KR20080099647A - Alignment material of liquid crystal display device and manufacturing method thereof - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alignment material for a liquid crystal display device and a method for manufacturing the same. In particular, a diaminobenzene derivative represented by the following Chemical Formula 1 having excellent liquid crystal orientation and rubbing resistance, high voltage retention and contrast, and capable of reducing charge accumulation. It relates to a manufacturing method thereof and a liquid crystal alignment film using the same.

[Formula 1]

In Formula 1, A ₁ to A ₅ are each independently -H, -F, -CF 3, -OCF 3, an alkyl group having 1 to 7 carbon atoms, an alkoxy group having 1 to 7 carbon atoms, and the following Formula 2a, 2b, 2c, or 2d And at least one of A ₁ to A ₅ is not -H.

[Formula 2a]

[Formula 2b]

[Formula 2c]

[Formula 2d]

In Formulas 2a, 2b, 2c, and 2d, each R independently represents an alkyl group having 1 to 7 carbon atoms or an alkoxy group having 1 to 7 carbon atoms.

Description

 ALIGNMENT MATERIAL FOR LIQUID CRYSTAL DISPLAY DEVICE AND A PREPARING METHOD OF SAME

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alignment material for a liquid crystal display device and a method for manufacturing the same. In particular, a diaminobenzene derivative represented by the following Chemical Formula 1 having excellent liquid crystal orientation and rubbing resistance, high voltage retention and contrast, and capable of reducing charge accumulation. It relates to a manufacturing method thereof and a liquid crystal alignment film using the same.

In general, the conventional cathode ray tube (CRT) display device, despite the excellent characteristics, the recent demand for high-definition, large screen and flat panel type due to the disadvantage that the volume and weight rapidly increases as the screen is larger It is inadequate for use in multimedia systems, and liquid crystal displays have been developed to improve this.

In the manufacturing process of the liquid crystal display device, the alignment effect of the alignment film is an important factor in determining the quality of the LCD. The alignment layer used in the liquid crystal display element basically aligns the liquid crystal molecules, has an appropriate pretilt angle between the substrate surface and the liquid crystal molecules according to the driving method, and forms a stable and uniform alignment layer as well as between the liquid crystal molecules and the alignment layer. Should form a strong anchoring energy of W> 10 ^-4 J / cm ² . This is because the alignment film is an important factor for determining the reliability, the display uniformity, the afterimage and the voltage holding ratio of the liquid crystal display element.

Currently, various polymer compounds are known as liquid crystal alignment films. Among the most commonly used high molecular compounds, there are polymer compositions such as polyamic acid and soluble polyimide, which are used by imidating polyamic acid. These are widely used industrially as an aligning agent which orientates a liquid crystal with excellent heat resistance and chemical resistance. On the other hand, these high molecular compounds are formed by polymerization of diamine and tetracarboxylic dianhydride, the monomer structure exhibits the material properties of the high molecular compound.

The basic requirement of the liquid crystal alignment film is the control of the pretilt angle. It is known that the pretilt angle of liquid crystal molecules is greatly influenced by the shape of the alignment film surface and the length of the side chains. In particular, in the liquid crystal display of the IPS mode, a low pretilt angle of about 1 to 2 degrees is required.

The driving method of the liquid crystal display device is a twist nematic mode in which nematic liquid crystal molecules are arranged between two transparent electrode substrates on which an alignment layer is coated on a transparent electrode, and super twist nematic (Super) mode. twist nematic (hereinafter referred to as "STN") mode, in-plane switching (hereinafter referred to as "IPS") mode, vertical alignment (hereinafter referred to as "VA") mode and thin film transistor (hereinafter referred to as "TFT") Can be classified into a TFT type.

In an IPS type liquid crystal display device having an improved viewing angle, two linear and linear electrodes are formed on one of two parallel substrates. The long axis of the liquid crystal molecules of the liquid crystal layer filled between the two substrates is parallel to the two substrates and arranged in a direction parallel to or at an angle with the electrodes. When an electric field is applied to both electrodes, the long axis of the liquid crystal molecules is arranged parallel to the electric field by an electric field parallel to the substrate. However, the conventional IPS type liquid crystal display device has a problem in that light leakage occurs in a dark state, resulting in a low contrast ratio, and a slow response speed of liquid crystal molecules.

