JP2003186056A - Method of manufacturing colored rotational particles and method of manufacturing display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the agglomeration of pigment in a resin in a manufacturing process for colored rotational particles thereby adjusting the color tone of pigment, more particularly increasing the whiteness thereof and preventing the occurrence of the uncolored areas of colored resin. <P>SOLUTION: The surface of the pigment 1 is coated with a coating resin 2 to make the coated pigment 3 and the colored resin is formed by dispersing the coated pigments 3 into a dispersing resin 4. As a result, the surfaces of the coated pigments 3 and the boundary of the dispersing resin 4 are made into the resins with each other and the agglomeration of the pigment is prevented. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a device having different surfaces.
The present invention relates to a method of manufacturing colored rotating particles that are color-coded and that rotate by the action of an electric field to display a surface of a corresponding color and a method of manufacturing a display device.

[0002]

2. Description of the Related Art In recent years, with the development of portable information terminals and advanced information communication networks, attention has been focused on the development of thin, lightweight, and highly portable display devices. Among them, so-called electronic devices that display images by changing the optical absorption characteristics and optical reflection characteristics by an electric field and have the function of easily rewriting electronic information in addition to the flexibility equivalent to paper. Paper, paper-like display,
Also, expectations for display devices called digital paper and the like are increasing.

As a display element which changes its optical absorption characteristics and optical reflection characteristics by the application of an electric field, microcapsules containing rotating particles including hemispheres having different colors and electrical characteristics together with a dielectric liquid, Japanese Patent Application Sho 62-24
As disclosed in Japanese Patent No. 4679, there is a microcapsule obtained by coloring a solvent in which electrophoretic particles are dispersed and encapsulating the solvent, a liquid crystal / polymer composite film containing a dichroic dye and a smectic liquid crystal, and the like.

These display elements have characteristics such as a memory property capable of holding image information without a power source and a reflective display, and the display elements can be formed on a PET film having electrodes. Therefore, it is a thin, light, and bendable sheet-type display device, and is expected as a substitute for paper.

In particular, US Pat. No. 4,126,854,
And No. 4,143,103,
A display medium using colored rotating particles in which hemispheres of rotating particles are divided into different colors and charging characteristics is known as a display exhibiting excellent contrast characteristics as compared with other systems. This display medium has a structure having a plurality of voids filled with a dielectric liquid and an optically transparent base material, and rotating particles in the voids. In addition, since the rotating particles are colored rotating particles having two regions having different colors and different charging characteristics in one particle, application of an electric field causes electrophoretic movement and rotational movement of the particles, resulting in image display. It can be carried out.

The following has been proposed as a method and material for producing the rotating particles. (1) A method disclosed in U.S. Pat. No. 5,262,908, in which two types of melted wax particles having different colors are combined, and spherical particles are solidified by surface tension and then solidified. The materials are carnauba wax, carbon black, and titanium oxide. To use. (2) Japanese Patent Application No. 9-246738 and Japanese Patent Application No. 9-2467
No. 39 disclosed on the surface of light transmissive particles,
It is a method of vapor deposition and coating of carbon black, antimony sulfide, etc., and the material is glass or resin. (3) Japanese Patent Application No. 9-24857 and Japanese Patent Application No. 9-33013
No. 5, which is a method for developing a color by performing exposure, development, and fixing treatments using particles made of a light-sensitive material, the materials being zinc oxide (coloring agent: toner), hydrophilic polymer (coloring agent: halogen). Silver halide) is used.

[0007]

However, the method of producing colored rotating particles by heating and melting a resin has a problem that the pigment dispersed in the resin is aggregated during heating. This means that the pigment is agglomerated to make the distribution of the pigment in the resin non-uniform, (1) the workability is deteriorated, (2) an uncolored portion is generated when the resin is stretched, (3). It means that the optical reflectance is lowered. This phenomenon remarkably appears in a resin in which titanium dioxide, which is a white pigment, is dispersed.

