JP2007140029A - Display material - Google Patents

Abstract

Disclosed is a microcapsule in which two or more different colors and a colorless transparent solvent are sealed in a microcapsule wall, and provides a display material that effectively prevents an afterimage of a display image and aggregation of particles of different colors.
A microcapsule in which electrophoretic particles are dispersed and encapsulated in a dispersion medium, wherein the microcapsule wall contains a silicon compound or a fluorine compound. For this reason, the particles in the microcapsule are repelled against the van der Waals force between the particles and the wall even after several tens of minutes after the voltage is applied and the desired color is displayed. It is possible to prevent particles from getting into the capsule wall.
[Selection] Figure 2

Description

  The present invention relates to a microcapsule-type electrophoretic display material that prevents an afterimage of a display image.

  As a flat panel display device, a liquid crystal display device (LCD) is now widely used in various applications because it is thin and can be miniaturized. As another display method aiming at further thinner and lower power consumption than such an LCD, a display device using an electrophoretic phenomenon has been developed.

  As one of display devices using the electrophoresis phenomenon, a microcapsule electrophoresis system has been put into practical use. In this type of display device, positively and negatively charged white particles and black particles are placed in a microcapsule filled with a transparent solvent, and an image is formed by pulling up each particle to the display surface by applying an external voltage. It is. Since the size of the microcapsule is as small as several tens μm to several hundred μm, when the microcapsule is dispersed in a transparent binder, it can be coated like ink. This ink is called electronic ink because an image can be drawn by applying a voltage from the outside.

  When this electronic ink is coated on a transparent resin film on which a transparent electrode is formed and bonded to a substrate on which an electrode circuit for driving an active matrix is formed, an active matrix display panel as shown in Patent Document 1, for example, can be obtained. it can. In general, a component in which a transparent resin film on which a transparent electrode is formed is coated with electronic ink is called a “front plate”, and a substrate on which an electrode circuit for driving an active matrix is formed is called a “back plate”.

  In the microcapsule-type electrophoretic display device configured as described above, when a voltage is applied to the particles in the microcapsule and a desired color is displayed, the particles and the microcapsule are Due to van der Waals forces between the walls, particles gradually bite into the capsule wall, and there is a problem in that afterimages occur when the opposite color is displayed.

  In particular, in the case of a microcapsule in which different particles of two or more colors and a colorless transparent solvent are sealed in the microcapsule wall, the color of each color particle can be clearly displayed, but the contrast is high. Since it is colorless and transparent, the afterimage phenomenon in which the opposite color remains is more remarkable.

In a multi-particle system, if the color display is changed with particles of a certain color biting into the wall, the distance between particles of different colors will be close, and electrostatic or van der Waals attraction will work. Aggregation of particles having different diameters is formed. For this reason, even if the driving waveform etc. is devised and the encroached particles are removed from the wall, the aggregated particles do not return to each other, but become a mixed color aggregate and give the original contrast. Can not be.
JP 2000-221546 A

  The present invention has been made under the circumstances as described above, and an object of the present invention is to provide a display material that effectively prevents an afterimage of a display image and aggregation of particles having different colors.

  The present invention described in claim 1 has a microcapsule layer between a front plate provided with a first electrode on a transparent substrate and a back plate provided with a second electrode on a substrate, A display material formed of microcapsules in which at least two different colors and particles and a colorless transparent solvent are sealed in a microcapsule wall, wherein the microcapsule wall contains a silicon compound .

  The present invention according to claim 2 has a microcapsule layer between a front plate provided with a first electrode on a transparent substrate and a back plate provided with a second electrode on a substrate, A display material formed of microcapsules in which at least two different colors or more and a colorless transparent solvent are sealed in a microcapsule wall, wherein the microcapsule wall contains a fluorine compound .

  According to the present invention, since the microcapsule wall contains a silicon compound or a fluorine compound, particles in the microcapsule are applied with voltage, and a desired color is displayed. However, there is a repulsive force against the van der Waals force between the particle and the wall. Thereby, the biting of the particles into the capsule wall can be prevented.

