JP2015018097A - Electrophoretic dispersion liquid, electrophoretic display sheet, electrophoretic display device, and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophoretic dispersion liquid, an electrophoretic display sheet, an electrophoretic display device, and an electronic apparatus, in which electrophoretic particles can be sufficiently charged and display performance is excellent.SOLUTION: An electrophoretic dispersion liquid 910 includes dispersion media 96 and electrophoretic particles. One of the dispersion media and the electrophoretic particles contains electron donating molecules, and the other of them contains electron accepting molecules. Charge transfer between the electron donating molecules and the electron accepting molecules is performed by π electron transfer. In the electrophoretic dispersion liquid, the electron donating molecules preferably have tetrathiafulvalene skeletons, and also the electron accepting molecules preferably have tetracyanoquinodimethane skeletons.

Description

  The present invention relates to an electrophoretic dispersion, an electrophoretic display sheet, an electrophoretic display device, and an electronic apparatus.

Generally, it is known that when an electric field is applied to a dispersion system in which fine particles are dispersed in a liquid, the fine particles move (migrate) in the liquid by Coulomb force. This phenomenon is called electrophoresis. In recent years, an electrophoretic display device that displays desired information (image) using this electrophoresis has attracted attention as a new display device.
This electrophoretic display device has characteristics such as a display memory property and a wide viewing angle property in a state where voltage application is stopped, and a high-contrast display with low power consumption.

In addition, since the electrophoretic display device is a non-light-emitting device, the electrophoretic display device has a feature that it is easier on the eyes than a light-emitting display device such as a cathode ray tube.
As such an electrophoretic display device, a device in which electrophoretic particles are dispersed in a solvent is provided as an electrophoretic dispersion liquid disposed between a pair of substrates having electrodes (for example, patents). Reference 1).

In the electrophoretic dispersion liquid having such a configuration, the electrophoretic particles include positively charged particles and negatively charged particles, so that a voltage is applied between a pair of substrates (electrodes). Thus, desired information (image) can be displayed.
However, in the conventional electrophoretic dispersion liquid, the electrophoretic particles cannot be sufficiently charged, and it has been difficult to sufficiently enhance the display performance of the electrophoretic display device.

JP 2004-333796 A

  An object of the present invention is to provide an electrophoretic dispersion, an electrophoretic display sheet, an electrophoretic display device, and an electronic apparatus that can sufficiently charge electrophoretic particles and have excellent display performance.

Such an object is achieved by the present invention described below.
The electrophoretic dispersion liquid of the present invention includes a dispersion medium and electrophoretic particles,
One of the dispersion medium and the electrophoretic particles contains an electron donating molecule, and the other contains an electron accepting molecule,
Charge transfer between the electron donating molecule and the electron accepting molecule is performed by movement of π electrons.
Thereby, the electrophoretic particles can be sufficiently charged, and an electrophoretic dispersion liquid having excellent display performance can be provided.

In the electrophoretic dispersion of the present invention, the electron donating molecule preferably has a tetrathiafulvalene skeleton.
Thereby, electrophoretic particles can be charged more greatly.
In the electrophoretic dispersion liquid of the present invention, the electron accepting molecule preferably has a tetracyanoquinodimethane skeleton.
Thereby, electrophoretic particles can be charged more greatly.

In the electrophoretic dispersion of the present invention, the content of the electron donating molecule or the electron accepting molecule contained in the electrophoretic particle is 0.1% by mass or more and 10% by mass or less with respect to the electrophoretic particle. It is preferable that
Thereby, electrophoretic particles can be charged more efficiently.
In the electrophoretic dispersion of the present invention, the content of the electron donating molecule or the electron accepting molecule contained in the dispersion medium is 0.1% by mass or more and 10% by mass or less with respect to the dispersion medium. It is preferable.
Thereby, electrophoretic particles can be charged more efficiently.

In the electrophoretic dispersion of the present invention, the number of molecules of the electron donating molecule or the electron accepting molecule contained in the dispersion medium is X, and the electron donating molecule or the electron contained in the electrophoretic particle. When the number of accepting molecules is Y, it is preferable to satisfy the relationship of X ≧ Y.
Thereby, electrophoretic particles can be more efficiently charged.

The electrophoretic display sheet of the present invention includes a substrate,
And a plurality of structures each of which is disposed above the substrate and houses the electrophoretic dispersion of the present invention.
Thereby, an electrophoretic display sheet excellent in display performance can be provided.
The electrophoretic display device of the present invention includes the electrophoretic display sheet of the present invention.
Thereby, an electrophoretic display device having excellent display performance can be provided.
An electronic apparatus according to the present invention includes the electrophoretic display device according to the present invention.
Thereby, an electronic device having excellent display performance can be provided.

