KR100555797B1 - Diamine containing Triazine group, Polyamic Acid synthesized from the Diamine, and LC Alignment Layer Prepared by the Polyamic acid - Google Patents

Abstract

The present invention relates to a diamine compound containing a triazine group, a polyamic acid and a liquid crystal alignment film prepared therefrom, and more particularly, a diamine compound containing a triazine group having a specific structure, a diamine containing the diamine compound, and an acid dianhydride. It relates to a polyamic acid and a liquid crystal alignment film obtained by imidating the polyamic acid. The liquid crystal alignment film prepared according to the present invention has high heat resistance, high transmittance in the visible light region, excellent alignment characteristics and high voltage holding ratio, and is easy to adjust the pretilt angle in a wide range.

Liquid crystal aligning film, polyamic acid polyimide, pretilt angle, voltage holding ratio, liquid crystal spreadability

Description

Diamine compound containing triazine group, polyamic acid and liquid crystal alignment film prepared therefrom {Diamine containing Triazine group, Polyamic Acid synthesized from the Diamine, and LC Alignment Layer Prepared by the Polyamic acid}

The present invention relates to a diamine compound containing a triazine group, a polyamic acid and a liquid crystal alignment film prepared therefrom, and more particularly, a diamine compound containing a triazine group having a specific structure, a diamine component (a) and an acid dianhydride component containing the diamine compound. The polyamic acid obtained by making (b) react, and the liquid crystal aligning film obtained by imidating the said polyamic acid. The liquid crystal alignment film prepared according to the present invention has high heat resistance, high transmittance in the visible light region, excellent alignment characteristics and high voltage holding ratio, and is easy to adjust the pretilt angle in a wide range.

Polyimide resins for liquid crystal alignment films according to the prior art include aromatic acid dianhydrides such as pyromellitic dianhydride (PMDA) and non-phthalic dianhydride (BPDA), paraphenylenediamine (p-PDA) and metaphenyl. Rendiamine (m-PDA), 4,4-methylenedianiline (MDA), 2,2-bisamino phenylhexafluoropropane (HFDA), metabisaminophenoxydiphenylsulfone (m-BAPS), parabisamino Manufacture by condensation of aromatic diamines such as phenoxydiphenylsulfone (p-BAPS), 4,4-bisaminophenoxyphenylpropane (BAPP), 4,4-bisaminophenoxyphenylhexafluoropropane (HF-BAPP) Doing.

As in the prior art, when only aromatic acid dianhydride and aromatic diamine are used, the thermal stability, chemical resistance, mechanical properties, etc. of the obtained polyimide liquid crystal alignment film are excellent, whereas the formation of the charge transfer complex (charge transfer complex) Its transparency and solubility are poor and its electro-optical properties are poor. In order to solve the above problem, Japanese Patent Laid-Open No. Hei 11-84391 discloses a polyimide (PI) -based liquid crystal aligning film in which an aliphatic cyclic acid dianhydride monomer or an aliphatic cyclic diamine is introduced, and Japanese Patent Laid-Open No. 06-136122 The PI type liquid crystal aligning film which improved the pretilt angle of a liquid crystal and improved stability using the functional diamine which has a side chain, the functional acid dianhydride which has a side chain, etc. is disclosed.

However, according to the researches of the present inventors, the PI-based alignment film according to the above technique uses a polyimide having an inadequate surface tension and polarity for the expression of a high pretilt angle, so that the spreadability of the liquid crystal during the liquid crystal injection is not good, so that the final alignment layer Defects occur, and the adjustable width of the pretilt angle is also not satisfactory.

Recently, as the liquid crystal display device market has grown, the demand for high quality display devices has been continuously increasing, and as the area of liquid crystal display devices has rapidly increased, the demand for high productivity alignment films has increased. There is an urgent need to develop an alignment film that can be easily adjusted in a wide range, has a low incidence rate when applied to an actual LCD production process, and has excellent electro-optical characteristics, high reliability, and excellent spreadability of liquid crystals. have.

The present inventors have studied to solve the above problems, and when using a novel diamine compound of a specific structure containing a triazine having a high polarity to obtain a polyamic acid, and imidized it to produce an alignment film, 1 ° It is possible to realize a pretilt angle of a desired value within the range of ˜90 °, and it is confirmed that the liquid crystal alignment film having excellent liquid crystal alignment characteristics and electro-optic properties, and excellent printability and liquid crystal spreadability can be produced and leads to the present invention. It became.

