JP2011069903A - Particle for display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide particles for display with stable charging characteristics compared with particles for display without containing a plate-like material that is derived from ion polymer and layered clay mineral. <P>SOLUTION: The particles 10 for display includes the ion polymer 12, plate-like material 14 that is derived from the layered clay mineral, and a color material 16. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to display particles.

  Cited Document 1 proposes a charged particle comprising an aprotic solvent as a dispersion medium, and a pigment, a resin compound, and a charge control agent having a solubility in an aprotic solvent of 5% by mass or less. ing. In Cited Document 1, as the charge adjusting agent, an electron-donating dye such as a nigrosine dye or an electron-accepting dye such as a metal complex salt of a monoazo dye is cited.

Cited Document 2 includes electrophoretic particles containing a material having a low refractive index (refractive index of 2.0 or less) such as zinc oxide.
Cited Document 3 proposes electrophoretic particles containing an oil-soluble dye, colored particles, an inorganic pigment, and an organic pigment in an organic solvent.

Cited Document 4 proposes an electrophoretic particle in which the surface of a colored particle is modified with a functional group capable of generating an intermolecular attractive force on the particle surface.
Cited Document 5 proposes an electrophoretic particle containing a resin, a coloring material, and a charge imparting agent.

JP2004-279732 JP 2004-522180 A JP 2001-166711 A JP 2006-220969 A JP 2001-272702 A

  An object of the present invention is to provide a plate-like member derived from a layered clay mineral and display particles having a stable charging property as compared with display particles not containing an ionic polymer held on the surface of the plate-like member. Is to provide.

The above problem is solved by the following means. That is,
The invention according to claim 1 is a display particle having a plate-like member derived from a layered clay mineral, an ionic polymer held on the surface of the plate-like member, and a coloring material.

  The invention according to claim 2 is the display particle according to claim 1, wherein the ionic polymer is a cationic polymer.

  The invention according to claim 3 is the display particle according to claim 1 or 2, wherein the layered clay mineral has an organic cation between layers.

  The invention according to claim 4 is the display particle according to any one of claims 1 to 3, wherein the layered clay mineral is a smectite group.

  According to the first to third aspects of the present invention, the charging characteristics of the plate-like member derived from the layered clay mineral and the display particles not containing the ionic polymer held on the surface of the plate-like member are higher. The stabilized display particles are provided.

  According to the invention which concerns on Claim 4, compared with the case where a smectite group layered clay mineral is not used, there exists an effect that the display particle suitable for the display particle for electrophoresis is provided.

  According to the invention according to claim 5, the charging property is more stable than the dispersion of the plate-like member derived from the layered clay mineral and the display particles not containing the ionic polymer held on the surface of the plate-like member. There is an effect that a dispersed dispersion of display particles is provided.

It is a schematic diagram which shows an example of the particle | grains for a display which concerns on this Embodiment. (A) (B) It is a schematic diagram which shows an example of a layered clay mineral. It is a schematic diagram which shows an example of a display medium and a display apparatus. (A) (B) It is a schematic diagram which shows an example of the drive state of a display medium and a display apparatus.

  Hereinafter, embodiments of the present invention will be described.

(Display particles and display particle dispersion)
The display particle dispersion according to the present embodiment includes display particles that move according to an electric field, and a dispersion medium. As shown in FIG. 1, the display particles 10 of the present embodiment include a plate-like member 14 derived from a layered clay mineral, an ionic polymer 12 held on the surface of the plate-like member 14, a color material 16, and the like. , Including. The ionic polymer 12 is bonded to the surface of the plate-like member 14.

  Here, in the display particles 10, the charging characteristics are adjusted by selecting the type and content of the ionic polymer 12. The charging characteristics indicate polarity and charge amount. In the display particles 10 including the ionic polymer 12, it is desirable that the charging characteristics of the display particles 10 do not change. However, in the conventional display particles that do not include the lamellar clay mineral-derived plate-like member and the ionic polymer bonded to the plate-like member, the change in polarity and the amount of charge with time result Changes in charging characteristics such as changes may occur. This is considered due to the ionic polymer eluting out of the display particles.

On the other hand, the display particle 10 according to the present embodiment includes a plate-like member 14 derived from a layered clay mineral, an ionic polymer 12 held on the surface of the plate-like member 14, and a color material 16. It is configured. By using the display particle 10 having such a configuration, the charging characteristics are stabilized as compared with the plate-like member derived from the layered clay mineral and the conventional display particle not containing the ionic polymer held on the plate-like member. It is thought.
The charging mechanism stabilization mechanism is not clear, but the following mechanism is presumed.
As shown in FIG. 2A, the layered clay mineral 14A is a substance having a layered structure. In the layered clay mineral 14A of this layered structure, both end surfaces in the thickness direction of each layer are charged to the negative electrode, and the end surfaces in the direction crossing the thickness direction are charged to the positive electrode, and calcium ions, sodium ions, etc. A layered structure is formed by sandwiching an inorganic cation. And in the plate-like member 14 which is each layer which the layered structure of the layered clay mineral 14A of this layered structure collapsed and separated, both end surfaces in the thickness direction are negatively charged, and end surfaces in the direction intersecting the thickness direction are It is charged to a positive charge (see FIG. 2B). For this reason, when the ionic polymer contained in the display particles 10 is a cationic polymer, the cationic polymer is held in a region showing the negative electrode of the plate-like member 14, and the ionic polymer Is an anionic polymer, it is considered that the anionic polymer is held in the region of the plate-like member 14 indicating the positive electrode. Therefore, when the plate-like member 14 derived from the layered clay mineral 14A is contained in the display particle 10, the ionic polymer 12 contained in the display particle 10 is held on the surface of the plate-like member 14. Thus, it is considered that the elution into the solution outside the display particles 10 is suppressed, and the charging characteristics are stabilized.

Hereinafter, the components and production method of the display particles 10 of the present embodiment will be described in detail.
Examples of the ionic polymer 12 contained in the display particles include a polymer having a cationic group or an anionic group.
Examples of the cationic group include an amino group and a quaternary ammonium group. On the other hand, examples of the anionic group include a phenol group, a carboxyl group, a carboxylate group, a sulfonate group, a sulfonate group, a phosphate group, a phosphate group, and a tetraphenylboron group.

  Examples of the ionic polymer 12 include a homopolymer of a monomer having a cationic group (hereinafter sometimes referred to as a cationic monomer), a cationic monomer, a cationic group, and an anionic group. Copolymer with a monomer having no anion (hereinafter referred to as a nonionic monomer), single copolymer of a monomer having an anionic group (hereinafter sometimes referred to as an anionic monomer) And a copolymer of an anionic monomer and a nonionic monomer.

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, vinylpyrrolidine aminoether 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. India , Carbazoles such as N-vinylcarbazole, 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 desirable cationic monomer from versatility, (meth) acrylates having an aliphatic amino group such as N, N-dimethylaminoethyl (meth) acrylate and N, N-diethylaminoethyl (meth) acrylate are included. In particular, it is preferable to use a quaternary ammonium salt structure before or after polymerization.

