JP2006259709A - Migration magnet for magnetphoresis reversal display panel and display panel set using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a suitable magnetic force characteristic range etc., by a migration magnet used for a panel performing magnetphoresis reversal display and to provide a display panel set for magnetphoresis reversal display using the same. <P>SOLUTION: The migration magnet for use in the magnetphoresis reversal display panel is provided which is characterized in that magnetic flux density near an inner wall surface opposite from the panel top surface side of a support material on which the migration magnet operates within a designated range, and the display panel set using the same is provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrophoretic magnet used in a magnetophoretic reversal display panel and a display panel set using the same, and more specifically, forms a display by moving or migrating / inverting a micro magnet with a writing magnet, and further for erasing from the back side. In a magnetophoretic reversal display panel that erases the display by attracting a minute magnet with a magnet, an electrophoretic magnet (for writing / erasing) having a more suitable magnetic property range during writing or erasing, and a display panel using the same Regarding the set.

  2. Description of the Related Art Conventionally, a magnetic display system using a magnetic display panel capable of performing display by magnetism has been known, and as the magnetic display system, a magnetism that performs display by migrating magnetic particles as described in Patent Document 1 is known. There have been proposed an electrophoretic display panel and a magnetic reversal display panel that performs display by reversing magnetic particles such as those disclosed in Patent Document 2.

As shown in FIG. 7, the magnetophoretic display panel is a so-called electrophoretic type, in which the entire surface of the backside plate (11) side of the magnetophoretic display panel is slid with an erasing magnet (4) before writing. 13) is pulled toward the back plate (11) and the surface plate (10) side is made a uniform surface, and then the writing magnet (5) is scanned on the surface plate (10) side, and the magnetic particles (13 ) Is drawn toward the surface plate (10) side to obtain a magnetic display. When erasing such a magnetic display, the erasing magnet (4) is slid on the back plate (11) side of the magnetophoretic display panel, and the magnetic particles (13) on the front plate (10) side are placed on the back plate ( 11) Pull back to the side, and erase the magnetic display written on the surface plate (10) side of the magnetophoretic display sheet. However, in such a display / erase method, the magnetic display written on the magnetophoretic display panel can only be erased from the back plate (11) side, so that it is not possible to change the color of only a desired part of the magnetic display. It was a thing. In addition, the magnetic particles (13) are not magnet structures, such as magnetite particles, and have almost no coercive force / residual magnetization / or few particles. There is no problem such as destruction of the magnetic pole, and the required performance of the writing and erasing magnets is such that there is sufficient magnetic force to migrate the magnetic particles (13). Issues related to the magnetic force (magnetic flux density) in the vicinity of the inner wall surface on the opposite side of the panel to be applied, and the magnetic force (magnetic flux density) applied to the breakage of the micro magnet in the vicinity of the inner wall surface of the surface on which the migrating magnet of the support material acts after migration There were no value constraints.
Further, since the magnetic particles (13) are monochromatic (black) substantially spherical particles as typified by magnetite particles, only black color magnetic display can be obtained.

On the other hand, as shown in FIG. 8, the magnetic reversal display panel, so-called reversal type, is an erasing magnet having a specific magnetic pole from the surface plate (10) side of the magnetic reversal display panel before writing. A magnet for writing (5) having the same pole of the magnet (2) facing the panel surface plate (10) side, making the surface plate (10) side a uniform surface, and having opposite magnetic poles on the same surface plate (10) side ) And the like, and a magnetic display is obtained by partially inverting the micromagnet and displaying the color of the micromagnet (2) having a magnetic pole opposite to the magnetic pole on which the writing magnet (5) is applied. It is. When erasing such a magnetic display, since erasing is performed from the same front plate (10) side, only a desired portion can be erased, and the back plate (11) side cannot be slid with a magnet. However, the magnetic display written on the magnetic reversal display panel is dominated by the two colors of the fine magnet (2) color-coded on the front and back, and In order to more faithfully express the color tone of the front and back of the micro magnet (2), it was necessary to use a transparent liquid as the dispersion medium.
That is, only the two-color display of the color tone of the uniform state before writing which is the color tone of the front and back of the micro magnet (2) and the color tone of the magnetic display by the writing magnet can be obtained, and the micro magnet (2) is suitably migrated. There was no disclosure about the electrophoretic magnets used therefor.

  Furthermore, the present inventors have previously proposed, for example, PCT / JP2004 / 004625, a display method and suitable inclusion characteristics (micromagnet characteristics) for a magnetophoretic reversal display panel. However, there are no proposals regarding a writing magnet and an erasing magnet suitable for migration of the micro magnet (2).

Japanese Examined Patent Publication No. 62-53359 Japanese Patent Publication No.59-32796

  Accordingly, the present invention provides a suitable magnetic property range and the like for a migrating magnet used in a panel capable of performing electrophoretic reversal display by magnetism, and also provides a display panel set for magnetophoretic reversal using the same. The object of the present invention is to propose means for solving such a problem.

The above-described problems of the present invention are solved by the following inventions.
That is, the present invention
“1. A dispersion liquid having a yield value obtained by dispersing micromagnets having a color different from the color of the dispersion medium and different from each other in the dispersion medium containing at least a colorant; An electrophoretic magnet used in a magnetophoretic reversal display panel having a supporting material for holding a dispersion liquid, wherein the magnetic flux density in the vicinity of the inner wall surface on the panel surface side on which the electrophoretic magnet of the supporting material acts is 400 mT or less. An electrophoretic magnet for a magnetophoretic reversal display panel, wherein the magnetic flux density in the vicinity of the inner wall surface on the opposite side is 10 mT or more and 300 mT or less.
2. The electrophoretic magnet for a magnetophoretic reversal display panel according to item 1, wherein the coercive force of the micromagnet in the magnetophoretic reversal display panel is 4.0 kA / m or more and 600 kA / m or less.
3. In the first or second item, the remanent magnetization per unit mass of the micro magnet in the magnetophoretic reversal display panel is 1 to 35 A · m ² / kg, and the saturation magnetization is 1 to 100 A · m ² / kg. Electrophoretic magnet for magnetophoretic reversal display panel as described.
4). At least a dispersion liquid having a yield value obtained by dispersing micro magnets having colors different from the color of the dispersion medium and different from the front and back colors in a dispersion medium containing a colorant, and the dispersion liquid. A display panel set comprising at least a magnetophoretic reversal display panel including a supporting material to be held, and the electrophoretic magnet according to any one of Items 1 to 3. ".

According to the electrophoretic reversal display panel electrophoretic magnet and the display panel set using the magnetophoretic reversal display panel, a display is formed by migrating or migrating / reversing the micromagnet with a writing magnet, and further the micromagnet with an erasing magnet from the back surface. In a magnetophoretic reversal display panel that draws and erases the display, a writing magnet (for writing / erasing) having a more suitable magnetic characteristic range and a display panel set using the same can be obtained at the time of writing or erasing. it can.
In addition, the electrophoretic reversal display panel migration has the magnetic characteristics more suitable for migrating micromagnets and does not cause problems such as the magnetic poles of micromagnets being destroyed even if relatively strong magnets are used. An excellent effect is obtained in that a magnet and a display panel set using the magnet can be obtained.

