JP2015215375A - Method for manufacturing electrophoretic particle, electrophoretic particle, electrophoretic dispersion liquid, electrophoretic sheet, electrophoretic device, and electronic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing electrophoretic particles to which aimed dispersibility and chargeability are imparted, even when base particles having hydroxyl groups exposed on the surfaces thereof are used, by coupling a polymer to the surfaces, and to provide the electrophoretic particles, an electrophoretic dispersion liquid, an electrophoretic sheet, an electrophoretic device, and electronic equipment.SOLUTION: A method for manufacturing electrophoretic particles 1 comprising particles 2 and coating layers covering at least a part of the particles 2 is provided, the method including: a step of obtaining a mixture 85 by adding a compound (compound Icontaining a polymerization initiating group) to a plurality of particles 2 to connect the compound to the surfaces of the particles 2, where the content of the above compound in the mixture 85 excluding the particles 2 is controlled to 75 wt.% or more; and a step of obtaining the electrophoretic particles 1 by connecting a polymer 32 via the above compound to the surfaces of the particles 2 to form coating layers.

Description

  The present invention relates to a method for producing electrophoretic particles, an electrophoretic particle, an electrophoretic dispersion, an electrophoretic sheet, an electrophoretic apparatus, and an electronic apparatus.

  Generally, it is known that when an electric field is applied to a dispersion system in which fine particles are dispersed in a liquid, the fine particles move (migrate) in the liquid by Coulomb force. This phenomenon is called electrophoresis. In recent years, an electrophoretic display device that displays desired information (image) using this electrophoresis has attracted attention as a new display device.

  This electrophoretic display device has characteristics such as a display memory property and a wide viewing angle property in a state where voltage application is stopped, and a high-contrast display with low power consumption.

  In addition, since the electrophoretic display device is a non-light-emitting device, the electrophoretic display device has a feature that it is easier on the eyes than a light-emitting display device such as a CRT.

  As such an electrophoretic display device, a device in which electrophoretic particles are dispersed in a solvent is provided as an electrophoretic dispersion liquid disposed between a pair of substrates having electrodes.

  In the electrophoretic dispersion liquid having such a configuration, the electrophoretic particles include positively charged particles and negatively charged particles, so that a voltage is applied between a pair of substrates (electrodes). Thus, desired information (image) can be displayed.

  Here, as the electrophoretic particle, for example, a particle including a coating layer in which a polymer is connected to a base particle is used, and by providing such a coating layer (polymer), The electrophoretic particles can be dispersed and charged in the electrophoretic dispersion.

  In addition, the electrophoretic particles having such a configuration are manufactured as follows using, for example, an atom transfer radical polymerization reaction (ATRP).

  That is, base material particles are prepared, and on the surface of the base material particles, AMP particles including a shell body made of an organic polymer and encapsulating the base material particles in a cell shape are formed, and polymerization in which the shell body has a polymerization initiating group is formed. After binding the initiator, an electrophoretic particle is produced by providing a polymer (polymer) in which the monomer is polymerized by living radical polymerization starting from this polymerization initiating group (see, for example, Patent Document 1). .

  At this time, the polymerization initiator is bonded to the shell by using a polymerization initiator having a functional group reactive to the hydroxyl group when the shell exposes a hydroxyl group (—OH group) on the surface thereof. , By connecting between a hydroxyl group and a functional group.

  However, if hydroxyl groups are exposed from the surface of the shell, aggregation may occur between the AMP particles due to the occurrence of hydrogen bonds between the hydroxyl groups. When the polymerization initiator is bound (chemically modified) to the shell provided in the aggregated AMP particles as described above and the particle size distribution of the obtained electrophoretic particles is measured, there are cases where a plurality of peaks are shown. In order to obtain an electrophoretic display device with excellent display quality, it is necessary to perform a sorting operation in order to make the particle size of the electrophoretic particles uniform to some extent.

  Such a problem is not limited to AMP particles having a shell, but also occurs in particles that have a shell and expose hydroxyl groups on the surface thereof.

JP 2013-218036 A

  One of the objects of the present invention is an electrophoretic particle imparted with the desired dispersibility and chargeability by binding a polymer to the surface of the base particle, even if the surface of the substrate particle is exposed to a hydroxyl group. Method for producing electrophoretic particles capable of producing electrophoretic particles, electrophoretic particles imparted with such properties, highly reliable electrophoretic dispersion, electrophoretic sheet, electrophoretic device and electronic apparatus using such electrophoretic particles Is to provide.

Such an object is achieved by the present invention described below.
The method for producing electrophoretic particles of the present invention is a method for producing electrophoretic particles comprising particles that expose hydroxyl groups on the surface and a coating layer that covers at least a part of the particles,
When obtaining a mixture in which a compound having a functional group having reactivity with the hydroxyl group is added to and mixed with the plurality of particles, the content of the compound excluding the plurality of particles in the mixture is 75% by weight or more. A first step of linking the compound to the surface of the particles;
And a second step of obtaining electrophoretic particles by forming a coating layer by connecting a polymer to the surface of the particles via the compound.

  In this way, even if particles that expose hydroxyl groups on the surface are used, electrophoretic particles imparted with the desired dispersibility and chargeability can be obtained by deaggregating the particles and bonding the polymer to the surface. Can be manufactured.

  In the method for producing electrophoretic particles of the present invention, the plurality of particles are preferably obtained by drying an aqueous dispersion in which the plurality of particles are dispersed.

  The method for producing electrophoretic particles of the present invention is particularly preferably applied to a plurality of particles thus obtained.

  In the method for producing electrophoretic particles of the present invention, the functional group is preferably a halogenated carboxyl group or a halogenated sulfonic acid.

  Since these halogenated acidic groups have excellent reactivity with respect to hydroxyl groups, the compounds can be reliably linked to the surface of the particles.

  In the method for producing electrophoretic particles of the present invention, the compound is preferably a polymerization initiating group-containing compound having the functional group and a polymerization initiating group.

  As a result, the polymerization initiating group-containing compound can be reliably linked to the surface of the particles, and the monomer can be polymerized starting from the polymerization initiating group.

［式中、Ｒ^１およびＲ^２は、それぞれ独立して、水素、および炭素原子の数が１〜２０であり任意の−ＣＨ_２−が−Ｏ−またはシクロアルキレン基で置換されてもよいアルキル基から選択される基を表し、Ｘ^１は、塩素、臭素またはヨウ素を表す。］ In the method for producing electrophoretic particles of the present invention, the polymerization initiating group is preferably represented by the following general formula (1).

[Wherein, R ¹ and R ² each independently represent hydrogen, and alkyl having 1 to 20 carbon atoms, and arbitrary —CH ₂ — may be substituted with —O— or a cycloalkylene group. Represents a group selected from the group, and X ¹ represents chlorine, bromine or iodine. ]

  Thereby, the living radical polymerization which a polymerization initiating group and a monomer react can be advanced more efficiently.

  In the method for producing electrophoretic particles of the present invention, in the second step, the polymer is obtained by adding a monomer and a catalyst to the mixture and polymerizing the monomer by radical polymerization starting from the polymerization initiating group. Is preferably formed.

  Thereby, an electrophoretic particle having a coating layer made of a polymer on the surface of the particle is obtained.

［式中、Ｒは水素原子またはメチル基、Ｒ’は水素原子または炭素数１〜４のアルキル基、ｎは０以上の整数、ｘは１〜３の整数を表す。］ In the method for producing electrophoretic particles of the present invention, the monomer preferably contains a silicone macromonomer represented by the following general formula (I).

[Wherein, R represents a hydrogen atom or a methyl group, R ′ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, n represents an integer of 0 or more, and x represents an integer of 1 to 3. ]

  By using such a monomer, when the main component of silicon oil is used as the dispersion medium contained in the electrophoretic dispersion liquid, this monomer exhibits excellent affinity for the dispersion medium. Electrophoretic particles including a polymer obtained by polymerization of this monomer can be dispersed in a dispersion medium with excellent dispersibility.

  In the method for producing electrophoretic particles of the present invention, it is preferable that the compound further includes a charged compound having a functional group and positively or negatively charged in addition to the polymerization initiating group-containing compound.

  Thereby, when forming a polymer in the second step, even if a nonionic monomer is used alone without using a cationic monomer and an anionic monomer as a monomer, dispersibility and Electrophoretic particles imparted with chargeability can be reliably obtained.

The electrophoretic particles of the present invention are manufactured using the method for manufacturing electrophoretic particles of the present invention.
The electrophoretic particles are provided with the desired dispersibility and chargeability.

The electrophoretic dispersion liquid of the present invention is characterized by containing the electrophoretic particles of the present invention.
Thereby, it can be set as the electrophoretic dispersion liquid provided with the electrophoretic particle which exhibits both excellent dispersibility and mobility.

The electrophoretic sheet of the present invention comprises a substrate,
And a plurality of structures each containing the electrophoretic dispersion of the present invention.
Thereby, an electrophoretic sheet with high reliability is obtained.

The electrophoretic device of the present invention includes the electrophoretic sheet of the present invention.
Thereby, a highly reliable electrophoresis apparatus is obtained.

An electronic apparatus according to the present invention includes the electrophoresis apparatus according to the present invention.
As a result, a highly reliable electronic device can be obtained.

It is a longitudinal cross-sectional view which shows embodiment of the electrophoretic particle of this invention. It is a schematic diagram of the coating layer which the electrophoretic particle shown in FIG. 1 has. It is a schematic diagram for demonstrating the manufacturing method of the electrophoretic particle of this invention. It is the elements on larger scale which show the dispersion state of the mother particle which may occur in the aqueous dispersion liquid of FIG.3 (c), and the elements on larger scale which show one form of the particle | grains of FIG.3 (d). It is the elements on larger scale which show another dispersion state of the mother particle which may occur in the aqueous dispersion of FIG.3 (c), and the elements on larger scale which show another form of the particle | grain of FIG.3 (d). It is a schematic diagram for demonstrating the mechanism by which the aggregate which particle | grains aggregated is dissolved and the particle | grains which the polymerization initiator group containing compound connected on the surface are disperse | distributed in a mixture. FIG. 5 is a schematic diagram for explaining a mechanism in which an aggregate in which particles are aggregated is dissolved and particles in which a polymerization initiator group-containing compound and a polymerization initiator group-free compound are connected to the surface are dispersed in a mixture. It is a figure which shows typically the longitudinal cross-section of embodiment of an electrophoretic display apparatus. It is a schematic diagram which shows the operating principle of the electrophoretic display device shown in FIG. It is a perspective view which shows embodiment at the time of applying the electronic device of this invention to electronic paper. It is a figure which shows embodiment at the time of applying the electronic device of this invention to a display. It is a graph which shows the particle size distribution of the encapsulation mother particle which the polymerization initiating group containing compound in each example and each comparative example couple | bonded with the surface. It is a graph which shows the relationship between the standard deviation of the particle size distribution in each Example and each comparative example, and content of a polymerization initiating group containing compound. The graph which shows the relationship between the total area of what has a particle size of 1 micrometer or more among the encapsulation mother particle | grains which the polymerization initiator group containing compound in each Example and each comparative example couple | bonded with the surface, and content of a polymerization initiator group containing compound It is.

  Hereinafter, a method for producing electrophoretic particles, an electrophoretic particle, an electrophoretic dispersion, an electrophoretic sheet, an electrophoretic apparatus, and an electronic apparatus according to the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

  First, prior to explaining the method for producing electrophoretic particles of the present invention, electrophoretic particles produced by applying the method for producing electrophoretic particles of the present invention (electrophoretic particles of the present invention) will be described.

  In this embodiment, the electrophoretic particles produced by applying the method for producing electrophoretic particles of the present invention have particles and a coating layer covering at least a part of the particles. An example will be described in which a mother particle and a shell body made of an organic polymer and encapsulating the mother particle in a cell shape are provided, and the coating layer includes a polymer in which a monomer is polymerized starting from a polymerization initiating group.

<Electrophoretic particles>
FIG. 1 is a longitudinal sectional view showing an embodiment of the electrophoretic particles of the present invention, and FIG. 2 is a schematic diagram of particles and coating layers of the electrophoretic particles shown in FIG.

  The electrophoretic particle 1 has a particle 2 exposing a hydroxyl group on the surface, and a coating layer 3 provided on the surface of the particle 2.

  In this embodiment, the particle 2 has a configuration including a mother particle 21 and a shell 22 that wraps the mother particle 21 in a cell shape (capsule shape).

  The base particles (base particles) 21 mainly constitute the particles 2 and function as a core material (base material) of the particles 2.

  As shown in FIG. 2, the mother particle 21 has a perfect circular cross section. Thus, when the mother particle 21 has a perfect spherical shape, the cross-sectional shape of the particle 2 can also be a perfect circle as shown in FIG. Thereby, since the electrophoretic performance of each electrophoretic particle 1 can be made more uniform, the shape of the mother particle 21 is preferably selected. If the electrophoretic performance of each electrophoretic particle 1 can be made uniform, the mother particle 21 has an oval cross section, a polygonal shape such as a quadrangular shape, a pentagonal shape, and a hexagonal shape. It may also be an agglomerate obtained by agglomerating particles having such a shape.

  For such mother particles 21, for example, at least one of pigment particles, dye particles, resin particles, or composite particles thereof is preferably used. These particles are easy to manufacture.

  Examples of pigments constituting the pigment particles include black pigments such as carbon black, aniline black, and titanium black, white pigments such as titanium dioxide, antimony trioxide, barium sulfate, zinc sulfide, zinc white, and silicon dioxide, monoazo, and disazo. Azo pigments such as polyazo, yellow pigments such as isoindolinone, yellow lead, yellow iron oxide, cadmium yellow, titanium yellow, antimony, azo pigments such as monoazo, disazo, polyazo, quinacridone red, chrome vermilion, etc. Examples thereof include red pigments, blue pigments such as phthalocyanine blue, indanthrene blue, bitumen, ultramarine blue, and cobalt blue, and green pigments such as phthalocyanine green. Among these, one or a combination of two or more can be used.