It is a figure which shows typically the longitudinal cross-section of embodiment of an electrophoretic display apparatus. It is a schematic diagram which shows the principle of operation of the electrophoretic display device shown in FIG. It is a perspective view which shows embodiment at the time of applying the electronic device of this invention to electronic paper. It is a figure which shows embodiment at the time of applying the electronic device of this invention to a display.

Hereinafter, an electrophoretic dispersion, an electrophoretic display sheet, an electrophoretic display device, and an electronic apparatus according to the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.
<Electrophoretic dispersion>
First, the electrophoretic dispersion of the present invention will be described.
The electrophoretic dispersion of the present invention is obtained by dispersing electrophoretic particles in a dispersion medium.

The electrophoretic dispersion of the present invention includes an electron donating molecule in one of the dispersion medium and the electrophoretic particles, and an electron accepting molecule in the other. Charge transfer between molecules is characterized by the movement of π electrons.
Due to these characteristics, π-electron charge transfer between the electron-donating molecule (electron-accepting molecule) on the surface of the electrophoretic particle and the electron-accepting molecule (electron-donating molecule) in the dispersion medium. Action (charge transfer) occurs. That is, the electron donating molecule (electron accepting molecule) is partially charged with a positive (negative) charge, and can function as an electrophoretic particle. In addition, since the electrophoretic particles can be charged more greatly than in the conventional electrophoretic dispersion liquid, the display can be switched at a higher speed. In addition, although an ionic molecule can be considered as an electron-donating molecule or an electron-accepting molecule, in a solvent having a low polarity such as a dispersion medium generally used in an electrophoretic dispersion, ion dissociation is small and electric Electrophoretic particles cannot be charged significantly. On the other hand, the electron donating molecule and the electron accepting molecule used in the present invention are not accompanied by ionization, and the charge is biased due to the movement of π electrons, thereby causing charging. Therefore, even in a low polarity solvent such as a dispersion medium, the electrophoretic particles can be largely charged.

Hereinafter, each component will be described in detail.
[Electron donating molecule]
The electron donating molecule is contained in either the dispersion medium or the electrophoretic particles.
Here, the fact that the electrophoretic particles contain an electron donating molecule means that the electrophoretic particles are contained in the particle surface (interface) portion where the electrophoretic particles and the dispersion medium are in contact and inside the particles.
In the present invention, the electron donating molecule is a molecule that is partially positively charged by transferring π electrons to the electron accepting molecule described later. The electron donating molecule also includes a polymer containing an electron donating moiety.

  Examples of electron donating molecules include tetrathiafulvalene, bis (ethylenedithio) tetrathiafulvalene, bis (methylenedithio) tetrathiafulvalene, bis (trimethylenedithio) tetrathiafulvalene, dimethyltetrathiafulvalene, and formyltetrathiafulvalene. , Tetrakis (methylthio) tetrathiafulvalene, tetrakis (octadecylthio) tetrathiafulvalene, tetrakis (pentylthio) tetrathiafulvalene, tetrakis (ethylthio) tetrathiafulvalene, 2,3,6,7-tetrakis (2-cyanoethylthio) tetra Thiafulvalene, tetracene, perylene, anthracene, coronene, pyrene, chrysene, phenanthrene, naphthalene, p-dimethoxybenzene, hexamethoxytriphenylene, tetra Otetracene, tetraselenotetracene, tetratellurotetracene, dibenzophenothiazine, benzophenothiazine, phenothiazine, N-methylphenothiazine, dibenzophenoselenazine, dimethylphenazine, phenazine, NN-diethyl-m-toluidine, NN-diethylaniline, N-ethyl- o-toluidine, diphenylamine, skatole, indole, NN-dimethyl-o-toluidine, o-toluidine, m-toluidine, aniline, o-chloroaniline, o-bromoaniline, p-nitroaniline, NNN'N'-tetramethyl -2,3,5,6-tetramethyldylenediamine, p-phenylenediamine, NNN'N'-tetramethylbenzidine, 3,3 ', 5,5'-tetramethylbenzidine, 3,3'-dimethyl Rubenzidine, 3,3′-dimethoxybenzidine, benzidine, 3,3′-dibromo-5,5′dimethylbenzidine, 3,3′-dichloro-5,5′dimethylbenzidine, 1,6-diaminopyrene, 1,4 , 6,8-tetrakisdimethylaminopyrene, 1,6-dithiopyrene, decamethylferrocene, ferrocene and the like, or derivatives of the above-described molecules and polymers containing these substances.

