JPS59115377A - Nematic liquid crystal composition - Google Patents

Abstract

PURPOSE:To provide a nematic liquid crystal compsn. which has a low viscosity and excellent time division driving characteristics, can be driven at a low voltage and is excellent in compatibility of compds., containing four specified kinds of compds. CONSTITUTION:A nematic liquid crystal compsn. consists of a compd. of formula I (wherein R is a 1-7C straight-chain alkyl; R' is a 1-17C straight-chain alkoxyl), a compd. of formula II (wherein R, R' are each a 1-7C straight-chain alkyl), a compd. of formula III (wherein R is a 1-7C straight-chain alkyl) and a compd. of formula IV (wherein R is a 1-7C straight-chain alkyl). The compd. of formula I has a low viscosity, excellent time division driving characteristics, a wide nematic liquid crystal temp. range, excellent compatibility with other liquid crystal mixture and is used as a main component. The compd. of formula IIhas a low viscosity and low anisotropy in refractive index. The compd. of formula III has very high anisotropy in dielectric constant and makes low- voltage driving possible by the incorporation of a small quantity thereof. By the incorporation of the compd. of formula IV, the compatibility of the compds. of formulas I , II and III with one another is increased and the liquid crystal temp. range can be widened.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to novel nematic liquid crystal compositions useful as electro-optic display materials.

M-Shut (M, 5) is a typical liquid crystal display cell.
chadt) etc. [:APPI, IED PI (YSI
C8LETTER81 and 127-128 (1971)
) or the field effect mode cell proposed by G.H. Beilmeier, etc. [PRO
CEEDING OF THE 1. E, E, E,
561162-1171 (1968)) or the dynamic scattering mode cell proposed by G.H.
G, HoHeilmeier) et al. [:APPLIED
PHYSIC8LETTER8±pre-291 (1968
)) Or D, L, Whi
te ) etc. (JOVRNAL OF APPLIEDP
There is a guest-host type cell proposed by HYSIC 845, 4718 (1974). The liquid crystal materials used in these liquid crystal display cells are required to have various properties, but for example, low viscosity is necessary to increase response speed, which is common to all types of cells mentioned above. A small refractive index anisotropy (△n) is required to increase the dichroism ratio of guest-host cells or to create field-effect cells with wide viewing angles. A large dielectric constant anisotropy is a characteristic required for driving a field effect cell at a low voltage.

The purpose of the present invention is to provide a nematic liquid crystal composition having these characteristics, and the purpose is to provide a nematic liquid crystal composition having these characteristics.
(In the formula, R is a linear alkyl group having 1 to 7 carbon atoms, R
' represents a linear alkoxyl group having 1 to 7 carbon atoms, respectively. ); (In the formula, R and R' each represent a linear narkyl group having 1 to 7 carbon atoms.); 7 represents a linear alkyl group) and (wherein, R represents a linear alkyl group having 1 to 7 carbon atoms). achieved.

The compound of general formula (1) is known from East German Patent No. 105701, and has the following features: low viscosity, extremely excellent time division drive characteristics, wide nematic liquid crystal temperature range, and other liquid crystal Due to its excellent compatibility with other compounds, it is used as the main component of the display liquid crystal material in each building, and the composition of the present invention also utilizes the above-mentioned properties of this compound.

The compound of general formula (2) was proposed in Japanese Patent Application No. 56-4136 previously filed by the present inventors, and has low viscosity and anisotropy of refractive index (△n). Due to its small size, when added to other nematic liquid crystal materials, it has little effect on fluctuations in the liquid crystal temperature range of the material, especially when added to other nematic liquid crystal materials.
The composition of the present invention does not significantly lower the I transition temperature (nematic phase - isotropic liquid phase transition temperature), and is a useful compound as a viscosity lowering agent and a refractive index anisotropy lowering agent. It takes advantage of the properties of On the other hand, since the compound of general formula (2) is a smectic liquid crystal compound,
Like other general smectic liquid crystal compounds, when mixed with a nematic liquid crystal compound, if the mixing ratio exceeds a certain level, the mixed liquid crystal will exhibit a smectic phase in a low temperature range. Appearance can be achieved by setting appropriate mixing ratios.

Therefore, this itself does not pose a problem in designing the composition of the present invention. However, if we want to make the anisotropy of the refractive index of the mixed liquid crystal as small as possible and thereby further increase the dichroic ratio of the mixed liquid crystal, the general formula (2
) becomes necessary to increase the mixing ratio of the compound.

In such a case, it is desirable to mix a compound represented by (in the formula, m represents an integer of 1 to 7). This is because this compound can be mixed in a larger amount than other compounds of general formula (2) without producing a smectic phase in a low temperature range. To illustrate this point with specific examples, see Figures 1 to 3.
As shown in the diagram.

