JPH0372317A - Element and device for liquid crystal display - Google Patents

Abstract

PURPOSE:To obtain the liquid crystal display element of low power consumption which has a superior contrast by providing such a particle size distribution that the number of particles whose mean particle size value and particle size are specified is >=70% of the total number of liquid crystal drops. CONSTITUTION:A polymer layer 1 which contains dispersed fine drops 2 of liquid crystal is sandwiched between transparent substrates 3 and 4 which have transparent electrodes 5 and 6 and a driving power source 7 is connected to the transparent electrodes 5 and 6. The particle size distribution is so determined that the number of particles which has a mean particle size value of 3-5 mum and particle sizes of 1-7 mum is >=70% of the total number of particles. Consequently, the high-contrast, low-contrast, and superior-performance liquid crystal display element is obtained.

Description

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

More specifically, by utilizing scattering, absorption, and transmission of light by liquid crystal microdroplets, display is performed by applying or not applying various voltages to the polymer layer that disperses and holds the liquid crystal microdroplets as necessary. The present invention also relates to a liquid crystal display element or device that constitutes part or all of a display board, window, door, wall, etc. that utilizes the shutter effect.

[Conventional technology]

Conventional liquid crystal display devices often use a twisted nematic (CTN) system in which liquid crystal droplets are sandwiched between transparent substrates such as glass coated with a transparent conductive film, and a polarizing plate is attached on the outside of the substrate.

Such liquid crystal display elements require expensive polarizing plates,
In terms of performance, there were also drawbacks such as insufficient brightness and viewing angle of the device. In addition, when using a glass substrate for a large-area display element, the element is easily broken and a glass plate that is not completely flat is used to form liquid crystal droplets with fluidity. Since it is extremely difficult to sandwich the inner and outer parts with uniform thickness, unevenness in appearance or properties is likely to occur due to uneven thickness.

To solve these problems, a method has been proposed that does not require a polarizing plate and utilizes the birefringence of liquid crystal to electrically control the transparent or cloudy state. This method basically matches the ordinary refractive index of the liquid crystal molecules with the refractive index of the supporting medium, and when a voltage is applied and the orientation of the liquid crystal molecules is aligned, a transparent state is displayed, and when no voltage is applied, a transparent state is displayed. It displays the state of light scattering due to disordered orientation of liquid crystal molecules.

One of the two proposed methods is described in Applied Physics Latter, Vol. 440, No. 1, January 1982.
Vol, 40. In this method, a liquid crystal is flowed into micropores in a porous layer, and both sides of the liquid crystal are sandwiched between transparent substrates. In this case, a polarizing plate is not necessary, but since the liquid crystal is not completely enclosed in the micropores, it flows freely, resulting in uneven thickness, and it is difficult to create a thin porous body that responds at low voltage. There were some drawbacks.

Another method proposed is to disperse and hold liquid crystal microdroplets in a polymer. This is also called a capsule type liquid crystal, and because the liquid crystal particles are independently encapsulated in the polymer, they do not flow, and the AIR thickness of the liquid crystal droplet can be controlled by the coating thickness of the polymer layer. , large-screen display elements can be manufactured relatively easily.

Specifically, first, patent publication number 501631 of 1982.

The water-soluble polyvinyl alcohol described in Patent Publication No. 226322/1982 is mixed with liquid crystal as a polymer component to form an emulsion, and this is spread on a substrate and dried to obtain a polymer layer in which liquid crystal droplets are dispersed. There is a way.

Also, as another example, Patent Publication No. 2231 of 1988,
A liquid crystal component is dissolved in an uncured resin such as an epoxy resin or an acrylic ultraviolet curable resin described in U.S. Patent No. 4,688,900, etc., and liquid crystal droplets are precipitated as the curing reaction progresses. There is a way.

Alternatively, rMolecular Crystal a
nd LiquidCrystal Include
g Non1inier 0ptics 1988J
Vol.

157, pp. 427-441, there is also a method in which liquid crystal droplets are precipitated from a mixture of liquid crystals, polymers, etc. at high temperatures during the cooling process.

In addition, an improved technique developed by the present inventors, namely, using a mixture of polyvinyl alkyral and its crosslinking agent instead of the water-soluble polyvinyl alcohol used in the above method, and a polymer layer in which liquid crystal microdroplets are dispersed. There is a technique to improve the heat resistance and durability of the display element by converting it into a polyvinylalkyral crosslinked product (Patent Application No. 13 of 1999).
No. 6251).

