JP5012839B2 - Display particle dispersion, display medium, and display device - Google Patents

Description

  The present invention relates to a display particle dispersion, a display medium, and a display device.

  An electrophoretic display medium has been actively studied as a display having a memory property. In this display method, display particles (electrophoretic particles) charged in a liquid are used, and the electrophoretic particles are enclosed in a cell by applying an electric field (two electrode substrates are stacked and an electrophoretic material is enclosed with a dispersion medium therebetween). Display is performed by alternately moving to the viewing surface and back surface of the configuration.

In the present technology, the display particles (electrophoretic particles) are important elements, and various technical developments have been made. For example, as a method for imparting electric charges to display particles for the purpose of migrating (moving) display particles, for example, a method of selecting a constituent material of the particles, a method of adding an additive, and the like are known ( For example, see Patent Documents 1 to 3). It is also known to form a display medium using two types of display particles having different charging polarities (for example, Patent Document 4).
JP 2004-279732 A Japanese Patent Publication No. 8-23005 Japanese Patent No. 3936588 Special Table 2007-508588

  The subject of the present application is given to each display particle in a system in which at least two types of display particles having different charge polarities are mixed, compared to the case where the two types of display particles having a specific relationship are not applied. It is an object to provide a particle dispersion for display in which fluctuations in charge polarity and charge amount are suppressed.

The above problem is solved by the following means. That is,
The invention according to claim 1
The first ionic polymer having a coloring agent and a first ionic polymer having a counter ion and moving in response to an electric field has a different charging polarity from the coloring agent and the first ionic polymer. And a second display particle comprising a second ionic polymer having the same structure as a counter ion of the first ionic polymer in a polymer chain structure, and moving according to an electric field;
A dispersion medium for dispersing the first colored particles and the second colored particles;
A particle dispersion for display comprising:

The invention according to claim 2
The display particle dispersion according to claim 1, wherein the counter ion of the first ionic polymer is an amine compound ion.

The invention according to claim 3
The display particle dispersion according to claim 1, wherein the counter ion of the first ionic polymer is a quaternary ammonium ion.

The invention according to claim 4
A pair of substrates, at least one of which is translucent,
The display dispersion liquid according to any one of claims 1 to 3, wherein the display dispersion liquid is sealed between the pair of substrates.
A display medium comprising:

The invention according to claim 5
A pair of electrodes, at least one of which is translucent,
A region having a display dispersion liquid according to any one of claims 1 to 3, provided between the pair of electrodes;
A display medium comprising:

The invention according to claim 6
A display medium according to claim 4 or 5, and
Voltage applying means for applying a voltage between the pair of substrates of the display medium;
A display device comprising:

According to the invention according to claim 1, in a system in which at least two kinds of display particles having different charge polarities are mixed, the two kinds of display particles having a specific relationship are compared with each other. Variations in the charge polarity and charge amount applied to the particle display particles are suppressed.
According to the invention concerning Claim 2, compared with the case where other kinds of counterion species are applied, fluctuations in the charge polarity and charge amount imparted to the display particles are suppressed.
According to the invention concerning Claim 3, compared with the case where other kinds of counterion species are applied, fluctuations in the charge polarity and the charge amount imparted to the display particles are suppressed.
According to the invention which concerns on Claim 4, compared with the case where it does not have this structure, a mixed color display is suppressed.
According to the invention which concerns on Claim 5, compared with the case where it does not have this structure, a mixed color display is suppressed.
According to the invention which concerns on Claim 6, compared with the case where it does not have this structure, mixed color display is suppressed.

  Hereinafter, embodiments of the present invention will be described.

(Particle dispersion for display)
The display particle dispersion according to this embodiment includes display particles (a group thereof) that move according to an electric field, and a dispersion medium for dispersing the display particles. The display particles are particles that move in response to an electric field, have a charging polarity when dispersed in the dispersion medium, and move in the dispersion medium in response to the formed electric field. The display particles have at least two types of display particles having different charging polarities. Specifically, the display particles include a first display particle including a colorant and a first ionic polymer having a counter ion, the colorant, and the first ionic polymer. A second display particle that includes a second ionic polymer having a charge chain polarity different from that of the counter ion of the first ionic polymer in a polymer chain structure, and that moves according to an electric field And have.

  The display dispersion according to this embodiment has the above-described configuration, so that the two types of display particles having a specific relationship are mixed in a system in which at least two types of display particles having different charging polarities are mixed. Compared to the case where the charge is not applied, fluctuations in the charge polarity and charge amount applied to the display particles are suppressed. As a result, when the display dispersion according to the present embodiment is applied to a display medium and a display device, fluctuations in the charge polarity and charge amount of the display particles are suppressed, so that the charge polarity and charge amount of the display particles are stable. As a result, mixed color display is suppressed. The reason for this is not clear, but the ionic polymer having the same structure as the counter ion of the first ionic polymer constituting the first display particles (counter ion with respect to the charged group of the polymer) in the polymer chain structure. Is applied to the second ionic polymer constituting the second display particles, the dissociation of the counter ion of the first ionic polymer is promoted while the acid-base dissociation equilibrium is considered to be stable. It is thought that fluctuations in the charge polarity and charge amount of the display particles of each other may be suppressed. For this reason, this embodiment is particularly effective when the display particles are used, because the charge polarity and the charge amount vary greatly and are difficult to use alone.

  In the display dispersion according to the present embodiment, the dispersion of the charge polarity and charge amount of the display particles is suppressed without adding an additive separately. Viscosity fluctuation (for example, increase in viscosity) and conductivity fluctuation (for example, increase in conductivity) are also suppressed. However, this does not mean that the additive is not included in the dispersion medium at all, and it is needless to say that the additive may be additionally included in the dispersion medium.

Hereinafter, the display particles will be described.
The first display particles include a colorant and a first ionic polymer, and may include other compounding materials as necessary. On the other hand, the second display particles having a different charge polarity from the first display particles are configured to include a colorant and a second ionic polymer, and include other blending materials as necessary. It may be. The second ionic polymer is a second ionic polymer having the same structure as the counter ion of the first ionic polymer in the polymer chain structure.

  Here, the ionic polymer is a polymer having a charged group. Specifically, the ionic polymer has, for example, a cationic polymer having a cationic group as a charged group or an anionic group as a charged group. It has an anionic polymer. This ionic polymer has a counter ion as a salt of these charged groups (cationic group or anionic group). Examples of the cationic group as the charging group include an amino group and a quaternary ammonium group, and positively charged polarity is imparted to the particles by this cationic group. On the other hand, examples of the anionic group as the charging group include a phenol group, a carboxyl group, a sulfonic acid group, a phosphoric acid group, and a tetraphenylboron group. The anionic group imparts a negatively charged polarity to the particles. The

  That is, when the first ionic polymer is a cationic polymer, the second ionic polymer is an anionic polymer. On the other hand, when the first ionic polymer is an anionic polymer, the second ionic polymer is a cationic polymer. The second ionic polymer has the same structure as the counter ion as a salt of the cationic group or anionic group of the first ionic polymer in the polymer chain structure of the second ionic polymer. It has the same structure as the counter ion in the structural unit of the main chain or side chain. More specifically, the monomer component constituting the second ionic polymer has, for example, the same structure as the counter ion of the first ionic polymer, or two single components in the second ionic polymer. It means that the structural unit formed as a result of the condensation polymerization of the monomer has the same structure as the counter ion of the first ionic polymer. However, the same structure as the counter ion means that the structure other than the terminal structure for having the polymer chain structure constituting the second ionic polymer is the same structure.

  In this embodiment, the same structure as the counter ion of the first ionic polymer has the same structure as the counter ion of the second ionic polymer, in addition to the polymer chain structure of the second ionic polymer. However, you may have in the polymer chain structure of a 1st ionic polymer. That is, the first ionic polymer and the second ionic polymer may have the same relationship between the counter ion and the polymer chain structure.

