JP2014215555A - Image display medium and manufacturing method thereof, image display unit, electronic equipment, exhibition medium and card medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image display medium capable of preventing fixation of electrophoretic particles, and a manufacturing method thereof.SOLUTION: A manufacturing method of an image display medium includes: a surface layer formation process for forming a surface layer through applying, on a pair of substrates at least one of which has light transmissivity, a composition containing a polymer having a crosslinking group and a crosslinking agent at a quantity equal to or larger than the crosslinking group in the polymer, to perform deposition and crosslinking; and a liquid dispersion encapsulation process for encapsulating liquid dispersion of particles for display containing electrophoretic particles configured to move according to an electric field, and at least a dispersant configured to disperse the electrophoretic particles, between the pair of substrates on which the surface layer is formed.

Description

  The present invention relates to an image display medium and a method for manufacturing the same, and an image display apparatus, electronic apparatus, exhibition medium, and card medium using the same.

  Conventionally, as a display technology that can be repeatedly rewritten, a display technology using electrophoresis has been proposed. As such a display technology, for example, a dispersion liquid is sealed between a pair of substrates. There is known an image display device having a configuration in which particles composed of charged particles are dispersed.

  In such an image display device, by applying a voltage according to an image between the substrates, it is possible to move the charged particles and display the image as the color contrast of the particles (for example, Patent Documents). 1-2).

  In relation to the display device as described above, a container having a coating film covering at least a part of the inner wall surface, a fluid medium filled in the container and in contact with the coating film, and particles dispersed in the fluid medium, A display device is disclosed in which the coating film is made of a cured product of a curable resin composition containing a main agent and an isocyanate curing agent (see, for example, Patent Document 3).

  Further, a technique for suppressing adhesion of particles to the wall surface of electrophoresis particles composed of crosslinked polymer fine particles is disclosed (for example, see Patent Document 4).

  In addition to the above, display particles formed by fixing charged particles obtained by oxidizing unreacted groups in resin fine particles containing a crosslinked resin are sealed between two substrates, and an electric field is applied between the substrates. A technique for displaying image information by moving particles for use is disclosed (for example, see Patent Document 5).

JP 2004-333589 A JP-A-2005-107146 JP 2005-215622 A JP 2003-161965 A JP 2013-7924 A

  Conventionally, in a display device using colored particles, a technique for introducing a strong cross-linked structure from the viewpoint of improving stability has been studied. As an example, a form in which a film (layer) crosslinked using a polymer containing a crosslinking group and a crosslinking agent is provided is known. However, since it is usually sufficient to form a crosslinked structure for strengthening the film, the amount of the crosslinking agent is small relative to the crosslinking group such as a hydroxyl group in the polymer so that a crosslinking agent such as an isocyanate compound does not remain after the reaction. It is not considered to add an amount of cross-linking agent, which is generally an amount that can be excessive relative to the amount of cross-linking groups in the polymer. Therefore, a crosslinking group such as a hydroxyl group tends to remain in the polymer. For example, since hydroxyl groups tend to interact with particles, in a system where there are few crosslinking agents and hydroxyl groups are likely to remain, the remaining hydroxyl groups may act on the particles and cause sticking.

  Further, Patent Document 3 which forms a film of a cured product of a curable resin composition using a main agent and an isocyanate curing agent has an isocyanate curing agent and a fluid medium so that the difference in SP value is 4.0 or more. Focusing on selecting a combination with the above, it is intended to prevent deterioration of display quality over time by suppressing swelling and elution of the coating, and it is not planned to suppress the fixation of colored particles.

On the other hand, Patent Document 4 relates to a technique for suppressing the adhesion of particles to the wall surface, but pays attention to the fixation of particles by hydrogen bonding on the particle surface, and the particles are composed of a crosslinked polymer, that is, on the substrate side. Instead, it tries to suppress adhesion on the particle side.
Similarly, Patent Document 5 uses a cross-linked resin for the chargeable particles constituting the display particles, and applies the cross-linking technique not to the substrate side but to the particle side.

  The present invention has been made in view of the above situation, and an image display medium in which the fixation of migrating particles (for example, colored particles) is suppressed, a method for manufacturing the same, and an image display device excellent in image display characteristics, An object is to provide an electronic device, an exhibition medium, and a card medium, and to achieve the object.

  In the present invention, when an unreacted crosslinkable functional group such as a hydroxyl group is present on the surface of a substrate such as an electrode surface in contact with the migrating particle, this functional group tends to act on the migrating particle to induce fixation. The inventors have obtained knowledge that a composition in which functional groups such as hydroxyl groups do not easily remain is effective in suppressing sticking of particles, and has been achieved based on such knowledge.

Specific means for achieving the above-described problems are as follows.
<1> On at least one of a pair of substrates having at least one light-transmitting property, a polymer having a crosslinking group and a composition containing an equal amount or more of a crosslinking agent with respect to the crosslinking group in the polymer are applied. A surface layer forming step of forming a surface layer by forming a film and cross-linking, and migrating particles moving according to an electric field and at least the migrating particles are dispersed between the pair of substrates on which the surface layer is formed And a dispersion encapsulating step of encapsulating a display particle dispersion containing the dispersion medium.
<2> The surface layer forming step is the method for producing an image display medium according to <1>, wherein the surface layer is formed by crosslinking by heating.
<3> The surface layer forming step forms the surface layer by crosslinking with the ratio of the amount of the crosslinking agent to the amount of the crosslinking group in the polymer being 1.2 (120 mol%) or more in terms of molar ratio <1> or <2> A method for producing an image display medium according to <2>.
<4> In the surface layer forming step, the surface layer is formed by crosslinking with the ratio of the amount of the crosslinking agent to the amount of the crosslinking group in the polymer being 1.3 (130 mol%) or more in terms of molar ratio. <3> A method for producing an image display medium according to any one of <3>.
<5> The method for producing an image display medium according to any one of <1> to <4>, wherein the crosslinking group of the polymer is a hydroxyl group.
<6> The method for producing an image display medium according to any one of <1> to <5>, wherein the crosslinking group of the crosslinking agent is an isocyanate group.
<7> a pair of substrates at least one of which has translucency;
Formed by forming a film using at least one of the substrates, a polymer having a crosslinking group, and a composition containing a crosslinking agent in an equal amount or more with respect to the crosslinking group in the polymer, followed by crosslinking. And a display particle dispersion liquid including a migrating particle sealed in contact with the surface layer between a pair of substrates and moving in response to an electric field, and a dispersion medium that disperses at least the migrating particle. Image display medium.
<8> The image display medium according to <7>, wherein the polymer crosslinking group is a hydroxyl group.
<9> The image display medium according to <7> or <8>, wherein the crosslinking group of the crosslinking agent is an isocyanate group.
<10> Image display manufactured by the method for manufacturing an image display medium according to any one of <7> to <9> or an image display medium according to any one of <1> to <6> Medium,
An electric field applying means for applying an electric field for moving the migrating particles between a pair of substrates;
It is an image display apparatus provided with.
<11> An image display manufactured by the method for manufacturing an image display medium according to any one of <7> to <9> or an image display medium according to any one of <1> to <6>. An electronic device provided with a medium.
<12> An image display manufactured by the method for manufacturing an image display medium according to any one of <7> to <9> or an image display medium according to any one of <1> to <6>. An exhibition medium provided with a medium.
<13> Image display manufactured by the method for manufacturing an image display medium according to any one of <7> to <9> or an image display medium according to any one of <1> to <6> A card medium provided with a medium.

ADVANTAGE OF THE INVENTION According to this invention, the image display medium in which adhesion | attachment of migrating particle (for example, colored particle) was suppressed and its manufacturing method are provided. Also,
ADVANTAGE OF THE INVENTION According to this invention, the image display apparatus excellent in the display characteristic of an image, an electronic device, the medium for exhibition, and a card medium are provided.

1 is a schematic configuration diagram of an image display device according to an embodiment of the present invention. FIG. 4 is a diagram schematically illustrating a relationship between an applied voltage and a migration amount (display density) of electrophoretic particles in the image display device according to the embodiment of the present invention. It is explanatory drawing which shows typically the voltage aspect applied between the board | substrates of the image display apparatus which concerns on this embodiment, and the movement aspect of an electrophoretic particle.

  Hereinafter, an image display medium and a manufacturing method thereof according to the present invention will be described in detail, and an image display device, an electronic apparatus, an exhibition medium, and a card medium using the image display medium will be described in detail.

  In this specification, “(meth) acryl” includes both “acryl” and “methacryl”, and “(meth) acrylo” includes both “acrylo” and “methacrylo”. . “(Meth) acrylate” is intended to include both “acrylate” and “methacrylate”.

<Image display medium and manufacturing method thereof>
The image display medium of the present invention displays an image by applying an electric field between a pair of substrates. Specifically, the image display medium of the present invention has at least one equivalent of a pair of substrates having translucency, a polymer having a crosslinkable group on the substrate, and a crosslinkable group in the polymer. Display comprising a surface layer obtained by cross-linking a film formed using a composition containing a cross-linking agent, electrophoretic particles enclosed between a pair of substrates and moving in response to an electric field, and a dispersion medium that disperses at least electrophoretic particles And a particle dispersion for use.

Since the surface layer in the present invention is disposed in contact with the display particle dispersion containing the migrating particles, in order to prevent the migrating particles from being fixed, an equal amount or more of a crosslinking agent is used with respect to the crosslinking group in the polymer. It is formed by crosslinking. In particular,
The image display medium of the present invention includes a polymer having a crosslinking group on at least one of a pair of substrates having at least one light-transmitting property, and a crosslinking agent in an amount equal to or more than the crosslinking group in the polymer. A surface layer forming step of forming a surface layer by forming a film by applying a composition and crosslinking, a migrating particle that moves according to an electric field between a pair of substrates on which the surface layer is formed, and at least the migrating particle And a dispersion encapsulating step of enclosing a display particle dispersion containing a dispersion medium for dispersing.

Conventionally, a technique for introducing a strong cross-linked structure has been widely used. However, since a certain degree of cross-linked structure may be formed with a cross-linking group such as a hydroxyl group in a polymer, a crosslinking agent such as an isocyanate compound may be used. The amount is small relative to the crosslinking group such as a hydroxyl group so as not to remain after the reaction. Therefore, generally, it is not considered to add an equal amount or more of a crosslinking agent to the crosslinking group in the polymer. Therefore, a crosslinking group such as a hydroxyl group tends to remain in the polymer. However, since hydroxyl groups and the like are likely to interact with the particles, if hydroxyl groups remain without contributing to the reaction, the remaining hydroxyl groups interact with the particles and, as a result, sticking tends to occur.
In view of such circumstances, in the present invention,
In particular, the amount of the crosslinking agent contained in the composition used when forming the surface layer is equal to or greater than the amount of the crosslinking group in the polymer. Thereby, the quantity of crosslinking groups, such as a hydroxyl group, decreases, and adhesion of particles is suppressed.
At this time, even if the amount of the cross-linking agent is excessively large, the cross-linking agent is deactivated by a post-treatment such as heating, so that the fixing and other properties are not adversely affected.

  Hereinafter, the manufacturing method of the image display medium of the present invention will be described, and details of the image display medium will be described through this description.

-Surface layer formation process-
In the surface layer forming step in the present invention, at least one of a pair of substrates having translucency, a polymer having a crosslinking group and a crosslinking agent in an amount equal to or more than the crosslinking group in the polymer are provided. A surface layer is formed by applying a composition containing the composition (hereinafter, also referred to as “curable composition”) and forming a film, followed by crosslinking. By using an equal amount or more of a crosslinking agent with respect to the crosslinking group, the amount of the crosslinking group (hydroxyl group, etc.) on the surface of the formed surface layer is reduced, and particles are prevented from sticking to the surface layer on the substrate. Is done.

