JP2013082875A - Non-electrostatic colored resin particle and usage thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-electrostatic colored resin particle which never inhibits electrophoresis of colored electrophoretic particles.SOLUTION: The non-electrostatic colored resin particle is obtained by covering the surface of a pigment particle including a metal oxide treated with a surface treatment agent with a polymer of a silicone macro monomer, a vinyl monomer free from polar group, a reactive dispersant obtained by polymerizing α-methylstyrene dimer, and an aromatic monomer free from polar group in the presence of a non-polar solvent. When the particle is sealed between ITO electrodes which are parallel flat plates with an interelectrode distance of 50 μm with it being dispersed in a silicone oil having a dynamic viscosity of 100 cSt at a solid content concentration of 10 wt.%, and voltage of 15V is applied thereto for 60 seconds, the particle shows an electric charge amount of 20 nC/cmor less.

Description

  The present invention relates to non-chargeable colored resin particles and uses thereof. More specifically, the present invention relates to a non-charged colored resin particle that stably exhibits non-charge properties, a non-charged colored resin particle dispersion using the same, and an electrophoretic display device.

In recent years, an image display device (electrophoretic display device) using electrophoresis of colored resin particles exhibiting chargeability has attracted attention. Because this device has characteristics that are not found in conventional display devices, such as having a memory property that the viewing angle is as wide as ordinary printed matter, power consumption is low, and the displayed information does not disappear even when the power is turned off, etc. It is expected to spread as an inexpensive display device.
Here, an example in which the colored resin particles are used as an image display element of an image display device will be introduced. Display in which colored resin particles exhibiting positive and / or negative chargeability as an image display element are dispersed in a dispersion medium between two electrode substrates that are arranged to face each other with a spacer interposed therebetween. A liquid crystal is sealed to form a display panel. By applying an electric field between the two electrode substrates of the display panel, colored resin particles exhibiting chargeability can be electrophoresed to obtain a display (Patent Documents 1 to 4).

Recently, attempts have been made to make such an image display device display in multiple colors.
As a conventional technique related to multicolor display, for example, a method using a dispersion medium colored by dissolving a dye or the like as described in Patent Document 2 is known. However, in the method of Patent Document 2, when colored particles that exhibit electrophoretic properties by application of a voltage (hereinafter also referred to as “colored electrophoretic particles”) are arranged on a transparent electrode substrate serving as a display surface, There is a problem that a mixed color is generated when a dispersion medium having a different color tone enters the gap, and a desired color display is not performed.
As a technique for solving the problem of Patent Document 2, for example, as described in Patent Document 3, colored particles (charged colored particles) that move in a dispersion medium in response to an electric field, and In combination with non-charged colored particles that do not move through the dispersion medium (also referred to as “uncharged colored particles”), that is, the base color corresponding to paper is displayed on the non-charged colored particles on the paper. There is known a method of displaying the color of an image corresponding to a character or a picture drawn in Fig. 1 on chargeable colored particles.

However, in the technique of Patent Document 3, when the charged colored particles are moved onto the electrode substrate opposite to the display surface to display the color (base color) due to the non-charged colored particles, they are arranged on the opposite electrode. There is a problem that the color of the charged colored particles is visible from the display surface.
As a technique for solving the problem of Patent Document 3, for example, the surface of titanium oxide as a colorant is uniformly coated with a resin having a large difference in refractive index from the dispersion medium as described in Patent Document 4. A method using white non-charged colored particles is known.

JP 2006-293028 A Japanese Patent No. 2551783 JP 2001-188269 A JP 2008-122468 A

The inventors of the present invention have conducted a preliminary test in order to seek a measure for further strengthening the color development by the non-charged colored particles in the technique of dispersing the non-charged colored particles in the solvent as in Patent Documents 3 and 4 to develop the color. went.
In the non-charged colored particles described in Patent Document 4, those having a sufficiently low charge amount cannot be obtained, and the polar group contained in the resin coated with the colored pigment is charged during electrophoresis in a non-polar solvent. It has been found that the desired display color cannot be obtained because the aggregation with the colored particles is promoted.
An object of the present invention is to solve the above-described problems and to provide non-electrophoretic non-chargeable colored resin particles that do not inhibit electrophoresis of the chargeable colored particles and cause less color mixing.

  As a result of intensive studies, the inventors of the present invention have found that the surface of the pigment particles made of a metal oxide treated with a surface treatment agent has a non-polar solvent in the presence of a silicone macromonomer and a vinyl having no polar group. Non-charged colored resin particles coated with a polymer of a monomer and a reactive dispersant obtained by polymerizing α-methylstyrene dimer and an aromatic monomer having no polar group Has arrived at the present invention by surprisingly finding that it is possible to suppress the occurrence of color mixing without causing aggregation with colored particles (chargeable colored particles) that move in the dispersion medium in response to an electric field.

Thus, according to the present invention, a silicone macromonomer, a vinyl monomer having no polar group, in the presence of a nonpolar solvent, on the surface of a pigment particle composed of a metal oxide treated with a surface treatment agent, and , Non-chargeable colored resin particles coated with a polymer of a reactive dispersant obtained by polymerizing α-methylstyrene dimer and an aromatic monomer having no polar group, In a state where it is dispersed in a silicone oil having a viscosity of 100 centistokes or less at a solid content concentration of 10% by weight, it is sealed between ITO electrodes that are parallel plates with an interelectrode distance of 50 μm, and a voltage of 15 V is applied for 60 seconds. In this case, non-chargeable colored resin particles are provided that exhibit a charge amount of ²⁰ nC / cm ² or less.

Moreover, according to this invention, the non-chargeable colored resin particle dispersion containing the said non-charged colored resin particle and the nonpolar solvent in which the said non-charged colored resin particle was disperse | distributed is provided.
Furthermore, according to the present invention, there is provided an electrophoretic display device obtained by using the non-chargeable colored resin particle dispersion.

According to the present invention, since the charge amount is low (20 nC / cm ² or less) and the non-charged colored resin particles themselves have substantially no polarity, interaction with the polar group having the charged colored resin particles during migration is possible. Reduced. As a result, it is possible to provide non-chargeable colored resin particles that break the charging polarity or suppress electrostatic aggregation and do not cause color mixing due to aggregation with the charged colored resin particles having a polar group.
The non-charged colored resin particles are a polymer of a reactive dispersant, an aromatic monomer, and a silicone macromonomer that is the same as or different from the silicone macromonomer used during the production of the reactive dispersant by polymerization. In the case of particles covering the surface of the pigment particles, it is possible to provide non-chargeable colored resin particles capable of suppressing the occurrence of color mixing due to aggregation with the chargeable colored resin particles.

  The silicone macromonomer is represented by the following general formula (1)

(R ₁ is a hydrogen atom or a methyl group, R ₂ is an alkylene group having 2 to 4 carbon atoms, R ₃ is the same or different alkyl group or phenyl group having 1 to 4 carbon atoms, and n is an integer). In the case of the compound, it is possible to provide uncharged colored resin particles capable of suppressing the occurrence of color mixing due to aggregation with the charged colored resin particles.
Furthermore, when the surface treatment agent is a coupling agent, it is possible to provide non-chargeable colored resin particles that can suppress the occurrence of color mixing due to aggregation with the chargeable colored resin particles.

  Further, the surface treating agent is represented by the following general formula (2), (3) or (4).

(Wherein R1 is an alkyl group having 8 to 20 carbon atoms, R2 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R3 is an alkoxy group having 1 to 6 carbon atoms)
In the case of the compound represented by the formula (1), it is possible to provide non-chargeable colored resin particles capable of suppressing the occurrence of color mixing due to aggregation with the chargeable colored resin particles.
Furthermore, when the non-charged colored resin particles have an average particle diameter of 50 to 1000 nm, it is possible to provide non-charged colored resin particles capable of suppressing color mixing due to aggregation with the chargeable colored resin particles.

It is the schematic of the non-chargeable colored resin particle of this invention. It is the schematic of the measuring device of the charge amount of a non-chargeable colored resin particle.

(Non-chargeable colored resin particles)
The non-charged colored resin particles of the present invention have a silicone macromonomer and a vinyl-based monomer having no polar group in the presence of a non-polar solvent on the surface of the pigment particles made of a metal oxide treated with a surface treating agent. It is covered with a polymer of a monomer and a reactive dispersant obtained by polymerizing α-methylstyrene dimer and an aromatic monomer having no polar group. These non-charged colored resin particles enclose pigment particles made of a metal oxide treated with a surface treatment agent, and a coating made of a polymer of a mixture of a reactive dispersant, a polymerization initiator and an aromatic monomer. With layers.
In the present invention, the term “non-chargeable” means that neither positive nor negative reaction is exhibited in the polarity evaluation method and the above charge amount is obtained. The polarity evaluation method and the charge amount measurement method will be described in Examples.

(1) Pigment particles The pigment particles are not particularly limited as long as they are metal oxide particles used as a pigment in the technical field. For example, iron oxide pigments such as mica-like iron oxide and iron black, red lead, Lead oxide pigments such as lead; titanium oxide pigments such as titanium white, titanium yellow and titanium black; zinc oxide pigments such as cobalt oxide and zinc yellow; molybdenum oxide pigments such as molybdenum red and molybdenum white It is done.
The average particle diameter of the pigment particles is appropriately set according to the request from the electrophoretic display device. In general, pigment particles having an average particle diameter of 50 to 300 nm are used.
The shape of the pigment particles is not particularly limited, but is preferably as close to a spherical shape as possible in consideration of dispersion stability in the dispersion medium.
Furthermore, the pigment particles preferably have a specific surface area of 0.5 to 300 m ² / g.

  Although it does not specifically limit as content of the said pigment particle, A preferable minimum is 10 weight part with respect to 100 weight part of aromatic monomers mentioned later, and a preferable upper limit is 800 weight part. When the content of the pigment particles is less than 10 parts by weight, aggregation of the non-charged colored resin particles may occur during the production of the non-charged colored resin particles. When the content of the pigment particles exceeds 800 parts by weight, the resulting non-charged colored resin particles may be fibrous and the desired non-charged colored resin particles may not be obtained. A more preferred lower limit is 20 parts by weight, and a more preferred upper limit is 400 parts by weight.

The surface of the pigment particles is treated with a surface treatment agent.
Surface treatment agents include aluminum (aluminate) coupling agents, titanium (titanate) coupling agents, zirconium (zirconate) coupling agents, phosphorus coupling agents, silicon (silane) coupling agents, etc. A coupling agent is preferred.
Examples of the aluminate coupling agent include acetooctadecyloxyaluminum diisopropionate, and the following formula (I):

(Wherein R1 is an alkyl group having 8 to 20 carbon atoms, R2 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R3 is an alkoxy group having 1 to 6 carbon atoms) Preferably used.

  Examples of titanate coupling agents include isopropyl triisostearoyl titanate, isopropyl tristearoyl titanate, isopropyl trioctanoyl titanate, isopropyl dimethacrylisostearoyl titanate, isopropyl tridodecylbenzenesulfonyl titanate, isopropyl isostearoyl diacryl titanate, isopropyl trititanate. (Dioctyl phosphate) titanate, isopropyl tricumyl phenyl titanate, isopropyl tris (dioctyl pyrophosphate) titanate, isopropyl tri (n-aminoethyl-aminoethyl) titanate, tetraisopropyl bis (dioctyl phosphite) titanate, tetraoctyl bis (ditridecyl) Phosphite) Titanate, Tet (2,2-diallyloxymethyl-1-butyl) bis (ditridecyl) phosphite titanate, dicumylphenyloxyacetate titanate, bis (dioctylpyrophosphate) oxyacetate titanate, diisostearoylethylene titanate, bis (dioctylpaolophosphate) Ethylene titanate, bis (dioctyl paophosphate) diisopropyl titanate, tetramethyl orthotitanate, tetraethyl orthotitanate, tetrapropyl orthotitanate, tetraisopropyl tetraethyl orthotitanate, tetrabutyl orthotitanate, butyl polytitanate, tetraisobutyl orthotitanate, 2-ethylhexyl titanate , Stearyl titanate, cresyl titanate monomer, cresyl Titanate polymer, diisopropoxy-bis- (2,4-pentadionate) titanium (IV), diisopropyl-bis-triethanolamino titanate, octylene glycol titanate, titanium lactate, acetoacetic estiltitanate, diiso Propoxybis-8acetylacetonato) titanium, di-n-butoxybis (triethanolaluminate) titanium, dihydroxybis (lactato) titanium, titanium-isopropoxyoctylene glycolate, tetra-n-butoxytitanium polymer, tri-n- Butoxytitanium monostearate polymer, butyl titanate dimer, titanium acetylacetonate, polytitanium titanium acetylacetonate, titanium octylene glycolate, titanium lactate ammonium , Titanium lactate ethyl ester, titanium triethanolaminate, polyhydroxy titanium stearate.

  Examples of the zirconate coupling agent include zirconium butyrate, zirconium acetylacetonate, acetylacetone zirconium butyrate, zirconium lactate, zirconium stearate butyrate, tetra (triethanolamine) zirconate, tetraisopropyl zirconate and the like.

  Examples of phosphorus coupling agents include acryloyloxyethyl phthaloxyethyl diethyl phosphate, di (methacryloyloxyethyl phthaloxyethyl) diethyl pyrophosphate, di (methacryloyloxyethyl phthaloxyethyl) methyl phosphite, and di (methacryloyloxyethyl). Phthaloxyethyl) phosphate, di (acryloyloxyethylphthaloxyethyl) pyrophosphate, di (methacryloyloxyethylphthaloxyethyl) phosphite, methacryloyloxyethyl maleoxyethyl diethyl phosphate, di (acryloyloxyethyl maleoxyethyl) diethyl pyro Phosphate, di (methacryloyloxyethylmaleoxyethyl) ethyl phosphite, di (acryloyloxy) Ethyl maleoxyethyl) phosphate, di (methacryloyloxyethyl maleoxyethyl) pyrophosphate, di (acryloyloxyethyl maleoxyethyl) phosphite, methacryloyloxyethyl succinoxyethyl diethyl phosphate, di (methacryloyloxyethyl succinoxyethyl) ) Dimethylpyrophosphate, di (methacryloyloxyethyl succinoxyethyl) ethyl phosphite, di (methacryloyloxyethyl succinoxyethyl) phosphate, di (methacryloyloxyethyl succinoxyethyl) pyrophosphate, di (methacryloyloxyethylsk Synoxyethyl) phosphite, di (N-acrylaminomethyl) phosphite, di (N-acrylaminomethyl) pyropho Feto, di (N- acrylic aminomethyl) phosphate and the like.

As the surface treatment agent, fatty acids such as stearic acid and oleic acid and their metal salts, and inorganic compounds such as silica, aluminum oxide, and aluminum hydroxide can also be used.
Among the above surface treatment agents, the aluminate coupling agent of the formula (I) is preferably used.
In formula (I), R1 is an alkyl group having 8 to 20 carbon atoms, R2 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R3 is an alkoxy group having 1 to 6 carbon atoms.
Examples of the alkyl group having 8 to 20 carbon atoms of R1 in the above structural formula include octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, icosyl, and the like. Examples of the alkyl group having 1 to 3 carbon atoms include methyl, ethyl, n-propyl, i-propyl and the like, and R3 represents an alkoxy group having 1 to 6 carbon atoms such as methoxy, ethoxy, propoxy, isopropoxy, butoxy. , Isobutoxy, sec-butoxy, pentoxy, hexoxy and the like.

  Examples of the aluminate coupling agent represented by such a formula include acetoalkoxy aluminum diisopropylate, ethyl acetoacetate aluminum diisopropylate, aluminum tris (ethyl acetoacetate), alkyl acetoacetate aluminum diisopropylate, Aluminum monoacetylacetonate bis (ethyl acetoacetate), aluminum tris (acetylacetonate), etc. are mentioned.

The amount of the surface treatment agent used is usually 1 to 20 parts by weight, preferably 2 to 15 parts by weight with respect to 100 parts by weight of the pigment particles, although it depends on the type and amount of the pigment particles and the surface treatment agent. is there.
If the usage-amount of a surface treating agent is said range, the surface state suitable for this invention can be given to a pigment particle. When the amount of the surface treatment agent used is less than 1 part by weight, the effect of improving the dispersion stability may not be sufficiently expected. When the amount exceeds 20 parts by weight, the effect is not so much improved even if the amount used is increased. There are many cases.

(2) Coating layer The coating layer contains pigment particles and is composed of a polymer of a mixture of a reactive dispersant, a polymerization initiator and an aromatic monomer.
(2-1) Reactive Dispersant The reactive dispersant is obtained by polymerizing a silicone macromonomer, a vinyl monomer having no polar group, and α-methylstyrene dimer in the presence of a nonpolar solvent. It is a dispersant.
By not including the structure derived from the polar group in the coating layer, aggregation of the charged colored resin particles and the non-charged colored resin particles can be prevented.
As the silicone macromonomer, various compounds having a polymerizable unsaturated group at one end and having a silicone unit (organosiloxane unit such as dimethylpolysiloxane unit) can be used.

    (A) As a silicone macromonomer, for example, the following formula:

(In the formula, R ₁ is a hydrogen atom or a methyl group, R ₂ is an alkylene group having 2 to 4 carbon atoms, R ₃ is the same or different from each other, and is an alkyl group or phenyl group having 1 to 4 carbon atoms. And n is an integer).
Examples of the alkylene group having 2 to 4 carbon atoms of R ₂ in the above structural formula include methylene, ethylene, trimethylene, tetramethylene, propylene, ethylethylene and the like, and examples of the alkyl group having 1 to 4 carbon atoms of R ₃ include , Methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, tert-butyl and the like.
Specific examples of the silicone macromonomer having the structure represented by the above formula include α-butyl-ω- (3-methacryloxypropyl) polydimethylsiloxane.
The molecular weight of the silicone macromonomer is preferably in the range of a number average molecular weight of 500 to 40000, more preferably 1000 to 20000. Two or more types of silicone macromonomers may be mixed and used. N in the above structural formula is a number that can give this number average molecular weight.

(B) The vinyl monomer is a vinyl monomer having no polar group.
Since the vinyl monomer does not have a polar group, the charge amount of the non-chargeable colored resin particles of the present invention can be sufficiently reduced. More specifically, the polar group is a vinyl containing no 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 a system monomer.

  Examples of such vinyl monomers include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, o-n-butyl styrene, mn-butyl styrene, pn-butyl styrene, o-tert-butyl styrene, m-tert-butyl styrene, p-tert-butyl styrene, on-hexyl styrene, m -N-hexyl styrene, pn-hexyl styrene, on-oct-styrene, mn-octyl styrene, pn-octyl styrene, on-nonyl styrene, mn-nonyl styrene, p- n-nonylstyrene, on-decylstyrene, mn-decylstyrene, pn-decylstyrene, on-dodecy Styrene, mn-dodecylstyrene, pn-dodecylstyrene, n-methoxystyrene, o-phenylstyrene, m-phenylstyrene, p-phenylstyrene, 1-vinylnaphthalene, 2-vinylnaphthalene, isoprene, isobutene, Examples include propylene, ethylene, and derivatives thereof.

The amount of the vinyl monomer used is preferably 2 to 50 parts by weight with respect to 100 parts by weight of the silicone macromonomer. More preferably, it is 5 to 25 parts by weight.
When the amount of the vinyl monomer used is less than 2 parts by weight, the affinity between the pigment particles and the reactive dispersant is deteriorated, so that it is difficult to chemically combine them. As a result, the dispersion of the non-chargeable colored resin particles Stability may deteriorate. On the other hand, when the amount exceeds 50 parts by weight, the affinity between the pigment particles and the nonpolar solvent is deteriorated, and the dispersion stability of the non-charged colored resin particles may be deteriorated.

    (C) As the α-methylstyrene dimer, an addition cleavage type chain transfer agent having a structure represented by the following formula is preferable.

Polymerizable copolymer having molecular weight controlled by copolymerization of α-methylstyrene dimer, silicone macromonomer and vinyl monomer, and having a reactive double bond derived from α-methylstyrene dimer at the terminal Coalescence is obtained.
The amount of α-methylstyrene dimer used varies depending on the number average molecular weight of the reactive dispersant, but is generally 0.1 to 10 parts by weight with respect to 100 parts by weight of the silicone macromonomer.
If the amount of α-methylstyrene dimer used is less than 0.1 parts by weight, the number average molecular weight of the resulting reactive dispersant may become too large. On the other hand, when the amount exceeds 10 parts by weight, it is difficult to control the molecular weight by α-methylstyrene dimer, the number average molecular weight cannot be lowered, and the effect commensurate with the addition may not be obtained.

By carrying out dispersion polymerization of the reactive dispersant and the vinyl monomer, the silicone chain derived from the silicone macromonomer is chemically immobilized on the surface while preventing aggregation due to coalescence of the particles during polymerization. Chargeable colored resin particles can be obtained.
Although the molecular weight of a reactive dispersing agent is not specifically limited, It is preferable that it is the range of the weight average molecular weight 3000-200000. A more preferable range is 5000 to 100,000.

The content of the reactive dispersant in the non-chargeable colored resin particles of the present invention is not particularly limited, but the preferred lower limit is 1 part by weight and the preferred upper limit is 150 weights with respect to 100 parts by weight of the aromatic monomer described later. Part. If the content of the reactive dispersant is less than 1 part by weight, desired colorability may not be obtained. Even if the content of the reactive dispersant exceeds 150 parts by weight, no further effect is obtained.
A more preferred lower limit is 10 parts by weight, a more preferred upper limit is 120 parts by weight, a still more preferred lower limit is 20 parts by weight, and a still more preferred upper limit is 100 parts by weight.

(D) Production method of 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, It can be obtained by copolymerization by heating with stirring by the method. A polymerization initiator may be used for the copolymerization. The polymerization initiator is usually used by being dissolved in advance in a vinyl monomer.

  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 naphthene hydrocarbons such as liquid paraffin; Examples thereof include silicone oils such as dimethyl silicone oil, phenylmethyl silicone oil, dialkyl silicone oil, alkylphenyl silicone oil, cyclic polydialkylsiloxane, and cyclic polyalkylphenylsiloxane.

Of these, silicone oils such as dimethyl silicone oil, phenyl methyl silicone oil, dialkyl silicone oil, alkyl phenyl silicone oil, cyclic polydialkyl siloxane and cyclic polyalkyl phenyl siloxane are considered in consideration of the environmental impact of the working environment. preferable.
In order to efficiently disperse by ultrasonic waves in the production of the reactive dispersant, the silicone oil used is more preferably an oil having a kinematic viscosity measured by JIS K 2283 of 100 centistokes or less.
The amount of the nonpolar solvent used for preparing the copolymer as the reactive dispersant is preferably 20 to 400 parts by weight with respect to 100 parts by weight of the monomer composition. More preferably, it is 50-200 weight part.

As the polymerization initiator used for the polymerization, an oil-soluble peroxide-based or azo-based initiator is used. For example, for example, benzoyl peroxide, lauroyl peroxide, octanoyl peroxide, orthochloroperoxide benzoyl, orthomethoxybenzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxydicarbonate, cumene hydroperoxide, cyclohexanone peroxide, t -Peroxide-based initiators such as butyl hydroperoxide and 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-triazobis (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- (carbamoylazo) isobutyronitrile, 4,4-azobis (4-cyanovaleric acid), dimethyl-2,2-azobisisobutyrate, etc. In particular, benzoyl peroxide, which is 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, Organic peroxides such as reduction lauroyl, dimethyl-2,2-azobis (2-methyl propionate) azo initiators are preferred.
The polymerization initiator is preferably contained in the monomer composition (a mixture of a silicone macromonomer and a vinyl monomer) in an amount of about 0.1 to 5% by weight.

The reaction temperature and time in the above copolymerization are not particularly limited. For example, the type and amount of polymerization initiator used and the silicone macromonomer, vinyl monomer, and α-methylstyrene dimer used. It is possible to adjust timely depending on the reactivity of For example, it is preferable to carry out in the range of reaction temperature 40-150 degreeC and reaction time 0.5-50 hours. More preferably, the reaction temperature is 40 to 80 ° C., and the reaction time is 2 to 25 hours.
The polymerization atmosphere in the copolymerization may be an air atmosphere or an inert gas atmosphere. However, in order to prevent a delay in polymerization rate and inhibition of polymerization due to oxygen in the atmosphere, the polymerization atmosphere is preferably performed in an inert gas atmosphere. 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 used nonpolar solvent 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.

(2-2) Aromatic monomer having no polar group The aromatic monomer having no polar group has an aromatic group, and is a cyano group, amino group, ammonium group, hydroxyl group, carbonyl group. , A nitro group, a thiol group, a sulfonyl group, a phosphonyl group, a halogen group, and a glycidyl group-free monomer. By not including the structure derived from the polar group in the coating layer, aggregation of the charged colored resin particles and the non-charged colored resin particles can be prevented.

  Examples of the aromatic 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, 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, pn-decyl styrene, -N-dodecylstyrene, mn-dodecylstyrene, pn-dodecylstyrene, n-methoxystyrene, o-phenylstyrene, m-phenylstyrene, p-phenylstyrene, m-ethylbenzene, p-ethylbenzene, divinylbenzene , 1-vinylnaphthalene, 2-vinylnaphthalene and derivatives thereof.

In addition to the components derived from the silicone macromonomer used in the production of the reactive dispersant, the non-charged colored resin particles of the present invention are newly added with the silicone macromonomer together with the reactive dispersant and the aromatic monomer. It is preferable to contain a component polymerized in this manner. By newly adding a silicone macromonomer, the obtained non-chargeable colored resin particles do not aggregate more with the other colored charged resin particles having a polar group, and are less likely to mix colors.
Here, the silicone macromonomer to be newly added may be the same as or different from the silicone macromonomer used during the production of the reactive dispersant.

  The amount of the silicone macromonomer to be newly added is not particularly limited, but is preferably 200 parts by weight or less with respect to 100 parts by weight of the aromatic monomer. Even if the addition amount exceeds 200 parts by weight, no further effect can be obtained. A more preferred upper limit is 150 parts by weight. Further, the lower limit of the addition amount is not particularly limited, but it is preferably 30 parts by weight or more with respect to 100 parts by weight of the aromatic monomer.

(2-3) Forming method of coating layer The coating layer can be formed by polymerizing a reactive dispersant and an aromatic monomer having no polar group in the presence of a polymerization initiator. This polymerization is preferably a dispersion polymerization in a nonpolar solvent.
In order to prevent coalescence during polymerization, the dispersion polymerization is preferably performed under ultrasonic irradiation. Also. You may use together mechanical stirring apparatuses, such as a magnetic stirrer.
The dispersion polymerization is preferably performed in an inert gas atmosphere for the same reason as in the production method of the reactive dispersant. A more preferable inert gas atmosphere is a nitrogen gas atmosphere.

(2-4) Polymerization initiator As the polymerization initiator for polymerizing the coating layer, an oil-soluble peroxide-based or azo-based initiator is used. For example, for example, benzoyl peroxide, lauroyl peroxide, octanoyl peroxide, orthochloroperoxide benzoyl, orthomethoxybenzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxydicarbonate, cumene hydroperoxide, cyclohexanone peroxide, t -Peroxide-based initiators such as butyl hydroperoxide and 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-triazobis (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-dimethylvalero) Nitrile), 2- (carbamoylazo) isobutyronitrile, 4,4-azobis (4-cyanovaleric acid), dimethyl-2,2-azobisisobutyrate, etc. Especially cyano group, carboxyl group, amide Organic initiators such as benzoyl peroxide and lauroyl peroxide, which are polymerization initiators that do not contain polar groups such as groups, ammonium groups and sulfonic acid groups, dimethyl-2,2-azobis (2-methylpropionate), etc. The azo initiator is preferred.

There are no particular limitations on the reaction temperature and time in the dispersion polymerization, and it is possible to use the polymerization initiator with timely adjustment according to the type and amount of polymerization initiator used and the amount of vinyl monomer used in the reaction. . Preferably, the reaction can be carried out at a reaction temperature of 40 to 120 ° C. and a reaction time of 0.5 to 50 hours. More preferably, the reaction temperature is 40 to 80 ° C., and the reaction time is 2 to 12 hours.
As the nonpolar solvent, any of those mentioned in the description of the production of the reactive dispersant can be used.

The coating layer can adjust the coating thickness and coating ratio by selecting the amount of the reactive dispersant and the aromatic monomer, thereby controlling the particle size of the non-charged colored resin particles. It is.
For example, the particle diameter can be reduced by increasing the proportion of the reactive dispersant relative to the aromatic monomer. Moreover, the particle diameter of non-chargeable colored resin particles can be reduced by selecting and using an aromatic monomer having a high affinity for a non-polar solvent.

(3) Properties of non-charged colored resin particles The inventors consider that the non-charged colored resin particles have the configuration shown in FIG. That is, the surface treatment agent-derived layer 2 is present on the surface of the pigment particles 1. Furthermore, the coating layer 3 exists on the surface of the surface treatment agent-derived layer 2. In the non-chargeable colored resin particles, the inventors consider that the surface treatment agent-derived layer 2 has a role of binding the pigment particles 1 and the coating layer 3 and suppressing peeling of the coating layer 3.
Although FIG. 1 shows a case where there is one pigment particle, the number is not limited to one, and a plurality of pigment particles may be present in a plurality of non-chargeable colored resin particles.
The non-charged colored resin particles are 15 V between ITO electrodes that are parallel flat plates with a distance between the electrodes of 50 μm in a state where the dynamic viscosity is dispersed in a silicone oil having a dynamic viscosity of 100 centistokes or less at a solid concentration of 10% by weight. When a voltage of 2 is applied for 60 seconds, the charge amount is ²⁰ nC / cm ² or less. By indicating this amount of charge, it is possible to suppress display fluctuation due to migration of non-chargeable colored resin particles in the electrophoretic display device.

The average particle diameter of the non-chargeable colored resin particles is preferably 0.1 to 1.0 μm. More preferably, it is 0.2 to 0.8 μm.
When the average particle diameter is less than 0.1 μm, the viscosity of the nonpolar solvent increases during polymerization, and as a result, it may not be possible to produce non-charged colored resin particles having stable average particles. On the other hand, when it exceeds 1.0 μm, dispersion stability in a nonpolar solvent may be deteriorated.
The specific gravity of the non-chargeable colored resin particles is preferably 1.0 to 3.0. More preferably, it is 1.2-2.5.
If the specific gravity is less than 1.0, the pigment concentration becomes low, and color development may be deteriorated. On the other hand, when it exceeds 3.0, the dispersibility to a nonpolar solvent may deteriorate.

(Non-chargeable colored resin particle dispersion)
The non-charged colored resin particle dispersion includes the non-charged colored resin particles and a non-polar solvent in which the non-charged colored resin particles are dispersed.
As the nonpolar solvent, any of those mentioned in the description of the production of the reactive dispersant can be used.
The ratio between the non-chargeable colored resin particles and the non-polar solvent is not particularly limited and can be appropriately set according to the use of the dispersion. For example, in the case of an electrophoretic display device, the content of the non-chargeable colored resin particles in 100 parts by weight of the dispersion is, for example, about 2 to 40 parts by weight, preferably 5 to 30 parts by weight.
The non-chargeable 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 is obtained using a non-charged colored resin particle dispersion.
In the electrophoretic display device, the non-charged colored resin particles develop a base color, and the chargeable colored resin particles develop a desired shape by electrophoresis, thereby displaying an image.
The content of the chargeable colored resin particles is preferably 0.2 to 30 parts by weight, more preferably 0.5 to 20 parts by weight with respect to 100 parts by weight of the non-chargeable colored resin particle dispersion.
The structure of the electrophoretic display device is not particularly limited. For example, a structure in which a display layer made of a non-chargeable colored resin particle dispersion is sandwiched between a pair of substrates having electrodes. By applying a voltage between the electrodes, the chargeable colored resin particles used in combination move to one side of the pair of substrates according to the polarity of the applied voltage. In this apparatus, information is displayed using movement of the chargeable colored resin particles.

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited by these Examples.
A method for measuring the average particle diameter, average molecular weight, resin amount, and charge amount and a color mixing drive evaluation method are described below.
(Average particle size)
The average particle diameter means a Z average particle diameter measured using a method called a dynamic light scattering method.
Specifically, a silicone oil dispersion of colored resin particles is irradiated with laser light, and the intensity of scattered light scattered from the colored resin particles is measured with a time change in units of microseconds. The scattering intensity distribution resulting from the detected colored resin particles is applied to a normal distribution, and the Z average particle diameter is obtained by a cumulant analysis method for calculating the average particle diameter.
This average particle diameter can be easily measured with a commercially available measuring apparatus such as “Zeta Sizer Nano ZS” of Malvern Instruments Ltd. used in this example and comparative examples.
Usually, a commercially available measuring apparatus is equipped with data analysis software, and the Z average particle diameter can be calculated by automatically analyzing the measurement data.

(Average molecular weight)
The average molecular weight means a weight average molecular weight in terms of polystyrene (PS) measured using gel permeation chromatography (GPC).
Specifically, 4 mg of a sample was dissolved in 4 mL of tetrahydrofuran (THF) (permeation time: 6.0 ± 0.5 hr (complete dissolution)), filtered through a non-aqueous 0.45 μm chromatographic disk, and then subjected to the following conditions. Measure using a chromatograph. The average molecular weight of the sample is obtained from a standard polystyrene calibration curve that has been measured and prepared in advance.
Liquid chromatograph: Tosoh Corporation, trade name “Gel Permeation Chromatograph HLC-8320”
Guard column: manufactured by Tosoh Corporation, one product name “TSKguardSuperMP (HZ) -HX” (4.6 mm ID × 2 cm)
Column: Two TOSGEL SuperMultipore HZ-HX (4.6 mm ID × 15 cm) manufactured by Tosoh Corporation
Column temperature: 40 ° C
Mobile phase: Tetrahydrofuran (THF)
Mobile phase flow rate: 0.2 mL / min
Detection: RI
Sample concentration: 0.5 g / mL THF
Injection volume: 20 microliters Measurement time: 25 min
Standard polystyrene for calibration curve: manufactured by Showa Denko KK, trade name “shodex” weight average molecular weight: 5620000, 3120,000, 1250,000, 442000, 131000, 54000, 20000, 7590, 3450, 1320
In the method for preparing a calibration curve, the standard polystyrene for calibration curve is grouped into A and B, dissolved in THF so that the concentration is about 1% by weight (0.1 g / L), and 20 μL is injected. A calibration curve (linear equation) is created from these retention times and used for molecular weight distribution measurement.

(Resin amount of colored resin particles)
The colored resin particles are weighed. The weighed colored resin particles are placed in a platinum cell in a thermogravimetric analyzer (TG / DTA6200 type, manufactured by SII Nano Technology). The resin is thermally decomposed by heating the colored resin particles in the platinum cell at a rate of 10 ° C./min from room temperature to 800 ° C. in a nitrogen atmosphere. The extracted particles are weighed. By substituting the weighing value A of the colored resin particles and the weighing value B of the heat-treated particles into the following equation, the resin amount with respect to 100 parts by weight of the pigment particles is calculated.
Resin ratio (% by weight) = (Weighing value A−Weighing value B) × 100 / Weighing value A
Resin amount (parts by weight) = resin ratio / (100−resin ratio) × 100

(Evaluation method of charge amount)
A colored resin particle having a solid content of 10% by weight is used as a measurement sample.
Two glass plates (width 20 mm, length 100 mm, thickness 0.7 mm: ITO coated glass EAGLE XG manufactured by Matsunami Glass Industrial Co., Ltd.) coated on one side with indium tin oxide (ITO) are prepared. As shown in FIG. 2, a Teflon (registered trademark) film (width 20 mm, length 25 mm) having a thickness of 50 μm is pasted as a spacer on the coated surface of one glass substrate, and the coated surfaces of the two glass plates are on the inside. In this state, a parallel flat plate (a jig) sandwiched between spacers is used. The sample for measurement is infiltrated by capillary action using a syringe into a gap (width 25 mm, length 20 mm, thickness 50 μm) between the coated surfaces of indium tin oxide (ITO) on the two glass plates. Next, both sides of the jig are connected to a measuring device (manufactured by KEITHLEY: KEITHLEY6514), and a measurement value obtained by applying a voltage of +15 V for 60 seconds is divided by the measurement area, and this is charged (nC / cm ^2). ).

(Color mixing drive evaluation method)
2.7 g of a 10% by weight silicone resin dispersion of colored resin particles is weighed into a 20 mL glass bottle, and further 0.3 g of magenta particles having a solid content of 8% by weight and showing negative chargeability are added to prepare a measurement sample. obtain.
Next, two glass plates coated with indium tin oxide (ITO) on one side (width 20 mm, length 100 mm, thickness 0.7 mm: manufactured by Matsunami Glass Industrial Co., Ltd., ITO coated glass EAGLE XG) are prepared. As shown in FIG. 1, a Teflon (registered trademark) film (width 20 mm, length 25 mm) having a thickness of 50 μm is pasted as a spacer on the coated surface of one glass substrate, and the coated surfaces of two glass plates are on the inside. In this state, a parallel flat plate (a jig) sandwiched between spacers is used. The sample for measurement is infiltrated by capillary action using a syringe into a gap (width 25 mm, length 20 mm, thickness 50 μm) between the coated surfaces of indium tin oxide (ITO) on the two glass plates. Next, both sides of the jig are connected to a measuring device (manufactured by KEITHLEY: KEITHLEY6514), and a voltage of +15 V is applied to the upper ITO coated glass.
A state in which magenta particles migrate to the upper ITO-coated glass side and appear magenta when viewed from the upper ITO-coated glass surface is indicated by ◯. On the other hand, the state where the magenta particles and the colored resin particles are aggregated and the magenta color and the colored resin particles appear to be mixed is defined as x.

(Evaluation of polarity of colored resin particles)
5 g of a silicone oil dispersion having a solid content of colored resin particles of 10 wt% and a kinematic viscosity of 2 centistokes is weighed into a 20 mL glass bottle, and the kinematic viscosity is 2 centimeters so that the solid content of the colored resin particles is 5 wt%. An additional 5 g of Stokes silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., KF-96L-2CS, hereinafter referred to as “2cs silicone”) is added to obtain a measurement sample.
Next, two sheets of glass plate coated with indium tin oxide (ITO) on one side (width 8 mm, length 100 mm, thickness 0.7 mm: made by Matsunami Glass Industrial Co., Ltd., ITO coated glass EAGLE XG) with the coated surface on the inside Then, a parallel plate (jig) having a distance of 1 mm between the glass plates with a spacer attached with a copper tape sandwiched between the glass plates is prepared. This jig is immersed in a measurement sample, a voltage of +100 V is applied to the left side (one) of the jig, and the jig is allowed to stand for 10 seconds. After 10 seconds, the jig is lifted from the measurement sample. If particles are attached to the left (one) glass plate, the particle polarity is negative, and if particles are attached to the right (other) glass plate, Judge the particle polarity as positive.

(Evaluation method of sedimentation rate: Evaluation method of dispersion stability of colored resin particles in silicone oil)
The “dispersion stability” as used in the present invention is evaluated using the sedimentation rate of the colored resin particles in the silicone oil measured using a method called a light transmission centrifugal sedimentation method.
Specifically, 2.7 g of a 10 wt% silicone oil dispersion of colored resin particles is weighed into a 20 mL glass bottle, and further 0.3 g of cyan particles having a solid content of 8 wt% and showing negative chargeability are added. To obtain a measurement sample. The sample cell containing the measurement sample is rotated at a high speed with a centrifugal acceleration of 1000 × g, and the sedimentation rate with the cyan particles is calculated by analyzing the separation phenomenon of the particles at the center of the cell based on the elapsed time.
This sedimentation velocity can be easily measured with a measuring device “LUMiSizer 611” commercially available from LUM GmbH (LUM GmbH).
Usually, the measurement apparatus is equipped with data analysis software, and the sedimentation velocity can be calculated by automatically analyzing the measurement data.

Example 1
(Preparation of reactive dispersant 1)
100 parts by weight of silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF-96L-1CS, kinematic viscosity: 1 centistokes), 2.0 parts by weight of lauroyl peroxide (manufactured by NOF Corporation: Parroyl L, LPO, hereinafter) as an initiator , 8.0 parts by weight of styrene (Japan oxirane: styrene monomer, hereinafter St), 91 parts by weight of silicone macromonomer (Silaplane FM-0721, manufactured by Chisso Corporation) and α-methylstyrene dimer (Nofmer MSD, manufactured by NOF Corporation) 1.0 part by weight was added, and solution polymerization was performed for 20 hours while stirring at 70 ° C. in a nitrogen atmosphere to obtain a reactive dispersant 1. The obtained reactive dispersant 1 had a weight average molecular weight of 42800.
Here, lauroyl peroxide was previously dissolved in styrene and added.
In addition, the reaction dispersing agent 1 was attached | subjected to the process of removing the silicone oil used at the time of manufacture before preparation of the following colored resin particles.

(Preparation of colored resin particles)
40 parts by weight of reactive dispersant 1 in a glass bead pot containing 600 g of zirconia beads having a diameter of 1 mm, 100 parts by weight of silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF-96L-1CS, kinematic viscosity: 1 centistokes), After adding 20 parts by weight of titanium oxide (Ishihara Sangyo Co., Ltd .: PT-401M specific surface area of 18.5 m ² / g) as a pigment and dispersing by bead mill for 72 hours at room temperature, silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd.) : KF-96L-1CS, kinematic viscosity: 1 centistokes) was added in an amount of 200 parts by weight to obtain a pigment dispersion. 1.0 part by weight of an aluminum coupling agent (manufactured by Ajinomoto Fine Techno Co., Ltd .: Preneact AL-M) is added to 360 parts by weight of the obtained pigment dispersion, stirred at room temperature for 16 hours, and surface-treated with the coupling agent. A pigment dispersion was obtained.

  600 parts by weight of silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF-96L-1CS, kinematic viscosity: 1 centistokes), 8.0 parts by weight of lauroyl peroxide (manufactured by NOF Corporation: Parroyl L, LPO) as a polymerization initiator, styrene (Japan oxirane: styrene monomer, hereinafter St) 30 parts by weight, divinylbenzene (manufactured by Nippon Steel Chemical Co., Ltd .: hereinafter DVB) 10 parts by weight, and 360 parts by weight of the above pigment dispersion were added, and at 60 ° C. in a nitrogen atmosphere. Dispersion polymerization was performed by ultrasonic irradiation for 7 hours. Here, lauroyl peroxide was previously dissolved in styrene and added.

After the completion of the dispersion polymerization, the colored resin particles were precipitated and separated by centrifugation, and dispersed again in silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF-96L-1CS, kinematic viscosity: 1 centistokes). This operation was repeated 4 times, and the colored resin particles were washed to remove reaction residues such as a polymerization initiator and then dispersed in silicone oil to obtain a colored resin particle silicone oil dispersion having a solid content of 10%.
The average particle size of the colored resin particles was 310 nm, and the proportion of the resin in the colored resin particles was 51.1% by weight. As a result of measuring the charge amount, it was 6.2 nC / cm ² . In addition, the color mixture driving evaluation was ○.

Example 2
The reactive dispersant was prepared in the same manner as in Example 1 (Preparation of reactive dispersant 1).
(Preparation of colored resin particles)
40 parts by weight of reactive dispersant 1 in a glass bead pot containing 600 g of zirconia beads having a diameter of 1 mm, 100 parts by weight of silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF-96L-1CS, kinematic viscosity: 1 centistokes), After adding 20 parts by weight of titanium oxide (Ishihara Sangyo Co., Ltd .: PT-401M specific surface area of 18.5 m ² / g) as a pigment and dispersing by bead mill for 72 hours at room temperature, silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd.) : KF-96L-1CS, kinematic viscosity: 1 centistokes) was added in an amount of 200 parts by weight to obtain a pigment dispersion. To 360 parts by weight of the obtained pigment dispersion, 1.0 part by weight of an aluminum coupling agent (manufactured by Ajinomoto Fine Techno Co., Ltd .: Preneact AL-M) is added, stirred at room temperature for 16 hours, and surface-treated with the coupling agent. A pigment dispersion was obtained.

  Silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF-96L-1CS, kinematic viscosity: 1 centistokes) 590 parts by weight, lauroyl peroxide (manufactured by NOF Corporation: Parroyl L, hereinafter referred to as LPO) 8.0 parts by weight, styrene (Nippon Oxirane) : 30 parts by weight of styrene monomer, hereinafter St), 10 parts by weight of divinylbenzene (manufactured by Nippon Steel Chemical Co., Ltd .: hereinafter DVB), 10 parts by weight of the above reactive dispersant 1, and 360 parts by weight of the above pigment dispersion Then, dispersion polymerization was carried out by irradiating ultrasonic waves at 60 ° C. for 7 hours in a nitrogen atmosphere. Here, lauroyl peroxide was previously dissolved in styrene and added.

After the completion of the dispersion polymerization, the colored resin particles were precipitated and separated by centrifugation, and dispersed again in silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF-96L-1CS, kinematic viscosity: 1 centistokes). This operation was repeated 4 times, and the colored resin particles were washed to remove reaction residues such as a polymerization initiator and then dispersed in silicone oil to obtain a colored resin particle silicone oil dispersion having a solid content of 10%.
The average particle diameter of the colored resin particles was 272 nm, and the proportion of the resin in the colored resin particles was 50.7% by weight. As a result of measuring the amount of charge, it was 19.1 nC / cm ² . In addition, the color mixture driving evaluation was ○.

Example 3
The reactive dispersant was prepared in the same manner as in Example 1 (Preparation of reactive dispersant 1).
(Preparation of colored resin particles)
In the same manner as in Example 1, a pigment dispersion surface-treated with a coupling agent was obtained.
600 parts by weight of silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF-96L-1CS, kinematic viscosity: 1 centistokes), 8.0 parts by weight of lauroyl peroxide (manufactured by NOF Corporation: Parroyl L, LPO) as a polymerization initiator, styrene (Japan oxirane: styrene monomer, hereinafter St) 20 parts by weight, divinylbenzene (manufactured by Nippon Steel Chemical Co., Ltd .: hereinafter DVB) 20 parts by weight, 360 parts by weight of the above-mentioned pigment dispersion were added, and at 60 ° C. in a nitrogen atmosphere. Dispersion polymerization was performed by ultrasonic irradiation for 7 hours. Here, lauroyl peroxide was previously dissolved in styrene and added.

After the completion of the dispersion polymerization, the colored resin particles were precipitated and separated by centrifugation, and dispersed again in silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF-96L-1CS, kinematic viscosity: 1 centistokes). This operation was repeated 4 times, and the colored resin particles were washed to remove reaction residues such as a polymerization initiator and then dispersed in silicone oil to obtain a colored resin particle silicone oil dispersion having a solid content of 10%.
The average particle diameter of the colored resin particles was 286 nm, and the proportion of the resin in the colored resin particles was 53.2% by weight. As a result of measuring the charge amount, it was 8.2 nC / cm ² . In addition, the color mixture driving evaluation was ○.

Example 4
The reactive dispersant was prepared in the same manner as in Example 1 (Preparation of reactive dispersant 1).
(Preparation of colored resin particles)
In the same manner as in Example 1, a pigment dispersion surface-treated with a coupling agent was obtained.
590 parts by weight of silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF-96L-1CS, kinematic viscosity: 1 centistokes), 8.0 parts by weight of lauroyl peroxide (Nippon Yushi Co., Ltd .: Parroyl L, LPO) as a polymerization initiator, styrene (Japan oxirane: styrene monomer, hereinafter St) 30 parts by weight, divinylbenzene (manufactured by Nippon Steel Chemical Co., Ltd .: hereinafter DVB) 20 parts by weight, 360 parts by weight of the above pigment dispersion were added, and at 60 ° C. in a nitrogen atmosphere. Dispersion polymerization was performed by ultrasonic irradiation for 7 hours. Here, lauroyl peroxide was previously dissolved in styrene and added.

After the completion of the dispersion polymerization, the colored resin particles were precipitated and separated by centrifugation, and dispersed again in silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF-96L-1CS, kinematic viscosity: 1 centistokes). This operation was repeated 4 times, and the colored resin particles were washed to remove reaction residues such as a polymerization initiator and then dispersed in silicone oil to obtain a colored resin particle silicone oil dispersion having a solid content of 10%.
The average particle diameter of the colored resin particles was 354 nm, and the proportion of the resin in the colored resin particles was 59.5% by weight. As a result of measuring the charge amount, it was 3.4 nC / cm ² . In addition, the color mixture driving evaluation was ○.

Example 5
The reactive dispersant was prepared in the same manner as in Example 1 (Preparation of reactive dispersant 1).
(Preparation of colored resin particles)
30 parts by weight of reactive dispersant 1 in a glass bead pot containing 600 g of zirconia beads having a diameter of 1 mm, 110 parts by weight of silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF-96L-1CS, kinematic viscosity: 1 centistokes), After adding 20 parts by weight of titanium oxide (Ishihara Sangyo Co., Ltd .: PT-401M specific surface area of 18.5 m ² / g) as a pigment and dispersing by bead mill for 72 hours at room temperature, silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd.) : KF-96L-1CS, kinematic viscosity: 1 centistokes) 200 parts by weight was added to obtain a pigment dispersion. 1.0 part by weight of an aluminum coupling agent (manufactured by Ajinomoto Fine Techno Co., Ltd .: Preneact AL-M) is added to 360 parts by weight of the obtained pigment dispersion, stirred at room temperature for 16 hours, and surface-treated with the coupling agent. A pigment dispersion was obtained.

600 parts by weight of silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF-96L-1CS, kinematic viscosity: 1 centistokes), 8.0 parts by weight of lauroyl peroxide (manufactured by NOF Corporation: Parroyl L, LPO) as a polymerization initiator, styrene (Nippon oxirane: styrene monomer, hereinafter St) 30 parts by weight, divinylbenzene (manufactured by Nippon Steel Chemical Co., Ltd .: hereinafter DVB) 10 parts by weight, 360 parts by weight of the above pigment dispersion were added, and at 60 ° C. in a nitrogen atmosphere. Dispersion polymerization was performed by ultrasonic irradiation for 7 hours. Here, lauroyl peroxide was previously dissolved in styrene and added.
After the completion of the dispersion polymerization, the colored resin particles were precipitated and separated by centrifugation, and dispersed again in silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF-96L-1CS, kinematic viscosity: 1 centistokes). This operation was repeated 4 times, and the colored resin particles were washed to remove reaction residues such as a polymerization initiator and then dispersed in silicone oil to obtain a colored resin particle silicone oil dispersion having a solid content of 10%.
The average particle diameter of the colored resin particles was 254 nm, and the proportion of the resin in the colored resin particles was 49.4% by weight. As a result of measuring the charge amount, it was 11.4 nC / cm ² . In addition, the color mixture driving evaluation was ○.

Example 6
The reactive dispersant was prepared in the same manner as in Example 1 (Preparation of reactive dispersant 1).
(Preparation of colored resin particles)
40 parts by weight of reactive dispersant 1 in a glass bead pot containing 600 g of zirconia beads having a diameter of 1 mm, 100 parts by weight of silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF-96L-1CS, kinematic viscosity: 1 centistokes), After adding 20 parts by weight of titanium oxide (manufactured by Teika: MT-600B specific surface area 32.1 m ² / g) as a colorant and dispersing with a bead mill for 72 hours at room temperature, silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd.) : KF-96L-1CS, kinematic viscosity: 1 centistokes) 200 parts by weight was added to obtain a pigment dispersion. 360 parts by weight of the obtained pigment dispersion and 1.2 parts by weight of an aluminum coupling agent (manufactured by Ajinomoto Fine Techno Co., Ltd .: Preneact AL-M) are added, stirred at room temperature for 16 hours, and surface-treated with the coupling agent. A pigment dispersion was obtained.

  600 parts by weight of silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF-96L-1CS, kinematic viscosity: 1 centistokes), 8.0 parts by weight of lauroyl peroxide (manufactured by NOF Corporation: Parroyl L, LPO) as a polymerization initiator, styrene (Nippon oxirane: styrene monomer, hereinafter St) 30 parts by weight, divinylbenzene (manufactured by Nippon Steel Chemical Co., Ltd .: hereinafter DVB) 10 parts by weight, 360 parts by weight of the above pigment dispersion were added, and at 60 ° C. in a nitrogen atmosphere. Dispersion polymerization was performed by ultrasonic irradiation for 7 hours. Here, lauroyl peroxide was previously dissolved in styrene and added.

After the completion of the dispersion polymerization, the colored resin particles were precipitated and separated by centrifugation, and dispersed again in silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF-96L-1CS, kinematic viscosity: 1 centistokes). This operation was repeated 4 times, and the colored resin particles were washed to remove reaction residues such as a polymerization initiator and then dispersed in silicone oil to obtain a colored resin particle silicone oil dispersion having a solid content of 10%.
The average particle diameter of the colored resin particles was 237 nm, and the proportion of the resin in the colored resin particles was 50.9% by weight. As a result of measuring the charge amount, it was 18.2 nC / cm ² . In addition, the color mixture driving evaluation was ○.

Example 7
The reactive dispersant was prepared in the same manner as in Example 1 (Preparation of reactive dispersant 1).
(Preparation of colored resin particles)
40 parts by weight of reactive dispersant 1 in a glass bead pot containing 600 g of zirconia beads having a diameter of 1 mm, 100 parts by weight of silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF-96L-1CS, kinematic viscosity: 1 centistokes), After adding 20 parts by weight of titanium oxide (Ishihara Sangyo Co., Ltd .: PT-401M specific surface area of 18.5 m ² / g) as a pigment and dispersing by bead mill for 72 hours at room temperature, silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd.) : KF-96L-1CS, kinematic viscosity: 1 centistokes) 200 parts by weight was added to obtain a pigment dispersion. 1.0 part by weight of a titanate coupling agent (manufactured by Ajinomoto Fine Techno Co., Ltd .: Preneact KR-TTS) was added to 360 parts by weight of the obtained pigment dispersion, stirred at room temperature for 16 hours, and surface-treated with the coupling agent. A pigment dispersion was obtained.

  600 parts by weight of silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF-96L-1CS, kinematic viscosity: 1 centistokes), 8.0 parts by weight of lauroyl peroxide (manufactured by NOF Corporation: Parroyl L, LPO) as a polymerization initiator, styrene (Nippon oxirane: styrene monomer, hereinafter St) 30 parts by weight, divinylbenzene (manufactured by Nippon Steel Chemical Co., Ltd .: hereinafter DVB) 10 parts by weight, 360 parts by weight of the above pigment dispersion were added, and at 60 ° C. in a nitrogen atmosphere. Dispersion polymerization was performed by ultrasonic irradiation for 7 hours. Here, lauroyl peroxide was previously dissolved in styrene and added.

After the completion of the dispersion polymerization, the colored resin particles were precipitated and separated by centrifugation, and dispersed again in silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF-96L-1CS, kinematic viscosity: 1 centistokes). This operation was repeated 4 times, and the colored resin particles were washed to remove reaction residues such as a polymerization initiator and then dispersed in silicone oil to obtain a colored resin particle silicone oil dispersion having a solid content of 10%.
The average particle diameter of the colored resin particles was 342 nm, and the resin ratio in the colored resin particles was 53.9% by weight. As a result of measuring the charge amount, it was 15.3 nC / cm ² . In addition, the color mixture driving evaluation was ○.

Example 8
The reactive dispersant was prepared in the same manner as in Example 1 (Preparation of reactive dispersant 1).
(Preparation of colored resin particles)
In the same manner as in Example 1, a pigment dispersion surface-treated with a coupling agent was obtained.
Silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF-96L-1CS, kinematic viscosity: 1 centistokes) 600 parts by weight in a 200 ml sample tube, lauroyl peroxide (manufactured by NOF Corporation: Parroyl L, LPO) 8.0 as a polymerization initiator Parts by weight, 30 parts by weight of p-methylstyrene (Wako Pure Chemical Industries: p-methylstyrene), 10 parts by weight of divinylbenzene (manufactured by Nippon Steel Chemical Co., Ltd .: DVB), and 360 parts by weight of the above pigment dispersion are added. Then, dispersion polymerization was performed by ultrasonic irradiation at 60 ° C. for 7 hours in a nitrogen atmosphere. Here, lauroyl peroxide was previously dissolved in styrene and added.

After the completion of the dispersion polymerization, the colored resin particles were precipitated and separated by centrifugation, and dispersed again in silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF-96L-1CS, kinematic viscosity: 1 centistokes). This operation was repeated 4 times, and the colored resin particles were washed to remove reaction residues such as a polymerization initiator and then dispersed in silicone oil to obtain a colored resin particle silicone oil dispersion having a solid content of 10%.
The average particle diameter of the colored resin particles was 335 nm, and the resin ratio in the colored resin particles was 52.9% by weight. As a result of measuring the charge amount, it was 5.2 nC / cm ² . In addition, the color mixture driving evaluation was ○.

Comparative Example 1
In Example 1 (Preparation of colored resin particles), styrene (manufactured by Nippon Oxirane Co., Ltd .: styrene monomer), methyl methacrylate (manufactured by Mitsubishi Rayon Co., Ltd .: MMA) and divinylbenzene (manufactured by Nippon Steel Chemical Co., Ltd .: hereinafter DVB) were used. Colored resin particles were prepared in the same manner as in Example 1 except that the ethylene glycol dimethacrylate (manufactured by Kyoeisha Chemical Co., Ltd.) was used.
The average particle diameter of the obtained colored resin particles was 293 nm, and the proportion of the resin in the colored resin particles was 54.3% by weight. The charge amount of the colored resin particles was 19.7 nC / cm ² , and the color mixture migration evaluation was x.

Comparative Example 2
In Example 1 (Preparation of Reactive Dispersant 1), 8.0 parts by weight of styrene (manufactured by Nippon Oxirane Co., Ltd .: styrene monomer) and 6.0 parts by weight of styrene (manufactured by Nihon Oxirane Co., Ltd .: styrene monomer) and diethylaminoethyl methacrylate Colored resin particles were prepared in the same manner as in Example 1 except that the reactive dispersant 2 obtained by changing to 2.0 parts by weight (manufactured by Kyoeisha Chemical Co., Ltd .: Light Ester DE) was used. The weight average molecular weight of the obtained reactive dispersant was 45200.
The average particle diameter of the obtained colored resin particles was 283 nm, and the proportion of the resin in the colored resin particles was 49.3% by weight. The charge amount of the colored resin particles was 27.4 nC / cm ² , and the color mixture migration evaluation was x.

Example 9
The reactive dispersant was prepared in the same manner as in Example 1 (Preparation of reactive dispersant 1).
(Preparation of colored resin particles)
40 parts by weight of reactive dispersant 1 in a glass bead pot containing 600 g of zirconia beads having a diameter of 1 mm, 100 parts by weight of silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF-96L-1CS, kinematic viscosity: 1 centistokes) Then, 20 parts by weight of titanium oxide (Ishihara Sangyo Co., Ltd .: PT-401M, specific surface area of 18.5 m ² / g) as a pigment was added and dispersed by a bead mill at room temperature for 72 hours, followed by silicone oil (Shin-Etsu Chemical Co., Ltd.). 200 parts by weight of KF-96L-1CS, kinematic viscosity: 1 centistokes) was added to obtain a pigment dispersion. To 360 parts by weight of the obtained pigment dispersion, 1.0 part by weight of an aluminum coupling agent (manufactured by Ajinomoto Fine Techno Co., Ltd .: Preneact AL-M) is added, stirred at room temperature for 16 hours, and surface-treated with the coupling agent. A pigment dispersion was obtained.

  590 parts by weight of silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF-96L-1CS, kinematic viscosity: 1 centistokes), 8.0 parts by weight of lauroyl peroxide (manufactured by NOF Corporation: Parroyl L, hereinafter referred to as LPO), divinylbenzene (new) Nippon Steel Chemical Co., Ltd .: DVB) 40 parts by weight and the above pigment dispersion were added by 360 parts by weight, and dispersion polymerization was carried out by irradiating ultrasonically at 60 ° C. for 7 hours in a nitrogen atmosphere. Here, lauroyl peroxide was previously dissolved in divinylbenzene and added.

After the completion of the dispersion polymerization, the colored resin particles were precipitated and separated by centrifugation, and dispersed again in silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF-96L-1CS, kinematic viscosity: 1 centistokes). This operation was repeated 4 times, and the colored resin particles were washed to remove reaction residues such as a polymerization initiator and then dispersed in silicone oil to obtain a colored resin particle silicone oil dispersion having a solid content of 10%.
The average particle diameter of the colored resin particles was 520 nm, and the resin ratio in the colored resin particles was 57.3% by weight. As a result of measuring the amount of charge, it was 2.6 nC / cm ² . The color mixture drive evaluation was ○. The sedimentation rate with cyan particles exhibiting negative chargeability was 4.57 μm / sec.

Example 10
The reactive dispersant was prepared in the same manner as in Example 1 (Preparation of reactive dispersant 1).
(Preparation of colored resin particles)
40 parts by weight of reactive dispersant 1 in a glass bead pot containing 600 g of zirconia beads having a diameter of 1 mm, 100 parts by weight of silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF-96L-1CS, kinematic viscosity: 1 centistokes) Then, 20 parts by weight of titanium oxide (Ishihara Sangyo Co., Ltd .: PT-401M, specific surface area of 18.5 m ² / g) as a pigment was added and dispersed by a bead mill at room temperature for 72 hours, followed by silicone oil (Shin-Etsu Chemical Co., Ltd.). 200 parts by weight of KF-96L-1CS, kinematic viscosity: 1 centistokes) was added to obtain a pigment dispersion. To 360 parts by weight of the obtained pigment dispersion, 1.0 part by weight of an aluminum coupling agent (manufactured by Ajinomoto Fine Techno Co., Ltd .: Preneact AL-M) is added, stirred at room temperature for 16 hours, and surface-treated with the coupling agent. A pigment dispersion was obtained.

  590 parts by weight of silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF-96L-1CS, kinematic viscosity: 1 centistokes), 8.0 parts by weight of lauroyl peroxide (manufactured by NOF Corporation: Parroyl L, hereinafter referred to as LPO), divinylbenzene (new) Nippon Steel Chemical Co., Ltd .: DVB) 40 parts by weight, silicone macromonomer (Silaplane FM-0721, manufactured by Chisso Corporation) 10 parts by weight, and 360 parts by weight of the above-mentioned pigment dispersion were added, and a nitrogen atmosphere at 60 ° C. Dispersion polymerization was performed by ultrasonic irradiation for 7 hours. Here, lauroyl peroxide was previously dissolved in divinylbenzene and added.

After the completion of the dispersion polymerization, the colored resin particles were precipitated and separated by centrifugation, and dispersed again in silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF-96L-1CS, kinematic viscosity: 1 centistokes). This operation was repeated 4 times, and the colored resin particles were washed to remove reaction residues such as a polymerization initiator and then dispersed in silicone oil to obtain a colored resin particle silicone oil dispersion having a solid content of 10%.
The average particle diameter of the colored resin particles was 516 nm, and the resin ratio in the colored resin particles was 57.8% by weight. As a result of measuring the charge amount, it was 1.7 nC / cm ² . The color mixture drive evaluation was ○. Further, the sedimentation rate with cyan particles exhibiting negative chargeability was 4.00 μm / sec.

Example 11
The reactive dispersant was prepared in the same manner as in Example 1 (Preparation of reactive dispersant 1).
(Preparation of colored resin particles)
40 parts by weight of reactive dispersant 1 in a glass bead pot containing 600 g of zirconia beads having a diameter of 1 mm, 100 parts by weight of silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF-96L-1CS, kinematic viscosity: 1 centistokes) Then, 20 parts by weight of titanium oxide (Ishihara Sangyo Co., Ltd .: PT-401M, specific surface area of 18.5 m ² / g) as a pigment was added and dispersed by a bead mill at room temperature for 72 hours, followed by silicone oil (Shin-Etsu Chemical Co., Ltd.). 200 parts by weight of KF-96L-1CS, kinematic viscosity: 1 centistokes) was added to obtain a pigment dispersion. To 360 parts by weight of the obtained pigment dispersion, 1.0 part by weight of an aluminum coupling agent (manufactured by Ajinomoto Fine Techno Co., Ltd .: Preneact AL-M) is added, stirred at room temperature for 16 hours, and surface-treated with the coupling agent. A pigment dispersion was obtained.

  590 parts by weight of silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF-96L-1CS, kinematic viscosity: 1 centistokes), 8.0 parts by weight of lauroyl peroxide (manufactured by NOF Corporation: Parroyl L, hereinafter referred to as LPO), divinylbenzene (new) Nippon Steel Chemical Co., Ltd .: DVB) 40 parts by weight, silicone macromonomer (Silaplane FM-0721, manufactured by Chisso Corporation) 20 parts by weight, and 360 parts by weight of the above-mentioned pigment dispersion were added, and a nitrogen atmosphere at 60 ° C. Dispersion polymerization was performed by ultrasonic irradiation for 7 hours. Here, lauroyl peroxide was previously dissolved in divinylbenzene and added.

After the completion of the dispersion polymerization, the colored resin particles were precipitated and separated by centrifugation, and dispersed again in silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF-96L-1CS, kinematic viscosity: 1 centistokes). This operation was repeated 4 times, and the colored resin particles were washed to remove reaction residues such as a polymerization initiator and then dispersed in silicone oil to obtain a colored resin particle silicone oil dispersion having a solid content of 10%.
The average particle diameter of the colored resin particles was 423 nm, and the resin ratio in the colored resin particles was 57.8% by weight. As a result of measuring the charge amount, it was 3.1 nC / cm ² . The color mixture drive evaluation was ○. The sedimentation rate with cyan particles exhibiting negative chargeability was 2.93 μm / sec.

Example 12
The reactive dispersant was prepared in the same manner as in Example 1 (Preparation of reactive dispersant 1).
(Preparation of colored resin particles)
40 parts by weight of reactive dispersant 1 in a glass bead pot containing 600 g of zirconia beads having a diameter of 1 mm, 100 parts by weight of silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF-96L-1CS, kinematic viscosity: 1 centistokes) Then, 20 parts by weight of titanium oxide (Ishihara Sangyo Co., Ltd .: PT-401M, specific surface area of 18.5 m ² / g) as a pigment was added and dispersed by a bead mill at room temperature for 72 hours, followed by silicone oil (Shin-Etsu Chemical Co., Ltd.). 200 parts by weight of KF-96L-1CS, kinematic viscosity: 1 centistokes) was added to obtain a pigment dispersion. To 360 parts by weight of the obtained pigment dispersion, 1.0 part by weight of an aluminum coupling agent (manufactured by Ajinomoto Fine Techno Co., Ltd .: Preneact AL-M) is added, stirred at room temperature for 16 hours, and surface-treated with the coupling agent. A pigment dispersion was obtained.

  590 parts by weight of silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF-96L-1CS, kinematic viscosity: 1 centistokes), 8.0 parts by weight of lauroyl peroxide (manufactured by NOF Corporation: Parroyl L, hereinafter referred to as LPO), divinylbenzene (new) Nippon Steel Chemical Co., Ltd .: DVB) 40 parts by weight, silicone macromonomer (Silaplane FM-0721, manufactured by Chisso Corporation) 40 parts by weight, 360 parts by weight of the above pigment dispersion were added, and a nitrogen atmosphere at 60 ° C. Dispersion polymerization was performed by ultrasonic irradiation for 7 hours. Here, lauroyl peroxide was previously dissolved in divinylbenzene and added.

After the completion of the dispersion polymerization, the colored resin particles were precipitated and separated by centrifugation, and dispersed again in silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF-96L-1CS, kinematic viscosity: 1 centistokes). This operation was repeated 4 times, and the colored resin particles were washed to remove reaction residues such as a polymerization initiator and then dispersed in silicone oil to obtain a colored resin particle silicone oil dispersion having a solid content of 10%.
The average particle diameter of the colored resin particles was 331 nm, and the proportion of the resin in the colored resin particles was 55.9% by weight. As a result of measuring the charge amount, it was 5.9 nC / cm ² . The color mixture drive evaluation was ○. The sedimentation rate with cyan particles exhibiting negative chargeability was 1.37 μm / sec.
The raw material types, raw material usage amounts and results of Examples 1 to 8 and Comparative Examples 1 and 2 are summarized in Table 1. In Table 1, the amount of raw material used is parts by weight.

  The raw material types, raw material usage amounts and results of Examples 9 to 12 are summarized in Table 2. In Table 2, the amount of raw material used is parts by weight.

From the result of Table 1, the colored resin obtained by using the polymer of the mixture of the reactive dispersing agent which does not have a specific kind polar group in a coating layer, a polymerization initiator, and an aromatic monomer. It can be seen that the particles have a low charge amount, do not mix with the charged colored resin particles, and have dispersion stability.
Moreover, the following can be understood from the results of Table 2.
From Examples 9, 10, 11 and 12, by obtaining a colored resin particle by adding and polymerizing a silicone macromonomer separately from the silicone macromonomer used in the production of the reactive dispersant, the sedimentation rate is increased. From the fact that it is slow, it can be seen that the dispersion stability is higher. In particular, it can be seen that by using 20 parts by weight or more of the silicone macromonomer during the production of the colored resin particles, the sedimentation rate can be made slower.

1 pigment particles, 2 surface treatment agent-derived layer, 3 coating layer

Claims (8)

In the presence of a nonpolar solvent, a silicone macromonomer, a vinyl monomer having no polar group, and an α-methylstyrene dimer in the presence of a nonpolar solvent are applied to the surface of the pigment particles made of a metal oxide treated with a surface treatment agent. Non-chargeable colored resin particles coated with a polymer of a reactive dispersant obtained by polymerization and an aromatic monomer having no polar group,
In a state where the dynamic viscosity is dispersed in a silicone oil of 100 centistokes or less at a solid content concentration of 10% by weight, it is sealed between ITO electrodes that are parallel plates with an interelectrode distance of 50 μm, and a voltage of 15 V is applied to 60 A non-chargeable colored resin particle which exhibits a charge amount of ²⁰ nC / cm ² or less when applied for ² seconds.   The non-charged colored resin particles are the reactive dispersant, the aromatic monomer, and a silicone macromonomer that is the same as or different from the silicone macromonomer used in the production by polymerization of the reactive dispersant. The non-chargeable colored resin particle according to claim 1, wherein the pigment particle surface is coated with a polymer. The silicone macromonomer is represented by the following general formula (1)
(R ₁ is a hydrogen atom or a methyl group, R ₂ is an alkylene group having 2 to 4 carbon atoms, R ₃ is the same or different alkyl group or phenyl group having 1 to 4 carbon atoms, and n is an integer). The non-chargeable colored resin particles according to claim 1 or 2, wherein   The non-chargeable colored resin particle according to claim 1, wherein the surface treatment agent is a coupling agent. The surface treatment agent is represented by the following general formula (2), (3) or (4)
(Wherein R1 is an alkyl group having 8 to 20 carbon atoms, R2 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R3 is an alkoxy group having 1 to 6 carbon atoms). Item 5. The non-chargeable colored resin particle according to any one of Items 1 to 4.   The non-chargeable colored resin particles according to any one of claims 1 to 5, wherein an average particle diameter is in a range of 50 to 1000 nm.   A non-charged colored resin particle dispersion obtained by dispersing the non-charged colored resin particles according to any one of claims 1 to 6 in a non-polar solvent.   An electrophoretic display device obtained by using the non-charged colored resin particles according to any one of claims 1 to 6 or the non-charged colored resin particle dispersion according to claim 7.