride compound may be added at room temperature to carry out polymerization.

The liquid crystal display element can be produced by the following steps.

(1) The liquid crystal alignment agent of the present invention is applied onto a glass substrate by a roll coating method, a spin coating method or a printing coating method. This glass substrate has a patterned transparent conductive film. After coating the liquid crystal alignment agent, heat baking is performed to remove the organic solvent in the liquid crystal alignment agent and to promote dehydration/ring closure reaction of the uncircularized polyamic acid to form a polyimide film. The above heat baking temperature is between 80 and 300 ° C, preferably 100 to 240 ° C. The thickness of the film formed is preferably from 0.005 micrometers to 0.5 micrometers.

(2) The formed film is directionally rubbed by a roller wound with a nylon or cotton fiber cloth to impart alignment property to the liquid crystal molecules.

(3) applying a sealant on the substrate having the liquid crystal alignment film, and spraying the spacer on the substrate having the liquid crystal alignment film, and then rubbing the two substrates perpendicular to each other or parallel to each other By combining and injecting liquid crystal into the gap between the two substrates and sealing the injection hole, a liquid crystal display element can be formed.

For liquid crystal display elements, the following characteristics are generally used as evaluation indicators:

(1) Pretilt angle

The liquid crystal display element to which the liquid crystal (ZLI-4792) was injected was measured by a crystal rotation method.

(2) Brushing

The liquid crystal alignment agent was applied by spin coating on an indium tin oxide (ITO) substrate, baked through an oven, and oriented at a speed of 1000 rpm and a platform moving speed of 60 mm/sec. The brush was rubbed 10 times, and the surface after brushing was visually observed by a polarizing microscope.

(3) Voltage retention rate

A direct current of 3 V was applied to the liquid crystal display element at 60 Hz and a pulse width of 60 μsec at an ambient temperature of 90 ° C to measure the voltage holding ratio in the liquid crystal display element.

(4) Residual DC charge

At a temperature of 60 ° C, a direct current of 5 V was applied to the liquid crystal display element for 1 hour, and then the direct current was cut off and the residual direct current voltage in the liquid crystal display element was measured.

(5) Cyclization rate (imidization ratio)

The liquid crystal alignment agent was dried under reduced pressure at room temperature, and then the dried solid was dissolved in deuterated dimethyl hydrazine, using tetramethyl decane as a reference substance, measured by ¹ H-NMR, and The imidization ratio was obtained from the following formula.

Amination ratio (%) = (1-A ¹ /A ² ×α)×100

A ¹ : peak area derived from the proton of the NH group (10 ppm)

A ² : Peak area derived from other protons

α: the number ratio of other protons to a proton of the NH group in the polylysine

(6) Adhesion

The liquid crystal alignment agent was applied onto the ITO substrate, and the ITO substrate was boiled at 100 ° C for 1 hour, and then subjected to a cross cut method using a 3 M tape.

(7) Reliability

The liquid crystal display element was driven at 60 Hz/5 V for 500 hours in a high-temperature and high-humidity environment (temperature: 50 ° C, relative humidity: 90 RH), and then observed through a polarizing microscope.

The invention will be described below by way of experimental examples.

Synthesis of aromatic diamine compounds Experimental example 1 Synthesis of 1-(2,4-diaminophenyl)-4-ethyl-piperazine (1-(2,4-diaminophenyl)-4-ethyl-piperazine)

In a 2 liter reaction flask, 2,4-dinitrofluorobenzene (67 g, 360 mM), dimethylacetamide (500 g) and carbonic acid were added. Potassium carbonate (72.5 g, 525 mmol), stirred for 5 minutes. Then, N-ethylpiperazine (40 g, 350 mmol) was slowly dropped into the reaction flask. After the completion of the whole number of drops, the temperature was raised to 80 ° C, the reaction was carried out for 48 hours, and then returned to room temperature. Next, the reactant was poured into ice pure water (2000 g) to precipitate a precipitate. Then, suction filtration was carried out, and the obtained cake was the product 1-(2,4-dinitrophenyl)-4-ethyl-piperazine (1-(2,4-dinitrophenyl)-4-ethyl-piperazine (70.6 g, 252 mmol), yield 72%. Spectral data: 1H NMR (400 MHz, CDCl 3) δ8.6 (1H), 8.2 (1H), 7.1 (1H), 3.3 (4H), 2.6 (4H), 2.5 (2H), 1.1 (3H) ppm.

