KR20040023201A - Novel Functional Diamines and LC Alignment Layer Prepared by Using the Same - Google Patents

Abstract

PURPOSE: A novel functional diamine compound, a polyamic acid prepared by using the diamine compound, a liquid crystal alignment layer prepared by using the polyamic acid and a liquid crystal display device containing the liquid crystal alignment layer are provided, to improve heat resistance, transmittance at visible light range, alignment characteristic and voltage holding ratio. CONSTITUTION: The diamine compound is represented by the formula 1, wherein A is H or a methyl group; B is -O-, -COO-, -CONH-, -OCO- or a single bond; and C is a linear, branched or cyclic alkyl group of C1-C20, an arylalkyl or alkylaryl group of C7-C30, or a cholesterol group of C16-C40; and the functional group can be substituted with a fluorinated alkyl group of C1-C20. The polyamic acid is prepared by copolymerizing the diamine compound of the formula 1, an aliphatic cyclic acid dianhydride, an aromatic cyclic acid dianhydride and optionally an aromatic cyclic diamine. Preferably the polyamic acid is represented by the formula 6.

Description

Novel Functional Diamines and LC Alignment Layer Prepared by Using the Same

The present invention relates to a novel functional diamine and a liquid crystal aligning film prepared using the same, and more particularly to producing a polyamic acid using the functional diamine, high heat resistance, high permeability in the visible light region, excellent alignment characteristics and high Provided is a liquid crystal alignment film having a voltage holding ratio and an easy adjustment of a pretilt angle.

Generally, the polyimide resin for liquid crystal aligning film currently used uses a pyromellitic dianhydride (PMDA), a non-phthalic dianhydride (BPDA) as an aromatic acid dianhydride, and paraphenylenediamine (p-) as an aromatic diamine component. PDA), metaphenylenediamine (m-PDA), 4,4-methylenedianiline (MDA), 2,2-bisamino phenylhexafluoropropane (HFDA), metabisaminophenoxydiphenylsulfone (m-BAPS ), Parabisaminophenoxydiphenylsulfone (p-BAPS), 4,4-bisaminophenoxyphenylpropane (BAPP), 4,4-bisaminophenoxyphenylhexafluoropropane (HF-BAPP) and the like are used. By condensation polymerization of these monomers.

However, when only aromatic acid dianhydride and diamine are used as described above, thermal stability, chemical resistance, mechanical properties, etc. are excellent, but transparency and solubility are degraded by charge transfer complex, and electro-optical properties are deteriorated. have. In order to solve this problem, there have been attempts to improve the problem by introducing an aliphatic cyclic acid dianhydride monomer or an aliphatic cyclic diamine (Japanese Patent Laid-Open No. 11-84391), and a functional diamine having a side chain for increasing the pretilt angle and stability of the liquid crystal. Functional acid dianhydrides having side chains and the like have been introduced (Japanese Patent Laid-Open No. 06-136122).

However, with the recent growth of the liquid crystal display device market, the demand for high quality display devices is continuously increasing, and the demand for high productivity productivity alignment films is increasing in liquid crystal display device manufacturers. Therefore, there is a demand for the development of an alignment film having a low defect rate, excellent electro-optical characteristics, and high reliability in a mass production process. Accordingly, excellent electro-optical characteristics such as high printability and high voltage holding ratio of the liquid crystal alignment layer, and maintaining the reliability of the display device with respect to long-term voltage application are increasing.

Existing functional diamines developed and applied to express high pretilt angles in the alignment layer have decreased reactivity due to steric hindrance of the side chains adjacent to the reaction functional groups to obtain high molecular weight polymers containing 10 mol% or more of such functional diamines. Was hard. Therefore, there is a problem that the physical properties of the resulting polymer is inferior, and the reliability of the alignment layer is degraded due to the remaining of unreacted amine.