  Next, the first ionic polymer and the second ionic polymer (both may be collectively referred to as ionic polymers) will be described. Specifically, the ionic polymer may be, for example, a homopolymer of a monomer having a charging group, or a monomer having a charging group and another monomer (having no charging group). Monomer). Examples of the monomer having a charging group include a monomer having a cationic group (hereinafter referred to as a cationic monomer) and a monomer having an anionic group (hereinafter referred to as an anionic monomer). The description such as “(meth) acrylate” is an expression including both “acrylate” and “methacrylate”. The same applies hereinafter.

Examples of the cationic monomer include the following. Specifically, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dibutylaminoethyl (meth) acrylate, N, N-hydroxyethylaminoethyl (meta) ) Acrylate, N-ethylaminoethyl (meth) acrylate, N-octyl-N-ethylaminoethyl (meth) acrylate, N, N-dihexylaminoethyl (meth) acrylate and other aliphatic amino groups (meth) Acrylates, aromatic substituted ethylene monomers having nitrogen-containing groups such as dimethylaminostyrene, diethylaminostyrene, dimethylaminomethylstyrene, dioctylaminostyrene,
Vinyl-N-ethyl-N-phenylaminoethyl ether, vinyl-N-butyl-N-phenylaminoethyl ether, triethanolamine divinyl ether, vinyl diphenylaminoethyl ether, N-vinylhydroxyethylbenzamide, m-aminophenyl vinyl ether Nitrogen-containing vinyl ether monomers such as vinylamine, pyrroles such as N-vinylpyrrole, pyrrolines such as N-vinyl-2-pyrroline and N-vinyl-3-pyrroline, N-vinylpyrrolidine, vinylpyrrolidineaminoe Ether, pyrrolidines such as N-vinyl-2-pyrrolidone, imidazoles such as N-vinyl-2-methylimidazole, imidazolines such as N-vinylimidazoline, indoles such as N-vinylindole, N-vinylindoline, etc. Inn of Phosphorus, N-vinylcarbazole, carbazoles such as 3,6-dibromo-N-vinylcarbazole, pyridines such as 2-vinylpyridine, 4-vinylpyridine, 2-methyl-5-vinylpyridine, (meth) acrylic Piperidines such as piperidine, N-vinylpiperidone and N-vinylpiperazine, quinolines such as 2-vinylquinoline and 4-vinylquinoline, pyrazoles such as N-vinylpyrazole and N-vinylpyrazoline, and oxazoles such as 2-vinyloxazole , Oxazines such as 4-vinyloxazine and morpholinoethyl (meth) acrylate.
Moreover, as a cationic monomer which is particularly desirable from the viewpoint of versatility, (meth) acrylates having an aliphatic amino group such as N, N-dimethylaminoethyl (meth) acrylate and N, N-diethylaminoethyl (meth) acrylate In particular, it is desirable to use a quaternary ammonium salt structure before or after polymerization. Quaternary ammonium chloride can be obtained by reacting the above compound with alkyl halides or tosylate esters.

On the other hand, as an anionic monomer, the following are mentioned, for example.
Specifically, among the anionic monomers, carboxylic acid monomers include (meth) acrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid, or anhydrides thereof and monoalkyl esters thereof. And vinyl ethers having a carboxyl group such as carboxyethyl vinyl ether and carboxypropyl vinyl ether.
Examples of the sulfonic acid monomer include styrene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, 3-sulfopropyl (meth) click acid ester, bis- (3-sulfopropyl) -itaconic acid ester, and salts thereof. There is. In addition, there are sulfuric acid monoesters of 2-hydroxyethyl (meth) acrylic acid and salts thereof.
Examples of phosphoric acid monomers include vinylphosphonic acid, vinyl phosphate, acid phosphoxyethyl (meth) acrylate, acid phosphoxypropyl (meth) acrylate, bis (methacryloxyethyl) phosphate, diphenyl-2-methacryloyloxyethyl phosphate, diphenyl There are 2-acryloyloxyethyl phosphate, dibutyl-2-methacryloyloxyethyl phosphate, dibutyl-2-acryloyloxyethyl phosphate, dioctyl-2- (meth) acryloyloxyethyl phosphate, and the like.
Desirable anionic monomers are those having (meth) acrylic acid or sulfonic acid, and more preferably those having a structure of an ammonium salt before or after polymerization. Ammonium salts are prepared by reacting with tertiary amines or quaternary ammonium hydroxides.

  Other monomers include nonionic monomers (nonionic monomers) such as (meth) acrylonitrile, (meth) acrylic acid alkyl esters, (meth) acrylamide, ethylene, propylene. , Butadiene, isoprene, isobutylene, N-dialkyl substituted (meth) acrylamide, styrene, vinyl carbazole, styrene, styrene derivatives, polyethylene glycol mono (meth) acrylate, vinyl chloride, vinylidene chloride, isoprene, butadiene, N-vinyl pyrrolidone, hydroxy Examples include ethyl (meth) acrylate and hydroxybutyl (meth) acrylate.

  Here, the copolymerization ratio of the monomer having a charging group and another monomer is changed according to the desired charge amount of the particles. Usually, the copolymerization ratio of the monomer having a charged group and another monomer is selected in the range of 1: 100 to 100: 0 in terms of the molar ratio.

  The weight average molecular weight of the ionic polymer is preferably 1,000 or more and 1,000,000 or less, and more preferably 10,000 or more and 200,000 or less.

  Here, a combination of a cationic polymer and an anionic polymer, which is a specific combination of the first ionic polymer and the second ionic polymer, will be exemplified. That is, the other polymer species with respect to the counter ion of one polymer is illustrated.

  Examples of the cationic polymer species constituting the cationic polymer with respect to the counter ion of the anionic polymer include, for example, as the counter ion of the anionic polymer, a cation of ethanolamine salt, and as the anionic polymer species, dimethylamine. Examples thereof include polymers having an ethanolamine structure as a structural unit, such as -epochrohydrin condensation polymer and ethylenediamine-epochrohydrin condensation polymer.

  Among these, it is preferable that the first ionic polymer is an anionic polymer and the counter ion is an amine compound ion (particularly a quaternary ammonium ion). If the counter ion is an amine compound ion (especially quaternary ammonium ion), the same structure as that of the amine compound (especially quaternary ammonium ion) can be stably formed, and the polymer chain structure of the second ionic polymer (cationic polymer). As compared with the case where other types of counter ions are applied, fluctuations in the charge polarity and the charge amount imparted to the display particles having a specific counter ion (first display particles) are suppressed. The

  Next, the colorant will be described. As the colorant, organic or inorganic pigments, oil-soluble dyes, etc. can be used, magnetic powders such as magnetite and ferrite, carbon black, titanium oxide, magnesium oxide, zinc oxide, phthalocyanine copper-based cyan colorant, Known colorants such as an azo yellow color material, an azo magenta color material, a quinacridone magenta color material, a red color material, a green color material, and a blue color material can be used. Specifically, aniline blue, calcoil blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black, rose bengal, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 57: 1, C.I. I. Pigment yellow 97, C.I. I. Pigment blue 15: 1, C.I. I. Pigment Blue 15: 3, etc. are exemplified as typical examples.

  The blending amount of the colorant is desirably 10% by mass or more and 99% by mass or less, and desirably 30% by mass or more and 99% by mass or less with respect to the polymer having a charging group.

Next, other compounding materials will be described. Examples of other compounding materials include a charge control agent and a magnetic material.
As the charge control agent, known materials used for toner materials for electrophotography can be used. For example, cetyl pyridium chloride, BONTRON P-51, BONTRON P-53, BONTRON E-84, BONTRON E-81 (above) Quaternary ammonium salts such as those manufactured by Orient Chemical Co., Ltd., salicylic acid metal complexes, phenol condensates, tetraphenyl compounds, metal oxide particles, and metal oxide particles surface-treated with various coupling agents.