  Examples of the dye material constituting the dye particles include azo compounds such as Oil Yellow 3G (manufactured by Orient Chemical Co.), azo compounds such as First Orange G (manufactured by BASF), Macrolex Blue RR (Bayer Co.). Anthraquinones such as Sumiblast Green G (Sumitomo Chemical Co., Ltd.), azo compounds such as Oil Brown GR (Orient Chemical Co., Ltd.), Oil Red 5303 (Arimoto Chemical Co., Ltd.) and Oil Red Azo compounds such as 5B (manufactured by Orient Chemical Co., Ltd.), anthraquinones such as oil violet # 730 (manufactured by Orient Chemical Co., Ltd.), azo compounds such as Sudan Black X60 (manufactured by BASF Corp.), an anthraquinone-based macrolex blue FR ( Bayer) and azo oil red XO Mixture of tho Chemical Co., Ltd.) and the like, can be used singly or in combination of two or more of them.

  Furthermore, examples of the resin material constituting the resin particles include acrylic resin, urethane resin, urea resin, epoxy resin, polystyrene, polyester, and the like, and one or more of these are combined. Can be used.

  The composite particles include, for example, those coated by coating the surface of pigment particles with a resin material, coated by coating the surface of resin particles with a pigment, and pigment and resin material. Examples thereof include particles composed of a mixture mixed at an appropriate composition ratio.

  In addition, the color of the electrophoretic particles 1 can be set to a desired color by appropriately selecting the types of pigment particles, resin particles, and composite particles used as the mother particles 21.

  The mother particles 21 are charged on the surface thereof so that the first polymerizable surfactant 61 can be oriented to the mother particles 21 when the shell 22 is formed in the method for producing electrophoretic particles described later. It is necessary to have. However, depending on the types of pigment particles, resin particles, and composite particles, they may not have a charge or the amount of charge may be insufficient. In this case, the polarity of the coupling agent, surfactant, etc. should be set in advance. It is preferable to give a charge to the surface of the mother particle 21 by performing a treatment for adsorbing the compound having the same.

  The shell 22 wraps the mother particle 21 in a cell shape. By providing the particle 2 with the shell 22 having such a configuration, the influence on the electrophoretic particle 1 due to the charge of the base particle (base particle) 21 can be accurately suppressed. Therefore, characteristics such as dispersibility and chargeability imparted to the electrophoretic particles 1 are changed depending on the charge of the particles 2 by setting the type and number of the polymers 32 connected to the shell 22. Can be accurately suppressed or prevented. That is, the electrophoretic particles 1 exhibit the desired characteristics such as dispersibility and chargeability regardless of the type of the mother particles 21.

  In the present embodiment, the shell 22 is composed of an organic polymer, and is not particularly limited as long as the organic polymer can wrap the particles 2 in a cell shape. It is preferable to form a network structure (linked structure) formed by cross-linking each other. Thereby, since the shell 22 can have excellent strength, peeling of the shell 22 from the particles 2 can be reliably suppressed.

  The shell body 22 having such a configuration includes, for example, a first polar group 611 and a hydrophobic group 612 having polarities opposite to the charge on the surface of the particle 2 in the aqueous dispersion 90 in which the particle 2 having a charge on the surface is dispersed. A first polymerizable surfactant 61 having a polymerizable group 613 is added and mixed, and then a second polymerization having a hydroxyl group, a hydrophobic group 622, and a polymerizable group 623, which are second polar groups 621. The active surfactant 62 is added and emulsified, and then a polymerization initiator is added to cause a polymerization reaction. This method will be described in detail in the method for producing electrophoretic particles described later.

  At least a part of the surface of the particle 2 (substantially the whole in the illustrated configuration) is covered with the covering layer 3.

  In this embodiment, the coating layer 3 has a configuration including a plurality of polymers 32 bonded to the surface of the shell 22 included in the particle 2.

  The polymer 32 is obtained by polymerizing a monomer starting from a polymerization initiating group-containing compound linked to the second polar group (hydroxyl group) 621 included in the shell 22, and the electrophoretic particles 1 in the electrophoretic dispersion described later. This is to make the characteristics of

  The polymerization initiating group-containing compound is provided with a polymerization initiating group, and becomes a starting point for polymerization when the monomers are sequentially bonded after being connected to the second polar group (hydroxyl group) 621 exposed from the surface of the shell 22. Is.

  This polymerization initiating group-containing compound has a functional group Z having reactivity with the second polar group (hydroxyl group) and a polymerization initiating group A. The detailed description thereof will be described later in the electrophoresis particles. This is done in the manufacturing method.

  The monomer has a polymerization group so that it can be polymerized by living radical polymerization, and is classified into a nonionic monomer, a cationic monomer, and an anionic monomer based on the properties imparted to the electrophoretic particles 1. In addition, as a polymeric group which a monomer has, the thing containing a carbon-carbon double bond like a vinyl group, a styryl group, and a (meth) acryloyl group is mentioned, for example.

  By using a monomer containing a nonionic monomer as a monomer and forming the polymer 32 by living radical polymerization, the polymer 32 has an excellent affinity for the dispersion medium contained in the electrophoretic dispersion described later. Will be shown. Therefore, the electrophoretic particles 1 including the polymer 32 can be dispersed in the electrophoretic dispersion liquid without agglomerating. That is, dispersibility characteristics can be imparted to the electrophoretic particles 1.

  Examples of such nonionic monomers include 1-hexene, 1-heptene, 1-octene, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, stearyl (meth) acrylate, lauryl ( (Meth) acrylate, decyl (meth) acrylate, isooctyl (meth) acrylate, isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, pentafluoro (meth) acrylate, silicone macromonomer represented by the following general formula (I), etc. Acrylic monomers, styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, 2-propylstyrene, 3-propylstyrene, 4-propylstyrene Down, 2-isopropyl styrene, 3-isopropyl styrene, 4-isopropyl styrene, and styrene-based monomers such as 4-tert-butylstyrene.

［式中、Ｒは水素原子またはメチル基、Ｒ’は水素原子または炭素数１〜４のアルキル基、ｎは０以上の整数、ｘは１〜３の整数を表す。］

[Wherein, R represents a hydrogen atom or a methyl group, R ′ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, n represents an integer of 0 or more, and x represents an integer of 1 to 3. ]

  Among these, the nonionic monomer is preferably a silicone macromonomer represented by the above general formula (I). By using such a nonionic monomer, the nonionic monomer is superior to the dispersion medium when a dispersion medium mainly containing silicon oil is used as the dispersion medium contained in the electrophoretic dispersion described later. Therefore, the electrophoretic particles 1 including the polymer 32 obtained by polymerizing a nonionic monomer can be dispersed in a dispersion medium with excellent dispersibility.

  In addition, by using a monomer containing a cationic monomer as a monomer and forming the polymer 32 by living radical polymerization, the polymer 32 is positively (plus) charged in the electrophoretic dispersion described later. . Therefore, in the electrophoretic dispersion liquid, the electrophoretic particles 1 including the polymer 32 are positively charged electrophoretic particles (positive electrophoretic particles). That is, the electrophoretic particles 1 can be imparted with a positive charging property.

  Examples of such a cationic monomer include those having an amino group in the structure, and specifically include benzyl (meth) acrylate, 2- (diethylamino) ethyl (meth) acrylate, 2- ( Trimethylammonium chloride) ethyl (meth) acrylate, 1,2,2,6,6-pentamethyl-4-piperidyl (meth) acrylate, 2,2,6,6-tetramethyl-4-piperidyl (meth) acrylate, 1 , 1,1,3,3,3-hexafluoroisopropyl (meth) acrylate, aminomethyl (meth) acrylate, aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N-ethyl-N -Phenylaminoethyl (meth) acrylate, N, N-dimethyl (meth) acrylic De, N, N-diethyl (meth) acrylamide, 4-vinylpyridine, methacrolein Lil choline chloride, and the like.

  In addition, by forming the polymer 32 by living radical polymerization using a monomer containing an anionic monomer as the monomer, the polymer 32 is negatively (negatively) charged in the electrophoretic dispersion described later. . Therefore, in the electrophoretic dispersion liquid, the electrophoretic particles 1 including the polymer 32 become negatively charged electrophoretic particles (negative electrophoretic particles). That is, the electrophoretic particles 1 can be imparted with a negative charging property.

  Examples of such an anionic monomer include those having a carboxyl group or a sulfonyl group in the structure, and specifically, (meth) acrylic acid, carboxymethyl (meth) acrylate, carboxyethyl (meth) ) Acrylate, vinyl benzoic acid, vinyl phenylacetic acid, vinyl phenyl propionic acid, vinyl sulfonic acid, sulfomethyl (meth) acrylate, 2-sulfoethyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, 2-methoxyethyl (meth) acrylate Etc.

  As described above, since the polymer 32 is formed by polymerization of various monomers, the degree of characteristics derived from the various monomers is desired for the polymer 32 by setting the number of structural units derived from these monomers. Can be set to

The polymer 32 obtained from the polymerization initiating group-containing compound and the monomer can be represented by a schematic diagram as shown in FIG. 2, where the monomer is represented by M and the polymerization initiating group-containing compound is represented by I ¹ .

  Such electrophoretic particles 1 are produced as follows by applying the method for producing electrophoretic particles of the present invention.

<Method for producing electrophoretic particles>
Hereinafter, the manufacturing method of the electrophoretic particle 1 will be described.

  In the method for producing the electrophoretic particle 1 described below, first, a particle (AMP particle) 2 in which a mother particle 21 is encapsulated by a shell 22 is obtained, and then a plurality of particles are formed on the surface of the particle 2. In this method, the electrophoretic particles 1 are obtained by forming (connecting) the polymer 32 to form the coating layer 3.

  FIG. 3 is a schematic diagram for explaining the method for producing electrophoretic particles of the present invention, and FIG. 4 (a) is a partially enlarged view showing a dispersion state of mother particles that can occur in the aqueous dispersion of FIG. 3 (c). FIG. 4 and FIG. 4B are partial enlarged views showing one embodiment of the particles of FIG. FIG. 5 (a) is a partially enlarged view showing another dispersion state of the mother particles that can occur in the aqueous dispersion of FIG. 3 (c), and FIG. 5 (b) is a diagram of the particles of FIG. 3 (d). It is the elements on larger scale which show another form. Furthermore, FIG. 6 is a schematic diagram for explaining a mechanism in which an aggregate in which particles are aggregated is dissolved and particles in which a polymerization initiator group-containing compound is connected to the surface are dispersed in the mixture.

In this embodiment, the method for producing the electrophoretic particle 1 includes [1] a step of dispersing the mother particle 21 having a charge on the surface in the aqueous dispersion 90, and [2] the charge of the mother particle 21 in the aqueous dispersion 90. Adding a first polymerizable surfactant 61 having a first polar group 611, a hydrophobic group 612, and a polymerizable group 613 having a polarity opposite to that of 64, and [3] the aqueous dispersion 90. Adding a second polymerizable surfactant 62 having a second polar group (hydroxyl group) 621, a hydrophobic group 622, and a polymerizable group 623, and emulsifying, and [4] polymerizing the aqueous dispersion 90. A step of obtaining a particle 2 in which the mother particle 21 is encapsulated by the shell 22 composed of an organic polymer by adding an initiator 80 to cause a polymerization reaction; [5] an aqueous solution containing the particle 2 By drying the dispersion 90, the particles 2 are dried. Obtaining a (aggregate) 86, [6] Drying the polymerization initiation group-containing compound I ¹ having the functional group Z and a polymerization initiator group A of the particles 2 having reactivity with a second polar group (hydroxyl group) 621 In the mixture 85 mixed with the product, the content of the polymerization initiating group-containing compound I ¹ excluding the dried product 86 (particle 2) is 75% by weight or more, and the polymerization initiating group-containing compound I ¹ is connected to the surface of the particle 2 A step of [7] adding the monomer M and the catalyst to the mixture 85 to form the polymer 32 to obtain the electrophoretic particles 1, and [8] a step of recovering the electrophoretic particles 1 from the mixture 85. [9] A step of drying the electrophoretic particles 1.

When the polymerization initiating group-containing compound I ¹ is connected to the surface of the particle 2 as in the above step [6], the dried product 86 in the mixture 85 of the dried product of the particle 2 and the polymerization initiating group-containing compound I ¹ ( Even if the content of the polymerization initiating group-containing compound I ¹ excluding the particles 2) is 75% by weight or more, the particles 2 that expose the second polar group (hydroxyl group) 621 on the surface are used. Electrophoretic particles 1 having a small number of peaks in the particle size distribution, preferably having only a single peak, can be produced. In addition, the content of the polymerization initiating group-containing compound I ¹ excluding the dried product 86 (particle 2) in the mixture 85 may be 75% by weight or more when starting the reaction, and the polymerization initiating group as the reaction proceeds. containing compound I ¹ is consumed, it may become less than 75 wt%.

Hereinafter, each process described above will be described sequentially.
[1] First, mother particles 21 having a charge 64 on the surface are dispersed in an aqueous dispersion 90.

  In the aqueous dispersion 90, for example, various waters such as distilled water, ion exchange water, pure water, ultrapure water, and RO water are used alone, or various lower alcohols such as methanol and ethanol are mixed with water as a main component. The obtained aqueous dispersion 90 is preferably used.

  [2] Next, as shown in FIG. 3 (a), in the aqueous dispersion 90, a first polar group 611, a hydrophobic group 612, and a polymerizable group 613 having polarities opposite to the charge 64 of the mother particle 21 are formed. A first polymerizable surfactant 61 having the following is added and mixed.

  At this time, the amount of the first polymerizable surfactant 61 added is the total number of moles of polar groups having a charge 64 converted from the amount used of the mother particles 21 (= weight [g] of the used mother particles 21 × The range of 0.5 to 2 times mol of the amount [mol / g] of the polar group having the charge 64 of the mother particle 21 is preferable, and more preferably 0.8 to 1.2 times mol. By setting the addition amount to 0.5 times mol or more, it is strongly ionically bound to the mother particle 21 having the electric charge 64 and can be easily encapsulated. On the other hand, when the addition amount is 2 times or less, the generation of the first polymerizable surfactant 61 that is not adsorbed on the mother particles 21 can be reduced, and the polymer particles that do not have the mother particles 21 as a core substance. Generation | occurrence | production of (the particle | grains which consist only of a polymer) can be prevented.

  Further, if necessary, the aqueous dispersion 90 may be irradiated with ultrasonic waves for a predetermined time. Thereby, the arrangement | positioning form of the 1st polymeric surfactant 61 which exists around the mother particle 21 is controlled very highly.

  Specifically, when the mother particle 21 has a negative charge 64, a cationic polymerizable surfactant can be used as the first polymerizable surfactant 61. On the other hand, when the mother particle 21 has a positive charge 64, an anionic polymerizable surfactant can be used as the first polymerizable surfactant 61.

