JP2003177437A - Method for manufacturing sheet-like display medium - Google Patents

Abstract

(57) [Summary] [Problem] To provide a method for manufacturing a sheet-shaped display device, a simple modification is made to the structure of the rotating particles in manufacturing a sheet-shaped display medium, and the rotating particles exist at a high density. Even in such a state, a cavity filled with the translucent liquid is surely generated between the individual rotating particles. A sheet is prepared by dispersing, in an optically transparent layer, rotating particles (13A) having a region having different optical characteristics on the surface and covering the surface with a coating layer (12), and forming the sheet into a light-transmitting layer. Then, the coating layer 12 is swelled by immersion in a permeable liquid to form a cavity 12A filled with the translucent liquid between the periphery of the rotating particles 13A and the like and the coating layer 12, thereby producing the sheet substrate 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet-like display having a structure in which a plurality of voids filled with a translucent liquid are formed in an optically transparent substrate, and rotating particles for display are included in the voids. It relates to an improved method of manufacturing a medium.

[0002]

2. Description of the Related Art Generally, it is called electronic paper, paper-like display, digital paper, etc., and a sheet-like display medium and a sheet-like display for displaying an image by changing optical absorption or reflection depending on application of an electric field. The device is known.

For example, in Japanese Patent No. 2551783 (Japanese Patent Application No. 62-244679), a solvent in which electrophoretic particles are dispersed is colored as an element for changing optical absorption or optical reflection depending on an electric field. A solvent-containing micro
A capsule is disclosed, and in Japanese Patent Application Laid-Open No. 8-234686 (Japanese Patent Application No. 7-343133), there is disclosed a microcapsule including a rotating body in which hemispheres having different colors and electrical characteristics are combined and combined. Further disclosed is a liquid crystal / polymer composite film containing a dichroic dye whose color changes with an electric field and a smectic liquid crystal, and the like.

The above-mentioned display device has a memory property and can retain image information even when the power supply is cut off.
In addition, since it is a reflective display device, it is expected as a substitute for paper that can be used repeatedly, and when it is made, a PET (polyethyleneterene) having electrodes is formed.
Since it is obtained by applying it on a phthalate film, it is realized as a thin, light, and flexible sheet-like material.

In particular, the display media disclosed in US Pat. Nos. 4,126,854 and 4,143,103 use rotating particles divided into hemispheres of different color and charging characteristics. It is known to exhibit excellent contrast characteristics as compared with other display media.

FIG. 5 is a cutaway side view of an essential part showing a display medium disclosed as a US patent, and FIG. 6 is a cutaway side view of an essential part for explaining the movement of rotating particles. Reference numeral 1 is a base material composed of an optically transparent layer, 2 is a void formed in the base material and filled with a transparent liquid, and 3 is a rotation divided into two regions having different colors and different charging characteristics Each particle is shown.

Since the display medium has the above-mentioned structure, it is possible to display an image by causing electrophoresis and rotation of rotating particles by applying an electric field. As rotating particles, multicolored particles such as not only two colors but also three colors or four colors are proposed.

As the method and material for producing the rotating particles, (1) US Pat. No. 5,262,908 describes:
Combine two types of molten wax particles of different colors,
A method of spheroidizing due to surface tension and then solidifying is disclosed, and examples of the material include carnauba wax, carbon black, and titanium oxide.

(2) Japanese Patent Application Laid-Open No. 11-85067 (Japanese Patent Application No. 9-246738) and Japanese Patent Application Laid-Open No. 11-850
No. 68 (Japanese Patent Application No. 9-246739) discloses a method of vapor-depositing or coating metal, carbon black, antimony sulfide or the like on the surface of light-transmissive particles,
Examples of the material include glass and resin.

(3) Japanese Patent Application Laid-Open No. 11-85069 (Japanese Patent Application No. 9-248527) and Japanese Patent Application Laid-Open No. 11-161.
Japanese Patent Application No. 206 (Japanese Patent Application No. 9-330135) discloses a method in which particles made of a photosensitizer are used to perform exposure, development, and fixing processes to develop a color, and as a material thereof, zinc oxide (a color former is Toners) and hydrophilic polymers (color formers are silver halides). Etc. are known.

In addition to the above, various materials for the rotating particles, such as resins, waxes, colorants, etc., may be used in various ways, or the rotating particles can be rotated with low energy, so that high resolution and high speed response can be obtained. A lot of research and development has been done to make a good display.