[0008] Therefore, the present invention solves and overcomes the above-mentioned problems, and suppresses the agglomeration of the pigment in the resin in the manufacturing process, thereby adjusting the color tone of the pigment and particularly increasing the whiteness and coloring resin. It is an object of the present invention to provide a method for producing colored rotating particles that prevents the occurrence of uncolored portions, and a method for producing a highly reliable display device that includes the colored rotating particles and has excellent display characteristics.

[0009]

As a result of intensive studies, the present inventor has come up with various aspects of the invention described below.

In the present invention, the surface is color-coded into two different colors, each color has a different charging characteristic, and a method for producing colored rotating particles in which the surface of a corresponding color is rotated by the action of an electric field to be displayed. Target.

In the method for producing colored rotating particles of the present invention, at least when the colored resins colored in the respective colors are bonded and the colored resins are integrally spherical by heat treatment to form the colored rotating particles. One of the colored resin,
It is formed by dispersing a pigment coated with a first resin in a second resin and coloring the second resin.

Further, in the present invention, at least one is sealed between a pair of transparent counter electrode substrates and the counter electrode substrate, the surface is color-coded into two different colors, and each color has different charging characteristics. Therefore, the colored rotating particles are produced by the above method, for a display device provided with a dispersion system including colored rotating particles that rotate by the action of an electric field to display a surface of a corresponding color.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments to which the present invention is applied will be described below in detail with reference to the drawings.

-Basic principle of this embodiment-First, the basic principle of this embodiment will be described. The surface of a pigment composed of a metal oxide such as titanium dioxide (TiO ₂ ) is hydrophilic and is difficult to be compatible with a resin in which the pigment is dispersed (second resin: hereinafter referred to as a dispersion resin). Therefore, when the dispersed resin is heated and brought into a molten state, the particles are aggregated so as to reduce the contact area between the pigment and the dispersed resin. Further, the surface treatment with a silane compound or the like fails to solve the above-mentioned problem because the entire surface of the pigment cannot be modified.

In this embodiment, as shown in FIG. 1, the surface of a pigment 1 is coated with a resin 2 (first resin: hereinafter referred to as a coating resin) to form a coating pigment 3, and the coating pigment 3 is formed. Three
Is dispersed in dispersion resin 4 to form a colored resin. As a result, the interface between the surface of the coated pigment 3 and the dispersed resin 4 becomes a resin, and aggregation of the pigment is prevented. Since the softening point of the coating resin 2 is higher than the softening point of the dispersion resin 4, the coating resin 2 can maintain the state in which the surface of the pigment 1 is covered even when the dispersion resin 4 is heated and is in a molten state. Since the coat resin 2 and the dispersion resin 4 are compatible with each other, detachment of the pigment 1 from the molten dispersion resin 4 can be prevented.

Further, by dispersing a dye in the coat resin, the color tone of the pigment can be adjusted, and particularly in the case of a white pigment,
Higher whiteness can be realized by using one kind or a mixture of plural kinds selected from blue dye, fluorescent dye and fluorescent brightening agent. At this time, by dissolving the coating resin and the dye in the organic solvent, the dye can be dissolved in the coating resin at a high concentration. Further, by using the coating resin and the organic solvent in which the dye is dissolved, it becomes possible to coat the surface of the pigment with the coating resin containing the dye.

-Structure of Sheet-Type Display Device- As shown in FIG. 2, this sheet-type display device has a plurality of voids (cavities) filled with a dielectric transparent liquid 12 constituting a dispersion system, The sheet base material 11 is an optically transparent layer having the colored rotating particles of the present invention (13A to 13F in the illustrated example) in these voids, and a counter electrode substrate provided on the upper surface of the sheet base material 11. Transparent common electrode 15
And display electrodes (16A to 16A in the illustrated example) provided on the lower surface of the sheet base material 11 so as to correspond to the respective colored rotating particles.
F), a drive circuit 17 having a signal input terminal 17A, and a power supply 18 for the drive circuit 17.

