WO2013154058A1

WO2013154058A1 - Display medium and display device

Info

Publication number: WO2013154058A1
Application number: PCT/JP2013/060544
Authority: WO
Inventors: 奈実徳永; 弘朗森山; 真鍋　力; 町田　義則; 佐藤　忠伸
Original assignee: 富士ゼロックス株式会社; 富士フイルム株式会社
Priority date: 2012-04-13
Filing date: 2013-04-05
Publication date: 2013-10-17
Also published as: JP2013235262A

Abstract

A display medium (10) that has the following: a pair of substrates (20, 22) that have electrodes and are laid out at a separation from each other, at least one of said substrates being light-transmitting; a dispersion medium (50) sealed in between the pair of substrates (20, 22); particles (34) that are dispersed within the dispersion medium (50) and move within the dispersion medium (50) in response to an electric field formed between the pair of substrates (20, 22); and a surface layer or surface layers (21, 23) comprising a macromolecular compound provided on at least one of the facing surfaces of the pair of substrates (20, 22). Said macromolecular compound is derived from at least the following: (1) 10-90 mol.% of a (meth)acrylic monomer; (2) 1-50 mol.% of a silicone macromer; and (3) 2-70 mol.% of a cross-linkable monomer (with said molar percentages based on the sum of the molar percentages of components (1), (2), and (3) being 100 mol.%).

Description

Display medium and display device

The present invention relates to a display medium and a display device.

Conventionally, a display medium using particles is known as a display medium that can be rewritten repeatedly. The display medium includes, for example, a pair of substrates, and a group of particles sealed between the substrates so as to be able to move between the substrates in accordance with an electric field formed between the pair of substrates. Further, a gap member for partitioning the substrates into a plurality of cells may be provided between the substrates for the purpose of preventing the particles from being biased to a specific region in the substrates.

Here, as an embodiment in which a treatment layer is formed on the surface of a substrate, Japanese Patent Application Laid-Open No. 2010-078826 discloses a pair of substrates having electrodes, at least one of which is translucent and disposed with a gap. A display medium, a dispersion medium sealed between the pair of substrates, and a group of particles that are dispersed in the dispersion medium and move in the dispersion medium in response to an electric field formed between the pair of substrates. An embodiment is disclosed in which a treatment layer formed of a polymer compound having a silicone chain is formed on at least one of the opposing surfaces of the pair of substrates in the medium.

In addition, as a mode in which the surface of the particles in the particle group is treated, JP 2010-262066 A discloses a display medium particle having chargeability used for an information display panel, on the surface of a base particle made of a resin. It is disclosed that an external additive having an external additive surface hydrophobicity of 25% or more and 40% or less measured in a methanol wetting test is used for particles for display media to which an external additive is added.

An object of the present invention is to provide a display medium capable of suppressing the sticking of particles to a substrate facing surface.

The above problem is solved by the following means.
<1> a pair of substrates having electrodes, at least one of which is translucent and disposed with a gap;
A dispersion medium sealed between the pair of substrates;
A group of particles dispersed in the dispersion medium and moving in the dispersion medium in response to an electric field formed between the pair of substrates;
(1) (meth) acrylic monomer of at least 10 mol% to 90 mol%, (2) silicone macromer of 1 mol% to 50 mol%, and (3) crosslinkability of 2 mol% to 70 mol% A polymer compound derived from a monomer (provided that the ratio is a ratio based on the total amount of the components (1), (2) and (3) (100 mol%)) A surface layer provided on at least one of the opposing surfaces of the substrate;
A display medium having

<2> The display medium according to <1>, wherein the surface layer has a surface wetting tension (JIS-K6768 / 1999) of 35 mN / m or less.

<3> The display medium according to <1> or <2>, wherein the polymer compound has a structural unit derived from at least one compound selected from compounds represented by the following structural formula as the silicone macromer.

[In the above structural formula, R ₁ represents a hydrogen atom or a methyl group. R ₁ ′ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. n represents a natural number. x represents an integer of 1 to 3. ]

<4> The dispersion medium is the display medium according to any one of <1> to <3>, wherein the content of polar components excluding water is 0.01% by mass or less.

<5> The display medium according to any one of <1> to <4>,
Voltage applying means for applying a voltage between the pair of substrates;
Is a display device.

According to the invention according to <1>, at least 10 mol% to 90 mol% of (1) (meth) acrylic monomer, 1 mol% to 50 mol% of (2) silicone macromer on the substrate facing surface, Compared with the case where there is no surface layer formed by bonding a polymer compound derived from (3) a crosslinkable monomer of 2 mol% or more and 70 mol% or less, adhesion of particles to the substrate facing surface can be suppressed. A display medium is provided.

According to the invention according to the above <2>, a display medium capable of suppressing the sticking of particles to the substrate facing surface is provided as compared with the case where the surface layer has a surface wetting tension of 35 mN / m or less.

According to the invention according to <3>, a display medium capable of suppressing the sticking of particles to the substrate facing surface is provided as compared with the case where at least one selected from the compounds represented by the structural formula is not used as the silicone macromer. Is done.

According to the invention according to <4>, there is provided a display medium in which the repeated stability of display is maintained as compared with the case where the dispersion medium contains polar components excluding water beyond the above range.

According to the invention according to the above <5>, at least 10 mol% to 90 mol% (1) (meth) acrylic monomer, 1 mol% to 50 mol% (2) silicone macromer on the substrate facing surface, And (3) a display device capable of suppressing the adhesion of particles to the substrate facing surface as compared with a case where a display medium having a surface layer of a polymer compound derived from a crosslinkable monomer of 2 mol% to 70 mol% is not provided. Provided.

1 is a schematic configuration diagram of a display device according to a first embodiment. It is explanatory drawing which shows typically the movement aspect of a particle group when a voltage is applied between the board | substrates of the display medium of the display apparatus which concerns on 1st Embodiment. It is explanatory drawing which shows typically the movement aspect of a particle group when a voltage is applied between the board | substrates of the display medium of the display apparatus which concerns on 1st Embodiment. It is a schematic block diagram of the display apparatus which concerns on 2nd Embodiment. It is a diagram which shows typically the relation between the applied voltage and the amount of movement of particles (display density) in the display device concerning a 2nd embodiment. It is explanatory drawing which shows typically the relationship between the voltage aspect applied between the board | substrates of a display medium, and the movement aspect of particle | grains.

Hereinafter, embodiments of a display medium and a display device according to the present invention will be described.

<Display medium and display device>
A display medium according to the present embodiment includes a pair of substrates having electrodes, at least one of which is translucent and disposed with a gap, a dispersion medium sealed between the pair of substrates, and the dispersion medium A group of particles dispersed in the particles and moving in the dispersion medium according to the electric field formed between the pair of substrates, and a polymer compound derived from at least the following components (1), (2) and (3): Has a surface layer provided on at least one of the opposing surfaces of the pair of substrates.
(1) (meth) acrylic monomer: 10 mol% or more and 90 mol% or less (2) Silicone macromer: 1 mol% or more and 50 mol% or less (3) Crosslinkable monomer: 2 mol% or more and 70 mol% or less The ratio is a ratio based on the total amount of the components (1), (2) and (3) as a reference (100 mol%))

Since the polymer compound obtained by polymerizing at least the compounds of (1) to (3) at the above-mentioned quantitative ratio has a surface layer provided on the opposing surface of the substrate, Particle sticking is suppressed.

In addition, if the amount ratio of (1) (meth) acrylic monomer is less than the lower limit, the surface layer may be whitened or the polymer compound may be gelled, making film formation difficult. When the upper limit is exceeded, particles that can be formed are fixed.
The amount ratio of the (meth) acrylic monomer is more preferably 40 mol% or more and 70 mol% or less.

In addition, if the amount ratio of (2) the silicone macromer is less than the above lower limit value, the effect of suppressing particle adhesion cannot be obtained. On the other hand, if the amount exceeds the above upper limit value, the polymer compound gels and the surface layer is formed. The film becomes difficult.
The amount ratio of the silicone macromer is more preferably 2 mol% or more and 40 mol% or less.

Further, if the amount ratio of (3) the crosslinkable monomer is less than the above lower limit value, the effect of suppressing particle fixation cannot be obtained, while if the amount exceeds the above upper limit value, whitening of the surface layer occurs.
The amount ratio of the crosslinkable monomer is more preferably 5 mol% or more and 40 mol% or less.

This ratio is the ratio of the amount charged when the polymer compound is synthesized.

-Wetting tension Moreover, it is preferable that the wetting tension of the surface of the said surface layer is 35 mN / m or less. When the wetting tension is in the above range, the adhesion of particles to the substrate facing surface is more effectively suppressed.
The wetting tension is preferably 30 mN / m or less, more preferably as small as possible.

The above wetting tension is measured according to JIS-K6768 (1999). Specifically, a cotton swab is immersed in a mixture for wetting tension test (for example, in the range of 22.6 mN / m to 73 mN / m / the greater the numerical value, the closer the intimacy is), and the subject (surface layer) The minimum value of the number of the test liquid mixture that is applied to the surface of the film and wets without getting water repellent is calculated as the wettability index.

The surface tension of the surface layer is controlled by adjusting the type and amount of the (meth) acrylic monomer, silicone macromer and crosslinkable monomer, and the type and amount of silicone macromer and crosslinkable monomer contribute greatly. To do. In particular, from the viewpoint of setting the wetting tension in the above range, it is preferable that the amount of the silicone macromer is not less than the lower limit and the amount of the crosslinkable monomer is not less than the lower limit.

Next, the configuration of the display medium and the display device according to this embodiment will be described.

Hereinafter, although the present embodiment will be described with reference to the drawings, members having the same functions and functions may be given the same reference numerals throughout the drawings, and redundant descriptions may be omitted.

(First embodiment)
FIG. 1 is a schematic configuration diagram of a display device according to the first embodiment. FIGS. 2A and 2B are explanatory views schematically showing a movement mode of the particle group when a voltage is applied between the substrates of the display medium of the display device according to the first embodiment.

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

The display medium 12 holds the display substrate 20 serving as an image display surface, the back substrate 22 facing the display substrate 20 with a gap, and holds the substrate between the display substrate 20 and the back substrate 22 at a predetermined interval. A gap member 24 that divides the space into a plurality of cells, a particle group 34 enclosed in each cell, and a colored suspended particle group 36 having optical reflection characteristics different from the particle group 34 are included.

The above cell indicates a region surrounded by the display substrate 20, the back substrate 22, and the gap member 24. A dispersion medium 50 is enclosed in this cell. The particle group 34 (details will be described later) includes a plurality of particles, dispersed in the dispersion medium 50, and colored floating particles between the display substrate 20 and the back substrate 22 according to the electric field strength formed in the cell. Move through the gaps in group 36.

In the present embodiment, the description will be made assuming that the particle group 34 enclosed in one cell has a predetermined color and is preliminarily prepared by being charged positively or negatively.

In addition, the gap member 24 is provided so as to correspond to each pixel when the image is displayed on the display medium 12, and cells are formed so as to correspond to each pixel, so that the display medium 12 can display each pixel. May be.

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

-Substrate First, a pair of substrates will be described. The display substrate 20 has a surface electrode 40 laminated on a support substrate 38. The back substrate 22 has a back electrode 46 laminated on a support substrate 44.

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

Examples of the support substrate 38 and the support substrate 44 include glass or plastic (for example, polyethylene terephthalate resin, polycarbonate resin, acrylic resin, polyimide resin, polyester resin, epoxy resin, polyethersulfone resin).

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

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

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

In the above description, the case where the electrodes (surface electrode 40 and back electrode 46) are provided on both the display substrate 20 and the back substrate 22 has been described, but active matrix driving may be performed by providing only one of them.

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

-Surface layer Next, a surface layer is demonstrated. A surface layer 21 and a surface layer 23 are provided on the opposing surfaces of the display substrate 20 and the back substrate 22, respectively. A surface layer 25 is also provided on the surface of the gap member 24 (cell inner surface).

In the present embodiment, a case in which surface layers (each of the surface layer 21 and the surface layer 23) are provided on both opposing surfaces of the display substrate 20 and the back substrate 22 will be described. However, the display substrate 20 and the back substrate 22 are described. May be provided only on one of the opposing surfaces, and it is desirable that the surface layer 21 is provided on at least the opposing surface on the display substrate 20 side from the viewpoint of suppressing image defects due to particle fixation. . Further, if the surface layer 25 is provided also on the surface of the gap member 24 (cell inner surface), the adhesion of particles to the gap member 24 is suppressed as compared with the case where the surface layer is not provided on the gap member 24, and the result is displayed. An increase in particles that do not contribute is suppressed. That is, it is preferable to provide a surface layer on at least the opposing surface of the display substrate 20, but it is best that the surface layer is disposed on all of the pair of substrates and the gap member (that is, the cell inner wall surrounded by these). .

In each of the surface layer 21, the surface layer 23, and the surface layer 25, at least a polymer compound derived from the following (1) to (3) (hereinafter also simply referred to as “specific polymer compound”) is used for the display substrate 20 or the back surface. It is preferably provided on the opposing surface of the substrate 22 and the surface of the gap member 24 and further joined together.
(1) (meth) acrylic monomer: 10 mol% or more and 90 mol% or less (2) Silicone macromer: 1 mol% or more and 50 mol% or less (3) Crosslinkable monomer: 2 mol% or more and 70 mol% or less The ratio is a ratio based on the total amount of the components (1), (2) and (3) as a reference (100 mol%))

Each of the surface layer 21, the surface layer 23, and the surface layer 25 contains the specific polymer compound. Specifically, for example, the process of chemically bonding the specific polymer compound to the opposing surfaces of the display substrate 20 and the back substrate 22 or the opposing surfaces of the gap members 24, or the specific polymer Each of the surface layer 21, the surface layer 23, and the surface layer 25 is configured by forming the specific polymer compound on the surface by a process of coating (coating) the compound (that is, a process of forming a polymer compound). is doing.

(1) (meth) acrylic monomers (meth) acrylic monomers include (meth) acrylic acid alkyl esters such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and butyl (meth) acrylate , Hydroxyethyl (meth) acrylate, hydroxybutyl (meth) acrylate, tetraethylene glycol monomethyl ether (meth) acrylate and other alkyloxyoligoethylene glycol (meth) acrylate, polyethylene glycol one-end (meth) acrylate, (meth) Acrylic acid, maleic acid, N, N-dialkylamino (meth) acrylate and the like can be mentioned, among which hydroxyethyl (meth) acrylate and methyl (meth) acrylate are preferred.