  In the present embodiment, the description such as “(meth) acrylate” is an expression including both “acrylate” and “methacrylate”. The same applies hereinafter.

On the other hand, examples of the anionic monomer include the following.
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. Is mentioned. Moreover, the sulfuric monoester of 2-hydroxyethyl (meth) acrylic acid and its salt are mentioned.
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 Examples include 2-acryloyloxyethyl phosphate, dibutyl-2-methacryloyloxyethyl phosphate, dibutyl-2-acryloyloxyethyl phosphate, dioctyl-2- (meth) acryloyloxyethyl phosphate, and the like.

  Desirable anionic monomers include those having (meth) acrylic acid and sulfonic acid, and those having a structure of an ammonium salt before or after polymerization. Ammonium salts are produced by reacting with tertiary amines or quaternary ammonium hydroxides.

  Nonionic monomers include nonionic monomers (nonionic monomers) such as (meth) acrylonitrile, (meth) acrylic acid alkyl esters, (meth) acrylamide, ethylene, propylene, and 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, vinyl pyrrolidone, hydroxyethyl (meth) Examples thereof include acrylate and hydroxybutyl (meth) acrylate.

  The copolymerization ratio between the anionic monomer or the cationic monomer and the monomer having no cationic property or anionic property is adjusted according to the charge amount of the target display particles. As an example, the copolymerization ratio of an anionic monomer or a cationic monomer and a monomer that does not have a cationic property and an anionic property is in a range of 1: 100 or more and 100: 0 or less in molar ratio. Selected.

  Examples of the mass average molecular weight of the ionic polymer 12 include 1,000 to 1,000,000 and 10,000 to 200,000.

  The layered clay mineral 14A is a silicate mineral having a layered structure. The layered structure is formed by neutralizing an insufficient charge by sandwiching an inorganic cation such as sodium ion, calcium ion, lithium ion, magnesium ion between each layer. Forming. Each plate member 14 peeled from the layered clay mineral 14A and holding the ionic polymer 12 on the surface corresponds to a plate member derived from the layered clay mineral in the display particles of the present invention. That is, the display particles 10 of the present embodiment contain a plate-like member 14 that holds the ionic polymer 12 on its surface.

  In the present embodiment, the plate-like member 14 derived from the layered clay mineral 14A only needs to be in a state in which the ionic polymer 12 is held on the surface in the display particles 10. For this reason, the plate-like member 14 may exist in a state of being dispersed in the display particles 10 (that is, in the ionic polymer) or in a state of being overlapped in the display particles 10. It may be. Examples of the state of being overlaid include a state in which an ionic polymer is inserted between layers constituting the layered clay mineral 14A (so-called intercalated state).

  Specifically, as this layered clay mineral 14A, kaolinite group such as kaolinite and halosite: smectite group such as beidelite, nontronite, bolcon score, saponite, montmorillonite, hectorite and stevensite: vermiculite group : Is mentioned.

  As the smectite group, natural smectites such as montmorillonite, saponite and hectorite may be used, and synthetic smectites such as saponite, hectorite and stevensite may be used.

  The size of the plate member 14 (the size of the plate member 14 alone and not including the ionic polymer held on the surface) is the size contained in the display particles 10 to be formed. For example, the volume average particle diameter is 2 μm or less, or 1 μm or less. The layered clay mineral in which each layer constituting the laminated structure is within this range includes the smectite group. For this reason, it is desirable to use the smectite group as the layered clay mineral used for the display particles 10.

  In addition, the volume average particle diameter of the plate-like member 14 derived from the layered clay mineral is measured by the following method. Using a laser diffraction particle size distribution analyzer (LA-700: manufactured by HORIBA, Ltd.), adjust the sample in the dispersion state to about 2 g in solid content, and add ion-exchanged water to this. And adjust to about 40 ml. This is put into the cell until an appropriate concentration is reached, and after waiting for 2 minutes, the concentration in the cell is stabilized, and then the measurement is performed. The obtained volume average particle diameter for each channel is accumulated from the smaller volume average particle diameter, and the place where the accumulation reaches 50% is defined as the volume average particle diameter. In addition, the volume average particle diameter described in the present specification is a value measured by the above method.

  The content of the plate-like member 14 in the display particles 10 is 0.01% by mass to 20% by mass, or 0.05% by mass to 5% by mass with respect to the ionic polymer contained in the display particles 10. The following are mentioned.

  Next, the color material 16 will be described. Examples of the color material 16 include organic or inorganic pigments, oil-soluble dyes, and the like, for example, magnetic powder such as magnetite and ferrite, carbon black, titanium oxide, magnesium oxide, zinc oxide, phthalocyanine copper-based cyan color material, Known color materials 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, the coloring material 16 includes 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. 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 coloring material 16 in the display particles 10 is 10% by mass to 99% by mass, or 30% by mass to 99% by mass with respect to the ionic polymer contained in the display particles 10.

  As the magnetic material, an inorganic magnetic material or an organic magnetic material colored as necessary is used. Further, a transparent magnetic material, in particular, a transparent organic magnetic material does not hinder the coloring of the coloring material, and the specific gravity is smaller than that of the inorganic magnetic material. Examples of the colored magnetic material include colored magnetic powder described in JP-A-2003-131420.

The dispersion liquid of the display particles is adjusted by dispersing the display particles 10 in a dispersion medium.
An example of the dispersion medium is an insulating liquid. Here, “insulating” indicates that the volume resistivity is 10 ¹¹ Ωcm or more. The same applies hereinafter.

  Specific examples of the insulating liquid include hexane, cyclohexane, toluene, xylene, decane, hexadecane, kerosene, paraffin, isoparaffin, silicone oil, dichloroethylene, trichloroethylene, perchloroethylene, high-purity petroleum, ethylene glycol, and alcohols. , Ethers, esters, dimethylformamide, dimethylacetamide, dimethylsulfoxide, N-methylpyrrolidone, 2-pyrrolidone, N-methylformamide, acetonitrile, tetrahydrofuran, propylene carbonate, ethylene carbonate, benzine, diisopropylnaphthalene, olive oil, isopropanol, trichloro Examples include trifluoroethane, tetrachloroethane, dibromotetrafluoroethane, and mixtures thereof. It is.

Further, from the viewpoint of ease of movement of the display particles 10 in the dispersion medium by an electric field, water (so-called pure water) is also used as the dispersion medium by removing impurities so as to have the following volume resistance value. The Examples of the volume resistance value include 10 ³ Ωcm or more and 10 ⁷ Ωcm or more and 10 ¹⁹ Ωcm or less, or 10 ¹⁰ Ωcm or more and 10 ¹⁹ Ωcm or less.