In the IPS mode, lateral symmetrical viewing angle characteristics can be obtained by using a transverse electric field method in which liquid crystal molecules are driven in the same plane. The transverse electric field method of applying an electric field in a direction parallel to the substrate by forming an electrode only on one side of the substrate has a wider viewing angle characteristic than the conventional electric field method of driving a liquid crystal by applying a voltage to electrodes formed on the upper and lower substrates. It is known as a liquid crystal display element which can display. The liquid crystal display element using such a transverse electric field system is described in Unexamined-Japanese-Patent No. 5-505247, for example.

As described above, the transverse electric field type liquid crystal cell has excellent viewing angle characteristics, but since there are few electrode portions formed in the substrate, static electricity is likely to accumulate in the liquid crystal cell, and charges are generated in the liquid crystal cell even by application of an asymmetric voltage generated by driving. These accumulated charges have a problem of dispersing the orientation of the liquid crystal or affecting the display as an afterimage or afterimage persistence, thereby significantly lowering the display quality of the liquid crystal element. Therefore, in order to exhibit a low pretilt angle (1-2 degrees) and to reduce an afterimage, especially in a transverse electric field drive liquid crystal display element, the improvement of the characteristic of a liquid crystal aligning film is calculated | required.

In order to solve the problems of the prior art as described above, the present invention provides a stable alignment of the liquid crystal, excellent rubbing resistance, high voltage retention and contrast, as well as a low pretilt angle, and a dia which can reduce the afterimage of the liquid crystal. An object of the present invention is to provide a minobenzene derivative, a manufacturing method thereof, and a liquid crystal aligning film using the same.

In order to achieve the above object, the present invention provides a diamino benzene derivative represented by the following formula (1).

[Formula 1]

In Formula 1, A ₁ to A ₅ are each independently -H, -F, -CF 3, -OCF 3, an alkyl group having 1 to 7 carbon atoms, an alkoxy group having 1 to 7 carbon atoms, and the following Formula 2a, 2b, 2c, or 2d And at least one of A ₁ to A ₅ is not -H.

[Formula 2a]

[Formula 2b]

[Formula 2c]

[Formula 2d]

In Formulas 2a, 2b, 2c, and 2d, each R independently represents an alkyl group having 1 to 7 carbon atoms or an alkoxy group having 1 to 7 carbon atoms.

In addition, the present invention

a) reacting a compound of Formula 3 with 4,4-dichlorobenzophenone to prepare a compound of Formula 4;

b) dehydrating the compound of formula 4 on paratoluenesulphonic acid and toluene to prepare a compound of formula 5;

c) preparing a compound of Chemical Formula 6 by reacting the compound of Chemical Formula 5 with lithium bis (trimethylsilyl) amide, (dibenzylithene acetone) palladium, and tricyclohexylphosphine;

d) hydrogen-reducing the compound of Formula 6 under a Pd / C catalyst and recrystallization of the compound to separate

It provides a method for producing a diamine compound represented by the formula (1) comprising a.

[Formula 3]

[Formula 4]

[Formula 5]

[Formula 6]

In Formulas 3 to 6, A ₁ to A ₅ are as described above.

In addition, the present invention

a) preparing a polyamic acid block copolymer of Chemical Formula 9 by reacting the diamine compound of Chemical Formula 1 with a tetracarboxylic anhydride of Chemical Formula 7 and a diamine compound having no side chain group of Chemical Formula 8 under a solvent; And

iii) converting the polyamic acid-based block copolymer into polyimide by dehydrating ring reaction

It provides a method for producing a polyimide resin for the alignment agent of the liquid crystal display device represented by the following formula (10) comprising a.

[Formula 7]

[Formula 8]

In Formulas 7 to 8, X is a tetravalent organic group, and Z is a divalent organic group without side chain groups.

