JP2001294663A - Polyamic acid, polyamic acid solution, and liquid crystal display device using the polyamic acid solution - Google Patents

Abstract

(57) [Summary] (Modified) [PROBLEMS] A liquid crystal display element having a pretilt angle of 2 to 3 degrees for preventing a reverse domain in a liquid crystal display element, having excellent electric characteristics, and generating no unevenness in washing. To get A polyamic acid containing tetracarboxylic dianhydride and a diamine as main raw materials, wherein the polyamic acid uses a compound of the formula (1) as a diamine as a raw material In the formula, R1 is hydrogen or CH3, three R1s may be the same or different, a, b, and c are 1 or 2, and n is an integer of 0 to 2. Further, the liquid crystal display element formed using a solution containing the liquid crystal material and a liquid crystal material has a pretilt angle of 2 to 3 degrees and can prevent the occurrence of unevenness in washing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a polyamic acid and a polyamic acid solution having excellent electrical properties and reliability used in the field of electronic materials. As an application thereof, it can be used as an alignment film, a protective film, an insulating film and the like. In particular, it is most suitable as an alignment agent for liquid crystal display elements.

[0002]

[Problems to be solved by the invention]

2. Description of the Related Art At present, a display element using a nematic liquid crystal is mainly used, and a TN type liquid crystal element twisted by 90 °, an STN type liquid crystal element usually twisted by 180 ° or more, and a TFT type liquid crystal using a thin film transistor are used. Device, and more recently, a lateral electric field type I with improved viewing angle characteristics.
Liquid crystal display devices using various driving methods such as a PS (In-Plane Switching) type liquid crystal device have been put to practical use. The development of liquid crystal display devices is not only simply progressing in these systems, but also the improvements in peripheral materials are being actively made to improve the characteristics of liquid crystal display devices.

As the liquid crystal display device is used in various fields, the characteristics required for the liquid crystal display device are becoming higher in performance. Among these performances, there are requirements for the orientation of the liquid crystal represented by the pretilt angle of the liquid crystal, requirements for the electric characteristics of the liquid crystal element such as current consumption value, voltage holding ratio, residual charge, and various characteristics. Of the liquid crystal display element for long-term use, and further, a demand for display quality such as an afterimage phenomenon of a liquid crystal display element and display unevenness. Among these characteristics, the pretilt angle of the liquid crystal differs depending on the driving method of the liquid crystal element. For example,
A pre-tilt angle of about 1 to 6 degrees is required for a TN type liquid crystal display element or a TFT type liquid crystal display element in which the liquid crystal is twisted 90 degrees, and a pretilt angle of about 3 to 8 degrees is required for an STN type liquid crystal display element having a large twist angle. Is done.

However, the required pretilt angle varies slightly depending on the use of the element.
Recently, the STN-type liquid crystal display device may be required to have an angle of 2 to 3 degrees or 8 degrees or more. Also,
Not only the pretilt angle, but also the properties related to the orientation of the liquid crystal, such as the uniformity of the orientation, the orientation stability, and the anchoring energy at the interface between the liquid crystal and the orientation film, are important factors because they greatly affect the performance of the liquid crystal element. Further, the process margin of these characteristics in the manufacturing process of the liquid crystal display element is also important. Depending on the conditions for drying the solvent after the application of the alignment agent, the conditions for imidizing the polyamic acid (usually imidized by performing heat treatment), or the conditions for annealing after injecting the liquid crystal into the element, If the pretilt angle or the orientation of the liquid crystal changes, there is a big problem.

[0005] With respect to STN-type liquid crystal display devices, particularly those of low voltage type used in the field of portable equipment, the driving voltage of the liquid crystal display device is low, so that the demand for current consumption is important. That is, when the current consumption of the liquid crystal element increases, the voltage applied to the liquid crystal relatively decreases, and therefore the rise of the liquid crystal molecules becomes insufficient and the contrast is lowered. Further, in a low-voltage type liquid crystal display device, a change (reliability) in a current consumption value occurring during long-term use of the liquid crystal display device is also important. In the STN-type display element, the display is turned on and off with a slight potential difference. Therefore, if the current consumption value of the element changes, the voltage applied to the liquid crystal also changes, and normal driving cannot be performed. In an extreme case, even a phenomenon in which an image on the liquid crystal display element is not displayed at all may occur due to long-time driving. Further, in recent years, a liquid crystal having a large dielectric anisotropy has been used with a decrease in the liquid crystal driving voltage, and this has caused a small threshold voltage unevenness (Vth unevenness) generated in a display surface. It has come to be seen as a problem. In particular, when water washing is performed to remove shavings generated when the alignment film is rubbed, traces of the water washing become Vt.
A phenomenon that remains as h unevenness (water washing unevenness) occurs, which is a major problem.

On the other hand, regarding a TFT type liquid crystal display element,
Particularly, the requirements for the voltage holding ratio and the residual charge are important.
If the voltage holding ratio is low, the voltage applied to the liquid crystal during the frame period decreases, and a problem occurs in that the contrast decreases. If the residual charge is large, turn off the voltage after applying the voltage.
However, the charge remains, and the image to be erased remains as an afterimage. In a TFT type liquid crystal display device, this afterimage phenomenon is one of quite important problems.

An object of the present invention is to solve, among the characteristics required for the above-described liquid crystal display device, particularly a request for an STN type liquid crystal display device. That is, an object of the present invention is to provide a liquid crystal aligning agent for obtaining a liquid crystal display element having a pretilt angle of 2 to 3 degrees in a method of measuring a pretilt angle described in Examples described later. Furthermore, the present invention provides a liquid crystal aligning agent for obtaining a liquid crystal display element having a small current consumption value, high reliability of a pretilt angle and a current consumption value for a long period of time, and free of uneven washing even when washed with water. That is the task. Looking at the prior art, for example, Japanese Patent Application Laid-Open No. 08-169954 discloses a liquid crystal aligning agent that provides a high-quality liquid crystal display device, a specific tetracarboxylic dianhydride and a tetracarboxylic dianhydride containing a cyclobutane ring. And an aligning agent containing a polyamic acid obtained from a diamine component.

