JPH0812362B2 - Optical element dispersion and method for producing the same - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to a dispersion for an optical element used for a light valve, a display device, a dimming window and the like, and a method for manufacturing the dispersion, and in particular, anisotropic colored particles are dispersed in an insulating medium to generate an electric field. The present invention relates to a dispersion for an optical element in which a color change is caused by applying a voltage to change the orientation of the particles, and a method for manufacturing the dispersion.

[Prior art]

Anisotropic particles are dispersed in a medium, and an electric field or magnetic field is applied to this to change the orientation of the particles to control optical characteristics such as light transmittance and reflectance. The principle itself has long been known (see, for example, US Pat. No. 1,955,923). A typical optical element using such a principle is
This will be described with reference to the accompanying drawings. As is apparent from FIG. 1, this optical element 1 is obtained by encapsulating a dispersion 4 in which particles 2 having a shape or optical anisotropy are dispersed in an insulating liquid medium 3 in a cell 5. It is configured. The cell 5 consists of a transparent plate 2
The electrode support plates 6 and 6 are made to face each other with a small space therebetween, and the periphery thereof is sealed by a sealing material 7. It is coated. An electric field is applied between the electrodes 8 and 8 by an external power supply 9. In the optical element 1 configured as above, the electrodes 8,
When an alternating current or a pulsed electric field is applied between 8, the orientation of the anisotropic particles 2, 2, ... In the dispersion 4 changes, and the light transmittance changes. That is, the particles 2 in the medium 3 have a positive or negative surface charge, and when the electric field is not applied, they are dispersed by the electric repulsive forces of each other, so that the light is a large number of particles oriented in random directions.
The optical element 1 becomes opaque because it is absorbed or scattered by 2, 2, ... But when an electric field is applied, the particles 2 are oriented in a direction parallel to the electric field, that is, in the thickness direction of the cell 5, Since the light easily passes through, the optical element 1 becomes transparent. Therefore, by using this optical element 1, it is possible to obtain a light valve, various display devices, a dimming window, or the like. In that case, if the particles 2 or the medium 3 are colored, various color tones can be obtained. By the way, in such an optical element for controlling the optical characteristics by changing the orientation of the particles, as a dispersion thereof,
Particles whose orientation changes and color tone changes when an electric field is applied,
It is necessary to use one dispersed in the medium. The main known materials for such particles are organic crystals such as herapasite and cinchonidine periodate sulfate, metals such as aluminum, mineral crystals such as mica, titanium oxide and tungsten oxide. Such as various inorganic oxides.

[Problems to be Solved by the Invention]

However, in the case of such an optical element, since the change of the color tone depends on the optical properties of the anisotropic particles, the color tone of the one using the dispersion of the particles of the conventional material is It will be limited to pearl or blue color. That is, in the case where particles of aluminum, mica, or titanium oxide are dispersed in the medium, the fact that the scattering of light changes depending on the orientation of the particles is used, so it is not transparent when an electric field is applied. Sometimes it is pearly. In this case, since scattering increases as the refractive index of the particle increases, it is also proposed to coat the surface of the particle with titanium oxide to improve the light control performance (see U.S. Pat.No. 3,257,903), Even if you do so, the color tone will not change. Further, since herapasite and cinchonidine periodate sulfate exhibit blue or bluish purple, the dispersion in which the particles are dispersed becomes transparent when an electric field is applied and has a blue color tone when not applied. Thus, in the case of an optical element that controls the optical characteristics by changing the orientation of the particles, the change in color tone is determined by the optical characteristics of the particles, so in order to obtain the desired color, It is necessary to use anisotropic particles having a tone matching the color. In that case, the particles are required to have various functions such as shape anisotropy, specific gravity, chemical stability, and dispersion stability, in addition to the color tone. It is extremely difficult to find particles that satisfy all such functions. In particular, in order to use it in an optical element that controls the optical characteristics by changing the orientation of particles by an electric field, it is required to make a large number of fine particles having an aspect ratio of 2 or more, preferably 7 or more. However, it is generally difficult to obtain particles having an aspect ratio of 5 or more by mechanical pulverization, except for layered crystals such as montmorillonite and vermiculite. Therefore, the conventional optical element has a problem that a desired color cannot be obtained. As an optical element that is similar in appearance but based on a different principle, there is one that uses electrophoresis. In that case, a DC electric field is applied, and the particles move by migration and collect on the electrode surface, thereby changing the color tone of the element. Even in such an optical element, it is desired to use particles of various color tones. The present invention has been made in view of such circumstances, and an object thereof is to provide a dispersion for an optical element, which can be an optical element exhibiting various color tones. Another object of the present invention is to provide a production method by which such a dispersion can be easily obtained.