Here, “(meth) acryl” means to include both “acryl” and “methacryl”.

(2) Silicone macromer A macromer refers to a monomer having a polymer structure in the molecule, and a silicone macromer represents a macromer having a silicone chain component.
Examples of the silicone macromer include a dimethyl silicone macromer having a (meth) acrylate group at one end, and a dimethyl silicone macromer having an epoxy group at one end.

As a dimethyl silicone macromer having an epoxy group at one end, for example, a silicone compound represented by the following structural formula 1 is preferable. Examples of the silicone compound represented by the following structural formula 1 include, for example, X-22-173DX manufactured by Shin-Etsu Chemical Co., Ltd.

[In Structural Formula 1, R ₁ ′ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. n represents a natural number, for example, 3 or more and 100 or less. x represents an integer of 1 to 3. ]

As a dimethyl silicone macromer having a (meth) acrylate group at one end, for example, a silicone compound represented by the following structural formula 2 is preferable. Examples of the silicone compound represented by the following structural formula 2 include, for example, manufactured by JNC: Silaplane: FM-0711, FM-0721, FM-0725, etc., Shin-Etsu Chemical Co., Ltd .: X-22-174DX, X- 22-2426, X-22-2475, and the like.

[In Structural Formula 2, R ₁ represents a hydrogen atom or a methyl group. R ₁ ′ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. n represents a natural number, for example, 3 or more and 100 or less. x represents an integer of 1 to 3. ]

As a dimethyl silicone macromer having a (meth) acrylate group at one end, for example, a silicone compound having a branched structure represented by the following structural formulas 3 and 4 is also preferable.

[In Structural Formula 3 and Structural Formula 4, R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are each independently a hydrogen atom, having 1 to 4 carbon atoms. Or a fluoroalkyl group having 1 to 4 carbon atoms. R ¹ represents a hydrogen atom or a methyl group. p, q, and r each independently represents an integer of 1 to 1000. x represents an integer of 1 to 3. ]

Examples of the silicone compound represented by the structural formula 3 include, for example, MCS-M11 manufactured by Gelest. Examples of the silicone compound represented by the structural formula 4 include RTT-1011 manufactured by Gelest, X-22-2404 manufactured by Shin-Etsu Chemical Co., Ltd., and the like. The structural formulas of these silicone compounds are shown below.

In MCS-M11, m and l in the above structural formula are each independently an integer of 2 or more and 4 or less, and the molecular weight thereof is 800 or more and 1000 or less.

RTT-1011 is a compound represented by the above structural formula.

X-22-2404 is a compound represented by the above structural formula.

(3) Crosslinkable monomer A crosslinkable monomer is a polymerizable monomer having a group that can form a crosslinked structure, a polymerizable monomer having a group that can form a crosslinked structure by changing the structure, or Represents a polymerizable monomer having a plurality of reactive groups in the molecule.
Examples of the crosslinkable monomer include an isocyanate monomer having an isocyanate block having a (meth) acrylate group at one end and becoming an active isocyanate group upon heating (for example, Karenz MOI-BP manufactured by Showa Denko KK).
Moreover, an isocyanate monomer having a (meth) acrylate group at one end and having an isocyanate group (for example, Showa Denko Co., Ltd .: Karenz AOI, Karenz MOI), glycidyl (meth) acrylate having an epoxy group, and the like are also included.
Further, diisocyanate compounds and triisocyanate compounds (toluene diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, triphenylmethane isocyanate (for example, Takenate D-160N manufactured by Mitsui Chemicals), diepoxy compounds (1,7-octadiene diepoxide, And dicyclopentadiene diepoxide).
Also included are alkylated melamine compounds and alkylated urea compounds having functional groups in the molecule such as imino group, methylol group and methoxymethyl group (for example, Nikalac MX-270 manufactured by Sanwa Chemical Co., Ltd.).

Among these, an isocyanate-based monomer having an isocyanate block having a (meth) acrylate group at one end and becoming an active isocyanate group by heating is particularly preferable.

(4) Other Polymerization Components The specific polymer compound may be a copolymer further containing other polymerization components.
Examples of other polymerization components include aromatic substituted ethylene monomers having a nitrogen-containing group such as dimethylaminostyrene, diethylaminostyrene, dimethylaminomethylstyrene, and dioctylaminostyrene; vinyl-N-ethyl-N-phenyl Nitrogen-containing vinyl ether monomers such as aminoethyl ether, vinyl-N-butyl-N-phenylaminoethyl ether, triethanolamine divinyl ether, vinyl diphenylaminoethyl ether, N-vinylhydroxyethylbenzamide, m-aminophenyl vinyl ether Pyrroles such as N-vinylpyrrole; pyrrolines such as N-vinyl-2-pyrroline and N-vinyl-3-pyrroline; pyrroles such as N-vinylpyrrolidine, vinylpyrrolidine amino ether and N-vinyl-2-pyrrolidone Imidazoles such as N-vinyl-2-methylimidazole; imidazolines such as N-vinylimidazoline; indoles such as N-vinylindole; indolines such as N-vinylindoline; N-vinylcarbazole, 3, Carbazoles such as 6-dibromo-N-vinylcarbazole; Pyridines such as 2-vinylpyridine, 4-vinylpyridine, 2-methyl-5-vinylpyrazine; (meth) acrylic piperidine, N-vinylpiperidone, N-vinylpiperazine, etc. Piperidines; quinolines such as 2-vinylquinoline and 4-vinylquinoline; pyrazoles such as N-vinylpyrazole and N-vinylpyrazoline; oxazoles such as 2-vinyloxazole; 4-vinyloxazine and morpholinoethyl (meth) Oxazine such as acrylate 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; styrene sulfonic acid, 2-acrylamide -2-Methylpropane sulfonic acid, 3-sulfopropyl (meth) acyclic acid ester, bis- (3-sulfopropyl) -itaconic acid ester, and salts thereof; sulfuric acid of 2-hydroxyethyl (meth) acrylic acid Monoesters and salts thereof; vinyl phosphonic acid, vinyl phosphate, acid phosphoxyethyl (meth) acrylate, acid phosphoxypropyl (meth) acrylate, bis (methacryloxyethyl) Sulfate, diphenyl-2-methacryloyloxyethyl phosphate, diphenyl-2-acryloyloxyethyl phosphate, dibutyl-2-methacryloyloxyethyl phosphate, dibutyl-2-acryloyloxyethyl phosphate, dioctyl-2- (meth) acrylic Leuoxyethyl phosphate; aromatic vinyl compounds such as styrene and vinyl naphthalene.

In addition, as the other polymerization component, a polymerization component having a polar group may be used.

Examples of the polymerization component having a polar group include a polymerization component having a base (cationic group), a polymerization component having an acid group (anionic group), and a polymerization component having a hydroxyl group (hydroxyl group).
Examples of the base (cationic group) as a polar group include an amino group and a quaternary ammonium group (including salts of these groups).
Examples of the acid group (anionic group) as the polar group include a phenol group, a carboxyl group, a carboxylate group, a sulfonate group, a sulfonate group, a phosphate group, a phosphate group, and a tetraphenylboron group.

Examples of the polymerization component having a base (cationic group) 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, (meth) acrylate having an aliphatic amino group such as N, N-dihexylaminoethyl (meth) acrylate N-methyl (meth) acrylamide, N-octyl (meth) acrylamide, N-phenylmethyl (meth) acrylamide, N-cyclohexyl (meth) acrylamide, N-phenyl (meth) acrylamide, Np-methoxy- Phenyl (meth) acrylamide, N, -(Meth) acrylamides such as dimethyl (meth) acrylamide, N, N-dibutyl (meth) acrylamide, N-methyl-N-phenyl (meth) acrylamide; dimethylaminostyrene, diethylaminostyrene, dimethylaminomethylstyrene, dioctyl Aromatic substituted ethylene monomers having nitrogen-containing groups such as aminostyrene; vinyl-N-ethyl-N-phenylaminoethyl ether, vinyl-N-butyl-N-phenylaminoethyl ether, triethanolamine di Nitrogen-containing vinyl ether monomers such as vinyl ether, vinyl diphenylaminoethyl ether, N-vinylhydroxyethylbenzamide and m-aminophenyl vinyl ether; pyrroles such as vinylamine and N-vinylpyrrole; N-vinyl-2-pyrrole Pyrrolines such as phosphorus and N-vinyl-3-pyrroline; pyrrolidines such as N-vinylpyrrolidine, vinylpyrrolidine amino ether and N-vinyl-2-pyrrolidone; imidazoles such as N-vinyl-2-methylimidazole Imidazolines such as N-vinylimidazoline; indoles such as N-vinylindole; indolines such as N-vinylindoline; carbazole such as N-vinylcarbazole and 3,6-dibromo-N-vinylcarbazole Pyridines such as 2-vinylpyridine, 4-vinylpyridine and 2-methyl-5-vinylpyridine; piperidines such as (meth) acrylic piperidine, N-vinylpiperidone and N-vinylpiperazine; Quinolines such as quinoline and 4-vinylquinoline; N-vinylpyrazo And pyrazoles such as N-vinylpyrazoline; oxazoles such as 2-vinyloxazole; and oxazines such as 4-vinyloxazine and morpholinoethyl (meth) acrylate.
The polymerization component having a base (cationic group) may be quaternized ammonium chloride before or after polymerization to form a salt structure. Quaternary ammonium chloride is realized, for example, by reacting a cationic group with alkyl halides or tosylate esters.

Examples of the polymerization component having an acid group (anionic group) include the following.
Examples of the polymerization component having a carboxylic acid group include (meth) acrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid, their anhydrides, monoalkyl esters, carboxyethyl vinyl ether, carboxypropyl vinyl ether. And vinyl ethers having a carboxyl group, and salts thereof.
Examples of polymerization components having a sulfonic acid group include styrene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, 3-sulfopropyl (meth) click acid ester, bis- (3-sulfopropyl) -itaconic. And acid esters and salts thereof. In addition, examples of the polymerization component having a sulfonic acid group include sulfuric acid monoesters of 2-hydroxyethyl (meth) acrylic acid and salts thereof.
Examples of the polymerization component having a phosphoric acid group include vinylphosphonic acid, vinyl phosphate, acid phosphoxyethyl (meth) acrylate, acid phosphoxypropyl (meth) acrylate, bis (methacryloxyethyl) phosphate, diphenyl-2-methacrylate. Examples include leuoxyethyl phosphate, diphenyl-2-acryloyloxyethyl phosphate, dibutyl-2-methacryloyloxyethyl phosphate, dibutyl-2-acryloyloxyethyl phosphate, dioctyl-2- (meth) acryloyloxyethyl phosphate It is done.
In addition, the polymerization component having an acid group (anionic group) may be subjected to ammonium chloride before polymerization or after polymerization to form a salt structure. Ammonium chloride is realized, for example, by reacting an anionic group with a tertiary amine or quaternary ammonium hydroxide.

Examples of the polymerization component having a hydroxyl group (hydroxyl group) include hydroxyalkyl (meth) acrylate (for example, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, etc.), allyl alcohol, polyethylene glycol mono (meth) acrylate, and the like. Other examples include those obtained by copolymerizing a monomer having a glycidyl group and then ring-opening, and those obtained by polymerizing a monomer having t-butoxy and then hydrolyzing it to introduce an OH group.

Furthermore, as polymerization components other than those listed above, for example, (meth) acrylonitrile, (meth) acrylic acid alkyl ester, (meth) acrylamide, ethylene, propylene, butadiene, isoprene, isobutylene, N-dialkyl substituted ( And (meth) acrylamide, vinyl carbazole, vinyl chloride, vinylidene chloride, isoprene, butadiene, vinyl pyrrolidone, and the like.

In addition, the polymerization component mentioned as “other polymerization component” is preferably 0% by mass or more and 74% by mass or less, more preferably 25% by mass or more and 70% by mass or less in terms of the mass ratio to the total polysynthesis.

The specific polymer compound may constitute a surface layer as a crosslinked body. In order to obtain the crosslinked body, for example, a polymerization component having a reactive group (crosslinkable group) as a polymerization component is polymerized to form a resin. In addition to the method of crosslinking, and a method of crosslinking by adding a crosslinking agent separately from the polymer compound. In addition, as a crosslinking agent, well-known crosslinking agents, such as isocyanate, are mentioned, for example.

However, when the specific polymer compound contains the above-described other polymerization component as a raw material, the ratio of the other polymerization component is the total amount (100) of the components (1), (2) and (3) described above. The mol% is preferably 900 mol% or less, more preferably 300 mol% or less.

The weight average molecular weight of the specific polymer compound is preferably from 100 to 1,000,000, more preferably from 400 to 1,000,000, more preferably from 500 to 1,000,000, and even more preferably from 1,000 to 500,000. is there.
The weight average molecular weight is measured by a static light scattering method or size exclusion column chromatography, and the numerical values described in this specification are measured by the method.

When the surface layer is formed using the specific polymer compound, when the substrate or the gap member includes a material having a functional group that reacts with a crosslinking group in the crosslinkable monomer, the substrate and the gap member are directly reacted and bonded. This is done by processing. On the other hand, the formation of the surface layer using a specific polymer compound is performed when the substrate or the gap member does not contain a material having a functional group that reacts with the crosslinking group in the crosslinkable monomer. After the treatment with (for example, a silane coupling agent), the treatment is performed by reacting a specific polymer compound with the substrate or the gap member.

Here, the treating agent is preferably a silane coupling agent, such as vinyltrichlorosilane, vinyltris (β-methoxyethoxy) silane, vinyltriethoxysilane, vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane and γ-chloropropyltrimethoxysilane, etc. (b) γ-glycidoxypropyltrimethoxysilane and γ-glycidoxypropylmethyldiethoxysilane, etc. (c) N-β (amino And ethyl) γ-aminopropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, and γ-aminopropyltriethoxysilane.

The thickness of the surface layer of the specific polymer compound is desirably 0.001 μm to 10 μm, more desirably 0.01 μm to 1 μm. The thickness of the surface layer was measured with a Dektak 6M step gauge (manufactured by Veeco).