Among the above, it is preferable to use a compound having a tetrathiafulvalene skeleton as the electron-donating molecule. Thereby, electrophoretic particles can be charged more greatly.
When the electron donating molecule is contained in the electrophoretic particle, the content of the electron donating molecule in the electrophoretic particle is preferably 0.1% by mass or more and 10% by mass or less with respect to the electrophoretic particle. More preferably, it is 0.5 mass% or more and 3 mass% or less. Thereby, electrophoretic particles can be charged more efficiently.
When the electron-donating molecule is contained in the dispersion medium, the content of the electron-donating molecule in the dispersion medium is preferably 0.1% by mass or more and 10% by mass or less with respect to the dispersion medium. It is more preferably 1% by mass or more and 5% by mass or less. Thereby, electrophoretic particles can be charged more efficiently.

[Electron-accepting molecule]
The electron accepting molecule is contained in either the dispersion medium or the electrophoretic particles.
In the present invention, the electron-accepting molecule is a molecule that is partially negatively charged by receiving π electrons from the above-described electron-donating molecule.
Examples of the electron accepting molecule include tetracyanoquinodimethane, 2,5-bis (2-hydroxyethoxy) -7,7,8,8-tetracyanoquinodimethane, 2,5-dimethyl-7,7. , 8,8-tetracyanoquinodimethane, 2,5-difluoro-7,7,8,8-tetracyanoquinodimethane, 2-fluoro-7,7,8,8-tetracyanoquinodimethane, tetra Cyanoquinoethylene, 7,7,8,8-tetracyanoquinodimethane, tetrafluorotetracyanoquinodimethane, 11,11,12,12-tetracyanonaphth-2,6-quinodimethane, bis (1,3- Dithiol-2-thione-4,5-dithiolato) zinc (II), bis (dithiobenzyl) nickel (II), bis (maleonitriledithiolato) nickel (II), bis (1,3 Dithiol-2-thione-4,5-dithiolato) palladium (II), bis (1,3-dithiole-2-thione-4,5-dithiolato) platinum (II), bis (1,3-dithiola-2-) Thione-4,5-dithiolato) aurate (III), (toluene-3,4-dithiolato) zinc (II), bis (1,3-dithiole-2-thione-4,5-dithiolato) nickel (III), Bis (maleonitriledithiolato) nickel (III), 1,4-benzoquinone, 1,3-bis (dicyanomethylidene) indane, 2-bromo-5-methyl-1,4-benzoquinone, 2-bromo-1, 4-benzoquinone, 2-chloro-5-methyl-1,4-benzoquinone, 1,5-diaminonaphthalene, 2,5-dichloro-1,4-benzoquinone, 2,3 Dichloro-5,6-dicyano-1,4-benzoquinone, 2,3-dimethoxy-5-methyl-1,4-benzoquinone, 2,5-di-tert-amylbenzoquinone, 2,6-dimethyl-1,4 -Benzoquinone, 2,5-dibromo-1,4-benzoquinone, 2,5-dimethoxy-1,4-benzoquinone, 5,10-dihydro-5,10-dimethylphenazine, methoxybenzoquinone, phenothiazine, chloranil, 2,4 , 7-trinitro-9-fluorenone, bromanyl, tetrafluoro-1,4-benzoquinone, 2,4,7-trinitro-9-fluorenylidenemalononitrile, 3,3 ′, 5,5′-tetramethylbenzidine, Tetrakis (dimethylamino) ethylene, 3,3 ′, 5,5′-tetra-tert-butyl-4,4′-diphenoquinone Tetracyanoanthraquinone dimethane, tetranitrobiphenol, dinitrobiphenyl, picric acid, trinitrobenzene, 2,6-dinitrophenol, 2,4-dinitrophenol, 9-dicyanomethylene-2,4,5,7-tetranitrofluorene, 9-dicyanomethylene-2,4,7-trinitrofluorene, 2,4,5,7-tetranitrofluorene, 2,4,7-trinitrofluorene, fullerene (C60), etc. Examples include polymers containing these substances.

Among the above, it is preferable to use a compound having a tetracyanoquinodimethane skeleton as the electron-accepting molecule. Thereby, electrophoretic particles can be charged more greatly.
When the electron-accepting molecule is contained in the electrophoretic particle, the content of the electron-accepting molecule in the electrophoretic particle is preferably 0.1% by mass or more and 10% by mass or less with respect to the electrophoretic particle, More preferably, it is 0.5 mass% or more and 3 mass% or less. Thereby, electrophoretic particles can be charged more efficiently.