[Means for Solving the Problems]

In order to achieve this object, the present invention focuses on a group of crystals called host crystals that are colored or discolored by incorporating an inorganic or organic ion, atom, molecule, or dye as a guest into the crystal. The anisotropic colored particles of crystals are dispersed in a medium to form a dispersion for an optical element. The anisotropic particles are obtained by connecting fine particles of a host crystal in a chain shape to form needle-like particles having a length within a predetermined range, or by cutting a layered crystal fiber into a length within a predetermined range. It is something that can be obtained. Some clay minerals, graphite, chalcogen compounds and the like have a layered crystal structure in which unit crystal layers are laminated. In the case of such a layered crystal, the bonding force between the crystal layers is relatively weak and the interlayer distance can be expanded or contracted to a considerable extent, so that various ions or molecules can be inserted between the layers without destroying the crystal structure. . Such a crystal is called a host crystal, and the ion or molecule to be inserted is called a guest. The host crystal is not necessarily a crystal having a layered structure, and there are some crystals in which the position where the guest enters, that is, the site, forms a three-dimensional network. For example, zeolite and tungsten oxide are typical ones. In the present invention, as the host crystal, montmorillonite, hydelite, clay mineral crystals such as vermulite, FeOCl, VOCl, metal oxyhalides such as TiOCl, titanium sulfide, chalcogenides such as molybdenum sulfide, zirconium phosphate, tungsten oxide. However, the host crystal is not limited to these and may be any host crystal having a site capable of accommodating a guest. For example, when using an inorganic ion as a guest, a group of crystals known as inorganic electrochromic crystals such as iridium oxide, molybdenum oxide, vanadium oxide, β-ZrNCl, graphite, zeolite, etc. should also be used as the host crystal. You can When a dye is used as the guest, montmorillonite, which absorbs various dyes in a large amount, is most preferable. The present invention is one in which such host crystals are anisotropic particles having a major axis length of 0.1 to 10 μm, preferably 0.3 to 1 μm, and an aspect ratio of 2 or more, preferably 7 or more. It is used for the dispersion of. Inorganic ions used as guests are hydrogen ions,
Examples are lithium ion, sodium ion, potassium ion and the like. Organic molecules include amines, pyridines and amino acids. Since the color tone of the host crystal does not change significantly even if the type of ion is changed, the ion used is appropriately selected within the range allowed by the crystal. The dye used as a guest includes a cationic dye and an anionic dye. The type of dye is appropriately selected according to the color tone required for the optical element. The dispersion of the present invention is a dispersion in which anisotropic colored particles of host crystals incorporating such guests are dispersed in a medium. In that case, two or more kinds of particles colored in different colors may be mixed and dispersed. Further, the medium may be colored by adding a dye in advance. Insulating oil such as silicone oil or fluoropolymer oil is used as the medium. In that case, a plurality of types of media having different specific gravities and viscosities may be mixed and used, and a surfactant may be added. When the particles are made of a conductive material, it is desirable to apply an insulating coating on the surface thereof. Further, in order to enhance the contrast of coloration / decoloration, the surface of the particles may be coated with a metal or a metal oxide. Next, regarding the method for producing the dispersion according to the present invention,
This will be described more specifically. There are several methods for obtaining anisotropic grains of host crystals. For example, since montmorillonite is a crystal contained in natural clay, in order to obtain anisotropic particles thereof, clay mineral crystals may be purified, fractionated, and selected in a size within a predetermined range. However, from the viewpoint of purity and shape control, it is desirable to artificially synthesize crystals. There are several methods for synthesizing such host crystals.
For example, crystals can be obtained by mixing metal salts such as sulfates, nitrates, phosphates, and carbonates or metal halides at an appropriate ratio and sintering in an atmosphere containing oxygen. Further, it is also possible to dissolve these metal salts or halides in sodium hydroxide and form crystals by hydrothermal synthesis. Furthermore, by mixing fine particles of metal oxide,
The host crystal can also be obtained by sintering at a high temperature. Others, such as synthetic mica, can be produced by the melt solidification method. Crystals having a layered structure have a remarkably small bonding force between layers as compared with other crystal planes, so if a large crystal thus obtained is mechanically crushed with a ball mill or the like,
It easily becomes plate-shaped, flaky, or rod-shaped particles. However, it is generally difficult to obtain particles having an aspect ratio of 5 or more by such mechanical pulverization, except for layered crystals such as montmorillonite and vermiculite. Therefore, in the present invention, such host crystal fine particles are connected in a chain shape to form particles that can be substantially regarded as needle-like particles. However, due to the function of the optical element in which the dispersion of the present invention is used, the particles are not necessarily linear and may have a two-dimensional spread. In order to produce such chain-like particles, a coprecipitation method, a hydrothermal synthesis method, or a vapor phase synthesis method, which is one of liquid phase methods, can be used. For example, a low-density sintered body obtained by mixing metal oxides and metal salts, calcining them, mechanically crushing them, and then sintering at a relatively low temperature, resulting in non-uniform aggregation of the particles and sintering. Is obtained. Such a state is not preferable when producing a sintered solid, but if this is again pulverized and separated, a chain in which several or more particles are linked can be obtained. Further, chelating hydroxycarboxylic acid with a metal salt, heating and stirring in a mixed solution of an organic acid such as citric acid and a polymer such as ethylene to cause precipitation.
A fine chain can also be produced by similarly calcining, crushing, sintering, and crushing the obtained precipitate. Furthermore, when the host crystal is a simple compound such as an oxide or sulfide such as tungsten oxide or titanium sulfide, a chain can be easily formed by a gas phase reaction such as a gas evaporation method. Depending on the aspect ratio
Ten or more particles can be obtained. The chain-like particles thus obtained are fractionated by a means such as centrifugation or a sedimentation method, and 0.1 to 10 microns,
Desirably, a length of 0.3 to 1 micron is collected.
By such a method, it is possible to easily prepare anisotropic particles that can be used in the dispersion of the present invention, even if the host crystal has a three-dimensional structure in which it is difficult to obtain anisotropic particles by mechanical pulverization. it can. Also, anisotropic particles can be formed by the fibers of the host crystal. For example, graphite whiskers can be made by heat treating carbon fibers at high temperatures of 2800 ° C and above. Then, by cutting it into a length within a predetermined range, fibrous anisotropic particles can be used in the dispersion of the present invention. Next, the guest is inserted into the anisotropic particles of the host crystal thus obtained. The type and amount of guests that can be inserted into a crystal site depends largely on the charge and size of the guest, but there is considerable freedom. It is also known that guests perform so-called ion exchange, which replaces the ions in the surrounding medium. Therefore, there are several ways to do this. For example, in the case of graphite, if it comes into contact with potassium vapor, potassium will enter between the layers. Also, in the case of molybdenum oxide or tungsten oxide, hydrogen ions or lithium ions can be inserted by precipitating the particles with a centrifuge, placing them on an electrode, and performing electrolytic reduction in an acid or lithium-based electrolytic solution. it can. Montmorillonite and β-Zr
When NCl is pickled and immersed in an electrolyte solution, cations are absorbed between layers. A method of coloring montmorillonite with a cationic dye is disclosed in Japanese Examined Patent Publication No. 50-8462. Also, a method of coloring with an anionic dye is disclosed in JP-A-63-9.
No. 0573 publication. Of these methods, an appropriate method may be selected depending on the properties of the host crystal. If the colored particles form clusters, these are filtered, washed with water, dried, and then mechanically or ultrasonically ground, stirred in a dispersion medium, or ultrasonically vibrated. To give particles again. The above-mentioned method is a method of coloring the host crystal after the size of the host crystal within a predetermined range. However, when anisotropically colored particles are obtained from the fibers of the layered crystal, it is necessary to obtain the desired particle size after coloring. You can also In that case, the guest may be absorbed in advance by the host crystal forming the fiber to form the colored fiber, and the colored fiber may be cut into a length within a predetermined range. The anisotropic particles colored in this way are added to an insulating medium such as silicon oil or fluorine-based polymer oil while stirring and uniformly dispersed. In order to make the dispersion uniform, it is necessary to balance the specific gravity of the particles with the specific gravity of the medium and to optimize the viscosity of the medium.To do this, mix oils with different specific gravities and viscosities. Can be used. To make the dispersion more preferable, a surfactant can be added as a dispersant. As the surfactant, a high-molecular-weight activator is effective, and among them, a graft polymer or a block polymer of a hydrophilic monomer and a hydrophobic monomer is preferable. To obtain an optical element that has a fast response to an electric field,
It is advantageous for the medium to have low viscosity, but from the viewpoint of element manufacturing technology, it is preferable that the medium has high viscosity so that it can be applied. In order to achieve both of these, it suffices to disperse particles obtained by dispersing particles in the low-viscosity first medium into the high-viscosity second medium by stirring and mixing. In that case, for example, halocarbon oil # 0.8 / 100 manufactured by Halocarbon Products can be used as the first medium, and # 11/4 or # 11/21 can be used as the second medium. Alternatively, silicon oil may be used as the first medium, and the mixture may be added to the mixed solution of polyethylene glycol and hexamethylene diisocyanate with strong stirring using a catalyst, and heated when the emulsion is formed. By doing so, ethylene glycol and hexamethylene diisocyanate are solidified by the polymerization reaction. That is, the polymer becomes the second medium. Such a polymerization reaction can also be carried out after encapsulating the dispersion in the cell of the optical element. Furthermore, it is also possible to microencapsulate the dispersion material dispersed in the first medium and disperse it in the second medium. A well-known technique can be used as the method for microencapsulation. For example, when a mixed aqueous solution of polyvinyl alcohol and sodium silicate and a dispersion containing halocarbon oil yl # 0.8 / 100 as the first medium are left to stand at room temperature with stirring and mixing, a composite of polyvinyl alcohol and sodium silicate is formed. Microcapsules with body walls are formed. Therefore, the capsule is filtered and dried, and then mixed with halocarbon oil # 11/21 as the second medium. Thereby, an encapsulated composite medium can be obtained. When the dispersion thus obtained is used for an optical element, the particles in the medium have a positive or negative surface charge, so that when the electric field is not applied, the dispersion is maintained by mutual electric repulsion. However, they move in the medium when an electric field is applied. Therefore, particles near the electrode may collide with the electrode and lose the charge. In such a state, even if the direction of the electric field is reversed, the particles cannot be separated from the electrode and remain attached. Such a tendency becomes more remarkable in the case of particles of a conductive substance such as graphite, titanium sulfide, or tungsten oxide. In such a case, the surface of the particles may be coated with an insulating material. By doing so, the movement of electric charges is hindered, so that the adhesion of particles is effectively prevented. The insulating material that can be easily used in that case is a polymer, but is not limited to this. As a method for coating the surface of the particles with the polymer, a microcapsule method can be used. As one example, there is a coating method using an ethylene copolymer as disclosed in JP-A-62-183439. Since the optical properties of the particles coated on the surface change, the color tone also changes delicately. Therefore, in order to improve the optical properties of the particles, the surface of the particles can be coated with various substances such as metals and metal oxides. For example, a metal film coating is suitable for increasing the reflectance of particles and enhancing the contrast of coloration and decoloration due to scattering. A known method can be used for coating the surface of the particle with a metal film. For example, in the case of coating with silver, it is possible to employ a method in which the particles are added to an aqueous solution of silver nitrate with stirring and the silver is deposited on the surface of the particles by photoreduction. Also, nickel can be deposited by directly applying the technique of electroless nickel plating to ceramics. Such particle surface coating is performed after the anisotropic colored particles are formed and before they are dispersed in the medium.

[Action]

The optical properties of the host crystal change greatly depending on the guest contained therein, and the color tone also changes considerably. For example, graphite containing potassium as a guest exhibits golden color, blue color, and black color depending on its concentration. In addition, when hydrogen ions or lithium ions are inserted as a guest in tungsten oxide, it is colored transparent to blue. others,
When hydrogen ions are inserted into iridium oxide, the color changes from dark blue to colorless, and when hydrogen ions are inserted into molybdenum oxide, the color changes from pale yellow to blue and then to brown. When hydrogen ions are inserted into vanadium oxide, the color changes from yellow to green and then to blue. When lithium ion is inserted into β-ZrNCl, the color changes from pale yellowish green to black. These are a group of crystals known as inorganic electrochromic crystals. Since most of them are transition metal oxides, even if the kind of ions to be inserted is changed, the color tone does not change so much. For example, in the case of tungsten oxide, the same blue color is exhibited regardless of whether the guest is hydrogen ion or lithium ion as described above. Therefore, the type of ion can be freely selected to some extent within the range allowed by the crystal. Generally, hydrogen ions, lithium ions, sodium ions, and potassium ions are easily inserted in this order. The layered crystal into which the inorganic ion can be inserted is not limited to the electrochromic crystal as described above. In the case of the dispersion according to the present invention, the guest is not taken in and out of the crystal, and the contrast is achieved by the orientation of the particles. Therefore, even if the crystal structure is distorted due to the large ionic radius, Even if the contrast at the time of erasing is low, it can be used as long as it has a desired color tone as particles. In order to obtain a dark color tone, it is necessary to increase the guest concentration. Since a small guest can be inserted at a high concentration without destroying the crystal structure, an inorganic ion is preferable to a molecule or an organic ion. However, if the crystal has a large site for the guest, even a guest having a large size such as an organic ion of an anion dye or a cationic dye can be inserted at a high concentration. For example, one type of clay mineral, montmorillonite,
It can be colored red with the cationic dye rhodamine, yellow with auramine, purple with crystal violet and blue with cyanine. However, it is considered that the coloring mechanism is different between the case of coloring with a dye and the other case. In other words, when colored with a dye, the dye itself causes coloring, but in other cases, by incorporating ions, atoms, or molecules into the crystal as guests, the energy state of electrons of metal atoms in the crystal is changed. The change causes color development. In this way, colored particles having various color tones are obtained. The length of the major axis of the host crystal colored in this way is 0.
When dispersed in a medium, anisotropic particles having a size of 1 to 10 μm and an aspect ratio of 2 or more change the orientation due to the electric field and change the optical characteristics. If the particles are significantly smaller than the wavelength of visible light, the light will not be absorbed and light control will be impossible. In addition, it is technically difficult to produce crystals with a length of 0.1 micron or less. On the contrary, when the size of the particles exceeds 10 microns, it becomes difficult to stably disperse the particles in the medium. Moreover, since the response to the electric field is lowered, it becomes impossible to obtain the performance required as the optical element. Further, particles having an aspect ratio of 2 or less have a low color change contrast, and cannot be used as a practical optical element. Therefore, it is desirable that the particle size is within the above range. More preferably, the particles have a major axis length of 0.3 to 1 micron and an aspect ratio of 7 or more. Such anisotropic particles can be easily obtained by connecting fine particles of host crystals in a chain shape as in the present invention, or by using a layered crystal fiber. When a dispersion in which such colored particles are uniformly dispersed in a medium is injected into the cell as described in FIG. 1 and an AC voltage is applied, the colored state of the particles changes to transparent. When the medium is colored in advance, the color of the medium and the color of the particles are mixed in the off state, but the color of the medium is displayed in the on state. Also, when particles colored in different colors are mixed and dispersed, an optical element exhibiting the mixed color is obtained.

【Example】

Examples of the present invention will be described below. (Example 1) Tungsten was placed in an atmosphere having a higher oxygen pressure than ordinary vacuum vapor deposition, and a gas phase reaction was forced to occur to form a chain in which fine particles of tungsten oxide were aggregated. The obtained chains were classified by a centrifuge, and those having a length of 0.1 to 10 microns were selected. This chain was fixed to an electrode, and the counter electrode was used as a positive electrode, and electricity was applied in dilute hydrochloric acid. Then, the chain-like particles incorporated hydrogen ions between the crystal layers, and changed from pale yellow, which was almost transparent, to blue. Therefore, when all the particles turned blue, the power supply was stopped, the particles were collected, washed with water, and dried. The surface of the thus obtained chain-like particles is coated with an ethylene-based copolymer, and the particles are
Add to the medium of silicone oil while stirring,
Dispersed evenly. In order to improve the dispersion, a surfactant composed of a graft polymer of a hydrophilic monomer and a hydrophobic monomer was mixed. Then, this dispersion was injected into a cell as shown in FIG. 1, and an AC voltage of 100 V was applied from a commercial power source through a switch. The optical element exhibited a blue color in an off state in which no electric field was applied, and became transparent in an on state in which an electric field was applied. Moreover, no aggregation of particles was found on the electrode surface of the optical element. (Example 2) Using tungsten as an electrode, arc discharge was performed in an oxygen atmosphere to form a chain made of fine particles of tungsten oxide. Then, the chain-like particles were classified in the same manner as in Example 1 and heated to 40 ° C. in a normal butyllithium solution dissolved in hexane. In this case, lithium ions were taken in between the crystal layers, but the color of the particles was the same as in Example 1.
It was similar to the case of. The particles were dispersed in halocarbon oil # 0.8 / 100, and the dispersion was further dispersed in halocarbon oil # 11/4. Then, the dispersion was applied to two glass plates coated with a transparent electrode film to prepare an optical element as shown in FIG. Also in this case, the same result as in Example 1 was obtained. (Example 3) Carbon fibers were prepared by a conventional method and then heat-treated at a high temperature of 2800 ° C or higher to obtain graphite whiskers. Then, it was mechanically cut into fibers having a length of 0.1 to 10 microns. This fiber was vacuum-sealed together with potassium powder and heated at a high temperature above the melting point of potassium to bring potassium vapor into contact with the fiber. The color of the fibrous particles changed to blue and then to gold as potassium penetrated between the graphite layers. When all the particles became golden, the heating was stopped and the particles were taken out. The particles were exposed to air for a while to change the potassium adhering to the surface to potassium hydroxide and potassium carbonate, and then they were dissolved in water to remove excess potassium. The obtained fibrous particles were dispersed in the same medium as in Example 1 and injected into the cell, and the same experiment was conducted. In this case, the optical element was gold in the off state and transparent in the on state. (Example 4) A hydroxycarboxylic acid was chelated with a metal salt of titanium and heated in a mixed solution of citric acid and ethylene with stirring to cause precipitation. The obtained precipitate was calcined, once pulverized by a ball mill, then sintered at a relatively low temperature, and pulverized again. The particles thus obtained were chain-shaped in which several fine particles of titanium oxyhalide were connected. The particles thus obtained are washed with 2% hydrochloric acid,
After activation, it was washed with water. Then, it was added to the aqueous solution in which the cationic dye auramine was dissolved while stirring. As the dye was absorbed by the particles, the supernatant liquid became transparent, so more dye was added and stirring continued. Thus, the dye was added until the color change of the supernatant liquid disappeared, and the coloring was completed when the color change disappeared. After this treatment, the particles were filtered off, washed with water and dried. The obtained particles were colored yellow. The chain-like colored particles are separated by the sedimentation method,
Those of 0.1-10 micron size were collected. The particles were mixed with the particles obtained in Example 1 and dispersed in the same medium. When a similar optical element was formed using the dispersion in which the mixed particles were dispersed, an optical element exhibiting a green color which was a mixed color of the particles was obtained. Example 5 Chain-like particles of tungsten oxide were prepared in the same manner as in Example 1 and fractionated to obtain particles having a length of 0.1 to 10 μm. The particles were activated in the same manner as in Example 4, washed with water, and then added to an aqueous solution in which crystal violet of the cationic dye was dissolved while stirring. When this was treated in the same manner as in Example 4, chain-like particles colored in purple were obtained. The particles were dispersed in halocarbon oil # 0.8 / 100, and the dispersion was allowed to stand at room temperature with stirring and mixing in a mixed aqueous solution of polyvinyl alcohol and sodium silicate. As a result, microcapsules encapsulating the particles and halocarbon oil were obtained. Therefore, the capsule was filtered, dried, and then mixed with halocarbon oil # 11/21. Using this dispersion, an optical element was formed in the same manner as in Example 2. Thereby, an optical element exhibiting a purple color could be obtained.

【The invention's effect】

As is clear from the above description, according to the present invention, since the host crystal is made to absorb an inorganic or organic ion, an atom, a molecule, or a dye as a guest, particles exhibiting various colors can be obtained. it can. Moreover, the crystal can be easily made into an anisotropic particle by connecting fine particles in a chain or by forming a layered crystal fiber and cutting the fiber. Therefore, an optical element exhibiting a desired color can be obtained by using it as a dispersion in which it is dispersed in a medium and using the dispersion as an optical element.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view showing an example of an optical element in which the dispersion according to the present invention is used. 1 ... Optical element, 2 ... Anisotropic particle, 3 ... Medium, 4 ...
... Dispersion, 5 ... Cell, 8 ... Electrode

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-64-57242 (JP, A) JP-A-54-64644 (JP, A) JP-A-2-118619 (JP, A) JP-B-49- 22665 (JP, B1) Japanese Patent Publication 2-17009 (JP, B2)

Claims (16)

[Claims] 1. A dispersion used in an optical element for controlling the optical characteristics by changing the orientation of the particles by applying an electric field to the dispersion in which anisotropic particles are dispersed in an insulating medium. The anisotropic particles are needle-like particles formed by connecting fine particles of a host crystal in a chain shape, and the host crystal forming the needle-like particles has inorganic or organic ions or atoms as guests, Alternatively, a dispersion for an optical element is characterized in that a molecule is inserted. 2. A dispersion used in an optical element for controlling the optical characteristics by changing the orientation of the particles by applying an electric field to the dispersion in which anisotropic particles are dispersed in an insulating medium. The anisotropic particles are composed of needle-like particles formed by connecting fine particles of host crystals in a chain shape, and a dye is inserted as a guest into the host crystals constituting the needle-like particles. A characteristic dispersion for optical elements. 3. A dispersion used in an optical element for controlling the optical characteristics by changing the orientation of the particles by applying an electric field to the dispersion in which anisotropic particles are dispersed in an insulating medium. A dispersion for an optical element, characterized in that the anisotropic particles are composed of layered crystal fibers, and inorganic or organic ions, atoms, or molecules are inserted as guests in the host crystals constituting the fibers. body. 4. A dispersion for use in an optical element for controlling the optical characteristics by changing the orientation of the particles by applying an electric field to the dispersion in which anisotropic particles are dispersed in an insulating medium. A dispersion for an optical element, characterized in that the anisotropic particles are composed of a layered crystal fiber, and a dye is inserted as a guest into a host crystal constituting the fiber. 5. The dispersion for an optical element according to claim 1, wherein the anisotropic particles are made of a conductive substance, and the surface of which is coated with an insulating coating. 6. The dispersion for an optical element according to claim 1, wherein the surface of the anisotropic particles is coated with a metal or a metal oxide. 7. The dispersion for an optical element according to claim 1, wherein two or more kinds of the anisotropic particles are dispersed in the medium. 8. The dispersion for an optical element according to claim 1, wherein the medium is colored. 9. The dispersion for an optical element according to claim 1, wherein the medium is a mixture of two or more kinds of insulating oil. 10. The dispersion for an optical element according to claim 1, wherein the medium comprises an insulating oil and a surfactant. 11. A method for producing a dispersion used in an optical element for controlling the optical characteristics by changing the orientation of the particles by applying an electric field to the dispersion in which anisotropic particles are dispersed in an insulating medium. A step of connecting the host crystal fine particles in a chain form to form needle-shaped particles, a step of separating the obtained particles to obtain anisotropic particles having a length within a predetermined range, and the anisotropy thereof. And a step of absorbing inorganic or organic ions, atoms, molecules, or a dye as a guest in a host crystal forming the particles, and a step of dispersing the obtained anisotropic colored particles in an insulating medium. A method for producing a dispersion for an optical element. 12. A method for producing a dispersion used in an optical element for controlling the optical characteristics by changing the orientation of the particles by applying an electric field to the dispersion in which anisotropic particles are dispersed in an insulating medium. A step of forming a layered crystal fiber, a step of cutting the fiber into a length within a predetermined range to obtain anisotropic particles, and an inorganic or organic compound as a guest in the host crystal forming the anisotropic particles. And a step of absorbing the anisotropic colored particles obtained in an insulative medium, and a step of absorbing the ions, atoms, molecules, or dye. 13. A method for producing a dispersion used in an optical element for controlling the optical characteristics by changing the orientation of the particles by applying an electric field to the dispersion in which anisotropic particles are dispersed in an insulating medium. A step of forming a layered crystal fiber, a step of allowing a host crystal constituting the fiber to absorb an inorganic or organic ion, atom, molecule, or dye as a guest, and the obtained colored fiber within a predetermined range. A method for producing a dispersion for an optical element, comprising: a step of cutting into anisotropic length to obtain anisotropic colored particles; and a step of dispersing the anisotropic colored particles in an insulating medium. 14. In the step of dispersing the anisotropic colored particles in a medium, the particles are first dispersed in a first medium and then dispersed in a second medium having a higher viscosity. 14. The method for manufacturing a dispersion for an optical element according to claim 11. 15. The step of dispersing the anisotropic colored particles in a medium, wherein the particles are first dispersed in a first medium, and then microencapsulated and dispersed in a second medium. The method for producing an optical element dispersion according to any one of claims 11 to 13. 16. The dispersion for an optical element according to claim 11, wherein a surface of the anisotropic colored particles is coated before being dispersed in a medium. Production method.