-Gap member Next, a gap member is demonstrated. The gap member 24 for holding a gap between the display substrate 20 and the back substrate 22 is formed so as not to impair the light-transmitting property of the display substrate 20, and is a thermoplastic resin, a thermosetting resin, an electron beam curable resin. , Photo-curing resin, rubber, metal and the like.

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

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

Further, it is desirable that the particulate gap member 24 is also transparent, and glass particles are used in addition to transparent resin particles such as polystyrene, polyester, or acrylic.

In addition, “transparent” indicates having a transmittance of 60% or more with respect to visible light.

-Dispersion medium Next, a dispersion medium is demonstrated. The dispersion medium 50 in which the particle group 34 is dispersed is desirably an insulating liquid. Here, “insulating” indicates that the volume resistivity is 10 ¹¹ Ωcm or more. The following are synonymous.

The dispersion medium 50 is not particularly limited, but a low dielectric solvent (for example, a dielectric constant of 5.0 or less, desirably 3.0 or less) is preferably selected. The dispersion medium may use a solvent other than the low dielectric solvent, but preferably contains 50% by volume or more of the low dielectric solvent. In addition, the dielectric constant of a low dielectric constant is calculated | required with a dielectric constant meter (made by Nippon Luft).

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

Further, water (so-called pure water) is also suitably used as the dispersion medium 50 by removing impurities so as to have the following volume resistance value. The volume resistance value is preferably 10 ³ Ωcm or more, more preferably 10 ⁷ Ωcm or more and 10 ¹⁹ Ωcm or less, and further preferably 10 ¹⁰ Ωcm or more and 10 ¹⁹ Ωcm or less.

The insulating liquid may contain acids, alkalis, salts, dispersion stabilizers, stabilizers for the purpose of preventing oxidation or UV absorption, antibacterial agents, preservatives, etc. It is desirable to add so that it may become the range of the volume resistance value of.

For insulating liquids, anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, fluorosurfactants, silicone surfactants, metal soaps as charge control agents Alkyl phosphate esters, succinimides and the like may be added and used.

Specific examples of the ionic and nonionic surfactants include the following. Nonionic surfactants include polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester And fatty acid alkylolamide. Examples of the anionic surfactant include alkylbenzene sulfonate, alkylphenyl sulfonate, alkyl naphthalene sulfonate, higher fatty acid salt, sulfate of higher fatty acid ester, sulfonic acid of higher fatty acid ester, and the like. Examples of the cationic surfactant include primary to tertiary amine salts and quaternary ammonium salts. These charge control agents are preferably 0.01% by mass or more and 20% by mass or less, and particularly preferably 0.05% by mass or more and 10% by mass or less with respect to the solid content of the particles.

The dispersion medium 50 may use a polymer resin in combination with the insulating liquid. The polymer resin is preferably a polymer gel, a polymer, or the like.

As this polymer resin, agarose, agaropectin, amylose, sodium alginate, propylene glycol ester of alginate, isolikenan, insulin, ethylcellulose, ethylhydroxyethylcellulose, curdlan, casein, carrageenan, carboxymethylcellulose, carboxymethyl starch, callose, agar, chitin , Chitosan, silk fibroin, gar gum, quince seed, crown gall polysaccharide, glycogen, glucomannan, keratan sulfate, keratin protein, collagen, cellulose acetate, gellan gum, schizophyllan, gelatin, elephant palm mannan, tunisin, dextran, dermatan sulfate, starch , Tragacanth gum, nigeran, hyaluronic acid, hydroxyethylcellulose, hydro Examples include synthetic gels derived from natural polymers such as cyclopropylcellulose, pustulan, funolan, decomposed xyloglucan, pectin, porphyran, methylcellulose, methyl starch, laminaran, lichenan, lentinan, locust bean gum, etc. Includes almost all polymer gels.

In addition, polymers containing functional groups of alcohol, ketone, ether, ester, and amide in the repeating unit are exemplified. For example, polyvinyl alcohol, poly (meth) acrylamide and derivatives thereof, polyvinyl pyrrolidone, polyethylene oxide and the like. Examples include copolymers containing molecules. Among these, gelatin, polyvinyl alcohol, poly (meth) acrylamide and the like are desirably used.

Alternatively, the following colorant may be mixed with the dispersion medium 50 to display a color different from the color of the particle group 34 on the display medium 12. For example, when the color of the particle group 34 is black by mixing a white colorant as the colorant, white and black are displayed on the display medium 12.

Examples of the colorant mixed in the dispersion medium 50 include carbon black, titanium oxide, magnesium oxide, zinc oxide, phthalocyanine copper-based cyan color material, azo-based yellow color material, azo-based magenta color material, quinacridone-based magenta color material, and red. Known colorants such as a color material, a green color material, and a blue color material can be used. Specifically, aniline blue, calcoil blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black, rose bengal, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 57: 1, C.I. I. Pigment yellow 97, C.I. Blue 15: 1, C.I. I. Pigment Blue 15: 3 is a typical example.

Since the particle group 34 moves in the dispersion medium 50, if the viscosity of the dispersion medium 50 is equal to or higher than a predetermined value, there is a large variation in force on the back substrate 22 and the display substrate 20, and the particle movement with respect to the electric field. Therefore, it is preferable to adjust the viscosity of the dispersion medium 50 as well.

The viscosity of the dispersion medium 50 is preferably 0.1 mPa · s or more and 100 mPa · s or less in an environment at a temperature of 20 ° C. from the viewpoint of the moving speed of the particles, that is, the display speed. -It is more preferable that it is s or less, and it is still more desirable that it is 0.1 mPa * s or more and 20 mPa * s or less.

The viscosity of the dispersion medium 50 is adjusted by adjusting the molecular weight, structure, composition, etc. of the dispersion medium. For measurement of the viscosity, a B-8L viscometer manufactured by Tokyo Keiki is used.

・ Particle group (electrophoretic particle group)
The particle group (electrophoretic particle group) 34 includes a plurality of electrophoretic particles. For example, each electrophoretic particle is positively or negatively charged, and is interposed between the front electrode 40 and the back electrode 46 (that is, the display substrate 20). And between the rear substrate 22 and the substrate), a predetermined voltage is applied to form an electric field higher than a predetermined electric field strength between the display substrate 20 and the rear substrate 22 in the dispersion medium 50. Is to move.
The change in display color on the display medium 12 is caused by the movement of each migrating particle contained in the migrating particle group 34 in the dispersion medium 50.

The migrating particles of the migrating particle group 34 include, for example, colored core material particles (hereinafter referred to as “core particles”) and a coating layer that covers the core particles.

-Core particles-
The core particles include, for example, a composition containing a resin (hereinafter referred to as “core particle resin”) and a colorant.

The resin of the core particle may be a non-crosslinked resin, but is preferably a crosslinked resin. In order to make the resin of the core particle a resin cross-linked body, for example, a polymerization component having a reactive group (crosslinkable group) as a polymerization component of the resin is polymerized to crosslink the resin. A method of adding and crosslinking the resin can be mentioned.

The core particle resin (pre-crosslinking resin) is preferably a water-soluble resin or an alcohol-soluble resin from the viewpoint of the production method of the electrophoretic particles. Water-soluble and alcohol-soluble means that the target substance dissolves 1% by mass or more in water or alcohol at 25 ° C.

The core particle resin may be a chargeable resin (a resin having a chargeable group) or a non-chargeable resin (a resin having no chargeable group), but from the viewpoint of improving the charge amount. It is preferable that the resin is a chargeable resin.
Examples of the chargeable resin include a homopolymer of a polymerization component having a chargeable group, and a copolymer of a polymerization component having a chargeable group and a polymerization component having no chargeable group.
On the other hand, examples of the non-chargeable resin include a homopolymer of a polymerization component having no chargeable group.
When these copolymers are resin crosslinked products, a polymerization component having a reactive group (crosslinkable group) may be further copolymerized.
Each of these polymerization components may be used alone or in combination of two or more.

Here, examples of the chargeable group (for example, a polar group; a polarizable functional group) include a base and an acid group.
Examples of the base (cationic group) as the chargeable group include an amino group and a quaternary ammonium group (including salts of these groups). These bases (cationic groups) tend to impart positively charged polarity to the particles, for example.
Examples of the acid group (anionic group) as the chargeable group include a phenol group, a carboxyl group, a carboxylate group, a sulfonate group, a sulfonate group, a phosphate group, a phosphate group, and a tetraphenylboron group. These acid groups (anionic groups) tend to impart negatively charged polarity to the particles, for example.

Hereinafter, each polymerization component will be described.
In the following description, descriptions such as “(meth) acrylate” are expressions including both “acrylate” and “methacrylate”.

Examples of the polymerization component having a base (cationic group) include those similar to the polymerization component having a base (cationic group) described as the polymerization component of the specific polymer compound contained in the surface layer.
Examples of the polymerization component having an acid group (anionic group) include those similar to the polymerization component having an acid group (anionic group) described as the polymerization component of the specific polymer compound contained in the surface layer. .

Examples of the polymerization component having no chargeable group include nonionic polymerization components (nonionic polymerization components). For example, (meth) acrylonitrile, (meth) acrylic acid alkyl ester, (meth) acrylamide, ethylene, propylene, Examples thereof include butadiene, isoprene, isobutylene, N-dialkyl-substituted (meth) acrylamide, vinyl carbazole, vinyl chloride, vinylidene chloride, isoprene, butadiene, vinyl pyrrolidone, and the like.

Examples of the polymerization component having a reactive group (crosslinkable group) include glycidyl (meth) acrylate having an epoxy group, an isocyanate monomer having an isocyanate group (for example, Showa Denko: Karenz AOI (2-isocyanatoethyl acrylate) ), Karenz MOI (2-isocyanatoethyl methacrylate)), an isocyanate monomer having a blocked isocyanate group (for example, Showa Denko: Karenz MOI-BM (methacrylic acid 2- (0- [1'-methylpropylideneamino)) Carboxyamino) ethyl), Karenz MOI-BP (2-[(3,5-dimethylpyrazolyl) carbonylamino] ethyl methacrylate)) and the like.
The blocked isocyanate group is, for example, a state in which the isocyanate group has reacted with a substituent, and a state in which the isocyanate group does not react with a substituent that is eliminated by heating. Thereby, the reactivity of an isocyanate group is suppressed and it will be in the state which reacts, when a substituent detaches | leaves by heating.
When a polymerization component having a reactive group is used as the polymerization component of the resin of the core particle, the core particle resin itself is crosslinked, and the core particle becomes a resin crosslinked body.

In the resin of the core particle, the polymerization component having a chargeable group is preferably 0.1% by mass or more and 90% by mass or less, more preferably 0.5% by mass or more and 70% by mass, with respect to the total polymerization component. It is below mass%.
In addition, the polymerization component having a reactive group is preferably 1% by mass or more and 80% by mass or less, more preferably 3% by mass or more and 60% by mass or less in terms of a mass ratio to the total polymerization components.

Here, as a crosslinking agent for obtaining a resin crosslinked body, crosslinking agents, such as an epoxy compound, a carboxyimide compound, block isocyanate, are mentioned, for example.
Examples of the epoxy compound include glycidyl (meth) acrylate, itaconic acid diglycidyl ester, butenetricarboxylic acid triglycidyl ester, p-styrenecarboxylic acid glycidyl ester, and the like, vinyl glycidyl ether, allyl glycidyl ether, 2- And unsaturated glycidyl ethers such as methylallyl glycidyl ether, methacryl glycidyl ether, and styrene-p-glycidyl ether.
Examples of the carboximide compound include saccharin, succinimide, and phthalimide.
Examples of the blocked isocyanate include isocyanate-based monomers having the blocked isocyanate groups exemplified above.
The amount of the crosslinking agent used to obtain the crosslinked resin is, for example, preferably from 1% by weight to 80% by weight, and more preferably from 3% by weight to 60% by weight with respect to the resin of the core particles.

The weight average molecular weight of the core particle resin is preferably 1,000 to 1,000,000, more preferably 10,000 to 200,000.

Examples of the colorant include organic or inorganic pigments, oil-soluble dyes, etc., for example, magnetic powders such as magnetite and ferrite, carbon black, titanium oxide, magnesium oxide, zinc oxide, phthalocyanine copper-based cyan colorants, azo-based materials Known colorants such as a yellow color material, an azo magenta color material, a quinacridone magenta color material, a red color material, a green color material, and a blue color material can be used. Specifically, 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 122, C.I. I. Pigment red 57: 1, C.I. I. Pigment yellow 97, C.I. I. Pigment blue 15: 1, C.I. I. Pigment Blue 15: 3, etc. are exemplified as typical examples.

The blending amount of the colorant is preferably 10% by mass or more and 99% by mass or less, and more preferably 30% by mass or more and 99% by mass or less with respect to the resin of the core particles.

The core particles may contain other compounding materials.
Examples of other compounding materials include charge control materials and magnetic materials.
As the charge control material, known materials used for electrophotographic toner materials can be used. 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.

As the magnetic material, a color-coated inorganic magnetic material or organic magnetic material is used as necessary. Further, a transparent magnetic material, in particular, a transparent organic magnetic material is more preferable because it hardly inhibits the coloring of the colored pigment and has a smaller specific gravity than the inorganic magnetic material.
Examples of the colored magnetic material (color-coated material) include small-diameter colored magnetic powder described in JP-A-2003-131420. A material provided with magnetic particles serving as nuclei and a colored layer laminated on the surface of the magnetic particles is used. The colored layer may be selected such that the magnetic powder is opaquely colored with a pigment or the like, but it is preferable to use, for example, a light interference thin film. This optical interference thin film is a thin film having a thickness equivalent to the wavelength of light made of an achromatic material such as SiO ₂ or TiO ₂ and selectively reflects the wavelength of light by optical interference in the thin film. It is.

-Coating layer-
The coating layer includes, for example, a resin (hereinafter referred to as “resin of the coating layer”).

The resin of the coating layer may be a non-crosslinked resin, but is preferably a crosslinked resin. In order to make the resin of the coating layer into a resin crosslinked body, for example, a polymerization component having a reactive group (crosslinkable group) as a polymerization component of the resin is polymerized to crosslink the resin. A method of adding and crosslinking the resin can be mentioned.