In the above-mentioned conventional technology, the shielding effect due to light scattering and the transparency due to light transmission of such elements are utilized to obtain various display devices, windows, doors, partition walls, etc. with varying transparency. However, the size distribution state of the liquid crystal droplets and
The relationship with the driving voltage for light scattering and transparency is as follows:
The problem has not been solved yet, and the problem is that the S dynamic voltage is high or the display contrast is low.

[Problem to be solved by the invention]

The present invention provides an excellent shielding effect when no voltage is applied by controlling the size and distribution of liquid crystal droplets within a certain range in liquid crystal droplet dispersion type display elements that are conventionally known and will be further developed in the future. It is an object of the present invention to provide a liquid crystal display element and device that has excellent transparency when voltage is applied, that is, can be driven at low voltage, thus consumes low power, and has excellent contrast. be.

[Means for elucidating the issue]

That is, the present invention provides at least one dispersed liquid crystal microdroplet.
one polymer layer and two or more transparent conductive substrates sandwiching the polymer layer (however).

one of them may be opaque or reflective)
In a liquid crystal display element and device comprising: a liquid crystal droplet having an average particle size of 34 to 5. A liquid crystal display element characterized by having a particle size distribution in which the number of particles falling within the range of 1/a to 7p is 70% or more of the total number of particles; and It provides equipment. In addition, in the device and device of the present invention, in particular, the thickness of the polymer layer in which liquid crystal microdroplets are dispersed is 104 or more, and 181
The range is 1 m or less, and the number density of liquid crystal microdroplets in the polymer layer in which liquid crystal microdroplets are dispersed is set to lX10'C.
By setting the number of particles/fl13) to 2×10'' (pieces/ff13) or less, it has become possible to implement a liquid crystal display element and device with particularly excellent properties of high contrast and low power consumption.

The present invention will be explained in more detail below.

First, the basic structure of the liquid crystal display element used in the present invention will be explained with reference to FIG.

A polymer layer 1 containing dispersed liquid crystal microdroplets 2 is sandwiched between transparent substrates 3.4 having transparent electrodes 5.6, and a driving power source 7 is connected to the transparent electrodes 5.6. .

If you select a material whose ordinary refractive index is almost the same as the refractive index of the polymer, when a voltage is applied and the long axes of the liquid crystal molecules are aligned in the direction of the electric field, the difference in refractive index will disappear. In a transparent state, when the voltage is removed, the liquid crystal molecules align along the polymer wall surface, creating a refractive index difference with a portion of the polymer and scattering incident light. In order to increase the light scattering properties when no voltage is applied, it is possible to increase the thickness of the polymer layer containing the liquid crystal droplets, but in this case, the electric field strength applied to the liquid crystal droplets when a voltage is applied is weakened, making it difficult to obtain sufficient transparency. can't get it.

There is also a method of increasing the ratio of liquid crystal droplets to polymer, but there are process limitations.

In order to realize an element that achieves both high contrast and low voltage activation, the inventors of the present invention have conducted intensive studies to determine the particle size distribution of liquid crystal droplets, the thickness of the polymer layer, and the number density of liquid crystal droplets. They discovered that it is effective to keep the values within a certain range, and completed a display element that achieves both of the above performances.

That is, if the average value of the particle size of the liquid crystal droplets is in the range of 3 to 51M, and most of the particles are in the range of particle size of 111 to 7M, high light scattering properties and low voltage disintegration properties are satisfied. do.

What is the storage capacity of the polymer layer at this time?

10-18M, particle density is IXIO' ~2X
It is desirable that the number is IO' (pieces/fflm3). Within this range, it is possible to achieve perfect light scattering properties when no voltage is applied and sufficient transparency when voltage is applied, particularly when AC is applied at 50 V or less.

When the particle size of the liquid crystal droplets is small, the shape of the object is recognized through the element in the light scattering property when no voltage is applied, that is, the light scattering property decreases. Further, even when a voltage is applied, there is a problem that the film does not become sufficiently transparent.

On the other hand, if the particle diameter is too large, the shielding property among the light scattering properties when no voltage is applied is unfavorable.

Among the particle size ranges (1 to 7-) of the liquid crystal droplets, a more desirable range is 3 to 5 IIm. When liquid crystal droplets are formed using various methods, the particle size distribution tends to be monodisperse or have a certain width, but the central particle size can be adjusted by controlling the process as described below. 3~
Keep it within the range of 5IIs.

Furthermore, the particle size is 1. The object of the present invention can be achieved by controlling the number of particles with a particle size of pm or more and 7 μ or less to be 70% or more, preferably 80% or more of the total number of particles.

In addition, the thickness of the polymer layer containing liquid crystal droplets is 10 to 184 mm.
is good, and more preferably 12-15-.