Further, when the electron-accepting molecule is contained in the dispersion medium, the content of the electron-accepting molecule in the dispersion medium is preferably 0.1% by mass or more and 10% by mass or less with respect to the dispersion medium. It is more preferably 1% by mass or more and 5% by mass or less. Thereby, electrophoretic particles can be charged more efficiently.
Further, when the number of electron-donating molecules or electron-accepting molecules contained in the dispersion medium is X and the number of electron-donating molecules or electron-accepting molecules contained in the electrophoretic particles is Y, X It is preferable to satisfy the relationship of ≧ Y. By satisfying such a relationship, the charge amount of the electrophoretic particles can be further increased.

[Dispersion medium]
The dispersion medium has a function of dispersing the electrophoretic particles.
It is preferable to use a dispersion medium having a relatively high insulating property. Moreover, it is preferable to use a nonpolar solvent as a dispersion medium. Thereby, the electrical conductivity of a dispersion medium can be kept low and the power consumption at the time of carrying out electrophoresis can be made smaller.

Examples of the dispersion medium include various types of water, alcohols, cellosolves, esters, aliphatic hydrocarbons (liquid paraffin), alicyclic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, and aromatics. Fluorine rings and the like can be mentioned, and these may be used as a single solvent or a mixed solvent.
In such a dispersion medium, either one of the above-described electron donating molecule or electron accepting molecule is contained.
In addition, in the dispersion medium, charge control comprising particles of electrolyte, surfactant (anionic or cationic), metal soap, resin material, rubber material, oils, varnish, compound, etc., if necessary. Various additives such as an agent, a lubricant, a stabilizer, various dyes, a phenol oxide-based or sulfur-based antioxidant, a radical scavenger, and an ultraviolet absorber may be added.

[Electrophoretic particles]
The electrophoretic particles are particles dispersed in the above-described dispersion medium, and are charged positively or negatively in the dispersion medium and electrophoresed in the dispersion liquid by applying an electric field.
In the electrophoretic particle, either one of the above-described electron donating molecule or electron accepting molecule is contained.

As the electrophoretic particles, any of organic particles, inorganic particles, and composite particles thereof may be used.
Organic particles include styrene, (meth) acrylic, isoprene, acrylonitrile, ethylene, nylon, silicone, urethane, melamine, benzoguanamine, phenol, fluorine, vinylidene chloride, cellulose And particles of the system.

Also, inorganic particles include alumina, titanium dioxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, chromium oxide, cerium oxide, bengara, antimony trioxide, magnesium oxide, zirconium oxide, Examples thereof include powders or particles of barium sulfate, barium carbonate, calcium carbonate, silica fine powder, silicon carbide, silicon nitride, boron carbide, tungsten carbide, titanium carbide and the like.
The material constituting the electrophoretic particles may contain a colorant.

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

When white (scattering) particles are used as the electrophoretic particles, the average diameter of the electrophoretic particles is preferably 200 nm or more and 1000 nm or less, and more preferably 300 nm or more and 500 nm or less.
When the electrophoretic particles are other than white, that is, colored particles such as black or RGBCMY are used, the average diameter of the electrophoretic particles is preferably 10 nm to 500 nm, and preferably 50 nm to 200 nm. Is more preferable.

Further, the electrophoretic particles may be subjected to a surface treatment. Thereby, the charge amount of the electrophoretic particles can be increased, and the electrophoretic particles can be electrophoresed with a larger force. Moreover, the dispersibility of the electrophoretic particles in the dispersion medium can be improved.
Examples of such surface treatment include coating treatment with a positively charged material such as an amine compound and alumina, a negatively charged material such as a carboxyl group, a sulfo group, and silicon oxide, and a cup such as a silane coupling agent and a titanium coupling agent. Examples include ring treatment, surfactant surface treatment, and polymer graft treatment.
As a method for including the electron donating molecule or the electron accepting molecule in the electrophoretic particle, for example, the following method can be used.

(Method 1)
First, a solution in which an electron donating molecule or an electron accepting molecule is dissolved in an organic solvent is prepared.
Next, the particles (organic particles and inorganic particles) are stirred in the obtained solution and then dried. Thereby, electrophoretic particles containing an electron donating molecule or an electron accepting molecule can be obtained.
As an example, when polymer particles are added after tetrathiofulvalene is dissolved in toluene, chloroform, and acetonitrile, the particles swell with the solvent, so that tetrathiofulvalene enters the gaps between the polymers.
And tetrathiofulvalene is fix | immobilized in particle | grains by drying, after removing a solvent by centrifugation etc. During this treatment, treatment such as heating or decompression may be performed as necessary.