[Formula 9]

[Formula 10]

In Formulas 7 to 10, X is a tetravalent organic group, Y is a branched divalent organic group derived from Formula 1, Z is a divalent organic group without a side chain group, wherein m is 1, n is one or more Is an integer.

In addition, the present invention provides a polyimide resin for an alignment agent of a liquid crystal display device having a weight average molecular weight of 1,000 to 200,000 made by the above method.

In another aspect, the present invention provides a liquid crystal alignment film characterized in that it is produced using a polyimide resin for the alignment agent of the liquid crystal display device.

In another aspect, the present invention provides a liquid crystal display device comprising the liquid crystal alignment film.

Hereinafter, the present invention will be described in detail.

The liquid crystal alignment data of the present invention has a diamine such as Chemical Formula 1 by stably aligning the liquid crystal, excellent rubbing resistance, high voltage retention and contrast, low pretilt angle, and particularly designed side chains to reduce afterimages of the liquid crystal. It is characterized by the use of compounds.

The diamine compound of Formula 1 may be prepared by the same method as in Scheme 1.

First stage

After cooling the solution of the compound of Formula 3 and magnesium in ether under a nitrogen atmosphere to room temperature, a solution of 4,4-dichlorobenzophenone in tetrahydrofuran is slowly added dropwise to obtain the compound of Formula 4.

2nd step

The compound of formula 4 may be dehydrated under paratoluenesulphonic acid 1-hydrate to obtain a compound of formula 5.

3rd step

The compound of formula 5 may be reacted with lithium bis (trimethylsilyl) amide, bis (dibenzylideneacetone) palladium, and tricyclohexylphosphine to obtain a diamine compound of formula 6 below.

4th step

The compound of Formula 6 may be hydrogen reduced under a Pd / C catalyst and the isomers may be separated to obtain the final diamine compound of Formula 1.

Scheme 1

In Scheme 1, A ₁ to A ₅ are the same as defined above.

In addition, the present invention provides a method for producing a polyimide resin and a polyimide resin using the diamine compound of the formula (1), a) a diamine compound of the formula (1), tetracarboxylic anhydride of the formula (7) Reacting a diamine compound having no side chain group to prepare a polyamic acid-based block copolymer of Formula 9; And iii) heat treating the polyamic acid-based block copolymer to convert the polyamic acid-based block copolymer into polyimide by a dehydration ring reaction.

As a specific example, tetracarboxylic dianhydride of Chemical Formula 7 is slowly added in a nitrogen atmosphere while maintaining 5 ° C. in a reaction solution in which the branched diamine compound of Chemical Formula 1 and the diamine of Chemical Formula 8 are dissolved in N-methyl-2-pyrrolidone. After the dropwise addition, the mixture was stirred for 6 hours to prepare a polyamic acid-based block copolymer. At this time, the viscosity can be adjusted using a cellosolve solvent such as diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, ethylene glycol monobutyl ether and the like.

Then, the present invention can be converted to a polyimide by a dehydration ring reaction by heat-treating the polyamic acid-based block copolymer for 100 minutes to 250 ℃ for 30 minutes to 2 hours.

In addition, the polyamic acid may be converted into a polyimide through a chemical imidization reaction by stirring at 0 to 180 ° C. for 1 to 100 hours in the presence of a basic catalyst and an acid anhydride. The polyimide solution thus obtained is preferably recovered by precipitation as mentioned in the above polyamic acid synthesis.

The solvent used for preparing the polyamic acid is not particularly limited as long as the produced polyamic acid is dissolved, but specific examples thereof include N-methyl-2-pyrrolidone (NMP), N, N-dimethylformamide (DMF), and N. , N-dimethylacetamide, N-methylcaprolactam, dimethyl sulfoxide (DMSO), r-butyrolactone, hexamethylphosphoamide, tetramethylenesulfone, p-chlorophenol, p-bromophenol, 2- Chloro-4-hydroxytoluene, dioxane, tetrahydrofuran (THF), cyclohexanone and the like. Moreover, even if it is a solvent which does not dissolve a polyamic acid, you may mix and use it with the said solvent in the range which does not precipitate the produced polyamic acid. Furthermore, since water in the organic solvent inhibits the polymerization reaction and causes hydrolysis of the produced polyamic acid, it is preferable to use an organic solvent dehydrated if possible.

