JP2002099005A - Rotating particles for display, its manufacturing method and sheet type display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide rotating particles capable of reducing the energy and the applied voltage for rotating and/or being manufactured in a simple and easy way in large quantities into stable shape, that are useful for a sheet type display device. SOLUTION: The rotating particles are manufactured by sealing a liquid into a microcapsule 11 which has areas of different in both of color and electrostatic charge characteristics. Another rotating particle is manufactured by moving one of the two types of coloring agents contained in a wax or a resin particle and localizing it in the particle to form two areas of different colors. The coloring agents are moved by magnetophoresis, electrophoresis or sedimentation. The other rotating particle is manufactured by filling two materials of different colors and electrostatic charge characteristics into a through-hole formed through a molding sheet to combine the two materials into a combination and molding the combination into a sphere.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet-type display device for displaying an image by rotating and turning particles having two regions having different colors and electric characteristics by an electric field. Rotating particles necessary for image display in a simple display device.

[0002]

2. Description of the Related Art In recent years, with the development of portable information terminals and advanced information communication networks, attention has been paid to the development of thin, lightweight, and highly portable display devices. Among them, a display device having a function of changing the optical absorption characteristics and optical reflection characteristics by an electric field to display an image and having the same flexibility as paper and a function of easily rewriting electronic information, so-called electronic paper, Expectations for display devices called paper-like displays, digital paper, and the like are increasing.

As an element used in such a display device, which changes optical absorption and optical reflection by an electric field, a rotating particle composed of hemispheres having different colors and electric characteristics is included together with a dielectric liquid. Microcapsule, as described in JP-A-1-86116, a solvent in which electrophoretic particles are dispersed is colored, and a microcapsule containing the solvent, a liquid crystal / polymer composite containing a dichroic dye and a smectic liquid crystal Films and the like are known. These elements are
It has features such as a memory that can hold image clearing information without a power supply, and when used in a display device, it is used as a reflective display device. To be thin, light,
It is possible to provide a sheet-type display device which can be bent and is expected as a substitute for paper.

[0004] In particular, the display medium described in US Pat. Nos. 4,126,854 and 4,143,103 using hemispheres of rotating particles divided into different colors and charging characteristics is of another type. The display is known as a display exhibiting excellent contrast characteristics. FIG.
As shown in FIG. 1, this display medium has a structure including a substrate 3 which is an optically transparent layer, and rotating particles 1 filled in a plurality of voids provided in the substrate 3 together with a dielectric liquid 2. ing. Since the rotating particles 1 have two regions 1a and 1b having different colors and different charging characteristics as shown in the drawing, when an electric field is applied, the rotating particles 1 are shown in a series of figures in FIGS. 2 (a) to 2 (c). As described above, the image display can be performed by changing the direction by performing the electrophoresis and rotating motion.

[0005] The method and material for producing the rotating particles (bicolor rotating particles) consisting of two colors of hemispheres are as follows: (1) US Pat. No. 5,262,098 binds two types of molten wax particles having different colors. , A method of solidifying after making it spherical by surface tension (examples of materials used in this method are:
Carnauba wax, carbon black, titanium oxide, etc.), (2) JP-A-11-85067 and JP-A-1
1-85068, a method of depositing or coating metal, carbon black, antimony sulfide, or the like on the surface of light-transmitting particles (the particle material in this method is glass or resin), and (3) JP-A-11-85069. JP-A-11-161206 and JP-A-11-161206, in which particles made of a photosensitive material are used to form a color by exposure, development, and fixing (examples of materials used in this method include zinc oxide (color former: toner), hydrophilic Water-soluble polymer (color former: silver halide)) and the like.

[0006] Further, as a method of easily producing two-color rotating particles, a resin particle formed by directly cutting a resin film having a two-layer structure having different colors and charging characteristics on the front and back to a particle size is used. A method of forming a sphere by a surface tension in an appropriate liquid (Japanese Patent Laid-Open No. 1-282589) is also known.

[0007]

However, conventionally used rotating particles are mainly composed of resin, glass and the like, and generally have a specific gravity of 1 or more. Even when a wax having a small specific gravity is used, titanium dioxide having a specific gravity of 3.9 to 4.3 needs to be contained inside the rotating particles in order to display high whiteness. And its mass also increases.

The energy K required for the rotation of a particle is related to the moment of inertia I and the angular velocity ω, which are proportional to the mass of the particle, as follows:

[0009]

(Equation 1)

Therefore, as the mass of the particles increases, the energy K required for the rotation of the particles increases, and accordingly, the power consumption accompanying the rotation of the particles increases.

Further, in the case of particles having a large mass, the sedimentation speed of the particles, which hinders the movement of the particles by electrophoresis, increases, so that the applied voltage for displaying an image increases. That is, (1) elements for performing image display are limited to those capable of withstanding a high applied voltage, and (2)
A problem arises in that a large power supply is required to realize a high applied voltage.

On the other hand, in the method of US Pat. No. 5,262,908, which is capable of producing a large amount of two-color particles, molten wax is injected by centrifugal force using a rotating disk and solidified by air cooling. Since it is affected by the size and the ambient temperature, there are problems that the shape of the manufactured particles is not stable and the yield of desired particles having different colors for each hemisphere is low. Also, JP-A-11-85067 and JP-A-11-850 for producing two-color particles by vapor deposition
The method disclosed in JP-A-68-68 has a problem that the number of devices that can be manufactured at one time is small and the productivity is low from the viewpoint of the time required to reach the degree of vacuum required for vapor deposition. JP-A-11-8
In the case of using the photosensitive material disclosed in Japanese Patent No. 5069 or Japanese Patent Application Laid-Open No. 11-161206, a step of applying a hydrophilic polymer containing a toner or silver halide to the surface of a particle having a particle size of about 100 μm as a uniform and thin film is required. Therefore, its productivity is still a problem.

Further, the two-color rotating particles produced by the above method are usually dispersed in a carrier medium such as silicone rubber,
The display is switched by rotating the two-color particles by applying an electric field. Therefore, the dispersion state of the two-color rotating particles greatly affects the resolution and brightness of the display device, and therefore, it is necessary to uniformly disperse the rotating particles having a controlled particle size.

According to a method of directly forming a resin film having a two-layer structure into a particle size by molding and spheroidizing a resin film in an appropriate liquid by surface tension (Japanese Patent Application Laid-Open No. 1-282589), the resin film has an uneven thickness. Cracks are formed in the produced particles, or burrs are formed on the particle ends, and it is difficult to obtain rotating particles having the same particle size and different colors each by a hemisphere due to uneven hardness and the like. .

An object of the present invention is to provide a rotating particle for display which reduces energy required for rotation and applied voltage and enables a more compact display device. Another object of the present invention is that it can be manufactured easily and in large quantities,
Moreover, it is to provide a rotating particle for display having a stable shape. It is also an object of the present invention to provide a sheet-type display device using the rotating particles of the present invention.

[0016]

According to the present invention, in a first aspect, a liquid is encapsulated in a microcapsule having a surface on which both color and electric characteristics, particularly charging characteristics, are different. It is intended to provide a display rotating particle characterized by the above. The particles enable image display by rotating the particles under the action of an electric field externally applied to the layer containing the particles.

Specifically, in the rotating particles, microcapsules made of a film mainly composed of a polymer material and containing a liquid having a smaller specific gravity than glass, titanium oxide, or the like are used as the rotating particles. By using a liquid having a low specific gravity as the liquid to be included, the specific gravity of the whole particles is reduced, and accordingly, the energy and applied voltage required for the rotation of the particles are reduced, and a display rotation that enables a more compact display device. The use of particles becomes possible.

This microcapsule is provided with a coloring layer in which a coloring agent such as a chargeable pigment is applied on a part, preferably half, of the surface by dip coating or spray coating. Since the color and charging characteristics of the microcapsules are different from the color and charging characteristics of the microcapsules themselves, they function as display elements.

It is also possible to form a two-color microcapsule by coloring a part, preferably half, of the film constituting the microcapsule in a color different from the color of the microcapsule itself. For example, by dispersing a colorant in a microcapsule during the manufacturing process, and then fixing the colorant in a film, a two-color microcapsule can be obtained. In this case, the film is immobilized with the colorant. Also functions as an agent.

As a method for obtaining microcapsules of two colors using a dispersion colorant, a colorant having a charge property or a colorant which is a magnetic substance is dispersed in a liquid, and a film of the microcapsule containing the liquid is contained. During or after the polymerization reaction for forming the polymer, the colorant in the microcapsule is electrophoresed by the action of an electric field or a magnetic field to localize in a half area of the spherical polymer film. It is valid.

