JPH02205819A - Liquid crystal device - Google Patents

Abstract

PURPOSE:To produce the liquid crystal device without using water and to prevent the intrusion of ionic impurities into the liquid crystal by inserting a porous high-polymer film holding a p type nematic liquid crystal between two sheets of electrodes, at least one of which is transparent. CONSTITUTION:This liquid crystal device is formed by inserting the porous high-polymer film holding the p type nematic liquid crystal between two sheets of the electrodes, at least one of which is transparent. The porous high-polymer film holding the p type nematic liquid crystal is formed of the p type nematic liquid crystal, the fine particles consisting of the high-polymer material insoluble in the nematic phase of the p type nematic liquid crystal and an isotropic phase as well and a binder for adhering the fine particles consisting of the high- polymer material insoluble in the nematic phase of the p type nematic liquid crystal. Since the water is not used in the production process in this way, the ionic impurities are hardly intruded into the liquid crystal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid crystal device, and more particularly to a liquid crystal device using a light scattering effect, which is suitably used in display devices, light control glasses, etc. It is something.

[Prior Art] A TN (twisted nematic) type liquid crystal device is currently widely used as a display device in which a liquid crystal is sandwiched between transparent electrode substrates.

However, this type of device is dark because it requires the use of two polarizing films, and requires a processing process to make the liquid crystal device continuously twisted by more than 90 degrees between the two electrodes. It has the following disadvantages.

Japanese Patent Application Laid-Open No. 54-21859 discloses a device in which transparent solid fine particles are dispersed in a liquid crystal. In this device, the liquid crystal is a p-type (positive dielectric anisotropy) nematic liquid crystal,
When the refractive index of normal light matches the refractive index of the fine particles of a transparent solid, light scatters and becomes opaque when no voltage is applied.1 When voltage is applied, liquid crystal molecules align parallel to the direction of the electric field and become transparent. Since this device does not require the use of a polarizing film, it is bright and does not require complicated processing steps for aligning liquid crystal molecules.

JP-A-60-252687 discloses a device in which liquid crystal is dispersed in a latex medium by mixing a liquid crystal and an aqueous phase to form a liquid crystal emulsion, mixing a suspension containing latex particles with this, and drying the liquid crystal emulsion. has been disclosed,
This device also has the same function as the device disclosed in Japanese Patent Application Laid-Open No. 54-21859.

[Problems to be Solved by the Invention] In the device described in JP-A-54-21859, when used for a long period of time, transparent solid particles in the liquid crystal move and
Local unevenness in the dispersion density of transparent solid particles and non-uniformity in the thickness of the liquid crystal layer tend to occur on the display surface. This causes a problem that the optical properties of the display surface are not uniform.

The device described in JP-A-60-252687 is manufactured by mixing a liquid crystal emulsion and a suspension of latex particles and drying the mixture. In effect, you will be using water.

The use of water is undesirable because ionic impurities are likely to be mixed into water, which may adversely affect the electrical characteristics of the device.

The present invention was devised in view of the shortcomings of the prior art, and its purpose is to make the optical properties of the display surface uniform over a large area, and to improve the uniformity of the optical properties of the display surface, which may adversely affect the electrical characteristics. An object of the present invention is to provide a liquid crystal device that can be manufactured without using water.

[Means for Solving the Problems] The object of the present invention is to provide two materials, at least one of which is transparent.
A liquid crystal device comprising a porous polymer film holding a p-type nematic liquid crystal sandwiched between two electrodes, the polymer porous film holding the p-type nematic liquid crystal comprising a p-type nematic liquid crystal, It is characterized by comprising fine particles made of a polymeric substance insoluble in both the nematic phase and the isotropic phase of the nematic liquid crystal, and a binder for adhering the fine particles made of a polymeric substance insoluble in the nematic phase of the p-type nematic liquid crystal. This is achieved by a liquid crystal device.