The magnetophoretic reversal display panel used in the present invention includes a dispersion liquid (3) having a yield value obtained by dispersing fine magnets in a dispersion medium containing at least a coloring material, and a support for holding the dispersion liquid. Material. As the migration magnets (4, 5), those having a specific range of “magnetic flux density in the vicinity of the inner wall surface on the opposite side of the panel on which the migration magnet of the support material acts” are used. By adopting such a configuration, it is possible to perform suitable migration display (writing / erasing) of the micro magnet without destroying the magnetic pole of the micro magnet. Furthermore, when a micro magnet having different magnetic pole colors is used, three colors of magnetic display can be obtained. That is, as shown in FIG. 4, the first color tone is generated on the back plate (11) side by using an erasing magnet (hereinafter simply referred to as an erasing magnet) (4) which is one of the migration magnets. When the micro magnet (2) is drawn, the dispersed liquid (3) component excluding the micro magnet (2) is colored and conceals the micro magnet (2), so when viewed from the surface plate (10) side It is obtained as a display of a uniform color tone of the dispersion medium [FIG. 4- (a)]. The second color tone is to apply an external magnetic field by selecting a specific magnetic pole of a writing magnet (hereinafter simply referred to as a writing magnet) (5), which is one of the other electrophoretic magnets, on the portion to be written. Is obtained by moving or migrating / reversing the micro magnet (2) in the dispersion liquid (3) to display the color tone of a specific surface (for example, the N pole surface) of the micro magnet [2] [FIG. (B)]. Further, the third color tone is obtained by obtaining the magnetic field of the opposite magnetic pole by another reversing magnet (6) which is not a migration magnet with respect to the handwriting on which the color tone of the specific surface is displayed after obtaining the handwriting by the magnetic display. By making the other micromagnets (2) that do not form a ring act as long as they do not migrate, the micromagnets (2) of any part that forms the handwriting are reversed, and the handwriting can be changed without changing the shape of the handwriting. It is obtained by changing the color tone of an arbitrary part [FIG. 4- (c)]. However, it goes without saying that the handwriting color can be displayed in the opposite direction by reversing the magnetic pole of the external magnetic field when obtaining the second and third color tones.
If both sides are the same color, it can be used as a bright color migration display panel with good contrast, and such an embodiment is also included in the present invention.

  When performing multicolor display as described above, the magnetic characteristics of the external magnetic field used for migration or migration / reversal, that is, the migration magnets (4) and (5), and the reversal magnet (6) used for display color reversal. By controlling well, etc., it is possible to control multicolor display by migration and inversion. That is, in order for the micromagnet (2) to migrate, the dispersion liquid of the panel support material is sealed by the partition plate (12) in FIG. 5 which is cited as an example of the magnetophoretic reversal display panel of the present invention. It must be attracted against the resistance in the liquid by the height of the cell.

  When the micro magnet (2) has different magnetic poles on the front and back sides and is colored in different colors, the magnetic display color is determined depending on which of the N or S poles is selected. The operating state of the micro magnet (2) at the time of the display migrates as it is when the different polarity faces the panel display surface in relation to the writing magnet (5), and displays the display color on the surface. When the pole is facing, it migrates while being reversed, and displays a reverse color tone. (Fig. 6)

  Therefore, in order to migrate the micromagnet (2) to the panel surface, the micromagnet existing in the vicinity of the inner wall surface (11 ') on the surface (11) on the opposite side of the panel on which the migration magnet acts is supported. It is necessary to migrate by the height of the partition plate (12). That is, “the magnetic flux density in the vicinity of the inner wall surface on the opposite side of the panel where the migration magnet of the support material acts” becomes an important factor.

  Here, the “magnetic flux density in the vicinity of the inner wall surface on the opposite side of the panel on which the migration magnet of the support material acts” is preferably 10 mT or more. Furthermore, 15 mT or more is good, 20 mT or more is better, and 35 mT or more is optimal.

  Needless to say, the minute magnet close to one surface on which the migrating magnet is applied from the vicinity of the inner wall surface (11 ') on the opposite side is subjected to a stronger magnetic force and thus preferably migrates.

  Furthermore, the larger the magnetic force applied to the vicinity of the inner wall surface (11 '), the better. As will be described in detail later, since the micro magnet itself has a magnetic property and must be stably held, if too much magnetic force is applied, the magnetic pole of the micro magnet may be destroyed, or other micro magnets This is because there is a possibility that color may be mixed and reversed by mistaken migration and inversion. Therefore, the upper limit value of “the magnetic flux density in the vicinity of the inner wall surface on the opposite side of the panel on which the migration magnet of the support material acts” is preferably 300 mT or less. Furthermore, 150 mT or less is good, and 100 mT or less is optimal.

This upper limit can be inferred for the following reason.
The magnetic force attenuates in inverse proportion to the square of the distance over which it acts. That is, when the micro magnet (2) migrates from the vicinity of the inner wall surface (11 ′) and is positioned in the vicinity of the surface (10 ′), the magnetic force acting on the micro magnet (2) is increased accordingly. become. Therefore, when the acting magnetic force becomes strong (when the micromagnet (2) is positioned in the vicinity of the surface (10 ′)), the magnetic poles of the micromagnet (2) are not destroyed and color mixing is not caused. A range of magnetic properties is required. From this point of view, “the magnetic flux density in the vicinity of the inner wall surface on the panel surface side on which the migration magnet of the support material acts” needs to be 400 mT or less, and preferably 300 mT or less. Similarly, “the magnetic flux density in the vicinity of the inner wall surface on the opposite side of the panel on which the migration magnet of the support material acts” is preferably 300 mT or less, and more preferably 150 mT or less. Furthermore, 100 mT or less is optimal from the viewpoint of material acquisition.

  Taking one of the examples given below as an example, the magnetic flux density of 150 mT at the distance of the support partition plate (12) is 150 mT, and the electrophoretic magnet used at that time is a surface magnetic flux density of 372 mT. “The magnetic flux density in the vicinity of the inner wall surface on the opposite side of the panel on which the supporting material migration magnet acts” According to the 150 mT migration magnet, the magnetic flux density is sufficient to migrate the micro magnet (2). Magnetic flux density in the vicinity of the inner wall surface on the panel surface side on which the magnet is applied is 372 mT, even when the micro magnet (2) is positioned near the surface (10 '), the magnetic pole of the micro magnet (2) is destroyed or color mixing is caused. Magnetic flux density that does not occur. In addition, although it became such a relationship in the magnet of this example, as can be seen from the examples etc., this relationship is not necessarily obtained depending on the form of the magnetic field lines of the magnet and the shape of the panel support. Care must be taken that it is not specified.

  That is, even if the surface magnetic flux density is the same (the magnetic flux density at the position of the surface side (10 ′)), depending on the configuration, “the magnetic flux density in the vicinity of the inner wall surface on the opposite side of the panel on which the migration magnet of the supporting material acts is applied. The panel surface on which the electrophoretic magnet of the supporting material acts is as described above under the condition that the magnetic pole of the micro magnet is not destroyed and color mixing is not caused while obtaining a good display. It is effective to set the magnetic flux density in the vicinity of the inner wall surface on the opposite side to a specific range. Furthermore, the magnetic flux density on the surface side can be said to be a limit point at which micro magnets are directly broken or color mixing occurs, and if the surface magnetic flux density of the migrating magnet is 400 mT or less, the micro magnets tend not to be broken. And more preferably 350 mT or less.