The resin of the coating layer is preferably copolymerized with a polymerization component having a silicone chain as a polymerization component of the resin from the viewpoint of improving the dispersibility of the electrophoretic particles.
Specifically, as the resin for the coating layer, for example, a polymerization component having a silicone chain, a polymerization component having a reactive group, and a polymerization component having a chargeable group and other polymerization components, if necessary, Examples of the resin include a copolymer.

As the polymerization component having a silicone chain (monomer having a silicone chain), for example, the same as the polymerization component having a silicone chain (that is, a silicone macromer) described as a polymerization component of a specific polymer compound contained in the surface layer. Things.
The polymerization component having a reactive group (crosslinkable group) is the same as the polymerization component having a reactive group (crosslinkable group) described as the polymerization component of the core particle resin.
In addition, when the polymerization component which has a reactive group is used as a polymerization component of resin of such a coating layer, the resin itself of a coating layer will bridge | crosslink and a coating layer will become a resin crosslinked body. In addition, the coating layer is coated on the core particle in a state where the reactive group of the resin of the coating layer is bonded to the functional group on the surface of the core particle.
Examples of the polymerization component having a chargeable group include the same as the polymerization component having a chargeable group described as the polymerization component of the core particle resin.

Other polymerization components include polymerization components that do not have a chargeable group.
The polymerization component having no chargeable group is the same as the polymerization component having no chargeable group described as the polymerization component of the core particle resin.

In the resin of the coating layer, the polymerization component having a silicone chain (that is, silicone macromer) is preferably 1% by mass or more and 90% by mass or less, more preferably 2% by mass or more and 80% by mass with respect to the total polymerization component. It is as follows.
The polymerization component having a reactive group is preferably 3% by mass or more and 80% by mass or less, more preferably 5% by mass or more and 60% by mass or less in terms of a mass ratio with respect to all the polymerization components.

Here, as a crosslinking agent for obtaining a resin crosslinked body, for example, a crosslinking agent such as an epoxy compound, a carboxyimide compound, and a blocked isocyanate can be used in the same manner as the crosslinking agent for converting the resin of the core particle into a crosslinked body. .
The amount of the crosslinking agent used to obtain the resin crosslinked body is, for example, preferably from 1% by mass to 80% by mass, and more preferably from 3% by mass to 60% by mass with respect to the resin of the coating layer.

The weight average molecular weight of the resin of the coating layer is preferably 500 to 1,000,000, more preferably 1,000 to 1,000,000.

The coating layer may contain other compounding materials.
Other compounding materials include, for example, styrenes such as styrene and chlorostyrene, monoolefins such as ethylene, propylene, butylene, and isoprene, vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate, and vinyl butyrate, and methyl acrylate. , Α-methylene aliphatic monocarboxylic esters such as ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate, vinyl Vinyl ethers such as methyl ether, vinyl ethyl ether, vinyl butyl ether, vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, vinyl isopropenyl ketone, hydroxyethyl (meth) acrylate, Alkoxyoxy-oligoethylene glycol (meth) acrylates such as droxybutyl (meth) acrylate, tetraethylene glycol monomethyl ether (meth) acrylate, polyethylene glycol one-terminal (meth) acrylate, (meth) acrylic acid and its salts, vinylsulfonic acid And a polymer of a known monomer such as a salt thereof, vinylpyrrolidone, or a copolymer thereof.

The coating layer has a coating amount on the surface of the core particles of, for example, 0.4% by mass or more and 15% by mass or less, and preferably 0.4% by mass or more and 6% by mass or less with respect to the core particles.

-Characteristics of migrating particles-
The average particle diameter (volume average particle diameter) of the migrating particles is, for example, 0.1 μm or more and 10 μm or less, but is selected according to the application and is not limited thereto.
The average particle size is measured using a Photo FPAR-1000 (dynamic light scattering type particle size distribution measuring device) manufactured by Otsuka Electronics Co., Ltd. and analyzed by the MARQUARD method.

-Manufacturing method of migrating particles-
An example of the method for producing the migrating particles includes, but is not limited to, the following production method.
First, the core particle resin, the colorant, and other compounding materials are mixed in the first solvent to prepare a mixed solution in which the core particle resin is dissolved.
Here, the first solvent is a good solvent capable of forming a dispersed phase in a second solvent described later (a poor solvent capable of forming a continuous phase), has a lower boiling point than the second solvent, and is a core particle resin. Is selected from solvents that dissolve.
Examples of the first solvent include water, isopropyl alcohol (IPA), methanol, ethanol, butanol, tetrahydrofuran, ethyl acetate, butyl acetate and the like.

Next, the obtained mixed liquid is mixed with the second solvent, stirred, and the mixed liquid is emulsified using the second solvent as a continuous phase to prepare an emulsified liquid.
Then, the first solvent in the emulsified liquid is removed (dried) by heating or the like to precipitate the core particle resin, and as a granular material containing the colorant and other compounding materials together with these, the core particles (to the second solvent) To obtain dispersed core particles).
Here, the second solvent is a poor solvent that can form a continuous phase with respect to the first solvent that becomes the dispersed phase, and is selected from solvents having a boiling point higher than that of the first solvent and in which the core particle resin is insoluble. .
Examples of the second solvent include a dispersion medium for dispersing the obtained electrophoretic particles.

Next, the resin of the coating layer and other compounding materials are mixed in a third solvent to prepare a mixed solution in which the resin of the coating layer is dissolved.
Here, the third solvent is also a good solvent that can form a dispersed phase in the second solvent (a poor solvent that can form a continuous phase), has a lower boiling point than the second solvent, and dissolves the resin of the coating layer. Select from the solvents to be used. The third solvent is preferably selected from solvents in which the core particle resin is insoluble.
Examples of the third solvent include water, isopropyl alcohol (IPA), methanol, ethanol, butanol, tetrahydrofuran, ethyl acetate, and butyl acetate.

Next, the obtained mixed liquid is mixed with the second solvent in which the core particles are dispersed and stirred to emulsify the mixed liquid using the second solvent as a continuous phase to prepare an emulsion.
Then, the third solvent in the emulsion is removed (dried) by heating, etc., and the resin of the coating layer is deposited on the surface of the core particles, and together with this, a coating layer containing other compounding materials is formed on the surface of the core particles To do.
Thereafter, when the resin contained in the core particles and the coating layer is cross-linked, a heat treatment for cross-linking the resin is performed.

In this way, electrophoretic particles having a coating layer formed on the surface of the core particles are obtained.

-Content of migrating particles-
The content of the migrating particles (the migrating particle group 34) (the content (% by mass) with respect to the total mass in the cell) is not particularly limited as long as the desired hue is obtained, and the cell thickness ( That is, it is effective for the display medium 12 to adjust the content by the distance between the display substrate 20 and the back substrate). That is, in order to obtain a desired hue, the content decreases as the cell becomes thicker, and the content increases as the cell becomes thinner. Generally, it is 0.01 mass% or more and 50 mass% or less.

-Colored suspended particle group Next, a colored suspended particle group is demonstrated. The colored floating particle group 36 is an uncharged particle group, includes colored particles having optical reflection characteristics different from that of the particle group 34, and functions as a reflecting member that displays a color different from that of the particle group 34. is there.

Specifically, the colored floating particle group 36 is, for example, a member that is colored in a color different from the color of the particle group 34 and causes the display medium 12 to display a color different from the color of the particle group 34. . In the present embodiment, the case where the colored suspended particle group 36 is white will be described, but the present invention is not limited to this color.

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

The colored floating particle group 36 is sealed between the substrates by, for example, an ink jet method.

The size of the cell in the display medium 12 is closely related to the resolution of the display medium 12, and the display medium 12 capable of displaying a higher resolution image is produced as the cell is smaller. The length of the substrate 20 in the plate surface direction is 10 μm or more and 1 mm or less.

In order to fix the display substrate 20 and the rear substrate 22 to each other via the gap member 24, fixing means such as a combination of bolts and nuts, a clamp, a clip, and a frame for fixing the substrate are used. Moreover, you may use fixing means, such as an adhesive agent, heat melting, and ultrasonic bonding.

The display medium 12 is, for example, a bulletin board that can store and rewrite images, a circular version, an electronic blackboard, an advertisement, a signboard, a flashing sign, an electronic paper, an electronic newspaper, an electronic book, a copier, a document sheet that is shared with a printer, Used for.

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

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

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

The control unit 18 stores in advance various programs such as a CPU (central processing unit) that controls the operation of the entire apparatus, a RAM (Random Access Memory) that temporarily stores various data, and a control program that controls the entire apparatus. It is good also as a microcomputer containing ROM (Read Only Memory).

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

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

Here, the case where the particle group 34 enclosed in the display medium 12 is black and is negatively charged will be described. In the following description, it is assumed that the dispersion medium 50 is transparent and the colored suspended particle group 36 is white. That is, in this embodiment, the case where the display medium 12 displays black or white by the movement of the particle group 34 will be described.

First, an initial operation signal indicating that the voltage is applied for a predetermined time so that the front electrode 40 becomes a negative electrode and the back electrode 46 becomes a positive electrode is output to the voltage application unit 16. When a negative electrode and a voltage equal to or higher than the threshold voltage at which the concentration variation ends is applied between the substrates, the particle group 34 charged on the negative electrode moves to the back substrate 22 side and reaches the back substrate 22 (FIG. 2 (A)).
At this time, the color of the display medium 12 visually recognized from the display substrate 20 side is visually recognized as white as the color of the colored floating particle group 36.

The predetermined time may be stored in advance in a memory such as a ROM (not shown) in the control unit 18 as information indicating the voltage application time in the voltage application in the initial operation. Then, when the process is executed, information indicating the predetermined time may be read.

Next, the polarity of the voltage applied between the substrates is reversed between the surface electrode 40 and the back electrode 46, and when the voltage is applied with the surface electrode 40 as the positive electrode and the back electrode 46 as the negative electrode, FIG. As shown in B), the particle group 34 moves to the display substrate 20 side and reaches the display substrate 20 side, and black display by the particle group 34 is performed.

Thus, in the display device 10 according to the present embodiment, the display is performed when the particle group 34 reaches the display substrate 20 or the back substrate 22 and adheres thereto. And the opposing surface of the display substrate 20 and the back substrate 22 has the surface layers 21 and 23 (surface layer) made of the specific polymer compound, so that the particles even if the particle group 34 moves and adheres to the opposing surface. The adhesion of the particles of the group 34 is suppressed. As a result, color reproducibility and high contrast are realized.

In the display device 10 (display medium 12) according to the present embodiment described above, in the display substrate 20 and the back substrate 22, the opposing surfaces of the support substrate 38 and the support substrate 44 are the specific polymer compound and have a polarity. It is preferable to have the surface layer 21 and the surface layer 23 comprised including the high molecular compound formed by superposing | polymerizing the polymerization component which has group.
Thereby, even when repeated display is performed, the state in which the migrating particle group 34 moves and adheres to the facing surface is maintained, and the memory property of the display is provided, while the facing of each migrating particle in the migrating particle group 34 Sticking to the surface is also suppressed.
The reason for this is not clear, but since the specific polymer compound is applied as the polymer compound contained in the surface layer, the release property to the migrating particle group 34 is expressed by the silicone chain, and the display substrate 20 and the back substrate While the migration of the migrating particles of the migrating particle group 34 is suppressed on the opposite surface 22, the polar group functions as a functional group that adsorbs the migrating particle group 34 (adsorptive functional group), and the display substrate 20 and the back surface This is considered because the state in which the migrating particle group 34 is attached to the opposite surface of the substrate 22 is easily maintained.

However, if the dispersion medium 50 in which the electrophoretic particle group 34 is dispersed contains a large amount of polar components other than water, each electrophoretic particle of the electrophoretic particle group 34 on the opposing surface of the display substrate 20 and the back substrate 22 over time. May occur, the voltage to be released from each substrate may increase, and the display stability may decrease.
Although this reason is not certain, it is because polar components other than water are adsorbed to the surface layer 21 and the surface layer 23, which are opposed surfaces of the display substrate 20 and the back substrate 22, in the dispersion medium 50. .

Therefore, in the display device 10 (display medium 12) according to the present embodiment, the content of polar components excluding water contained in the dispersion medium 50 is 0.01% by mass or less, preferably 0.005% by mass or less. Is preferred.
Thereby, the display device 10 (display medium 12) according to the present embodiment maintains the repeated stability of display.

Here, the “polar component excluding water” that causes the repeated stability of display to decrease is, for example, a member in contact with the dispersion medium 50 (for example, the surface layer 21, the surface layer 23, the surface layer 25, and the electrophoretic particles). The polymerization component having an unreacted polar group contained in the resin (polymer) contained in is dissolved in the dispersion medium 50. In other words, the “polar component excluding water” is an unreacted low molecular weight component among the polymerization components having a polar group that is blended to function as a functional functional group (for example, an adsorptive functional group or a chargeable group). The component eluted from the member in contact with the dispersion medium 50 into the dispersion medium 50.
The “polar component excluding water” refers to a component in which a polar component other than the resin (polymer) constituting the migrating particles is eluted into the dispersion medium 50, a residual solvent, and the like.
Of the polar components, “water” does not cause the repeated stability of the display to deteriorate because the silicone oil contains approximately 140 ppm of water in normal use conditions and is almost saturated. Therefore, it is not necessary to consider the content.

And as a structure which reduces the polar component except this water within the said range, the following structures are mentioned, for example.

1) A configuration in which a resin (polymer) contained in a member in contact with the dispersion medium 50 has a high molecular weight (for example, a weight average molecular weight of 100,000 or more). In this configuration, in the resin itself contained in the member in contact with the dispersion medium 50, the polymerization component having an unreacted polar group is easily reduced. As a result, the polar component eluted from the member in contact with the dispersion medium 50 to the dispersion medium 50 Is considered to be reduced.

2) A configuration in which a resin (polymer) contained in a member in contact with the dispersion medium 50 is a crosslinked body. In this configuration, since a so-called three-dimensional network structure in which polymer (polymer) polymer chains are three-dimensionally connected is taken, when the polar component eluted from the member in contact with the dispersion medium 50 to the dispersion medium 50 is reduced. Conceivable.