Further, for forming microcapsules, W /
When the monomer is polymerized from the state of the O emulsion, that is, when the liquid inside the microcapsules is water, the surface of the colorant is subjected to a hydrophilic treatment so that the colorant is stably dispersed in the liquid even during the polymerization reaction. Since it continues, migration control by an electric field or a magnetic field becomes easy. Conversely, O /
When polymerizing from the W emulsion state, that is, when the liquid inside the microcapsules is an oily liquid, the same effect can be obtained by subjecting the surface of the colorant to a hydrophobic treatment.

In order to display a higher degree of whiteness with the above-described microcapsule-type rotating particles, it is effective to disperse a white pigment such as silica, titanium oxide, or alumina in the liquid inside the microcapsules. is there.

The above microcapsule-type rotating particles are:
It can be produced by a known method such as (1) coacervation method, (2) complex coacervation method, (3) interfacial polymerization method, (4) spray drying method, (5) soap-free emulsion polymerization method. it can. Preferably, an amide bond represented by the following chemical formula

[0024]

Embedded image

By using a polymerization method using a monomer having the above, ie, an interfacial polymerization method, particles having excellent mechanical strength can be easily obtained.

By storing the microcapsule type rotating particles in a plurality of voids provided on an optically transparent base material and filled with a dielectric liquid, a sheet type display device can be formed. In this case, the specific gravity S ₁ of the dielectric liquid and the specific gravity S ₂ of the liquid inside the microcapsule are at least S ₁
With the relationship of ≧ S ₂ , it is possible to further reduce the energy required for rotation.

In a second aspect, the present invention realizes the production of particles having a true spherical shape and a region divided into two colors, which can be used as two-color rotating particles in a display element of a sheet-type display device. . Specifically, a suspension of particles having a stable shape of wax or resin containing two types of coloring agents is prepared, and then, by performing an appropriate process, without changing the shape of the particles. One colorant is moved to localize, thereby producing two-color particles having different optical absorption or reflection characteristics for each hemisphere.

Means for moving the colorant include (1)
Methods such as (2) migration of a colorant by applying a magnetic field, (2) migration of a colorant by application of an electric field, and (3) sedimentation of the colorant can be used. By any of these methods, a specific colorant is aggregated in a local region of the particle, and a particle having a plurality of regions having different optical absorption or optical reflection in the particle is obtained.

When the melting point of the wax or the softening point of the resin is lower than the boiling point of water of 100 ° C., the colorant-containing particles can be obtained in a stable and safe suspended state in water. In this case, there is an additional advantage that a surfactant effective for stabilizing the shape of the particles can be selected from a wide variety of water-soluble surfactants. When suspending wax or resin in water, the surface of the colorant is subjected to a hydrophobic treatment to prevent the colorant in the wax or resin from leaking into water, and to color the wax or resin. The dispersion state of the agent can be maintained.

In order to move the colorant in the wax or the resin particles, heating for melting the wax or softening the resin is required. When using resin,
In order to prevent the deformation of the shape of the resin particles due to the heating, it is effective to disperse the colorant in the resin before curing, and then perform a process such as heating or moving the colorant. Further, when silicone rubber is used as a resin for dispersing the rotating particles when manufacturing a display device, the colorant is moved, and then the silicone rubber is swelled with silicone oil. Is filled with silicone oil as a dielectric liquid at the interface with the substrate, thereby facilitating the production of the sheet-type display device.

In the third aspect, the present invention makes it possible to easily produce particles having a uniform particle diameter and different in color and charging characteristics from one hemisphere to another, which can also be used as two-color rotating particles in a display element of a sheet-type display device. A manufacturing method is provided. In this method, two types of materials having different colors and charging characteristics are filled in through holes provided in a molding sheet to prepare a preformed combined body in which the two types of materials are bonded. Subjecting the combined body to a molding process to form spherical two-color rotating particles composed of two hemispheres each composed of the two types of materials.

Each of the two-color rotating particles according to the present invention can form a display layer by being filled together with a transparent dielectric liquid into the space inside the binder formed into a sheet. By disposing this display layer between a pair of counter electrodes, a sheet-type display device can be manufactured.

[0033]

DETAILED DESCRIPTION OF THE INVENTION In one aspect of the present invention, the rotating particles encapsulate a liquid in microcapsules having regions on the surface that differ in both color and electrical properties, especially charging properties, and The rotating particles can be used as a display element in a sheet-type display device that performs display by changing optical absorption or optical reflection by an electric field. By making the inside (core) a liquid, the mass of the microcapsule-type rotating particles becomes relatively small, and as a result, the energy required to rotate the particles, the applied voltage (driving voltage)
Can be reduced.

Specific examples of the liquid contained in the microcapsules include (1) water, (2) alcohols such as ethanol, methanol and isopropyl alcohol, and (3)
Hydrocarbons such as toluene, cyclohexane, hexane, and dodecylbenzene; (4) halogenated hydrocarbons such as chloroform, chlorobenzene, allyl bromide and acryl chloride; (5) ketones such as acetone, methyl ethyl ketone and acetylacetone; and aldehydes such as acetaldehyde. (6) Carboxylic acids such as oleic acid and maleic anhydride or anhydrides thereof, (7) Silicones such as dimethyl silicone oil, methylphenyl silicone oil, fluorine-modified silicone oil, amino-modified silicone oil, and polyether-modified silicone oil Oils and modified silicone oils, (8) animal and vegetable oils such as soybean oil, peanut oil, olive oil, tallow fatty acid triglyceride, shark liver oil, (9) Isopar G, Isopar L (exonization) Company, Ltd.) isoparaffins such as, and the like. In particular, it is preferable to use water, isoparaffin, silicone oil, animal and vegetable oils and the like as a stable liquid with little volatilization. The liquid inside the microcapsule is not limited to a single liquid, and may be a mixture of a plurality of liquids.

The membrane (shell) of the microcapsule is made of a known resin such as gelatin, gelatin-gum arabic, gelatin-gellan gum, polystyrene, polymethyl methacrylate, polyester, polyphenyl ester, polyurethane, nylon 6, nylon 66, and polyurea. Can be formed.

The method of forming the film of the microcapsule with a resin includes (1) coacervation method, (2) complex coacervation method, (3) interfacial polymerization method,
Known methods, such as forming a microcapsule film by polymerizing and aggregating a plurality of types of monomers on the surface of a droplet serving as a core portion by using (4) a spray drying method, (5) a soap-free emulsion polymerization method, or the like. Method.

Alternatively, a film of microcapsules may be formed by using a plurality of polymerization methods in combination. For example, after forming a film by interfacial polymerization, by spray drying method,
There is a method of further forming a film on the outside. Instead of the polymerization method, a method of forming a resin film may be used. For example, after forming microcapsules by the complex coacervation method, an aqueous solution of polyvinyl alcohol is applied and dried on the surface of the microcapsules,
There is a method of forming a thin layer of polyvinyl alcohol. In this case, the final microcapsule film has a two-layer structure.

As a polymer forming a film of the microcapsule, a polymer formed from a monomer having an amide bond has excellent mechanical strength, solvent resistance and elasticity, and is more suitable for use as rotating particles. I have. As a method for producing microcapsules from a monomer having an amide bond, there is a well-known interfacial polymerization method. As an example of a method for producing microcapsules using an interfacial polymerization method,
(1) Polyvinyl alcohol as a surfactant is dissolved in ion-exchanged water, and (2) methylhexane diisocyanate as an oil-soluble monomer is dissolved in cyclohexane.
(3) The aqueous solution prepared in (1) is mixed with the cyclohexane solution prepared in (2), and the mixture is stirred with a homogenizer to obtain an emulsion (O / O) in which droplets of the cyclohexane solution are dispersed.
W emulsion), and (4) the obtained emulsion is kept at a temperature of 40 to 90 ° C., an aqueous solution of polyethylene glycol is added dropwise while stirring, and the mixture is heated for 3 hours. Needless to say, the method for producing microcapsules by the interfacial polymerization method is not limited to this.

Specific examples of oil-soluble monomers used for producing microcapsules by the interfacial polymerization method include hexamethylene diisocyanate, sebacoyl chloride,
4-diphenyl diisocyanate, terephthal chloride, bischloroformate and the like. Specific examples of the water-soluble monomer include 1,6-hexamethylenediamine, diethylenetriamine, and polyethylene glycol. Examples of the liquid inside the microcapsules include cyclohexane and toluene.