As the magnetic material, an inorganic magnetic material or an organic magnetic material color-coated as necessary is used. Further, a transparent magnetic material, in particular, a transparent organic magnetic material does not hinder the color development of the color pigment, and the specific gravity is smaller than that of the inorganic magnetic material, and is more desirable.
Examples of the colored magnetic material (color-coated material) include small-diameter colored magnetic powder described in JP-A-2003-131420. A material provided with magnetic particles serving as nuclei and a colored layer laminated on the surface of the magnetic particles is used. The colored layer may be selected by coloring the magnetic powder opaque with a pigment or the like, but it is desirable to use, for example, a light interference thin film. This optical interference thin film is a thin film having a thickness equivalent to the wavelength of light made of an achromatic material such as SiO ₂ or TiO ₂ and selectively reflects the wavelength of light by optical interference in the thin film. It is.

  Here, the display particles may be particles having a surface bonded or coated with a silicone-based polymer. The silicone polymer is, for example, a polymer compound having a silicone chain, and more specifically, a compound having a silicone chain (silicone graft chain) as a side chain with respect to the main chain of the main polymer compound. Is good.

  As one of the silicone-based polymers, for example, at least a silicone chain component and, if necessary, a reactive component, a copolymer component having a charged group, and other copolymer components (a copolymer component having no charged group) are included. The copolymer which copolymerized 1 type is mentioned suitably. In addition, a monomer may be used for the raw material of the copolymerization component (especially silicone chain component) in the said copolymer, and a macromonomer may be used. This "macromonomer" is a generic term for oligomers having a polymerizable functional group (degree of polymerization of about 2 or more and about 300 or less) or polymers, and has the properties of both polymers and monomers. is there.

  As the silicone chain component, a dimethyl silicone monomer having a (meth) acrylate group at one end (for example, manufactured by Chisso: Silaplane: FM-0711, FM-0721, FM-0725, etc., Shin-Etsu Silicone Co., Ltd .: X -22-174DX, X-22-2426, X-22-2475, etc.).

  Examples of the reactive component include glycidyl (meth) acrylate having an epoxy group, and isocyanate monomers having an isocyanate group (Showa Denko: Karenz AOI, Karenz MOI).

  As the copolymerization component having a charging group and other copolymerization components (copolymerization components having no charging group), the monomer having a charging group described in the polymer having a charging group, other monomers ( Those mentioned in (monomers not having a charging group) are applied.

  In the silicone polymer, the mass ratio of the silicone chain component to the whole polymer is 3% or more and 60% or less, preferably 5% or more and 40% or less. By setting it within this range, for example, other properties (charging polarity imparting and charge amount control) are realized while imparting stable dispersibility to the particles.

  Examples of the silicone polymer include a silicone compound having an epoxy group at one end (silicone compound represented by the following structural formula 1) in addition to the copolymer. Examples of the silicone compound having an epoxy group at one end include X-22-173DX manufactured by Shin-Etsu Silicone Co., Ltd.

In Structural Formula 1, R ₁ ′ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. n represents a natural number (for example, 1 to 1000, preferably 3 to 100). x represents an integer of 1 to 3.

  Examples of the silicone polymer include a dimethyl silicone monomer having a (meth) acrylate group at one end (silicone compound represented by the following structural formula 2: manufactured by Chisso Corporation: Silaplane: FM-0711, FM-0721, FM -7725, Shin-Etsu Silicone Co., Ltd .: X-22-174DX, X-22-2426, X-22-2475, etc.) and glycidyl (meth) acrylate or isocyanate monomer (Showa Denko: Karenz AOI, Karenz MOI) A copolymer comprising at least two components is also preferred.

In Structural Formula 2, R ₁ represents a hydrogen atom or a methyl group. R ₁ ′ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. n represents a natural number (for example, 1 to 1000, preferably 3 to 100). x represents an integer of 1 to 3.

  The weight average molecular weight of the silicone polymer is desirably 500 or more and 1,000,000 or less, and more desirably 1,000 or more and 1,000,000 or less.

Next, a method for producing display particles will be described.
The method for producing display particles includes, for example, a method in which an ionic polymer, a colorant, a first solvent, and the first solvent are incompatible with each other, have a boiling point lower than that of the first solvent, and dissolve the ionic polymer. A step of stirring and emulsifying a mixed solution containing two solvents, and removing the second solvent from the emulsified mixed solution, and coloring particles (display particles) containing the ionic polymer and the colorant. It is preferable to have the process of producing | generating. When display particles are produced by a so-called liquid drying method, display particles having particularly stable dispersibility and charging characteristics can be obtained.

  This method may be used as a display particle dispersion containing display particles and a dispersion medium as it is by using a dispersion medium used for the display medium as the first solvent. Thereby, in the method for producing display particles according to the present embodiment, the display particle dispersion using the first solvent as the dispersion medium can be easily produced without going through the washing / drying step by passing through the above steps. The Of course, in order to improve the electrical characteristics, it is possible to carry out cleaning of particles (removal of ionic impurities) and replacement of the dispersion medium. Hereinafter, it demonstrates according to a process.

  The production method of the display particles is not limited to the above production method. For example, colored particles (display particles) by other known methods (coacervation method, dispersion polymerization method, suspension polymerization method, etc.) You may employ | adopt the method of forming.

  Hereinafter, details of an example of a method for producing display particles to which the above-described drying method in liquid is applied will be described. Hereinafter, it demonstrates according to a process.

-Emulsification process-
In the emulsification step, for example, the solution containing the first solvent, the ionic polymer, the colorant, and the first solvent are incompatible with each other and have a lower boiling point than the first solvent and dissolve the ionic polymer. The two solutions of the second solvent and the second solvent are mixed, stirred and emulsified. Moreover, it is also possible to mix | blend other compounding materials (a charge control agent, a pigment dispersant, etc.) other than the said material in the mixed solution to emulsify as needed.

  In the emulsification step, by stirring the mixed solution, the low-boiling point second solvent is emulsified in a continuous phase using the high-boiling point solution as the first solvent, forming a droplet-like dispersed phase. Note that the ionic polymer and the colorant are dissolved or dispersed in the second solvent.

  In the emulsification step, each material may be mixed sequentially in the mixed solution. For example, first, a mixed solution in which an ionic polymer, a colorant, and a second solvent are mixed is prepared. And it is good to emulsify so that a mixed solution may be disperse | distributed and mixed in a 1st solvent, and a mixed solution may be disperse | distributed to a particulate form in a 1st solvent.

  Stirring for emulsification is performed using, for example, a known stirring device (for example, a homogenizer, a mixer, an ultrasonic crusher, etc.). In order to suppress the temperature rise during emulsification, the temperature of the mixed solution during emulsification is desirably maintained at 0 ° C. or higher and 50 ° C. or lower. For example, the stirring speed of a homogenizer or mixer for emulsification, the output intensity of the ultrasonic crusher, and the emulsification time are set according to the desired particle diameter.

Next, the first solvent will be described.
The first solvent is used as a poor solvent capable of forming a continuous phase in a mixed solution, and examples thereof include petroleum-derived high-boiling solvents such as paraffinic hydrocarbon solvents, silicone oils, and fluorinated liquids. Although not, silicone oil is preferred.

  Specifically, silicone oils having hydrocarbon groups bonded to siloxane bonds (for example, dimethyl silicone oil, diethyl silicone oil, methyl ethyl silicone oil, methyl phenyl silicone oil, diphenyl silicone oil, etc.), modified silicone oil ( For example, fluorine-modified silicone oil, amine-modified silicone oil, carboxyl-modified silicone oil, epoxy-modified silicone oil, alcohol-modified silicone oil, and the like. Among these, dimethyl silicone is particularly desirable from the viewpoint of high safety, chemical stability, long-term reliability, and high resistivity.

  The viscosity of the silicone oil is desirably 0.1 mPa · s or more and 20 mPa · s or less, and more desirably 0.1 mPa · s or more and 2 mPa · s or less in an environment at a temperature of 20 ° C. By setting the viscosity within the above range, the moving speed of particles, that is, the display speed can be improved. In addition, Tokyo Keiki B-8L type | mold viscosity meter is used for the measurement of this viscosity.

