JPH03186818A - liquid crystal element - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a liquid crystal element.

[Prior Art] In recent years, research on liquid crystals as light modulation elements has been very active, but the aim is to produce displays, optical shutters, etc., and most of these are TN (Twisted Nema).
tic) type display system.

On the other hand, display systems using ferroelectric liquid crystals, which are characterized by high-speed switching memory properties [N, A, C1arks et al.;
Applied Phys, Lett, 88,899 (
1980)] has been proposed.

In these liquid crystal elements, it is necessary to preferentially align the liquid crystal in one direction. Since this alignment treatment has a great influence on the quality of these liquid crystal elements, much research has been conducted on it. The alignment state of liquid crystal on the substrate surface can be broadly divided into homogeneous alignment, which is aligned parallel to the substrate surface, and homeotropic alignment, which is aligned perpendicular to the substrate surface.

In actual liquid crystals, the alignment state of the liquid crystals is changed by applying an electric field to the oriented liquid crystals, resulting in birefringence,
Light is turned on and off using dichroism.

Conventional methods for aligning liquid crystals include oblique vapor deposition of inorganic materials and rubbing of organic polymer coatings, but none of them are satisfactory. In particular, when trying to align a ferroelectric liquid crystal, it is much more oriented than a conventional nematic type, and it is difficult to achieve a uniform alignment using any method.

[Problems to be Solved by the Invention] An object of the present invention is to provide a liquid crystal element that can improve the alignment of liquid crystal, particularly ferroelectric liquid crystal, and obtain good drive characteristics by using a specific alignment layer. It is.

[Means for Solving the Problems] As a result of intensive studies to solve the above problems, the present inventors found that it is effective to use a liquid crystalline silane coupling agent as an alignment layer, and have arrived at the present invention. Ta.

That is, the present invention provides a liquid crystal element comprising a pair of opposing substrates, each having an electrode and an alignment layer for aligning liquid crystal, and a liquid crystal layer provided therebetween, in which liquid crystalline silane is used as a component forming the alignment layer. This is a liquid crystal element that uses a coupling agent.

The present invention will be explained below based on the drawings.

FIG. 1 is a cross-sectional view of the liquid crystal element of the present invention, in which 1.2 is a substrate, 3.4 is an electrode, 7 and 8 are alignment layers made of a liquid crystalline silane coupling agent, 9 is a liquid crystal layer, and 10 is a spacer. 1
1.12 is a polarizing plate. FIG. 2 is a cross-sectional view showing another embodiment of the present invention, where 5.6 is an inorganic oxide film or an organic polymer film.

As the substrate, glass, a synthetic resin film such as polyester, etc. can be used.

For the electrodes provided on this substrate, known indium tin oxide (ITO) is used, for example, and is formed on a substrate such as glass by vapor deposition, sputtering, or the like. If necessary, a blocking layer of 5iOz or the like may be provided between the glass substrate and the electrode in order to prevent alkali ions from entering from the glass substrate. Further, the electrode thus provided can be formed into a desired shape by etching.

Next, an alignment layer is formed on this electrode. Materials for the alignment film corresponding to 5.6 in Figure 2 include organic polymer materials such as polyimide, polyvinyl alcohol (PVA), polyamide, polyvinylidene fluoride (PVDF), silane coupling agents, and oxidized materials such as SiO. Vapor deposition of materials is suitable.

The silane coupling agent used as a component for forming the alignment layer in the present invention is, for example, the following general formula (I) and (n
) It is a silane coupling agent with liquid crystallinity shown by the following formulas.

(RI0)3si(CH2) ll NCO-R2-
M (I) (RI O)35t-CH2CH2R
2M (II) (In the formula, RI is a lower alkyl group, n is an integer from 1 to G, R2 is a spacer group, and M is a mesogenic group.) R2 represents a so-called spacer, that is, a group forming a certain distance. .

Examples of suitable groups R2 (spacer groups) include -CH2-ICH2+2, ICHz+s, Icn2+4
Icn2+s ICH2+64CH2+y,
Icnz+s ICHz+94CH2+ 10%
-+CH2+ ++, -CH2-()(CH2+ 3,
CH2 ICH2 +CH2 -C)+2 GCH2 CH2 -□□□CH2chi4, CH2-斡CH2chiro, +3
En CH2+ 3.4cu2+3 sail CH2) 4+3 old CH
2+ 6, -CI2 NH CH2+2, -N(CH3
)4011z + 2,'j-3NH-ECHz +
2 or +sN-GHz+2, etc.