The main component of the rotating particles 3 is a resin such as polystyrene, polyacryl or polyethylene, or
Although glass or the like is used, in terms of manufacturability, it is desirable to use a substance whose shape control, color classification, charge controllability, etc. are easy. In addition, charge control is performed in view of motion control such as rotation and stop of the rotating particles 3. In addition to easy controllability of shape, shape and size, specific gravity is also important, and it is chemically stable and is insoluble in some translucent liquids or neglected. It is necessary that the substance has a small interaction such as possible.

By the way, the rotating particles having the above-mentioned properties are also useful for the translucent liquid used in the present invention, and such a substance has a molecular weight of 50,000 or less and a specific gravity of 0.70 to 1. A waxy substance of 20 is suitable.

Examples of the waxy substance include higher fatty acids such as stearic acid, palmitic acid, myristic acid and lauric acid, higher fatty acid metal salts such as aluminum stearate, potassium stearate and zinc palmitate, and hydrogenation. Higher fatty acid dielectrics such as castor oil, cocoa butter, methyl hydroxystearate and glycerol monohydroxystearate, waxes such as wood wax, beeswax, carnauba wax, microcrystalline wax, paraffin wax, polyethylene, polypropylene, ethylene -Low-molecular-weight olefin polymers and copolymers such as vinyl acetate copolymers and ethylene-vinyl alkyl ethers.

A sheet-shaped display medium can be obtained by dispersing the above-mentioned rotating particles in an elastomer such as silicone rubber to form voids.

The rotating particles are thoroughly mixed and dispersed with the silicone rubber (liquid) before the crosslinking reaction, and the dispersion system is spread in the form of a plate or a film, after which the silicone rubber undergoes a crosslinking reaction. However, in the rotating particle-dispersed silicone rubber thus prepared, there are no cavities around the rotating particles.

The rotating particle-dispersed silicone rubber plate prepared as described above is immersed in a translucent liquid and left for an appropriate time.

Then, the molecules of the translucent liquid penetrate into the silicone rubber molecules, so that the silicone rubber swells, but the rotating particles are insoluble in the translucent liquid, or the rotating particles are translucent. Since the permeation of the ionic liquid is extremely slow, a cavity is created around the rotating particles, and
This void is filled with a translucent liquid.

By the way, in order to realize a clear image in the sheet-shaped display medium manufactured by applying the above-mentioned technique, the filling rate of the rotating particles with respect to the sheet base material should be made as large as possible. It is better that there is no gap between the and cavity.

However, when the packing ratio of the rotating particles to the sheet base material is increased, the dispersed state of the rotating particles deteriorates, the rotating particles adhere to each other, and a communicating cavity containing two to three rotating particles is formed. This causes a problem that the rotating particles in the cavity cannot perform normal rotational movement.

[0021]

SUMMARY OF THE INVENTION In the present invention, a simple modification is made to the structure of the rotating particles in the production of the sheet-shaped display medium, and the rotating particles are made to have a high density. , It is ensured that a cavity filled with a translucent liquid can be generated between individual rotating particles.

[0022]

According to the present invention, a coating layer is formed on the surface of rotating particles in advance and then introduced and dispersed in a sheet substrate, and the sheet substrate is immersed in a translucent liquid to form rotating particles. It is basically to swell the translucent liquid with the coat layer to form a cavity.

In this case, by making the critical surface tension of the coating layer equal to or higher than the critical surface tension of the sheet base material, when the sheet base material is immersed in the translucent liquid, the sheet base material and the coat are coated. The translucent liquid infiltrates not between the coat layer but between the coat layer and the rotating particles to form a void, and a normal cavity can be generated.

For example, when the sheet base material is a silicone rubber, if the coating layer is made of a substance having the same chemical structure as the sheet base material and the coating layer, such as a polymer having a similar siloxane bond, It is possible to reliably generate a normal cavity.

By adopting the above means, it is possible to suppress the generation of defective cavities even if the filling ratio of the rotating particles to the sheet base material is sufficiently increased, and therefore, in the state where the rotating particles are present in a high density, The rotating motion of the rotating particles is normally and smoothly performed, and as a result, a clear image with high resolution can be realized.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a cutaway view of an essential part for explaining an example of a sheet-like display device manufactured by applying a manufacturing method of the present invention. In this figure, for example, the sizes of the rotating particles, the sizes of the cavities, and the intervals between them are shown to be substantially uniform, but this is for the sake of easy understanding and is not actually shown. It is usually uniform.