(Method 2)
First, an organic low-molecular gel is formed in a sol-gel reaction solution containing a metal oxide precursor, and then an electron-donating molecule or an electron-accepting molecule is added.
Thereafter, by maintaining the gel-formed system and allowing the polymerization of the metal oxide to proceed, organic-inorganic composite particles (electrophoretic particles) containing an electron-donating molecule or an electron-accepting molecule can be produced.
(Method 3)
Electron-donating molecules or electron-accepting molecules can also be chemically bonded in the particle or on the surface. In this case, an electron donating molecule or an electron accepting molecule having a functional group that can be chemically bonded is used.

<Electrophoretic display device>
Next, an electrophoretic display device to which an electrophoretic display sheet using the electrophoretic dispersion of the present invention is applied will be described.
FIG. 1 is a diagram schematically showing a longitudinal section of an embodiment of an electrophoretic display device, and FIG. 2 is a schematic diagram showing the operating principle of the electrophoretic display device shown in FIG. In the following description, for convenience of explanation, the upper side in FIGS. 1 and 2 is described as “upper” and the lower side is described as “lower”.

An electrophoretic display device 920 shown in FIG. 1 includes an electrophoretic display sheet (front plane) 921, a circuit board (back plane) 922, an adhesive layer 98 that bonds the electrophoretic display sheet 921 and the circuit board 922, and A sealing portion 97 that hermetically seals a gap between the electrophoretic display sheet 921 and the circuit board 922 is provided.
The electrophoretic display sheet (electrophoretic display sheet of the present invention) 921 includes a substrate 912 including a flat base 92 and a second electrode 94 provided on the lower surface of the base 92, and a lower surface (one of the substrates 912). A partition layer 940 formed in a matrix and a display layer 9400 composed of an electrophoretic dispersion liquid 910.
On the other hand, the circuit board 922 includes a counter substrate 911 including a flat base 91 and a plurality of first electrodes 93 provided on the upper surface of the base 91, and the counter substrate 911 (base 91), for example. And a circuit (not shown) including a switching element such as a TFT.

Hereinafter, the structure of each part is demonstrated sequentially.
The base portion 91 and the base portion 92 are each composed of a sheet-like (flat plate) member, and have a function of supporting and protecting each member disposed between them.
Each of the bases 91 and 92 may be either flexible or hard, but preferably has flexibility. By using the flexible base portions 91 and 92, a flexible electrophoretic display device 920, that is, an electrophoretic display device 920 useful for constructing, for example, electronic paper can be obtained.

Moreover, when each base part (base material layer) 91 and 92 shall have flexibility, it is preferable to respectively comprise these with resin material.
The average thicknesses of the bases 91 and 92 are appropriately set depending on the constituent material, application, and the like, and are not particularly limited, but are preferably about 20 to 500 μm, and more preferably about 25 to 250 μm. .

A first electrode 93 and a second electrode 94 that form a layer (film shape) are provided on the surface of the bases 91 and 92 on the partition wall 940 side, that is, on the upper surface of the base 91 and the lower surface of the base 92, respectively. Yes.
When a voltage is applied between the first electrode 93 and the second electrode 94, an electric field is generated between them, and this electric field acts on the electrophoretic particles 95.

In the present embodiment, the second electrode 94 is a common electrode, the first electrode 93 is an individual electrode (pixel electrode connected to a switching element) divided in a matrix (matrix), A portion where the two electrodes 94 overlap with one first electrode 93 constitutes one pixel.
The constituent materials of the electrodes 93 and 94 are not particularly limited as long as they are substantially conductive.

The average thicknesses of the electrodes 93 and 94 are appropriately set depending on the constituent materials and applications, and are not particularly limited, but are preferably about 0.05 to 10 μm, and about 0.05 to 5 μm. Is more preferable.
Of the base portions 91 and 92 and the electrodes 93 and 94, the base portion and the electrodes (in the present embodiment, the base portion 92 and the second electrode 94) disposed on the display surface side each have light transmittance. In other words, substantially transparent (colorless transparent, colored transparent or translucent).

In the electrophoretic display sheet 921, a display layer 9400 is provided in contact with the lower surface of the second electrode 94.
The display layer 9400 is configured such that an electrophoretic dispersion liquid (the above-described electrophoretic dispersion liquid of the present invention) 910 is contained (enclosed) in a plurality of pixel spaces 9401 defined by partition walls 940.