If the thickness is less than 10Is, the light scattering property will be insufficient when no voltage is applied, and if it is too thick, the prescribed electric field strength for opening the liquid crystal will not be obtained, resulting in insufficient transparency when voltage is applied. Or you can't get it! ! ! The voltage required for movement increases. A high drive voltage means high power consumption.

The number density of liquid crystal droplets with the above particle size in the polymer layer is 1 x 107 (drops/3) or more and 2 x 10'' (drops/3).
) is preferably in the following range, more preferably,
5xlo' (pieces/m3) or more, 1.5X10" (pieces/■
3) The following is true. In order to obtain a sufficient light scattering state when no voltage is applied, it is desirable that the incident light be scattered by microdroplets at least multiple times when passing through the polymer layer, and if the number density is less than the above range. On the other hand, if there is too much light scattering, the transparency during voltage application will be impaired, and the physical strength of the polymer wall will decrease due to a relative decrease in the amount of polymer components, which is undesirable. .

As a method for physically evaluating the optical shutter effect of such a liquid crystal display element and the quality of light transmittance when voltage is applied, the present inventors have developed a method in which a beam-shaped parallel light is perpendicularly incident on a liquid crystal droplet-dispersed polymer layer. With respect to the scattering property of light transmitted in the back direction of the liquid crystal droplet dispersion layer, the intensity curve of the transmitted light obtained by setting the center as Oo and measuring the light intensity corresponding to the left and right angles is determined, and the voltage is determined. We have established a method to evaluate the light scattering properties when no voltage is applied and the transparency when voltage is applied.

- As an example, FIG. 3 shows a liquid crystal display device according to Example 1 of the present invention in which the average particle size of the liquid crystal droplets is 3.9μ, when no voltage is applied (a), and when a voltage is applied (b). The light intensity at 100% transmission when no element is placed in the optical path, which shows the angular dependence of light scattering, is set to 1, and the element is set in the primary order.
The fact that scattered light is detected over a wide range of angles, where the vertical axis shows the transmitted light intensity at an angle θ from the incident point in logarithmic quantities, is
This means that the element has high light scattering properties. Also, θ=00
A large amount of light means that the element has high transparency. Furthermore, the larger the change in the intensity of transmitted light with respect to the change in θ near the center point, the more clearly the outline of the shape of the object on the light source side can be seen through this element. Therefore, FIG. 3(a) shows a case in which the contour of the object on the opposite side of the element cannot be seen due to the cloudy state when no voltage is applied. On the other hand, Fig. 3 (
b) Now.

The transmittance is high at θ=0'', and the scattered light is weak at θ=0@, which means extremely high transparency.

FIG. 5 shows the average particle size of liquid crystal droplets in Comparative Example 1.

1.4. (a) shows the angle dependence of light scattering in the no voltage applied state (a) and the voltage applied state (b) when the voltage is small.
Although it is in a cloudy state, the shape of the object behind the element can be clearly seen because the change in transmittance intensity near the incident point is large.

When voltage is applied (b), the transmittance at angle Oo is as shown in Figure 3 (b).
), and indicates a so-called cloudy state in which light is detected even at surrounding angles other than 0°. Therefore, it is clear that the performance when no voltage is applied (a) or when voltage is applied (b) in FIG. 5 is inferior to that in FIG. 3.

On the other hand, FIG. 7 shows the light scattering characteristics when the average particle size of the liquid crystal droplets was too large at 6.64 in Comparative Example 2 with the present invention.
This shows that the light source transmittance at θ=O° when no voltage is applied (a) is high and the light scattering property is weak, which is not preferable for 1 display.

The liquid crystal referred to in the present invention is an organic substance mixture that exhibits a liquid crystal state at around room temperature and has positive dielectric constant anisotropy, and includes nematic liquid crystal, cholesteric liquid crystal, smectic liquid crystal, and the like.

Among these, nematic liquid crystals or nematic liquid crystals to which a cholesteric component is added are preferable in terms of characteristics.

The liquid crystal may contain pigments to improve contrast or color tone.In order to obtain a strong light scattering state when no voltage is applied, the extraordinary refractive index of the liquid crystal mixture should be as close as possible to the polymer refractive index. It is desirable that the refractive index of the liquid crystal be significantly different, and it is desirable that the ordinary refractive index of the liquid crystal be as close as possible to the refractive index of the polymer.

As a liquid crystal mixture, the temperature range in which the liquid crystal state occurs should be as wide as possible, especially for outdoor applications, from -20℃ to
It is desirable to have a liquid crystal temperature range of +90°C or higher.