Further, in the present invention, by applying the magnetic field of the opposite magnetic pole by the reversing magnet (6) to the handwriting on which the color tone of the specific surface is displayed, the micromagnet (2) in an arbitrary portion where the handwriting is formed is reversed. It is possible to change the color tone of any part of the handwriting without changing the form of the handwriting. At this time, only the micro magnets (2) in an arbitrary portion of the displayed handwriting are reversed and the color tone changes, so that the other micro magnets (2) not forming the handwriting do not migrate due to the received magnetic field. It is necessary to control so that only the micromagnet (2) in an arbitrary part of the handwriting displayed in the range is inverted. That is, when subjected to the action of a relatively weak magnetic field, only the handwriting displayed in a range where other micromagnets (2) do not migrate, that is, only the micromagnet (2) migrated to the display surface side is inverted. It is achieved by controlling so that.
Therefore, when such a usage is used, it is possible to obtain a multicolor display in which an arbitrary color tone is selected and an arbitrary handwriting is obtained, and a color tone of only an arbitrary portion of the obtained handwriting is changed.

In the erasing magnet (4) which is one of the electrophoretic magnets used in the panel of the present invention, it is sufficient that the micro magnet (2) is drawn from the display surface side to the back surface side. There is no particular limitation on the magnetic poles and arrangement. Further, it may be a single pole magnet or a plurality of magnets arranged in parallel. That is, any material that satisfies the above-mentioned magnetic property range can be used. When viewed from the display surface, the micro magnet (2) attracted to the back side is concealed by the component of the dispersion liquid excluding the micro magnet (2), and whichever surface faces the display surface side. This is because there is no problem.
The writing magnet (5) needs to be configured to have a specific magnetic pole.

  Hereinafter, the magnetic characteristics and the like of the migration magnet and the micro magnet will be described in more detail.

  In general, magnetic materials constituting magnets and the like are roughly classified into hard magnetic materials, semi-hard magnetic materials, and soft magnetic materials depending on the coercive force. The coercive force of magnetic materials is said to have a large range from 0.001 kA / m to 1000 kA / m. Among them, the soft magnetic material has an extremely small coercive force of 0.01 kA / m or less, and is used for a magnetic recording head of a hard disk, a magnetic core for power equipment such as a transformer. On the other hand, a hard magnetic material has a large coercive force and a large magnetic hysteresis curve, and is used as a so-called permanent magnet. A material having a coercive force intermediate between a hard magnetic material and a soft magnetic material is called a semi-hard magnetic material, and there are many materials in the vicinity of 10 to 100 kA / m, which are used as magnetic recording materials such as hard disk recording disks and magnetic tapes. It is used.

It is a well-known fact that magnets have different lines of magnetic force depending on the structure, material, shape, and the like. Even in the case of a magnet having a large surface magnetic flux density, the magnetic force applied when the distance is increased if the shape of the magnetic field lines is a flat shape or the like.
The magnetic reversal panel with migration reversal has a problem of preventing breakage of magnetic poles of a micro magnet while ensuring suitable migration display (writing / erasing), and the method for selecting the magnetic characteristics is particularly important. understood.

  In other words, in the conventional migration operation based only on the magnetic characteristics unique to the magnet, even if a magnet having a large surface magnetic flux density is selected as the migration magnet, if the magnetic field lines are flat, suitable migration is performed. However, if a magnet having a larger surface magnetic flux density is selected because a suitable migration is required, the magnetic pole of the magnet may be destroyed depending on the performance of the micro magnet. . In that respect, according to the specific scope of the present invention, it can be used without any particular problems.

Next, the magnetic characteristics of the micro magnet will be described.
If the electrophoretic magnet is used, a micro magnet having a wide range of characteristics can be used, but if a micro magnet having durability is used, electrophoretic reversal display can be suitably performed.

The coercive force of the micro magnet itself is 4.0 kA / m (50.3 Oe) or more and 600 kA / m (7560 Oe) or less, preferably 4.0 kA / m (50.3 Oe) or more and 310 kA / m (3900 Oe) or less, more preferably. A favorable effect is exhibited when the pressure is 12.0 kA / m (150.9 Oe) or more and 80 kA / m (1006 Oe) or less.
Below this range, the reversibility of the micro magnets tends to be poor, and the magnetic pole surfaces of the micro magnets are not arranged in parallel on the panel display surface side, and the display tends to be unclear or impossible. In addition, depending on the selection of the electrophoretic magnet, when a strong magnet is used, the magnetic pole of the micro magnet tends to be easily broken.
On the other hand, if it exceeds this range, the surface magnetic flux density of the resulting micromagnet itself will become too large, causing aggregation of the micromagnets and being more sensitive to the influence of external magnetic fields such as migrating magnets. There is a tendency that color mixing is likely to occur, which also causes aggregation of minute magnets and tends to cause the above problems.

Further, it is preferable that the magnetic characteristics per unit mass of the micro magnet are composed of the following a) and b).
a) Residual magnetization: 1 to 35 A · m ² / kg (1 to 35 emu / g)
b) Saturation magnetization: 1 to 100 A · m ² / kg (1 to 100 emu / g)
Residual magnetization is necessary for the micromagnet to change its direction as quickly as possible with respect to the external magnetic field, and greatly contributes to the reversibility of the micromagnet. Below this range, the micromagnet does not reverse. There is a tendency, and if it exceeds, the micro magnets tend to aggregate.
Saturation magnetization is used to generate magnetic stress that is surely attracted magnetically by an external magnetic field, and mainly contributes to the migration of the micromagnet. There is a tendency that the fine magnets are aggregated when exceeding.

Further preferable magnetic characteristics are as follows.
a ′) Residual magnetization: 3 to 16 A · m ² / kg (3 to 16 emu / g)
b ′) Saturation magnetization: 5 to 40 A · m ² / kg (5 to 40 emu / g)

  On the other hand, the micro magnets used in the present invention are mainly obtained by coloring the two magnetic poles of the N pole and the S pole in different colors. As described above, the micro magnets migrate and reverse by the action of an external magnetic field to form a display. For example, when the small magnets are gathered on the back side and the display surface is in a color tone such as a colored dispersion medium, the micro magnets are swept from the back side to the front side when the display surface of the panel is swept with the south pole of the writing magnet. The N pole face is aligned with the panel surface and becomes the color of the N pole face. When this surface is swept with the N pole of another magnet with weak magnetic force, only the micromagnet that has migrated to the surface side is reversed and the S pole surface of the micromagnet appears, changing the display color while maintaining the display shape. Can be made. Next, if scanning is performed from the back side with a relatively strong erasing magnet, the micro magnets migrate to the back side and the display disappears.

  That is, according to the present invention, by selecting the magnetic pole of the writing magnet, it is possible to selectively write in two colors, and by selecting the magnetic pole of the reversing magnet, these two colored writing parts can be changed to other colors. Can be reversed.

