JP2014010308A - Non-electrostatic colored resin particle and use thereof - Google Patents

Abstract

Disclosed is a non-chargeable colored resin particle with reduced chargeability.
SOLUTION: A pigment particle 1 made of a metal oxide, a surface treatment agent-derived layer 2 that coats the pigment particle 1, and a resin layer 3 that coats the surface treatment agent-derived layer 2, wherein the surface treatment agent has a general formula R ¹ _n R ² _p SiX _m (1) is a fluorine group-containing silane compound, and the amount of the surface treatment agent-derived layer 2 is 0.05 to 2.50 mg per m ² of the surface area of the pigment particles 1 A voltage of 15V is sandwiched between a pair of parallel ITO electrodes having a mutual distance of 50 μm and dispersed in a silicone oil having a kinematic viscosity of 100 cSt or less at a solid concentration of 20% by weight. When applied for 60 seconds, the measured charge amount is 10 nC / cm ² or less.
[Selection] Figure 1

Description

  The present invention relates to non-chargeable colored resin particles with reduced chargeability and uses thereof. More specifically, the present invention relates to non-charged colored resin particles, a non-charged colored resin particle dispersion using the same, and an electrophoretic display device.

  2. Description of the Related Art In recent years, image display devices (electrophoretic display devices) using colored particles as image display elements using electrophoresis of charged colored particles such as colored resin particles (charged colored resin particles) exhibiting charging properties have been developed. Attention has been paid. This electrophoretic display device is inexpensive, has a viewing angle as wide as a normal printed matter, has low memory consumption, and has a memory property that displayed information does not disappear even when the power is turned off. Because of its advantages, it is expected to be widely used as an inexpensive display device.

  An electrophoretic display device typically includes two electrode substrates that are disposed opposite to each other with a spacer interposed therebetween, and at least one of which is transparent, and a display liquid as an image display element enclosed between these electrode substrates. A display panel including the display panel, wherein the display liquid is a dispersion liquid in which positively charged charged colored particles and / or negatively charged charged colored particles are dispersed in a dispersion medium. The electrophoretic display device having the above configuration can display an image by electrophoresing the charged colored particles by applying an electric field between the two electrode substrates of the display panel (see Patent Documents 1 to 4). ).

  In addition, as an electrophoretic display device, a dispersion system in which at least one type of electrophoretic particles (colored particles) having different optical characteristics (color tone) from the dispersion medium is dispersed in a colored dispersion medium is used as a display liquid. An electrophoretic display device is known in which the dispersion system is enclosed in a number of microcapsules and these microcapsules are arranged between the electrode plates (see Patent Document 2).

  However, in the electrophoretic display device of Patent Document 2, when colored particles are arranged on a transparent electrode substrate serving as a display surface by application of a voltage, a dispersion medium having a color tone different from that of the colored particles enters the gaps between the colored particles. As a result, there is a problem that color mixing occurs and a desired display is not performed.

  As a technique for solving the problem of Patent Document 2, for example, charged colored particles (A) that move in a dispersion medium in response to an electric field, and colored particles (B) that do not move in a dispersion medium in response to an electric field (B) ) Is used in a dispersion medium (see Patent Document 3). In this electrophoretic display device, a base color corresponding to paper is displayed by colored particles (B), and an image color corresponding to characters and / or pictures drawn on paper is displayed as charged colored particles (A). By displaying on the screen, it is possible to display an image corresponding to paper on which characters and / or pictures are drawn. In Patent Document 3, it is said that display with high contrast can be realized by the electrophoretic display device. Patent Document 3 describes that, as the colored particles (B), it is possible to use hollow particles made of an organic polymer that are colored by dyeing.

JP 2006-293028 A Japanese Patent No. 2551783 JP 2001-188269 A JP 2009-31329 A

  However, Patent Document 3 does not describe a particle configuration and manufacturing method that can realize non-charged colored resin particles with reduced chargeability. In the electrophoretic display device of Patent Document 3, when colored resin particles (chargeable colored resin particles) having a relatively high chargeability are used as the colored particles (B), the colored particles (A) and the colored particles (B) If the charging polarity is reversed, the colored particles (A) and the colored particles (B) are agglomerated due to electrostatic attraction between the colored particles (A) and the colored particles (B). Occurs, and good display cannot be realized. In the electrophoretic display device of Patent Document 3, when colored resin particles (chargeable colored resin particles) having a relatively high chargeability are used as the colored particles (B), the colored particles (A) and the colored particles (B) are used. If the charged polarity is the same, the colored particles (B) migrate in the same direction as the colored particles (A) when the colored particles (A) migrate, and as a result, color mixing occurs. , Good display cannot be realized.

  Further, for example, colored particles that are organic pigments surface-treated by reaction with a fluorine atom-containing alkyl group, a fluorine atom-containing aryl group or a fluorine atom-containing aralkyl group, and a polymerizable monomer. It is known (see Patent Document 4).

  However, the colored particles of Patent Document 4 are colored particles having high chargeability (chargeable colored particles), as is clear from the fact that they are described as electrophoretic colored particles in Patent Document 4. Patent Document 4 does not describe a technique for obtaining non-charged colored resin particles with reduced chargeability. In fact, in the example of Patent Document 4, since the amount of the silane compound used relative to the organic pigment is large, it is not possible to obtain non-chargeable colored resin particles with reduced chargeability.

  An object of the present invention is to provide a non-charged colored resin particle with reduced chargeability, a non-charged colored resin particle dispersion using the same, and an electrophoretic display capable of suppressing the occurrence of color mixing and realizing good display To provide an apparatus.

The non-charged colored resin particles of the present invention include pigment particles made of a metal oxide, a layer derived from a surface treatment agent that coats the pigment particles, and a resin layer that coats a layer derived from the surface treatment agent. And the surface treatment agent has the following general formula: R ¹ _n R ² _p SiX _m (1)
(In the above formula, R ¹ represents a fluorine atom-containing alkyl group, a fluorine atom-containing aryl group, or a fluorine atom-containing aralkyl group, R ² represents an alkyl group, and X represents an alkoxy group or a chlorine atom. M represents an integer of 1 to 3, n represents an integer of 1 to 3, p represents an integer of 0 to 2, and m + n + p = 4)
The amount of the layer derived from the surface treatment agent is 0.05 to 2.50 mg per 1 m ² of the surface area of the pigment particles, and the kinematic viscosity is 100 cSt (centistokes). Between a pair of parallel indium tin oxide (hereinafter abbreviated as “ITO”) electrodes having a mutual distance of 50 μm and dispersed in a silicone oil having a solid content concentration of 20% by weight. When a voltage of 15 V is sandwiched and applied for 60 seconds, the measured charge amount is 10 nC / cm ² or less.

According to the said structure, since the quantity of the layer originating in a surface treating agent is 0.05-2.50 mg per 1 m < ² > of the surface area of the said pigment particle, charging property is reduced. This is because the negative charge on the fluorine atom on the surface of the layer derived from the surface treatment agent is present in an amount commensurate with the positive charge on the metal atom on the surface of the pigment particle, and thus the positive charge on the metal atom on the surface of the pigment particle. This is considered to be because it can be neutralized.

Moreover, the non-chargeable colored resin particles having the above-described configuration have a measured charge amount of 10 nC / cm ² or less measured under the above-described conditions, and the chargeability is reduced.

  Further, since the non-charged colored resin particles having the above-described configuration are covered with the resin layer, they are easily dispersed in the non-polar solvent.

  Due to these actions, the non-charged colored resin particles having the above-described structure are non-charged when used in an electrophoretic display device in combination with chargeable colored resin particles having a reverse polarity to the non-charged colored resin particles. Since aggregation due to electrostatic attraction between the chargeable colored resin particles and the chargeable colored resin particles can be suppressed, the occurrence of color mixing can be suppressed and a good display can be realized. In addition, since the non-charged colored resin particles having the above-described structure have reduced chargeability, they are used in electrophoretic display devices in combination with charged colored resin particles having the same charging polarity as the non-charged colored resin particles. In this case, it is possible to suppress the occurrence of migration of non-charged colored resin particles in the same direction as the direction of migration of the charged colored particles during migration of the charged colored particles. Can be realized.

In this application document, “non-chargeable” means that neither positive nor negative migration is shown in the polarity evaluation method, and the measured value in the charge amount measurement method is 10 nC / cm ² or less. Means. The polarity evaluation method and the charge amount measurement method will be described in the section of Examples.

  The non-charged colored resin particle dispersion of the present invention is characterized by containing a non-polar solvent and the non-charged colored resin particles of the present invention dispersed in the non-polar solvent.

  Since the non-charged colored resin particle dispersion having the above-described configuration uses the non-charged colored resin particles of the present invention with reduced chargeability, the chargeable coloring having a charging polarity opposite to that of the non-charged colored resin particles. Occurrence of aggregation due to electrostatic attraction between non-charged colored resin particles and charged colored resin particles when used in an electrophoretic display device in combination with resin particles, thus preventing color mixing Can be suppressed, and a good display can be realized. In addition, since the non-charged colored resin particle dispersion having the above-described configuration uses the non-charged colored resin particles of the present invention with reduced chargeability, the chargeability having the same charging polarity as that of the non-charged colored resin particles is used. When used in an electrophoretic display device in combination with colored resin particles, migration of non-charged colored resin particles in the same direction as the direction of migration of charged colored particles occurs during migration of charged colored particles. Since it can suppress, generation | occurrence | production of color mixing can be suppressed and a favorable display is realizable.