  Examples of the cationic group possessed by the cationic polymerizable surfactant include a primary amine cation group, a secondary amine cation group, a tertiary amine cation group, a quaternary ammonium cation group, and a quaternary phosphonium. A cationic group, a sulfonium cationic group, a pyridinium cationic group, etc. are mentioned.

  Among these, the cationic group is one selected from the group consisting of a primary amine cation group, a secondary amine cation group, a tertiary amine cation group, and a quaternary ammonium cation group. preferable.

  The hydrophobic group possessed by the cationic polymerizable surfactant preferably contains at least one of an alkyl group and an aryl group.

  The polymerizable group possessed by the cationic polymerizable surfactant is preferably an unsaturated hydrocarbon group capable of radical polymerization.

  Among unsaturated hydrocarbon groups capable of radical polymerization, one selected from the group consisting of a vinyl group, an allyl group, an acryloyl group, a methacryloyl group, a propenyl group, a vinylidene group, and a vinylene group is preferable. Furthermore, among these, an acryloyl group and a methacryloyl group can be exemplified as more preferred examples.

  Examples of the cationic polymerizable surfactant include a cationic allylic acid derivative as described in JP-B-4-65824. Specific examples of the cationic polymerizable surfactant include dimethylaminoethyl methyl chloride methacrylate, dimethylaminoethyl benzyl methacrylate methacrylate, methacryloyloxyethyltrimethylammonium chloride, diallyldimethylammonium chloride, 2-hydroxy-3-methacryloxy And propyltrimethylammonium chloride.

  Moreover, a commercial item can also be used as a cationic polymerizable surfactant. Examples include Acryester DMC (Mitsubishi Rayon Co., Ltd.), Acryester DML60 (Mitsubishi Rayon Co., Ltd.), C-1615 (Daiichi Kogyo Seiyaku Co., Ltd.), and the like.

  The cationic polymerizable surfactants exemplified above can be used alone or as a mixture of two or more.

On the other hand, examples of the anionic group possessed by the anionic polymerizable surfactant include a sulfonate anion group (—SO ₃ ⁻ ) and a sulfinate anion group (—RSO ₂ ^— : R is alkyl having 1 to 12 carbon atoms). Group or phenyl group and modified product thereof), carboxylate anion group (—COO ⁻ ), phosphate anion group (—PO ₃ ⁻ ), alkoxide anion group (—O ⁻ ), and the like. It is preferable that it is 1 type selected.

  As the hydrophobic group possessed by the anionic polymerizable surfactant, a hydrophobic group similar to the hydrophobic group possessed by the cationic polymerizable surfactant described above can be used.

  As the polymerizable group possessed by the anionic polymerizable surfactant, a polymerizable group similar to the polymerizable group possessed by the cationic polymerizable surfactant described above can be used.

Examples of the anionic polymerizable surfactant include anionic allyl derivatives as described in JP-B-49-46291, JP-B-1-24142, or JP-A-62-104802. Anionic propenyl derivatives as described in JP-A-62-221431, anionic acrylics as described in JP-A-62-34947 or JP-A-55-11525 Examples thereof include acid derivatives and anionic itaconic acid derivatives as described in JP-B No. 46-34898 or JP-A No. 51-30284.
As a specific example of such an anionic polymerizable surfactant, the general formula (31):

［式中、Ｒ^２１およびＲ^３１は、それぞれ独立して、水素原子または炭素数１〜１２の炭化水素基であり、Ｚ^１は、炭素−炭素単結合または式−ＣＨ_２−Ｏ−ＣＨ_２−で表される基であり、ｍは２〜２０の整数であり、Ｘは式−ＳＯ_３Ｍ^１で表される基であり、Ｍ^１はアルカリ金属、アンモニウム塩、またはアルカノールアミンである］
で表される化合物、または式（３２）：

[Wherein, R ²¹ and R ³¹ each independently represent a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms, and Z ¹ represents a carbon-carbon single bond or a formula —CH ₂ —O—CH ₂ - a group represented by, m is an integer of 2 to 20, X is a group represented by the formula _-SO 3 ^{M 1, M 1} is an alkali metal, an ammonium salt or an alkanolamine,]
Or a compound represented by formula (32):

［式中、Ｒ^２２およびＲ^３２は、それぞれ独立して、水素原子または炭素数１〜１２の炭化水素基であり、Ｄは、炭素−炭素単結合または式−ＣＨ_２−Ｏ−ＣＨ_２−で表される基であり、ｎは２〜２０の整数であり、Ｙは式−ＳＯ_３Ｍ^２で表される基であり、Ｍ^２はアルカリ金属、アンモニウム塩、またはアルカノールアミンである］
で表される化合物が好ましい。

[Wherein, R ²² and R ³² each independently represent a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms, and D represents a carbon-carbon single bond or a formula —CH ₂ —O—CH ₂ — Wherein n is an integer of 2 to 20, Y is a group represented by the formula —SO ₃ M ² , and M ² is an alkali metal, an ammonium salt, or an alkanolamine]
The compound represented by these is preferable.

The polymerizable surfactant represented by the formula (31) is described in JP-A-5-320276 or JP-A-10-316909. By appropriately adjusting the type of R ²¹ and the value of X in the formula (31), it is possible to correspond to the degree of the charge 64 of the base particles 21. As a preferable polymerizable surfactant represented by the formula (31), a compound represented by the following formula (310) can be exemplified. Specifically, in the following formulas (31a) to (31d) Mention may be made of the compounds represented.

［式中、Ｒ^３１，ｍ，Ｍ^１は式（３１）で表される化合物と同様］

[Wherein R ³¹ , m and M ¹ are the same as the compound represented by formula (31)]

Adeka Soap SE-10N manufactured by Asahi Denka Kogyo Co., Ltd. is a compound represented by formula (310) in which M ¹ is NH ₄ , R ³¹ is C ₉ H ₁₉ , and m = 10. Adeka Soap SE-20N manufactured by Asahi Denka Kogyo Co., Ltd. is a compound represented by formula (310) in which M ¹ is NH ₄ , R ³¹ is C ₉ H ₁₉ , and m = 20.

  Examples of the anionic group possessed by the anionic polymerizable surfactant include, for example, the general formula (33):

［式中、ｐは９または１１であり、ｑは２〜２０の整数であり、Ａは−ＳＯ_３Ｍ^３で表わされる基であり、Ｍ^３はアルカリ金属、アンモニウム塩またはアルカノールアミンである］
で表される化合物が好ましい。式（３３）で表される好ましいアニオン性の重合性界面活性剤としては、以下の化合物を挙げることができる。

[In the formula, p is 9 or 11, q is an integer of 2 to 20, A is a group represented by —SO ₃ M ³ , and M ³ is an alkali metal, an ammonium salt or an alkanolamine]
The compound represented by these is preferable. Preferred examples of the anionic polymerizable surfactant represented by the formula (33) include the following compounds.

［式中、ｒは９または１１、ｓは５または１０である］

[Wherein r is 9 or 11, and s is 5 or 10]

  A commercial item can also be used as said anionic polymerizable surfactant. For example, Aqualon KH series (Aqualon KH-5, Aqualon KH-10) from Daiichi Kogyo Seiyaku Co., Ltd. can be mentioned. Aqualon KH-5 is a mixture of a compound represented by the above formula wherein r is 9 and s is 5 and a compound where r is 11 and s is 5. Aqualon KH-10 is a mixture of a compound represented by the above formula wherein r is 9 and s is 10, and a compound where r is 11 and s is 10.

  Moreover, as an anionic polymerizable surfactant, the compound represented by following formula (34) is preferable.

［式中、Ｒは炭素数８〜１５のアルキル基であり、ｎは２〜２０の整数であり、Ｘは−ＳＯ_３Ｂで表わされる基であり、Ｂはアルカリ金属、アンモニウム塩またはアルカノールアミンである。］

[Wherein, R is an alkyl group having 8 to 15 carbon atoms, n is an integer of 2 to 20, X is a group represented by —SO ₃ B, and B is an alkali metal, an ammonium salt or an alkanolamine] It is. ]

A commercial item can also be used as said anionic polymerizable surfactant. As a commercial item, Asahi Denka Kogyo Co., Ltd. Adeka rear soap SR series (Adeka rear soap SR-10, SR-20, R-1025) (above, a brand name) etc. can be mentioned, for example. The ADEKA rear soap SR series is a compound in which B is NH ₄ in the general formula (34), SR-10 is n = 10, and SR-20 is n = 20.

  Moreover, as an anionic polymeric surfactant, the compound represented by a following formula (A) is also preferable.

［上記式中、Ｒ^４は水素原子または炭素数１〜１２の炭化水素基を表し、Ｉは２〜２０の数を表し、Ｍ^４はアルカリ金属、アンモニウム塩、またはアルカノールアミンを表す。］

[In the above formula, R ⁴ represents a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms, I represents a number of 2 to 20, and M ⁴ represents an alkali metal, an ammonium salt, or an alkanolamine. ]

  A commercial item can also be used as said anionic polymerizable surfactant. As a commercial item, the Dai-Ichi Kogyo Seiyaku Co., Ltd. product Aqualon HS series (Aquaron HS-10, HS-20, and HS-1025) (above, a brand name) is mentioned, for example.

  In addition, examples of the anionic polymerizable surfactant used in the present invention include alkylallylsulfosuccinate sodium salt represented by the general formula (35).

  A commercial item can also be used as said anionic polymerizable surfactant. As a commercial item, Elyoinol JS-2 of Sanyo Chemical Industries Ltd. can be mentioned, for example, In the said General formula (35), it is a compound represented by m = 12.

  Examples of the anionic polymerizable surfactant used in the present invention include methacryloyloxypolyoxyalkylene sulfate sodium salt represented by the general formula (36). In the following formula, n is 1-20.

  A commercial item can also be used as said anionic polymerizable surfactant. As a commercial item, the Eleminol RS-30 of Sanyo Chemical Industries Ltd. can be mentioned, for example, In the said General formula (36), it is a compound represented by n = 9.

  Moreover, as an anionic polymeric surfactant used in this invention, the compound represented by General formula (37) can be used, for example.

  A commercial item can also be used as said anionic polymerizable surfactant, and this corresponds to Antox MS-60 of Nippon Emulsifier Co., Ltd.

  The anionic polymerizable surfactants exemplified above can be used alone or as a mixture of two or more.

  Furthermore, the organic polymer constituting the shell 22 preferably has a repeating structural unit derived from a hydrophobic monomer.

  This hydrophobic monomer has at least a hydrophobic group and a polymerizable group in its molecular structure. By containing such a hydrophobic monomer, the hydrophobicity and polymerizability of the shell 22 can be improved. As a result, the mechanical strength and durability of the shell 22 can be improved.

  Among these, examples of the hydrophobic group include those containing at least one of an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group.

  Examples of the aliphatic hydrocarbon group include a methyl group, an ethyl group, and a propyl group. Examples of the alicyclic hydrocarbon group include a cyclohexyl group, a dicyclopentenyl group, a dicyclopentanyl group, and an isobornyl group, and an aromatic hydrocarbon group. Examples thereof include a benzyl group, a phenyl group, and a naphthyl group.

  The polymerizable group is an unsaturated hydrocarbon group capable of radical polymerization, and is selected from the group consisting of a vinyl group, an allyl group, an acryloyl group, a methacryloyl group, a propenyl group, a vinylidene group, and a vinylene group. Preferably it is a seed.

  Specific examples of the hydrophobic monomer include styrene and methylstyrene, dimethylstyrene, chlorostyrene, dichlorostyrene, bromostyrene, p-chloromethylstyrene, divinylbenzene, and other styrene derivatives; methyl acrylate, ethyl acrylate, acrylic acid n-butyl, butoxyethyl acrylate, benzyl acrylate, phenyl acrylate, phenoxyethyl acrylate, cyclohexyl acrylate, dicyclopentanyl acrylate, dicyclopentenyl acrylate, dicyclopentenyloxyethyl acrylate, tetrahydrofurfuryl acrylate, isobol Monofunctional acrylic esters such as nyl acrylate; methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate , Butoxymethyl methacrylate, benzyl methacrylate, phenyl methacrylate, phenoxyethyl methacrylate, cyclohexyl methacrylate, dicyclopentanyl methacrylate, dicyclopentenyl methacrylate, dicyclopentenyloxyethyl methacrylate, tetrahydrofurfuryl methacrylate, isobornyl methacrylate, etc. Monofunctional methacrylic acid esters of allyl such as allylbenzene, allyl-3-cyclohexanepropionate, 1-allyl-3,4-dimethoxybenzene, allylphenoxyacetate, allylphenylacetate, allylcyclohexane, allyl polycarboxylate Compound: ester cheek of fumaric acid, maleic acid, itaconic acid; has radical polymerizable group such as N-substituted maleimide, cyclic olefin Monomer, and the like that. As the hydrophobic monomer, those satisfying the above-mentioned required characteristics are appropriately selected, and the addition amount thereof is arbitrarily determined.

  Furthermore, the organic polymer constituting the shell 22 preferably has a repeating structural unit derived from a crosslinkable monomer and / or a repeating structural unit derived from a monomer represented by the following general formula (B).

［ただし、Ｒ^１は水素原子またはメチル基を表す。Ｒ^２はｔ−ブチル基、脂環式炭化水素基、芳香族炭化水素基、またはヘテロ環基を表す。ｍは０〜３、ｎは０または１の整数を表す。］

[Wherein R ¹ represents a hydrogen atom or a methyl group. R ² represents a t-butyl group, an alicyclic hydrocarbon group, an aromatic hydrocarbon group, or a heterocyclic group. m represents an integer of 0 to 3, and n represents an integer of 0 or 1. ]

  Since the organic polymer constituting the shell 22 has a repeating structural unit derived from a crosslinkable monomer, a denser cross-linked structure is formed in the polymer. Therefore, the mechanical strength of the shell 22 and thus the electrophoretic particles 1 is increased. Can be improved.

When the organic polymer has a repeating structural unit derived from the monomer represented by the general formula (1), the R ² group which is a “bulky” group reduces the flexibility of the molecule of the shell 22, That is, since the mobility of molecules is restricted, the mechanical strength of the shell 22 is improved. Further, the presence of the R ² group, which is a “bulky” group, in the shell 22 makes the shell 22 excellent in solvent resistance. In the general formula (1), examples of the alicyclic hydrocarbon group represented by R ² include a cycloalkyl group, a cycloalkenyl group, an isobornyl group, a dicyclopentanyl group, a dicyclopentenyl group, an adamantane group, and a tetrahydrofuran group. Is mentioned.