  In the present invention, the above-described two-color writing can be selectively performed, and the two-color writing portion can be reversed to another color. The display panel set of the present invention can be achieved by a combination of a micro magnet having a magnetic field, a relatively strong writing electrophoretic magnet and an erasing electrophoretic magnet, and an external magnet for reversing the weak magnetic force used as desired. is there.

  In order to perform better writing, that is, a relatively strong electrophoretic magnet is necessary in order to perform electrophoretic display, while in order to perform an excellent reversal display, it is necessary not to migrate micro magnets other than the portion to be inverted, and In order not to break the magnetic poles of the minute magnets, it is preferable to satisfy the conflicting conditions of selecting a relatively weak magnet as described above. However, if both migration and reversal actions are performed on the same panel as in the present invention, the magnetic pole may be destroyed depending on the design of the micromagnet when a strong migration magnet is selected in favor of good migration display. In such a case, it may be difficult to perform reverse display. On the other hand, if a weak electrophoretic magnet is selected with priority given to maintaining the reverse display performance, the magnetic force applied when performing electrophoretic display and erasing is weak, causing problems such as difficulty in electrophoretic migration. Although a good reversal display can be achieved if a micro magnet is deviated on the surface as in a conventional reversal type magnetic panel, the magnetic force applied when performing migration display and erasure is weak, and the physical properties of the dispersion liquid are reduced. There will be inconveniences such as the need for detailed control. As a result, problems such as process management problems and usage environments are limited, and migration itself becomes difficult. In other words, depending on the selection of the external magnetic field, the migration / reversal display becomes difficult, and there is a possibility that the problem that it is not possible to rewrite well is caused. Therefore, in the magnetophoretic reversal display panel used in the present invention, it is possible to widen the selection range of the electrophoretic magnet and to perform favorable electrophoretic / inverted display coupled with the selection of the relatively free electrophoretic magnet within the scope of the present invention. Therefore, even more effects can be obtained by using a micro magnet under specific conditions.

  As described above, it is important that the micro magnet can control the posture of migration and inversion. That is, it is preferable that the magnetic characteristics can be easily controlled. Conventionally, the micro magnets used in the reversal type magnetic display panel need only consider reversal performance, so that the magnetic material used is of a single system or very close to the manufacturing tolerance due to processing accuracy. It is made of a material having similar magnetic characteristics, and has not been provided with a good balance of both magnetic characteristics for contributing to migration and magnetic characteristics for contributing to inversion.

  In the present invention, the magnetic material constituting the micro magnet may be one kind. Furthermore, it is more preferable if it satisfies the said characteristic range suitably. In addition, when the micro magnets used in other inventions are made of two or more kinds of magnetic materials having different coercive forces, the range of the magnetic properties such as the apparent coercive force of the micro magnets is widened, and the portion contributing to the migration and the reversibility It is preferable because a micro magnet satisfying both of the portions contributing to the above can be obtained.

  Further, when the micro magnet is made of two or more kinds of magnetic materials including at least a first magnetic material made of a high coercive force material and a second magnetic material made of a low coercive force material, as described above, By compounding materials having different magnetic properties such as coercive force materials, the width of the magnetic properties described above is more clearly widened, and good electrophoretic properties and inversion properties can be obtained, which is more preferable.

  Here, the high coercive force material refers to a magnetic material having a relatively high coercive force including a semi-hard magnetic material centered on a hard magnetic material, and is a magnetic material that is not easily magnetized by an external magnetic field. The high coercive force material contributes to exhibiting good reversal performance when forming a reversal display of a micro magnet. For example, hexagonal magnetoplumbite type ferrite such as barium ferrite and strontium ferrite, rare earth cobalt such as samarium cobalt, cerium cobalt, yttrium cobalt, braseodymium cobalt, neodymium alloy, samarium-iron-nitrogen alloy, neodymium nanocrystal spring Examples include magnetic powder.

  On the other hand, a low coercive force material is a soft magnetic material or a semi-hard magnetic material whose coercive force is less than that of an intermediate material and has a small coercive force, and is relatively susceptible to the influence of an external magnetic field. It is. The low coercive force material contributes to exhibiting good migration performance when forming a migration display of a micro magnet. Examples thereof include magnetite, maghematite, cobalt-coated magnetite, cobalt-coated maghemite, manganese zinc ferrite, nickel zinc ferrite, lead ferrite, rare earth ferrite, and chromium dioxide.

  In the present invention, by combining magnetic materials having different magnetic properties, the micromagnet has a more clearly expanded magnetic property range, and good migration and reversal can be obtained.

  When only a high coercive force material is used, display performance such as migration and reversal when an external magnetic field is applied is often satisfied, but the influence of the magnetic force between the micro magnets and the magnetic field generated by an external magnet such as a writing pen In other words, they are not arranged in parallel to the panel surface side, but are aggregated so as to be folded. Inconvenience occurs, and it becomes difficult to obtain sufficient display and contrast. Once the micromagnets agglomerate, it is difficult to unravel and is a very important issue. Further, when the blending ratio of the micro magnets is increased and the existence ratio is increased, inversion failure tends to occur in the overlapping portion due to mutual interference, and control is limited by the blending ratio of the micro magnets. In addition, as a problem when using only a high coercive force material, the remanent magnetization generally tends to increase due to its properties, so reversal performance requires mutual magnetic force when an external magnetic field is applied. In order to avoid this tendency, the yield of the dispersed liquid tends to be oversensitive. Although there are countermeasures such as increasing the value and viscosity, the yield value and viscosity gradually increase over time, the range of changes in physical properties due to the ambient environmental temperature becomes wider, and adverse effects occur, causing the reaction of micromagnets. Problems such as worsening may occur. In order to avoid this, if the external magnetic field is increased, other problems such as difficulty in writing or re-inversion display of only the desired part may occur, and there is a possibility that problems may occur cumulatively. The balance with the electrophoretic magnet tends to be poor.

  In addition, it can also be used as a granulated magnetic material by mixing a plurality of types of magnetic materials, that is, a high coercive force material and a low coercive force material. For example, a material obtained by mixing a plurality of very fine magnetic materials such as nanomagnetic powder and hardening with a binder or the like.

  If only the low coercive force material is used, depending on the choice of the electrophoretic magnet, the magnetic flux density on the surface side may exceed the coercive force of the micromagnet, destroying the magnetic pole of the micromagnet, and causing a fatal reversibility failure. There is.

  In the present invention, when the micro magnets are made of composite materials having different magnetic properties, if the high coercive force material has a coercive force twice or more that of the low coercive force material, even better effects can be obtained. In addition, materials that can be used as magnetic materials can be appropriately mixed as long as they do not cause any problem with respect to those that are less likely to adversely affect the performance of reversibility and reversibility. Examples of such magnetic materials include magnetic metal oxides such as black magnetite, bengara or red maghematite, green chromium oxide, yellow lithium ferrite, etc. It is blended with.

  In the two types of magnetic materials in the micro magnet, the coercive force of the first magnetic material is 65.0 kA / m (817 Oe) or more and 600 kA / m (7560 Oe) or less, more preferably 65.0 kA / m (817 Oe). When the coercive force of the second magnetic material is 350 kA / m (4402 Oe) or less and less than 65.0 kA / m (817 Oe), the effect is further improved.