  Examples of the paraffinic hydrocarbon solvent include normal paraffinic hydrocarbons and isoparaffinic hydrocarbons having 20 or more carbon atoms (boiling point of 80 ° C. or higher), but it is desirable to use isoparaffins for reasons such as safety and volatility. . Specifically, Shell Sol 71 (manufactured by Shell Petroleum), Isopar O, Isopar H, Isopar K, Isopar L, Isopar G, Isopar M (Isopar is a trade name of Exxon), IP Solvent (manufactured by Idemitsu Petrochemical), etc. Can be mentioned.

Next, the second solvent will be described.
The second solvent is used as a good solvent that can form a dispersed phase in the mixed solution. Further, a material that is incompatible with the first solvent, has a boiling point lower than that of the first solvent, and dissolves a polymer having a charged group is selected. Here, incompatible means a state in which a plurality of substance systems exist in independent phases without being mixed. Moreover, dissolution refers to a state where the residue of the dissolved material is not visually confirmed.

  Specific examples of the second solvent include water, lower alcohols having 5 or less carbon atoms (eg, methanol, ethanol, propanol, isopropyl alcohol, etc.), tetrahydrofuran, acetone, and other organic solvents (eg, toluene, dimethylformamide, dimethyl). Acetamide) and mixed solvents thereof, but are not limited thereto.

  The second solvent is selected from those having a boiling point lower than that of the first solvent because it can be removed from the mixed solution system, for example, by heating under reduced pressure. The boiling point is, for example, 50 ° C. or more and 200 ° C. or less. Desirably, more desirably, it is 50 ° C or higher and 150 ° C or lower.

-Second solvent removal step-
Next, in the second solvent removal step, the second solvent (low boiling point solvent) is removed from the mixed solution emulsified in the emulsification step. By removing the second solvent, the ionic polymer is precipitated and particleized in the dispersed phase formed by the second solvent while encapsulating other materials, and colored particles are obtained. Further, the polymer forming the particles may contain various additives such as pigment dispersants and weathering stabilizers. For example, a commercially available pigment dispersion contains a polymer substance and a surfactant for dispersing the pigment. When this is used, the colored particles are used together with a resin for controlling charging, as well as these resins. Substance will be included. The particle-shaped colored particles are applied as display particles.

Here, examples of the method for removing the second solvent include a method of heating the mixed solution and a method of reducing the pressure of the mixed solution, and these methods may be combined.
When the mixed solution is heated to form the second solvent, the heating temperature is preferably 30 ° C. or higher and 200 ° C. or lower, and more preferably 50 ° C. or higher and 180 ° C. or lower. The reactive silicon polymer or the reactive long-chain alkyl polymer may be reacted with the particle surface by heating in the second solvent removing step. On the other hand, when the mixed solution is depressurized to remove the second solvent, the depressurization pressure is preferably 0.01 mPa to 200 mPa, and more preferably 0.01 mPa to 20 mPa.

  In addition, the manufacturing method of the display particles is not limited to the above-described manufacturing method, and for example, colored particles (display particles) by a known method (pulverization method, coacervation method, dispersion polymerization method, suspension polymerization method, or the like). The method of forming is adopted. In each method, a dispersion medium used for a display medium may be used as a solvent (a solvent finally remaining in the manufacturing method), and the display medium may be used as a display particle dispersion liquid including display particles and a dispersion medium after production. Thereby, in the manufacturing method of the display particle, the display particle dispersion using the solvent to be used as the dispersion medium can be easily produced without going through the washing / drying process by passing through each manufacturing process. Of course, in order to improve electrical characteristics, cleaning of particles (removal of ionic impurities) and replacement of a dispersion medium are also performed.

Here, a method for bonding or coating the silicone polymer to the display particles will be described. Examples of the method for bonding or coating the silicone polymer to the display particles include a method using a coacervation method. Specifically, for example, the produced display particles are dispersed in a first solvent in which a silicone-based polymer is dissolved, the second solvent is dropped into the second solvent and emulsified, and then the first solvent. And a method in which the silicone polymer is precipitated on the white mother particles and reacted to bind or cover the surfaces of the display particles. Suitable examples of the first solvent include isopropyl alcohol (IPA), methanol, ethanol, butanol, tetrahydrofuran, ethyl acetate, and butyl acetate. Among these, isopropyl alcohol (IPA) is desirable from the viewpoint of providing stable dispersion stability and charging characteristics. On the other hand, a silicone oil is preferably exemplified as the second solvent.
The method for bonding or coating the silicone polymer to the display particles is not limited to the above method.

  Through the above steps, display particles are obtained, and a display particle dispersion containing the display particles is obtained. In addition, for the obtained display particle dispersion, acid, alkali, salt, dispersant, dispersion stabilizer, stabilizer for anti-oxidation or ultraviolet absorption, antibacterial agent, preservative, etc., if necessary May be added.

  An anionic surfactant, a cationic surfactant, an amphoteric surfactant, a nonionic surfactant, a fluorine surfactant, a silicone surfactant as a charge control agent for the obtained display particle dispersion. Silicone cationic compounds, silicone anionic compounds, metal soaps, alkyl phosphate esters, succinimides, and the like may be added.

Charge control agents include ionic or nonionic surfactants, block or graft copolymers composed of a lipophilic part and a hydrophilic part, polymers such as cyclic, star-like or dendritic polymers (dendrimers) Compounds with a chain skeleton, metal complexes of salicylic acid, metal complexes of catechol, metal-containing bisazo dyes, tetraphenylborate derivatives, copolymers of polymerizable silicone macromers (Tisso: Silaplane) and anionic monomers or cationic polymers, etc. Is mentioned.
More specific examples of the ionic and nonionic surfactants are as follows. Nonionic activators include polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, And fatty acid alkylolamide. Examples of the anionic surfactant include alkylbenzene sulfonate, alkylphenyl sulfonate, alkyl naphthalene sulfonate, higher fatty acid salt, sulfate of higher fatty acid ester, sulfonic acid of higher fatty acid ester, and the like. Examples of the cationic surfactant include primary to tertiary amine salts and quaternary ammonium salts. These charge control agents are desirably 0.01% by mass or more and 20% by mass or less, and particularly desirably 0.05% by mass or more and 10% by mass or less with respect to the solid content of the particles.

In addition, the obtained display particle dispersion may be diluted with, for example, a first solvent (a first solvent containing a dispersant as necessary) or the like as necessary.
The concentration of the display particles in the display particle dispersion is variously selected depending on display characteristics, response characteristics, or use thereof, but is preferably selected in a range of 0.1 mass% to 30 mass%. When mixing multi-particles having different colors, the total amount of the particles is preferably within this range. If the amount is less than 0.1% by mass, the display density may be too low. If the amount is more than 30% by mass, there is a problem that the display speed is slow or aggregation tends to occur.

  The display particle dispersion according to the present embodiment is obtained by preparing first display particles (dispersion liquid) and second display particles (dispersion liquid), respectively, and mixing them.

  The display particle dispersion according to this embodiment is used for an electrophoretic display medium, an electrophoretic light control medium (light control element), a liquid toner of a liquid developing electrophotographic system, and the like. In addition, as an electrophoretic display medium and an electrophoretic light control medium (light control element), a known method of moving particles in a direction perpendicular to the electrode (substrate) surface is different from the horizontal direction. There is a method of moving to (so-called in-plane type element), or a hybrid element combining these.

(Display medium, display device)
Hereinafter, examples of the display medium and the display device according to the embodiment will be described.

-First embodiment-
First, the first embodiment will be described. FIG. 1 is a schematic configuration diagram of a display device according to the first embodiment. FIG. 2 is an explanatory diagram schematically illustrating a movement mode of the particle group when a voltage is applied between the substrates of the display medium of the display device according to the first embodiment.

  The display device 10 according to the first embodiment relates to the present embodiment including the display particles and the dispersion medium according to the above embodiment as a particle dispersion liquid including the dispersion medium 50 of the display medium 12 and the particle group 34. In this mode, a display particle dispersion is applied. Specifically, among the particle groups 34, the first display particles are applied as the particle groups 34A, the second display particles are displayed as the particle groups 34B that exhibit a color different from that of the particle groups 34A and have different charging polarities. It is an applied form.

  As shown in FIG. 1, the display device 10 according to the first embodiment includes a display medium 12, a voltage application unit 16 that applies a voltage to the display medium 12, and a control unit 18.

  The display medium 12 includes a display substrate 20 that serves as an image display surface, a rear substrate 22 that faces the display substrate 20 with a gap, and holds a space between these substrates at a specific interval, and between the substrates of the display substrate 20 and the rear substrate 22. The gap member 24 is configured to include a plurality of cells, a particle group 34 enclosed in each cell, and a reflective particle group 36 having an optical reflection characteristic different from that of the particle group 34.

  The cell indicates a region surrounded by the display substrate 20, the back substrate 22, and the gap member 24. A dispersion medium 50 is enclosed in this cell. The particle group 34 (described in detail later) is composed of a plurality of particles. The particle group 34 is dispersed in the dispersion medium 50 and passes between the display substrate 20 and the back substrate 22 according to the electric field strength formed in the cell. It moves through the gap between the reflective particle groups 36.

  In addition, the gap member 24 is provided so as to correspond to each pixel when an image is displayed on the display medium 12, and cells are formed so as to correspond to each pixel, so that the display medium 12 can display each pixel. You may comprise so that it may become possible.

  Further, in the present embodiment, in order to simplify the description, the present embodiment will be described using a diagram focusing on one cell. Hereinafter, each configuration will be described in detail.

  First, the pair of substrates will be described. The display substrate 20 has a configuration in which a surface electrode 40 and a surface layer 42 are sequentially laminated on a support substrate 38. The back substrate 22 has a configuration in which a back electrode 46 and a surface layer 48 are laminated on a support substrate 44.

  The display substrate 20 or both the display substrate 20 and the back substrate 22 are translucent. Here, the translucency in the present embodiment indicates that the visible light transmittance is 60% or more.

  Examples of the support substrate 38 and the support substrate 44 include glass and plastics such as polyethylene terephthalate resin, polycarbonate resin, acrylic resin, polyimide resin, polyester resin, epoxy resin, and polyethersulfone resin.

  For the surface electrode 40 and the back electrode 46, oxides such as indium, tin, cadmium and antimon, composite oxides such as ITO, metals such as gold, silver, copper and nickel, organic materials such as polypyrrole and polythiophene are used. Is done. These can be used as a single layer film, a mixed film or a composite film, and are formed by vapor deposition, sputtering, coating, or the like. Moreover, the thickness is normally 100 to 2000 mm according to the vapor deposition method and the sputtering method. The back electrode 46 and the front electrode 40 may be formed in a desired pattern, for example, a matrix shape or a stripe shape enabling a passive matrix drive, by a conventionally known means such as etching of a conventional liquid crystal display medium or a printed circuit board. Good.

  Further, the surface electrode 40 may be embedded in the support substrate 38. Further, the back electrode 46 may be embedded in the support substrate 44. In this case, the materials of the support substrate 38 and the support substrate 44 are selected according to the composition of each particle of the particle group 34 and the like.

  The back electrode 46 and the surface electrode 40 may be separated from the display substrate 20 and the back substrate 22 and disposed outside the display medium 12.

  In the above description, the case where both the display substrate 20 and the back substrate 22 are provided with electrodes (the front electrode 40 and the back electrode 46) has been described. However, only one of them is provided, and active matrix driving is performed. Also good.

  In order to enable active matrix driving, the support substrate 38 and the support substrate 44 may include a TFT (thin film transistor) for each pixel. Since it is easy to laminate wiring and mount components, it is desirable to form the TFT on the back substrate 22 instead of the display substrate.

  If the display medium 12 is a simple matrix drive, the structure of the display device 10 having the display medium 12 described later can be simplified, and the active matrix drive using TFTs is simpler than the simple matrix drive. Display speed.

  Next, the gap member will be described. When the surface electrode 40 and the back electrode 46 are formed on the support substrate 38 and the support substrate 44, respectively, the electrodes between the electrodes that cause breakage of the surface electrode 40 and the back electrode 46 and adhesion of each particle of the particle group 34 are obtained. In order to prevent the occurrence of leakage, a surface layer 42 and a surface layer 48 as dielectric films are formed on the surface electrode 40 and the back electrode 46, respectively, as necessary.

  Examples of materials for forming the surface layer 42 and the surface layer 48 include polycarbonate, polyester, polystyrene, polyimide, epoxy, polyisocyanate, polyamide, polyvinyl alcohol, polybutadiene, polymethyl methacrylate, copolymerized nylon, ultraviolet curable acrylic resin, and fluorine resin. Etc. may be used.

  In addition to the insulating material described above, an insulating material containing a charge transport material may be used. Inclusion of a charge transport material improves particle chargeability by injecting particles into the particle, and when the charge amount of the particle becomes extremely large, the charge of the particle is leaked and the charge amount of the particle is stabilized. An effect is obtained.

Examples of the charge transport material include a hydrazone compound, a stilbene compound, a pyrazoline compound, and an arylamine compound that are hole transport materials. Further, a fluorenone compound, a diphenoquinone derivative, a pyran compound, zinc oxide, or the like, which is an electron transport material, may be used. Further, a self-supporting resin having a charge transporting property may be used.
Specific examples thereof include polyvinyl carbazole and polycarbonate obtained by polymerization of a specific dihydroxyarylamine and bischloroformate described in US Pat. No. 4,806,443. Since the dielectric film may affect the charging characteristics and fluidity of the particles, it is appropriately selected according to the composition of the particles. Since the display substrate which is one of the substrates needs to transmit light, it is desirable to use a transparent one of the above materials.

  Next, the gap member will be described. The gap member 24 for maintaining a gap between the display substrate 20 and the back substrate 22 is formed so as not to impair the light-transmitting property of the display substrate 20, and is a thermoplastic resin, a thermosetting resin, or an electron beam curing. It is made of resin, photo-curing resin, rubber, metal or the like.

The gap member 24 may be integrated with either the display substrate 20 or the back substrate 22. In this case, the support substrate 38 or the support substrate 44 is manufactured by performing etching processing, laser processing processing, press processing processing, printing processing, or the like using a previously manufactured mold.
In this case, the gap member 24 is fabricated on either the display substrate 20 side, the back substrate 22 side, or both.

  The gap member 24 may be colored or colorless, but is preferably colorless and transparent so as not to adversely affect the display image displayed on the display medium 12, and in this case, for example, transparent such as polystyrene, polyester, or acrylic Resin or the like is used.

  The particulate gap member 24 is also preferably transparent, and glass particles are used in addition to transparent resin particles such as polystyrene, polyester, or acrylic.

  Note that “transparent” means having a transmittance of 60% or more with respect to visible light.

  Next, the reflective particle group will be described. The reflective particle group 36 is an uncharged particle group, is composed of reflective particles having optical reflection characteristics different from that of the particle group 34, and functions as a reflective member that displays a color different from that of the particle group 34. is there. And it also has a function as a gap member to move without hindering movement between the display substrate 20 and the back substrate 22. That is, each particle of the particle group 34 is moved from the back substrate 22 side to the display substrate 20 side or from the display substrate 20 side to the back substrate 22 side through the gap between the reflective particle groups 36. As the color of the reflective particle group 36, for example, it is desirable to select white or black so as to be the background color. In the present embodiment, the case where the reflective particle group 36 is white is described, but the present invention is not limited to this color.

  As the reflective particle group 36, for example, particles in which a white pigment such as titanium oxide, silicon oxide, or zinc oxide is dispersed in polystyrene, polyethylene, polypropylene, polycarbonate, PMMA, acrylic resin, phenol resin, formaldehyde condensate, or the like are used. . Moreover, when applying particles other than white as the particles constituting the reflective particle group 36, for example, the above-described resin particles containing a pigment or dye of a desired color may be used. If the pigment or dye is, for example, RGB or YMC color, a general pigment or dye used for printing ink or color toner may be used.