X in tetracarboxylic dianhydride in the production step of the polyamic acid is a tetravalent organic group. Specific examples include 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride (BTDA), 4,4'-oxydiphthalic anhydride (ODPA), 3,3', 4,4'-biphenyltetra Carboxylic dianhydride (BPDA), 1,2,4,5-benzenetetracarboxylic dianhydride (PMDA), cyclobutanetetracarboxylic dianhydride (CBDA) and 4- (2,5-didoxotetrahydrofuran-3-yl ) -1,2,3,4, -tetrahydronaphthalene-1,2-carboxylic dianhydride (TDA).

In addition, the diamine for constituting Y having a nitrogen atom of Formula 9 'or 10 is a diamine derived from Formula 1. Benzyl group derivatives linked to methylene groups located at the end of the diamine side chains may exhibit horizontal orientation, and the main chain, the side chain diamines, and the tetracarboxylic dianhydride containing a lot of aromatics may increase the surface polarity and at the same time increase the surface tension of the alignment layer. Increase the low pretilt angle. Benzyl groups linked with amines can also increase solubility by creating spaces through which organic solvents can penetrate between chains.

In addition, the diamine compound which does not have a lateral substituent can be used for the said diamine compound for forming Z which has the nitrogen atom of the said Formula (9) or (10). Specifically, 4,4'-diaminodiphenyl ether (ODA), 4,4'-methylenebiscyclohexylamine (PACM), 4,4'-methylene-2-methylcyclohexylamine (ANCAMINE), 4, 4'-methylenedianiline, diaminobenzophenone, 4,4'-methylenediphenyldiamine (MDA), 4.4'-hexafluoroisopropyldiphenyldiamine (6FDA), p-phenylenediamine ( p- PDA) and the like There is this.

When the tetracarboxylic dianhydride component and the diamine component are reacted in an organic solvent in order to obtain a polyamic acid, 5-100 degreeC is preferable normally. At high temperatures, the polymerization terminates quickly, but care must be taken as the molecular weight of the polymer may be too high. In addition, the reaction concentration is 5 to 30% by weight so that uniform stirring is performed to obtain the required molecular weight. The obtained polyamic acid can be used by diluting the reaction solution, and can also be used by re-dissolving through recovery of precipitation. The poor solvent used for the precipitation recovery is not particularly limited, but examples thereof include methanol, ethanol, hexane, acetone, butyl cellosolve, methyl ethyl ketone, toluene, benzene and diethyl ether. The polyamic acid precipitate obtained by adding to a poor solvent can be collected by filtration, washing | cleaning, collect | recovered, and normal temperature or heat-drying under normal pressure or a reduced pressure can be obtained as solid content.

In the polyimide, the side chain type divalent organic group (Y) is used to impart the functionality of the polyimide such as liquid crystal alignment, solubility and membrane permeability, and the side chain-free divalent organic group (Z) is side chain by adjusting the distance between the side chains. Used to determine the distribution of groups. In Formula 7, m is 1, n is an integer of 1 to 10, more preferably 2 to 4.

The side chain length of the side chain type divalent organic group (Y) is preferably adjusted so that the ratio of the average length of the long axis of the liquid crystal molecules is 0.8 to 1.5 times, and the length between the side chain groups is 1.5 to 3.5 times the length of the long axis of the liquid crystal molecules. It is preferable to determine the kind and the amount of use of the divalent organic group (Z) having no side chain group. In this manner, a polyimide resin having a specific structure capable of producing excellent orientation in polyimide and having excellent properties in solubility, membrane permeability, and chemical stability can be prepared. Preferably, the weight average molecular weight of the polyimide resin is 1,000 to 200,000.

In addition, the present invention provides a liquid crystal alignment layer using the polyimide resin, the liquid crystal alignment layer may be obtained by coating the alignment liquid containing the polyimide compound on a patterned substrate and then firing. The solvent used in the alignment liquid is generally used in the liquid crystal alignment liquid, and is not particularly limited as long as it can dissolve the polyimide compound. Preferably, the alignment liquid contains 1 to 30% by weight of the polyimide compound. .

