WO2016129435A1 - Electrophoretic element and method for manufacturing same, and display device - Google Patents

Abstract

In an electrophoretic element according to the present technique, migrating particles and a porous layer are provided in an insulating liquid, wherein the porous layer is formed from a fibrous structure formed by overlaying one or more fibers and non-migrating particles held by the fibrous structure, and reinforcing parts are provided at at least some of fiber-fiber neighboring sections in the fibrous structure.

Description

Electrophoretic element, method for manufacturing the same, and display device

The present technology relates to an electrophoretic element including a plurality of electrophoretic particles in an insulating liquid, a manufacturing method thereof, and a display device using the same.

In recent years, with the spread of mobile devices such as mobile phones or portable information terminals, the demand for display devices (displays) with low power consumption and high quality image quality has increased. In particular, recently, the electronic book distribution business has started, and a display with a display quality suitable for reading applications is desired.

As such a display, various displays such as a cholesteric liquid crystal display, an electrophoretic display, an electrooxidation reduction display, and a twist ball display have been proposed, but a reflective display is advantageous for reading applications. . In the reflective display, bright display is performed using reflection (scattering) of external light as in the case of paper, so that display quality closer to that of paper can be obtained.

Among the reflective displays, electrophoretic displays using the electrophoretic phenomenon are expected to be promising candidates because of their low power consumption and fast response speed. As the display method, the following two methods are mainly proposed.

The first method is to disperse two kinds of charged particles in an insulating liquid and move the charged particles according to the electric field. The two kinds of charged particles have different optical reflection characteristics and opposite polarities. In this method, an image is displayed by changing a distribution state of charged particles according to an electric field.

The second method is to disperse charged particles in an insulating liquid and dispose a porous layer (for example, Patent Document 1). In this method, charged particles move through the pores of the porous layer according to the electric field. The porous layer includes, for example, a fibrous structure made of a polymer material, and non-electrophoretic particles that are held by the fibrous structure and have different optical reflection characteristics from the charged particles. In an electrophoretic display in which such a porous layer is arranged, the display is switched by moving charged particles through voids (pores) according to an electric field. For example, in Patent Document 2, the fibrous structure constituting the porous layer is provided with a highly functional group such as an amide group, an imide group, a carboxyl group, a cyano group, a chloride group, a sulfonyl group, an amino group, or a urethane bond. An electrophoretic element has been disclosed in which the structure and the functional group having high reactivity are modified to facilitate the formation of a structure, and the absolute value of the surface potential is increased to improve the display characteristics.

JP 2012-22296 A JP 2013-254019 A

However, in such an electrophoretic display, the fibrous structure is deformed by bending or pressing the display screen, and the pore diameter is reduced. This makes it difficult to move the electrophoretic particles, resulting in a problem that the responsiveness of the electrophoretic display is deteriorated. As a method for solving this problem, it is conceivable to increase the rigidity by forming a fibrous structure using a molecule (polymer) having a large molecular weight, but in this case, the fiber diameter becomes thick and the scattering efficiency decreases. There is a problem that the contrast is lowered.

Therefore, it is desirable to provide an electrophoretic element that can reinforce the fibrous structure and improve the reliability, a manufacturing method thereof, and a display device.

An electrophoretic element according to an embodiment of the present technology includes a fibrous structure formed by superimposing electrophoretic particles and one or more fibers in an insulating liquid, and non-electrophoretic particles held by the fibrous structure. The fibrous structure is provided with a reinforcing portion in at least a part of the proximity portion between the fibers.

An electrophoretic device manufacturing method according to an embodiment of the present technology includes forming electrophoretic particles, mixing non-electrophoretic particles, forming a fibrous structure that forms a porous layer, and fibrous structure. Forming a reinforcing portion.

A display device according to an embodiment of the present technology includes a plurality of the electrophoretic elements of the present technology.

In the electrophoretic element according to an embodiment of the present technology, the manufacturing method according to the embodiment, and the display device according to the embodiment, at least a part of a proximity portion in which the fibers are adjacent to each other in the fibrous structure constituting the porous layer. By providing the reinforcing portion on the fibrous structure, the fibrous structure is reinforced and the rigidity of the porous layer is improved.

According to the electrophoretic element of one embodiment of the present technology, the manufacturing method of the one embodiment, and the display device of the one embodiment, at least a part of the proximity portion between the fibers of the fibrous structure constituting the porous layer A reinforcing portion was provided to reinforce the fibrous structure. Thereby, the rigidity of a porous layer improves and the hole diameter of the pore formed with a fibrous structure is maintained. That is, a display device with high reliability can be provided. Note that the effects described here are not necessarily limited, and may be any effects described in the present disclosure.

It is a top view showing the composition of the electrophoretic device concerning one embodiment of this art. It is sectional drawing of the display apparatus provided with the electrophoretic element shown in FIG. It is a flowchart explaining an example of the formation process of a porous layer. It is a flowchart explaining the other example of the formation process of a porous layer. FIG. 2 is a cross-sectional view for explaining the operation of the display device shown in FIG. 1. FIG. 2 is a cross-sectional view for explaining the operation of the display device shown in FIG. 1. It is a plane schematic diagram of the porous layer as a comparative example. It is a plane schematic diagram of the porous layer of this technique. It is an expansion schematic diagram of the fibrous structure as a comparative example. It is an expansion schematic diagram of the fibrous structure of this technique shown in FIG. 5B. 12 is a perspective view illustrating an example of an appearance of application example 1. FIG. FIG. 7B is a perspective view illustrating another example of the electronic book illustrated in FIG. 7A. 12 is a perspective view illustrating an appearance of application example 2. FIG.

Hereinafter, an embodiment of the present technology will be described in detail with reference to the drawings. The description will be given in the following order.
1. Embodiment (Example in which reinforcing portion is formed on fibrous structure forming porous layer)
1-1. Configuration of electrophoretic element 1-2. Configuration of display device 1-3. Manufacturing method 1-4. Action / Effect Application example Example

<1. Embodiment>
(1-1. Configuration of electrophoretic element)
FIG. 1 illustrates a planar configuration of an electrophoretic element (electrophoretic element 30) according to an embodiment of the present technology, and FIG. 2 illustrates a display device including the electrophoretic element 30 illustrated in FIG. 2 shows a cross-sectional configuration of (display device 1). The electrophoretic element 30 generates contrast using an electrophoretic phenomenon, and is used as a display body of various electronic devices such as tablets. The electrophoretic element 30 includes an electrophoretic particle 32 and a porous layer 33 having pores 36 in an insulating liquid 31. The porous layer 33 includes a fibrous structure 34 and non-migrating particles 35 held by the fibrous structure 34. In this Embodiment, the porous layer 33 has the reinforcement part A by which the fibers were bridge | crosslinked in the adjacent part of the fibers of the fibrous structure 34 formed as a three-dimensional solid structure. 1 and 2 schematically illustrate the configuration of the electrophoretic element 30 and the display device 1 including the same, and may differ from actual dimensions and shapes.

The insulating liquid 31 is made of, for example, an organic solvent such as paraffin or isoparaffin. As the insulating liquid 31, one kind of organic solvent may be used, or a plurality of kinds of organic solvents may be used. It is preferable to make the viscosity and refractive index of the insulating liquid 31 as low as possible. When the viscosity of the insulating liquid 31 is lowered, the mobility (response speed) of the migrating particles 32 is improved. In accordance with this, the energy (power consumption) required to move the migrating particles 32 is reduced. When the refractive index of the insulating liquid 31 is lowered, the difference in refractive index between the insulating liquid 31 and the porous layer 33 is increased, and the reflectance of the porous layer 33 is increased.