  Specific examples of the crosslinkable monomer include compounds having two or more unsaturated hydrocarbon groups selected from a vinyl group, an allyl group, an acryloyl group, a methacryloyl group, a propenyl group, a vinylidene group, and a vinylene group. For example, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, allyl acrylate, bis (acryloxyethyl) hydroxyethyl isocyanurate, bis (acryloxyneopentyl) Glycol) adipate, 1,3-butylene glycol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, propylene glycol Diacrylate, polypropylene glycol diacrylate, 2-hydroxy-1,3-diaacryloxypropane, 2,2-bis [4- (acryloxy) phenyl] propane, 2,2-bis [4- (acryloxyethoxy) phenyl ] Propane, 2,2-bis [4- (acryloxyethoxy diethoxy) phenyl] propane, 2,2-bis [4- (acryloxyethoxy polyethoxy) phenyl] propane, hydroxypentylglycol diacrylate 1,4-butanediol diacrylate, dicyclopentanyl diacrylate, dipentaerythritol hexaacrylate, dipentaerythritol monohydroxypentaacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol Acrylate, tetrabromobisphenol A diacrylate, triglycerol diacrylate, trimethylolpropane triacrylate, tris (acryloxyethyl) isocyanurate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, Polyethylene glycol dimethacrylate, propylene glycol dimethacrylate, polypropylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, 2- Hydroxy-1,3-dimethacryloxypropane 2,2-bis [4 (methacryloxy) phenyl] propane, 2,2-bis [4- (methacryloxyethoxy) phenyl] propane, 2,2-bis [4- (methacryloxyethoxydiethoxy) phenyl] Propane, 2,2-bis [4- (methacryloxyethoxypolyethoxy) phenyl] propane, tetrabromobisphenol A dimethacrylate, dicyclopentanyl dimethacrylate, dipentaerythritol hexamethacrylate, glycerol dimethacrylate, neohydroxybivalinate Pentyl glycol dimethacrylate, dipentaerythritol monohydroxypentamethacrylate, ditrimethylolpropane tetramethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate Chromatography, tri glycerol dimethacrylate, trimethylolpropane trimethacrylate, tris (methacryloxyethyl) isocyanurate, allyl methacrylate, divinylbenzene, diallyl phthalate, diallyl terephthalate, diallyl isophthalate, diethylene glycol bis allyl carbonate.

  Specific examples of the monomer represented by the general formula (1) include the following.

  [3] Next, as shown in FIG. 3 (b), the second polymerizable interface having a hydroxyl group, a hydrophobic group 622, and a polymerizable group 623 as the second polar group 621 in the aqueous dispersion 90. Activator 62 is added and emulsified as shown in FIG.

  In the conditions selected from (A) the number of second polar groups (hydroxyl groups) 621 in the second polymerizable surfactant 62, and (B) the addition amount of the second polymerizable surfactant 62. The amount of charge on the surface of the shell 22 can be controlled by setting at least one condition in this step.

  The amount of the second polymerizable surfactant 62 added is preferably in the range of about 1 to 10 moles compared to the first polymerizable surfactant 61 added in the step [2], more preferably 1 to 1 times. The range is about 5 times mole. By setting the addition amount to be 1 mol or more, the charge amount of the shell 22 can be controlled with higher accuracy. On the other hand, when the addition amount is 10 times or less, the generation of hydrophilic monomers that do not contribute to the formation of the shell 22 can be suppressed, and the generation of polymer particles having no core substance other than the particles 2 can be prevented. .

  Further, if necessary, the aqueous dispersion 90 may be irradiated with ultrasonic waves for a predetermined time. Thereby, the arrangement | positioning form of the 2nd polymeric surfactant 62 which exists around the particle | grains 2 is controlled very highly.

As the second polymerizable surfactant 62, among those listed as the first polymerizable surfactant, in the subsequent step [5], in order to be able to react with the polymerization initiator having a polymerization initiating group, A polymerizable surfactant having a second polar group (hydroxyl group) 621, that is, an anionic polymerizable surfactant having an alkoxide anion group (—O ⁻ ) as an anionic group is used.

  [4] Next, as shown in FIG. 3C, a polymerization initiator 80 is added to the aqueous dispersion 90 to cause a polymerization reaction. Thereby, the particle | grains (encapsulated mother particle) 2 which encapsulate the mother particle 21 in the capsule form with the shell 22 comprised with an organic polymer are obtained.

  At this time, if necessary, the temperature of the aqueous dispersion 90 is raised to a predetermined temperature (a temperature at which the polymerization initiator 80 is activated). Thereby, the polymerization initiator 80 can be activated reliably and the polymerization reaction in the aqueous dispersion 90 can be suitably advanced.

  As the polymerization initiator 80, a water-soluble polymerization initiator is preferable, and potassium persulfate, ammonium persulfate, sodium persulfate, 2,2-azobis- (2-methylpropionamidine) dihydrochloride, or 4,4-azobis. -(4-cyanovaleric acid) etc. are mentioned, Among these, it can use combining 1 type (s) or 2 or more types.

  Here, according to the emulsion polymerization method which is the polymerization in the aqueous dispersion 90 described above, it is presumed that the first polymerizable surfactant 61 and each monomer exhibit the following behavior. Hereinafter, a case where a hydrophobic monomer is further added in the step [2] will be described.

  First, the first polymerizable surfactant 61 is adsorbed on the charges 64 of the particles 2 and irradiated with ultrasonic waves, then the hydrophobic monomer is added, and then the second polymerizable surfactant 62 is added and ultrasonic waves are added. , The arrangement of the first polymerizable surfactant 61 and the monomer existing around the particle 2 is very highly controlled, and the first polarity toward the particle 2 is formed in the innermost shell. The state where the groups 611 are oriented and the second polar group 621 is oriented toward the aqueous dispersion 90 in the outermost shell is formed. Then, by the emulsion polymerization, the monomer 2 is converted into an organic polymer in this highly controlled form to form the shell 22, thereby forming the particles 2 in which the mother particles 21 are encapsulated by the shell 22. Is formed.

  According to said method, the production | generation of the water-soluble oligomer and polymer which are a by-product can be reduced. Thereby, the viscosity of the aqueous dispersion 90 in which the obtained particles 2 are dispersed can be reduced, and a purification process such as ultrafiltration can be facilitated.

  The polymerization reaction as described above is preferably performed in a reaction vessel equipped with an ultrasonic generator, a stirrer, a reflux condenser, a dropping funnel, and a temperature controller.

  In the polymerization reaction, the polymerization initiator 80 is cleaved by raising the temperature to the cleavage temperature of the polymerization initiator 80 added in the reaction system (aqueous dispersion 90), thereby generating an initiator radical. This initiator radical attacks the unsaturated group of each polymerizable surfactant 61, 62 or the unsaturated group of the monomer, thereby starting the polymerization reaction.

  The addition of the polymerization initiator 80 into the reaction system can be easily performed by, for example, dropping an aqueous solution obtained by dissolving the water-soluble polymerization initiator 80 in pure water into the reaction vessel. At this time, an aqueous solution containing the polymerization initiator 80 may be added to the aqueous dispersion 90 heated to a temperature at which the polymerization initiator 80 is activated, or may be added in one portion or continuously. .

  Further, after the polymerization initiator 80 is added, the aqueous dispersion 90 may be heated to a temperature at which the polymerization initiator 80 is activated.

  As described above, it is preferable to use a water-soluble polymerization initiator as the polymerization initiator 80 and add an aqueous solution obtained by dissolving it in pure water dropwise to the aqueous dispersion 90 in the reaction vessel. As a result, the added polymerization initiator 80 is cleaved to generate initiator radicals, which attack the polymerizable groups of the polymerizable surfactants 61 and 62 and the polymerizable groups of the polymerizable monomers to cause the polymerization reaction. Occur. The polymerization temperature and polymerization reaction time vary depending on the type of polymerization initiator 80 used and the type of polymerizable monomer, but those skilled in the art can easily set preferable polymerization conditions as appropriate.

  As described above, the activation of the polymerization initiator 80 in the reaction system can be suitably performed by raising the temperature of the aqueous dispersion 90 to a predetermined polymerization temperature. The polymerization temperature is preferably in the range of 60 to 90 ° C. The polymerization time is preferably 3 to 10 hours.

  The particles 2 obtained as described above are obtained by wrapping the mother particles 21 with the shells 22.

  Here, an example of the behavior exhibited by each polymerizable surfactant and each monomer in the production process of the particles 2 thus obtained will be described in more detail with reference to FIG.

  When the first polymerizable surfactant 61 is added to the aqueous dispersion 90, the charge 64 of the mother particle 21 and the first polar group 611 of the first polymerizable surfactant 61 are ionically bonded. When the opposite polarities are combined, the polarities of the two are canceled out.

  Further, the first hydrophobic group 612 of the first polymerizable surfactant 61 and the hydrophobic group 622 of the second polymerizable surfactant 62 face each other, so that the second polymerizable surfactant 62 The second polar group (hydroxyl group) 621 is oriented toward the aqueous dispersion 90 side to form a micelle-like structure as shown in FIG.

  When the polymerization reaction is carried out in this state, the shell 22 composed of an organic polymer as shown in FIG. 4B maintaining the above structure on the surface of the mother particle 21 has the second polar group (hydroxyl group) 621 attached thereto. It is formed in a state exposed on the surface. That is, the arrangement form of the polymerizable surfactants 61 and 62 existing around the mother particle 21 before the polymerization reaction is extremely highly controlled. Then, by the emulsion polymerization reaction, the polymerizable surfactants 61 and 62 and the monomers are converted into organic polymers in this highly controlled form. Therefore, the particle 2 produced by such a method has the second polar group (hydroxyl group) 621 exposed on the surface thereof, and the structure thereof is controlled with extremely high accuracy.

  An example of another behavior exhibited by each polymerizable surfactant and each monomer will be described with reference to FIG.

  As shown in FIG. 5 (a), the first polymerizable surfactant 61 has its first polar group 611 oriented toward the mother particle 21 having a negative charge 64, and has a strong ionic bond. Adsorb at. The hydrophobic group 612 and the polymerizable group 613 of the first polymerizable surfactant 61 are polymerized with the hydrophobic group 622 of the second polymerizable surfactant 62 by hydrophobic interaction. The second polar group 621 faces the direction in which the aqueous dispersion 90 exists, that is, the direction away from the base particle 21.

  Further, the surface of the mother particle 21 has negative charges 64 chemically bonded at a specific density, and has a hydrophobic region 70 between the negative charges 64. The hydrophobic group 612 ″ and the polymerizable group 613 ″ of the first polymerizable surfactant 61 ″ are suitable. Then, the first polar group 611 of the other first polymerizable surfactant 61 ″. The first polymerizable surfactant 61 is arranged so that the first polar group 611 faces each other. Each hydrophobic group 612 and each polymerizable group 613 of the first polymerizable surfactant 61 are arranged. The hydrophobic group 622 and the polymerizable group 623 of the second polymerizable surfactant 62 face each other due to the hydrophobic interaction, and the second polar group (hydroxyl group) 621 is present in the direction in which the aqueous dispersion 90 exists. That is, it is directed away from the particle 2.

  When, for example, the polymerization initiator 80 is added to the aqueous dispersion 90 in such a dispersed state, the polymerizable groups 613 of the first polymerizable surfactant 61, 61 ″ and the second polymerizable surfactant 62, By polymerizing 613 ″ and 623, as shown in FIG. 5 (b), the particle 2 in which the mother particle 21 is wrapped in the shell 22 ′ is produced.

  In each of the polymerizable surfactants 61 and 62, the charge 64 of the mother particle 21 and the first polar group 611 of the first polymerizable surfactant 61 are ionically bonded in the polymerization system. A second micelle-like structure in which the second polar group 621 of the second polymerizable surfactant 62 is oriented toward the aqueous dispersion 90 side is formed in the outermost shell, and an organic polymer is generated by the polymerization reaction. Since the shell body 22 is formed in this manner, the arrangement form of the monomers existing around the mother particle 21 before the emulsion polymerization affects the polarization state in the vicinity of the mother particle 21 after the polymerization, and therefore it is controlled with extremely high accuracy. Can be said.

  As a result, the obtained particle 2 has the second polar group (hydroxyl group) 621 on the outside thereof and has a charging polarity depending on the hydroxyl group. Further, the amount of charge depending on the number of second polar groups 621 in the second polymerizable surfactant 62, the molecular weight of the second polymerizable surfactant 62, and the amount of the second polymerizable surfactant 62 added. The particles 2 have a charge of

  In the above polymerization reaction, each of the above polymerizable surfactants, hydrophobic monomers, crosslinkable monomers, the compound represented by the above general formula (1), and other known polymerizable monomers are each one type or Two or more kinds can be used.

  Moreover, since the said emulsion polymerization reaction is performed using an ionic polymeric surfactant, the emulsification state of the liquid mixture containing a raw material monomer is often favorable even if it does not use an emulsifier. Therefore, it is not always necessary to use an emulsifier, but at least one selected from the group consisting of known anionic, nonionic, and cationic emulsifiers may be used as necessary.

  [5] Next, as shown in FIG. 3 (d), the aqueous dispersion 90 containing the particles 2 is dried to obtain a dried product 86 of the particles 2.

  At this time, since a hydroxyl group (—OH group) is exposed from the surface of the shell body 22, a dry bond 86 is generated due to the occurrence of hydrogen bonding between the hydroxyl groups of the shell body 22 included in the adjacent particle 2. An aggregate in which a plurality of particles 2 are aggregated is formed.

  The aqueous dispersion 90 is dried by various drying methods such as freeze drying, aeration drying, surface drying, fluidized drying, airflow drying, spray drying, vacuum drying, infrared drying, high frequency drying, ultrasonic drying, and finely pulverized drying. Although it can be performed, it is preferably performed by lyophilization. According to lyophilization, the aqueous dispersion 90 is dried by sublimation from a solid to a gas, so that the particle 2 is dried without substantially affecting the original shape and function of the shell 22 of the particle 2. Can be made.

  As the freeze-drying method, a method similar to the method described in the post-process [9] can be used.