In a 1 liter reaction flask, 1-(2,4-dinitrophenyl)-4-ethyl-piperazine (56.07 g, 200 mmol), tetrahydrofuran (400 g), 10% was added. Palladium-on-carbon (2.05 g) was stirred for 10 minutes. Then, 80% aqueous hydrazine hydrate (30 ml) was slowly added dropwise. After the completion of the dropwise addition, the temperature was raised to 40 ° C, and 80% aqueous hydrazine (30 ml) was slowly added dropwise. Stirring was continued for 24 hours after all the drops were completed. Next, the reaction temperature was lowered back to room temperature. Then, suction filtration was carried out to obtain a filtrate. Thereafter, the solvent was removed by concentration under reduced pressure, and the residue was recrystallized from ethyl acetate and n-hexane to afford product 1-(2,4-diaminobenzene)-4. Ethyl-piperazine (39.6 g, 180 mmol) in 90% yield. Spectroscopic data: 1H NMR (400 MHz, CDCl ₃ ) δ 6.81-6.85 (1H), 6.04-6.10 (2H), 3.4-4.1 (4H), 2.85-2.87 (4H), 2.40-2.55 (2H), 1.08 -1.12 (3H) ppm.

Experimental example 2 Synthesis of 1-(3,5-diaminobenzoguanidine)-4-ethyl-piperazine (1-(3,5-diaminobenzoyl)-4-ethyl-piperazine)

In a 2 liter reaction flask, 3,5-dinitrobenzoyl chloride (115.3 g, 500 mmol), anhydrous tetrahydrofuran (500 g) and potassium carbonate (103.7 g, 750 mmol) and cooled to 10 ° C and stirred for 5 minutes. Then, N-ethylpiperazine (74.2 g, 650 mmol) was slowly dropped into the reaction flask. After all the drops were completed, the mixture was returned to room temperature and stirred for 4 hours. The tetrahydrofuran was removed by concentration under reduced pressure, and the residue was poured into purified water (2000 g) to be precipitated. Next, suction filtration is performed. Thereafter, the filter cake was taken out and methanol (100 g) was added. Then, heating and refluxing were carried out for 1 hour. Then, return to room temperature. Thereafter, suction filtration was carried out and washed with methanol to obtain the product 1-(3,5-dinitrobenzhydrazide)-4-ethyl-piperazine (1-(3,5-dinitrobenzoyl)-4-ethyl -piperazine) (126.4 g, 410 mmol) in 82% yield. Spectroscopic data: 1H NMR (400 MHz, CDCl ₃ ) δ 9.04-9.05. (1H), 8.55-8.56 (2H), 3.42-3.81 (4H), 2.43-2.55 (6H), 1.06-1.09 (3H) ppm .

In a 500 ml reaction flask, 1-(3,5-dinitrobenzimidamide)-4-ethyl-piperazine (24.9 g, 81 mmol), tetrahydrofuran (200 g), 10% Palladium on carbon catalyst (0.43 g) and stirred for 10 minutes. Then, 80% aqueous hydrazine (15 ml) was slowly added dropwise. After the completion of the dropwise addition, the temperature was raised to 40 ° C, and 80% aqueous hydrazine (15 ml) was slowly added dropwise. Stirring was continued for 24 hours after all the drops were completed. Next, the reaction temperature was lowered back to room temperature. Then, suction filtration was performed to take the filtrate. Thereafter, the solvent was removed by concentrating under reduced pressure and concentrated under reduced pressure, and the residue was recrystallized from ethyl acetate and n-hexane to give the product 1-(3,5-diaminobenzhydrazide)-4 Ethyl-piperazine (17.7 g, 71 mmol) in 88% yield. Spectral data: 1H NMR (400 MHz, CDCl 3) δ6.0-6.01 (3H), 3.5-3.8 (4H), 2.4-2.5 (6H), 1.1 (3H) ppm.