The present invention is to solve the problems of the prior art as described above, to provide a new functional diamine excellent in reactivity by minimizing the steric hindrance effect of the side chain, using this to implement a pretilt angle to the desired size up to 3 ° ~ 90 ° It is an object of the present invention to provide a liquid crystal aligning film which can exhibit excellent alignment properties and is excellent in electro-optical properties.

That is, the present invention relates to a diamine compound represented by the following formula (1).

[Formula 1]

Wherein A is a hydrogen atom or a methyl group,

B is -O-, -COO-, -CONH-, -OCO-, or a single bond,

C is a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, an arylalkyl group or alkylaryl group having 7 to 30 carbon atoms, or a cholesterol group having 16 to 40 carbon atoms, and the functional group has 1 to 20 carbon atoms. Fluorinated alkyl groups may be substituted.

Another aspect of the present invention relates to a polyamic acid prepared by copolymerizing the functional diamine, aliphatic cyclic acid dianhydride, and aromatic cyclic acid dianhydride with an aromatic cyclic diamine.

Another aspect of the present invention relates to a liquid crystal alignment film obtained by dissolving the polyamic acid in a solvent and coating the same, and imidating it in whole or in part.

1 is a ¹ H-NMR spectrum of the functional diamine prepared in Preparation Example 2, and

2 is a TGA spectrum of the functional diamine prepared in Preparation Example 2. FIG.

The present invention will be described in more detail below.

Functional diamine newly provided in the present invention is represented by the following formula (1).

Wherein A is a hydrogen atom or a methyl group,

B is -O-, -COO-, -CONH-, -OCO-, or a single bond,

C is a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, an arylalkyl group or alkylaryl group having 7 to 30 carbon atoms, or a cholesterol group having 16 to 40 carbon atoms, and the functional group includes a fluorinated alkyl group having 1 to 20 carbon atoms. Can be substituted.

As the C unit in the functional diamine compound, a structure represented by the following general formula (2) is preferably used.

or

Wherein x is an integer from 0 to 19.

In addition, as the cholesterol structure included in the C unit, the structure shown in Formula 3 is illustrated, but is not limited thereto, and other steroid structures may be used.

or

R is a hydrogen atom or a linear or branched alkyl group having 1-20 carbon atoms.

Representative examples of such functional diamines include compounds represented by the following formulas (4) and (5).

The polyamic acid according to the present invention is prepared by copolymerizing functional diamines, aliphatic cyclic acid dianhydrides and aromatic cyclic acid dianhydrides with a specific structure having the above-described side chains, and optionally including aromatic cyclic diamines therein.

By containing the said functional diamine in the polyamic acid of this invention, adjustment of a pretilt angle becomes easy and it shows the outstanding orientation. Since the pretilt angle is adjusted according to the content of the functional diamine, it is also possible to prepare a polyamic acid using only the functional diamine and use it as the liquid crystal alignment layer, depending on the mode of the liquid crystal display, without containing any aromatic cyclic diamine. The use of aromatic diamines is optional.

The content of the functional diamine accounts for 0.1 to 100 mol%, preferably 3 to 50 mol%, more preferably 5 to 30 mol% of the total diamine monomers.

Aromatic cyclic diamines used in the preparation of the polyamic acid of the present invention include paraphenylenediamine (p-PDA), 4,4-methylenedianiline (MDA), 4,4-oxydianiline (ODA), metabisamino Phenoxydiphenylsulfone (m-BAPS), parabisaminophenoxydiphenylsulfone (p-BAPS), 2,2-bisaminophenoxyphenylpropane (BAPP), 2,2-bisaminophenoxyphenylhexafluoropropane (HF-BAPP) and the like, but is not limited thereto.

The amount of the aromatic cyclic diamine is 0 to 99.9 mol%, preferably 50 to 97 mol%, more preferably 70 to 95 mol% relative to the total diamine content.