Next, a method for manufacturing the display particles 10 will be described.
The display particles 10 include, for example, a solution (continuous phase) containing a first solvent, an ionic polymer 12, a layered clay mineral 14A or an organically processed layered clay mineral 14A, a color material 16, and the first material. A step of mixing and emulsifying a mixed solution of a solution (dispersed phase) that is incompatible with one solvent and has a boiling point lower than that of the first solvent and that dissolves the ionic polymer; And removing the second solvent from the emulsified liquid to produce display particles 10 containing the ionic polymer 12, the plate-like member 14, and the colorant 16. . When the display particles 10 are produced by a so-called liquid drying method, it is considered that the display particles 10 having particularly stable dispersibility and charging characteristics can be obtained.

  This technique 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 dispersion of display particles as the first solvent. Thereby, in the method for producing display particles according to the present embodiment, a dispersion liquid of display particles using the first solvent as a dispersion medium can be easily produced without going through a cleaning / drying step by passing through the above-described steps. Is done. Of course, in order to improve electrical characteristics, the particles may be washed (removal of ionic impurities) or the dispersion medium may be replaced. Hereinafter, it demonstrates according to a process.

  In addition, the manufacturing method of the display particles 10 is not limited to the above-described manufacturing method. For example, the display particles 10 are formed by other known methods (coacervation method, dispersion polymerization method, suspension polymerization method, etc.). You may employ | adopt the method to do.

  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, first, a solution (continuous phase) containing the first solvent is prepared. This first solvent is used as a poor solvent that can form a continuous phase in a mixed solution, and examples thereof include petroleum-derived high-boiling solvents such as paraffinic hydrocarbon solvents, silicone oils, and fluorine-based liquids. I can't. Of these, silicone oil is preferable.

  Further, the ionic polymer 12, the layered clay mineral 14A, the coloring material 16, and a second solvent that is incompatible with the first solvent and has a lower boiling point than the first solvent and dissolves the ionic polymer. Prepare the solution (dispersed phase). In the dispersed phase solution, the ionic polymer 12, the layered clay mineral 14A, the coloring material 16, and the second solvent may be mixed at one time or sequentially.

  This second solvent is used as a good solvent capable of forming a dispersed phase in the mixed solution. In addition, one that is incompatible with the first solvent, has a lower boiling point than the first solvent, and dissolves the ionic polymer 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.

  At the time of preparing the solution forming the dispersed phase, the ionic polymer 12, the layered clay mineral 14A, the coloring material 16, and the second solvent are mixed. At this time, the layered structure of the layered clay mineral 14 </ b> A disappears to form a plate-like member 14.

  Specifically, the layered clay mineral 14A has an action of adsorbing and swelling the solvent when contacted with a solvent such as water, alcohol or ether. For this reason, if the layered clay mineral having the swelling action is used, and the layered clay mineral 14A is swollen by using a solvent that causes a swelling action such as water, alcohol, ether or the like as the second solvent, and further applying a shearing force, The layered structure of the layered clay mineral 14A is lost. Then, the ionic polymer 12 contained in the same solution is held on the surface of each layer in a state where this layered structure is lost, so that the plate-like member 14 holding the ionic polymer 12 on the surface is obtained. The

Further, in the layered clay mineral 14A, as described above, a layered structure is formed by sandwiching an inorganic cation between layers, but the inorganic cation sandwiched between the layers, the negative charge on the surface of each layer, Since the bonding force of is weak, contact with a solution containing other ions causes an exchange reaction between the inorganic cation between the layers and the cation in the solution, resulting in cation exchange.
If a cationic polymer is used as the ionic polymer 12 by utilizing this cation exchange property, the inorganic cation and the cationic polymer between the layers of the layered clay mineral 14A in the solution forming the dispersed phase In between, cation exchange occurs. As a result, the ionic polymer 12 is inserted (intercalated) between the layers of the layered clay mineral 14A, the layered structure of the layered clay mineral 14A disappears, and the plate holding the ionic polymer 12 on the surface. The member 14 is formed. This method may be used in combination with the swelling treatment of the layered clay mineral 14A.

Further, by utilizing the cation exchange property of the layered clay mineral 14A, an organic treatment is performed by inserting an organic agent between the layers of the layered clay mineral 14A. A method of using the plate-like member 14 held on the surface is also mentioned. This organic treatment indicates that the layered clay mineral 14A is organically modified. Specifically, the inorganic cation between the layers of the layered clay mineral 14A is replaced with an organic cation.
By replacing the inorganic cation between the layers of the layered clay mineral 14A with an organic cation, the compatibility with the ionic polymer 12 in the solution forming the dispersed phase is increased, and the layered state of the layered clay mineral 14A in the solution is increased. It is thought that the disappearance of the structure proceeds efficiently. Then, the ionic polymer 12 contained in the same solution is held on the surface of each layer in a state where this layered structure is lost, so that the plate-like member 14 holding the ionic polymer 12 on the surface is obtained. The

  For this reason, as the layered clay mineral 14A, the layered clay mineral 14A that has been subjected to the organic treatment, that is, the layered clay mineral 14A having an organic cation between the layers, easily causes the layered structure of the layered clay mineral 14A to disappear. In particular, it is considered that the deterioration of charging characteristics when the display particles 10 are obtained is further suppressed.

  This organic treatment may be performed in combination with at least one of a swelling treatment of the layered clay mineral 14A and a treatment of intercalating the ionic polymer. By performing in combination, it is considered that further reduction in charging characteristics can be suppressed.

  Examples of the organic agent include compounds containing onium ions. As the onium ion, primary to quaternary ammonium ions are particularly preferable. Examples of primary to quaternary ammonium ions include hexyl ammonium ion, octyl ammonium ion, 2-ethylhexyl ammonium ion, dodecyl ammonium ion, lauryl ammonium ion, octadecyl ammonium ion, stearyl ammonium ion, dioctyl dimethyl ammonium ion, and trioctyl ammonium ion. , Distearyldimethylammonium ion, ammonium laurate ion, alkylbis (2-hydroxyethyl) methylammonium ion, polyoxypropylenemethyldiethylammonium ion, and the like. Among them, a quaternary ammonium salt having a hydrophobic group is preferable.

  In addition, when a cationic polymer is used as the ionic polymer 12, the cationic polymer may function as the organic agent.

It is known in the art that metal cations or anions associated with layered clay mineral 14A can be exchanged for organic ions by an ion exchange process. As a typical process, the layered clay mineral 14A is first swollen or expanded in one or more suitable solvents and then ion exchanged, then by methods such as filtration, centrifugation, solvent evaporation or sublimation. Aggregated and collected from the swelling solvent.
In addition, the following method is mentioned as a method of confirming that the layered clay mineral 14A is organically treated.
For example, the inorganic cation (layered clay mineral 14A) released into the second solvent in a state where only the layered clay mineral 14A, the organic agent, and the second solvent are mixed at the time of preparing the solution of the dispersed phase. What is necessary is just to confirm by measuring the quantity of the inorganic cation currently hold | maintained between the layers.
Moreover, as another method, the method of confirming the absorption peak derived from the coupling | bonding of the organic agent in the surface of the layered clay mineral 14A by FT-IR measurement, and observing the absorption peak derived from this coupling | bonding is mentioned.