Although the method of forming the microcapsule film with the resin has been described above, the rotating particles of the present invention are not limited to those having the resin film microcapsules. Is a liquid. Further, the film of the microcapsule does not need to be formed only of a resin material, and may contain various organic or inorganic additives such as a charge control agent and a pigment (particularly a white pigment).

The microcapsules produced by the various methods described above generally have an average volume particle size of 1 to 500 μm.
In a wide range of. When used as rotating particles for display, the particle size of the microcapsules is preferably in the range of 10 to 200 μm, particularly from the viewpoint of resolution, concealment ratio, and the like. The microcapsules having a preferable particle size can be obtained by subjecting the produced microcapsules to a classification treatment. To control the particle size during microcapsule production,
Surfactants and dispersion stabilizers may be used. As the surfactant, any of an anionic surfactant, a cationic surfactant, and a nonionic surfactant such as polyvinyl alcohol may be used. As the dispersion stabilizer, inorganic fine particles such as tricalcium phosphate may be used.

In order to use a microcapsule as a display element, it is necessary to provide a surface of the microcapsule with regions having both different colors and different electric characteristics (charging characteristics). For this reason, the easiest is to color only the hemisphere. As a coloring method,
(A) a method of vacuum-depositing carbon black, copper phthalocyanine, titanyl phthalocyanine, aluminum, tungsten, or the like; (b) a resin in which a pigment or a dye is dispersed is dispersed or dissolved in a solvent, and spray coating, dip coating, or doctor blade is performed. And (c) a method in which microcapsules are immersed in a solvent containing an oil-soluble disperse dye to impregnate the dye into the microcapsule membrane. FIG. 3 shows two-color rotating particles obtained by these methods. The particles contain a liquid 12 inside the microcapsule 11 and have a colored layer 13 covering half the surface of the microcapsule 11.

In the above methods (b) and (c),
In order to color only the hemisphere, only half of the microcapsules are embedded in a water-soluble resin such as polyvinyl alcohol or a thermoplastic resin such as polystyrene (mask processing). It is effective to carry out coloring by the method described above, and then remove the water-soluble resin by washing with water, or melt and remove the thermoplastic resin by heating.

Specific examples of the pigment used in the above method (b) include (1) black pigments such as carbon black and magnetite, (2) azo pigments such as soluble azo, monoazo and disazo pigments, 2) Polycyclic pigments such as phthalocyanine, quinacridone, perillin, perinone, and isoindoline, and (4) white pigments such as titanium dioxide, silicon dioxide, alumina, and calcium carbonate. Specific examples of the dye include an oil-soluble dye, a reactive dye, a disperse dye, a direct dye, an acid dye, and a basic dye. These pigments or dyes may be used as a mixture. Specific examples of the resin in which the pigment or the dye is dispersed include known resins used in commercially available colored sprays, such as an acrylic resin and an alkyd resin. By dissolving a resin in which a pigment or a dye is dispersed in an organic solvent such as toluene, butyl acetate, or ethyl acetate, and coating the solution on the surface of the microcapsule, the hemispherical portion of the microcapsule can be colored. Further, in order to further charge the microcapsules, a charge control agent may be mixed with the pigment and the dye in the resin. Specific examples of the charge control agent include a nigrosine dye, a triphenylmethane dye, and a quaternary ammonium salt as the positive charge control agent, and a salicylic acid-based compound and a boron-based compound as the negative charge control agent.

As a specific example of the above method (c), in addition to the above method, a microcapsule obtained by dissolving a disperse dye or an oil-soluble dye or the like in ethanol, and masking a hemisphere portion of the solution with polyvinyl alcohol. And stirring, for example, while maintaining the temperature at 70 ° C.,
A method of impregnating the dye into the microcapsule membrane can also be mentioned. The impregnated particles can be used as a display element by washing and drying.

Further, as a coloring method (d) other than the above (a) to (c), as shown in FIG. 4, an electrophoretic particle (or The particles 14 are dispersed, and the particles 14 are formed by applying an electric field or a magnetic field (for example, in a direction indicated by an arrow in the drawing) while forming the film of the microcapsule 11 or while heating after forming the film. There is also a method in which electrophoresis is performed and dispersed in the film of the microcapsule 11. Specific examples of the electrophoretic particles include (1) azo pigments such as a soluble azo type, monoazo type and disazo type, and (2) phthalocyanine type, quinacridone type, perillin type, perinone type, isoindoline type and isoindoline type. Black pigments such as polycyclic pigments and (3) carbon.
Further, not limited to these pigment particles, as the migrating particles, various kinds of organic / inorganic pigments, fine particles such as dyes, metal powders, resins, and the like can be used as well as well-known colloid particles. As the electrophoretic particles, iron, nickel, iron-
Nickel alloy, iron-nickel-chromium alloy, cobalt,
Cobalt-aluminum alloy, samarium-cobalt alloy, magnetite and the like can be mentioned.

In order to stabilize the localization (fixation) of the migrating particles in the microcapsules, it is effective to perform a pretreatment on the surface of the migrating particles and to stably disperse the migrating particles in a liquid. In this case, the electrophoretic particles can be stably dispersed as follows depending on the type of the liquid inside the microcapsules. (1) When the liquid inside the microcapsules is water and the electrophoretic particles have been subjected to a hydrophilic treatment, a W / O emulsion is prepared at the time of performing the polymerization reaction. Therefore, the electrophoretic particles subjected to the hydrophilization treatment are held in the aqueous phase having a higher affinity than the oil phase (organic phase), so that the dispersed state of the electrophoretic particles in the liquid becomes stable. Thereby, it is possible to prevent a phenomenon that the migrating particles move to the interface between the aqueous phase and the oil phase (organic phase) during the polymerization reaction and are randomly integrated with the microcapsule membrane. (2) When the liquid inside the microcapsules is an oily liquid and electrophoretic particles subjected to a hydrophobic treatment are used, an O / W emulsion is prepared when performing the polymerization reaction. Therefore, the electrophoretic particles subjected to the hydrophobic treatment are held in the oil phase having a higher affinity than the aqueous phase, so that the dispersed state of the electrophoretic particles in the liquid becomes stable. As a surface treatment agent,
Known treatment agents such as a silane coupling agent, a fluorine compound, and silicone oil are used. Furthermore, a method of modifying the surface of the migrating particles by irradiation with ultraviolet light may be used. The electrophoretic coloring agent used for the rotating particles of the present invention needs to have high affinity for the liquid inside the microcapsules regardless of the surface treatment agent and surface treatment method.

In order to display higher whiteness with the microcapsule-type rotating particles, it is effective to include a white colorant in the liquid inside the microcapsules. For example, a white pigment such as silica, titanium oxide, and alumina can be dispersed in a liquid.

By applying a magnetic field and an electric field simultaneously, colorants having different colors, for example, a black colorant and a white colorant may be localized in different hemispheres. In this case, a black pigment such as magnetite or the like can be preferably used as a black colorant, and a white pigment such as titanium dioxide can be preferably used as a white pigment.

In the present invention, the microcapsules can be used as a display element by coloring by the coloring method described above. Such microcapsule-type rotating particles are dispersed in an optically transparent resin together with a dielectric liquid for filling voids, for example, as described above with reference to FIG. Incorporated in At this time, the specific gravity S ₁ of the dielectric liquid and the specific gravity S _{2 of} the liquid contained in the display rotating particles of the microcapsule are included.
However, if the relation of S ₁ ≧ S ₂ is satisfied, the buoyancy of the microcapsules becomes larger, and the applied voltage required for electrophoresis can be further reduced. Since the particles move to the upper part of the gap by the electrophoresis, the contrast of the display device is improved.

According to another aspect of the present invention, one of two types of colorants dispersed in particles made of resin or wax is subjected to the action of magnetophoresis, electrophoresis, sedimentation, etc. By moving and localizing the shape of the resin or wax particles while keeping them stable, 2
Color rotating particles can be made.

As the resin forming the particles, polyethylene, polystyrene, polyvinyl chloride, polypropylene,
Known resins such as polyacetal, polycarbonate, acrylic, and nylon can be used alone or in combination. Copolymers of these resin monomers may be used. When a resin is used, preferably, the resin containing the dispersed colorant is produced by heating, stirring, and mixing the colorant and the resin using a kneader or the like. The colorant-containing resin is molded by a known method such as injection molding, blow molding, extrusion molding, or calendar molding to produce colorant-containing particles. In order to enhance the dispersibility of the colorant, preferably, the colorant is added to the monomer, and the monomer is polymerized by heating with a polymerization initiator or the like to produce polymer resin particles.