The aromatic cyclic acid dianhydride used in the production of the polyamic acid of the present invention can withstand the rubbing process in which the alignment film coated at about 0.1 μm is applied to induce the unidirectional alignment of the liquid crystal, and the heat resistance to the high temperature processing process of 200 ° C. or higher. It is maintained, and excellent chemical resistance can be expressed.

Such aromatic cyclic acid dianhydrides include pyromellitic dianhydride (PMDA), nonphthalic dianhydride (BPDA), oxydiphthalic dianhydride (ODPA), benzophenone tetracarboxylic dianhydride (BTDA), and hexafluoroisopropylidenedidie Phthalic dianhydride (6-FDA), but is not limited thereto.

The content of the aromatic cyclic acid dianhydride is 10 to 80 mol%, more preferably 10 to 50 mol% relative to the total content of the acid dianhydride used. If the aromatic cyclic acid dianhydride is 10 mol% or less, the mechanical properties, heat resistance, etc. of the alignment film are lowered, and if it is 80 mol% or more, electrical properties such as voltage retention are lowered.

The aliphatic cyclic acid dianhydride used in the preparation of the polyamic acid of the present invention is insoluble in a general organic solvent, low permeability in the visible light region by a charge transfer complex, and electro-optical properties due to its molecular structurally high polarity. It compensates for problems such as degradation.

As the aliphatic cyclic acid dianhydride, 5- (2,5-dioxotetrahydrofuryl) -3-methylcyclohexene-1,2-dicarboxylic acid anhydride (DOCDA), bicyclooctene-2,3,5 , 6-tetracarboxylic dianhydride (BODA), 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA),

1,2,3,4-cyclopentanetetracarboxylic dianhydride (CPDA), 1,2,4,5-cyclohexanetetracarboxylic dianhydride (CHDA), and the like, but are not limited thereto.

The content is 20 to 90 mol%, preferably 50 to 90 mol% relative to the total acid dianhydride content used.

The polyamic acid of the present invention more preferably has a structure represented by the following formula (6).

In the formula, X represents one or more selected from the functional groups represented by the following formula (7), Y represents one or more selected from the functional groups represented by the following formula (8), Z is selected from the functional groups represented by the following formula (9) At least one functional group or a functional group represented by the following general formula (10) is represented, wherein the proportion of the functional group represented by the general formula (10) in the total Z units is 0.1 to 100 mol%.

Wherein A is a hydrogen atom or a methyl group,

B is -O-, -COO-, -CONH-, -OCO-, or a single bond,

C is a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, an arylalkyl group or alkylaryl group having 7 to 30 carbon atoms, or a cholesterol group having 16 to 40 carbon atoms, and the functional group includes a fluorinated alkyl group having 1 to 20 carbon atoms. Can be substituted.

Polyamic acid according to the present invention is generally used N-methyl-2-pyrrolidone (NMP), gamma-butyrolactone (GBL) dimethylformamide (DMF), dimethylacetamide (DMAc), tetrahydrofuran ( Very good solubility in aprotic polar solvents such as THF). Such excellent solubility is thought to be great in the effect of the functional diamine in which three benzene rings exist in three dimensions with large three-dimensional repulsion in the introduction of aliphatic cyclic acid dianhydride and molecular structure. In the situation where the printability of the alignment agent is very important in recent years due to the large size, high resolution and high quality of the liquid crystal display device, such excellent solubility in solvents has a good effect on the printability to the substrate when applied to the liquid crystal alignment layer. Go crazy.

The polyamic acid of the present invention has a number average molecular weight in the range of 10,000 to 300,000 g / mol, the glass transition is in the range of 200 to 350 ℃ when imidization proceeds.

In the present invention, the polyamic acid is dissolved in a solvent and applied to a substrate, and then imidated in whole or in part to provide a liquid crystal alignment layer.

The alignment film exhibits a high transmittance of 90% or more in the visible light region in light transmittance, is excellent in alignment of liquid crystals, and can be easily adjusted within a range of 3 to 90 °. In addition, since the functional diamine is included, the refractive index of the polymer may be lowered and the dielectric constant may be lowered.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the following Examples are for the purpose of explanation and are not intended to limit the present invention.

Preparation Example 1 Preparation of 3,5-Dibromo-4-methylphenoxyhexadecane

After dissolving 5 g (0.018 mol) of 3,5-dibromo-4-methylphenol in a 500 ml three-necked flask equipped with a stirrer, a cooler, and a nitrogen injector in 100 g of dimethylacetamide (DMAc) as a reaction solvent, potassium carbonate 2.85 g was added. 7.28 g (0.02 mol) of 1-iodohexadecane was added thereto, and the temperature of the reactor was increased to 90 ° C., and the reaction was performed for 24 hours. After the completion of the reaction, the reaction solution was precipitated in distilled water and filtered, and the obtained solid was recrystallized from methanol to obtain pure 3,5-dibromo-4-methylphenoxyhexadecane. (Yield: 92%)

Preparation Example 2 Preparation of 3,5-bis (3-aminophenyl) -4-methylphenoxyhexadecane

Prepare a 250 ml flask with a stirrer, a cooler and a device to make a vacuum and vacuum the inside of the reactor, 3.5 g (0.025 mol) of 3-aminophenylboronic acid, 8.6 g of K ₃ PO ₄ (0.04mol) and tetrabutylammonium bromide

0.66 g (0.002 mol) was added to each other to create an argon atmosphere. After the reactor was vacuumed again, 5.01 g (0.01 mol) of 3,5-dibromo-4-methylphenoxyhexadecane was dissolved in 100 g of dimethylformamide and placed in the reactor, palladium acetate, a metal catalyst.

[Pd (OAc) ₂ ] 0.011g (0.00005mol) was added to make an argon atmosphere again. After raising the temperature of the reactor to 130 ℃ proceeds for 48 hours, it was confirmed that all the starting material 3,5-dibromo-4-methylphenoxyhexadecane disappeared. After completion of the reaction, the temperature of the reactor was lowered to room temperature and 400 g of petroleum ether was added. Extraction was performed using an aqueous solution of 1 molar sodium hydroxide, washed two times or more with brine, and then several times again with pure distilled water to separate only the organic layer. Magnesium sulfate (MgSO ₄ ) was added to the organic layer separated and stirred to remove the remaining water and filtered. The filtrate was evaporated with an evaporator (concentrator) to obtain a solid, and recrystallized with ethanol to give white pure 3,5-bis (3-aminophenyl) -4-methylphenoxyhexadecane. 77%)

3,5-bis (3-aminophenyl) -4-methylphenoxyhexadecane prepared in Preparation Example 2 was a pure white solid, and showed excellent oxidation stability and good solubility in the air. The structure was confirmed by ¹ H-NMR spectrum (FIG. 1), and TGA measurement results showing its pyrolysis behavior are shown in FIG. 2.

Preparation Example 3 Preparation of 2,4-Dibromophenoxyhexadecane

2,4-dibromophenoxyhexadecane was obtained in the same manner as in Preparation Example 1, except that 10 g (0.039 mol) of 2,4-dibromophenol was used, and the yield was 90%. It was.

Preparation Example 4 Preparation of 2,4-bis (3-aminophenyl) phenoxyhexadecane

2,4-bis (3-amino was carried out in the same manner as in Preparation Example 2, except that 10g (0.02 mol) of 2,4-dibromophenoxyhexadecane prepared in Preparation Example 3 was used. Phenyl) phenoxyhexadecane was obtained with a yield of 47%. 2,4-bis (3-aminophenyl) phenoxyhexadecane prepared in Preparation Example 4 was a white solid having a relatively good storage stability in the air, and the structure was confirmed by ¹ H-NMR spectrum.