However, the publication does not mention the pretilt angle of the liquid crystal, and is particularly an object of the present invention which is obtained with an aligning agent as shown in Examples of the present invention.
It was difficult to achieve an appropriate pretilt angle of 3 degrees. In addition, as described in the description of the diamine component having an ether group, a thioether group, an SO2 group, and the like, the diamine component which can be used as the component of the polyamic acid having excellent electric properties particularly specified in the present invention is a composition. The content was different, and the electrical characteristics of the obtained device were also inferior. Further, when a liquid crystal display element is manufactured by using the alignment agent disclosed in this publication, Vt is washed by water after the rubbing treatment.
A problem such as h unevenness occurs, and particularly when a liquid crystal having a large dielectric constant is used, traces of water washing are clearly left. That is, according to the method described in the above publication, it was difficult to obtain a material having an appropriate pretilt angle, electrical characteristics and the reliability of those characteristics at the same time, and having no unevenness in washing. In addition, WO98 / 3172
As disclosed in PCT Publication No. 5, the present inventors have found that by using a specific diamine compound, stain-like display unevenness that occurs after the alignment film is washed with water is less likely to occur. However, the application did not mention a suitable pretilt angle (2 to 3 degrees), electrical characteristics, and means for obtaining reliability of those characteristics.

[0009]

As means for solving the above problems, as a result of intensive studies on the structure of tetracarboxylic acid and diamine used for polyamic acid, a liquid crystal aligning agent used for a liquid crystal display device was obtained. It has been found that this can be achieved by using an aligning agent containing a polyamic acid obtained from a specific diamine component and tetracarboxylic dianhydride described below. That is, the first of the present invention is a polyamic acid obtained using tetracarboxylic dianhydride and a diamine as main raw materials, and using a compound represented by the formula (1) as a diamine as a raw material.

[0010]

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Wherein R 1 is hydrogen or CH 3,
R1 may be the same or different, a, b and c are 1 or 2, and n is an integer of 0 to 2. The second of the present invention is a polyamic acid solution containing the above polyamic acid, and the third of the present invention is a liquid crystal display device using the polyamic acid solution of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION In a preferred embodiment of the present invention, at least one selected from the group consisting of alicyclic tetracarboxylic dianhydride and aliphatic tetracarboxylic dianhydride is used as the tetracarboxylic dihydrate. It is a polyamic acid obtained by reacting with a diamine. A more preferred embodiment of the present invention is the above-mentioned polyamic acid using, as raw materials, a compound represented by the above formula (1) and a compound represented by the following formula (2) as a diamine.

[0012]

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In the formula (2), l and m are 1 or 2
It is. Further, the content of the polyamic acid in the polyamic acid solution of the present invention is 0.1 to 40% by weight, and more preferably 0.5 to 10% by weight. The diamine compound used in the present invention has a benzene ring having a linking group -CH2C
It is a substance having a skeleton linked by H2-. Although the reason is not clear, a diamine component having this structure can be particularly preferably used in order to obtain a pretilt angle of 2 to 3 degrees which is the object of the present invention. For example, as in the examples of the present invention, the linking group of the benzene ring is -CH2
When the main component is a diamine having a skeleton of-or -CH2CH2CH2-, the pretilt angle is undesirably too low as 1 to 2 degrees. In the present invention, those having a skeleton having a methyl group at the lateral position of the benzene ring and those having a hydrogen atom can be used. In this case, those having a skeleton having a methyl group tend to have a lower pretilt angle, but can be preferably used in view of display quality such as uneven washing.

When the diamine compound represented by the formula (1) is used as a liquid crystal alignment film, other diamine components, for example, diamine compounds having polar groups such as O, CO, C (CF3) 2, and COO groups Is a preferable component in terms of electric characteristics of a liquid crystal display element obtained as compared with a product containing as a main component.
Therefore, it is a main component of the diamine component of the alignment agent, which is the main use of the present invention, and is preferably used particularly in terms of electrical characteristics. Specific examples of these compounds include 4,4′-diamino-1,2-diphenylethane, 1,2-bis- (4-amino-2-methylphenyl) ethane, and 1,2-bis- (4 -Amino-3-methylphenyl) ethane, 1,2-bis- (4-amino-3,
5-dimethylphenyl) ethane, 1,4-bis [2-
(4-aminophenyl) ethyl] benzene, 1,4-bis [2- (4-amino-3-methylphenyl) ethyl]
Benzene, 1,2-bis [4- (2- (4-aminophenyl) ethyl) phenyl] ethane and the like can be mentioned.

Further, as the diamine component of the polyamic acid which can be preferably used in the present invention, the aromatic diamine represented by the formula (2) has a structure having a methyl group at the lateral position of the benzene ring of 4,4′-diaminodiphenylmethane. Since the compound is a compound and the linking group of the benzene ring is CH2, the pretilt angle is as low as about 1 degree, but it can be preferably used particularly from the viewpoint of display quality such as unevenness in washing.

Although the cause of the unevenness in the washing is not clear, it is considered that the water absorbed during the washing slightly remains in the liquid crystal alignment film, and Vth unevenness is caused by the influence of the influence of the washing. Since the diamine component represented by the formula (2) has a methyl group at the lateral position of the benzene ring, it is considered that the water absorption of a liquid crystal alignment film is reduced. For this type of diamine compound, O, CO, C (CF
3) The diamine component of the formula (1) or (2) is more preferably used in terms of electrical characteristics than the diamine component having a polar group such as 2, COO group. Specific examples of these compounds include 1,2-bis- (4-amino-2-methylphenyl) methane and 1,2-bis- (4-
Amino-3-methylphenyl) methane, 1,2-bis-
(4-amino-3,5-dimethylphenyl) methane and the like.