Specific examples of the monomer for producing the resin particles include (1) styrene derivatives such as o-methylstyrene, m-methylstyrene, p-phenylstyrene, and pn-dodecylstyrene, or styrene, 2) olefins such as ethylene, propylene and butylene;
(3) vinyl halides such as vinyl chloride, vinyl bromide and vinyl fluoride; (4) vinyl esters such as vinyl acetate, vinyl benzoylate and vinyl propionate; (5)
Α-methylene fatty acid monocarboxylic esters such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, dodecyl methacrylate, dimethylaminoethyl methacrylate, and phenyl methacrylate; (6) methyl acrylate, ethyl acrylate, acrylic acid acrylic acid esters of n-butyl koto; (7) vinyl ethers such as vinyl methyl ether and vinyl ethyl ether;
(8) vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, and methyl isopropenyl ketone; (9)
Vinyl compounds such as N-vinylpyrrole, N-vinylcarbazole, and N-vinylpyrrolidone; and (10) acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, and acrylamide. Further, as a polymerization initiator for polymerization, a persulfate such as potassium persulfate, 2,2′-azobis (2,4-
Dimethylvaleronitrile), 2,2'-azobis (2,
Azo compounds such as 4-isobutyronitrile) can be used. The polymerization initiator is usually used at a concentration of 0.01 to 10% based on the weight of the monomer.

The polymerization methods include membrane emulsification, emulsion polymerization,
Known techniques such as soap-free emulsion polymerization, suspension polymerization, miniemulsion polymerization, nozzle vibration method, and two-stage swelling method can be used. In order to stabilize the state of emulsification or suspension, anionic surfactants, cationic surfactants or nonionic surfactants as surfactants, and inorganic fine particles such as tricalcium phosphate as dispersion stabilizers Can be used.

Further, in order to achieve both the ease of migration by migration or sedimentation of one colorant in the particles and the subsequent fixation of both colorants, it is preferable to use a wax-like substance as a material forming the particles. preferable. This takes advantage of the unique temperature-viscosity properties of waxy substances. Taking carnauba wax as an example, as shown in FIG. 5, above a certain temperature, that is, above the melting point, the viscosity of the wax sharply decreases. Therefore, while the colorant cannot migrate or settle under an atmosphere lower than the melting point of the wax,
In an atmosphere at or above the melting point of the wax, the fluid drag, which is a resistance to the migration or settling of the colorant, decreases as the viscosity of the wax decreases, and the ease of migration or settling of the colorant increases.

Specific examples of the wax include known waxes such as carnauba wax, polyethylene wax, polypropylene wax, amide wax, ester wax and paraffin wax. Mixtures of two or more waxes may be used. When a wax having a melting point of less than 100 ° C. is used, particles can be produced by suspension in water, which is excellent in stability and safety. Melting point 100 ° C
Specific examples of the lower wax include paraffin wax, carnauba wax, ester wax and the like.

As a method of dispersing the coloring agent in the wax, a method of adding the coloring agent to the molten wax and stirring the mixture with a homogenizer or the like can be used. As the method of forming the wax into particles, (1) a method in which the dispersed colorant-containing wax is charged into a liquid having a melting point of the wax or higher and stirring with a homogenizer or the like, and (2) a method in which the dispersed colorant-containing wax is heated and molded. , And the like. When the liquid into which the dispersed colorant-containing wax is charged is an oily liquid, a known oil-soluble surfactant such as metal soap or modified silicone oil may be used to prevent aggregation of the wax and stabilize the particle size. Good. Further, in order to stabilize the shape of the wax particles, an anionic surfactant, a cationic surfactant, a nonionic surfactant or the like may be used alone or as a mixture.

Next, an example of a method for producing wax particles by a suspension method in an aqueous phase will be specifically described. In the first step, 0.1 part by mass of each of the two types of colorants is added to 10 parts by mass of the melted wax, and the mixture is stirred with a homogenizer to prepare a wax in which the colorants are dispersed. In the second step, after dissolving 2.5 parts by mass of polyvinyl alcohol as a surfactant in 500 parts by mass of ion-exchanged water at a temperature higher than the melting point of the wax, a wax containing a dispersed colorant is mixed with this solution, Stir with a homogenizer or the like. In a third step, the mixture was stirred at 20 ° C.
And then rapidly cooled to below the melting point of the wax to solidify the wax and form particles. The particle size of the obtained two-color particles is desirably in the range of 0.1 to 300 μm. Generally, the particles are used after having a desired range of particle size by classification.

In order to produce two-color particles by the method of the present invention, at least two kinds of colorants having different hues are dispersed in wax or resin particles, and one of the colorants is migrated by applying a magnetic field or an electric field. Or settle by settling. Examples of the coloring agent that can be subjected to magnetophoresis include particles of iron, nickel, an iron-nickel alloy, an iron-nickel-chromium alloy, cobalt, a cobalt-aluminum alloy, a samarium-cobalt alloy, magnetite, and a resin in which these are dispersed. Particles may be mentioned. Examples of colorants that can be electrophoresed include (1) azo pigments such as soluble azo, monoazo and disazo, and (2) polycyclic such as phthalocyanine, quinacridone, perillin, perinone, and isoindoline. Formula pigments, (3) black pigments such as carbon,
And the like. In addition to the above-mentioned colorant to be migrated, various kinds of fine particles such as organic and inorganic pigments, dyes, metal powders, and resins can be used as the other colorant in addition to well-known colloid particles. For example, in order to produce two-color particles having high whiteness, a white pigment such as titanium oxide, silicon dioxide, alumina, or calcium carbonate can be used. When resin fine particles are used as the colorant, it is necessary that the resin (or wax) forming the two-color particles has a lower melting point and that the two-color particles have a larger particle size than the resin fine particles.

In order to disperse the colorant in the resin or wax, it is effective to subject the colorant surface to a hydrophobic treatment. Known surface treating agents such as a silane coupling agent, a fluorine compound, and silicone oil are used as the surface treating agent. Alternatively, a method of modifying the surface of the colorant by irradiation with ultraviolet rays may be used. The colorant dispersed in the resin or wax particles needs to have a high affinity for the resin or wax regardless of the surface treatment agent or surface treatment method used.

In some cases, a part of the colorant dispersed in the resin or wax may be exposed on the surface of the resin or wax particles. In such a case, it is effective to coat the resin or wax particles having the colorant exposed on the surface with an additional resin or wax film. The resin or wax that forms the film may be the same as the resin or wax of the particles in which the colorant is dispersed, or a different resin or wax may be used. As a method for coating the particles, known microencapsulation techniques such as a phase separation method, a submerged drying method, a melting dispersion cooling method, and a spray drying method can be used. By coating the particles in this way, it is possible to simply and reliably eliminate or reduce the exposure of the colorant.

In order to migrate one colorant dispersed in the particles while maintaining the shape of the two-color particles, (1) 2
The color particles are dispersed in a binder such as an uncured water-soluble resin, silicone rubber, or photocurable resin, and then the binder is cured. (2) Next, the binder in which the two-color particles are dispersed is heated to a temperature equal to or higher than the melting point of the two-color particles. A method including heating and applying a magnetic field or an electric field to the two-color particles in the binder to cause the colorant to migrate, and (3) cooling while applying the magnetic field or the electric field can be used. In order to cause the colorant to settle without being migrated, in the above-mentioned methods (2) and (3), the colorant is allowed to stand without applying a magnetic field or an electric field, and heating and subsequent cooling may be performed. When using the method described here, it is necessary that at least the melting point of the binder is higher than the melting point of the two-color particles. After cooling, the binder is dissolved and removed, and the remaining particles are washed, whereby two-color rotating particles functioning as a display element can be obtained.

When one of the colorant dispersed in the wax or the resin particles is moved by electrophoresis or sedimentation and localized by using silicone rubber as a binder, the localization treatment is performed. After completion, it may be used as it is for the display layer.

According to another aspect of the present invention, a preformed composite, which is a composite of two materials formed from two materials having both different colors and different charging characteristics, is composed of two hemispheres. Subjected to a molding process to make
Color rotating particles can be obtained.