The partition 940 is formed between the counter substrate 911 and the substrate 912 so as to be divided in a matrix.
Examples of the constituent material of the partition wall 940 include various resins such as thermoplastic resins such as acrylic resins, urethane resins, and olefin resins, epoxy resins, melamine resins, and thermosetting resins such as phenol resins. A material etc. are mentioned, Among these, it can use combining 1 type (s) or 2 or more types.

In this embodiment, the electrophoretic dispersion liquid 910 accommodated in the pixel space 9401 is dispersed (suspended) in the dispersion medium 96, in which two types of colored particles 95b and white particles 95a (at least one type of electrophoretic particle 1) are dispersed. The electrophoretic dispersion liquid of the present invention described above is applied.
In such an electrophoretic display device 920, when a voltage is applied between the first electrode 93 and the second electrode 94, colored particles 95b and white particles 95a (electrophoretic particles) are generated according to the electric field generated therebetween. ) Electrophoresis towards either electrode.
In the present embodiment, white particles 95a having a positive charge are used, and negative particles are used as colored particles (black particles) 95b.

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

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

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

In the present embodiment, the electrophoretic display sheet 921 and the circuit board 922 are bonded via the adhesive layer 98. Thereby, the electrophoretic display sheet 921 and the circuit board 922 can be more reliably fixed.
The average thickness of the adhesive layer 98 is not particularly limited, but is preferably about 1 to 30 μm, and more preferably about 5 to 20 μm.

A sealing portion 97 is provided between the base portion 91 and the base portion 92 and along the edges thereof. The electrodes 93 and 94, the display layer 9400, and the adhesive layer 98 are hermetically sealed by the sealing portion 97. Accordingly, it is possible to prevent moisture from entering the electrophoretic display device 920 and more reliably prevent the display performance of the electrophoretic display device 920 from deteriorating.
As the constituent material of the sealing portion 97, the same materials as those described above as the constituent material of the partition wall 940 can be used.

<Electronic equipment>
Next, the electronic apparatus of the present invention will be described.
The electronic apparatus of the present invention includes the electrophoretic display device 920 as described above.
<< Electronic Paper >>
First, an embodiment when the electronic apparatus of the present invention is applied to electronic paper will be described.

FIG. 3 is a perspective view showing an embodiment when the electronic apparatus of the present invention is applied to electronic paper.
An electronic paper 600 shown in FIG. 3 includes a main body 601 composed of a rewritable sheet having the same texture and flexibility as paper, and a display unit 602.
In such an electronic paper 600, the display unit 602 includes the electrophoretic display device 920 as described above.

<< Display >>
Next, an embodiment when the electronic apparatus of the present invention is applied to a display will be described.
FIG. 4 is a diagram showing an embodiment when the electronic apparatus of the present invention is applied to a display. 4A is a sectional view, and FIG. 4B is a plan view.
A display (display device) 800 shown in FIG. 4 includes a main body portion 801 and an electronic paper 600 that is detachably attached to the main body portion 801.

  The main body 801 has an insertion port 805 into which the electronic paper 600 can be inserted on the side (right side in FIG. 4A), and two pairs of conveying rollers 802a and 802b are provided inside. Yes. When the electronic paper 600 is inserted into the main body 801 through the insertion port 805, the electronic paper 600 is installed in the main body 801 in a state of being sandwiched between the pair of conveyance rollers 802a and 802b.

  A rectangular hole 803 is formed on the display surface side of the main body 801 (the front side in FIG. 4B), and a transparent glass plate 804 is fitted in the hole 803. . Thereby, the electronic paper 600 installed in the main body 801 can be viewed from the outside of the main body 801. That is, in the display 800, the display surface is configured by visually recognizing the electronic paper 600 installed in the main body 801 on the transparent glass plate 804.

Further, a terminal portion 806 is provided at the leading end portion (left side in FIG. 4) of the electronic paper 600 in the insertion direction, and the terminal is provided inside the main body portion 801 with the electronic paper 600 installed on the main body portion 801. A socket 807 to which the unit 806 is connected is provided. A controller 808 and an operation unit 809 are electrically connected to the socket 807.
In such a display 800, the electronic paper 600 is detachably installed on the main body 801, and can be carried and used while being detached from the main body 801.
Further, in such a display 800, the electronic paper 600 includes the electrophoretic display device 920 as described above.