As a result, the present invention is to provide a liquid crystal alignment layer having a novel triazine-based diamine compound having a specific structure, excellent printing characteristics, liquid crystal spreadability, high pretilt angle and very low incidence in actual process.

One aspect of the present invention for this purpose relates to a diamine compound comprising a triazine group, represented by the following formula (1):                     

 Wherein X, Y and Z are direct bonds, -O-, -COO-, -CONH-, or -OCO-, n is an integer from 0 to 12, A is a linear, branched carbon of 1 to 10 Or a substituent represented by one or more groups selected from the group consisting of divalent organic groups having a form or a complex form thereof, or represented by the formula (2).)

Another aspect of the present invention relates to a polyamic acid prepared by reacting a diamine (a) and an acid dianhydride (b) containing the diamine compound of Formula 1 in an amount of at least 0.1 mol% based on 100 mol% of the total diamine mixture. will be.

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

Hereinafter, the present invention will be described in more detail.

In the diamine compound including the triazine group according to the formula (1), wherein A is a divalent organic group having a linear, branched form or a complex form of 1 to 10 carbon atoms, preferably a group represented by the following formula (2) It is a diamine compound characterized by the above-mentioned.

      According to the researches of the present inventors, by using a diamine compound having a specific structure containing a triazine group as a diamine component in the production of polyamic acid, the adjustable width of the pretilt angle of the final polyimide is widened and its adjustment is easy, and excellent orientation is achieved. Indicates.

The content in the diamine component (a) of the functional diamine compound of Formula 1 is 0.1 to 100 mol%, preferably 2 to 60 mol%, more preferably 2 to 30 mol% with respect to 100 mol% of the total diamine component. Occupy.

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 used is 0 to 99.9 mol%, preferably 40 to 98 mol%, more preferably 70 to 98 mol% relative to the total diamine content.                     

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), 2,3,5-tricarboxy cyclopentyl acetic Acid dianhydride (TCA-AH) and the like, but is not limited thereto.

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

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.

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), benzophenonetetracarboxylic dianhydride (BTDA), hexafluoroisopropylidene diene 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 polyamic acid of the present invention more preferably has a structure represented by the following formula (3).

In Formula 3, X represents at least one selected from the functional groups represented by Formula 4, Y represents at least one selected from the functional groups represented by Formula 5, and Z is represented by the following Formula 6 and the following Formula 7. At least one functional group selected from among the functional groups, Z 'is a functional group represented by the formula (8) derived from the diamine compound of the formula (1).

Wherein X1, X2, X3 and X4 are each -CH3, -F, -H single or a mixture thereof.
[Formula 6]

delete

[Formula 7]

상기 식에서, X, Y 및 Z는 직접결합, -O-, -COO-, -CONH-, 또는 -OCO-이며, n은 0에서 12의 정수이고, A는 탄소수 1내지 10의 선형, 가지형 또는 이들의 복합적 형태를 갖는 2가의 유기기로 이루어진 군으로부터 선택된 1 이상의 기로 치환기이거나, 또는 화학식 2로 표현되는 기이다.Wherein n is an integer from 1 to 10.
[Formula 8]

Wherein X, Y and Z are direct bonds, -O-, -COO-, -CONH-, or -OCO-, n is an integer from 0 to 12, and A is a linear, branched form of 1 to 10 carbon atoms Or a substituent represented by one or more groups selected from the group consisting of divalent organic groups having a complex form thereof, or a group represented by the formula (2).

Polyamic acid according to the present invention is a commonly used N-methyl-2-pyrrolidone (NMP), gamma-butyrolactone (GBL) dimethylformamide (DMF), dimethylacetamide (DMAc), tetrahydrofuran ( Very good solubility in aprotic polar solvents such as THF). This excellent solubility is thought to be due to the introduction of aliphatic cyclic acid dianhydrides, the alkyl portion in the main chain, and the joint role of the side chain portion to increase the free volume of the polymer. In recent years, the printability of the alignment agent is very important due to the large size, high resolution, and high quality of the liquid crystal display device. Thus, the excellent solubility in the solvent 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 500,000 g / mol, and when the imidation proceeds, the glass transition temperature has a range of 200 to 350 ° C. depending on the imidation ratio or structure.

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 the light transmittance, is excellent in the orientation of the liquid crystal, and can be easily adjusted within the range of 1 to 90 °. In addition, since the functional diamine is included, the refractive index of the polymer may be lowered and the dielectric constant may also be lowered.

Hereinafter, the structure and effect of the present invention will be described in more detail with specific examples and comparative examples, but these examples are only intended to more clearly understand the present invention, and are not intended to limit the scope of the present invention.                     