The production of the two-color rotating particles will be described with reference to FIG. First, two kinds of materials having different colors and charging characteristics are coated with a film 21 having the same thickness in the range of about several tens to several hundreds of μm,
22 are formed into sheets. At this time, when the mechanical strength of the film to be formed is insufficient, for example, a film 23 such as polyethylene or Kapton (manufactured by DuPont) having an appropriate strength is used as a carrier, and a film 21 of a predetermined material is placed thereon.
2 may be produced. Next, these two types of material films 21,
22 is arranged on one side of the molding sheet 25 and the other is arranged on the opposite side.
A laminate with 22 is made. As shown in FIG. 7 which is a perspective view of the molding sheet 25, the molding sheet 25 has a plurality of through holes 26 of a predetermined size.

Subsequently, the obtained laminate was pressed into a pressing device 28.
(FIG. 6), and the two types of materials are pressed through holes 26.
Fill to the same thickness. For this purpose, the same amount of each material must be filled into the through hole 26 from both sides thereof. In order to fill the through holes 26 with the same amount of each material,
It is necessary that the two types of material films 21 and 22 have the same mechanical strength and extensibility. The mechanical strength here is evaluated by the area of the film after rolling when the same amount of two kinds of material films are pressed and rolled with the same force, and when the area after rolling of both material films is equal. , Their mechanical strength is considered to be the same. Usually, the material for forming the two-color particles is mixed with a pigment for coloring in advance, an additive for the purpose of adding electrical properties, and the like, and the two materials have different mechanical strengths. In order to obtain two kinds of materials having the same mechanical strength, it is effective to mix an inorganic material such as ceramics or an inorganic salt or an organic material having different mechanical properties from those materials.

When two types of materials are filled into the through holes by pressing, it is necessary to effectively remove unnecessary resin that is not filled in the through holes. To this end, it is effective to add a spreading agent to the material to be pressed to provide sufficient spreadability, and to use a roll press for the pressing of the material, thereby effectively eliminating unnecessary materials at the time of pressing. The two types of materials can be filled at a predetermined ratio into the through holes provided in the molding sheet.

When the two types of materials are not sufficiently integrated by pressing, the laminate of the molding sheet and the material film is subjected to a preheating treatment before the pressing, a heat roll is used, or a super roll is used. The material films can be bound together by utilizing local heating of the material film surfaces by sonication or the like.

A series of steps of filling the material into the through holes of the molding sheet and binding them is performed in a reduced pressure environment in order to maintain good filling of the materials into the through holes and binding between the materials. Is preferred.

The particles (preformed composite) formed by integrating the two types of materials in the through holes of the molding sheet are separated from the molding sheet by blowing a high-pressure gas, for example, compressed air. Alternatively, it may be extruded using a jig such as a pin corresponding to the through hole. In order to facilitate separation from the molding sheet, the molding sheet may be subjected to a surface treatment with a release agent or the like.

With respect to the production of a preformed joint by filling two types of materials into the through holes of the molding sheet, it is not necessary to be bound by each of the above-described methods, and the same amount of each material is placed in the through holes of the molding sheet. Any technique can be used as long as it can be filled to obtain the desired preformed conjugate. For example, it is also possible to use a material in which two types of material films are integrated in advance and form a sheet, and fill the sheet from one of the through holes of the shaping sheet.

The preformed composite separated from the molding sheet has the shape of a small cylinder (in some cases, a prism-like shape can be considered) following the shape of the through hole. Such a preformed composite must subsequently be subjected to a suitable molding process to form a sphere. For this purpose, it is effective to disperse the preformed conjugate in a liquid, heat the dispersion to melt the preformed conjugate, form the sphere by surface tension, and then cool to obtain spherical solid particles. is there. Any other method can be used as long as spherical two-color particles composed of two hemispheres can be obtained from a preformed composite of two materials.

Each hemisphere has a pigment or dye for coloring,
If necessary, other additive components are formed from a mixed material (composition) mixed with the main material.

The main materials forming each hemisphere include various resins such as polyester, acrylic and alkyd, and various waxes such as carnauba wax, polyethylene wax, polypropylene wax, amide wax, ester wax, paraffin wax and the like.

The pigments for coloring the main material include (1) black pigments such as carbon black and magnetite;
Azo pigments such as soluble azo, monoazo and disazo,
(3) polycyclic pigments such as phthalocyanine, quinacridone, perillin, perinone, and isoindoline;
(4) White pigments such as titanium dioxide, silicon dioxide, alumina, and calcium carbonate. In addition, examples of dyes for coloring the main material include oil-soluble dyes, reactive dyes, disperse dyes, direct dyes, acid dyes, and basic dyes. These pigments or dyes may be used as a mixture of two or more.

Further, a charge controlling agent may be used together with a pigment or a dye in order to increase the difference in chargeability between the respective color portions of the rotating particles. Specific examples of the charge control agent include a nigrosine dye, a triphenylmethane dye, and a quaternary ammonium salt as the positive charge control agent, and a salicylic acid-based compound and a boron-based compound as the negative charge control agent.

Further, a spreading agent may be added to the material to be filled in the through-hole in order to improve the characteristics of the molding sheet when the material is filled in the through-hole. Examples of spreading agents include low molecular weight substances such as tetraamide for waxes, but any spreading agent can be used as long as the desired filling properties are not impaired.

The forming sheet having the through holes is preferably made of a material such as a metal, for example, stainless steel, which has a uniform thickness and does not change its thickness during the pressing step or has a small deformation. As a method of providing a through hole in a metal molding sheet, it is preferable to use electrolytic etching or the like that makes the surface after treatment relatively smooth. As long as the effects of the present invention are not impaired, other materials and through hole forming techniques may be used. The shape of the through hole may be any shape as long as the effect of the present invention is not impaired.

The preformed joint formed by binding in the through hole is formed into a sphere by a molding process. This spheronization can be effected, for example, by pouring the preformed combination into a heated liquid, melting it in the liquid and utilizing the effect of surface tension. In this case, the liquid may be any liquid as long as the resin particles do not dissolve and can be made spherical by surface tension.

As usual, the hemispherical portions of the prepared monochromatic particles are separately applied by dip coating or the like, the dye is deposited on the hemispherical portions, or the monochromatic particles formed by using a photosensitive material are exposed. In the case of producing two-color particles by applying a treatment such as development and coloring only the hemisphere, a polymerization technique such as suspension polymerization is generally used for producing monochromatic particles. Difficult to obtain. On the other hand, according to the present invention, the two-color particles produced from the combination of the two materials each containing the colorant are produced from the same amount of the preformed combination defined by the through holes of the same size. , Can have a uniform particle size.

Each of the two-color rotating particles (or two-color particles) according to the present invention described so far is filled with a transparent dielectric liquid into the voids inside the binder formed into a sheet to form a display layer. Can be used for
By disposing this display layer between a pair of counter electrodes, a sheet-type display device can be manufactured.

The method for filling the binder with two-color particles and a transparent dielectric liquid to form a display layer is as follows: (1) The two-color particles are added to silicone rubber before curing described in US Pat. No. 4,143,103. Is dispersed and the silicone rubber (binder) is cured, and then the silicone rubber is swollen with silicone oil. Sait
oh et a1. , “A Newly Level
oped Electrical Twisting
Ball Dispay ", Proc. Of S
ID, Vol. 23/4, 1982, a method in which two-color particles are coated with a toluene-soluble resin, dispersed in polyvinyl alcohol (binder), and cured and then immersed in toluene. (3) A method described in JP-A-8-234686. A method of forming microcapsules by covering a dielectric liquid and two-color particles with a resin film using interfacial polymerization, and dispersing the microcapsules in a transparent resin (binder).

By disposing the display layer between a pair of counter electrodes, at least one of which is transparent, a sheet-type display device can be manufactured. Generally, indium tin oxide (ITO) can be used as the transparent electrode material. Other electrode materials include metals such as gold, silver, copper, and iron, and conductive resins. In order to obtain flexibility advantageous for a sheet-type display device, it is preferable to use a conductive resin. Specific examples of the conductive resin include (1) polyacetylene and poly (1,6) which are conductive polymers.
Polyacetylene-based polymers such as -heptadiyne),
(2) polyparaphenylene, polymetaphenylene, polyphenylenevinylene, polyphenylene oxide, polyphenylene sulfide, polypyrene, polyazulene,
Polyphenylene-based polymers such as polyorphrene,
(3) Heterocyclic polymers such as polypyrrole, polythiophene, polyselenophene, polytellurophen, and polythienylenevinylene; (4) ionic polymers such as polyanilene; and (5) ladders such as polyacene, polyphenanthrene, and polyperinautarene. Polymer. Further, as the electrode material, a resin in which a conductive powder in which a metal such as gold, silver, copper, iron or the like or graphite is finely dispersed may be used. ITO is a preferable material for the conductive powder because of its high transparency and high electrical conductivity.
Is dispersed in a resin, whereby a conductive resin composition particularly suitable for an electrode on the display surface side can be obtained. As the binder resin in which the conductive powder is dispersed, known resins such as polyester, epoxy, silicone, polyvinyl acetal, polycarbonate, acryl, and urethane can be used alone or in combination. When a conductive resin film or a film of a conductive resin composition in which conductive powder is dispersed in a binder resin is used as an electrode, the thickness thereof is desirably 0.1 to 20 μm.