  For this reason, even in the case of a microcapsule in which at least two or more different particles and a colorless transparent solvent are sealed in the microcapsule wall, it is possible to effectively prevent an afterimage when displaying opposite colors effectively.

  Moreover, aggregation of particles having different colors can be prevented, and aggregation of particles having different colors can be prevented.

  The display material of the present invention is characterized in that the microcapsule wall contains a silicon compound or a fluorine compound.

  FIG. 1 is a cross-sectional view of a microcapsule in which white and black electrophoretic particles are dispersed and encapsulated in a dispersion medium.

  Microcapsule wall formation methods include phase separation method, submerged drying method, melt dispersion cooling method, spray-drying method, pan coating method, interfacial polymerization method, in situ polymerization method, submerged cured coating method, interfacial reaction method, etc. Any suitable method can be used.

  In the present embodiment, a silicon compound or a fluorine compound is obtained by an in situ polymerization method in which a reactant (monomer, oligomer) is supplied from an electrophoretic dispersion liquid that is a core material and a microcapsule wall is formed around the core material. The present invention will be illustrated by exemplifying a method for incorporating a selenium into the microcapsule wall.

  First, as an electrophoretic dispersion liquid that is a core substance, for example, when two-color particles are displayed in black and white, white particles made of negatively charged titanium oxide and black particles made of positively charged carbon black are changed to tetrachloroethylene or the like. Those dispersed in a dispersion medium can be used.

  As the microcapsule wall material supplied from the inside of the core substance, a monofunctional or polyfunctional monomer such as acrylic ester, methacrylic ester, vinyl acetate, styrene-divinylbenzene is used, and the microcapsule wall is formed by radical polymerization. Can be formed.

  In addition, compounds such as polyisocyanates, polyisothiocyanates, polyamines, polycarboxylic acids, polybasic acid chlorides, acid anhydrides, epoxy compounds, polyols, acrylate compounds, polysulfides, and the like can be used for polyaddition and polycondensation reactions. A capsule wall can be formed.

  If necessary, a catalyst may be blended to cure these microcapsule wall materials.

  By using a silicon compound or fluorine compound having a reactive group as a part of these wall materials, a microcapsule wall containing the silicon compound or fluorine compound can be formed.

  At this time, one silicon microcapsule wall may contain both a silicon compound and a fluorine compound.

  Examples of the silicon compound include a polymer of terminally modified dimethyl silicone oil in which both ends are modified with a reactive group such as a vinyl group, a methacryloxy group, and an isocyanate group, or one end and both ends have the above-described reaction activity. Copolymers with those modified with groups may be used.

  Examples of the fluorine compound include a monomer or oligomer polymer in which one end is modified with a perfluoroalkyl group and the other end is modified with a reactive group such as a vinyl group, a methacryloxy group, or an isocyanate group, or one end Further, a copolymer having both ends modified with a reactive group as described above may be used.

  After mixing the microcapsule wall material with the electrophoretic dispersion which is the core substance, the mixture is emulsified in water.

  At this time, an emulsifier may be used as necessary.

  And in order to advance the polymerization reaction of a microcapsule wall material, the microcapsule wall containing a silicon compound or a fluorine compound can be formed by raising the temperature of this emulsion.

As for the transparent substrate, a transparent plastic film such as polyethylene terephthalate, polymethyl methacrylate, polycarbonate, polyethylene naphthalate, polypropylene, nylon-6, nylon-66, polyvinylidene chloride, and polyethersulfone is used in addition to the glass substrate. May be.

[Create microcapsules]
First, in order to form a microcapsule wall in 100 parts of a tetrachloroethylene solvent, 20 parts of diphenylmethane diisocyanate, 15 parts of polyoxypropylene ether, and 2 parts of an isocyanate-modified dimethyl silicone oil having an isocyanate group at one end were mixed. A mixed solution was prepared.

  Next, in this mixed solution, 30 parts of titanium oxide having an average particle diameter of 3 μm and coated with a polyethylene resin that is negatively charged in the solution as white particles, and an average particle diameter that is positively charged in the solution as black particles A dispersion was prepared by dispersing 10 parts of 3.5 μm carbon black.

