JPH01240591A - Liquid crystal composition - Google Patents

Abstract

PURPOSE:To obtain a liquid crystal composition effective for providing elements having excellent electron optical characteristics, having excellent sharpness, high-speed response and a sufficiently wide nematic liquid crystal temperature, containing specific six kinds of liquid crystal compounds. CONSTITUTION:The aimed liquid crystal compound containing (A) about 1-70wt.% one or more compounds shown by formula I (R1 is 1-10C alkenyl), (B) about 1-50wt.% one or more compounds shown by formula II (R2 is 1-10C alkyl), (C) about 1-50wt.% one or more compounds shown by formula III (R3 and R4 are 1-10C alkyl), (D) about 1-50wt.% one or more compounds shown by formula IV (R5 is 1-10C alkenyl; R6 is 1-10C alkyl), (E) about 1-50wt.% one or more compounds shown by formula V (R7 and R8 are 1-10C alkyl) and (F) about 1-50wt.% one or more compounds shown by formula VI (R9 and R10 are 1-10C alkyl) to give the aimed liquid crystal composition.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid crystal composition useful for use in electro-optical elements.

[Conventional technology]

Conventional electro-optical elements using twisted nematic mode (hereinafter abbreviated as TN mode in the text) sandwich a nematic liquid crystal having positive dielectric anisotropy between two opposing electrode substrates, and align it. 9 defined by processing
It has a spiral structure with a 0" twist, and a polarizing plate is placed on the outside of the picture electrode base.

FIG. 4 shows the results of measuring the electro-optic characteristics of an electro-optic element using the conventional TN mode.

However, in recent years, the requirements for the electro-optical characteristics of electro-optical elements, especially the time-division drive characteristics, have become stricter, and the conventional T
In the N mode, a state has been reached where the required characteristics cannot be satisfied.

Therefore, by adding an optically active substance to nematic liquid crystal, a mode (hereinafter referred to as S T N
A technique for improving time-division drive characteristics using a mode (abbreviated as "mode") is disclosed in, for example, Japanese Patent Laid-Open No. 60-50511.

Furthermore, the new twisted nematic mode (hereinafter abbreviated as NTN mode in the main text) eliminates the discoloration of the appearance of electro-optic elements that is characteristic of the STN mode, and as in JP-A-62-121701, a pair of By providing at least one layer of optically anisotropic material between the polarizing plates,
It is now possible to display white on a black background or black on a white background.

The advantage of these STN, . . . NTN modes over the conventional TN mode is that the threshold characteristics of the electro-optic characteristics are steep, so that a large display capacity can be achieved by time-division driving.

[Problem to be solved by the invention]

However, with conventional electro-optical elements using STN and NTN modes, sufficient response speed cannot be obtained.

For example, in the case of the NTN mode, the response speed is 340 m5 including the rising response and the falling response, and the response is too slow for displaying moving images on a TV or the like, causing images to flow.

On the other hand, the number of divisions is 20 when the transmittance of this element is 50% when it is on.
If time-divisional driving of 0 is performed, a display contrast of 1=14 is obtained, but this is still insufficient for displaying television images.

Therefore, the present invention aims to solve these problems.
The purpose is to provide a liquid crystal composition that is effective in obtaining an electro-optical element with excellent electro-optic properties and has excellent steepness and high-speed response.

[Means to solve the problem]

The present invention provides a liquid crystal composition that satisfies the above conditions based on the above object, - Formula % Formula % (1) Ro is an alkenyl group of 1 to 10 R2 is an alkyl group of 1 to 10 R3 is 1 -10 alkyl groups R4 are 1-10 alkyl groups R6 are 1-10 alkenyl groups R6 are 1-10 alkyl groups R9 are 1-10 alkyl groups R8 are 1-10 alkyl groups R7 is 1-10 The alkyl group R8° is represented by an alkyl group of I to 10.

〔Example〕

Hereinafter, the present invention will be described in detail based on examples.