In the present invention, the polymer is not limited as long as the ordinary refractive index of the liquid crystal to be dispersed and the refractive index of the polymer are almost the same, but in order not to reduce the brightness of the device or the transparency during driving, It is desirable that the coloring is high and that there is little coloring.
In addition, substances that dissolve in liquid crystals or elute ionic or nonionic impurities into liquid crystals are undesirable because they degrade the performance of liquid crystals, and the ordinary refractive index of liquid crystals and the refractive index of polymers It is especially important that the refractive indexes of the polymer containing the liquid crystal and the liquid crystal almost match, even when a small amount of liquid crystal is dissolved and contained in the polymer. The difference in refractive index in the case is 0.
It is desirable that the value be within 01.

Specific examples of polymers include polyvinyl alcohol, polyvinyl formal, polyvinyl butyral, polyethylene, polypropylene, polymethyl methacrylate, polyamide, ethyl cellulose, cellulose acetate, hydroxypropyl cellulose, curable epoxy resin, polyurethane, etc. It can also be used if it meets the above conditions.

Further, chemical substances such as resins, plasticizers, ultraviolet absorbers, and some dyes that are compatible with the polymer may be mixed.

Further, a crosslinking agent, a curing agent, a reaction initiator, or a small amount of additive for adjusting the refractive index may be mixed to improve the heat resistance and other properties of the polymer. Among these, when using a water-soluble polymer, a liquid crystal material is added to an aqueous solution of the polymer and emulsified and dispersed using a homogenizer or the like.

By changing the emulsification conditions in the homogenizer, particles with different distributions of particle sizes can be obtained. Furthermore, the dispersion may be subjected to filtration treatment using a filter, or may be subjected to classification treatment such as centrifugation treatment.

Furthermore, it is possible to obtain liquid crystal grooves with uniform particle diameters.

By spreading this dispersion on a substrate and removing the solvent, a polymer layer having desired liquid crystal grooves can be obtained.

In addition, polyvinyl butyral, polyvinyl formal,
When using a polymer that can be used in organic solvents, such as polymethyl methacrylate, the liquid crystal material is uniformly dissolved in the polymer solution and then spread on the substrate, and as the solvent dries, liquid crystal microdroplets are deposited in the polymer layer. can be done. At this time, the particle size of the liquid crystal produced can be changed by selecting the type of solvent used, so by mixing the desired solvents in any ratio to create an appropriate mixed solvent, you can use the desired It is possible to obtain particles with a particle size of In addition, if the rate of evaporation of the solvent is slow, relatively large liquid crystal grooves are likely to be obtained, and if the rate is high, small liquid crystal grooves are likely to be obtained. The average grain size of the liquid crystal grooves can be controlled by adjusting the line speed, etc.

Furthermore, after forming the liquid crystal grooves, the particles can be grown to any desired size by heat treatment at high temperatures.

In addition, when using a curable resin such as epoxy resin, acrylic resin, or urethane resin, liquid crystal is uniformly dissolved in the resin solution before curing, and liquid crystal microdroplets are precipitated into the polymer layer as the curing reaction progresses. be able to. At this time 5
By changing the curing speed and resin, liquid crystal grooves with an optimal particle size distribution can be obtained. In addition, these microscopic spheres are often close to spherical, but they do not need to be perfectly spherical. Furthermore, the microdroplets do not have to be completely independent, and some linkage in the liquid crystal droplet volume does not impede light scattering properties.

In the present invention, as a transparent substrate, a relatively rigid substrate with a thickness of 0.1 to 4 mm such as glass with high visible light transmittance and low scattering property, polymethyl methacrylate, epoxy cured resin, or polyester film, epoxy resin, etc. cured film, polyether sulfone film,
Polypropylene film and other flexible film substrates with a thickness of 0.01" and 0.5m, which are chemically stable for liquid crystals, can be used. The surface of the substrate has a barrier effect that blocks air and water vapor. A reflective film, an antireflective film, a hard coat layer, an ultraviolet absorbing layer, or the like may be formed.

A display element is constructed by sandwiching a polymer layer between two of these, either the same one or a different combination.

Reflective display boards that use reflective substrates are especially important for large display boards.Reflective display boards include a pure reflective type that uses a metallic mirror surface, a colored reflective type that uses various types of light absorption, and a colored reflective type that uses light absorption. There are mainly black reflective type 1 reflecting surfaces such as specular reflection, satin finish, and matte depending on the condition of the reflecting surface, and milky white and various emulsion colored reflecting plates that utilize light absorption and scattered transmitted light. When directly utilizing a metal surface or a conductive coating, the transparent conductive film treatment may be omitted. The metal surface, like the transparent conductive film, can be photoresist and/or etched to suit various display purposes.

aluminum, gold, silver, platinum, nickel, palladium,
A reflective substrate is formed by coating a suitable substrate using a method such as plating, vapor deposition, sputtering, or ion blasting.