By fixing the structure consisting of liquid crystal and fine particles using a binder made of a polymeric substance, it exhibits stable performance even during long-term use.

The fine particles made of a polymeric substance used in the present invention can be used at room temperature and at the temporary liquid crystal clearing point (
In order to maintain the structure of the porous film even at high temperatures above (the phase transition temperature between nematic phase and isotropic phase), it is necessary that the porous film does not dissolve in either the nematic phase or the isotropic phase of p-type nematic liquid crystal. is important. Examples of fine particles that satisfy these conditions include polyethylene, polypropylene, polyamide, polyacrylonitrile, polyvinyl alcohol, and cellulose, and those containing ethylene or ethylene in the main chain.
Examples include copolymers containing structural units such as propylene, acrylonitrile, or vinyl alcohol.

As the copolymer, it is preferable to use a copolymer containing 80 mo1% or more of ethylene, propylene or acrylonitrile, or a copolymer containing 4Q mo1% or more of vinyl alcohol.

Further, fine particles made of a three-dimensionally crosslinked polymer substance also satisfy the above conditions. For example, in addition to fine particles made of crosslinked polymer substances, crosslinked epoxy resins, crosslinked polyurethanes, and styrene, isoprene, butadiene, alkanols, acrylic esters such as ethyl acrylate, and methacrylates such as methyl methacrylate in the main chain. At least one of acid esters, vinyl esters such as isobutylene, methyl butene, vinyl acetate, and vinyl chloride
Examples include, but are not limited to, fine particles made of a crosslinked polymer containing various structural units.

The refractive index of the fine particles made of a polymeric substance is not particularly limited, but is preferably in the range of 1.4'6 to 1.56, which makes it possible to match the refractive index of normal light of the p-type nematic liquid crystal used in the present invention. It can be made as suitable.

In order to use the liquid crystal device of the present invention as a large-area light control glass, for example, since a large-area glass with transparent electrodes is very expensive, first a p-type nematic film is placed between the films with transparent electrodes. Generally, a method is adopted in which a structure is made in which porous polymer membranes holding liquid crystal are sandwiched, and this is heat-sealed to a glass surface using ethylene-vinyl acetate copolymer, polyvinyl butyral, or the like. If the fine particles made of a polymeric substance are thermoplastic and their softening point is too low, there is a risk that the membrane structure will be destroyed during thermal fusion to the glass surface.

When the fine particles made of a polymeric substance used in the present invention are thermoplastic, the softening temperature thereof may be selected within a range that achieves the object of the present invention, and is not particularly limited, but preferably 80°C or higher, It is more preferable to select the temperature in the range of 100°C or higher, further preferably 110°C or higher.

The fine particles made of the above-mentioned polymeric substance serve as the skeleton of the porous membrane. These may be used alone, but in the case of fine particles having similar refractive indexes, two or more types may be used in combination.

The particle size of the fine particles forming the framework of the porous membrane is not particularly limited, but is preferably 0.5 to 20 μm, more preferably 1
The thickness is in the range of 1 to 10 μm, more preferably 2 to 6 μm. If the particle size is too small, the amount of light scattered by a single particle is too small, resulting in poor opacity of the device when no voltage is applied. If the particle size is too large, the amount of light scattered by a single particle is large, but the number of particles contained in a unit volume is too small, and the opacity of the device when no voltage is applied may also be poor. Become.

As the p-type nematic liquid crystal used in the present invention, known ones can be used, and there are no particular limitations, but
In order to achieve good transparency when a voltage is applied and opacity when no voltage is applied, select a material whose refractive index for normal light is close to that of fine particles made of polymeric material and has a large refractive index anisotropy. It is better to do so. Further, in order to lower the driving voltage, it is preferable to select a material with large dielectric anisotropy.

As a commercially available p-type nematic liquid crystal that can be used in the present invention, for example, p-type nematic liquid crystal RO-T manufactured by Roche
Merck p-type nematic liquid crystal ZLI-2061 and ZLI- such as N-403 and RO-TN-623
2144, p-type nematic liquid crystal E-3 manufactured by BDH
7 and E-44.