  As described above, when adjusting the solution forming the dispersed phase, the layered structure of the layered clay mineral 14A disappears, and the plate-like member 14 holding the ionic polymer 12 on the surface is adjusted.

  In the emulsification step, for example, the solution containing the first solvent (continuous phase), the ionic polymer 12, the layered clay mineral 14A, the coloring material 16, and the first solvent are incompatible with the first solvent. Two solutions of a second solvent having a boiling point lower than that of one solvent and containing a second solvent that dissolves the ionic polymer (dispersed phase) are mixed, stirred, and emulsified. Moreover, you may mix | blend other compounding materials (a charge control agent, a pigment dispersant, etc.) other than the said material in the liquid mixture made to emulsify.

  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. In the second solvent, the ionic polymer 12, the layered clay mineral 14A, the layered clay mineral 14A subjected to the organic treatment, and the color material 16 are dispersed.

  In the emulsification step, each material may be sequentially mixed in the mixed solution. For example, first, the ionic polymer 12, the color material 16, and the layered clay mineral 14A (or the plate member 14) If necessary, a mixed solution in which the organic agent and the second solvent are mixed is prepared. And it is good to emulsify so that this liquid mixture may be disperse | distributed and mixed in a 1st solvent, and a liquid mixture 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.

-Second solvent removal step-
Next, in the second solvent removal step, the second solvent (low boiling point solvent) is removed from the mixed liquid emulsified in the emulsification step. By removing the second solvent, the ionic polymer 12 is precipitated in the dispersed phase formed by the second solvent while enclosing other materials such as the plate member 14 and the coloring material 16. The particles 10 for display are obtained.

Here, examples of the method of 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 heating a liquid mixture, as heating temperature, 30 degreeC or more and 200 degrees C or less, 50 degreeC or more and 180 degrees C or less are mentioned, for example. The mixed solution may be decompressed to remove the second solvent, or may be dried under reduced pressure combined with heating. As a pressure at the time of pressure reduction, 100 mPa or more and 50 KPa or less, 100 Pa or more and 20 KPa or less are mentioned.

  The production method of the display particles is not limited to the above production method, and a known method such as a pulverization method, a coacervation method, a dispersion polymerization method, or a suspension polymerization method may be used. In each of these methods, a dispersion medium used in the dispersion liquid of display particles is used as a solvent (a solvent finally remaining in the manufacturing method), and as a display particle dispersion liquid including display particles and a dispersion medium as it is after production. May be used. Thereby, in the manufacturing method of the display particle, the display particle dispersion liquid using the solvent to be used as the dispersion medium is easily produced through the manufacturing steps without passing through the washing and drying steps. Of course, in order to improve electrical characteristics, cleaning of particles (removal of ionic impurities) and replacement of a dispersion medium are also performed.

  Through the above steps, display particles are obtained, and a dispersion of display particles containing the display particles is obtained. In addition, for the obtained dispersion of display particles, an acid, an alkali, a salt, a dispersant, a dispersion stabilizer, a stabilizer for anti-oxidation or ultraviolet absorption, an antibacterial agent, an antiseptic agent, if necessary. Etc. may be added.

  In addition, an anionic surfactant, a cationic surfactant, an amphoteric surfactant, a nonionic surfactant, a fluorosurfactant, a silicone-based surfactant as a charge control agent for the obtained dispersion of display particles Surfactants, silicone-based cationic compounds, silicone-based anion 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.

  Moreover, you may dilute with the 1st solvent (The 1st solvent containing a dispersing agent as needed), for example with respect to the obtained dispersion liquid of the display particle | grains as needed.

  The concentration of the display particles 10 in the display particle dispersion is variously selected depending on the display characteristics and response characteristics of the display medium to which the display particle dispersion is applied. The range of mass% or more and 30 mass% or less is mentioned.

  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.

  The display device 60 according to the present embodiment applies a dispersion liquid of display particles including the display particles 10 and the dispersion medium described above as a particle dispersion liquid including the dispersion medium 50 and the display particles 10. It is. Specifically, among the display particles 10, the first display particles are applied as the display particles 10 </ b> A, and the second display particles 10 </ b> B exhibit a color different from the display particles 10 </ b> A and have different charging polarities. This is a form in which display particles are applied.

  As shown in FIG. 3, the display device 60 according to the present embodiment includes a display medium 13, a voltage application unit 17 that applies a voltage to the display medium 13, and a control unit 18.

  The display medium 13 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, holds a distance between these substrates, and a distance between the display substrate 20 and the rear substrate 22. Are formed to include a gap member 24 that divides each cell into a plurality of cells, display particles 10 enclosed in each cell, and a reflective particle group 36 having optical reflection characteristics different from those of the display particles 10.

  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 display particles 10 are dispersed in the dispersion medium 50 and move between the display substrate 20 and the back substrate 22 through the gap between the reflective particle groups 36 according to the electric field strength formed in the cell.

  In addition, the gap member 24 is provided so as to correspond to each pixel when an image is displayed on the display medium 13, and the cell is formed so as to correspond to each pixel, whereby the display medium 13 can be displayed for 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 is configured by laminating a back electrode 46 and a surface layer 48 on a support substrate 44.

  The display substrate 20 or both the display substrate 20 and the back substrate 22 are translucent. Here, in this embodiment, translucency indicates that the transmittance of visible light 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 display particles 10.

  The back electrode 46 and the surface electrode 40 may be separated from the display substrate 20 and the back substrate 22 and arranged outside the display medium 13.

  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 13 is a simple matrix drive, the structure of a display device 60 having the display medium 13 to be described later can be simplified. If the active matrix drive using TFTs is used, the display device 13 is simpler than the simple matrix drive. Display speed.

  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 damage to the surface electrode 40 and the back electrode 46 or the display particles 10 are fixed. In order to prevent the occurrence of leakage, it is preferable to form a surface layer 42 and a surface layer 48 as dielectric films 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.

  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 formed 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 13. In this case, for example, transparent such as polystyrene, polyester, or acrylic is used. Resin or the like is used. Note that “transparent” means having a transmittance of 60% or more with respect to visible light.

  The reflective particle group 36 is an uncharged particle group, is composed of reflective particles having optical reflection characteristics different from those of the display particles 10, and functions as a reflective member that displays a color different from that of the display particles 10. Is. 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 display particles 10 is moved through the gap between the reflective particle groups 36 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. As the color of the reflective particle group 36, for example, white or black is selected 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.

  For the reflective particle group 36, for example, a white pigment such as titanium oxide, silicon oxide, or zinc oxide is used. The reflective particle group 36 may be dispersed in the dispersion medium 50 or may be fixed between the substrates.