In this case, a reflective display element is constructed by combining a reflective substrate, a polymer layer, and another conductive transparent substrate.In the case of a single reflective type, a double-sided reflective substrate with a reflective film treatment on both sides is used. Two transparent conductive substrates sandwich two liquid crystal microdroplet-dispersed polymer layers to form a double-sided reflective display element.

A transparent conductive layer is required on the surface of the opposing transparent substrate facing the liquid crystal droplet-dispersed polymer layer in order to apply voltage to the liquid crystal droplets, and this layer is made by vapor-depositing and sputtering tin oxide or a mixture mainly composed of indium oxide. It is formed by coating to a thickness of 20 to 5,000 layers using a CVD method, a pyrosol method, or the like.

The transparent electrode can be etched into a predetermined shape by photolithography or photoresist printing to display a localized image, or it can be formed into a segment or dot matrix.

Further, a large number of conductive film transistor elements or diode elements for driving each dot independently may be formed on the substrate.

In addition, the liquid crystal display element manufactured in this way can be used alone as it is, or it may be used as laminated glass by covering one or both sides with a glass plate, etc. In this case, the overall smoothness Improves properties such as toughness, rigidity, surface hardness, durability, and design. Furthermore, by providing a plurality of liquid crystal droplets, higher quality and larger capacity display can be achieved.

The liquid crystal display device of the present invention can be used in many of the applications of conventional liquid crystal display devices, such as calculator 1 clock, ECR 1 automobile instrument panel display, and other information displays.

In addition, this type of liquid crystal display element is suitable for manufacturing larger display devices than conventional ones, so it can electrically control the transition between a transparent and cloudy state or between a transparent and colored state. It can be applied to windows, doors, partitions, automobile sunroofs, etc., as well as large double-sided reflective advertising boards and 1-time display boards.

〔Example〕

An example of the present invention is shown below, but the present invention is not limited thereto.

As a polymer for ecchial macules, 9 g of a 3% aqueous solution of polyvinyl alcohol (PVA) (PVA 224 manufactured by Kuraray) and 6 g of nematic liquid crystal (ZLI-1289 manufactured by Merck) were mixed.

The mixture was stirred for 10 minutes at a rotational speed of 500 rpm using a homogenizer (Labora Leap Superser manufactured by Istral) to form liquid crystal droplets having a particle size distribution as shown in FIG.

This particle size distribution was actually measured using a particle size distribution measuring device (SH-CP3L) manufactured by Shimadzu Corporation. The average particle size of all particles was 3.94.

The number of particles having a particle size in the range of 1 to 7-7 was 96% of the total number of particles.

Next, the liquid crystal droplet dispersion was applied onto a polyester film with transparent electrodes by a bar coating method.

After sufficiently drying, a panel-shaped sample was prepared by pasting it on flint glass with a transparent electrode and laminating it. As a result of observation with a scanning electron microscope (SEM), the particle size distribution of liquid crystal particles in the liquid crystal droplet-dispersed polymer layer (hereinafter referred to as "liquid crystal droplets") of the sample prepared here was determined to be
The distribution was similar to that shown in the figure. The thickness of the liquid crystal droplet, that is, the distance between the two transparent electrodes, is 16. Met.

The above polyester film is a polyester film (thickness 11110. .cm).

FIG. 3 shows the angular dependence of light scattering of the above sample when no voltage is applied (a) and when 50 V AC voltage is applied (b), measured by the light scattering evaluation device proposed by the present inventors. Figure 3(a) shows that the sample is in a sufficiently opaque state when no voltage is applied to it;
Figure (b) shows that when a voltage is applied, the light component becomes almost a straight light component and becomes transparent.

Note that the straight light transmittance is 1.0% when no voltage is applied, and 5%.
When 0 V AC voltage was applied, the contrast was 80.5%, indicating good contrast. Moreover, when no voltage was applied, the shape of the object could not be seen through the sample at all, and it had perfect blocking properties.

According to the sample preparation method described in Example 1, a mixture of polymer solution and liquid crystal was prepared, and the particle size of liquid crystal droplets was determined by changing the stirring speed of the homogenizer from 500 Orpm to 15.00 Orpm. The distribution was formed as shown in FIG. The average value of the particle size of all the particles was 1.4μ, and the number of particles having a particle size within the range of IIa to 7μ was 64% of the total number of particles.

Next, the liquid crystal droplet dispersion was applied onto a polyester film with transparent electrodes by a bar coating method.

After drying thoroughly, the thickness of the liquid crystal droplet is reduced to 1.
A comparative sample (1) of 6Itm was prepared.