A known insulating resin such as polyester, epoxy, silicone, polyvinyl acetal, polycarbonate, acrylic and urethane is used alone or in combination.
A solution diluted in a solvent is applied to the display surface and dried to be used as a protective layer of the electrode on the display surface side. The thickness of the protective layer is desirably 0.1 to 20 μm.

As described above, the sheet type display device according to the present invention is a display layer formed by filling the rotating particles for display (bicolor particles) of the present invention into the gaps inside the sheet-like binder together with the transparent dielectric liquid. And a pair of counter electrodes sandwiching the display layer. This sheet type display device is schematically shown in FIG. In this figure, 100 is a sheet type display device, 10
1 denotes a binder layer, 102 denotes rotating particles for display, 103 denotes a dielectric liquid, and 104 and 105 denote electrodes. Electrode 1
One of 04 and 105 is formed as a common electrode,
The other is formed as an individual electrode (in FIG. 8, the individual electrodes are simplified and drawn integrally). The electrodes 104 and 105 are connected to an external power supply (not shown) for driving the display device 100.

[0086]

Next, the present invention will be further described with reference to examples.
The present invention is not limited to these examples.

(Example 1) First, display rotating particles for enclosing a liquid in microcapsules were produced as follows. In 150 parts by weight of water, 0.02 parts by weight of a surfactant, polyvinyl alcohol # 2000 (manufactured by Kanto Chemical Co., Ltd.) was dissolved to prepare an aqueous continuous phase. Cyclohexane 20
1.5 parts by mass of hexamethylene diisocyanate as an oil-soluble monomer was dissolved in parts by mass to prepare a dispersed phase.
The continuous phase and the dispersed phase were mixed, and the mixture was stirred at a rotation speed of 500 rpm for 10 minutes using a disk turbine type stirrer to obtain O /
A W emulsion was prepared.

The O / W prepared in a thermostat at a temperature of 60 ° C.
While stirring the emulsion using a disk turbine type stirrer at a rotation speed of 500 rpm, a solution obtained by dissolving 0.65 part by mass of polyethylene glycol 200 (manufactured by Wako Pure Chemical Industries) as a water-soluble monomer was slowly dropped into 30 parts by mass of water. Then, the mixture was stirred for 2 hours, washed with water, filtered, dried and further classified to obtain a cloudy microcapsule having a volume average particle size of 150 μm.

This microcapsule is treated with an aqueous solution of modified polyvinyl alcohol, Gohsenal T-350 (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) (polyvinyl alcohol: water = 1: 4).
Was dispersed in an uncured film having a thickness of about 80 μm formed by the above method, lightly pressed from above with an aluminum plate, and then dried at room temperature for 48 hours to perform a mask treatment.
A film having a thickness of 20 μm was formed on the microcapsules having been subjected to the mask treatment in this manner using a commercially available black acrylic lacquer. Thereafter, polyvinyl alcohol as a mask was dissolved by washing with water, washed, and dried to produce microcapsule-type rotating particles in which hemispheres were colored in two colors.

Subsequently, a display device for a test was manufactured as follows. As shown in FIG. 9, on a glass substrate 31 having a common electrode 32 made of gold,
With reference to the method disclosed in Japanese Patent Publication No. 30, a vertical spacer 33 made of silicone rubber (having a thickness of 40
μm, height 300 μm). Isopar G (manufactured by Ericsson Chemical Co., Ltd.) is placed inside a cell 34 having a square cross section with a side length of 300 μm formed by the spacer 33.
And a glass substrate 3 enclosing the microcapsule-type rotating particles 35 produced above and having individual electrodes 36 made of ITO.
7 were attached to each other to produce a display device 30 for testing.
A voltage 200 is applied to the upper and lower electrodes 32 and 36 of the display device 30.
When V was applied, the microcapsule-type rotating particles 35 rotated, and it was confirmed that image display was possible. It can be seen that the applied voltage required for the inversion of the rotating particles 35 is considerably lower than the voltage of about 500 V in the case of ordinary rotating particles that do not contain a liquid inside the particles (they are solid as a whole).

Example 2 A magnetic powder BL-200 (manufactured by Titanium Co., Ltd.) surface-treated with triethoxyphenylsilane as a silane coupling agent was dispersed in a liquid inside a microcapsule. Microcapsules were produced in the same manner as in Example 1.

The microcapsules were dispersed in a 30% aqueous solution of polyvinyl alcohol 500 (manufactured by Kanto Kagaku Co., Ltd.), and this dispersion was applied on a substrate to form a sheet. 10
When a magnetic field was applied to the sheet while heating at 0 ° C., the magnetic powder migrated and collected inside the upper part of the film. Thereafter, the mixture was gradually cooled while a magnetic field was applied, and the magnetic powder was fused with the film on the top of the microcapsule, thereby producing a microcapsule divided into two regions of white and black. Next, the polyvinyl alcohol was dissolved in water, washed and dried to obtain microcapsule-type rotating particles containing a liquid therein.

Subsequently, a display device was manufactured in the same manner as in Example 1, and when a voltage of 300 V was applied to the upper and lower electrodes of the display device, the microcapsule-type rotating particles were inverted, and an image could be displayed. I was assured.

Example 3 Microcapsule-type rotating particles were produced in the same manner as in Example 1. Next, a display device 30 ′ shown in FIG. 10 was manufactured in the same manner as in Example 1, except that the liquid to be sealed in the cell together with the microcapsule-type rotating particles was dodecylbenzene. This display device 30 'was constituted by the same components as the display device 30 of Example 1 except that the liquid contained in the rotating particles 35' was different from that of Example 1. On the other hand, in the display device 30 'of this example, since the specific gravity of dodecylbenzene is 0.86, which is larger than the specific gravity of cyclohexane of the encapsulating solution of Example 1 being 0.78, the microcapsule-type rotating particles 35' are not shown in FIG. As shown in FIG. 10, it was always in contact with the display surface. When a voltage of 150 V is applied to the upper and lower electrodes,
The microcapsule type rotating particles were inverted, and it was confirmed that image display was possible.

Example 4 Microcapsule-type rotating particles were produced in the same manner as in Example 1. Next, the obtained microcapsule-type rotating particles were subjected to two-component silicone rubber K.
E109 (manufactured by Shin-Etsu Chemical Co., Ltd.), and the silicone rubber was cured after forming into a sheet. The resulting cured rubber was swollen with silicone oil SH200, 20cS (manufactured by Dow Corning Toray Silicone Co., Ltd.), and the resulting curing was achieved. The gap between the rubber and the rotating particles was filled with the same silicone oil to form a sheet-like display layer. This display layer is bonded to a common electrode side formed of gold on a PET film, and then a PET film having individual electrodes formed of ITO is bonded to an exposed surface side of the display layer, thereby forming a sheet-type display device. Was prepared. When a voltage of 300 V was applied to both electrodes of this display device, the microcapsule-type rotating particles were inverted, and an image could be displayed.

(Example 5) Here, two-color rotating particles produced by dispersing a colorant in wax will be described. Ester wax (manufactured by NOF CORPORATION, melting point 67)
C) 5 parts by mass, 1 part by mass of silane compound surface-treated magnetite as a black colorant, and 1 part by mass of titanium dioxide as a white colorant. In a constant temperature bath with a liquid temperature of 80 ° C,
The wax and the two types of colorants were mixed, and the mixture was stirred at 5,000 rpm for 10 minutes using a homogenizer to prepare a melt of the colorant-dispersed wax. 2.5 parts by mass of polyvinyl alcohol # 2000 (manufactured by Kanto Chemical Co., Ltd.) was dissolved in 500 parts by mass of ion-exchanged water, and the solution was stirred at 800 rpm while maintaining the liquid temperature at 70 ° C. A suspension treatment was performed by adding a wax melt.
After the suspension treatment, 500 parts by mass of ion-exchanged water having a liquid temperature of 20 ° C. is put into the suspension, the liquid temperature is lowered to the melting point of the wax or lower, and the wax particles solidified are separated, washed and dried. Subsequently, classification was performed to obtain colorant-dispersed wax particles having an average volume particle size of 120 μm.

After dispersing the colorant-dispersed wax particles in an aqueous solution of polyvinyl alcohol # 2000 (concentration: 10 wt%), the dispersion is applied on a substrate and dried at a temperature of 25 ° C. for 48 hours to prepare a sheet for a display layer. did. As shown in FIG. 11, the obtained sheet 41 was heated at 80 ° C. on a hot plate 42.
While heating, the magnet 43 is placed on the sheet 41 and a magnetic field is applied in the direction of the dashed arrow in the figure, thereby causing the magnetite coloring agent 45 in the wax particles 44 contained in the sheet 41 to migrate, By cooling while applying a magnetic field, spherical two-color particles having different colors for each hemisphere could be produced.

Next, polyvinyl alcohol as a binder was dissolved and removed with water, and after washing the two-color particles, they were dispersed in a two-part silicone rubber KE109 (manufactured by Shin-Etsu Chemical Co., Ltd.). To form a sheet.
After the silicone oil was cured, the cured sheet was swollen with silicone oils SH200, 20cS (manufactured by Dow Corning Toray Silicone Co., Ltd.) to form a display layer. When an electric field was directly applied to the display layer, rotation of the two-color particles could be confirmed, and an image having a contrast of 1: 4 could be displayed.

Example 6 Instead of magnetite treated with a silane compound surface, 0.5 part by mass of polystyrene particles (particle diameter 3 μm, dark blue) in which 2 wt% of copper phthalocyanine was dispersed was used as a coloring agent. Two-color rotating particles were produced in the same manner as in Example 5, except that an electric field was applied instead of the magnetic field during the migration. That is, FIG.
As shown in the figure, the sheet 41 ′ in which the wax particles 44 ′ are dispersed is placed on the hot plate 42 sandwiched between the electrodes 51 connected to the power supply 52, and the sheet 41 ′ is heated.
A two-color particle was produced by applying an electric field in the direction of the dashed arrow in the figure to cause the copper phthalocyanine colorant 45 'in the wax particles 44' to migrate and then cooling while applying the electric field. Next, after a display layer was formed in the same manner as in Example 5, when an electric field was directly applied to the display layer, rotation of the two-color particles could be confirmed, and an image with a contrast of 1: 3 could be displayed.

Example 7 Hoechs as wax
5 parts by mass of t-Wax KST (manufactured by Clariant Japan, melting point: 60 ° C.), carbon (0.5%) as a black colorant
wt%) dispersed wax particles (Paraff manufactured by Nippon Seiro Co., Ltd.)
in Wax 155, melting point 69 ° C.) and 1 part by mass of titanium dioxide as a white colorant. Example 5 was repeated except that the temperature of the hot plate was set to 65 ° C., and the white colorant was settled by standing without applying a magnetic field.
Two-color rotating particles were produced in the same manner as in the above. After the display layer was formed in the same manner as in Example 5, when an electric field was directly applied to the display layer, rotation of the two-color particles was confirmed, and an image with a contrast of 1: 4 was displayed.

Example 8 Two-color rotating particles were produced in the same manner as in Example 7, except that the carbon (0.5 wt%) dispersed wax particles were oil-soluble black dyes. After a display layer was formed in the same manner as in Example 7, when an electric field was directly applied to the display layer, rotation of two-color particles could be confirmed, and the contrast was 1: 3.
Image was displayed.

Example 9 In the preparation of a wax particle-containing sheet before migration of a colorant by applying a magnetic field in Example 5, a two-part silicone rubber KE109 (manufactured by Shin-Etsu Chemical Co., Ltd.) was used instead of the aqueous solution of polyvinyl alcohol # 2000. Was used. Also. After the coloring agent is migrated by a magnetic field, the silicone rubber is removed from the silicone oil SH20 without removing the wax particles from the wax-containing silicone rubber sheet.
The display layer was directly formed by swelling with 0 and 20 cS (manufactured by Dow Corning Toray Silicone Co., Ltd.). When an electric field was directly applied to the display layer, rotation of the two-color particles could be confirmed, and an image having a contrast of 1: 4 could be displayed.

Example 10 A white wax sheet having a thickness of 50 μm was formed on a Kapton film (manufactured by DuPont) by hot pressing using a polyester wax (melting point: 70 ° C.) melted by heating. Similarly, a black coloring carbon black surface-treated with a charging agent is mixed with a polyester wax, and 50 μm on a Kapton film.
Was prepared. To these wax sheets, a tetraamide-based material was added in order to improve the spreadability at the time of rolling, and both sheets were adjusted with the same force so that the areas after rolling became equal. A 100 μm-thick stainless steel plate having a 100 μm diameter through-hole and having a surface treated with a fluoropolymer was sandwiched between the wax sheets of each color to form a laminate.

After the laminate was preheated, it was pressed and rolled by a roll press to fill the two holes with the materials of the wax film and to bind the two materials together. It was integrated to produce a pre-formed composite. The steps from rolling to binding were performed under reduced pressure. The combined body filled in the through-hole of the stainless steel plate was taken out of the through-hole with compressed air to obtain cylindrical two-color particles having a uniform particle size.
Put the particles in a hot water bath containing 1% surfactant,
The wax was partially added while stirring, and the wax was partially melted to form a spherical shape by surface tension, followed by cooling to produce two-color rotating particles having a uniform particle size.

Example 11 The same procedure as in Example 10 was carried out except that the polyester wax was replaced with ester wax, and the two-color materials filled in the through-holes of the stainless steel plate were subjected to ultrasonic treatment to be bound. Thus, two-color rotating particles having a uniform particle size were prepared.

Example 12 Example 10 was repeated except that polyester wax was replaced with ester wax and wax sheets of two colors were filled in the through holes by heat press.
In the same manner as described above, two-color rotating particles having a uniform particle size were prepared.

The present invention is as described above.
The features are described below together with various aspects. (Supplementary Note 1) Particles having regions on the surface that differ in both color and charging characteristics, and enabling image display by rotating the particles by the action of an electric field externally applied to a layer containing the particles. A rotating particle for display, characterized in that a liquid is encapsulated in a microcapsule having on its surface a region having both different colors and charging characteristics. (Supplementary Note 2) The rotating display particles according to Supplementary Note 1, wherein a coloring layer having a color and a charging characteristic different from that of the microcapsule itself is provided on a part of the surface of the microcapsule. (Supplementary Note 3) The rotating display particles according to Supplementary Note 1, wherein a part of the film constituting the microcapsule is colored by a coloring agent present in the film of this part. (Supplementary Note 4) The display rotating particles according to Supplementary Note 1, wherein separate portions of the film forming the microcapsules are colored with coloring agents having different colors. (Supplementary Note 5) The rotating display particles according to Supplementary Note 3 or 4, wherein the colorant is a particle capable of electrophoresis or a particle capable of magnetophoresis. (Supplementary Note 6) The rotating particles for display according to any one of Supplementary Notes 1 to 5, wherein a material of a film constituting the microcapsule is a polymer containing an amide bond. (Supplementary Note 7) A particle having a region having both a different color and a different charging characteristic, and a display for enabling image display by rotating the particle by the action of an electric field externally applied to a layer containing the particle. This is a method for producing rotating particles, in which particles of wax or resin containing two kinds of colorants are produced, and then one of the colorants is moved to be localized in the particles, thereby obtaining color and charging characteristics. Forming a region having both of them different from each other. (Supplementary Note 8) The colorant is moved by melting the wax or softening the resin by heating, migrating the colorant by applying a magnetic field, migrating the colorant by applying an electric field, or sedimenting the colorant. And the method of supplementary note 7. (Supplementary note 9) The method according to Supplementary note 7 or 8, wherein the melting point of the wax or the softening point of the resin is less than 100 ° C, and the particles containing the colorant are produced in a state of being suspended in water. (Supplementary note 10) The method according to any one of Supplementary notes 7 to 9, wherein the particles containing the colorant are produced using a wax. (Supplementary Note 11) As a colorant to be migrated by magnetism, iron,
The method according to claim 8, wherein nickel, iron-nickel alloy, iron-nickel-chromium alloy, cobalt, cobalt-aluminum alloy, samarium-cobalt alloy or magnetite particles, or resin particles in which the particles are dispersed are used. (Supplementary Note 12) The method according to any one of Supplementary Notes 7 to 11, wherein a surface of the colorant to be contained in the wax or the resin is subjected to a hydrophobic treatment. (Supplementary Note 13) The particles containing the colorant are dispersed in an uncured binder, and then the binder is cured.
13. The method according to any one of claims 7 to 12, comprising heating the cured binder above the melting point of the particles to move one of the colorants in the particles, and then cooling the binder. (Supplementary note 14) The method according to supplementary note 13, wherein the movement is performed by migration of a coloring agent by applying a magnetic field or an electric field, and the application of the magnetic field or the electric field is maintained during the cooling. (Supplementary Note 15) Rotating particles for display manufactured by the method according to any one of Supplementary Notes 7 to 14. (Supplementary Note 16) A particle having a region having both a different color and a different charging characteristic, and a display for enabling image display by rotating the particle by the action of an electric field externally applied to a layer containing the particle. Rotating particles for display, characterized in that the particles contain coloring agents having different hues, and one of them is a magnetophoretic particle. (Supplementary Note 17) A particle having a region having both a different color and a different charging characteristic, and a display for enabling image display by rotating the particle by the action of an electric field externally applied to a layer containing the particle. A rotating particle, wherein the particles contain colorants having different hues, one of which is a magnetophoretic particle or an electrophoretic particle, and the other is stably dispersed in the particle. Rotating particles. (Supplementary Note 18) A particle having a region in which both the color and the charging characteristics are different, and a display for enabling image display by rotating the particle by the action of an electric field externally applied to a layer containing the particle. A method for producing rotating particles, wherein two types of materials having both different colors and different charging characteristics are filled in through holes provided in a molding sheet to produce a preformed joint in which the two types of materials are bonded. Then, this preformed combined body is
A method for producing a rotating particle for display, comprising molding into a spherical particle composed of two hemispheres composed of each kind of material. (Supplementary Note 19) A sheet is prepared from each of the two types of materials, and the sheet for molding is sandwiched between these two sheets.
19. The method according to claim 18, wherein a laminate having a layer structure is formed, and the laminate is pressed to fill the through-holes with the respective materials to obtain the preformed joint. (Supplementary Note 20) Rotating particles for display manufactured by the method according to Supplementary Note 18 or 19. (Supplementary Note 21) A display layer formed by filling the rotating particles for display according to any one of Supplementary Notes 1 to 6, 15 to 17, and 20 into a void inside a sheet-like binder together with a transparent dielectric liquid. And a pair of opposed electrodes sandwiching the display layer. (Supplementary Note 22) The display rotating particles are those described in any one of Supplementary Notes 1 to 6, and a specific gravity S _{1 of the} dielectric liquid is provided.
And the specific gravity S ₂ of the liquid in the microcapsule is S ₁ ≧ S
23. The sheet-type display device according to supplementary note 21, which has a relationship of ₂ .