3) In a resin (polymer) contained in a member in contact with the dispersion medium 50, the polar group of the resin (polymer) is oriented on the side in contact with the dispersion medium 50. In this configuration, in the resin (polymer), a reduction in the amount of the polymerization component itself having a polar group that functions as a functional functional group (for example, an adsorptive functional group or a chargeable group) is realized. It is considered that the polymerization component having a polar group is easily reduced, and as a result, the polar component eluted from the member in contact with the dispersion medium 50 to the dispersion medium 50 is reduced.
In addition, as a method for orienting the polar group of the resin (polymer) on the side in contact with the dispersion medium 50, for example, a method of orienting by an electric field or a magnetic field, or by spreading the resin on a gas-liquid or two-liquid interface. And a method of forming a layer on the substrate.

4) In addition, a configuration in which the dispersion medium 50 itself is purified by a method such as reprecipitation and recrystallization, and polar components other than water contained in the dispersion medium 50 before sealing between the substrates are reduced.

The content of “polar components excluding water” is measured as follows.
First, a part of the dispersion medium 50 is collected from the produced display device 10 (display medium 12) and used as a measurement sample.
Using the collected measurement sample, the solid and the liquid are separated by an operation such as centrifugation. Current measurement is performed on the separated liquid, and the content of polar components excluding water is measured by comparison with a calibration curve prepared in advance.

Here, in the manufacturing process (manufacturing method) of the display device 10 (display medium 12), the content of the polar component excluding water is measured as a step of discriminating the final product from the non-defective product or the defective product. It may be determined whether the content of polar components excluding water contained is within the above range.

(Second Embodiment)
FIG. 3 is a schematic configuration diagram of a display device according to the second embodiment. FIG. 4 is a diagram schematically showing a relationship between an applied voltage and a moving amount (display density) of particles in the display device according to the second embodiment. FIG. 5 is an explanatory diagram schematically showing the relationship between the voltage mode applied between the substrates of the display medium and the particle movement mode in the display device according to the second embodiment.

The display device 10 according to the second embodiment is a form in which two or more kinds of particle groups are applied. Two or more kinds of particle groups are all charged with the same polarity.

As shown in FIG. 3, the display device 10 according to the present embodiment includes a display medium 12, a voltage application unit 16 that applies a voltage to the display medium 12, and a control unit 18.
Note that the display device 10 according to the present embodiment has substantially the same configuration as the display device 10 described in the first embodiment, and thus the same reference numerals are given to the same configuration and detailed description thereof is omitted.

The display medium 12 holds the display substrate 20 serving as an image display surface, the back substrate 22 facing the display substrate 20 with a gap, and holds the substrate between the display substrate 20 and the back substrate 22 at a predetermined interval. A gap member 24 that divides the substrate into a plurality of cells, a particle group 34 enclosed in each cell, and a colored suspended particle group 36 having optical reflection characteristics different from the particle group 34 are included.
The opposing surfaces of the display substrate 20 and the back substrate 22 are charged as described in the first embodiment, and the surface layer 21 and the surface layer 23 are provided on the opposing surfaces.

In this embodiment, a plurality of types of particle groups 34 having different colors are dispersed in the dispersion medium 50 as the particle group 34.

In the present embodiment, the description will be made on the assumption that the yellow particle group 34Y, the magenta magenta particle group 34M, and the cyan cyan particle group 34C are dispersed as the three types of particle groups 34. Not limited to.
The plurality of types of particle groups 34 are particle groups that perform electrophoresis between substrates, and the absolute value of the voltage required to move in accordance with the electric field is different for each color particle group. That is, each color particle group 34 (yellow particle group 34Y, magenta particle group 34M, and cyan particle group 34C) has a voltage range necessary for moving each color particle group 34 for each color. Are different.

As each particle of the plurality of types of particle groups 34 having different absolute values of voltages necessary to move according to the electric field, for example, among the materials included in the particle group 34 described in the first embodiment, for example, It can be obtained by preparing particle dispersions each containing particles having different charge amounts by mixing the charge control agent and the amount of magnetic powder, the type and concentration of the resin constituting the particles, and the like.

Here, as described above, in the display medium 12 according to the present embodiment, the yellow particle group 34Y, the magenta particle group 34M, and the cyan particle group 34C having different colors are dispersed as the three types of particle groups 34. These plural types of particle groups 34 have different absolute values of voltages necessary for moving in accordance with the electric field in the respective color particle groups.

In the present embodiment, the absolute value of the voltage when each of the three color particle groups, the magenta magenta particle group 34M, the cyan cyan particle group 34C, and the yellow yellow particle group 34Y, starts moving. In the following description, it is assumed that the magenta magenta particle group 34M is | Vtm |, the cyan cyan particle group 34C is | Vtc |, and the yellow yellow particle group 34Y is | Vty |. Also, the absolute value of 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 each color particle group 34. Assuming 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 | <| Description will be made assuming that the relationship is Vtm | <| Vdm | <| Vty | <| Vdy |.

Specifically, as shown in FIG. 4, for example, the three types of particle groups 34 are dispersed in the dispersion medium 50 in a state of being charged with the same polarity, and voltages necessary for moving the cyan particle groups 34C. Absolute value of range | Vtc ≦ Vc ≦ Vdc | (absolute value of a value between Vtc and Vdc), absolute value of voltage range necessary for moving magenta particle group 34M | Vtm ≦ Vm ≦ Vdm | (from Vtm The absolute value of the value between Vdm) and the absolute value of the voltage range necessary to move the yellow particle group 34Y | Vty ≦ Vy ≦ Vdy | (the absolute value of the value between Vty and Vdy) are in this order. It is set to be large without overlapping.

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

That is, in this embodiment, the particle groups 34 of each color are independently driven by setting the voltage ranges necessary for moving the particle groups 34 of each color so as not to overlap.

The “voltage range necessary for moving the 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. It shows the voltage range until it disappears and the display density is saturated.
The “maximum voltage necessary for moving almost all the particle groups 34” means that even if the voltage and the 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 voltage.
Further, “almost all” means that there is a variation in the characteristics of the particle groups 34 of the respective colors, so that some of the characteristics of the particle groups 34 are so different that they 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.
The “display density” is a color density on the display surface side measured with a reflection densitometer of an optical density (Optical Density = 0D) reflection densitometer 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 the present embodiment, a voltage is applied from 0 V between the display substrate 20 and the rear substrate 22 to gradually increase the voltage value of the applied voltage, and the voltage applied between the substrates is When + Vtc is exceeded, 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 34C in the display medium 12 stops.

When the voltage value is further increased and the voltage applied between the display substrate 20 and the back 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 display substrate 20 and the back 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 contrary, when a negative voltage is applied from 0V to the display substrate 20 and the back 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 cyan particle group 34C between the substrates. Furthermore, when the absolute value of the voltage value is increased and the voltage applied between the display substrate 20 and the back substrate 22 becomes −Vdc or more, the change in display density due to the movement of the cyan particle group 34C in the display medium 12 stops. .

When the negative voltage is further applied by increasing the absolute value of the voltage value, and the voltage applied between the display substrate 20 and the back substrate 22 exceeds the absolute value of −Vtm, the magenta particles are displayed on the display medium 12. A change in display density due to movement of the group 34M begins to appear. When the absolute value of the voltage value is further increased and the voltage applied between the display substrate 20 and the back 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.

When the absolute value of the voltage value is further increased and a negative voltage is applied, and the voltage applied between the display substrate 20 and the rear substrate 22 exceeds the absolute value of −Vty, the yellow particles in the display medium 12 A change in the display density starts to appear due to the movement of 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 34Y in the display medium 12 stops.

That is, in the present embodiment, as shown in FIG. 4, the voltage applied between the substrates is in the range of −Vtc to + Vtc (voltage range | Vtc | or less) between the display substrate 20 and the back substrate 22. Is applied to the 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, the movement of the particles does not occur. I can say that. When a voltage higher than the absolute value of the voltage + Vtc and the voltage −Vtc is applied between the substrates, the display density of the display medium 12 changes so as to change with respect to the cyan particle group 34C among the three color particle groups 34. When the voltage of −Vdc and the absolute value | Vdc | of the voltage Vdc is applied, the display density per unit voltage does not change.

Further, when a voltage that is applied between the substrates is between −Vtm and + Vtm (voltage range | Vtm | or less) is applied between the display substrate 20 and the back substrate 22, the display medium 12. 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 is changed does not occur. When a voltage higher than the absolute values 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 such an extent that the particles move to the extent that occurs, and the display density changes when a voltage greater than the absolute value | Vdm | of the voltage −Vdm and the voltage Vdm is applied. Disappear.

Further, when a voltage that is applied between the substrates is between −Vty and + Vty (voltage range | Vty | or less) is applied between the display substrate 20 and the back substrate 22, It can be said that there is no movement of the particles of the yellow particle group 34Y to the extent that the display density changes. When a voltage higher than the absolute values 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 higher than the absolute value | Vdy | of the voltage −Vdy and the voltage Vdy is applied, the display density does not change.

Next, the mechanism of particle movement when displaying an image on the display medium 12 will be described with reference to FIG.

For example, it is assumed that the display medium 12 is filled with the yellow particle group 34Y, the magenta particle group 34M, and the cyan particle group 34C described with reference to FIG.

In the following, the voltage applied between the substrates that is larger than the absolute value of the voltage necessary for the particles constituting the yellow particle group 34Y to start moving and less than or equal to the maximum voltage of the yellow particle group 34Y is referred to as “large voltage”. The voltage applied between the substrates that is larger than the absolute value of the voltage necessary for the particles constituting the magenta particle group 34M to start moving and is equal to or less than the maximum voltage of the magenta particle group 34M is referred to as “medium voltage”. The voltage applied between the substrates that is larger than the absolute value of the voltage required for the particles constituting the cyan particle group 34C to start moving and below the maximum voltage of the cyan particle group 34C is referred to as a “small voltage”. To do.

Further, when a higher voltage is applied to the display substrate 20 side than the rear substrate 22 side, the respective voltages are referred to as “+ large voltage”, “+ medium voltage”, and “+ small voltage”, respectively. Further, when a higher voltage is applied to the back substrate 22 side than the display substrate 20 side, the respective voltages will be referred to as “−large voltage”, “−medium voltage”, and “−small voltage”, respectively. .

As shown in FIG. 5A, in the initial state, it is assumed that 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 (white display state). ) When a “+ high voltage” is applied between the display substrate 20 and the rear substrate 22 from this initial state, the magenta particle group 34M, the cyan particle group 34C, and the yellow particle group 34Y are formed as all the particle groups. Move to the display substrate 20 side. In this state, even if the voltage application is canceled, each particle group does not move while adhering to the display substrate 20 side, and subtractive color mixing (magenta) by the magenta particle group 34M, the cyan particle group 34C, and the yellow particle group 34Y. In this case, the black color is displayed by the subtractive color mixture of cyan and yellow. (See FIG. 5B).

Next, when a “−medium voltage” is applied between the display substrate 20 and the back substrate 22 from the state of FIG. 5B, among the particle groups 34 of all colors, the magenta particle group 34M and cyan The particle group 34 </ b> C moves to the back substrate 22 side. For this reason, since only the yellow particle group 34Y is attached to the display substrate 20 side, yellow display is performed (see FIG. 5C).

Further, when “+ small voltage” is applied between the display substrate 20 and the back substrate 22 from the state of FIG. 5C, the magenta particle group 34M and the cyan particle group 34C moved to the back substrate 22 side. The cyan particle group 34C moves to the display substrate 20 side. For this reason, the yellow particle group 34Y and the cyan particle group 34C are attached to the display substrate 20 side, and green is displayed by the subtractive color mixture of yellow and cyan (see FIG. 5D).

When a “−small voltage” is applied between the display substrate 20 and the back substrate 22 from the state of FIG. 5B, among all the particle groups 34, the cyan particle group 34C is on the back substrate 22 side. Move to. For this reason, since the yellow particle group 34Y and the magenta particle group 34M are attached to the display substrate 20 side, red display is performed by additive mixing of cyan and magenta (see FIG. 5I).

On the other hand, when “+ medium voltage” is applied between the display substrate 20 and the back substrate 22 from the initial state shown in FIG. 5A, all the particle groups 34 (magenta particle group 34M, cyan particle group 34C) are applied. , And the yellow particle group 34Y), the magenta particle group 34M and the cyan particle group 34C move to the display substrate 20 side. For this reason, since the magenta particle group 34M and the cyan particle group 34C are attached to the display substrate 20 side, blue is displayed by the subtractive color mixing of magenta and cyan (see FIG. 5E).

When a “−small voltage” is applied between the display substrate 20 and the back substrate 22 from the state of FIG. 5E, the magenta particle group 34M and the cyan particle group 34C attached to the display substrate 20 side. Among them, the cyan particle group 34C moves to the back substrate 22 side.
Therefore, only the magenta particle group 34M is attached to the display substrate 20 side, so that a magenta color is displayed (see FIG. 5F).

When a “−large voltage” is applied between the display substrate 20 and the back substrate 22 from the state of FIG. 5F, the magenta particle group 34M adhering to the display substrate 20 side is moved to the back substrate 22 side. Moving.
For this reason, since nothing is attached to the display substrate 20 side, white is displayed as the color of the colored suspended particle group 36 (see FIG. 5G).

When a “+ small voltage” is applied between the display substrate 20 and the back substrate 22 from the initial state shown in FIG. 5A, all the particle groups 34 (magenta particle group 34M, cyan particle group) are applied. 34C and the yellow particle group 34Y), the cyan particle group 34C moves to the display substrate 20 side. For this reason, the cyan particle group 34C adheres to the display substrate 20 side, so that a cyan color is displayed (see FIG. 5H).

Further, when a “−high voltage” is applied between the display substrate 20 and the back substrate 22 from the state shown in FIG. 5I, all the particle groups 34 are transferred to the back substrate as shown in FIG. It moves to the 22 side and a white display is made.
Similarly, when a “−high voltage” is applied between the display substrate 20 and the back substrate 22 from the state shown in FIG. 5D, all the particle groups 34 appear on the back surface as shown in FIG. Moving to the substrate 22 side, white display is performed.

In the present embodiment, by applying a voltage corresponding to each particle group 34 between the substrates, the desired particles are selectively moved according to the electric field generated by the voltage, so that particles of colors other than the desired color are dispersed. The movement in the medium 50 is suppressed, and the color mixture in which colors other than the desired color are mixed is suppressed, and color display is performed. In addition, if the absolute value of the voltage required for each particle group 34 to move according to the electric field is different from each other, even if the voltage ranges necessary for moving according to the electric field overlap with each other, clear color display is possible. However, when the voltage ranges are different from each other, color mixing is further suppressed and color display is realized.