FIG. 5 shows the light scattering properties (a) when no voltage is applied to this comparative sample and the light scattering properties (b) when an AC voltage of 60 V is applied.

Comparing Figure 5(a) with Figure 3(a), a sharp change in the intensity of the transmitted light is seen near θ=O°, and when no voltage is applied, the transmitted light passes through the element and the opposite side It was shown that there is a problem in recognizing the shape contour of an object.

In addition, the straight light transmittance (θ=0°) of this comparative sample is 5
When 0V AC voltage was applied, it remained at 52.7%.

The transparency when applying an AC voltage of 50 volts was significantly inferior compared to Example 1.

A mixture of a polymer solution and a liquid crystal was prepared according to the sample preparation method described in Example 1, and the particle size distribution of liquid crystal droplets was adjusted by changing the stirring speed of the homogenizer from 500 Orpm to 200 Orpm. It was formed as shown in Figure 6. Furthermore, a comparative sample (2) in which the thickness of the liquid crystal droplet after drying was 16- was produced by a bar coating method. What is the average particle size of all particles?

6.6p, and the number of particles having a particle size within the range of 14 to 7μ was 53% of the total number of particles.

FIG. 7 shows the light scattering characteristics (a) when no negative voltage is applied to comparative sample (2) and the light scattering characteristics (b) when an AC voltage of 50 V is applied.

Comparing FIG. 7(a) with no voltage applied to FIG. 3(a), the straight light transmittance is high, indicating that the light blocking effect is lacking. The main reason for this is considered to be that the particle size of the liquid crystal droplets is large on average, so the density of the liquid crystal droplets is low, and the number of times the incident light is scattered is significantly reduced.

Note that the transmittance of straight light is 7% and 50% when no voltage is applied.
v When AC voltage was applied, it was 80.4%.

Thief Wataru 1 According to the sample preparation method described above in the examples.

Prepare a mixture of polymer solution and liquid crystal, each with 20
Three types of liquid crystal droplet dispersion polymers were obtained at stirring speeds of 00 rpm, 5000 rpm+, and 15000 rpm, and by uniformly mixing equal amounts of these polymers, a liquid crystal droplet dispersion having a particle size distribution shown in FIG. 8 was obtained. By using the bar coating method, the thickness of the liquid crystal droplets after drying was reduced to 16. A comparative sample was prepared.

The average particle size of all particles was 5.04.

The number of particles having a particle size of 14 to 7Ia was 67% of all particles.

FIG. 9 shows the light scattering characteristics (a) when no voltage is applied to the sample and the light scattering characteristics (b) when an AC voltage of 50 V is applied.

In this comparative example, a distant view was visible through the sample when no voltage was applied, and this is shown in FIG. 9(a), that is, θ=
Strong forward scattering occurred near 0°, indicating that the outline of the shape of the object in front could be identified by the transmitted light, similar to what was explained in FIG. 5(a). Further, the linear light transmittance when voltage was applied was 63.2%, indicating incomplete transparency.

Using the same dispersion of polyvinyl alcohol aqueous solution and liquid crystal as prepared in Example 1 (the particle size distribution is the same as that shown in Figure 2), the coating thickness was adjusted by selecting a bar coater. Dry film thickness: 8-22. Six levels of samples (Examples 2-1 to 2-6) and two levels of comparative samples (Comparative Examples 2-1 and 2-2) were prepared within the range of . The straight light transmittance of these objects was measured when there was no charge (OV) and AC charge (50V), and the contrast ratio was determined.
It was shown to. It has been found that a film thickness in the range of 10-18 m is particularly desirable in order to ensure the contrast ratio necessary for a display and the transparency when 50 V AC is applied.

By changing the mixing ratio of polyvinyl alcohol and liquid crystal, the number density of liquid crystal microdroplets in the polymer was changed. That is, using the formulation shown in Table 2, 10% PVA aqueous solution, water and liquid crystal were mixed as in Examples 3-1 to 3-6, and similarly emulsified and dispersed at 5000 rpm for 10 minutes using a homogenizer.

The particle size distribution of these materials has an average particle size of 3
-54, and the sum of the number of particles less than 14 and more than 7 was 20% or less of the total particles. As comparative examples, Comparative Examples 3-1 and 3-2 were prepared, and their formulations are also shown in Table-2.

Using these dispersions, the dry thickness of liquid crystal droplets was approximately 16
A liquid crystal display element was prepared in the same manner as in Example 1 by applying the coating using various bar coaters depending on the non-volatile content so that the coating thickness was μ.