In the present invention, the polymeric substance used as a binder for adhering fine particles made of a polymeric substance may be dissolved in the isotropic phase of the p-type nematic liquid crystal, but it maintains the structure of the porous membrane at room temperature. Therefore, it must be insoluble in the nematic phase. Written by Vinyl Gil S) [Scaling Concepts in Polymers]
Physics (Scaling Concepts i)
Cornell University Press
rsity Press) 1979 edition 9! According to the description on pages 1 to 99, polymeric substances generally have a degree of polymerization of 40.
If it is above, it is insoluble in the nematic phase of the nematic liquid crystal. Therefore, the polymeric substance for the binder is not particularly limited, but preferably has a degree of polymerization of 40 or more,
More preferably, it is 80 or more.

It is desirable that the refractive index of the polymer material for the binder be close to the refractive index of the fine particles that form the framework of the porous membrane, but since the amount used is small, there is actually a considerable difference in the refractive index. It doesn't really matter though.

The polymeric substance for the binder may be any substance as long as it is insoluble in the nematic phase of the p-type nematic liquid crystal and can adhere the fine particles that form the framework of the porous membrane, but preferably the polymeric substance is p-type. Insoluble in the nematic phase of nematic liquid crystal and isotropic phase of p-type nematic liquid crystal or p
It is desirable that the liquid crystal be dissolved in a mixture of a nematic liquid crystal and an organic solvent described below.

Specific examples include polyethylene, polypropylene,
Examples include polyamide, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinylidene chloride, polymethyl methacrylate, polyurethane, polyether, polyvinyl acetate, voisoprene, polybutadiene, polyacrylonitrile, polystyrene, and copolymers thereof. but not limited to. Moreover, these polymer substances for binders may be used alone, or two or more types may be used in combination.

If necessary, add stabilizers to the fine particles that form the framework of the porous membrane.
Plasticizers, dyes, pigments, etc. may also be added. Also,
A chiral agent, pleochroic dye, etc. may be added to the p-type nematic liquid crystal. Furthermore, stabilizers, plasticizers, dyes, pigments, etc. may be added to the binder polymer material.

The ratio (weight ratio) of the total amount of the p-type nematic liquid crystal, the microparticles that form the skeleton of the porous membrane that holds the liquid crystal, and the polymer substance for the binder is not particularly limited, but is preferably The ratio is in the range of 2:8 to 7:3, more preferably 3-near to 6:4, and even more preferably 4:6 to 5:5. If the proportion of the liquid crystal is too small, the proportion of the voltage distributed to the liquid crystal will be too small, and therefore the driving voltage will become too high, which is not preferable. Furthermore, if the ratio of the total amount of fine particles serving as the skeleton of the porous membrane and the polymeric substance for the binder is too small, a porous membrane may not be formed by bonding the fine particles with a bander.

The ratio (weight ratio) of the fine particles serving as the skeleton of the porous membrane to the polymeric substance for the binder is not particularly limited, but is preferably 50:1 to 2:1, more preferably 20:1 to 5:1.
, more preferably in the range of 15:1 to 9.1. If the proportion of the polymeric substance for binder is too small, fine particles may not be able to adhere to each other, and a porous membrane may not be formed.

Furthermore, if the proportion of the polymeric substance for the binder is too large, and the refractive index thereof is considerably different from the refractive index of the fine particles, the transparency of the liquid crystal device when a voltage is applied becomes poor, which is undesirable.

A porous polymer membrane holding p-type nematic liquid crystal formed by bonding fine particles that form the framework of the porous membrane with a polymeric binder is created, and this is connected to two electrodes, at least one of which is transparent. One method of manufacturing a liquid crystal device by sandwiching the liquid crystal devices is as follows.