Further, by dispersing the three color particle groups 34 of cyan, magenta, and yellow in the dispersion medium 50, cyan, magenta, yellow, blue, red, green, and black are displayed, and white colored floating particle groups A white color is displayed by 36 and a specific color display is realized.

Thus, also in the display device 10 according to the present embodiment, as shown in the display device 10 described in the first embodiment, the particle group 34 reaches the display substrate 20 or the back substrate 22 and adheres to display. Is called. And the opposing surface of the display substrate 20 and the back substrate 22 has the surface layers 21 and 23 (surface layer) made of the specific polymer compound, so that the particles even if the particle group 34 moves and adheres to the opposing surface. The adhesion of the particles of the group 34 is suppressed. As a result, color reproducibility and high contrast are realized.

The disclosures of Japanese application 2012-092466 and Japanese application 2012-092468 are incorporated herein by reference in their entirety.
All documents, patent applications, and technical standards mentioned in this specification are to the same extent as if each individual document, patent application, and technical standard were specifically and individually described to be incorporated by reference, Incorporated herein by reference.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples.

[Measuring method]
-Measurement of volume average primary particle size of particles-
The volume average primary particle diameter of the particles was measured using a Coulter Multisizer-II type (manufactured by Beckman Coulter, Inc.) with an aperture diameter of 50 μm. At this time, the measurement is performed after the particles are dispersed in an electrolyte aqueous solution (Isoton aqueous solution, manufactured by Beckman Coulter, Inc.) and dispersed by ultrasonic waves for 30 seconds or more.
As a measuring method, 0.5 to 50 mg of a measurement sample is added to 2 ml of a 5% aqueous solution of a surfactant, preferably sodium alkylbenzenesulfonate as a dispersant, and this is added to 100 to 150 ml of the electrolytic solution. The electrolytic solution in which the measurement sample is suspended is subjected to a dispersion treatment for 1 minute with an ultrasonic disperser, and the particle size distribution of the particles is measured. The number of particles to be measured is 50,000.
For the measured particle size distribution, a cumulative distribution is drawn from the smaller diameter side with respect to the divided particle size range (channel), and the particle size at which 50% is accumulated is defined as the volume average primary particle size.

-Measurement of glass transition temperature of resin contained in particles-
The glass transition temperature was measured according to JIS 7121-1987 using a differential scanning calorimeter (DSC-50 manufactured by Shimadzu Corporation). The melting temperature of the mixture of indium and zinc was used for temperature correction of the detection part of this apparatus, and the heat of melting of indium was used for correction of the amount of heat.
The particles were put in an aluminum pan as they were, and an aluminum pan containing particles and an empty aluminum pan for control were set, and measurement was performed at a heating rate of 10 ° C./min.
The glass transition temperature was defined as the temperature at the intersection of the extension line of the base line and the rising line in the endothermic part of the DSC curve obtained by the measurement.

Example A
[Preparation of colored floating particles (white particles)]
1) Preparation of core particles-Preparation of continuous phase-
The following materials were mixed and a polymer dispersant E1 was synthesized by radical solution polymerization (55 ° C./6 hours).
Silaplane FM-0711 (manufactured by JNC, weight average molecular weight Mn = 1,000): 36 g
-Methacrylic acid (manufactured by Aldrich): 0.35 g
・ Silicone oil KF-96L-2CS (manufactured by Shin-Etsu Chemical Co., Ltd.): 40g
・ Polymerization initiator V-65 (manufactured by Wako Pure Chemical Industries): 0.06 g
Dilution was performed using silicone oil KF-96L-2CS (manufactured by Shin-Etsu Chemical Co., Ltd.) so that the amount of the polymerization anti-soluble component was 3 g, and a solution A1 (continuous phase) containing the polymer dispersant E1 was prepared.

-Preparation of dispersed phase-
Add zirconia beads to a mixture of 10 g of styrene acrylic resin X-1220L (manufactured by Seiko PMC), 10 g of titanium dioxide TTO-55A (manufactured by Ishihara Sangyo Co., Ltd.), and 90 g of distilled water, and disperse with a rocking mill for 1 hour. To obtain solution B1 (dispersed phase).

-Emulsification and drying in liquid process-
80 g of solution A1 (continuous phase) and 20 g of solution B1 (dispersed phase) were mixed and emulsified at 20,000 rpm for 10 minutes using an omnihomogenizer GLH-115 to prepare an emulsion.
Next, the obtained emulsion is put into an eggplant flask, water is removed by heating and reducing to 65 ° C. and 10 mPa with an evaporator while stirring, and a particle dispersion in which titanium dioxide particles are dispersed in silicone oil is obtained. Obtained. The obtained dispersion was sedimented using centrifugation, the supernatant was removed, and toluene was added to prepare a particle solid concentration of 20% by mass to obtain a particle toluene dispersion C1.

2) Shelling process -Synthesis of shell resin-
・ Styrene (Wako Pure Chemical Industries, Ltd.): 70g
Silaplane FM-0721 (manufactured by JNC, weight average molecular weight Mw = 5000): 25 g
・ Methacrylic acid (manufactured by Tokyo Chemical Industry Co., Ltd.): 5g
・ Lauroyl peroxide (Aldrich): 1g
・ Toluene (Kanto Chemical Co., Inc.): 100g
After mixing each material with the said composition and heating at 75 degreeC for 6 hours, it was dripped in isopropyl alcohol (made by Kanto Chemical Co., Inc.), it refine | purified by the reprecipitation method, and white solid (shell resin) was obtained. The weight average molecular weight Mw of the obtained shell resin was 30000.

-Shelling process-
Preparation of titanium oxide particle dispersion ・ Shell resin: 10 g
-Particle toluene dispersion C1 (particle solid content concentration 20% by mass): 50 g
Each material was mixed with the above composition, and 200 g of silicone oil KF-96L-2CS (manufactured by Shin-Etsu Chemical Co., Ltd.) was added dropwise to deposit a shell resin. Then, the dispersion liquid of the colored floating particle group (white particle group) which consists of titanium oxide coat | covered with shell resin was obtained by removing toluene using an evaporator under 60 degreeC and 20 mbar.

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

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

-Particle preparation-
50 g of the above dispersed phase and 350 g of the above continuous phase were 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 (manufactured by Tokushu Kika Kogyo Co., Ltd.). As a result, an emulsion having an emulsion droplet diameter of 2 μm was obtained. This was dried using a rotary evaporator at a vacuum degree 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-96L-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): 50 g
・ Hydroxyethyl methacrylate (HEMA / Aldrich): 32 g
Monomer AMP-10G containing phenoxy group (manufactured by Shin-Nakamura Chemical Co., Ltd.): 18 g
-Monomer containing blocked isocyanate group-Karenz MOI-BP (manufactured by Showa Denko KK): 2g
・ Isopropyl alcohol (Kanto Chemical Co., Inc.): 200g
Polymerization initiator AIBN (2,2′-azobisisobutyronitrile, manufactured by Aldrich): 0.2 g
The product was purified using cyclohexane as a reprecipitation solvent and dried 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 above core particles was placed in a 200 mL eggplant flask, 15 g of silicone oil KF-96L-2CS was added, and the mixture was stirred and dispersed while applying ultrasonic waves. To this, 7.5 g of t-butanol, 22 g of the above shell resin solution, and 12.5 g of silicone oil KF-96L-2CS were sequentially added. 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, thereby forming a shell material. The crosslinking reaction was performed.
After cooling, 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-96L-2CS was repeated three times. Thus, 0.6 g of cyan (C) particle group was obtained.

[Preparation of red particles]
-Preparation of dispersion A-1A-
The following ingredients were mixed, and ball milling was performed for 20 hours with 10 mmφ zirconia balls to prepare dispersion A-1A.
・ Methyl methacrylate (manufactured by Aldrich): 53 parts by mass ・ 2- (diethylamino) ethyl methacrylate (manufactured by Aldrich): 0.3 part by mass ・ Red pigment Red 3090 (manufactured by Sanyo Dye): 1.5 parts by mass

-Preparation of dispersion A-1B-
The following components were mixed and pulverized with a ball mill by the method described in the above dispersion A-1A to prepare calcium carbonate dispersion A-1B.
・ Calcium carbonate: 40 parts by mass ・ Water: 60 parts by mass

-Preparation of 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: 20 g
・ Ethylene glycol dimethacrylate: 0.6g
-Polymerization initiator V601 (Dimethyl 2,2'-azobis (2-methylpropionate): Wako Pure Chemical Industries, Ltd.): 0.2 g
This was added to the mixed solution A-1C and emulsified with an emulsifier. Next, this emulsified liquid was put into 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 primary particle size of 13 μm.

-4 quaternary ammonium treatment
The obtained particles are dispersed in silicone oil KF-96L-1CS (manufactured by Shin-Etsu Chemical Co., Ltd.), and dodecyl bromide (quaternizing agent) is used, such as 2- (diethylamino) ethyl methacrylate used for particle preparation. Molar amount was added and 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 (R) particles. The glass transition temperature of the resin contained in the red (R) particle group was 145 ° C.

[Preparation of cyan / red / white mixture]
The white (W) particle group, the cyan (C) particle group, and the red (R) particle group are solid components of 0.1 g of the C particle group, 1.3 g of the R particle group, and 2 of the W particle group. A silicone dispersion KF-96L-2CS (manufactured by Shin-Etsu Chemical Co., Ltd.) was added to a liquid volume of 10 g, and the mixture was ultrasonically stirred to obtain a display dispersion.

<Example A1>
(Production of surface layer and display medium)
-Synthesis of polymer compound A1-
-(Meth) acrylic monomer 1 (hydroxyethyl methacrylate, HEMA, manufactured by Wako Pure Chemical Industries): 23 parts by mass-(Meth) acrylic monomer 2 (methacrylic acid, MAA, manufactured by Wako Pure Chemical Industries) 13 parts by mass Silicone macromer (Silaplane FM-0711, manufactured by JNC, weight average molecular weight Mw = 1000): 25 parts by mass Crosslinkable monomer (monomer containing a blocked isocyanate group, Karenz MOI-BP, Showa Denko): 38 mass Parts: Isopropyl alcohol (Wako Pure Chemical Industries, Ltd.): 45 parts by mass Polymerization initiator (azobisvaleronitrile, Wako Pure Chemicals: V-65): 0.1 parts by mass After carrying out the polymerization at 10 ° C. for 10 hours, the obtained product was purified and dried using hexane as a reprecipitation solvent to prepare the polymer compound A1. It was. The weight average molecular weight was 45,000. And the 4 mass% isopropyl alcohol solution of polymer compound A1 was prepared by melt | dissolving in isopropyl alcohol (made by Wako Pure Chemical Industries Ltd.).

-Production of display media-
A display medium was produced as follows.
An ITO film having a thickness of 50 nm was formed as an electrode on a supporting substrate made of glass having a thickness of 0.7 mm by a sputtering method. The electrode surface of the back substrate composed of this ITO / glass substrate was immersed in a 2% by mass aqueous solution of γ-aminopropyltriethoxysilane for 15 minutes, rinsed with pure water, and then dried at 120 ° C. for 30 minutes. Thereafter, a thin film was formed by spin coating using a 4 mass% isopropyl alcohol solution of the polymer compound A1, and then heated at 120 ° C. for 60 minutes. Thereby, a surface layer was formed. The surface layer had a thickness of 100 nm and was insoluble in various organic solvents such as dimethyl silicone oil (KF-96L-1CS manufactured by Shin-Etsu Chemical Co., Ltd.), acetone, and tetrahydrofuran (THF). The thickness of the surface layer was measured with a Dektak 6M step gauge (manufactured by Veeco).

Thereafter, a layer was applied using a photosensitive polyimide varnish (PROBIMIDE 7005, manufactured by Fuji Hunt Electronics Technology Co., Ltd.), followed by exposure and wet etching to form a gap member having a height of 100 μm and a width of 20 μm. A surface layer was formed on the surface of the gap member (cell side surface) by the same method as that for the back substrate.

After forming a heat-fusible adhesive layer on top of the gap member and filling the display dispersion liquid (mixed dispersion liquid of C particle group, R particle group, and W particle group), the same method as for the back substrate is used. A display substrate made of ITO / glass and having a surface layer formed is bonded to the back substrate so that the surfaces (electrode surfaces) on which the surface layers are formed face each other, and heat is applied. A medium was made.

-Measurement of surface layer wetting tension-
The wetting tension of the formed surface layer was measured according to JIS-K6768 (1999). The results are shown in Table 1 below.

-Particle sticking evaluation test-
Using the produced display medium, a potential difference of 15 V was applied between the electrodes for 5 seconds so that the electrodes on the surface substrate were negative. The dispersed positively charged cyan particle group and positively charged red particle group moved to the negative electrode, that is, the surface electrode side, and when observed from the display substrate side, black color was observed.
Thereafter, when a potential difference of 15 V is applied between the electrodes so that the surface electrode becomes positive, the positively charged cyan particle group and the positively charged red particle group move to the negative electrode, that is, the back electrode side, and display When observed from the substrate side, white color was observed.

Here, the degree of adhesion of the particle group to the surface layer was evaluated by the decrease in white reflectance after the black display and white display were repeated 100 times. Specifically, using a spectral luminance meter CM-2022 (manufactured by Minolta), the white reflectance Y1 at the first white display and the white reflectance Y100 after driving 100 times are measured and fixed. Was defined as “α (%) = (Y1−Y100) / Y1 × 100” and used as an evaluation index. Note that the luminous reflectance was used as the reflectance. The results are shown in Table 1 below.