The liquid crystal alignment film of the present invention is excellent in liquid crystal alignment and rubbing resistance, has a high voltage retention and contrast, reduces charge accumulation, and has an inclination angle of 1 to 2 degrees with respect to the nematic liquid crystal, so that there is no afterimage.

Hereinafter, the present invention will be described in detail based on the following examples, but the scope of the present invention is not limited by the following examples.

Example 1

The diamine compound of formula 1 was synthesized by Scheme 1. The synthesis method for each step is as follows.

First stage

In a nitrogen atmosphere, iodine fragment and 3.5 g of magnesium were added to 100 ml of ether and slowly refluxed, and 22.1 g of methylbenzyl bromide was slowly added to 100 ml of ether to reflux for 2 hours to prepare a Grignard reaction. After cooling to room temperature, 20 g of 4,4-dichlorobenzophenone was dissolved in 150 ml of tetrahydrofuran and slowly added dropwise to reflux for 1 hour and 30 minutes. After the reaction was cooled, 10 ml of saturated ammonium chloride was added, filtered through Celite, extracted with chloroform and sodium chloride, dried over anhydrous magnesium sulfate, and distilled under reduced pressure to obtain 1,1-bis- (4-chloro-phenyl) -2-. A light yellow liquid of methylphenyl ethanol was obtained. (25 g, 90%)

¹ H NMR (CDCl ₃ , ppm): 7.20 (d, 4H), 7.13 (d, 4H), 7.09 (d, 1H), 6.93 (d, 1H), 6.92 (s, 1H), 6.88 (d, 1H ), 3.32 (d, 2H), 2.35 (d, 3H), 2.00 (s, 1H)

2nd step

1,1-Bis- (4-chloro-phenyl) -2-phenyl ethanol and 35 g p-toluene sulfonic acid monohydrate into the (p -toluenesulfonic acid, 1-hydrate ) 2.7 g of toluene were placed 200 ml. The solution was reacted by refluxing for 12 hours. After completion of the reaction by TLC plate, washed with saturated sodium chloride and ether and extracted. The remaining water was dried over anhydrous magnesium sulfate and distilled under reduced pressure to obtain a brown 1,1-bis- (4-chloro-phenyl) -2-methylphenyl ethylene liquid. (31 g, 95%)

¹ H NMR (CDCl ₃ , ppm): 7.36 (d, 4H), 7.27 (d, 4H), 7.23 (d, 1H), 7.22 (s, 1H), 7.14 (d, 1H), 6.92 (s, 1H ), 6.91 (d, 1H), 2.35 (d, 3H)

3rd step

20 g of 1,1-bis- (4-chloro-phenyl) -2-methylphenyl ethylene, 43.2 g of lithium bis (trimethylsilyl) amide, 2.6 g of tricyclohexylphosphine, 5.3 g of bis (dibenzylideneacetone) palladium 150 ml of toluene was added. The reaction vessel was kept at 90 ° C. in a nitrogen atmosphere for 12 hours. Reaction progress was confirmed by GC / Mass. 200 ml of ether was added to dilute the reaction mixture, and 300 ml of 1 N hydrochloric acid was added to terminate the reaction. The organic layer and the aqueous layer were washed with 1 N sodium hydroxide and ether, and extracted. The organic layer was filtered after drying by adding anhydrous magnesium sulfate. The solvent was distilled off under reduced pressure and the obtained mixture was recrystallized from methylene chloride to obtain a white 1,1-bis- (4-amino-phenyl) -2-methylphenyl ethylene solid. (9g, 50%)

¹ H NMR (CDCl ₃ , ppm): 7.23 (d, 1H), 7.22 (s, 1H), 7.14 (d, 1H), 7.17 (d, 4H), 6.91 (d, 1H), 6.92 (s, 1H ), 6.46 (d, 4H), 3.74 (s, broad, 4H), 2.35 (d, 3H)