The characteristics of the liquid crystal composition were measured as follows. 1st
The measurement system for electro-optical properties is shown in the figure.Measurement cell 4 has a transparent electrode attached to one side of a glass substrate by vapor deposition or sputtering, and then that surface is covered with an organic thin film and subjected to an alignment treatment. The nylon film 1, which also serves as and S.T.
This is an N mode cell. On the other hand, cells in NTN mode are
Furthermore, at least one optically anisotropic material is provided between the polarizing plates. In the text, the distance between the glass substrates (ie, the thickness of the liquid crystal layer) is abbreviated as cell thickness. A light beam emitted from a white light source 1 passes through a lens system 3 and enters a cell 4 from a perpendicular direction, and the intensity of the transmitted light is measured by a detector provided at the rear. At this time, an alternating rectangular voltage having a frequency of 1 kilohertz and having an arbitrary effective value voltage is applied to the cell 4 by the driving circuit 5. Figures 2 and 3 show voltage-transmittance curves obtained by measuring a liquid crystal cell using the measurement system shown in Figure 1. FIG. 2 shows the measurement results of the electro-optical characteristics of the electro-optical element using the NTN mode, and FIG. 3 shows the measurement results using the STN mode. In the figure, the transmittance represents the amount of light transmitted through two polarizing plates bonded together with their polarization axes aligned as 100%. In this voltage-transmittance curve, the transmittance T0 at the darkest time and the transmittance T0 at the brightest time
1°. Toji, T.I.G. -To and T+ from the darkest side, with a sufficient distance between T0 and T0. , T2゜,...T,. l'r" is 10°. Gradually increase the voltage and the voltage when the transmittance is T1° is the optical threshold voltage vth. Further increase the voltage and the voltage when the transmittance is T9° is the optical threshold voltage vth. At this time, the rise (ie, steepness) of the voltage-transmittance curve near the optical threshold voltage is determined as the following formula β.

The response speed is measured at an applied voltage such that the rising response time (expressed as T07) and the falling response time (expressed as T or r) are almost equal, and the average value T of To, 1 and Toff (= To , + Tott/2) in milliseconds.

Further, for stability of orientation, the nematic liquid crystal composition of the present invention to which an optically active substance was added was sealed in a cell. The amount of the optically active substance added was determined from the formula below.

θ C÷□ Show power.

The stability of the nematic liquid crystal phase was shown as high-temperature liquid crystallinity and low-temperature liquid crystallinity when sealed in a cell.

Assuming the chronological temperature is 20°C, 50° is 30°C higher than that.
Whether the nematic phase is stable at C is referred to as high-temperature liquid crystallinity, and on the other hand, whether the nematic phase is stable at 10-10°C, which is 30°C lower than 20°C, is referred to as low-temperature liquid crystallinity.

The measurement temperature was 25°C in all cases.

Further, the measurement was performed using the NTN mode under the conditions that the twist angle of the cell was 210° to the left, and the product Δnd of the cell thickness d and the refractive index anisotropy Δn of the liquid crystal was about 0.9. Note that the effects of the present invention are not limited to these conditions and modes, and similar effects can be obtained under other conditions and modes (TN, STN mode, etc.).

[Example-1] Table 1 shows the composition and properties of Example-1 according to the present invention. However, in this example, as compound (6) -format R, -0
-C=C-C3c-0-R,. (In the formula, R7 and R1° represent a straight-chain alkyl group having 1 to 10 carbon atoms) (hereinafter abbreviated as BTT in the text).
It is characterized by containing heavy ■%.

Further, the characteristics of Conventional Example-1 are shown in Table 2.

While the response speed T in Conventional Example-1 is 132 milliseconds, in Example-1 it is 52 milliseconds, which is a significant improvement of 61%.

Further, the β value representing steepness is 1°090 in Conventional Example-1, whereas it is improved to 1.084 in Example-1.

Regarding the optical threshold voltage, although it is higher in Example-1 than in Conventional Example-1, it does not pose any particular problem because it is well within the tolerance range that does not cause any problems in driving.

Furthermore, Example-1 has high-temperature liquid crystallinity at 50°C and low-temperature liquid crystallinity at -10°C, is sufficiently stable, and has a sufficiently wide nematic liquid crystal temperature range to be used as a normal display.

As described above, this example has a very fast response speed and excellent steepness, and is a liquid crystal composition useful for electro-optical elements.