  The electrophoretic display device of the present invention comprises the non-charged colored resin particle dispersion of the present invention, wherein the non-charged colored resin particle dispersion is dispersed in the non-polar solvent. It further comprises chargeable colored resin particles having a different color tone.

  Since the electrophoretic display device having the above configuration uses the non-chargeable colored resin particles of the present invention with reduced chargeability, the chargeable colored resin particles having a charging polarity opposite to that of the non-charged colored resin particles are used. In this case, aggregation due to electrostatic attractive force between the non-chargeable colored resin particles and the chargeable colored resin particles can be suppressed. In addition, since the electrophoretic display device having the above configuration uses the non-chargeable colored resin particles of the present invention with reduced chargeability, the chargeable colored resin particles having the same charging polarity as the non-charged colored resin particles are used. When used, the migration of the non-chargeable colored resin particles in the same direction as the migration direction of the charged colored particles during migration of the charged colored particles can be suppressed. Therefore, according to the above configuration, it is possible to suppress the occurrence of color mixing and to realize a good display.

  According to the present invention, non-charged colored resin particles with reduced chargeability, a non-charged colored resin particle dispersion using the same, and electrophoretic display capable of suppressing the occurrence of color mixing and realizing good display Equipment can be provided.

It is the schematic which shows the non-chargeable colored resin particle which concerns on one Embodiment of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic which shows the jig | tool used to measure the charge amount of the non-chargeable colored resin particle which concerns on one Example of this invention, the upper figure is a side view, and the lower figure is a top view.

[Non-chargeable colored resin particles]
The non-charged colored resin particles of the present invention include pigment particles made of a metal oxide, a layer derived from a surface treatment agent that coats the pigment particles, and a resin layer that coats a layer derived from the surface treatment agent. And the surface treatment agent has the following general formula: R ¹ _n R ² _p SiX _m (1)
(In the above formula, R ¹ represents a fluorine atom-containing alkyl group, a fluorine atom-containing aryl group, or a fluorine atom-containing aralkyl group, R ² represents an alkyl group, and X represents an alkoxy group or a chlorine atom. M represents an integer of 1 to 3, n represents an integer of 1 to 3, p represents an integer of 0 to 2, and m + n + p = 4)
The amount of the layer derived from the surface treatment agent is 0.05 to 2.50 mg per 1 m ² of the surface area of the pigment particles, and the kinematic viscosity is 100 cSt or less. When a voltage of 15 V is applied for 60 seconds while being sandwiched between a pair of parallel ITO electrodes having a mutual distance of 50 μm and dispersed in oil at a solid concentration of 20% by weight, The measured charge amount is 10 nC / cm ² or less.

  The non-chargeable colored resin particles are considered to have the configuration shown in FIG. 1 in one embodiment. That is, as shown in FIG. 1, the non-charged colored resin particles according to one embodiment have a layer 2 derived from the surface treatment agent on the surface of the pigment particles 1. Furthermore, the resin layer 3 exists on the surface of the layer 2 derived from the surface treatment agent. In the non-chargeable colored resin particles, it is considered that the surface treatment agent-derived layer 2 has a role of binding the pigment particles 1 and the resin layer 3 and suppressing peeling of the resin layer 3.

  FIG. 1 shows the case where one pigment particle is present in one non-charged colored resin particle, but only one pigment particle is present in one non-charged colored resin particle. However, the present invention is not limited to this, and a plurality of pigment particles may be present in one non-chargeable colored resin particle.

[1. Pigment particles)
The pigment particles are made of a metal oxide. The pigment particle is not particularly limited as long as it is a metal oxide particle used as a pigment in the technical field. For example, iron oxide pigments such as mica-like iron oxide and iron black, red lead, air lead, etc. Lead oxide pigments; titanium oxide pigments such as titanium white (rutile titanium oxide), titanium yellow and titanium black; cobalt oxides; zinc oxide pigments such as zinc yellow; molybdenum oxide pigments such as molybdenum red and molybdenum white And the like. When the non-charged colored resin particles of the present invention are used to display the background of an electrophoretic display device, a white background display such as paper can be realized. As the pigment particles, titanium white, molybdenum white, etc. It is preferable to use white pigment particles, and it is more preferable to use titanium white particles as the pigment particles because the white background can be displayed with more excellent whiteness. The pigment particles may be used alone or in combination of two or more.

  The average particle diameter of the pigment particles can be appropriately set according to the characteristics required for the non-chargeable colored resin particles used in the electrophoretic display device, but generally may be in the range of 50 to 300 nm.

Furthermore, the specific surface area of the pigment particles is preferably in the range of 0.5 to 300 m ² / g.

[2. Layer derived from surface treatment agent]
The layer derived from the surface treatment agent (hereinafter referred to as “surface treatment agent-derived layer”) covers the pigment particles. The surface treatment agent-derived layer can be formed by treating the surface of the pigment particles with a surface treatment agent.

The surface treatment agent has the following general formula: R ¹ _n R ² _p SiX _m (1)
(In the above formula, R ¹ represents a fluorine atom-containing alkyl group, a fluorine atom-containing aryl group, or a fluorine atom-containing aralkyl group, R ² represents an alkyl group, and X represents an alkoxy group or a chlorine atom. M represents an integer of 1 to 3, n represents an integer of 1 to 3, p represents an integer of 0 to 2, and m + n + p = 4)
It is a fluorine group containing silane compound represented by these.

The fluorine atom-containing alkyl group represented by R ¹ preferably has 1 to 25 carbon atoms. The number of carbon atoms of the fluorine atom-containing aryl group represented by R ¹ is preferably 6-22. The fluorine atom-containing aralkyl group represented by R ¹ preferably has 7 to 30 carbon atoms. The number of carbon atoms of the alkyl group represented by R ² is preferably 1 to 25. The alkoxy group represented by X preferably has 1 to 15 carbon atoms.

  Examples of the fluorine group-containing silane compound include trifluoromethyltriethoxysilane, trifluoromethyltrimethoxysilane, trifluoromethyltrichlorosilane, 3,3,3-trifluoropropyltrimethoxysilane, and (pentafluorophenyl) trimethyl. Ethoxysilane, (tridecafluoro-1,1,2,2-tetrahydrooctyl) trimethoxysilane, (tridecafluoro-1,1,2,2-tetrahydrooctyl) triethoxysilane, (heptadecafluoro-1, 1,2,2-tetrahydrodecyl) trichlorosilane, (heptadecafluoro-1,1,2,2-tetrahydrodecyl) trimethoxysilane, dimethoxy-methyl (3,3,3-trifluoropropyl) silane, trichloro ( 3,3,3-trifluoropropyl Pyr) silane, dimethyl (3,3,3-trifluoropropyl) chlorosilane, trichloro (1H, 1H, 2H, 2H-perfluorooctyl) silane, 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane, 1H , 1H, 2H, 2H-perfluorododecyltrichlorosilane, pentafluorophenylethoxydimethylsilane, pentafluorophenyldimethylchlorosilane and the like. 1 type may be used for the said fluorine group containing silane compound, and it may use 2 or more types together.

The amount of the surface treatment agent-derived layer (corresponding to the amount of the fluorine group-containing silane compound used for preparing the surface treatment agent-derived layer) is 0.05 to 2.50 mg per 1 m ² of the surface area of the pigment particles. It is. When the amount of the surface treatment agent-derived layer is less than 0.05 mg per 1 m ² of the surface area of the pigment particles, the chargeability of the colored resin particles cannot be sufficiently reduced. This is considered to be because the effect of neutralizing the positive charge on the surface of the pigment particles by the negative charge on the fluorine atom on the surface of the surface treatment agent-derived layer becomes insufficient. Even when the amount of the surface treatment agent-derived layer exceeds 2.50 mg per 1 m ² of the surface area of the pigment particles, the chargeability of the colored resin particles cannot be sufficiently reduced. This is because the amount of negative charges on the fluorine atoms on the surface of the surface treatment agent-derived layer is excessively larger than the amount of positive charges on the surface of the pigment particles, which increases the chargeability of the colored resin particles. Conceivable.

The amount of the surface treatment agent-derived layer (corresponding to the amount of the fluorine group-containing silane compound used to prepare the surface treatment agent-derived layer) is 0.0001 to 0.0100 per 1 m ² of the surface area of the pigment particles. It preferably contains millimolar fluorine atoms.

  The surface treatment agent-derived layer can be formed by a known surface treatment method in which pigment particles are treated with a surface treatment agent. Examples of the surface treatment method include a direct method in which pigment particles are directly treated with a surface treatment agent, and the direct method is simple. Examples of the direct method include a dry method, a wet method (slurry method), and a spray method. As the surface treatment method, a wet method is most preferable. Thereby, the process of forming the below-mentioned resin layer can be easily performed by the dispersion polymerization method.

  Examples of the dry method include a direct method called an integral blend method, a master batch method, and a dry concentrate method. In the dry method, pigment particles are surface-treated by mixing pigment particles and a surface treatment agent in a dry state (a state without a medium such as a solvent). In this method, after the surface treatment agent is added, the surface treatment can be performed by high-speed stirring under a heating condition using a Henschel mixer, a super mixer, or the like having a shearing force. The temperature conditions at the time of the surface treatment may be any conditions that allow the treatment reaction with the surface treatment agent to proceed, and may be heated as necessary. Further, if the pigment particles are dried before the surface treatment as necessary, the efficiency of the treatment can be improved.