  The size of the cell in the display medium 13 is closely related to the resolution of the display medium 13, and the smaller the cell, the higher the resolution of the display medium 13 that can display an image. As the size of this cell, for example, the length of the display substrate 13 in the plate surface direction of the display medium 13 is about 10 μm or more and 1 mm or less.

  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 13 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 that are shared with other companies.

  As described above, the display device 60 according to the present embodiment includes the display medium 13, the voltage application unit 17 that applies a voltage to the display medium 13, and the control unit 18 (FIG. 3). And FIG. 4).

  The voltage application unit 17 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 17 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 17.

  The voltage application unit 17 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. And a ROM (Read Only Memory).

  The voltage application unit 17 is a voltage application device for applying a voltage to the surface electrode 40 and the back electrode 46, and applies a voltage according to the control of the control unit 18 between the surface electrode 40 and the back electrode 46.

  Next, the operation of the display device 60 will be described. This operation will be described according to the operation of the control unit 18.

  Here, among the display particles 10 sealed in the display medium 13, the case where the display particles 10B are negatively charged and the display particles 10B are 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 13 displays the colors exhibited by the movement of the display particles 10A and the display particles 10B, and displays white as the background color.

First, an initial operation signal indicating that the voltage is applied so that the front electrode 40 becomes a negative electrode and the back electrode 46 becomes a positive electrode for a specific time is output to the voltage application unit 17. When a voltage of a negative electrode and a voltage value equal to or higher than the threshold value at which the concentration variation ends is applied for T1 time between the substrates, the particles constituting the display particles 10A charged on the negative electrode move to the back substrate 22 side. , And reaches the rear substrate 22 (see FIG. 4A). On the other hand, particles constituting the display particles 10B charged to the positive electrode move toward the display substrate 20 and reach the display substrate 20 (see FIG. 4A).
At this time, the color of the display medium 13 visually recognized from the display substrate 20 side is white as the color of the reflective particle group 36, and the color exhibited by the display particles 10B is visually recognized. The display particles 10 </ b> A are concealed by the reflective particle group 36 and are not easily 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 voltage application. Then, information indicating this specific time may be read when the process is executed.

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 display particles 10A are moved to the display substrate 20 side and reach the display substrate 20 side (see FIG. 4B). On the other hand, the particles constituting the display particles 10B charged on the positive electrode move to the back substrate 22 side and reach the back substrate 22 (see FIG. 4B).
At this time, the color of the display medium 13 visually recognized from the display substrate 20 side is white as the color of the reflective particle group 36, and the color exhibited by the display particles 10A is visually recognized. Note that the display particles 10B are concealed by the reflective particle group 36 and are not easily recognized.

  Thus, in the display device 60 according to the present embodiment, display is performed when the display particles 10 (the display particles 10A and the display particles 10B) reach the display substrate 20 or the back substrate 22.

  Here, as described above, the display particles 10 used in the display device 60 of the present embodiment include a plate-like member derived from a layered clay mineral and an ionic polymer held on the surface of the plate-like member. The display particles 10 have a stable charging characteristic as compared with conventional display particles that do not contain any of the above. For this reason, in the display device 60 using the display particles 10, even after a long period of time has elapsed since the display medium 13 and the display device 60 were manufactured, compared to the display device using the conventional display particles, It is considered that display deterioration is suppressed.

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

Example 1
5 parts by mass of a silicone-modified acrylic polymer (KP545 manufactured by Shin-Etsu Chemical Co., Ltd.) as an emulsifier is dissolved in 95 parts by mass of dimethyl silicone oil (KF-96-2CS manufactured by Shin-Etsu Chemical Co., Ltd.) as a poor solvent, and a solution A (continuous Phase). The continuous phase was adjusted under a nitrogen environment.

  Next, 20 parts by mass of distilled water, 0.3 part by mass of synthetic smectite LAPONITE RDS (manufactured by Rockwood Additives) as a layered clay mineral, and cationized polyvinyl alcohol (K-210, Nippon Synthetic Chemical Co., Ltd.) as a cationic polymer , 7 parts by mass), and a cation exchange reaction was performed to exchange cations between the release layers of the layered clay mineral with cationized polyvinyl alcohol.

After the cation exchange reaction was performed, an absorption peak derived from the OH bond of the cationized polyvinyl alcohol was confirmed by FT-IR measurement. As a result, the O—H of the cationized polyvinyl alcohol was found in the vicinity of 3500 cm ^−1. Absorption peaks due to binding were observed. Thereby, it was confirmed that the cationized polyvinyl alcohol which is a cationic polymer was held on the surface of the plate-like member.

The measurement conditions for this FT-IR were as follows.
Fourier transform infrared spectroscopy:
Using a Fourier transform infrared spectrophotometer (FT-IR, Impact 400, manufactured by Nicolet (Ltd.)), the measurement frequency ^{4000cm -1 ~400cm} -1, the number of integrations 16, at a resolution ^{4 cm -1,} the organized Mt FT- IR spectrum was measured. The organic sample was measured by the KBr tablet method.

  Furthermore, 8 parts by mass of a blue pigment (Dainippon Ink Chemical Co., Ltd .: microencapsulated pigment MC Blue 182-E) having a volume average primary particle size of 0.1 μm was added as a colorant, and the mixture was stirred and mixed to obtain a solution B (dispersed phase). ) Was adjusted. The dispersion phase was also adjusted in a nitrogen environment.

  Next, 80 parts by mass of the solution A (continuous phase) and 20 parts by mass of the solution B (dispersed phase) were mixed and emulsified to prepare an emulsion. The emulsification was performed for 10 minutes with an ultrasonic crusher (UH-600S manufactured by SMT).

  Next, moisture was removed by drying under reduced pressure with an evaporator at 65 ° C. while continuing stirring, and display particles 1 were produced. When the produced display particle 1 was observed with a scanning electron microscope (FE-SEM S-5500, manufactured by Hitachi), it was observed to be spherical. Moreover, when measured by HORIBA LB-550 (dynamic light scattering type particle size distribution measuring device), the average particle size was 280 nm.