  The curable composition can be formed by applying a known method such as a coating method, an inkjet method, or an immersion method. In the coating method, a known method using apparatuses such as a spin coater, spray coating, bar coater, gravure coater, extrusion die coater, air doctor coater, blade coater, rod coater, knife coater, squeeze coater, reverse roll coater. This can be done by applying the composition.

  The film thickness when the curable composition is applied to form a film is not particularly limited, but is preferably 0.05 μm or more and 20 μm or less, and more preferably 0.2 μm or more and 10 μm or less. When the thickness is 0.05 μm or more, good durability can be secured, and when the thickness is 20 μm or less, the display responsiveness can be maintained well.

Crosslinking after film formation is preferably performed by a heating method. By heating, the reaction between the crosslinking group in the film and the crosslinking agent can be promoted.
The heating temperature at the time of crosslinking varies depending on the reaction rate and composition, but is preferably about 60 ° C to 200 ° C, more preferably 80 ° C to 150 ° C. Although heating time changes with heating temperature, the range for 30 minutes-180 minutes is preferable.

  The substrate on which the surface layer is formed can be appropriately selected and used as long as it is a conductive material capable of applying an electric field. Specific examples of the substrate include a conductive substrate having electrodes on a support substrate.

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

Examples of the electrode material include oxides such as indium, tin, cadmium and antimony, composite oxides such as ITO, metals such as gold, silver, copper and nickel, and organic materials such as polypyrrole and polythiophene. The electrode may be a single layer film, a mixed film, or a composite film.
The electrode can be formed by, for example, a vapor deposition method, a sputtering method, a coating method, or the like.
The film thickness of the electrode is appropriately adjusted so as to obtain a desired conductivity, but is generally 10 nm or more and 1 μm or less.
The electrodes are formed in a desired pattern, for example, a matrix shape or a stripe shape enabling passive matrix driving by a conventionally known means such as etching of a conventional liquid crystal display element or a printed board.
The electrode may be embedded in the support substrate, or the electrode may be separated from the substrate and disposed outside.

  The curable composition for forming the surface layer contains at least a polymer having a crosslinking group and a crosslinking agent, and, if necessary, further includes other polymerization initiators (such as radical initiators), organic solvents, and other additives. It can be constructed using components.

(Polymer having a crosslinking group)
The polymer having a crosslinking group is not particularly limited as long as it is a polymer having a crosslinking group such as a hydroxyl group. For example, olefin resin (for example, polyethylene, polypropylene), polycarbonate, polyester (for example, (meth) acrylate resin), High molecular compounds such as polystyrene, polyimide, polyurethane, polyamide, polymethyl methacrylate, copolymerized nylon, epoxy resin, ultraviolet curable acrylic resin, silicone resin, and fluorine resin can be used.
Among these, a silicone-based polymer compound is preferable, a silicone-based polymer compound that is a copolymer including a structural unit derived from a monomer having a crosslinking group is more preferable, and further, a silicone chain and a crosslinking group are included in the molecule. A silicone-based polymer compound having a group derived from a monomer having a hydrogen atom is preferred.
Examples of the crosslinking group include an epoxy group, an oxazoline group, and an isocyanate group.

  Preferred embodiments of the polymer compound having a silicone chain include, for example, a monomer having a silicone chain (hereinafter, also referred to as “A. silicone chain component”) and a monomer having a reactive group (hereinafter, “ B. Reactive component "or" Crosslinking group-containing component ") and, if necessary, a copolymer of other monomer (hereinafter also referred to as" C. Other copolymer component "). Is mentioned. Hereinafter, each monomer (component) will be described.

-A. Silicone chain component
Examples of the reactive compound having a silicone chain (polymerizable monomer having a silicone chain) include known compounds such as a linear silicone compound and a branched silicone compound. The reactive compound having a silicone chain may be a monomer or a macromonomer. This "macromonomer" is a generic term for oligomers having a polymerizable functional group (degree of polymerization of about 2 or more and about 300 or less) or polymers, and has the properties of both polymers and monomers. is there. Moreover, the reactive compound having a silicone chain may be used alone or in combination.
As the silicone chain component, a monomer represented by the following general formula (1) having a linear structure is suitable.

In general formula (1), R ₁ represents a hydrogen atom or a methyl group. R ₂ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. n represents 0 or more and 1000 or less. x represents an integer of 1 to 3.

  Specific examples of the monomer represented by the general formula (1) include: JNC Corporation: Silaplane: FM-0711, FM-0721, FM-0725, etc., Shin-Etsu Chemical Co., Ltd .: X-22-174DX, X- 22-2426, X-22-2475, etc.).

  Moreover, the monomer shown by following General formula (2) and (3) which has a branched structure is also suitable.

In the general formulas (2) and (3), R ₁ and R ₂ represent a hydrogen atom or a methyl group as in the general formula (1). R ₃ , R ₄ , R ₅ , and R ₆ each independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a fluoroalkyl group having 1 to 4 carbon atoms. n, l, and m each independently represent an integer of 0 or more and 1000 or less. x represents an integer of 1 to 3.

  Specific examples of the monomers represented by the general formulas (2) and (3) include RTT-1011 and MCS-M11 manufactured by Gelest, X22-2404 manufactured by Shin-Etsu Chemical Co., Ltd., and the like.

-B. Reactive component (crosslinking group-containing component)-
Examples of the reactive component containing a crosslinking group include monomers having a crosslinking group such as an epoxy group, an oxazoline group, and an isocyanate group.
Examples of reactive components containing a crosslinking group include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, glycerin methacrylate, N, N, N-trimethyl-N- (2-hydroxy-3-methacryloyloxypropyl) ammonium chloride. , Polyethylene glycol monomethacrylate, polypropylene glycol monomethacrylate, polyethylene glycol-polypropylene glycol-monomethacrylate, 2-hydroxy-3-phenoxypropyl acrylate, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3- Methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethyl And so on.

-C. Other copolymer components
Other copolymer components include N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dibutylaminoethyl (meth) acrylate, and N, N-hydroxyethylaminoethyl. It has an aliphatic amino group such as (meth) acrylate, N-ethylaminoethyl (meth) acrylate, N-octyl-N-ethylaminoethyl (meth) acrylate, N, N-dihexylaminoethyl (meth) acrylate ( (Meth) acrylates;
N-methylacrylamide, N-octylacrylamide, N-phenylmethylacrylamide, N-cyclohexylacrylamide, N-phenylacrylamide, Np-methoxy-phenylacrylamide, N, N-dimethylacrylamide, N, N-dibutylacrylamide, N -(Meth) acrylamides such as methyl-N-phenylacrylamide; aromatic substituted ethylene monomers having a nitrogen-containing group such as dimethylaminostyrene, diethylaminostyrene, dimethylaminomethylstyrene, dioctylaminostyrene; vinyl -N-ethyl-N-phenylaminoethyl ether, vinyl-N-butyl-N-phenylaminoethyl ether, triethanolamine divinyl ether, vinyl diphenylaminoethyl ether, N -Nitrogen-containing vinyl ether monomers such as vinyl hydroxyethylbenzamide and m-aminophenyl vinyl ether;

Pyrroles such as N-vinylpyrrole; pyrrolines such as N-vinyl-2-pyrroline and N-vinyl-3-pyrroline; N-vinylpyrrolidine, vinylpyrrolidine aminoether, N-vinyl-2-pyrrolidone and the like Pyrrolidines; imidazoles such as N-vinyl-2-methylimidazole; imidazolines such as N-vinylimidazoline; indoles such as N-vinylindole; indolines such as N-vinylindoline; Carbazoles such as vinyl carbazole and 3,6-dibromo-N-vinyl carbazole; pyridines such as 2-vinyl pyridine, 4-vinyl pyridine and 2-methyl-5-vinyl pyrrolidine ;, (meth) acrylic piperidine, N- Piperidines such as vinylpiperidone and N-vinylpiperazine; 2-vinylquinoline Quinolines such as 4-vinyl quinoline; pyrazoles such as N-vinyl pyrazole and N-vinyl pyrazoline; oxazoles such as 2-vinyl oxazole; oxazines such as 4-vinyl oxazine and morpholinoethyl (meth) acrylate; ,

Acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid, or their anhydrides and their monoalkyl esters, vinyl ethers having a carboxyl group such as carboxyethyl vinyl ether, carboxypropyl vinyl ether; Sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, 3-sulfopropyl (meth) acyclic acid ester, bis- (3-sulfopropyl) -itaconic acid ester, and salts thereof; 2-hydroxyethyl (Meth) acrylic acid monoester and salts thereof; vinyl phosphonic acid, vinyl phosphate, acid phosphoxyethyl (meth) acrylate, acid phosphoxypropyl (meth) acrylate, bis (meta Liloxyethyl) phosphate, diphenyl-2-methacryloyloxyethyl phosphate, diphenyl-2-acryloyloxyethyl phosphate, dibutyl-2-methacryloyloxyethyl phosphate, dibutyl-2-acryloyloxyethyl phosphate, dioctyl-2- (meth) ) Acryloyloxyethyl phosphate;
Other copolymer components include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, (meth) acrylic acid alkyl esters such as butyl (meth) acrylate, hydroxyethyl (meth) acrylate, and hydroxybutyl. (Meth) acrylate, monomer having ethylene oxide unit (for example, (meth) acrylate of alkyloxyoligoethylene glycol such as tetraethylene glycol monomethyl ether (meth) acrylate, (meth) acrylate of one end of polyethylene glycol), (meth) acrylic acid , Maleic acid, N, N-dialkylamino (meth) acrylate and the like.

  Among the above, components A and B are indispensable components for constituting the polymer compound, and component C is preferably copolymerized as necessary. As for the copolymerization ratio of the three components, “A. silicone chain component” is 5% by mass or more, more desirably 10% by mass or more. When the non-silicone chain component is 95% by mass or less, the surface activity ability is maintained, and the effect of suppressing the sticking of particles is improved. Further, “B. reactive component (crosslinking group-containing component)” is desirably in the range of 0.1% by mass to 90% by mass. When the reactive component is 90% by mass or less, the reactive group hardly remains in the treatment layer, and an adverse effect on the movement characteristics (electrophoretic characteristics) of the particles can be suppressed. Further, when the reactive component is 0.1% by mass or more, the polymer compound is favorably bonded to the substrate surface. This ratio is the ratio of the charged amount when synthesizing the polymer compound.

The weight average molecular weight of the polymer having a crosslinking group (preferably a polymer compound having a silicone chain) is preferably in the range of 500 to 1,000,000, more preferably 1,000 to 1,000,000. The weight average molecular weight is a value measured as a polystyrene equivalent value using gel permeation chromatography (GPC). The measurement conditions are as follows.
<Condition>
・ GPC: HLC-8220 GPC [manufactured by Tosoh Corporation]
Column: TSKgeL SuperHZM-H, TSKgeL SuperHZ4000, TSKgeL SuperHZ2000 (all manufactured by Tosoh Corporation)
-Mobile phase solvent: Tetrahydrofuran-Standard sample: Standard polystyrene-Flow rate: 0.35 ml / min
-Column temperature: 40 ° C

  The surface layer in the present invention is a layer in which a polymer compound is crosslinked using a crosslinking agent, and is crosslinked by polymerizing a reactive group of a polymer compound that is a polymerization component having a reactive group (crosslinkable group). And a method of adding a crosslinking agent to the polymer compound to cause crosslinking.