That is, a suspension is created by mixing the p-type nematic liquid crystal, fine particles that form the framework of the porous membrane, and a binder polymer substance that dissolves in the isotropic phase of the p-type nematic liquid crystal. This is a method in which the electrode is dropped onto a substrate provided with an electrode, and another substrate provided with an electrode is placed on top of it and heat pressed.

When making a suspension by mixing the p-type nematic liquid crystal, the fine particles serving as the framework of the porous membrane, and the polymer material for the binder, the order in which the three components are mixed may be any. The champion may be mixed at the same time. Also, in advance,
The p-type nematic liquid crystal may be mixed after the fine particles forming the framework of the porous membrane are coated with a binder polymer material.

Further, in order to make the thickness of the porous polymer membrane constant, an appropriate amount of commonly used spacer particles may be added to the suspension.

If the polymeric substance for the binder is soluble in the isotropic phase of the p-type nematic liquid crystal, if the polymeric substance for the binder is heated to a temperature above the clearing point of the p-type nematic liquid crystal during the heat pressing stage, the polymeric substance for the binder will dissolve in the isotropic phase of the p-type nematic liquid crystal. Dissolves in nematic liquid crystal. After finishing the heat press,
When cooled to a temperature below the clearing point, a binder polymer substance precipitates from the liquid crystal, adheres the fine particles that form the framework of the porous membrane, and forms a porous polymer membrane holding the p-type nematic liquid crystal. . Of course, the suspension may be heated to a temperature above the clearing point in advance to dissolve the binder polymer material in the p-type nematic liquid crystal before heat pressing. In addition, if a crosslinking agent is added to the polymeric material for the binder, a crosslinking reaction occurs due to heat and ultraviolet rays during heat pressing, and as a result, fine particles are precipitated from the liquid crystal and become the framework of the porous membrane. are adhered to form a porous film holding P-type nematic liquid crystal.

Incidentally, in order to make light incident on a porous polymer film holding p-type nematic liquid crystal and to cause the light to be reflected or transmitted, at least one of the substrates provided with electrodes needs to be transparent. 5. As the substrate provided with the transparent electrode, glass or plastic film coated with a known transparent conductive film can be used. Generally known transparent conductive films include tin oxide films (so-called NESA films) and indium tin oxide films (so-called ITO films).

Another method for manufacturing a liquid crystal device is to defoam a suspension consisting of a p-type nematic liquid crystal, fine particles that form the framework of a porous membrane, and a polymeric substance for a binder, and then apply an applicator onto a substrate equipped with electrodes. , reverse roll coater, Whaler, or other known coating equipment.

If the polymeric material for the binder is dissolved in the isotropic phase of the p-type nematic liquid crystal, the polymeric material for the binder is heated to a temperature above the clearing point of the liquid crystal after application.
The p-type nematic liquid crystal is dissolved therein, and then cooled to precipitate it from the liquid crystal, and the fine particles that form the framework of the porous membrane are adhered to form a polymeric porous membrane holding the p-type nematic liquid crystal.

A liquid crystal device is manufactured by covering the porous film holding the p-type nematic liquid crystal formed as described above with the electrode surface of a substrate provided with electrodes so as to be in contact with the porous film. In addition, after applying the suspension onto a substrate equipped with an electrode, another substrate equipped with an electrode is placed over it and heated, and the polymeric substance for the binder is then deposited by cooling or deposited by a crosslinking reaction. Alternatively, heat fusion may be performed.

The viscosity of the suspension consisting of the p-type nematic liquid crystal, the fine particles that form the framework of the porous membrane, and the polymer material for the binder is high; If this is very difficult, an organic solvent may be added to the suspension to reduce the viscosity. However, the solvent used here is preferably one that does not dissolve the fine particles that form the skeleton of the porous membrane. If it dissolves the fine particles that form the framework of the porous membrane, the shape of the fine particles will be lost.

