JP2003290647A - Method for producing microcapsule encapsulating electrophoretic particle dispersion and reversible display medium using the capsule - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a microcapsule encapsulating electrophoretic particle dispersion by which a microcapsule with uniform particle size is produced and the content of the electrophoretic particle in the microcapsule is uniformed to make high definition and high contrast display possible in a display apparatus using the microcapsule encapsulating the electrophoretic particle and to provide a reversible display medium using the capsule. <P>SOLUTION: The method for producing a microcapsule encapsulating electrophoretic particle dispersion comprises: discharging a dispersion phase formed by dispersing an electrophoretic particle in a hydrophobic dispersant to a fluidizing continuous phase of a hydrophilic medium containing a dispersion stabilizer through a large number of holes formed in a plate contacting the continuous phase; brining the dispersion phase into contact with the continuous phase; and forming a microcapsule wall between the dispersion phase and the continuous phase after the dispersion phase is emulsified. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an effective method for producing microcapsules containing an electrophoretic particle dispersion liquid and having a uniform particle size, and a display medium using the same.

[0002]

2. Description of the Related Art Microcapsules are used in many fields such as recording materials such as pressure-sensitive recording paper and heat-sensitive recording paper, agricultural chemicals, pharmaceuticals, fragrances, liquid crystals and adhesives. Many methods have been proposed for the production method, and typical microencapsulation methods include coacervation method, interfacial polymerization method,
The in-situ polymerization method and the like are known. By the way, in recent years, with the development of information equipment, the data amount of various information has been expanding, and the output of information has also taken various forms. The form of information output is generally displayed on a display screen using a cathode ray tube or liquid crystal, but these displays are required to be portable and have low power consumption, and new displays are being actively developed. There is. As such a new display, a system in which electrophoretic particles are dispersed in a dispersion medium colored in a color tone different from that of the particles is encapsulated in a microcapsule, and these microcapsules are arranged between electrodes. An electrophoretic display device is disclosed in Japanese Patent Laid-Open No. 1-86116 (Patent No. 255178).
3), US Pat. No. 6,241,921, US Pat. No. 6,262,706, and the like. This method reduces the burden on the user's eyes because it is a reflective display that does not require a backlight like liquid crystal displays, does not become difficult to see even if the viewing angle is changed, and the response time is compared. It is possible to rewrite as quickly as possible.Furthermore, the electrophoretic particles that have moved to the electrodes by applying a voltage have a memory property that maintains that state for a long period of time even if the voltage is removed. It is expected to have excellent performance as a display device such that it does not require electric power during the running time. As a method for producing a microcapsule containing electrophoretic particles, it is disclosed that a general microencapsulation method is used as described above. It is difficult to make microcapsules, and currently there is a problem that sieving by classification is performed and production efficiency is very poor, which is an obstacle to the spread of the display device. Since the particle size of the microcapsules is not uniform, the content of the electrophoretic particles contained therein is also uneven, and as a result, there is a problem that the contrast in display is lowered.

[0003]

The object of the present invention is to reduce the particle size of the microcapsule in order to enable high-definition and high-contrast display in a display device using microcapsules containing electrophoretic particles. A method for producing microcapsules containing an electrophoretic particle-dispersed solution, which can be produced uniformly and have a uniform content of electrophoretic particles in the microcapsules, and a reversible display medium using the capsules Is.

[0004]

Means for Solving the Problems As a result of intensive studies by the present inventors, a microcapsule produced by discharging a dispersed phase in which electrophoretic particles are dispersed in a hydrophobic dispersion medium from a large number of pores has the above-mentioned problems. I found that I could solve it.

That is, according to the present invention, the electrophoretic particles are dispersed in a hydrophobic dispersion medium through the pores of a plate having a large number of pores, which are in contact with a flowing continuous phase made of a hydrophilic medium containing a dispersion stabilizer. Is discharged into the continuous phase, brought into contact with the continuous phase to emulsify the dispersed phase, and then microcapsule walls are formed between the dispersed phase and the continuous phase, electrophoretic particles. The present invention relates to a method for producing dispersion-containing microcapsules.

The present invention also relates to a method for producing the above-mentioned microcapsules containing electrophoretic particle dispersion liquid, characterized in that the plate has an aspect ratio of 2 to 10.

The present invention also relates to a method for producing the above-mentioned microcapsules containing electrophoretic particle dispersion liquid, which has a short side length of 1 to 50 μm.

The present invention also relates to a method for producing the above-mentioned microcapsules containing electrophoretic particle dispersion liquid, characterized in that the holes of the plate are rectangular.

In the present invention, the dispersion stabilizer contains at least one of a carboxyl group, an acid anhydride group, a hydroxyl group, an amino group, an isocyanate group and a glycidyl group as a reactive functional group, and has a weight average molecular weight. Is 1000-2
It is related with the manufacturing method of the said electrophoretic particle dispersion liquid containing microcapsule characterized by being 000000.

The present invention also relates to a method for producing the above-mentioned microcapsules containing electrophoretic particle dispersion liquid, wherein the particle size of the microcapsules is 1 to 500 μm.

The present invention also relates to a method for producing the above-mentioned microcapsules containing electrophoretic particulate dispersion liquid, which comprises one or more dispersants as a dispersed phase.

Further, according to the present invention, the electric conductivity of the dispersed phase is 0 to 2
The present invention relates to the display liquid for an electrophoretic display device, which has a range of 0 pS / cm.

Further, the present invention is characterized in that the electrophoretic particles include at least two types of colored particles having different color tones and electrophoretic properties, and the electrophoretic particle-dispersed liquid-encapsulating microcapsules. Manufacturing method.

The present invention also relates to an electrophoretic particle dispersion-containing microcapsule produced by the method for producing an electrophoretic particle dispersion-containing microcapsule.

In the present invention, at least one of the microcapsules containing the electrophoretic particle dispersion liquid is transparent.
The present invention relates to a reversible display medium sandwiched between a pair of opposing electrodes.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The method for producing microcapsules containing electrophoretic particles according to the present invention comprises the steps of dispersing at least two kinds of colored particles having different color tones and electrophoretic properties, ie, polarities, in a hydrophobic dispersion medium. The dispersion liquid is emulsified in a continuous phase composed of a hydrophilic medium containing a dispersion stabilizer to carry out microencapsulation. In the process, a dispersed phase in which electrophoretic particles are dispersed in a hydrophobic dispersion medium through a large number of pores. Are discharged, and the dispersed phase is fed into a continuous phase made of a hydrophilic medium containing a dispersion stabilizer to contact with the continuous phase, and immediately the microcapsule wall is formed via an emulsified state, thereby forming particles of the microcapsule. Diameter from 1 to 500
μm, more preferably 10 to 100 μm,
It has become possible to make the particle size distribution of the microcapsules having good contrast preferably 100% or less, more preferably 70% or less in terms of the coefficient of variation.

The hole for discharging the dispersed phase used in the present invention may have any shape, but when the aspect ratio is 2 to 10 or the hole has a rectangular shape, the short side The length is preferably 1 to 50 μm. When the aspect ratio is in the above range, the variation coefficient of the particle size distribution of the microcapsules shows a very small value, and more preferable particles can be selectively obtained. Further, when the shape of the holes is rectangular and the short side length is 1 μm or less, the generated particles become too small, resulting in a decrease in contrast. This is because when the short side length is 50 μm or more, the generated particles become large and the particle moving distance increases, resulting in an increase in response time during reverse display.