(Example 2)
5 parts by mass of a silicone-modified acrylic polymer (KP545 manufactured by Shin-Etsu Chemical Co., Ltd.) as an emulsifier is dissolved in 95 parts by mass of dimethyl silicone oil (KF-96-2CS manufactured by Shin-Etsu Chemical Co., Ltd.) as a poor solvent, and a solution A (continuous Phase). The continuous phase was adjusted under a nitrogen environment.
Next, 20 parts by mass of distilled water, 0.3 part by mass of organic PLAYTON AF (manufactured by Rockwood Additives), which is a quaternary ammonium compound of synthetic smectite as a layered clay mineral, and cationized polyvinyl as a cationic polymer Alcohol (NIPPON GOHSEI K-210, 7 parts by mass) was added and mixed. Furthermore, 8 parts by mass of a blue pigment (Dainippon Ink Chemical Co., Ltd .: microencapsulated pigment MC Blue 182-E) having a volume average primary particle size of 0.1 μm was added as a colorant, and the mixture was stirred and mixed to obtain solution C (dispersed phase) ) Was adjusted. The dispersion phase was also adjusted in a nitrogen environment.
Next, 80 parts by mass of the solution A (continuous phase) and 20 parts by mass of the solution B (dispersed phase) were mixed and emulsified to prepare an emulsion. The emulsification was performed for 10 minutes with an ultrasonic crusher (UH-600S manufactured by SMT).
Next, moisture was removed by drying under reduced pressure with an evaporator at 65 ° C. while further stirring, and display particles 2 were produced. When the produced display particles 2 were observed with a scanning electron microscope (FE-SEM S-5500, manufactured by Hitachi), the particles were observed to be spherical. Moreover, when measured by HORIBA LB-550 (dynamic light scattering type particle size distribution measuring device), the average particle size was 720 nm.
Display particles 2 were produced as described above.

(Example 3)
5 parts by mass of a silicone-modified acrylic polymer (KP545 manufactured by Shin-Etsu Chemical Co., Ltd.) as an emulsifier is dissolved in 95 parts by mass of dimethyl silicone oil (KF-96-2CS manufactured by Shin-Etsu Chemical Co., Ltd.) as a poor solvent, and a solution A (continuous Phase). The continuous phase was adjusted under a nitrogen environment.

  Next, 20 parts by mass of distilled water, 0.3 part by mass of synthetic smectite LAPONITE RDS (manufactured by Rockwood Additives) as a layered clay mineral, and polyacrylic acid neutralized with triethylamine as an anionic polymer (Wako Pure Chemical Industries, Ltd.) Manufactured, 7 parts by mass).

  Furthermore, 8 parts by mass of a blue pigment (Dainippon Ink Chemical Co., Ltd .: microencapsulated pigment MC Blue 182-E) having a volume average primary particle size of 0.1 μm was added as a colorant, and the mixture was stirred and mixed to obtain a solution B (dispersed phase). ) Was adjusted. The dispersion phase was also adjusted in a nitrogen environment.

  Next, 80 parts by mass of the solution A (continuous phase) and 20 parts by mass of the solution B (dispersed phase) were mixed and emulsified to prepare an emulsion. The emulsification was performed for 10 minutes with an ultrasonic crusher (UH-600S manufactured by SMT).

  Next, moisture was removed by drying under reduced pressure with an evaporator at 65 ° C. while further stirring, and display particles 3 were produced. When the produced display particles 3 were observed with a scanning electron microscope (FE-SEM S-5500 manufactured by Hitachi), it was observed that the particles were spherical. Moreover, when measured by HORIBA LB-550 (dynamic light scattering type particle size distribution measuring device), the average particle size was 476 nm.

Example 4
5 parts by mass of a silicone-modified acrylic polymer (KP545 manufactured by Shin-Etsu Chemical Co., Ltd.) as an emulsifier is dissolved in 95 parts by mass of dimethyl silicone oil (KF-96-2CS manufactured by Shin-Etsu Chemical Co., Ltd.) as a poor solvent, and a solution A (continuous Phase). The continuous phase was adjusted under a nitrogen environment.
Next, 20 parts by mass of distilled water, 0.3 part by mass of synthetic smectite LAPONITE RDS (manufactured by Rockwood Additives) as a layered clay mineral, and polyacrylic acid neutralized with triethylamine as an anionic polymer (Wako Pure Chemical Industries, Ltd.) Manufactured, 7 parts by mass).
Furthermore, 8 parts by mass of a blue pigment (Dainippon Ink Chemical Co., Ltd .: microencapsulated pigment MC Blue 182-E) having a volume average primary particle size of 0.1 μm was added as a coloring material, and the mixture was stirred and mixed to obtain a solution D (dispersed phase). ) Was adjusted. The dispersion phase was also adjusted in a nitrogen environment.

Next, 80 parts by mass of the solution A (continuous phase) and 20 parts by mass of the solution B (dispersed phase) were mixed and emulsified to prepare an emulsion. The emulsification was performed for 10 minutes with an ultrasonic crusher (UH-600S manufactured by SMT).
Next, moisture was removed by drying under reduced pressure with an evaporator at 65 ° C. while further stirring, and display particles 4 were produced. When the produced display particle 4 was observed with a scanning electron microscope (FE-SEM S-5500, manufactured by Hitachi), it was observed to be spherical. Moreover, when measured by HORIBA LB-550 (dynamic light scattering type particle size distribution measuring device), the average particle size was 742 nm.
Display particles 4 were produced as described above.

(Example 5)
5 parts by mass of a silicone-modified acrylic polymer (KP545 manufactured by Shin-Etsu Chemical Co., Ltd.) as an emulsifier is dissolved in 95 parts by mass of dimethyl silicone oil (KF-96-2CS manufactured by Shin-Etsu Chemical Co., Ltd.) as a poor solvent, and a solution A (continuous Phase). The continuous phase was adjusted under a nitrogen environment.

  Next, 1.5 parts by mass of Kunipia F (sodium-bentonite; manufactured by Kunimine Kogyo Co., Ltd.) as a layered clay mineral was mixed with 98.5 parts by mass of distilled water, and the dispersed liquid was dispersed by an ultrasonic crusher. Filtration was performed with a membrane filter having a pore diameter of 800 nm to remove coarse components.

  20 parts by mass of this filtrate and cationized polyvinyl alcohol (K-210 manufactured by Nippon Synthetic Chemical Co., Ltd., 7 parts by mass) as a cationic polymer were added, and the cation between the release layers of the layered clay mineral was added. A cation exchange reaction was carried out to exchange with cationized polyvinyl alcohol.

After the cation exchange reaction was performed, an absorption peak derived from the OH bond of the cationized polyvinyl alcohol was confirmed by FT-IR measurement. As a result, the O—H of the cationized polyvinyl alcohol was found in the vicinity of 3500 cm ^−1. Absorption peaks due to binding were observed. Thereby, it was confirmed that the cationized polyvinyl alcohol which is a cationic polymer was held on the surface of the plate-like member.
The measurement conditions for this FT-IR were as follows.
Fourier transform infrared spectroscopy:
Using a Fourier transform infrared spectrophotometer (FT-IR, Impact 400, manufactured by Nicolet (Ltd.)), the measurement frequency ^{4000cm -1 ~400cm} -1, the number of integrations 16, at a resolution ^{4 cm -1,} the organized Mt FT- IR spectrum was measured. The organic sample was measured by the KBr tablet method.