Example 1

0.95 mol of 4,4-methylenedianiline and 3,5-bis (3-aminophenyl) -4-methylphenoxy while passing nitrogen through a four-necked flask equipped with a stirrer, a thermostat, a nitrogen gas injector and a cooler 0.05 mol of hexadecane was added, and N-methyl-2-pyrrolidone (NMP) was added to dissolve it. Add 0.5 mol of 5- (2,5-dioxotetrahydrofuryl) -3-methylcyclohexane-1,2-dicarboxylic acid anhydride (DOCDA) in solid state and 0.5 mol of pyromellitic dianhydride (PMDA) Stir vigorously. The solid content at this time is 15% by weight in mass ratio, the reaction was carried out for 24 hours while maintaining the temperature below 25 ℃ to prepare a polyamic acid solution (PAA-1).

In order to measure the orientation and pretilt angle of the liquid crystal by rubbing, the polyamic acid solution was applied to an ITO glass substrate with a thickness of 0.1 μm and cured at a temperature of 210 ° C.

In this process, in order to determine the printability of the alignment film, the alignment film was applied to the ITO glass substrate, and the printability was evaluated by observing the spreading property and the end curling property through the naked eye and an optical microscope. After the surface of the alignment film was rubbed using a rubbing machine and the two substrates were rubbed in opposite directions to each other, the cells were bonded to maintain a cell gap of 80 mu m. After filling the liquid crystal in the liquid crystal cell produced by the above method and observing the orientation by a cross-polarized optical microscope, the pretilt angle was measured using a crystal rotation method is shown in Table 1 below.

In addition, in order to investigate the electrical properties, a polyamic acid solution was applied to the ITO surface of the ITO patterned glass substrate with a thickness of 0.1 μm, the cell rubbing direction was twisted at 90 °, and the gap was uniformed to 5 μm. The test cell was prepared by maintaining it, and the voltage holding ratio thereof was measured.

Example 2

Except that 0.9 mol of 4,4-methylenedianiline and 0.1 mol of 3,5-bis (3-aminophenyl) -4-methylphenoxyhexadecane were used in the same manner as in Example 1 above. Polyamic acid solution (PAA-2) was obtained. In addition, the orientation, pretilt angle and voltage retention of the liquid crystal were measured in the same manner as in Example 1, and the results are shown in Table 1 below.

Example 3

Same as Example 1 except that 2,4-bis (3-aminophenyl) phenoxyhexadecane was used in place of 3,5-bis (3-aminophenyl) -4-methylphenoxyhexadecane To give a polyamic acid (PAA-3). In addition, the orientation, pretilt angle and voltage retention of the liquid crystal were measured in the same manner as in Example 1, and the results are shown in Table 1 below.

Example 4

Except for using 0.9 mol of 4,4-methylenedianiline and 0.1 mol of 2,4-bis (3-aminophenyl) phenoxyhexadecane, it was carried out in the same manner as in Example 3 above to obtain a polyamic acid (PAA- 4) was obtained. In addition, the orientation, pretilt angle and voltage retention of the liquid crystal were measured in the same manner as in Example 1, and the results are shown in Table 1 below.

Example 5

Except for using 0.5 mol of 4,4-methylenedianiline and 0.5 mol of 2,4-bis (3-aminophenyl) phenoxyhexadecane, the same procedure as in Example 1 above was carried out to provide polyamic acid (PAA- 5) was obtained. In addition, the orientation, pretilt angle and voltage retention of the liquid crystal were measured in the same manner as in Example 1, and the results are shown in Table 1 below.

Example 6

Polyamic acid (PAA-) was prepared in the same manner as in Example 1 except that 1.0 mol of 2,4-bis (3-aminophenyl) phenoxyhexadecane was used without using 4,4-methylenedianiline. 6) was obtained. In addition, the orientation, pretilt angle and voltage retention of the liquid crystal were measured in the same manner as in Example 1, and the results are shown in Table 1 below.

