JPS5865783A - Liquid crystal material - Google Patents

Abstract

PURPOSE:A liquid crystal composition suitable for a positive guest-host color liquid crystal display device, prepd. by mixing a cyclohexanecarboxylate deriv., a 4-cyclohexane biphenyl deriv. and a phenylcyclohexane deriv. CONSTITUTION:The liquid crystal composition is prepd. by mixing a cyclohexanecarboxylate deriv. of formulaI[wherein R1 is 15C or lower alkyl, alkoxy or cyano; A is a group of formula II, III, IV, V or VI (wherein R2-R6 are each 10C or lower alkyl, alkoxy, nitro or cyano)], about 3-20wt%, based on the entire composition, 4-cyclohexanebiphenyl deriv. of formula VII (wherein R7 is 10C or lower alkyl, alkoxy, nitro or cyano; B is a group of formula VIII or R7), and about 0.5-20wt%, based on the entire composition, phenylcyclohexane deriv. of formula IX (wherein R9 and R10 are each 10C or lower alkyl, alkoxy or cyano).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention first describes the basic operation of a positive type guest-host color liquid crystal display with respect to liquid crystal materials suitable for use in the positive type guest-host color liquid crystal display.

Figure 1 (a), ←) is a side view of the main parts of this type of color liquid crystal display device for explaining the basic operation.
(b) is a diagram corresponding to the time when no voltage is applied, and (b) is a diagram corresponding to the time when voltage is applied. The Jinnotane color liquid crystal display device consists of 4 [0.62 sheets of insulating substrates made of glass or the like having a transparent conductor 11Q made of indium oxide, etc., on the surface thereof, and facing each other at a constant interval. The dielectric anisotropy of the host is negative! A liquid crystal substance made by adding a guest dichroic dye ■ to Tituta liquid crystal 0 is sealed, and a polarizing plate 0 is placed on one insulating substrate surface to further increase the display contrast, resulting in a nine structure. and its operation is in the following seconds. That is, 11g
As shown in Figure 1 (a), when no voltage is applied between the transparent electrode and @, the nematic liquid crystal molecules and dichroic dye molecules are aligned directly on the insulating substrate, and the light does not penetrate. ◇As shown in Figure 1 (b), when a voltage is applied between the transparent electrode [Co., Ltd.] and The dye molecules are aligned horizontally with the insulating substrate, and light is absorbed in this portion, resulting in color display using the dichroic dye. In addition,
In Figure 'll11, ■ is a power supply.

Positive type guest-host color liquid crystal displays developed from the basic operation and structure on paper include phase change layer, DaM type (dynamic scattering liquid crystal, etc.).The phase change layer consists of nematic liquid crystal, a small amount of cholesteric liquid crystal, It has a structure in which a liquid crystal substance made by adding an optically active substance such as chiral nematic liquid crystal and a dichroic dye is sealed between two insulating substrates such as nine glass with transparent electrodes such as indium oxide formed on the surface. By applying a voltage between the transparent electrodes, the liquid crystal molecules and dichroic dye molecules are slightly twisted, forming a helical structure, which absorbs light and performs color display.

D8Mfi is characterized by using a liquid crystal material made by adding a small amount of ionic material to a nematic liquid crystal, so when a voltage is applied between the transparent electrodes, the flow of ions in the liquid crystal material causes the liquid crystal molecules to change. Display is performed by utilizing a phenomenon in which the alignment state is partially disturbed and incident light is scattered.

As described in the paper, there are various positive type guest-host color liquid crystal display devices, but in any type, the characteristics of the nematic liquid crystal serving as the host are important, and the following are required.

(1) Must be a liquid crystal at room temperature; (2) Must have as large an absolute value of dielectric anisotropy as possible to reduce driving voltage; (3) Must have low viscosity to improve responsiveness during erasing. However, for example, in phase transition mc, display contrast increases by adding an appropriate amount of optically active substance, but on the other hand, driving voltage also increases. In order to lower the driving voltage, it is necessary for the nematic liquid crystal to have a large absolute value of dielectric anisotropy, but a nematic liquid crystal that satisfies this requirement has not been obtained so far. In addition, in order to improve display contrast in D8Mall, it is necessary to select a liquid crystal that does not cause light scattering as much as possible when no voltage is applied, that is, has good orientation of liquid crystal molecules. was not obtained.

The present invention was made in view of the drawback KfIi on paper, and its purpose is to provide a positive type guest-host color liquid crystal display with good display contrast and good display rise and fall without using a polarizing plate. The goal is to provide the following.

The present invention is characterized by using a cyclohexanecarboxylic acid ester haze conductor having a structural formula of R1-@-COO-A and a cyclohexanecarboxylic acid ester haze conductor having a structural formula of 4- This is because a mixture consisting of 114 cyclohexane piphenyl units and the structural formula was used.

Cyclohexane carboxylic acid ester derivative is 20CK
Although it has a low viscosity of 200p, it has poor orientation (order parameter) for dyes, and if the content is too large, it will be colored when no voltage is applied.