In the diamine compound used for the polyamic acid, the ratio of the diamine compound of the formula (1) to the diamine compound of the formula (2) depends on the required pretilt angle, but is usually from 95/5 to 50/50. It is. When the proportion of the diamine compound of the formula (1) is less than 50%,
The pretilt angle becomes too low, and the required 2
A pretilt angle of 3 degrees cannot be obtained. On the other hand, equation (1)
When the ratio of the diamine exceeds 95%, unevenness in washing with water becomes conspicuous, which is not preferable.

In the present invention, specific examples of the alicyclic tetracarboxylic dianhydride that can be preferably used include cyclobutanetetracarboxylic dianhydride, cyclopentanetetracarboxylic dianhydride and bicyclo [2.2.2]. -Oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, cyclohexane-1,2,5,6-tetracarboxylic dianhydride, 3,3′-bicyclohexyl-1,
1 ′, 2,2′-tetracarboxylic dianhydride, 2,3
5-tricarboxycyclopentylacetic acid dianhydride, 5-
(2,5-dioxotetrahydrofural) -3-methyl-3-cyclohexene-1,2-dicarboxylic dianhydride, 1,3,3a, 4,5,9b-hexahydro-5-
Tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2, -c] -furan-1,3-dione, 3,
5,6-Tricarboxynorbornane-2-acetic acid dianhydride, 2,3,4,5-tetrahydrofurantetracarboxylic dianhydride, or an alicyclic group obtained by partially substituting a lower alkyl such as a methyl or ethyl group with them Examples thereof include tetracarboxylic dianhydride. Of these, tetracarboxylic dianhydrides such as cyclobutanetetracarboxylic dianhydride, cyclopentanetetracarboxylic dianhydride, tricarboxycyclopentylacetic dianhydride, and cyclohexanetetracarboxylic dianhydride are particularly preferably used. .

In the present invention, the aliphatic tetracarboxylic dianhydride which can be preferably used includes ethylene tetracarboxylic dianhydride, butane tetracarboxylic dianhydride, pentane tetracarboxylic dianhydride, hexane tetracarboxylic dianhydride. Anhydride and heptanetetracarboxylic dianhydride can be mentioned. These alicyclic and aliphatic tetracarboxylic dianhydrides are particularly preferably used from the viewpoint of the electrical characteristics of a liquid crystal device produced using the obtained polyamic acid solution. In the tetracarboxylic dianhydride used for the polyamic acid, the ratio between the aliphatic tetracarboxylic dianhydride and the alicyclic tetracarboxylic dianhydride differs depending on the required pretilt angle, but is usually an aliphatic type. The ratio of the alicyclic system is 90/10 to 30/70, preferably 70/30 to 30/70. When the proportion of the aliphatic tetracarboxylic dianhydride increases, the pretilt angle tends to decrease, and the required pretilt angle of 2 to 3 degrees cannot be obtained.

As long as the effects of the present invention are not impaired, an acid component such as an aromatic tetracarboxylic dianhydride may be used in combination with the alicyclic or aliphatic tetracarboxylic dianhydride described above. Can be. Specifically, pyromellitic dianhydride is preferably used as the aromatic tetracarboxylic dianhydride that can be used. However, other than pyromellitic dianhydride, 3,3 ′, 4,4′-diphenyltetracarboxylic acid may be used. Acid dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, naphthalene dianhydride (2,3,6,7-naphthalene anhydride and the like), 3,
3 ′, 4,4′-biphenylsulfonetetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenylethertetracarboxylic dianhydride, 3,3 ′, 4,4′-dimethyldiphenyl Silanetetracarboxylic dianhydride, 4,
4′-bis (3,4-dicarboxyphenoxy) diphenyl sulfide dianhydride, 4,4′-bis (3,4-dicarboxyphenoxy) diphenyl sulfone dianhydride,
4,4'-bis (3,4-dicarboxyphenoxy) diphenylpropane dianhydride, 3,3 ', 4,4'-par
Fluoropyridene diphthalic dianhydride, 3,3 ′, 4
4'-biphenyltetracarboxylic dianhydride, bis (phthalic acid) phenylsulfin oxide dianhydride, p-
Phenylene-bis (triphenylphthalic acid) dianhydride,
m-phenylene-bis (triphenylphthalic acid) dianhydride, bis (triphenylphthalic acid) -4,4'-diphenylether dianhydride, bis (triphenylphthalic acid)
And aromatic tetracarboxylic dianhydrides such as -4,4'-diphenylmethane dianhydride.

Of these, those containing oxygen, sulfur, etc. are not preferred because of their poor electrical properties. These aromatic tetracarboxylic dianhydrides have some drawbacks in the electrical characteristics of the liquid crystal device obtained by using the obtained polyamic acid solution as an aligning agent, particularly because the current consumption value and its reliability tend to deteriorate. It is. In this respect, since an element using an alignment agent using an alicyclic or aliphatic tetracarboxylic dianhydride can obtain good electric characteristics, it is a necessary component for realizing the object of the present invention. . On the other hand, with respect to the orientation of the liquid crystal molecules, it is more preferable to use an aromatic tetracarboxylic dianhydride. It can be said that it is preferable to use tetracarboxylic dianhydride in combination.

Further, in addition to these tetracarboxylic acids and diamines, it is also possible to use a monoamine compound and / or a monocarboxylic anhydride which forms a reactive end of polyamic acid. To improve the adhesion to the substrate, an aminosilicon compound or a diaminosilicon compound may be introduced. As aminosilicon compounds, para-aminophenyltrimethoxysilane,
Examples include paraaminophenyltriethoxysilane, metaaminophenyltrimethoxysilane, metaaminophenyltriethoxysilane, aminopropyltrimethoxysilane, and aminopropyltriethoxysilane. Further, as the diaminosilicon compound, 1,3-bis (3-aminopropyl) -1,1,3,3-tetraphenylsiloxane, 1,3-bis (3-aminopropyl)
-1,1,3,3-tetramethyldisiloxane, 1,3
And bis- (4-aminobutyl) -1,1,3,3-tetramethyldisiloxane.