CH3, in the above formula, R3 is C1-CI2-alkyl group, 01-CI2 alkoxy group, C1-CI2-alkoxycarbonyl group, CI
-C12 alkanoyloxy group, hydrogen, fluorine atom, chlorine atom, cyano group, 4-cyanophenyl group or nitro group, and R4 represents a C1-CI2-alkyl group.

These liquid crystalline silane coupling agents can be obtained according to the following reaction formula.

First, general formula (1) is obtained by heating and reacting isocyanate alkyltrialkoxysilane (III) and alcohol compound (IV) in a solvent such as toluene or tetrahydrofuran.

General formula (n) can be obtained from a trialkoxysilane (V) and an ethylene compound (Vr) by a known hydrosilation reaction. The reaction is carried out in a suitable organic solvent such as benzene, toluene, tetrahydrofuran, etc. from room temperature to 2.
Within a temperature range of about 00°C, a known hydrosilation catalyst,
For example, the reaction is carried out in the presence of a chloroplatinic acid catalyst for 10 minutes to 100 hours. The concentration of the catalyst used is 0 relative to the trialkoxysilane raw material.
．． It is used in an amount within the range of 0.001% to 1%.

(R1O)3St (CHz). NCO(1) +
HO-R2-M(IV)→(RI 0) 3 Sl
(CH2). N C0-R2-)I(1)(
RI O)3 SIR(V) +CH2-CB-R2-
M(Vl) −=(RI O) 3 SI −CH2
CH2-R2-M(I+) Specific examples of liquid crystalline silane coupling agents are listed below. Note that in the following, * is an asymmetric carbon atom ■ (RI 0)3si (C1+2) OR2 (I) ■ (RI 0)35iCH2CH2-R2 H (n) 1 A known liquid crystal material used in the liquid crystal element of the present invention For example, ferroelectric liquid crystals include Fu-SI 1011.1013.1014.1015 made by Chisso, ZLI-3234, 3489, 3654 made by Merck & Co.
etc. Cholera exhibits a bachiral smectic phase.

Light modulation in a liquid crystal element using ferroelectric liquid crystal can be performed as follows.

When an electric field is applied to liquid crystal molecules that are homogeneously aligned with respect to the substrate using electrodes that sandwich the liquid crystal layer, the liquid crystal molecules change their orientation within the plane relative to the direction of the electric field due to the action of spontaneous polarization and the electric field (Figure 3). ).

3 Therefore, by using birefringence or dichroism, light can be turned on.
, OFF, that is, optical modulation becomes possible. However, at this time, the thickness of the liquid crystal layer needs to be so thin that the helix of the liquid crystal disappears.

Now, when carrying out such light modulation, the liquid crystal must be aligned uniformly in order to increase the contrast. The structure of the cell is shown in FIG. 1.2, and alignment of the liquid crystal is performed by an alignment film layer.

Ferroelectric liquid crystals are more difficult to align than nematic type liquid crystals, but in the first invention, good alignment is obtained by using a liquid crystalline silane coupling agent as a component for forming an alignment layer.

The reason why an alignment film made of a liquid crystalline silane coupling agent exhibits good alignment is not clear, but it is thought to be due to the interaction between the mesogenic groups in the silane coupling agent and the liquid crystal material.

In another embodiment of the present invention, good alignment is obtained by sequentially laminating an inorganic oxide film or an organic polymer film and a thin film made of a liquid crystalline silane coupling agent as an alignment layer. At this time, the inorganic oxide film or organic polymer film is treated by oblique vapor deposition or rubbing, which has the effect of orienting the mesogenic groups of the liquid crystalline silane coupling agent laminated thereon. Therefore, the liquid crystal can be oriented by the mesogenic groups of the oriented liquid crystalline silane coupling agent.

To form these liquid crystalline silane coupling agent layers on substrates, inorganic oxide films, or organic polymer films, these liquid crystalline silane coupling agents are dissolved in a solvent such as 1,2-dichloroethane, toluene, or tetrahydrofuran. death,
It is applied onto a substrate, an inorganic oxide film, or an organic polymer film by spin coating, dipping, plate coating, roll coating, screen printing, flexographic printing, etc., heated to 80 to 120°C, and then unreacted liquid crystal The silane coupling agent is washed with the above solvent and dried.

5. The thickness of the laminated alignment layers must be such that the electric field applied to the liquid crystal layer is not greatly attenuated, and preferably the total thickness is 100 OX or less.

