JP6851226B2 - Electrophoretic particles, methods for producing electrophoretic particles, electrophoretic dispersions, electrophoretic sheets, electrophoretic devices and electronic devices - Google Patents

Description

In general, 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, and in recent years, an electrophoresis display device that uses this electrophoresis to display desired information (image) has been attracting attention as a new display device.

This electrophoresis display device has features such as display memory and wide viewing angle when voltage application is stopped, and high contrast display with low power consumption.

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

Such an electrophoresis display device is known to include an electrophoresis particle dispersed in a solvent as an electrophoresis dispersion liquid arranged between a pair of substrates having electrodes.

In the electrophoresis dispersion liquid having such a configuration, those containing positively charged particles and negatively charged ones are used as the electrophoresis particles, whereby a voltage is applied between the pair of substrates (electrodes). Then, desired information (image) can be displayed.

Here, as the electrophoresis particles 501, those provided with a coating layer 503 in which a polymer 533 is linked to a base particle 502 are generally used (see FIG. 11), and such a coating layer 503 is used. The configuration including (polymer 533) makes it possible to disperse and charge the electrophoresis particles 501 in the electrophoresis dispersion liquid.

Further, the electrophoretic particles having such a constitution are produced, for example, by using atom transfer radical polymerization (ATRP) as follows.

That is, after the base material particles 502 are prepared and a silane coupling agent 531 having a polymerization initiating group is bonded to the surface of the base material particles 502, the monomer is polymerized by living radical polymerization starting from this polymerization initiating group. By forming the polymerized portion 532 and providing the polymer (polymer) 533, the electrophoresis 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, whether the electrophoretic particle 501 has a positive charge property or a negative charge property is because the base particle 502 has a charge property peculiar to itself. By appropriately selecting the type of the base particle 502, the chargeability of the electrophoretic particle 501 can be made desired.

However, in the electrophoresis display device, for example, in order to set the electrophoresis speed of the electrophoresis particles 501 to an appropriate rate, it is necessary to control the charge amount of the electrophoresis particles 501, but it is simply higher than that of the substrate particles 502. It was difficult to control the charge amount of the electrophoretic particles 501 within an appropriate range only by providing the molecule 533.

Japanese Unexamined Patent Publication No. 2013-156381

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

Such an object is achieved by the following invention.
The electrophoretic particles of the present invention include particles having a first functional group reactive with an isocyanate group on the surface thereof.
It has a first compound and a second compound bound to the particles.
The first compound is different from the isocyanate group because it has reactivity with the first functional group and the dispersion part derived from the first monomer having a site that contributes to dispersibility in the dispersion medium. It is a block copolymer having a bond portion derived from a second monomer having a second functional group, and the particles are formed by reacting the first functional group with the second functional group at the bond portion. Is connected to
The second compound has a smaller molecular weight than the first compound and has a polar group or a non-polar group and the isocyanate group, and the isocyanate group reacts with the first functional group. This is characterized by being connected to the particles.

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

In the electrophoresis particles of the present invention, the second compound is preferably a silane-based coupling agent having the non-polar group and the isocyanate group.

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

In the electrophoresis particles 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. Further, the hydroxyl group and the isocyanate group show particularly excellent reactivity, and a chemical bond can be surely 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.

In addition, the first compound having an alkoxysilyl group can be prepared relatively easily. Furthermore, since the hydroxyl group and the alkoxysilyl group show excellent reactivity and a chemical bond can be formed between them, the first compound can be linked to the surface of the mother particle with a high coverage. Is preferably used.

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

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

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

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

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

The method for producing electrophoretic particles of the present invention is a method for producing electrophoretic particles of the present invention.
A step of linking the first compound to the particles at the bonding portion by reacting the first functional group with the second functional group.
It is characterized by having a step of linking 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 a uniform dispersibility in the electrophoretic dispersion and having a charge amount set in an appropriate range.

The electrophoresis dispersion liquid of the present invention is characterized by containing the electrophoresis particles of the present invention and a dispersion medium.

As a result, it is possible to obtain an electrophoretic dispersion liquid having a uniform dispersing ability and having electrophoretic particles in which the amount of charge is set in an appropriate range.

The electrophoresis sheet of the present invention has a substrate and
It is characterized by including a structure provided on the substrate and accommodating the electrophoresis dispersion liquid of the present invention and the electrophoresis dispersion liquid.
As a result, an electrophoresis sheet with high performance and reliability can be obtained.

The electrophoresis apparatus of the present invention is characterized by comprising the electrophoresis sheet of the present invention.
As a result, an electrophoresis device with high performance and reliability can be obtained.

The electronic device of the present invention is characterized by comprising the electrophoresis apparatus of the present invention.
As a result, an electronic device having high performance and reliability can be obtained.

It is a vertical sectional view which shows the 1st Embodiment of the electrophoretic particle of this invention. It is a schematic diagram of the 1st compound and the 2nd compound which the 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 process order. It is a schematic diagram of the 1st compound and the 2nd compound which the 2nd Embodiment of the electrophoretic particle of this invention has. It is a figure which shows typically the vertical cross section of the embodiment of an electrophoresis display device. It is a schematic diagram which shows the operating principle of the electrophoresis display apparatus shown in FIG. It is a schematic diagram which shows the operating principle of the electrophoresis display apparatus shown in FIG. It is a perspective view which shows the embodiment when the electronic device of this invention is applied to electronic paper. It is sectional drawing which shows the embodiment when the electronic device of this invention is applied to a display. It is a top view which shows the embodiment when the electronic device of this invention is applied to a display. It is a figure which shows typically the vertical cross section of the structure in the conventional electrophoretic particle.

Hereinafter, the electrophoresis particles of the present invention, the method for producing the electrophoresis particles, the electrophoresis dispersion liquid, the electrophoresis sheet, the electrophoresis apparatus and the electronic device will be described in detail based on the 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 vertical sectional view showing a first embodiment of the electrophoretic particles of the present invention, and FIG. 2 is a schematic view of a first compound and a second compound contained in the first embodiment of the electrophoretic particles of the present invention. Is.

The electrophoresis 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 particle 2, for example, at least one of pigment particles, resin particles, and composite particles thereof is preferably used. These particles are easy to produce.

Examples of the pigment 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 flower and silicon dioxide, monoazo and disuazo. , Azo pigments such as polyazo, yellow pigments such as isoindolinone, yellow lead, yellow iron oxide, cadmium yellow, titanium yellow, antimon, azo pigments such as monoazo, disazo, polyazo, quinacridone red, chrome vermilion, etc. Examples thereof include red pigments, blue pigments such as phthalocyanine blue, induslen blue, navy blue, ultramarine blue and cobalt blue, and green pigments such as phthalocyanine green, and one or more of these can be used in combination.

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 may be combined. Can be used.

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

By appropriately selecting the types of pigment particles, resin particles, and composite particles used as the mother particles 2, the color of the electrophoresis particles 1 can be set to a desired one.

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

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

The first functional group capable of reacting with the isocyanate group contained 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 may be combined. However, 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, respectively. Further, since the hydroxyl group and the isocyanate group show particularly excellent reactivity and a chemical bond can be surely formed between them, the second compound 37 is coated on the surface of the mother particle 2 with a particularly high coverage. It is preferably used because it can be linked.