  In the wet method, surface treatment with a surface treatment agent is performed in a state where pigment particles are dispersed in a solvent. Also in this case, it may be heated as necessary, and the pigment particles may be dried before the surface treatment. In addition, since the wet method is a method in which the surface treatment of the pigment particles proceeds in a state where the pigment particles are dispersed in the solvent, the pigment particles are aggregated before the surface treatment in order to improve the surface treatment efficiency of the pigment particles. It is preferable to loosen the state. Examples of the method for loosening the aggregation state of the pigment particles include a pulverization process by stirring, dispersion, etc., a pulverization process using shearing force by various mixers, a dispersion process by adding various dispersants, emulsifiers, and the like.

  Specifically, the wet method can be performed, for example, by the following procedure. That is, first, pigment particles are dispersed in a solvent to prepare a dispersion, and then a surface treatment agent is added to the dispersion. After the addition, a dispersion medium such as glass beads, steel beads, and zirconia beads is added to the dispersion as necessary. The dispersion liquid containing the dispersion medium is put in a disperser, and the dispersion liquid is mixed in the disperser, whereby the surface treatment of the pigment particles can be performed. Examples of the disperser include a ball mill; a bead mill such as “DYNO (registered trademark) -MILL” (Dyno mill) and a DSP-mill; a roll mill; a sand mill; an attritor; a kneader; and a high-pressure jet mill such as a nanomizer.

  Examples of the nonpolar solvent include paraffinic hydrocarbons such as pentane, hexane, heptane, octane, nonane, decane and dodecane; isoparaffinic hydrocarbons such as isohexane, isooctane and isododecane; alkyl naphthenic hydrocarbons such as liquid paraffin A dialkyl silicone oil such as dimethyl silicone oil, an alkylphenyl silicone oil such as methylphenyl silicone oil (phenylmethylsilicone oil), a silicone oil such as cyclic polydialkylsiloxane, and cyclic polyalkylphenylsiloxane. Of these, taking into consideration the environmental impact of the working environment, alkyl naphthenic hydrocarbons such as liquid paraffin; dialkyl silicone oils such as dimethyl silicone oil, and alkyl phenyls such as methyl phenyl silicone oil (phenyl methyl silicone oil) Silicone oils such as silicone oil, cyclic polydialkylsiloxane, and cyclic polyalkylphenylsiloxane are preferred as the nonpolar solvent. The said nonpolar solvent may use 1 type and may use 2 or more types together. In order to efficiently disperse the pigment particles and the surface treatment agent, the silicone oil is preferably a silicone oil having a kinematic viscosity of 100 cSt or less measured by a measurement method defined in JIS K 2283.

[3. (Resin layer)
The resin layer covers a layer derived from the surface treatment agent. The resin constituting the resin layer is not particularly limited as long as it is a hydrophobic resin, and any known resin can be used. The resin layer is preferably a layer made of a polymer of a vinyl monomer (a compound having at least one ethylenically unsaturated group (broadly defined vinyl group)).

[3-1. Vinyl monomer)
As the vinyl monomer, a vinyl monomer having one ethylenically unsaturated group (hereinafter referred to as “monofunctional vinyl monomer”) can be used. The monofunctional vinyl monomer may be a monofunctional vinyl monomer having no polar group, or may be a monofunctional vinyl monomer having a polar group. In the present application document, the “polar group” is selected from the group consisting of cyano group, amino group, ammonium group, hydroxyl group, carbonyl group, nitro group, thiol group, sulfonyl group, phosphonyl group, halogen group, and glycidyl group. Means at least one substituent. Therefore, the monofunctional vinyl monomer having no polar group is a vinyl monomer that does not contain any of the substituents constituting the group.

  Examples of the monofunctional vinyl monomer having no polar group include monofunctional aromatic vinyl monomers having no polar group described later; olefins such as isoprene, isobutene, propylene and ethylene Vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether and the like.

  Examples of the monofunctional vinyl monomer having the above polar group include styrene derivatives such as p-chlorostyrene and 3,4-dichlorostyrene; vinyl chloride, vinylidene chloride, vinyl bromide, vinyl fluoride, and the like. Vinyl halides; vinyl acetates such as vinyl acetate, vinyl propionate, vinyl benzoate and vinyl butyrate; methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, acrylic acid n-octyl, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl α-chloroacrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, methacrylate n -Butyl, isobuty methacrylate Α- such as n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, etc. Methylene aliphatic monocarboxylic acid esters; acrylics such as acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate Acid derivatives or methacrylic acid derivatives (excluding α-methylene aliphatic monocarboxylic acid esters); ethylene, acrylic acid, methacrylic acid, maleic acid, fumaric acid, etc. Fatty acids having an unsaturated group; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and methyl isopropenyl ketone; N-vinyl pyrrole, N-vinyl carbazole, N-vinyl indole, N-vinyl pyrrolidone and the like N- Examples thereof include a vinyl nitrogen-containing heterocyclic compound; a silicone macromonomer having an ethylenically unsaturated group described later; and a reactive dispersant having an ethylenically unsaturated group described later. The monofunctional vinyl monomer may be used alone or in combination of two or more.

  As the vinyl monomer, a vinyl monomer having two or more ethylenically unsaturated groups (hereinafter referred to as “crosslinkable vinyl monomer”) can be used. Examples of the crosslinkable vinyl monomer include a crosslinkable aromatic vinyl monomer having no polar group described later; ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (Meth) acrylate, tetradecaethylene glycol di (meth) acrylate, nonaethylene glycol di (meth) acrylate, tetradecaethylene glycol di (meth) acrylate, decaethylene glycol di (meth) acrylate, pentadecaethylene glycol di (meta ) Acrylate, 1,3-butanediol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, glycerin di (meth) acrylate, trimethylol group Pantri (meth) acrylate, pentaerythritol tetra (meth) acrylate, diethylene glycol di (meth) acrylate phthalate, caprolactone-modified dipentaerythritol hexa (meth) acrylate, caprolactone-modified hydroxypivalate ester neopentyl glycol diacrylate, polyester Examples include (meth) acrylic acid ester monomers such as acrylate and urethane acrylate. In this application document, “(meth) acrylate” means acrylate or methacrylate, and “(meth) acryl” means acrylic or methacryl. The crosslinkable vinyl monomer may be used alone or in combination of two or more.

  The vinyl monomer is preferably a vinyl monomer having no polar group (a monofunctional vinyl monomer having no polar group or a crosslinkable vinyl monomer having no polar group), An aromatic vinyl monomer (a monofunctional aromatic vinyl monomer having no polar group described later or a crosslinkable aromatic vinyl monomer having no polar group described later) is more preferable. That is, the resin layer is preferably composed of a polymer containing a structural unit derived from a vinyl monomer having no polar group, and a structural unit derived from an aromatic vinyl monomer having no polar group. More preferably, it comprises a polymer containing. Thereby, since the number of polar groups contained in the resin layer can be reduced, the chargeability of the non-chargeable colored resin particles can be further reduced. As a result, when the non-charged colored resin particles of the present invention are used in an electrophoretic display device in combination with the charged colored resin particles, the non-charged colored resin particles and the charged colored resin particles are aggregated or charged. Generation of color mixing due to migration of non-chargeable colored resin particles in the same direction as the migration direction of the colored particles can be further suppressed.

  Ratio of structural units derived from vinyl monomers having no polar group in the polymer constituting the resin layer (corresponding to the ratio of vinyl monomers having no polar group in all vinyl monomers) Is preferably 50% by weight or more, more preferably 80% by weight or more, and most preferably 100% by weight. Thereby, since the number of polar groups contained in the resin layer can be further reduced, the chargeability of the non-chargeable colored resin particles can be further reduced. As a result, when the non-charged colored resin particles of the present invention are used in an electrophoretic display device in combination with the charged colored resin particles, the non-charged colored resin particles and the charged colored resin particles are aggregated or charged. Generation of color mixing due to migration of non-chargeable colored resin particles in the same direction as the migration direction of the colored particles can be further suppressed.

  The aromatic vinyl monomer having no polar group is a compound having at least one ethylenically unsaturated group (in a broad sense) and having an aromatic group (aromatic vinyl monomer). It is a compound that does not contain a polar group. The aromatic vinyl monomer having no polar group includes cyano group, amino group, ammonium group, hydroxyl group, carbonyl group, nitro group, thiol group, sulfonyl group, phosphonyl group, halogen group, and glycidyl group. It is an aromatic vinyl monomer that does not contain any of them.

  The aromatic vinyl monomer having no polar group is a monofunctional aromatic vinyl monomer having no polar group (aromatic vinyl monomer having one ethylenically unsaturated group). It may be a crosslinkable aromatic vinyl monomer which is an aromatic vinyl monomer having two or more ethylenically unsaturated groups. Examples of the monofunctional aromatic vinyl monomer having no polar group include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, on-butylstyrene, mn-butylstyrene, pn-butylstyrene, o-tert-butylstyrene, m-tert-butylstyrene, p-tert -Butyl styrene, on-hexyl styrene, mn-hexyl styrene, pn-hexyl styrene, on-octyl styrene, mn-octyl styrene, pn-octyl styrene, on- Nonyl styrene, mn-nonyl styrene, pn-nonyl styrene, on-decyl styrene, mn-decyl styrene, p n-decylstyrene, on-dodecylstyrene, mn-dodecylstyrene, pn-dodecylstyrene, n-methoxystyrene, o-phenylstyrene, m-phenylstyrene, p-phenylstyrene, 1-vinylnaphthalene , 2-vinylnaphthalene, and derivatives thereof. Examples of the crosslinkable aromatic vinyl monomer having no polar group include aromatic divinyl monomers such as divinylbenzene, divinylnaphthalene and derivatives thereof. One type of aromatic vinyl monomer having no polar group may be used, or two or more types may be used in combination.