The colored rotating particles have different colors and different charging characteristics.
Since the particles have two regions (white portion 14A and black portion 14B), a voltage is applied between the transparent common electrode 15 and each of the display electrodes 16A to 16F by the power supply 18 and the drive circuit 17, as shown in FIG. By doing so, electrophoresis and rotational motion of the colored rotating particles are induced, and image display (in the illustrated example, (a) is black display, (b) is color change process, and (c) is white display) is performed. You can

-Method for Producing Colored Rotating Particles-In the present embodiment, the surface of the pigment is coated with a coating resin to prevent aggregation of the pigment, which tends to occur when the dispersion resin in which the pigment is dispersed is heated. It is a thing. The coated pigment and the dispersed resin are used to produce colored rotating particles of two colors by stretching and molding.

Specifically, first, as shown in FIG. 4A, a white pigment and a black pigment are kneaded in a resin to prepare a white lump resin 21 and a black lump resin 22. As described above, the surface of the white pigment is coated with a coating resin in order to prevent the agglomeration of the pigment generated during the treatment involving heating such as defoaming and rolling. Of course, the surface of the black pigment may be coated with the coating resin.

As the white pigment, known pigments such as titanium dioxide, barium titanate, calcium carbonate, alumina and zinc oxide can be used. As the black pigment, a known pigment such as carbon black, magnetite, aniline black, or a complex oxide composed of copper, cobalt, iron, manganese, chromium or the like can be used. It should be noted that the pigment may be other than the combination of white and black. As a kneading method, a method such as a kneader or a roll mill can be used.

As the coating resin, known resins such as polyester, polystyrene, polypropylene, epoxy, nylon, polyvinyl acetal, polycarbonate, acrylic and urethane can be used alone or in combination. Furthermore, when the same resin system is used for the coat resin and the dispersion resin, the softening point is maintained while maintaining compatibility by increasing the molecular weight of the coat resin, using a crosslinked structure, or modifying the coat resin. There is a way to raise.

As a method for coating the coating resin on the pigment, a method of spraying an organic solvent in which the coating resin is dissolved onto the pigment and drying or cooling it, and a method of directly applying the coating resin melted by heat onto the pigment (spray dry method) , A method in which a pigment is dispersed in a heat-melted resin, and after cooling, the resin is crushed, a pigment is dispersed in an uncured ultraviolet curable resin,
A method of crushing the resin after irradiating it with ultraviolet rays to cure it,
There is a method in which a pigment is dispersed in an uncured thermosetting resin, the resin is cured by heating, and then the resin is pulverized.

The present invention is not limited to these coating methods, and its main purpose is to coat the surface of the pigment with a resin to prevent aggregation of the pigment during heating. To crush the resin, a known crusher such as a Henschel mixer, a jet mill crusher, or a ball mill may be used.

By dissolving the disperse resin and the dye in the organic solvent, it becomes possible to disperse the dye which is difficult to be contained in the disperse resin. By using a blue dye, a fluorescent dye, a fluorescent whitening agent or the like as the dye, it is possible to increase the whiteness of the pigment. As the dye, known dyes such as oil-soluble dyes, disperse dyes, reactive dyes, direct dyes and acid dyes can be used. As fluorescent dyes and fluorescent whitening agents,
Known materials such as 4,4-diaminostilbene derivative, 4,4-diaminostilbenzenesulfonic acid derivative, triazinyl derivative, coumarin derivative, and bisoxal can be used.

As described above, the white coated pigment and the black pigment are kneaded into the respective dispersed resins to form the respective lump resins 2
After producing Nos. 1 and 22, as shown in FIG. 4B, each of the massive resins 21 and 22 is subjected to defoaming treatment by heating and rolled into a sheet. By laminating the white resin sheet 23 and the black resin sheet 24 of different colors while heating, the multilayer resin sheet 25 in which the resin sheets 23 and 24 of two colors are laminated is manufactured.