In the figure, 11 is a sheet substrate consisting of an optically transparent layer, 12 is a coat layer, and 12A is a cavity formed between the coat layer and rotating particles and filled with a light-transmitting liquid. , 13A, 13B, 13C, ... Rotating particles having a colored layer formed thereon, 14 a colored layer, 15 a transparent common electrode, 16A, 16B, 16C.
Reference numeral 7 indicates a drive circuit, 17A indicates a signal input terminal, and 18 indicates a power source.

In the illustrated sheet-like display device, the common electrode 15 is connected to the positive electrode side of the power source 18, and the display electrode 16
A, 16B, 16C, ... Are selectively connected to the negative electrode side of the power source 18 via the drive circuit 17.

Here, the signal input terminal 17A of the drive circuit 17
When a signal is input from the display electrode 16C, 16E, 16F when the display electrode selected by the signal, for example, 16C, 16E, 16F is connected to the negative side of the power supply 18,
Rotating particles 13B existing between 16F and the common electrode 15, 1
An electric field is applied to 3E and 13F to rotate them, and the colored layer 1
4 is exposed on the side of the common electrode 15 which is the display surface, and the display is realized. Hereinafter, the above-mentioned components will be described in detail.

The cavity 12A is filled with a translucent liquid, and the rotating particles 13A and 13B existing in the cavity 12A.
The colored layer 14 in ... suffices to be able to display different hues from the viewing side by utilizing the color of reflected light, the difference in reflection intensity, and the like.

The size of the rotating particles 13A, 13B, ... Is required to be such that the diameter of the rotating particles 13A, 13B ...
m] or less is selected, and as the material, as described above,
Various ones can be used.

By applying an appropriate coating method such as a spin coating method, a spraying method or a dipping method to the surface of the rotating particles 13A, 13B ...
A coat layer 12 made of the following surface treatment agent is formed.

Since the thickness of the coat layer 12 has an influence on the density or reflectance of each color after being formed into a sheet, it is better to make it as thin as possible. When the diameter of the rotating particles 13A is r, r / 10 The following is desirable.

The rotating particles 13A etc. coated as described above are dispersed in a sheet material and then molded into a sheet to prepare a sheet base material 11.

The sheet base material 11 is immersed in a translucent liquid such as a solvent to swell, and at that time, the translucent liquid enters between the rotating particles 13A and the like and the coat layer 12,
Cavity 1 containing translucent liquid and rotating particles 13A
2A is produced.

The present inventors have developed a two-component RTV (room) in which liquid silicone is solidified as the sheet base material 11 at room temperature.
temperature vulcanizing silicone rubber (critical surface tension: 25 [dyne / c
m]) as the material of the coat layer 12, those having different critical surface tensions and swelling properties with respect to each solvent, that is,
Fluorine resin, silicone rubber, polyethylene resin,
Butyl rubber is used, and it is immersed in each solvent and the cavity 12
As a result of investigating whether A can be normally produced, the results shown in the following table were obtained.

[0037]

[Table 1]

[Table 2]

FIG. 2 is a cutaway explanatory view of an essential part for explaining an example of a sheet-like display device in which a good cavity is formed. The same symbols as those used in FIG. 1 represent the same parts, or They have the same meaning.

The sheet-like display device shown in FIG.
It corresponds to the sample marked with a circle.

FIG. 3 is an explanatory view of a main part for explaining an example of a sheet-shaped display device in which a cavity having two layers is formed. The same symbols as those used in FIG. Represent or have the same meaning.

The sheet-like display device shown in FIG.
Cavities 12A and 12 though they do not communicate with each other.
This is an example of two layers of B.

FIG. 4 is an explanatory view of a main part for explaining an example of a sheet-like display device in which communicating cavities are formed. The same symbols as those used in FIG. 1 represent the same parts, or They have the same meaning.

The sheet-like display device shown in FIG.
Which corresponds to the sample marked with X in FIG. 2, is an example in which a large number of communicating cavities 12A are generated.
Normal operation cannot be expected with this.

Based on the above results, a good cavity 1
In order to generate 2A, it is necessary to cover the surfaces of the rotating particles 13A and the like with a coat layer 12 made of a coating material having a surface tension equal to or higher than the critical surface tension of the sheet base material 11. It is better that the swelling rate of the sheet base material 11 due to the transparent liquid is equal to or higher than the swelling rate of the sheet base material 11 due to the transparent liquid.
If the coat layer 12 is formed of a substance having the same chemical structure as that of 1, the swelling rate for the translucent liquid is substantially the same as that of the sheet base material 11, and a good cavity 12A is generated around the rotating particles 13A and the like. be able to.