[0108]

As described above, according to the present invention, a display device can be driven at a lower voltage than usual by using light-weight microcapsules having a liquid inside as rotating particles, that is, display elements. Further, by making the specific gravity of the liquid inside the microcapsules smaller than the specific gravity of the liquid sealed together with the rotating particles of the microcapsules in the display device, a display device driven at a lower voltage can be provided.

Further, by forming particles from a wax or resin in which a colorant is dispersed, and utilizing any of the physical phenomena of magnetophoresis, electrophoresis, or sedimentation, two-color rotating particles having a stable shape can be obtained relatively. It can be easily manufactured in large quantities. By using the two-color rotating particles as a display element, a sheet-type display device with good contrast can be provided.

If a molding sheet provided with through holes is used, the amount of material of the preformed composite produced thereby becomes uniform.
Efficient provision of color rotating particles becomes possible.

[Brief description of the drawings]

FIG. 1 US Pat. Nos. 4,126,854 and 4,143.
FIG. 103 is a diagram illustrating a sheet-type display device using two-color rotating particles described in each specification of No. 103.

FIG. 2 is a diagram illustrating migration and rotation of two-color rotating particles by application of an electric field.

FIG. 3 is a diagram illustrating one embodiment of a two-color rotating particle according to the present invention.

FIG. 4 is a diagram illustrating one of coloring methods for obtaining two-color rotating particles according to the present invention.

FIG. 5 is a graph showing a relationship between temperature and viscosity of a wax material.

FIG. 6 is a diagram illustrating the production of two-color rotating particles using a molding sheet.

FIG. 7 is a perspective view of a molding sheet.

FIG. 8 is a diagram illustrating a sheet-type display device according to the present invention.

FIG. 9 is a diagram illustrating a test display device manufactured in Example 1.

FIG. 10 is a diagram illustrating a display device for testing manufactured in Example 3.

FIG. 11 is a diagram illustrating the production of a display layer in Example 5.

FIG. 12 is a diagram illustrating the production of a display layer in Example 6.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Microcapsule 12 ... Liquid 13 ... Coloring layer 14 ... Electrophoretic particle 21, 22 ... Material film for two-color particle production 25 ... Molding sheet 26 ... Through-hole 30, 31 '... Display device 31, 37 ... Glass substrate 32 ... Common electrode 33 Vertical spacer 34 Cell 35, 35 'Rotating particle 36 Individual electrode 100 Sheet type display device 101 Binder layer 102 Display rotating particle 103 Dielectric liquid 104, 105 Electrode

 ────────────────────────────────────────────────── ─── Continued from the front page (72) Inventor Makoto Fukuda 4-1-1, Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture Inside Fujitsu Limited

Claims (10)

[Claims] 1. A particle having on its surface a region having both a different color and a different charging characteristic. An image can be displayed by rotating the particle by the action of an electric field externally applied to a layer containing the particle. A rotating particle for display, characterized in that a liquid is encapsulated in a microcapsule having on its surface a region having both different color and charging characteristics. 2. Particles having regions having both different colors and different charging characteristics. A display capable of displaying an image by rotating the particles by the action of an electric field externally applied to a layer containing the particles. A method for producing rotating particles for
Create particles of wax or resin containing different types of colorants, and then move one colorant to localize in the particles to form regions that differ in both color and charging characteristics A method for producing rotating particles for display, comprising: 3. The movement of the colorant includes melting of the wax or softening of the resin by heating, migration of the colorant by at least application of a magnetic field, migration of the colorant by application of an electric field, or sedimentation of the colorant. 3. The method according to claim 2, wherein the method is performed by any of the methods. 4. Particles having regions having both different colors and different charging characteristics, and a display capable of displaying an image by rotating the particles by the action of an electric field externally applied to a layer containing the particles. Particles of wax or resin containing two kinds of coloring agents, and then one of the coloring agents is moved and localized in the particles to obtain both the color and the charging characteristics. Rotating particles for display manufactured by forming regions having different sizes. 5. A display which has a region having both a different color and a different charging characteristic, and displays an image by rotating the particle by the action of an electric field externally applied to a layer containing the particle. Rotating particles for display, comprising a coloring agent having a different hue in the particles, one of which is a magnetophoretic particle. 6. A particle having a region having both a different color and a different charging characteristic, and a display capable of displaying an image by rotating the particle by the action of an electric field externally applied to a layer containing the particle. Display, wherein the particles contain colorants having different hues in the particles, one of which is a magnetophoretic particle or an electrophoretic particle, and the other is stably dispersed in the particle. For rotating particles. 7. Particles having regions having both different colors and different charging characteristics, and a display which enables image display by rotating the particles by the action of an electric field externally applied to a layer containing the particles. A method for producing rotating particles for use, wherein two types of materials having both different colors and different charging characteristics are filled in through holes provided in a molding sheet, and a preformed combined body in which the two types of materials are bound is formed. Producing a preformed combined article into a spherical particle composed of two hemispheres each comprising said two types of materials. 8. A sheet is formed from each of the two types of materials, a laminate having a three-layer structure is formed between the sheets by sandwiching the molding sheet, and the laminate is pressed to form a laminate in the through hole. 8. The method of claim 7, wherein each of the materials is filled to obtain the preformed composite. 9. Particles having regions having both different colors and different charging characteristics, and a display which enables image display by rotating the particles by the action of an electric field externally applied to a layer containing the particles. Rotary particles, two types of materials having both different colors and different charging characteristics are filled in through holes provided in a molding sheet to prepare a preformed combined body in which the two types of materials are bound, Rotating particles for display manufactured by molding the preformed combination into spherical particles composed of two hemispheres each of the two materials. 10. A display formed by filling the rotating particles for display according to any one of claims 1, 4, 5, 6 and 9 into a space inside a sheet-like binder together with a transparent dielectric liquid. A sheet-type display device comprising: a layer; and a pair of opposed electrodes sandwiching the display layer.