  If the first magnetic material falls below this range, the reversibility of the micromagnet becomes poor as in the case of using the low coercivity material alone, and the magnetic pole surface of the micromagnet is arranged uniformly in parallel on the panel display surface side. The display tends to be unclear or impossible.

  When the coercive force of the first magnetic material increases, the micromagnet becomes magnetically stable, and at the same time, the remanent magnetization generally tends to increase, and the reversal performance is improved. It becomes easy to be. However, if it exceeds the above range, there is a restriction that the blending design becomes delicate. In other words, since the magnetic characteristics are easily affected by a slight loss of the blending balance, if the blending is more than the designed blending, the surface magnetic flux density of the resulting micromagnet itself becomes too large, and the micromagnet When it is blended in a small amount, it tends to cause inversion problems similar to those when it falls below the above range of the first magnetic material. There is a tendency that the balance with the electrophoretic magnet of the present invention is deteriorated, such as a side that is difficult to handle in design.

  Further, if the second magnetic material exceeds this range, the surface magnetic flux density of the micromagnet itself becomes too large, as in the case of using a high coercive force material alone, and the micromagnet tends to aggregate. In addition, if a small amount of magnetic material is blended to satisfy the reversal performance, there is a tendency to result in poor migration and the balance with the migration magnet of the present invention tends to deteriorate.

  Therefore, when either the first magnetic material or the second magnetic material is out of the above range, it is difficult to balance both the migration performance and the reversal performance of the micromagnet. The balance tends to get worse.

  Here, the boundary between the coercive force of the first magnetic material and the second magnetic material is set to 65.0 kA / m (817 Oe), which is the criticality that has the best balance of reversibility and migration performance. For example, the point was found experimentally. The magnetic force attenuates in inverse proportion to the distance while being affected by the migration magnet. Therefore, 65.0 kA / m (817 Oe) is affected by the influence of the surface panel, the dispersion liquid, and the surface coating and binder components in the micro magnet. It becomes a good critical point. Further, the second magnetic material is preferably a semi-hard magnetic material of 0.5 kA / m (6.3 Oe) or more and less than 65.0 kA / m (817 Oe). The soft magnetic material is theoretically a material of about 0.001 kA / m or less including 0 kA / m (0 Oe), and effectively acts as a magnetic property of the magnetic material used in the present invention. However, semi-hard magnetic materials and soft magnetic materials having extremely small coercive force have a problem that it is generally difficult to process them as fine powders. Since the micromagnet is composed of the composite material as described above, it is preferable that the magnetic material is coated in the form of fine powder, but because of its nature, it is difficult to process it as a fine powder. The size of the micromagnet becomes relatively large, and there is a risk of inconvenience in reversibility and migration.

The shape of the micromagnet used in the present invention is not particularly limited as long as the S pole face and the N pole face are colored with different colors, but the display formability when written with a so-called magnetic pen (electrophoretic magnet) is used. A layered body in which fine magnets color-coded based on the sharpness of display formed are coated with a coloring composition of another color on one side of a layer in which a magnetic material is dispersed in a synthetic resin and / or synthetic rubber composition of a specific color Those obtained by cutting or pulverizing are preferred. Alternatively, a layer in which a magnetic material is dispersed on a colored metal vapor-deposited layer and is cut or pulverized, or a layer in which micromagnets are dispersed in a specific color synthetic resin and / or synthetic rubber composition A preferable example is one obtained by cutting or pulverizing a layered body in which colored sheets of other colors are laminated on one side.
If both sides are the same color, it can be used as a bright color migration display panel with good contrast, and such an embodiment is also included in the present invention.

The dispersion liquid in which the micro magnets are dispersed preferably contains a colorant, is colored, and has a specific yield value. The reason for the color is that when the micro magnets migrate to the back side as described above, the display is erased.In other words, the color of the micro magnets separated from the front side and migrated to the back side is concealed, and the migration display is ensured.・ This is for erasing. At this time, the color tone of the micro magnet can be concealed by completely concealing it, or the expression color of the micro magnet can be substantially erased by using a color tone having a complementary color relationship. Various pigments and dyes are appropriately selected as the colorant. The yield value is necessary for preventing fine magnets in the dispersion liquid from being properly dispersed and preventing sedimentation. That is, a dispersion liquid of about 0.15 to 7.5 N / m ² , more preferably about 0.3 to 5.0 N / m ² is preferable. In order to obtain these physical property values, conventional methods are appropriately used, and can be obtained by appropriately blending a dispersion medium, a thickener, a coloring material, an antistatic agent and the like. The viscosity is necessary for migration or inversion of only that portion when a magnetic field is applied to the display panel, and is preferably a dispersion liquid having a viscosity of about 3 to 350 mPa · s.

  The support material for holding the dispersion liquid is not particularly limited, and is a support body that is provided with a gap and sealed around the periphery of the two sheets, and a support body in which a substantially hexagonal honeycomb cell is disposed between the two substrates. A support having microcapsules arranged on a substrate is used as appropriate.

  Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings, taking examples of magnetophoretic reversal display panels.

<Production of magnetophoretic reversal display panel>
<Micro magnet example 1>
A magnetic ink in which the composition shown in Table 1 is dispersed and dissolved in methyl ethyl ketone (hereinafter referred to as “MEK”) on a polyethylene terephthalate (hereinafter referred to as “PET”) film having a thickness of 25.0 μm is coated and dried by the following means. A blue magnetic sheet was obtained. At this time, the thickness of the blue magnetic ink layer was 25.5 μm, and the coating mass was 51.3 g / m ² .
(Procedure 1)
The resin component was dissolved in MEK at the blending ratio shown in Table 1, and two types of magnetic materials having different magnetic properties were added thereto, and then dispersed with an attritor for 1 hour.
(Procedure 2)
To this dispersion, a pigment dispersion in which a blue pigment is dispersed in MEK was added at a blending ratio shown in Table 1, followed by mixing and stirring to obtain a magnetic ink exhibiting a blue color. (Solid content 60% by mass)
(Procedure 3)
This magnetic ink was applied and dried with a wire bar to obtain the above-described blue magnetic sheet.
Next, a white ink having the following composition was applied and dried on the blue magnetic layer of the sheet according to the above procedure, and a white ink layer was laminated on the blue magnetic layer.
The white ink layer had a thickness of 8.0 μm and a coating mass of 16.0 g / m ² .
White pigment dispersion 60.0 parts by mass (titanium oxide pigment MEK dispersion: solid content 66.0%)
31.8 parts by mass of resin (epoxy resin MEK solution: solid content 60.0%)
Solvent 8.2 parts by mass (MEK)
Next, a pink ink layer having the following composition was applied and dried on the white ink layer of the sheet according to the above procedure, and the pink ink layer was laminated on the white layer.
The pink ink layer had a thickness of 8.0 μm and a coating mass of 9.6 g / m ² .
Pink pigment dispersion 75.0 parts by mass (pink pigment MEK dispersion: solid content 30.0%) Resin 25.0 parts by mass (epoxy resin MEK solution: solid content 60.0%)
The three layers thus obtained were 41.5 μm in total and a coating sheet with a coating mass of 76.9 g / m ² .
Subsequently, this coating layer was magnetized together with the base film, the blue surface was made the N pole, and the pink surface was made the S pole, and then the coating layer was peeled off from the base film to form flakes, and finely pulverized with a cutter mill pulverizer After that, sieving was performed to obtain a micro magnet in which the color of the magnetic pole was separately applied to the blue / pink color having a particle diameter in the range of 63 to 180 μm. Here, the magnetic characteristics of the micro magnets are shown in Table 1.

<Magnetic property measurement method>
In the present invention, the coercive force, residual magnetization and saturation magnetization of the micro magnet are measured with a vibrating sample magnetometer (VSM-P7-15 type manufactured by Toei Kogyo Co., Ltd.), and the method is as follows. That is, when a minute magnet is tightly packed in a measurement case consisting of the following lid (A) and main body (B), and a magnetic field of 684.4 kA / m of the magnetometer is applied to this measurement case, hysteresis is generated on the XY recorder. A curve is recorded. From this hysteresis curve, coercive force, residual magnetization and saturation magnetization are obtained. For residual magnetization and saturation magnetization, this value is divided by the mass of the micro magnet packed in the measurement case to convert the residual magnetization and saturation magnetization (A · m ² / kg) per unit mass.
(A) A lid of acrylic resin consisting of a disc having a thickness of 1 mm and a diameter of 7.0 mm, and a protrusion raised from the disc surface to one side and having a height of 0.5 mm and a diameter of 6 mm. (B) The inner diameter is 6.0 mm. Acrylic resin bottomed cylindrical case body with outer diameter of 2.5mm and outer diameter of 7.0mm and depth of 4.0mm

<Panel Example 1>
On the other hand, a thickener was added to isoparaffin having a viscosity of 3.2 mPa · S at 20 ° C. as a dispersion medium, this was heated and dissolved, and then cooled to prepare a thickener paste. Next, a thickener paste, a coloring material, and an antistatic agent were added to isoparaffin and stirred to obtain a plastic dispersion having the following blending ratio (100 parts by mass in total).
Thickener 1.3 parts by mass [ethylene bis-12-hydroxystearic acid amide (made by Ito Oil Co., Ltd .: trade name ITOHWAX J-530)]
Colorant 1.4 parts by mass (titanium oxide)
Antistatic agent 0.1 part by mass Dispersion medium remaining part (Esso Chemical Co., Ltd .: trade name ISOPAR M)
Next, the foil dispersion-like micro magnet example 1 coated in the blue / pink color is mixed with the plastic dispersion at a ratio of 10.7 parts by mass of the micro magnet to 89.3 parts by mass of the dispersion. Stirring was performed to obtain a plastic dispersion liquid having a yield value as shown in Table 1 in which fine magnets are uniformly dispersed in the dispersion liquid.
The yield value is measured by using a Brookfield viscometer (BL type manufactured by Tokyo Keiki Co., Ltd.) in the same manner as conventionally used, and the rotor is rotated at low speed (0.3 rpm) in a dispersion liquid. It measured by the method of reading the twist angle. The rotor used was the No. 2 rotor attached to the BL type viscometer.
Further, this dispersion liquid was bonded to one surface of a vinyl chloride resin film having a plate thickness of 0.25 mm using an adhesive, and the cell size was 3.5 mm, a regular hexagonal shape and a height of 1.0 mm were made of a vinyl chloride resin honeycomb. The cell is filled into the cells of the multi-cell structure, and then the open surface of the multi-cell structure is covered with a vinyl chloride resin film having a thickness of 0.08 mm using an adhesive, and the dispersion liquid is enclosed in the cell. To obtain a display panel.

<Other micro magnet examples and panel examples>
Example of micro magnet 3, 11-12, 15, 24 (blue / pink)
A micromagnet was produced in the same manner as the micromagnet example 1 except that the first magnetic layer was changed to those shown in Tables 1 to 4. Moreover, except having mix | blended the thickener suitably as Tables 1-4, it made into the panel after making it into the dispersion liquid like the panel example 1, and evaluated.

Micro magnet examples 2, 4 to 10, 13 to 14, 16 to 23, 25 to 33, reference examples 1 to 8 (gold / black)
The first magnetic layer is as shown in Table 1, and a yellow colored layer and an aluminum vapor-deposited layer are provided on a PET film which has been subjected to a release treatment with a thickness of 25.0 μm so as to have a combined thickness of 3.0 μm. A micro magnet was produced in the same manner as in the micro magnet example 1 except that the first magnetic layer was applied on the vapor deposition layer and the white ink layer and the pink ink layer were not applied. Moreover, except having mix | blended the thickener suitably as Tables 1-5, it was made into the panel and evaluated by making it into a dispersion liquid like the panel example 1.

(Note) BaO.6Fe2O3 ... Barium ferrite SrO.6Fe2O3 ... Strontium ferrite NixZn1-xFe2O4 (O <x≤1) ... Nickel zinc ferrite Fe3O4 ... Magnetite Co-γ-Fe2O3 ... Cobalt coating Coated maghemite Co-Fe3O4 Cobalt-coated magnetite

<Electrophoresis magnet>
<Writing magnet>
Example 1
A writing magnet was prepared using a neodymium alloy magnet (φ1 × 5 mm), a surface magnetic flux density of 155 mT, and a “magnetomagnetic flux density in the vicinity of the inner wall surface on the opposite side of the panel where the electrophoretic magnet of the support material acts” 30 mT.

<Measurement method of “magnetic flux density in the vicinity of the inner wall surface on the opposite side of the panel where the migration magnet of the support material acts”>
When the electrophoretic magnet is applied to one surface of the support member of the magnetophoretic reversal display panel, a distance (1 mm in this embodiment) corresponding to the vicinity of the inner wall surface on the opposite side of the panel is set, and the magnetic flux density applied to that portion is set. The magnetic flux density of the electrophoretic magnet was measured as “the magnetic flux density in the vicinity of the inner wall surface on the opposite side of the panel where the electrophoretic magnet of the support material acts”. (See Figure 13)
For the measured value, the maximum value in the above measurement was defined as the magnetic flux density in the present invention.
In the measurement, “GAUSS METER MODEL GM-4000, manufactured by Electronic Magnetic Industry Co., Ltd.” was used.

<Measurement method of “magnetic flux density in the vicinity of the inner wall surface on the panel surface side where the migration magnet of the support material acts”>
“The magnetic flux density in the vicinity of the inner wall surface on the panel surface side on which the migration magnet of the support material acts” is the same as the measurement on the opposite side, “when the micro magnet (2) is positioned in the vicinity of the surface (10 ′)”. Magnetic flux density ".
When the electrophoretic magnet is allowed to act on the surface side of the support member of the magnetophoretic reversal display panel, the distance corresponding to the thickness of the surface is set as the position where the micromagnet (2) migrates near the surface (10 ′) The magnetic flux density of the electrophoretic magnet was measured by setting the magnetic flux density applied to the portion as “the magnetic flux density in the vicinity of the inner wall surface on the panel surface side on which the electrophoretic magnet of the support material acts”.
For the measured value, the maximum value in the above measurement was defined as the magnetic flux density in the present invention.
In the measurement, “GAUSS METER MODEL GM-4000, manufactured by Electronic Magnetic Industry Co., Ltd.” was used.
In this example, since a film having a thickness of 0.08 mm to 0.25 mm was used as the display panel support, there was no significant difference from the surface magnetic flux density, and the surface magnetic flux density value was used approximately. It was.

Example 2
A writing magnet was prepared using a neodymium alloy magnet (φ1.5 × 8 mm), a surface magnetic flux density of 247 mT, and “magnetomagnetic flux density in the vicinity of the inner wall surface on the opposite side of the panel where the electrophoretic magnet of the support material acts” 59 mT.

Example 3
A writing magnet was produced using a neodymium alloy magnet (φ2 × 5.5 mm), a surface magnetic flux density of 266 mT, and a “magnetic flux density in the vicinity of the inner wall surface on the opposite side of the panel where the electrophoretic magnet of the support material acts” 73 mT.

Example 4
A writing magnet was prepared using a neodymium alloy magnet (φ3 × 6 mm), a surface magnetic flux density of 372 mT, and a “magnetomagnetic flux density in the vicinity of the inner wall surface on the opposite side of the panel on which the electrophoretic magnet of the support material acts” 150 mT.

Using the writing magnets of Examples 1 to 4 and writing on the panel example using the micro magnet example as described below, it was possible to repeat writing well and break the magnetic pole of the micro magnet. There was no. (Excluding reference examples)
Thus, even if the surface magnetic flux density is the same (magnetic flux density at the position of the surface side (10 ′)), depending on the configuration, “in the vicinity of the inner wall surface on the opposite side of the panel on which the migration magnet of the support material acts is applied. There is a case where a difference occurs in the “magnetic flux density” and the magnetic poles of the micro magnets are not destroyed or color mixing is not caused. The above-mentioned “magnetic flux density in the vicinity of the inner wall surface on the opposite side of the panel on which the migration magnet of the support material acts” It is effective to set a specific range. Furthermore, it can be said that the magnetic flux density on the surface side is a limit point at which the micro magnet is directly broken, and it has been found that the micro magnet tends to be hard to break within the range of these examples.

<Erase magnet>
Example 5
Ferrite rubber magnet (L = 100 mm) (W = 6 mm × t = 1 mm) (magnetization pitch 4 mm), surface magnetic flux density 60.4 mT, “magnetic flux in the vicinity of the inner wall surface on the opposite side of the panel on which the migration magnet of the supporting material acts An erasing magnet was prepared using an electrophoretic magnet having a density of 20.9 mT.

Examples 6-9, Comparative Example 1
Using a ferrite rubber magnet (L = 100 mm), the width × thickness, magnetization pitch, surface magnetic flux density shown in Table 6, “Magnetic flux density near the inner wall on the opposite side of the panel on which the migration magnet of the support material acts” An erasing magnet was prepared using a migration magnet (magnetic force at a distance of 1 mm).

Examples 10-12
Using a ferrite rubber magnet (L = 100 mm), the width × thickness, magnetization pitch, surface magnetic flux density shown in Table 6, “Magnetic flux density near the inner wall on the opposite side of the panel on which the migration magnet of the support material acts” An erasing magnet was prepared using a migration magnet (magnetic force at a distance of 1 mm).

  In addition, the aspect of Examples 10-12 was shown in FIG. That is, the condition of the multipolar magnet is changed. Also from this result, it is understood that “magnetic flux density in the vicinity of the inner wall surface on the opposite side of the panel on which the migration magnet of the support material acts” directly affects the migration (erasability).

<Writing and erasing display panel examples>
As shown in FIG. 1, the micro magnets (2) are drawn from the back surface of the panel (1) to the back surface side using the erasing magnet (4) to prepare for writing. At that time, the dispersed liquid component excluding the micromagnet (2) is colored and conceals the micromagnet (2), so that a uniform color tone of the dispersion medium is obtained as the display (7) (first). 1 color tone).
Next, the display surface of the panel (1) is swept from the surface of the panel as shown in FIG. 2 with the south pole of the writing magnets (5) of Examples 1 to 4, and the micro magnet (2) is removed from the back side. While migrating to the display surface side (partially reversed), the N pole surface of the micro magnet (2) was aligned with the display surface side of the panel to obtain the handwriting (8) of the color tone of the N pole surface (second color tone). .
Further, as shown in FIG. 3, when this surface is swept by the N pole of another reversal magnet (6) having a weak magnetic force, the display surface side is not attracted to the non-migrated fine magnet (2-B). Only the micromagnet (2-A) migrating to the reverse is reversed, and the handwriting (9) by the S pole surface composed of the migrating micromagnet (2-A) appears, and the display shape is changed. The display color could be changed while maintaining this (third color tone).
Finally, scanning was performed from the back side with the erasing magnets (4) of Examples 5 to 12, and the micro magnet (2) was migrated to the back side to erase the display (first color tone).

  Each evaluation of the magnetophoretic reversal display panel, the electrophoretic magnet, and the display panel set in each example is shown in Tables 1-6.

<Panel evaluation method>
The evaluation test follows the above writing and erasing procedures. 1. electrophoretic properties; 2. Reversibility (cohesiveness) 3. Print quality The evaluation was conducted on the items of comprehensive evaluation including whether or not the magnetic pole of the micro magnet was broken and whether or not there was color mixing.
Electrophoretic properties ◎: The micro magnets have migrated completely to the front side, and there is no residue on the back side. It is difficult to migrate to the side, and there is a residue on the back side. ×: There is no minute magnet that migrates to the front side or the amount is extremely low (aggregation)
◎: There is no aggregation between the micromagnets, the alignment is good, and it is completely inverted. ○: The aggregation between the micromagnets is somewhat observed, but it is inverted. △: Although the aggregation between the micromagnets is observed, Almost reversed ×: Print quality that does not invert or extremely small micro magnets ◎: Display is clear, contrast is good, print quality is good ○: Display with good contrast △: Micro magnets X: Sedimentation or electrophoretic failure is observed, and display is possible but partly unclear ×: Overall evaluation where contrast is poor and display is unclear or cannot be displayed ◎: Very good and practical panel ○: Good and practical Panel △: Panel that has some problems but can be used ×: Panel that has poor performance and cannot be used

  The evaluation of each example is shown in the table and will be described in detail below.

  The micro magnet examples 1 to 33 were generally good although there were performance differences.

  In particular, for the micro magnet examples 1 to 5, 9 to 10, and 15, all the evaluation items were balanced and very good. As can be seen from micro magnet examples 5 and 10, even if the yield value is changed, it is difficult for the difference in performance to occur, the degree of freedom in designing the physical properties of the dispersion liquid is increased, and the performance deterioration due to various conditions such as aging and environmental temperature is small. In addition, the range of selection of the electrophoretic magnet and the like was also suitable.

  The micro magnet examples 8, 13, 18, and 20 were generally good, although a slight tendency of aggregation was observed.

  Regarding the micro magnet examples 6, 11, 12, 24, and 27, since the residual magnetization was slightly low, there was a tendency to generate non-reversed micro magnets, but the overall results were good.

  In the micro magnet example 7, since the residual magnetization was further lower, there was a tendency that a little more non-inverted micro magnets were generated than in the micro magnet example 6 or the like, but it was generally good.

  Since the micro magnet example 14 showed an agglomeration tendency in the micro magnet example 13, it was possible to obtain a more preferable form by controlling the yield value.

  The micromagnet example 16 has a slight difficulty in migration due to its low saturation magnetization. However, the micromagnet example 16 is generally good, and the micromagnet example 17 can be controlled even better when the yield value is lowered. did it. Further, since the remanent magnetization was somewhat low, there was a tendency for non-reversed micromagnets to be generated, but the overall condition was good.

  Since the micro magnet example 19 showed a tendency to agglomerate slightly, it was possible to suppress the agglomeration by increasing the yield value, but the yield value had to be set high, and the dependence on the change with time and the environmental temperature was high. There were restrictions, such as having to make the electrophoresis magnet strong.

  The micro magnet example 21 had good migration performance, but had difficulty in inversion performance, and was a usable limit level.

  The micro magnet example 22 showed a slight tendency to agglomerate, but the micro magnet could migrate and was at a usable limit level. In addition, since a tendency to agglomerate was observed, the yield value was increased in the micro magnet example 23. However, since the residual magnetization and saturation magnetization values were low, the electrophoretic properties were affected, and the limit level that can be controlled by the yield value. I found out.

  In the micro magnet example 25, since both the residual magnetization and the saturation magnetization were low, it was difficult for the micro magnets to migrate, and there was a tendency for non-inverted micro magnets to be generated. It was also a usable limit level.

  For the micro magnet examples 28 and 31 to 33, the electrophoretic property is good, but the reversibility is slightly inferior, and a relatively weak electrophoretic magnet that does not break the magnetic pole of the micro magnet must be selected. / There were many restrictions such as affecting reversal performance. In addition, since the micro magnet examples 29 to 30 have difficulty in migration and tend to be aggregated, there are many restrictions on adjustment of proper migration magnets and dispersion liquid properties. Although -33 was (triangle | delta) by comprehensive evaluation, it was a little inferior compared with the example of another micromagnet.

  In Reference Examples 1 to 8, since the magnetic material was generally a single system and a magnetic material having sufficient performance was not used, there was a limit to the control of the magnetic characteristics of the micromagnet, and it was difficult to obtain satisfactory performance. .

  In Reference Examples 1 and 2, it was difficult for the micromagnets to migrate, and migration was performed when a strong electrophoretic magnet was used, but the micromagnets aggregated and there was no contrast. Reference Examples 3 and 4 are slightly better than Reference Examples 1 and 2, but still have poor migration properties. If a strong migration magnet exceeding the preferred range of the present invention is used, the magnetic poles of the micro magnets are broken. It was.

  In Reference Examples 5 and 6, the electrophoretic property was good, but the reversibility was poor, and when a slightly strong electrophoretic magnet was used, the magnetic poles of the micro magnets tended to be easily broken. Reference Examples 7 and 8 were inferior in electrophoretic properties because the micromagnets did not invert so much that they could not be reversed at all.

  In Reference Examples 2, 4, 6, and 8, the yield value control was attempted for those in Reference Examples 1, 3, 5, and 7, respectively, but it was difficult to achieve a usable level.

  According to the electrophoretic magnet for a magnetophoretic reversal display panel and a display panel set using the same, display and erasure can be performed repeatedly, and in particular, two colors which are the color tones of the front and back of the micro magnet on the background color. The three colors can be expressed together with the color tone of the dispersed liquid component excluding fine magnets such as a dispersion medium. Further, the magnetic display has an excellent effect that the color can be changed by selecting an arbitrary part of an arbitrary handwriting. In other words, it is possible to change the color of the important points of the characters once written, which could not be done on a blackboard or whiteboard, or to change the color only where you want to attract attention with an advertising display etc. In addition, it has an excellent effect that it can be easily restored when it is no longer needed. When used in place of a blackboard or whiteboard at school, etc., the effect is better.

It is a figure which shows the (a) schematic diagram (b) display example at the time of displaying a 1st color tone. It is a figure which shows the (a) schematic diagram (b) display example at the time of displaying a 2nd color tone. It is a figure which shows the (a) schematic diagram (b) display example at the time of displaying a 3rd color tone. It is a schematic diagram which shows the display mechanism in the magnetophoretic inversion display panel set of this invention. It is a schematic diagram which shows the display mechanism in the magnetophoretic inversion display panel set of this invention. It is a schematic diagram which shows the micro magnet behavior mechanism in the magnetophoretic inversion display panel set of this invention. It is a schematic diagram which shows the display mechanism in the conventional magnetophoretic display panel. It is a schematic diagram which shows the display mechanism in the conventional magnetic inversion type | mold display panel. It is a schematic diagram which shows the example of the electrophoresis magnet for magnetophoretic inversion display panels of this invention. It is a schematic diagram which shows the example of the electrophoresis magnet for magnetophoretic inversion display panels of this invention. It is a schematic diagram which shows the example of the electrophoresis magnet for magnetophoretic inversion display panels of this invention. It is a schematic diagram which shows the example of the electrophoresis magnet for magnetophoretic inversion display panels of this invention. It is a schematic explanatory drawing at the time of measuring the magnetic flux density of the migration magnet in the present invention. It is a schematic diagram which shows the structural example of the electrophoresis magnet for magnetophoretic inversion display panels of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Display panel 2 Micro magnet 3 Dispersed liquid 4 Erase magnet (electrophoresis magnet)
5 Writing magnet (electrophoresis magnet)
6 Inverting magnet 7 Display of first color tone 8 Handwriting of second color tone 9 Handwriting of third color tone 10 Surface plate 10 Near the inner wall surface of the panel surface on which the moving magnet of the supporting material acts 11 Moving magnet of the supporting material The surface on the opposite side of the panel on which 11 is applied 11) Near the inner wall surface on the opposite side of the panel on which the migration magnet of the supporting material is applied 12 Partition plate 13 Magnetic particle 14 Probe

Claims (4)

  At least a dispersion liquid having a yield value obtained by dispersing micro magnets having colors different from the color of the dispersion medium and different from the front and back colors in a dispersion medium containing a colorant, and the dispersion liquid. An electrophoretic magnet used in a magnetophoretic reversal display panel having a supporting material to be held, wherein the magnetic flux density in the vicinity of the inner wall surface on the panel surface side on which the electrophoretic magnet of the supporting material acts is 400 mT or less, and An electrophoretic magnet for a magnetophoretic reversal display panel, wherein a magnetic flux density in the vicinity of an inner wall surface is 10 mT or more and 300 mT or less.   2. The electrophoretic magnet for a magnetophoretic reversal display panel according to claim 1, wherein the coercive force of the micro magnet in the magnetophoretic reversal display panel is 4.0 kA / m or more and 600 kA / m or less. The remanent magnetization per unit mass of the micro magnet in the magnetophoretic reversal display panel is 1 to 35 A · m ² / kg, and the saturation magnetization is 1 to 100 A · m ² / kg. Electrophoresis magnet for reverse display panel. At least a dispersion liquid having a yield value obtained by dispersing micro magnets having colors different from the color of the dispersion medium and different from the front and back colors in a dispersion medium containing a colorant, and the dispersion liquid. A display panel set comprising at least a magnetophoretic reversal display panel including a supporting material to be held and the electrophoretic magnet according to any one of claims 1 to 3.

Images