  In order to enclose the reflective particle group 36 between the substrates, for example, an inkjet method or the like is performed. Further, when the reflective particle group 36 is fixed, for example, after the reflective particle group 36 is sealed, the particle group surface layer of the reflective particle group 36 is melted by heating (and pressurizing if necessary). It is performed while maintaining the gap.

  The size of the cell in the display medium 12 is closely related to the resolution of the display medium 12, and the display medium 12 capable of displaying a high-resolution image as the cell is smaller can be manufactured. The length of the twelve display substrates 20 in the plate surface direction is about 10 μm to 1 mm.

  In order to fix the display substrate 20 and the back substrate 22 to each other through the gap member 24, fixing means such as a combination of bolts and nuts, a clamp, a clip, and a substrate fixing frame are used. Also, fixing means such as an adhesive, heat melting, and ultrasonic bonding may be used.

  The display medium 12 configured as described above includes, for example, a bulletin board capable of storing and rewriting images, a circulation version, an electronic blackboard, an advertisement, a signboard, a flashing sign, electronic paper, an electronic newspaper, an electronic book, and a copier / printer. Used for document sheets etc.

  As described above, the display device 10 according to the present embodiment includes the display medium 12, the voltage application unit 16 that applies a voltage to the display medium 12, and the control unit 18 (FIG. 1). reference).

  The voltage application unit 16 is electrically connected to the front electrode 40 and the back electrode 46. In the present embodiment, the case where both the front electrode 40 and the back electrode 46 are electrically connected to the voltage application unit 16 will be described. However, one of the front electrode 40 and the back electrode 46 is grounded. The other may be connected to the voltage application unit 16.

  The voltage application unit 16 is connected to the control unit 18 so as to be able to exchange signals.

  The control unit 18 stores in advance various programs such as a CPU (Central Processing Unit) that controls the operation of the entire apparatus, a RAM (Random Access Memory) that temporarily stores various data, and a control program that controls the entire apparatus. It is also possible to configure as a microcomputer including a ROM (Read Only Memory).

  The voltage application unit 16 is a voltage application device for applying a voltage to the front electrode 40 and the back electrode 46, and applies a voltage according to the control of the control unit 18 between the front electrode 40 and the back electrode 46.

  Next, the operation of the display device 10 will be described. This operation will be described according to the operation of the control unit 18.

  Here, among the particle groups 34 enclosed in the display medium 12, the case where the particle group 34B is negatively charged and the particle group 34B is positively charged will be described. In the following description, it is assumed that the dispersion medium 50 is transparent and the reflective particle group 36 is white. That is, in the present embodiment, a case will be described in which the display medium 12 displays the colors presented by the movement of the particle group 34A and the particle group 34B, and displays white as the background color.

First, an initial operation signal indicating that a voltage is applied for a specific time so that the surface electrode 40 is a negative electrode and the back electrode 46 is a positive electrode is output to the voltage application unit 16. When a negative electrode and a voltage equal to or higher than the threshold voltage at which the concentration variation ends is applied between the substrates, the particles constituting the particle group 34A charged on the negative electrode move to the back substrate 22 side, (See FIG. 2A). On the other hand, particles constituting the particle group 34B charged to the positive electrode move to the display substrate 20 side and reach the display substrate 20 (see FIG. 2A).
At this time, as the color of the display medium 12 visually recognized from the display substrate 20 side, white as the color of the reflective particle group 36 is used as the background color, and the color exhibited by the particle group 34B is visually recognized. Note that the particle group 34 </ b> A is concealed by the reflective particle group 36 and is difficult to be visually recognized.

  The T1 time may be stored in advance in a memory such as a ROM (not shown) in the control unit 18 as information indicating the voltage application time in the voltage application in the initial operation. Then, information indicating this specific time may be read at the time of processing execution.

Next, the polarity of the voltage applied between the substrates is reversed between the surface electrode 40 and the back electrode 46, and when the voltage is applied with the surface electrode 40 as the positive electrode and the back electrode 46 as the negative electrode, the negative electrode is charged. The moving particle group 34A moves to the display substrate 20 side and reaches the display substrate 20 side (see FIG. 2B). On the other hand, the particles constituting the particle group 34B charged to the positive electrode move to the back substrate 22 side and reach the back substrate 22 (see FIG. 2B).
At this time, as the color of the display medium 12 visually recognized from the display substrate 20 side, white as the color of the reflective particle group 36 is used as the background color, and the color exhibited by the particle group 34A is visually recognized. The particle group 34 </ b> B is concealed by the reflective particle group 36 and is difficult to be visually recognized.

  Thus, in the display device 10 according to the present embodiment, the display is performed when the particle group 34 (particle group 34A, particle group 34B) reaches the display substrate 20 or the back substrate 22 and adheres thereto.

  Hereinafter, the present invention will be described more specifically with reference to examples.

[Example 1]
(Preparation of magenta particles (dispersion liquid))
Solution A (continuous phase) by dissolving 3 parts by mass of silicone-modified acrylic polymer (KP545 manufactured by Shin-Etsu Silicone) as an emulsifier in 97 parts by mass of dimethyl silicone oil (KF-96-2CS manufactured by Shin-Etsu Silicone) as a poor solvent Was prepared. Next, anionic styrene acrylic polymer / dimethylethanolamine neutralized product as an ionic polymer (polymer represented by the following structural formula 1, weight average molecular weight 18000, partial structure (A) [styrene acrylic polymer structural part] Acid value: 41) 7 parts by mass, 5 parts by mass of a magenta pigment dispersion as a colorant (Emacol: equivalent to 20 parts by mass of pigment solid content) and 85 parts by mass of water as a good solvent are mixed. Solution B (dispersed phase) was prepared. Emulsification was carried out by mixing 80 parts by mass of solution A and 20 parts by mass of solution B to prepare an emulsion. The emulsification was performed for 10 minutes with an ultrasonic crusher (UH-600S manufactured by SMT).

  Next, the obtained emulsion is put into an eggplant flask and heated (65 ° C.) / Depressurized (10 mPa) with an evaporator while stirring to remove moisture (good solvent), and magenta pigment-containing electrophoretic particles (magenta A particle dispersion in which the particles were dispersed in silicone oil was obtained.

  The produced magenta pigment-containing migrating particles were measured by Fpar1000 (dynamic light scattering type particle distribution measuring device) manufactured by Otsuka Electronics Co., Ltd., and the average particle diameter of the particles was 287 nm. Further, the obtained particle dispersion was diluted with a dispersion medium (silicone oil) so as to have a solid content of 0.1 part by mass. A pair of electrode substrates facing each other with an electrode interval of 1 mm was immersed in the diluted particle dispersion, and a voltage (100 V) was applied between the electrode substrates. As a result, when particles were attached to the electrode substrate and the charge polarity of the particles was evaluated, it was found that the same amount of particles adhered to any electrode substrate, and the obtained particles were charged half positively and negatively. .

(Preparation of cyan particles (dispersion liquid))
Solution A (continuous phase) by dissolving 3 parts by mass of silicone-modified acrylic polymer (KP545 manufactured by Shin-Etsu Silicone) as an emulsifier in 97 parts by mass of dimethyl silicone oil (KF-96-2CS manufactured by Shin-Etsu Silicone) as a poor solvent Was prepared. Next, 7 parts by mass of a cationic dimethylamine / epochrohydrin-based polymer (polymer represented by the following structural formula 2, weight average molecular weight 2600) as an ionic polymer, a cyan pigment dispersion (Sanyo dye) as a colorant Emacol: equivalent to 20 parts by mass of pigment solid content) and 5 parts by mass of water as a good solvent were mixed to prepare a solution B (dispersed phase). Emulsification was carried out by mixing 80 parts by mass of solution A and 20 parts by mass of solution B to prepare an emulsion. The emulsification was performed for 10 minutes with an ultrasonic crusher (UH-600S manufactured by SMT).

  Next, the obtained emulsion is put into an eggplant flask and heated (65 ° C.) / Reduced pressure (10 mPa) with an evaporator while stirring to remove moisture (good solvent), and magenta pigment-containing electrophoretic particles (cyan A particle dispersion in which the particles were dispersed in silicone oil was obtained.