Note that the electronic apparatus of the present invention is not limited to the application to the above, and for example, a television, a viewfinder type, a monitor direct view type video tape recorder, a car navigation device, a pager, an electronic notebook, a calculator, an electronic Examples include newspapers, word processors, personal computers, workstations, videophones, POS terminals, and devices equipped with touch panels. The electrophoretic display device 920 can be applied to the display units of these various electronic devices. is there.
The electrophoretic dispersion, electrophoretic display sheet, electrophoretic display device, and electronic apparatus according to the present invention have been described based on the illustrated embodiment. However, the present invention is not limited to this, and the configuration of each part Can be replaced with any structure having a similar function. In addition, any other component may be added to the present invention.

In the above-described embodiment, the electrophoretic particle is described as including an electron donating molecule or an electron accepting molecule. However, the dispersion medium does not include an electron donating molecule and an electron accepting molecule. Electrophoretic particles (electrophoretic particles having different colors) may be included.
The electrophoretic dispersion of the present invention includes a dispersion medium containing both an electron donating molecule and an electron accepting molecule, electrophoretic particles 1 containing an electron donating molecule, and an electrophoretic particle. 1 may include electrophoretic particles 2 having different colors.

1. Production of electrophoretic dispersion (Example 1)
(1) Preparation of black particles (electrophoretic particles) 10 g of copper chromite (black particles) and 2 g of (3-GLYCIDOXYPROPYL) TRIMETHOXYSILANE were placed in 100 mL of toluene, and the mixture was well stirred with a magnetic stirrer for 1 hour.

Next, after adding a mixed solution of water (0.5 mL) and toluene (10 mL), reflux was performed for 2 hours to epoxidize the surface of the copper chromite.
Next, after washing the particles using a centrifugal separator, 1 g of the obtained particles and 0.1 g of the following compound A are added to 50 mL of acetonitrile and refluxed for 2 hours, whereby the thiol group of compound A and chromium oxide are added. Electron copper surfaces were reacted with epoxy groups to impart electron donating properties to the particles. Thereby, electrophoretic particles were obtained.

(2) Preparation of electrophoretic dispersion 1 g of electrophoretic particles was added to 15 mL of Isopar G, 0.05 g of Solsperse 17000 (Nippon Lubrizol Co., Ltd.) was added as a dispersant, and sonication was performed for 2 hours.
Next, a positively charged electrophoretic dispersion was prepared by adding a solution prepared by dissolving 0.01 g of tetracyanoquinodimethane (electron-accepting molecule) in 5 mL of toluene.

(Example 2)
An electrophoretic dispersion was produced in the same manner as in Example 1 except that the black particles were prepared as follows.
(1) Preparation of black particles (electrophoretic particles) 10 g of carbon black (black particles) and 0.1 g of tetrathiafulvalene (electron-donating molecule) were added to 100 mL of acetonitrile, followed by ultrasonic treatment for 2 hours. Time reflux was performed.
As a result, tetrathiafulvalene was adsorbed on the surface by π-electron interaction with the benzene ring on the surface of carbon black, and electron donating properties were imparted to the particles. Thereby, electrophoretic particles were obtained.

Example 3
(1) Creation of white particles (electrophoretic particles)
10 g of crosslinked polymethyl methacrylate particles (Techpolymer: Sekisui Chemicals Co., Ltd.) having a diameter of 0.4 μm as white particles were dissolved in 50 mL of THF and stirred well with a magnetic stirrer while raising the temperature to 50 ° C.

Next, in a state where the particles were swollen with THF, 0.2 g of tetrafluorotetracyanoquinodimethane (electron-accepting molecule) was added and further stirred for 1 hour.
Next, after cooling to room temperature, the particles are isolated by centrifugation, vacuum-dried at 80 ° C. for 2 hours to remove the solvent that has swollen the particles, and tetrafluorotetracyanoquinodimethane is fixed in the particles. To give electron acceptability to the particle surface. Thereby, electrophoretic particles were obtained.
In addition, from the measurement of the infrared spectrum of the actually obtained particles, it was confirmed that tetrafluorotetracyanoquinodimethane was present in the particles.

(2) Preparation of electrophoretic dispersion 1 g of electrophoretic particles obtained as described above and 0.02 g of octadecyltriethoxysilane were added to 20 mL of hexane, and the mixture was stirred for 2 hours with an ultrasonic cleaner.
After standing overnight, solvent washing with a centrifuge and hexane was repeated three times to remove excess octadecyltriethoxysilane.
Thereafter, the particles were dried to obtain particles whose surface was treated with an alkyl group (octadecyl group). A dispersion of negatively charged white particles (electrophoretic particle dispersion) was prepared by mixing 1 g of the particles and 0.01 g of the following polymer compound B having an electron donating property in silicon oil.