  Examples of the crosslinking agent include known crosslinking agents such as polyisocyanate compounds, amino resins, amino formaldehyde resins, phosphoric dichloride compounds, acid anhydrides, polyaldehyde compounds, and the like. Of these, polyisocyanate compounds, amino resins, aminoformaldehyde resins, and polyaldehyde compounds are preferable, and polyisocyanate compounds are particularly preferable.

  Examples of the polyisocyanate include tolylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, 1,3-bis (isocyanatomethyl) benzene, 1,3-bis (isocyanatomethyl) cyclohexane, and the like. Bifunctional isocyanate is mentioned. Furthermore, the bifunctional isocyanate adduct to a polyfunctional alcohol and the biuret body, allophanate body, and isocyanurate body which are multimers of the bifunctional isocyanate are also preferably used.

  The treatment layer using the polymer compound having a silicone chain is formed by, for example, applying and drying a coating solution containing the polymer layer on the substrate and the gap member.

  Commercially available products may be used as the crosslinking agent. Examples of commercially available products include, for example, Takenate series manufactured by Takeda Pharmaceutical Co., Ltd. (for example, Takenate D120N, D160N, D140N, D103H, etc.) can be preferably used.

In the present invention, the ratio of the cross-linking agent to the cross-linking group in the polymer in the surface layer is equal to or more than the same amount. The molar ratio of the crosslinking agent and the crosslinking group in the polymer is the same, or the ratio of the crosslinking agent to the crosslinking group in the polymer (crosslinking agent / crosslinking group [molar ratio]) exceeds 1 (100 mol%), That is, by setting the amount of the cross-linking agent in an excessive amount range, the remaining amount of the cross-linking group is reduced, and the occurrence of particle sticking can be suppressed.
The ratio (molar ratio) of the crosslinking agent to the crosslinking group in the polymer is preferably 120 mol% or more, more preferably 130 mol% or more, from the viewpoint that the effect of suppressing the adhesion of the migrating particles is more exerted. Even if an excessive amount of the crosslinking agent is contained, the subsequent production process (for example, heating at the time of crosslinking) is eliminated, so that there is little risk of adverse effects.

  The content of the crosslinking agent in the curable composition may be in a range satisfying the above-described ratio, and specifically, it is preferably 25% by mass or more and 75% by mass or less with respect to the total mass of the composition.

  Preparation of a curable composition can be prepared by mixing the polymer which has a crosslinking group, and a crosslinking agent, and adjusting to a desired density | concentration with a solvent if needed.

  The thickness of the surface layer is preferably 0.05 μm or more and 20 μm or less, and more preferably 0.2 μm or more and 10 μm or less. When the thickness of the surface layer is 0.05 μm or more, it is possible to form a durable surface layer. Moreover, when the thickness of the surface layer is 20 μm or less, there is no influence on the application of the electric field, and the image display property can be maintained well.

-Dispersion encapsulation process-
The dispersion encapsulating step in the present invention is a display particle dispersion comprising a migrating particle that moves according to an electric field between a pair of substrates on which a surface layer is formed in the surface layer forming step, and a dispersion medium that disperses at least the migrating particle. Enclose the solution.

  In this step, the dispersion is sealed between the substrates to form a multilayer structure of substrate / surface layer / dispersion / surface layer / substrate. Since it is required that an electric field can be applied between the two substrates, a conductive substrate having an electrode on the support substrate is preferably used as the substrate, and the support substrate / electrode / surface layer / dispersion liquid / surface layer / electrode is used. It is preferable to form a multilayer structure of / support substrate or support substrate / electrode / surface layer / dispersion / surface layer / support substrate.

Since the pair of substrates enclose the dispersion liquid between the substrates, a gap member (so-called spacer) can be provided to form a gap between the substrates of the pair of substrates.
The gap member (for example, 24 in FIG. 1) is formed so as not to impair the translucency of the substrate, and is made of thermoplastic resin, thermosetting resin, electron beam curable resin, photo curable resin, rubber, metal, Teflon (registered) Trademark) sheet or the like.

  The gap member may be integrated with any one of the substrates. In this case, the substrate can be manufactured by performing etching processing for etching the substrate, laser processing processing, press processing processing or printing processing using a previously manufactured mold. The gap member can be formed on one or both of the pair of substrates.

The gap member may be colored or colorless, but is desirably colorless and transparent so as not to adversely affect the image displayed on the display medium. Specifically, for example, transparent resins such as polystyrene, polyester, and acrylic can be used.
“Transparent” means having a transmittance of 60% or more with respect to visible light.

  The gap provided between the pair of substrates, that is, the thickness of the gap member varies depending on the substrate size and the like, but is preferably 20 μm or more and 100 μm or less.

--Particulate dispersion for display--
The display particle dispersion encapsulated between a pair of substrates includes migrating particles that move in response to an electric field, and at least a dispersion medium that disperses the migrating particles. If necessary, a charge control agent and an external additive are further included. Can be used.

(Electrophoretic particles)
The display particle dispersion in the present invention contains at least one kind of migrating particles.
Electrophoretic particles are at least one type of particles that move in response to an electric field. The electrophoretic particles are positively or negatively charged, for example, and can move in the dispersion medium by forming an electric field having a predetermined electric field strength or higher. Electrophoretic particles are particles having different colors and different charging characteristics. The difference in the charging characteristics indicates that the charging polarity or the charging amount of the particles is different, or that both the charging polarity and the charging amount are different.
The change in display color in the image display medium is caused by the movement of the migrating particles in the dispersion medium.

  Examples of the migrating particles include resin particles, those obtained by fixing a colorant on the surface of the resin particles, and particles containing a colorant in the resin. In addition, examples of the migrating particles include insulating metal oxide particles (for example, particles such as glass beads, alumina, and titanium oxide), metal colloid particles having a plasmon coloring function, and the like.

(1) Resin Examples of thermoplastic resins used for the migrating particles include styrenes such as styrene and chlorostyrene; monoolefins such as ethylene, propylene, butylene, and isoprene; vinyl acetate, vinyl propionate, vinyl benzoate, Vinyl esters such as vinyl butyrate; α such as methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate -Methylene aliphatic monocarboxylic acid esters; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl butyl ether; or vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and vinyl isopropenyl ketone. Polymer, or resin made of a copolymer thereof.
Examples of thermosetting resins used for the migrating particles include cross-linked copolymers based on divinylbenzene and cross-linked resins such as cross-linked polymethyl methacrylate, phenol resins, urea resins, melamine resins, polyester resins, silicone resins, etc. Is mentioned.

  Typical resins used for the migrating particles include, for example, polystyrene resin, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene. -Maleic anhydride copolymer, polyethylene resin, polypropylene resin, polyester resin, polyurethane resin, epoxy resin, silicone resin, polyamide resin, modified rosin, paraffin wax and the like.

In particular, as the resin used for the migrating particles, a resin having a chargeable group (hereinafter referred to as “polymer having a chargeable group”) is preferably used in order to impart charge to the particles.
The polymer having a chargeable group is, for example, a polymer having a cationic group or an anionic group. Examples of the cationic group as the charging group include an amine group and a quaternary ammonium group (including salts of these groups), and a positively charged polarity is imparted to the particles by the cationic group. On the other hand, examples of the anionic group as the chargeable group include a carboxyl group, a carboxylate group, a sulfonate group, a sulfonate group, a phosphate group, and a phosphate group. Charge polarity is imparted.

  Specific examples of the polymer having a chargeable group include, for example, a homopolymer of a monomer having a chargeable group, a monomer having a chargeable group, and another monomer (having no chargeable group). Monomer).

  Examples of the monomer having a charging group include a monomer having a cationic group (hereinafter referred to as a cationic monomer) and a monomer having an anionic group (hereinafter referred to as an anionic monomer). It is done.

  Examples of the cationic monomer include the following. Specifically, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dibutylaminoethyl (meth) acrylate, N, N-hydroxyethylaminoethyl (meta) ) Acrylate, N-ethylaminoethyl (meth) acrylate, N-octyl-N-ethylaminoethyl (meth) acrylate, N, N-dihexylaminoethyl (meth) acrylate and other aliphatic amino groups (meth) Acrylates: N-methylacrylamide, N-octylacrylamide, N-phenylmethylacrylamide, N-cyclohexylacrylamide, N-phenylacrylamide, Np-methoxy-phenylacrylamide, N, N-dimethylacrylamide, N, N-dibutylacrylate (Meth) acrylamides such as rilamide, N-methyl-N-phenylacrylamide; aromatic substituted ethylene monomers having a nitrogen-containing group such as dimethylaminostyrene, diethylaminostyrene, dimethylaminomethylstyrene, dioctylaminostyrene; Vinyl-N-ethyl-N-phenylaminoethyl ether, vinyl-N-butyl-N-phenylaminoethyl ether, triethanolamine divinyl ether, vinyl diphenylaminoethyl ether, N-vinylhydroxyethylbenzamide, m-aminophenyl vinyl ether Nitrogen-containing vinyl ether monomers such as;

  Preferred examples of the cationic monomer include nitrogen-containing heterocyclic compounds. Among them, pyrroles such as N-vinylpyrrole; N-vinyl-2-pyrroline, N-vinyl-3-pyrroline, etc. Pyrrolines; N-vinyl pyrrolidine, vinyl pyrrolidine amino ether, pyrrolidines such as N-vinyl-2-pyrrolidone; imidazoles such as N-vinyl-2-methylimidazole; imidazolines such as N-vinyl imidazoline; Indoles such as vinylindole; Indolines such as N-vinylindoline; N-vinylcarbazole, carbazoles such as 3,6-dibromo-N-vinylcarbazole; 2-vinylpyridine, 4-vinylpyridine, 2-methyl- Pyridines such as 5-vinylpyridine; (meth) acrylic piperidine, N-vinylpiperide Piperidines such as N-vinylpiperazine; quinolines such as 2-vinylquinoline and 4-vinylquinoline; pyrazoles such as N-vinylpyrazole and N-vinylpyrazoline; oxazoles such as 2-vinyloxazole; 4-vinyloxazine And oxazines such as morpholinoethyl (meth) acrylate;

On the other hand, examples of the anionic monomer include a carboxylic acid monomer, a sulfonic acid monomer, and a phosphoric acid monomer.
Examples of the carboxylic acid monomer include, for example, (meth) acrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, and citraconic acid, and anhydrides thereof, monoalkyl esters thereof, carboxyethyl vinyl ether, or carboxy Examples thereof include vinyl ethers having a carboxyl group such as propyl vinyl ether, and salts thereof.
Examples of the sulfonic acid monomer include styrene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, 3-sulfopropyl (meth) acyclic acid ester, bis- (3-sulfopropyl) -itaconic acid ester, and the like. The salt is mentioned. Examples of the sulfonic acid monomer include sulfuric acid monoesters of 2-hydroxyethyl (meth) acrylic acid and salts thereof.
Examples of phosphoric acid monomers include vinyl phosphonic acid, vinyl phosphate, acid phosphoxyethyl (meth) acrylate, acid phosphoxypropyl (meth) acrylate, bis (methacryloxyethyl) phosphate, diphenyl-2-methacryloyloxyethyl phosphate Diphenyl-2-acryloyloxyethyl phosphate, dibutyl-2-methacryloyloxyethyl phosphate, dibutyl-2-acryloyloxyethyl phosphate, dioctyl-2- (meth) acryloyloxyethyl phosphate, and the like.