For example, a coloring agent, a charge adjusting agent, a dispersion stabilizer, a viscosity adjusting agent, a surfactant, or a resin may be added to the insulating liquid 31.

The migrating particles 32 dispersed in the insulating liquid 31 are one or two or more charged particles, and the charged migrating particles 32 move through the pores 36 according to the electric field. The migrating particles 32 have an arbitrary optical reflection characteristic (light reflectance), and a contrast (CR) is generated due to the difference between the light reflectance of the migrating particles 32 and the light reflectance of the porous layer 33. It has become. For example, the migrating particles 32 may be brightly displayed and the porous layer 33 may be darkly displayed, or the migrating particles 32 may be darkly displayed and the porous layer 33 may be brightly displayed.

When the electrophoretic element 30 is viewed from the outside, when the electrophoretic particles 32 are brightly displayed, the electrophoretic particles 32 are visually recognized as white or a color close to white, and when darkly displayed, for example, black or black It is visually recognized as a color close to. The color of the migrating particles 32 is not particularly limited as long as contrast can be generated.

The migrating particles 32 are made of particles (powder) such as organic pigments, inorganic pigments, dyes, carbon materials, metal materials, metal oxides, glass, or polymer materials (resins). One of these may be used for the migrating particles 32, or two or more of them may be used. The migrating particles 32 may be composed of pulverized particles or capsule particles of resin solids containing the particles. Note that materials corresponding to the carbon material, metal material, metal oxide, glass, or polymer material are excluded from materials corresponding to organic pigments, inorganic pigments, or dyes. The particle size of the migrating particles 32 is, for example, 30 nm to 300 nm.

Examples of the organic pigments include azo pigments, metal complex azo pigments, polycondensed azo pigments, flavanthrone pigments, benzimidazolone pigments, phthalocyanine pigments, quinacridone pigments, anthraquinone pigments, and perylene pigments. Perinone pigments, anthrapyridine pigments, pyranthrone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments or indanthrene pigments. Inorganic pigments include, for example, zinc white, antimony white, iron black, titanium boride, bengara, mapico yellow, red lead, cadmium yellow, zinc sulfide, lithopone, barium sulfide, cadmium selenide, calcium carbonate, barium sulfate, lead chromate Lead sulfate, barium carbonate, lead white or alumina white. Examples of the dye include nigrosine dyes, azo dyes, phthalocyanine dyes, quinophthalone dyes, anthraquinone dyes, and methine dyes. The carbon material is, for example, carbon black. The metal material is, for example, gold, silver or copper. Examples of metal oxides include titanium oxide, zinc oxide, zirconium oxide, barium titanate, potassium titanate, copper-chromium oxide, copper-manganese oxide, copper-iron-manganese oxide, and copper-chromium-manganese oxide. Or copper-iron-chromium oxide. The polymer material is, for example, a polymer compound in which a functional group having a light absorption region in the visible light region is introduced. If it is a high molecular compound which has a light absorption area | region in visible region, the kind will not be specifically limited.

The specific material of the migrating particles 32 is selected according to, for example, the role that the migrating particles 32 play in causing contrast. When the migrating particles 32 display brightly, for example, a metal oxide such as titanium oxide, zinc oxide, zirconium oxide, barium titanate or potassium titanate is used for the migrating particles 32. When the migrating particles 32 display in the dark, the migrating particles 32 may be, for example, a carbon material such as carbon black or copper-chromium oxide, copper-manganese oxide, copper-iron-manganese oxide, copper-chromium-manganese oxide. In addition, metal oxides such as copper-iron-chromium oxide are used. Among these, it is preferable to use a carbon material for the migrating particles 32. Electrophoretic particles 32 made of a carbon material exhibit excellent chemical stability, mobility and light absorption.

The content (concentration) of the migrating particles 32 in the insulating liquid 31 is not particularly limited, and is, for example, 0.1 wt% to 10 wt%. In this concentration range, the shielding and mobility of the migrating particles 32 are ensured. Specifically, if the content of the migrating particles 32 is less than 0.1% by weight, the migrating particles 32 are less likely to shield (conceal) the porous layer 33, and there is a possibility that sufficient contrast cannot be generated. is there. On the other hand, if the content of the migrating particles 32 is more than 10% by weight, the dispersibility of the migrating particles 32 is lowered, so that the migrating particles 32 are difficult to migrate and may aggregate.

The migrating particles 32 are preferably easily dispersed and charged in the insulating liquid 31 for a long period of time, and are preferably not easily adsorbed to the porous layer 33. For this reason, for example, a dispersant is added to the insulating liquid 31. A dispersant and a charge control agent may be used in combination.

This dispersing agent or charge adjusting agent has, for example, a positive or negative charge, or both, and increases the amount of charge in the insulating liquid 31 and causes the migrating particles 32 to move by electrostatic repulsion. It is for dispersing. Examples of such a dispersant include Solsperce series manufactured by Lubrizol, BYK series or Anti-Terra series manufactured by BYK-Chemie, or Span series manufactured by TCI America.

In order to improve the dispersibility of the migrating particles 32, the migrating particles 32 may be subjected to a surface treatment. This surface treatment is, for example, rosin treatment, surfactant treatment, pigment derivative treatment, coupling agent treatment, graft polymerization treatment or microencapsulation treatment. In particular, long-term dispersion stability of the migrating particles 32 can be maintained by performing a graft polymerization process, a microencapsulation process, or a combination thereof.

For such surface treatment, for example, a material (adsorbent material) having a functional group and a polymerizable functional group that can be adsorbed on the surface of the migrating particle 32 is used. The adsorbable functional group is determined according to the forming material of the migrating particle 32. For example, when the migrating particles 32 are made of a carbon material such as carbon black, an aniline derivative such as 4-vinylaniline, and when the migrating particles 32 are made of a metal oxide, methacrylic acid 3- Organosilane derivatives such as (trimethoxysilyl) propyl can be adsorbed respectively. Examples of the polymerizable functional group include a vinyl group, an acrylic group, and a methacryl group.

A surface treatment may be performed by introducing a polymerizable functional group onto the surface of the migrating particle 32 and grafting it onto the surface (graftable material). The graft material has, for example, a polymerizable functional group and a dispersing functional group. The functional group for dispersion disperses the migrating particles 32 in the insulating liquid 31 and retains dispersibility due to steric hindrance. For example, when the insulating liquid 31 is paraffin, a branched alkyl group or the like can be used as the functional group for dispersion. Examples of the polymerizable functional group include a vinyl group, an acrylic group, and a methacryl group. In order to polymerize and graft the graft material, for example, a polymerization initiator such as azobisisobutyronitrile (AIBN) may be used. In addition, a material having a functional group capable of being adsorbed on the surface of the migrating particle 32 and an alkyl chain for imparting dispersibility can be used. Examples of such materials include titanate coupling agents (for example, KR-TTS manufactured by Ajinomoto Fine Techno Co., Ltd.) and aluminate coupling agents.

For details of the method for dispersing the migrating particles 32 in the insulating liquid 31, see “Dispersion Technology of Ultrafine Particles and its Evaluation: Surface Treatment / Fine Grinding and Dispersion Stabilization in Air / Liquid / Polymer— Science & Technology)).

The porous layer 33 can shield the migrating particles 32, and includes a fibrous structure 34 and non-migrating particles 35 that are modified by the surfactant and held by the fibrous structure 34. Yes. The porous layer 33 is a three-dimensional structure (irregular network structure such as a nonwoven fabric) formed by the fibrous structure 34, and is provided with a plurality of gaps (pores 36). By forming the three-dimensional structure of the porous layer 33 by the fibrous structure 34, light (external light) is irregularly reflected (multiple scattering), and the reflectance of the porous layer 33 is increased. Therefore, even when the thickness of the porous layer 33 is small, a high reflectance can be obtained, the contrast of the electrophoretic element 30 can be improved, and the energy required to move the electrophoretic particles 32 can be reduced. . The film thickness in the Z-axis direction of the entire porous layer 33 (hereinafter simply referred to as thickness) is, for example, 1 μm or more and 300 μm or less, depending on the element configuration of the electrophoretic element 30.