Furthermore, the 4-cyclohexane biphenyl derivative has a high viscosity and a narrow liquid crystal temperature range, and if the content is too large, it becomes a solid crystal at room temperature) and liquid crystal properties cannot be obtained. Furthermore, the trout conductor used in 7EL cyclo has a good order parameter, but when used alone, the dielectric anisotropy is negative and it cannot be used as a liquid crystal.
There is a drawback that properties that can be used practically at room temperature cannot be obtained. Taking these things into consideration, as a result of various studies, the content of the 4-cyclohexane biphenyl derivative was determined to be 5 to 20 Wt.
-, the content of phenylcyclohexane derivative is a, 5
It has been found that a value of ~2 OWt is appropriate. 4
-Content of cyclohexane biphenyl a conductor is 5 wt
%, the resulting color liquid crystal display device will be colored even when no voltage is applied. If the amount is more than 20wt, the viscosity of the liquid crystal substance will become high and the liquid crystal temperature range will become extremely narrow. If the content of the phenylschiff tetrahexane derivative is less than αS Wt-, the order parameters will be poor and the display will be colored even when no voltage is applied, resulting in poor display contrast. The water runs out.

The present invention will now be described in detail based on Examples. Example 1 An indium oxide transparent electrode is formed in a predetermined shape on a glass substrate, and a silane coupling agent is further applied and a vertical alignment process is performed. Next, two glass substrates are pressed against each other with a gap of 15 μm maintained, thereby producing a liquid crystal cell. Next, a liquid crystal substance having the composition shown below was injected into a liquid crystal cell and sealed to produce a color liquid crystal display device.

Cyclohexanecarboxylic acid ester-conductor 84 w
t%C,H,-@-coo-@-oc, H,1o w
t%C,H,÷cooshaoc, )%2
2 Wt-C,H,-■-coo-@-oc, H,1
7WtnC,n, -@-coo-@, -oc, H,
22wt-C, H, ningoo-@@-c, Hq
1 s wts4-cyclohexane biphenyl 11
11 bodies 1owtl”sHy H00HC
IHtt Blt@C,)! ,,%C,
H, 2wt% phenycyclohexane derivative 5wt1C5
H, (gun ■ → C, H.

Optically active substance α55wt * Cholesteryl nonanoate ionic substance αoswt * Tetrabutylammonium puminum dichroic dye α6 wt - The obtained color liquid crystal display device has an extremely low degree of coloring when no voltage is applied and has good display contrast. It was something.

! I! Example 2 A liquid crystal cell was prepared by maintaining a distance of 10 μm between two glass substrates, and a color liquid crystal display device was prepared in the same manner as in Example 1 using a liquid crystal material having the following composition.

Schiff tetrahexane carboxylic acid ester dielectric 175
wt%CsH,-@-coo-@and--QC,H,a7
5wt%C4H@C5Hq in No. C00
22Wt Chi C4 (needle C0) 0 → Cs kLr
15wt5C,H, -@-C00shaQC,H
, 15Wt Chi C, H, 4coo-cue-ocut, H・2
．． swt%N CN c, u, 1-@-coo-qtsuco-@-CaHo
2.5wt5N CN (4Hll-e-cOOmin OCo No.C, Hu 25
wt%N CN Cs Ht -@-COOYellowOCoCs Hu
2.5Wt*N CN C,H,-@-COOiOCOsha CI H,z,swt
Fight N CN C5Hn-@-COO threat-CO combination C,H,,zswts
CN CN 4-cyclohexane biphenyl 1li1 body 1
5Wt*C,H,,-@@-coo bone oc,)(,2,
swt%CN C:N CIHII-@@-COO-i needle C,) (, 2,5Wt
4N CN c, H, → anti-α turbidity ic, H Tsuru 6wt
俤c、u、4■心XCN 2wt1
Phenylcyclohexane s conductor 1owtsC,H,-@
@-0C4Hs Optically active substance nswt-Cholesteryl nonanoate ionic substance a, yswt@The obtained color liquid crystal display device had a good lWI-like display contrast with that of Example 1.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional side view of the main part of a positive type guest-host color liquid crystal display device, in which (a) shows the state when no voltage is applied, and (b) shows the state when voltage is applied. [Phase] , 0: Transparent electrode [Co., Ltd.], O: Insulating substrate ■
: Nematic liquid crystal ■ : Dichroic dye ■ : Light plate
■；Power supply patent owner Alps Electric Co., Ltd.

Claims (2)

[Claims] (1) A cyclohexanecarboxylic acid ester derivative whose structural formula is represented by R1-@-c00-A, a 4-schiftetrahexane biphenyl derivative whose structural formula is tabbed as 1. A liquid crystal substance with negative dielectric anisotropy, characterized in that it consists of a mixture of the following phenylcyclohexane derivatives. (2) The content of the 4-1' p-hexane biphenyl trout conductor is 3 to 2 Q wt %, and the content of the phenylcyclohexane derivative is 05 to 20 Wtn. liquid crystal substance O