  The resin layer is preferably made of a crosslinked polymer. Therefore, the resin layer is preferably made of a copolymer of the monofunctional vinyl monomer and the crosslinkable vinyl monomer. The proportion of structural units derived from the crosslinkable vinyl monomer in the copolymer (corresponding to the proportion of the crosslinkable vinyl monomer in all vinyl monomers) is 0.5 to 80 wt. %, Preferably in the range of 5 to 50% by weight.

  The amount of the resin layer is preferably 40 parts by weight or more with respect to 100 parts by weight of the pigment particles, and preferably 300 parts by weight or less with respect to 100 parts by weight of the pigment particles. When the amount of the resin layer exceeds 300 parts by weight with respect to 100 parts by weight of the pigment particles, aggregation of the non-charged colored resin particles may occur during the production of the non-charged colored resin particles. When the amount of the resin layer is less than 40 parts by weight with respect to 100 parts by weight of the pigment particles, the coating of the resin layer with respect to the pigment particles is incomplete, and the non-chargeable colored resin particles to the nonpolar solvent Dispersibility may deteriorate. The amount of the resin layer is more preferably 100 parts by weight or more with respect to 100 parts by weight of the pigment particles, and more preferably 250 parts by weight or less with respect to 100 parts by weight of the pigment particles.

[3-2. (Method for forming resin layer)
The resin layer can be formed by polymerizing the vinyl monomer in the presence of pigment particles coated with the layer derived from the surface treatment agent and a polymerization initiator.

  As a polymerization initiator used for the polymerization for forming the resin layer, an oil-soluble peroxide polymerization initiator, an azo polymerization initiator, or the like can be used. Specific examples of the polymerization initiator include, for example, benzoyl peroxide, lauroyl peroxide, octanoyl peroxide, o-chloroperoxide benzoyl, o-methoxybenzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxydicarbonate, Peroxide polymerization initiators such as cumene hydroperoxide, cyclohexanone peroxide, tert-butyl hydroperoxide, diisopropylbenzene hydroperoxide; 2,2′-azobisisobutyronitrile, 2,2′-azobis ( 2,4-dimethylvaleronitrile), 2,2′-azobis (2,3-dimethylbutyronitrile), 2,2′-azobis (2-methylbutyronitrile), 2,2′-azobis (2, 3,3-trimethylbutyronitrile), 2,2 -Azobis (2-isopropylbutyronitrile), 1,1'-azobis (cyclohexane-1-carbonitrile), 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2- (carbamoyl) And azo polymerization initiators such as azo) isobutyronitrile, 4,4′-azobis (4-cyanovaleric acid), and dimethyl-2,2′-azobisisobutyrate. As the polymerization initiator, a polymerization initiator not containing a polar group such as a cyano group, a carboxyl group, an amide group, an ammonium group or a sulfonic acid group, for example, an organic peroxide-based polymerization such as benzoyl peroxide or lauroyl peroxide. An initiator and an azo polymerization initiator such as dimethyl-2,2-azobis (2-methylpropionate) are preferred. The said polymerization initiator may use 1 type and may use 2 or more types together.

  The polymerization is preferably dispersion polymerization in a nonpolar solvent. As the nonpolar solvent, any of those mentioned in the section of “2. Layer derived from surface treatment agent” can be used, and silicone oil is preferred in consideration of the influence on the environment such as the working environment. The silicone oil is preferably a silicone oil having a kinematic viscosity of 100 cSt or less measured by a measuring method defined in JIS K 2283 in order to efficiently perform dispersion in the dispersion polymerization.

  In order to prevent coalescence of the pigment particles during the dispersion polymerization, the dispersion polymerization is preferably performed under irradiation of ultrasonic waves or stirring with a mechanical stirring device such as a magnetic stirrer. Also. The dispersion polymerization may be performed by using both ultrasonic irradiation and stirring by a mechanical stirring device such as a magnetic stirrer.

  The reaction temperature and time in the above polymerization are not particularly limited, and may be adjusted as appropriate depending on the type and amount of polymerization initiator used, the amount of vinyl monomer used for polymerization, and the like. The polymerization reaction temperature is preferably in the range of 40 to 120 ° C, and more preferably in the range of 40 to 80 ° C. The polymerization reaction time is preferably in the range of 0.5 to 50 hours, and more preferably in the range of 2 to 12 hours.

  The polymerization may be performed in an air atmosphere or an inert gas atmosphere. In order to prevent a polymerization rate delay and polymerization inhibition due to oxygen in the atmosphere, the polymerization may be performed in an inert gas atmosphere. Preferably it is done. Examples of such an inert gas include nitrogen gas and argon gas, and nitrogen gas is preferable from the viewpoint of economy.

  In the resin layer, the coating thickness and the coating ratio can be adjusted by selecting a vinyl monomer, whereby the particle diameter of the non-chargeable colored resin particles can be controlled. For example, as described later, when the resin layer is composed of a polymer of a reactive dispersant and an aromatic vinyl monomer having no polar group, the ratio of the reactive dispersant to the aromatic vinyl monomer By increasing the number, the particle diameter of the non-chargeable colored resin particles can be reduced. Moreover, the particle diameter of the non-chargeable colored resin particles can be reduced by selecting and using a vinyl monomer having high affinity for the non-polar solvent.

[3-4. (Reactive dispersant)
The resin layer is preferably made of a polymer of a reactive dispersant having an ethylenically unsaturated group and an aromatic vinyl monomer having no polar group. As a result, the non-charged colored resin particles are easily dispersed in the non-polar solvent. In addition, when the resin layer is formed by dispersion polymerization, by performing dispersion polymerization of the reactive dispersant and the vinyl monomer, the reactive dispersant is prevented while preventing aggregation due to coalescence of particles during polymerization. Uncharged colored resin particles having molecular chains (for example, silicone chains derived from silicone macromonomer) chemically immobilized on the surface can be obtained.

  The reactive dispersant is preferably a copolymer of a silicone macromonomer, a vinyl monomer having no polar group, and α-methylstyrene dimer. Thereby, the chargeability of non-chargeable colored resin particles can be further reduced. As a result, when the non-charged colored resin particles of the present invention are used in an electrophoretic display device in combination with the charged colored resin particles, the non-charged colored resin particles and the charged colored resin particles are aggregated or charged. Generation of color mixing due to migration of non-chargeable colored resin particles in the same direction as the migration direction of the colored particles can be further suppressed. The copolymer can be obtained by dispersion polymerization of a silicone macromonomer, a vinyl monomer having no polar group, and α-methylstyrene dimer in the presence of a nonpolar solvent.

  As the silicone macromonomer having an ethylenically unsaturated group, various compounds having an ethylenically unsaturated group at one end and a silicone unit (organosiloxane unit such as dimethylpolysiloxane unit) can be used.

  As said silicone macromonomer, what has a structure shown by following General formula (2) is mentioned, for example.

（上記式中、Ｒ³は水素原子又はメチル基を表し、Ｒ⁴は、炭素数２〜４のアルキレン基を表し、Ｒ⁵は、互いに同一又は異なって、炭素数１〜４のアルキル基又はフェニル基を表し、ｎは、正の整数を表す）
上記一般式（２）中におけるＲ⁴で表される炭素数２〜４のアルキレン基としては、エチレン基、ｎ−プロピレン基（トリメチレン基）、テトラメチレン基、エチルエチレン基等が挙げられる。上記一般式（２）中におけるＲ⁵で表される炭素数１〜４のアルキル基としては、メチル基、エチル基、ｎ−プロピル基、イソプロピル基、ｎ−ブチル基、イソブチル基、ｔｅｒｔ−ブチル基等が挙げられる。

(In the above formula, R ³ represents a hydrogen atom or a methyl group, R ⁴ represents an alkylene group having 2 to 4 carbon atoms, and R ^{5 s} are the same as or different from each other and represent an alkyl group having 1 to 4 carbon atoms or Represents a phenyl group, and n represents a positive integer)
Examples of the alkylene group having 2 to 4 carbon atoms represented by R ⁴ in the general formula (2) include an ethylene group, an n-propylene group (trimethylene group), a tetramethylene group, and an ethylethylene group. Examples of the alkyl group having 1 to 4 carbon atoms represented by R ⁵ in the general formula (2) include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a tert-butyl group. Groups and the like.

  Specific examples of the silicone macromonomer having the structure represented by the general formula (2) include, for example, α-butyl-ω- (3-methacryloxypropyl) polydimethylsiloxane (for example, “manufactured by JNC Corporation” Silaplane (registered trademark) FM-0721 "(trade name)). 1 type may be used for the said silicone macromonomer, and 2 or more types may be used together.

  The number average molecular weight of the silicone macromonomer is preferably in the range of 500 to 40000, and more preferably in the range of 1000 to 20000. N in the general formula (2) is preferably a number that can give a number average molecular weight within this range. N in the general formula (2) is preferably in the range of 3 to 500, and more preferably in the range of 10 to 250.

  The vinyl monomer having no polar group is a compound having at least one ethylenically unsaturated group (vinyl monomer), which is a cyano group, an amino group, an ammonium group, a hydroxyl group, or a carbonyl group. , A nitro group, a thiol group, a sulfonyl group, a phosphonyl group, a halogen group, and a glycidyl group. When the vinyl monomer does not have a polar group, the chargeability of the non-chargeable colored resin particles of the present invention can be further reduced.