  Furthermore, 8 parts by mass of a blue pigment (Dainippon Ink Chemical Co., Ltd .: microencapsulated pigment MC Blue 182-E) having a volume average primary particle size of 0.1 μm was added as a colorant, and the mixture was stirred and mixed to obtain a solution B (dispersed phase). ) Was adjusted. The dispersion phase was also adjusted in a nitrogen environment.

  Next, 80 parts by mass of the solution A (continuous phase) and 20 parts by mass of the solution B (dispersed phase) were mixed and emulsified to prepare an emulsion. The emulsification was performed for 10 minutes with an ultrasonic crusher (UH-600S manufactured by SMT).

  Next, moisture was removed by drying under reduced pressure with an evaporator at 65 ° C. while further stirring, and display particles 5 were produced. When the produced display particles 5 were observed with a scanning electron microscope (FE-SEM S-5500 manufactured by Hitachi), it was observed that the particles were spherical. Moreover, when measured by HORIBA LB-550 (dynamic light scattering type particle size distribution measuring device), the average particle size was 650 nm.

(Comparative Example 1)
First, the following components were mixed to prepare a solution.
-Butyl methacrylate: 16.0 parts by mass-Lauryl methacrylate: 10.0 parts by mass-Styrene: 35.0 parts by mass-Methacrylic acid: 7.0 parts by mass-Glycidyl methacrylate: 12.0 parts by mass-X-22-174DX (Shin-Etsu Chemical Co., Ltd.): 20.0 mass parts perbutyl O (Nippon Yushi Co., Ltd.) 8.0 mass parts

  100 parts of methyl ethyl ketone was weighed into a reaction vessel equipped with a nitrogen introduction tube, the temperature was fixed at 80 ° C. while sealing with nitrogen, the solution was added dropwise over 2 hours, and the reaction was carried out for 6 hours while refluxing after completion of the addition. A polymer resin compound (carboxyl group-containing silicone graft acrylic resin compound) having a nonvolatile content of 50.7% and a number average molecular weight of 7,300 was synthesized.

  Measure the following <component (I)> in a 100 cc plastic bottle, disperse it in a paint shaker (manufactured by Toyo Seiki) for 2 hours, add the following <component (II)> to this, and mix To obtain a dispersed slurry.

<Ingredient (I)>
Carboxyl group-containing silicone graft acrylic resin compound: 12.0 parts by mass (polymer resin compound having a number average molecular weight of 7300 synthesized above)
Carbon black (pigment): 6.0 parts (manufactured by Degussa Huls; Printex 85)
Dispersant (Zeneca Corp .; Solsperse 5000): 0.3 parts by mass Nigrosine compound (charge control agent): 0.3 parts by mass (Chuo Chemical Co., Ltd .; CHUO CCA-2)
・ Methyl ethyl ketone (MEK: good solvent): 12.0 parts by mass

<Ingredient (II)>
Methyl ethyl ketone (good solvent): 15.0 parts by mass Silicone oil (dispersion medium): 15.0 parts by mass (trade name: KF-96L-2)

  Next, the dispersion slurry was slowly dropped into silicone oil (trade name: KF-96L-2) as a dispersion medium, and a resin compound was deposited on the pigment surface. After the dropping, methyl ethyl ketone was removed by distillation under reduced pressure to obtain comparative particles 1.

(Comparative Example 2)
5 parts by mass of a silicone-modified acrylic polymer (KP545 manufactured by Shin-Etsu Chemical Co., Ltd.) as an emulsifier is dissolved in 95 parts by mass of dimethyl silicone oil (KF-96-2CS manufactured by Shin-Etsu Chemical Co., Ltd.) as a poor solvent, and a solution A (continuous Phase). The continuous phase was adjusted under a nitrogen environment.

  Next, to 20 parts by mass of distilled water, cationized polyvinyl alcohol (K-210, 7 parts by mass made by Nippon Synthetic Chemical Co., Ltd.) is added as a cationic polymer, and a volume average primary particle size of 0.1 μm is used as a coloring material. 8 parts by mass of a blue pigment (Dainippon Ink Chemical Co., Ltd .: microencapsulated pigment MC Blue 182-E) was added and mixed by stirring to prepare solution B (dispersed phase). The dispersion phase was also adjusted in a nitrogen environment.

  Next, 80 parts by mass of the solution A (continuous phase) and 20 parts by mass of the solution B (dispersed phase) were mixed and emulsified to prepare an emulsion. The emulsification was performed for 10 minutes with an ultrasonic crusher (UH-600S manufactured by SMT).

  Next, moisture was removed by drying under reduced pressure with an evaporator at 65 ° C. while continuing stirring, and Comparative Particles 2 were produced. When the produced comparative particle 1 was observed with a scanning electron microscope (FE-SEM S-5500, manufactured by Hitachi), it was observed to be spherical. Moreover, when measured by HORIBA LB-550 (dynamic light scattering type particle size distribution measuring device), the average particle size was 280 nm.

(Evaluation)
―Evaluation of charging characteristics―
<Evaluation of charge amount>
Measurement results of charge amount in the initial state:
The zeta potential was measured for the display particles and the comparative particles obtained in the above Examples and Comparative Examples. The results are shown below.
Example 1 Zeta potential: -90.4 mV
Example 2 Zeta potential: -86.0 mV
Example 3 Zeta potential: +65.2 mV
Example 4 Zeta potential: +65.2 mV.
Example 5 Zeta potential: -88.1 mV
Comparative Example 1 Zeta potential: +70.5 mV
Comparative Example 2 Zeta potential: +35.3 mV

Result of measurement of charge amount after time from initial state:
The display particles and comparative particles obtained in the above Examples and Comparative Examples were measured for zeta potential after being left in a 60 ° C. environment for 1000 hours from the preparation of the particles. The results are shown below.
Example 1 Zeta potential: -90.2 mV
Example 2 Zeta potential: -86.4 mV
Example 3 Zeta potential: +64.2 mV
Example 4 Zeta potential: +65.2 mV
Example 5 Zeta potential: -90.4 mV
Comparative Example 1 Zeta potential: +54.1 mV
Comparative Example 2 Zeta potential: +22.3 mV

  From the above results, it was confirmed that in Example 1 to Example 5, the change in charge amount over time was suppressed as compared with Comparative Examples 1 and 2.

  In addition, in the obtained particle dispersion liquid, a zeta potential is generated at the interface between the dispersion medium and the particles constituting the zeta potential, that is, a zeta potential is generated. The value of increases. The zeta potential was measured using a laser zeta electrometer ELS-8000 manufactured by Otsuka Electronics.

<Evaluation of polarity stability>
For the display particles and the comparative particles obtained in Examples 1 to 5 and Comparative Examples 1 and 2, the stability of the charging polarity was evaluated.

First, white particles were produced.
By using zirconia balls having a diameter of 10 mm and carrying out ball milling for 20 hours, cyclohexyl methacrylate: 53 parts by mass, titanium oxide: (Taipeku CR63: manufactured by Ishihara Sangyo Co., Ltd.): 45 parts by mass, and cyclohexane: 5 parts by mass Dispersion A was prepared.
A calcium carbonate dispersion B was prepared by pulverizing 40 parts by mass of calcium carbonate and 60 parts by mass of water with a ball mill. 2% serogen aqueous solution (Daiichi Kogyo Seiyaku Co., Ltd.): 4.3 g, calcium carbonate dispersion B 8.5 g, and 20% saline: 50 g were mixed, degassed with an ultrasonic machine for 10 minutes, and then emulsified with an emulsifier. A liquid mixture C was prepared by stirring. 35 g of the dispersion A, 1 g of divinylbenzene, and polymerization initiator AIBN: 0.35 g were sufficiently mixed and deaerated with an ultrasonic machine for 10 minutes. This was put into the mixed solution C and emulsified with an emulsifier.
Next, this emulsified liquid was put into a bottle, siliconized, and using an injection needle, vacuum deaeration was sufficiently performed, and the mixture was sealed with nitrogen gas. Next, it was made to react at 60 degreeC for 10 hours, and particle | grains were created. After cooling, this dispersion was lyophilized by removing cyclohexane at −35 ° C. and 0.1 Pa for 2 days, dispersing the obtained particle powder in ion-exchanged water, decomposing calcium carbonate with hydrochloric acid water, Filtration was performed. Thereafter, it was washed with sufficient distilled water to have a uniform particle size and dried. Thus, white particles having a volume average primary particle diameter of 20 μm were prepared.

―Preparation of display media―
First, a display medium was produced as follows. A back substrate was formed by depositing ITO as an electrode with a thickness of 50 nm on a support substrate made of glass having a thickness of 0.7 mm by a sputtering method. When the color density of the back substrate at this time was measured by X-Rite, the L * value showed 93. Then, after forming a layer on this substrate using a photosensitive polyimide varnish, a gap member having a height of 100 μm and a width of 20 μm was formed by performing exposure and wet etching. Then, after forming a heat-fusible adhesive layer on the upper part of the gap member, after filling the dispersion of the above white particles and the display particles 1 obtained in Example 1, the back substrate A display substrate 1 produced in the same manner as above was attached to a back substrate so that the electrode surfaces face each other and heated to produce a display medium 1. Similarly, in place of the display particle 1, the display particle 2 to the display particle 5 adjusted in each of the example 2 to the example 5, and the comparison adjusted in each of the comparative example 1 to the comparative example 2 By using each of the particles 1 to the comparative particles 2, the display medium 2 to the display medium 5 and the comparative media 1 to the comparative medium 2 were produced. In addition, each display particle and comparative particle used the thing within 24 hours after manufacture.

Using each of display medium 1 to display medium 5 and comparison medium 1 to comparison medium 2 manufactured in this manner, the electrode on the display substrate side is positive and the electrode on the back substrate is negative. A voltage of 40 V was applied for 5 seconds.
Then, the display particles 1, the display particles 2, the display particles 5, and the comparative particles 1 that are the particles of the display medium 1, the display medium 2, the display medium 5, and the comparison medium 1 are moved to the display substrate side. Confirmed to move. For this reason, it was confirmed that the display particles 1, the display particles 2, the display particles 5, and the comparative particles 1 are charged in the negative electrode.
Next, the display medium 1, the display medium 2, the display medium 5, and the like after application of the above voltage (voltage of 40 V is applied for 5 seconds so that the electrode on the display substrate side is positive and the electrode on the back substrate is negative) The display substrate of Comparative Medium 1 was peeled off, and the color density of each display substrate was measured. The measurement results are shown in Table 1.

On the other hand, for the display particles 3, the display particles 4, and the comparative particles 2 that are the particles of the display medium 3, the display medium 4, and the comparison medium 2, the voltage (the electrode on the display substrate side is positive and the electrode on the back substrate is used). It was confirmed that when the voltage of 40 V was applied for 5 seconds so that the voltage becomes negative, it moved to the back substrate side. For this reason, it was confirmed that the display particles 3, the display particles 4, and the comparative particles 2 are charged to the positive electrode.
Next, the display medium 3, the display medium 4, and the comparison medium in a state after the above voltage is applied (a voltage of 40 V is applied for 5 seconds so that the electrode on the display substrate side is positive and the electrode on the back substrate is negative) Two back substrates were peeled off, and the color density of each back substrate was measured. The measurement results are shown in Table 1.

Next, after applying a voltage of 40 V for 5 seconds so that the display substrate side electrode is positive and the back substrate electrode is negative, the polarity is reversed, the display substrate side electrode is negative, and the back substrate electrode is After applying a series of operations 1000 times, applying a voltage of 40V for 5 seconds so that becomes positive, the voltage on the display substrate side is positive, and the voltage on the back substrate is negative so that the electrode on the back substrate is negative. Was applied for 5 seconds.
For the display medium 1, the display medium 2, the display medium 5, and the comparative medium 1, the display substrate is peeled off. For the display medium 3, the display medium 4, and the comparative example 2, the back substrate is peeled off, The color density of the substrate was measured. The measurement results are shown in Table 1.

  The color density (L *) was measured using an optical densitometer X-Rite MODEL 404 (manufactured by X-Rite).

  Table 1 shows the evaluation results of the charge amount evaluation and the polarity stability evaluation results.

As shown in Table 1, the display particles 1 to the display particles 5 of Examples 1 to 5 having a configuration including an ionic polymer, a plate-like member derived from a layered clay mineral, and a coloring material, Compared with Comparative Particles 1 to 2 of Comparative Examples 1 and 2 that do not contain a layered clay mineral, a decrease in charge amount was suppressed.
Moreover, as shown in the evaluation result of the polarity change shown in Table 1, the display particles 1 to 5 of the examples 1 to 5 are those of the comparative example 1 to the comparative example 2 that do not include the layered clay mineral. Compared to Comparative Particles 1 and 2, it can be said that the color density change is small and the polarity change of each particle is small.

  In addition, among the examples, Example 2 and Example 4 in which the organic treatment was performed were more charged than those in Examples 1 and 3 under the same conditions except that the organic treatment was not performed. Both the change and the change in polarity were small.

  Moreover, in Example 1 and Example 3 which did not perform the organic treatment among Examples, Example 1 using a cationic polymer as an ionic polymer had a change in charge amount and The change in polarity was small.

DESCRIPTION OF SYMBOLS 10 Display particle | grains, 12 Ionic polymer, 13 Display medium, 14 Plate-shaped member, Color material 16, 50 Dispersion medium

Claims (4)

A plate-like member derived from a layered clay mineral;
An ionic polymer held on the surface of the plate member;
Color materials,
Particles for display.   The display particle according to claim 1, wherein the ionic polymer is a cationic polymer.   The display particle according to claim 1, wherein the layered clay mineral has an organic cation between layers.   The display particle according to any one of claims 1 to 3, wherein the layered clay mineral is a smectite group.

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