Examples of other monomers that may be used in combination with the monomer having a chargeable group include water-soluble monomers (for example, monomers having a hydroxyl group). Specifically, for example, , Hydroxyethyl (meth) acrylate, hydroxybutyl (meth) acrylate, a monomer having an ethylene oxide unit (eg, (oxy) alkyloxyoligoethylene glycol (meth) acrylate such as tetraethylene glycol monomethyl ether (meth) acrylate), or one end of polyethylene glycol (Meth) acrylate), (meth) acrylic acid and salts thereof, maleic acid, (meth) acrylamide-2-methylpropanesulfonic acid and salts thereof, vinylsulfonic acid and salts thereof, and vinylpyrrolidone.
Examples of other monomers include other well-known nonionic monomers.

(2) Colorant Examples of the colorant used for the migrating particles include organic or inorganic pigments and oil-soluble dyes.
Examples of the colorant include magnetic powder such as magnetite and ferrite, and carbon black, titanium oxide, magnesium oxide, zinc oxide, phthalocyanine copper-based cyan color material, azo-based yellow color material, azo-based magenta color material, and quinacridone-based material. Known colorants such as a magenta color material, a red color material, a green color material, and a blue color material can be used.
Specific examples of the colorant include aniline blue, calcoyl blue, chrome yellow, ultramarine blue, dupont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black, rose bengal, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 122C. I. Pigment red 57: 1, C.I. I. Pigment yellow 97, C.I. Blue 15: 1, C.I. I. Pigment Blue 15: 3 is a typical example.

  The content of the colorant is, for example, from 10% by mass to 99% by mass and preferably from 30% by mass to 99% by mass with respect to the resin that is a constituent component of the migrating particles.

(3) Other components The electrophoretic particles may contain a charge control agent, if necessary. Examples of the charge control agent include known ones used for toner materials for electrophotography. For example, cetylpyridyl chloride, BONTRON P-51, BONTRON P-53, BONTRON E-84, BONTRON E-81 (above, Quaternary ammonium salts such as Orient Chemical Industry Co., Ltd., salicylic acid metal complexes, phenol condensates, tetraphenyl compounds, metal oxide particles, and metal oxide particles surface-treated with various coupling agents.

If necessary, an external additive may be attached to the surface of the migrating particle. The color of the external additive is preferably transparent so as not to affect the color of the migrating particles.
Examples of the external additive include inorganic particles such as metal oxides such as silicon oxide (silica), titanium oxide, and alumina. The external additive may be surface-treated with a coupling agent or silicone oil in order to adjust the chargeability, fluidity, or environment dependency of the migrating particles.
Examples of coupling agents include positively chargeable coupling agents such as aminosilane coupling agents, aminotitanium coupling agents, and nitrile coupling agents, and no nitrogen atoms (consisting of atoms other than nitrogen). And negatively chargeable coupling agents such as silane coupling agents, titanium coupling agents, epoxy silane coupling agents, and acrylic silane coupling agents.
Examples of silicone oils include positively charged silicone oils such as amino-modified silicone oils, and dimethyl silicone oils, alkyl-modified silicone oils, α-methylsulfone-modified silicone oils, methylphenyl silicone oils, chlorophenyl silicone oils, and Examples include negatively charged silicone oils such as fluorine-modified silicone oils.
These coupling agents or silicone oils are selected according to the desired resistance of the external additive.

  The primary particle diameter of the external additive is, for example, preferably from 1 nm to 100 nm, and preferably from 5 nm to 50 nm, but is not limited thereto.

The external additive amount of the external additive is, for example, preferably 0.01 parts by mass or more and 3 parts by mass or less, and preferably 0.05 parts by mass or more and 1 part by mass or less with respect to 100 parts by mass of the migrating particles. .
The external addition amount of the external additive is preferably adjusted based on the balance between the particle size of the migrating particles and the particle size of the external additive. When the amount of the external additive is within the above range, at least a part of the external additive is liberated from the surface of the migrating particle and adheres to the surface of the other migrating particle, so that desired charging characteristics cannot be obtained. This is advantageous in that it is easily prevented.

  The external additive may be added to any one of a plurality of types of migrating particles, or may be externally added to a plurality of types or all types of migrating particles. When an external additive is added to the surface of all types of migrating particles, the external additive is applied to the migrating particle surface with an impact force, or the migrating particle surface is heated to firmly fix the external additive to the migrating particle surface. It is preferable to do. As a result, the external additive is released from the migrating particles, and the external additive of different polarity is strongly aggregated to prevent the formation of an aggregate of the external additive that is difficult to dissociate with an electric field. This is advantageous in that deterioration is easily prevented.

-Characteristics of migrating particles-
The volume average particle size of the migrating particles is, for example, preferably from 0.05 μm to 20 μm, and preferably from 0.1 μm to 1 μm. The size of the migrating particles is not particularly limited, and a preferable range can be determined according to the application. The particle size is a value measured by a particle size analyzer (FPAR-1000 manufactured by Otsuka Electronics Co., Ltd.) as a volume average particle size.

The concentration of the migrating particles in the display particle dispersion is not particularly limited as long as a desired display color can be obtained. For example, the concentration is preferably 0.01% by mass or more and 50% by mass or less. .
The concentration of the migrating particles is preferably within the above range as the concentration in the display particle dispersion in a state of being enclosed between a pair of substrates of the image display medium. Further, it is effective to adjust the concentration of the migrating particles by the distance between the pair of substrates of the image display medium. In order to obtain a desired hue, the particle concentration decreases as the distance between the pair of substrates of the image display medium increases, and the particle concentration increases as the distance decreases.

--Method of producing electrophoretic particles--
Any conventionally known method may be used as a method for producing the migrating particles. Specifically, the method shown below is mentioned, for example.
1) As described in JP-A-7-325434, the resin, the pigment and, if necessary, the charge control agent are weighed to the desired mixing ratio, the resin is heated and melted, and then the pigment is added and mixed A method of producing electrophoretic particles by using a pulverizer such as a jet mill, a hammer mill, or a turbo mill after being dispersed and cooled.
2) A method of producing electrophoretic particles by a polymerization method such as suspension polymerization, emulsion polymerization, dispersion polymerization, or coacervation, melt dispersion, or emulsion aggregation.
3) When the resin has plasticity, the dispersion medium does not boil, and the resin, the colorant, and the dispersion are at a temperature lower than the decomposition point of at least one of the resin, the colorant, and if necessary, the charge control agent. A method of producing particles by dispersing and kneading the medium and, if necessary, the raw material of the charge control agent (specifically, for example, a meteor mixer, a kneader, etc. A method of producing electrophoretic particles by heating and melting a control agent in a dispersion medium, and using the temperature dependence of the solvent solubility of the resin, cooling the molten mixture with stirring, solidifying and / or precipitating).
4) The above raw materials are put into a suitable container equipped with granular media for dispersion and kneading, for example a heated vibration mill such as an attritor or a heated ball mill, and the container is placed in a preferred temperature range, for example 80 ° C. A method of producing particles by dispersing and kneading at 160 ° C. or lower.
As the granular media, for example, steel such as stainless steel and carbon steel, alumina, zirconia, silica and the like are desirably used. In order to produce migrating particles by a method using granular media, the raw material that has been fluidized in advance is further dispersed in the container by granular media, and then the dispersion medium is cooled to remove a resin containing a colorant from the dispersion medium. It is better to precipitate. It is preferable that the granular media generate shear and / or impact while maintaining the motion state during and after cooling and reduce the particle size of the resulting migrating particles.

(Dispersion medium)
The display particle dispersion in the present invention contains at least one dispersion medium.
The dispersion medium is preferably an insulating liquid. Here, “insulating” indicates that the volume resistivity value is 10 ¹¹ Ωcm or more.
Specific examples of the insulating liquid include hexane, cyclohexane, toluene, xylene, decane, hexadecane, kerosene, paraffin, isoparaffin, silicone oil, high-purity petroleum, ethylene glycol, alcohols, ethers, esters, dimethylformamide. , Dimethylacetamide, dimethylsulfoxide, 1-methyl-2-pyrrolidone, N-methylformamide, acetonitrile, tetrahydrofuran, propylene carbonate, ethylene carbonate, benzine, diisopropylnaphthalene, olive oil, trichlorotrifluoroethane, tetrachloroethane, dibromotetrafluoroethane, etc. Moreover, a mixture thereof is preferably mentioned.

Of these, silicone oil is preferably used as the dispersion medium.
Specific examples of the silicone oil include silicone oils in which a hydrocarbon group is bonded to a siloxane bond (for example, dimethyl silicone oil, diethyl silicone oil, methyl ethyl silicone oil, methyl phenyl silicone oil, diphenyl silicone oil, etc.). Among these, dimethyl silicone is particularly preferable.

  If necessary, an acid, an alkali, a salt, a dispersion stabilizer, a stabilizer for the purpose of preventing oxidation or ultraviolet absorption, an antibacterial agent, an antiseptic, and the like may be added to the dispersion medium. It is preferable to add so that it may become the range of the specific volume specific resistance value shown.

For dispersion media, anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, fluorosurfactants, silicone surfactants, metal soaps, alkyl phosphates as charge control agents Esters and succinimides may be added and used.
Examples of these surfactants include the following.

  Examples of nonionic surfactants include polyoxyalkylene alkylphenol ethers such as polyoxyethylene nonylphenol ether and polyoxyethylene octylphenyl ether; polyoxyalkylene ethers such as polyoxyethylene cetyl ether and polyoxypropylene ether; Glycols such as all-type polyoxyalkylene glycol, diol-type polyoxyalkylene glycol, and triol-type polyoxyalkylene glycol; primary linear alcohol ethoxylates such as octylphenol ethoxylate, and secondary linear alcohol ethoxys Alkyl alcohol ethers such as rate; polyoxyalkylene alkyl esters such as polyoxyethylene lauryl ester; sorbita Sorbitan fatty acid esters such as monolaurate, sorbitan dilaurate, sorbitan sesquipalmitate; polyoxyethylene sorbitan esters such as polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan dilaurate, polyoxyethylene sorbitan sesquilaurate Fatty acid esters such as saturated fatty acid stearyl ester, unsaturated fatty acid stearyl ester, and stearic acid polyethylene glycol ester; fatty acids such as stearic acid and oleic acid, and amidated compounds of these fatty acids; polyoxyethylene alkylamines, higher Examples include fatty acid monoethanolamides, higher fatty acid diethanolamides, amide compounds, and alkanolamides.

  Examples of anionic surfactants include polycarboxylic acid type polymer surfactants, carboxylates such as rosin soap; castor oil sulfate ester salt, lauryl alcohol sulfate ester Na salt, lauryl alcohol sulfate ester amine salt, higher grades Alcohol sulfate salts such as alcohol sulfate Na salt, sulfate amine amine of lauryl alcohol ether, sulfate ester Na salt of lauryl alcohol ether, sulfate amine salt of synthetic higher alcohol ether, sulfate ester Na of synthetic higher alcohol ether Salt, alkyl polyether sulfate ester amine salt, alkyl polyether sulfate Na salt, natural alcohol EO (ethylene oxide) addition system sulfate amine amine, natural alcohol EO (ethylene oxide) addition system sulfuric acid Steal Na salt, synthetic alcohol EO (ethylene oxide) addition system sulfate ester amine salt, synthetic alcohol EO (ethylene oxide) addition system sulfate ester Na salt, alkylphenol EO (ethylene oxide) addition system sulfate ester amine salt, alkylphenol EO (ethylene oxide) addition system sulfuric acid Ester Na salt, polyoxyethylene nonyl phenyl ether sulfate amine salt, polyoxyethylene nonyl phenyl ether sulfate Na salt, polyoxyethylene polycyclic phenyl ether sulfate amine salt, polyoxyethylene polycyclic phenyl ether sulfate Na salt, etc. Sulfate ester salts of: various alkylallyl sulfonic acid amine salts, various alkyl allyl sulfonic acid Na salts, naphthalene sulfonic acid amine salts, naphthalene Sulfonates such as sulfonic acid Na salt, various alkylbenzene sulfonic acid amine salts, various alkylbenzene sulfonic acid Na salts, naphthalene sulfonic acid condensate, naphthalene sulfonic acid formalin condensate; polyoxyethylene nonylphenyl ether sulfonic acid amine salt, polyoxy And polyoxyalkylene sulfonates such as ethylene nonylphenyl ether sulfonate Na salt.