  Examples of the vinyl monomer having no polar group include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, 2 , 4-dimethylstyrene, on-butylstyrene, mn-butylstyrene, pn-butylstyrene, o-tert-butylstyrene, m-tert-butylstyrene, p-tert-butylstyrene, o- n-hexylstyrene, mn-hexylstyrene, pn-hexylstyrene, on-octylstyrene, mn-octylstyrene, pn-octylstyrene, on-nonylstyrene, mn -Nonyl styrene, pn-nonyl styrene, on-decyl styrene, mn-decyl styrene, pn-decyl styrene Styrenes such as styrene, o-n-dodecyl styrene, mn-dodecyl styrene, pn-dodecyl styrene, n-methoxy styrene, o-phenyl styrene, m-phenyl styrene, p-phenyl styrene; 1-vinyl Naphthalene or 2-vinylnaphthalene (vinyl naphthalenes); olefins such as isoprene, isobutene, propylene, and ethylene; and derivatives thereof. 1 type may be used for the vinyl monomer which does not have said polar group, and 2 or more types may be used together.

  The amount of the vinyl monomer having no polar group is preferably in the range of 2 to 50 parts by weight and in the range of 5 to 25 parts by weight with respect to 100 parts by weight of the silicone macromonomer. More preferably. If the amount of the vinyl monomer having no polar group is less than 2 parts by weight based on 100 parts by weight of the silicone macromonomer, the affinity between the pigment particles and the reactive dispersant is deteriorated. It becomes difficult for the particles and the reactive dispersant to be chemically bonded. As a result, the non-charged colored resin particle dispersion is obtained by dispersing the non-charged colored resin particles in a non-polar solvent. The dispersion stability of the conductive colored resin particles may deteriorate. On the other hand, if the amount of the vinyl monomer having no polar group exceeds 50 parts by weight with respect to 100 parts by weight of the silicone macromonomer, the affinity between the pigment particles and the nonpolar solvent deteriorates. When the chargeable colored resin particles are dispersed in a nonpolar solvent to form a nonchargeable colored resin particle dispersion, the dispersion stability of the nonchargeable colored resin particles may deteriorate.

  The α-methylstyrene dimer is an addition cleavage type chain transfer agent having a structure represented by the following formula.

α−メチルスチレンダイマーと、シリコーンマクロモノマーと、極性基を有しないビニル系単量体との共重合により、分子量が制御され、かつ末端にα−メチルスチレンダイマーに由来する反応性の二重結合を有する重合性共重合体が反応性分散剤として得られる。

Reactive double bond derived from α-methylstyrene dimer at the end with molecular weight controlled by copolymerization of α-methylstyrene dimer, silicone macromonomer, and vinyl monomer having no polar group Is obtained as a reactive dispersant.

  The amount of the α-methylstyrene dimer used varies depending on the number average molecular weight of the reactive dispersant, but is generally preferably in the range of 0.1 to 10 parts by weight with respect to 100 parts by weight of the silicone macromonomer. . Further, instead of α-methylstyrene dimer, (meth) acrylic acid ester containing ethylenically unsaturated group having low radical polymerizability, such as 2-propenyl (meth) acrylate, 3-butenyl (meth) acrylate, etc. By using it, a polymerizable copolymer having a reactive double bond may be obtained as a reactive dispersant.

  When the amount of α-methylstyrene dimer used is less than 0.1 parts by weight based on 100 parts by weight of the silicone macromonomer, it becomes difficult to control the molecular weight by α-methylstyrene dimer, and the number average molecular weight of the resulting reactive dispersant is May become too large. On the other hand, when the amount of α-methylstyrene dimer used exceeds 10 parts by weight with respect to 100 parts by weight of the silicone macromonomer, an effect commensurate with the amount added (an effect of reducing the number average molecular weight of the reactive dispersant) is obtained. There may not be.

  The weight average molecular weight of the reactive dispersant is preferably in the range of 3000 to 200000, and more preferably in the range of 5000 to 100,000.

  The content of the reactive dispersant in the non-charged colored resin particles is not particularly limited, but is preferably 1 part by weight or more with respect to 100 parts by weight of an aromatic vinyl monomer described later, and 150 It is preferable that it is below the weight part. When the content of the reactive dispersant is less than 1 part by weight based on 100 parts by weight of the aromatic vinyl monomer described later, unchargeable colored resin particles having desired colorability cannot be obtained. There is. Even if the content of the reactive dispersant exceeds 150 parts by weight with respect to 100 parts by weight of the aromatic vinyl monomer described later, no further effect is obtained. The content of the reactive dispersant is more preferably 10 parts by weight or more, and more preferably 120 parts by weight or less with respect to 100 parts by weight of an aromatic vinyl monomer described later. Furthermore, the content of the reactive dispersant is more preferably 20 parts by weight or more and 100 parts by weight or less with respect to 100 parts by weight of an aromatic vinyl monomer described later. preferable.

[3-5. Method for producing reactive dispersant]
The reactive dispersant is, for example, a silicone macromonomer, a vinyl monomer having no polar group, and α-methylstyrene dimer added to a nonpolar solvent and dispersed in the nonpolar solvent. It can be obtained by copolymerization by heating with stirring by the above method. A polymerization initiator may be used for the copolymerization. The polymerization initiator is usually used after being previously dissolved in a vinyl monomer.

  As the nonpolar solvent, any of those mentioned in the section of “2. Layer derived from surface treatment agent” can be used, and silicone oil is preferred in consideration of the influence on the environment such as the working environment.

  In addition, in order to efficiently disperse by ultrasonic waves or the like in the production of the reactive dispersant, the silicone oil is a silicone oil having a kinematic viscosity measured by a measuring method defined in JIS K 2283 of 100 cSt or less. Is preferred.

  The amount of the nonpolar solvent used for the preparation of the reactive dispersant is 20 with respect to 100 parts by weight of the total amount of the silicone macromonomer, the vinyl monomer having no polar group, and the α-methylstyrene dimer. It is preferably within the range of ˜400 parts by weight, and more preferably within the range of 50 to 200 parts by weight.

  As the polymerization initiator used in the above polymerization, an oil-soluble peroxide polymerization initiator, an azo polymerization initiator, or the like can be used. Specific examples of the polymerization initiator include, for example, benzoyl peroxide, lauroyl peroxide, octanoyl peroxide, o-chloroperoxide benzoyl, o-methoxybenzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxydicarbonate, Peroxide polymerization initiators such as cumene hydroperoxide, cyclohexanone peroxide, tert-butyl hydroperoxide, diisopropylbenzene hydroperoxide; 2,2′-azobisisobutyronitrile, 2,2′-azobis ( 2,4-dimethylvaleronitrile), 2,2′-azobis (2,3-dimethylbutyronitrile), 2,2′-azobis (2-methylbutyronitrile), 2,2′-azobis (2, 3,3-trimethylbutyronitrile), 2,2 -Azobis (2-isopropylbutyronitrile), 1,1'-azobis (cyclohexane-1-carbonitrile), 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2- (carbamoyl) And azo polymerization initiators such as azo) isobutyronitrile, 4,4′-azobis (4-cyanovaleric acid), and dimethyl-2,2′-azobisisobutyrate. As the polymerization initiator, a polymerization initiator not containing a polar group such as a cyano group, a carboxyl group, an amide group, an ammonium group or a sulfonic acid group, for example, an organic peroxide-based polymerization such as benzoyl peroxide or lauroyl peroxide. An initiator and an azo polymerization initiator such as dimethyl-2,2-azobis (2-methylpropionate) are preferred. The said polymerization initiator may use 1 type and may use 2 or more types together.

  The polymerization initiator is an amount of 0. 0 to the total of the polymerization initiator and a monomer mixture (a mixture of a silicone macromonomer, a vinyl monomer having no polar group, and an α-methylstyrene dimer). It is preferably contained in an amount in the range of 1 to 5% by weight.

  The reaction temperature and reaction time in the above polymerization are not particularly limited. For example, the type and amount of the polymerization initiator used, the silicone macromonomer used, the vinyl monomer, and the α-methylstyrene dimer are used. It can be adjusted in a timely manner depending on reactivity. The polymerization reaction temperature is preferably in the range of 40 to 150 ° C, and more preferably in the range of 40 to 80 ° C. The polymerization reaction time is preferably in the range of 0.5 to 50 hours, and more preferably in the range of 2 to 25 hours.

  The copolymerization may be performed in an air atmosphere or in an inert gas atmosphere. In order to prevent a polymerization rate delay and polymerization inhibition due to oxygen in the atmosphere, an inert gas atmosphere may be used. It is preferable to carry out with. Examples of such an inert gas include nitrogen gas and argon gas, and nitrogen gas is preferable from the viewpoint of economy.

  Here, the reactive dispersant may or may not be separated from the nonpolar solvent used after the production of the reactive dispersant. When not separated, a reactive dispersant dispersed or dissolved in a nonpolar solvent can be used as it is for the production of non-charged colored resin particles.

[3-6. Silicone macromonomer)
A reactive dispersant that is a copolymer of a silicone macromonomer, a vinyl monomer that does not have a polar group, and an α-methylstyrene dimer; and an aromatic monomer that does not have a polar group. In addition to the component derived from the silicone macromonomer used during the production of the reactive dispersant, the resin layer is newly added during the copolymerization of the reactive dispersant and the aromatic vinyl monomer. It is preferable that the component derived from the added silicone macromonomer is included. By adding a silicone macromonomer together with the reactive dispersant and the aromatic vinyl monomer at the time of copolymerization of the reactive dispersant and the aromatic vinyl monomer, the silicone macromonomer and the reactive dispersant and A resin layer made of a copolymer with an aromatic vinyl monomer can be formed. When the resin layer contains a component derived from a silicone macromonomer newly added during copolymerization of the reactive dispersant and the aromatic vinyl monomer, the chargeability of the non-chargeable colored resin particles can be further reduced. As a result, when the non-charged colored resin particles of the present invention are used in an electrophoretic display device in combination with the charged colored resin particles, the non-charged colored resin particles and the charged colored resin particles are aggregated or charged. Generation of color mixing due to migration of non-chargeable colored resin particles in the same direction as the migration direction of the colored particles can be further suppressed.

  Here, the silicone macromonomer newly added at the time of copolymerization of the reactive dispersant and the aromatic vinyl monomer may be the same as the silicone macromonomer used in the production of the reactive dispersant. May be different.

  The addition amount of the silicone macromonomer newly added at the time of copolymerization of the reactive dispersant and the aromatic vinyl monomer is not particularly limited, but is 200 parts by weight with respect to 100 parts by weight of the aromatic vinyl monomer. Or less, more preferably 150 parts by weight or less. Even if the addition amount of the newly added silicone macromonomer exceeds 200 parts by weight, no further effect can be obtained. Moreover, although the minimum of the addition amount of the silicone macromonomer newly added is not specifically limited, It is preferable that it is 30 weight part or more with respect to 100 weight part of said aromatic vinyl-type monomers.

[4. Properties of non-charged colored resin particles]
As described above, the non-charged colored resin particles are a pair of mutually parallel pairs having a distance of 50 μm in a state of being dispersed in a silicone oil having a kinematic viscosity of 100 cSt or less at a solid concentration of 20% by weight. The amount of charge measured when a voltage of 15 V is applied for 60 seconds with the electrode sandwiched between the flat ITO electrodes is 10 nC / cm ² or less. The non-charged colored resin particles have a charge amount measured under the above-mentioned conditions of 10 nC / cm ² or less, so that when they are used in an electrophoretic display device in combination with the chargeable colored resin particles, It is possible to suppress the occurrence of color mixing due to aggregation of the charged colored resin particles and the charged colored resin particles or migration of the non-charged colored resin particles in the same direction as the migration direction of the charged colored particles. . The non-chargeable colored resin particles more preferably have a charge amount measured under the above conditions of 8 nC / cm ² or less.

  The average particle diameter of the non-charged colored resin particles is preferably in the range of 50 to 1000 nm, more preferably in the range of 100 to 1000 nm, and still more preferably in the range of 200 to 800 nm. .

  In the present application documents, the average particle diameter of the non-charged colored resin particles means a Z average particle diameter measured by a measurement method using a dynamic light scattering method, for example, the measurement method described in the Examples section. It shall be.

  When the average particle size of the non-charged colored resin particles is less than 0.1 μm, the viscosity of the reaction system during the polymerization for forming the resin layer (the resin layer is formed by dispersion polymerization in a non-polar solvent) In some cases, the viscosity of the nonpolar solvent) increases, and as a result, it is sometimes impossible to produce non-charged colored resin particles having a stable average particle size. On the other hand, when the non-charged colored resin particles have an average particle diameter exceeding 1000 nm, the non-charged colored resin particles are non-polar when dispersed in a non-polar solvent to form a non-charged colored resin particle dispersion. The dispersion stability in the solvent may be deteriorated.

  The specific gravity of the non-chargeable colored resin particles is preferably in the range of 1.0 to 3.0, and more preferably in the range of 1.2 to 2.5. When the specific gravity of the non-charged colored resin particles is less than 1.0, the pigment concentration (the content of the pigment particles) is low, and the color development may be deteriorated. On the other hand, when the specific gravity of the non-charged colored resin particles exceeds 3.0, the non-charged colored resin particles are dispersed in the non-polar solvent to obtain a non-charged colored resin particle dispersion. Dispersibility may be deteriorated.

[Uncharged colored resin particle dispersion]
The non-charged colored resin particle dispersion of the present invention contains a non-polar solvent and the non-charged colored resin particles of the present invention dispersed in the non-polar solvent.

  As the nonpolar solvent, any of those mentioned in the section of “2. Layer derived from surface treatment agent” can be used, and silicone oil is preferred in consideration of the influence on the environment such as the working environment. The silicone oil is preferably a silicone oil having a kinematic viscosity of 100 cSt or less measured by a measurement method defined in JIS K 2283 in order to promote dispersion of the non-charged colored resin particles.

  The ratio of the non-charged colored resin particles and the nonpolar solvent is not particularly limited, and can be appropriately set according to the use of the non-charged colored resin particle dispersion. For example, when the non-charged colored resin particle dispersion is used for an electrophoretic display device, the content of the non-charged colored resin particle in the non-charged colored resin particle dispersion is 2 to 40% by weight. Is preferable, and it is more preferable that it is in the range of 5 to 30% by weight.

  The uncharged colored resin particle dispersion may be blended with known additives as long as the effects of the present invention are not impaired.

[Electrophoretic display device]
The electrophoretic display device of the present invention uses the non-chargeable colored resin particle dispersion of the present invention. The electrophoretic display device of the present invention comprises the non-charged colored resin particle dispersion of the present invention, wherein the non-charged colored resin particle dispersion is dispersed in the non-polar solvent. And charging colored resin particles having a different color tone.

  The electrophoretic display device displays an image using electrophoresis of chargeable colored resin particles. Specifically, in the electrophoretic display device, the non-charged colored resin particles develop a base color (color corresponding to paper), and the charged colored resin particles are electrophoresed at desired positions (desired). An image corresponding to the paper on which the characters and / or pictures are drawn is displayed by developing a color different from the base color (in the shape) (color corresponding to the letters and / or pictures drawn on the paper). In the case of a monochrome display electrophoretic display device, for example, a combination of white non-chargeable colored resin particles and black chargeable colored resin particles may be used. In the case of an electrophoretic display device for color display, for example, white non-chargeable colored resin particles, red chargeable colored resin particles, green chargeable colored resin particles, and blue chargeable colored resin particles. What is necessary is just to use in combination.

  The content of the chargeable colored resin particles in the nonchargeable colored resin particle dispersion is 0.2 to 30 with respect to 100 parts by weight of the components other than the chargeable colored resin particles in the nonchargeable colored resin particle dispersion. It is preferably in the range of parts by weight, and more preferably in the range of 0.5 to 20 parts by weight.

  The configuration of the electrophoretic display device is not particularly limited. For example, the electrophoretic display device has a configuration in which a display layer made of the non-chargeable colored resin particle dispersion is sandwiched between a pair of opposing substrates each having an electrode. A configuration in which at least one of the substrates is a transparent substrate having a transparent electrode such as an ITO electrode may be mentioned. In this configuration, by applying a voltage between the electrode of one substrate and the electrode of the other substrate, the chargeable colored resin particles are electrophoresed on the one substrate side according to the polarity of the applied voltage. (Moving. In the electrophoretic display device, an image can be displayed by using a plurality of pixel electrodes in which electrodes on at least one substrate are arranged in a matrix and controlling the voltage for each pixel electrode. The non-charged colored resin particle dispersion is preferably sealed in a plurality of transparent organic polymer microcapsules, and each microcapsule is disposed adjacent to each pixel electrode.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited by these Examples.

  First, the measurement method of the average particle diameter and charge amount of the colored resin particles and the method for evaluating the polarity of the colored resin particles in the following Examples and Comparative Examples will be described.

[Method for measuring average particle diameter of colored resin particles]
In the following examples and comparative examples, the Z average particle diameter of the colored resin particles is measured using a dynamic light scattering method as follows, and the measured Z average particle diameter is taken as the average particle diameter of the colored resin particles. did.

  That is, first, a silicone oil dispersion of colored resin particles having a solid content of 10% by weight obtained in the following examples and comparative examples was irradiated with laser light, and the scattered light intensity scattered from the colored resin particles was measured in microseconds. Measured with time change. And the scattering average distribution resulting from the detected colored resin particle was applied to normal distribution, and the Z average particle diameter of the colored resin particle was calculated | required by the cumulant analysis method for calculating an average particle diameter.

  The measurement of the Z average particle diameter can be easily performed with a commercially available particle diameter measuring apparatus. In the following Examples and Comparative Examples, the Z average particle size was measured using a particle size measuring device (trade name “Zetasizer Nano ZS”) manufactured by Malvern Instruments Ltd. (Malvern Instruments Ltd.). Usually, a commercially available particle size measurement apparatus is equipped with data analysis software, and the data analysis software can automatically calculate the Z-average particle size by analyzing the measurement data.

[Method for measuring charge amount of colored resin particles]
A silicone oil dispersion of colored resin particles having a solid content of 10% by weight obtained in the following examples and comparative examples was used as a measurement sample.

  Moreover, the jig shown in FIG. 2 was produced as follows. First, a glass plate (width 20 mm, length 100 mm, thickness 0.7 mm, manufactured by Matsunami Glass Industrial Co., Ltd., trade name “EAGLE XG”, which is a pair of rectangular flat plates coated with ITO (flat ITO electrode) on one side. ", Hereinafter referred to as" ITO coated glass plate "). As shown in FIG. 2, one end (45 mm in length) of the pair of ITO-coated glass substrates 11 in the length direction are parallel to each other, and the respective ITO-coated surfaces 12 are inside. In this state, a jig having a distance of 50 μm was produced by stacking two spacers 14 each having a thickness of 50 μm (the spacer 14 was sandwiched between the ITO-coated glass substrates 11). As the two spacers 14 having a thickness of 50 μm, two “Teflon (registered trademark)” (polytetrafluoroethylene) films (length: 20 mm, width: 10 mm) having a thickness of 50 μm were used. These “Teflon (registered trademark)” The film was affixed to both end portions (dimension 10 mm along the length direction of the ITO coated glass substrate 11) along the length direction of the one end portion (length 45 mm) of one ITO coated glass substrate 11. The jig has a measurement sample injection portion 13 which is a gap having a width of 25 mm, a length of 20 mm, and a thickness of 50 μm between the ITO-coated surfaces 12 of the two ITO-coated glass plates 11.

Next, the measurement sample is infiltrated into the measurement sample injection portion 13 of the jig by capillary action using a syringe. Next, the ITO coated surfaces 12 at both ends in the length direction of the jig are connected to a charge amount measuring device (trade name “6514 type programmable electrometer” manufactured by Keithley Instruments Inc.), and the ITO coated surface 12 The amount of charge (nC) was measured by applying a voltage of +15 V between them for 60 seconds. The measured value of the obtained charge amount is divided by the area (cm ² ) of the ITO coat surface 12 facing the measurement sample injection portion 13, and this is charged (charge density per unit area) (nC / cm ² ). ).

[Method for evaluating polarity of colored resin particles]
The colored resin particles after washing obtained in the following Examples and Comparative Examples were prepared by using silicone oil (trade name “KF-96L-2CS” manufactured by Shin-Etsu Chemical Co., Ltd., kinematic viscosity at 25 ° C., 1 cSt, hereinafter “silicone”. (Referred to as “oil 2CS”) to obtain a silicone oil dispersion of colored resin particles having a solid content of 10% by weight.

  Next, 5 g of the obtained silicone resin dispersion of colored resin particles having a solid content of 10% by weight is weighed into a 20 mL glass bottle, and further 5 g of silicone oil 2CS is added so that the solid content of the colored resin particles becomes 5% by weight. In addition, a measurement sample was obtained.

  Next, a glass plate (width 8 mm, length 100 mm, thickness 0.7 mm, Matsunami Glass Industrial Co., Ltd., trade name “EAGLE”) is a pair of rectangular flat plates coated with ITO (flat ITO electrode) on one side. XG ”(hereinafter referred to as“ ITO coated glass plate ”), a spacer with a copper tape attached between the glass plates so that the glass plates are parallel to each other and the ITO coated surface is inside. A jig with a gap of 1 mm between the glass plates was produced. This jig was immersed in a measurement sample, and a voltage of +100 V was applied to the left side (anode, positive electrode) of one ITO-coated surface of the jig and allowed to stand for 10 seconds. After 10 seconds, if the jig is pulled up from the measurement sample and the colored resin particles adhere to the glass plate on the side (left side, one side) to which a voltage of +100 V is applied, the polarity of the colored resin particles is determined to be negative. If the colored resin particles are attached to the glass plate on the opposite side (right side, the other side) to which the voltage of +100 V is applied, the polarity of the colored resin particles is determined to be positive, and the colored resin particles are applied to any glass plate. If the particles were not attached, the colored resin particles were judged as “not clearly showing polarity”.

[Example 1]
(Preparation of reactive dispersant)
In a separable flask having an internal volume of 300 ml, silicone oil as a nonpolar solvent (trade name “KF-96L-1CS”, manufactured by Shin-Etsu Chemical Co., Ltd., kinematic viscosity at 25 ° C., 1 cSt, hereinafter “silicone oil 1CS” 100 parts by weight and 2,2′-azobis- (2,4-dimethylvaleronitrile) (manufactured by Nippon Finechem Co., Ltd.) as a polymerization initiator in advance, 2.0 parts by weight of a vinyl-based monomer having no polar group 5.0 parts by weight of a methyl methacrylate solution of 2,2′-azobis- (2,4-dimethylvaleronitrile) prepared by dissolving in 3.0 parts by weight of methyl methacrylate as a monomer, and a silicone macromonomer (Α-Butyl-ω- (3-methacryloxypropyl) polydimethylsiloxane, manufactured by JNC Corporation, trade name “Shiraplane (registered) Mark) FM-0721 ", number-average molecular weight 5850, a compound represented by the general formula (2), R ³ is a methyl group, R ⁴ is a propylene group, R ⁵ is methyl group , M≈62) and 95.9 parts by weight of α-methylstyrene dimer (manufactured by NOF Corporation, trade name “NOFMER (registered trademark) MSD)” were mixed. A reactive dispersant was obtained by subjecting the mixture to solution polymerization for 20 hours while stirring at 50 ° C. in a nitrogen atmosphere, and the number average molecular weight of the obtained reactive dispersant was 29100.

(Preparation of colored resin particles)
60 parts by weight of silicone oil 1CS as a nonpolar solvent, rutile titanium oxide particles as pigment particles (Ishihara Sangyo Co., Ltd., trade name “PT-401M”, specific surface area 20.5 m ² / g, average particle diameter 70 nm ) 20.0 parts by weight and 3,3,3-trifluoropropyltrimethoxysilane (Shin-Etsu Chemical Co., Ltd., trade name “KBM-7103”) as a fluorine group-containing silane compound (surface treatment agent) 0.02 Part by weight (0.15 mg per 1 m ² of surface area of titanium oxide particles) was placed in a 200 mL glass eggplant flask equipped with a reflux tube. The contents of the glass eggplant flask were heated at 150 ° C. for 8 hours with stirring. Thereby, the titanium oxide particles were surface-treated with 3,3,3-trifluoropropyltrimethoxysilane and surface-treated (coated with a layer derived from 3,3,3-trifluoropropyltrimethoxysilane). A liquid mixture containing titanium oxide particles was obtained.

  Add the surface-treated mixture containing titanium oxide and 80 parts by weight of the reactive dispersant to a 300 mL glass bead pot containing 500 g of zirconia beads (diameter 1 mm), and disperse by ball mill for 48 hours at room temperature. To obtain a dispersion. Thereafter, 200 parts by weight of silicone oil 1CS was added to the dispersion, and the zirconia beads were separated by filtration to obtain a dispersion containing surface-treated titanium oxide particles.

  The obtained dispersion liquid containing the surface-treated titanium oxide particles was transferred from the bead pot to a separable flask having an internal volume of 300 mL. In this separable flask, 580 parts by weight of silicone oil 1CS and 6 parts by weight of lauroyl peroxide (manufactured by NOF Corporation, trade name “Perroyl (registered trademark) L)) as a polymerization initiator are put, and lauroyl peroxide is converted into silicone. Dissolved in Oil 1CS. Next, in the separable flask, 30.0 parts by weight of styrene as a monofunctional aromatic vinyl monomer having no polar group, and a crosslinkable aromatic vinyl monomer having no polar group. Of divinylbenzene and 20.0 parts by weight of the reactive dispersant were added. Next, the separable flask is placed in a cleaning tank (length 230 mm × width 180 mm × height 110 mm inner dimension) of an ultrasonic cleaning machine (product name “VS-150” manufactured by VervoCrea Inc.) with an output of 150 W. It was immersed in water kept at 60 ° C. Thereafter, the content of the separable flask is subjected to dispersion polymerization at 60 ° C. for 8 hours in a nitrogen atmosphere and under ultrasonic irradiation to polymerize styrene, divinylbenzene, and the reactive dispersant, and then surface treatment. White particles, ie, colored resin particles, in which the titanium oxide particles thus coated were further coated with a resin layer were obtained.

  After the completion of the dispersion polymerization, the colored resin particles were settled and separated from the contents of the separable flask by centrifugation, and the isolated colored resin particles were redispersed in silicone oil 1CS. The sedimentation and redispersion operations were repeated three times to wash the colored resin particles.

  The colored resin particles after washing were dispersed in silicone oil 1CS to obtain a silicone oil dispersion of colored resin particles having a solid content of 10% by weight.

The average particle diameter of the colored resin particles in the obtained silicone oil dispersion was 371 nm. Further, the charge amount of the colored resin particles in the obtained silicone oil dispersion was 5.1 nC / cm ² , and thus the obtained colored resin particles were non-chargeable colored resin particles. Further, the obtained colored resin particles did not clearly show polarity.

[Example 2]
The amount of rutile titanium oxide particles (trade name “PT-401M”) used was changed to 25.0 parts by weight, and the amount of 3,3,3-trifluoropropyltrimethoxysilane used was 0.05 parts by weight (oxidized). The surface area of the titanium particles is changed to 0.10 mg per 1 m ² ), the amount of the dispersant used for obtaining the pigment particle dispersion is changed to 64 parts by weight, and the polar group is changed to 30.0 parts by weight of styrene. When using 15.0 parts by weight of methyl methacrylate as a monofunctional vinyl monomer and changing the amount of divinylbenzene to 15.0 parts by weight to obtain colored resin particles from the pigment particle dispersion Colored resin particles were obtained in the same manner as in Example 1 except that the amount of the dispersant used was changed to 16 parts by weight.

  A silicone oil dispersion of colored resin particles having a solid content of 10% by weight was obtained in the same manner as in Example 1 except that the colored resin particles of this example were used instead of the colored resin particles of Example 1.

The average particle diameter of the colored resin particles in the obtained silicone oil dispersion was 368 nm. Further, the charge amount of the colored resin particles in the obtained silicone oil dispersion was 9.3 nC / cm ² , and thus the obtained colored resin particles were non-chargeable colored resin particles. Further, the obtained colored resin particles did not clearly show polarity.

Example 3
(Heptadecafluoro-1,1,2,2-tetrahydrodecyl) trimethoxysilane instead of 0.06 part by weight of 3,3,3-trifluoropropyltrimethoxysilane as fluorine group-containing silane compound (surface treatment agent) (Product name “TSL8233” manufactured by Momentive Performance Materials Japan LLC) 0.03 parts by weight (0.07 mg per 1 m ² of surface area of titanium oxide particles) and 20.0 wt. The colored resin particles were obtained in the same manner as in Example 1 except that the amount of divinylbenzene was changed to 15.0 parts by weight.

  Next, a silicone oil dispersion of colored resin particles having a solid content of 10% by weight was obtained in the same manner as in Example 1 except that the colored resin particles of this example were used instead of the colored resin particles of Example 1.

The average particle diameter of the colored resin particles in the obtained silicone oil dispersion was 369 nm. Further, the charge amount of the colored resin particles in the obtained silicone oil dispersion was 5.2 nC / cm ² , and thus the obtained colored resin particles were non-chargeable colored resin particles. Further, the obtained colored resin particles did not clearly show polarity.

Example 4
The amount of rutile titanium oxide particles (trade name “PT-401M”) was changed to 25.0 parts by weight, and the amount of 3,3,3-trifluoropropyltrimethoxysilane was changed to 0.03 parts by weight (oxidized). Example 1 except that the surface area of titanium particles is changed to 0.06 mg per 1 m ² , the amount of styrene used is changed to 20.0 parts by weight, and the amount of divinylbenzene is changed to 15.0 parts by weight. Similarly, colored resin particles were obtained.

  Next, a silicone oil dispersion of colored resin particles having a solid content of 10% by weight was obtained in the same manner as in Example 1 except that the colored resin particles of this example were used instead of the colored resin particles of Example 1.

The average particle diameter of the colored resin particles in the obtained silicone oil dispersion was 401 nm. Further, the charge amount of the colored resin particles in the obtained silicone oil dispersion was 6.8 nC / cm ² , and thus the obtained colored resin particles were non-chargeable colored resin particles. Further, the obtained colored resin particles did not clearly show polarity.

Example 5
Instead of 20.0 parts by weight of rutile titanium oxide particles (trade name “PT-401M”), rutile titanium oxide particles (trade name “PT-501R”, manufactured by Ishihara Sangyo Co., Ltd., specific surface area 8.9 m ² / g) 20.0 parts by weight), and the amount of 3,3,3-trifluoropropyltrimethoxysilane used is 0.02 parts by weight (0.11 mg per 1 m ² of surface area of titanium oxide particles). Colored resin particles were obtained in the same manner as in Example 1 except that the amount of styrene was changed to 20.0 parts by weight and the amount of divinylbenzene was changed to 15.0 parts by weight.

  Next, a silicone oil dispersion of colored resin particles having a solid content of 10% by weight was obtained in the same manner as in Example 1 except that the colored resin particles of this example were used instead of the colored resin particles of Example 1.

The average particle diameter of the colored resin particles in the obtained silicone oil dispersion was 389 nm. Further, the charge amount of the colored resin particles in the obtained silicone oil dispersion was 6.1 nC / cm ² , and thus the obtained colored resin particles were non-chargeable colored resin particles. Further, the obtained colored resin particles did not clearly show polarity.

Example 6
Dispersant used to obtain pigment particle dispersion by changing the amount of 3,3,3-trifluoropropyltrimethoxysilane to 0.6 parts by weight (1.46 mg per 1 m ² of surface area of titanium oxide particles) In the same manner as in Example 1, except that the amount of the dispersant is changed to 64 parts by weight and the amount of the dispersant used for obtaining the colored resin particles from the pigment particle dispersion is changed to 16 parts by weight. Obtained.

  A silicone oil dispersion of colored resin particles having a solid content of 10% by weight was obtained in the same manner as in Example 1 except that the colored resin particles of this example were used instead of the colored resin particles of Example 1.

The average particle diameter of the colored resin particles in the obtained silicone oil dispersion was 408 nm. Further, the charge amount of the colored resin particles in the obtained silicone oil dispersion was 9.2 nC / cm ² , and thus the obtained colored resin particles were non-chargeable colored resin particles.

[Comparative Example 1]
The amount of rutile titanium oxide particles (trade name “PT-401M”) used was changed to 25.0 parts by weight, and the amount of 3,3,3-trifluoropropyltrimethoxysilane used was 0.01 parts by weight (oxidized). change in surface area 1 m ² per 0.02 mg) of the particles of titanium, the amount of dispersing agent used in obtaining the pigment particle dispersion was changed to 64 parts by weight, used to obtain colored resin particles from the pigment particle dispersion Colored resin particles were obtained in the same manner as in Example 1 except that the amount of the dispersing agent was changed to 16 parts by weight.

  A silicone oil dispersion of colored resin particles having a solid content of 10% by weight was obtained in the same manner as in Example 1 except that the colored resin particles of this comparative example were used in place of the colored resin particles of Example 1.

The average particle diameter of the colored resin particles in the obtained silicone oil dispersion was 361 nm. Further, the charge amount of the colored resin particles in the obtained silicone oil dispersion was 15.9 nC / cm ² , and thus the obtained colored resin particles were chargeable colored resin particles. Further, the obtained colored resin particles did not clearly show polarity.

[Comparative Example 2]
Colored resin in the same manner as in Example 1 except that the amount of 3,3,3-trifluoropropyltrimethoxysilane used was changed to 1.4 parts by weight (3.41 mg per 1 m ² of surface area of titanium oxide particles). Particles were obtained.

  A silicone oil dispersion of colored resin particles having a solid content of 10% by weight was obtained in the same manner as in Example 1 except that the colored resin particles of this comparative example were used in place of the colored resin particles of Example 1.

The average particle diameter of the colored resin particles in the obtained silicone oil dispersion was 412 nm. Further, the charge amount of the colored resin particles in the obtained silicone oil dispersion was 20.1 nC / cm ² , and thus the obtained colored resin particles were chargeable colored resin particles. Further, the obtained colored resin particles did not clearly show polarity.

  Table 1 summarizes the types and amounts used of the raw materials used, the specific surface area of the titanium oxide used, and the evaluation results of the resulting colored resin particles in Examples 1 to 6 and Comparative Examples 1 and 2. .

表１の実施例１〜６と比較例１・２との比較により、表面処理剤の量を顔料粒子の表面積１ｍ²あたり０．０５〜２．５０ｍｇにした場合に（実施例１〜６）、表面処理剤の量が顔料粒子の表面積１ｍ²あたり０．０５ｍｇ未満の場合（比較例１）及び表面処理剤の量が顔料粒子の表面積１ｍ²あたり２．５０ｍｇを超える場合（比較例２）と比較して、着色樹脂粒子の帯電性を低下させることができ、前述の測定方法による着色樹脂粒子の帯電量の測定値を１０ｎＣ／ｃｍ²以下とすることができることが分かった。

When Examples 1-6 in Table 1 and Comparative Examples 1 and 2 were compared, the amount of the surface treatment agent was 0.05-2.50 mg per 1 m ² of the surface area of the pigment particles (Examples 1-6). When the amount of the surface treatment agent is less than 0.05 mg per 1 m ² of the surface area of the pigment particles (Comparative Example 1) and when the amount of the surface treatment agent exceeds 2.50 mg per 1 m ² of the surface area of the pigment particles (Comparative Example 2) It was found that the chargeability of the colored resin particles can be reduced, and the measured value of the charge amount of the colored resin particles by the measurement method described above can be 10 nC / cm ² or less.

DESCRIPTION OF SYMBOLS 1 Pigment particle 2 Surface treatment agent origin layer 3 Resin layer

Claims (6)

Pigment particles made of metal oxide;
A layer derived from a surface treatment agent that coats the pigment particles;
A resin layer covering the layer derived from the surface treatment agent,
The surface treatment agent has the following general formula: R ¹ _n R ² _p SiX _m (1)
(In the above formula, R ¹ represents a fluorine atom-containing alkyl group, a fluorine atom-containing aryl group, or a fluorine atom-containing aralkyl group, R ² represents an alkyl group, and X represents an alkoxy group or a chlorine atom. M represents an integer of 1 to 3, n represents an integer of 1 to 3, p represents an integer of 0 to 2, and m + n + p = 4)
A fluorine group-containing silane compound represented by:
The amount of the layer derived from the surface treatment agent is 0.05 to 2.50 mg per 1 m ² of the surface area of the pigment particles,
It is sandwiched between a pair of indium tin oxide electrodes which are a pair of flat plates parallel to each other and a distance of 50 μm in a state where the solid content is dispersed in a silicone oil having a kinematic viscosity of 100 cSt or less at a solid concentration of 20% by weight. A non-chargeable colored resin particle which exhibits a measured charge amount of 10 nC / cm ² or less when a voltage of 15 V is applied for 60 seconds.   2. The non-chargeable colored resin particle according to claim 1, wherein the resin layer is made of a polymer containing a structural unit derived from an aromatic vinyl monomer having no polar group. The resin layer is composed of a polymer of a reactive dispersant and an aromatic vinyl monomer having no polar group,
The non-charging property according to claim 2, wherein the reactive dispersant is a copolymer of a silicone macromonomer, a vinyl monomer having no polar group, and α-methylstyrene dimer. Colored resin particles.   The non-chargeable colored resin particles according to any one of claims 1 to 3, wherein an average particle diameter is in a range of 50 to 1000 nm.   A non-chargeable colored resin particle dispersion comprising a non-polar solvent and the non-charged colored resin particles according to claim 1 dispersed in the non-polar solvent. The uncharged colored resin particle dispersion according to claim 5,
The electrophoretic display device, wherein the non-charged colored resin particle dispersion further includes charged colored resin particles having a color tone different from that of the non-charged colored resin particles dispersed in the non-polar solvent.

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