Further, the first compound 39, which will be 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 of the above include an alkoxysilyl group, an epoxy group, a glycidyl group, an oxetane group and the like, and one or a combination of two or more of these can be used. Among them, the alkoxysilyl group is used. Is preferable. The first compound 39 having an alkoxysilyl group can be prepared relatively easily. Further, since the hydroxyl group and the alkoxysilyl group show excellent reactivity and a chemical bond can be formed between them, the first compound 39 is linked to the surface of the mother particle 2 with a high coverage. It is preferably used because it can be 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 (almost the entire surface in the illustrated configuration) is covered with the coating layer 3.

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

The second compound 37 has a polar group or a non-polar group and an isocyanate group. In the following, the second compound 37 is a silane cup having a non-polar group and an isocyanate group. A case where the ring agent is used will be described. A silane-based coupling agent having an isocyanate group can be prepared (obtained) relatively easily, and is firmly (stable) bonded to the surface of the mother particle 2, and further has a non-polar group. As a result, the charge amount of the electrophoretic particle 1 can be easily adjusted, and therefore, it is preferably used as the second compound 37.

First, among 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 (hereinafter, also simply referred to as “monomer M ₁ ”) having a site (group) that contributes to dispersibility in a dispersion medium, and a first compound 39. 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 the functional group of 1 (hereinafter, also simply referred to as “monomer M _2”). Then, in the bonding portion 31, the first functional group and the second functional group react with each other to be linked to the mother particle 2.

By making the first compound 39 have such a constitution, dispersibility is imparted to the dispersion portion 32 composed of the unit derived from the _{monomer M 1 (hereinafter, also referred to as a dispersion unit), and the monomer M 2 is provided with dispersibility.} It is connected to the mother particle 2 by a bonding portion 31 composed of a derived unit (hereinafter, also referred to as a bonding unit). Therefore, the electrophoretic particle 1 provided with the first compound 39 having such a constitution can exhibit a uniform dispersing ability in the electrophoretic dispersion liquid.

The first compound 39 is obtained by linking a dispersion portion 32 in which _{the first monomer M 1} is polymerized and a bonding portion 31 in which _{the second monomer M 2 is polymerized.} 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 bond portion 31 of the first compound 39, the mother particle 2 and the first compound 39 are chemically reacted by the reaction of the hydroxyl group as the first functional group and the alkoxysilyl group as the second functional group. Are combined.

Hereinafter, the dispersion portion 32 and the binding portion 31 constituting the first compound 39 will be described.

The dispersion unit 32 is provided on the surface of the mother particles 2 in the coating layer 3 in order to impart dispersibility to the electrophoresis particles 1 in the electrophoresis dispersion liquid described later.

The distribution unit 32, in the electrophoretic dispersion, a polymerization unit of a monomer M ₁ is formed by a plurality polymerization has a portion serving as a contributing side chains dispersibility in a dispersion medium, a monomer M ₁ A plurality of dispersion units derived from are connected.

Monomer M ₁ is a pendant-type monofunctional monomer having one polymerization group so that it can be polymerized by living radical polymerization (radical polymerization), and further having a site which becomes a nonionic side chain after polymerization.

As monomer M _1, by using those with a non-ionic side chain, dispersing section 32 which is formed by living radical polymerization, the dispersion medium contained in the electrophoretic dispersion liquid will be described later, excellent affinity Will be shown. Therefore, in the electrophoresis dispersion liquid, the electrophoresis particles 1 provided with the dispersion portion 32 are dispersed with excellent dispersibility without agglutination.

In addition, examples of the one polymerization group contained in the monomer M ₁ include those containing a carbon-carbon double bond such as a vinyl group, a styryl group, and a (meth) acryloyl group.

Examples of such a monomer M ₁ include a vinyl monomer, a vinyl ester monomer, a vinylamide monomer, a (meth) acrylic monomer, a (meth) acrylic ester monomer, a (meth) acrylamide monomer, a styryl monomer, and the like, and more specific examples thereof. Specifically, 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, isobonyl (meth) acrylate, cyclohexyl (meth) acrylate, pentafluoro (meth) acrylate, silicone macromonomer represented by the following general formula (I), styrene, 2- Methyl styrene, 3-methyl styrene, 4-methyl styrene, 2-ethyl styrene, 3-ethyl styrene, 4-ethyl styrene, 2-propyl styrene, 3-propyl styrene, 4-propyl styrene, 2-isopropyl styrene, 3- Examples thereof include styrene-based monomers such as isopropyl styrene, 4-isopropyl styrene, and 4-tert-butyl styrene, and one or a combination of two or more of these can be used.

［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。］

[In the formula, 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. A structure containing one of the above, n represents an integer of 0 or more. ]

Among these, the monomers M _1, is preferably a silicone macromonomer represented by the above general formula (I). The dispersion portion obtained by polymerizing such a monomer M ₁ exhibits excellent dispersibility with respect to a non-polar dispersion medium. That is, as the dispersion medium contained in the electrophoresis dispersion liquid described later, a dispersion medium containing silicone oil as a main component is preferably used, but even when a hydrocarbon solvent such as this silicone oil is used. Shows excellent affinity for dispersion media. Therefore, the electrophoretic particles 1 provided with the dispersion portion 32 obtained by polymerizing the _{monomer M 1 can be dispersed in the dispersion medium with excellent dispersibility.}

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 more preferably about 5,000 or more and 20,000 or less. As a result, the electrophoretic particles 1 provided with the dispersion portion 32 obtained by polymerizing the _{monomer M 1 can be dispersed in the dispersion medium with better dispersibility.}

The weight average molecular weight of the dispersion portion 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, when _{a silicone macromonomer as represented by the general formula (I) is used as the monomer M 1} , or when a hydrocarbon-based monomer is used, the weight average molecular weight of the dispersion portion 32 is 8,000 or more. It is preferably 50,000 or less, and more preferably 10,000 or more and 35,000 or less. Thereby, the dispersibility of the electrophoretic particle 1 in the electrophoretic dispersion liquid can be made more excellent.

Further, in one polymer, the number of dispersion units contained in the dispersion unit 32 is preferably 1 or more and 20 or less, and more preferably 2 or more and 10 or less. Thereby, the dispersibility of the electrophoretic particle 1 in the electrophoretic dispersion liquid can be surely imparted.

The binding portion 31 is bonded to the surface of the mother particle 2 in the coating layer 3 included in the electrophoresis particle 1, whereby the first compound 39 is linked to the mother particle 2.

In the present embodiment, the bond portion 31 has an alkoxysilyl group as a second functional group capable of reacting with a hydroxyl group provided on the surface of the mother particle 2 as a first functional group to form a covalent bond. It is a polymerization part formed by polymerizing a plurality of the monomers M _{2 of 2} , and a plurality of bonding units (constituent units) derived from the _{monomer M 2 are connected.}

As described above, by using the first compound 39 having the binding portion 31 each having a plurality of binding units each having an alkoxysilyl group as the second functional group, the dispersibility of the electrophoretic particle 1 is further improved. Can be. That is, the first compound 39 not only contains a plurality of alkoxysilyl groups as the second functional group, but also a plurality of alkoxysilyl groups are concentrated in the bond portion 31. Further, since a plurality of binding units are connected to the binding portion 31, the portion capable of reacting with the mother particle 2 is larger than that in the case where there is only one binding unit. Therefore, the first compound 39 can be surely bonded to the surface of the mother particles 2 at the bonding portion 31 formed by polymerizing the _{plurality of monomers M 2.}

In the present embodiment, as described above, the surface of the mother particle ₂ is provided with a hydroxyl group as a first functional group, and the second functional group contained in the monomer M 2 is an alkoxysilyl group. By combining such a hydroxyl group and an alkoxysilyl group, the reaction between them exhibits excellent reactivity, so that the bond to the surface of the mother particle 2 at the bonding portion 31 can be more reliably formed. Can be done.

Such a monomer M ₂ includes one alkoxysilyl group represented by the following general formula (II) as a second functional group, and further comprises one polymerization group so that it can be polymerized by living radical polymerization. It is a thing.

［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 the formula, R independently represents an alkyl group having 1 to 4 carbon atoms, and n represents an integer of 1 to 3 carbon atoms. ]

By using a monomer M ₂ having such a structure, _{it is possible to form a bonding portion 31 in which the monomer M 2} is polymerized by living radical polymerization, and further, the bonding portion 31 formed by living radical polymerization is a mother particle. It exhibits excellent reactivity with the hydroxyl group (first functional group) located on the surface of 2.

Further, as one polymerization group possessed by the monomer M ₂ , as in the monomer M ₁ , for example, those containing a carbon-carbon double bond such as a vinyl group, a styryl group and a (meth) acryloyl group can be mentioned.

Examples of such a monomer M ₂ include a vinyl monomer having one alkoxysilyl group represented by the above general formula (II), a vinyl ester monomer, a vinylamide monomer, a (meth) acrylic monomer, and (meth). Acrylic ester monomer, (meth) acrylamide monomer, styryl monomer and the like can be mentioned, and more specifically, 3- (meth) acryloxipropyltriethoxy (methoxy) silane, vinyltriethoxy (methoxy) silane, 4-vinylbutyl A silane system containing silicon atoms such as triethoxy (methoxy) silane, 8-vinyloctyltriethoxy (methoxy) silane, 10-methacryloyloxydecyltriethoxy (methoxy) silane, and 10-acryloyloxydecyltriethoxy (methoxy) silane. Monomers can be mentioned, and one or a combination of two or more of these can be used.

Further, in one polymer, the number of binding units contained 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 that the connecting portions 31 will react with each other. 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.

The number of binding units contained in the binding portion 31 can be determined by analysis using a general-purpose analytical instrument such as NMR spectrum, IR spectrum, elemental analysis, and gel permeation chromatography (GPC). In the first compound 39, since the binding portion 31 and the dispersion portion 32 are polymer polymers, they both have a certain molecular weight distribution. Therefore, the results of the above analysis do not necessarily apply to all the first compounds 39, but at least if the number of binding units obtained by the above method is 1 to 8, the first compound 39 and the mother It is possible to achieve both the reactivity with the particles 2 and the dispersibility of the electrophoretic particles 1.

Such a first compound 39 is a diblock copolymer in which a binding portion 31 and a dispersion portion 32 are individually provided. Therefore, 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, so that the electrophoretic particle 1 can be provided in the electrophoretic dispersion liquid. , It will exhibit excellent dispersibility.

The first compound 39 can be obtained, for example, by using reversible addition cleavage chain transfer polymerization (RAFT), as described in the production method described below. By using this reversible addition cleavage chain transfer polymerization (RAFT), a relatively uniform polymer can be obtained. Therefore, if 1 to 8 molar equivalents of the monomer M ₂ is added to the chain transfer agent and polymerized, the number of binding units in the binding portion 31 can be within the above range. As a result, the effect can be surely exhibited by configuring the electrophoresis particles 1 to include the first compound 39, and the electrophoresis particles 1 have excellent dispersibility in the electrophoresis dispersion liquid. Become.

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

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

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

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

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

As a method for controlling this charge amount, for example, it is conceivable that the first compound 39 covers the charged region exposed on the surface of the mother particle 2, but the first compound 39 is a block copolymer and its molecular weight. Further, the introduction amount thereof is also set to a certain specified amount in order to impart dispersibility to the electrophoretic particles 1. Therefore, it was impractical to specify the introduction amount of the first compound 39 for the purpose of controlling the charge amount, that is, the migration rate.

On the other hand, in the present invention, in addition to the first compound 39, the mother particle 2 is further provided with a second compound 37 (silane-based coupling agent) having a molecular weight smaller than that of the first compound 39. 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 particles 2, and the introduction amount (linkage amount) thereof can be determined. By setting the amount to, a predetermined region of the charged region exposed on the surface of the mother particle 2 can be covered. Therefore, it is possible to set the charge amount of the electrophoresis particles 1, that is, the migration speed to a desired size. Therefore, by appropriately setting the coating amount of the second compound 37 on the charged region, the electrophoretic particle 1 in which the charged amount is set in an appropriate range can be obtained.

Furthermore, the second compound 37 comprises a non-polar group in this embodiment. Therefore, the charged amount of the electrophoretic particle 1 can be set by adjusting the introduction amount (covered region) of the second compound 37 with respect to the charged region exposed on the surface of the mother particle 2, but the charged region is almost the same. By coating the entire region with the second compound 37, the charge amount of the electrophoretic particle 1 can be set to almost 0, specifically, the ζ potential can be set to less than ± 1 mV. That is, the electrophoretic particles 1 can be uncharged. Further, not only does it not adversely affect the dispersibility and chargeability (charge amount) of the electrophoretic particles 1, but also it is possible to accurately suppress or prevent aggregation of the electrophoretic particles 1 with each other. Such aggregation of the electrophoresis particles 1 is particularly effective with the white particles 95a in which the electrophoresis particles 1 have a negative charge (loading charge) and a positive charge (positive charge), as in the electrophoresis display device 920 described later. ), It is possible to more accurately suppress the aggregation of the white particles 95a having the opposite chargeability and the colored particles 95b.

As described above, in order to impart the non-polar group to suppress or prevent the aggregation of the electrophoretic particles 1 in the electrophoretic dispersion, the second compound 37 is further linked to the surface of the mother particles 2. As a result, it is provided on the surface of the mother particles 2 in the coating layer 3 so that the amount of charge of the electrophoretic particles 1 can be controlled to an uncharged state.

The non-polar group may be any non-polar group and is not particularly limited, but for example, an alkyl group, an aryl group, a cycloalkyl group, a phenyl group, an alkenyl group, an aralkyl group, a cycloalkenyl group, etc. Examples thereof include a hydrocarbon group such as an alkynyl group, an aryl ether group, a silyl group, a siroxanyl group, an alkoxy group and the like, and one or a combination of two or more of these can be used. Among them, a hydrocarbon group Is preferable. Since the hydrocarbon group exhibits excellent non-polarity, aggregation of the electrophoretic particles 1 can be more accurately suppressed or prevented.

Further, 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-mentioned effect can be exhibited more remarkably.

The hydrocarbon group preferably has 1 to 20 carbon atoms, and more preferably 1 to 10 carbon atoms. As a result, the second compound 37 can be reliably linked to the region between the first compounds 39 that are linked to the mother particles 2 while exhibiting the function as a non-polar group.

Further, the non-polar group may be linear, branched or cyclic, but is preferably linear. As a result, the steric hindrance of the non-polar group is reduced, and the second compound 37 can be reliably inserted into the region between the first compounds 39 linked to the mother particle 2.

The second compound 37 (silane-based coupling agent) having such a non-polar group and an isocyanate group is, for example, a silane-based compound represented by the following general formula (III) when the non-polar group is D. Coupling agents can be 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 the formula, D represents a non-polar group, R represents an alkyl group having 1 to 4 carbon atoms, and n represents an integer of 1 to 3 carbon atoms. ]

Further, 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. It is preferable to have. As a result, the chance of contact with the hydroxyl group (first functional group) contained in the mother particle 2 becomes larger than in the case where there is only one isocyanate group. Therefore, the second compound 37 can be surely bonded to the surface of the mother particle 2 via a chemical bond formed by the reaction of the isocyanate group and the hydroxyl group.

As shown in the general formula (III), the second compound 37 may be one in which a non-polar group is directly linked to a silicon atom, but inclusions such as a siloxane skeleton are non-silicon atoms. 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. As a result, the steric hindrance of the second compound 37 (silane-based coupling agent) is reduced, and the second compound 37 is reliably inserted in the region between the first compounds 39 linked to the mother particles 2. The second compound 37 can be reliably linked by the mother particles 2 with excellent reactivity of the isocyanate group. As a result, the dispersibility of the electrophoretic particle 1 in the electrophoretic dispersion liquid can be made more excellent while setting the charge amount of the electrophoretic particle 1 in an appropriate range.

Further, when the weight average molecular weight of the dispersion portion 32 is A and the molecular weight of the second compound 37 is B, the A / B is preferably 10 or more and 1,000 or less, and 50 or more and 500 or less. Is more preferable. As a result, the effect can be exerted more remarkably.

The amount of the second compound 37 added to the electrophoretic particle 1 is preferably 0.1 wt% or more and 3.0 wt% or less, and 0.3 wt% or more and 2.5 wt% or less with respect to the mother particle 2. Is more preferable. As a result, the effect can be exerted more remarkably.

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

In the present embodiment, the case where the second compound 37 has a non-polar group has been described from the viewpoint that the amount of charge of the electrophoretic particle 1 can be easily controlled, but the case is not limited to this case. Compound 37 of 2 may have a polar group. For example, when the mother particle 2 exhibits negative charge and the electrophoretic particle 1 is uncharged, by using a particle having a positive charge group (positive electrode group) with the second compound 37 as a polar group. By connecting a relatively small amount of the second compound 37 to the surface of the mother particle 2, the electrophoretic particle 1 can be decharged. Further, when the mother particle 2 exhibits positive charge and the electrophoretic particle 1 is uncharged, a particle having a negative charge group (negative electrode group) with the second compound 37 as a polar group is used. By connecting a relatively small amount of the second compound 37 to the surface of the mother particle 2, the electrophoretic particle 1 can be decharged. Examples of the negatively charged group include a sulfone group and a carboxyl group, and examples of the positively charged group include amines and salts thereof, quaternary ammonium salts and the like.

As described above, the electrophoresis 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 electrophoresis particle of the present invention. It can be applied and manufactured as follows.

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

In the present embodiment, the method for producing the electrophoresis particles 1 is a step of obtaining a first compound 39 in which the bonding portion 31 and the dispersion portion 32 are linked by using _{the monomer M 1} and the monomer M _{2 by living polymerization.} , The first compound 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. A second step of connecting 39 to the mother particle 2 at the bonding portion 31 and a reaction of the first functional group provided on the surface of the mother particle 2 with the isocyanate group of the second compound 37 are carried out. It has a step of connecting the compound 37 of the above to the mother particle 2 to form the coating layer 3.

In the step of obtaining the first compound 39, 1) _{a dispersion portion 32 in which the first monomer M 1} is polymerized is formed by living radical polymerization using a polymerization initiator, and then a second functional group having a second functional group is formed. The bonding portion 31 in which the monomer M2 of ₂ is polymerized may be formed, or 2) the bonding portion 31 and the dispersion portion 32 may be formed in this order. Here, a plurality of bonding portions 31 may be formed by the method of 1). The case where the first compound 39 is formed will be described.

Hereinafter, each step will be described in detail.
[1] First, a plurality of first compounds 39 in which the dispersion portion 32 and the binding portion 31 are linked are produced (first step; S1).

[1-1] First, a dispersion portion 32 in which _{the first monomer M 1} is polymerized is formed by living polymerization using a polymerization initiator.

Examples of this living polymerization method include living radical polymerization, living cationic polymerization, living anionic polymerization and the like, and among them, 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.

Examples of the living radical polymerization method include atom transfer radical polymerization (ATRP), nitroxide-mediated radical polymerization (NMP), radical polymerization using organic tellurium (TERP), and reversible addition cleavage chain transfer polymerization (RAFT). However, it is preferable to use reversible addition cleavage chain transfer polymerization (RAFT). According to reversible addition-fragmentation chain transfer polymerization (RAFT), there is no fear of metal contamination without using a metal catalyst, further, it is possible to proceed easily polymerized during the polymerization of the monomers M _1.

The polymerization initiator (radical polymerization initiator) is not particularly limited, and is, for example, 2,2'-azobisisobutyronitrile (AIBN) and 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-based 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.

Further, in the case of reversible addition cleavage chain transfer polymerization (RAFT), 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 a combination of two or more of these can be used. These compounds are preferably used because they are relatively easily available and the reaction can be easily controlled.

Further, when reversible addition cleavage chain transfer polymerization (RAFT) is used, the ratio of the monomer M ₁ , the polymerization initiator, and the chain transfer agent is the degree of polymerization of the dispersion portion 32 to be formed and the reactivity of the compound such as the _{monomer M 1.} However, it is preferable that these molar ratios are monomer: polymerization initiator: chain transfer agent = 500 to 5: 5 to 0.25: 1. Thereby, the length (degree of polymerization) of the dispersion portion 32 obtained by polymerizing the _{monomer M 1 can be set to an 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 Examples include ethers such as diethyl ether and tetrahydrofuran, esters such as ethyl acetate, halogenated aromatic hydrocarbons such as chlorobenzene and o-dichlorobenzene, and the like, which can be used alone or as a mixed solvent. ..

Further, it is preferable that the solution (reaction solution) is deoxidized before starting the polymerization reaction. Examples of the deoxidizing treatment include replacement after vacuum degassing with an inert gas such as argon gas and nitrogen gas, and purging treatment.

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 within the above range.

When reversible additional cleavage chain transfer polymerization (RAFT) is used, a fragment of the chain transfer agent used is present at one end (tip portion) of the dispersion portion 32. Then, the dispersion portion 32 including this fragment acts as a chain transfer agent in the reaction of polymerizing the binding portion 31 on the dispersion portion 32 in the next step [1-2].

[1-2] Next, a second having a second functional group (alkoxysilyl group) that is reactive with the first functional group (hydroxyl group) contained in the mother particle 2 so as to be connected to the dispersion portion 32. The monomer M ₂ forms a polymerized bond 31.

As a result, a first compound 39 composed of a diblock copolymer in which the dispersion portion 32 and the binding portion 31 are linked is produced.

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], Purification treatment (removal treatment) may be performed to remove impurities such as a polymerization initiator and isolate and purify the dispersion portion 32. As a result, the first compound 39 obtained in this step [1-2] becomes more uniform and has 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 a combination of two or more of these can be used.

Further, as described above, when reversible additional cleavage chain transfer polymerization (RAFT) is used, a fragment of the chain transfer agent used 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, a plurality of first functional groups contained in the mother particle 2 are reacted with a plurality of second functional groups possessed by the bonding portion 31 to form a chemical bond between them. The first compound 39 of the above is linked to the mother particle 2 (second step; S2).

Examples of such a process include the dry method and the wet method shown below.
<< Dry method >>
In the dry method, first, the first compound 39 and the mother particles 2 are mixed in an appropriate solvent to prepare a solution. In addition, in order to promote the hydrolysis of the alkoxysilyl group (second functional group) contained in the first compound 39, a trace amount of water, acid or base may be added to the solution as needed. Moreover, heating, light irradiation and the like may be performed 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 particles 2. .. As a result, the contact opportunity of the first compound 39 with respect to the mother particle 2 can be increased, so that the binding portion 31 can be more reliably bonded to the surface of the mother particle 2.

Next, the first compound 39 is highly efficiently adsorbed on the surface of the mother particles 2 by dispersing by ultrasonic irradiation, stirring using a ball mill, a bead mill, or the like, and then the solvent is removed.

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

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

By going through the above steps, 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 particles 2 are mixed in an appropriate solvent to prepare a solution. In addition, in order to promote the hydrolysis of the alkoxysilyl group (second functional group) contained in the first compound 39, a trace amount of water, acid or base may be added to the solution as needed. Moreover, heating, light irradiation and the like may be performed 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 particles 2. .. As a result, the contact opportunity of the first compound 39 with respect to the mother particle 2 can be increased, so that the binding portion 31 can be more reliably bonded to the surface of the mother particle 2.

Next, the first compound 39 is highly efficiently adsorbed on the surface of the mother particles 2 by dispersing by ultrasonic irradiation, stirring using a ball mill, a bead mill, or the like, and then the solution is preferably prepared in this state. By decomposing the alkoxysilyl group by heating at 100 ° C. to 200 ° C. for 1 hour or more, a chemical bond is formed with the hydroxyl group exposed on the surface of the mother particle 2 to form the first compound 39 into the mother particle 2. Can be linked to.

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

[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, and these are reacted with 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 by using various known methods.
Further, as the process of connecting the second compound 37 to the mother particle 2, the dry method and the wet method described in the above step [2] are used in the same manner as the process of connecting the first compound 39 to the mother particle 2. Be done.

When the second compound 37 is linked to the mother particle 2, since the second compound 37 has an isocyanate group, the hydroxyl group provided by the mother particle 2 as the first functional group is particularly opposed. Shows 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 linked to the surface of the mother particle 2 with a particularly high coverage.

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

By going through the above steps, the electrophoretic particle 1 of the present invention can be obtained in a purified state.

Depending on the type of monomer M ₁ included in the first compound 39, there is a case where the electrophoretic particles 1 thus dried not dispersed in the dispersion solvent. In such a case, it is preferable to carry out the washing operation by a solvent replacement method in which the reaction solvent is gradually replaced with a dispersion solvent (without going through a drying step).

Further, as the solvent used in this step, the same solvent as that mentioned in the above step [1-1] can be used, and the aliphatic hydrocarbons listed as the dispersion liquid provided in the electrophoresis dispersion liquid described 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 view of the first compound and the second compound contained in the second embodiment of the electrophoretic particles of the present invention.

Hereinafter, the electrophoretic particles of the second embodiment will be described mainly on the differences from the electrophoretic particles of the first embodiment, and the same matters will be omitted.

As shown in FIG. 4, the electrophoretic particle 1 of the present embodiment is shown in FIG. 2 except that the composition of the second compound among the first compound and the second compound bound to the mother particle 2 is different. It is the same as the electrophoretic particle 1 of the first embodiment shown.

That is, in the electrophoresis particles 1 of the second embodiment, the second compound 38 is linked instead of the second compound 37, and the second compound 38 is a third monomer having a non-polar group. It is a block copolymer having a non-polar portion 33 derived from M ₃ and a binding 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 particles 2 by the reaction of the first functional group (hydroxyl group) and the isocyanate group at the bonding portion 34.

The non-polar portion 33 contained in the second compound 38 causes the electrophoresis particles 1 to aggregate with each other in the electrophoresis dispersion liquid described later, similarly to the non-polar group contained in the second compound 37 of the first embodiment. It is provided on the surface of the mother particle 2 in the coating layer 3 in order to suppress or prevent the addition.

In the non-polar portion 33, after polymerization, a plurality of _{monomers M 3} having a site in which the non-polar group contained in the second compound 37 of the first embodiment becomes a side chain are polymerized in the electrophoresis dispersion liquid. is formed, a non-polar units derived from the monomer M ₃ is multiple linked.

Monomer M ₃ is a pendant-type monofunctional monomer having one polymerization group so that it can be polymerized by living radical polymerization (radical polymerization), and further having a site which becomes a non-polar side chain after polymerization.

As monomers M _3, by using those with a non-polar side chain of a non-polar portion 33 which is formed by living radical polymerization, in the electrophoretic dispersion liquid will be described later, inhibit or prevent aggregation of the electrophoretic particles 1 Demonstrate the function to be performed. Therefore, in the electrophoresis dispersion liquid, the electrophoresis particles 1 provided with the non-polar portion 33 are dispersed with excellent dispersibility without agglutination.

As such a monomer M ₃ , a side chain having a non-polar group contained in the second compound 37 described above may be used instead of the side chain contributing to the dispersibility of the monomer M _{1 described above.} it can.

Further, the bonding portion 34 is bonded to the surface of the mother particle 2 in the coating layer 3 included in the electrophoresis particle 1, thereby connecting the second compound 38 to the mother particle 2. As the bonding portion 34, those having the same configuration as that of the bonding portion 31 included in the first compound 39 described above and having an isocyanate group instead of the second functional group (alkoxysilyl group) are used. Can be done.

The same effect as that of the first embodiment can be obtained by the electrophoresis particles of the second embodiment including the second compound 38 composed of the block copolymer having the non-polar portion 33 and the binding portion 34. Be done.

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

The electrophoresis dispersion liquid is formed by dispersing (suspending) at least one kind of electrophoresis particles 1 (electrophoresis particles of the present invention) in a dispersion medium (liquid phase dispersion medium). That is, the electrophoresis dispersion liquid contains the electrophoresis particles 1 and the dispersion medium. Since this electrophoresis dispersion liquid contains the electrophoresis particles 1, the effect of the above-mentioned electrophoresis particles 1 is exhibited, and in the electrophoresis dispersion liquid, the electrophoresis particles 1 have a uniform dispersion ability and. The amount of charge is set in an appropriate range.

As the dispersion medium, one having a boiling point of 100 ° C. or higher and having a relatively high insulating property is preferably used. Examples of such dispersion medium include various types of water (for example, distilled water, pure water, etc.), 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, alicyclic hydrocarbons such as cyclohexane, aromatic hydrocarbons such as xylene, halogenated hydrocarbons such as methylene chloride, aromatic heterocycles such as pyridine, etc. Examples thereof include nitriles such as acetonitrile, amides such as N, N-dimethylformamide, carboxylates, silicone oils and various other oils, and these can be used alone or as a mixture.

Among them, the dispersion medium preferably containing an aliphatic hydrocarbon (liquid paraffin) or silicone oil as a main component. Since the dispersion medium containing liquid paraffin or silicone oil as a main component has a high effect of suppressing aggregation of the electrophoresis particles 1, it is possible to suppress deterioration of the display performance of the electrophoresis display device 920 shown in FIG. 5 over time. Can be done. Further, the liquid paraffin or silicone oil has an advantage that it has excellent weather resistance and is also highly safe because it does not have an unsaturated bond.

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

Further, in the dispersion medium, if necessary, charge control consisting of particles such as an electrolyte, a surfactant (anionic or cationic), a metal soap, a resin material, a rubber material, an oil, a varnish, and a compound. Various additives such as agents, lubricants, stabilizers, and various dyes may be added.

Further, the electrophoresis particles may be dispersed in a dispersion medium by, for example, one or a combination of one or more of a paint shaker method, a ball mill method, a media mill method, an ultrasonic dispersion method, a stirring dispersion method and the like. it can.

In such an electrophoresis dispersion liquid, due to the action of the first compound 39 and the second compound 37 possessed by the coating layer 3, the electrophoresis particles 1 have a uniform dispersion ability and an appropriate charge amount. It will be set in the range.

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

FIG. 5 is a diagram schematically showing a vertical cross section of an embodiment of an electrophoresis display device, and FIGS. 6 and 7 are schematic views showing an operating principle of the electrophoresis display device shown in FIG. In the following, for convenience of explanation, the upper side in FIGS. 5 to 7 will be referred to as “upper” and the lower side will be referred to as “lower”.

The electrophoresis display device 920 shown in FIG. 5 includes an electrophoresis display sheet (front plane) 921, a circuit board (backplane) 922, an adhesive layer 98 for joining the electrophoresis display sheet 921 and the circuit board 922, and an adhesive layer 98. It has a sealing portion 97 that airtightly seals the gap between the electrophoresis display sheet 921 and the circuit board 922.

The electrophoresis display sheet (electrophoresis sheet of the present invention) 921 includes a substrate 912 including a flat base portion 92 and a second electrode 94 provided on the lower surface of the base portion 92, and a lower surface (one surface) of the substrate 912. ) Side, it has a partition wall 940 (a plurality of structures) formed in a matrix and a display layer 9400 composed of an electrophoresis dispersion liquid 910. In the display layer 9400, the electrophoresis dispersion liquid 910 is housed in a plurality of pixel spaces 9401 defined by the partition wall 940.

On the other hand, the circuit board 922 is provided on a counter substrate 911 having a flat plate-shaped 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. It has a circuit (not shown) including a switching element such as a TFT, and a drive IC (not shown) for driving the switching element.

Hereinafter, the configuration of each part will be described in sequence.
The base 91 and the base 92 are each composed of sheet-shaped (flat plate-shaped) members, and have a function of supporting and protecting each member arranged between them.

The bases 91 and 92 may be either flexible or rigid, but are preferably flexible. By using the flexible bases 91 and 92, it is possible to obtain a flexible electrophoresis display device 920, that is, an electrophoresis display device 920 useful for constructing, for example, electronic paper.

When the bases (base material layers) 91 and 92 are made flexible, it is preferable that they are each made of a resin material.

The average thickness of the bases 91 and 92 is appropriately set depending on the constituent materials, applications, and the like, and is not particularly limited, but is preferably about 20 to 500 μm, and more preferably about 25 to 250 μm. ..

A layered (film-like) first electrode 93 and a second electrode 94 are provided on the surfaces 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. There is.

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, and the first electrode 93 is an individual electrode (pixel electrode connected to a switching element) divided into a matrix (matrix). The portion where the two electrodes 94 and the one first electrode 93 overlap each other 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 thickness of such electrodes 93 and 94 is appropriately set depending on the constituent materials, applications, and the like, and is not particularly limited, but is preferably about 0.05 to 10 μm, and is preferably about 0.05 to 5 μm. Is more preferable.

Of the bases 91 and 92 and the electrodes 93 and 94, the base and the electrode (in this embodiment, the base 92 and the second electrode 94) arranged on the display surface side have light transmission properties, respectively. The thing, that is, substantially transparent (colorless transparent, colored transparent or translucent).

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

The display layer 9400 has a configuration in which the electrophoresis dispersion liquid (electrophoresis dispersion liquid of the present invention described above) 910 is housed (encapsulated) in a plurality of pixel spaces 9401 defined by the partition wall 940.

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

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. Examples include materials, and one or a combination of two or more of these can be used.

In the present embodiment, the electrophoresis dispersion liquid 910 housed in the pixel space 9401 disperses (suspends) two types (at least one type of electrophoresis particles 1) of colored particles 95b and white particles 95a in a dispersion medium 96. ), And the above-mentioned electrophoresis dispersion of the present invention is applied.

In such an electrophoresis 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 applied according to the electric field generated between them. 1) is electrophoresed toward any of the electrodes.

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

When such electrophoretic particles 1 are used, assuming that the first electrode 93 has a positive potential, as shown in FIG. 6, the colored particles 95b move to the second electrode 94 side and move to the second electrode 94. Gather at 94. On the other hand, the white particles 95a move to the first electrode 93 side and gather at the first electrode 93. Therefore, when the electrophoresis 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 contrary, when the first electrode 93 has a negative potential, as shown in FIG. 7, the colored particles 95b move to the first electrode 93 side and gather at the first electrode 93. On the other hand, the white particles 95a move to the second electrode 94 side and gather at the second electrode 94. Therefore, when the electrophoresis display device 920 is viewed from above (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 provided by appropriately setting the charge amounts 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. Desired information (image) is displayed on the display surface side of the 920 according to the color combination of the white particles 95a and the colored particles 95b, the number of particles aggregated on the electrodes 93 and 94, and the like.

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

Further, it is preferable that the specific gravity of the electrophoresis particles 1 is set to be substantially equal to the specific gravity of the dispersion medium 96. As a result, the electrophoretic particles 1 can stay at a fixed position in the dispersion medium 96 for a long time even after the application of the voltage between the electrodes 93 and 94 is stopped. That is, the information displayed on the electrophoresis display device 920 is retained for a long time.

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

In the present embodiment, the electrophoresis display sheet 921 and the circuit board 922 are joined via the adhesive layer 98. As a result, the electrophoresis 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 91 and the base 92 along the edges thereof. The electrodes 93 and 94, the display layer 9400, and the adhesive layer 98 are airtightly sealed by the sealing portion 97. As a result, it is possible to prevent the infiltration of water into the electrophoresis display device 920 and more reliably prevent deterioration of the display performance of the electrophoresis display device 920.

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

In the present embodiment, in the electrophoresis display device 920, the white particles 95a and the colored particles (black particles) 95b to which the electrophoresis particles 1 are applied are prepared as loaded electric particles and positively charged particles, respectively. The electrophoresis display device 920 is intended to display black and white in a two-particle system, but the electrophoresis display device 920 is not limited to those having such a configuration, and the white particles 95a and the colored particles (black particles) 95b are used. It may be a two-particle system black-and-white display including uncharged and positive or loaded electric particles, respectively, and further, it may be uncharged as white particles 95a, black particles, and color particles other than black, respectively. , A three-particle system including one with a load electric charge and one with a positive charge may be displayed in color.

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

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

FIG. 8 is a perspective view showing an embodiment when the electronic device of the present invention is applied to electronic paper.
The electronic paper 600 shown in FIG. 8 includes a main body 601 made 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 is composed of the electrophoresis display device 920 as described above, whereby the electronic paper 600 has high performance and reliability.

<< Display >>
Next, an embodiment when the electronic device 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 an embodiment when the electronic device of the present invention is applied to a display.

The display (display device) 800 shown in FIGS. 9 and 10 includes a main body 801 and an electronic paper 600 detachably provided 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 is formed on the side portion (right side in FIG. 9), and two sets of transport roller pairs 802a and 802b are provided inside. When the electronic paper 600 is inserted into the main body 801 via the insertion port 805, the electronic paper 600 is installed in the main body 801 in a state of being sandwiched by the transport roller pairs 802a and 802b.