Furthermore, in the porous layer 33 of the present embodiment, the reinforcing portion A is formed between the fibers on which the fibrous structures 34 are superimposed, in other words, in a proximity portion where the fibers are close to each other. The reinforcing portion A reinforces the three-dimensional structure of the fibrous structure 34 and improves the rigidity of the porous layer 33. For example, after the reinforcing portion A is mixed with a polymer for reinforcement including a binder and a curing agent in a polymer material constituting the fibrous structure 34 described later, for example, after spinning using an electrostatic spinning method, It is formed by heating to promote crosslinking of the reinforcing polymer. Alternatively, the reinforcing polymer solution may be prepared and applied to the surface of the fibrous structure 34 using an electrostatic coating method, and then heated to promote crosslinking of the reinforcing polymer.

When the reinforcing polymer is mixed, the fiber diameter becomes larger than the fibrous structure in the state where the reinforcing polymer is not mixed (see, for example, FIGS. 5A and 5B and FIGS. 6A and 6B). Thereby, the rigidity of the whole porous layer 33 improves. When the reinforcing polymer is applied to the surface of the fibrous structure 34, the smoothness of the surface is improved by covering the fibrous structure 34 with the reinforcing polymer, and migration when passing through the pores 36 is performed. The movement of the particles 32 is facilitated. Thereby, although the whole intensity | strength is lower than the case where it mixes, a response speed can be improved.

For the reinforcing polymer (binder and curing agent) forming the reinforcing portion A, a material capable of improving the strength of the fibrous structure 34 while maintaining the elasticity of the fibrous structure is used. preferable. Specifically, the binder includes vinyl chloride, vinyl acetate, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, acrylate ester-acrylonitrile copolymer. , Acrylic ester-vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, acrylic ester-acrylonitrile copolymer, acrylic ester-vinylidene chloride copolymer, methacrylic ester-vinylidene chloride copolymer , Methacrylate ester-vinyl chloride copolymer, methacrylate ester-ethylene copolymer, polyvinyl fluoride, vinylidene chloride-alrilonitrile copolymer, acrylonitrile-butadiene copolymer, polyamide resin, polyvinyl butyral, cellulose derivative Cellulose acetate butyrate, cellulose diacetate, cellulose triacetate, cellulose propionate, nitrocellulose), styrene-butadiene copolymer, polyester resin, amino resin, and the like. Examples of the curing agent include polyisocyanate, toluene diisocyanate, and adducts thereof, alkylene diisocyanate, adducts thereof and the like.

It should be noted that the load on the porous layer 33 in the manufacturing process is selected by selecting a material that can be crosslinked at a low temperature and in a short time (for example, 60 ° C., 2 hours) as the material of the reinforcing polymer for forming the reinforcing portion A. Is reduced.

The fibrous structure 34 is a fibrous substance having a sufficient length with respect to the fiber diameter (diameter). For example, a plurality of fibrous structures 34 are assembled and randomly overlapped to form the porous layer 33. One fibrous structure 34 may be entangled randomly to form the porous layer 33. Or the porous layer 33 by the one fibrous structure 34 and the porous layer 33 by the some fibrous structure 34 may be mixed.

The fibrous structure 34 extends, for example, in a straight line. The shape of the fibrous structure 34 may be any shape. For example, the fibrous structure 34 may be crimped or bent in the middle. Or the fibrous structure 34 may be branched on the way.

The fiber diameter of the fibrous structure 34 is preferably, for example, 50 nm or more and 2000 nm or less, but may be outside the above range. By reducing the average fiber diameter, light is easily diffusely reflected, and the pore diameter of the pores 36 is increased. The fiber diameter is determined so that the fibrous structure 34 can hold the non-migrating particles 35. The average fiber diameter can be measured, for example, by microscopic observation using a scanning electron microscope or the like. The average length of the fibrous structure 34 is arbitrary. The fibrous structure 34 is formed by, for example, a phase separation method, a phase inversion method, an electrostatic (electric field) spinning method, a melt spinning method, a wet spinning method, a dry spinning method, a gel spinning method, a sol-gel method, or a spray coating method. Is done. By using such a method, the fibrous structure 34 having a sufficient length with respect to the fiber diameter can be easily and stably formed.

The fibrous structure 34 can be made of a polymer material or an inorganic material. Among these, it is preferable to use nanofibers. Here, the nanofiber is a fibrous substance having a fiber diameter of 1 nm to 1000 nm and a length of 100 times or more of the fiber diameter. By using such nanofibers as the fibrous structure 34, light is easily diffusely reflected, and the reflectance of the porous layer 33 can be further improved. That is, the contrast of the electrophoretic element 30 can be improved. Further, in the fibrous structure 34 made of nanofibers, the proportion of the pores 36 in the unit volume increases, and the migrating particles 32 can easily move through the pores 36. Therefore, the energy required for moving the migrating particles 32 can be reduced. The fibrous structure 34 made of nanofibers is preferably formed by an electrostatic spinning method. By using the electrospinning method, the fibrous structure 34 having a small fiber diameter can be easily and stably formed.

It is preferable to use a fibrous structure 34 having a light reflectance different from that of the migrating particles 32. Thereby, a contrast due to a difference in light reflectance between the porous layer 33 and the migrating particles 32 is easily formed. A fibrous structure 34 showing light transparency (colorless and transparent) in the insulating liquid 31 may be used.

The pores 36 are configured by overlapping a plurality of fibrous structures 34 or tangling one fibrous structure 34. The pores 36 preferably have as large an average pore diameter as possible so that the migrating particles 32 can easily move through the pores 36. The average pore diameter of the pores 36 is, for example, not less than 0.1 μm and not more than 10 μm.

Non-electrophoretic particles 35 are one or more particles that are fixed to the fibrous structure 34 and do not undergo electrophoresis. The non-migrating particles 35 may be embedded in the held fibrous structure 34 or may partially protrude from the fibrous structure 34 (see FIGS. 5B and 6B).

As the non-electrophoretic particles 35, those having a light reflectance different from that of the electrophoretic particles 32 are used. The average particle diameter of the non-migrating particles 35 is preferably, for example, 50 nm or more and 1000 nm or less. The non-migrating particles 35 can be made of the same material as the migrating particles 32. Specifically, when the non-electrophoretic particles 35 (porous layer 33) display brightly, the material when the electrophoretic particles 32 display brightly, and when the non-electrophoretic particles 35 display darkly, the electrophoretic particles 32 darken. Each material for display can be used. When performing bright display by the porous layer 33, it is preferable that the non-migrating particles 35 are made of a metal oxide. Thereby, it is possible to obtain excellent chemical stability, fixability and light reflectivity. The constituent materials of the non-migrating particles 35 and the migrating particles 32 may be the same or different. The color visually recognized from the outside when the non-electrophoretic particle 35 performs bright display or dark display is the same as that described for the electrophoretic particle 32.