[Example-2] Table 1 shows the composition and properties of Example-2 according to the present invention. However, in this example, 10% by weight of BTT and the compound (2
), a compound represented by the formula R2-■-〇-NC3 (in the formula, R2 represents a straight-chain alkyl group having 1 to 10 carbon atoms) (hereinafter abbreviated as 11133 in the text) is 19
It is characterized by containing a heavy weight of 1%.

Further, the characteristics of Conventional Example-1 are shown in Table 2.

While T is 132 milliseconds in Conventional Example-1, T is significantly increased to 50 milliseconds in Example-2.

Further, the β value of Conventional Example-1 is 1.090, whereas that of Example-2 is 1.087, which is slightly improved.

Regarding the optical threshold voltage, Example-2 is the conventional example-
It is 2.08V, which is almost the same as 1, and is within a completely acceptable range.

Furthermore, the nematic liquid crystal temperature range is sufficiently wide.

As described above, this example is a useful liquid crystal composition similar to Example-1, and is even more superior to Example-1 in terms of optical threshold voltage in particular.

[Example-3] Table 1 shows the composition and properties of Example-3 according to the present invention. However, this example is characterized by containing 10% by weight of 13TT and 22% by weight of HBS.

Further, the characteristics of Conventional Example-1 are shown in Table 2.

While the β value of Conventional Example-1 is 1,090, the β value of Example-3 is significantly improved to 1.080.

Furthermore, the optical threshold voltage of Conventional Example-1 is 2.07 V, whereas that of Example-3 is very low at 1.90.

Regarding T, while the conventional example-1 was 132 milliseconds, the Example-3 was improved to 60 milliseconds, which was half that.

Furthermore, it has a sufficient nematic liquid crystal temperature range, causing no problems.

Table 1 As shown above, this example is a very useful liquid crystal composition, similar to Examples 1 and 2, and is particularly superior to Examples 2 in terms of contrast, sharpness, and optical threshold voltage. There is.

Table 2 [Effects of the Invention] As described above, the liquid crystal composition of the present invention has superior steepness and extremely fast response speed compared to conventional compositions, and also has a sufficient nematic liquid crystal temperature range. It is extensive and very useful.

Applications of electro-optical elements using the liquid crystal composition of the present invention include televisions, computer terminals, word processors, and the like.

[Brief explanation of the drawing]

FIG. 1 is a hardware diagram showing a measuring device used in an embodiment of the present invention. FIG. 2 is a curve diagram showing the voltage-transmittance change in NTN mode generally obtained using the measuring device shown in FIG. FIG. 3 is a curve diagram showing a change in voltage-transmittance in STN mode, which is generally obtained using the measuring device shown in FIG. FIG. 4 is a curve diagram showing changes in voltage-transmittance in STN mode generally obtained using the measuring device shown in FIG. 1. 1...Light source 2...Light ray 3...Lens and filter system 4...
Cell 5... Light receiving part (photomultiplier tube) Deaf 2 Figure off V3 Not pictured

Claims (1)

[Claims] 1) General formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (1) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (2) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (3) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (4) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (5) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (6) Each group represented by (1), (2 ), (3), (4), (5
), (6) A liquid crystal composition comprising at least one component of each of the compounds of (6) and (6). However, R_1 is an alkenyl group of 1 to 10 R_2 is an alkyl group of 1 to 10 R_3 is an alkyl group of 1 to 10 R_4 is an alkyl group of 1 to 10 R_5 is an alkenyl group of 1 to 10 R_6 is an alkyl group of 1 to 10 R_7 is an alkyl group of 1 to 10 R_8 is an alkyl group of 1 to 10 R_9 is an alkyl group of 1 to 10 R_1_0 is an alkyl group of 1 to 10. 2) The proportion of compound (1) is 1 to 70% by weight. The proportion of compound (2) is 1 to 50% by weight. The proportion of compound (3) is 1 to 50% by weight. The proportion of compound (4) is 1 to 50% by weight. 2. The liquid crystal composition according to claim 1, wherein the proportion of compound (5) is 1 to 50% by weight, and the proportion of compound (6) is 1 to 50% by weight.