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

Further, a terminal portion 806 is provided at the tip end portion (left side in FIG. 9) of the electronic paper 600 in the insertion direction, and a terminal portion is provided inside the main body portion 801 with the electronic paper 600 installed in the main body portion 801. A socket 807 to which the portion 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 in a state of being removed from the main body 801.

Further, in such a display 800, the electronic paper 600 is composed of the electrophoresis display device 920 as described above, whereby the electronic paper 600 has high performance and reliability.

The electronic device of the present invention is not limited to the above applications, 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 organizers, calculators, electronic newspapers, word processors, personal computers, workstations, videophones, POS terminals, devices equipped with touch panels, etc., and the display unit of these various electronic devices includes an electrophoretic display device 920. Can be applied.

The electrophoresis particles of the present invention, the method for producing the electrophoresis particles, the electrophoresis dispersion liquid, the electrophoresis sheet, the electrophoresis apparatus and the electronic device have been described above based on the illustrated embodiments, but the present invention is limited thereto. The configuration of each part can be replaced with an arbitrary configuration having a similar function. Further, any other constituents may be added to the present invention.

Further, in the method for producing electrophoretic particles of the present invention, one or two or more steps of arbitrary purpose may be added.

Next, specific examples of the present invention will be described.
Production of electrophoresis particles, preparation of electrophoresis dispersion, evaluation of electrophoresis dispersion 1. Synthesis of the first compound (block copolymer) 1-1. Synthesis of dispersion 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 : 100 mg was added, the system was replaced with nitrogen, 22.5 mL of ethyl acetate was further added, and then the mixture was heated and stirred at 75 ° C. for 8 hours to polymerize the silicone macromonomer. This was cooled to room temperature to terminate the reaction, and the solvent was removed to obtain a silicone polymer reaction solution.

The obtained reaction solution was purified on a silica gel column using a mixed solvent of hexane and chloroform as a developing solvent to remove impurities, and a silicone polymer was isolated. 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 bond part In a flask, the silicone polymer obtained above: 10 g, azobisisobutyronitrile: 27.5 mg, 3-methacryloxypropyltriethoxysilane (manufactured by Shinetsu Silicone Co., Ltd., "KBE-503"): After 200 mg was added and the system was replaced with nitrogen, ethyl acetate was further added, and then the polymerization was carried out by heating and stirring at 75 ° C. for 4 hours. This was cooled to room temperature to terminate the reaction, and the solvent was removed to obtain a first compound (block copolymer) in which the dispersion part and the bonding part were linked.

2. Preparation of Electrophoretic Dispersion Solution Containing White Particles (Polarly Charged Particles) [Example 1A]
To the flask, add 10 g of the first compound (block copolymer) obtained above and 60 g of titania particles (“CR50” manufactured by Ishihara Sangyo Co., Ltd.) to silicone oil (“KF-96-20cs” manufactured by Shinetsu Chemical Co., Ltd.). After sonication for 1 hour, the first compound was bound to the particles by heating and stirring at 180 ° C. for 8 hours.

Then, as a second compound, 1.8 g of methyl triisocyanate silane (manufactured by Matsumoto Fine Chemical Co., Ltd., “Organix SI-310”, Mw: 169) (charged amount of 3 wt% with respect to 60 g of titania particles) was added, and 1 After sonication for hours, the mixture was heated and stirred at 130 ° C. for 4 hours to bond the second compound to the particles to obtain electrophoresis particles. The 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 Co., Ltd. to obtain an electrophoretic dispersion containing white particles.

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

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

The addition amounts of the first compound and the second compound in the obtained electrophoretic particles were 2.5 wt% and 1.5 wt%, respectively, with respect to the titania particles.

[Example 3A]
As the second compound, 0.9 g of methyl triisocyanate silane (charged amount 1.5 wt% with respect to 60 g of titania particles) was added, ultrasonically treated for 1 hour, and then heated and stirred at 130 ° C. for 4 hours to obtain the second compound. An electrophoresis dispersion containing white particles was obtained in the same manner as in Example 1A, except that the compound (methyltriisocyanate sisilane) was bound to the particles.

The addition amounts of the first compound and the second compound in the obtained electrophoretic particles were 2.5 wt% and 1.0 wt% with respect to the titania particles, respectively.

[Reference Example 1A]
As the second compound, 1.8 g of n-butyltrimethoxysilane (charged amount 3 wt% with respect to 60 g of titania particles) (manufactured by Gelest, Mw: 178.3) was added in place of methyl triisocyanate silane, and ultrasonic treatment was performed for 1 hour. After that, electrophoresis containing white particles was carried out in the same manner as in Example 1A, except that the second compound (n-butyltrimethoxysilane) was bound to the particles by heating and stirring at 130 ° C. for 4 hours. A dispersion was obtained.

The addition amounts of the first compound and the second compound in the obtained electrophoretic particles were 2.5 wt% and 0.5 wt%, respectively, with respect to the titania particles.

[Reference Example 2A]
As the second compound, n-butyltrimethoxysilane: 3.0 g (charged amount 5 wt% with respect to 60 g of titania particles) was added instead of methyltriisocyanatesilane, ultrasonically treated for 1 hour, and then heated at 130 ° C. for 4 hours. An electrophoresis dispersion containing white particles was obtained in the same manner as in Example 1A, except that the second compound (n-butyltrimethoxysilane) was bound to the particles by stirring.

The addition amounts of the first compound and the second compound in the obtained electrophoretic particles were 2.5 wt% and 1.0 wt% with respect to the titania particles, respectively.

[Reference Example 3A]
As the second compound, 6.0 g of n-butyltrimethoxysilane (charged amount 10 wt% with respect to 60 g of titania particles) was added in place of methyltriisocyanatesilane, ultrasonically treated for 1 hour, and then heated at 130 ° C. for 4 hours. An electrophoresis dispersion containing white particles was obtained in the same manner as in Example 1A, except that the second compound (n-butyltrimethoxysilane) was bound to the particles by stirring.

The addition amounts of the first compound and the second compound in the obtained electrophoretic particles were 2.5 wt% and 1.0 wt% with respect to the titania particles, respectively.

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

3. 3. Preparation of Electrophoretic Dispersion Solution Containing Black Particles (Negatively Charged Particles) [Example 1B]
An electrophoretic dispersion containing black particles was obtained in the same manner as in Example 1A, except that 60 g of titanium nitride particles (“SC13MT” manufactured by Mitsubishi Materials Corporation) was added to the flask in place of the 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%, respectively, with respect to the titanium nitride particles.

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

The addition amounts of the first compound and the second compound in the obtained electrophoretic particles were 2.3 wt% and 1.5 wt%, respectively, with respect to the titanium nitride particles.

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

The addition amounts of the first compound and the second compound in the obtained electrophoretic particles were 2.3 wt% and 1.0 wt%, respectively, with respect to the titanium nitride particles.

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

The addition amounts of the first compound and the second compound in the obtained electrophoretic particles were 2.3 wt% and 0.5 wt%, respectively, with respect to the titanium nitride particles.

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

The addition amounts of the first compound and the second compound in the obtained electrophoretic particles were 2.3 wt% and 1.0 wt%, respectively, with respect to the titanium nitride particles.

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

The addition amounts of the first compound and the second compound in the obtained electrophoretic particles were 2.3 wt% and 1.0 wt%, respectively, with respect to the titanium nitride particles.

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

4. Preparation of Electrophoretic Dispersant Containing White Particles and Black Particles About the electrophoretic dispersion liquid containing white particles of Example 1A and the electrophoretic dispersion liquid containing black particles of Examples 2B and 3B and Reference Examples 1B to 3B. , And the electrophoretic dispersion containing the white particles of Reference Example 1A and Comparative Example 1A, and the electrophoresis dispersion containing the black particles of Reference Example 1B, each of which is white in combination with the white particles and the black particles. The electrophoresis dispersion and the black electrophoresis dispersion were mixed so as to have a volume ratio of 10: 1 to prepare an electrophoresis dispersion containing white particles and black particles.

5. Evaluation of Electrophoretic Dispersion Solution 5-1. First, the above 2. ~ 3. The dispersibility and mobility of the electrophoretic dispersion prepared in the above were evaluated as follows, respectively.

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

Next, the electrophoresis dispersion was diluted so that the content of the electrophoresis particles was 1 wt%, and then the diluted electrophoresis dispersion was dropped onto the comb tooth electrode of the evaluation comb tooth electrode substrate.
Then, the dropped electrophoresis dispersion was observed using a microscope.

The results were evaluated based on the evaluation criteria shown below.
<< Evaluation Criteria >>
⊚: No aggregation of the electrophoresis particles was observed in the electrophoresis dispersion, and the electrophoresis particles were uniformly spread in the electrophoresis dispersion.
◯: Some agglutination of electrophoretic particles is observed in the electrophoretic dispersion.
Δ: Agglutination of some electrophoretic particles is observed in the electrophoretic dispersion.
X: A large number of agglutination 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”). As a measuring method, first, 10 g of an electrophoresis dispersion containing white particles or an electrophoresis dispersion containing black particles prepared to a concentration of 20 wt% is prepared in a 30 ml beaker. Next, the colloidal oscillating current was detected by immersing this electrophoresis dispersion in the zeta potential probe, and the ζ potential was obtained from this current value. The average value of the results of a total of 5 measurements was determined as the measured value.
The evaluation results are shown in Tables 1 and 2.

As is clear from Tables 1 and 2, in the electrophoresis dispersion of each example, the amount of the second compound charged is smaller than that of the electrophoresis dispersion of each reference, and the second compound is densely charged. The electrophoretic particles into which the compound was introduced were dispersed, and the results showing excellent dispersibility were obtained.

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

5-2. In addition, the above 4. The following display performance, power consumption, and retention were evaluated for the electrophoresis dispersion prepared in.

<Display performance>
That is, the above 4. The white reflectance when white was displayed and the black reflectance when black was displayed by injecting them into a transparent electrode cell having a thickness of 50 μm were measured for each of the electrophoresis dispersions prepared in the above, and the contrast was calculated from these. ..

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

<Power consumption>
In addition, the above 4. ^{The power consumption (μJ / cm 2} ) in 1 sec when each of the electrophoresis dispersions prepared in 1 was injected into a transparent electrode cell having a thickness of 50 μm and displayed in black was measured.

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 4. The white reflectance when white was displayed and the black reflectance when black was displayed by injecting them into a transparent electrode cell having a thickness of 50 μm were measured for each of the electrophoresis dispersions prepared in the above, and the contrast was calculated from these. .. Then, the calculation of this contrast was repeated for one week.

The results were evaluated based on the evaluation criteria shown below.
<< Evaluation Criteria >>
◯: The decrease in contrast is within 5 for 1 week or more.
Δ: Contrast decreases by 5 or more within 1 day to 1 week.
X: Contrast decreases by 5 or more within 1 day.
The evaluation results are shown in Table 3.

As is clear from Table 3, Example 1A having white particles having a zeta potential of less than <1.0 mV, Examples 2B and 3B having black particles having a zeta potential of 2.0 to 5.0 mV, and Reference Example 1B. In the electrophoresis dispersion in combination with 2B, the results showing excellent contrast, that is, display performance were obtained due to the excellent dispersibility of the white particles and the excellent migration of the black particles in the electrophoresis dispersion.

On the other hand, in the combination of Example 1A and Reference Example 3B, agglomeration occurs between the black particles due to the excessive amount of the second compound charged in the black particles, resulting in contrast. That is, the result was inferior in display performance. Further, with respect to the combination of Reference Example 1A and Comparative Example 1A and Reference Example 1B, the white particles exhibit mobility due to the small amount of the second compound added to the white particles, and as a result, the contrast, that is, the display is displayed. The result was inferior in performance.

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

1 ... Electrophoretic particles, 2 ... Mother particles, 3 ... Coating layer, 31 ... Bonding part, 32 ... Dispersing part, 33 ... Non-polar part, 34 ... Bonding 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 particles, 503 ... Coating layer, 513 ... Silane coupling agent, 532 ... Polymerization part, 533 ... Polymer, 600 ... Electrons Paper, 601 ... Main body, 602 ... Display unit, 800 ... Display, 801 ... Main body, 802a ... Transfer roller pair, 802b ... Transfer roller pair, 803 ... Hole, 804 ... Transparent glass plate, 805 ... Insertion port, 806 ... Terminal part, 807 ... Socket, 808 ... Controller, 809 ... Operation part, 910 ... Electrophoresis dispersion, 911 ... Opposite substrate, 912 ... Substrate, 920 ... Electrophoresis display device, 921 ... Electrophoresis 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,
It has a first compound and a second compound bound to the particles.
The first compound is different from the isocyanate group because it has reactivity with the first functional group and the dispersion part derived from the first monomer having a site that contributes to dispersibility in the dispersion medium. It is a block copolymer having a bond portion derived from a second monomer having a second functional group, and the particles are formed by reacting the first functional group with the second functional group at the bond portion. Is connected to
The second compound has a smaller molecular weight than the first compound and has a polar group or a non-polar group and the isocyanate group, and the isocyanate group reacts with the first functional group. An electrophoresis particle characterized by being linked to the particle. The electrophoretic particle according to claim 1, wherein the second compound is a silane-based coupling agent having the non-polar group and the isocyanate group. The electrophoretic particle according to claim 1 or 2, wherein the first functional group is a hydroxyl group and the second functional group is an alkoxysilyl group. The electrophoretic particle according to any one of claims 1 to 3, wherein the non-polar group is a hydrocarbon group. The electrophoretic particle according to any one of claims 1 to 4, wherein the molecular weight of the second compound is 100 or more and 1,000 or less. The method according to any one of claims 1 to 5, wherein when the weight average molecular weight of the dispersed portion is A and the molecular weight of the second compound is B, the A / B is 10 or more and 1,000 or less. Electrophoretic particles. The method for producing electrophoretic particles according to any one of claims 1 to 6.
A step of linking the first compound to the particles at the bonding portion by reacting the first functional group with the second functional group.
A method for producing electrophoretic particles, which comprises a step of linking the second compound to the particles by reacting the first functional group with the isocyanate group. An electrophoretic dispersion liquid containing the electrophoretic particles according to any one of claims 1 to 6 and a dispersion medium. With the board
An electrophoresis sheet provided on the substrate and containing the structure for accommodating the electrophoresis dispersion according to claim 8, and the electrophoresis dispersion. An electrophoresis apparatus comprising the electrophoresis sheet according to claim 9. An electronic device comprising the electrophoresis apparatus according to claim 10.

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