Experimental example 3 Synthesis of 1-(2,4-diaminophenyl)-4-phenyl-piperazine (1-(2,4-diaminophenyl)-4-phenyl-piperazine)

In a 2 liter reaction flask, 1-phenylpiperazine (56.74 g, 350 mM), N-methyl-2-pyrrolidone (700 g) was added. ) with potassium carbonate (72.5 g, 525 mmol) and stirred at room temperature for 20 minutes and then warmed to 70 °C. Then, a mixed solution of 2,4-dinitrofluorobenzene (67.1 g, 360 mmol) and N-methylxanthone (175 g) was slowly dropped into the reaction flask. After all the dropwise drops, stir for 6 hours. Next, the temperature of the reaction flask was lowered back to room temperature, and the solution was poured into pure water (2625 g) to be precipitated. Then, suction filtration was performed to obtain a filter cake. Thereafter, the filter cake was taken out and methanol (525 g) was added, and the mixture was heated under reflux for 1 hour. After cooling, suction filtration was carried out, and the obtained product, 1-(2,4-dinitrophenyl)-4-phenyl-piperazine (1-(2,4-dinitrophenyl)-4-phenyl-, was washed with methanol. Piperazine) (91.9 g, 280 mmol) in 80% yield. Spectroscopic data: 1H NMR (400 MHz, d-DMSO) δ 8.60 (1H), 8.30 (1H), 8.30 (1H), 7.30-7.50 (1H), 7.20-7.30 (2H), 6.90 (2H), 6.8 -6.9 (1H), 3.4-3.5 (4H), 3.30 (4H) ppm.

In a 2 liter reaction flask, put 1-(2,4-dinitrophenyl)-4-phenyl-piperazine (40 g, 121 mmol) and ethanol (200 mL), and Stir at 10 ° C for 10 minutes. Then, a mixture of tin chloride (202 g, 784 mmol), hydrogen chloride (132 ml), water (26 ml), and ethanol (200 ml) was slowly added dropwise. After all the dropwise drops, the temperature was raised to 75 ° C, stirred for 3 hours, and then returned to room temperature. Next, the solution was poured into pure water (1500 g), and potassium hydroxide (100 g) was slowly added to precipitate. Thereafter, suction filtration was carried out and washed with pure water to obtain a solid 1-(2,4-diaminophenyl)-4-phenyl-piperazine (25 g, 84 mmol) in a yield of 70%. . Spectroscopic data: 1H NMR (400 MHz, CDCl ₃ ) δ 7.26-7.30 (2H), 6.96-6.98 (d, 2H), 6.85-6.89 (2H), 6.09-6.12 (2H), 3.30-4.02 (8H) , 2.98-3.00 (4H) ppm.

Experimental example 4 Synthesis of 1-(3,5-diaminobenzoguanidine)-4-phenyl-piperazine (1-(3,5-diaminobenzoyl)-4-phenyl-piperazine)

In a 2 liter reaction flask, 1-phenylpiperazine (48.6 g, 300 mmol), N-methylxanthone (600 g) and pyridine (35.6 g) were added to the chamber. Stir for 20 minutes at room temperature and then warm to 70 °C. Then, a mixture of 3,5-dinitrobenzhydrin chloride (71.2 g, 309 mmol) and N-methylxanthone (150 g) was slowly dropped into the reaction flask. After the completion of the dropwise addition, the mixture was stirred for 6 hours, and the reaction temperature was lowered to room temperature, and poured into pure water (2250 g). Then, suction filtration was performed to obtain a filter cake. Next, the filter cake was taken out and methanol (450 g) was added. Then, heating and refluxing were carried out for 1 hour. Thereafter, suction filtration was carried out and washed with methanol to obtain the product 1-(3,5-dinitrobenzimidazole)-4-phenyl-piperazine (1-(3,5-dinitrobenzoyl)-4- Phenyl-piperazine) (85.5 g, 240 mmol) in 80% yield. Spectroscopic data: 1H NMR (400 MHz, CDCl ₃ ) δ 9.07-9.08 (1H), 8.59-8.60 (2H), 7.24-7.29 (2H), 6.89-6.93 (3H), 3.58-3.96 (4H), 3.16 -3.2 (4H) ppm.

In a 2 liter reaction flask, 1-(3,5-dinitrobenzoyl)-4-phenyl-piperazine (1-(3,5-dinitrobenzoyl)-4-phenyl-piperazine) was placed ( 40 g, 112 mmol, stannous chloride (201 g, 784 mmol) and ethanol (800 ml) were stirred at 5 ° C for 10 minutes. Then, a mixture of hydrochloric acid (132 ml) and pure water (26 ml) was slowly added dropwise. After all the drops were completed, the temperature of the reaction flask was raised to 75 ° C, stirred for 3 hours, and then returned to room temperature. Next, the solution was poured into pure water (2000 g), and potassium hydroxide (100 g) was slowly added thereto to precipitate. Then, suction filtration was carried out and washed with pure water to obtain a solid 1-(3,5-diaminobenzimidazole)-4-phenyl-piperazine (25 g, 84 mmol) in a yield of 75%. Spectroscopic data: 1H NMR (400 MHz, d-DMSO) δ 7.20-7.24 (2H), 6.93-6.95 (2H), 6.79-6.82 (2H), 5.80-5.88 (3H), 4.96 (4H), 3.52- 3.66 (4H), 3.10 (4H) ppm.

Synthesis of Polyimine and Preparation of Liquid Crystal Alignment Membrane

(1) 1-(2,4-Diaminophenyl)-4-ethyl-piperazine, abbreviated as DPEP.

(2) 1-(3,5-diaminobenzoyl)-4-ethyl-piperazine, abbreviated as DBEP.

(3) 1-(2,4-Diaminophenyl)-4-phenyl-piperazine, abbreviated as DPPP.

(4) 1-(3,5-diaminobenzoyl)-4-phenyl-piperazine, abbreviated as DBPP.

(5) 4,4'-diethylenediphenylmethane (4,4'-methylenedianiline), abbreviated as MDA.

(6) 1,2,3,4-cyclobutane-1,2,3,4-tetracarboxylic dianhydride, abbreviated as CBDA.

Experimental example 5

11 grams (0.05 moles) of DPEP was reacted with 9.8 grams (0.05 moles) of CBDA in 83.2 grams of N-methylxanthone (NMP) for 12 hours at room temperature, followed by the addition of 312 grams of NMP. Dilute to obtain a polyamidonic acid solution (specific viscosity 0.6 dl/g). Then, this polyamine acid solution was spin-coated on a glass substrate having a transparent electrode at 3000 rpm. Next, it was heated at 200 ° C for 30 minutes to form a polyimide film, which was assembled into a liquid crystal cell assembled in parallel directions using a 40 μm spacer. After filling the liquid crystal (for example, model: ZLI-4792, manufactured by Merck), the liquid crystal cell rotates between crossed nicols and assumes a full dark state, using a pretilt measuring machine ( The tilt angle tester (TBA) obtained a pretilt angle value of 90°.

Experimental example 6

12.4 g (0.05 mol) of DBEP was reacted with 9.8 g (0.05 mol) of CBDA in 88.8 g of NMP at room temperature for 12 hours, and then 333 g of NMP was added for dilution to obtain a polyamidonic acid solution. (Specific viscosity is 0.55 dl/g). Then, this polyamine acid solution was spin-coated on a glass substrate having a transparent electrode at 3000 rpm. Next, it was heated at 200 ° C for 30 minutes to form a polyimide film, which was assembled into a liquid crystal cell assembled in parallel directions using a 40 μm spacer. After filling the liquid crystal (for example, model: ZLI-4792, manufactured by Merck), the liquid crystal cell rotates between the crossed Nichols crystals and assumes a full dark state, and the pretilt angle value obtained by the pretilt angle measuring machine is used. It is 90°.

Experimental example 7

13.4 g (0.05 mol) of DPPP was reacted with 9.8 g (0.05 mol) of CBDA in 92.8 g of NMP at room temperature for 12 hours, and then 348 g of NMP was added for dilution to obtain a polyamidonic acid solution. (Specific viscosity is 0.57 dl/g). Then, this polyamine acid solution was spin-coated on a glass substrate having a transparent electrode at 3000 rpm. Next, it was heated at 200 ° C for 30 minutes to form a polyimide film, which was assembled into a liquid crystal cell assembled in parallel directions using a 40 μm spacer. After filling the liquid crystal (for example, model: ZLI-4792, manufactured by Merck), the liquid crystal cell rotates between the crossed Nichols crystals and assumes a full dark state, and the pretilt angle value obtained by the pretilt angle measuring machine is used. It is 90°.

Experimental Example 8

14.8 g (0.05 mol) of DBPP was reacted with 9.8 g (0.05 mol) of CBDA in 98.4 g of NMP at room temperature for 12 hours, and then 369 g of NMP was added for dilution to obtain a polyamidonic acid solution. (Specific viscosity is 0.52 dl/g). Then, this polyamine acid solution was spin-coated on a glass substrate having a transparent electrode at 3000 rpm. Next, it was heated at 200 ° C for 30 minutes to form a polyimide film, which was assembled into a liquid crystal cell assembled in parallel directions using a 40 μm spacer. After filling the liquid crystal (for example, model: ZLI-4792, manufactured by Merck), the liquid crystal cell rotates between the crossed Nichols crystals and assumes a full dark state, and the pretilt angle value obtained by the pretilt angle measuring machine is used. It is 90°.

Experimental Example 9

2.2 g (0.01 mol) of DPEP, 14.8 g (0.04 mol) of MDA and 9.8 g (0.05 mol) of CBDA were reacted in 107.2 g of NMP for 12 hours at room temperature, followed by the addition of 402 g of NMP. Dilution was carried out to obtain a polyaminic acid solution (specific viscosity of 0.86 dl/g). Then, this polyamine acid solution was spin-coated on a glass substrate having a transparent electrode at 3000 rpm. Next, it was heated at 200 ° C for 30 minutes to form a polyimide film. After cooling the polyimide film, it was directionally rubbed with bristles, and assembled into a liquid crystal cell assembled in parallel directions using a 40 micrometer spacer. After pouring the liquid crystal (for example, model: ZLI-4792, manufactured by Merck), the pretilt angle value obtained by the pretilt angle measuring machine was 5.0.

Experimental Example 10

2.48 g (0.01 mol) of DBEP, 14.8 g (0.04 mol) of MDA and 9.8 g (0.05 mol) of CBDA were reacted in 108.3 g of NMP for 12 hours at room temperature, followed by the addition of 406.2 g of NMP. Dilution was carried out to obtain a polyaminic acid solution (specific viscosity of 0.73 dl/g). Then, this polyamine acid solution was spin-coated on a glass substrate having a transparent electrode at 3000 rpm. Then, it was heated at 200 ° C for 30 minutes to form a polyimide film. After cooling the polyimide film, it was directionally rubbed with bristles, and assembled into a liquid crystal cell assembled in parallel directions using a 40 micrometer spacer. After filling the liquid crystal (for example, model: ZLI-4792, manufactured by Merck), the pretilt angle value obtained by the pretilt angle measuring machine was 5.3.