4th step

10 g of 1,1-bis- (4-amino-phenyl) -2-methylphenyl ethylene was dissolved in benzene and ethanol, followed by 1 g of palladium (10 wt% on activated carbon) for 5 hours under a pressure of 4 kg / cm 2. Stirred. After confirming the completion of the reaction, the mixture was filtered using Celite, and the solution was distilled under reduced pressure to obtain a white solid. This solid was recrystallized with ethylene acetate and ethanol to obtain white solid 1,1-bis- (4-amino-phenyl) -2-methylphenyl ether. (5 g, 50%)

¹ H NMR (CDCl ₃ , ppm): 7.09 (t, 1H), 6.93 (d, 1H), 6.92 (s, 1H), 6.88 (d, 1H), 6.87 (d, 4H), 6.41 (d, 4H ), 4.44 (t, 1H), 3.74 (s, broad, 4H), 3.17 (d, 2H), 2.35 (d, 3H)

Example 2

Synthesis of 1,1-bis- (4-amino-phenyl) -2-fluorophenyl ether in the same manner as in Example 1 except that fluorobenzyl bromide was used instead of the methylbenzyl bromide of Example 1 It was. (5 g, 20%)

¹ H NMR (CDCl ₃ , ppm): 7.19 (t, 1H), 6.89 (d, 1H), 6.87 (s, 1H), 6.79 (d, 1H), 6.87 (d, 4H), 6.41 (d, 4H ), 4.44 (t, 1H), 3.75 (s, broad, 4H), 3.17 (d, 2H)

Example 3

6.3 g of 1,1-bis- (4-amino-phenyl) -2-methylphenyl ether and 8.3 g of 4,4'-diaminodiphenyl ether (ODA) were added to N-methyl-2-pyrrolidone 122 under a nitrogen atmosphere. 20 g of 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride (BTDA) was added while maintaining in 5 g. 132 g of remaining N-methyl-2-pyrrolidone was slowly added dropwise for 2 hours, and reacted for 10 hours. The reaction solution was poured into excess ultrapure water and the precipitate precipitated was filtered. The filtrate was washed with methyl alcohol and dried under reduced pressure in a vacuum oven at 50 ° C. to obtain a polyamic acid. (Weight average molecular weight = 60,000)

Example 4

Except for replacing 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride (BTDA) used in Example 3 with 3,3', 4,4'-biphenyltetracarboxylic dianhydride (BPDA) Then, a polyamic acid solid content was obtained in the same manner as in Example 3. (Weight average molecular weight = 70,000)

Example 5

Except for replacing 1,1-bis- (4-amino-phenyl) -2-methylphenyl ether used in Example 3 with 1,1-bis- (4-amino-phenyl) -2-fluorophenyl ether Then, a polyamic acid solid content was obtained in the same manner as in Example 3. (Weight average molecular weight = 60,000)

Example 6

1,1-bis- (4-amino-phenyl) -2-methylphenyl ether used in Example 3 was replaced with 1,1-bis- (4-amino-phenyl) -2-fluorophenyl ether 3, Same as Example 3, except that 3 ', 4,4'-benzophenonetetracarboxylic dianhydride (BTDA) was replaced with 3,3', 4,4'-biphenyltetracarboxylic dianhydride (BPDA) The polyamic acid solids were obtained by the method. (Weight average molecular weight = 70,000)

Comparative Example 1

Except for replacing the 1,1-bis- (4-amino-phenyl) -2-methylphenyl ether used in Example 3 with 1,1-bis- (4-amino-phenyl) -2-phenyl ether , The polyamic acid solid content was obtained in the same manner as in Example 3. (Weight average molecular weight = 60,000)

Property evaluation method used the following methods.

① Weight average molecular weight of polymer

Gel permeation chromatography (GPC) was measured to calculate the weight average molecular weight of the polymer. The retention time of the column filled with the polymer material was measured by using dimethyl acetamide (DMAc) as a mobile phase at 60 ° C, and the average molecular weight of the polyamic acid solid was calculated from the results obtained by correcting the average molecular weight and retention time of the styrene polymer. It was. The polymer constituting the liquid crystal aligning agent has a value of a weight average molecular weight of about 1,000 to 200,000 g / mol.