Subsequently, as shown in FIG. 4C, the multilayer resin sheet 25 is cut into a desired size, and each resin piece 2 is cut.
6 is formed. As a means for cutting the multilayer resin sheet 25, a known method such as a metal blade, a tungsten wire, or laser cutting may be used.

Then, as shown in FIG. 4D, the resin piece 26 is put into heated silicone oil. As a result, the resin (sheet resin and dispersed resin) is melted and spherical due to surface tension. By cooling this,
The colored rotating particles 31 are produced.

The above manufacturing process is only one embodiment, and the scope of application of the present invention is not limited to this.
In the present invention, it is important to prevent the pigment from agglomerating by coating the pigment with a sheet resin in the method for producing colored rotating particles by stretching and molding.

A display device can be formed by filling the voids inside the binder with the colored rotating particles together with a transparent insulating liquid. As a method for filling colored rotating particles and a transparent dielectric liquid, (1) US Pat. No. 4,143,1
(2) "A Newly Developed Electri", which is a method of dispersing two-color particles in silicone rubber before curing described in No. 03, curing the silicone rubber, and swelling the silicone rubber with silicone oil.
cal Twisting Ball Display ", M. Saitoh et.al.: Proc.
of SID, Vol.23 / 4. 1982, a method in which colored rotating particles are coated with a toluene-soluble resin, dispersed in polyvinyl alcohol, cured, and then dipped in toluene, (3) Japanese Patent Application No. Hei 7
There is a method in which the dielectric liquid and the colored rotating particles are covered with a resin film to form microcapsules, and the microcapsules are dispersed in a transparent resin by using the interfacial polymerization described in JP-A-343133.

As described above, according to the present embodiment, the aggregation of the pigment in the resin in the manufacturing process is suppressed, the color tone of the pigment is adjusted thereby, the whiteness is particularly increased, and the uncolored resin is not colored. It is possible to provide a method for producing colored rotating particles that prevents the occurrence of parts, and a method for producing a highly reliable display device that is equipped with the colored rotating particles and has excellent display characteristics.

[0032]

EXAMPLES The method for producing colored rotating particles of the present invention will be described in more detail below with reference to examples.

Example 1 (Preparation of colored rotating particles) White pigment: 30 parts by mass of titanium dioxide (manufactured by Titanium Industry Co., Ltd.) was sprayed with a modified polyester resin (softening point: 113 ° C.) dissolved in chloroform and dried. The white pigment surface was coated with resin. This coated white pigment is used as a polyester resin (softening point 93 ° C.) 270
A white lump resin was prepared by kneading with a mass part in a roll mill. On the other hand, polyester resin (softening point 1
A black lump resin was prepared by kneading 294 parts by mass of (00 ° C.) carbon black (made by Cabot) as a black pigment by 6 parts by mass with a roll mill. After vacuum defoaming while heating each block resin to a temperature of 110 ° C.,
A resin sheet having a thickness of about 30 μm was produced by a rolling press machine at 105 ° C. According to this method, it is possible to prevent the pigment from agglomerating during the production of the resin sheet, and to produce a uniformly colored resin sheet.

While heating the respective resin sheets, the resin sheets were laminated together to produce a two-color multilayer resin sheet. This multilayer resin sheet was cut with a metal blade to prepare a square resin piece having a side of about 300 μm, and the resin piece was put into heated silicone oil to prepare colored rotating particles having a particle size of about 170 μm.

Comparative Example Here, a comparative example of this embodiment will be described. It was produced in the same manner as in Example 1 except that titanium dioxide (manufactured by Titanium Industry Co., Ltd.) whose surface was not treated was used as the white pigment. In this case, as shown in FIG. 5, titanium dioxide aggregated during vacuum defoaming, and the whiteness was reduced. When this was further rolled, a resin sheet having an uncolored portion was formed, and the production efficiency of colored rotating particles was reduced.