  This dispersion was mixed with an aqueous solution containing 300 parts of water adjusted to 10 ° C. and 0.2 part of sodium dodecyl sulfate as an emulsifier, and the mixture was stirred using a homogenizer while maintaining the liquid temperature at 10 ° C., and an O / W emulsion. Got.

  Next, the liquid temperature was raised to 95 ° C. while stirring to form a microcapsule wall, and a microcapsule in which a dispersion liquid in which white and black particles were dispersed was enclosed.

  The diameters of the microcapsules thus prepared were each adjusted to 40 μm by sieving.

[Preparation of microcapsule coating solution]
150 parts of the obtained microcapsules, 100 parts of a polyurethane resin solution (Nipporan 5037, manufactured by Nippon Polyurethane Industry Co., Ltd.) and 5 parts of a curing agent (Coronate HL, manufactured by Nippon Polyurethane Industry Co., Ltd.) are mixed to prepare a microcapsule coating solution. It was created.

[Production of display panel]
This microcapsule coating solution was applied using an applicator on a transparent substrate (11) provided with indium tin oxide (hereinafter referred to as ITO) first electrode (12) on the entire surface, and dried at 70 ° C. for 30 minutes. A microcapsule layer (13) having a film thickness of 45 μm was obtained.

  Then, a second electrode (15), a matrix electrode (not shown), and a switching element (not shown) in which a pattern of 40 μm in length × 40 μm in width is repeatedly formed on the base material (14) are formed. The display panel (20) shown in FIG. 2 was obtained by laminating the back plate and the back plate that were attached to each other by hot pressing at 80 ° C.

[Evaluation of afterimage]
The evaluation results are shown in Table 1.

<Afterimage after white display>
First, the reflectance of the white display and the black display in the initial state was measured for the display panel as follows.

A voltage of 30 V is applied for 500 ms so that the front side (display side) is a positive electrode and the back side is a negative electrode. As shown in FIG. 2, white particles in each microcapsule are moved to the front side and black particles are moved to the back side. The white reflectance at this time was measured. The measurement conditions are as follows.
Measurement conditions Incident light: 0 °
Light reception: 45 °
Light source: D65
Viewing angle: 10 °

  Subsequently, a voltage of 30 V is applied for 500 ms so that the front side is a negative electrode and the back side is a positive electrode, and as shown in FIG. 3, the black particles in each microcapsule are moved to the front side, and the white particles are moved to the back side. The black reflectance at this time was measured under the previous measurement conditions.

  Subsequently, in order to confirm the influence of the afterimage, a voltage of 30 V was applied for 500 ms so that the front side was a positive electrode and the back side was a negative electrode. After white display, the voltage was held for 30 minutes.

  Then, a voltage of 30 V was applied for 500 ms so that the front side was a negative electrode and the back side was a positive electrode, and the black reflectance at this time was measured under the previous measurement conditions.

  As a result, there is no difference in reflectance between the black display in the initial state and the black display at the time of afterimage evaluation. As shown in FIG. It was confirmed that no white particles remained on the side) and no afterimage occurred.

<Afterimage after black display>
A voltage of 30 V is applied for 500 ms so that the front side (display side) is a negative electrode and the back side is a positive electrode. As shown in FIG. 6, black particles in each microcapsule are moved to the front side and white particles are moved to the back side. The black reflectance at this time was measured.

  Subsequently, a voltage of 30 V was applied for 500 ms so that the front side was a positive electrode and the back side was a negative electrode. As shown in FIG. 7, white particles in each microcapsule were moved to the front side, and black particles were moved to the back side. The white reflectance at the time was measured under the previous measurement conditions.

  Subsequently, in order to confirm the influence of the afterimage, a voltage of 30 V was applied for 500 ms so that the front side was a negative electrode and the back side was a positive electrode. After black display, the voltage was turned off and held for 30 minutes.