Further, the surface of the non-electrophoretic particle 35 may be modified with a surfactant. Surfactants are, for example, anionic (anionic) surfactants having a carboxylic acid, sulfonic acid or phosphoric acid structure as hydrophilic groups and cationic (cationic) properties having, for example, tetraalkylammonium or alkylamine as hydrophilic groups. Surfactant is mentioned. In addition, nonionic (nonionic) surfactants having a hydrophilic part as a non-electrolyte, that is, a non-ionized hydrophilic part, and amphoteric surfactants having both an anionic part and a cationic part in the molecule may be used. . Examples of amphoteric surfactants include alkyl dimethylamine oxide and alkyl carboxybetaine. In addition, when using metal materials, such as a titanium oxide, as the non-electrophoretic particle 35, it is preferable to use an anionic surfactant. In particular, a surfactant having a hydrophilic group with a small molecular volume such as carboxylic acid is preferable because it easily covers the entire surface of the non-electrophoretic particle 35. Further, it is desirable that the surfactant does not ooze into the insulating liquid 31 so that the display characteristics are not deteriorated for a long time.

The porous layer 33 can be formed by the following method, for example. FIG. 3A shows the flow of the formation procedure of the porous layer 33. First, as the non-electrophoretic particles 35, for example, titanium oxide having two types of primary particle sizes (for example, 250 nm (small particles) and, for example, 450 nm (large particles)) is prepared, and these are, for example, carboxylic acid anions. The organic surfactant is added to the organic solvent in which it has been dissolved and stirred. As a result, titanium oxide (non-electrophoretic particles 35) whose surface is coated with a carboxylic acid anionic surfactant is obtained (step S101). Next, for example, a constituent material of the fibrous structure 34 such as a polymer material (polymer) is dissolved in an organic solvent to prepare a solution, and then the non-electrophoretic particles 35 are sufficiently added to the solution. A spinning solution for stirring and dispersing the non-electrophoretic particles 35 is prepared (step S102). Subsequently, the spinning solution is spun by, for example, an electrostatic spinning method to form a fibrous structure 34 to which the non-migrating particles 35 are fixed (step S103). Here, the primary particle size is a minimum particle size. For example, when the particles are aggregated or bonded, the primary particle size represents the particle size of each particle.

Next, the reinforcing part A is formed on the fibrous structure 34. First, as a binder, for example, a vinyl chloride copolymer resin and a curing agent, for example, an isocyanate curing agent is dissolved in N, N′-dimethylformamide (DMF) to prepare a reinforcing polymer solution. This reinforcing polymer solution is put into a syringe and electrostatically applied to the fibrous structure 34 (step S104). After that, the film substrate is heated to promote the crosslinking reaction between the binder and the curing agent, thereby forming the porous layer 33 having the reinforcing portion A (step S105). The reinforcing polymer solution has a fibrous structure that does not fill the voids of the fibrous structure 34, that is, does not narrow the pore diameter of the fibrous structure 34, by setting the diameter and weight of the coating droplets within a predetermined range. 34 can be coated.

Thus, the dispersibility of the non-migrating particles 35 in the spinning solution is improved by using the non-migrating particles 35 previously modified with a surfactant. As a result, an electric field is easily applied to the non-migrating particles 35 during spinning, and a fibrous structure 34 with a reduced fiber diameter, that is, a fine fiber is obtained.

In addition, although the example which forms the reinforcement part A in the display surface side of the porous layer 33 was shown here, you may make it provide the reinforcement part A uniformly in the whole porous layer 33 besides this. In that case, for example, the porous layer 33 has a multilayer structure (for example, a three-layer structure (first layer 33A, second layer 33B, and third layer 33C) as shown in FIG. 2), and the fibers of each layer. Each time the shaped structure 34 is spun, the reinforcing polymer solution may be electrostatically coated and then heated to form the reinforcing portion A. Or you may make it form the reinforcement part A like the flow of the formation procedure of the porous layer 33 shown to FIG. 3B. Specifically, after adjusting the non-migrating particles 35 using the same method as in step S101 (step 201), the organic solvent is made of, for example, a constituent material of the fibrous structure 34 such as a polymer material (polymer). Is dissolved to prepare a solution. Subsequently, a reinforcing polymer (a binder and a curing agent) is added to the solution together with the non-electrophoretic particles 35 and sufficiently stirred to prepare a mixed spinning solution in which the non-electrophoretic particles 35 and the reinforcing polymer are dispersed ( Step S202). Next, the spinning solution is spun by, for example, an electrostatic spinning method to form a fibrous structure 34 in which the non-migrating particles 35 are fixed and the reinforcing polymer is mixed (step S103). Subsequently, the fibrous structure 34 is heated to promote the crosslinking reaction of the binder and the curing agent, which are reinforcing polymers, to form the porous layer 33 having the reinforcing portion A (step S204).

In addition, the porous layer 33 may be formed by forming holes in the polymer film by using a laser, and a cloth knitted with a synthetic fiber or the like on the porous layer 33, Alternatively, open-cell porous polymer may be used.

The fibrous structure is preferably composed of molecules having a main skeleton (main part of the molecule) composed of, for example, carbon atoms, oxygen atoms and hydrogen atoms. In other words, the main skeleton of this molecule does not contain atoms other than carbon atoms, oxygen atoms, and hydrogen atoms, and consists only of these atoms. Such molecules forming the fibrous structure 34 preferably do not contain a highly polar functional group such as a hydroxyl group and a carboxylic acid group. Thereby, the absolute value of the surface potential of the fibrous structure 34 becomes small, and the response speed of the electrophoretic element 30 can be improved. Here, the main skeleton refers to a portion excluding both ends of the molecule. The molecules forming the fibrous structure 34 are preferably composed of carbon atoms, oxygen atoms and hydrogen atoms up to both ends, but the ends contain atoms other than these carbon atoms, oxygen atoms and hydrogen atoms. May be. For example, when a polymer is synthesized by radical polymerization, a polymerization initiator such as azobisisobutyronitrile (AIBN) is used as a catalyst. Nitrogen atoms and the like are contained at both ends of the polymer synthesized in this way, but the atoms at the ends are less than 1/1000 of the whole molecule in terms of molecular weight. Therefore, this terminal atom contributes little to the properties of the molecule. The same applies to polymerization initiators other than AIBN. Thus, the reactivity of the fibrous structure 34 composed of only carbon atoms, oxygen atoms, and hydrogen atoms is low, so that the fibrous structure 34 exists stably in the insulating liquid 31. Therefore, the electrophoretic element 30 can obtain high reliability.

The molecule forming the fibrous structure 34 is a chain polymer. Here, a chain molecule (chain molecule) refers to a molecule that does not include a cyclic atomic arrangement structure. Examples of the cyclic atomic arrangement include a monocyclic compound and a heterocyclic compound. Monocyclic compounds are composed of a single element, and specifically include aromatic compounds, cycloalkenes, cycloalkanes, cycloalkynes, and the like. The heterocyclic compound is composed of two or more kinds of elements, and specifically includes pyrrole, carbazole, cyclic acetal, pyran, furan and thiophene. The chain molecule may be linear or branched. When the fibrous structure 34 is composed of chain molecules, since the steric hindrance is smaller than that of a molecule including a cyclic structure, the migrating particles 32 are easily moved, and the contrast and response speed of the electrophoretic element 30 are improved. To do.

The chain molecule constituting the fibrous structure 34 includes an ester group. For example, the fibrous structure 34 is preferably formed from an acrylic resin. Specific examples of the chain molecule include polyalkyl methacrylate, polyalkyl acrylate, polyalkenyl methacrylate, polyalkenyl acrylate, polyalkynyl methacrylate and polyalkynyl acrylate. This chain molecule does not have a functional group having a polarity higher than that of the ester group, and the absolute value of the surface potential of the fibrous structure 34 is, for example, 20 mV or less. It is more preferable to select chain molecules so that the absolute value of the surface potential of the fibrous structure 34 is 10 mV or less. That is, the ester group has a smaller polarity than the cyano group and the like, but this is sufficiently large for spinning using the electrospinning method, and the fibrous structure 34 can be easily formed by the electrospinning method. can do.