(Comparative example)
After adding 1 g of copper chromite (black particles) to 15 mL of Isopar G, 0.05 g of Solsperse 17000 (Nihon Lubrizol Co., Ltd.) was added as a dispersant, and sonication was performed for 2 hours. Thereby, an electrophoretic dispersion was prepared.

2. Preparation and evaluation of electrophoretic display (2-1)
A dispersion was separately prepared in which titanium oxide particles (CR-80: Ishihara Sangyo Co., Ltd.) were dispersed in Isopar G using Solsperse 17000 as a dispersant.
This dispersion was mixed with the electrophoretic dispersion of Example 1 above.

When the obtained liquid mixture was injected into an ITO cell having a thickness of 50 μm and the display performance was evaluated, the display characteristics of white display reflectance 55% / black display reflectance 1% (contrast 55) were exhibited. I understood.
Moreover, when the electrophoretic dispersion liquid of Example 1 was changed to the dispersion liquid of Example 2 and the above evaluation was performed, a good display of white display reflectance 40% / black display reflectance 3% (contrast 13) was obtained. It turns out that it shows the characteristic.
Further, when the above-described evaluation was performed by changing the electrophoretic dispersion liquid of Example 1 to the dispersion liquid of the comparative example, the white display reflectance 30% / black display reflectance 6% (contrast 5) were good results. Was not obtained.

(2-2)
In the same manner as in Example 3, 0.02 g of octadecyltriethoxysilane was added to black titanium oxynitride pigment powder in 20 ml of hexane, and the mixture was stirred with an ultrasonic cleaner for 2 hours. A black particle dispersion treated with (octadecyl group) was obtained.
This black particle dispersion was mixed with the electrophoretic dispersion obtained in Example 3.
When the obtained liquid mixture was injected into an ITO cell having a thickness of 50 μm and the display performance was evaluated, the display characteristics of white display reflectance 50% / black display reflectance 2% (contrast 25) were exhibited. I understood.

  91 …… Base 92 …… Base 93 …… First electrode 94 …… Second electrode 95a …… White particles 95b …… Colored particles (black particles) 96 …… Dispersion medium 97 …… Sealing portion 98 …… Adhesive layer 910 …… Electrophoretic dispersion liquid 911 …… Counter substrate 912 …… Substrate 920 …… Electrophoretic display device 921 …… Electrophoretic display sheet 922 …… Circuit substrate 940 …… Partition wall 9400 …… Display layer 9401 …… Pixel space 600 ... Electronic paper 601 ... Main body 602 ... Display unit 800 ... Display 801 ... Main body 802a, 802b ... Conveying roller pair 803 ... Hole 804 ... Transparent glass plate 805 ... Insertion port 806 …… Terminal part 807 …… Socket 808 …… Controller 809 …… Operation part

Claims (9)

Including a dispersion medium and electrophoretic particles,
One of the dispersion medium and the electrophoretic particles contains an electron donating molecule, and the other contains an electron accepting molecule,
The electrophoretic dispersion liquid, wherein charge transfer between the electron donating molecule and the electron accepting molecule is performed by movement of π electrons.   The electrophoretic dispersion according to claim 1, wherein the electron donating molecule has a tetrathiafulvalene skeleton.   The electrophoretic dispersion according to claim 1, wherein the electron accepting molecule has a tetracyanoquinodimethane skeleton.   4. The content of the electron donating molecule or the electron accepting molecule contained in the electrophoretic particle is 0.1% by mass or more and 10% by mass or less with respect to the electrophoretic particle. The electrophoretic dispersion liquid according to claim 1.   5. The content of the electron donating molecule or the electron accepting molecule contained in the dispersion medium is 0.1% by mass or more and 10% by mass or less with respect to the dispersion medium. The electrophoretic dispersion liquid according to item.   The number of the electron donating molecule or the electron accepting molecule contained in the dispersion medium is X, and the number of the electron donating molecule or the electron accepting molecule contained in the electrophoretic particle is Y. 6. The electrophoretic dispersion according to claim 1, wherein the relationship of X ≧ Y is satisfied. A substrate,
An electrophoretic display sheet, comprising: a plurality of structures that are disposed above the substrate and each store the electrophoretic dispersion liquid according to any one of claims 1 to 6.   An electrophoretic display device comprising the electrophoretic display sheet according to claim 7.   An electronic apparatus comprising the electrophoretic display device according to claim 8.

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