The distribution density of liquid crystal microdroplets in the polymer layer was determined by observing all cross sections of the polymer layer and counting the number of particles using a scanning electron microscope. Examples 3-1 to 3-6 had a tenoparticle number density of 1×107 to 2×1O” (particles/am)
), there are no process problems,
Also, the display contrast was good, but Comparative Example 3
When the particle number density is small, as in Comparative Example 3-1, light scattering becomes weak when no voltage is applied, and when the particle number density is too high, as in Comparative Example 3-2, transparency is poor when electricity is applied. was.

Moreover, in Comparative Example 3-2, when the coating film was dried, the liquid crystal droplets were destroyed because the amount of polymer was too small.

The surface smoothness was poor.

Arrow 104L Polyvinyl Butyral (Sekisui Chemical S-LEC BM-5
Log), 45 g of tetrahydrofuran, and 45 g of isopropyl alcohol were mixed and dissolved to prepare a polymer solution. 20 g of liquid crystal (manufactured by BDH! E!-7) was added to this and uniformly dissolved. This liquid mixture was applied onto a toon polyester film coated with ITO (indium tin oxide) using a bar coater so that the dry thickness was 151 Ia. The coated film was dried in a hot air dryer at 50° C. for 30 minutes, and then laminated with another ITO-coated film to produce a liquid crystal display element. When the polymer layer was observed using a scanning electron microscope fIt (SEM), it was found that liquid crystal microdroplets with a particle size of about 1 to 5− were formed in the polymer layer, and the size of the liquid crystal grooves was determined from the 58M photograph of them. When measured, the average particle size was 3.7. and
Further, the total number of liquid crystal particles having a particle size of less than 1 μm and more than 7 μm was 10% or less of the total number of liquid crystal particles. This display element.

When no voltage was applied, it completely blocked the distant view, and its straight light transmittance was 0.7%, and when 50V AC was applied, it became transparent, and its straight light transmittance reached 80.2%.

The sample preparation method described in Example 4 was followed, but the drying temperature was changed to 30°C for 1 hour or 80°C. After drying for 10 minutes, each was laminated with another IT○ film to produce a liquid crystal display element.

The one dried at 30°C (Comparative Example 4-1) had a diameter of 3 to 1
5. It is formed by liquid crystal grooves with an average particle size of 6.
The number of particles as large as 2p and exceeding 74 was 37% of the total number.

The straight light transmittance of this display element is 5.8 when no voltage is applied.
%, and the light shielding property was insufficient. Also, 8
Those dried at 0°C (Comparative Example 4-2) had a diameter of 0.3~
It is formed by 2.44 liquid crystal grooves, and the average diameter is 1
．． 24, and the number of particles less than 14 was 33%.

The straight light transmittance of the display element in Comparative Example 4-2 was 0.9% when no voltage was applied, but it decreased to 6% when 50V AC was applied.
It was cloudy at 2% and the 1 display contrast was poor.

ζ 5 and ratio 5 Almost the same as Example 4, except that the thickness of the liquid crystal drop after drying was 10. ．． 124.15. ．． It was coated onto an ITo-coated polyester film using several types of bar coaters to give a thickness of 18μ and 20μ. Also, for comparison, the thickness is 25. One (Comparative Example 5-1) and one with a thickness of 8 μm (Comparative Example 5-2) were also produced.

The coated film was dried in a hot air dryer at 50° C. for 1 hour, and then bonded to another 1+am thick ITO coated glass plate to produce a liquid crystal display element.

Liquid crystal droplets with a diameter of about 1 to 5 μm are formed in these polymer layers, and the average particle size is 3.2 to 4.2 μm.
4, and the number of liquid crystal droplets with sizes from 1p to 74 was 90% or more of the total number.

Among these display elements, those with a thickness of 10 to 20/a (
Examples 5-1 to 5-5) showed good contrast at low voltage, but the thickness was 8/l! (Comparative Example 5-2)
The light transmittance in the OFF state is too large, and the thickness is 25
．． The one (Comparative Example 5-1) had insufficient transparency when 50 V AC was applied (ON state). These results are shown in Table 3.

The mixed solution of the polymer solution and liquid crystal prepared in Example 4 was mixed using a gravure coating device manufactured by Hirano Metal Co., Ltd.
m@ roll-wound polyester film with ITO (
Kanai Co., Ltd. iaT coat A-125) with a dry thickness of 15M
After drying in-line at 80° C. for 5 minutes, it was laminated with another 10-L film with ITO.

After cutting this into a length of 1.4 m, an extraction electrode was attached when voltage was applied, and two windshield plates each having a thickness of 2 mm were laminated together to form glass. A polyvinyl butyral film having a thickness of 25 μm was used as the adhesive layer for the laminated glass, and after laminating in vacuum, hot pressing was performed at 150° C. for 5 minutes. Furthermore, we completed a dimming window glass by connecting an open circuit to the extraction electrode.