<Example A2>
Evaluation was performed by forming a surface layer by the method described in Example A1 except that the composition of the polymer compound used in Example A1 was changed to the composition of the following polymer compound A2.
-Synthesis of polymer compound A2-
(Meth) acrylic monomer 1 (hydroxyethyl methacrylate, HEMA, manufactured by Wako Pure Chemical Industries, Ltd.): 65 parts by mass Silicone macromer (Silaplane FM-0711, manufactured by JNC, weight average molecular weight Mw = 1000): 28 masses Parts Crosslinkable monomer (monomers containing blocked isocyanate groups, Karenz MOI-BP, manufactured by Showa Denko KK): 7 parts by mass Isopropyl alcohol (manufactured by Wako Pure Chemical Industries, Ltd.): 45 parts by mass Polymerization initiator (azobis valero Nitrile, manufactured by Wako Pure Chemical Industries, Ltd .: V-65): 0.1 parts by mass

<Example A3>
A surface layer was formed and evaluated by the method described in Example A1 except that the composition of the polymer compound used in Example A1 was changed to the composition of the following polymer compound A3.
-Synthesis of polymer compound A3-
(Meth) acrylic monomer 1 (hydroxyethyl methacrylate, HEMA, manufactured by Wako Pure Chemical Industries): 17 parts by mass (meth) acrylic monomer 2 (methacrylic acid, MAA, manufactured by Wako Pure Chemical Industries, Ltd.) 6 parts by mass Silicone macromer (Silaplane FM-0711, manufactured by JNC, weight average molecular weight Mw = 1000): 22 parts by mass Crosslinkable monomer (monomer containing blocked isocyanate group, Karenz MOI-BP, manufactured by Showa Denko KK): 55 parts by mass Isopropyl alcohol (Wako Pure Chemical Industries, Ltd.): 45 parts by mass Polymerization initiator (Azobisvaleronitrile, Wako Pure Chemical Industries, Ltd .: V-65): 0.1 parts by mass

<Example A4>
The surface layer was formed by the method described in Example A1 except that the composition of the polymer compound used in Example A1 was changed to the composition of the following polymer compound A4 and the method for producing the display medium was changed. Evaluation was performed.
-Synthesis of polymer compound A4-
-(Meth) acrylic monomer 1 (hydroxyethyl methacrylate, HEMA, manufactured by Wako Pure Chemical Industries): 4 parts by mass-(Meth) acrylic monomer 3 (methyl methacrylate, MMA, manufactured by Wako Pure Chemical Industries): 3 masses Parts Silicone macromer (Silaplane FM-0711, manufactured by JNC, weight average molecular weight Mw = 1000): 3 parts by mass 1-methoxy-2-propanol (manufactured by Wako Pure Chemical Industries, Ltd.): 30 parts by mass Polymerization initiator (Azobisvaleronitrile, manufactured by Wako Pure Chemical Industries, Ltd .: V-65): 0.2 parts by mass

-Production of display media-
A display medium was produced by the method described in Example A1, except that the method for forming the surface layer was changed to the following method in “-Production of display medium” in Example A1.
For the surface layer, a cyclohexanone solution was prepared so that the polymer compound A4 was 4% by mass and Takenate D-160N (manufactured by Mitsui Chemicals) was 2% by mass as a crosslinkable monomer, and a thin film was formed by spin coating. It was formed by heating at 0 Pa 100 ° C. for 60 minutes. The surface layer had a thickness of 100 nm and was insoluble in various organic solvents such as dimethyl silicone oil (KF-96L-1CS manufactured by Shin-Etsu Chemical Co., Ltd.), acetone, and tetrahydrofuran (THF).

<Example A5>
A surface layer was formed and evaluated by the method described in Example A1, except that the composition of the polymer compound used in Example A1 was changed to the composition of the following polymer compound A5.
-Synthesis of polymer compound A5-
-(Meth) acrylic monomer 1 (hydroxyethyl methacrylate, HEMA, manufactured by Wako Pure Chemical Industries): 58 parts by mass-(Meth) acrylic monomer 2 (methacrylic acid, MAA, manufactured by Wako Pure Chemical Industries): 18 masses Parts Silicone macromer (Silaplane FM-0711, manufactured by JNC, weight average molecular weight Mw = 1000): 14 parts by mass Crosslinkable monomer (monomer containing blocked isocyanate group, Karenz MOI-BP, manufactured by Showa Denko KK): 9 Mass parts-Isopropyl alcohol (Wako Pure Chemical Industries, Ltd.): 45 parts by mass-Polymerization initiator (Azobisvaleronitrile, Wako Pure Chemical Industries, Ltd .: V-65): 0.1 parts by mass

<Example A6>
A surface layer was formed and evaluated by the method described in Example A1, except that the composition of the polymer compound used in Example A1 was changed to the composition of the following polymer compound A6.
-Synthesis of polymer compound A6-
-(Meth) acrylic monomer 1 (hydroxyethyl methacrylate, HEMA, manufactured by Wako Pure Chemical Industries): 31 parts by mass-Silicone macromer (VTT106, manufactured by Gelest, weight average molecular weight Mw = 550): 30 parts by mass-Crosslinkability Monomer (Monomer containing a blocked isocyanate group, Karenz MOI-BP, manufactured by Showa Denko KK): 51 parts by mass ・ Isopropyl alcohol (manufactured by Wako Pure Chemical Industries): 45 parts by mass ・ Polymerization initiator (azobisvaleronitrile, Wako Pure) Yakuhin Kogyo Co., Ltd .: V-65): 0.1 parts by mass

<Example A7>
A surface layer was formed and evaluated by the method described in Example A1 except that the composition of the polymer compound used in Example A1 was changed to the composition of the following polymer compound A7.
-Synthesis of polymer compound A7-
(Meth) acrylic monomer 1 (hydroxyethyl methacrylate, HEMA, manufactured by Wako Pure Chemical Industries, Ltd.): 52 parts by mass Silicone macromer (VTT106, manufactured by Gelest, weight average molecular weight Mw = 550): 68 parts by mass Monomer (Monomer containing a blocked isocyanate group, Karenz MOI-BP, manufactured by Showa Denko KK): 6 parts by mass Isopropyl alcohol (manufactured by Wako Pure Chemical Industries, Ltd.): 45 parts by mass Polymerization initiator (Azobisvaleronitrile, Wako Pure) Yakuhin Kogyo Co., Ltd .: V-65): 0.1 parts by mass

<Example A8>
A surface layer was formed and evaluated by the method described in Example A1 except that the composition of the polymer compound used in Example A1 was changed to the composition of the following polymer compound A8.
-Synthesis of polymer compound A8-
(Meth) acrylic monomer 2 (methacrylic acid, MAA, manufactured by Wako Pure Chemical Industries, Ltd.): 3.6 parts by mass Silicone macromer (Silaplane FM-0711, manufactured by JNC, weight average molecular weight Mw = 1000): 4 0.1 parts by mass Other polymerization components (styrene, manufactured by Wako Pure Chemical Industries, Ltd.): 2.9 parts by mass Crosslinkable monomer (glycidyl methacrylate, GMA, manufactured by Wako Pure Chemical Industries, Ltd .: 2.6 parts by mass) Isopropyl alcohol (Wako Pure Chemical Industries, Ltd.): 40 parts by mass Polymerization initiator (azobisvaleronitrile, Wako Pure Chemical Industries, Ltd .: V-65): 0.3 parts by mass

<Comparative Example A1>
A surface layer was formed and evaluated by the method described in Example A1, except that the composition of the polymer compound used in Example A1 was changed to the composition of the following polymer compound B1.
-Synthesis of polymer compound B1-
(Meth) acrylic monomer 1 (hydroxyethyl methacrylate, HEMA, manufactured by Wako Pure Chemical Industries, Ltd.): 71 parts by mass Silicone macromer (Silaplane FM-0711, manufactured by JNC, weight average molecular weight Mw = 1000): 29 masses Parts Isopropyl alcohol (Wako Pure Chemical Industries, Ltd.): 45 parts by mass Polymerization initiator (Azobisvaleronitrile, Wako Pure Chemical Industries, Ltd .: V-65): 0.1 parts by mass

<Comparative Example A2>
Evaluation was performed by forming a surface layer by the method described in Example A1, except that the composition of the polymer compound used in Example A1 was changed to the composition of the following polymer compound B2.
-Synthesis of polymer compound B2-
-(Meth) acrylic monomer 1 (hydroxyethyl methacrylate, HEMA, manufactured by Wako Pure Chemical Industries): 66 parts by mass-(Meth) acrylic monomer 2 (methacrylic acid, MAA, manufactured by Wako Pure Chemical Industries): 20 masses Part Silicone macromer (Silaplane FM-0711, manufactured by JNC, weight average molecular weight Mw = 1000): 4 parts by mass Crosslinkable monomer (monomer containing a blocked isocyanate group, Karenz MOI-BP, manufactured by Showa Denko KK): 10 Mass parts-Isopropyl alcohol (Wako Pure Chemical Industries, Ltd.): 45 parts by mass-Polymerization initiator (Azobisvaleronitrile, Wako Pure Chemical Industries, Ltd .: V-65): 0.1 parts by mass

<Comparative Example A3>
A surface layer was formed by the method described in Example A1, except that the composition of the polymer compound used in Example A1 was changed to the composition of the following polymer compound B3.
-Synthesis of polymer compound B3-
(Meth) acrylic monomer 1 (hydroxyethyl methacrylate, HEMA, manufactured by Wako Pure Chemical Industries, Ltd.): 19 parts by mass Silicone macromer (Silaplane FM-0711, manufactured by JNC, weight average molecular weight Mw = 1000): 49 masses Parts Crosslinkable monomer (monomers containing blocked isocyanate group, Karenz MOI-BP, Showa Denko KK): 33 parts by mass Isopropyl alcohol (Wako Pure Chemical Industries, Ltd.): 45 parts by mass Polymerization initiator (azobis valero Nitrile, manufactured by Wako Pure Chemical Industries, Ltd .: V-65): 0.1 part by mass However, in Comparative Example A3, the polymer compound B3 gelled, and the surface layer could not be formed. Therefore, “measurement of surface layer wetting tension” and “particle adhesion evaluation test” could not be performed.

<Comparative Example A4>
A surface layer was formed by the method described in Example A1, except that the composition of the polymer compound used in Example A1 was changed to the composition of the following polymer compound B4.
-Synthesis of polymer compound B4-
(Meth) acrylic monomer 1 (hydroxyethyl methacrylate, HEMA, manufactured by Wako Pure Chemical Industries, Ltd.): 10 parts by mass Silicone macromer (Silaplane FM-0711, manufactured by JNC, weight average molecular weight Mw = 1000): 19 masses Parts Crosslinkable monomer (monomers containing blocked isocyanate group, Karenz MOI-BP, Showa Denko KK): 71 parts by mass Isopropyl alcohol (Wako Pure Chemical Industries, Ltd.): 45 parts by mass Polymerization initiator (azobis valero Nitrile, manufactured by Wako Pure Chemical Industries, Ltd .: V-65): 0.1 part by mass However, in Comparative Example A4, whitening of the surface layer occurred. Therefore, “measurement of surface layer wetting tension” and “particle adhesion evaluation test” were not performed.

<Examples A9 to A26, Comparative Examples A5 and A6>
[Substrate surface layer material]
-Preparation of substrate surface layer materials a1 to a19-
Polymer compounds having silicone chains having compositions according to Table 2 and Table 3 were synthesized by radical solution polymerization, and these were used as substrate surface layer materials a1 to a19.

[substrate]
-Preparation of substrates b1 to b18 with surface layers and substrates bb1 and bb2 with surface layers for comparison-
The substrate surface layer material according to Table 2 and Table 3 was dissolved in a mixed solvent (toluene / tetrahydrofuran = 25/75 mass ratio solvent) to prepare a 4 mass% solution of the substrate surface layer material. The crosslinkable monomer (post-addition) agent was mixed in the part at the ratio shown in Table 2 and Table 3.
On the other hand, ITO (indium tin oxide) was formed as an electrode on a 0.7 mm thick glass substrate by sputtering to a thickness of 50 nm to prepare an ITO electrode substrate.
Then, the obtained solution was applied to the electrode surface of the ITO electrode substrate by spin coating (2000 rpm × 30 sec, 3500 rpm × 2 sec) and baked at 130 ° C. for 1 hour to form a surface layer having a thickness of 100 nm. The substrates b1 to b18 with surface layers and the substrates bb1 and bb2 with surface layers for comparison were obtained.

In the production of the display medium of Example A1, a display medium was produced in the same manner as in Example A1, except that the display substrate used was changed to the above-mentioned substrates b1 to b18 with surface layers and substrates bb1 and bb2 with comparative surface layers. Evaluation was performed in the same manner as in Example A1. The results are shown in Table 4.

Details of abbreviations and the like in Table 2 and Table 3 are as follows.
FM-0711: “Silaplane FM-0711 (manufactured by JNC)”, weight average molecular weight Mw = 1,000
・ X-22-2404: “X-22-2404 (manufactured by Shin-Etsu Chemical Co., Ltd.)”

-HEMA: 2-hydroxyethyl methacrylate-MAA: methacrylic acid-MMA: methyl methacrylate-CXMA: cyclohexyl methacrylate-DEAEMA: N, N-diethylaminoethyl methacrylate-A-SA: 2-acryloyloxyethyl succinate (Shin Nakamura (Chemical company)
MOI-BP: Isocyanate monomer having a blocked isocyanate group: 2-[(3,5-dimethylpyrazolyl) carbonylamino] ethyl methacrylate “Karenz MOI-BP (manufactured by Showa Denko KK)”
D-160N: Isocyanate compound “Takenate D-160 (Mitsui Chemicals)”
MX-270: Methylated urea compound “Nicalak MX-270 (manufactured by Sanwa Chemical Co., Ltd.)”

From the above results, it can be seen that the sticking of particles is suppressed in Example A as compared with Comparative Example A.

Example B
[Substrate surface layer material]
-Production of substrate surface layer materials A1 to A17-
Polymer compounds having silicone chains having compositions according to Tables 5 and 6 were synthesized by radical solution polymerization, and these were used as substrate surface layer materials A1 to A17.

[substrate]
-Production of substrates B1 to B17 with surface layers-
The substrate surface layer material according to Table 5 and Table 6 was dissolved in a mixed solvent (toluene / tetrahydrofuran = 25/75 mass ratio solvent) to prepare a 4% by mass solution of the substrate surface layer material. 2 parts by mass of a triisocyanate-based crosslinking agent (“Takenate D160N (manufactured by Takeda Pharmaceutical Co., Ltd.)”) was mixed with the part.
On the other hand, ITO (indium tin oxide) was formed as an electrode on a 0.7 mm thick glass substrate by sputtering to a thickness of 50 nm to prepare an ITO electrode substrate.
Then, the obtained solution was applied to the electrode surface of the ITO electrode substrate by spin coating (2000 rpm × 30 sec, 3500 rpm × 2 sec) and baked at 130 ° C. for 1 hour to form a surface layer having a thickness of 100 nm. Substrates B1 to B17 with a surface layer were obtained.