Examples of cationic surfactants include alkyltrimethylamine quaternary ammonium salts; quaternary ammonium salts such as tetramethylamine salts and tetrabutylamine salts; (RNH ₃ ) (CH ₃ COO) [R = stearyl, cetyl, Lauryl, oleyl, dodecyl, coconut oil, soybean oil, beef tallow etc.] acetates; lauryl dimethylbenzylammonium salt (halogen salt or amine salt), stearyl dimethylbenzylammonium salt (halogen salt or amine salt etc.) Benzylamine-based quaternary ammonium salts such as dodecyldimethylbenzylammonium salt (halogen salt or amine salt); R (CH ₃ ) N (C ₂ H ₄ O) _m H (C ₂ H ₄ O) _n · X [ R = stearyl, cetyl, lauryl, oleyl, dodecyl, tetradecyl, f Sadeshiru or linoleyl like; X = polyoxyalkylene quaternary ammonium salts represented by halogen or amine, etc.].

  Examples of amphoteric surfactants include various betaine surfactants.

The content of these charge control agents in the display particle dispersion (the total content when multiple types are used) is, for example, based on the total solid content of all the particles (that is, the display colored particles and the display white particles). It is good that it is 0.01 mass% or more, Preferably it is 20 mass% or less, More preferably, it is 0.05 mass% or more and 10 mass% or less.
When the content of the charge control agent is 0.01% by mass or more, it is advantageous in that the desired charge control effect is sufficiently exhibited, and when it is 20% by mass or less, an excessive increase in conductivity of the dispersion medium is achieved. Is advantageous in that it is easily suppressed.

  The dispersion medium may be added with a polymer. The polymer is preferably a polymer gel or a polymer.

-Characteristics of dispersion medium-
The specific gravity of the dispersion medium, for example, in an environment of temperature 25 ℃, 0.6g / cm ³ or more 1.2 g / cm ³ or less is that good, 0.7 g / cm ³ or more 1.1 g / cm ³ or less Is preferable, and 0.7 g / cm ³ or more and 1.0 g / cm ³ or less is more preferable.
Setting the specific gravity of the display white particles in the above range is advantageous in that the precipitation of the display white particles is easily suppressed.

The viscosity of the dispersion medium is, for example, preferably from 0.1 mPa · s to 100 mPa · s, preferably from 0.1 mPa · s to 50 mPa · s in an environment of a temperature of 20 ° C. More preferably, it is s or more and 20 mPa · s or less.
In particular, the viscosity of the dispersion medium is preferably 5 mPa · s or less. When the viscosity of the dispersion medium is 5 mPa · s or less, the display responsiveness of the colored particles for display is improved, and even when the viscosity is 5 mPa · s or less, the white particles for display have the above characteristics, so that the sedimentation is suppressed. It is advantageous in that it becomes easy.
The viscosity of the dispersion medium can be adjusted, for example, by adjusting the molecular weight, structure, composition, etc. of the dispersion medium.

<Image display device>
The image display device of the present invention is configured by providing the above-described image display medium of the present invention and an electric field applying means for applying an electric field for moving the migrating particles between a pair of substrates constituting the image display medium. ing. The details of the image display medium are as described above.

  The electric field applying means can be configured by electrically connecting a voltage applying unit (voltage applying device) to the electrode so that an electric field for moving the migrating particles can be applied. You may electrically connect to the application part. Moreover, the structure by which one of the electrodes was earth | grounded and the other was connected to the voltage application part may be sufficient.

The voltage application unit can be configured to be connected so as to transmit and receive a signal to the control unit.
The control unit stores in advance various programs such as a CPU (central processing unit) that controls the operation of the entire apparatus, a RAM (Random Access Memory) that temporarily stores various data, and a control program that controls the entire apparatus. It may be configured as a microcomputer including a ROM (Read Only Memory).
Therefore, the voltage application unit is a voltage application device for applying a voltage to the electrodes, and can apply a voltage according to the control of the control unit between the electrodes.

Hereinafter, an image display apparatus according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram illustrating an image display apparatus according to an embodiment of the present invention. Hereinafter, the migrating particles are also referred to as “colored particles” or “colored particles for display”.

  As shown in FIG. 1, the image display apparatus 10 according to the present embodiment includes a display medium 12, a voltage application unit 16 (an example of an electric field generation unit), and a control unit 18. In the present embodiment, a particle dispersion liquid including the colored particle group 34, the white particle group 36, and the dispersion medium 50 is used as the display particle dispersion liquid.

As shown in FIG. 1, the display medium 12 holds a display substrate 20 serving as a display surface, a rear substrate 22 facing the display substrate 20 with a gap, and holds the substrates at a predetermined interval. And a gap member 24 that divides the back substrate 22 into a plurality of cells.
Here, the cell refers to a region surrounded by the display substrate 20, the back substrate 22, and the gap member 24. In this cell, a colored particle group 34, a white particle group 36, and a dispersion medium 50 for dispersing these particle groups are enclosed. The colored particle group 34 and the white particle group 36 are dispersed in the dispersion medium 50, and the colored particle group 34 moves between the display substrate 20 and the back substrate 22 in accordance with the electric field strength formed in the cell. A surface layer 25 is provided on the inner surface of each gap member 24.

It is to be noted that the gap member 24 is provided so as to correspond to each pixel when an image is displayed on the display medium 12, and cells are formed so as to correspond to each pixel, whereby the display medium 12 displays the color for each pixel. May be configured to be possible.
A plurality of types of colored particle groups 34 having different colors are dispersed in the dispersion medium 50 of the display medium 12. The plurality of types of colored particle groups 34 are particles that can be electrophoresed between the substrates, and the absolute value of the voltage required to move in accordance with the electric field is different for each color particle group.

  The display substrate 20 has a configuration in which a surface electrode 40 and a surface layer 42 are sequentially laminated on a support substrate 38. The back substrate 22 has a structure in which a back electrode 46 and a surface layer 48 are sequentially laminated on a support substrate 44.

  Examples of materials of the support substrate 38 and the support substrate 44 and examples of materials of the front electrode 40 and the back electrode 46 are as described above. Further, the surface electrode 40 may be embedded in the support substrate 38. Similarly, the back electrode 46 may be embedded in the support substrate 44. The back electrode 46 and the surface electrode 40 may be separated from the display substrate 20 and the back substrate 22 and disposed outside the display medium 12.

In the above description, the case where both the display substrate 20 and the back substrate 22 are provided with the electrodes (the front electrode 40 and the back electrode 46) has been described.
In order to enable active matrix driving, the support substrate 38 and the support substrate 44 are provided with active elements such as TFT (Thin Film Transistor), TFD (Thin Film Diode), MIM (Metal-Insulator-Metal) element, and varistor for each pixel. May be provided. The active elements are preferably formed not on the display substrate 20 but on the back substrate 22 because wiring can be easily stacked and components can be easily mounted.

  In particular, when the front electrode 40 and the back electrode 46 are formed on the support substrate 38 and the support substrate 44, respectively, it is preferable to provide the surface layers 42 and 48 as dielectric films. A surface layer is used. This prevents the occurrence of leakage between the electrodes that causes breakage of the front electrode 40 and the back electrode 46 and adhesion of the particles of the colored particle group 34.

  In the present embodiment, a case where surface layers (a surface layer 42 and a surface layer 48) are provided on both opposing surfaces of the display substrate 20 and the back substrate 22 will be described, but the display substrate 20 and the back substrate 22 are opposed to each other. The structure provided only in either one of the surfaces may be sufficient. These surface layers may be made of different materials.

  Note that examples of the material of the surface layer 42 and the surface layer 48 are as described above in the section of “surface layer forming step”.

As the material for the surface layer 42 and the surface layer 48, in addition to the above-described insulating material, an insulating material containing a charge transporting substance may be used. Inclusion of a charge transport material improves particle chargeability by injecting particles into the particle, and when the charge amount of the particle becomes extremely large, the charge of the particle is leaked and the charge amount of the particle is stabilized. An effect is obtained.
Examples of charge transport materials include hole transport materials such as hydrazone compounds, stilbene compounds, pyrazoline compounds, and arylamine compounds, electron transport materials such as fluorenone compounds, diphenoquinone derivatives, pyran compounds, and zinc oxide, and polyvinylcarbazole. Examples thereof include resins having charge transport properties such as

The gap member 24 is a member for holding a gap between the display substrate 20 and the back substrate 22 and is formed so as not to impair the transparency of the display substrate 20, and is a thermoplastic resin, a thermosetting resin, an electron beam curing. It is formed of resin, photo-curing resin, rubber, metal or the like. A surface layer 25 is provided on the inner surface of the gap member 24. The material and thickness of the surface layer 25 are the same as those of the surface layers 42 and 48 described above.
The gap member 24 includes a cell type and a particle type. Examples of the cellular shape include a net or a sheet having holes formed in a matrix shape by etching or laser processing.
The gap member 24 may be integrated with either the display substrate 20 or the back substrate 22, and the support substrate 38 or the support substrate 44 is etched or laser processed, or a prefabricated mold is used and pressed. The support substrate 38 or the support substrate 44 having a cell pattern of any size and the gap member 24 are manufactured by processing or printing. In this case, the gap member 24 can be fabricated on either the display substrate 20 side, the back substrate 22 side, or both. The gap member 24 may be colored, but is preferably colorless and transparent so as not to adversely affect the display image displayed on the display medium 12.

The voltage application unit 16 is electrically connected to the front electrode 40 and the back electrode 46. In this embodiment, the case where both the front electrode 40 and the back electrode 46 are electrically connected to the voltage application unit 16 will be described. However, one of the front electrode 40 and the back electrode 46 is grounded. The other may be connected to the voltage application unit 16.
The voltage application unit 16 is a voltage application device (for example, a power supply) for applying a voltage to the surface electrode 40 and the back electrode 46, and applies a voltage between the surface electrode 40 and the back electrode 46 according to the control of the control unit 18. To do.

The control unit 18 is connected to the voltage application unit 16 so as to be able to exchange signals.
Although not shown, the control unit 18 includes a CPU (Central Processing Unit) that controls the operation of the entire apparatus, a RAM (Random Access Memory) that temporarily stores various data, and a control program and processing routine that control the entire apparatus. The microcomputer includes a ROM (Read Only Memory) in which various programs including the program shown are stored in advance.

~ Driving method ~
In the image display apparatus 10 according to the present embodiment, the display medium 12 displays different colors by changing the applied voltage (V) applied between the display substrate 20 and the back substrate 22.
In the display medium 12, the colored particles move in accordance with the electric field formed between the display substrate 20 and the back substrate 22, so that each pixel corresponding to each pixel of the display medium 12 is assigned to each pixel of the image data. A corresponding color can be displayed.

  Here, in the display medium 12, as described above, as shown in FIG. 2, in the colored particle group 34, the colored particle group 34 moves for each color according to the electric field when electrophoresis is performed between the substrates. Therefore, the absolute value of the voltage required for each is different. The colored particle group 34 for each color has a voltage range necessary for moving the colored particle group 34 for each color, and the voltage range is different. In other words, the absolute value of the voltage has the voltage range, and the voltage range is different for each color of the colored particle group 34.