  Further, prior to drying the aqueous dispersion 90, it is preferable to perform a purification step such as ultrafiltration for purifying the particles 2 in the aqueous dispersion 90. Thereby, the water-soluble oligomer and polymer contained as a by-product in the aqueous dispersion 90 can be removed, and the content rate of the particles 2 in the dried product 86 can be increased.

  In the present embodiment, an aggregate in which the particles 2 are aggregated due to the hydrogen bond generated in the hydroxyl group is prepared through the steps [1] to [5] described above.

[6] Next, as shown in FIG. 3 (e), the dried product (aggregate) 86 has a functional group Z having reactivity with the second polar group (hydroxyl group) 621 and a polymerization initiating group A. polymerization initiation group-containing compound (compound comprising a functional group Z) to obtain a mixture 85 were added and mixed I ¹ (first step). This step is preferably performed in an inert gas atmosphere such as argon or nitrogen gas.

Here, as described in the above step [5], an aggregate in which the particles 2 are aggregated is formed in the dried product 86, but in the present embodiment, the dried product 86 (particles in the mixture 85). Except for 2), the content of the polymerization initiating group-containing compound I ¹ is set to a high content (high concentration) such as 75% by weight or more. In the mixture 85, the polymerization initiating group-containing compound I ¹ is linked to the surface of the particle 2. At this time, as described above, due to the presence of the polymerization initiating group-containing compound I ¹ in a high content, the affinity to the mixture 85 of the particles 2 having the polymerization initiating group-containing compound I ¹ bonded to the surface is increased. , Easily dispersed in the mixture 85. Thereby, aggregation of particles 2 becomes easy to be unraveled, and a ratio of particles having a large particle diameter, which is considered that a plurality of particles 2 are aggregated, can be reduced. Further, the polymerization initiating group-containing compound I ¹ can be linked to almost the entire surface of the particle 2. As a result, the particles 2 having the polymerization initiating group-containing compound I ¹ connected to the surface are dispersed in the mixture 85 (see FIG. 3F).

Hereinafter, for convenience of explanation, “content of polymerization initiating group-containing compound I ¹ excluding dried product 86 (particle 2) in mixture 85” is simply referred to as “content of polymerization initiating group-containing compound I ¹ ”. Sometimes said.

In the present embodiment, it is presumed that the polymerization initiating group-containing compound I ¹ can be linked to almost the entire surface of the particle 2 as described above by the following mechanism.

That is, the aggregate of the particles 2 aggregated by hydrogen bonding between the hydroxyl groups exposed from the surface is surrounded by a high concentration of the polymerization initiator group-containing compound I ¹ (see FIG. 6A). hydroxyl groups exposed from the outermost surface of Atsumaritai is, after the polymerization initiation group containing compound I ¹ is reacted with a functional group Z which also, there is a polymerization initiation group containing compound I ¹ a sufficient amount of unreacted therearound. Therefore, as shown in FIG. 6 (b), acting between the polymerization initiation group containing compound I ¹ particles 2 are bonded with other particles 2 on the surface, than the cohesive force due to hydrogen bond or the like, the particles 2 it is high in affinity with the polymerization initiation group containing compound I ¹ in the mixture 85 and the site of polymerization initiation group-containing compound derived from I ¹ bound to the surface of the particles 2 are dispersed in the mixture 85. As a result, the reaction between the hydroxyl group on the exposed surface of the other particle 2 and the functional group Z of the polymerization initiating group-containing compound I ¹ further proceeds, and such a reaction is repeated. Aggregation between the two is solved. As a result, as shown in FIG. 6 (c), it is presumed that the particles 2 in which the polymerization initiating group-containing compound I ¹ is connected to almost the entire surface are monodispersed in the mixture 85.

As described above, the second polar group (hydroxyl group) 621 reacts with the functional group Z, so that the polymerization initiating group-containing compound I ¹ is connected to almost the entire surface of the shell 22 (particle 2). Is done. That is, the polymerization initiating group A provided in the polymerization initiating group-containing compound I ¹ is introduced on the surface of the particle 2. In the polymerization initiating group-containing compound I ¹ , in the next step [7], a monomer is polymerized starting from the polymerization initiating group A, whereby a polymer 32 is formed. Therefore, the polymerization initiating group-containing compound I ¹ having the polymerization initiating group A constitutes a connection part that connects (links) the shell 22 and the polymer 32.

As described above, the polymerization initiating group-containing compound I ¹ (“compound having a functional group Z” in the present embodiment) includes the functional group Z having reactivity with the second polar group (hydroxyl group) 621 and the polymerization initiating group A. It is a compound which has these.

Among these, examples of the functional group Z include a halogenated carboxyl group and a halogenated sulfonic acid, and any one of these is selected. Since these halogenated acidic groups have excellent reactivity with respect to hydroxyl groups, the polymerization initiating group-containing compound I ¹ can be reliably linked to the surface of the shell 22.

  Further, the polymerization initiating group A may be any one that can polymerize a monomer starting from the polymerization initiating group, for example, one that is polymerized by atom transfer radical polymerization (ATRP), or one that is polymerized by nitroxide-mediated polymerization (NMP). , Reversible addition-fragmentation chain transfer polymerization (RAFT), those polymerized by living radical polymerization (TERP) using an organic tellurium compound, and the like. Among them, those polymerized by atom transfer radical polymerization are preferable. Thereby, the living radical polymerization in which the polymerization initiating group A and the monomer react can be more efficiently advanced.

  Examples of the polymerization initiating group A include those derived from an organic halide represented by the following general formula (1).

［式（１）中、Ｒ^１およびＲ^２は、それぞれ独立して、水素、および炭素原子の数が１〜２０であり任意の−ＣＨ_２−が−Ｏ−またはシクロアルキレン基で置換されてもよいアルキル基から選択される基を表し、Ｘ^１は、塩素、臭素またはヨウ素を表す。］

[In Formula (1), R ¹ and R ² are each independently hydrogen, and the number of carbon atoms is 1 to 20, and any —CH ₂ — is substituted with —O— or a cycloalkylene group. Represents a group selected from the possible alkyl groups, X ¹ represents chlorine, bromine or iodine. ]

Therefore, specifically, examples of the polymerization initiating group-containing compound I ¹ include acid halogenated compounds represented by the following general formula (2) or the following general formula (3).

［式（２）、（３）中、Ｒ^１およびＲ^２は、それぞれ独立して、水素、および炭素原子の数が１〜２０であり任意の−ＣＨ_２−が−Ｏ−またはシクロアルキレン基で置換されてもよいアルキル基から選択される基を表し、Ｒ^３は、単結合、水素、および炭素原子の数が１〜２０であるアルキレン基またはアリーレン基から選択される基を表し、Ｘ^１およびＸ^２は、それぞれ独立して、塩素、臭素またはヨウ素を表す。］

[In the formulas (2) and (3), R ¹ and R ² are each independently hydrogen, the number of carbon atoms is 1 to 20, and any —CH ₂ — is —O— or a cycloalkylene group. And R ³ represents a group selected from a single bond, hydrogen, and an alkylene or arylene group having 1 to 20 carbon atoms, and X 3 ¹ and X ² each independently represent chlorine, bromine or iodine. ]

The groups R ¹ and R ² are each preferably an alkyl group having 1 to 3 carbon atoms, particularly 1 in the general formulas (1) to (3). The group R ³ is preferably a single bond or an arylene group having 5 or 6 carbon atoms in the general formulas (1) to (3), and more preferably a single bond. Thus, it is possible to further proceed the reaction with the surface to improve dispersibility in a mixture 85 of particles 2, the polymerization initiating group-containing compound I ¹ and the shell 22 (particle 2).

From the above, the polymerization initiation group containing compound I ^1, compounds represented by the following general formula (4) or the following general formula (5) is preferably used.

［式（４）、（５）中、Ｘ^１およびＸ^２は、それぞれ独立して、塩素、臭素またはヨウ素を表す。］

[In the formulas (4) and (5), X ¹ and X ² each independently represent chlorine, bromine or iodine. ]

Further, the content of the polymerization initiating group-containing compound I ¹ may be 75% by weight or more, preferably 85% by weight or more, more preferably 95% by weight or more, and 100% by weight. More preferably. As a result, it contains a polymerization initiating group bonded to the surface of the particle 2 rather than the cohesive force caused by hydrogen bonding or the like, which acts between the particle 2 having the polymerization initiating group-containing compound I ¹ bonded to the surface and the other particle 2. since the direction of affinity with the compounds I ¹ in part a mixture 85 from polymerization initiation group containing compound I ¹ is more reliably high, it is possible to improve the dispersibility in a mixture 85 of particles 2.

Furthermore, when the content of the polymerization initiating group-containing compound I ¹ is set to 75% by weight or more and less than 100% by weight, the mixture 85 is set so that the content of the polymerization initiating group-containing compound I ¹ is set within this range. A solvent is added to the solvent, and the solvent is preferably a nonpolar solvent or a solvent having a small polarity (low). Thus, an acid halide compound represented by formula used as the polymerization initiating group-containing compound I ¹ (2) or the general formula (3) can be prevented from being degraded by the solvent.

  Such a nonpolar solvent or a solvent having a small polarity is not particularly limited. For example, hexane, cyclohexane, benzene, toluene, xylene, diethyl ether, chloroform, ethyl acetate, methylene chloride, isooctane, decane, dodecane, tetradecane, Tetrahydrofuran and the like can be mentioned, and one or more of these can be used in combination.

[7] Next, as shown in FIG. 3 (f), the monomer M and the catalyst are added to the mixture 85, and the monomer M is placed in the living room starting from the polymerization initiating group A of the polymerization initiating group-containing compound I ^1. Polymer 32 is formed by polymerization by radical polymerization (third step).

In this way, the polymer 32 was connected to the surface of the particle 2 via the polymerization initiating group-containing compound I ^1, thereby forming the polymer 32 on the surface of the particle 2 as shown in FIG. Electrophoretic particles 1 having a coating layer 3 are obtained.

  As the catalyst, in the process of growing the polymer 32, a catalyst having a growing end as a polymerizable group or a catalyst having a relatively low Lewis acidity is used. Such catalysts include, for example, transition metal halides such as Cu, Fe, Au, Ag, Hg, Pd, Pt, Co, Mn, Ru, Mo and Nb, and organic groups such as copper phthalocyanine as ligands. Transition metal complexes, etc., of which a transition metal halide is the main component is preferred.

  When the monomer M and the catalyst are added to the mixture 85, the polymerization initiating group A and the monomer M come into contact with each other, and a polymerization reaction occurs between them. Further, in the growth process of the polymer 32, the growth terminal is always the polymerization initiating group A, and a polymerization reaction is further generated between the polymerization initiating group and the monomer polymerizing group to synthesize the polymer (polymer) 32 ( To generate).

  Here, in the living radical polymerization, since the growing terminal always has polymerization activity in the process of polymer growth, the monomer is consumed, and the polymerization reaction is further stopped by adding a new monomer after the polymerization reaction is stopped.

  Therefore, as a result of adjusting the amount of monomer supplied to the reaction system, the reaction time and the amount of catalyst according to the desired degree of polymerization, it is possible to accurately control the number of structural units derived from the monomer of the polymer 32 to be synthesized. it can.

  Moreover, since the polymer 32 with uniform distribution of the degree of polymerization can be obtained, the film thickness of the coating layer 3 to be formed can be made relatively uniform.

  For this reason, the polymer 32 having a desired degree of polymerization can be formed by a simple process while suppressing variations among the electrophoretic particles 1. As a result, the electrophoretic particles 1 have excellent dispersibility and mobility in an electrophoretic dispersion described later.

  The solution (reaction solution) containing the monomer M and the catalyst is preferably subjected to deoxygenation treatment before starting the polymerization reaction. Examples of the deoxidation treatment include substitution after vacuum degassing with an inert gas such as argon gas and nitrogen gas, purge treatment, and the like.

  Further, in the polymerization reaction, the monomer polymerization reaction can be performed more quickly and reliably by heating (heating) the temperature of the mixture 85 to a predetermined temperature (temperature at which the monomer and catalyst are activated).

The heating temperature varies slightly depending on the type of the catalyst and is not particularly limited, but is preferably about 30 to 100 ° C. The heating time (reaction time) is preferably about 10 to 20 hours when the heating temperature is in the above range.
As described above, the electrophoretic particles 1 are manufactured.

[8] Next, the electrophoretic particles 1 are recovered from the mixture 85 as necessary.
Examples of the recovery method include various filtration methods such as ultrafiltration, nanofiltration, microfiltration, cake filtration, and reverse osmosis, and one or more of these can be used in combination. It is preferred to use ultrafiltration.

  The ultrafiltration is a method of filtering fine particles, and is a method suitably used as a method of filtering the electrophoretic particles 1.

[9] Next, if necessary, the electrophoretic particles 1 are dried.
The electrophoretic particles 1 are dried by various drying methods such as freeze drying, aeration drying, surface drying, fluidized drying, airflow drying, spray drying, vacuum drying, infrared drying, high frequency drying, ultrasonic drying, and finely pulverized drying. Although it can be performed, it is preferably performed by lyophilization.

  In lyophilization, since the mixture 85 is dried by sublimating from a solid to a gas, the shell 22 is dried without substantially affecting the original shape or function of the shell 22 of the electrophoretic particles 1. be able to.

Hereinafter, a method for freeze-drying the electrophoretic particles 1 will be described.
First, the electrophoretic particles 1 taken out from the mixture 85 by filtration are cooled and frozen. Thereby, liquid components, such as a solvent, contained in electrophoretic particle 1 change to solid.

  The cooling temperature is not particularly limited as long as it is not higher than the temperature at which the liquid component is frozen, but it is preferably about −100 to −20 ° C., more preferably about −80 to −40 ° C. . If the cooling temperature is higher than the above temperature range, the liquid component may not be sufficiently solidified. On the other hand, when the cooling temperature is lower than the above temperature range, the liquid component cannot be further solidified.

  Next, the pressure around the frozen electrophoretic particles 1 is reduced. Thereby, the boiling point of a liquid component can be reduced and a liquid component can be sublimated.

  The pressure at the time of depressurization varies depending on the composition of the liquid component, but is preferably about 100 Pa or less, and more preferably about 10 Pa or less. When the pressure at the time of depressurization is within the above range, the liquid component can be sublimated more reliably.

In addition, since the pressure around the electrophoretic particles 1 increases with the sublimation of the liquid component, it is preferable to keep the pressure constant by evacuating continuously with an exhaust pump or the like during lyophilization. Thereby, the rise in pressure can be suppressed and the sublimation efficiency of the liquid component can be prevented from decreasing.
As described above, the electrophoretic particles 1 can be freeze-dried.