(Production of Display Device) Synthetic paper (thickness 80 μm
m, presented by Oji Yuka Synthetic Paper), individual display electrodes were vapor-deposited with aluminum to prepare a sheet at the bottom of the display device. On the other hand, ITO on the PET film (thickness 150 microns)
Was uniformly vapor-deposited to form a transparent common electrode, and a sheet above the display device was produced.

The prepared particles are dispersed in a two-component silicone rubber KE106 (manufactured by Toray Dow Corning Co., Ltd.), and a Teflon (R) resin plate is uniformly bladed to a thickness of 300 μm by a blade method.
It was applied to about m and cured in an atmosphere of a temperature of 50 ° C. for 8 hours. This silicone rubber is used as silicone oil S
1 for H200-10cst (Toray Dow Corning)
A display layer was produced by immersing it for 2 hours. A sheet type display device was produced by bonding the display layer, the upper sheet of PET film, and the lower sheet of synthetic paper. When a voltage was applied to this display device, the rotation of the colored rotating particles showed stable behavior without variation.

Example 2 In the chloroform of Example 1, CI, which is an optical brightener, is added.
It was produced in the same manner as in Example 1 except that Fluorescent Brightening Agent 164 was added in a weight ratio of 1 wt% with respect to the modified polyester. In this example, an increase in whiteness was confirmed by the addition of the fluorescent whitening agent.

The various aspects of the present invention will be collectively described below as supplementary notes.

(Supplementary Note 1) A method for producing colored rotating particles in which the surface is color-coded into two different colors, each color has a different charging characteristic, and the surface of a corresponding color is rotated by the action of an electric field to display the surface. That is, the respective colored resins colored in the respective colors are joined, and the respective colored resins are spherically formed integrally by heat treatment to form the colored rotating particles. A method for producing colored rotating particles, characterized in that a coated pigment obtained by coating a pigment with a resin is dispersed in a second resin, and the second resin is colored.

(Supplementary Note 2) The method for producing colored rotating particles according to Supplementary Note 1, wherein the first resin has a higher softening point temperature than the second resin.

(Supplementary note 3) The method for producing colored rotating particles according to Supplementary note 1 or 2, wherein the first resin has a property of being compatible with the second resin.

(Supplementary Note 4) The first resin and the second resin are the same kind of resin, and the first resin is the second resin.
4. The method for producing colored rotating particles according to any one of appendices 1 to 3, which has a larger average molecular weight than the resin.

(Supplementary Note 5) By spraying the first resin in a fluid state onto the pigment, and drying or cooling,
The method for producing colored rotating particles according to any one of appendices 1 to 4, wherein the coated pigment is formed.

(Supplementary note 6) The colored rotating particle according to any one of supplementary notes 1 to 4, wherein the coated pigment is formed by applying the heat-melted first resin to the pigment. Manufacturing method.

(Supplementary Note 7) The coated pigment is formed by dispersing the pigment in the heat-melted first resin, cooling it, and then pulverizing the first resin. 5. The method for producing colored rotating particles according to any one of 1 to 4.

(Supplementary Note 8) The pigment is dispersed in the uncured first resin having ultraviolet curability, the first resin is cured by irradiation with ultraviolet rays, and then the first resin is pulverized. 5. The method for producing colored rotating particles according to any one of appendices 1 to 4, wherein the coated pigment is formed by:

(Supplementary Note 9) The pigment is dispersed in the uncured thermosetting first resin, the first resin is heated and cured, and then the first resin is crushed. The above-mentioned coated pigment is formed by
5. The method for producing colored rotating particles according to any one of 4 above.

(Supplementary Note 10) The first colored with a dye
10. The method for producing colored rotating particles according to any one of appendices 1 to 9, wherein the coated pigment is formed using the resin described in 1.

(Supplementary Note 11) The dye is a mixture of one or more selected from a blue dye, a fluorescent dye, and a fluorescent brightening agent, and the pigment is a white pigment. The method for producing colored rotating particles according to Appendix 10.