That is, FIGS. 1, 2, and 3 show the following parent liquid crystals (
For A), the following formulas (1b), (1c) and (1d)
It is a phase diagram of each mixed liquid crystal obtained by mixing each compound in various ratios. As is clear from the comparison of Figures 1 and 2 with Figure 6, the maximum amount that can be mixed without causing the appearance of a smectic phase at low temperatures is 10% of the compound of formula (1d). In contrast, the compound of formula (1b) accounts for 62%, and the compound of formula (1C) accounts for 20%.

The parent liquid crystal diagram is 1 mol of n-C3H7% C00-e OC2Ha1
Mol n-C4H, PeDCOO-CJ-o C2&
and 1 mol of n -Cal Hl @COO-
Q o CH,.

It consists of

n-C3H, 18CH2CH, -C door H, -... (1b
)n CaH7+CH2CH2+n C3H?・”
``'(1d) The compound of general formula (3) is a new compound proposed in Japanese Patent Application No. 179618/1987 previously filed by the present inventors, and has dielectric constant anisotropy (△ ε) is +
66, which is a surprisingly large compound. Therefore, by mixing a small amount of this compound, it becomes possible to drive the mixed liquid crystal at a low voltage. The present inventors have learned that in order to improve the time-division drive characteristics of a mixed liquid crystal, it is effective to minimize the amount of the mixture with a strong positive △ε. From previous studies, compounds of general formula (3) are suitable for this purpose.

The compound of formula (3) can be produced by a two-step reaction as shown in the reaction formula.

In the first step, a compound of formula (3a') (wherein, be.

) is manufactured.

In the compound of formula (3a), X is preferably a chlorine atom, and thionyl chloride may be used as the /'%Q generating agent. The reaction is carried out at normal pressure and the reflux temperature of the reaction mixture.

It is not necessary to isolate the compound of formula (5a') from the mixture produced by the reaction (it is only necessary to remove excess halogenating agent).

In the second step, the crude compound of formula (38) prepared in the first step and the compound of formula (3b) are reacted in an inert organic bath medium. Examples of inert organic solvents include diethyl ether, tetrahydrofuran, dimethyl Formamide, benzene, etc. may be used.In order to remove the hydrogen halide liberated during the reaction from the reaction system, a basic substance such as pyridine, 6th class amine, etc. may be included in the inert organic solvent. It is desirable to

The reaction is carried out at normal pressure and at a temperature ranging from room temperature to the reflux temperature of the reaction mixture. By subjecting the reaction product to a series of purification treatments such as solvent extraction, water washing, drying, and recrystallization, the target compound of formula (3) can be isolated.

The transition temperature of the representative compound of formula (3) thus produced is as shown in the table below. In the table below, C represents a crystal, N represents a nematic phase, and ■ represents an isotropic liquid.

The compound of general formula (4) in Table 1 is known from JP-A No. 53-23957, and has a relatively large Δε of +11 (,
Since it is a compound with a relatively low viscosity, it is effective for low-voltage drive and high-speed response, but its primary role in the composition of the present invention is elsewhere. That is, through the intervention of this compound, the above-mentioned general formulas (1), (2) and (3)
The mutual solubility of the six types of compounds further increases, thereby making it possible to widen the liquid crystal temperature range of the mixed liquid crystal.

The preferred mixing ratio of the four essential components of the composition of the present invention described above is 15 to 755 to 75% by weight of the compound of general formula (1), 5 to 4% by weight of the compound of formula (2), and 5 to 4% of the compound of general formula (3). Compound 5-65% by weight and compound 15-50f of general formula (4)
f & amount%.

Hereinafter, the present invention will be explained in more detail using specific examples.

Examples 1 to 10 Mixed liquid crystals having various compositions were prepared, and their respective viscosity (4720°C) and threshold voltage (Vth/'20°C)
) and refractive index anisotropy (Δn) were measured. The results are listed in Table 2.

However, (B) in the table is a mixed liquid crystal consisting of and, and its η is 20 centivoise/
At 20° C., vth is 2.20 volts, and Δn is 0.085.

[Brief explanation of the drawing]

Figures 1, 2 and 6 show nematic matrix liquid crystal (A
) with smectic liquid crystal compounds (1b), (1C) and (
1d) It is a phase diagram of a mixed liquid crystal formed by mixing each of 'e. In the figure, ■ indicates an isotropic liquid phase, N indicates a nematic phase, S indicates a smectic phase, and C indicates a crystalline phase. Patent applicant Dainippon Ink & Chemicals Co., Ltd. Figure 1 (A) +C11) tt% accommodation of IJf (/l,)
2 Figure 10 20 30 4O CA)+CIC)l2 wt% of (IC) 4th
figure

Claims (1)

[Scope of Claims] (In the formula, R is a linear alkyl group having 1 to 7 carbon atoms, R
' represents a linear alkoxyl group having 1 to 7 carbon atoms, respectively. ); (In the formula, R and R' each represent a linear alkyl group having 1 to 7 carbon atoms.); 7) and the compound represented by the general formula R(◇→C)toCN...
- (4) A nematic liquid crystal composition comprising a compound represented by the formula (wherein R represents a linear alkyl group having 1 to 7 carbon atoms).