With the above consideration, when the sheet base material 11 is swollen with the translucent liquid, no void is formed between the coat layer 12 and the sheet base material 11, and the rotating particles 1 are formed.
A void is formed only between 3A and the like and the coat layer 12, and a normal cavity 12A can be generated.

As the translucent liquid, an insulating liquid having a high electric insulating property or a high resistance liquid may be used, and an organic solvent such as toluene or acetone or water may be used, but in the cavity. It is preferable to use a non-volatile liquid in order to prevent the liquid that is always indispensable for the above from escaping. In particular, silicone oil is preferable because it has a low content of ions and impurities and a high resistance.

The rotating particles 13A, etc. in the liquid are the rotating particles 1.
It is known that electric charges are exchanged between 3A and the like and a liquid to form an electric double layer, and the rotating particles 13A and the like are positively or negatively charged.

In the rotating particle 13A, for example, when the white part is negatively charged and the colored part is positively charged, the rotating particle 1 is connected to the common electrode 15 side connected to the positive electrode of the power source 18.
For example, the display electrodes 16A and 16A, which face the white portions in 3A and the like, and which are selectively connected to the negative electrode of the power source 18
The colored portion side faces the B and 16D sides.

Therefore, when viewed from the transparent common electrode 15 side, light reflected by the colored portions of the rotating particles 13A, 13B, 13D, for example, a black image can be seen. When the direction of the electric field is reversed, the rotating particles 13A and the like are reversed and rotated, and the white portion is exposed on the observation side, so that the light reflected by that, that is, a white image can be seen.

As described above, since the observer sees the image through the common electrode 15, the common electrode 15 needs to be transparent. Therefore, the material forming the common electrode 15 is as follows. SnO ₂ and TiO which are transparent conductive materials
₂ , ZnO, ITO (indium tin oxide)
e) or the like is preferably used.

In the sheet-like display device described and illustrated above,
The rotation of the rotating particles can be performed with low energy, high-resolution and high-speed response display can be performed, color display is also possible, and display quality is excellent.

Further, since the structure is simple and the display can be rewritten, as well as the display can be held, and energy is not required for the holding, a limited power source, that is, a battery. It is suitable as a portable device that must use.

Furthermore, it can be used in a wide range of fields, for example, it can be used as a light-receiving display device for displaying image information such as characters, graphics, videos, etc., or can be handled like paper and viewed. It can be used as a paper display that can move, write images, copy images, read images, and erase images.

Example 1 Diameter 1 painted in black and white
A liquid one-component silicone rubber KE45S (manufactured by Shin-Etsu Chemical Co., Ltd.) was spray-coated on polyacrylic particles of about 00 [μm] to form a coating layer of about 10 [μm] on each of the polyacrylic particles.

Two-color type silicone rubber KE109 (manufactured by Shin-Etsu Chemical Co., Ltd.) containing the above-mentioned two-color particles having a coating layer in a ratio of 1: 1.
And then left standing at room temperature for 48 hours for curing to prepare a sheet base material in which two-color particles are dispersed and introduced.

The sheet base material in which the bicolor particles were dispersed was dipped in silicone oil SH200, 20 cS (manufactured by Toray Dow Corning Silicone Co., Ltd.) for 6 hours.

The sheet base material produced as described above was observed under a microscope, and it was confirmed that there were no communicating cavities in the entire sheet base material.

When a required transparent electrode was brought into close contact with both front and back surfaces of this sheet and an electric field was applied, a display having excellent display quality and responsiveness could be obtained.

Comparative Example 1 In the above-mentioned Example 1, a coating layer of rotating particles having a thickness of 10 was used.
When the [μm] fluororesin layer was substituted, the adhesion between the sheet base material and the coat layer was poor, and the coat layer was in close contact with the particle side, and cavities were formed around the coat layer. There were many defective cavities communicating with each other as shown in Fig.

Comparative Example 2 In the above-mentioned Example 1, a coating layer of rotating particles having a thickness of 10 was used.
When a translucent liquid, that is, ASTM # 3 was used as a swelling oil instead of the polyethylene resin layer of [μm], a cavity communicating with the cavity did not occur, but as shown in FIG. Is separated into two layers of 12A and 12B, and when a required transparent electrode is adhered to both sides of this sheet and an electric field is applied, particles that rotate normally and rotation inside are interrupted by the inner layer Particles that did not rotate were mixed in, and the display quality was extremely poor.