Preparation Example 1 Preparation of [4- (3,5-dimethoxy-2,4,6-triazinyl) -dicyclohexanol

1 mol of 2-chloro-4,6-dimethoxy-1,3,5-triazine was dissolved in THF at 15% by weight, and then 1 mol of triethylamine (TEA) was added thereto, and the temperature was-. Lowered to 5 ° C. After slowly adding an excess of 2.5 mol of bicyclohexanediol to the solution, the reaction was maintained for 8 hours while maintaining at -5 ° C. After the reaction was completed, the reaction mixture was placed in a 1N NaOH aqueous solution and stirred vigorously, the resulting white solid was filtered and washed several times with distilled water, and then by-products were removed by using column chromatography.

Preparation Example 2 Preparation of 4- [4- (3,5-dimethoxy-2,4,6-triazinyl) -dicyclohexanoxy] -1,3-diamino benzene

1 mol of the reactant in Preparation Example 1 was dissolved in chloroform at 15% by weight, and triethylamine (TEA) was added as much as 1.1 mol. 1 mol of 4-chloro-1,3-diamino benzene was added thereto, stirred, and heated to 60 ° C., followed by reaction under reflux for 6 hours while maintaining a temperature of 60 ° C. After completion of the reaction, the mixture was extracted with aqueous NaOH solution and the aqueous solution was removed, washed again with ultrapure water, and the aqueous solution was removed using a separatory funnel, dried over magnesium sulfate and filtered. It was. Thereafter, the chloroform was distilled off using vacuum distillation to obtain a light white product, and ethanol was recrystallized to obtain a white high purity diamine.                     

Example 1

While passing nitrogen through a four-necked flask equipped with a stirrer, a thermostat, a nitrogen gas injector, and a cooler, 0.95 mol of 4-, 4-methylenedianiline and 4- [4- (3,5-dimethoxy-2,4, 0.05 mol of 6-triazinyl) -dicyclohexanoxy] -1,3-diamino benzene was added, and N-methyl-2-pyrrolidone (NMP) was added and dissolved. 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. Then, the surface of the alignment film was rubbed using a rubbing machine, and the two substrates were rubbed in parallel to each other in the opposite direction, and then 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, 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, and the cell rubbing direction was twisted at 90 ° to be bonded, and then the cell gap was uniformed to 5 μm. The test cell was prepared by maintaining the same, and the voltage holding ratio thereof was measured and shown in Table 1 below.

Example 2

4- [4- (3,5-dimethoxy-2,4,6-triazinyl) -dicyclohexanoxy] -1,3-diamino benzene using 0.9 mol of 4,4-methylenedianiline A polyamic acid solution (PAA-2) was obtained in the same manner as in Example 1 except that 0.1 mol was used. 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

0.5 mol of cyclobutane dianhydride (CBDA) was used instead of 0.5 mol of 5- (2,5-dioxotetrahydrofuryl) -3-methylcyclohexane-1,2-dicarboxylic acid anhydride (DOCDA) Except for the same as in Example 1 except for obtaining 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

0.5 mol of cyclobutane dianhydride (CBDA) was used instead of 0.5 mol of 5- (2,5-dioxotetrahydrofuryl) -3-methylcyclohexane-1,2-dicarboxylic acid anhydride (DOCDA) Except for the same as in Example 2 except for obtaining a polyamic acid (PAA-4). 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

2,4-diamino-1-hexadecyloxy instead of 4- [4- (3,5-dimethoxy-2,4,6-triazinyl) -dicyclohexanoxy] -1,3-diamino benzene Except for using benzene it was carried out in the same manner as in Example 2 to obtain a polyamic acid (PAA-5). In addition, the orientation, pretilt angle and voltage holding ratio of the liquid crystal were measured in the same manner as in Example 2, and the results are shown in Table 1 below.