② Pretilt angle of liquid crystal display element

It was measured by crystal rotation method using He-Ne laser light according to the method described in T. J. Schffer, et. Al., J., Appl., Phys., Vol. 19, 2013 (1980).

③ orientation of liquid crystal

The presence or absence of an abnormal domain in the liquid crystal cell when the voltage was turned on or off in the liquid crystal display element was observed under a microscope, and it was judged as 'good' that there was no abnormal domain.

④ Voltage retention of liquid crystal display element

After applying a voltage of 5 V to the liquid crystal display element for 60 micrometer seconds, the voltage retention after 16.67 milliseconds from the release of the application was measured.

⑤ Contrast ratio

The light transmittance in a voltage-free state (dark state) and the light transmittance under voltage (bright state) at which the light transmittance becomes maximum were measured and calculated for the liquid crystal display element.

⑥ Afterimage evaluation

A liquid crystal aligning agent was printed, dried, and fired on a substrate having a zigzag electrode (super-IPS) having an electrode width of 5 μm and an interelectrode spacing of 10 μm, thereby producing a thin film having a thickness of 200 nm. A liquid crystal aligning agent was printed, dried, and fired on a glass substrate, thereby producing a thin film having a thickness of 200 nm. (Substrate 2) The substrate 1 was subjected to a rubbing treatment with a liquid crystal aligning agent having an angle of 20 degrees in the electrode direction. In addition, the substrate 2 is subjected to a rubbing treatment so that the rubbing direction is parallel to the substrate 1, the spacers are scattered and bonded to the substrate to form a cell having a gap of 4 µm, and a liquid crystal MJ991735 (manufactured by Merck Co., Ltd.) is injected into the cell to form a liquid crystal. The cell was fabricated. The voltage-transmittance (V-T) characteristics of the liquid crystal cell were measured at a frequency of 1 kHz at a rate of 0.1 V / s from 0 to 10 V and applied to the liquid crystal cell, and then a DC voltage of 10 V was applied for 30 minutes. Immediately after the DC voltage was turned off, the V-T characteristic was measured again, and the afterimage was evaluated from the change in the voltage-transmittance characteristic before and after applying the DC voltage. In other words, when the transmittance upon application of a constant voltage is changed by the V-T characteristic causing a change, it is observed as an afterimage in the region.

In addition, the polyamic acid solids prepared in Examples 3 to 6 and Comparative Example 1 were added to a solvent in which NMP and 2-butoxyethanol were mixed at a 3: 1 weight ratio to obtain a solution having a concentration of 4% by weight. The solution was filtered with a filter of 0.1 mu m and coated with a spinner method to a thickness of 600 mm on a glass substrate on which a transparent conductive film was patterned. After application | coating, it prebaked for 3 minutes at 90 degreeC, and baked at 210 degreeC for 1 hour, and obtained the board | substrate with a polyimide aligning film.

In addition, after aligning the obtained alignment film by ultrasonic cleaning for 3 minutes in ethanol, the surface of the alignment film obtained by using two glass substrates, a glass substrate with an IPS comb-shaped electrode and a glass substrate without electrodes, was dried with an oven of 4 micro After spreading and bonding the gap material, a liquid crystal was injected and sealed with an epoxy curing agent to prepare a liquid crystal cell. The characteristics of the liquid crystal cell thus produced are shown in Table 1 below.

[Table 1] Characteristics of Liquid Crystal Cell

division Pretilt angle (degrees) Voltage retention rate (%) Contrast Orientation afterimage Example 3 1.5 (± 0.2) 99 100 Good none Example 4 1.5 (± 0.2) 98 100 Good none Example 5 1.5 (± 0.2) 99 100 Good none Example 6 1.5 (± 0.2) 98 100 Good none Comparative Example 1 1.5 (± 0.2) 97 98 Good has exist

As shown in Table 1, in the case of Examples 3 to 6 and Comparative Example 1 of the present invention, it can be seen that both exhibit excellent characteristics as the liquid crystal alignment agent for driving the transverse electric field and at the same time excellent voltage retention and orientation. In particular, Examples 3 to 6 it can be seen that the afterimage is significantly reduced than Comparative Example 1.