Experimental Example 11

2.68 g (0.01 mol) of DPPP, 14.8 g (0.04 mol) of MDA and 9.8 g (0.05 mol) of CBDA were reacted in 109.1 g of NMP for 12 hours at room temperature, followed by the addition of 409.2 g of NMP. Dilution was carried out to obtain a polyaminic acid solution (specific viscosity of 0.80 dl/g). Then, this polyamine acid solution was spin-coated on a glass substrate having a transparent electrode at 3000 rpm. Next, it was heated at 200 ° C for 30 minutes to form a polyimide film. After cooling the polyimide film, it was directionally rubbed with bristles, and assembled into a liquid crystal cell assembled in parallel directions using a 40 micrometer spacer. After pouring the liquid crystal (for example, model: ZLI-4792, manufactured by Merck), the pretilt angle value obtained by the pretilt angle measuring machine was 5.2.

Experimental Example 12

2.96 g (0.01 mol) of DBPP, 14.8 g (0.04 mol) of MDA and 9.8 g (0.05 mol) of CBDA were reacted in 110.2 g of NMP at room temperature for 12 hours, and then 413.4 g of NMP was added. Dilute to obtain a polyamic acid solution (specific viscosity 0.72 dl/g). Then, this polyamine acid solution was spin-coated on a glass substrate having a transparent electrode at 3000 rpm. Next, it was heated at 200 ° C for 30 minutes to form a polyimide film. After cooling the polyimide film, it was directionally rubbed with bristles, and assembled into a liquid crystal cell assembled in parallel directions using a 40 micrometer spacer. After pouring the liquid crystal (for example, model: ZLI-4792, manufactured by Merck), the pretilt angle value obtained by the pretilt angle measuring machine was 5.5°.

Comparative example 1

9.7 g (0.05 mol) of MDA was reacted with 9.8 g (0.05 mol) of CBDA in 78 g of NMP for 12 hours at room temperature, and then added with 292.5 g of NMP to obtain a polyamidonic acid solution. (Specific viscosity is 0.81 dl/g). Then, this polyamine acid solution was spin-coated on a glass substrate having a transparent electrode at 3000 rpm. Next, it was heated at 200 ° C for 30 minutes to form a polyimide film. After cooling the polyimide film, it was directionally rubbed with bristles, and assembled into a liquid crystal cell assembled in parallel directions using a 40 micrometer spacer. After pouring the liquid crystal (for example, model: ZLI-4792, manufactured by Merck), the pretilt angle value obtained by the pretilt angle measuring machine was 2.1°.

Table 1 compares the pretilt angles of the examples and the comparative examples, and refers to Table 1.

As apparent from Table 1, since the aromatic diamine compound of the present invention (Experimental Examples 5 to 12) was added at the time of preparation of the liquid crystal alignment agent, the formed liquid crystal alignment film had an effect of improving the pretilt angle.

Table 2 compares the residual DC charges of the examples and comparative examples. Please refer to Table 2.

As is apparent from Table 2, since the aromatic diamine compound of the present invention (Experimental Examples 5 to 12) was added at the time of preparation of the liquid crystal alignment agent, the liquid crystal display element was allowed to have a low residual DC charge.

As described above, since the liquid crystal alignment agent contains a polyimine or a polyimine obtained by polymerization of the aromatic diamine compound of the present invention and a tetracarboxylic acid or a dianhydride compound thereof, The liquid crystal alignment film formed by the liquid crystal alignment agent can have the effect of increasing the pretilt angle, and enables the liquid crystal display element to have a lower residual DC charge, thereby achieving the purpose of improving the performance of the liquid crystal display element.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the invention, and any one of ordinary skill in the art can make some modifications and refinements without departing from the spirit and scope of the invention. The scope of the invention is defined by the scope of the appended claims.