The average value of the liquid crystal particle diameter of the light control window glass produced in this way was 4.24, and the particle size was 1 to 7 μm.

It is 85% of the total number, and the straight light transmittance is 1 between 0 and 50V.
．． It varied from 2 to 78%, and it was possible to switch display between complete shielding and transparency.

5 g of twisted epoxy resin (Epicoat 828 manufactured by Yuka Shell Epoxy Co., Ltd.), 5 g of hardening agent (Epomate S-002 manufactured by Yuka Shell Epoxy Co., Ltd.), 5 g of methyl ethyl ketone
g, and 5 g of liquid crystal (E-9 manufactured by BDH),
Dissolved uniformly. This was applied onto the ITO-coated polyester film using a bar coater so that the dry thickness was 15 μm, and after drying in a hot air dryer at 45°C for 10 minutes to remove the solvent, it was laminated with another sheet of ITO film. did.

This was heated at 45° C. overnight to harden the epoxy resin, and a layer of liquid crystal portion precipitated in the cured epoxy material layer was obtained. In the epoxy cured layer, an average of 4.4. Particles of the liquid crystal part were formed, and the sum of the number of particles less than 14 and more than 7M was 10% or less of the total number of liquid crystal droplet particles. The straight light transmittance of this display element was 1.8% when no voltage was applied, blocking distant views, and 76.7% when 50V was applied, showing high transparency.

The method was similar to Example 7, but after laminating a polyester film with ITO through a cured epoxy resin layer containing liquid crystal, it was cured by heating at 80°C for 2 hours (Comparative Example 6-
1), or Comparative Example 6-2) L left at room temperature for a week
, the epoxy resin was cured.

In the case of Comparative Example 6-1, the liquid crystal part was small as a whole because the curing was completed in a short time, and the epoxy cured material layer contained
Particles with an average particle size of 0.87a are formed, and the particle size is 11
Particles smaller than a accounted for 85%.

The straight light transmittance of this display element is 1 when no voltage is applied.
．． 6%, but even if an AC voltage of 50V was applied, it was 32.
6%, indicating extremely poor transparency.

In the epoxy cured material layer of Comparative Example 6-2, an average particle size of 12
．． Liquid crystal droplets as large as 04 are formed, and the diameter is 7y.
Particles larger than m accounted for 65%. The straight light transmittance of this display element was 17.8% when no voltage was applied, and 81.4% when an AC voltage of 50 V was applied, indicating low contrast.

[Brief explanation of drawings]

FIG. 1 is a sectional view schematically showing the basic structure of a liquid crystal display device according to the present invention. Figure 2 shows the particle size distribution of the liquid crystal microdroplets described in Example 1 of the present invention, and Figure 3 shows the liquid crystal display element produced in Example 1 when no voltage is applied (a) and when no voltage is applied. The light scattering characteristics at time (b) are shown. 4, 6 and 8 show the particle size distribution of liquid crystal microdroplets in each comparative example corresponding to Comparative Examples 1 and 2.3, respectively, and FIGS. The figure shows the light scattering characteristics of each liquid crystal display element when no voltage is applied (a) and when a voltage is applied (b) corresponding to Comparative Examples 1.2.3. In FIG. 1, each number has the following meaning. 1...Polymer layer 2...Liquid crystal microdroplet 3.4...Transparent substrate 5.6...Transparent electrode 7...Active power source 5 1 1 Figure 2 Figure og r(G) ) Fig. Fig. 2 0 2 4 Fig. Particle size (pm) Fig.

Claims (1)

[Scope of Claims] 1) At least one polymer layer in which liquid crystal microdroplets are dispersed, and two or more transparent conductive substrates sandwiching the polymer layer (provided that one of the substrates is opaque). liquid crystal display elements and devices comprising liquid crystal droplets (which may be reflective or reflective), wherein the liquid crystal droplets have an average particle size of 3 μm to 5 μm.
A liquid crystal display element and device characterized by having a particle size distribution in which the number of particles with a particle size of 1 μm or more and 7 μm or less is 70% or more of the total number of particles. . 2) The thickness of the polymer layer in which liquid crystal microdroplets are dispersed is 10μ
2. The liquid crystal display element and device according to claim 1, wherein the liquid crystal display element and device are in a range of not less than m and not more than 18 μm. 3) The number density of the liquid crystal droplets in the polymer layer in which the liquid crystal microdroplets are dispersed is in the range of 1×10^7 (pieces/mm^3) or more and 2×10^■ (pieces/mm^3) or less. The liquid crystal display element and device according to claim 1 or 2.