(Supplementary Note 12) A step of forming two resin sheets having different colors, adhering these resin sheets together to form a multilayer resin sheet, and cutting the multilayer resin sheet into chips. And, at least one of the resin sheets is formed from the colored resin containing the coating pigment, wherein the chip-shaped piece is heat-treated to be spherical. 1
Item 8. A method for producing colored rotating particles according to item.

(Supplementary Note 13) A pair of counter electrode substrates, at least one of which is transparent, and a space between the counter electrode substrates are enclosed. The surface is color-coded into two different colors, and each color has different charging characteristics. And a method of manufacturing a display device including a dispersion system including colored rotating particles that rotate by an action of an electric field to display a surface of a corresponding color, wherein each colored resin colored in each color is bonded, and heat treatment is performed. When forming the colored rotating particles by integrally sphericalizing each of the colored resins with each other, a coated pigment obtained by coating at least one of the colored resins with a pigment with a first resin is placed in a second resin. A method for manufacturing a display device, which comprises dispersing and coloring the second resin.

[0053]

EFFECTS OF THE INVENTION According to the present invention, the aggregation of pigments in the resin during the production process is suppressed, whereby the color tone of the pigment is adjusted, especially the whiteness is increased, and the generation of uncolored portions of the colored resin is prevented. It is possible to provide a method for producing colored rotating particles, and a method for producing a highly reliable display device having excellent display characteristics, which includes the colored rotating particles.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a state in which a pigment is coated with a coating resin and dispersed in a dispersion resin.

FIG. 2 is a schematic cross-sectional view showing a display device of this embodiment.

FIG. 3 is a schematic diagram showing how colored rotating particles are rotated by voltage application in the display device of the present embodiment.

FIG. 4 is a schematic view showing a method of manufacturing colored rotating particles in the present embodiment in order of steps.

FIG. 5 is a micrograph showing how a white pigment is dispersed in a resin in a comparative example of Example 1.

[Explanation of symbols]

1 pigment 2 coat resin 3 coated pigments 4 Dispersion resin 11 Sheet base material 12 Translucent liquid 13A to 13F, 31 colored rotating particles 14A White part 14B Black part 15 Transparent common electrode 16A to 13F display electrode 17 Drive circuit 18 power 21 White lump resin 22 Black block resin 23 White resin sheet 24 Black resin sheet 25 Multi-layer resin sheet 26 resin pieces

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Mitsuo Ozaki             4-1, Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa             No. 1 within Fujitsu Limited

Claims (5)

[Claims] 1. A method for producing colored rotating particles, the surface of which is color-coded into two different colors, each of which has different charging characteristics, and which is rotated by the action of an electric field to display a surface of a corresponding color. When the colored resins colored in the respective colors are joined, and the colored resins are integrally spherical by heat treatment to form the colored rotating particles, at least one of the colored resins is changed by the first resin. A method for producing colored rotating particles, characterized in that a coated pigment obtained by coating a pigment is dispersed in a second resin, and the second resin is colored to form the pigment. 2. The method for producing colored rotating particles according to claim 1, wherein the first resin has a higher softening point temperature than the second resin. 3. The coloring rotation according to claim 1, wherein the coated pigment is formed by spraying the first resin in a fluid state onto the pigment, and drying or cooling the first resin. Method for producing particles. 4. The coated pigment is formed by dispersing the pigment in the heat-melted first resin, cooling it, and then crushing the first resin. Or the method for producing colored rotating particles according to item 2. 5. A pair of counter electrode substrates, at least one of which is transparent, and a space between the counter electrode substrates, the surface of which is divided into two different colors, and each color has different charging characteristics. A method for manufacturing a display device including a dispersion system including colored rotating particles that rotate to display a surface of a corresponding color by the action of an electric field, wherein each colored resin colored in each color is bonded, and the heat treatment is performed to In forming the colored rotating particles by integrally sphericalizing each colored resin, at least one of the colored resins is coated with a pigment by a first resin, and a coated pigment is dispersed in a second resin. A method for manufacturing a display device, which is formed by coloring the second resin.