The concentration of the polyamic acid in the polyamic acid solution used as the liquid crystal aligning agent is 0.1 to 40% by weight, and the optimum concentration when using it is to coat the aligning agent on the substrate. Since the method differs depending on the method, the range cannot be definitely determined. In a spinner method, a printing method, and the like which are usually performed, a concentration of about 0.5 to 10% is preferably used. If the polyamic acid concentration is 0.5% or less, the film thickness as an alignment film may be too thin, and if it is 10% or more, the film thickness may be too thick. Further, in the case of a solution having a polyamic acid concentration of 40% or more, the viscosity of the stock solution is too high when the solution is diluted for film thickness adjustment at the stage of use,
In many cases, adverse effects such as inadequate mixing of solvents appear, which are not preferable. As long as the effects of the present invention are not impaired,
As the polyamic acid of the present invention, a polyamic acid ester, a soluble polyimide, a polyamideimide or the like can be used in the form of a polymer. The liquid crystal aligning agent that can be used in the present invention is imidized by heat treatment after being applied to the substrate (it is not necessarily 100% imidized, but the imidation rate after heating is 40% or more). Is preferred). Therefore, it goes without saying that the same effect can be expected even when a soluble polyimide is used in place of the polyamic acid of the present invention.

As a solvent used for the liquid crystal aligning agent, a solvent usually used for polyamic acid or soluble polyimide can be used. That is, N-methyl-2-pyrrolidone, dimethylimidazolidinone, N-methylcaprolactam, N-methylpropionamide, N, N-dimethyl, which are aprotic polar organic solvents which are lipophilic solvents for polyamic acid Acetamide, dimethylsulfoxide, N, N-dimethylformamide, N, N
N-diethylformamide, diethylacetamide, γ-butyllactone and the like can be used. Along with these solvents, other solvents having a low surface tension, such as alkyl lactate, 3-methyl-3-
Methoxybutanol, tetralin, isophorone, ethylene glycol monoalkyl ether (such as ethylene glycol monobutyl ether), diethylene glycol monoalkyl ether (such as diethylene glycol monoethyl ether), ethylene glycol monoalkyl acetate or ethylene glycol monophenyl acetate,
Examples thereof include triethylene glycol monoalkyl ether, propylene glycol monoalkyl ether (propylene glycol monobutyl ether, etc.), dialkyl malonate (diethyl malonate, etc.). Many of these solvents are poor solvents with respect to the above-mentioned parent solvent.

As a method of applying the alignment agent dissolved in these solvents to a substrate on which a liquid crystal alignment element is formed, a commonly used method can be used. For example, spinner
It is possible to apply by a method, a printing method, a dipping method, a dropping method or the like. In addition, the heat treatment required for drying and dehydration / ring-closure reaction of the solvent after applying these alignment agents can be carried out in the same manner as the method usually using polyamic acid. For example, heat treatment can be performed in an oven, hot plate, infrared furnace, or the like. After the application of the alignment agent, it is preferable to evaporate the solvent at a relatively low temperature and then perform a heat treatment at a temperature of about 150 to 300 ° C. In the aligning agent of the present invention, it is also possible to add a catalyst for the purpose of promoting imidization and the like, and further, for the purpose of surfactants and antistatic purposes used for the purpose of improving coating properties and the like. It is also possible to add antistatic agents to be used. Alternatively, a silane coupling agent and a titanium-based coupling agent can be further blended to improve the adhesion to the substrate.
Although the present invention has been invented as an aligning agent particularly preferably used for a low voltage type STN type liquid crystal element, since an aligning agent having an appropriate pretilt can be obtained, a TN type or a TFT type other element is used. Needless to say, it can also be used for applications.

The liquid crystal composition which can be preferably used in a liquid crystal display device using the alignment agent of the present invention is as follows:
(A), (c), (d), (e), (f) and (g)
It is as described in. (A) A compound containing at least one compound selected from the group of compounds represented by the following general formulas (5), (6) and (7).

[0027]

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In these formulas, R2 has 1 to 1 carbon atoms.
0 represents an alkyl group, and any non-adjacent methylene group in the group may be substituted by -O- or -CH = CH-, and any hydrogen atom in the alkyl group is a fluorine atom. R3 may be a fluorine atom, a chlorine atom, -OCF3, -OCF2H, -CF3, -CF2
H, -CFH2, -OCF2CF2H or -OCF2
L1 and L2 each independently represent a hydrogen atom or a fluorine atom; Z1 and Z2 each independently represent 1,2-ethylene, 1,4-butylene,
-COO-, -CF2O-, -OCF2-, -CH = C
H- or a single bond; ring B is trans-1,4-cyclohexylene, 1,3-dioxane-2,5-diyl or 1,4-phenylene in which a hydrogen atom may be substituted by a fluorine atom; Ring C is trans-1,4-
Cyclohexylene or 1,4-phenylene in which a hydrogen atom may be replaced by a fluorine atom.

Specific examples of these compounds will be given below, but all compounds corresponding to the formulas (5), (6) and (7) cannot be mentioned. Therefore, any compounds not listed here may be used as long as they correspond to the formulas (5), (6) and (7).

[0030]

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[0031]

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[0032]

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[0033]

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[0034]

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[0035]

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(A) A liquid crystal composition containing at least one compound selected from the group consisting of the following general formulas (8) and (9):

[0037]

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In these formulas, R4 and R6 each independently represent an alkyl group having 1 to 10 carbon atoms, and any non-adjacent methylene group in the group is -O- or -C
R ＝ may be substituted with H ＝ CH—, and any hydrogen atom in the alkyl group may be substituted with a fluorine atom; R5 represents a —CN group or —C≡C—CN;
Represents trans-1,4-cyclohexylene, 1,4-phenylene, 1,3-dioxane-2,5-diyl or pyrimidine-2,5-diyl; ring E is trans-
1,4-cyclohexylene, 1,4-phenylene in which a hydrogen atom may be replaced by a fluorine atom, or pyrimidine-2,5-diyl; ring F is trans-1,4
-Cyclohexylene or 1,4-phenylene;
Z3 represents 1,2-ethylene, -COO- or a single bond; L3, L4 and L5 each independently represent a hydrogen atom or a fluorine atom; e, f and g each independently represent 0 or 1 . Specific examples of these compounds will be given below.

[0039]

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[0040]

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[0041]

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[0042]

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[0043]

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[0044]

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[0045]

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[0046]

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(C) A liquid crystal composition containing at least one compound selected from the group consisting of the following general formulas (10), (11) and (12).

[0048]

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In these formulas, R7 and R8 each independently represent an alkyl group having 1 to 10 carbon atoms, in which any non-adjacent methylene group is substituted by -O- or -CH = CH-. And any hydrogen atom in this group may be replaced by a fluorine atom;
Ring G and Ring I are each independently trans-1,4
-Cyclohexylene or 1,4-phenylene;
L6 and L7 each independently represent a hydrogen atom or a fluorine atom, but do not represent a hydrogen atom at the same time;
And Z5 are each independently 1,2-ethylene, -C
OO- or a single bond is shown. Specific examples of these compounds will be given below.

[0050]

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(D) The first component contains at least one compound selected from the compound group consisting of the general formulas (5), (6) and (7), and the second component has the following general formula (13) ), A liquid crystal composition containing at least one compound selected from the compound group consisting of (14) and (15).

[0052]

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In these formulas, R9 and R10 each independently represent an alkyl group having 1 to 10 carbon atoms;
Any non-adjacent methylene group in the group is -O- or-
CH = CH-, and any hydrogen atom in the alkyl group may be substituted with a fluorine atom; Ring J, Ring K and Ring M are each independently trans-1 , 4-cyclohexylene, pyrimidine-2,5
-Diyl or 1,4-phenylene in which a hydrogen atom may be replaced by a fluorine atom; Z6 and Z7 each independently represent 1,2-ethylene, -C≡C-, -CO
O-, -CH = CH- or a single bond is shown. Specific examples of these compounds will be given below.

[0054]

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[0055]

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[0056]

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[0057]

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(E) As the first component, at least one compound selected from the group consisting of the compounds represented by the above formulas (8) and (9) is contained, and as the second component, the compounds represented by the above formulas (13) and (14) Or (15) a liquid crystal composition containing at least one compound selected from the group of compounds represented by (15). (F) As the first component, the above general formulas (10) and (11)
Or at least one compound selected from the group of compounds represented by (12), and as the second component, selected from the group of compounds represented by formula (13), (14) or (15) above. Liquid crystal composition containing at least one compound represented by the formula: (G) As the first component, at least one compound selected from the group of compounds represented by the above general formulas (5), (6) and (7) is contained, and as the second component, the above general formula (8) ) Or at least one compound selected from the group of compounds represented by (9), and as the third component selected from the group of compounds represented by the above general formula (13), (14) or (15) Liquid crystal composition containing at least one compound represented by the formula: Further, the liquid crystal compositions shown in the above (A) to (G) may contain at least one optically active compound for use.

【Example】

Before describing Example 1, the names of the tetracarboxylic dianhydride, the diamine compound and the solvent are abbreviated. This abbreviation may be used in the following description. Tetracarboxylic dianhydride Cyclobutanetetracarboxylic dianhydride: CBDA Butanetetracarboxylic dianhydride: BDA Pyromellitic acid: PMDA Diamine compound 4,4'-diamino-1,2-diphenylethane: DPEt 1,2- Bis- (4-amino-2-methylphenyl) ethane: DMDPet 1,4-bis [2- (4-aminophenyl) ethyl] benzene: DPEB 4,4'-diaminodiphenylmethane: DPM 4,4'-diamino- 1,3-diphenylpropane: DPP 1,2-bis- (4-amino-2-methylphenyl) methane: DMDPM 1,2-bis- (4-amino-3,5-dimethylphenyl) methane: TMDPM 4, 4'-diaminodiphenyl ether: DPer 2,2-bis [(4,4'-diaminophenoxy ) Phenyl)] propane: DPPP Solvent component N-methyl-2-pyrrolidone: NMP butyl cellosolve: BC

[0060]

Example 1 (1) Synthesis of Polyamic Acid A1 2.4720 g of DPEt, 0.6588 g of DMDPM and dehydration were placed in a 200 ml four-necked flask equipped with a thermometer, a stirrer, a raw material charging port and a nitrogen gas inlet. 44.00 g of NMP was added and stirred under a dry nitrogen stream to dissolve. Next, 1.4419 g of BDA and CBDA
After adding 1.4273 g in sequence and reacting at room temperature for 30 hours, 50.00 g of BC was added to synthesize a polyamic acid A1 having a polymer concentration of 6%. Next, NMP and BC 1
The mixture was diluted with a one-to-one mixed solvent to adjust the polyamic acid concentration to 3%, thereby obtaining an aligning agent for spinner coating. (2) Preparation of cell for measuring pretilt angle On a glass substrate with an ITO transparent electrode, an orientation agent for application of polyamic acid A1 was applied by a spinner, and the coating was performed at 80 ° C for about 5 hours.
After pre-baking for 30 minutes, a heat treatment was performed at 200 ° C. for 30 minutes to imidize the polyamic acid. Next, the surface of the substrate on which the coating film was formed was rubbed with a rubbing device to perform an alignment treatment, and further subjected to ultrasonic cleaning in ethanol for 5 minutes, and the surface was cleaned in a flow of chlorofluorocarbon. Dry at 分 間 C for 30 minutes. 2 on this board
Spray a gap material for 0 μm, seal with an epoxy curing agent with the surface on which the alignment film is formed inside,
m anti-parallel cells were created. A liquid crystal material was injected into this cell, and the injection port was sealed with a photocuring agent. Next, heat treatment was performed at 110 ° C. for 30 minutes to obtain a pretilt angle measurement cell. The composition of the liquid crystal composition used as the liquid crystal material is shown below. This composition has an NI point of 88.3.
° C, refractive index anisotropy: 0.151 and threshold voltage:
It was 1.35V.

[0061]

Embedded image

(3) Measurement of Pretilt Angle The pretilt angle of the liquid crystal was measured by a usual crystal rotation method. The pretilt angle of the device made using the above liquid crystal material was 2.3 degrees. (4) Preparation of Cell for Evaluation of Electric Characteristics A cell for evaluation of electric characteristics was prepared in the same manner as the cell for measuring the pretilt angle, except that the cell was prepared using a gap material for 7 μm. (5) Evaluation of Current Consumption Value A 10 V, 32 Hz rectangular wave was applied to the evaluation cell prepared according to the preceding section, and the current consumption value was measured. The electrode area of this cell was 1 cm ² . First, the initial value of the consumption current value was measured, and then the consumption current value after the constant temperature heating test at 110 ° C. for 120 hours was measured. The value obtained by dividing the value of the consumed current value after 120 hours by the initial value was determined as the change ratio of the consumed current value with time. The initial value of the current consumption was 1.6 μA, and the change over time was 1.21. (6) Preparation of cell for evaluating unevenness in water washing 0.01 ml of ultrapure water (specific resistance 1 × 10 ¹⁷ Ωcm) was dropped on the substrate electrode subjected to the rubbing treatment described in the above item (2) and left for 5 minutes. After washing with ultrasonic waves for 5 minutes in a bath and cleaning the surface in a flow of Freon, it was dried in an air oven at 120 ° C. for 30 minutes. 7μ on this substrate
m, and seal with an epoxy curing agent with the surface on which the alignment film is formed facing inward.
N cells were created. After the same liquid crystal material as that used in the above (2) was injected into this cell, the injection port was sealed with a photocuring agent. Next, heat treatment was performed at 110 ° C. for 30 minutes to obtain a cell for evaluating uneven cleaning. (7) Evaluation of water washing unevenness As a result of applying a DC voltage to the evaluation cell created in the preceding section, which shows the most intense traces of water droplets on the panel, and visually observing the presence of water droplets and the shading, no water washing unevenness was observed. Was.

[0063]

Examples 2 to 8 and

Comparative Examples 1 to 13 Polyamic acid A1 in Example 1
Instead of the above, polyamic acids A2 to A8 and polyamic acids B1 to B13 were synthesized with the raw material compositions shown in Table 1 below, respectively, and the pretilt angle, the current consumption value, and the evaluation of unevenness in washing were evaluated in the same manner as in Example 1. It went to. Synthesis Examples of Various Polyamic Acid Components Polyamic Acids A2 to A8 and Polyamic Acids B1 to B1
About the synthesis | combination of 3, it synthesize | combined by the method similar to the synthesis example A1. When the temperature increased due to the heat of the reaction during the reaction, the reaction was carried out at a temperature of about 70 ° C. or less. In the synthesis of the polyamic acid, the reaction is performed while checking the viscosity of the reaction solution, and the viscosity of the polyamic acid after adding BC is 55 to 6
The reaction was terminated when the pressure reached 5 mPa · s (using an E-type viscometer at 25 ° C.), and the polyamic acid was stored at a low temperature. That is, the initial polyamic acid is synthesized only with NMP, and then BC is added to finally adjust the polyamic acid concentration to 6
%. Table 1 shows the molar ratios of the raw materials in each synthesis example.

[0064]

[Table 1]

Examples 1 to 3 and Comparative Examples 1 to 3 The devices prepared using the polyamic acids A1 to A3 and the devices prepared using the polyamic acids B1 to B3 were examined with respect to the pretilt angle, the electrical characteristics, and the unevenness of washing. Table 2 shows the results
Shown in Incidentally, as the excellent electrical characteristics in the present invention,
Polyamic acid having a low current consumption value and high long-term reliability of the current consumption value, specifically, in the test method of the example of the present invention, the current consumption value is 1.8 μA or less, and 110 ° C. , Which means that the rate of increase in the current consumption after a constant temperature heating test for 120 hours is 1.4 times or less.

[0066]

[Table 2]

From the results of Examples 1 to 3 and Comparative Examples 1 to 3, according to the present invention, the pretilt angle was 2 to 3 degrees, the initial value of the current consumption value and the change ratio with the passage of time were excellent, and water washing was performed. It can be seen that a liquid crystal aligning agent free from unevenness in washing can be obtained. According to the pretilt angles of Examples 1 to 3 and Comparative Examples 1 to 3, the DPEt mole fraction was 25% or more,
A pretilt angle of 2 to 2.7 degrees has been obtained. However, it can be seen that uneven washing with water occurs at 50% DPEt. On the other hand, it can be seen that good values were obtained for the initial value of the current consumption value and the change ratio with time, regardless of the DPEt mole fraction. These results are summarized in FIG.

[0068]

FIG.

From this figure, it can be understood that there is a well-balanced region of the pretilt angle, the initial value of the current consumption value, the change over time, and the unevenness of washing at a molar ratio of DPEt to DMDPM diamine of 50/50 to 95/5.

Examples 4 to 6 and

Comparative Examples 4 to 10 In this example and this comparative example, the results of investigations on the pretilt angle, the electrical characteristics and the unevenness of washing of the polyamic acids A4 to A6 and the polyamic acids B4 to B10 are shown. Table 3 shows Examples 1, 4 to 6 and Comparative Examples 4-1.
A result of 0 is shown.

[0070]

[Table 3]

Results of Examples 1, 4 to 6 and Comparative Examples 4 to
From the result of 5, it was found that the linking group of the benzene ring was -CH2CH2-
A diamine compound DPEt, DMDPet or D
By using PEB in combination with a diamine compound DMDPM or TMDPM having a methyl group at a benzene ring's lateral position, it has a pretilt angle of 2 to 3 degrees, is excellent in an initial value of current consumption value and a change ratio with time, and is washed with water. It can be seen that a liquid crystal aligning agent free from unevenness in water washing can be obtained even when the above-mentioned step is carried out. From the results of Comparative Examples 6 to 8, it can be seen that when the diamine compound in which the linking group of the benzene ring is -CH2- and -CH2CH2CH2- is used alone, the pretilt angle is too low, which is not preferable. Furthermore, from the results of Comparative Examples 9 and 10, it can be seen that as the diamine component used in the polyamic acid, those having an ether group such as DPer and DPPP are not preferable in terms of electrical properties and unevenness in washing.

Examples 7 and 8 and Comparative Examples 11 to 1
3, polyamic acids A7 and A8 and polyamic acids B11
Table 4 shows the observation results of the pretilt angle, the electrical characteristics, and the unevenness of washing of the elements prepared using the samples Nos. B13 to B13.

[0073]

[Table 4]

Examples 1, 7, 8 and Comparative Examples 11 to 13
From the results, it was found that the tetracarboxylic dianhydride component used in the polyamic acid is more CBDA than PMDA
Alternatively, it can be seen that BDA is more preferable in terms of electrical characteristics. On the other hand, the pretilt angle may be larger when PMDA is used. Therefore, when a larger pretilt angle is required, the PM should be reduced to such an extent that there is no problem in the electrical characteristics.
It can be said that it is preferable to use DA in combination.

[0075]

In the liquid crystal display device, by using the liquid crystal aligning agent containing the polyamic acid of the present invention, a pretilt angle of 2 to 3 degrees is obtained, an initial value of current consumption value and a change ratio with time are small, and An excellent liquid crystal display element free from unevenness in washing can be produced.

[0076]

[Brief description of the drawings]

FIG. 1 is a region diagram of the present invention showing a pretilt angle, an initial value of a current consumption value, a time-dependent change ratio, and a balance of washing unevenness in a liquid crystal display device using a polyamic acid solution of the present invention. / DMDPM ratio.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09K 19/20 C09K 19/20 19/30 19/30 19/34 19/34 19/56 19/56 G02F 1/13 500 G02F 1/13 500 1/1337 520 1/1337 520 F term (reference) 2H090 HB09Y HB10Y HD12 HD14 KA05 KA08 MA04 MA11 4H027 BD13 BE04 CA03 CB01 CB03 CC04 CE03 CM01 CM04 CN05 CT01 CT04 CW01 4J002 CM041 EB106 ED106 EH116 EH126 EH146 EL106 ET006 EU096 GH00 GQ00 HA05 4J043 PA02 PA05 PA06 PA08 PB21 PB23 PC015 QB31 RA05 RA34 SA06 SA42 SA43 SA44 SB01 SB03 TA13 TA22 TA66 TB01 TB03 VA04 UA022 UA032 UA042 UA051 UA081 UA081 UA081 UA081 UA081 UA081 ZB23

Claims (16)

[Claims] 1. A polyamic acid obtained from a tetracarboxylic dianhydride and a diamine as main raw materials, wherein the diamine is a compound represented by the formula (1) as a raw material. Embedded image In the formula (1), R1 is hydrogen or CH3, and 3
R1 may be the same or different, a, b and c are 1 or 2, and n is an integer of 0 to 2. 2. The polyamic acid according to claim 1, wherein at least one selected from the group consisting of aliphatic tetracarboxylic dianhydride and alicyclic tetracarboxylic dianhydride is used as the tetracarboxylic dianhydride. . 3. The compound represented by the formula (1) and the compound represented by the formula (2) are used as the diamine.
Polyamic acid according to the above. Embedded image In the formula (2), 1 and m are 1 or 2. 4. The polyamic acid according to claim 3, wherein an aliphatic tetracarboxylic dianhydride and an alicyclic tetracarboxylic dianhydride are used as the tetracarboxylic dianhydride. 5. The diamine represented by the formula (1) according to claim 4, wherein the ratio of the aliphatic tetracarboxylic dianhydride to the alicyclic tetracarboxylic dianhydride is 90/10 to 30/70. And the ratio of the diamine represented by the formula (2) is 9
A polyamic acid which is 5/5 to 50/50. 6. The polyamic acid according to claim 5, wherein butanetetracarboxylic dianhydride is used as aliphatic tetracarboxylic dianhydride, and cyclobutanetetracarboxylic dianhydride is used as alicyclic tetracarboxylic dianhydride. . 7. A polyamic acid solution containing the polyamic acid according to claim 1, wherein
A polyamic acid solution comprising 1 to 40% by weight of polyamic acid. 8. A liquid crystal display device produced using a polyamic acid solution containing the polyamic acid according to claim 1 and a liquid crystal material. 9. The liquid crystal display device according to claim 8, wherein the liquid crystal material is at least one selected from the group of compounds represented by the following formulas (5), (6) and (7). Embedded image In these formulas, R2 represents an alkyl group having 1 to 10 carbon atoms, and any non-adjacent methylene group in the group is -O
-Or -CH = CH-, and any hydrogen atom in the alkyl group may be substituted with a fluorine atom; R3 represents a fluorine atom, a chlorine atom, -OCF
3, -OCF2H, -CF3, -CF2H, -CFH
2, -OCF2CF2H or -OCF2CFHCF3
L1 and L2 each independently represent a hydrogen atom or a fluorine atom; Z1 and Z2 each independently represent 1,2-ethylene, 1,4-butylene, -COO-,-
CF2O-, -OCF2-, -CH = CH- or a single bond; ring B is trans-1,4-cyclohexylene, 1,3-dioxane-2,5-diyl, or a hydrogen atom is substituted by a fluorine atom Ring C represents trans-1,4-cyclohexylene or 1,4-phenylene in which a hydrogen atom may be replaced by a fluorine atom. 10. The liquid crystal display device according to claim 8, wherein the liquid crystal material is at least one compound selected from the group of compounds represented by the following formulas (8) and (9). Embedded image In these formulas, R4 and R6 each independently have 1 carbon atom.
Represents an alkyl group of 10 to 10, wherein any non-adjacent methylene group in the group may be substituted with -O- or -CH = CH-, and any hydrogen atom in the alkyl group is substituted with a fluorine atom. R5 is -CN or-
Ring D represents trans-1,4-cyclohexylene, 1,4-phenylene, 1,3-dioxane-2,5-diyl, or pyrimidine-2,5-diyl; E is trans-1,4-cyclohexylene,
1,4-, in which a hydrogen atom may be replaced by a fluorine atom
Represents phenylene or pyrimidine-2,5-diyl;
Ring F is trans-1,4-cyclohexylene or 1,
Represents 4-phenylene; Z3 is 2-ethylene, -COO
-Or a single bond; L3, L4 and L5 independently represent a hydrogen atom or a fluorine atom; e, f and g each independently represent 0 or 1. 11. The liquid crystal display according to claim 8, wherein the liquid crystal material is at least one compound selected from the group of compounds represented by the following formulas (10), (11) and (12). element. Embedded image In these formulas, R7 and R8 are independently
Represents an alkyl group of 10 to 10, wherein any non-adjacent methylene group in the group may be substituted with -O- or -CH = CH-, and any hydrogen atom in the alkyl group is substituted with a fluorine atom. Ring G and Ring I are independently trans-1,4-cyclohexylene or 1,4-
L6 and L7 each independently represent a hydrogen atom or a fluorine atom but not simultaneously a hydrogen atom; Z4 and Z5 each independently represent 1,2-ethylene, -CO
O- or a single bond is shown. 12. The liquid crystal material according to claim 9, wherein the liquid crystal material further contains at least one compound selected from the group of compounds represented by the following formulas (13), (14) and (15). Liquid crystal display device. Embedded image In these formulas, R9 and R10 independently represent an alkyl group having 1 to 10 carbon atoms, and any non-adjacent methylene group in the group may be substituted with -O- or -CH = CH-, Any hydrogen atom in this alkyl group may be replaced by a fluorine atom; ring J, ring K and ring M are independently trans-1,4-cyclohexylene, pyrimidine-2,5-diyl or hydrogen atom Represents 1,4-phenylene which may be substituted by a fluorine atom; Z6
And Z7 are independently 1,2-ethylene, -C≡C-,-
COO-, -CH = CH- or a single bond is shown. 13. The liquid crystal material according to claim 10, wherein the liquid crystal material further contains at least one compound selected from the group of compounds represented by the following formulas (13), (14) and (15). Liquid crystal display device. Embedded image In these formulas, R9 and R10 independently represent an alkyl group having 1 to 10 carbon atoms, and any non-adjacent methylene group in the group may be substituted with -O- or -CH = CH-, Any hydrogen atom in this alkyl group may be replaced by a fluorine atom; ring J, ring K and ring M are independently trans-1,4-cyclohexylene, pyrimidine-2,5-diyl or hydrogen atom Represents 1,4-phenylene which may be substituted by a fluorine atom; Z6
And Z7 are independently 1,2-ethylene, -C≡C-,-
COO-, -CH = CH- or a single bond is shown. 14. The liquid crystal material according to claim 11, wherein the liquid crystal material further contains at least one compound selected from the group of compounds represented by the following formulas (13), (14) and (15). Liquid crystal display device. Embedded image In these formulas, R9 and R10 independently represent an alkyl group having 1 to 10 carbon atoms, and any non-adjacent methylene group in the group may be substituted with -O- or -CH = CH-, Any hydrogen atom in this alkyl group may be replaced by a fluorine atom; ring J, ring K and ring M are independently trans-1,4-cyclohexylene, pyrimidine-2,5-diyl or hydrogen atom Represents 1,4-phenylene which may be substituted by a fluorine atom; Z6
And Z7 are independently 1,2-ethylene, -C≡C-,-
COO-, -CH = CH- or a single bond is shown. 15. The liquid crystal display device according to claim 12, wherein the liquid crystal material further contains at least one compound selected from the group of compounds represented by the following formula (8) or (9). Embedded image In these formulas, R4 and R6 each independently have 1 carbon atom.
Represents an alkyl group of 10 to 10, wherein any non-adjacent methylene group in the group may be substituted with -O- or -CH = CH-, and any hydrogen atom in this alkyl group is substituted with a fluorine atom. R5 is -CN or-
Ring D represents trans-1,4-cyclohexylene, 1,4-phenylene, 1,3-dioxane-2,5-diyl, or pyrimidine-2,5-diyl; E is trans-1,4-cyclohexylene,
1,4-, in which a hydrogen atom may be replaced by a fluorine atom
Represents phenylene or pyrimidine-2,5-diyl;
Ring F is trans-1,4-cyclohexylene or 1,
Represents 4-phenylene; Z3 is 1,2-ethylene, -C
L3, L4 and L5 each independently represent a hydrogen atom or a fluorine atom; e, f and g each independently represent 0 or 1. 16. The liquid crystal display device according to claim 9, wherein the liquid crystal material further contains at least one optically active compound.