[Example] The present invention will be explained below with reference to Examples, but the present invention is not limited only to these Examples.

Production Example 1 Production of liquid crystalline silane coupling agent represented by general formula (1) (CzHsO)3si(C)+2)3NCO(0
112) 60 [R1 in general formula (1) R2-iCH2+6, -C2H5 -3 Compound No., S-111,4-(6-Hydroxyhexyloxy)benzoic acid-4°-hexyloxyphenyl ester 2 .07 g (0,005 mol) and 1.48 g (o, oo
Dissolve e mole) in 100 + nl of toluene and 20 molar under reflux.
Time reacted. After the reaction, toluene was distilled off, and the resulting crude product was recrystallized from hexane to obtain 2.24 g of the target product.

Clearing point: 82.0°C Elemental analysis C (%) H (%) N (%) Actual value Calculated value 83.41 B3.51 8.48 8.38 2.10 2.12 The structure of this substance absorbs infrared rays Confirmed by spectrum. A diagram of this infrared absorption spectrum is shown in FIG.

Example 1 Transparent substrate: Glass plate (thickness: 1.1 om) Transparent electrode: ITO (thickness: 500 mm, butter coating after vapor deposition) Alignment film: Liquid crystalline silane coupling of Production Example 1 The agent was adjusted to lvt% with toluene, and a film was formed by dipping. After heat treatment at 100°C for 30 minutes, the surface was washed with toluene and dried at 00°C for 1 hour.

Spacer...5P-202 made by Building Block Foin Chemical
(Average particle size 7.0 μml) Liquid crystal: Nematic liquid crystal ZLI-1132 manufactured by Merck & Co.
Sealant: Photorec A- manufactured by Blocks Fine Chemicals
704 (Ultraviolet curable type) A liquid crystal element was prepared using the above materials as shown in FIG.

The liquid crystal device produced in this manner exhibited extremely uniform homeotropic alignment.

Example 2 Transparent substrate...Glass plate (thickness 1.1ni) Transparent electrode/
...ITO (thickness 500λ, buttering after vapor deposition) Orientation layer (transparent electrode side) Rubbing treatment was performed twice.

Alignment film (liquid crystal layer side): An alignment layer was prepared using the liquid crystalline silane coupling agent of Production Example 1 in the same manner as in Example 1.

Spacer...5P-202 made by Building Block Foin Chemical
(Average particle size 1.8 μm) Liquid crystal: Ferroelectric liquid crystal C8-1014 manufactured by Chisso Sealant: Photorec A-704 manufactured by Block Fine Chemicals
(Ultraviolet curing type) A liquid crystal element was prepared by laminating the above materials as shown in FIG. Next, the ferroelectric liquid crystal was oriented by heating to 85° C. and then slowly cooling.

The liquid crystal element prepared in this way was examined under a polarizing microscope for 40 minutes.
When driven by applying a voltage of 10Vpp between the electrodes while maintaining the temperature at °C, the response speed was 150μ5ec (0 → 90%)
, and the contrast ratio was 47.

It also had good memory properties.

Comparative Example 1 A liquid crystal device was produced and driven in the same manner as in Example 2 except that only polyvinyl alcohol was used as one alignment layer. The response speed was 150μ5ec (0→9%) and the contrast ratio was 8. Moreover, no memory properties were obtained.

[Effects of the Invention] According to the present invention, uniform alignment is possible in the liquid crystal layer, and a liquid crystal element having a high contrast ratio during driving and stable memory performance can be obtained.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a liquid crystal element showing an example of the present invention, Figure 2 is a cross-sectional view of a liquid crystal element showing another example of the present invention, and Figure 3 is a diagram showing liquid crystal molecules when an electric field is applied to the liquid crystal layer. FIG. 4 is an infrared absorption spectrum diagram of the liquid crystalline silane coupling agent obtained in Production Example 1. In the figure, 1 and 2 are substrates, 3 and 4 are electrodes, 5.8.7.8 are alignment layers, and 9 is a liquid crystal layer. 0

Claims (2)

[Claims] (1) In a liquid crystal element that has an electrode and an alignment layer for aligning liquid crystal on the inside of a pair of opposing substrates, and a liquid crystal layer is provided between them, liquid crystalline silane coupling is used as a component forming the alignment layer. A liquid crystal element characterized by using an agent. (2) The liquid crystal element according to claim (1), wherein the liquid crystalline silane coupling agent is formed as an alignment layer on an inorganic oxide film or an organic polymer film.