  Then, a voltage of 30 V was applied for 500 ms so that the front side was a positive electrode and the back side was a negative electrode, and the white reflectance at this time was measured under the previous measurement conditions.

  As a result, there is no difference between the reflectance of the white display in the initial state and the white display at the time of afterimage evaluation. As shown in FIG. It was confirmed that no black particles remained on the side) and no afterimage occurred.

(Comparative Example 1)
[Production of microcapsules]
In order to form a microcapsule wall in 100 parts of a tetrachloroethylene solvent, a mixed solution was prepared by mixing 20 parts of diphenylmethane diisocyanate and 15 parts of polyoxypropylene ether.

  Next, in this mixed solution, 30 parts of titanium oxide having an average particle diameter of 3 μm and coated with a polyethylene resin that is negatively charged in the solution as white particles, and an average particle diameter that is positively charged in the solution as black particles A dispersion was prepared by dispersing 10 parts of 3.5 μm carbon black.

  This dispersion was mixed with an aqueous solution prepared by mixing 300 parts of water adjusted to 10 ° C. with 0.2 part of sodium dodecyl sulfate as an emulsifier, and the mixture was stirred using a homogenizer while maintaining the liquid temperature at 10 ° C., and an O / W emulsion. Got.

  Next, the liquid temperature was raised to 95 ° C. while stirring to form a microcapsule wall, and a microcapsule in which a dispersion liquid in which white and black particles were dispersed was enclosed.

  The diameters of the microcapsules thus prepared were each adjusted to 40 μm by sieving.

[Preparation of microcapsule coating solution]
It was produced in the same manner as in Example 1.

[Production of display panel]
It was produced in the same manner as in Example 1.

[Evaluation of afterimage]
Evaluation was performed in the same manner as in Example 1.
The evaluation results are shown in Table 1.

<Afterimage after white display>
The reflectivity of black display at the time of afterimage evaluation was larger than that in the initial state, and it was confirmed that afterimage was generated when black display was performed 30 minutes after white display. This is presumably because white particles remained on the front side (display side) as shown in FIG.

<Afterimage after black display>
The reflectance of the white display at the time of the afterimage evaluation was smaller than that in the initial state, and it was confirmed that afterimage was generated when the white display was performed 30 minutes after the black display. This is presumably because black particles remained on the front side (display side) as shown in FIG.

[Create microcapsules]
First, in order to form a microcapsule wall in 100 parts of a tetrachlorethylene solvent, 5 parts of an acrylic ester, 10 parts of a methacrylic ester, 1 part of a perfluoroalkyl group-containing oligomer having an ester group at one end, a polymerization initiator A mixed solution was prepared by mixing 1 part of a certain benzoyl peroxide.

  Next, in this mixed solution, 30 parts of titanium oxide having an average particle diameter of 3 μm and coated with a polyethylene resin that is negatively charged in the solution as white particles, and an average particle diameter that is positively charged in the solution as black particles A dispersion was prepared by dispersing 10 parts of 3.5 μm carbon black.

  It mixed with the aqueous solution which mix | blended 0.2 part of sodium dodecyl sulfate as an emulsifier with 200 parts of water adjusted to 10 degreeC, and it stirred using the homogenizer, keeping the liquid temperature at 10 degreeC, and obtained O / W emulsion.

  Next, the liquid temperature was raised to 70 ° C. while stirring to form a microcapsule wall, and a microcapsule in which a dispersion liquid in which white and black particles were dispersed was enclosed.

  The diameters of the microcapsules thus prepared were each adjusted to 40 μm by sieving.

[Preparation of microcapsule coating solution]
It was produced in the same manner as in Example 1.

[Evaluation of afterimage]
Evaluation was performed in the same manner as in Example 1.
The evaluation results are shown in Table 1.

<Afterimage after white display>
There is no difference in the reflectivity between the black display in the initial state and the black display after the afterimage evaluation. After white display, after 30 minutes, no black particles remain on the front side (display side) even after black display. It was confirmed that no afterimage occurred.