For the chain molecule constituting the fibrous structure 34, it is preferable to use a material that is not easily decomposed by microorganisms. That is, the chain molecule is preferably resistant to biodegradation. Examples of the biodegradable polymer include polylactic acid, polyvinyl alcohol, cellulose acetate, collagen, gelatin, and chitosan. Since such a polymer is easily decomposed, there is a possibility that the characteristics of the fibrous structure cannot be maintained when some kind of stimulus is applied to the electrophoretic element from the outside. In addition, many of such polymers are water-soluble and may be dissolved by moisture in the electrophoretic element, so that the shape of the fibrous structure cannot be maintained. On the other hand, when the fibrous structure 34 is formed of chain molecules having resistance to biodegradation, the stability of the fibrous structure 34 is increased. Therefore, the reliability of the electrophoretic element 30 can be improved. The surface of the fibrous structure 34 may be covered with an arbitrary protective layer.

(1-2. Configuration of display device)
Next, the overall configuration and operation principle of the display device 1 will be described.

2, 4A and 4B show an example of a cross-sectional configuration of the display device 1 using the electrophoretic element 30. FIG. The display device 1 is an electrophoretic display (so-called electronic paper display) that displays an image (for example, character information) using an electrophoretic phenomenon, and an electrophoretic element between a driving substrate 10 and a counter substrate 20. 30 is provided. The space between the driving substrate 10 and the counter substrate 20 is adjusted to a predetermined distance by the spacer 40.

The drive substrate 10 includes, for example, a TFT (Thin Film Transistor) 12, a protective layer 13, a pixel electrode 14, and an adhesive layer 15 in this order on one surface of the support member 11. For example, the TFT 12 and the pixel electrode 14 are arranged in a matrix or a segment according to the pixel arrangement.

The support member 11 is made of, for example, an inorganic material, a metal material, a plastic material, or the like. Examples of the inorganic material include silicon (Si), silicon oxide (SiOx), silicon nitride (SiNx), and aluminum oxide (AlOx). Silicon oxide includes glass or spin-on-glass (SOG). Examples of the metal material include aluminum (Al), nickel (Ni), and stainless steel, and examples of the plastic material include polycarbonate (PC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polyethyl ether. Ketone (PEEK) etc. are mentioned.

Since the display device 1 displays an image on the counter substrate 20 side, the support member 11 may be non-light transmissive. The support member 11 may be configured by a rigid substrate such as a wafer, or may be configured by a flexible thin glass or film. By using a flexible material for the support member 11, the flexible display device 1 can be realized.

TFT 12 is a switching element for selecting a pixel. The TFT 12 may be an inorganic TFT using an inorganic semiconductor layer as a channel layer, or an organic TFT using an organic semiconductor layer. The protective layer 13 and the adhesive layer 15 are made of, for example, an insulating resin material such as polyimide. If the surface of the protective layer 13 is sufficiently flat, the adhesive layer 15 can be omitted. The pixel electrode 14 is made of a metal material such as gold (Au), silver (Ag), or copper (Cu). The pixel electrode 14 is connected to the TFT 12 through a contact hole (not shown) provided in the protective layer 13 and the adhesive layer 15.

The counter substrate 20 includes, for example, a support member 21 and a counter electrode 22, and the counter electrode 22 is provided on the entire surface of the support member 21 (a surface facing the drive substrate 10). Similarly to the pixel electrode 14, the counter electrode 22 may be arranged in a matrix or a segment.

The support member 21 is made of the same material as the support member 11 except that it is light transmissive. For the counter electrode 22, for example, a light-transmitting conductive material such as indium oxide-tin oxide (ITO), antimony oxide-tin oxide (ATO), fluorine-doped tin oxide (FTO), or aluminum-doped zinc oxide (AZO). (Transparent electrode material) can be used.

When displaying an image on the counter substrate 20 side, since the electrophoretic element 30 is viewed through the counter electrode 22, the light transmittance (transmittance) of the counter electrode 22 is preferably as high as possible. 80% or more. Further, the electrical resistance of the counter electrode 22 is preferably as low as possible, for example, 100Ω / □ or less.

The electrophoretic element 30 includes an electrophoretic particle 32 and a porous layer 33 having a plurality of pores 36 in an insulating liquid 31. The insulating liquid 31 is filled in the space between the driving substrate 10 and the counter substrate 20, and the porous layer 33 is supported by the spacer 40, for example. The space filled with the insulating liquid 31 is divided into, for example, a retreat area R1 closer to the pixel electrode 14 and a display area R2 closer to the counter electrode 22 with the porous layer 33 as a boundary. . The configurations of the insulating liquid 31, the migrating particles 32, and the porous layer 33 are the same as those described in the above embodiments and the like. In FIG. 4A and later-described FIG. 4B, the pores 36 are omitted in order to simplify the illustrated contents.

The porous layer 33 may be adjacent to one of the pixel electrode 14 and the counter electrode 22, and the retreat area R1 and the display area R2 may not be clearly separated. The migrating particles 32 move toward the pixel electrode 14 or the counter electrode 22 according to the electric field.

The thickness of the spacer 40 is, for example, 10 μm to 100 μm, and is preferably as thin as possible. Thereby, power consumption can be suppressed. The spacer 40 is made of, for example, an insulating material such as a polymer material, and is provided, for example, in a lattice shape between the drive substrate 10 and the counter substrate 20. The arrangement shape of the spacer 40 is not particularly limited, but it is preferable that the spacer 40 is provided so as not to disturb the movement of the migrating particles 32 and to uniformly distribute the migrating particles 32.

In the display device 1 in the initial state, the migrating particles 32 are arranged in the retreat area R1 (FIG. 4A). In this case, since the migrating particles 32 are shielded by the porous layer 33 in all the pixels, no contrast is generated when the electrophoretic element 30 is viewed from the counter substrate 20 side (an image is not displayed). Is in a state.

On the other hand, when a pixel is selected by the TFT 12 and an electric field is applied between the pixel electrode 14 and the counter electrode 22, as shown in FIG. 4B, the migrating particles 32 are moved from the retreat area R1 to the porous layer 33 for each pixel. It moves to display area R2 via (pore 36). In this case, since the pixels in which the migrating particles 32 are shielded by the porous layer 33 and the pixels that are not shielded coexist, when the electrophoretic element 30 is viewed from the counter substrate 20 side, a contrast is generated. become. Thereby, an image is displayed.

In addition, according to the display device 1, the electrophoretic element 30 having a high response speed can display a high-quality image suitable for, for example, colorization and moving image display.

In general electrophoretic displays, as described above, contrast is generated by the difference between the light reflectance of the migrating particles and the light reflectance of the porous layer. Specifically, among the migrating particles and the porous layer, the light reflectance for bright display is higher than the light reflectance for dark display. It is preferable that the light reflectance of the non-electrophoretic particles is higher than that of the electrophoretic particles so that the porous layer displays light and the electrophoretic particles display dark. By performing such a display, the light reflectance at the time of bright display is remarkably increased by utilizing the irregular reflection of light by the porous layer (three-dimensional structure). Accordingly, the contrast is remarkably improved accordingly.

In the electrophoretic element, the electrophoretic particles move through the pores of the porous layer within the range where the electric field is applied. Depending on the area where the migrating particles have moved or not moved, either bright display or dark display is performed, and an image is displayed.