Solvents are not particularly limited as long as they do not dissolve fine particles made of polymeric substances, but include aromatic hydrocarbons such as benzene and toluene, alcohols such as ethanol and propatool, and esters such as ethyl acetate and butyl acetate. Ketones such as acetone, cyclohexanone,
Examples include chlorinated hydrocarbons such as dichlorothane and chloroform, aliphatic hydrocarbons such as n-pentane and n-hexane, ethers such as dioxane and tetrahydrofuran, aldehydes such as furfural, and amides such as dimethylformamide. It will be done.

These solvents may be used alone, or two or more solvents may be used in combination.

The amount of solvent to be mixed into the suspension consisting of the p-type nematic liquid crystal, fine particles serving as the skeleton of the porous membrane, and the polymeric substance for the binder is not particularly limited, but the amount is such that the mixed liquid has a viscosity suitable for the coating method. It is best to adjust it to For example, when applying using an applicator, the viscosity of the mixed liquid is 1
It is preferable to adjust the amount of solvent so that it becomes ~10 poise.

When making a liquid mixture from p-type nematic liquid crystal, fine particles that form the framework of a porous membrane, a polymeric substance for a binder, and an organic solvent, the additives may be mixed in any order; May be mixed. Furthermore, the fine particles that will form the framework of the porous membrane may be coated with a binder polymer material in advance before mixing.

After degassing these mixed solutions, the mixture is coated onto a substrate provided with electrodes using a known coating device, and the solvent is removed. The solvent may be removed by leaving it at room temperature or by heating it to a high temperature. Alternatively, the solvent may be removed by reduced pressure treatment.

If the binder polymer is soluble in the isotropic phase of the p-type nematic liquid crystal and is also soluble in the solvent, when the solvent is removed at a temperature below the clearing point of the liquid crystal, the binder polymer Molecular substances precipitate and adhere to the fine particles that form the framework of the porous membrane.
A porous polymer membrane holding a nematic liquid crystal is formed.

When solvent removal is performed at a temperature above the clearing point of the liquid crystal, the binder polymer substance precipitates from the liquid crystal during the cooling process after the solvent is removed, and binds the fine particles that form the framework of the porous membrane. A porous polymer membrane holding p-type nematic liquid crystal is formed. When a crosslinking agent is added to the binder polymer material, the binder polymer material precipitates from the solvent or liquid crystal due to a crosslinking reaction caused by heat or ultraviolet rays before and after the removal of the solvent, and forms a porous membrane skeleton. A porous polymer membrane holding P-type nematic liquid crystal is formed by adhering the fine particles.

If the binder polymer substance is not dissolved in the isotropic phase of the p-type nematic liquid crystal but is dissolved in the solvent, the binder polymer substance will precipitate as the solvent is removed and will adhere the fine particles that will form the framework of the porous membrane. A porous polymer film holding p-type nematic liquid crystal is formed. When a crosslinking agent is added to the polymeric material for the binder, the polymeric material for the binder precipitates from the solvent through a crosslinking reaction caused by heat or ultraviolet rays before and after the removal of the solvent, and bonds with the fine particles that form the framework of the porous membrane. Then, a porous polymer film holding P-type nematic liquid crystal is formed.

If the polymeric material for the binder is soluble in the isotropic phase of the p-type nematic liquid crystal, but not in the solvent, and the solvent is removed at a temperature below the clearing point of the liquid crystal, the liquid crystal may be cleared after the removal of the solvent. Heating to a temperature above the ring point dissolves the binder polymer material in the p-type nematic liquid crystal, and then during the cooling process, the binder polymer material precipitates from the liquid crystal and becomes the framework of the porous membrane. A porous polymer membrane holding p-type nematic liquid crystal is formed by adhering the fine particles. When a crosslinking agent is added to the binder polymer, the binder polymer is heated to a temperature above the clearing point of the liquid crystal to dissolve the binder polymer in the P-type nematic liquid crystal. Due to the reaction, a binder polymer substance is precipitated from the liquid crystal, and the fine particles forming the framework of the porous membrane are adhered to form a porous polymer membrane holding the P-type nematic liquid crystal.