  The produced cyan pigment-containing migrating particles were measured by Fpar1000 (dynamic light scattering type particle distribution measuring device) manufactured by Otsuka Electronics Co., Ltd., and the average particle diameter of the particles was 780 nm. Further, in the same manner as in the magenta particle dispersion, the charge polarity applied to the particles of the obtained particle dispersion was examined. As a result, the particles adhered to any electrode substrate (the positive electrode adhered slightly more). The obtained particles were found to be positively and negatively charged, although the number of negatively charged particles was slightly larger.

(Preparation of mixed particle dispersion)
The obtained magenta particle dispersion (solid content 0.1 parts by weight) 0.1 part by weight and cyan particle dispersion (solids 0.1 part by weight) 0.1 parts by weight are mixed to obtain mixed particles A dispersion was prepared. In the same manner as in the above magenta particle dispersion, the charging polarity of magenta particles and cyan particles in the obtained mixed dispersion was examined. As a result, it was found that all the magenta particles adhered only to the positive electrode substrate and were all negatively charged, while all the cyan particles adhered only to the negative electrode substrate and were all positively charged. As a result, it was found that color mixing was suppressed and cyan / magenta display was performed.

In addition, the above evaluation was performed in detail as follows. The results are shown in Table 1.
The particles attached to the positive electrode substrate and the negative electrode substrate were observed and evaluated according to the following evaluation criteria.
G3: No other particles were present on the electrode substrate (single color of cyan or magenta).
G2: Other particles are present on the electrode substrate, but the ratio is different (reddish cyan or bluish magenta).
G1: Other particles were present on the electrode substrate in the same ratio (blue).

[Example 2]
(Preparation of magenta particles (dispersion liquid))
Solution A (continuous phase) by dissolving 3 parts by mass of silicone-modified acrylic polymer (KP545 manufactured by Shin-Etsu Silicone) as an emulsifier in 97 parts by mass of dimethyl silicone oil (KF-96-2CS manufactured by Shin-Etsu Silicone) as a poor solvent Was prepared. Next, 7 parts by mass of a cationic dimethylamine / epochrohydrin-based polymer (polymer represented by the above structural formula 2, weight average molecular weight 7900) as an ionic polymer, magenta pigment dispersion (Sanyo dye) as a colorant Emacol: equivalent to 20 parts by mass of pigment solid content) and 5 parts by mass of water as a good solvent were mixed to prepare a solution B (dispersed phase). Emulsification was carried out by mixing 80 parts by mass of solution A and 20 parts by mass of solution B to prepare an emulsion. The emulsification was performed for 10 minutes with an ultrasonic crusher (UH-600S manufactured by SMT).

  Next, the obtained emulsion is put into an eggplant flask and heated (65 ° C.) / Depressurized (10 mPa) with an evaporator while stirring to remove moisture (good solvent), and magenta pigment-containing electrophoretic particles (magenta A particle dispersion in which the particles were dispersed in silicone oil was obtained.

  The produced magenta pigment-containing migrating particles were measured with an Fpar1000 (dynamic light scattering type particle distribution measuring device) manufactured by Otsuka Electronics Co., Ltd., and the average particle diameter of the particles was 504 nm. Further, when the charge polarity applied to the particles of the obtained particle dispersion was examined in the same manner as in Example 1, the particles adhered to any electrode substrate (the positive electrode adhered slightly more). The obtained particles were found to be positively and negatively charged, although the number of negatively charged particles was slightly larger.

(Preparation of cyan particles (dispersion liquid))
Solution A (continuous phase) by dissolving 3 parts by mass of silicone-modified acrylic polymer (KP545 manufactured by Shin-Etsu Silicone) as an emulsifier in 97 parts by mass of dimethyl silicone oil (KF-96-2CS manufactured by Shin-Etsu Silicone) as a poor solvent Was prepared. Next, an anionic styrene acrylic polymer / dimethylethanolamine neutralized product as an ionic polymer (polymer represented by the above structural formula 1, weight average molecular weight 1800, partial structure (A) [styrene acrylic polymer structural portion] Acid mixture 41) 7 parts by weight, 5 parts by weight of a cyan pigment dispersion as a colorant (Emacol manufactured by Sanyo Dye Co., Ltd .: equivalent to 20 parts by weight of pigment solids), and 85 parts by weight of water as a good solvent are mixed. B (dispersed phase) was prepared. Emulsification was carried out by mixing 80 parts by mass of solution A and 20 parts by mass of solution B to prepare an emulsion. The emulsification was performed for 10 minutes with an ultrasonic crusher (UH-600S manufactured by SMT).

  Next, the obtained emulsion is put into an eggplant flask and heated (65 ° C.) / Reduced pressure (10 mPa) with an evaporator while stirring to remove moisture (good solvent), and magenta pigment-containing electrophoretic particles (cyan A particle dispersion in which the particles were dispersed in silicone oil was obtained.

  The produced cyan pigment-containing migrating particles were measured with Fpar1000 (dynamic light scattering type particle distribution measuring device) manufactured by Otsuka Electronics Co., Ltd., and the average particle size of the particles was 176 nm. Further, when the charge polarity applied to the particles of the obtained particle dispersion was examined in the same manner as in Example 1, the same amount of particles adhered to any electrode substrate, and the obtained particles were half positive and negative. It was found that the battery was charged.

(Preparation of mixed particle dispersion)
The above-obtained magenta particle dispersion (solid content 0.1 part by mass) 0.1 part by mass and cyan particle dispersion (solid content 0.1 part by mass) 0.1 part by mass are mixed to disperse the mixed particles. A liquid was prepared. In the same manner as in Example 1, the charging polarity of magenta particles and cyan particles in the obtained mixed dispersion was examined. As a result, it was found that all the cyan particles adhered only to the positive electrode substrate and were all negatively charged, while all the magenta particles adhered only to the negative electrode substrate and were all positively charged. As a result, it was found that color mixing was suppressed and cyan / magenta display was performed. In addition, in the same manner as in Example 1, the above evaluation was performed in detail. The results are shown in Table 1.

[Example 3]
(Preparation of magenta particles (dispersion liquid))
Solution A (continuous phase) by dissolving 3 parts by mass of silicone-modified acrylic polymer (KP545 manufactured by Shin-Etsu Silicone) as an emulsifier in 97 parts by mass of dimethyl silicone oil (KF-96-2CS manufactured by Shin-Etsu Silicone) as a poor solvent Was prepared. Next, 7 parts by mass of a cationic dimethylamine / epochrohydrin-based polymer (polymer represented by the above structural formula 2, weight average molecular weight 2600) as an ionic polymer, magenta pigment dispersion (Sanyo) as a colorant Emacol manufactured by Dye Co., Ltd. (equivalent to 20 parts by mass of pigment solid content) and 5 parts by mass of water as a good solvent were mixed to prepare Solution B (dispersed phase). Emulsification was carried out by mixing 80 parts by mass of solution A and 20 parts by mass of solution B to prepare an emulsion. The emulsification was performed for 10 minutes with an ultrasonic crusher (UH-600S manufactured by SMT).

  Next, the obtained emulsion is put into an eggplant flask and heated (65 ° C.) / Depressurized (10 mPa) with an evaporator while stirring to remove moisture (good solvent), and magenta pigment-containing electrophoretic particles (magenta A particle dispersion in which the particles were dispersed in silicone oil was obtained.

  The produced magenta pigment-containing migrating particles were measured with an Fpar1000 (dynamic light scattering type particle distribution measuring device) manufactured by Otsuka Electronics Co., Ltd., and the average particle size of the particles was 246 nm. Further, when the charge polarity applied to the particles of the obtained particle dispersion was examined in the same manner as in Example 1, the particles adhered to any electrode substrate (the positive electrode adhered slightly more). The obtained particles were found to be positively and negatively charged, although the number of negatively charged particles was slightly larger.

(Preparation of cyan particles (dispersion liquid))
A cyan particle dispersion similar to that in Example 2 was prepared and prepared.