<Another configuration example of the method for producing electrophoretic particles>
The electrophoretic particles 1 can be manufactured not only by the method for manufacturing electrophoretic particles described above but also by a manufacturing method of another configuration example as described below.

<< First Other Configuration Example >>
FIG. 7 is a schematic diagram for explaining a mechanism in which an aggregate in which particles are aggregated is dissolved, and particles in which a polymerization initiator group-containing compound and a polymerization initiator group-free compound are connected to the surface are dispersed in the mixture. is there.

In the first other configuration example, instead of the step [6], the following step [6A] is used so that the polymerization initiating group-containing compound I ¹ and the polymerization initiating group are not contained on the surface of the particle 2. except be a concatenation of the compound I ² is the same as the method of manufacturing the above-described electrophoretic particles.

[6A] In the first alternative configuration example, the dry matter 86 obtained in the step [5], in addition to the polymerization initiation group containing compound I ^1, further functional group having no polymerization initiation group A A mixture 85 containing Z and containing positively or negatively charged polymerization-initiating group-free compound (charged compound) I ² is mixed.

At this time, an aggregate in which the particles 2 are aggregated is formed in the dried product 86. In this embodiment, the polymerization initiation group-containing compound I excluding the dried product 86 (particle 2) in the mixture 85 is used. The total content of ¹ and the polymerization initiating group-free compound I ² is set to a high content (high concentration) such as 75% by weight or more. Thus, in a mixture 85, solved the aggregation of particles 2, since the polymerization initiation group containing compound I ¹ a polymerization initiating group-free compounds I ² is connected to substantially the entire surface of the particles 2, the surface The particles 2 in which the polymerization initiating group-containing compound I ¹ and the polymerization initiating group-free compound I ² are connected to each other are dispersed in the mixture 85.

In the following, for convenience of explanation, “the total content of the polymerization initiating group-containing compound I ¹ and the polymerization initiating group-free compound I ² excluding the dried product 86 (particle 2) in the mixture 85” is simply referred to as “ , “The total content of the polymerization initiator group-containing compound I ¹ and the polymerization initiator group-free compound I ² ”.

In the present embodiment, the polymerization initiating group-containing compound I ¹ and the polymerization initiating group non-containing compound I ² can be linked to almost the entire surface of the particle 2 as described above by the following mechanism. It is guessed.

That is, the aggregate of the particles 2 aggregated by hydrogen bonding between the hydroxyl groups exposed from the surface is surrounded by a high concentration of the polymerization initiating group-containing compound I ¹ and the polymerization initiating group-free compound I ² (FIG. 7 (a )), And thus, the hydroxyl group exposed from the outermost surface of the aggregate also reacts with the functional group Z of the polymerization initiating group-containing compound I ¹ and the polymerization initiating group non-comprising compound I ^2. A sufficient amount of unreacted polymerization initiating group-containing compound I ¹ and polymerization initiating group-free compound I ² are present. Therefore, as shown in FIG. 7 (b), hydrogen bonding or the like acting between the particle 2 in which the polymerization initiating group-containing compound I ¹ and the polymerization initiating group-free compound I ² are bonded to the surface and the other particles 2 is performed. in than cohesion caused, the polymerization initiating group-containing compound I ¹ and a polymerization initiating group in the mixture 85 and the site of polymerization initiation group containing compound I ¹ and a polymerization initiator group non-containing compounds derived from I ² was bonded to the surface of the particles 2 The affinity with the non-containing compound I ² becomes higher, and the particles 2 are dispersed in the mixture 85. As a result, the reaction between the hydroxyl group on the exposed surface of the other particle 2 and the functional group Z of the polymerization initiator group-containing compound I ¹ and the polymerization initiator group-free compound I ² further proceeds, and such a reaction is repeated. As a result, the aggregation of the particles 2 is finally solved. As a result, as shown in FIG. 6 (c), the particles 2 in which the polymerization initiating group-containing compound I ¹ and the polymerization initiating group-free compound I ² are connected to almost the entire surface are monodispersed in the mixture 85. It is assumed that

As described above, the second polar group (hydroxyl group) 621 reacts with the functional group Z, whereby the polymerization initiating group-containing compound I ¹ and the polymerization initiating group-free compound I ² are converted into the shell 22 ( It is connected to almost the entire surface of the particle 2).

That is, the polymerization initiating group A provided in the polymerization initiating group-containing compound I ¹ is introduced on the surface of the particle 2. This polymerization initiation group containing compound I ^1, in the step [7], the polymer 32 is formed by polymerization of the monomer to polymerization initiating group A as a starting point. Therefore, the polymerization initiating group-containing compound I ¹ having the polymerization initiating group A constitutes a connecting portion that connects (links) the shell 22 and the polymer 32.

Further, the surface of the particle 2, the charging property is imparted to positively or negatively charged including the polymerization initiation group-free compounds I ^2. Therefore, in the step [7], when the polymer 32 is formed, the use of a cationic monomer and an anionic monomer as the monomer M is omitted and a nonionic monomer is used alone. The electrophoretic particles 1 imparted with the property and the chargeability can be reliably obtained.

In addition, when imparting positively chargeable characteristics to the electrophoretic particles 1, a positively charged polymerization initiator group-free compound I ² is added to the mixture 85 to impart negatively chargeable characteristics to the electrophoretic particles 1. In this case, the negatively charged polymerization initiating group-free compound I ² may be added to the mixture 85.

Examples of such a polymerization initiating group-free compound I ² include positively charged compounds such as compounds represented by the following general formula (6) and the following general formula (7), which are negatively charged. Examples of the compound include compounds represented by the following general formula (8) to the following general formula (11).

［式（６）〜（１１）中、Ｘ^２は、塩素、臭素またはヨウ素を表す。］

[In the formulas (6) to (11), X ² represents chlorine, bromine or iodine. ]

Further, the total content of the polymerization initiating group-containing compound I ¹ and the polymerization initiating group-free compound I ² may be 75% by weight or more, preferably 85% by weight or more, and more preferably 95% by weight or more. More preferably, it is more preferably 100% by weight. Thereby, the particle 2 rather than the cohesive force caused by hydrogen bonding or the like acting between the particle 2 having the polymerization initiating group-containing compound I ¹ and the polymerization initiating group-free compound I ² bound to the other particle 2 on the surface. site and in a mixture 85 polymerization initiation group containing compound I ¹ and a polymerization initiator group affinity with the non-containing compound I ² of the polymerization initiating group-containing compound bound to the surface I ¹ and a polymerization initiator group derived from non-containing compound I ² Therefore, the dispersibility of the particles 2 in the mixture 85 can be further improved.

The ratio of the content of the polymerization initiating group-containing compound I ¹ and the polymerization initiating group non-containing compound I ² is determined by the types of the polymerization initiating group non-containing compound I ² and the monomer M used, and the number of hydroxyl groups exposed from the shell 22. For example, it is preferably about 10: 1 to 1: 5, and more preferably about 5: 1 to 1: 2. Thereby, both the dispersibility and the charging characteristics can be imparted to the obtained electrophoretic particles 1 in a balanced manner.

<< Second Other Configuration Example >>
In the second other configuration example, instead of the step [6] and the step [7], the following step [6B] and step [7B] are used, so that carbon- After linking the carbon double bond-containing compound, the polymer 32 is formed by linking the carbon-carbon double bond-containing compound with a polymer having a Si—H group at the terminal, thereby obtaining the electrophoretic particle 1. Except for this, the method is the same as the method for producing electrophoretic particles described above.

[6B] In this second other configuration example, instead of the polymerization initiating group-containing compound I ¹ , the functional group Z and carbon- A carbon-carbon double bond-containing compound having a carbon double bond (vinyl group) is added and mixed to obtain a mixture 85.

  At this time, an aggregate in which the particles 2 are aggregated is formed in the dried product 86. In the present embodiment, a carbon-carbon double bond excluding the dried product 86 (particle 2) in the mixture 85 is used. The content of the contained compound is set to a high content (high concentration) such as 75% by weight or more. Thereby, in the mixture 85, the aggregation of the particles 2 is released, and the carbon-carbon double bond-containing compound is connected to almost the entire surface of the particle 2, so that the carbon-carbon double bond-containing compound is formed on the surface. Will be dispersed in the mixture 85.

  In the following, for convenience of explanation, “content of carbon-carbon double bond-containing compound excluding dried product 86 (particle 2) in mixture 85” is simply referred to as “carbon-carbon double bond-containing compound”. It may be referred to as “content”.

In the present embodiment, the carbon-carbon double bond-containing compound can be connected to almost the entire surface of the particle 2 as described above, as described in the step [6]. It is presumed that the mechanism is similar to the mechanism in which the compound I ¹ is connected to almost the entire surface of the particle 2, and by this mechanism, the second polar group (hydroxyl group) 621 reacts with the functional group Z. The carbon-carbon double bond-containing compound is linked to almost the entire surface of the shell 22 (particle 2). That is, the carbon-carbon double bond provided in the carbon-carbon double bond-containing compound is introduced on the surface of the particle 2.

  The polymer 32 is linked to the carbon-carbon double bond by reacting the carbon-carbon double bond and the Si—H group included in the polymer in the step [7B] described later. Therefore, the carbon-carbon double bond-containing compound having a carbon-carbon double bond constitutes a connection part that connects (links) the shell 22 and the polymer 32.

  Examples of such a carbon-carbon double bond-containing compound include acid halogenated compounds represented by the following general formula (12) or the following general formula (13).

［式（１２）、（１３）中、Ｒ^３は、単結合、水素、および炭素原子の数が１〜２０であるアルキレン基またはアリーレン基から選択される基を表し、Ｘ^１およびＸ^２は、それぞれ独立して、塩素、臭素またはヨウ素を表す。］

[In the formulas (12) and (13), R ³ represents a single bond, hydrogen, and a group selected from an alkylene group or an arylene group having 1 to 20 carbon atoms, and X ¹ and X ² are Each independently represents chlorine, bromine or iodine. ]

The group R ³ is preferably an alkylene group having 1 to 5 carbon atoms, and more preferably an alkylene group having 2 carbon atoms in the general formulas (12) and (13). Thereby, since the dispersibility in the mixture 85 of the particle | grains 2 improves, reaction with a carbon-carbon double bond containing compound and the surface of the shell 22 (particle | grain 2) can further be advanced.

  From the above, as the carbon-carbon double bond-containing compound, a compound represented by the following general formula (14) or the following general formula (15) is preferably used.

［式（１４）、（１５）中、Ｘ^２は、塩素、臭素またはヨウ素を表す。］

[In the formulas (14) and (15), X ² represents chlorine, bromine or iodine. ]

  The content of the carbon-carbon double bond-containing compound may be 75% by weight or more, preferably 85% by weight or more, more preferably 95% by weight or more, and 100% by weight. More preferably it is. Thereby, the carbon-carbon bonded to the surface of the particle 2 rather than the cohesive force caused by the hydrogen bond or the like that acts between the particle 2 having the carbon-carbon double bond-containing compound bonded to the surface and the other particle 2. Since the affinity between the site derived from the double bond-containing compound and the carbon-carbon double bond-containing compound in the mixture 85 is more reliably increased, the dispersibility of the particles 2 in the mixture 85 is further improved. Can do.

  [7B] Next, in this second other configuration example, for example, a polymer having a Si—H group at the terminal represented by the following general formula (16) and a platinum catalyst are added to the mixture 85.

  Thereby, the Si—H group and the carbon-carbon double bond (vinyl group) react by a hydrosilylation reaction, and as a result, the polymer 32 is formed on the surface of the particle 2. Thereby, the electrophoretic particle 1 including the polymer 32 on the surface of the particle 2 is obtained.

［式（１６）中、Ｍは、前記モノマーを表し、ｍは、１以上の整数を表す。］

[In Formula (16), M represents the said monomer, m represents an integer greater than or equal to 1. ]

  Further, when the Si—H group and the carbon-carbon double bond (vinyl group) are reacted by the hydrosilylation reaction, the reaction is performed more quickly and reliably by setting the temperature of the mixture 85 to a predetermined temperature. Can do.

  Although the temperature of this heating is not specifically limited, It is preferable that it is about 30-100 degreeC. The heating time (reaction time) is preferably about 10 to 20 hours when the heating temperature is in the above range.

<< Third Other Configuration Example >>
In the third other configuration example, in place of the step [6] and the step [7], the following step [6C] and step [7C] are used, so that acid halogen is formed on the surface of the particle 2. Production of the electrophoretic particles described above, except that the electrophoretic particles 1 are obtained by linking a polymer having a hydroxyl group at the end to the acid halogenated compound after the linking compound is linked. It is the same as the method.

[6C] In this third other configuration example, first, an oxidizing agent such as potassium permanganate is added to the dried product 86 obtained in the step [5]. Thereby, the hydroxyl group exposed from the surface of the shell 22 is oxidized beforehand to form a carboxyl group, whereby the hydroxyl group is provided in the carboxyl group. Then, the dried product 86, further mixture by the acid halide compound having two functional groups (halogenated acidic group) Z, in place of the polymerization initiation group containing compound I ^1, is mixed with 85 Get.

  At this time, an aggregate in which the particles 2 are aggregated is formed in the dried product 86. However, in this embodiment, the acid halide compound is contained excluding the dried product 86 (particle 2) in the mixture 85. The amount is set to a high content (high concentration) such as 75% by weight or more. Thereby, in the mixture 85, the aggregation of the particles 2 is released, and the acid halide compound is connected to almost the entire surface of the particle 2, so that the particle 2 having the acid halide compound connected to the surface is mixed with the mixture 85. Will be dispersed inside.

  In the following, for convenience of explanation, the “content of acid halogenated compound excluding the dried product 86 (particle 2) in the mixture 85” may be simply referred to as “content of acid halogenated compound”. .

In the present embodiment, the acid halide compound can be linked to almost the entire surface of the particle 2 as described above because the polymerization initiating group-containing compound I ¹ described in the step [6] is used. It is presumed that this is the same mechanism as that for coupling to almost the entire surface of the particle 2, and by this mechanism, the second polar group (hydroxyl group) 621 reacts with one of the functional groups Z, thereby producing an acid halogen. The compound is linked to almost the entire surface of the shell 22 (particle 2). That is, the other functional group (halogenated acidic group) Z of the acid halogenated compound is introduced on the surface of the particle 2.