However, in an electrophoretic display having a porous layer between a pair of electrodes (for example, the pixel electrode 14 and the counter electrode 22 in FIG. 2), as described above, by bending or pressing the display screen The porous layer is deformed. In particular, when the porous layer is composed of a fibrous structure, there is a problem that the fiber structure is deformed, the pore diameter is reduced, and the responsiveness is deteriorated. It was. For this reason, it is conceivable to form a highly rigid fibrous structure using a polymer material. In this case, however, the fiber diameter becomes thick, and the scattering efficiency may be lowered, resulting in a deterioration in contrast.

On the other hand, in the electrophoretic element 30 and the manufacturing method thereof according to the present embodiment, and the display device 1 including the same, the rigidity of the porous layer 33 is added to the fibrous structure 34 constituting the porous layer 33. The reinforcing part A to be improved is formed. Specifically, the reinforcing polymer solution was applied to the fibrous structure 34, or when the fibrous structure was formed, the reinforcing polymer was added to the spinning solution to form the reinforcing portion A. The reinforcing part A is formed by heating after spinning to promote the crosslinking reaction of the reinforcing polymer (binder and curing agent).

5A and 5B schematically show actual shapes of a general fibrous structure (FIG. 5A) and the fibrous structure 34 of the present embodiment (FIG. 5B). 6A is an enlarged schematic view of the fibrous structure shown in FIG. 5A, and FIG. 6B is an enlarged schematic view of the fibrous structure 34 shown in FIG. 5B. By mixing or applying the reinforcing polymer to the fibrous structure 34, as shown in FIGS. 5B and 6B, the fiber diameter of the fibrous structure 34 is increased and the strength of the fiber itself is improved. Further, the reinforcing portion A is formed between adjacent fibers by crosslinking of the reinforcing polymer, and the rigidity of the fibrous structure 34, that is, the rigidity of the porous layer 33 is improved. Further, when the reinforcing polymer is applied, not only the fibrous structure 34 but also the non-migrating particles 35 held by the fibrous structure 34 are coated, thereby improving the smoothness of the surface and reducing the pores. The moving speed of the migrating particles 32 moving in the 36 is further improved.

As described above, in the electrophoretic element 30 of the present embodiment, the manufacturing method thereof, and the display device 1 including the same, the reinforcing polymer is applied to the fibrous structure 34 constituting the porous layer 33, or the fibers The reinforcing polymer was added to the spinning solution forming the fibrous structure 34 and spun, and the reinforcing part A was provided in the vicinity of the fibers constituting the fibrous structure 34. Thereby, the rigidity of the porous layer 33 is improved, and the pore diameter of the pores 36 formed by the three-dimensional structure of the fibrous structure 34 can be maintained against bending or pressing of the display screen. That is, the durability of the porous layer 33 is improved. Thus, a display device with improved reliability can be provided.

Furthermore, the smoothness of the surface of the fibrous structure 34 is improved by applying the reinforcing polymer to the fibrous structure 34. Thereby, it becomes possible to improve the responsiveness while improving the strength of the porous layer 33. That is, a display device with improved reliability and display characteristics can be provided.

<2. Application example>
Next, an application example of the display device 1 will be described.

The display device 1 of the present technology can be applied to electronic devices for various uses, and the type of the electronic device is not particularly limited. This display device 1 can be mounted on, for example, the following electronic devices. However, the configuration of the electronic device described below is merely an example, and the configuration can be changed as appropriate.

(Application example 1)
7A and 7B show the external configuration of the electronic book. The electronic book includes, for example, a display unit 110, a non-display unit 120, and an operation unit 130. Note that the operation unit 130 may be provided on the front surface of the non-display unit 120 as illustrated in FIG. 7A, or may be provided on the upper surface as illustrated in FIG. 7B. The display unit 110 is configured by the display device 1. The display device 1 may be mounted on a PDA (Personal Digital Assistants) having the same configuration as the electronic book shown in FIGS. 7A and 7B.

(Application example 2)
FIG. 8 shows the appearance of a tablet personal computer. The tablet personal computer has, for example, a touch panel unit 310 and a housing 320, and the touch panel unit 310 is configured by the display device 1.

<3. Example>
Next, embodiments of the present technology will be described in detail.

Display devices (Experimental Examples 1 to 10) were prepared using black (dark display) migrating particles and a white (bright display) porous layer (particle-containing fibrous structure) by the following procedure.

(Experimental example 1)
(Preparation of migrating particles)
First, a mixed solution of 400 ml of tetrahydrofuran and 400 ml of methanol was prepared, and then 50 g of composite oxide fine particles (copper-iron-manganese oxide: Daipi Seika Kogyo Co., Ltd. Daipyroxide Side Color TM9550) were added to the solution. Ultrasonic stirring (at 25 ° C. to 35 ° C. for 30 minutes) was performed in an ultrasonic bath. Next, 40 ml of 28% ammonia water was added dropwise to the dispersion of the composite oxide fine particles over 30 minutes, and then a solution in which 10 g of preneact KR-TTS (manufactured by Ajinomoto Fine Techno Co., Ltd.) was dissolved in 80 ml of tetrahydrofuran was added over 30 minutes. And dripped. Subsequently, the ultrasonic bath was heated to 60 ° C. and held for 3 hours, and then cooled to room temperature, followed by centrifugation (at 6000 rpm for 10 minutes) and decantation. Next, the precipitate after the decantation was redispersed in a mixed solvent of tetrahydrofuran and methanol (volume ratio 1: 1), and centrifuged (at 6000 rpm for 10 minutes) and decantation again. The precipitate obtained by repeating this washing operation three times was dried overnight in a vacuum oven at 70 ° C. As a result, black electrophoretic particles coated with a dispersing group were obtained.

(Preparation of insulating liquid)
After preparing the migrating particles, 16.7 g of OLOA 1200 (manufactured by Chevron Chemicals) was dissolved in 83.3 g of the insulating liquid to prepare an OLOA 1200 solution. 1 g of the migrating particles was added to 9 g of this OLOA 1200 solution, and ultrasonic dispersion was performed. This dispersion was centrifuged (at 6000 rpm for 90 minutes) and decanted, and then redispersed in an insulating liquid. This operation was repeated 3 times, and the resulting electrophoretic particle component in the dispersion liquid was adjusted to 10% by weight. Subsequently, OLOA 1200 1 g, ADDOCONATE S (manufactured by Lubrizol) 10 g and the above dispersion 20 g were added to 69 g of insulating liquid and stirred to obtain an insulating liquid containing additives and migrating particles.

(Preparation of fibrous structure)
A solution D was prepared by dissolving 14 g of polymethyl methacrylate, which is a material for forming a fibrous structure, in 86 g of N, N′-dimethylformamide. Subsequently, 30 g of titanium oxide (primary particle size 250 nm) as non-electrophoretic particles was added to 70 g of the solution D, and then mixed with a bead mill to prepare a spinning solution E. Next, this spinning solution E is put in a syringe, and on a PET film having a counter electrode (ITO) formed on the entire surface thereof, a UV resin is provided with a pitch of 30 μm in height, 10 μm in width, and 200 μm in pitch. Spinning with a basis weight of 1.2 mg / cm ² was performed using an electrospinning apparatus (NANON manufactured by MEC Co., Ltd.).

(Preparation of polymer for reinforcement)
30 g of vinyl chloride copolymer resin (MR-110 cyclohexanone 30 wt% solution manufactured by Nippon Zeon Co., Ltd.) and 0.9 g of isocyanate curing agent (Coronate L-50 50 wt% manufactured by Nippon Polyurethane Industry Co., Ltd.), which are forming materials for reinforcing binders (5 parts by weight) and 50 g of N, N′-dimethylformamide were mixed to prepare a fiber reinforcing polymer solution F. Subsequently, the fiber reinforcing polymer solution F is put into a syringe, and, for example, the fibrous structure placed on the ITO PET film (film substrate) is electrostatically charged with a basis weight of 0.1 mg / cm ² using an electrospinning device. Application was performed. Further, this film substrate was placed in an oven at 70 ° C. for 2 hours to promote the crosslinking reaction.

