JP2005352424A - Electrophoretic particle, electrophoretic dispersion liquid and electrophoresis display element using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide electrophoretic particles whose high speed response is made possible under a condition of low voltage driving and to provide an electrophoresis display element using the same. <P>SOLUTION: The electrophoretic particles having particles having an acidic group and any one compound represented by general formulae (1) to (3) is characterized in that the acidic group and any one compound represented by general formulae (1) to (3) form a salt. Wherein, n denotes an integer of 2 to 6, n<SP>1</SP>denotes an integer of 1 to 4, R<SB>1</SB>denotes a 1-18C straight or branched alkyl group, m, m<SP>1</SP>and m<SP>2</SP>each denotes an integer of 1 to 3 and a 3-18C straight or branched alkyl group may be substituted for hydrogen atoms of methylene groups which constitute a ring. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrophoretic particle, an electrophoretic dispersion, and an electrophoretic display element using the same.

  In recent years, with the development of information equipment, the need for low power consumption and thin display elements has increased, and research and development of display elements that meet these needs has been actively conducted. Among them, the liquid crystal display element can change the optical characteristics of the liquid crystal by electrically controlling the arrangement of liquid crystal molecules, and has been actively developed and commercialized as a display element that can meet the above needs. .

  However, these liquid crystal display elements sufficiently solve the problem that it is difficult to see characters on the screen due to the angle and reflected light when viewing the screen, or the visual burden caused by flickering of the light source, low luminance, etc. Absent. For this reason, research on display elements with less visual burden has been actively studied.

As one such display element, Paul F. et al. An electrophoretic display element invented by Evans et al. Is known (see Patent Document 1).
The electrophoretic display element includes a pair of substrates arranged with a predetermined gap therebetween, and electrodes are formed on each substrate. The gap between the substrates is filled with a large number of electrophoretic particles that are positively charged and colored, and a dispersion medium that is colored with a color different from the electrophoretic particles. Further, the partition is arranged so as to divide the gap into a large number of pixels along the surface direction of the substrate, and is configured to prevent the uneven distribution of the electrophoretic particles and to define the substrate gap.

  In such an electrophoretic display element, when a positive voltage is applied to the electrode on the viewer side and a negative voltage is applied to the opposite electrode, the positively charged electrophoretic particles are applied to the opposite electrode. When the display element is viewed from the observer, the same color as the dispersion medium is displayed.

  On the other hand, when a negative voltage is applied to the electrode on the viewer side and a positive voltage is applied to the electrode on the opposite side, the electrophoretic particles gather to cover the electrode on the viewer side, and the display element is moved from the viewer. When viewed, the same color as the electrophoretic particles is displayed. By performing such driving in units of pixels, an arbitrary image or character is displayed by a large number of pixels.

Conventionally, in an electrophoretic dispersion liquid used for an electrophoretic display element, a charging agent, a dispersing agent, or the like is added to an insulating dispersion medium to impart charging properties and dispersibility to the electrophoretic particles.
The chargeability of the electrophoretic particles is considered to be due to the zeta potential appearing on the particle surface when the dissociated charging agent is adsorbed on the particles.

On the other hand, the dispersibility of the electrophoretic particles is considered to be due to the steric exclusion effect being exhibited by the added dispersant adsorbing to the particles.
In recent years, in an electrophoretic dispersion medium colored with a dye, by combining a yellow pigment particle having an acidic site and a charge control agent comprising a polymer chain containing a basic group, the chargeability and dispersibility of the pigment particle are increased. Has been disclosed (see Patent Document 2).

In addition, in an electrophoretic dispersion liquid composed of a hydrocarbon solvent, particles having an acidic group (or basic group), a basic (or acidic) polymer, and a compound having a nonionic polar group, the particles are charged and dispersible. Has been disclosed (see Patent Document 3).
US Pat. No. 3,612,758 Japanese National Patent Publication No. 9-500458 JP 2002-0662545 A

Conventional electrophoretic particles using acid-base dissociation or electrophoretic particles using a charging agent have a small degree of dissociation in an insulating solvent and have a low zeta potential. As a result, the conventional electrophoretic particles have a problem that they cannot respond at high speed under low voltage driving conditions.
The present invention provides an electrophoretic particle capable of high-speed response under conditions of low-voltage driving, and an electrophoretic display element using the same.

  As a result of various studies to solve these problems, the present inventor has found that the dissociation characteristics and zeta are higher than those of electrophoretic particles using acid-base dissociation as in the past or electrophoretic particles using a charging agent. The present inventors have found electrophoretic particles having excellent potential characteristics and have achieved the present invention.

  That is, the present invention is an electrophoretic particle having particles having an acidic group and any one of the compounds represented by the following general formulas (1) to (3), wherein at least the surface of the particle has the acidic group. Electrophoretic particles, wherein any of the compounds represented by formulas (1) to (3) forms a salt.

(In the formula, n is an integer of 2 to 6. The ring is composed of an oxygen atom and a methylene group, and the hydrogen atom of the methylene group is substituted with a linear or branched alkyl group having 3 to 18 carbon atoms. May be.)

(In the formula, n ¹ is an integer of 1 to 4. R ₁ represents a linear or branched alkyl group having 1 to 18 carbon atoms. The ring is composed of a nitrogen atom and a methylene group, (The hydrogen atom of the methylene group may be substituted with a linear or branched alkyl group having 3 to 18 carbon atoms.)

(In the formula, m, m ¹ and m ² are integers of 1 to 3. The ring is composed of an oxygen atom, a nitrogen atom and a methylene group, and the hydrogen atom of the methylene group is a straight chain having 3 to 18 carbon atoms. And may be substituted with a linear or branched alkyl group.)
In the present invention, a salt formed of the acidic group and any one of the compounds represented by the general formulas (1) to (3) is an anion of the acidic group and the following general formulas (4) to (6): The salt which consists of the cation which consists of any compound represented by this is preferable.

(In the formula, M ⁺ represents a hydrogen ion or an alkali metal ion. N is an integer of 2 to 6. The ring is composed of an oxygen atom and a methylene group, and the hydrogen atom of the methylene group has 3 to 18 carbon atoms. (It may be substituted with a linear or branched alkyl group.)

(In the formula, n ¹ is an integer of 1 to 4. R ₁ represents a linear or branched alkyl group having 1 to 18 carbon atoms. The ring is composed of a nitrogen atom and a methylene group, (The hydrogen atom of the methylene group may be substituted with a linear or branched alkyl group having 3 to 18 carbon atoms.)

(In the formula, M ₁ ⁺ represents an alkali metal ion. M, m ¹ and m ² are integers of 1 to 3. The ring is composed of an oxygen atom, a nitrogen atom and a methylene group, and the hydrogen atom of the methylene group. May be substituted with a linear or branched alkyl group having 3 to 18 carbon atoms.
The particles having an acidic group are preferably particles in which a pigment is dispersed in a polymer having an acidic group or particles obtained by coloring a polymer having an acidic group with a dye.

The polymer having an acidic group is preferably a polymer having at least a carboxyl group, a sulfonic acid group, or a salt thereof.
In the present invention, the acidic group anion on the particle surface and the compounds represented by the general formulas (4) to (6) are at least partially dissociated and contained in the dispersion. The electrophoretic display element characterized by the above.

Since the electrophoretic particles of the present invention form a specific salt, they have dissociation characteristics superior to those of conventionally used acid-base salts and charging agents in an insulating solvent. Thus, the zeta potential of the electrophoretic particles can be dramatically increased as compared with the conventional case.
Therefore, the present invention can provide an electrophoretic particle capable of high-speed response under low voltage driving conditions, and an electrophoretic display element using the same.

An embodiment of an electrophoretic display element using electrophoretic particles of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing one embodiment of an electrophoretic display element using electrophoretic particles of the present invention.

  In the electrophoretic display element of FIG. 1A, the first substrate 1a provided with the first electrode 1c and the second substrate 1b provided with the second electrode 1d are opposed to each other at a predetermined interval through the partition wall 1g. Is arranged. An electrophoretic dispersion liquid including at least electrophoretic particles 1e and an electrophoretic dispersion medium 1f is sealed in a cell (space) including the first substrate 1a, the second substrate 1b, and the partition walls 1g. An insulating layer 1h is formed on each electrode. In the electrophoretic display element, the side on which the second substrate 1b is provided is a display surface.

  FIG. 1B shows an electrophoretic display element using microcapsules. A microcapsule 1i containing the electrophoretic dispersion is disposed on the first substrate 1a and covered with the second substrate 1b. When the microcapsule 1i is used, the insulating layer 1h may not be provided.

  In FIG. 1, the first electrode 1c is a pixel electrode that can independently apply a desired electric field to the electrophoretic dispersion liquid in each cell (or microcapsule), and the second electrode 1d has the same potential on the entire surface. This is a common electrode to be applied. This pixel electrode is provided with a switch element, a selection signal is applied to each row from a matrix drive circuit (not shown), and a control signal and an output from the drive transistor are applied to each column. A desired electric field can be applied to the electrophoretic dispersion in the cell (or microcapsule). The electrophoretic particles 1e in each cell (or microcapsule) are controlled by the electric field applied by the first electrode 1c, and each pixel has a color of the electrophoretic particles (for example, white) and a color of the dispersion medium (for example, blue). Is displayed. By performing such driving in units of pixels, an arbitrary image or character can be displayed by a large number of pixels.

The first substrate 1a is an arbitrary insulating member that supports the electrophoretic display element, and glass, plastic, or the like can be used.
For the first electrode 1c, a metal vapor-deposited film such as ITO (Indium Tin Oxide), tin oxide, indium oxide, gold, or chromium can be used, and a photolithography method is used for pattern formation of the first electrode 1c. be able to.

As the second substrate 1b, an insulating member such as a transparent glass substrate or a plastic substrate can be used.
A transparent electrode such as ITO or an organic conductive film can be used for the second electrode 1d.

  As the insulating layer 1h, a colorless and transparent insulating resin can be used. For example, acrylic resin, epoxy resin, fluorine resin, silicone resin, polyimide resin, polystyrene resin, polyalkene resin, or the like can be used.

  A polymer resin can be used as the material of the partition wall 1g. Any method may be used to form the partition walls. For example, a method of forming a partition wall by a photolithography method using a photosensitive resin, a method of bonding a partition wall prepared in advance to a substrate, a method of forming a partition wall by a mold, or the like can be used.

A method for filling the electrophoretic dispersion liquid in the cell is not particularly limited, but an ink jet type nozzle can be used.
The microcapsule 1i enclosing the electrophoretic dispersion liquid can be obtained by a known method such as an interfacial polymerization method, an in situ polymerization method, or a coacervation method.

  The material forming the microcapsule 1i is preferably a material that transmits light sufficiently. Specifically, urea-formaldehyde resin, melamine-formaldehyde resin, polyester, polyurethane, polyamide, polyethylene, polystyrene, polyvinyl alcohol, gelatin, or These copolymers can be mentioned.

Further, the method for disposing the microcapsule 1i on the first substrate 1a is not particularly limited, but an ink jet type nozzle can be used.
An example of the electrophoretic dispersion medium 1f is a highly insulating and colorless and transparent liquid. For example, aromatic hydrocarbons such as toluene, xylene, ethylbenzene, dodecylbenzene, aliphatic hydrocarbons such as hexane, cyclohexane, kerosene, normal paraffin, isoparaffin, chloroform, dichloromethane, pentachloroethane, 1,2-dibromoethane, 1, Halogenated hydrocarbons such as 1,2,2-tetrabromoethane, trichloroethylene, tetrachloroethylene, trifluoroethylene, tetrafluoroethylene, various natural or synthetic oils, etc. can be used, these alone or in combination of two or more May be used.

  In order to color the electrophoretic dispersion medium 1f, an oil-soluble dye having colors such as R (red), G (green), B (blue), C (cyan), M (magenta), and Y (yellow) is used. Can do. These oil-soluble dyes include azo dyes, anthraquinone dyes, quinoline dyes, nitro dyes, nitroso dyes, penoline dyes, phthalocyanine dyes, metal complex dyes, nafur dyes, benzoquinone dyes, cyanine dyes, indigo dyes, and quinoimine dyes. Dyes are preferred, and these may be used in combination.

  For example, the following oil-soluble dyes can be mentioned. Bali First Yellow (1101, 1105, 3108, 4120), Oil Yellow (105, 107, 129, 3G, GGS), Bali First Red (1306, 1355, 2303, 3304, 3306, 3320), Oil Pink 312, Oil Scarlet 308, Oil Violet 730, Bali First Blue (1501, 1603, 1605, 1607, 2606, 2610, 3405), Oil Blue (2N, BOS, 613), Macrolex Blue RR, Sumiplast Green G, Oil Green (502 BG) and the like, and the concentration of the oil-soluble dye is preferably 0.1 to 3.5% by weight with respect to the electrophoretic dispersion medium 1f.

  The electrophoretic particle 1e used in the present invention is an electrophoretic particle having an acidic group on at least the particle surface, a particle obtained by dispersing a pigment in a polymer having an acidic group, and a particle obtained by coloring a polymer having an acidic group with a dye. Etc. can be used.

  Particles in which a pigment is dispersed in a polymer having an acidic group can be obtained by polymerizing an acidic monomer containing the pigment. For example, a suspension polymerization method, an emulsion polymerization method, a precipitation polymerization method, a dispersion polymerization method, or the like can be used.

  Examples of the polymer having an acidic group constituting such particles include (meth) acrylic acid, 2-butenoic acid (crotonic acid), 3-butenoic acid (vinyl acetic acid), 3-methyl-3-butenoic acid, 3 -Pentenoic acid, 4-pentenoic acid, 4-methyl-4-pentenoic acid, 4-hexenoic acid, 5-hexenoic acid, 5-methyl-5-hexenoic acid, 5-heptenoic acid, 6-heptenoic acid, 6-methyl -6-heptenoic acid, 6-octenoic acid, 7-octenoic acid, 7-methyl-7-octenoic acid, 7-nonenoic acid, 8-nonenoic acid, 8-methyl-8-nonenoic acid, 8-decenoic acid, 9 -Decenoic acid, 3-phenyl-2-propenoic acid (cinnamic acid), carboxymethyl (meth) acrylate, carboxyethyl (meth) acrylate, vinylbenzoic acid, vinylphenylacetic acid, vinylphenylpropionic acid Maleic acid, fumaric acid, methylene succinic acid (itaconic acid), hydroxystyrene, styrene sulfonic acid, vinyl toluene sulfonic acid, vinyl sulfonic acid, sulfomethyl (meth) acrylate, 2-sulfoethyl (meth) acrylate, 2-propene-1- Homopolymers of acidic monomers such as sulfonic acid, 2-methyl-2-propene-1-sulfonic acid, 3-butene-1-sulfonic acid, or methyl (meth) acrylate, ethyl (meth) acrylate, styrene, Copolymers with monomers such as p-methylstyrene, p-ethylstyrene, acrylonitrile and the like can be used.

  As the pigment, an organic pigment, an inorganic pigment, or the like can be used. Examples of organic pigments include azo pigments, phthalocyanine pigments, quinacridone pigments, isoindolinone pigments, isoindoline pigments, dioxazine pigments, perylene pigments, perinone pigments, thioindigo pigments, quinophthalone pigments, anthraquinone pigments, nitro pigments, and nitroso pigments. Specifically, red pigments such as quinacridone red, lake red, brilliant carmine, perylene red, permanent red, toluidine red, madder lake, green pigments such as diamond green lake, phthalocyanine green, pigment green B, Victoria Blue pigments such as Blue Lake, Phthalocyanine Blue, Fast Sky Blue, Hansa Yellow, Fast Yellow, Disazo Yellow, Isoindolinone Yellow, Quinophthalo Yellow pigments such as yellow, aniline black, black pigments such as diamond black.

  Examples of inorganic pigments include white pigments such as titanium oxide, aluminum oxide, zinc oxide, lead oxide, tin oxide, and zinc sulfide, black pigments such as carbon black, manganese ferrite black, cobalt ferrite black, and titanium black, and cadmium red. Red pigments such as red iron oxide and molybdenum red, green pigments such as chromium oxide, viridian, titanium cobalt green, cobalt green and victoria green, blue pigments such as ultramarine blue, Prussian blue and cobalt blue, cadmium yellow and titanium yellow Yellow pigments such as yellow iron oxide, yellow lead, chrome yellow, and antimony yellow can be used.

  Particles obtained by coloring a polymer having an acidic group with a dye may be particles obtained by coloring polymer particles having an acidic group with a dye or particles obtained by polymerizing an acidic monomer containing a dye. Can do. The dye used here is not particularly limited as long as it is insoluble in the electrophoretic dispersion medium 1f. In order to obtain a polymer having an acidic group, the above-described monomer material can be used.

  In the electrophoretic particle of the present invention, on the surface of the particle having the acidic group, the acidic group and any one of the compounds represented by the following general formulas (1) to (3) form a salt. It is characterized by that.

Specifically, electrophoretic particles 1e are obtained by reacting with crown ether or azacrown ether using particles having an acidic group.
Moreover, the electrophoretic particle 1e is obtained by making it react with a crown ether or a cryptand using the alkali metal salt of the particle | grains which have such an acidic group. Here, the acidic group is a sulfonic acid group or a carboxyl group.

  The first electrophoretic particle of the present invention is an electrophoretic particle in which the acidic group and a compound represented by the following general formula (1) form a salt at least on the surface of the particle having an acidic group. .

(In the formula, n is an integer of 2 to 6. The ring is composed of an oxygen atom and a methylene group, and the hydrogen atom of the methylene group is substituted with a linear or branched alkyl group having 3 to 18 carbon atoms. May be.)
An example of the reaction for forming a salt at this time is shown in the following reaction formula (1).

  Reaction formula (1) is a reaction formula in which electrophoretic particles 1e having a crown ether salt are generated by reacting particles having a sulfonic acid group or particles having an alkali metal salt of sulfonic acid with crown ether. . The reaction solvent is not particularly limited, and examples thereof include the solvents described in the description of the electrophoretic dispersion medium 1f, and solvents such as ethanol and methanol.

  The crown ether salt is composed of a salt composed of an anion having an acidic group and a cation composed of a compound represented by the following general formula (4).

However, n is an integer of 2 to 6, and M ⁺ represents a hydrogen ion or an alkali metal ion. As an alkali metal ion, a sodium ion, a potassium ion, and a rubidium ion are preferable. Moreover, the hydrogen atom of the methylene group which comprises a ring may be substituted by the C3-C18 linear or branched alkyl group.

  Examples of preferred crown ethers represented by the general formula (1) include 12-crown-4-ether (n = 2), 2-hexyl-12-crown-4-ether (n = 2), 2-octyl- 12-crown-4-ether (n = 2), 2-decyl-12-crown-4-ether (n = 2), 2-dodecyl-12-crown-4-ether (n = 2), 2-tetradecyl -12-crown-4-ether (n = 2), 15-crown-5-ether (n = 3), 2-butyl-15-crown-5-ether (n = 3), 2-hexyl-15 Crown-5-ether (n = 3), 2-octyl-15-crown-5-ether (n = 3), 2-decyl-15-crown-5-ether (n = 3), 2-dodecyl-15 -Crown-5-ether n = 3), 2-tetradecyl-15-crown-5-ether (n = 3), 2,12-didodecyl-15-crown-5-ether (n = 3), 18-crown-6-ether (n = 4), 2-hexyl-18-crown-6-ether (n = 4), 2-octyl-18-crown-6-ether (n = 4), 2-decyl-18-crown-6-ether ( n = 4), 2-dodecyl-18-crown-6-ether (n = 4), 2-tetradecyl-18-crown-6-ether (n = 4), 2,3-dioctyl-18-crown-6 -Ether (n = 4), 2,12-didodecyl-18-crown-6-ether (n = 4), 2,15-didodecyl-18-crown-6-ether (n = 4), 2, 6, 11,15-tetra (dodecyl) 18-crown-6-ether (n = 4), 21-crown-7-ether (n = 5), 2-decyl-21-crown-7-ether (n = 5), 2-dodecyl-21-crown -7-ether (n = 5), 2-tetradecyl-21-crown-7-ether (n = 5), 2-hexadecyl-21-crown-7-ether (n = 5), 24-crown-8- Ether (n = 6), 2-decyl-24-crown-8-ether (n = 6), 2-dodecyl-24-crown-8-ether (n = 6), 2-tetradecyl-24-crown-8 -Ether (n = 6), 2-hexadecyl-24-crown-8-ether (n = 6) and the like.

  The crown ether in the insulative electrophoretic dispersion medium 1f has a structure in which the hydrophobic ethylene cross-linked portion faces outward and the oxygen atom faces inward. That is, inside the crown ether, a cavity that is hydrophilic and rich in electrons is formed. Cations are taken into this cavity and stabilized. In the electrophoretic dispersion medium 1f, cations (hydrogen ions, alkali metal ions, etc.) generated by the dissociation of the salt are not stabilized by the solvation, so that the dissociation hardly occurs. However, by using crown ether, the cation becomes a quasi-solvated state and can be stabilized. Therefore, the electrophoretic particle 1e having a crown ether salt exhibits excellent dissociation characteristics in the electrophoretic dispersion medium 1f.

  That is, the crown ether salt is easily dissociated in the dispersion and exhibits a large degree of dissociation. Since many acidic groups on the particle surface are dissociated, the charge amount of the particle is increased, and particles that are easy to migrate in the dispersion are generated. As a result, an electrophoretic display element capable of high-speed response under low voltage driving conditions is realized.

  The second electrophoretic particle of the present invention is an electrophoretic particle in which the acid group and a compound represented by the following general formula (2) form a salt at least on the surface of the particle having an acid group. .

(In the formula, n ¹ is an integer of 1 to 4. R ₁ represents a linear or branched alkyl group having 1 to 18 carbon atoms. The ring is composed of a nitrogen atom and a methylene group, (The hydrogen atom of the methylene group may be substituted with a linear or branched alkyl group having 3 to 18 carbon atoms.)
An example of the reaction for forming a salt at this time is shown in the following reaction formula (2).

  Reaction formula (2) is a reaction formula in which electrophoretic particles 1e having an azacrown ether salt are generated by reacting particles having a sulfonic acid group with an azacrown ether represented by the general formula (2). . The reaction solvent is not particularly limited, and examples include the solvents described in the reaction of crown ether salt.

  The azacrown ether salt is composed of a salt composed of an anion having an acidic group and a cation composed of a compound represented by the following general formula (5).

However, n ¹ is an integer of from 1 4, R ₁ is a straight or branched alkyl group having 1 to 18 carbon atoms. Moreover, the hydrogen atom of the methylene group which comprises a ring may be substituted by the C3-C18 linear or branched alkyl group.

As an example of a preferred azacrown ether, 1,4,7-tripropyl-1,4,7-triazacyclononane (n ¹ = 1), 2-decyl-1,4,7-tripropyl-1,4 7-triazacyclononane (n ¹ = 1), 1,4,7-tributyl-1,4,7-triazacyclononane (n ¹ = 1), 2-dodecyl-1,4,7-tributyl -1,4,7-triazacyclononane (n ¹ = 1), 1,4,7-trihexyl-1,4,7-triazacyclononane (n ¹ = 1), 2-dodecyl-1,4 , 7-trihexyl-1,4,7-triazacyclononane (n ¹ = 1), 1,4,7-trioctyl-1,4,7-triazacyclononane (n ¹ = 1), 1,4 7- tri (decyl) 1,4,7-triazacyclononane (n ¹ = 1), 1, 4, 7 Tri (dodecyl) -1,4,7-triazacyclononane (n ¹ = ^1), 1,4,7- tri (tetradecyl) -1,4,7-triazacyclononane (n ¹ = 1), 1,4,7,10-tetraoctyl-1,4,7,10-tetraazacyclododecane (n ¹ = 2), 1,4,7,10-tetra (decyl) -1,4,7,10 - tetraazacyclododecane (n ¹ = 2), 1,4,7,10- tetra (dodecyl) -1,4,7,10 tetraazacyclododecane ^{(n 1 = 2), 1,4,7} , 10-tetra (hexadecyl) -1,4,7,10-tetraazacyclododecane (n ¹ = 2), 1,4,7,10-tetra (octadecyl) -1,4,7,10-tetraazacyclo dodecane (n ¹ = 2), 1,4,7,10,13- pen octyl 1,4,7 10,13- penta azacyclopentadecan (n ¹ = 3), 1,4,7,10,13- penta (decyl) -1,4,7,10,13- penta azacyclopentadecan (n ¹ = 3) 1, 4, 7, 10, 13-penta (dodecyl) -1, 4, 7, 10, 13-pentaazacyclopentadecane (n ¹ = 3), ^1, 4, 7, 10, 13, 16-hexa (Decyl) -1,4,7,10,13,16-hexaazacyclooctadecane (n ¹ = 4), 1,4,7,10,13,16-hexa (tetradecyl) -1,4,7, 10, 13, 16-hexaazacyclooctadecane (n ¹ = 4), ^1, 4, 7, 10, 13, 16-hexa (hexadecyl) -1, 4, 7, 10, 13, 16-hexaazacyclooctadecane (N ¹ = 4).

  The azacrown ether in the insulating electrophoretic dispersion medium 1f has a structure in which the hydrophobic ethylene cross-linked portion faces outward and the nitrogen atom faces inward, like the above-mentioned crown ether. That is, the inside of the azacrown ether is formed with a hydrophilic and electron-rich cavity, and hydrogen ions are taken into this cavity and stabilized by pseudo solvation, so that the electrophoretic particles having an azacrown ether salt 1e exhibits excellent dissociation characteristics in the electrophoretic dispersion medium 1f.

  The third electrophoretic particle of the present invention is an electrophoretic particle in which the acidic group and a compound represented by the following general formula (3) form a salt at least on the surface of the particle having an acidic group. .

(In the formula, m, m ¹ and m ² are integers of 1 to 3. The ring is composed of an oxygen atom, a nitrogen atom and a methylene group, and the hydrogen atom of the methylene group is a straight chain having 3 to 18 carbon atoms. And may be substituted with a linear or branched alkyl group.)
An example of the reaction for forming a salt at this time is shown in the following reaction formula (3).

  Reaction formula (3) is a reaction formula in which electrophoretic particles 1e having a cryptand salt are generated by reacting particles having an alkali metal salt of sulfonic acid with the cryptand represented by the general formula (3). The reaction solvent is not particularly limited, and examples include the solvents described in the reaction of crown ether salt.

  The cryptand salt is composed of a salt composed of an anion having an acidic group and a cation composed of a compound represented by the following general formula (6).

However, m, m ¹ and m ² are integers of 1 to 3, and M ₁ ⁺ represents an alkali metal ion. As the alkali metal ions, sodium ions, potassium ions, rubidium ions, and cesium ions are preferable. Moreover, the hydrogen atom of the methylene group which comprises a ring may be substituted by the C3-C18 linear or branched alkyl group.

As an example of a preferred cryptand, 4, 10, 15-trioxa-1, 7-diazabicyclo [5.5.5] heptadecane (also known as cryptand 111, m = 1, m ¹ = 1, m ² = 1), 3- Tetradecyl-4,10,15-trioxa-1,7-diazabicyclo [5.5.5] heptadecane (m = 1, m ¹ = 1, m ² = 1) 4, 7, 13, 18-tetraoxa-1 10-diazabicyclo [8.5.5] eicosane (also known as cryptand 211, m = 2, m ¹ = 1, m ² = 1) 4, 7, 13, 16, 21-pentaoxa-1, 10-diazabicyclo [8.8.5] tricosane (aka cryptand ^{221, m = 2, m 1} = 2, m 2 = 1), 5- decyl -4,7,13,16,21- Pentaokisa 1,10-diazabicyclo [8.8. ] Tricosane (aka cryptands ^{221D, m = 2, m 1} = 2, m 2 = 1), 4,7,13,16,21,24- hexaoxa-1,10-diazabicyclo [8.8.8] hexacosane (also known as cryptands ^{222, m = 2, m 1} = 2, m 2 = 2), 5- decyl -4,7,13,16,21,24- hexaoxa-1,10-diazabicyclo [8.8.8 ] hexacosane (aka cryptands ^{222D, m = 2, m 1} = 2, m 2 = 2), 5- tetradecyl -4,7,13,16,21,24- hexaoxa-1,10-diazabicyclo [8.8 .8] hexacosane ^{(m = 2, m 1 =} 2, m 2 = 2), 5- hexadecyl -4,7,13,16,21,24- hexaoxa-1,10-diazabicyclo [8.8.8] Hexacosan (m = 2, ^{1 = 2, m 2 = 2} ), 4,7,10,16,19,24,27- Heputaokisa 1,13-diazabicyclo [11.8.8] nonacosanoic (aka cryptand 322, m = 3, m ¹ = 2, m ² = 2), 4, 7, 10, 16, 19, 22, 27, 30-octoxa- ¹ , 13-diazabicyclo [11.11.8] dotriacontane (also known as cryptand 332, m = 3, m ¹ = 3, m ² = 2), 4, 7, 10, 16, 19, 22, 27, 30, 33-nonaoxa- ¹ , 13-diazabicyclo [11.11.11] pentatriacontane ( Alias: cryptand 333, m = 3, m ¹ = 3, m ² = 3) and the like.

  The cryptand in the insulative electrophoretic dispersion medium 1f has a structure in which the hydrophobic ethylene cross-linked portion faces outward and the oxygen atom or nitrogen atom faces inward, like the above-mentioned crown ether. That is, the inside of the cryptand is formed with a hydrophilic and electron-rich cavity, and cations are taken into the cavity and stabilized by pseudo solvation. Excellent dissociation characteristics in the dispersion medium 1f.

  As described above, the electrophoretic particle 1e exhibits excellent dissociation characteristics in the insulating electrophoretic dispersion medium 1f, compared with a conventionally used charging agent (zirconium octylate). It has a degree of dissociation from several times to about 30 times.

  The degree of dissociation can be determined from well-known conductivity measurements. That is, the degree of dissociation is determined by dissolving a fixed amount of crown ether in a solvent and determining the ion concentration in the liquid from the conductivity.

  The average particle diameter of the electrophoretic particles 1e is preferably within a range of 50 nm to 10 μm, and more preferably 300 nm to 2 μm. When the average particle diameter exceeds 10 μm, high resolution display cannot be performed, which is not preferable. Further, if the average particle size is less than 50 nm, there is a problem in dispersion stability due to aggregation of particles, which is not preferable.

  The concentration of the electrophoretic particles 1e is preferably 1 to 40% by weight, more preferably 3 to 20% by weight with respect to the electrophoretic dispersion medium 1f. When the concentration of the electrophoretic particles 1e is less than 1% by weight, the display contrast of the electrophoretic particles 1e is not preferable. On the other hand, if the concentration of the electrophoretic particles 1e exceeds 40% by weight, the display contrast of the colored electrophoretic dispersion medium 1f becomes unpreferable.

  Regarding dispersion of the electrophoretic particles 1e in the electrophoretic dispersion medium 1f, a dispersion stabilizer may be added to cause the electrophoretic particles 1e to exhibit dispersibility, or a steric hindrance group may be introduced into the electrophoretic particles 1e. Dispersibility may be expressed.

  As a dispersion stabilizer, a homopolymer, a copolymer, a block polymer, etc. can be used. As an example, polyvinylpyrrolidone, polyvinyl methyl ether, (styrene-vinylpyridine) copolymer, (styrene-butadiene) A copolymer etc. can be mentioned.

  Regarding the steric hindrance group, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, tetradecyl (meth) acrylate, hexadecyl (meth) acrylate, Monomers such as octadecyl (meth) acrylate, butadiene, isoprene, isobutene, pentene, hexene can be used, and sterically hindered groups can be introduced onto the electrophoretic particles 1e by copolymerization with the acidic monomer. .

  A display example of an electrophoretic display element using the electrophoretic particles of the present invention is shown in FIG. FIG. 2 is a display example when the cell is filled with an electrophoretic dispersion liquid comprising white electrophoretic particles 1e and an electrophoretic dispersion medium 1f colored with a blue dye. The electrophoretic particle 1e is negatively charged due to the dissociation of the salt. When the second electrode 1d is applied with 0V and a negative voltage is applied to the first electrode 1c, the electrophoretic particles 1e gather at the second electrode 1d, and when the cell is observed from the top, the white electrophoretic particles 1e cause whitening. It can be seen (FIG. 2 (a)). On the other hand, when 0V is applied to the second electrode 1d and a positive voltage is applied to the first electrode 1c, the electrophoretic particles 1e gather on the first electrode 1c, and when the cell is observed from above, it looks blue (FIG. 2 (b )). By performing such driving in units of pixels, an arbitrary image or character can be displayed by a large number of pixels.

Another embodiment of the electrophoretic display element using the electrophoretic particles of the present invention will be described with reference to the drawings.
FIG. 3 is a cross-sectional view showing another embodiment of the electrophoretic display element using the electrophoretic particles of the present invention.

  In the electrophoretic display element of FIG. 3A, a first electrode 3c and a second electrode 3d are provided on a first substrate 3a, and insulating layers 3h and 3i are formed between the electrodes and on the second electrode 3d, respectively. ing. The insulating layer 3h may be colored or colorless and transparent, but the insulating layer 3i is colorless and transparent. The 1st board | substrate 3a and the 2nd board | substrate 3b are arrange | positioned so that it may oppose at predetermined intervals through the partition 3g. An electrophoretic dispersion liquid including at least electrophoretic particles 3e and an electrophoretic dispersion medium 3f is enclosed in a cell (space) including the first substrate 3a, the second substrate 3b, and the partition walls 3g. In the electrophoretic display element, the side on which the second substrate 3b is provided is a display surface.

  FIG. 3B shows an electrophoretic display element using microcapsules. A microcapsule 3j enclosing the electrophoretic dispersion is disposed on the first substrate 3a and covered with the second substrate 3b. Note that when the microcapsule 3j is used, the insulating layer 3i may not be provided.

  In FIG. 3, the second electrode 3d is a pixel electrode that can independently apply a desired electric field to the electrophoretic dispersion liquid in each cell (or microcapsule), and the first electrode 3c is the same potential on the entire surface. It is a common electrode applied by. This pixel electrode is provided with a switch element, a selection signal is applied to each row from a matrix drive circuit (not shown), and a control signal and an output from the drive transistor are applied to each column. A desired electric field can be applied to the electrophoretic dispersion in the cell (or microcapsule). The electrophoretic particles 3e in each cell (or microcapsule) are controlled by the electric field applied by the second electrode 3d, and each pixel has a color of the electrophoretic particles (for example, black) and a color of the insulating layer 3h (for example, white). ) Is displayed. By performing such driving in units of pixels, an arbitrary image or character can be displayed by a large number of pixels.

  The first substrate 3a is an arbitrary insulating member that supports the electrophoretic display element, and glass, plastic, or the like can be used. An insulating member such as a transparent glass substrate or plastic substrate can be used for the second substrate 3b.

  As the material of the first electrode 3c, a light reflective metal electrode such as Al is used. As the insulating layer 3h formed on the first electrode 3c, a fine particle for scattering light, such as aluminum oxide, titanium oxide or the like mixed with a colorless and transparent insulating resin can be used. Examples of the colorless and transparent insulating resin include the insulating resin described above. Or you may use the method of scattering light using the unevenness | corrugation of the metal electrode surface, without using microparticles | fine-particles.

  The second electrode 3d can be made of a conductive material that looks dark black when viewed from the viewer side of the display element, such as titanium carbide, blackened Cr, Al or Ti with a black layer formed on the surface. Further, a photolithography method can be used for pattern formation of the second electrode 3d.

Subsequently, an insulating layer 3i is formed on the second electrode 3d. As the insulating layer 3i, the above-described colorless and transparent insulating resin can be used.
Since the display contrast of this embodiment greatly depends on the area ratio between the second electrode 3d and the pixel, it is necessary to reduce the exposed area of the second electrode 3d with respect to that of the pixel in order to increase the contrast. It is preferably about 1: 2 to 1: 5.

  For the partition 3g, the same partition formation method and material as described above can be used. A method for filling the electrophoretic dispersion liquid in the cell is not particularly limited, but the above-described inkjet nozzle can be used.

  As described above, the microcapsule 3j containing the electrophoretic dispersion can be obtained by a known method such as an interfacial polymerization method, an in situ polymerization method, a coacervation method, and the like. The same polymer materials as described above can be used.

The method for disposing the microcapsule 3j on the first substrate 3a is not particularly limited, but the above-described ink jet type nozzle can be used.
For the electrophoretic dispersion medium 3f, the same liquid as described above can be used. As the electrophoretic particles 3e, the same particles as described above can be used. In this embodiment, the concentration of the electrophoretic particles 3e is preferably 0.5 to 10% by weight, more preferably 1 to 5% by weight, based on the electrophoretic dispersion medium 3f. When the concentration of the electrophoretic particles 3e is less than 0.5% by weight, it is not preferable because the first electrode 3c cannot be concealed and the display contrast becomes light. On the other hand, if the concentration of the electrophoretic particles 3e exceeds 10% by weight, it overflows from the colored second electrode 3d and the display contrast is deteriorated.

  A display example of an electrophoretic display element using the electrophoretic particles of the present invention is shown in FIG. FIG. 4 is a display example when the cell is filled with an electrophoretic dispersion liquid composed of black electrophoretic particles 3e and a colorless and transparent electrophoretic dispersion medium 3f. The electrophoretic particle 3e is negatively charged due to the dissociation of the salt. It is assumed that the top of the insulating layer 3h is white and the top of the second electrode 3d is black. When 0V is applied to the first electrode 3c and a positive voltage is applied to the second electrode 3d, the electrophoretic particles 3e gather on the second electrode 3d, and when the cell is observed from above, it appears white (FIG. 4 (a)). . On the other hand, when 0V is applied to the first electrode 3c and a negative voltage is applied to the second electrode 3d, the electrophoretic particles 3e gather on the first electrode 3c, and when the cell is observed from above, it appears black (FIG. 4B). )). By performing such driving in units of pixels, an arbitrary image or character can be displayed by a large number of pixels.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.
Example 1
Hydrophobized titanium oxide (average particle size 0.2 μm) 15 g and AIBN (polymerization initiator) 1.7 g were mixed with 7 g of methacrylic acid and 130 g of methyl methacrylate to obtain a uniform mixed solution. The above homogeneous mixed solution was charged into a dispersion medium obtained by dispersing 90 g of calcium phosphate in 1800 g of a sodium dodecyl sulfate aqueous solution (concentration 0.05 wt%). This mixed solution was stirred with a homogenizer at 10,000 rpm for 15 minutes to prepare a suspension. Thereafter, this suspension was polymerized under a nitrogen atmosphere at 80 ° C. for 7 hours. After completion of the polymerization, the mixture was washed with hydrochloric acid, and further washed with water, dried and classified to obtain particles in which 145 g of titanium oxide was coated with a (methacrylic acid-methyl methacrylate) copolymer. The average particle size was about 2 μm.

  Further, 1.1 g of 15-crown-5-ether represented by the following chemical formula (7) was reacted with 10 g of this particle in methanol, followed by separation and purification to obtain electrophoretic particles 1e having a crown ether salt. It was.

  5% by weight of electrophoretic particles 1e (white particles), 2.5% by weight of styrene-butadiene copolymer as a dispersion stabilizer, and 0.1% by weight of oil blue N (manufactured by Aldrich) as an electrophoretic dispersion medium 1f are dissolved. 12.5% by weight of Isopar H (manufactured by Exxon) colored in blue, and an electrophoretic dispersion liquid composed of these is injected into the cell using an ink jet nozzle, and a voltage application circuit is connected to FIG. The electrophoretic display element shown in a) was produced.

  From the electrical conductivity measurement, the degree of dissociation of the crown ether salt of the electrophoretic particles 1e is about 25 times that of the charging agent used in Comparative Example 1 described later, and the crown ether salt of the electrophoretic particles 1e has excellent dissociation characteristics. It was confirmed that it has.

  Further, when contrast display is performed at a low voltage drive of ± 5 V, a clear blue-white display can be performed, and the electrophoretic particle 1 e has a response speed about several tens of times that of the particles of Comparative Example 1. Confirmed that high-speed response is possible.

Example 2
Using the electrophoretic dispersion liquid obtained in the same manner as in Example 1, microcapsules 1i enclosing the dispersion liquid were prepared by an in situ polymerization method. The membrane material is urea-formaldehyde resin. The microcapsule 1i was placed on the first substrate 1a using an inkjet nozzle, and a voltage application circuit was connected to produce the electrophoretic display element shown in FIG.

  From the electrical conductivity measurement, the degree of dissociation of the crown ether salt of the electrophoretic particles 1e is about 25 times that of the charging agent used in Comparative Example 1 described later, and the crown ether salt of the electrophoretic particles 1e has excellent dissociation characteristics. It was confirmed that it has.

  Further, when contrast display is performed at a low voltage drive of ± 5 V, a clear blue-white display can be performed, and the electrophoretic particle 1 e has a response speed about several tens of times that of the particles of Comparative Example 1. Confirmed that high-speed response is possible.

Example 3
Particles obtained by coating titanium oxide with a methacrylic acid-methyl methacrylate copolymer obtained in the same manner as in Example 1 were further polymerized in 2-step with 2-ethylhexyl methacrylate to form a core-shell structure, and steric hindrance was formed on the particle surface. A group was introduced.

  Next, 2.0 g of 1,4,7,10,13-penta (n-butyl) -1,4,7,10,13-pentaazacyclopentadecane represented by the chemical formula (8) was added to 10 g of this particle in methanol. After reacting in, electrophoretic particles 1e having an azacrown ether salt were obtained by separation and purification.

  Electrophoretic dispersion comprising 5% by weight of electrophoretic particles 1e (white particles) and 95% by weight of Isopar H colored in blue by dissolving 0.1% by weight of oil blue N (Aldrich) as the electrophoretic dispersion medium 1f. The liquid was injected into the cell using an inkjet nozzle, and a voltage application circuit was connected to produce the electrophoretic display element shown in FIG.

  From the electrical conductivity measurement, the degree of dissociation of the azacrown ether salt of the electrophoretic particle 1e is about 18 times that of the charging agent used in Comparative Example 1 described later, and the crown ether salt of the electrophoretic particle 1e is excellent in dissociation. It was confirmed that it had characteristics.

  Further, when contrast display is performed at a low voltage drive of ± 5 V, a clear blue-white display can be performed, and the electrophoretic particle 1 e has a response speed about several tens of times that of the particles of Comparative Example 1. Confirmed that high-speed response is possible.

Example 4
Using an electrophoretic dispersion obtained in the same manner as in Example 3, a microcapsule 1i enclosing the dispersion was produced by an in situ polymerization method. The membrane material is urea-formaldehyde resin. The microcapsule 1i was placed on the first substrate 1a using an inkjet nozzle, and a voltage application circuit was connected to produce the electrophoretic display element shown in FIG.

  From the electrical conductivity measurement, the degree of dissociation of the azacrown ether salt of the electrophoretic particle 1e is about 18 times that of the charging agent used in Comparative Example 1 described later, and the crown ether salt of the electrophoretic particle 1e is excellent in dissociation. It was confirmed that it had characteristics.

  Further, when contrast display is performed at a low voltage drive of ± 5 V, a clear blue-white display can be performed, and the electrophoretic particle 1 e has a response speed about several tens of times that of the particles of Comparative Example 1. Confirmed that high-speed response is possible.

Example 5
Hydrophobized carbon black (average particle size 30 nm) 10 g and AIBN (polymerization initiator) 1.7 g were mixed with sodium styrenesulfonate 5 g and styrene 130 g to obtain a uniform mixed solution. The above homogeneous mixed solution was charged into a dispersion medium obtained by dispersing 90 g of calcium phosphate in 1800 g of a sodium dodecyl sulfate aqueous solution (concentration 0.05 wt%). This mixture was stirred with a homogenizer at 10,000 rpm for 15 minutes to prepare a suspension. Thereafter, this suspension was polymerized under a nitrogen atmosphere at 80 ° C. for 7 hours. After completion of the polymerization, the mixture was washed with hydrochloric acid, and further washed with water, dried and classified to obtain 140 g of particles coated with carbon black with a (styrenesulfonic acid-styrene) copolymer. The average particle size was about 2 μm.

  Subsequently, styrene sulfonic acid on 10 g of particles was treated with potassium chloride to convert to potassium salt, and then 5-decyl-4, 7, 13, 16, 21, 24, hexahexa-1 represented by the chemical formula (9). The reaction was carried out in methanol with 3.0 g of 10-diazabicyclo [8,8,8] hexacosane (cryptand 222D). Thereafter, separation and purification were performed to obtain electrophoretic particles 3e having a cryptand salt.

  Electrophoretic dispersion liquid comprising 1% by weight of electrophoretic particles 3e (black particles), 0.5% by weight of styrene-butadiene copolymer as a dispersion stabilizer, and 98.5% by weight of Isopar H as an electrophoretic dispersion medium 3f. Was injected into the cell using an inkjet nozzle, and a voltage application circuit was connected to produce the electrophoretic display element shown in FIG.

  From the electrical conductivity measurement, the dissociation degree of the cryptand salt of the electrophoretic particle 3e is about 15 times that of the charging agent used in Comparative Example 2 described later, and the cryptand salt of the electrophoretic particle 3e has excellent dissociation characteristics. I confirmed that

  Further, when contrast display is performed with a low voltage drive of ± 5 V, clear black and white display can be performed, and the electrophoretic particle 3 e has a response speed about several tens of times that of the particle of Comparative Example 2. Confirmed that high-speed response is possible.

Example 6
Using an electrophoretic dispersion obtained in the same manner as in Example 5, a microcapsule 3j containing the dispersion was produced by an interfacial polymerization method. The film material is a polyamide resin. The microcapsule 3j was placed on the first substrate 3a using an inkjet nozzle, and a voltage application circuit was connected to produce the electrophoretic display element shown in FIG.

  From the electrical conductivity measurement, the dissociation degree of the cryptand salt of the electrophoretic particle 3e is about 15 times that of the charging agent used in Comparative Example 2 described later, and the cryptand salt of the electrophoretic particle 3e has excellent dissociation characteristics. I confirmed that

  Further, when contrast display is performed with a low voltage drive of ± 5 V, a clear black and white display can be performed, and the electrophoretic particles 3e have a response speed about several tens of times that of the particles of Comparative Example 2. Confirmed that high-speed response is possible.

Comparative Example 1
A uniform mixed solution was obtained by mixing 137 g of methyl methacrylate with 15 g of hydrophobized titanium oxide and 1.7 g of AIBN (polymerization initiator). The above homogeneous mixed solution was charged into a dispersion medium obtained by dispersing 90 g of calcium phosphate in 1800 g of a sodium dodecyl sulfate aqueous solution (concentration 0.05 wt%). This mixed solution was stirred with a homogenizer at 10,000 rpm for 15 minutes to prepare a suspension. Thereafter, this suspension was polymerized under a nitrogen atmosphere at 80 ° C. for 7 hours. After completion of the polymerization, the particles were washed with hydrochloric acid, and further washed with water, dried and classified to obtain particles coated with titanium oxide with polymethyl methacrylate. The average particle size was about 2 μm.

  5% by weight of the above particles (white particles), 0.5% by weight of zirconium octylate as a charging agent, 2.5% by weight of styrene-butadiene copolymer as a dispersion stabilizer, 0.1% by weight of Oil Blue N (Aldrich) As shown in FIG. 1A, an electrophoretic dispersion liquid composed of Isopar H 92% by weight dissolved in blue is injected into a cell using an inkjet nozzle and a voltage application circuit is connected. An electrophoretic display element was produced.

  When contrast display was performed at the same drive voltage as in Examples 1 to 4, a clear blue-white display and high-speed response could not be achieved because the dissociation degree of the charging agent was small and the zeta potential of the particles was low.

Comparative Example 2
A uniform mixed solution was obtained by mixing 135 g of styrene with 10 g of hydrophobized carbon black (average particle size 30 nm) and 1.7 g of AIBN (polymerization initiator). The above homogeneous mixed solution was charged into a dispersion medium obtained by dispersing 90 g of calcium phosphate in 1800 g of a sodium dodecyl sulfate aqueous solution (concentration 0.05 wt%). This mixed solution was stirred with a homogenizer at 10,000 rpm for 15 minutes to prepare a suspension. Thereafter, this suspension was polymerized under a nitrogen atmosphere at 80 ° C. for 7 hours. After completion of the polymerization, the mixture was washed with hydrochloric acid, and further washed with water, dried, and classified to obtain particles coated with carbon black with polystyrene. The average particle size was about 2 μm.

  1% by weight of the above particles, 0.1% by weight of zirconium octylate as a charging agent, 0.5% by weight of a (styrene-butadiene) copolymer as a dispersion stabilizer, and 98.4% by weight of Isopar H as an electrophoretic dispersion medium 3f. The electrophoretic dispersion liquid composed of these was injected into the cell using an ink jet nozzle, and a voltage application circuit was connected to produce the electrophoretic display element shown in FIG.

  When contrast display was performed at the same drive voltage as in Examples 5 and 6, since the degree of dissociation of the charging agent was small and the zeta potential of the particles was low, clear monochrome display and high-speed response could not be achieved.

  The electrophoretic particles of the present invention can be utilized in industrial fields such as electrophotography using electrophoretic display elements and liquid toner. The salt of the electrophoretic particle of the present invention has a dissociation property superior to that of an acid-base salt or a charging agent that has been conventionally used in an insulating solvent. Than can be dramatically higher. Therefore, the present invention can provide an electrophoretic display element and an electrophotography using electrophoretic particles capable of high-speed response.

It is sectional drawing which shows the example of 1 embodiment of the electrophoretic display element using the electrophoretic particle of this invention. It is the schematic which shows the example of a display of the electrophoretic display element using the electrophoretic particle of this invention. It is sectional drawing which shows the other embodiment example of the electrophoretic display element using the electrophoretic particle of this invention. It is the schematic which shows the example of a display of the electrophoretic display element using the electrophoretic particle of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a 1st board | substrate 1b 2nd board | substrate 1c 1st electrode 1d 2nd electrode 1e Electrophoretic particle 1f Electrophoretic dispersion medium 1g Partition 1h Insulating layer 1i Microcapsule 3a 1st board | substrate 3b 2nd board | substrate 3c 1st electrode 3d 2nd electrode 3e Electrophoretic particle 3f Electrophoretic dispersion medium 3g Partition wall 3h Insulating layer 3i Insulating layer 3j Microcapsule

Claims (6)

An electrophoretic particle having particles having an acidic group and any of the compounds represented by the following general formulas (1) to (3), wherein at least the surface of the particle has the acidic group and the general formula (1). ) To (3), and any one of the compounds forms a salt.

(In the formula, n is an integer of 2 to 6. The ring is composed of an oxygen atom and a methylene group, and the hydrogen atom of the methylene group is substituted with a linear or branched alkyl group having 3 to 18 carbon atoms. May be.)

(In the formula, n ¹ is an integer of 1 to 4. R ₁ represents a linear or branched alkyl group having 1 to 18 carbon atoms. The ring is composed of a nitrogen atom and a methylene group, (The hydrogen atom of the methylene group may be substituted with a linear or branched alkyl group having 3 to 18 carbon atoms.)

(In the formula, m, m ¹ and m ² are integers of 1 to 3. The ring is composed of an oxygen atom, a nitrogen atom and a methylene group, and the hydrogen atom of the methylene group is a straight chain having 3 to 18 carbon atoms. And may be substituted with a linear or branched alkyl group.) A salt formed of the acidic group and any one of the compounds represented by the general formulas (1) to (3) is represented by an anion of the acidic group and the following general formulas (4) to (6). The electrophoretic particle according to claim 1, comprising a cation comprising any one of the compounds.

(In the formula, M ⁺ represents a hydrogen ion or an alkali metal ion. N is an integer of 2 to 6. The ring is composed of an oxygen atom and a methylene group, and the hydrogen atom of the methylene group has 3 to 18 carbon atoms. (It may be substituted with a linear or branched alkyl group.)

(In the formula, n ¹ is an integer of 1 to 4. R ₁ represents a linear or branched alkyl group having 1 to 18 carbon atoms. The ring is composed of a nitrogen atom and a methylene group, (The hydrogen atom of the methylene group may be substituted with a linear or branched alkyl group having 3 to 18 carbon atoms.)

(In the formula, M ₁ ⁺ represents an alkali metal ion. M, m ¹ and m ² are each an integer of 1 to 3. The ring is composed of an oxygen atom, a nitrogen atom and a methylene group, and a hydrogen atom of the methylene group. May be substituted with a linear or branched alkyl group having 3 to 18 carbon atoms.)   3. The electrophoretic particle according to claim 1, wherein the particle having an acidic group is a particle in which a pigment is dispersed in a polymer having an acidic group or a particle in which a polymer having an acidic group is colored with a dye.   The electrophoretic particle according to claim 3, wherein the polymer having an acidic group is a polymer having at least a carboxyl group, a sulfonic acid group, or a salt thereof.   An electrophoretic dispersion liquid comprising the electrophoretic particles according to claim 1 and an insulating solvent, wherein the anion of an acidic group on the particle surface and the general formulas (4) to (6) The electrophoretic dispersion is characterized in that the compound represented by (2) is at least partially dissociated and contained in the dispersion.   An electrophoretic display element using the electrophoretic dispersion according to claim 5.

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