  In the present embodiment, as the colored particle group 34 enclosed in the same cell of the display medium 12, as shown in FIG. 1, a magenta magenta particle group 34M, a cyan cyan particle group 34C, and The description will be made assuming that the three colored particles 34 of the yellow yellow particle group 34Y are enclosed.

  The magenta magenta particle group 34M, the cyan cyan particle group 34C, and the yellow color yellow particle group 34Y are used as the absolute value of the voltage when the three color particle groups start moving. It is assumed that 34M is | Vtm |, the cyan cyan particle group 34C is | Vtc |, and the yellow yellow particle group 34Y is | Vty |. Further, the maximum voltage for moving almost all of the three color particle groups of the magenta particle group 34M, the cyan cyan particle group 34C, and the yellow yellow particle group 34Y of the colored particle group 34 of each color is set. As absolute values, it is assumed that the magenta magenta particle group 34M is | Vdm |, the cyan cyan particle group 34C is | Vdc |, and the yellow yellow particle group 34Y is | Vdy |.

The absolute values of Vtc, -Vtc, Vdc, -Vdc, Vtm, -Vtm, Vdm, -Vdm, Vty, -Vty, Vdy, and -Vdy described below are | Vtc | <| Vdc | <| Vtm | In the following description, it is assumed that the relationship is <| Vdm | <| Vty | <| Vdy |.
Specifically, as shown in FIG. 2, for example, all the colored particle groups 34 are charged to the same polarity, and the absolute value of the voltage range necessary to move the cyan particle group 34C | Vtc ≦ Vc ≦ Vdc | ( Absolute value of a value between Vtc and Vdc), absolute value of voltage range necessary to move the magenta particle group 34M | Vtm ≦ Vm ≦ Vdm | (absolute value of a value between Vtm and Vdm), and yellow The absolute value of the voltage range necessary to move the particle group 34M | Vty ≦ Vy ≦ Vdy | (the absolute value of the value between Vty and Vdy) is set so as to increase without overlapping in this order. ing.

  Further, in order to independently drive the colored particle groups 34 of the respective colors, the absolute value | Vdc | of the maximum voltage for moving almost all of the cyan particle groups 34M is within the voltage range necessary for moving the magenta particle group 34M. Absolute value | Vtm ≦ Vm ≦ Vdm | (absolute value between Vtm and Vdm), and absolute value of voltage range necessary to move yellow particle group 34M | Vty ≦ Vy ≦ Vdy | (Vty to Vdy) Is set to be smaller than the absolute value). Further, the absolute value | Vdm | of the maximum voltage for moving almost all of the magenta particle group 34M is equal to the absolute value | Vty ≦ Vy ≦ Vdy | (Vty to Vdy) of the voltage range necessary for moving the yellow particle group 34M. Is set to be smaller than the absolute value).

That is, in this embodiment, the color particle groups 34 of each color are independently driven by setting the voltage ranges necessary for moving the color particle groups 34 of each color so as not to overlap.
The “voltage range necessary for moving the colored particle group 34” means the voltage necessary for the particle to start moving and the change in display density even if the voltage and voltage application time are further increased from the start of movement. Indicates a voltage range until the display density is saturated.
The “maximum voltage necessary for moving almost all the colored particle groups 34” means that even if the voltage and voltage application time are further increased from the start of the above movement, the display density does not change and the display density is saturated. Indicates the voltage to be used.

  Further, “almost all” means that the characteristics of some of the colored particle groups 34 are different so that the characteristics of some of the colored particle groups 34 do not contribute to the display characteristics. That is, even if the voltage and the voltage application time are further increased from the start of the movement described above, the display density does not change and the display density is saturated.

In addition, “display density” is measured between the display surface side and the back side while measuring the color density on the display surface side with a reflection densitometer of optical density (Optical Density = 0D) of X-rite. Apply a voltage and gradually change this voltage in the direction of increasing the measured concentration (increase or decrease the applied voltage) to saturate the concentration change per unit voltage, and in that state, adjust the voltage and voltage application time. Even when the density is increased, the density does not change, and the density is shown when the density is saturated.
In the display medium 12 according to this embodiment, the voltage applied between the substrates is gradually increased by applying a voltage from 0 V between the front substrate 20 and the rear substrate 22 to increase the voltage value of the applied voltage. When the value exceeds + Vtc, the display density starts to change due to the movement of the cyan particle group 34C in the display medium 12. Further, when the voltage value is increased and the voltage applied between the substrates becomes + Vdc, the change in display density due to the movement of the cyan particle group 34 in the display medium 12 stops.

  Further, when the voltage value is increased and the voltage applied between the front substrate 20 and the rear substrate 22 exceeds + Vtm, a change in display density due to the movement of the magenta particle group 34M starts to appear in the display medium 12. When the voltage value is further increased and the voltage applied between the front substrate 20 and the rear substrate 22 becomes + Vdm, the change in display density due to the movement of the magenta particle group 34M in the display medium 12 stops.

Further, when the voltage value is increased and the voltage applied between the substrates exceeds + Vty, a change in display density due to the movement of the yellow particle group 34Y starts to appear in the display medium 12. When the voltage value is further increased and the voltage applied between the substrates becomes + Vdy, the change in display density due to the movement of the yellow particle group 34Y in the display medium 12 stops.
On the other hand, if the negative electrode voltage is applied from 0 V to the substrate between the front substrate 20 and the rear substrate 22 to gradually increase the absolute value of the voltage, and the absolute value of the voltage −Vtc applied between the substrates is exceeded. In the display medium 12, the display density starts to change due to the movement of the yellow particle group 34C between the substrates. Further, when the absolute value of the voltage value is increased and the voltage applied between the front substrate 20 and the rear substrate 22 becomes −Vdc or more, the display density changes due to the movement of the cyan particle group 34C in the display medium 12. Stop.

  Further, when the negative voltage is applied by increasing the absolute value of the voltage value and the voltage applied between the front substrate 20 and the rear substrate 22 exceeds the absolute value of −Vtm, the display medium 12 displays magenta. A change in display density due to the movement of the particle group 34M begins to appear. When the absolute value of the voltage value is further increased and the voltage applied between the front substrate 20 and the rear substrate 22 becomes −Vdm, the change in display density due to the movement of the magenta particle group 34M in the display medium 12 stops. .

  Further, when the negative voltage is applied by increasing the absolute value of the voltage value, and the voltage applied between the front substrate 20 and the rear substrate 22 exceeds the absolute value of −Vty, the display medium 12 displays yellow. Changes in the display density begin to appear due to the movement of the particle group 34Y. When the absolute value of the voltage value is further increased and the voltage applied between the substrates becomes −Vdy, the change in display density due to the movement of the yellow particle group 34 </ b> C in the display medium 12 stops.

  That is, in the present embodiment, as shown in FIG. 2, the voltage applied between the substrates is in the range of −Vtc to Vtc (voltage range | Vtc | or less). Are applied between the substrates, the movement of the particles of the colored particle group 34 (the cyan particle group 34C, the magenta particle group 34M, and the yellow particle group 34Y) to the extent that the display density of the display medium 12 changes. Is not occurring. When a voltage equal to or higher than the absolute value of the voltage + Vtc and the voltage −Vtc is applied between the substrates, a change occurs in the display density of the display medium 12 for the cyan particle group 34 </ b> C among the three color particle groups 34. The display density starts to change for a certain degree of particle movement, and when a voltage equal to or higher than the absolute value | Vdc | of the voltage −Vdc and the voltage Vdc is applied, the display density per unit voltage does not change.

  Further, when a voltage is applied between the front substrate 20 and the rear substrate 22 such that the voltage applied between the substrates is in the range of −Vtm to Vtm (voltage range | Vtm | or less), It can be said that the movement of the particles of the magenta particle group 34M and the yellow particle group 34Y to the extent that the display density of the display medium 12 changes does not occur. When a voltage higher than the absolute value of the voltage + Vtm and the voltage −Vtm is applied between the substrates, the display density of the display medium 12 is changed for the magenta particle group 34M and the magenta particle group 34M of the yellow particle group 34Y. The display density per unit voltage starts to change to the extent that particles are generated, and when the voltage −Vdm and voltage Vdm absolute value | Vdm | or more are applied, the display density changes. Disappear.

  Further, when a voltage is applied between the front substrate 20 and the rear substrate 22 so that the voltage applied between the substrates is within a range of −Vty to Vty (voltage range | Vty | or less), the display is performed. It can be said that the movement of the particles of the yellow particle group 34Y to the extent that the display density of the medium 12 changes does not occur. When a voltage higher than the absolute value of the voltage + Vty and the voltage −Vty is applied between the substrates, the yellow particle group 34Y starts to move and display a particle that causes a change in the display density of the display medium 12. When the density starts to change and a voltage equal to or higher than the absolute value | Vdy | of the voltage −Vdy and the voltage Vdy is applied, the display density does not change.

  Next, a driving method for displaying an image on the display medium 12 in the image display apparatus 10 according to the present embodiment will be described with reference to FIG.

  First, a voltage −Vdy is applied between the display substrate 20 and the back substrate 22. Thereby, all of the magenta particle group 34M, the cyan particle group 34C, and the yellow particle group 34Y are positioned on the back substrate 22 side (see FIG. 3A).

  Next, it is selected whether the yellow particle group 34Y having the highest movement start voltage is moved or left as it is. When the voltage + Vdy is applied, all of the magenta particle group 34M, the cyan particle group 34C, and the yellow particle group 34Y move to the display substrate 20 side and display black (K) (see FIG. 3B). On the other hand, when the voltage + Vty is applied, the magenta particle group 34M and the cyan particle group 34C move to the display substrate 20 side, but the yellow particle group 34Y remains as it is and remains on the back substrate 22 side as blue (B). Display is made (see FIG. 3C). When the voltage is greater than or equal to + Vty and less than or equal to + Vdy, a part of the yellow particle group 34Y moves, so that a halftone can be obtained.

  Next, it is selected whether the magenta particle group 34M having the second highest movement start voltage is moved or left as it is. When the voltage −Vdm is applied, the magenta particle group 34M moves to the back substrate 22 side, while when the voltage −Vtm is applied, the magenta particle group 34M remains on the display substrate 20 side. The cyan particles 34C whose movement start voltage is lower than the magenta particles 34M move to the back substrate 22 side in any case. On the other hand, the yellow particles 34Y whose movement start voltage is higher than the magenta particles 34M maintain the previous state (for example, the state of FIG. 3A or the state of FIG. 3B) in any case. When the voltage is −Vtm or more and −Vdm or less, a part of the magenta particle group 34M moves, so that a halftone can be obtained.

Therefore, when the voltage −Vdm is applied in the state of FIG. 3B, the yellow particles 34Y remain on the display substrate 20 side, and the magenta particles 34M and the cyan particles 34C move to the back electrode 22 side. As yellow (Y) display (see FIG. 3D).
When the voltage −Vtm is applied in the state of FIG. 3B, the yellow particles 34Y and the magenta particles 34M remain on the display substrate 20 side, and the cyan particles 34C move to the back electrode 22 side, resulting in red (R) is displayed (see FIG. 3E).
When the voltage −Vdm is applied in the state of FIG. 3C, the yellow particles 34Y remain on the back substrate 22 side, and the magenta particles 34M and cyan particles 34C move to the back electrode 22 side, resulting in white (W) is displayed (see FIG. 3F).
When the voltage −Vtm is applied in the state of FIG. 3C, the yellow particles 34Y remain on the back substrate 22 side, the magenta particles 34M remain on the display substrate 20 side, and the cyan particles 34C remain on the back electrode 22. As a result, the display becomes magenta (M) (see FIG. 3G).