<Afterimage after black display>
There is no difference in reflectance between the white display in the initial state and the white display after the afterimage evaluation. After 30 minutes from the black display, even if the white display is performed, no black particles remain on the front side (display side). It was confirmed that no afterimage was generated.

(Comparative Example 2)
[Production of microcapsules]
First, in order to form a microcapsule wall in 100 parts of a tetrachloroethylene solvent, a mixed solution was prepared by mixing 5 parts of an acrylate ester, 10 parts of a methacrylic acid ester, and 1 part of benzoyl peroxide as a polymerization initiator.

  Next, in this mixed solution, 30 parts of titanium oxide having an average particle diameter of 3 μm and coated with a polyethylene resin that is negatively charged in the solution as white particles, and an average particle diameter that is positively charged in the solution as black particles A dispersion was prepared by dispersing 10 parts of 3.5 μm carbon black.

  It mixed with the aqueous solution which mix | blended 0.2 part of sodium dodecyl sulfate as an emulsifier with 200 parts of water adjusted to 10 degreeC, and it stirred using the homogenizer, keeping the liquid temperature at 10 degreeC, and obtained O / W emulsion.

  Next, the liquid temperature was raised to 70 ° C. while stirring to form a microcapsule wall, and a microcapsule in which a dispersion liquid in which white and black particles were dispersed was enclosed.

  The diameters of the microcapsules thus prepared were each adjusted to 40 μm by sieving.

[Preparation of microcapsule coating solution]
It was produced in the same manner as in Example 1.

[Production of display panel]
It was produced in the same manner as in Example 1.

[Evaluation of afterimage]
Evaluation was performed in the same manner as in Example 1.
The evaluation results are shown in Table 1.

<Afterimage after white display>
The reflectivity of black display at the time of afterimage evaluation is larger than that in the initial state, and after 30 minutes after white display, when black display is performed, white particles remain on the front side (display side), resulting in an afterimage. It was confirmed.

<Afterimage after black display>
The reflectance of white display at the time of afterimage evaluation is smaller than that in the initial state, and after 30 minutes after black display, when white display is performed, black particles remain on the front side (display side), resulting in an afterimage. It was confirmed.

  Since the display material of the present invention contains a silicon compound or a fluorine compound in the microcapsule wall, it is possible to effectively prevent an afterimage of the display image, and therefore, for various segment display and active matrix display applications, Widely available.

It is explanatory drawing of the microcapsule which disperse | distributed the white and black electrophoretic particle in the dispersion medium, and was enclosed. FIG. 6 is an explanatory diagram illustrating white display in an initial state according to the first embodiment. FIG. 3 is an explanatory diagram illustrating black display in an initial state of Example 1. It is explanatory drawing which shows the black display in which the afterimage after the white display of Example 1 does not remain. It is explanatory drawing which shows the black display in which the afterimage after the white display of the comparative example 1 remains. FIG. 3 is an explanatory diagram illustrating black display in an initial state of Example 1. FIG. 6 is an explanatory diagram illustrating white display in an initial state according to the first embodiment. It is explanatory drawing which shows the white display in which the afterimage after black display of Example 1 does not remain. It is explanatory drawing which shows the white display in which the afterimage after the black display of the comparative example 1 remains.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... White particle 2 ... Black particle 3 ... Dispersion medium 4 ... Microcapsule wall 11 ... Transparent substrate 12 ... First electrode 13 ... Microcapsule layer 14 ... Base material 15 ... Second electrode 20 ... Display panel

Claims (2)

  A microcapsule layer is provided between a front plate having a first electrode on a transparent substrate and a back plate having a second electrode on a base, and the microcapsule layer is transparent and colorless with at least two different colors. A display material comprising a microcapsule in which a solvent is sealed on a microcapsule wall, wherein the microcapsule wall contains a silicon compound.   A microcapsule layer is provided between a front plate having a first electrode on a transparent substrate and a back plate having a second electrode on a base, and the microcapsule layer is transparent and colorless with at least two different colors. A display material comprising a microcapsule in which a solvent is sealed on a microcapsule wall, wherein the microcapsule wall contains a fluorine compound.

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