  In the step [7C], which will be described later, the other functional group Z and the hydroxyl group included in the polymer react with this other functional group Z, whereby the polymer 32 is linked. Therefore, the acid halogenated compound having the functional group Z constitutes a connecting portion that connects (links) the shell 22 and the polymer 32.

  Examples of such an acid halogenated compound include those represented by the following general formula (17) or the following general formula (18).

［式（１７）、（１８）中、Ｒ^３は、単結合、水素、および炭素原子の数が１〜２０であるアルキレン基またはアリーレン基から選択される基を表し、２つのＸ^２は、それぞれ独立して、塩素、臭素またはヨウ素を表す。］

Expression (17), in (18), ^{R 3} represents a single bond, represents hydrogen, and the group number of carbon atoms is selected from an alkylene group or an arylene group is 1 to 20, the two ^{X 2} are, Each independently represents chlorine, bromine or iodine. ]

The group R ³ is preferably a single bond or an alkylene group having 1 or 2 carbon atoms in the general formulas (17) and (18), and more preferably a single bond. Thereby, since the dispersibility in the mixture 85 of the particle | grains 2 improves, reaction with an acid halogenated compound and the surface of the shell 22 (particle | grain 2) can further be advanced.

  From the above, as the acid halogenated compound, a compound represented by the following general formula (19) or the following general formula (20) is preferably used.

［式（１９）、（２０）中、２つのＸ^２は、それぞれ独立して、塩素、臭素またはヨウ素を表す。］

[In formulas (19) and (20), two X ^{2 s} each independently represent chlorine, bromine or iodine. ]

  Further, the content of the acid halogenated compound may be 75% by weight or more, preferably 85% by weight or more, more preferably 95% by weight or more, and further preferably 100% by weight. preferable. As a result, the site derived from the acid halide compound bonded to the surface of the particle 2 rather than the cohesive force caused by hydrogen bonding or the like acting between the particle 2 having the acid halogenated compound bonded to the surface and the other particle 2. And the acid halogenated compound in the mixture 85 are more reliably increased in affinity, so that the dispersibility of the particles 2 in the mixture 85 can be further improved.

  [7C] Next, in this third other configuration example, for example, a polymer having a hydroxyl group at the terminal represented by the following general formula (21) and a base such as triethylamine are added to the mixture 85.

  As a result, the hydroxyl group reacts with the functional group (halogenated acidic group) Z, and as a result, the polymer 32 is formed on the surface of the particle 2. Thereby, the electrophoretic particle 1 including the polymer 32 on the surface of the particle 2 is obtained.

［式（２１）中、Ｍは、前記モノマーを表し、ｍは、１以上の整数を表す。］

[In the formula (21), M represents the monomer, and m represents an integer of 1 or more. ]

  In addition, when the hydroxyl group and the functional group (halogenated acidic group) Z are reacted, the reaction can be performed more quickly and reliably by setting the temperature of the mixture 85 to a predetermined temperature.

  Although the temperature of this heating is not specifically limited, It is preferable that it is about 30-100 degreeC. The heating time (reaction time) is preferably about 5 to 20 hours when the heating temperature is in the above range.

  In the present embodiment, the particles 2 include mother particles 21 and a shell 22, and a hydroxyl group is exposed from the surface of the shell 22 to show hydrophilicity (has polarity), thereby providing a nonpolar solvent. Alternatively, the particles that aggregate in a solvent having a small polarity have been described. However, the particles 2 are not limited to those having such a configuration, and the aggregates are formed by exposing hydroxyl groups from the surface. For example, the surface of the mother particle 21 may be modified with a low molecule or polymer containing a hydroxyl group. Examples of the low molecule include alcohols such as monool, diol, and triol, and nonionic surfactants having a hydroxyl group at the terminal. Examples of the polymer include polyvinyl alcohol and carboxy. Examples thereof include celluloses such as methylcellulose, gum arabic (gum arabic), albumin, gelatin and polyethylene glycol. In addition, the production method of the present invention is particularly suitable for particles having a high hydroxyl density on the particle surface and high hydrophilicity. Here, high hydrophilicity means that the contact angle of water is 30 ° or less.

<Electrophoretic dispersion>
Next, the electrophoretic dispersion of the present invention will be described.

  The electrophoretic dispersion liquid is obtained by dispersing (suspending) at least one type of electrophoretic particles (electrophoretic particles of the present invention) in a dispersion medium (liquid phase dispersion medium; organic solvent).

  As the dispersion medium, those having a boiling point as high as 100 ° C. or higher and relatively high insulating properties are preferably used. Examples of such a dispersion medium include various types of water (eg, distilled water, pure water), alcohols such as butanol and glycerin, cellosolves such as butyl cellosolve, esters such as butyl acetate, ketones such as dibutyl ketone, and pentane. Aliphatic hydrocarbons (liquid paraffin) such as cyclohexane, alicyclic hydrocarbons such as cyclohexane, aromatic hydrocarbons such as xylene, halogenated hydrocarbons such as methylene chloride, aromatic heterocycles such as pyridine, Nitriles such as acetonitrile, amides such as N, N-dimethylformamide, carboxylate, silicon oil or other various oils can be used, and these can be used alone or as a mixture.

  Among these, as the dispersion medium, those mainly composed of aliphatic hydrocarbons (liquid paraffin such as Isopar) or silicon oil are preferable. Since the dispersion medium mainly composed of liquid paraffin or silicon oil has a high aggregation suppressing effect on the electrophoretic particles 1, it is possible to suppress deterioration of the display performance of the electrophoretic display device 920 over time. Further, liquid paraffin or silicone oil has an advantage that it has excellent weather resistance and high safety because it does not have an unsaturated bond.

  Further, as the dispersion medium, those having a relative dielectric constant of 1.5 or more and 3 or less are preferably used, and those having a dielectric constant of 1.7 or more and 2.8 or less are more preferably used. Such a dispersion medium is excellent in the dispersibility of the electrophoretic particles 1 and also has good electrical insulation. This contributes to the realization of the electrophoretic display device 920 that consumes less power and can display with high contrast. The value of the dielectric constant is a value measured at 50 Hz, and is a value measured for a dispersion medium having a water content of 50 ppm or less and a temperature of 25 ° C.

  In addition, in the dispersion medium, charge control comprising particles of electrolyte, surfactant (anionic or cationic), metal soap, resin material, rubber material, oils, varnish, compound, etc., if necessary. You may make it add various additives, such as an agent, a lubricant, a stabilizer, and various dyes.

  In addition, the dispersion of the electrophoretic particles in the dispersion medium may be performed by, for example, one or more of paint shaker method, ball mill method, media mill method, ultrasonic dispersion method, stirring dispersion method, and the like. it can.

  In such an electrophoretic dispersion, the electrophoretic particles 1 exhibit both excellent dispersibility and mobility due to the action of the polymer 32 of the coating layer 3.

<Electrophoretic display device>
Next, an electrophoretic display device (the electrophoretic device of the present invention) to which the electrophoretic sheet of the present invention is applied will be described.

  FIG. 8 is a diagram schematically showing a longitudinal section of an embodiment of the electrophoretic display device, and FIG. 9 is a schematic diagram showing the operating principle of the electrophoretic display device shown in FIG. In the following description, for convenience of explanation, the upper side in FIGS. 8 and 9 will be described as “upper” and the lower side as “lower”.

  An electrophoretic display device 920 shown in FIG. 8 includes an electrophoretic display sheet (front plane) 921, a circuit board (back plane) 922, an adhesive layer 98 that bonds the electrophoretic display sheet 921 and the circuit board 922, and A sealing portion 97 that hermetically seals a gap between the electrophoretic display sheet 921 and the circuit board 922 is provided.

  An electrophoretic display sheet (electrophoretic sheet of the present invention) 921 includes a substrate 912 including a flat base 92 and a second electrode 94 provided on the lower surface of the base 92, and a lower surface (one surface) of the substrate 912. ) And a display layer 9400 composed of partition walls 940 formed in a matrix and an electrophoretic dispersion liquid 910.

  On the other hand, the circuit board 922 includes a counter substrate 911 including a flat base 91 and a plurality of first electrodes 93 provided on the upper surface of the base 91, and the counter substrate 911 (base 91), for example. And a circuit (not shown) including a switching element such as a TFT.

Hereinafter, the structure of each part is demonstrated sequentially.
The base portion 91 and the base portion 92 are each composed of a sheet-like (flat plate) member, and have a function of supporting and protecting each member disposed between them.

  Each of the bases 91 and 92 may be either flexible or hard, but preferably has flexibility. By using the flexible base portions 91 and 92, a flexible electrophoretic display device 920, that is, an electrophoretic display device 920 useful for constructing, for example, electronic paper can be obtained.

  Moreover, when each base part (base material layer) 91 and 92 shall have flexibility, it is preferable to respectively comprise these with resin material.

  The average thicknesses of the bases 91 and 92 are appropriately set depending on the constituent material, application, and the like, and are not particularly limited, but are preferably about 20 to 500 μm, and more preferably about 25 to 250 μm. .

  A first electrode 93 and a second electrode 94 that form a layer (film shape) are provided on the surface of the bases 91 and 92 on the partition wall 940 side, that is, on the upper surface of the base 91 and the lower surface of the base 92, respectively. Yes.

  When a voltage is applied between the first electrode 93 and the second electrode 94, an electric field is generated between them, and this electric field acts on the electrophoretic particles (electrophoretic particles of the present invention) 95.

  In the present embodiment, the second electrode 94 is a common electrode, the first electrode 93 is an individual electrode (pixel electrode connected to a switching element) divided in a matrix (matrix), A portion where the two electrodes 94 overlap with one first electrode 93 constitutes one pixel.

  The constituent materials of the electrodes 93 and 94 are not particularly limited as long as they are substantially conductive.

  The average thicknesses of the electrodes 93 and 94 are appropriately set depending on the constituent materials and applications, and are not particularly limited, but are preferably about 0.05 to 10 μm, and about 0.05 to 5 μm. Is more preferable.

  Of the base portions 91 and 92 and the electrodes 93 and 94, the base portion and the electrodes (in the present embodiment, the base portion 92 and the second electrode 94) disposed on the display surface side each have light transmittance. In other words, substantially transparent (colorless transparent, colored transparent or translucent).

  In the electrophoretic display sheet 921, a display layer 9400 is provided in contact with the lower surface of the second electrode 94.

  The display layer 9400 is configured such that an electrophoretic dispersion liquid (the above-described electrophoretic dispersion liquid of the present invention) 910 is contained (enclosed) in a plurality of pixel spaces 9401 defined by partition walls 940.

  The partition 940 is formed between the counter substrate 911 and the substrate 912 so as to be divided in a matrix.

  Examples of the constituent material of the partition wall 940 include various resins such as thermoplastic resins such as acrylic resins, urethane resins, and olefin resins, epoxy resins, melamine resins, and thermosetting resins such as phenol resins. A material etc. are mentioned, Among these, it can use combining 1 type (s) or 2 or more types.

  In this embodiment, the electrophoretic dispersion liquid 910 accommodated in the pixel space 9401 is dispersed (suspended) in the dispersion medium 96, in which two types of colored particles 95b and white particles 95a (at least one type of electrophoretic particle 1) are dispersed. The electrophoretic dispersion liquid of the present invention described above is applied.

  In such an electrophoretic display device 920, when a voltage is applied between the first electrode 93 and the second electrode 94, colored particles 95b and white particles 95a (electrophoretic particles) are generated according to the electric field generated therebetween. 1) Electrophoresis toward one of the electrodes.

  In the present embodiment, white particles 95a having a positive charge are used, and negative particles are used as colored particles (black particles) 95b. That is, the electrophoretic particles 1 in which the polymer 32 is positively charged are used as the white particles 95a, and the electrophoretic particles 1 in which the polymer 32 is negatively charged are used as the colored particles 95b.

  When such electrophoretic particles 1 are used, if the first electrode 93 is set to a positive potential, the white particles 95a move to the second electrode 94 side as shown in FIG. The two electrodes 94 gather. On the other hand, the colored particles 95 b move to the first electrode 93 side and gather at the first electrode 93. For this reason, when the electrophoretic display device 920 is viewed from above (the display surface side), the color of the white particles 95a can be seen, that is, white can be seen.

  On the contrary, when the first electrode 93 is set to a negative potential, the white particles 95a move to the first electrode 93 side and gather on the first electrode 93 as shown in FIG. 9B. . On the other hand, the colored particles 95 b move to the second electrode 94 side and gather at the second electrode 94. For this reason, when the electrophoretic display device 920 is viewed from above (display surface side), the color of the colored particles 95b can be seen, that is, black can be seen.

  In such a configuration, the electrophoretic display device is appropriately set by appropriately setting the charge amount of the white particles 95a and the colored particles 95b (electrophoretic particles 1), the polarity of the electrodes 93 or 94, the potential difference between the electrodes 93 and 94, and the like. On the display surface side of 920, desired information (image) is displayed according to the combination of the colors of the white particles 95a and the colored particles 95b, the number of particles gathered at the electrodes 93 and 94, and the like.

  Moreover, it is preferable that the specific gravity of the electrophoretic particles 1 is set to be approximately equal to the specific gravity of the dispersion medium 96. Thereby, even after the application of the voltage between the electrodes 93 and 94 is stopped, the electrophoretic particles 1 can stay in a certain position in the dispersion medium 96 for a long time. That is, information displayed on the electrophoretic display device 920 is held for a long time.

  The average particle diameter of the electrophoretic particles 1 is preferably about 0.1 to 10 μm, and more preferably about 0.1 to 7.5 μm. By setting the average particle size of the electrophoretic particles 1 within the above range, aggregation of the electrophoretic particles 1 and sedimentation in the dispersion medium 96 can be reliably prevented. As a result, the display of the electrophoretic display device 920 is displayed. The deterioration of quality can be suitably prevented.

  In the present embodiment, the electrophoretic display sheet 921 and the circuit board 922 are bonded via the adhesive layer 98. Thereby, the electrophoretic display sheet 921 and the circuit board 922 can be more reliably fixed.

  The average thickness of the adhesive layer 98 is not particularly limited, but is preferably about 1 to 30 μm, and more preferably about 5 to 20 μm.

  A sealing portion 97 is provided between the base portion 91 and the base portion 92 and along the edges thereof. The electrodes 93 and 94, the display layer 9400, and the adhesive layer 98 are hermetically sealed by the sealing portion 97. Accordingly, it is possible to prevent moisture from entering the electrophoretic display device 920 and more reliably prevent the display performance of the electrophoretic display device 920 from deteriorating.