Claims (18)

A liquid crystal alignment agent suitable for use in a display, the liquid crystal alignment agent comprising: polyimine, obtained by polymerization of a diamine compound and a tetracarboxylic acid or a dianhydride compound thereof, wherein the diamine compound contains the formula (I) An aromatic diamine compound, Wherein R ₁ to R ₅ are each a primary amine group, and the remainder are each independently a hydrogen atom; R ₆ is a C1 to C20 alkyl group or a C6 to C51 monovalent aromatic substituent; and X ₁ and X ₂ are each independently It is a single bond or a divalent bond selected from the group consisting of an ether group, a ketone group, an ester group, a guanamine group and a secondary amine group; and X ₃ and X ₄ are each independently a C1 to C3 linear alkylene group. The liquid crystal alignment agent according to claim 1, wherein the aromatic diamine compound is used in an amount of at least 1 mol% based on the total amount of the diamine compound. The liquid crystal alignment agent according to claim 1, wherein the aromatic diamine compound is used in an amount of at least 10 mol% based on the total amount of the diamine compound. The liquid crystal alignment agent according to claim 1, wherein the aromatic diamine compound is used in an amount of at least 50 mol% based on the total amount of the diamine compound. The liquid crystal alignment agent according to claim 1, further comprising polyamic acid obtained by polymerizing the diamine compound and the tetracarboxylic acid or a dianhydride compound thereof. The liquid crystal alignment agent according to claim 5, wherein the aromatic diamine compound is used in an amount of at least 1 mol% based on the total amount of the diamine compound. The liquid crystal alignment agent according to claim 5, wherein the aromatic diamine compound is used in an amount of at least 10 mol% based on the total amount of the diamine compound. The liquid crystal alignment agent according to claim 5, wherein the aromatic diamine compound is used in an amount of at least 50 mol% based on the total amount of the diamine compound. The liquid crystal alignment agent according to claim 1, further comprising a solvent. An aromatic diamine compound represented by formula (I), Wherein R ₁ to R ₅ are each a primary amine group, and the remainder are each independently a hydrogen atom; R ₆ is a C1 to C20 alkyl group or a C6 to C51 monovalent aromatic substituent; and X ₁ and X ₂ are each independently It is a single bond or a divalent bond selected from the group consisting of an ether group, a ketone group, an ester group, a guanamine group and a secondary amine group; and X ₃ and X ₄ are each independently a C1 to C3 linear alkylene group. Polylysine, consisting of a tetracarboxylic acid or a dianhydride compound thereof The amine compound is obtained by a polymerization reaction, wherein the diamine compound contains the aromatic diamine compound as described in claim 10 of the patent application. The polyaminic acid according to claim 11, wherein the content of the aromatic diamine compound is at least 1 mol% based on the total amount of the diamine compound. The polyaminic acid according to claim 11, wherein the aromatic diamine compound is present in an amount of at least 10 mol% based on the total of the diamine compound. The polyaminic acid according to claim 11, wherein the aromatic diamine compound is present in an amount of at least 50 mol% based on the total of the diamine compound. A polyimine which is obtained by polymerization of a tetracarboxylic acid or a dianhydride compound thereof and a diamine compound, wherein the diamine compound contains the aromatic diamine compound as described in claim 10 of the patent application. The polyimine according to claim 15, wherein the content of the aromatic diamine compound is at least 1 mol% based on the total amount of the diamine compound. The polyimine according to claim 15, wherein the aromatic diamine compound is present in an amount of at least 10 mol% based on the total of the diamine compound. The polyimine of claim 15, wherein the aromatic diamine compound is present in an amount of at least 50 mol% based on the total of the diamine compound.