The present invention can be embodied in many forms including the above-described embodiment, which will be exemplified below.

(Supplementary Note 1) A step of preparing a sheet by dispersing rotating particles having a region having different optical characteristics on the surface and having the surface covered with a coat layer into an optically transparent layer; A step of swelling the coating layer by immersing the transparent layer in a translucent liquid to form a cavity filled with the translucent liquid between the periphery of the rotating particles and the coating layer to produce a sheet substrate. A method for manufacturing a sheet-shaped display device, comprising: (1)

(Appendix 2) The sheet-like display device according to (Appendix 1), characterized in that the coat layer is formed of a material having a critical surface tension equal to or higher than the critical surface tension of the sheet base material. Method. (2)

(Supplementary Note 3) The sheet-like article according to Supplementary Note 1 wherein the swelling ratio of the material forming the coat layer due to the light-transmitting liquid is equal to or higher than the swelling ratio of the sheet base material. Manufacturing method of display device. (3)

(Supplementary Note 4) The method for producing a sheet-shaped display device according to Supplementary Note 1, wherein the material constituting the coat layer has the same chemical structure as the sheet base material.
(4)

(Supplementary Note 5) The method for producing a sheet-shaped display device according to Supplementary Note 1, wherein the thickness of the coating layer is r / 10 or less, where r is the diameter of the rotating particles.

[0067]

In the method for producing a sheet-like display device according to the present invention, the rotating particles having a region having different optical characteristics on the surface and having the surface covered with a coat layer are made optically transparent. A step of preparing a sheet by dispersing it in layers, and immersing the sheet in a translucent liquid to swell the coat layer and filling the translucent liquid between the periphery of the rotating particles and the coat layer. It is fundamental to include a step of producing a cavity to produce a sheet base material.

By adopting the above construction, it is possible to suppress the generation of defective cavities even if the filling ratio of the rotating particles to the sheet base material is sufficiently increased, and therefore, in the state where the rotating particles are present at a high density, The rotating motion of the rotating particles is normally and smoothly performed, and as a result, a clear image with high resolution can be realized.

[Brief description of drawings]

FIG. 1 is a fragmentary explanatory view for explaining an example of a sheet-shaped display device manufactured by applying a manufacturing method of the present invention.

FIG. 2 is a main part cutting explanatory diagram for explaining an example of a sheet-shaped display device in which a good cavity is generated.

FIG. 3 is a fragmentary explanatory view for explaining an example of a sheet-shaped display device in which a cavity having two layers is generated.

FIG. 4 is a main part cutting explanatory view for explaining an example of a sheet-shaped display device in which a communicating cavity is generated.

FIG. 5 is a cutaway side view of a main part of a display medium disclosed as a US patent.

FIG. 6 is a cutaway side view of an essential part for explaining the movement of rotating particles.

[Explanation of symbols]

11 Sheet Substrate Comprising Optically Transparent Layer 12 Coat Layer 12A Cavity 12B Formed in Sheet Substrate and Filled with Translucent Liquid Cavity (One in Two Layers) 13A, 13B, 13C .... Rotating particles 14 on which a colored layer is formed Colored layer 15 Transparent common electrodes 16A, 16B, 16C ... Display electrode 17 Drive circuit 17A Signal input terminal 18 Power supply

Claims (4)

[Claims] 1. A step of preparing a sheet by dispersing rotating particles having a region having different optical characteristics on the surface and having the surface covered with a coat layer into an optically transparent layer, and producing the sheet. A step of swelling the coating layer by immersing the coating layer in a light-transmitting liquid to form a cavity filled with the light-transmitting liquid between the periphery of the rotating particles and the coat layer to produce a sheet substrate. A method for manufacturing a sheet-shaped display device, comprising: 2. The method for producing a sheet-shaped display device according to claim 1, wherein the coat layer is formed of a material having a critical surface tension equal to or higher than the critical surface tension of the sheet base material. 3. The sheet-shaped display device according to claim 1, wherein the swelling ratio of the material forming the coat layer due to the translucent liquid is equal to or higher than the swelling ratio of the sheet base material. Production method. 4. The chemical structure of the material forming the coat layer has the same chemical structure as that of the sheet base material.
A method for manufacturing the sheet-shaped display device described.