When the solvent is removed at a temperature above the clearing point of the liquid crystal, the binder polymer substance dissolved in the p-type nematic liquid crystal precipitates from the liquid crystal during the subsequent cooling process, forming the framework of the porous film. A porous polymer membrane holding p-type nematic liquid crystal is formed by adhering the fine particles.

When a crosslinking agent is added to the binder polymer substance, the binder polymer substance precipitates from the liquid crystal due to the crosslinking reaction before and after the solvent is removed, and bonds the fine particles that will form the framework of the porous membrane, forming a p A porous polymer membrane holding a nematic liquid crystal is formed.

After removing the solvent, the p-type nematic liquid crystal produced by the above method is placed on top of the porous polymer film holding the electrode, so that the substrate with the electrode is in contact with the electrode surface.
A liquid crystal device is manufactured.

In addition, the mixed solution is applied onto a substrate equipped with electrodes, the solvent is removed, another substrate equipped with electrodes is covered, and then heated to cool the polymeric material for the binder or to form liquid crystals through a crosslinking reaction. The fine particles forming the framework of the porous membrane may be adhered by shell precipitation or thermal fusion.

Another method for manufacturing a liquid crystal device is to extrude a suspension of fine particles consisting of p-type nematic liquid crystal and the skeleton of a porous membrane and a polymer material for a binder into a film through a slit of a predetermined thickness and a predetermined width. This method involves placing the device on a substrate with electrodes and covering it with another substrate with electrodes. In this case, adhesion of the fine particles that will form the framework of the porous membrane using the binder polymer material may be performed immediately after extrusion, immediately after being placed on a substrate equipped with electrodes, or may be performed by another method.
This may be performed after covering the substrate with two electrodes.

Alternatively, a liquid mixture consisting of p-type nematic liquid crystal, fine particles serving as a skeleton of a porous membrane, a polymeric substance for a binder, and an organic solvent medium may be similarly extruded into a membrane through a predetermined slit. In this case, the fine particles that form the framework of the porous membrane may be adhered to the polymer material for the binder at any time, but the solvent must be removed before covering the substrate with another electrode. is preferred.

By the above-mentioned heat pressing, coating or extrusion method, an electrode is prepared from a suspension consisting of a P-type nematic liquid crystal, fine particles serving as the framework of a porous membrane, and a polymeric substance for a binder, or a mixture of the suspension and an organic solvent added thereto. directly on the substrate with P
Instead of forming a porous polymer film holding a nematic liquid crystal, for example, it may be formed on a substrate without electrodes and then transferred onto a substrate with electrodes.

Another method for manufacturing a liquid crystal device is to form a porous polymer film in advance from fine particles that will become the framework of the porous film and a polymeric substance for a binder, or a mixture of these and an organic solvent, and then Impregnated with shaped nematic liquid crystal,
There is also a method of sandwiching it between two electrodes.

The thickness of the porous polymer membrane in the present invention is not particularly limited, but is preferably 3 to 100 μm, more preferably 5 μm.
~50 μm1, more preferably 10 to 30 μm.

If the thickness of the porous membrane is too small, the opacity will be poor when no electrode is applied. Further, if the thickness is too large, the voltage required for driving becomes too high, which is not preferable.

When driving the liquid crystal device of the present invention, the voltage source used may be either a direct current voltage or an alternating current voltage, but an alternating current voltage is preferable from the viewpoint of preventing electrolysis of the liquid crystal. Although a 50 Hz or 60 Hz commercial sine wave AC voltage source may be used as the AC voltage source, a rectangular wave voltage source or a 1 kHz
When the above-mentioned high-frequency voltage source is used, the fluctuation of the liquid crystal due to the reversal of the electric field is eliminated, and the average transmittance of light is increased, so that contrast and transparency can be improved.

