JPH0574639B2 - - Google Patents

Description

[Detailed description of the invention]

[Field of Application] The present invention relates to a liquid crystal composition used in a liquid crystal display element, and particularly to a liquid crystal composition with improved response speed. [Prior art and problems] Liquid crystal display elements have characteristics such as low voltage drive, low power consumption, and thin shape, and are used for watches, calculators, electronic games, small televisions, vehicle instruments, and terminal equipment. Its uses are expanding more and more. However, on the other hand, there are problems such as slow response speed, narrow viewing angle, lack of sharp optical characteristics with respect to applied electric field, limited operating temperature range, and large temperature dependence of various characteristics of display elements. It has
If these problems are resolved, it is expected that its applications will further expand. However, it is currently difficult to find a single liquid crystal compound that can solve all of these problems at once, and various liquid crystal compounds are mixed depending on the driving method etc. to find the characteristics most suitable for the purpose. At present, liquid crystal compositions that have the same properties have been obtained and put into practical use. Among the above-mentioned problems, improvement in response speed is particularly required in relation to fields of application such as vehicle instruments and large television display devices. As a means to improve the response speed, improvements can be made in two ways: increasing the refractive index anisotropy Δn of the liquid crystal composition to lower the viscosity of the liquid crystal composition (the larger Δn, the smaller the cell layer). It is being done. Currently, liquid crystal materials commonly used for such purposes include those mainly based on cyanophenylcyclohexane and phenylcyclohexyl ether. However, phenylcyclohexyl ether type has a negative dielectric constant (-0.3 to -0.5), so if it is used in large quantities, the operating voltage of the display element will increase, making it undesirable. In a system in which an ether type material is added, the viscosity is small, but Δn is also small. Therefore, it is necessary to increase the cell thickness, which tends to slow down the response speed. [Object of the Invention] In view of the above circumstances, the present inventors have searched for a liquid crystal composition with even better response characteristics, and as a result, have found that
We have arrived at the present invention. [Structure of the Invention] That is, the present invention is a liquid crystal composition comprising two or more components, which is characterized by containing at least the following two components A and B2. A component: general formula

A compound represented by: (R ₁ represents an alkyl group having 1 to 8 carbon atoms). Component B: one or more compounds selected from the group of compounds represented by the following general formula.

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[Effect]

The response speed of a liquid crystal display element obtained using the liquid crystal composition of the present invention is higher than that of a conventional liquid crystal composition, that is, a cyanophenylcyclohexane liquid crystal, or a liquid crystal composition using a combination thereof with a phenylcyclohexyl ether liquid crystal. This is a significant improvement compared to conventional display elements. This is because the liquid crystal composition of the present invention has a low viscosity and a large Δn. Furthermore, the liquid crystal composition of the present invention also improves viewing angle characteristics and temperature dependence characteristics of threshold voltage and response speed. [Example] The liquid crystal composition of the present invention will be explained in more detail with reference to Examples below. In addition, in the examples, electro-optic effect (threshold voltage
A 32 Hz AC power supply was used to measure the V ₁₀ and response speed, and a voltage twice the V ₁₀ of each sample was applied to measure the response speed. The viewing angle characteristic (β) is defined by the following equation (the closer the value is to 1, the better the viewing angle characteristic). V ₁₀ at β = θ = 0° / V _{10 at θ = 40° V 10 =} Threshold voltage (voltage at which the transmittance becomes 10%) θ = Viewing angle (perpendicular to the display surface is assumed to be 0°) Example 1 As component A

[Table] 〓
As component B

【table】
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A liquid crystal composition was prepared, its properties as a liquid crystal were measured, and a TN cell containing it was made and its display properties were measured. The results are shown in Table 1 together with the results of other Examples. In the same manner, liquid crystal compositions of Examples 2 to 6 having the compositions shown below were prepared and their various properties were measured. The results are also shown in Table 1. Example 2 10% of the composition A of Example 1 as the A component As the B component

【table】
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Example 3 Composition A of Example 1 as A component 30% As B component

【table】
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Example 4 20% composition A of Example 1 as A component; as B component

【table】
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Example 5 20% of the composition A of Example 1 as the A component As the B component

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Example 6 20% of the composition A of Example 1 as the A component As the B component

【table】
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【table】 Example 11 As component A

[ka] As component B

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A composition consisting of: The N-1 point of this thing is
The viscosity at 49.8°C and 20°C was 17.7 cP. Comparative Example Instead of component A in Example 11,

The liquid crystal composition prepared in the same manner as in Example 11 except for using [Chemical Formula] had an N-1 point of 47.1°C and a viscosity of 20.1 cP at 20°C.

Claims (1)

[Scope of Claims] 1. A liquid crystal composition comprising at least two components, characterized in that it contains at least the following two components. Component A: A compound represented by the general formula: (In the above formula, R ₁ represents an alkyl group having 1 to 8 carbon atoms.) Component B: One or more compounds selected from the group of compounds represented by the following general formula. [C] [C] [C] [C] [C] [C] [C] [C] [C] [C] [C] [C] [C] [C] [C] [C] [C] [C] ₂ represents an alkyl group or alkoxy group having 1 to 8 carbon atoms, and R ₃ represents an alkyl group having 1 to 8 carbon atoms;
8 alkoxy group, and R ₄ represents an alkyl group having 1 to 8 carbon atoms. However, in equation (B5)
R ₄ is not a pentyl group. ). 2 7 to 60% (weight) of A component, 93 to 30% of B component
% (weight) of claim 1 containing
The liquid crystal composition described in .