As described above, the side chain type diamine compound of the general formula (1) of the present invention is useful as a liquid crystal aligning agent for transverse electric field driving, and the polyimide resin prepared using the diamine compound has a stable liquid crystal orientation and a rubbing resistance. It is excellent and can express a low pretilt angle of 1.5 ± 0.2 degrees, and furthermore, the polyimide resin according to the present invention is remarkably improved in terms of contrast and afterimage reduction, which is useful as an alignment agent of a liquid crystal display device.

Claims (9)

Diamino benzene derivative represented by the following formula (1): [Formula 1]

In Formula 1, A ₁ to A ₅ are each independently -H, -F, -CF 3, -OCF 3, an alkyl group having 1 to 7 carbon atoms, an alkoxy group having 1 to 7 carbon atoms, and the following Formula 2a, 2b, 2c, or 2d; , At least one of A₁ to A ₅ is not -H. [Formula 2a]

[Formula 2b]

[Formula 2c]

[Formula 2d]

In Formulas 2a, 2b, 2c, and 2d, each R independently represents an alkyl group having 1 to 7 carbon atoms or an alkoxy group having 1 to 7 carbon atoms. a) reacting a compound of Formula 3 with 4,4-dichlorobenzophenone to prepare a compound of Formula 4; b) dehydrating the compound of formula 4 on paratoluenesulphonic acid and toluene to prepare a compound of formula 5; c) preparing a compound of Chemical Formula 6 by reacting the compound of Chemical Formula 5 with lithium bis (trimethylsilyl) amide, (dibenzylithene acetone) palladium, and tricyclohexylphosphine; d) separating the compound of Formula 6 by hydrogen reduction under a Pd / C catalyst and recrystallization of the compound Method for producing a diamine compound represented by the formula (1) comprising: [Formula 3]

[Formula 4]

[Formula 5]

[Formula 6]

In Formulas 3 to 6, A ₁ to A ₅ are as described above. a) preparing a polyamic acid block copolymer represented by Chemical Formula 9 by reacting the diamine compound of Chemical Formula 1 with a tetracarboxylic acid anhydride of Chemical Formula 7 and a diamine compound having no side chain group of Chemical Formula 8 under a solvent; And b) heat-treating the polyamic acid-based block copolymer to convert it to polyimide by dehydration ring reaction Method for producing a polyimide resin for the alignment agent of the liquid crystal display device represented by the following formula (10) comprising: [Formula 7]

[Formula 8]

[Formula 9]

[Formula 10]

In Formulas 7 to 10, X is a tetravalent organic group, Y is a branched divalent organic group derived from Formula 1, Z is a divalent organic group without a side chain group, wherein m is 1, n is one or more Is an integer. The method of claim 3, N is a method for producing a polyimide resin for an alignment agent of a liquid crystal display device, characterized in that n is an integer of 1 to 10 in the formula (10). The method of claim 3, The solvent is N-methyl-2-pyrrolidone (NMP), N, N-dimethylformamide (DMF), dimethylsulfoxide (DMSO), hexamethylphosphoamide, tetramethylenesulfone, p-chlorophenol, p A poly for the alignment agent of the liquid crystal display device, wherein the solvent is at least one solvent selected from the group consisting of bromophenol, 2-chloro-4-hydroxytoluene, dioxane, tetrahydrofuran (THF), and cyclohexanone. Method for producing a mid resin. The polyimide resin for the alignment agent of the liquid crystal display device manufactured by the manufacturing method of Claim 3 whose weight average molecular weight is 1,000-200,000. The method of claim 6, The side chain length of the polyimide is 0.8 to 1.5 times the length of the long axis of the liquid crystal molecules, and the length between the side chains is 1.5 to 3.5 times the length of the major axis of the liquid crystal molecules. It is manufactured using the polyimide resin for aligning agents of the liquid crystal display device of Claim 6, The liquid crystal aligning film characterized by the above-mentioned. A liquid crystal display device comprising the liquid crystal alignment film as set forth in claim 8.