According to the liquid crystal device of the present invention, the optical properties of the display surface tend to be uniform over a large area compared to conventional devices, and since no water is used in the manufacturing process, ionic impurities are less likely to be mixed in. <, has the advantageous property that deterioration of electrical characteristics is less likely to occur.

The device of the present invention has a function of being opaque when no voltage is applied and transparent when a voltage is applied, and can be effectively used for display devices, light control glasses, and the like.

[Examples] The present invention will be specifically described below with reference to Examples, but the present invention is not limited thereto.

Example 1 0.1 g of chlorinated polypropylene "Super Chron" 803MW (chlorine content 30%) manufactured by Yamaba Kokusaku Pulp Co., Ltd. was dissolved in 3.0 g of dioxane, and polyethylene fine particles manufactured by Seitetsu Kagaku Kogyo Co., Ltd. were dissolved in this solution. Flow beads “LE-1”
1.4 g of 080 (average particle size 5 μm) and 5 g of P-type nematic liquid crystal ZLI-21441 manufactured by Merck & Co., Ltd. were mixed and stirred to prepare a mixed solution, and the mixture was left to stand for defoaming. This mixed solution was applied onto a glass substrate equipped with a transparent electrode made of tin oxide and indium oxide using an applicator with a gap of 50 μm, and the mixture was left in an oven set at 90° C. for 3 minutes to evaporate dioxane.

In the process of taking it out of the oven and cooling it to room temperature, a porous film was formed in which polyethylene fine particles with a thickness of about 20 μm holding liquid crystal were adhered with chlorinated polypropylene. Next, it was surrounded by a polyester film with a thickness of 16 μm, and then covered with another glass substrate provided with electrodes to produce a liquid crystal device.

The obtained liquid crystal device was evaluated and the following results were obtained. In other words, when no voltage is applied, it scatters light and is opaque.
When a 60 Hz sinusoidal AC voltage of 10 V was applied, scattering decreased and the film began to become transparent, and at a voltage of 40 V, the transparency reached almost a saturated state.

I left it indoors for a month, but no changes occurred in its appearance or performance.

Comparative Example 1 Polyethylene fine particles "Flow Beads" manufactured by Seitetsu Kagaku Kogyo Co., Ltd. LE-1080 (average particle size 5 μm) 1.5 g, P-type nematic liquid crystal ZLI-21441,5 manufactured by Merck & Co., Ltd.
g and 3.0 g of dioxane were mixed and stirred to prepare a mixed solution, which was then left to stand for defoaming. Pour this mixture into a gap of 50 μm.
Using an applicator set to
The dioxane was allowed to evaporate by leaving it in the oven for 3 minutes. When I took it out of the oven, it was about 20cm thick.
A layer of a suspension of μm liquid crystal and polyethylene fine particles was formed. A liquid crystal device was fabricated by surrounding the periphery with a 16 μm thick polyester film and covering it with another glass substrate provided with electrodes.

The obtained liquid crystal device was evaluated and the following results were obtained. In other words, when no voltage is applied, it scatters light and is opaque.
When a 60 Hz sinusoidal AC voltage of 10 V was applied, scattering decreased and the film began to become transparent, and at a voltage of 70 V, the transparency reached almost a saturated state.

However, after being left indoors for three days, cracks appeared in the display surface made of fine particles and liquid crystal.

Example 2 0.2 g of polyvinyl formal manufactured by Tokyo Chemical Industry Co., Ltd. was dissolved in 3.0 g of cyclohexanone, and polyamide fine particles 5P-500 (average particle size 5 μm) manufactured by Toshiku Co., Ltd. were added to this solution.
) 1.0g, p-type nematic liquid crystal "RO-" manufactured by Roche
0.8g of TN-403" was mixed and stirred to create a mixed solution, which was left to stand to defoam. This mixed solution was passed through a gap 25
It was applied onto a glass substrate equipped with a transparent electrode made of tin oxide and indium with an applicator set to 11 μm.
The cyclohexane was left in an oven set at 0° C. for 5 minutes to evaporate, and then cooled. In the process of evaporation of cyclohexanone, a porous film was formed in which polyamide fine particles with a thickness of about 15 μm holding liquid crystal were adhered with polyvinyl formal. Next, a polyester film with transparent electrodes made of tin oxide and indium oxide was covered to fabricate a liquid crystal device.