  Finally, it is selected whether the cyan particle 34C having the lowest movement start voltage is moved or left as it is. When the voltage + Vdc is applied, the cyan particle group 34C moves to the display substrate 20 side. On the other hand, when the voltage + Vtc is applied, the cyan particle group 34C remains on the back substrate 22 side. The magenta particles 34M and the yellow particles 34Y whose movement start voltage is higher than that of the cyan particle group 34C maintain the previous state in any case. Therefore, when the voltage + Vtc is applied, the previous display color is maintained. When the voltage is greater than or equal to + Vtc and less than or equal to + Vdc, part of the cyan particle group 34C moves, so that a halftone can be obtained.

Therefore, when the voltage + Vdc is applied in the state of FIG. 3D, the cyan particle group 34C moves to the display substrate 20 side, the yellow particles 34Y move to the display substrate 20 side, and the magenta particles 34M move to the back electrode 22 side. As a result, green (G) is displayed (see FIG. 3H).
When the voltage + Vdc is applied in the state of FIG. 3E, the cyan particle group 34C moves to the display substrate 20 side, and the yellow particles 34Y and the magenta particles 34M remain on the display substrate 20 side, resulting in black ( K) is displayed (see FIG. 3I).
When the voltage + Vdc is applied in the state of FIG. 3F, the cyan particle group 34C moves to the display substrate 20 side, and the yellow particles 34Y remain on the magenta particle 34M back electrode 22 side, resulting in cyan ( C) Display is made (see FIG. 3J).
When the voltage + Vdc is applied in the state of FIG. 3G, the cyan particle group 34C moves to the display substrate 20 side, the yellow particles 34Y remain on the back electrode 22 side, and the magenta particles 34M remain on the display substrate 20 side. As a result, blue (B) display is obtained (see FIG. 3K).

  In this way, any color display can be performed by selectively moving desired particles by applying a voltage corresponding to the particle group between the substrates in order from each colored particle group 34 having a high movement start voltage. It becomes.

<Electronic equipment>
The image display device of the present invention is provided in electronic devices, exhibition media, card media, and the like.
Specifically, the image display device of the present invention includes, for example, an electronic bulletin board capable of storing and rewriting images, an electronic circulation version, an electronic blackboard, an electronic advertisement, an electronic signboard, a flashing sign, electronic paper, an electronic newspaper, and an electronic book. Electronic document sheets that can be shared with copiers and printers, portable computers, tablet computers, mobile phones, smart cards, signature devices, watches, shelf labels, flash drives, etc.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist thereof. Unless otherwise specified, “part” is based on mass.

<Preparation of Cyan Particle C1>
1) Preparation of core particles-Preparation of dispersed phase-
The following components were mixed while heating at 60 ° C. to prepare a dispersed phase so that the ink solid content concentration was 15% and the pigment concentration after drying was 50%.
-Styrene acrylic polymer X345 (trade name; manufactured by Seiko PMC) ... 7.2 g
-Cyan pigment PB15: 3 aqueous dispersion: 18.8 g
(Emacol SF Blue H524F (trade name; manufactured by Sanyo Dye Co., Ltd., solid content: 26 mass%)
・ Distilled water ... 24.1 g

-Preparation of continuous phase-
The following components were mixed to prepare a continuous phase.
・ Surfactant KF-6028 (trade name; manufactured by Shin-Etsu Chemical Co., Ltd.) 3.5g
・ Silicone oil KF-96-2cs ... 346.5g
(Product name: Shin-Etsu Chemical Co., Ltd.)

-Particle preparation-
50 g of the above dispersed phase and 350 g of the above continuous phase are mixed and emulsified for 10 minutes at a rotational speed of 10,000 rpm and a temperature of 30 ° C. using an internal tooth tabletop dispersing machine ROBOMICS (trade name; manufactured by Tokushu Kika Kogyo Co.) It was. As a result, an emulsified liquid having an emulsified droplet diameter of about 2 μm was obtained. This was dried with a rotary evaporator at a vacuum of 20 mbar and a water bath temperature of 40 ° C. for 18 hours.
The obtained particle suspension was centrifuged at 6,000 rpm for 15 minutes, the supernatant was removed, and the washing step of redispersing with silicone oil KF-96-2CS was repeated three times. In this way, 6 g of core particles were obtained. As a result of SEM image analysis, the average particle size was 0.6 μm.

2) Shell formation (coacervation method)
-Synthesis of shell resin-
The following components were mixed and polymerized at 70 ° C. for 6 hours under nitrogen.
Silaplane FM-0721 (manufactured by JNC, weight average molecular weight Mw = 5000: general formula (1) [R ₁ = methyl group, R ₂ = butyl group, n = 68, x = 3])
... 50g
・ Hydroxyethyl methacrylate (Aldrich) ・ ・ ・ 32g
・ Monomer AMP-10G containing phenoxy group: 18 g
(Product name: Shin-Nakamura Chemical Co., Ltd.)
・ Monomer containing blocked isocyanate group: 2g
(Karenz MOI-BP (registered trademark; manufactured by Showa Denko KK))
・ Isopropyl alcohol (Kanto Chemical Co., Ltd.) ・ ・ ・ 200g
・ AIBN: 0.2g
(2,2′-azobisisobutyronitrile, trade name, manufactured by Aldrich; radical initiator)

  The obtained product was purified and dried using cyclohexane as a reprecipitation solvent to obtain a shell resin. 2 g of this shell resin was dissolved in 20 g of t-butanol solvent to prepare a shell resin solution.

-Particle coating with shell resin-
1 g of the core particles was placed in a 200 mL eggplant flask, 15 g of silicone oil KF-96-2cs (manufactured by Shin-Etsu Chemical Co., Ltd.) was added, and the mixture was stirred and dispersed while applying ultrasonic waves. 7.5 g of t-butanol, 22 g of the above shell resin solution, and 12.5 g of silicone oil KF-96-2cs (trade name; manufactured by Shin-Etsu Chemical Co., Ltd.) were sequentially added thereto. The input speed was all 2 mL / s. The eggplant flask was connected to a rotary evaporator, and t-butanol was removed at a vacuum of 20 mbar and a water bath temperature of 50 ° C. for 1 hour.

This was further heated in an oil bath with stirring. First, after heating at 100 ° C. for 1 hour to remove residual moisture and residual t-butanol, heating is continued at 130 ° C. for 1.5 hours to remove the blocking group of the blocked isocyanate group, and the shell resin The crosslinking reaction was performed.
After cooling, the obtained particle suspension is centrifuged at 6,000 rpm for 15 minutes, the supernatant is removed, and then re-dispersed using silicone oil KF-96-2cs (manufactured by Shin-Etsu Chemical Co., Ltd.). Was repeated three times. In this way, 0.6 g of cyan particles C1 was obtained. The average particle size was 0.55 μm. The average particle size was measured with a particle size analyzer (FPAR-1000 manufactured by Otsuka Electronics Co., Ltd.) as a volume average particle size.

<Preparation of Cyan Particle C2>
Particle preparation was performed in the same manner as in the method for producing cyan particles C1, except that the method for synthesizing the shell resin was changed as follows, and cyan particles C2 were obtained. The average particle size was 0.55 μm. The average particle size was measured with a particle size analyzer (FPAR-1000 manufactured by Otsuka Electronics Co., Ltd.) as a volume average particle size.
-Synthesis of shell resin-
1.7 parts of Silaplane FM-0721 (manufactured by JNC), 0.2 part of Silaplane FM-0725 (manufactured by JNC), 59.8 parts of hydroxyethyl methacrylate, AMP-10G (Shin Nakamura Chemical Co., Ltd.) 6.5 parts) and Karenz MOI-BP (Showa Denko) 21.8 parts were mixed and dissolved in 200 parts of isopropyl alcohol. In this, 0.2 part of AIBN (2,2′-azobis (isobutyronitrile)) was dissolved as a polymerization initiator, and polymerization was performed at 70 ° C. for 6 hours under nitrogen. The product was purified using cyclohexane as a reprecipitation solvent and dried to obtain a resin (shell resin) for the coating layer.
2 parts of this coating layer resin was dissolved in 20 parts of t-butanol solvent to prepare a coating layer forming solution (shell solution).

<Preparation of Cyan Particle C3>
A solution A was prepared by dissolving 3 parts of silicone-modified polymer KP-545 (manufactured by Shin-Etsu Chemical Co., Ltd.) in 97 parts of dimethyl silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., KF-96-2CS). Subsequently, a solution B was prepared by mixing 10 parts of a dimethylamine / epichlorohydrin polymer, 5 parts of a water-dispersed pigment solution (Ciba, Unisperse / Cyan, pigment concentration 20% by mass) and 85 parts of pure water. . Next, the obtained solution A and solution B were mixed, and dispersed and emulsified with an ultrasonic crusher (UH-600S manufactured by SMT).
Next, the obtained suspension was decompressed (2 KPa), heated (70 ° C.) to remove moisture, and the concentration was adjusted to disperse the comparative cyan particles (electrophoretic particles) CC1 in the silicone oil. A comparative cyan particle dispersion C3 (particle solid content 5 mass%) was obtained.
It was 290 nm as a result of measuring the average particle diameter of the cyan particle (electrophoretic particle) in the produced cyan particle dispersion. The average particle size was measured by a particle size analyzer as a volume average particle size in the same manner as described above.

<Preparation of red particle R1>
-Preparation of dispersion A-1A-
The following components were mixed and ball milling was performed for 20 hours with 10 mmφ zirconia balls to prepare dispersion A-1A.
・ Methyl methacrylate (Aldrich) ・ ・ ・ 53g
・ 2- (Diethylamino) ethyl methacrylate (manufactured by Aldrich) ・ ・ ・ 0.3g
・ Red pigment Red 3090 (trade name; manufactured by Sanyo Dye) ・ ・ ・ 1.5g

-Preparation of dispersion A-1B-
The following components were mixed and finely pulverized with a ball mill in the same manner as described above to prepare a calcium carbonate dispersion A-1B.
・ Calcium carbonate ... 40g
・ Water: 60g

-Preparation of liquid mixture A-1C-
The following components were mixed, degassed with an ultrasonic machine for 10 minutes, and then stirred with an emulsifier to prepare a mixed solution A-1C.
・ Calcium carbonate dispersion A-1B ... 4g
・ 20% saline solution 60g

-Preparation of colored particles-
After mixing the following components, deaeration was performed with an ultrasonic machine for 10 minutes.
・ Dispersion A-1A ... 20g
・ Ethylene glycol dimethacrylate ... 0.6g
・ V601 0.2g
(Dimethyl 2,2′-azobis (2-methylpropionate); trade name, manufactured by Wako Pure Chemical Industries, Ltd .; polymerization initiator)

  This was added to the mixed solution A-1C and emulsified with an emulsifier. Next, this emulsified liquid was placed in a flask, sufficiently degassed under reduced pressure, and sealed with nitrogen gas. Next, it was reacted at 65 ° C. for 15 hours to prepare particles. After cooling, the particles were filtered, and the obtained particle powder was dispersed in ion-exchanged water, and calcium carbonate was decomposed with hydrochloric acid water, followed by filtration. After washing with sufficient distilled water, the openings were passed through nylon sieves having a mesh size of 15 μm and 10 μm to make the particle sizes uniform. The obtained particles had a volume average particle size of 13 μm.