Comparative Example 2

4- [4- (3,5-dimethoxy-2,4,6-triazinyl) -dicyclohexanoxy] -1,3-diamino benzene instead of 2,2-bis ([4- (4- Aminophenoxy) phenyl] hexafluoropropane was used in the same manner as in Example 2 to obtain a polyamic acid (PAA-6), and the alignment of liquid crystals in the same manner as in Example 2. , The pretilt angle and the voltage holding ratio were measured and shown in Table 1 below.                     

sample Printability Orientation Voltage retention rate (%) Pretilt Liquid crystal spreadability Room temperature 60 ℃ Example 1 Good Good 99.5 98.3 3.4 Good Example 2 Good Good 99.2 97.8 4.6 Good Example 3 Good Good 99.3 97.9 3.2 Good Example 4 Good Good 99.1 97.0 4.3 Good Comparative Example 1 Good Good 98.8 93.7 6.9 Bad Comparative Example 2 Good Good 96.3 85.2 1.5 Good

As shown in Table 1, the liquid crystal alignment layer of the present invention has a voltage preservation ratio of 99% or more at room temperature and 97% or more at 60 ° C, and is excellent in electro-optic properties, and the diameter of the liquid crystal without significant deterioration of physical and electro-optic properties. It can be seen that the blind spot can be adjusted.

According to this invention, the liquid crystal aligning agent which is excellent in liquid crystal orientation property, the adjustment of a pretilt angle is easy, and is excellent in electro-optical characteristics, such as a voltage holding ratio, can be provided.

Claims (11)

delete delete A diamine component (a) comprising the diamine compound of formula (1) in an amount of at least 0.1 mol% with respect to 100 mol% of the total diamine mixture and an acid dianhydride component (b) are prepared. Polyamic acid characterized in that the average molecular weight is 10,000 ~ 300,000g / mol: [Formula 1]

 Wherein X, Y, Z are direct bonds, -O- or -COO-, -CONH-, or -OCO-, n is an integer from 0 to 12, and A is linear, branched from 1 to 10 carbon atoms At least one group selected from the group consisting of divalent organic groups having a form or a complex form thereof, or a group represented by the formula (2). [Formula 2]

[Formula 3]

In the formula, X represents one or more selected from the functional groups represented by the following formula (4), Y represents one or more selected from the functional groups represented by the following formula (5), Z is represented by the following formula (6) At least one functional group selected from the functional groups, and Z 'is a functional group represented by Formula 8 derived from the diamine compound of Formula 1. [Formula 4]

[Formula 5]

Wherein X1, X2, X3 and X4 are each -CH3, -F, -H single or a mixture thereof. [Formula 6]

[Formula 7]

  Wherein n is an integer from 1 to 10. [Formula 8]

 Wherein X, Y and Z are direct bonds, -O-, -COO-, -CONH-, or -OCO-, n is an integer from 0 to 12, and A is a linear, branched form of 1 to 10 carbon atoms Or a substituent represented by one or more groups selected from the group consisting of divalent organic groups having a complex form thereof, or a group represented by the formula (2). The polyamic acid according to claim 3, wherein the content of the functional diamine is 0.1 to 100 mol%, and the content of the aromatic cyclic diamine is 0 to 99.9 mol% based on the total diamine monomers contained in the polyamic acid.        The method of claim 3, wherein the aromatic cyclic diamine is paraphenylenediamine (p-PDA), 4,4-methylenedianiline (MDA), 4,4-oxydianiline (ODA), metabisaminophenoxydi. Phenyl sulfone (m-BAPS), parabisaminophenoxydiphenylsulfone (p-BAPS), 2,2-bisaminophenoxyphenylpropane (BAPP) and 2,2-bisaminophenoxyphenylhexafluoropropane (HF -BAPP) polyamic acid, characterized in that selected from the crowd consisting of.        The aliphatic cyclic acid dianhydride according to claim 3, wherein the aliphatic cyclic acid dianhydride is 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 Crowd consisting of acid dianhydride (CPDA), 1,2,4,5-cyclohexanetetracarboxylic dianhydride (CHDA), 2,3,5-tricarboxy cyclopentylacetic acid dianhydride (TCA-AH) Polyamic acid, characterized in that selected from.        4. The aromatic cyclic acid dianhydride according to claim 3, wherein the aromatic cyclic acid dianhydride is pyromellitic dianhydride (PMDA), nonphthalic dianhydride (BPDA), oxydiphthalic dianhydride (ODPA), benzophenonetetracarboxylic dianhydride (BTDA), Polyamic acid, characterized in that selected from the group consisting of hexafluoroisopropylidenediphthalic dianhydride (6-FDA).  According to claim 3, wherein the content of the aromatic cyclic acid dianhydride in the total acid dianhydride monomer included in the polyamic acid is 10 to 80 mol%, the content of aliphatic cyclic acid dianhydride is 20 to 90 mol% Polyamic acid. delete A liquid crystal aligning film obtained by dissolving and coating a polyamic acid according to claim 3 in a solvent, and imidating it in whole or in part. A liquid crystal display device comprising the liquid crystal alignment film according to claim 10.