The obtained liquid crystal device was evaluated and the following results were obtained. In other words, when no voltage is applied, it scatters light and is opaque.
When a 60 Hz sinusoidal AC voltage of 10 V was applied, scattering decreased and the film began to become transparent, and at a voltage of 80 V, the transparency reached almost a saturated state.

I left it indoors for a month, but no changes occurred in its appearance or performance.

Example 3 Cross-linked polymethyl methacrylate fine particles MP-3100G (average particle size 1 μm) manufactured by Soken Kagaku Co., Ltd. 1°4 g 1 non-cross-linked polymethyl methacrylate fine particles MP-2701 (average particle size 0.4 μm) 0.6 g.

Merck p-type nematic liquid crystal “ZLI-2061”
3.2 g were mixed and stirred to form a suspension, which was degassed by decompression treatment. This suspension was dropped onto a glass substrate equipped with a transparent electrode made of tin oxide and indium oxide, surrounded by a 16 μm thick polyester film, and then covered with another glass substrate equipped with an electrode. C
A liquid crystal device was produced by heat pressing for 10 minutes.

The obtained liquid crystal device was evaluated and the following results were obtained. In other words, when no voltage is applied, it scatters light and is opaque.
When a 60 Hz sinusoidal AC voltage of 10 V was applied, scattering decreased and the film began to become transparent, and at a voltage of 100 V, the transparency reached almost a saturated state. I left it indoors for a month, but no changes occurred in its appearance or performance.

[Effects of the Invention] Since the liquid crystal device of the present invention is constructed as described above, the optical properties of the display surface are uniform over a large area, and since no water is used in the manufacturing process, ionic impurities are not mixed in. << has the advantage that deterioration of electrical characteristics is less likely to occur. Furthermore, the device of the present invention is opaque when no voltage is applied;
It has the function of becoming transparent when voltage is applied, and can be effectively used in display devices, light control glass, etc.

Patent applicant: Toshi Co., Ltd.

Claims (1)

[Claims] 1. A liquid crystal device comprising a porous polymer film holding a p-type nematic liquid crystal sandwiched between two electrodes, at least one of which is transparent, the liquid crystal device holding the p-type nematic liquid crystal. The porous polymer membrane comprises a p-type nematic liquid crystal, fine particles made of a polymeric substance that is insoluble in both the nematic phase and the isotropic phase of the p-type nematic liquid crystal, and a polymeric substance that is insoluble in the nematic phase of the p-type nematic liquid crystal. A liquid crystal device comprising a binder for adhering fine particles. 2. The refractive index of fine particles made of a polymer substance that is insoluble in both the nematic phase and the isotropic phase of a p-type nematic liquid crystal is 1.
4. The liquid crystal device according to claim 1, which has a molecular weight of 46 to 1.56. 3 Fine particles made of a polymer substance insoluble in both the nematic phase and the isotropic phase of the p-type nematic liquid crystal are at least one selected from polyethylene, polypropylene, polyamide, polyacrylonitrile, polyvinyl alcohol, and cellulose, or contain ethylene in the main chain. ,propylene,
The liquid crystal device according to claim 1, which is a copolymer containing at least one structural unit of acrylonitrile and vinyl alcohol. 4. The liquid crystal device according to claim 1, wherein the fine particles made of a polymeric substance that is insoluble in neither the nematic phase nor the isotropic phase of the p-type nematic liquid crystal are three-dimensionally crosslinked polymeric substances.