Comparative Example 1

Polya was carried out in the same manner as in Example 1, except that 1 mol of 4,4-methylenedianiline was used and 3,5-bis (3-aminophenyl) -4-methylphenoxyhexadecane was not used. Mic acid (PAA-7) was obtained. In addition, the orientation, pretilt angle and voltage retention of the liquid crystal were measured in the same manner as in Example 1, and the results are shown in Table 1 below.

Pretilt angle (°) Voltage retention rate (%) Printability Orientation Room temperature 60 ℃ PAA-1 5.3 Over 99 Over 98 Good Good PAA-2 7.2 Over 99 Over 98 Good Good PAA-3 4.4 Over 99 Over 98 Good Good PAA-4 6.5 Over 99 Over 98 Good Good PAA-5 89.9 Over 99 Over 97 Good Good PAA-6 89.9 Over 99 Over 97 Good Good PAA-7 1.9 Over 98 Over 97 usually Good

As shown in Table 1 above, the liquid crystal alignment layer of the present invention has a voltage retention of 99% or more at room temperature and 98% or more at 60 ° C., and is excellent in electro-optic characteristics, and the line diameter of the liquid crystal is not significantly reduced in physical and electro-optical properties. It can be seen that the blind spot can be adjusted.

According to the present invention, it is possible to provide a liquid crystal aligning material which is excellent in liquid crystal alignment property, easy to adjust the pretilt angle, and excellent in electro-optical properties such as voltage holding ratio.

Claims (8)

Diamine compound represented by following formula (1). [Formula 1] Wherein A is a hydrogen atom or a methyl group, B is -O-, -COO-, -CONH-, -OCO-, or a single bond, C is a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, an arylalkyl group or alkylaryl group having 7 to 30 carbon atoms, or a cholesterol group having 16 to 40 carbon atoms (cholesterol group), and the functional group may be substituted with a fluorinated alkyl group having 1 to 20 carbon atoms. A polyamic acid prepared by copolymerizing the functional diamine, aliphatic cyclic acid dianhydride and aromatic cyclic acid dianhydride of claim 1 with an aromatic cyclic diamine. The polyamic acid according to claim 2, wherein the content of the functional diamine in the total diamine monomers included in the polyamic acid is 0.1 to 100 mol%, and the content of the aromatic cyclic diamine is 0 to 99.9 mol%. According to claim 2, wherein the content of the aromatic cyclic acid dianhydride in the total acid dianhydride monomer contained in the polyamic acid is 10 to 80 mol%, the content of aliphatic cyclic acid dianhydride is 20 to 90 mol% Polyamic acid. The polyamic acid according to claim 2, wherein the polyamic acid is represented by the following Chemical Formula 6. [Formula 6] In the formula, X represents one or more selected from the functional groups represented by the following formula (7), Y represents one or more selected from the functional groups represented by the following formula (8), Z is selected from the functional groups represented by the following formula (9) At least one functional group or a functional group represented by the following general formula (10) is represented, wherein the proportion of the functional group represented by the general formula (10) in the total Z units is 0.1 to 100 mol%. [Formula 7] [Formula 8] [Formula 9] [Formula 10] Wherein A is a hydrogen atom or a methyl group, B is -O-, -COO-, -CONH-, -OCO-, or a single bond, C is a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, an arylalkyl group or alkylaryl group having 7 to 30 carbon atoms, or a cholesterol group having 16 to 40 carbon atoms, and the functional group includes a fluorinated alkyl group having 1 to 20 carbon atoms. Can be substituted. The polyamic acid according to claim 5, wherein the polyamic acid has an average molecular weight of 10,000 to 300,000 g / mol. The liquid crystal aligning film obtained by dissolving the polyamic acid of Claim 2 in a solvent, and coating it, and imidating it all or part. A liquid crystal display device comprising the liquid crystal alignment film of claim 7.