(Assembly of display device)
The film substrate in which the fibrous structure and the reinforcing polymer are coated on the lattice-like ribs is subjected to nip treatment 8 times with a metal roll at a linear pressure of 16 kgf / cm and a treatment speed of 6 m / min. Filled between rib lattices. This was overlaid with an ITO PET film serving as a counter electrode. A photocurable resin (photosensitive resin Photorec A-400 manufactured by Sekisui Chemical Co., Ltd.) containing beads (outer diameter = 30 μm) was drawn along the outer periphery of the superimposed film. Subsequently, an insulating liquid in which electrophoretic particles were dispersed was injected between two ITO PET film substrates. Finally, the photocurable resin was cured by irradiation with ultraviolet light. The gap between the superimposed films was kept at 30 μm with beads mixed with ribs and a photocurable resin.

(Experimental example 2)
It was produced in the same manner as in Experimental Example 1 except that the amount of the isocyanate curing agent as the reinforcing polymer was 1.8 g (10 parts by weight).

(Experimental example 3)
It was produced in the same manner as in Experimental Example 1 except that the amount of the isocyanate curing agent as the reinforcing polymer was 3.6 g (20 parts by weight).

(Experimental example 4)
It was produced in the same manner as in Experimental Example 1 except that the amount of the isocyanate curing agent as the reinforcing polymer was 5.4 g (30 parts by weight).

(Experimental example 5)
It was produced in the same manner as in Experimental Example 1 except that the amount of the isocyanate curing agent as the reinforcing polymer was 0.54 g (3 parts by weight).

(Experimental example 6)
It was produced in the same manner as in Experimental Example 1 except that the amount of the isocyanate-based curing agent as the reinforcing polymer was 3.6 g (20 parts by weight) and the electrostatic coating amount of the reinforcing polymer was 0.05 mg / cm ² . .

(Experimental example 7)
It was produced in the same manner as in Experimental Example 1 except that the amount of the isocyanate-based curing agent as the reinforcing polymer was 3.6 g (20 parts by weight) and the electrostatic coating amount of the reinforcing polymer was 0.30 mg / cm ² . .

(Experimental example 8)
The amount of the isocyanate curing agent as the reinforcing polymer was 3.6 g (20 parts by weight), and the reinforcing polymer was 0.1 mg / cm ² electrostatically coated when the fibrous structure was spun at 0.6 mg / cm ^2. This was prepared in the same manner as in Experimental Example 1 except that the fibrous structure was spun at 0.6 mg / cm ² from above and the reinforcing polymer was electrostatically applied to the intermediate layer of the fibrous structure.

(Experimental example 9)
It was produced in the same manner as in Experimental Example 1 except that the reinforcing portion was not formed with the reinforcing polymer.

(Experimental example 10)
Polymethyl methacrylate, which is a material for forming a fibrous structure, and a vinyl chloride copolymer resin and an isocyanate curing agent (20 parts by weight) mixed at a ratio of 70:30 to make 14 g, N, Solution G was prepared by dissolving in 86 g of N′-dimethylformamide. 30 g of non-migrating particles (titanium oxide (primary particle size 250 nm)) were added to 70 g of this solution G, and then mixed by a bead mill to prepare a spinning solution H. Subsequently, after spinning the spinning solution H in the same manner as in Experimental Example 1 to form a fibrous structure, the film substrate on which the fibrous structure was formed was placed in an oven at 70 ° C. for 2 hours to promote the crosslinking reaction. I let you. Other than the above, it was fabricated in the same manner as in Experimental Example 1. In addition, the compounding ratio of the reinforcing polymer to the polymer constituting the fibrous structure in this experimental example is 30 parts by weight.

As the performance of the display devices of Experimental Examples 1 to 10, the fiber diameter of the fibrous structure was measured, and the white reflectance (%), black reflectance (%), contrast (CR), average mobility (μm ²⁾ / V · ms) and the number of defective cells. Table 1 summarizes the configurations of Experimental Examples 1 to 10, and Table 2 summarizes the measurement results. Each measurement item was measured as follows.

(Reflectance measurement)
First, after applying an alternating voltage (0.1 Hz and 15 V) for 1 hour, white reflectance (%) and black reflectance (%) were measured, and contrast = white reflectance / black reflectance was calculated. Here, using a spectrophotometer (eye-one pro manufactured by X-Rite Co., Ltd.), the white reflectance and black reflectance in the normal direction of the substrate with respect to the standard diffuser plate were measured with 45 ° -0 ° ring illumination.

(Average mobility measurement)
First, brightness was measured using a function generator (manufactured by Toyo Technica Co., Ltd.) while applying a rectangular wave electric field (15 V). Here, the luminance in the white state = 1, the luminance in the black state = 0, the time required for the luminance to change from 0.1 to 0.9 by applying the electric field, and the electric field application are stopped, and the luminance is 0. The average value (response time (ms)) with the time required to change from 9 to 0.1 was calculated. Further, by measuring the actual gap of the fabricated cell, calculating the average response time (ms / μm), converting the applied voltage 15V to unit electric field strength (V / μm), and then dividing the average response time, The average mobility (μm ² / V · ms) of the migrating particles was calculated.

(Defect cell count measurement)
As a measurement of the number of defective cells, a stylus pushing test was performed using a tensile tester (MX2-500N-FA manufactured by Imada Co., Ltd.). The tip is a stylus pen (R = 0.7 mm, manufactured by Sony Corporation), the load is 10 N, the pushing speed is 30 times / minute, the display element is tapped 10 times, and then white display and black display are performed. The number of defective cells was measured with a cell that was not reversed (lattice size 200 μm) as a defective cell.

(Fiber diameter measurement)
The average fiber diameter, the maximum fiber diameter, and the minimum fiber diameter of the fibrous structure are 80 measurement points, and the fiber of the fibrous structure is 5,000 times the field emission scanning electron microscope FFE-SEM (S4800, manufactured by Hitachi High-Technology Corporation). The diameter was measured.

As can be seen from Table 2, in Experimental Examples 1 to 3, the number of defective cells was 1 or 2 which was very small compared to Experimental Example 9 in which no reinforcing portion was provided. This is considered to be because the rigidity of the fibrous structure is improved by the crosslinking of the reinforcing polymer. In addition, the average mobility was higher than that of Experimental Example 9. This is presumably because the unevenness of the fiber diameter was reduced by the application of the reinforcing polymer, and the migration of the migrating particles became smooth.

On the other hand, in Example 4, the number of defective cells was as small as one and the effect of crosslinking the reinforcing polymer was observed, but the black reflectance was high and the contrast was lowered. The average mobility was also low. This is because the amount of the curing agent contained in the reinforcing polymer is large and the viscosity of the paint is high, so that it cannot be applied finely in the electrostatic coating process. As a result, the fiber diameter of the portion where the reinforcing polymer is applied This is thought to be because the movement of the migrating particles was hindered by the increase in the thickness. In Experimental Examples 5 and 6, the number of defective cells was relatively large. In Experimental Example 5, the amount of the curing agent added was small, so that the isocyanate group of the curing agent reacted with moisture in the solution or in the atmosphere, so that the urethanization reaction was not sufficiently performed, and the reinforcing effect was insufficient. It is thought that it was because of. In Experimental Example 6, since the amount of the reinforcing polymer applied was small, it is considered that the fibrous structure was not sufficiently reinforced. In Experimental Example 7, although the number of defective cells was small, white reflectance, black reflectance, contrast, and average mobility decreased. This is presumably because the fiber diameter of the fiber portion to which the reinforcing polymer was applied became too thick due to the large amount of the reinforcing polymer applied.