As an apparatus capable of discharging such a dispersed phase, for example, an apparatus having a plate in which a large number of nozzles having a constant diameter are arranged in an array is disclosed in Japanese Patent Laid-Open No. 9-2252.
There is a microchannel type discharge device disclosed in Japanese Patent Publication No. 91, which makes it possible to manufacture electrophoretic particle dispersion-containing microcapsules having a uniform particle size distribution. Furthermore, the through-type microchannels introduced in G122 of the 33rd Autumn Meeting of the Chemical Engineering Society of Japan, through-holes created by photolithography and high-density plasma etching enable high integration of channels. It has the advantage of superior production efficiency as compared to the arrayed microchannels described above. As a method for producing a microcapsule by sending the dispersed phase into the continuous phase through pores having a constant diameter, for example, a method of performing filtration using a membrane made of polycarbonate (BIOCHMICA ETBIOPHYSICA A
CTA, 557 (1979) NORTH-HOLLAND BIOCHEMICALPRESS),
Method of repeating filtration using PTFE (polytetrafluoroethylene) membrane (The 26th Autumn Meeting of the Chemical Engineering Society of Japan)
(Summary of Abstracts: 1993), and a method of feeding into a continuous phase through a porous glass membrane having uniform pores (JP-A-2-
95433), or a laminar flow dropping method using a nozzle or a perforated plate (Chemical Engineering Volume 21 No. 4: 1957), etc., but it is an object of the present invention.
This is not sufficient for efficiently producing microcapsules containing electrophoretic particle dispersion liquid having a uniform particle size distribution.

In the microcapsule manufacturing apparatus according to the present invention, the pressurized dispersed phase may be forcibly fed into the continuous phase via a large number of microchannels having a constant width formed on the substrate or the like. it can. Further, the microcapsule production apparatus according to the present invention includes a substrate on which a supply port for the dispersed phase is formed, and a gap for supplying the dispersed phase is formed between the substrate and a plate arranged facing this substrate, A boundary between the dispersed phase and the continuous phase is formed on the surface of the substrate facing the plate, and a large number of microchannels having a constant width are formed at the boundary, and the dispersed phase and the continuous phase are formed through the microchannel. Can be contacted.

The plate facing the substrate may be a transparent plate. By doing so, it is possible to directly observe the channel movement of the dispersed phase and the contact state with the continuous phase, and it becomes possible to monitor the production of microcapsules, which facilitates production control by using an in-line monitor. Becomes Further, by providing a boundary portion in which a large number of microchannels are formed so as to surround the supply port for the dispersed phase, it is possible to efficiently manufacture the microcapsules.

Next, constituent materials that can be used for producing the electrophoretic particle-encapsulating microcapsules of the present invention will be described. First, as the hydrophobic dispersion medium, for example, aromatic hydrocarbons such as benzene, toluene, xylene, phenylxylylethane, diisopropylnaphthalene, naphthene hydrocarbons, hexane, dodecylbenzene, cyclohexane, kerosene, paraffin hydrocarbons, etc. Of aliphatic hydrocarbons, chloroform, trichlorethylene,
Halogenated hydrocarbons such as tetrachloroethylene, trifluoroethylene, tetrafluoroethylene, dichloromethane and ethyl bromide, tricresyl phosphate, trioctyl phosphate, octyl diphenyl phosphate, phosphate esters such as tricyclohexyl phosphate, dibutyl phthalate ,
Phthalates such as dioctyl phthalate, dilauryl phthalate, dicyclohexyl phthalate, butyl oleate, diethylene glycol dibenzoate, dioctyl sebacate, dibutyl sebacate, dioctyl adipate, trioctyl trimellitate, acetyltriethyl citrate, maleic acid Carboxylic esters such as octyl, dibutyl maleate, ethyl acetate, isopropyl biphenyl, isoamyl biphenyl, chlorinated paraffin, diisopropyl naphthalene, 1,1-ditolylethane, 1,2-ditolylethane, 2,4-ditertiaryaminophenol, N , N-dibutyl-2-butoxy-5
-Tertiary octyl aniline and the like, but not limited thereto. In addition, these organic solvents can be used alone or in combination of two or more.

The above hydrophobic dispersion medium is colorless,
Any color can be used. When two types of particles such as positively charged particles and negatively charged particles or positively or negatively charged particles and uncharged particles are used as the electrophoretic particles, a colorless hydrophobic dispersion medium is used. When one kind of electrophoretic particles is used, a dispersion medium in which a dye is dissolved is used as a colored hydrophobic dispersion medium. Oil-soluble dyes are used as dyes that can be used at that time, and for example, Spirit Black (SB, SS
BB, AB), Nigrosine base (SA, SAP, SA
PL, EE, EEL, EX, EXBP, EB), oil yellow (105, 107, 129, 3G, GGS),
Oil Orange (201, PS, PR), Fast Orange, Oil Red (5B, RR, OG), Oil Scarlet, Oil Pink 312, Oil Violet # 730, Macrolex Blue RR, Sumiplast Green G, Oil Brown (GR, 416), Sudan Black X60, Oil Green (502, BG), Oil Blue (613, 2N, BOS), Oil Black (HBB, 860, BS), Varifast Yellow (1101, 1105, 3108, 4120), Varifast. Orange (3209, 3210), Bali Fast Red (1306, 1355, 2303, 3304,
3306, 3320), Bali First Pink 2310
N, Bali Fast Brown (2402, 3405),
Bali First Blue (3405, 1501, 160
3, 1605, 1607, 2606, 2610), Varifast Violet (1701, 1702), Varifast Black (1802, 1807, 380).
4, 3810, 3820, 3830) and the like can be used.

Inorganic pigment particles and organic pigment particles can be used as the electrophoretic particles that can be used in the method for producing the electrophoretic particle-containing microcapsules of the present invention. Examples of the inorganic pigment particles include lead white, zinc white,
Lithopone, titanium dioxide, zinc sulfide, antimony oxide,
Calcium carbonate, kaolin, mica, barium sulfate, gloss white, alumina white, talc, silica, calcium silicate, cadmium yellow, cadmium lipoton yellow, yellow iron oxide, titanium yellow, titanium barium yellow, cadmium orange, cadmium lipoton orange. , Molybdate orange, red iron oxide, red lead,
Silver vermilion, cadmium red, cadmium lipotone red,
Amber, brown iron oxide, zinc iron chrome brown, chrome green, chrome oxide, viridian, cobalt green, cobalt chrome green, titanium cobalt green, navy blue, cobalt blue, ultramarine blue, cerulean blue,
Cobalt aluminum chrome blue, cobalt violet, mineral violet, carbon black, iron black, manganese ferrite black, cobalt ferrite black, copper chrome black, copper chrome manganese black, titanium black, aluminum powder, copper powder, lead powder, bell powder, zinc Powder or the like can be used.

Examples of the organic pigment particles include fast yellow, disazo yellow, condensed azo yellow,
Anthrapyrimidine yellow, isoindoline yellow, copper azomethine yellow, quinophthaloin yellow,
Benzimidazolone yellow, nickel dioxime yellow, monoazo yellow lake, dinitroaniline orange, pyrazolone orange, perinone orange, naphthol red, toluidine red, permanent carmine, brilliant fast scarlet, pyrazolone red, rhodamine 6G lake, permanent red, resole red , Bon lake red, lake red, brilliant carmine, bordeaux 10B, naphthol red, quinacridone magenta, condensed azo red, naphthol carmine, perylene scar red, condensed azo scar red, benzimidazolone carmine, anthraquinonyl red, perylene red, perylene maroon , Quinacridone maroon, quinacridone scarred, quinacridone red, diketopiro Pyrrole red, benzimidazolone Brown, phthalocyanine green, Victoria blue lake, phthalocyanine blue, fast sky blue, alkali blue toe toner, indanthrone blue, Rhodamine B lake, methyl violet lake,
Dioxazine violet, naphthol violet and the like can be used.

Further, fine polymer particles can be used as the electrophoretic particles. The polymer fine particles can be produced by a conventionally known method, and examples thereof include a method using emulsion polymerization, a seed emulsion polymerization method, a soap-free polymerization method, a dispersion polymerization method, and a suspension polymerization method. But,
It is not limited to those produced by these methods.

Examples of the material of the polymer fine particles include styrene type, styrene-acrylic type, styrene-isoprene type, divinylbenzene type, methyl methacrylate type, methacrylate type, ethyl methacrylate type, ethyl acrylate type, n-butyl acrylate type, Acrylic acid type, acrylonitrile type, acrylic rubber-methacrylate type, ethylene type, ethylene-acrylic acid type, nylon type, silicone type, urethane type, melamine type, benzoguanamine type, phenol type, fluorine (tetrachloroethylene) type, vinylidene chloride type, Quaternary pyridinium salt system,
Examples thereof include synthetic rubber, cellulose, cellulose acetate, chitosan, calcium alginate, etc., but are not limited to these polymer materials. Further, the above-mentioned polymer fine particles used in the present invention may be dyed with a dye as required, or may be colored by containing pigment particles before use.

Further, these pigment components are preferably used not only as fine particles of the pigment alone but also in the state of being subjected to various surface treatments. As the surface treatment method in this case, various methods that are usually carried out for pigment particles can be applied. For example, a pigment surface coated with various compounds including a polymer, a titanate-based silane-based coating, etc. Examples thereof include those subjected to coupling treatment with various coupling agents such as the above, and those subjected to graft polymerization treatment. Further, these pigment particles can be used even in a state of being subjected to mechanochemical treatment, and composite particles formed between pigment particles or between polymer particles and hollow polymer particles, and various resins. It can also be used in the form of composite particles or the like formed between and.
The particle size of these electrophoretic particles is preferably 0.0.
The particle size is 1 to 10 μm, more preferably 0.05 to 5 μm, but is not limited to these particle sizes.

In the hydrophobic dispersion medium used in the electrophoretic particle-encapsulating microcapsules of the present invention, a dispersant is used for the purpose of controlling the charge amount of the electrophoretic particles or enhancing the dispersibility. It is preferable to contain one or more kinds. Examples of these dispersants include nonionic (nonionic) surfactants and anionic surfactants, cationic surfactants, and amphoteric surfactants that can be dissolved or mixed in a dispersion medium. The ionic surfactants may be used alone or in combination of two or more.

Examples of nonionic surfactants as these dispersants include polyoxyethylene nonylphenol ether, polyoxyethylene dinonylphenol ether, polyoxyethylene octylphenol ether, polyoxyethylene styrenated phenol, polyoxypolyoxyethylene bisphenol A. , Polyoxyethylene nonylphenyl ethers, polyoxyethylene octylphenyl ethers, nonylphenol ethoxylates and other polyoxyalkylene alkylphenol ethers.

Polyoxyalkylene ethers such as polyoxyethylene castor oil, polyoxyalkylene block polymer, polyoxyethylene cetyl ether, polyoxyethylene lauryl ether, polyoxyethylene oleyl ether, polyoxyethylene stearyl ether and polyoxypropylene ether.

Monool type polyoxyalkylene glycol, diol type polyoxyalkylene glycol, triol type polyoxyalkylene glycol, monool type block type polyalkylene glycol, diol type block type polyalkylene glycol, random type Glycols such as polyalkylene glycol.

Primary linear alcohol ethoxylates such as octylphenol ethoxylate, oleyl alcohol ethoxylate and lauryl alcohol ethoxylate, and alkyl alcohol ethers such as secondary linear alcohol ethoxylate and polynuclear phenol ethoxylate.

Polyoxyalkylene alkyl esters such as polyoxyethylene rosin ester, polyoxyethylene lauryl ester, polyoxyethylene oleyl ester and polyoxyethylene stearyl ester.

Sorbitan such as sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan dilaurate, sorbitan dipalmitate, sorbitan distearate, sorbitan sesquilaurate, sorbitan sesquipalmitate, sorbitan sesquistearate. Fatty acid esters.

Polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate,
Polyoxyethylene sorbitan dilaurate, polyoxyethylene sorbitan dipalmitate, polyoxyethylene sorbitan distearate, polyoxyethylene sorbitan sesquilaurate, polyoxyethylene sorbitan sesquipalmitate, polyoxyethylene sorbitan sesquistearate, etc. Oxyethylene sorbitan esters.

Saturated fatty acid methyl ester, unsaturated fatty acid methyl ester, saturated fatty acid butyl ester, unsaturated fatty acid butyl ester, saturated fatty acid stearyl ester,
Fatty acid esters such as unsaturated fatty acid stearyl ester, saturated fatty acid octyl ester, unsaturated fatty acid octyl ester, stearic acid polyethylene glycol ester, oleic acid polyethylene glycol ester and rosin polyethylene glycol ester. Fatty acids such as stearic acid, oleic acid, palmitic acid, lauric acid and myristic acid, and amidated compounds of these fatty acids. Polyoxyethylene alkylamines such as polyoxyethylene lauryl amine, polyoxyethylene alkyl amine, polyoxyethylene alkyl amine ether.

Higher fatty acid monoethanolamides such as lauric acid monoethanolamide and coconut fatty acid diethanolamide, higher fatty acid diethanolamides, polyoxyethylenestearic acid amide, coconut diethanolamide (1-2 type / 1-1 type), Amide compounds such as alkylalkylolamide and alkanolamides. R
_{- (CH 2 CH 2 O)} mH (CH 2 CH 2 O) nH, R-N
Alkanolamines represented by H—C ₃ H ₆ —NH ₂ [R = oleyl octyl dodecyl tetradecyl hexadecyl ochradecyl coconut, beef tallow, soybean, etc.].

R-NH ₂ [R = oleyl octyl dodecyl tetradecyl hexadecyl ocradidecyl.
Palm, beef tallow, soybean, etc.] primary amines. R1R
Secondary amines represented by 2-NH [R1, R2 = R = oleyl, octyl, dodecyl, tetradecyl, hexadecyl, ochradecyl, coconut, beef tallow, soybean, etc.]. R1R2
Tertiary amines represented by R3N [R1, R2, R3 = oleyl, octyl, dodecyl, tetradecyl, hexadecyl, ocradidecyl, coconut, beef tallow, soybean, etc.]. Various synthetic higher alcohols and various natural higher alcohols. Polymers such as acrylic acid-based compounds, polycarboxylic acid-based compounds, hydroxy fatty acid oligomers, modified hydroxy fatty acid oligomers, and oligomers can be used.

Examples of the anionic surfactants include polycarboxylic acid type polymer activators, polycarboxylic acid type anion activators, carboxylic acid salts such as special fatty acid soaps and rosin soaps. Castor oil sulfuric acid ester salt, lauryl alcohol sulfuric acid ester Na salt, lauryl alcohol sulfuric acid ester amine salt, natural alcohol sulfuric acid ester Na salt, higher alcohol sulfuric acid ester Na salt, and other alcoholic sulfuric acid ester salts, and lauryl alcohol ether sulfuric acid ester Amine salt, lauryl alcohol ether sulfate ester Na salt, synthetic higher alcohol ether sulfate ester amine salt, synthetic higher alcohol ether sulfate ester Na salt, alkyl polyether sulfate ester amine salt, alkyl polyether sulfate ester Na salt, natural alcohol EO (ethylene oxide) addition system sulfuric acid ester amine salt, natural alcohol EO (ethylene oxide)
Addition-based sulfate Na salt, synthetic alcohol EO (ethylene oxide) addition-based sulfate amine salt, synthetic alcohol EO (ethylene oxide) addition-based sulfate Na salt, alkylphenol EO (ethylene oxide) addition-based sulfate amine salt, alkylphenol EO (ethylene oxide) Addition system sulfate ester Na
Sulfuric acid such as salt, polyoxyethylene nonyl phenyl ether sulfuric acid ester amine salt, polyoxyethylene nonyl phenyl ether sulfuric acid ester Na salt, polyoxyethylene polycyclic phenyl ether sulfuric acid ester amine salt, polyoxyethylene polycyclic phenyl ether sulfuric acid ester Na salt, etc. Ester salts. Various alkyl allyl sulfonic acid amine salt, various alkyl allyl sulfonic acid Na salt, naphthalene sulfonic acid amine salt, naphthalene sulfonic acid Na salt, various alkyl benzene sulfonic acid amine salt, various alkyl benzene sulfonic acid Na salt, naphthalene sulfonic acid condensate, naphthalene sulfone Sulfonates such as acid formalin condensates.

Polyoxyethylene nonyl phenyl ether sulfonic acid amine salt, polyoxyethylene nonyl phenyl ether sulfonic acid Na salt, polyoxyethylene special allyl ether sulfonic acid amine salt, polyoxyethylene special allyl ether sulfonic acid Na salt, polyoxyethylene Polyoxyalkylene sulfonates such as amine salt of tridecyl phenyl ether sulfonate, Na salt of polyoxyethylene tridecyl phenyl ether sulfonate, amine salt of polyoxyethylene alkyl ether sulfonate, Na salt of polyoxyethylene alkyl ether sulfonate. Dialkyl sulfosuccinate amine salt,
Dialkyl sulfosuccinate Na salt, polycyclic phenyl polyethoxy sulfosuccinate amine salt, polycyclic phenyl polyethoxy sulfo succinate Na salt, polyoxyethylene alkyl ether sulfosuccinic acid monoester amine salt, polyoxyethylene alkyl ether sulfosuccinic acid Monosulfate sulfosuccinate ester salts such as Na salt.
Alkyl phosphate ester, alkoxyalkyl phosphate ester, higher alcohol phosphate ester, higher alcohol phosphate salt, alkylphenol type phosphate ester, aromatic phosphate ester, polyoxyalkylene alkyl ether phosphate ester, polyoxyalkylene alkyl allyl ether Phosphates such as phosphates and phosphates can be used.

Examples of the cationic surfactant include R
-N (CH₃) 3X [R = stearyl cetyl lauri
Le oleyl, dodecyl, coconut, soybean, beef tallow, etc./X=ha
[Rogen, amine, etc.]
Quaternary ammonium salts. Tetramethylamine salt,
Quaternary ammonium salts such as tetrabutylamine salt. (R
NH₃) (CH₃COO) [R = stearyl cetyl la
Uril, oleyl, dodecyl, palm, soybean, beef tallow, etc.]
Acetates represented. Lauryl dimethyl benzyl ammoni
Umium salt (halogen, amine salt, etc.), stearyl dimethyl
Benzyl ammonium salt (halogen, amine salt, etc.)
Decyldimethylbenzyl ammonium salt (halogen
Benzylamine-based quaternary ammonium salts such as min salts)
Kind. R (CH ₃) N (C₂H_FourO) mH (C₂H_FourO) n
X [R = stearyl / cetyl / lauryl / oleyl / de
Decyl, coconut, soybean, beef tallow, etc./X = halogen, amine
Etc.] Polyoxyalkylene-based quaternary ammonium
Murine salts can be used. As an amphoteric surfactant
For example, various betaine type surfactants, various imidazo
Phosphorus-based surfactant, β-alanine type surfactant, Polio
Butyl polyaminoethylglycine hydrochloride, etc. may be used.
You can In addition, various other protective colloid agents are used
be able to.

It is preferable that the above-mentioned display liquid for an electrophoretic display device can exert its effect in the range of 0 to 20 pS / cm.

The in-situ which has been conventionally used for producing the electrophoretic particle-containing microcapsules of the present invention.
It can be prepared by a u method, an interfacial polymerization method, a coacervation method, or the like, and in that case, as the wall material of the microcapsule, polyurethane, polyurea, polyurea-polyurethane, amino resin, polyamide, acrylate ester , Methacrylic acid ester, vinyl acetate, gelatin and the like. Further, the size of the microcapsules used in the present invention is 1 to 200 μm, more preferably 10 μm.
˜100 μm.

When manufacturing the microcapsules, it is first necessary to emulsify and disperse the hydrophobic dispersion in a hydrophilic medium. Water is most preferable as the hydrophilic medium, but in some cases, an organic solvent that dissolves in water, such as alcohols, may be added.

In the present invention, the dispersion stabilizer has a reactive functional group such as a carboxyl group, an acid anhydride group, a hydroxyl group, an amino group,
Contains at least one of an isocyanate group and a glycidyl group, and has a weight average molecular weight of 1,000 to 200,000.
It is characterized by using a dispersion stabilizer of 0. By containing a reactive functional group, it is possible to immediately react after emulsification with a microchannel type ejection device, and uniform droplets can be microencapsulated as they are. Further, when the weight average molecular weight of the dispersion stabilizer is 1000 or less, the droplets are likely to be miniaturized during the reaction, and the particle size distribution is likely to be broadened. Further, when the weight average molecular weight is 2,000,000 or more, the viscosity of the continuous phase becomes high, and as a result, the amount of the dispersion stabilizer used is limited and the reaction cannot be sufficiently performed.

Examples of such dispersion stabilizers include:
Water-soluble acrylic resin, water-soluble polyurethane resin, water-soluble polyester resin, water-soluble epoxy resin and the like,
Monomers may be selected and synthesized such that each resin skeleton contains at least one of a carboxyl group, an acid anhydride group, a hydroxyl group, an amino group, an isocyanate group, and a glycidyl group. Further, maleic acid copolymers (styrene, ethylene, propylene, methyl vinyl ether, vinyl acetate, isobutylene, copolymers of butadiene and the like with maleic acid), carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, gelatin, gum arabic starch derivative, Polyvinyl alcohol and the like can also be used.

Other nonionic surfactants, ionic surfactants and inorganic fine particles for controlling the emulsified state include, for example, talc, bentonite, organic bentonite, white carbon, colloidal silica and colloidal particles. Alumina, fine particle silica, calcium carbonate, calcium sulfate and the like can be used in combination.

A typical method for synthesizing the microcapsules used in the present invention is shown below. In the case of the in-situ method, the wall material is polyurethane, polyurea, polyurea-
Polyurethane, urea-formaldehyde resin, melamine-formaldehyde resin, acrylic acid ester, methacrylic acid ester, vinyl acetate and the like can be used. As the polyvalent isocyanate compound used when polyurethane, polyurea, or polyurea-polyurethane is used as the wall material, first, an organic compound having two or more isocyanate groups in the molecule is used. Examples of such a polyvalent isocyanate compound include m-phenylene diisocyanate, p-phenylene diisocyanate,
2,6-tolylene diisocyanate, 2,4-tolylene diisocyanate, naphthalene-1,4-diisocyanate,
Diphenylmethane-4,4'-diisocyanate, 3,3'-dimethoxy-4,4'-biphenyldiisocyanate, 3,3'-
Dimethyldiphenylmethane-4,4'-diisocyanate,
Xylylene-1,4-diisocyanate, 4,4'-diphenylpropane diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate, propylene-1,2-diisocyanate, butylene-1,2-diisocyanate, cyclohexylene-1,2-diisocyanate, Diisocyanates such as cyclohexylene-1,4-diisocyanate, triisocyanates such as p-phenylene diisothiocyanate, xylylene-1,4-diisothiocyanate and ethylidyne diisothiocyanate, 4,
Tetraisocyanates such as 4'-dimethyldiphenylmethane-2,2 ', 5,5'-tetraisocyanate can be utilized. As the polyvalent isocyanate compound, for example, an adduct of hexamethylene diisocyanate and hexanetriol, an adduct of 2,4-tolylene diisocyanate and prenzcatechol, an adduct of tolylene diisocyanate and hexane triol, tolylene diisocyanate and trimethylol. Polyvalent isocyanate prepolymers such as propane adducts, xylylene diisocyanate and trimethylol propane adducts, hexamethylene diisocyanate and trimethylol propane adducts, and the like can also be utilized.

Further, as a polyvalent isocyanate compound,
A prepolymerized compound can also be used. Further, two or more of the above-mentioned substances can be used in combination.
On the other hand, as the wall film forming substance having reactivity with the polyvalent isocyanate compound, polyhydric alcohols, hydroxypolyesters, hydroxypolyalkylene ethers, alkylene oxide adducts of polyvalent amines, polyvalent amines, etc. Examples thereof include substances having two or more active hydrogens.

The above polyhydric alcohols may be aliphatic, aromatic or alicyclic and include, for example, catechol, resorcinol, 1,2-dihydroxy-4-methylbenzene and 1,3-dihydroxy-5. -Methylbenzene,
3,4-dihydroxy-1-methylbenzene, 3,5-dihydroxy-1-methylbenzene, 2,4-dihydroxyethylbenzene, 1,3-naphthalenediol, 1,5-naphthalenediol, 2,7-naphthalenediol, 2,3-naphthalenediol, o, o'-biphenol, p, p '
-Biphenol, bisphenol A, bis- (2-hydroxyphenyl) methane, xylylenediol, ethylene glycol, 1,3-propylene glycol, 1,4-butylene glycol, 1,5-pentanediol, 1,6-hexanediol , 1,7-heptanediol, 1,8-octanediol, 1,1,1-trimethylolpropane, hexanetriol, pentaerythritol, glycerin,
Sorbitol and the like can be used.

The hydroxypolyalkylene ethers include the above polyhydric alcohols and polycarboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, isophthalic acid, terephthalic acid and gluconic acid. The resulting hydroxypolyesters may be mentioned. Examples of the hydroxypolyalkylene ethers include hydroxypolyalkylene ethers which are condensation products of the above polyhydric alcohols and alkylene oxides such as ethylene oxide, propylene oxide and butylene oxide. Examples of the alkylene oxide adduct of polyvalent amine include o-phenylenediamine, p-phenylenediamine, diaminonaphthalene, ethylenediamine, 1,3-propylenediamine and diethylenetriamine. Triethylenetetramine, 1,6
An example is one in which at least one or more of the hydrogens of the amino group of a polyvalent amine such as hexamethylenediamine is replaced with the above-mentioned alkylene oxide.

Examples of the polyvalent amines include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, 1,6-hexamethylenediamine, 1,8-
Octamethylenediamine, 1,12-dodecamethylenediamine, o-phenylenediamine, p-phenylenediamine, m-phenylenediamine, o-xylylenediamine, p-xylylenediamine, m-xylylenediamine, menthanediamine, bis ( 4-amino-3-methylcyclohexylnomethane, isophoronediamine, 1,3
-Diaminocyclohexane, spiro acetal-based diamine and the like can be used. Further, water can also be used as a wall film forming substance having reactivity with polyvalent isocyanate.

Basically, it comprises the following steps. An aqueous solution containing a dispersion stabilizer is prepared. The amount of dispersion stabilizer is
It is suitable to use 0.2 to 10 parts by weight, preferably 0.5 to 5 parts by weight, relative to 100 parts by weight of water. Next, a hydrophobic dispersion liquid is prepared by mixing electrophoretic particles, a polyvalent isocyanate compound, a polyhydric alcohol and, in some cases, a polyvalent amine with the hydrophobic dispersion medium. This hydrophobic dispersion is emulsified and dispersed in the aqueous dispersion stabilizer solution prepared in the above step using the microchannel capsule manufacturing apparatus used in the present invention. Here, the amount of the electrophoretic particles used is 0.1 to 100 parts by weight of the hydrophobic dispersion.
20 parts by weight, preferably 1 to 10 parts by weight. The amount of the polyvalent isocyanate compound used is in the range of 1 to 50 parts by weight, preferably 5 to 20 parts by weight, based on 100 parts by weight of the hydrophobic dispersion. The amount of polyhydric alcohol or polyhydric amine used is the same as the above-mentioned hydrophobic dispersion 1.
1 to 50 parts by weight, preferably 5 to 100 parts by weight
-20 parts by weight.

The obtained emulsified dispersion is heated to a predetermined temperature to react the polyvalent isocyanate with the polyhydric alcohol or the polyvalent amine to obtain the desired microcapsules.

When acrylic acid ester, methacrylic acid ester, vinyl acetate or the like is used as the wall material, examples of the radical polymerizable monomer usable in the present invention include styrene, α-methylstyrene,
Aromatic monomers such as p-methylstyrene, t-butylstyrene, chlorostyrene, benzyl acrylate, benzyl methacrylate and vinyltoluene. Methyl acrylate, ethyl acrylate, isopropyl acrylate,
N-Butyl acrylate, isobutyl acrylate, n-amyl acrylate, isoamyl acrylate, n acrylate
-Aryl alkyl esters such as hexyl, 2-ethylhexyl acrylate, n-octyl acrylate, decyl acrylate, dodecyl acrylate. Methyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-amyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, decyl methacrylate, dodecyl methacrylate, etc. Methacrylic acid alkyl esters. Hydroxy group-containing monomers such as hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, and hydroxypropyl methacrylate. N-methylol acrylamide, N
-N-substituted acrylic and methacrylic monomers such as butoxymethyl acrylamide, N-methylol methacrylamide and N-butoxymethyl methacrylamide.
Acrylic acid, methacrylic acid, itaconic acid, maleic acid,
Carboxyl group-containing monomers such as polymerizable unsaturated carboxylic acids such as fumaric acid and crotonic acid and their anhydrides. One or two of epoxy group-containing monomers such as glycidyl acrylate and glycidyl methacrylate, and acrylonitrile, methacrylonitrile, crotonnitrile, vinyl acetate, vinyl chloride, vinylidene chloride, etc.
More than one species can be selected.

Further, in the present invention, together with the above-mentioned radical-polymerizable monomer, polyfunctional and accordingly crosslinkable monomers such as methylenebisacrylamide, divinylbenzene, tripropyleneglycol diacrylate, bisphenol A diester, etc. Glycidyl ether diacrylate, trimethylolpropane triacrylate, acrylated cyanurate and the like can also be used.

When the above radical polymerizable monomer is used, the radical polymerization initiator usable in the present invention includes organic peroxides such as lauroyl peroxide, benzoyl peroxide, methyl ethyl ketone peroxide, cyclohexanone peroxide, and 2 2,2-bis (t-butylperoxy) valate, di-t-butylperoxide, dicumylperoxide, octanoylperoxide, etc. and azo compounds such as 2,2-azobis (2,4-dimethylvalero) Nitrile), 2,2-azobis (2-methylbutyronitrile), 1,1-azobis (cyclohexyl-1-carbonitrile), VA-061, V
A-080, VR-110, V-601 (all are Wako Pure Chemical Industries, Ltd.) etc. can be used. Inorganic peroxides such as ammonium peroxide and sodium peroxide can also be used. These initiators may be used alone, or may be used in a redox type by being used in combination with a reducing agent such as Rongalit. Further, as a chain transfer agent for adjusting the molecular weight, mercaptans such as octyl thioglycolate, methoxybutyl thioglycolate, octyl mercaptopropionate, methoxybutyl mercaptopropionate, and stearyl mercaptan, and α-methylstyrene dimer should be used. You can

In the step, electrophoretic particles, radical polymerizable monomers, radical polymerization initiators,
Depending on the case, a hydrophobic dispersion liquid is prepared by mixing a chain transfer agent or the like. Similar to the above, this hydrophobic dispersion is emulsified and dispersed in an aqueous dispersion stabilizer solution using the microchannel capsule manufacturing apparatus used in the present invention. Here, the amount of the radical-polymerizable monomer used is in the range of 1 to 90 parts by weight, preferably 10 to 50 parts by weight, based on 100 parts by weight of the hydrophobic dispersion liquid. The amount of the radical polymerization initiator used is not particularly limited, but is usually 0.1 to 10 parts by weight, preferably 0.1 to 5 parts by weight with respect to 100 parts by weight of the radical polymerizable monomer. It is a range. in-sit
In the case of radical polymerization by the u method, it is possible not to mix the radically polymerizable monomer and the radical polymerization initiator into the hydrophobic dispersion medium, but to dissolve them in water and polymerize them. In this case, it is preferable to use the radically polymerizable monomer and the radical polymerization initiator to be used in a range that dissolves in water. The obtained emulsified dispersion is heated to a predetermined temperature to initiate radical polymerization to obtain the target microcapsules.

When an amino resin is used as the wall material, the components usable in the present invention are:
For example, melamine / formaldehyde prepolymer, urea /
Formaldehyde prepolymer, alkylated methylolurea alkylated methylolmelamine, N-alkylmelamine / formaldehyde prepolymer, guanamine / formaldehyde prepolymer, alkylurea / formaldehyde prepolymer, alkyleneurea / formaldehyde prepolymer, etc. are used. be able to.

In the step, electrophoretic particles are mixed with a hydrophobic dispersion medium to prepare a hydrophobic dispersion liquid. Similar to the above, this hydrophobic dispersion is emulsified and dispersed in an aqueous dispersion stabilizer solution using the microchannel capsule manufacturing apparatus used in the present invention. The amino resin component is used in an amount of 1 to 200 parts by weight, preferably 10 to 60 parts by weight, based on 100 parts by weight of the hydrophobic dispersion. When the amino resin component is a urea / formaldehyde prepolymer, this component may be gradually or once added to the system, or the raw material urea may be previously dissolved in an aqueous medium, and then gradually or once. Formaldehyde may be added to the system. The microencapsulation reaction is preferably under acidic conditions, i.e.
pH is 2.0 to 6.8, more preferably 3.0 to 6.0.
Done in. The conditions of the system may be appropriately adjusted depending on the kind of the amino resin component used. For example, in the case of melamine / formaldehyde prepolymer or alkylated methylol melamine, the pH is 4.0 to 5.5, and in the case of urea / formaldehyde prepolymer. Is preferably pH 2.0 to 4.5. System p
By adjusting H to 3.0 to 6.8 and heating to a predetermined temperature, polycondensation is performed on the surface of the dispersed particles of the hydrophobic substance to obtain the target microcapsules. The amino resin component is an initial condensate of formaldehyde and urea, melamine, etc., and can be produced by a conventional method.

Next, in the case of the interfacial polymerization method, polyurethane, polyurea, polyurea-polyurethane, polyamide or the like can be used as the wall material. In the interfacial polymerization method, a hydrophobic monomer is added to a hydrophobic dispersion medium, the hydrophobic dispersion is emulsified and dispersed in water, and then a hydrophilic monomer is added to cause polymerization on the oil droplet surface. As the polyvalent isocyanate compound used when polyurethane, polyurea, or polyurea-polyurethane is used as the wall material, the polyvalent isocyanate, polyvalent alcohol, and polyvalent amine shown by the in-situ method can be used. . Generally, polyvalent isocyanate is used as the hydrophobic monomer, and polyhydric alcohol or polyvalent amine is used as the hydrophilic monomer. The amounts of these monomers used are the same as the amounts shown by the in-situ method.

When polyamide is used as the wall material, polybasic acid halide may be used as the hydrophobic monomer and polyvalent amine may be used as the hydrophilic monomer instead of the polyvalent isocyanate. As the polybasic acid halide, sebacoyl chloride, terephthaloyl chloride or the like can be used.

Next, in the case of the coacervation method, the well-known gelatin-acacia complex coacervation method can be used. In addition to gum arabic, gelatin can react with anions such as sodium alginate, carrageenan, carboxymethylcellulose, agar, polyvinylbenzenesulfonic acid, maleic anhydride copolymer, and other surfactants. After coacervating, it is common to cure with formaldehyde. As described above, when the electrophoretic particle-containing microcapsules produced by various methods and materials are used as a display material, high-definition and high-contrast display can be performed.

In the present invention, there is provided a method of reversibly displaying an electro-responsive property using the above-described electrophoretic particle-containing microcapsules. The electrophoretic display medium may have, for example, at least one of them. At least one of the pair of transparent substrates has an electrode on one surface, and the electrode surface is connected to the one substrate via a spacer /
Alternatively, an electrophoretic reversible display medium in which spaces formed by facing each other without being interposed are filled with the electrophoretic particle-encapsulating microcapsules of the present invention. Alternatively, at least one of the pair of substrates, at least one of which is transparent, has an electrode on one surface, and the electrode surface is arranged to face the one substrate with or without a spacer. An electrophoretic reversible display medium in which the space formed in 1 is discontinuously divided by a matrix material and filled with the electrophoretic particle-encapsulating microcapsules of the present invention. Alternatively, an electrophoretic reversible display medium in which a coating layer made of the electrophoretic particle-encapsulating microcapsules of the present invention and a matrix material is formed on the electrode surface side of a transparent or opaque substrate having an electrode on one surface. Alternatively, a coating layer composed of the electrophoretic particle-encapsulating microcapsules of the present invention and a matrix material is formed on the electrode surface side of a transparent or opaque substrate having an electrode on one surface, and an overcoat is formed on the coating layer. Examples include electrophoretic reversible display media provided with layers. In addition, the substrate in the present invention indicates both a substrate having an electrode surface and a substrate not having an electrode surface.

FIG. 1 shows that the space formed by a pair of electrode substrates via a spacer is filled with the electrophoretic particle-encapsulating microcapsules of the present invention as a reversible display recording layer by using a matrix material, and electrophoresis is performed. A display medium is manufactured. The reversible display recording layer is prepared by dissolving, dispersing, suspending or emulsifying the electrophoretic particle-containing microcapsules of the present invention and a matrix material as a coating liquid, and the resulting coating liquid is wire bar coat, roll coat, It can be obtained by coating and drying on the electrode plate by a method such as blade coating, dip coating, spray coating, spin coating, or gravure coating. In this case, examples of the electrode plate include an electrode formed by forming a conductive film such as ITO on a glass plate or a plastic film, an electrode formed by forming a conductive metal film such as aluminum, copper, or gold. .

As the matrix material, the same material as the wall material of the microcapsule, or polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinyldene chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl butyral, polyvinyl alcohol, poly Ethylene oxide, polypropylene oxide, ethylene-vinyl alcohol copolymer, polyacetal, acrylic resin, methyl cellulose, ethyl cellulose, phenol resin,
Fluorine resin, silicone resin, diene resin, polystyrene-based thermoplastic elastomer, polyolefin-based thermoplastic elastomer, polyurethane-based thermoplastic elastomer,
Polyester thermoplastic elastomer, polyphenylene ether, polyphenylene sulfide, polyether sulfone, polyether ketone, polyarylate, aramid, polyimide, poly-p-phenylene, poly-p-xylene, poly-p-phenylene vinylene, polyhydantoin, polyparaban One or more materials selected from acids, polybenzimidazoles, polybenzothiazoles, polybenzooxadiazoles, polyquinoxalines, the above-mentioned thermosetting resins or active energy ray-curing resins, or mixtures thereof can be used. .

As the material for forming the overcoat layer, the material for forming the above matrix material can be used. The overcoat layer comprises a medium for dissolving, dispersing, suspending or emulsifying these materials, a curing agent, a protective layer material composition containing a catalyst and / or a cocatalyst, a wire bar coat, a roll on the display layer. Coat, blade coat, dip coat, spray coat, spin coat,
Alternatively, it is formed by a coating method such as a gravure coating, a sputtering method, a chemical vapor deposition method, or the like. The thickness of the overcoat layer is preferably as thin as possible within the range of having a function of protecting the recording layer, and is about 0.1 to 100 μm.
m, and more preferably 0.3 to 30 μm.

[0068]

EXAMPLES The present invention will be described below with reference to examples. In addition, "part" and "%" in an example show "weight part" and "weight%", respectively.

(Example 1) Dispersed phase 1: 150 parts by weight of paraffin hydrocarbon isoper (manufactured by Exxon Corporation) was dissolved in 1 part by weight of oil-soluble dye Oil Blue to give a colored hydrophobic dispersion medium. I prepared. Titanium dioxide (Ti-PURE R104 manufactured by DuPont) as electrophoretic particles is added to the hydrophobic dispersion medium.
5 parts by weight, OLOA4382 (made by Chevron) as a dispersant
0.1 part was added and dispersed for 10 minutes using an ultrasonic disperser to prepare a hydrophobic dispersed phase solution. Electrical conductivity is 5 pS / c
It was m.

Continuous phase 1: An aqueous solution was prepared by dissolving 20 parts by weight of a partially neutralized styrene-maleic anhydride resin having a weight average molecular weight of 70,000 as a dispersion stabilizer in 1500 parts by weight of ion-exchanged water. Using the above-mentioned dispersed phase 1 and continuous phase 1, and using the microchannel type capsule manufacturing apparatus used in the present invention (aspect ratio of plate holes is 4, short side length is 20 μm), the driving pressure is 8 kPa, and microcapsule manufacturing is tried. It was As a result, a microcapsule dispersion liquid containing electrophoretic particles having a particle size distribution of 70 to 80 μm was obtained. To 1000 parts by weight of this dispersion, a mixture of 90 parts by weight of 37% formalin, 30 parts by weight of melamine, and 240 parts by weight of ion-exchanged water was added, and the pH was adjusted to 9.0 using a caustic soda aqueous solution under weak stirring. Then, the mixture was reacted at 60 ° C. for 20 minutes to reinforce the capsule wall with a melamine / formaldehyde condensate to obtain electrophoretic particle-encapsulating microcapsules 1 having a particle size distribution of 70 to 80 μm.

Then, 20 g of the obtained electrophoretic particle-encapsulating microcapsule-1 was added to 80 g of a 10% by weight polyvinyl alcohol aqueous solution to prepare a dispersion coating solution. Using an applicator with a gap of 100 μm,
Coating on a glass plate with an ITO film (on the ITO film) and drying to form a microcapsule coating film containing electrophoretic particles,
Further, a glass plate with an ITO film (ITO film on the side of the microcapsule coating film) was placed thereon to prepare an electrophoretic display medium. When the electrophoretic display medium thus prepared is connected to a DC power source, the direction of the electric field is switched at a rectangular frequency of 10 Hz, and a voltage of ± 100 V is applied, whereby titanium dioxide particles are electrophoresed on the upper electrode. It was possible to display white (the electric field of the upper electrode was positive) and blue (the electric field of the lower electrode was positive) when the titanium dioxide particles were electrophoresed on the lower electrode. In order to investigate the display performance of the obtained electrophoretic display medium, Pho manufactured by Otsuka Electronics
Using talMCPD-1000, white display,
The reflected light intensity at the time of blue display was measured in the visible light region by irradiation at 45 ° and received at 0 °, and the ratio of the reflectances of both display colors was obtained as the contrast. As a result, the contrast is 1 (blue):
It was 6.2 (white). By the way, the contrast between the solid blue print on the newspaper and the white background of the newspaper is 1
(Blue): 7.4 (white), which proved that the display contrast of the electrophoretic display medium was high.

Example 2 Dispersed phase 2: 150 parts by weight of paraffin hydrocarbon isoper (manufactured by Exxon Corporation) was used as electrophoretic particles of titanium dioxide (manufactured by DuPont, Ti-PURE®).
101) 5 parts by weight, 5 parts by weight of titanium black (black titanium manufactured by Ako Kasei) and 0.1 part of OLOA4382 (manufactured by Chevron Co.) as a dispersant were added, and dispersed by using an ultrasonic disperser for 10 minutes to give a hydrophobic dispersion. A phase solution was prepared. Electric conductivity is 3p
It was S / cm. Continuous phase 2: An aqueous solution was prepared by dissolving 20 parts by weight of an ethylene-maleic anhydride resin having a weight average molecular weight of 70,000 as a water-soluble polymer in 1500 parts by weight of ion-exchanged water. Then, using the dispersed phase 2 and the continuous phase 2 in the same manner as in Example 1 (aspect ratio of plate holes of microchannel capsule manufacturing apparatus is 8, short side length is 15 μm), and particle size distribution is 70 to 80 μm. The electrophoretic particle-encapsulating microcapsules 2 of Example 1 were obtained, and an electrophoretic display medium was prepared and the reflection contrast of the medium was evaluated by the same method. In this embodiment,
Titanium dioxide particles (Ti-PURE R-101)
Electrophoresis was performed on the negative electrode side, and titanium black particles were electrophoresed on the positive electrode side, and white and black display was possible. The reflectance contrast of both display colors was 1 (black): 8.8 (white). By the way, the contrast between the black solid print on the newspaper and the white background of the newspaper is 1 (black): 10.1.
It was (white), and it was proved that the display contrast of the electrophoretic display medium was high.

Comparative Example 1 A hydrophobic dispersion medium colored by dissolving 1 part by weight of oil blue, an oil-soluble dye, in 150 parts by weight of paraffin hydrocarbon isoper (manufactured by Exxon Corporation) was prepared. Titanium dioxide (manufactured by DuPont, Ti-PUR) as electrophoretic particles was added to the hydrophobic dispersion medium.
5 parts by weight of ER104) and 0.1 part of OLOA4382 (manufactured by Chevron) as a dispersant were added and dispersed for 5 minutes using an ultrasonic disperser to prepare a hydrophobic dispersion solution. On the other hand, an aqueous solution was prepared by dissolving 20 parts by weight of a partially neutralized styrene-maleic anhydride resin having a weight average molecular weight of 70,000 as a water-soluble polymer in 1500 parts by weight of ion-exchanged water. Next, the previously prepared hydrophobic dispersion was added to this aqueous solution, and the mixture was emulsified and dispersed for 5 minutes at 400 rpm using a stirring device equipped with a screw blade. Separately, a mixture of 150 parts by weight of 37% formalin, 50 parts by weight of melamine, and 400 parts by weight of ion-exchanged water was stirred and pH was adjusted using a caustic soda aqueous solution.
It was adjusted to 9.0 and reacted at 60 ° C. for 20 minutes to obtain a transparent melamine / formaldehyde condensate. This reaction liquid is added to the previous emulsified dispersion liquid that has been placed in the reaction kettle, and the temperature is 50 ° C.
The reaction was carried out for 3 hours by the in-situ method. The particle size distribution of the obtained electrophoretic particle-containing microcapsules is 5 to 12.
It was 0 μm. Using these microcapsules as they were, an electrophoretic display medium was prepared in the same manner as in Example 1, and the reflected light intensities at the time of white display and blue display were respectively obtained as the contrast. As a result, the contrast was 1 (blue):
It was 2.7 (white).

(Comparative Example 2) The microcapsules obtained in Comparative Example 1 had a particle size distribution of 70 to 8 using a sieving type classifier.
The particles were classified to have a size of 0 μm, an electrophoretic display medium was prepared in the same manner using the particles, and the reflected light intensities at the time of white display and blue display were obtained as contrasts. As a result, the contrast was 1 (blue): 5 It was 0.7 (white). Although better results were obtained than in Comparative Example 1, it was difficult to completely separate microcapsules having a particle size of 70 μm or less and 80 μm or more, and the same contrast as in Example 1 could not be obtained.

[0075]

EFFECTS OF THE INVENTION According to the present invention, it is possible to make the particle size of the microcapsules uniform, and it is also possible to make the content ratio of the electrophoretic particles contained therein uniform. A high-contrast display is possible in an electrophoretic display device using the.

[0076]

[Brief description of drawings]

FIG. 1 shows a schematic view of an electrophoretic display medium using the electrophoretic particle dispersion-containing microcapsules of the present invention.

[0003]

[Explanation of symbols]

1. substrate 2. electrode 3. Transparent electrode 4. Microcapsule filling layer (matrix layer) 5. Microcapsules containing electrophoretic particle dispersion 6. spacer

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4G005 AA01 AB15 BA02 BA03 BA05                       BB06 BB09 DA12X DA20X                       DC26Y DC41Y DC42Y DC46Y                       DD28Z DD34Z DD35Z DD38Z                       EA09

Claims (11)

[Claims] 1. A continuous phase containing electrophoretic particles dispersed in a hydrophobic dispersion medium through the pores of a plate having a large number of pores in contact with a flowing continuous phase made of a hydrophilic medium containing a dispersion stabilizer. A microcapsule containing electrophoretic particles, characterized in that it is discharged into a phase, brought into contact with the continuous phase, emulsifies the dispersed phase, and then forms a microcapsule wall between the dispersed phase and the continuous phase. Capsule manufacturing method. 2. The plate has an aspect ratio of 2-10.
The method for producing microcapsules containing electrophoretic particle dispersion liquid according to claim 1, wherein 3. The method for producing microcapsules containing electrophoretic particle dispersion liquid according to claim 1, wherein the holes of the plate have a short side length of 1 to 50 μm. 4. The method of producing microcapsules containing electrophoretic particle dispersion liquid according to claim 1, wherein the holes of the plate are rectangular. 5. The dispersion stabilizer contains at least one of a carboxyl group, an acid anhydride group, a hydroxyl group, an amino group, an isocyanate group, and a glycidyl group as a reactive functional group, and has a weight average molecular weight of 1000 to 1000. It is 2000000, The manufacturing method of the electrophoretic particle dispersion liquid containing microcapsule in any one of Claims 1-4. 6. The particle size of the microcapsules is 1 to 500 μm.
The method for producing electrophoretic particle-dispersed liquid-containing microcapsules according to any one of claims 1 to 5, wherein m is m. 7. The method for producing microcapsules containing electrophoretic particle dispersion liquid encapsulation liquid according to claim 1, wherein the dispersed phase contains one or more kinds of dispersants. 8. The display liquid for an electrophoretic display device according to claim 1, wherein the dispersed phase has an electric conductivity in the range of 0 to 20 pS / cm. 9. The electrophoretic particle dispersion liquid encapsulation liquid according to claim 1, wherein the electrophoretic particles include at least two kinds of colored particles having different color tones and electrophoretic properties. Manufacturing method of microcapsules. 10. The method for producing a microcapsule containing an electrophoretic particle dispersion liquid according to any one of claims 1 to 9,
Microcapsules containing electrophoretic particle dispersion liquid produced. 11. The electrophoretic particle-dispersed liquid-encapsulating microcapsule according to claim 10, at least one of which is transparent.
A reversible display medium sandwiched between a pair of opposing electrodes.