  As the constituent material of the sealing portion 97, the same materials as those described above as the constituent material of the partition wall 940 can be used.

<Electronic equipment>
Next, the electronic apparatus of the present invention will be described.
The electronic apparatus of the present invention includes the electrophoretic display device 920 as described above.

<< Electronic Paper >>
First, an embodiment when the electronic apparatus of the present invention is applied to electronic paper will be described.

  FIG. 10 is a perspective view showing an embodiment when the electronic apparatus of the present invention is applied to electronic paper.

  An electronic paper 600 shown in FIG. 10 includes a main body 601 composed of a rewritable sheet having the same texture and flexibility as paper, and a display unit 602.

  In such an electronic paper 600, the display unit 602 includes the electrophoretic display device 920 as described above.

<< Display >>
Next, an embodiment when the electronic apparatus of the present invention is applied to a display will be described.

  FIG. 11 is a diagram showing an embodiment when the electronic apparatus of the present invention is applied to a display. 11A is a cross-sectional view, and FIG. 11B is a plan view.

  A display (display device) 800 shown in FIG. 11 includes a main body 801 and an electronic paper 600 that is detachably attached to the main body 801.

  The main body 801 has an insertion port 805 into which the electronic paper 600 can be inserted on its side (right side in FIG. 11A), and two pairs of conveying rollers 802a and 802b are provided inside. Yes. When the electronic paper 600 is inserted into the main body 801 through the insertion port 805, the electronic paper 600 is installed in the main body 801 in a state of being sandwiched between the pair of conveyance rollers 802a and 802b.

  A rectangular hole 803 is formed on the display surface side of the main body 801 (the front side in FIG. 11B), and a transparent glass plate 804 is fitted in the hole 803. . Thereby, the electronic paper 600 installed in the main body 801 can be viewed from the outside of the main body 801. That is, in the display 800, the display surface is configured by visually recognizing the electronic paper 600 installed in the main body 801 on the transparent glass plate 804.

  In addition, a terminal portion 806 is provided at the distal end portion (left side in FIG. 11) of the electronic paper 600 in the insertion direction, and the terminal is provided inside the main body portion 801 with the electronic paper 600 installed on the main body portion 801. A socket 807 to which the unit 806 is connected is provided. A controller 808 and an operation unit 809 are electrically connected to the socket 807.

  In such a display 800, the electronic paper 600 is detachably installed on the main body 801, and can be carried and used while being detached from the main body 801.

  Further, in such a display 800, the electronic paper 600 includes the electrophoretic display device 920 as described above.

  Note that the electronic apparatus of the present invention is not limited to the application to the above, and for example, a television, a viewfinder type, a monitor direct view type video tape recorder, a car navigation device, a pager, an electronic notebook, a calculator, an electronic Examples include newspapers, word processors, personal computers, workstations, videophones, POS terminals, and devices equipped with touch panels. The electrophoretic display device 920 can be applied to the display units of these various electronic devices. is there.

  The electrophoretic particle production method, electrophoretic particle, electrophoretic dispersion liquid, electrophoretic sheet, electrophoretic device, and electronic apparatus of the present invention have been described based on the illustrated embodiments, but the present invention is not limited thereto. However, the configuration of each part can be replaced with any configuration having a similar function. In addition, any other component may be added to the present invention.

  In addition, in the method for producing electrophoretic particles of the present invention, one or two or more optional steps may be added.

  In the above embodiment, the case where a polymer having excellent dispersibility with respect to a dispersion medium, that is, a polymer having hydrophobicity is connected to particles having a hydroxyl group, that is, hydrophilic particles, is not limited to such a configuration. According to the present invention, for example, a hydrophilic polymer can be linked to a hydrophobic particle.

1. Bonding of polymerization-initiating group-containing compound to particles [Example 1]
[1] First, carbon black particles having an average particle size of 0.1 μm (mother particles: “Asahi Thermal” manufactured by Asahi Carbon Co., Ltd.) were dispersed in water (aqueous dispersion) to obtain a dispersion. Note that the surface of the carbon black particles was negatively charged.

  [2] Next, a cationic polymerizable surfactant (first polymerizable surfactant: DMC) was added to this dispersion and stirred while irradiating with ultrasonic waves to obtain a mixed solution.

  [3] Next, a polymerizable surfactant having a hydroxyl group (second polymerizable surfactant: manufactured by ADEKA, Adekari Soap ER-10) is used as a cationic polymerizable surfactant in the mixed solution. On the other hand, an equimolar amount was added and stirred while irradiating ultrasonic waves to obtain an emulsion.

  [4] Next, sodium persulfate (polymerization initiator) is added to this emulsion and stirred, and particles (encapsulated mother) formed by coating the periphery of the carbon black particles with a shell composed of an organic polymer. A mixed solution containing particles) was obtained. The conditions at this time were temperature: 70 ° C. and stirring time: 5 hours.

  [5] Next, the mixed liquid was dried under the conditions of a temperature of 60 ° C. and a time of 120 minutes to obtain a dried body of encapsulated mother particles.

  [6] Next, 10 g of 2-bromoisobutyryl bromide represented by the following chemical formula (4A) (“B0607” manufactured by Tokyo Chemical Industry Co., Ltd.) was added to 0.1 g of the dried body of the obtained encapsulated mother particles. After adding a polymerization initiating group-containing compound) to obtain a mixture, the mixture was stirred and mixed in a nitrogen atmosphere to obtain encapsulated mother particles in which the polymerization initiating group-containing compound was bonded to the surface.

  The mixture was stirred and mixed for 3 hours under the conditions of a temperature of 25 ° C. and a rotational speed of 600 rpm, and irradiated with 38 kHz ultrasonic waves for 5 minutes after 1 hour and 2 hours, respectively. It was.

[Example 2]
In the step [6], in place of 2-bromoisobutyryl bromide (BIBB), except that 10 g of a 75 wt% solution of BIBB in tetrahydrofuran (THF) was added to 0.1 g of a dried product, a mixture was obtained. In the same manner as in Example 1, encapsulated mother particles having a polymerization initiating group-containing compound bonded to the surface were obtained.

[Comparative Example 1]
In the step [6], in place of 2-bromoisobutyryl bromide (BIBB), 10 g of a 50 wt% solution of BIBB in tetrahydrofuran (THF) was added to 0.1 g of a dry product to obtain a mixture, In the same manner as in Example 1, encapsulated mother particles having a polymerization initiating group-containing compound bonded to the surface were obtained.

[Comparative Example 2]
In the step [6], in place of 2-bromoisobutyryl bromide (BIBB), 10 g of a 25 wt% solution of BIBB in tetrahydrofuran (THF) was added to 0.1 g of a dried product to obtain a mixture. In the same manner as in Example 1, encapsulated mother particles having a polymerization initiating group-containing compound bonded to the surface were obtained.

[Comparative Example 3]
In the step [6], instead of 2-bromoisobutyryl bromide (BIBB), 10 g of a 0.2 wt% solution of BIBB in tetrahydrofuran (THF) was added to 0.1 g of a dry product to obtain a mixture. Produced encapsulated mother particles in which the polymerization-initiating group-containing compound was bonded to the surface in the same manner as in Example 1.

2. Evaluation 2-1. Particle size distribution measurement by dynamic light scattering About the encapsulated mother particles in which the polymerization initiating group-containing compound obtained in each Example and each Comparative Example was bonded to the surface, the encapsulated mother in which the polymerization initiating group-containing compound was bonded to the surface, respectively. After adding methylene chloride as a dispersion solvent to the mixture until the content of the particles is within the appropriate range for measurement, dynamic light scattering is performed using a particle size distribution measuring device ("Microtrac UPA-250" manufactured by Nikkiso Co., Ltd.). The particle size distribution was measured by the method.
These results are shown in FIG.

  This particle size distribution was determined by performing one measurement by integrating 30 times 5 times, performing each measurement twice for each example and each comparative example, and calculating the average of these measurements.

2-2. Standard deviation analysis of particle size distribution From the particle size distribution measured in the encapsulated mother particle in which the polymerization initiating group-containing compound of each Example and each Comparative Example was bonded to the surface, 84% particle size [μm] (cumulative curve was 84 % Particle size; d84%) and 16% particle size [μm] (particle size when cumulative curve becomes 16%; d16%), and from these particle sizes, the following formula (II ) Was used to determine the standard deviation σ of the encapsulated mother particles with the polymerization initiating group-containing compound bound to the surface.
σ = (d84% −d16%) / 2 (II)

For the encapsulated mother particles in which the polymerization initiator group-containing compounds of Examples and Comparative Examples 1 and 2 were bonded to the surface, the calculation was performed using the encapsulated mother particles in which the polymerization initiator group-containing compound of Comparative Example 3 was bonded to the surface The relative value when the standard deviation σ was 1 was determined.
These results are shown in FIG.

2-3. Microscopic image analysis For encapsulated mother particles in which the polymerization initiator group-containing compound of each Example and each Comparative Example was bonded to the surface, methylene chloride was added to the mixture used in the measurement of the particle size distribution of 2-1. Microscopic images in the dispersion were acquired at a constant magnification. And in the obtained microscope image, what has a particle size of 1 micrometer or more was picked up, and the total (total area) of those areas was calculated | required.

Further, for the encapsulated mother particles in which the polymerization initiator group-containing compounds of Examples and Comparative Examples 1 and 2 were bonded to the surface, the encapsulated mother particles in which the polymerization initiator group-containing compound of Comparative Example 3 was bonded to the surface were determined. The relative value when the total area was 1 was determined.
These results are shown in FIG.

2-4. Summary As shown in FIG. 12, in the particle size distribution of the encapsulated mother particles in which the polymerization initiator group-containing compound of each example is bonded to the surface, one peak is mainly observed, whereas the polymerization initiator group of each comparative example is observed. In the particle size distribution of the encapsulated mother particles having the compound contained on the surface, two peaks are observed, and in addition to the encapsulated mother particles having the polymerization initiator group-containing compound bonded to the surface, aggregates of these particles are formed. It was inferred.

  In addition, this shows the relationship between the standard deviation of the particle size distribution and the content of the polymerization initiating group-containing compound shown in FIGS. 13 and 14, and the total area of those having a particle size of 1 μm or more and the polymerization initiating group-containing compound. From the graph showing the relationship with the content, the content of the polymerization initiating group-containing compound is 75% by weight or more as in each Example, and the polymerization initiating group-containing compound is in a state in which formation of aggregates is suppressed. It has been found that encapsulated mother particles bound to the surface can be dispersed in a dispersion.

DESCRIPTION OF SYMBOLS 1 ... Electrophoretic particle 2 ... Particle 3 ... Coating layer 21 ... Base particle 22 ... Shell body 32 ... Polymer 61, 61 "... 1st polymeric surfactant 62 ... 2nd polymerization Surfactants 611, 611 "... first polar groups 612, 612", 622 ... hydrophobic groups 613, 613 ", 623 ... polymerizable groups 621 ... second polar groups 64 ... charge 70 ... hydrophobic region 80 ... polymerization initiator 85 ... mixture 86 ... dried product 90 ... aqueous dispersion 91 ... base 92 ... base 93 ... first electrode 94 ... second electrode 95a ... White particles 95b ... colored particles 96 ... dispersion medium 97 ... sealing part 98 ... adhesive layer 600 ... electronic paper 601 ... main body 602 ... display unit 800 ... display 801 ... main body part 802a ... Conveying roller pair 803 ....... hole 804 .. transparent glass plate 8 5... Insertion port 806... Terminal portion 807... Socket 808 .. controller 809 .. operation portion 910. Electrophoretic display sheet 922 ... Circuit board 940 ... Partition 9400 ... Display layer 9401 ... Pixel space A ... Polymerization initiating group I ¹ ... Polymerization initiating group-containing compound I ² ... Polymerization initiating group-free compound Z ... Functional group

Claims (13)

A method for producing electrophoretic particles comprising particles that expose hydroxyl groups on the surface and a coating layer that covers at least a portion of the particles,
When obtaining a mixture in which a compound having a functional group having reactivity with the hydroxyl group is added to and mixed with the plurality of particles, the content of the compound excluding the plurality of particles in the mixture is 75% by weight or more. A first step of linking the compound to the surface of the particles;
And a second step of obtaining electrophoretic particles by forming a coating layer by connecting a polymer to the surface of the particles via the compound.   The method for producing electrophoretic particles according to claim 1, wherein the plurality of particles are obtained by drying an aqueous dispersion in which the plurality of particles are dispersed.   The method for producing electrophoretic particles according to claim 1, wherein the functional group is a halogenated carboxyl group or a halogenated sulfonic acid.   The method for producing electrophoretic particles according to any one of claims 1 to 3, wherein the compound is a polymerization initiating group-containing compound having the functional group and a polymerization initiating group. The method for producing electrophoretic particles according to claim 4, wherein the polymerization initiating group is represented by the following general formula (1).

[Wherein, R ¹ and R ² each independently represent hydrogen, and alkyl having 1 to 20 carbon atoms, and arbitrary —CH ₂ — may be substituted with —O— or a cycloalkylene group. Represents a group selected from the group, and X ¹ represents chlorine, bromine or iodine. ]   The said 2nd process WHEREIN: The said polymer is formed by adding a monomer and a catalyst to the said mixture, and polymerizing the said monomer by radical polymerization from the said polymerization initiation group as the starting point. Of producing electrophoretic particles. The method for producing electrophoretic particles according to claim 6, wherein the monomer contains a silicone macromonomer represented by the following general formula (I).

[Wherein, R represents a hydrogen atom or a methyl group, R ′ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, n represents an integer of 0 or more, and x represents an integer of 1 to 3. ]   The electrophoretic particle according to any one of claims 4 to 7, wherein the compound further comprises a charged compound having the functional group and positively or negatively charged in addition to the polymerization initiating group-containing compound. Production method.   Electrophoretic particles produced using the method for producing electrophoretic particles according to any one of claims 1 to 8.   An electrophoretic dispersion comprising the electrophoretic particles according to claim 9. A substrate,
An electrophoretic sheet, comprising: a plurality of structures that are disposed above the substrate and each store the electrophoretic dispersion according to claim 10.   An electrophoretic apparatus comprising the electrophoretic sheet according to claim 11.   An electronic apparatus comprising the electrophoresis apparatus according to claim 12.

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