In Experimental Example 8 in which the reinforcing polymer was applied to the inside and intermediate layer of the porous layer, the number of defective cells was very small at two. This shows that the rigidity of the fibrous structure is improved and the durability is improved even when the reinforcing polymer is provided inside the fibrous structure.

In Experimental Example 10, a reinforcing polymer was mixed in a fibrous structure, but it was defective as in Experimental Examples 1 to 4 and Experimental Examples 7 and 8 in which the reinforcing polymer was applied to the surface of the fibrous structure. The number of cells was two and very small. On the other hand, the average mobility was low. This is presumably because the viscosity of the spinning solution was increased by mixing the reinforcing polymer, and the fiber diameter of the fibrous structure was increased.

Although the present technology has been described with reference to the embodiments and examples, the present technology is not limited to the above-described embodiments and the like, and various modifications are possible.

In addition, the effect described in this specification is an illustration to the last, and is not limited, Moreover, there may exist another effect.

In addition, this technique can also take the following structures.
(1) Electrophoretic particles, a fibrous structure formed by superimposing one or more fibers in an insulating liquid, and a porous layer formed by non-electrophoretic particles held by the fibrous structure The fibrous structure includes an electrophoretic element having a reinforcing portion in at least a part of a proximity portion between the fibers.
(2) The electrophoretic element according to (1), wherein the reinforcing portion is formed of a reinforcing polymer.
(3) The electrophoretic device according to (2), wherein the reinforcing polymer is a binder and a curing agent.
(4) The fiber in the proximity portion of the fibrous structure is covered with the reinforcing polymer and connected to each other, as described in any one of (2) and (3) Electrophoretic element.
(5) The electrophoretic element according to any one of (2) to (4), wherein the fiber is mixed with the reinforcing polymer.
(6) The electrophoretic element according to any one of (1) to (5), wherein an average pore diameter of the fibrous structure is 0.1 μm or more and 10 μm or less.
(7) The electrophoretic element according to (1), wherein the fibrous structure has a fiber diameter of 50 nm to 2000 nm.
(8) The electrophoretic element according to any one of (1) to (7), wherein the fibrous structure is formed of a polymer material or an inorganic material.
(9) The electrophoretic element according to any one of (1) to (8), wherein the fibrous structure is configured by nanofibers.
(10) The electrophoretic element according to any one of (1) to (9), wherein the fibrous structure is formed by an antistatic method.
(11) The electrophoretic element according to any one of (1) to (10), wherein the non-electrophoretic particle has an optical reflection characteristic different from that of the electrophoretic particle.
(12) The migrating particles and the non-migrating particles are composed of at least one of an organic pigment, an inorganic pigment, a dye, a carbon material, a metal material, a metal oxide, glass, and a polymer material. The electrophoretic device according to any one of (1) to (11). (13) The electrophoretic element according to any one of (1) to (12), wherein the non-electrophoretic particles include titanium oxide.
(14) The light reflectance of the non-electrophoretic particles is higher than the light reflectance of the electrophoretic particles, the electrophoretic particles perform dark display, and the non-electrophoretic particles and the porous layer perform light display. (13) The electrophoretic device according to any one of (13).
(15) Electricity including a step of forming electrophoretic particles, a step of mixing non-electrophoretic particles to form a fibrous structure constituting a porous layer, and a step of forming a reinforcing portion in the fibrous structure. Manufacturing method of electrophoretic element.
(16) The method for manufacturing an electrophoretic element according to (15), wherein the reinforcing portion is formed by electrostatically applying a reinforcing polymer to the fibrous structure and then heating.
(17) The electrophoretic element according to (15) or (16), wherein the reinforcing portion is formed by mixing a reinforcing polymer together with the non-electrophoretic particles to form the fibrous structure and then heating. Manufacturing method.
(18) It has a plurality of electrophoretic elements, and the electrophoretic element includes a fibrous structure formed by superimposing electrophoretic particles and one or more fibers in an insulating liquid, and the fibrous structure. And a porous layer formed of held non-electrophoretic particles, wherein the fibrous structure has a reinforcing portion in at least a part of a proximity portion between the fibers.

This application claims priority on the basis of Japanese Patent Application No. 2015-26730 filed on February 13, 2015 at the Japan Patent Office. The entire contents of this application are hereby incorporated by reference. Incorporated into.

Those skilled in the art will envision various modifications, combinations, subcombinations, and changes, depending on design requirements and other factors, which are within the scope of the appended claims and their equivalents. It is understood that

Claims (18)

1. In insulating liquid,
   Electrophoretic particles,
   A fibrous structure formed by superimposing one or more fibers and a porous layer formed by non-electrophoretic particles held by the fibrous structure;
   The fibrous structure is an electrophoretic element having a reinforcing portion in at least a part of a proximity portion between the fibers.
2. 2. The electrophoretic element according to claim 1, wherein the reinforcing portion is formed of a reinforcing polymer.
3. The electrophoretic element according to claim 2, wherein the reinforcing polymer is a binder and a curing agent.
4. 3. The electrophoretic element according to claim 2, wherein the fibers in the proximity portion of the fibrous structure are covered with the reinforcing polymer and connected to each other.
5. The electrophoretic element according to claim 2, wherein the fiber is mixed with the reinforcing polymer.
6. The electrophoretic element according to claim 1, wherein the fibrous structure has an average pore diameter of 0.1 μm or more and 10 μm or less.
7. The electrophoretic element according to claim 1, wherein the fibrous structure has a fiber diameter of 50 nm or more and 2000 nm or less.
8. 2. The electrophoretic element according to claim 1, wherein the fibrous structure is formed of a polymer material or an inorganic material.
9. The electrophoretic element according to claim 1, wherein the fibrous structure is composed of nanofibers.
10. The electrophoretic element according to claim 1, wherein the fibrous structure is formed by an antistatic method.
11. The electrophoretic element according to claim 1, wherein the non-electrophoretic particles have optical reflection characteristics different from those of the electrophoretic particles.
12. The electrophoretic particles and the non-electrophoretic particles are composed of at least one of an organic pigment, an inorganic pigment, a dye, a carbon material, a metal material, a metal oxide, glass, and a polymer material. The electrophoretic element according to 1.
13. The electrophoretic element according to claim 1, wherein the non-electrophoretic particles include titanium oxide.
14. 2. The electrophoresis according to claim 1, wherein the light reflectance of the non-electrophoretic particles is higher than the light reflectance of the electrophoretic particles, the electrophoretic particles perform dark display, and the non-electrophoretic particles and the porous layer perform light display. element.
15. Forming electrophoretic particles;
    Mixing non-electrophoretic particles to form a fibrous structure constituting the porous layer;
    Forming a reinforcing portion on the fibrous structure.
16. The method for producing an electrophoretic element according to claim 15, wherein the reinforcing portion is formed by electrostatically applying a reinforcing polymer to the fibrous structure and then heating.
17. The method of manufacturing an electrophoretic element according to claim 15, wherein the reinforcing portion is formed by mixing a non-electrophoretic particle together with a reinforcing polymer to form the fibrous structure and then heating.
18. Having a plurality of electrophoretic elements,
    The electrophoretic element is:
    In insulating liquid,
    Electrophoretic particles,
    A fibrous structure formed by superimposing one or more fibers and a porous layer formed by non-electrophoretic particles held by the fibrous structure;
    The said fibrous structure has a reinforcement part in at least one part of the proximity | contact part of the said fibers. Display apparatus.

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