JP2001316670A - Liquid crystal composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal composition which does not affect the display properties of the liquid crystal and has an antistatic effect and a high long-time reliability, and a liquid crystal display. SOLUTION: The liquid crystal composition has a specific resistance of at least 1.0×1011 Ωcm and is a nematic liquid crystal composition containing content A comprising one or an arbitrary combination of the group of compounds consisting of isoquinoline of formula I of a compound having an isoquinoline structure, quinaldine of formula II of a compound having an quinaldine structure and quinoxaline of formula III of a compound having an quinoxaline structure. The composition gives a liquid crystal composition which has suppressed static phenomena without affecting the original properties of the liquid crystal. The long-time reliabilities of both the obtained liquid crystal composition and the liquid crystal display device using the composition are excellent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an isoquinoline represented by the formula (1) or a compound having an isoquinoline structure,
A compound having a quinaldine or a compound having a quinaldine structure represented by (2), characterized by being added with any one or any combination of quinoxaline or a compound having a quinoxaline structure represented by the formula (3), the specific resistance is at least The present invention relates to a liquid crystal composition having 1.0 × 10 ¹¹ Ωcm and a liquid crystal display device using the same, particularly to a field effect liquid crystal display device.

[0002]

2. Description of the Related Art Liquid crystal display devices, particularly field-effect type liquid crystal display devices, are used in various applications such as watches, calculators, mobile communication portable terminals, OA equipment, and home appliances. Such a field effect type liquid crystal display element has a problem of malfunction due to charging. On the other hand, JP-A-59-4676 discloses a method in which an ionic substance such as a quaternary ammonium salt is added to reduce the specific resistance.
A method has been proposed in which charging is prevented by lowering the current to 10 ¹⁰ Ωcm and passing a current. However, the addition of such ionic substances adversely affects the display characteristics and reliability of the liquid crystal,
There is a drawback that display failure occurs. Therefore, there has been a demand for a liquid crystal composition and a liquid crystal display element having an antistatic effect that does not affect the display characteristics of the liquid crystal and has high long-term reliability.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a liquid crystal composition and a liquid crystal display element having an antistatic effect which does not affect the display characteristics of the liquid crystal and has a high long-term reliability. It is in.

[0004]

In order to solve the above-mentioned problems, the present invention has found the following liquid crystal composition and a liquid crystal display device using the liquid crystal composition.

Invention 1 A liquid crystal composition having a specific resistance of at least 1.0 × 10 ¹¹ Ωcm, comprising an isoquinoline represented by the formula (1) or a compound having an isoquinoline structure,
(2) a quinaldine or a compound having a quinaldine structure represented by the formula (3), a quinoxaline represented by the formula (3) or a compound having a quinoxaline structure, characterized by containing a component A which is any one or any combination thereof Nematic liquid crystal composition.

[0006]

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Invention 2 The content of the component A is 0.01 to 10.0% by mass.
The liquid crystal composition according to invention 1, wherein Invention 3 The liquid crystal composition according to Invention 1 or 2, wherein the charging time is 30 seconds or less. Invention 4 The liquid crystal composition according to Invention 1 or 2, wherein the voltage holding ratio is 70% to 85%. Invention 5 A liquid crystal display device using the liquid crystal composition according to any one of Inventions 1 to 3. Invention 6 is a method for improving charging of a liquid crystal display element,
A method comprising using the liquid crystal composition according to any one of Inventions 1 to 3 for a liquid crystal display device.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of the present invention will be described below. In the invention 1, the specific resistance of the liquid crystal composition is 1.0 × 10 ¹¹ Ωc
It is preferably m~1.0 × 10 ¹³ Ωcm, particularly preferably ^{1.0 × 10 11 Ωcm~5.0 × 10 12} Ωcm, more preferably from ^{1.0 × 10 11 Ωcm~1.0 × 10 12} Ωcm. Further, it preferably contains isoquinoline.

In the invention 2, the content of the compound of the component A is
It is preferably 0.01 to 5.0% by mass, particularly 0.01 to 1.0% by mass.
It is preferable that the content is mass%.

In the invention 3, the charging time is 30 seconds or less, and particularly preferably 20 seconds or less.

In the invention 4, a field effect type liquid crystal display element is suitable for the liquid crystal display element.
Liquid crystal display device having a twist angle of, for example, TN
A (twisted nematic) display element or a super twist type liquid crystal display element, for example, an STN (super twisted nematic) liquid crystal display element is suitable. Further, the present invention can be applied to a liquid crystal display element having no twist and an IPS (in-plane switching) liquid crystal display element.

The nematic liquid crystal composition contains 5 or more, preferably 10 or more liquid crystal compounds and preferably has an optical anisotropy of 0.03 to 0.30, more preferably 0.05 to 0.30.
~ 0.20. The dielectric anisotropy of the liquid crystal composition is at least
3, preferably 5 or more. The liquid crystal composition has a nematic-isotropic phase transition temperature of at least 70 ° C, particularly preferably at least 80 ° C.

[0013]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. Further, “%” in the compositions of the following examples means “% by mass”.

The following abbreviations are used in describing the compounds. Terminal n (number): C _n H _{2n + 1} -ndm-: C _n H _{2n + 1} -C = C- (CH ₂ ) _m-1 --T-: -C≡C- -VO-:- COO- F: -F On: -OC _n H _{2n + 1}

[0015]

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For example, abbreviations are used as shown below.

[0017]

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Example 1, Comparative Example 1 A liquid crystal composition R was prepared according to a conventional method. Isoquinoline was added to the obtained liquid crystal composition R at 1.0% by mass to prepare a liquid crystal composition M according to the present invention. As a comparative example, a liquid crystal composition R containing no isoquinoline was added.
And injecting the liquid crystal composition M according to the present invention into a TN cell having a 90 ° twist, charging time (sec), electro-optical characteristics, and voltage holding ratio.
(%) And phase transition temperature (° C.).

Charge time measurement method: Structure Probe, I
The test cell was charged using the nc. Zerostat Antistatic Gun. The time from when the electrode portion of the test cell turned on until when it turned off was measured with a stopwatch. Specific resistance measurement method: Put the liquid crystal composition in the liquid electrode and apply voltage
(DC) The resistance value when 1 V was applied was measured at 25 ° C. Voltage holding ratio measurement method: 90 ° twist T with cell thickness d = 8.3μm
When a voltage of 5 V was applied to the N cell, the voltage held after 20 msec was measured. The ratio of this value to the initial voltage of 5V is%
Expressed by Threshold voltage measurement method: A voltage was applied to a 90 ° twist TN cell, and the voltage at 90% transmittance was measured when the initial transmittance was 100%. Phase transition temperature (nematic-isotropic phase transition temperature)
Measurement method: Liquid crystal (nematic phase) when temperature is increased
The temperature (° C.) when was changed to the isotropic phase was measured by visual observation.

[0020]

[Table 1]

It can be seen that M, which is the liquid crystal composition of the present invention, has a charging time 1/6 that of R, and has a large effect of preventing charging. On the other hand, it can be seen that the phase transition temperature and the threshold voltage hardly change. The addition of isoquinoline reduced the specific resistance and the voltage holding ratio, but did not affect the electro-optical characteristics. As described above, it can be seen that the method of the present invention has the effect of suppressing charging without substantially changing the electro-optical characteristics and the like of the liquid crystal composition.

Further, after injecting the liquid crystal compositions M and R into the TN cell, a UV reliability test (FIG. 1) and a heating reliability test (FIG. 2) were performed, and an ionic substance such as a quaternary ammonium salt was tested. No decrease in the initial specific resistance and the retention as seen in the system to which was added was further deteriorated by the reliability test. That is, no significant deterioration in reliability due to the addition of isoquinoline was observed. As described above, the addition of isoquinoline can provide a liquid crystal composition which is extremely stable as compared with the conventional addition of an ionic substance.

[0023]

According to the liquid crystal composition to which the isoquinoline of the present invention is added, a liquid crystal composition in which the charging phenomenon is suppressed without impairing the original characteristics of the liquid crystal composition can be obtained.
In addition, a liquid crystal display device having an excellent charge suppressing effect was able to be produced using this composition. This liquid crystal composition is TN
And it is useful and practical as STN-LCD (STN liquid crystal display). According to the method of the present invention, an antistatic effect can be obtained regardless of the liquid crystal composition. If the liquid crystal composition according to the present invention is used, erroneous display due to electrification in the manufacturing process,
It is not necessary to provide a special static elimination facility in the process, and the production process can be reduced and the productivity can be improved.

[Brief description of the drawings]

FIG. 1 is a graph of a UV reliability test of a liquid crystal containing isoquinoline.

FIG. 2 is a graph of a heating reliability test of the liquid crystal containing isoquinoline.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Naoe Kato 7-24-1-403 Aoto, Katsushika-ku, Tokyo (72) Inventor Haruyoshi Takatsu 3-6-27 Nakahara, Higashiyamato-shi, Tokyo F-term (reference) 4H027 BA01 BB04 BC04 BD24 BE07 CL01 CL04 CR01 CS04 CT02 CT04 CU01 CW02 DL01 DL02

Claims (6)

[Claims] 1. A liquid crystal composition having a specific resistance of at least 1.0 × 10 ¹¹ Ωcm, comprising an isoquinoline represented by the formula (1) or a compound having an isoquinoline structure, a quinaldine represented by the formula (2) or a quinaldine structure represented by the formula (2): 1. A nematic liquid crystal composition comprising: a compound having a quinoxaline represented by the formula (3) or a compound having a quinoxaline structure, or a component A which is an arbitrary combination thereof. Embedded image 2. The liquid crystal composition according to claim 1, wherein the content of the component A is 0.01 to 10.0% by mass. 3. The liquid crystal composition according to claim 1, wherein the charging time is 30 seconds or less. 4. The liquid crystal composition according to claim 1, wherein the voltage holding ratio is from 70% to 85%. 5. A liquid crystal display device using the liquid crystal composition according to claim 1. 6. A method for improving charging of a liquid crystal display device, wherein the liquid crystal composition according to claim 1 is used for a liquid crystal display device.