-Quaternary ammonium treatment-
The obtained particles are dispersed in silicone oil KF96-1cs (manufactured by Shin-Etsu Chemical Co., Ltd.), and dodecyl bromide (quaternizing agent) is equimolar with 2- (diethylamino) ethyl methacrylate used for particle preparation. In addition, the mixture was heated at 90 ° C. for 6 hours.
After cooling, this dispersion was washed with a large amount of silicone oil and dried under reduced pressure to obtain red particles R1. The glass transition temperature of the resin contained in the particles was 145 ° C.

<Preparation of white particles W1>
Each material in the following composition was mixed, heated at 65 ° C. for 18 hours, and then subjected to solvent substitution with dimethyl silicone oil (manufactured by Shin-Etsu Silicone, KF-96L-2cs, viscosity 2 cs). Thereby, a resin particle dispersion liquid composed of a copolymer containing 4-vinylbiphenyl as a polymerization component was obtained, and the obtained resin particle dispersion liquid was designated as white particle dispersion liquid 1. The volume average particle diameter of the resin particles was 0.53 μm.
<Composition>
4-vinylbiphenyl (manufactured by Nippon Steel Chemical Co., Ltd.): 1 part Silaplane FM-0721 (manufactured by JNC, weight average molecular weight Mw = 5000: general formula (1) [R ₁ = methyl group, R ₂ = butyl Group, n = 68, x = 3]): 1 part Lauroyl peroxide (manufactured by Aldrich): 0.03 part isopar M (Isopar M: registered trademark, manufactured by ExxonMobil): 10 parts hexane (Kanto) Chemical Co., Ltd.): 2 parts, Toluene (Kanto Chemical Co., Ltd.): 2 parts

<Preparation of particle dispersion 1 for display (CRW mixed particle dispersion)>
The cyan particles C1, red particles R1, and white particles W1 are solids so that the cyan particles (C1, C2, or C3) are 0.1 g, the red particles R1 are 1.3 g, and the white particles W1 are 2.0 g. The silicone oil KF-96L-2cs (manufactured by Shin-Etsu Chemical Co., Ltd.) was added so that the liquid volume was 10 g. Then, the particle dispersion liquid 1 for display was prepared by ultrasonically stirring.

Example 1
<Synthesis of Polymer Compounds A1 to A25>
Add a predetermined amount of a cross-linking group-containing component (such as HEMA), a copolymer component such as MMA, and Si macromer to a three-way cock / Dimroth condenser and a thermometer three-necked flask according to Table 1 below, and the solid content concentration is 25 mass. MFG was added so that it might become%. After carrying out N ₂ bubbling for 10 minutes, the mixture was heated and stirred in an N ₂ atmosphere until the temperature reached 60 ° C. After confirming that the temperature in the flask reached 60 ° C., 0.5 mol% of initiator V-65 was added, followed by heating and stirring at 60 ° C. 0.5 mol% of initiator V-65 was added every 2 hours, and when the reaction time reached 6 hours in total, the reaction was terminated and allowed to cool to obtain polymer compounds A1 to A25.

Details of abbreviations and the like in Table 1 are as follows.
-HEMA: 2-hydroxyethyl methacrylate-MMA: methyl methacrylate-FM-0711: Silaplane FM-0711 (manufactured by JNC)
・ FM-0721: Silaplane FM-0721 (manufactured by JNC)
・ FM-0725: Silaplane FM-0725 (manufactured by JNC)
-X-22-2404: manufactured by Shin-Etsu Chemical Co., Ltd.-X-22-2475: manufactured by Shin-Etsu Chemical Co., Ltd.-MCS-M11: the exemplified compound 1 described above (manufactured by AMAX Co.)
RRT-1011: Exemplary compound 2 described above (manufactured by Amax Co.)

<Preparation of curable compositions B1-B81, BB1-BB56>
According to the present invention, B1 to B81, BB1 to BB56 as comparative examples, and predetermined polymer compounds A1 to A25 are dissolved in a mixed solvent (toluene / tetrahydrofuran = 25/75 mass ratio solvent) according to Tables 2 and 3, respectively. Then, a 4% by mass solution was prepared, and 4 parts of this solution was mixed with 2 parts of the crosslinking agent solution shown in Tables 2 to 4 below to obtain curable compositions B1 to B81 and BB1 to BB56. The concentration of the crosslinking agent solution was appropriately adjusted using the above mixed solvent so that the concentration ratios shown in Tables 2 to 4 below were obtained.

<Production of display cell>
-Formation of surface layer-
A glass substrate on which ITO (indium tin oxide) with a thickness of 50 nm was formed as an electrode by sputtering was prepared, and spin coating was performed on the ITO film by sequentially using the solution of the curable composition obtained above. did. Thereafter, the coating film was dried at 130 ° C. for 1 hour to form a surface layer having a thickness of 400 nm.

-Production of display cells-
Two ITO substrates with a surface layer thus prepared were prepared and used as a display substrate and a back substrate. A Teflon (registered trademark) sheet having a thickness of 50 μm is used as a spacer, and two ITO substrates with a surface layer are overlapped with the surface layers facing each other so as to sandwich this, and the above-mentioned gap is formed in the cell formed by the spacer. The display particle dispersion 1 was injected, and the peripheral portion was cured and sealed with a UV curable resin to produce a display cell as an image display medium.

<Evaluation>
The surface layer and display cell obtained above were measured and evaluated as follows. The results of measurement and evaluation are shown in Tables 2 to 4 below.

-Amount of particles fixed-
For the fabricated cell, the operation of applying a voltage for 5 seconds at ± 20 V was repeated 10 times, and then the voltage was applied to the upper surface for 5 seconds at −20 V, and the encapsulated cyan particles were moved 100% to the upper surface. And then left to stand for 72 hours. Thereafter, a spectral spectrum when a voltage was applied to the upper surface at +20 V for 5 seconds was measured using a colorimeter CM2022 (manufactured by Konica Minolta). For the measured spectrum, the density (X) at a light wavelength of 650 nm is extracted, the density when cyan particles are 100% on the upper surface is “A”, and the density when cyan particles are not present on the upper surface is “B”. Then, the ratio of particles adhering to the upper surface (adhesion ratio) was determined from the following formula.
Fixed particle ratio = (X−B) / (A−B)
For each density, a value obtained by multiplying the logarithm of reflectance by −1 was used. Tables 2 to 4 below show the fixing amount of cyan particles evaluated by the above method for each example.

Details of abbreviations and the like in Tables 2 to 4 are as follows.
D160N: Triisocyanate crosslinking agent ("Takenate D160N" manufactured by Takeda Pharmaceutical Co., Ltd.) D120N: Hydrogenated xylylene diisocyanate crosslinking agent (Takenate D120N manufactured by Takeda Pharmaceutical Co., Ltd.)
D140N: Isophorone diisocyanate crosslinking agent (Takenate D140N manufactured by Takeda Pharmaceutical Co., Ltd.)
D103H: Tolylene diisocyanate crosslinking agent (Takenate D103H manufactured by Takeda Pharmaceutical Co., Ltd.)
AA: Nicarak MW-390 (manufactured by Sanwa Chemical Co., Ltd.)
-BB: Nikarac MX-270 (manufactured by Sanwa Chemical Co., Ltd.)

As shown in Tables 2 to 3, in the present invention in which the amount of the cross-linking agent with respect to the cross-linking group in the polymer is equal to or more than that, it was possible to prevent the adhesion of various display particles that are electrophoretic particles. In particular, a remarkable effect was observed when the amount of the crosslinking agent relative to the crosslinking group in the polymer was 120 mol% or more.
On the other hand, as shown in Table 4, the amount of fixation was not suppressed in the comparative display cell.

  A voltage application unit electrically connected to the control unit was connected to the ITO film of the display cell manufactured as described above to manufacture an image display device.

(Example 2)
In Example 1, the cyan particles C1 used for the preparation of the display particle dispersion 1 were changed to cyan particles C2 and C3, and the surface layers were prepared as B-16 to B in Table 2 as the present invention. −18, A display cell was produced, measured, and evaluated in the same manner as in Example 1 except that BB11 and BB12 were used as comparative examples. The results of measurement and evaluation are shown in Table 5 below.

As shown in Table 5, regardless of the type of particles, in the present invention in which the amount of the crosslinking agent with respect to the crosslinking group in the polymer is equal to or more than that, the effect of preventing the adhesion of various display particles as electrophoretic particles was observed. . In particular, it was remarkable when the amount of the crosslinking agent relative to the crosslinking group in the polymer was 130 mol% or more.
On the other hand, in the display cell for comparison, the amount of fixing was not suppressed.

DESCRIPTION OF SYMBOLS 10 ... Image display apparatus 12 ... Display medium 16 ... Voltage application part 18 ... Control part 20 ... Display board 22 ... Back board 24 ... Gap member 34, 34C, 34M, 34Y ... colored particle group 36 ... white particle group 38 ... support substrate 40 ... surface electrode 42 ... surface layer 44 ... support substrate 46 ... back electrode 48 ... surface layer 50: Dispersion medium

Claims (13)

On at least one of a pair of substrates having at least one light-transmitting property, a composition having a cross-linking group and a composition containing an equal amount or more of a cross-linking agent with respect to the cross-linking group in the polymer is applied. A surface layer forming step of forming a surface layer by forming a film and crosslinking;
A dispersion encapsulating step of encapsulating a display particle dispersion containing a migrating particle that moves according to an electric field between the pair of substrates on which the surface layer is formed, and at least a dispersion medium that disperses the migrating particle;
Manufacturing method of image display medium having   The method for manufacturing an image display medium according to claim 1, wherein the surface layer forming step forms the surface layer by crosslinking by heating.   The image according to claim 1 or 2, wherein in the surface layer forming step, the surface layer is formed by crosslinking with a molar ratio of the amount of the crosslinking agent to the amount of the crosslinking group in the polymer being 120 mol% or more. A method for manufacturing a display medium.   The surface layer forming step forms the surface layer by cross-linking the ratio of the amount of the crosslinking agent to the amount of the crosslinking group in the polymer at a molar ratio of 130 mol% or more. The manufacturing method of the image display medium as described in an item.   The method for producing an image display medium according to claim 1, wherein a cross-linking group of the polymer is a hydroxyl group.   The method for producing an image display medium according to claim 1, wherein the crosslinking group of the crosslinking agent is an isocyanate group. A pair of substrates, at least one of which is translucent,
Formed by forming a film using at least one of the substrates, a polymer having a crosslinking group, and a composition containing a crosslinking agent in an equal amount or more with respect to the crosslinking group in the polymer, followed by crosslinking. A surface layer,
A display particle dispersion liquid containing electrophoretic particles sealed in contact with the surface layer between the pair of substrates and moving in response to an electric field, and at least a dispersion medium for dispersing the electrophoretic particles;
An image display medium comprising:   The image display medium according to claim 7, wherein the crosslinking group of the polymer is a hydroxyl group.   The image display medium according to claim 7 or 8, wherein a crosslinking group of the crosslinking agent is an isocyanate group. An image display medium according to any one of claims 7 to 9, or an image display medium manufactured by the method for manufacturing an image display medium according to any one of claims 1 to 6,
An electric field applying means for applying an electric field for moving the migrating particles between a pair of substrates;
An image display device comprising:   An image display medium according to any one of claims 7 to 9, or an image display medium manufactured by the method for manufacturing an image display medium according to any one of claims 1 to 6. Electronic equipment.   An image display medium according to any one of claims 7 to 9, or an image display medium manufactured by the method for manufacturing an image display medium according to any one of claims 1 to 6. Exhibition media.   An image display medium according to any one of claims 7 to 9, or an image display medium manufactured by the method for manufacturing an image display medium according to any one of claims 1 to 6. Card medium.