-Production of substrate BB1 with a surface layer for comparison-
The fluororesin was dissolved in a diluting fluorosolvent to prepare a 33% by mass solution of the fluororesin.
The obtained solution was applied to the electrode surface of the ITO electrode substrate similar to the substrate B1 with the surface layer by spin coating (500 rpm × 20 sec, 2500 rpm × 10 sec), baked at 130 ° C. for 1 hour, and a film thickness of 100 nm A surface layer with a comparative surface layer BB1 was obtained.

[Electrophoretic particles (dispersion liquid)]
-Preparation of cyan particles C1 (dispersion C1)-
45 parts by mass of styrene / acrylic resin A as the core particle resin, 5 parts by mass of methylated melamine resin (“MX-035 (manufactured by Sanwa Chemical Co.)”) as the crosslinking agent, and 26 cyan pigment PB15: 3 as the colorant 50% by weight of an aqueous dispersion containing Emasol SF Blue H524F (manufactured by Sanyo Dye) and 24.1 parts by weight of distilled water are mixed while heating to 60 ° C., and the ink solid content concentration is 15% and dried. The dispersed phase was prepared so that the subsequent pigment concentration was 50%.

Next, 3.5 parts by mass of surfactant KF-6028 (manufactured by Shin-Etsu Chemical Co., Ltd.) is dissolved in silicone oil KF-96L-2cs (manufactured by Shin-Etsu Chemical Co., Ltd.) to prepare 350 parts by mass of a continuous phase. 50 parts by mass of the above dispersed phase was added to the mixture, and emulsification was carried out for 10 minutes at a rotational speed of 10000 rpm and a temperature of 30 ° C. using an internal tooth tabletop dispersing machine ROBOMICS (manufactured by Tokushu Kika Kogyo). As a result, an emulsion having an emulsion droplet diameter of about 2 μm was obtained. This was dried using a rotary evaporator at a vacuum degree of 20 mbar and a water bath temperature of 40 ° C. for 18 hours.
Next, the sediment dispersion step using a centrifugal separator and the redispersion step using an ultrasonic washer are repeated three times to remove the excess surfactant KF-6028 and concentrate the core particle dispersion in silicone oil. 6 parts by mass of particles were obtained. The centrifugation conditions are 15 minutes at 6000 rpm.
As a result of SEM observation and image analysis of the obtained particles, the average particle diameter was 0.6 μm, CV value (index indicating monodispersity: Coefficient of Variation: CV [%] = (σ / D) × 100 (σ: standard deviation, D: average particle size)) was 25%.

Next, as each polymerization component, Silaplane FM-0721 (manufactured by JNC) is 1.7 parts by mass, Silaplane FM-0725 (manufactured by JNC) is 0.2 parts by mass, and hydroxyethyl methacrylate is 59.8 parts by mass. AMP-10G (manufactured by Shin-Nakamura Chemical Co., Ltd.) and 21.8 parts by mass of Karenz MOI-BP (manufactured by Showa Denko KK) were mixed and dissolved in 200 parts by mass of isopropyl alcohol. 0.2 parts by mass of AIBN (2,2′-azobis (isobutyronitrile)) as a polymerization initiator was dissolved in this, 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 by mass of the resin of the coating layer was dissolved in 20 parts by mass of t-butanol solvent to prepare a coating layer forming solution (shell solution).

Next, 1 part by mass of the above core particles was placed in a 200 mL eggplant flask, 15 parts by mass of silicone oil KF-96L-2cs was added, and the core particle dispersion was stirred and dispersed at 25 ° C. while applying ultrasonic waves. To this, 7.5 parts by mass of t-butanol, 22 parts by mass of the above coating layer forming solution (shell solution), and 12.5 parts by mass of silicone oil “KF-96L-2cs (manufactured by Shin-Etsu Chemical Co., Ltd.)” were sequentially added. It was. 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 heated in an oil bath with further stirring. First, heating is performed at 100 ° C. for 1 hour to remove residual moisture and residual t-butanol, followed by heating at 130 ° C. for 1.5 hours to remove the blocking group of the blocked isocyanate group, and thereby the coating layer A cross-linking reaction of the resin (shell resin) was performed.
After cooling, the silicone oil particle dispersion was subjected to a sedimentation step using a centrifuge and a redispersion step using an ultrasonic cleaner three times to remove excess resin (shell resin) of the coating layer. The finally obtained particles were 0.6 parts by mass.

Through the above steps, a dispersion of cyan particles (electrophoretic particles) C1 having a coating layer formed on the surface of the core particles was obtained.
The cyan particles (electrophoretic particles) C1 dispersed in the liquid are obtained as a cyan particle dispersion C1 (particle solid content of 5% by mass) dispersed in silicone oil by washing with silicone oil using a centrifuge. It was.
It was 600 nm as a result of measuring the average particle diameter of the cyan particle (electrophoretic particle) in the produced cyan particle dispersion.
In addition, the charged polarity of cyan particles (electrophoretic particles) in the cyan particle dispersion was positively charged as a result of encapsulating the dispersion between two electrode substrates and applying a DC voltage to evaluate the electrophoretic direction. It was.

-Preparation of cyan particles C2 to C6 (dispersions C2 to C6 thereof)-
According to Tables 7 and 8, cyan particles (electrophoretic particles) C2 to C6 (dispersions C2 to C6) are the same as cyan particles C1 (dispersion C1) except that the composition of the core particles and the coating layer is changed. Got.
As a result of evaluating the charging polarity of the cyan particles (electrophoretic particles) in the produced cyan particle dispersion by enclosing the dispersion between two electrode substrates and applying a DC voltage to evaluate the electrophoretic direction. The cyan particles C1 to C4 and C6 were negatively charged and positively charged.

-Preparation of comparative cyan particles CC1 (dispersion liquid CC1 thereof)-
A solution A was prepared by dissolving 3 parts by mass of silicone-modified polymer KP-545 (manufactured by Shin-Etsu Chemical Co., Ltd.) in 97 parts by mass of dimethyl silicone oil (KF-96L-2CS manufactured by Shin-Etsu Chemical Co., Ltd.).
Next, 10 parts by mass of a dimethylamine / epichlorohydrin polymer, 5 parts by mass of a water-dispersed pigment solution (Unipas cyan color, pigment concentration 20% by mass, manufactured by Ciba), and 85 parts by mass of pure water are mixed to prepare a solution B. It was adjusted.
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 suspension was decompressed (2 KPa), heated (70 ° C.) to remove moisture, and the concentration was adjusted, whereby comparative cyan particles (electrophoretic particles) CC1 were dispersed in silicone oil. Cyan particle dispersion CC1 (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.
In addition, the charged polarity of cyan particles (electrophoretic particles) in the cyan particle dispersion was positively charged as a result of encapsulating the dispersion between two electrode substrates and applying a DC voltage to evaluate the electrophoretic direction. It was.

[White particles W1]
-Preparation of dispersion AA1-
The following components were mixed and ball milling was performed for 20 hours with 10 mmφ zirconia balls to prepare dispersion AA.
<Composition>
・ Cyclohexyl methacrylate: 53 parts by mass. Titanium oxide: 45 parts by mass (white pigment: primary particle size 0.3 μm, Type CR63: manufactured by Ishihara Sangyo Co., Ltd.)
・ Cyclohexane: 5 parts by mass

-Preparation of charcoal dispersion AB-
The following components were mixed, and finely pulverized with a ball mill in the same manner as above to prepare a charcoal dispersion AB.
<Composition>
・ Calcium carbonate: 40 parts by mass ・ Water: 60 parts by mass

-Preparation of mixture AC-
The following components were mixed, degassed with an ultrasonic machine for 10 minutes, and then stirred with an emulsifier to prepare a mixed liquid AC.
<Composition>
-2% serogen 4.3 parts by mass-Charcoal cal dispersion AB: 8.5 parts by mass-20% saline: 50 parts by mass

Next, 35 parts by weight of dispersion AA, 1 part by weight of divinylbenzene, and 0.35 part by weight of polymerization initiator AIBN (azobisisobutyronitrile) are weighed, mixed, and deaerated with an ultrasonic machine. I did it. This was added to the liquid mixture AC and emulsified with an emulsifier.
Next, this emulsified liquid was put into a bottle, and a silicone bottle was put on it, and a vacuum needle was sufficiently deaerated using an injection needle and sealed with nitrogen gas.
Next, particles were prepared by reacting at 65 ° C. for 15 hours. After cooling, cyclohexane was removed from the dispersion with a freeze dryer at −35 ° C. and 0.1 Pa for 2 days. The obtained particle powder was dispersed in ion-exchanged water, calcium carbonate was decomposed with hydrochloric acid water, and filtered. Thereafter, it was washed with sufficient distilled water, and passed through a nylon sieve having openings of 20 μm and 25 μm to make the particle sizes uniform. This was dried to obtain white particles W1 having an average particle diameter of 20 μm.

[Examples B1 to B22, Comparative Examples B1 to B4]
In accordance with Table 9, two identical substrates with a surface layer were prepared and used as a first substrate and a second substrate. Then, using a 50 μm Teflon (registered trademark) sheet as a spacer, the second substrate was superimposed on the first substrate with the surface layers facing each other, and fixed with clips.
Next, according to Table 9, the white particles were mixed with the cyan particle dispersion so that the white particles were 10 parts by mass and the cyan particles were 5 parts by mass, and the mixture was injected into the gap between the substrates, and then sealed. An evaluation cell was produced.

After the evaluation cell was prepared and 12 hours passed, a part of the silicone oil (dispersion medium) was collected from the evaluation cell, and this was used as a measurement sample according to the method described above. The content of polar components excluding water was measured.

Next, using the produced evaluation cell, the first substrate is used as a display substrate, and the display surface is cyan (that is, cyan particles migrate to the first substrate side). A voltage of 15 V was applied to each electrode of the second substrate.

Thereafter, the first substrate is used as a display substrate, and the display surface is white (that is, cyan particles migrate to the second substrate side). A voltage was applied.
At this time, the white white density observed from the first substrate side was measured by X-Rite 404 and converted into white reflectance. The white reflectance at this time was defined as “initial white reflectance”.
Then, after the same operation was repeated 100 times, the white reflectance was measured in the same manner, and the white reflectance at this time was defined as “temporal white reflectance”.

After that, again, the first substrate is used as a display substrate, and the display surface becomes white (that is, cyan particles migrate to the second substrate side). A voltage of 15V was applied.

From the above results, it can be seen that in Example B, the decrease in white reflectance over time is suppressed as compared with Comparative Example B.

Details of abbreviations and the like in Tables 5 to 8 are as follows.
FM-0711: “Silaplane FM-0711 (manufactured by JNC)”, weight average molecular weight Mw = 1,000
FM-0721: “Silaplane FM-0721 (manufactured by JNC)”, weight average molecular weight Mw = 5,000
FM-0725: “Silaplane FM-0725 (manufactured by JNC)”, weight average molecular weight Mw = 10,000
・ X-22-2404: “X-22-2404 (manufactured by Shin-Etsu Chemical Co., Ltd.)”

· HEMA: 2-hydroxyethyl methacrylate · MAA: methacrylic acid · MMA: methyl methacrylate · CXMA: cyclohexyl methacrylate · DMAPAA: dimethylaminopropylacrylamide · A-SA: 2-acryloyloxyethyl succinate (manufactured by Shin-Nakamura Chemical Co., Ltd.) )
MOI-BP: Isocyanate monomer having a blocked isocyanate group: 2-[(3,5-dimethylpyrazolyl) carbonylamino] ethyl methacrylate “Karenz MOI-BP (manufactured by Showa Denko KK)”
D-160N: Isocyanate compound “Takenate D-160 (Mitsui Chemicals)”
MX-270: Methylated urea compound “Nicalak MX-270 (manufactured by Sanwa Chemical Co., Ltd.)”

Styrene / acrylic resin A: “X-345 (manufactured by Seiko PMC)” (the carboxylic acid of the acrylic moiety is ammonium chloride with 2-hydroxyethyldimethylammonium)
Acrylic resin B: Acrylic compound polymer “AW-36H (manufactured by Seiko PMC)” (acrylic carboxylic acid is ammonium chloride with aqueous ammonia)
Styrene / maleic acid resin C: Copolymer of styrene compound and maleic acid compound “X-1220L (manufactured by Seiko PMC)” (maleic acid is ammonium chloride with ammonia water)
・ Sulphonic acid resin D: Polymer containing 2-acrylamido-2-methylpropanesulfonic acid ・ CTX-809M: Fluorine resin “CTX-809M (manufactured by AGC)”
・ AMP-10G: Polymer of phenoxy compound ・ MX-035: Methylated melamine resin “MX-035 (manufactured by Sanwa Chemical Co., Ltd.)”
-H525F: Cyan pigment ("H525F (manufactured by Sanyo Dye)")

Claims

A pair of substrates having electrodes, at least one of which is translucent and disposed with a gap;
A dispersion medium sealed between the pair of substrates;
A group of particles dispersed in the dispersion medium and moving in the dispersion medium in response to an electric field formed between the pair of substrates;
(1) (meth) acrylic monomer of at least 10 mol% to 90 mol%, (2) silicone macromer of 1 mol% to 50 mol%, and (3) crosslinkability of 2 mol% to 70 mol% A polymer compound derived from a monomer (provided that the ratio is a ratio based on the total amount of the components (1), (2) and (3) (100 mol%)) A surface layer provided on at least one of the opposing surfaces of the substrate;
A display medium.
The display medium according to claim 1, wherein the surface layer has a surface wetting tension (JIS-K6768 / 1999) of 35 mN / m or less.
The display medium according to claim 1, wherein the polymer compound has a structural unit derived from at least one selected from compounds represented by the following structural formula as the silicone macromer.

[In the above structural formula, R 1 represents a hydrogen atom or a methyl group. R 1 ′ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. n represents a natural number. x represents an integer of 1 to 3. ]
The display medium according to any one of claims 1 to 3, wherein the dispersion medium has a content of polar components excluding water of 0.01% by mass or less.
A display medium according to any one of claims 1 to 4,
Voltage applying means for applying a voltage between the pair of substrates;
A display device comprising: