JP2018146858A - Electrophoretic particle, production method of electrophoretic particle, electrophoretic dispersion liquid, electrophoretic sheet, electrophoretic device and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide electrophoretic particles having uniform dispersibility in an electrophoretic dispersion liquid and having a charge amount set in an appropriate range, a production method of electrophoretic particles by which the above electrophoretic particles can be produced, and an electrophoretic dispersion liquid, an electrophoretic sheet, an electrophoretic device and an electronic apparatus of high reliability using the above electrophoretic particles.SOLUTION: An electrophoretic particle 1 of the present invention comprises a base particle (particle) 2 having a first functional group on the surface thereof, and a first compound 39 and a second compound 37 coupled to the base particle 2. The first compound 39 is a polymer having a dispersing moiety 32 and a coupling moiety 31 and is connected at the coupling moiety 31 to the base particle 2. The second compound 37 is a compound having a molecular weight smaller than that of the first compound 39 and having a polar group or a non-polar group and an isocyanate group, in which the isocyanate group is connected to the base particle 2 by the reaction with the first functional group.SELECTED DRAWING: Figure 2

Description

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

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

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

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

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

  Here, as the electrophoretic particles 501, those having a coating layer 503 in which a polymer 533 is connected to the base particle 502 are generally used (see FIG. 11), and such a coating layer 503 is used. With the configuration including (polymer 533), the electrophoretic particles 501 can be dispersed and charged in the electrophoretic dispersion.

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

  That is, after preparing the base particle 502 and bonding the silane coupling agent 531 having a polymerization initiating group to the surface of the base particle 502, the monomer is polymerized by living radical polymerization using the polymerization initiating group as a starting point. By forming the polymerized portion 532 and providing the polymer (polymer) 533, electrophoretic particles 501 are produced by imparting properties such as dispersibility (see, for example, Patent Document 1).

  By the way, in the electrophoretic particle 501 having such a configuration, as to whether the electrophoretic particle 501 has a positive charging property or a negative charging property, the base material particle 502 has its own charging property. The electrification property of the electrophoretic particles 501 can be made desired by appropriately selecting the type of the base particle 502.

  However, in the electrophoretic display device, for example, in order to set the electrophoresis speed of the electrophoretic particles 501 to an appropriate speed, the charge amount of the electrophoretic particles 501 needs to be controlled. It is difficult to control the charge amount of the electrophoretic particles 501 within an appropriate range only by providing the molecules 533.

JP 2013-156281 A

  One of the objects of the present invention is an electrophoretic particle having a uniform dispersibility in an electrophoretic dispersion and having a charge amount set in an appropriate range, and an electrophoretic particle capable of producing the electrophoretic particle. It is an object of the present invention to provide a manufacturing method, a highly reliable electrophoretic dispersion, an electrophoretic sheet, an electrophoretic device, and an electronic apparatus using such electrophoretic particles.

Such an object is achieved by the present invention described below.
The electrophoretic particle of the present invention includes a particle having a first functional group having reactivity with an isocyanate group on the surface;
A first compound and a second compound bonded to the particles;
The first compound has reactivity with the first functional group and the dispersion part derived from the first monomer having a site contributing to dispersibility in a dispersion medium, and is different from the isocyanate group. A block copolymer having a bonding portion derived from a second monomer having a second functional group, wherein the first functional group and the second functional group react with each other in the bonding portion, so that the particles Connected to
The second compound has a molecular weight smaller than that of the first compound, has a polar group or a nonpolar group, and the isocyanate group, and the isocyanate group reacts with the first functional group. It is connected with the said particle | grain by this.

  Thereby, it is possible to obtain an electrophoretic particle having a uniform dispersibility in the electrophoretic dispersion liquid and having a charge amount set in an appropriate range.

  In the electrophoretic particle of the present invention, the second compound is preferably a silane coupling agent having the nonpolar group and the isocyanate group.

  The silane coupling agent having an isocyanate group can be prepared relatively easily and is firmly connected to the surface of the particles. Furthermore, by having a non-polar group, the charge amount of the electrophoretic particles can be easily adjusted, so that it is preferably used as the second compound.

  In the electrophoretic particle of the present invention, it is preferable that the first functional group is a hydroxyl group and the second functional group is an alkoxysilyl group.

  Particles having a hydroxyl group can be prepared relatively easily. Furthermore, the hydroxyl group and the isocyanate group exhibit particularly excellent reactivity, and a chemical bond can be reliably formed between them. Therefore, it is preferably used because the second compound can be linked to the surface of the particles with a particularly high coverage.

  Moreover, the 1st compound provided with an alkoxy silyl group can be prepared comparatively easily. Furthermore, since the hydroxyl group and the alkoxysilyl group exhibit excellent reactivity and can form a chemical bond between them, the first compound can be connected to the surface of the mother particle with a high coverage. Are preferably used.

In the electrophoretic particles of the present invention, the nonpolar group is preferably a hydrocarbon group.
Since these have excellent non-polarity, aggregation of the electrophoretic particles can be suppressed or prevented more accurately.

  In the electrophoretic particles of the present invention, the molecular weight of the second compound is preferably 100 or more and 1,000 or less.

  Thereby, the steric hindrance of the second compound is reduced, and the second compound can be reliably inserted in the region between the first compounds connected to the particles. As a result, the dispersibility of the electrophoretic particles in the electrophoretic dispersion liquid can be further improved.

  In the electrophoretic particles of the present invention, A / B is preferably 10 or more and 1,000 or less, where A is the weight average molecular weight of the dispersion and B is the molecular weight of the second compound.

  Thereby, the steric hindrance of the second compound is reduced, and the second compound can be more reliably inserted in a region between the first compounds connected to the particles. As a result, the dispersibility of the electrophoretic particles in the electrophoretic dispersion liquid can be further improved.

The method for producing electrophoretic particles of the present invention is a production method for producing the electrophoretic particles of the present invention,
Reacting the first functional group with the second functional group to link the first compound to the particles at the binding portion;
A step of coupling the second compound to the particles by reacting the first functional group with the isocyanate group.

  As a result, it is possible to produce electrophoretic particles having uniform dispersibility in the electrophoretic dispersion and having the charge amount set in an appropriate range.

  The electrophoretic dispersion liquid of the present invention contains the electrophoretic particles of the present invention and a dispersion medium.

  Thereby, it can be set as the electrophoresis dispersion liquid provided with the electrophoretic particle which is provided with the uniform dispersibility and the charge amount was set to the appropriate range.

The electrophoretic sheet of the present invention comprises a substrate,
A structure provided on the substrate and containing the electrophoretic dispersion of the present invention, and the electrophoretic dispersion.
Thereby, an electrophoretic sheet having high performance and reliability can be obtained.

The electrophoretic device of the present invention includes the electrophoretic sheet of the present invention.
Thereby, an electrophoretic device with high performance and reliability can be obtained.

An electronic apparatus according to the present invention includes the electrophoresis apparatus according to the present invention.
Thereby, an electronic device with high performance and reliability can be obtained.

It is a longitudinal cross-sectional view which shows 1st Embodiment of the electrophoretic particle of this invention. It is a schematic diagram of the 1st compound and 2nd compound which 1st Embodiment of the electrophoretic particle of this invention has. It is a flowchart which shows the manufacturing method of 1st Embodiment of the electrophoretic particle of this invention in order of a process. It is a schematic diagram of the 1st compound and 2nd compound which 2nd Embodiment of the electrophoretic particle of this invention has. It is a figure which shows typically the longitudinal cross-section of embodiment of an electrophoretic display apparatus. FIG. 6 is a schematic diagram illustrating an operation principle of the electrophoretic display device illustrated in FIG. 5. FIG. 6 is a schematic diagram illustrating an operation principle of the electrophoretic display device illustrated in FIG. 5. It is a perspective view which shows embodiment at the time of applying the electronic device of this invention to electronic paper. It is sectional drawing which shows embodiment at the time of applying the electronic device of this invention to a display. It is a top view which shows embodiment at the time of applying the electronic device of this invention to a display. It is a figure which shows typically the longitudinal cross-section of the structure in the conventional electrophoretic particle.

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

<Electrophoretic particles>
<< First Embodiment >>
First, a first embodiment of the electrophoretic particles of the present invention will be described.

  FIG. 1 is a longitudinal sectional view showing a first embodiment of the electrophoretic particle of the present invention, and FIG. 2 is a schematic diagram of the first compound and the second compound of the first embodiment of the electrophoretic particle of the present invention. It is.

  The electrophoretic particle 1 has a mother particle (particle) 2 and a coating layer 3 provided on the surface of the mother particle 2.

  For the mother particles 2, for example, at least one of pigment particles, resin particles, or composite particles thereof is preferably used. These particles are easy to manufacture.

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

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

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

  In addition, the color of the electrophoretic particles 1 can be set to a desired color by appropriately selecting the types of pigment particles, resin particles, and composite particles used as the mother particles 2.

  Furthermore, by these selections, the positive chargeability or negative chargeability of the mother particle 2 and the charge amount can be set as unique to the mother particle 2.

  The mother particle 2 (particles) needs to have (exposed) a first functional group having a binding property (reactivity) with an isocyanate group included in the second compound 37 described later. is there. However, depending on the types of pigment particles, resin particles, and composite particles, the first functional group may not be included. In this case, in advance, acid treatment, base treatment, UV treatment, ozone treatment, plasma treatment, etc. The first functional group is introduced to the surface of the mother particle 2 by performing a functional group introduction treatment.

  Further, the first functional group capable of reacting with the isocyanate group included in the second compound 37 is not particularly limited, and examples thereof include a hydroxyl group and an amino group, and one or two of these are combined. Among them, a hydroxyl group is preferable. The second compound 37 having an isocyanate group and the mother particle 2 having a hydroxyl group can be prepared relatively easily. Furthermore, since the hydroxyl group and the isocyanate group exhibit particularly excellent reactivity and a chemical bond can be reliably formed between them, the second compound 37 is applied to the surface of the mother particle 2 with a particularly high coverage. It is preferably used because it can be connected.

  Further, the first compound 39 described later needs to have a second functional group that is reactive with the first functional group of the mother particle 2 and is different from the isocyanate group. Examples of the functional group include an alkoxysilyl group, an epoxy group, a glycidyl group, and an oxetane group, and one or more of these can be used in combination. Is preferred. The first compound 39 having an alkoxysilyl group can be prepared relatively easily. Furthermore, since the hydroxyl group and the alkoxysilyl group exhibit excellent reactivity and can form a chemical bond between them, the first compound 39 is connected to the surface of the mother particle 2 with a high coverage. Can be preferably used.

Therefore, in response to the isocyanate groups in which the second compound 37 is provided, in the following, a first functional group is a hydroxyl group provided on the surface of the mother particle 2, further a second functional group comprising a monomer M ₂ alkoxy The case of a silyl group will be described as an example.

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

  The coating layer 3 has a configuration including a plurality of first compounds 39 and a second compound 37 having a molecular weight smaller than that of the first compound 39 (see FIG. 2).

  In addition, although the 2nd compound 37 has a polar group or a nonpolar group, and an isocyanate group, below, this 2nd compound 37 is a silane type cup which has a nonpolar group and an isocyanate group. The case where it is a ring agent will be described. Silane coupling agents having an isocyanate group can be prepared (obtained) relatively easily, and can be firmly (stable) linked to the surface of the mother particle 2 and further have a nonpolar group Therefore, since the charge amount of the electrophoretic particles 1 can be easily adjusted, it is preferably used as the second compound 37.

  First, of the first compound 39 and the second compound 37, the first compound 39 will be described.

The first compound 39 includes a dispersion portion 32 derived from a _first monomer M ₁ having a site (group) contributing to dispersibility in a dispersion medium (hereinafter also simply referred to as “monomer M ₁ ”), It is a block copolymer having a bonding portion 31 derived from a _second monomer M ₂ having a second functional group having reactivity with one functional group (hereinafter also simply referred to as “monomer M ₂ ”). And in the coupling | bond part 31, it has connected with the mother particle 2 because the 1st functional group and the 2nd functional group react.

By making the first compound 39 to have such a configuration, dispersibility is imparted to the dispersion portion 32 composed of units derived from the monomer M ₁ (hereinafter also referred to as dispersion units), and the monomer M ₂ It becomes what was connected with respect to the mother particle 2 by the coupling | bond part 31 comprised with the unit (henceforth a coupling | bonding unit) derived. Therefore, the electrophoretic particle 1 including the first compound 39 having such a configuration can exhibit a uniform dispersibility in the electrophoretic dispersion liquid.

Incidentally, the first compound 39, in which the distribution unit 32 first monomer M ₁ is polymerized, and the coupling portion 31 where the second monomer M ₂ are polymerized and ligated. In the first compound 39 having such a structure, distribution unit 32 is formed by the monomers M ₁ is polymerized, a polymerization unit comprising a plurality of distributed units derived from the monomer M _1, further coupling 31 monomer M ₂ There are formed by polymerizing a polymerization unit including a plurality of coupling units derived from the monomer M _2. In the bonding part 31 of the first compound 39, the hydroxyl group as the first functional group and the alkoxysilyl group as the second functional group react to cause the mother particle 2 and the first compound 39 to chemically react. Are connected.

  Hereinafter, the dispersion part 32 and the coupling part 31 constituting the first compound 39 will be described.

  The dispersion part 32 is provided on the surface of the mother particle 2 in the coating layer 3 in order to impart dispersibility to the electrophoretic particles 1 in an electrophoretic dispersion described later.

The dispersion portion 32 is a polymerization portion formed by polymerizing a plurality of monomers M ₁ having a side chain that contributes to dispersibility in the dispersion medium in the electrophoretic dispersion, and the monomer M ₁ A plurality of dispersion units derived from is connected.

Monomer M ₁ is provided with one polymerizable group, as may be polymerized by living radical polymerization (radical polymerization), after the polymerization is a monofunctional monomer pendant with a portion to be a non-ionic side chains.

By using the monomer M ₁ having a nonionic side chain, the dispersion part 32 formed by living radical polymerization has an excellent affinity for the dispersion medium contained in the electrophoretic dispersion described later. Will be shown. Therefore, in the electrophoretic dispersion liquid, the electrophoretic particles 1 including the dispersion portion 32 are dispersed with excellent dispersibility without aggregation.

As the one polymerizable group of the monomer M _1, for example, vinyl group, styryl group, a carbon such as (meth) acryloyl group - include those containing a carbon double bond.

Examples of such a monomer M ₁ include vinyl monomers, vinyl ester monomers, vinylamide monomers, (meth) acrylic monomers, (meth) acrylic ester monomers, (meth) acrylamide monomers, styryl monomers, and the like. 1-hexene, 1-heptene, 1-octene, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, decyl (meth) Acrylic monomers such as acrylate, isooctyl (meth) acrylate, isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, pentafluoro (meth) acrylate, silicone macromonomer represented by the following general formula (I) -Styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, 2-propylstyrene, 3-propylstyrene, 4-propylstyrene, 2 -Styrenic monomers, such as isopropyl styrene, 3-isopropyl styrene, 4-isopropyl styrene, 4-tert- butyl styrene, are mentioned, It can use combining these 1 type (s) or 2 or more types.

［式中、Ｒ^１は水素原子またはメチル基、Ｒ^２は水素原子または炭素数１〜４のアルキル基、Ｒ^３は、炭素数１〜６までのアルキル基およびエチレンオキサイドまたはプロピレンオキサイドのエーテル基のうちの１種を含む構造、ｎは０以上の整数を表す。］

[Wherein, R ¹ is a hydrogen atom or a methyl group, R ² is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R ³ is an alkyl group having 1 to 6 carbon atoms and an ether group of ethylene oxide or propylene oxide. The structure containing 1 type of these, n represents an integer greater than or equal to 0. ]

Among these, the monomer M ₁ is preferably a silicone macromonomer represented by the above general formula (I). Dispersion unit obtained by polymerizing such monomers M ₁ exhibits excellent dispersibility in a non-polar dispersion medium. That is, as a dispersion medium contained in the electrophoretic dispersion described later, a material mainly composed of silicone oil is preferably used, but even when a hydrocarbon-based solvent is used like this silicone oil, Excellent affinity for the dispersion medium. Therefore, it is possible to with a good dispersibility electrophoretic particles 1 with a dispersing section 32 which is obtained by the monomer M ₁ is polymerized is dispersed in a dispersion medium.

If the monomer _{M 1} a silicone macro monomer represented by the general formula (I), the weight average molecular weight is preferably on the order of 1,000 to 60,000, 3,000 to 30,000 More preferably, it is about 5,000 or more and 20,000 or less. Thereby, the electrophoretic particle 1 provided with the dispersion part 32 obtained by the polymerization of the monomer M ₁ can be dispersed in the dispersion medium with more excellent dispersibility.

Further, the weight average molecular weight of the dispersion part 32 is preferably 10,000 or more and 100,000 or less, and more preferably 10,000 or more and 60,000 or less. In particular, as monomers M _1, when using silicone macromonomers as represented by formula (I), or when using hydrocarbon monomers, the weight average molecular weight of the dispersing section 32, more than 8,000 It is preferably 50,000 or less, and more preferably 10,000 or more and 35,000 or less. Thereby, the dispersibility in the electrophoresis dispersion liquid of the electrophoretic particle 1 can be made more excellent.

  Furthermore, in one polymer, the number of dispersion units contained in the dispersion part 32 is preferably 1 or more and 20 or less, and more preferably 2 or more and 10 or less. Thereby, the dispersibility in the electrophoresis dispersion liquid of the electrophoretic particle 1 can be provided reliably.

  The coupling portion 31 is coupled to the surface of the mother particle 2 in the coating layer 3 included in the electrophoretic particle 1, thereby coupling the first compound 39 to the mother particle 2.

In the present embodiment, the bonding portion 31 has a second functional group having an alkoxysilyl group as a second functional group that can form a covalent bond by reacting with the hydroxyl group provided on the surface of the mother particle 2 as the first functional group. monomer M ₂ of 2 are polymerized portion formed by a plurality polymerization, bond unit derived from the monomer M ₂ (structural units) are continuous plurality.

Thus, the dispersibility of the electrophoretic particle 1 is further improved by using the first compound 39 including the bonding portion 31 having a plurality of bonding units each having an alkoxysilyl group as the second functional group. It can be. That is, the first compound 39 includes not only a plurality of alkoxysilyl groups as second functional groups but also a plurality of alkoxysilyl groups concentrated on the bonding portion 31. Furthermore, since the coupling | bond part 31 has several coupling | bonding units connected, the site | part which can react with the mother particle 2 is large compared with the case where there is only one coupling unit. Therefore, the first compound 39, the coupling portion 31 formed by a plurality of monomer M ₂ is polymerized, it can be assumed that securely bonded to the surface of the mother particle 2.

In the present embodiment, as described above, with a hydroxyl group as a first functional group on the surface of the mother particle 2, the second functional group with a monomer M ₂ has a alkoxysilyl group. By using such a combination of a hydroxyl group and an alkoxysilyl group, the reaction between them exhibits excellent reactivity, so that the bonding to the surface of the mother particle 2 at the bonding portion 31 can be more reliably formed. Can do.

Such monomers M _2, as a second functional group comprising one alkoxysilyl group represented by the following formula (II), further comprising one polymerizable group, as may be polymerized by living radical polymerization Is.

［式中、Ｒは、それぞれ、独立して、炭素数１〜４のアルキル基、ｎは１〜３の整数を表す。］

[In formula, R represents a C1-C4 alkyl group each independently, and n represents the integer of 1-3. ]

By using the monomer M ₂ having such a configuration, it is possible to obtain the bonding part 31 in which the monomer M ₂ is polymerized by living radical polymerization, and the bonding part 31 formed by living radical polymerization is a mother particle. 2 shows excellent reactivity with respect to the hydroxyl group (first functional group) located on the surface of 2.

As the one polymerizable groups of the monomer M _2, similarly to the monomer M _1, for example, vinyl group, styryl group, a carbon such as (meth) acryloyl group - include those containing a carbon double bond.

Examples of such a monomer M ₂ include a vinyl monomer, a vinyl ester monomer, a vinyl amide monomer, a (meth) acryl monomer, and a (meth) each having one alkoxysilyl group represented by the general formula (II). Examples include acrylic ester monomers, (meth) acrylamide monomers, styryl monomers, and more specifically, 3- (meth) acryloxypropyltriethoxy (methoxy) silane, vinyltriethoxy (methoxy) silane, 4-vinylbutyl. Silanes containing silicon atoms such as triethoxy (methoxy) silane, 8-vinyloctyltriethoxy (methoxy) silane, 10-methacryloyloxydecyltriethoxy (methoxy) silane, 10-acryloyloxydecyltriethoxy (methoxy) silane mono Chromatography and the like, can be used in combination of one or more of them.

Further, in one polymer, the number of bonding units included in the bonding portion 31 is preferably 1 or more and 10 or less, more preferably 2 or more and 10 or less, and further preferably 3 or more and 6 or less. preferable. It exceeds the upper limit, since the coupling portion 31 is lower affinity for the dispersion medium is compared with the distribution unit 32, depending on the type of monomer M _2, or reduce the dispersibility of the electrophoretic particles 1, partially There is a risk of reaction between the coupling portions 31. Also, if less than the lower limit, depending on the type of monomer M _2, can not be sufficiently advanced the binding of the mother particles 2, the dispersibility of the electrophoretic particles 1 is decreased due to fear There is.

  Moreover, the number of the coupling | bonding units contained in the coupling | bond part 31 can be calculated | required by the analysis using general purpose analyzers, such as a NMR spectrum, IR spectrum, elemental analysis, and gel permeation chromatography (GPC). In the first compound 39, since the bonding portion 31 and the dispersion portion 32 are high molecular polymers, both have a certain molecular weight distribution. Therefore, the results of the analysis as described above may not apply to all the first compounds 39, but if at least the number of binding units obtained by the above method is 1 to 8, the first compound 39 and the mother The reactivity with the particles 2 and the dispersibility of the electrophoretic particles 1 can be made compatible.

  Such a first compound 39 is a diblock copolymer in which the bonding portion 31 and the dispersion portion 32 are individually provided. Therefore, since the binding property to the mother particle 2 and the dispersibility of the electrophoretic particle 1 can be independently imparted to the first compound 39, the electrophoretic particle 1 is contained in the electrophoretic dispersion liquid. And exhibit excellent dispersibility.

The first compound 39 can be obtained, for example, by using reversible addition-fragmentation chain transfer polymerization (RAFT) as described in the production method described later. When this reversible addition-fragmentation chain transfer polymerization (RAFT) is used, a relatively uniform polymer can be obtained. Therefore, if the polymerization by the addition of 1-8 molar equivalents of the monomer M ₂ with respect to the chain transfer agent, the number of binding units in coupling portion 31 may be in the above range. As a result, the electrophoretic particles 1 having the first compound 39 can be reliably exerted, and the electrophoretic particles 1 have excellent dispersibility in the electrophoretic dispersion. Become.

  The addition amount of the first compound 39 in the electrophoretic particles 1 is preferably 1.0 wt% or more and 10.0 wt% or less with respect to the mother particles 2, and is 3.0 wt% or more and 7.0 wt% or less. It is more preferable that Thereby, the dispersibility in the electrophoresis dispersion liquid of the electrophoretic particle 1 can be made more excellent.

  As described above, the second compound 37 is a silane coupling agent having a nonpolar group and an isocyanate group in the present embodiment.

  The second compound 37 has a molecular weight smaller than that of the first compound 39, but is linked to the mother particle 2 by reacting with the hydroxyl group as the first functional group in the isocyanate group.

  Here, as described above, the second compound 37 has an isocyanate group, and in the present embodiment, the mother particle 2 has a hydroxyl group as a first functional group on the surface thereof. These hydroxyl groups and isocyanate groups exhibit particularly excellent reactivity, and a chemical bond is reliably formed between the hydroxyl groups and the isocyanate groups by the progress of the reaction represented by the following reaction formula (A). be able to. Therefore, the second compound 37 can be connected to the surface of the mother particle 2 with a particularly high coverage.

  Furthermore, the mother particle 2 has its own positive or negative charge amount depending on the type of the selected mother particle 2. On the other hand, in the electrophoretic display device 920, in order to set the migration speed of the electrophoretic particles 1 to an appropriate size, it is necessary to control the charge amount of the electrophoretic particles 1.

  As a method for controlling the charge amount, for example, it is conceivable to cover the charged region exposed on the surface of the mother particle 2 with the first compound 39. However, the first compound 39 is a block copolymer and has a molecular weight. In addition, the introduction amount is also set to a certain prescribed amount in order to impart dispersibility to the electrophoretic particles 1. Therefore, it is impractical to define the introduction amount of the first compound 39 for the purpose of controlling the charge amount, that is, the migration speed.

  On the other hand, in the present invention, in addition to the first compound 39, the second compound 37 (silane coupling agent) having a molecular weight smaller than that of the first compound 39 is added to the mother particle 2. It is configured to be connected to the particle 2.

  As a result, as shown in FIG. 2, the second compound 37 can be linked between the first compounds 39 linked to the mother particle 2, and the introduction amount (linkage amount) is predetermined. By setting this amount, it is possible to cover a predetermined region of the charged region exposed on the surface of the mother particle 2. Therefore, the charge amount of the electrophoretic particles 1, that is, the migration speed can be set to a desired size. Therefore, the electrophoretic particle 1 in which the charge amount is set in an appropriate range can be obtained by appropriately setting the coating amount of the second compound 37 on the charged region.

  Furthermore, the 2nd compound 37 is provided with a nonpolar group in this embodiment. Therefore, the charge amount of the electrophoretic particles 1 can be set by adjusting the introduction amount (covering region) of the second compound 37 with respect to the charged region exposed on the surface of the mother particle 2. By covering the entire region with the second compound 37, the charge amount of the electrophoretic particles 1 can be set to substantially 0, specifically, the ζ potential can be set to less than ± 1 mV. That is, the electrophoretic particles 1 can be made uncharged. Furthermore, not only does the dispersion and chargeability (charge amount) of the electrophoretic particles 1 not be adversely affected, but also aggregation of the electrophoretic particles 1 can be accurately suppressed or prevented. Such agglomeration of the electrophoretic particles 1 is particularly caused when the electrophoretic particles 1 are negatively charged (negatively charged) as in the electrophoretic display device 920 described later, and positively charged (positively charged). ), The aggregation of the white particles 95a and the colored particles 95b having the opposite chargeability can be more accurately suppressed.

  As described above, the nonpolar group imparts to suppress or prevent aggregation of the electrophoretic particles 1 in the electrophoretic dispersion liquid, and further, the second compound 37 is linked to the surface of the mother particle 2. Thus, the electrophoretic particles 1 are provided on the surface of the mother particles 2 in the coating layer 3 so that the charge amount of the electrophoretic particles 1 can be controlled to an uncharged state.

  The nonpolar group is not particularly limited as long as it exhibits nonpolarity. For example, an alkyl group, an aryl group, a cycloalkyl group, a phenyl group, an alkenyl group, an aralkyl group, a cycloalkenyl group, A hydrocarbon group such as an alkynyl group, an aryl ether group, a silyl group, a siloxanyl group, an alkoxy group and the like can be mentioned, and one or more of these can be used in combination. It is preferable that Since the hydrocarbon group exhibits excellent non-polarity, aggregation of the electrophoretic particles 1 can be more accurately suppressed or prevented.

  The hydrocarbon group is particularly preferably an alkyl group. Since the alkyl group has a structure that is particularly difficult to be charged, the above-described effect can be exhibited more remarkably.

  The hydrocarbon group preferably has 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms. Thereby, the 2nd compound 37 can be reliably connected to the field between the 1st compounds 39 connected to mother particle 2, while exhibiting the function as a nonpolar group.

  Further, the nonpolar group may be linear, branched or cyclic, but is preferably linear. Thereby, the steric hindrance of the nonpolar group is reduced, and the second compound 37 can be reliably inserted in the region between the first compounds 39 connected to the mother particle 2.

  The second compound 37 (silane coupling agent) having such a nonpolar group and an isocyanate group is, for example, a silane system represented by the following general formula (III) when the nonpolar group is D. A coupling agent is mentioned.

［式中、Ｄは、非極性基を表し、Ｒは、炭素数１〜４のアルキル基、ｎは１〜３の整数を表す。］

[In formula, D represents a nonpolar group, R represents a C1-C4 alkyl group, and n represents the integer of 1-3. ]

  In the silane coupling agent represented by the general formula (III), n is 2 or 3, that is, the second compound 37 has a plurality of (2 or 3) isocyanate groups. Preferably there is. Thereby, a contact opportunity with the hydroxyl group (1st functional group) with which the mother particle 2 is provided becomes large compared with the case where there is only one isocyanate group. Therefore, the second compound 37 can be reliably bonded to the surface of the mother particle 2 through a chemical bond formed by a reaction between an isocyanate group and a hydroxyl group.

  The second compound 37 may be a compound in which a nonpolar group is directly connected to a silicon atom as shown in the general formula (III), but an inclusion such as a siloxane skeleton is not bonded to a silicon atom. It may be interposed between the polar group.

  The molecular weight of the second compound 37 is preferably 100 or more and 1,000 or less, and more preferably 100 or more and 500 or less. Thereby, the steric hindrance of the second compound 37 (silane coupling agent) is reduced, and the second compound 37 is reliably inserted in a region between the first compounds 39 connected to the mother particle 2. The second compound 37 can be reliably connected to the base particle 2 with excellent reactivity of the isocyanate group. As a result, the dispersibility of the electrophoretic particles 1 in the electrophoretic dispersion liquid can be further improved while setting the charge amount of the electrophoretic particles 1 within an appropriate range.

  Furthermore, when the weight average molecular weight of the dispersion part 32 is A and the molecular weight of the second compound 37 is B, A / B is preferably 10 or more and 1,000 or less, and 50 or more and 500 or less. Is more preferable. Thereby, the said effect can be exhibited more notably.

  The amount of the second compound 37 added to the electrophoretic particles 1 is preferably 0.1 wt% or more and 3.0 wt% or less with respect to the mother particles 2, and is 0.3 wt% or more and 2.5 wt% or less. It is more preferable that Thereby, the said effect can be exhibited more notably.

  By connecting the second compound 37 as described above to the mother particle 2, the electrophoretic particle 1 has an excellent electrophoretic property in which the charge amount is set in an appropriate range in the electrophoretic dispersion liquid. It becomes.

  In the present embodiment, the case where the second compound 37 includes a nonpolar group has been described from the viewpoint that the charge amount of the electrophoretic particles 1 can be easily controlled. The second compound 37 may have a polar group. For example, when the mother particle 2 exhibits negative chargeability and the electrophoretic particle 1 is uncharged, by using the second compound 37 as a polar group and a positively chargeable group (positive polarity group). By connecting a relatively small amount of the second compound 37 to the surface of the base particle 2, the electrophoretic particles 1 can be made non-charged. Further, when the mother particle 2 exhibits positive chargeability and the electrophoretic particle 1 is uncharged, by using the second compound 37 having a negative chargeable group (negative polarity group) as a polar group By connecting a relatively small amount of the second compound 37 to the surface of the base particle 2, the electrophoretic particles 1 can be made non-charged. Examples of the negatively chargeable group include a sulfone group and a carboxyl group, and examples of the positively chargeable group include amines and salts thereof, and quaternary ammonium salts.

  As described above, the electrophoretic particle 1 of the present embodiment in which the first compound 39 and the second compound 37 are connected to the surface of the mother particle 2 is, for example, the method for producing the electrophoretic particle of the present invention. By applying, it can be manufactured as follows.

<Method for producing electrophoretic particles>
FIG. 3 is a flowchart showing the manufacturing method of the first embodiment of the electrophoretic particle of the present invention in the order of steps.

In the present embodiment, the method for producing the electrophoretic particle 1 includes the step of obtaining the first compound 39 in which the bonding portion 31 and the dispersion portion 32 are connected by using the monomer M ₁ and the monomer M ₂ by living polymerization. By reacting the first functional group (hydroxyl group) provided on the surface of the mother particle 2 (particle) with the second functional group (alkoxysilyl group) of the first compound 39, the first compound is reacted. 39 is coupled to the mother particle 2 at the bonding portion 31, and the first functional group provided on the surface of the mother particle 2 is reacted with the isocyanate group of the second compound 37, thereby causing the second reaction. The compound 37 is connected to the base particle 2 to form the coating layer 3.

In the step of obtaining a first compound 39, the living radical polymerization using a polymerization initiator, 1) after the first monomer M ₁ formed a dispersing section 32 which is polymerized, the having a second functional group may form a coupling portion 31 which monomer M ₂ are polymerized in 2, 2) the coupling portion 31 and the dispersing portion 32 may be formed in this order, but here, 1 by the method), a plurality of The case where the 1st compound 39 is formed is demonstrated.

Hereinafter, each process is explained in full detail.
[1] First, a plurality of first compounds 39 in which the dispersion part 32 and the coupling part 31 are connected is generated (first step; S1).

[1-1] First, by living polymerization using a polymerization initiator, to form a dispersion unit 32 in which the first monomer M ₁ is polymerized.

Examples of the living polymerization method include living radical polymerization, living cation polymerization, and living anion polymerization, among which living radical polymerization is preferable. Living With the radical polymerization, the reaction solution and the like can be conveniently used to occur in the reaction system, further, it is possible to also improve polymerizing monomers M ₁ control of the reaction.

Living radical polymerization methods include atom transfer radical polymerization (ATRP), radical polymerization via nitroxide (NMP), radical polymerization using organic tellurium (TERP), and reversible addition-fragmentation chain transfer polymerization (RAFT). Among them, it is preferable to use reversible addition-fragmentation chain transfer polymerization (RAFT). According to reversible addition-fragmentation chain transfer polymerization (RAFT), there is no concern about metal contamination without using a metal catalyst, and further, the polymerization during the polymerization of the monomer M ₁ can be easily advanced.

  The polymerization initiator (radical polymerization initiator) is not particularly limited. For example, 2,2′-azobisisobutyronitrile (AIBN), 2,2′-azobis (4-methoxy-2.4-dimethylvaleronitrile) ), 2,2'-azobis (2.4-dimethylvaleronitrile), dimethyl 2,2'-azobis (2-methylpropionate), 1,1'-azobis (cyclohexane-1-carbonitrile), 2,2 Azo initiators such as' -azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride, 2,2'-azobis [2- (2-imidazolin-2-yl) propane], Examples thereof include persulfates such as potassium sulfate and ammonium persulfate.

  When reversible addition-fragmentation chain transfer polymerization (RAFT) is used, a chain transfer agent (RAFT agent) is used in addition to the polymerization initiator. The chain transfer agent is not particularly limited, and examples thereof include sulfur compounds having a functional group such as a dithioester group, a trithiocarbamate group, a xanthate group, and a dithiocarbamate group.

  Specifically, examples of the chain transfer agent include compounds represented by the following chemical formulas (1) to (7), and one or more of them can be used in combination. These compounds are preferably used because they are relatively easily available and the reaction can be easily controlled.

Further, when reversible addition-fragmentation chain transfer polymerization (RAFT) is used, the ratio of the monomer M ₁ , the polymerization initiator, and the chain transfer agent depends on the degree of polymerization of the dispersion 32 to be formed and the reactivity of the compound such as the monomer M ₁ . The molar ratio is preferably monomer: polymerization initiator: chain transfer agent = 500 to 5: 5 to 0.25: 1. Thus, it is possible to set the length of the dispersing section 32 which is obtained by the monomer M ₁ is polymerized (polymerization degree) to the appropriate size.

As the solvent for preparing a solution polymerizing monomers M ₁ by living radical polymerization, for example, water, alcohols such as methanol, ethanol, butanol, hexane, octane, benzene, hydrocarbons such as toluene and xylene , Ethers such as diethyl ether and tetrahydrofuran, esters such as ethyl acetate, halogenated aromatic hydrocarbons such as chlorobenzene and o-dichlorobenzene, and the like can be used alone or as a mixed solvent. .

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

Further, the polymerization reaction of the monomer M _1, by heating the temperature of said solution to a predetermined temperature (warming), it is possible to carry out the polymerization reaction of the monomer more quickly and reliably.

This heating temperature is slightly different depending on the kind of the monomer M _1, etc., it is not particularly limited, preferably about 30 to 100 ° C.. The heating time (reaction time) is preferably about 5 to 48 hours when the heating temperature is in the above range.

  When reversible addition-fragmentation chain transfer polymerization (RAFT) is used, a fragment of the used chain transfer agent is present at one end (front end) of the dispersion portion 32. And the dispersion | distribution part 32 provided with this fragment | piece acts as a chain transfer agent in reaction which superposes | bonds the coupling | bond part 31 to the dispersion | distribution part 32 in the following process [1-2].

[1-2] Next, a second functional group (alkoxysilyl group) having a second functional group (alkoxysilyl group) that is reactive with the first functional group (hydroxyl group) included in the mother particle 2 so as to be connected to the dispersion part 32. to form a coupling portion 31 which monomer M ₂ are polymerized.

  Thereby, the 1st compound 39 comprised with the diblock copolymer with which the dispersion | distribution part 32 and the coupling | bond part 31 were connected is produced | generated.

Incidentally, in this step [1-2], prior to the formation of the coupling portion 31 with a monomer _{M 2,} optionally, unreacted monomer _{M 1} and solvent used in the step [1-1], You may make it perform the refinement | purification process (removal process) which removes impurities, such as a polymerization initiator, and isolates and purifies the dispersion | distribution part 32. FIG. Thereby, the 1st compound 39 obtained by this process [1-2] becomes more uniform and a thing with high purity. The purification treatment is not particularly limited, and examples thereof include a column chromatography method, a recrystallization method, a reprecipitation method, and the like, and one or more of them can be combined.

As described above, when reversible addition-fragmentation chain transfer polymerization (RAFT) is used, a fragment of the used chain transfer agent is present at one end of the dispersion portion 32. Thus, coupling portions 31 of such a configuration, as the step [1-1] dispersing unit 32 is obtained by completing, as a monomer M _2, a solution containing a polymerization initiator was prepared and this solution Then, it is formed by performing living polymerization again.

As the solvent used in this step, the process can be used. Similar to that mentioned in [1-1], also conditions for the polymerization of monomers M ₂ in solution, the step [ 1-1] can be similar to that mentioned as conditions for polymerizing the monomer M ₁ in solution in.

  [2] Next, the first functional group included in the mother particle 2 and the plurality of second functional groups included in the bonding portion 31 are reacted to form a chemical bond between them. The first compound 39 is linked to the mother particle 2 (second step; S2).

Examples of such processes include the dry method and wet method shown below.
<< dry method >>
In the dry method, first, the first compound 39 and the mother particles 2 are mixed in a suitable solvent to prepare a solution. In addition, in order to accelerate | stimulate hydrolysis of the alkoxy silyl group (2nd functional group) with which the 1st compound 39 is provided in a solution, you may add a trace amount of water, an acid, and a base as needed. Moreover, you may perform a heating, light irradiation, etc. as needed.

  At this time, the volume of the solvent is preferably about 1% by volume or more and about 20% by volume or less, and more preferably about 5% by volume or more and about 10% by volume or less with respect to the volume of the mother particle 2. . Thereby, since the contact opportunity of the 1st compound 39 with respect to the mother particle 2 can be increased, the coupling | bond part 31 can be more reliably couple | bonded with the surface of the mother particle 2. FIG.

  Next, dispersion by ultrasonic irradiation, stirring using a ball mill, bead mill, or the like is performed to adsorb the first compound 39 to the surface of the mother particle 2 with high efficiency, and then the solvent is removed.

  Subsequently, the powder obtained by removing the solvent is preferably heated at 100 ° C. to 200 ° C. for 1 hour or more to decompose the alkoxysilyl group (second functional group), thereby generating the mother particles. A chemical bond is formed with a hydroxyl group (first functional group) exposed on the surface of 2.

  Next, the excess first compound 39 adsorbed on the surface of the mother particle 2 is removed without forming a chemical bond by washing again in the solvent several times using a centrifuge.

  Through the steps as described above, the first compound 39 can be linked to the mother particle 2.

<< Wet method >>
In the wet method, first, the first compound 39 and the mother particle 2 are mixed in a suitable solvent to prepare a solution. In addition, in order to accelerate | stimulate hydrolysis of the alkoxy silyl group (2nd functional group) with which the 1st compound 39 is provided in a solution, you may add a trace amount of water, an acid, and a base as needed. Moreover, you may perform a heating, light irradiation, etc. as needed.

  At this time, the volume of the solvent is preferably about 1% by volume or more and about 20% by volume or less, and more preferably about 5% by volume or more and about 10% by volume or less with respect to the volume of the mother particle 2. . Thereby, since the contact opportunity of the 1st compound 39 with respect to the mother particle 2 can be increased, the coupling | bond part 31 can be more reliably couple | bonded with the surface of the mother particle 2. FIG.

  Subsequently, the dispersion by ultrasonic irradiation, stirring using a ball mill, a bead mill, or the like is performed so that the first compound 39 is adsorbed on the surface of the mother particle 2 with high efficiency. The first compound 39 is heated to 100 ° C. to 200 ° C. for 1 hour or longer to decompose the alkoxysilyl group to form a chemical bond with the hydroxyl group exposed on the surface of the mother particle 2 to thereby form the first compound 39 as the mother particle 2. Can be linked.

  Next, the excess first compound 39 adsorbed on the surface of the mother particle 2 is removed without forming a chemical bond by washing again in the solvent several times using a centrifuge.

  [3] Next, the first functional group remaining in the mother particle 2 to which the plurality of first compounds 39 are linked is reacted with the second functional group of the second compound 37 to thereby react each other. A plurality of second compounds 37 are linked to the mother particle 2 by forming a chemical bond between them (third step; S3).

The second compound 37 can be prepared using various known methods.
In addition, as a process for linking the second compound 37 to the mother particle 2, the dry method and the wet method exemplified in the step [2] are used in the same manner as the process for linking the first compound 39 to the mother particle 2. It is done.

  When the second compound 37 is linked to the mother particle 2, the second compound 37 has an isocyanate group, so that the mother particle 2 particularly has a hydroxyl group provided as the first functional group. Excellent reactivity. Therefore, since a chemical bond can be reliably formed between the hydroxyl group and the isocyanate group, the second compound 37 can be connected to the surface of the mother particle 2 with a particularly high coverage.

  Thereby, the electrophoretic particle 1 in which at least a part of the mother particle 2 is coated with the coating layer 3 is obtained.

  Through the steps as described above, the electrophoretic particles 1 of the present invention can be obtained in a purified state.

Depending on the type of monomer M ₁ contained in the first compound 39, when the electrophoretic particles 1 are dried, they may not be dispersed in the dispersion solvent. In such a case, it is preferable to carry out the solvent replacement method in which the reaction solvent is gradually replaced with the dispersion solvent during the washing operation (without passing through the drying step).

  Moreover, as a solvent used for this process, the thing similar to the thing quoted by the said process [1-1] can be used, In addition, the aliphatic hydrocarbons mentioned as a dispersion liquid with which the electrophoretic dispersion liquid mentioned later ( Liquid paraffin) and silicone oil can be used.

<< Second Embodiment >>
Next, a second embodiment of the electrophoretic particles of the present invention will be described.

  FIG. 4 is a schematic diagram of the first compound and the second compound included in the second embodiment of the electrophoretic particle of the present invention.

  Hereinafter, the electrophoretic particles of the second embodiment will be described with a focus on differences from the electrophoretic particles of the first embodiment, and description of similar matters will be omitted.

  As shown in FIG. 4, the electrophoretic particle 1 of the present embodiment is similar to that shown in FIG. 2 except that the configuration of the second compound is different from the first compound and the second compound that bind to the mother particle 2. The same as the electrophoretic particles 1 of the first embodiment shown.

That is, in the electrophoretic particle 1 of the second embodiment, a second compound 38 is linked instead of the second compound 37, and the second compound 38 is a third monomer having a nonpolar group. It is a block copolymer having a nonpolar portion 33 derived from M ₃ and a bonding portion 34 derived from a _fourth monomer M ₄ having an isocyanate group. In the second compound 38 having such a configuration, the second compound 38 is linked to the mother particle 2 by the reaction of the first functional group (hydroxyl group) and the isocyanate group at the bonding portion 34.

  The nonpolar portion 33 of the second compound 38 aggregates the electrophoretic particles 1 in the electrophoretic dispersion described later, similarly to the nonpolar group provided in the second compound 37 of the first embodiment. In order to suppress or prevent, it is provided on the surface of the mother particle 2 in the coating layer 3.

The non-polar portion 33, the electrophoretic dispersion liquid, after polymerization, the by nonpolar group second compound 37 is provided in the first embodiment is a monomer M ₃ having a portion serving as a side chain are a plurality of polymerization is formed, a non-polar units derived from the monomer M ₃ is multiple linked.

Monomer M ₃ are provided with one polymerizable group, as may be polymerized by living radical polymerization (radical polymerization), after the polymerization is a monofunctional monomer pendant with a portion to be a non-polar side chain of.

By using the monomer M ₃ having a non-polar side chain, the non-polar part 33 formed by living radical polymerization suppresses or prevents aggregation of the electrophoretic particles 1 in the electrophoretic dispersion described later. The function to perform is surely demonstrated. Therefore, in the electrophoretic dispersion liquid, the electrophoretic particles 1 including the nonpolar portion 33 are dispersed with excellent dispersibility without aggregation.

Examples of such monomers M _3, instead of contributing side chains in dispersibility comprising monomers M ₁ described above, a non-polar group included in the second compound 37 as described above, be used those having as a side chain it can.

  In addition, the bonding portion 34 is bonded to the surface of the mother particle 2 in the coating layer 3 included in the electrophoretic particle 1, and thereby connects the second compound 38 to the mother particle 2. As this bonding part 34, the same structure is used except that the bonding part 31 included in the first compound 39 described above has an isocyanate group instead of the second functional group (alkoxysilyl group). Can do.

  The electrophoretic particles of the second embodiment including the second compound 38 composed of the block copolymer having the nonpolar portion 33 and the bonding portion 34 can also obtain the same effect as the first embodiment. It is done.

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

  The electrophoretic dispersion liquid is obtained by dispersing (suspending) at least one type of electrophoretic particles 1 (electrophoretic particles of the present invention) in a dispersion medium (liquid phase dispersion medium). That is, the electrophoretic dispersion liquid contains the electrophoretic particles 1 and the dispersion medium. Since the electrophoretic dispersion liquid contains the electrophoretic particles 1, the electrophoretic particles 1 exhibit the effects described above. In the electrophoretic dispersion liquid, the electrophoretic particles 1 have a uniform dispersibility, and The charge amount is set to an appropriate range.

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

  Among these, as the dispersion medium, those mainly composed of aliphatic hydrocarbons (liquid paraffin) or silicone oil are preferable. Since the dispersion medium containing liquid paraffin or silicone oil as a main component has a high aggregation suppressing effect on the electrophoretic particles 1, the display performance of the electrophoretic display device 920 shown in FIG. Can do. Further, liquid paraffin or silicone oil has an advantage that it has excellent weather resistance and high safety because it does not have an unsaturated bond.

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

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

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

  In such an electrophoretic dispersion, the electrophoretic particles 1 have uniform dispersibility and an appropriate charge amount due to the action of the first compound 39 and the second compound 37 included in the coating layer 3. It will be set to the range.

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

  FIG. 5 is a diagram schematically showing a longitudinal section of an embodiment of the electrophoretic display device, and FIGS. 6 and 7 are schematic diagrams showing the operation principle of the electrophoretic display device shown in FIG. In the following description, for convenience of explanation, the upper side in FIGS. 5 to 7 will be described as “upper” and the lower side as “lower”.

  An electrophoretic display device 920 shown in FIG. 5 includes an electrophoretic display sheet (front plane) 921, a circuit board (back plane) 922, an adhesive layer 98 that bonds the electrophoretic display sheet 921 and the circuit board 922, and A sealing portion 97 that hermetically seals a gap between the electrophoretic display sheet 921 and the circuit board 922 is provided.

  An electrophoretic display sheet (electrophoretic sheet of the present invention) 921 includes a substrate 912 including a flat base 92 and a second electrode 94 provided on the lower surface of the base 92, and a lower surface (one surface) of the substrate 912. ) Side and a display layer 9400 including a partition wall 940 (a plurality of structures) formed in a matrix and an electrophoretic dispersion liquid 910. Note that in the display layer 9400, the electrophoretic dispersion liquid 910 is stored in a plurality of pixel spaces 9401 defined by the partition walls 940.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  In the present embodiment, negatively charged particles are used as the white particles 95a, and positively charged particles (black particles) 95b are used. That is, the electrophoretic particle 1 in which the mother particle 2 is negatively (negatively) charged is used as the white particle 95a, and the mother particle 2 is positively (positively) charged in the colored particle 95b. Is used.

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

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

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

  In addition, by applying the electrophoretic particles 1 to the white particles 95a and the colored particles 95b, the white particles 95a and the colored particles 95b have uniform dispersibility and the charge amount is set in an appropriate range. Therefore, the electrophoretic display device 920 (electrophoretic display sheet 921) including the white particles 95a and the colored particles 95b has high performance and reliability.

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

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

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

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

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

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

  In the present embodiment, in the electrophoretic display device 920, as the white particles 95a and the colored particles (black particles) 95b to which the electrophoretic particles 1 are applied, negatively charged and positively charged particles are prepared, respectively. The electrophoretic display device 920 is configured to perform two-particle black-and-white display. However, the electrophoretic display device 920 is not limited to such a configuration, and as white particles 95a and colored particles (black particles) 95b, Two-particle black-and-white display including non-charged and positive or negative ones may be made, respectively. Further, as white particles 95a, black particles, and non-black color particles, uncharged, respectively. Three-particle color display including negatively charged and positively charged ones may be made.

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

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

FIG. 8 is a perspective view showing an embodiment when the electronic apparatus of the present invention is applied to electronic paper.
An electronic paper 600 shown in FIG. 8 includes a main body 601 composed of a rewritable sheet having the same texture and flexibility as paper, and a display unit 602.

  In such an electronic paper 600, the display unit 602 includes the electrophoretic display device 920 as described above, so that the electronic paper 600 has high performance and reliability.

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

  FIG. 9 is a cross-sectional view showing an embodiment when the electronic device of the present invention is applied to a display, and FIG. 10 is a plan view showing the embodiment when the electronic device of the present invention is applied to a display.

  A display (display device) 800 shown in FIGS. 9 and 10 includes a main body 801 and an electronic paper 600 that is detachably attached to the main body 801.

  The main body 801 is provided with an insertion port 805 into which the electronic paper 600 can be inserted on the side (right side in FIG. 9), and two pairs of conveying rollers 802a and 802b are provided therein. When the electronic paper 600 is inserted into the main body 801 through the insertion port 805, the electronic paper 600 is installed in the main body 801 in a state of being sandwiched between the transport roller pairs 802a and 802b.

  In addition, a rectangular hole 803 is formed on the display surface side of the main body 801 (the front side in FIG. 10), and a transparent glass plate 804 is fitted in the hole 803. Thereby, the electronic paper 600 installed in the main body 801 can be viewed from the outside of the main body 801. That is, in the display 800, the display surface is configured by visually recognizing the electronic paper 600 installed in the main body 801 on the transparent glass plate 804.

  Further, a terminal portion 806 is provided at the leading end portion (left side in FIG. 9) of the electronic paper 600 in the insertion direction, and the terminal is provided inside the main body portion 801 with the electronic paper 600 installed on the main body portion 801. A socket 807 to which the unit 806 is connected is provided. A controller 808 and an operation unit 809 are electrically connected to the socket 807.

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

  In such a display 800, the electronic paper 600 includes the electrophoretic display device 920 as described above, and thus the electronic paper 600 has high performance and reliability.

  Note that the electronic device of the present invention is not limited to the application to the above, and for example, a smartphone, a tablet terminal, a clock, a television, a viewfinder type, a monitor direct view type video tape recorder, a car navigation device, a pager. Electronic notebooks, calculators, electronic newspapers, word processors, personal computers, workstations, videophones, POS terminals, devices equipped with touch panels, and the like. An electrophoretic display device 920 is displayed on the display unit of these various electronic devices. It is possible to apply.

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

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

Next, specific examples of the present invention will be described.
Production of electrophoretic particles, preparation of electrophoretic dispersion, evaluation of electrophoretic dispersion 1. Synthesis of first compound (block copolymer) 1-1. Synthesis of dispersion part In a flask, a silicone macromonomer having a molecular weight of 16,000 ("Silaplane FM-0726" manufactured by JNC Corporation): 60 g, 2-cyano-2-propylbenzodithioate: 250 mg, azobisisobutyronitrile After adding 100 mg and replacing the system with nitrogen, 22.5 mL of ethyl acetate was further added, and then heated and stirred at 75 ° C. for 8 hours to polymerize the silicone macromonomer. This was cooled to room temperature to complete the reaction, and the solvent was removed to obtain a silicone polymer reaction solution.

  The obtained reaction solution was purified with a silica gel column using a mixed solvent of hexane and chloroform as a developing solvent, and impurities were removed to isolate the silicone polymer. As a result of measuring the weight average molecular weight (Mw) of the obtained silicone polymer by gel permeation chromatography using toluene as a developing solvent, it was confirmed to be 48,000.

1-2. Synthesis of Bonding Part In a flask, 10 g of the silicone polymer obtained above, 27.5 mg of azobisisobutyronitrile, 3-methacryloxypropyltriethoxysilane (“KBE-503” manufactured by Shin-Etsu Silicone): After 200 mg was added and the system was purged with nitrogen, ethyl acetate was further added. Thereafter, the mixture was heated and stirred at 75 ° C. for 4 hours for polymerization. This was cooled to room temperature to complete the reaction, and the solvent was removed to obtain a first compound (block copolymer) in which the dispersed portion and the bonded portion were connected.

2. Preparation of electrophoretic dispersion liquid containing white particles (positively charged particles) [Example 1A]
To the flask, 10 g of the first compound (block copolymer) obtained above and titania particles (“CR50” manufactured by Ishihara Sangyo Co., Ltd.): 60 g are added to silicone oil (“KF-96-20cs” manufactured by Shin-Etsu Chemical). After ultrasonic treatment for 1 hour, the first compound was bonded to the particles by heating and stirring at 180 ° C. for 8 hours.

  Thereafter, 1.8 g of methyl triisocyanate silane (manufactured by Matsumoto Fine Chemical Co., “Orgatix SI-310”, Mw: 169) is added as a second compound (addition amount 3 wt% with respect to 60 g of titania particles). After ultrasonic treatment for a period of time, the second compound was bonded to the particles by heating and stirring at 130 ° C. for 4 hours to obtain electrophoretic particles. Unreacted block copolymer and methyl triisocyanate silane were removed from the solution after the reaction, and the silicone oil was replaced with “KF-96L-2cs” manufactured by Shin-Etsu Chemical, thereby obtaining an electrophoretic dispersion liquid containing white particles.

  In addition, the addition amount of the 1st compound and the 2nd compound in the obtained electrophoretic particle was 2.5 wt% and 2.5 wt% with respect to the titania particle, respectively.

[Example 2A]
As a second compound, 1.2 g of methyl triisocyanate silane (amount 2 wt% charged with respect to 60 g of titania particles) was added, subjected to ultrasonic treatment for 1 hour, and then heated and stirred at 130 ° C. for 4 hours to obtain the second compound ( An electrophoretic dispersion liquid containing white particles was obtained in the same manner as in Example 1A except that methyl triisocyanate silane) was bonded to the particles.

  In addition, the addition amount of the 1st compound and the 2nd compound in the obtained electrophoretic particle was 2.5 wt% and 1.5 wt% with respect to the titania particle, respectively.

[Example 3A]
As a second compound, 0.9 g of methyltriisocyanate silane (a charge amount of 1.5 wt% with respect to 60 g of titania particles) was added, subjected to ultrasonic treatment for 1 hour, and then heated and stirred at 130 ° C. for 4 hours. An electrophoretic dispersion liquid containing white particles was obtained in the same manner as in Example 1A, except that the compound (methyl triisocyanate silane) was bonded to the particles.

  In addition, the addition amount of the 1st compound and the 2nd compound in the obtained electrophoretic particle was 2.5 wt% and 1.0 wt% with respect to the titania particle, respectively.

[Reference Example 1A]
As a second compound, 1.8 g of n-butyltrimethoxysilane (a charge amount of 3 wt% with respect to 60 g of titania particles) (manufactured by Gelest Co., Mw: 178.3) is added instead of methyltriisocyanatesilane, and ultrasonic treatment is performed for 1 hour. After that, electrophoresis including white particles was performed in the same manner as in Example 1A except that the second compound (n-butyltrimethoxysilane) was bonded to the particles by heating and stirring at 130 ° C. for 4 hours. A dispersion was obtained.

  In addition, the addition amount of the 1st compound and the 2nd compound in the obtained electrophoretic particle was 2.5 wt% and 0.5 wt% with respect to the titania particle, respectively.

[Reference Example 2A]
As a second compound, 3.0 g of n-butyltrimethoxysilane (a charge amount of 5 wt% with respect to 60 g of titania particles) was added instead of methyltriisocyanatesilane, and the mixture was subjected to ultrasonic treatment for 1 hour and then heated at 130 ° C. for 4 hours. An electrophoretic dispersion liquid containing white particles was obtained in the same manner as in Example 1A except that the second compound (n-butyltrimethoxysilane) was bonded to the particles by stirring.

  In addition, the addition amount of the 1st compound and the 2nd compound in the obtained electrophoretic particle was 2.5 wt% and 1.0 wt% with respect to the titania particle, respectively.

[Reference Example 3A]
As a second compound, 6.0 g of n-butyltrimethoxysilane (preparation amount of 10 wt% with respect to 60 g of titania particles) was added instead of methyltriisocyanatesilane, and the mixture was subjected to ultrasonic treatment for 1 hour and then heated at 130 ° C. for 4 hours. An electrophoretic dispersion liquid containing white particles was obtained in the same manner as in Example 1A except that the second compound (n-butyltrimethoxysilane) was bonded to the particles by stirring.

  In addition, the addition amount of the 1st compound and the 2nd compound in the obtained electrophoretic particle was 2.5 wt% and 1.0 wt% with respect to the titania particle, respectively.

[Comparative Example 1A]
An electrophoretic dispersion liquid containing white particles was obtained in the same manner as in Example 1A except that the addition of the second compound was not performed and the binding of the second compound to the titania particles was omitted.

3. Preparation of electrophoretic dispersion containing black particles (negatively charged particles) [Example 1B]
An electrophoretic dispersion liquid containing black particles was obtained in the same manner as in Example 1A except that titanium nitride particles (“SC13MT” manufactured by Mitsubishi Materials Corporation): 60 g were added to the flask instead of titania particles. .

  The addition amounts of the first compound and the second compound in the obtained electrophoretic particles were 2.3 wt% and 2.5 wt% with respect to the titanium nitride particles, respectively.

[Example 2B]
An electrophoretic dispersion liquid containing black particles was obtained in the same manner as in Example 2A, except that titanium nitride particles (“SC13MT” manufactured by Mitsubishi Materials Corporation): 60 g were added to the flask instead of titania particles. .

  In addition, the addition amount of the 1st compound and the 2nd compound in the obtained electrophoretic particle was 2.3 wt% and 1.5 wt% with respect to the titanium nitride particle, respectively.

[Example 3B]
An electrophoretic dispersion liquid containing black particles was obtained in the same manner as in Example 3A, except that titanium nitride particles (“SC13MT” manufactured by Mitsubishi Materials Corporation): 60 g were added to the flask instead of titania particles. .

  In addition, the addition amount of the 1st compound and the 2nd compound in the obtained electrophoretic particle was 2.3 wt% and 1.0 wt% with respect to the titanium nitride particle, respectively.

[Reference Example 1B]
An electrophoretic dispersion liquid containing black particles was obtained in the same manner as in Reference Example 1A, except that titanium nitride particles (“SC13MT” manufactured by Mitsubishi Materials Corporation): 60 g were added to the flask instead of titania particles. .

  In addition, the addition amount of the 1st compound and the 2nd compound in the obtained electrophoretic particle was 2.3 wt% and 0.5 wt% with respect to the titanium nitride particle, respectively.

[Reference Example 2B]
An electrophoretic dispersion liquid containing black particles was obtained in the same manner as in Reference Example 2A, except that titanium nitride particles (“SC13MT” manufactured by Mitsubishi Materials Corporation): 60 g were added to the flask instead of titania particles. .

  In addition, the addition amount of the 1st compound and the 2nd compound in the obtained electrophoretic particle was 2.3 wt% and 1.0 wt% with respect to the titanium nitride particle, respectively.

[Reference Example 3B]
An electrophoretic dispersion liquid containing black particles was obtained in the same manner as in Reference Example 3A, except that titanium nitride particles (“SC13MT” manufactured by Mitsubishi Materials Corporation): 60 g were added to the flask instead of titania particles. .

  In addition, the addition amount of the 1st compound and the 2nd compound in the obtained electrophoretic particle was 2.3 wt% and 1.0 wt% with respect to the titanium nitride particle, respectively.

[Comparative Example 1B]
An electrophoretic dispersion liquid containing black particles was obtained in the same manner as in Comparative Example 1A, except that titanium nitride particles (“SC13MT” manufactured by Mitsubishi Materials Corporation): 60 g were added to the flask instead of titania particles. .

4). Preparation of electrophoretic dispersion containing white particles and black particles About electrophoretic dispersion containing white particles of Example 1A and electrophoretic dispersion containing black particles of Examples 2B and 3B and Reference Examples 1B to 3B In addition, with respect to the electrophoretic dispersion liquid containing white particles of Reference Example 1A and Comparative Example 1A and the electrophoretic dispersion liquid containing black particles of Reference Example 1B, a combination of white particles and black particles, The electrophoresis dispersion liquid and the black electrophoresis dispersion liquid were mixed at a volume ratio of 10: 1 to prepare an electrophoresis dispersion liquid containing white particles and black particles.

5. Evaluation of electrophoretic dispersion 5-1. First, 2. ~ 3. The following electrophoretic dispersions prepared in (1) were evaluated for dispersibility and electrophoretic properties as follows.

<Dispersibility>
That is, first, a comb electrode substrate for evaluation was prepared in which a comb electrode having an interelectrode distance of 100 μm was formed on a glass substrate.

Next, after diluting the electrophoretic dispersion so that the content of the electrophoretic particles was 1 wt%, the diluted electrophoretic dispersion was dropped onto the comb-shaped electrode of the comb-shaped electrode substrate for evaluation.
Next, the dropped electrophoretic dispersion was observed using a microscope.

The results were evaluated based on the evaluation criteria shown below.
<< Evaluation criteria >>
A: No aggregation of the electrophoretic particles is observed in the electrophoretic dispersion liquid, and the electrophoretic particles spread uniformly in the electrophoretic dispersion liquid.
○: Some aggregation of electrophoretic particles is observed in the electrophoretic dispersion.
Δ: Some aggregation of electrophoretic particles is observed in the electrophoretic dispersion.
X: Many aggregations of electrophoretic particles are observed in the electrophoretic dispersion.

<Ζ potential>
Next, the ζ potential of the electrophoretic particles contained in the electrophoretic dispersion was measured using an ultrasonic zeta potential measuring device (manufactured by Nippon Luft Co., Ltd., “model number: DT-300”). First, an electrophoretic dispersion containing white particles or an electrophoretic dispersion containing black particles prepared to a concentration of 20 wt% is prepared in a 30 ml beaker. Next, the electrophoretic dispersion was immersed in a zeta potential probe to detect colloidal oscillation current, and the ζ potential was determined from this current value. The average value of the results obtained by measuring five times in total was obtained as an actual measurement value.
These evaluation results are shown in Tables 1 and 2.

  As is clear from Tables 1 and 2, in the electrophoretic dispersion liquid of each example, the second density is increased with a small amount of the second compound charge compared to the electrophoretic dispersion liquid of each reference example. The electrophoretic particles into which the compound was introduced were dispersed, and a result showing excellent dispersibility was obtained.

  Furthermore, in the electrophoretic dispersion liquid of the example, electrophoretic particles having a desired charge amount can be obtained according to the charged amount of the second compound. In Examples 1A and 1B, the ζ potential is 1.0 mV. It was possible to produce less than.

  5-2. The above 4. The electrophoretic dispersion prepared in (1) was evaluated for the following display performance, power consumption and retention.

<Display performance>
That is, 4. Each of the electrophoretic dispersions prepared in (1) was injected into a transparent electrode cell having a thickness of 50 μm to measure the white reflectance when displaying white, and the black reflectance when displaying black, and the contrast was calculated therefrom. .

The results were evaluated based on the evaluation criteria shown below.
<< Evaluation criteria >>
A: Contrast is 25 or more.
○: The contrast is 20 or more and less than 25.
Δ: Contrast is 15 or more and less than 20.
X: Contrast is less than 15.

<Power consumption>
The above 4. Each of the electrophoretic dispersions prepared in step 1 was measured for power consumption (μJ / cm ² ) in 1 sec when it was injected into a transparent electrode cell having a thickness of 50 μm and displayed in black.

The results were evaluated based on the evaluation criteria shown below.
<< Evaluation criteria >>
○: Power consumption is 0.2 μJ / cm ² or less.
△: the power consumption is less than 0.2μJ / cm ² ultra 1.0μJ / cm ^2.
X: Power consumption is 1.0 μJ / cm ² or more.

<Retention>
Furthermore, the above-mentioned 4. Each of the electrophoretic dispersions prepared in (1) was injected into a transparent electrode cell having a thickness of 50 μm to measure the white reflectance when displaying white, and the black reflectance when displaying black, and the contrast was calculated therefrom. . This contrast calculation was repeated for one week.

The results were evaluated based on the evaluation criteria shown below.
<< Evaluation criteria >>
○: Contrast reduction is within 5 weeks for 1 week or more.
Δ: Contrast drops by 5 or more within 1 day to 1 week.
X: Contrast drops 5 or more within one day.
The evaluation results are shown in Table 3.

  As is clear from Table 3, Example 1A comprising white particles with a ζ potential of <1.0 mV, Examples 2B and 3B comprising black particles with a ζ potential of 2.0 to 5.0 mV, Reference Example 1B In the electrophoretic dispersion in combination with 2B, a result showing excellent contrast, that is, display performance was obtained due to the excellent dispersibility of the white particles and the excellent electrophoretic property of the black particles in the electrophoretic dispersion.

  On the other hand, in the combination of Example 1A and Reference Example 3B, aggregation was caused between the black particles due to the addition amount of the second compound in the black particles, and as a result, the contrast was increased. That is, the results were inferior in display performance. Further, for the combination of Reference Example 1A and Comparative Example 1A and Reference Example 1B, the white particles exhibit electrophoretic properties due to the small amount of the second compound added to the white particles, and as a result, contrast, display Inferior results were shown.

  Similarly, the combination of Example 1A, Examples 2B and 3B, and Reference Examples 1B and 2B showed good values in terms of power consumption and retention, while the combination of Example 1A and Reference Example 3B A decrease in power consumption and retention was observed. Further, for the combination of Reference Example 1A and Comparative Example 1A and Reference Example 1B, further reductions in power consumption and retention were observed.

DESCRIPTION OF SYMBOLS 1 ... Electrophoretic particle, 2 ... Mother particle, 3 ... Covering layer, 31 ... Coupling part, 32 ... Dispersion part, 33 ... Nonpolar part, 34 ... Coupling part, 37 ... Second compound, 38 ... Second compound 39 ... first compound, 91 ... base, 92 ... base, 93 ... first electrode, 94 ... second electrode, 95 ... electrophoretic particles, 95a ... white particles, 95b ... colored particles, 96 ... dispersion medium 97 ... Sealing part, 98 ... Adhesive layer, 501 ... Electrophoretic particles, 502 ... Base particle, 503 ... Coating layer, 531 ... Silane coupling agent, 532 ... Polymerization part, 533 ... Polymer, 600 ... Electron Paper, 601 ... Main body, 602 ... Display unit, 800 ... Display, 801 ... Main body, 802a ... Conveying roller pair, 802b ... Conveying roller pair, 803 ... Hole, 804 ... Transparent glass plate, 805 ... Insertion port, 806 ... Terminal part, 807 ... 808 ... controller, 809 ... operation unit, 910 ... electrophoretic dispersion liquid, 911 ... counter substrate, 912 ... substrate, 920 ... electrophoretic display device, 921 ... electrophoretic display sheet, 922 ... circuit board, 940 ... partition wall, 9400 ... display layer, 9401 ... pixel space, M 1 _... first monomer, M 2 _... second monomer, M 3 _... third monomer, M 4 _... fourth monomer

Claims (11)

Particles having a first functional group reactive with an isocyanate group on the surface;
A first compound and a second compound bonded to the particles;
The first compound has reactivity with the first functional group and the dispersion part derived from the first monomer having a site contributing to dispersibility in a dispersion medium, and is different from the isocyanate group. A block copolymer having a bonding portion derived from a second monomer having a second functional group, wherein the first functional group and the second functional group react with each other in the bonding portion, so that the particles Connected to
The second compound has a molecular weight smaller than that of the first compound, has a polar group or a nonpolar group, and the isocyanate group, and the isocyanate group reacts with the first functional group. Electrophoretic particles characterized in that the electrophoretic particles are connected to the particles.   2. The electrophoretic particle according to claim 1, wherein the second compound is a silane coupling agent having the nonpolar group and the isocyanate group.   The electrophoretic particle according to claim 1, wherein the first functional group is a hydroxyl group, and the second functional group is an alkoxysilyl group.   The electrophoretic particle according to claim 1, wherein the nonpolar group is a hydrocarbon group.   5. The electrophoretic particle according to claim 1, wherein the molecular weight of the second compound is 100 or more and 1,000 or less.   6. The A / B is 10 or more and 1,000 or less, where A is the weight average molecular weight of the dispersion and B is the molecular weight of the second compound. Electrophoretic particles. A method for producing electrophoretic particles according to any one of claims 1 to 6,
Reacting the first functional group with the second functional group to link the first compound to the particles at the binding portion;
A method for producing electrophoretic particles, comprising: reacting the first functional group with the isocyanate group to link the second compound to the particles.   An electrophoretic dispersion liquid comprising the electrophoretic particles according to any one of claims 1 to 6 and a dispersion medium. A substrate,
An electrophoretic sheet comprising the structure provided on the substrate and containing the electrophoretic dispersion liquid according to claim 8, and the electrophoretic dispersion liquid.   An electrophoretic apparatus comprising the electrophoretic sheet according to claim 9.   An electronic apparatus comprising the electrophoresis apparatus according to claim 10.

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