(Preparation of mixed particle dispersion)
The above-obtained magenta particle dispersion (solid content 0.1 part by mass) 0.1 part by mass and cyan particle dispersion (solid content 0.1 part by mass) 0.1 part by mass are mixed to disperse the mixed particles. A liquid was prepared. In the same manner as in the above magenta particle dispersion, the charging polarity of magenta particles and cyan particles in the obtained mixed dispersion was examined. As a result, it was found that all the cyan particles adhered only to the positive electrode substrate and were all negatively charged, while all the magenta particles adhered only to the negative electrode substrate and were all positively charged. As a result, it was found that color mixing was suppressed and cyan / magenta display was performed. In addition, in the same manner as in Example 1, the above evaluation was performed in detail. The results are shown in Table 1.

[Comparative Example 1]
(Preparation of magenta particles (dispersion liquid))
A magenta particle dispersion similar to that in Example 1 was prepared and prepared.

(Cyan particles (preparation of the dispersion))
Solution A (continuous phase) by dissolving 3 parts by mass of silicone-modified acrylic polymer (KP545 manufactured by Shin-Etsu Silicone) as an emulsifier in 97 parts by mass of dimethyl silicone oil (KF-96-2CS manufactured by Shin-Etsu Silicone) as a poor solvent Was prepared. Next, 7 parts by mass of a cationic polyvinyl alcohol polymer (polymer represented by the following structural formula α, weight average molecular weight 7500) as an ionic polymer, and a cyan pigment dispersion as a colorant (Emacol manufactured by Sanyo Dye Co., Ltd .: Pigment solids) 5 parts by weight (equivalent to 20 parts by weight) and 85 parts by weight of water as a good solvent were mixed to prepare a solution B (dispersed phase). Emulsification was carried out by mixing 80 parts by mass of solution A and 20 parts by mass of solution B to prepare an emulsion. The emulsification was performed for 10 minutes with an ultrasonic crusher (UH-600S manufactured by SMT).

  Next, the obtained emulsion is put into an eggplant flask and heated (65 ° C.) / Reduced pressure (10 mPa) with an evaporator while stirring to remove moisture (good solvent), and cyan pigment-containing electrophoretic particles (cyan A particle dispersion in which the particles were dispersed in silicone oil was obtained.

  The produced cyan pigment-containing migrating particles were measured by Fpar1000 (dynamic light scattering type particle distribution measuring device) manufactured by Otsuka Electronics Co., Ltd., and the average particle diameter of the particles was 141 nm. Further, when the charge polarity applied to the particles of the obtained particle dispersion was examined in the same manner as in Example 1, the particles adhered to any electrode substrate (the negative electrode adhered slightly more). The obtained particles were found to be positively and negatively charged although the number of positively charged particles was slightly larger.

(Preparation of mixed particle dispersion)
The magenta particle dispersion (solid content 0.1 parts by mass) 0.1 part by mass and the cyan particle dispersion (solids 0.1 part by mass) 0.1 part by mass are mixed to obtain a mixed particle dispersion. Produced. In the same manner as in Example 1 above, the charging polarity of the magenta particles and cyan particles of the obtained mixed dispersion was examined. As a result, it was found that cyan particles adhered only to the negative electrode and were positively charged, whereas magenta particles adhered to the bipolar electrode substrate and were charged both positively and negatively. As a result, it was found that color mixing occurs in cyan display. In addition, in the same manner as in Example 1, the above evaluation was performed in detail. The results are shown in Table 1.

[Comparative Example 2]
(Preparation of magenta particles (dispersion liquid))
Solution A (continuous phase) by dissolving 3 parts by mass of silicone-modified acrylic polymer (KP545 manufactured by Shin-Etsu Silicone) as an emulsifier in 97 parts by mass of dimethyl silicone oil (KF-96-2CS manufactured by Shin-Etsu Silicone) as a poor solvent Was prepared. Next, 7 parts by mass of cationic acrylamide / dimethylaminoethyl acrylate methyl chloride quaternary salt (polymer represented by the following structural formula β, a = 50, b = 50) as an ionic polymer, magenta pigment as a colorant A dispersion B (dispersed phase) was prepared by mixing 5 parts by mass of a dispersion (Emacol manufactured by Sanyo Dye Co., Ltd .: equivalent to 20 parts by mass of pigment solids) and 85 parts by mass of water as a good solvent. Emulsification was carried out by mixing 80 parts by mass of solution A and 20 parts by mass of solution B to prepare an emulsion. The emulsification was performed for 10 minutes with an ultrasonic crusher (UH-600S manufactured by SMT).

  Next, the obtained emulsion is put into an eggplant flask and heated (65 ° C.) / Depressurized (10 mPa) with an evaporator while stirring to remove moisture (good solvent), and magenta pigment-containing electrophoretic particles (magenta A particle dispersion in which the particles were dispersed in silicone oil was obtained.

  The produced magenta pigment-containing migrating particles were measured with an Fpar 1000 (dynamic light scattering particle distribution measuring device) manufactured by Otsuka Electronics Co., Ltd., and the average particle size of the particles was 483 nm. Further, when the charge polarity applied to the particles of the obtained particle dispersion was examined in the same manner as in Example 1, the same amount of particles adhered to any electrode substrate (the negative electrode adhered slightly more). The particles obtained were found to be positively and negatively charged, although the number of negatively charged particles was slightly larger.

(Cyan particles (preparation of the dispersion))
A cyan particle dispersion similar to that in Example 2 was prepared and prepared.

(Preparation of mixed particle dispersion)
The magenta particle dispersion (solid content 0.1 parts by mass) 0.1 part by mass and the cyan particle dispersion (solids 0.1 part by mass) 0.1 part by mass are mixed to obtain a mixed particle dispersion. Produced. In the same manner as in Example 1 above, the charging polarity of the magenta particles and cyan particles of the obtained mixed dispersion was examined. As a result, it was found that the cyan particles and the magenta particles are attached to the bipolar electrode substrate and are charged to both positive and negative. As a result, it was found that color mixing occurs in the cyan / magenta display. In addition, in the same manner as in Example 1, the above evaluation was performed in detail. The results are shown in Table 1.

  From the above results, it can be seen that the mixed particle dispersion of this example realizes a display in which color mixing is suppressed as compared with the comparative example.

1 is a schematic configuration diagram of a display device according to a first embodiment. It is explanatory drawing which shows typically the movement aspect of a particle group when a voltage is applied between the board | substrates of the display medium of the display apparatus which concerns on 1st Embodiment.

DESCRIPTION OF SYMBOLS 10 Display apparatus 12 Display medium 16 Voltage application part 18 Control part 20 Display substrate 22 Back substrate 24 Gap member 34 Particle group 34A Particle group 34B Particle group 36 Reflective particle group 38 Support substrate 40 Surface electrode 42 Surface layer 44 Support substrate 46 Back electrode 48 Surface layer 50 Dispersion medium

Claims (6)

The first ionic polymer having a coloring agent and a first ionic polymer having a counter ion and moving in response to an electric field has a different charging polarity from the coloring agent and the first ionic polymer. And a second display particle comprising a second ionic polymer having the same structure as a counter ion of the first ionic polymer in a polymer chain structure, and moving according to an electric field;
A dispersion medium for dispersing the first colored particles and the second colored particles;
A particle dispersion for display comprising:   The display particle dispersion according to claim 1, wherein the counter ion of the first ionic polymer is an amine compound ion.   The display particle dispersion according to claim 1, wherein the counter ion of the first ionic polymer is a quaternary ammonium ion. A pair of substrates, at least one of which is translucent,
The display dispersion liquid according to any one of claims 1 to 3, wherein the display dispersion liquid is sealed between the pair of substrates.
A display medium comprising: A pair of electrodes, at least one of which is translucent,
A region having a display dispersion liquid according to any one of claims 1 to 3, provided between the pair of electrodes;
A display medium comprising: A display medium according to claim 4 or 5, and
Voltage applying means for applying a voltage between the pair of substrates of the display medium;
A display device comprising: