JPH0971042A - Magnetic recording body and its recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic recording body of high resolution, clear, and of superior image stability in which different light intensity is displayed between magnetized sections and unmagnetized sections and the reversible display and color display can be provided. SOLUTION: In a magnetic recording body 1, at least flake-shaped magnetic particles, a coloring agent and dispersion mediums representing the solid phase state at the normal temperature, in which the above-said particles and the coloring agent are dispersed, and having different melting points for respective colors of the coloring agent are contained on a substrate 11 composed of a non-magnetic material, and a magnetic recording layer 12 in which microcapsules of two kinds or more representing different color phases are dispersed in a binder is formed. The dispersion mediums are melted in order of decreasing melting points by heating the magnetic recording layer 12, and the flake-shaped magnetic particles are oriented by applying magnetism in the horizontal or vertical direction, and images corresponding to respective colors of microcapsules are recorded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording body for displaying a pattern such as an image by applying a magnetism with heating and a recording method therefor, and in particular, color display is possible,
In addition, the present invention relates to a reversible display magnetic recording medium having excellent resolution and image stability, and a recording method thereof.

[0002]

2. Description of the Related Art Conventionally, as a magnetic recording medium utilizing magnetism, a magnetic field is applied to a suspension in which magnetic particles are dispersed in a coloring dispersion medium, as described in, for example, JP-A-48-56393. By doing so, a method is known in which the magnetic particles are moved to change the color of the colored dispersion medium and display is performed.

However, in such a magnetic recording medium, when the suspension is sealed between two substrates and one of the substrates draws characters and patterns with a magnetic pen to apply magnetism, the magnetic particles of the suspension are attracted. Although the characters and patterns are obtained as they are, since the specific gravity of the magnetic particles is much larger than that of the dispersion medium, the attracted magnetic particles have the drawback that the characters and patterns cannot be retained for a long time because they settle with time. .

Further, since all the magnetic particles magnetized by the magnetic pen are attracted to the magnetic pen, the magnetic particles existing apart from the magnetic pen are also attracted, so that only unclear characters and patterns are obtained. It also had drawbacks. In order to prevent sedimentation of magnetic particles, for example, if the magnetic particles are made finer or the magnetic particles are coated with a polymer having a low specific gravity, and the apparent specific gravity of the magnetic particles approximates that of the dispersion medium, the magnetic particles Since the force becomes extremely small, it becomes difficult to be sucked by the magnetic pen, which causes a defect that it is not possible to obtain a clear character or pattern with high density.

Further, if the apparent specific gravity of the magnetic particles is approximated to that of the dispersion medium, the magnetic particles are difficult to be attracted to the opposite side of the substrate even when characters and patterns are erased, and the particles cannot be completely erased. Repeatedly, it turned black overall, which was not practical.

As a mode for solving these drawbacks, for example, Japanese Patent Publication No. 57-27463 and Japanese Patent Laid-Open No. 62-53.
As described in Japanese Patent No. 359, as a dispersion medium,
By using a liquid that has a yield value of a certain value or more, or by using a thickener, clear and high-contrast characters and images without blur can be displayed, and the display can be kept stable for a long time, and erasure can be completed completely. There are known magnetic recording media that can be neatly cleaned.

However, this magnetic recording medium is formed by forming honeycomb cells each having a side and a depth of about 2 mm on the entire surface of a transparent plastic sheet, and the magnetic particles and the white pigment are contained in the cells. The suspension was injected into a dispersion medium, and the suspension was sealed with a transparent sheet, which had the following drawbacks. That is, since the image is formed by moving the magnetic particles from the back surface to the front surface in the honeycomb-shaped cell, it is impossible to make the resolution of the image smaller than that of the honeycomb-shaped cell. Further, it is difficult to form honeycomb cells, to make the honeycomb cells large or very small, and to inject a suspension into the honeycomb cells.

As another form, for example, Japanese Patent Laid-Open No. Hei 2
As described in JP-A-146082 and JP-A-4-233581, unlike a magnetic recording medium in which magnetic particles and pigments are sealed in a honeycomb-shaped cell as described above,
A magnetic recording medium is known in which magnetic particles are enclosed in microcapsules and coated on a support. According to this method, the resolution can be increased by controlling the particle size of the microcapsules, and the manufacturing process is easy. Further, various films and the like can be selected as the substrate on which the microcapsules are applied, and the shape and size can be freely selected.

However, the image formation shown here is performed by the following method. First, the permanent magnet attracts the light-absorbing magnetic particles in the microcapsule to the back surface side of the magnetic recording medium, and the light-reflecting non-magnetic particles remain on the surface of the magnetic recording medium. It becomes the color of non-magnetic particles and is in an erased state. Then, by applying and recording magnetism from the surface of the magnetic recording medium by a permanent magnet, the light-absorbing magnetic particles are magnetically attracted to the surface, and desired characters and images are formed. Therefore, in such image formation, it takes a long time to attract the magnetic particles, resulting in a magnetic recording material having poor sensitivity.

Further, as another embodiment utilizing the microcapsules, for example, JP-A-1145637, JP-A-63-153197, JP-B-4-7518, JP-A-6-79986 and JP-A-6-79986. 6-9206
No. 8, or Eyne S. Trumble
P. S. & E. 7 213 (1963), there is known a magnetic recording medium in which light-absorbing magnetic particles and light-reflecting non-magnetic particles are encapsulated in microcapsules.

In the image forming method of this embodiment, first, when the magnetic recording medium is manufactured, the magnetic particles in the coated capsules are orientated in advance in parallel with the plane of the magnetic recording medium so that all the incident light is reflected to make it appear bright. Next, magnetic recording causes magnetic particles to rotate and scatter incident light.
It becomes absorbed, and contrast is generated, and a black image is formed.

However, the magnetic recording material thus obtained has a magnetic force over a wide range, and therefore has a resolution extremely inferior to that of recording by other heat or light. Furthermore, since the magnetic recording medium can be easily printed and erased by magnetic force, the image may be fogged in the unprinted portion or the image may be erased by just touching the magnet. It has the drawback of poor stability.

Further, as a magnetic recording medium capable of color display, for example, the N and S poles of the magnetic particles described in JP-A-1-63991 are colored in different colors, and the magnetic particles are rotated by applying a magnetic force. A magnetic recording body for color display, and magnetic particles having different magnetic properties described in JP-A-4-175196 are colored in different colors,
2. Description of the Related Art There is known a magnetic recording body that controls a magnetic field strength to perform color display.

In the former case, however, the magnetic recording medium for color display is manufactured by spraying a coloring dye solution on fine magnetic particles to color the magnetic recording particles. For example, the N and S poles of the magnetic particles have different colors. It is difficult to color fine magnetic particles when colored in the background, and the color coding of each pole is incomplete. In the latter case, it is difficult to control the magnetic field strength at the time of display, and there is ambiguity in controlling the magnetic field. Both of them have a drawback that clear color display cannot be performed.

[0015]

As described above, the conventional magnetic recording material using the magnetic material as the display means cannot display an image of high resolution, and the image displayed by the influence of external magnetism is not displayed. Since an image is erased in a partially or unreadable state or fog occurs in an unprinted portion, stable recording cannot be performed, and further clear color display cannot be performed. Further, there has been no magnetic recording material having mobility of the magnetic particles contained therein, that is, good recording reactivity and stability of recorded image.
Therefore, the present invention provides a magnetic recording medium that exhibits reversible display and color display, in which a portion to which a magnetic field is applied and a portion to which a magnetic field is not applied show different brightness and darkness, have high resolution, are clear, and have excellent image stability. The purpose is to provide.

[0016]

The present invention has been made to achieve the above object, and the invention according to claim 1 is such that at least flaky magnetic particles are provided on a support made of a non-magnetic material. , A colorant, and a dispersion medium in which these are dispersed and exhibiting a solid phase state at room temperature, and two kinds of different hues are obtained using a dispersion medium having a different melting point for each color of the colorant. A magnetic recording medium is characterized in that the above-mentioned microcapsules are dispersed in a binder to form a magnetic recording layer.

According to a second aspect of the invention, in the magnetic recording medium according to the first aspect, the dispersion medium has a melting point of 35 ° C. or higher and 100 ° C. or higher.
The organic compound is in the following range.

According to a third aspect of the invention, in the magnetic recording medium according to the first aspect, the coloring agent is a dye or a pigment.

According to a fourth aspect of the present invention, in the magnetic recording medium according to the first aspect, the average particle size of the microcapsules is 10 μm.
It is characterized by being between m and 1000 μm.

According to a fifth aspect of the invention, in the magnetic recording medium according to the first aspect, the average major axis of the flaky magnetic particles is 5 μm.
It is characterized in that it is between m and 30 μm, and the average thickness is between 0.1 μm and 5 μm.

According to a sixth aspect of the invention, in the magnetic recording medium according to the first aspect, a protective layer is formed on the magnetic recording layer.

According to a seventh aspect of the present invention, at least a flake-shaped magnetic particle, a coloring agent, and a dispersion medium which is a solid state at room temperature and is formed by dispersing these flaky magnetic particles and a colorant are included on a support made of a non-magnetic material. And a magnetic recording medium formed by forming a magnetic recording layer in which two or more kinds of microcapsules expressing different hues are dispersed and arranged in a binder by using a dispersion medium having a different melting point for each color of the colorant. Then, a recording step of partially heating and melting the magnetic recording layer in the order of higher melting point in accordance with the recorded image and magnetically applying in the horizontal or vertical direction to orient the flake-shaped magnetic particles, and the next higher melting point or higher. A recording method for a magnetic recording medium, characterized in that an image is recorded corresponding to the color of the microcapsule by heating the entire surface and a fixing process by applying a magnetic force in the vertical or horizontal direction.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. 1 is a sectional view showing an embodiment of a magnetic recording medium of the present invention, FIG. 2 is a sectional view showing an embodiment of a microcapsule used in the magnetic recording layer of the present invention, and FIG. 3 is a sectional view of the present invention. 5 is a sectional view showing an unrecorded state of the magnetic recording body of FIG. 4, FIG. 4 is a sectional view showing a recording state of the magnetic recording body of the present invention in a first stage, and FIG. 5 is a first sectional view of the magnetic recording body of the present invention. FIG. 7 is a sectional view showing a fixing state of recording at a stage, FIG. 6 is a sectional view showing a recording state at a second stage of the magnetic recording body of the present invention, and FIG. 7 is a sectional view showing a second stage of the magnetic recording body of the present invention. FIG. 8 is a sectional view showing a fixed state of recording, and FIG. 8 is a sectional view showing a recording state of the magnetic recording medium of the present invention in a third stage.

FIG. 1 shows the structure of the magnetic recording medium 1 of the present invention, in which a magnetic recording layer coated with a coating material in which a support 11 and microcapsules 14 containing flaky magnetic particles are dispersed in a binder 15. 12 and the protective layer 13 are sequentially stacked. Here, the magnetic recording layer 12 includes two or more kinds of microcapsules containing a dispersion medium having a different melting point for each color of the coloring agent, for example, 14-A, 14-B, 14-
It is composed of three types of microcapsules such as C, and a large number of these microcapsules are randomly dispersed and arranged in the magnetic recording layer 12. It should be noted that, here, for the sake of explanation, although three types of microcapsules are arranged in order,
Actually, the microcapsules that are fine particles are randomly arranged.

FIG. 2 is a sectional view showing an embodiment of the microcapsules 14 used in the magnetic recording layer 12 in the present invention. The microcapsule 14 has a core mainly composed of a suspension in which flaky magnetic particles 22 and a colorant 23 composed of a pigment or a dye are dispersed in a dispersion medium (organic compound such as wax) 24 that is in a solid state at room temperature. The substance 21 is encapsulated by a shell substance 25 made of a polymer or the like.

The flaky magnetic particles 22 are made of, for example, stainless steel such as iron, nickel, iron / nickel, iron / nickel / chromium, fine particles of cobalt, cobalt / aluminum, samarium / cobalt alloy, etc. by an atomizer or a hammer mill. Flakes can be used. In particular, in order to enhance the affinity of the magnetic particles with an organic solvent or the like, it is preferable to carry out a higher ester treatment, a silane coupling treatment, a titanate coupling treatment or the like. The size of the flake-shaped magnetic particles 22 in the present invention is 5 μm to 30 μm and has a thickness of 0. 0 in consideration of easiness of rotation in a microcapsule due to application of magnetism, image contrast of the magnetic recording layer 12, and the like. 1 μm to 3
It is preferably between μm.

The colorant 23 comprises a pigment or a dye, and is used as a pigment alone, a mixture of several pigments, a mixture of a pigment and a polymer, a dye alone, a mixture of several dyes, and the like. For example, in the case of a pigment, fine particles such as an inorganic pigment such as titanium dioxide, zinc sulfide, lead titanate, zirconium oxide, lead white, cadmium red, or cadmium yellow, or an organic pigment such as a phthalocyanine pigment (for example, the size is 1n
m-1 μm), and in the case of dyes, various known dyes such as azo dyes, quinoline dyes and phthalocyanine dyes can be used. When a mixture of a pigment or dye and a polymer is used as the colorant 23, the pigment or dye and the polymer are kneaded and then pulverized. Alternatively, the colorant 23 may be produced by a method of polymerizing a pigment or dye with a monomer such as emulsion polymerization, suspension polymerization, or dispersion polymerization. In this case, the polymer is preferably crosslinkable.

The dispersion medium 24 is at room temperature (about 10-35).
It should be solid (in the range of ° C) (in a solid state) and be in a fluid state when heated to a temperature higher than room temperature (in the range of approximately 40 to 100 ° C), such as an organic compound. Naturally known or synthetic waxes such as paraffin wax and carnauba wax, naturally occurring or synthetic resins, carboxylic acid esters and the like which are generally known and satisfy the above conditions can be used alone or in combination. For example, recording can be performed on the magnetic recording medium of the present invention by using paraffin wax having a melting point of 69 ° C., 55 ° C. or 43 ° C. In the present invention, the melting point of the dispersion medium 24 is made different according to the color of the colorant to prepare the microcapsules, and the microcapsules having different colorants are separately prepared and finally mixed. Thus, the microcapsules of each color are randomly mixed.

The core substance 21 containing the above-mentioned flaky magnetic particles 22, colorant 23, dispersion medium 24 and the like as main components is covered with a shell substance 25 such as a polymer to be microencapsulated.
Examples of the resin used as the shell substance 25 include commonly used resins such as acrylic resin, methacrylic resin, polystyrene, polyester resin, polyurethane resin, polyurea resin, polyamide resin, epoxy resin and natural resin. , These alone or 2
It is also possible to use a mixture of two or more species.

Microcapsules 1 having the above shell material
The production method of 4 is a phase separation method in which a concentrated phase of the polymer is separated around the core substance dispersed in the polymer solution, and a liquid for curing the polymer around the core substance in the polymer solution with a curing test agent for the polymer or the like. Medium-cure coating method, in-situ polymerization method in which the surface of the core material is covered with a polymer by supplying a monomer or a polymerization catalyst from either one of the emulsion in which the core material is dispersed, or the external phase, and the emulsion in which the core material is dispersed. A microencapsulation technique such as an interfacial polymerization method in which a monomer is supplied from both the internal phase and the external phase is suitable, but the method is not limited to these methods.

In particular, the flake-like magnetic particles 22 as the core substance 21 and the colorant 23 are uniformly dispersed in the dispersion medium 24, and are produced by the in-situ polymerization method in which the monomer is supplied from the outer phase of the suspension, or the phase separation method. As a result, it is possible to manufacture the microcapsules 14 having a uniform particle size and in which the flaky magnetic particles 22 can be easily moved. The polymerizable monomer used here is preferably acrylic acid ester, methacrylic acid ester, styrene and its derivatives, isocyanate, various amines, compounds having an epoxy group, and the like.

Next, in the magnetic recording body 1 of the present invention, as shown in FIG. 1, the microcapsules 14 having the above-mentioned structure are coated on a support 11 together with a binder 15 to form the magnetic recording layer 1.
2 is formed, and the protective layer 13 is further laminated to produce the layer.

The support 11 is a synthetic resin such as polyvinyl chloride, polyester, polycarbonate, polymethyl methacrylate, polystyrene, polyethylene terephthalate, natural resin, paper, synthetic paper, metal, ceramics, etc., alone or in combination. Can be used. In addition, its shape can be selected according to the application such as a card shape or a sheet shape, a film shape, and further considering the physical properties required according to the application, for example, strength, rigidity, hiding power, light opacity, etc. It can be appropriately selected.

As the binder 15 in which the microcapsules 14 are dispersed, a water-based binder, a solvent-based binder, an emulsion-based binder or the like is appropriately used.
Further, as the protective layer 13, an epoxy resin, tetrafluoroethylene, or the like, or a synthetic resin such as polyvinyl chloride, polyester, polycarbonate, polymethyl methacrylate, polystyrene, or polyethylene terephthalate,
Natural resin or the like can be used. The protective layer 13 needs to hold the microcapsules 14 formed on the support 11 and have a light-transmitting property such that the flaky magnetic particles 22 in the microcapsules 14 can be seen from the outside. Any material can be used as long as it satisfies necessary conditions such as strength.

The protective layer 13 may be colored in a range that does not affect the display / reading of the lower magnetic recording layer, or a colored layer (not shown) having light transmittance may be provided. For coloring the protective layer, mix a pigment or dye,
When a colored layer (not shown) is provided, a pigment or dye dispersed or dissolved in a binder or the like is applied and formed between the magnetic recording layer 12 and the protective layer 13.

The magnetic recording layer 12 and the protective layer 13 can be formed by a known printing method such as offset printing, gravure printing, silk screen printing, roll coating, knife edge coating, or the like. System, a transfer system using a transfer sheet having a transfer layer containing the microcapsules 14 described above, and a plurality of types of microcapsules 14 (for example, 14-A, 14-B, and
14-C) is mixed with an ink jet method in which an ink mixed with a base material is sprayed onto a base material, and a method of filling a solution containing the microcapsules 14 described above between the support 11 and the protective layer 13 is used. It is possible to appropriately select from the above methods according to the use and quantity of the information recording medium to be manufactured.

Next, a method of forming a display image on the magnetic recording medium of the present invention will be described. FIG. 1 shows a magnetic recording medium of the present invention in which a microcapsule 14 containing a suspension in which a flaky magnetic particle 22 and a colorant 23 shown in FIG. It is explanatory drawing showing the sectional view which expanded a part of 1. Initially, the flake-shaped magnetic particles 22 and the coloring agent 23 are fixed in the dispersion medium 24 in the microcapsule 14 in a uniformly dispersed state. This microcapsule 1
In addition to the flaky magnetic particles 22, 4 is a dispersion medium having different melting points (for example, paraffin wax (melting point 69 ° C.), paraffin wax (melting point 55 ° C.) depending on the color of the colorant 23, for example, three colors (yellow, red, blue). ), Microcapsules 14-A, 14- containing paraffin wax (melting point: 43 ° C.)
B and 14-C, which are randomly distributed.

FIG. 3 generally shows a state in which an image is not recorded, that is, a state in which the image is erased or unrecorded, and the microcapsules 14 are perpendicular to the magnetic recording layer 12.
It is explanatory drawing which shows the state formed by orienting the flake-shaped magnetic particle 22 inside. In this case, the microcapsule 14-
When the magnetic recording layer 12 is heated by the thermal / magnetic recording head 30 at a temperature at which A, 14-B, and 14-C are all melted, that is, a temperature slightly higher than the melting point of the highest dispersion medium,
The dispersion medium 24 in all the microcapsules becomes in a molten state, and the flaky magnetic particles 22 can be oriented or moved (rotated). Then, by applying magnetism, the orientation state becomes the same as the direction of magnetism application. Therefore, in the figure, the magnetic recording layer 12 is uniformly heated and the magnetic field applied in the horizontal direction causes the flaky magnetic particles 22 in the microcapsules 14 to be oriented vertically to the magnetic recording layer 12. As a result, incident light is hardly reflected on the surface of the magnetic recording body,
The color is scattered or absorbed to form a dark color tone, or incident light is transmitted through the magnetic recording layer and reflected by the surface of the support to display the color of the support. The support 11 is a dark color here, for example, black.

FIG. 4 is a cross-sectional view showing the first-stage recording state of the magnetic recording medium 1 of the present invention, which is slightly higher than the melting point of the highest dispersion medium for the magnetic recording layer 12 of the magnetic recording body 1. The magnetic recording layer 12 is partially heated according to the recording image of the first stage by the thermal / magnetic recording head at a temperature, and the dispersion medium 24 in the heated microcapsules 14-A, 14-B, 14-C is generated. While being in a molten state, the flake-shaped magnetic particles 22 are movable (rotatable), and when magnetism is applied, the orientation state becomes the same as the direction of magnetism application. Therefore, in the figure, the dispersion medium 24 is heated to a molten state, and the vertically oriented flake-shaped magnetic particles 22 in the microcapsules 14 of the magnetic recording layer 12 are generated by the magnetic field applied in the horizontal direction. 12 horizontally oriented. As a result, the incident light is reflected by the flaky magnetic particles 2
The color of the colorant 23 which is mostly reflected by 2 and is encapsulated in the microcapsules 14 appears.

FIG. 5 is a cross-sectional view showing the fixing state of the recording of the first stage of the magnetic recording medium of the present invention. In the recording state shown in FIG. 4, heat and magnetism are slightly higher than the highest melting point of the dispersion medium. Since the recording head is heated and magnetized and the flaky magnetic particles 22 of all the microcapsules 14 in the corresponding portion are oriented, the microcapsules 14 having a color corresponding to the recorded image in the first stage (for example, 14-A)
In order to bring only the flaky magnetic particles 22 into the oriented state, the fixing operation is performed. This is a microcapsule 14-
The magnetic recording layer 12 is heated at a temperature at which B and 14-C are melted, that is, below the melting point of the highest dispersion medium and slightly above the melting point of the next (second) highest dispersion medium. When heated by, the dispersion medium 24 in the microcapsules 14-B and 14-C excluding the microcapsules 14-A enclosing the dispersion medium having the highest melting point is in a molten state, and the flake-shaped magnetic particles 22 are oriented or moved ( Rotation) is possible. In the figure, the magnetic field applied uniformly to the magnetic recording layer 12 in the vertical direction causes the flaky magnetic particles 22 in the microcapsules 14 to be oriented perpendicular to the magnetic recording layer 12. As a result, only the flaky magnetic particles 22 in the recorded microcapsules 14-A are horizontally oriented, and the other flaky magnetic particles 22 in the microcapsules 14 are vertically oriented. A bright image of the color of the colorant 23 contained in the microcapsules 14-A is formed in 11 dark color tones, whereby the first visible display information can be recorded.

Further, FIG. 6 is a sectional view showing the recording state of the magnetic recording medium 1 of the present invention in the second stage, in which the microcapsules 14-B,
14-C is melted, that is, lower than the melting point of the highest dispersion medium and slightly higher than the melting temperature of the next (second) highest dispersion medium, according to the second-stage recorded image by the thermal / magnetic recording head. The magnetic recording layer 12 is partially heated, and the dispersion medium 2 in the heated microcapsules 14-B and 14-C.
4 is in a molten state and the flaky magnetic particles 22
Can be moved (rotated), and by applying magnetism,
The orientation state is the same as the magnetic application direction. Therefore, in the figure, the dispersion medium 24 is heated to a molten state, and the vertically oriented flake-shaped magnetic particles 22 in the microcapsules 14 of the magnetic recording layer 12 are generated by the magnetic field applied in the horizontal direction. 12 horizontally oriented. As a result, most of the incident light is reflected by the flaky magnetic particles 22, and the color of the coloring agent 23 contained in the microcapsules 14 appears.

FIG. 7 is a sectional view showing the fixing state of the recording of the second stage of the magnetic recording medium of the present invention. In the recording state shown in FIG. 6, the heat / magnetism is slightly higher than the highest melting point of the dispersion medium. Since the recording head is heated and magnetized and the flaky magnetic particles 22 of all the microcapsules 14 in the corresponding portion are oriented, the microcapsules 14 having a color corresponding to the recorded image in the first stage (for example, 14-A)
In order to bring only the flaky magnetic particles 22 into the oriented state, the fixing operation is performed. This is a microcapsule 14-C
Melting temperature, that is, lower than the melting point of other dispersion medium,
When the magnetic recording layer 12 is heated by the thermal / magnetic recording head 30 at a temperature slightly higher than the melting point of the lowest (third) dispersion medium, the inside of the microcapsules 14-C excluding the microcapsules 14-A and 14-B. The dispersion medium 24 becomes in a molten state, and the flaky magnetic particles 22 can be oriented or moved (rotated). In the figure, the microcapsules 1 are applied to the magnetic recording layer 12 by a magnetic field uniformly applied in the vertical direction.
The magnetic flakes 22 in 4 are oriented perpendicular to the magnetic recording layer 12. As a result, only the flake-shaped magnetic particles 22 in the recorded microcapsules 14-B are oriented horizontally, and the flake-shaped magnetic particles 22 in the other microcapsules 14 are oriented vertically. A bright image of the color of the colorant 23 contained in the microcapsules 14-B is formed in the dark color tone of 11, whereby the second visible display information can be recorded.

Further, FIG. 8 shows the third embodiment of the magnetic recording medium of the present invention.
FIG. 6 is a cross-sectional view showing a recording state at a stage, which is lower than the melting temperature of the microcapsules 14-C of the magnetic recording layer 12 of the magnetic recording body 1, that is, lower than the melting point of another dispersion medium and the lowest (the third ) At a temperature slightly higher than the melting point of the dispersion medium, the magnetic recording layer 12 is partially heated according to the recording image of the third stage by the thermal / magnetic recording head, and the dispersion medium 24 in the heated microcapsules 14-C is heated. Becomes a molten state, the flake-shaped magnetic particles 22 become movable (rotatable), and when magnetism is applied, the orientation state becomes the same as the direction of magnetism application. Therefore, in the figure, the dispersion medium 24 is heated to a molten state, and the vertically oriented flake-shaped magnetic particles 22 in the microcapsules 14 of the magnetic recording layer 12 are generated by the magnetic field applied in the horizontal direction. 12 horizontally oriented. The incident light is
The color of the colorant 23 which is mostly reflected by the flake-shaped magnetic particles 22 and is encapsulated in the microcapsules 14-C appears, and the microcapsules 14 appear in the dark tone of the support 11.
A bright image is formed by the color of the colorant 23 included in −C, and thus the third visible display information can be recorded.
In the third stage, there is no microcapsule in which the flake-shaped magnetic particles 22 are oriented other than the microcapsule 14-C, so that the fixing operation is unnecessary.

As described above, recording and fixing are repeatedly performed on the magnetic recording layer 12 composed of a plurality of types of microcapsules using dispersion media having different melting points and different coloring agents, so that micro recording is performed according to a recorded image. A plurality of visible display information for each color by the capsule can be recorded, and the number of colors used can be two or more. That is, the present invention enables display of multicolored color images.

The thermal / magnetic head 30 used for recording the magnetic recording medium 1 of the present invention is, for example, a method in which heat is applied only to a recording portion after a uniform magnetic field is formed over the entire recording area. There is a method of recording by applying heat uniformly and then forming a magnetic field only at the recording location. (1) Specifically, an optical head capable of heat conversion such as laser light and a uniform magnetic field are applied. Possible magnetic field forming means, (2) thermal head and uniform magnetic field applying means, and (3) magnetic head and uniform heat applying means. It may be configured to scan in a line shape, and can be appropriately selected according to the application. In particular, the heating means for applying heat may have a heating ability to melt the above-mentioned dispersion medium 24 such as wax or organic compound.

Since this image formation is simple due to heat with low energy to the extent that magnetism and the viscosity of the dispersion medium are lowered, recording is easy, and the resolution can be improved by controlling the particle size of the microcapsules. High image formation is possible. In addition, the image formed by the thermal / magnetic head is in a fixed state at the same time when the dispersion medium returns to room temperature, so that the recording stability is good, and since the image formation only by magnetism cannot be performed except in the melted state, No fogging caused by touching the magnet. The magnetic recording medium according to the present invention has the mobility (rotation) of the contained flake-like colored magnetic particles during recording, that is, both good recording reactivity and stable recorded image. Further, by using the dispersion medium 24 having a different melting point for each color of the colorant 23 of the microcapsule 14, image recording can be performed in the order of higher melting point, and clear multicolored recording such as recording according to the number of colors can be realized. Alternatively, it is possible to record a color image with each color of yellow, magenta, and cyan as in printing.

Furthermore, since the microcapsules can be made into a coating solution by mixing with a binder, they can be applied to various supports and can be processed into various shapes, and the manufacturing process is simple. Therefore, the range of applications can be expanded. Further, a magnetic recording material capable of displaying various colors can be obtained by appropriately selecting a colorant, a dispersion medium and the like.

The image recorded on the magnetic recording medium of the present invention is various visible information such as characters, numbers, marks, patterns, pictures, photographs, etc., and is supported by transmitting incident light through the magnetic recording layer and reflecting on the surface of the support. Visible information is displayed by the contrast between the color of the body and the display of a bright image by the colorant on the horizontally oriented flaky magnetic particles, whereby a clear color image is obtained. Note that the entire surface of the magnetic recording layer can be erased entirely or partially by heating the entire surface of the magnetic recording layer with a heat / magnetic recording head at a temperature slightly higher than the melting point of the highest dispersion medium and applying magnetism in the vertical direction. , Reversible recording and erasing can be performed.

[0049]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to specific embodiments. <Example> 60 parts by weight of flake-shaped nickel powder subjected to silane coupling treatment and 1 part by weight of a yellow pigment (Bentzin Yellow YT564) were heated to 80 ° C and melted into 80 parts by weight of paraffin wax having a melting point of 80 ° C. It was uniformly dispersed, and this dispersion was dispersed in 200 parts by weight of a 10% aqueous gelatin solution heated to 80 ° C. using a homogenizer at a rotation speed of 2000 rpm for about 5 minutes so that the average particle diameter was 75 μm. 200 parts by weight of an aqueous solution of 10% arabic gum was mixed with the obtained dispersion liquid, 1000 parts by weight of water was further added, and the mixture was kept at 40 ° C. and a 10% aqueous solution of acetic acid was added dropwise.
H was adjusted to 4. Then, the liquid temperature is cooled to 7 ° C.,
10% by weight formalin aqueous solution was added, and 10% aqueous sodium hydroxide solution was added dropwise to adjust the pH to 9.
Microcapsule A having a gum arabic wall was prepared.

Next, a yellow pigment (Bentzin Yellow YT56
4) instead of magenta pigment (Watching Red RT
761D) and the paraffin wax having a melting point of 80 ° C. was used in place of the paraffin wax having a melting point of 80 ° C.

Furthermore, a yellow pigment (Bentzin Yellow YT5
64), instead of cyan pigment (phthalocyanine blue)
And, instead of paraffin wax having a melting point of 80 ° C., a melting point of 4
Microcapsules C were prepared in the same manner except that paraffin wax at 0 ° C. was used.

Next, a coating liquid in which the obtained microcapsules A, B, and C were evenly dispersed in a polyvinyl alcohol aqueous solution was applied onto a black polyethylene terephthalate (PET) film to form a magnetic recording layer. The protective layer was formed to obtain the magnetic recording material of the present invention.

The entire surface of this magnetic recording medium is heated to 85 ° C.,
A magnetic field perpendicular to the magnetic recording layer was applied from the outside, and the flaky magnetic particles in all microcapsules were oriented perpendicular to the surface of the magnetic recording layer, leaving the magnetic recording layer in an unrecorded state. . Next, the entire surface of the magnetic recording layer or a part thereof is heated to 85 ° C. according to the first visible display information to be recorded, and a magnetic field is applied in the horizontal direction of the magnetic recording layer so that the flake-like magnetic particles are applied to the magnetic recording layer. The flakes in the microcapsules B and C are oriented horizontally and heated to 65 ° C., which is lower than the melting point of the dispersion medium of the microcapsules A, and a magnetic field perpendicular to the magnetic recording layer is applied from the outside. The first visible display information was recorded by orienting the magnetic particles in a direction perpendicular to the surface of the magnetic recording layer.

Next, the entire surface of the magnetic recording layer or the second recording
Of the microcapsule B by partially heating the magnetic recording layer to 65 ° C. according to the visible display information and applying a magnetic field in the horizontal direction of the magnetic recording layer to orient the flaky magnetic particles so as to be horizontal to the magnetic recording layer. It is heated to 45 ° C., which is lower than the melting point of the dispersion medium, and a magnetic field perpendicular to the magnetic recording layer is applied from the outside to make the flaky magnetic particles in the microcapsules C perpendicular to the surface of the magnetic recording layer. Then, the second visible display information was recorded. Further, the entire surface of the magnetic recording layer or partly heated to 45 ° C. according to the third visible display information to be recorded, and a magnetic field is applied in the horizontal direction of the magnetic recording layer so that the flake-shaped magnetic particles are horizontal to the magnetic recording layer. Then, the third visible display information was recorded. By the above operation, a full-color bright and clear image can be formed in a dark tone.

Although not shown, the above magnetic recording layer is formed on a transparent polyethylene terephthalate (PET) film, and an acrylic resin in which a black pigment (for example, carbon black , graphite, acetylene black, naphthol blue black, etc.) is kneaded. An image can be recorded or erased from the side of the support (PET) by forming a layer made of, and the magnetic recording part is formed by fitting the support (PET) side to the concave side of another medium. It can also be used as a display means.

[0056]

According to the magnetic recording medium and the recording method of the magnetic recording medium of the present invention, flaky magnetic particles, a coloring agent, and a dispersion of these particles, which shows a solid state at room temperature, and which varies depending on the color of the coloring agent. A magnetic recording layer in which two or more kinds of microcapsules containing a dispersion medium having a melting point are dispersed in a binder, and the flaky magnetic particles of these microcapsules are oriented horizontally with respect to the magnetic recording layer. Or, the image is recorded by the contrast of the reflected light by orienting vertically, and color display is possible by containing the coloring agent contained in the microcapsules, and the use of microcapsules of different colors Thus, multicolor display and further full color display can be performed. In particular, by using a dispersion medium having a different melting point for each color of the colorant, it is possible to record an image for each color, so that the colors do not mix and a clear color display is possible. Further, it is a magnetic recording medium in which bright and dark are clearly defined so that a portion to which magnetism is applied and a portion to which no magnetism is applied are clearly defined, and which has high resolution, is clear, and is excellent in image stability and which can be repeatedly recorded and erased.

Further, since the magnetic recording medium of the present invention can easily form an image by heating at a low temperature and applying magnetism, the energy consumption is low, and by using the microcapsules for the recording layer, microcapsules can be obtained. The resolution can be increased by controlling the particle size of the. Moreover, since the magnetic particles are dispersed in the dispersion medium that is in a solid state at room temperature in the microcapsule and are fixed except during recording and erasing, even if external magnetism is applied after recording the information, the inside of the microcapsule remains Stable recording can be obtained without causing movement of the magnetic particles. Since the movement (orientation) of the magnetic particles can be substantially limited only to the portion to which heating / magnetism is applied, the stability of the image is excellent by using a dispersion medium having a high resolution and showing a solid state at room temperature.

Further, since the step of applying the coating liquid containing the microcapsules can be applied, the manufacturing steps of the magnetic recording body can be simplified.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of a magnetic recording body of the present invention.

FIG. 2 is a cross-sectional view showing an example of microcapsules used in the magnetic recording layer of the magnetic recording medium of the present invention.

FIG. 3 is a cross-sectional view showing an unrecorded state of the magnetic recording body of the present invention.

FIG. 4 is a cross-sectional view showing a first-stage recording state of the magnetic recording body of the present invention.

FIG. 5 is a cross-sectional view showing a fixed state of recording in the first stage of the magnetic recording body of the present invention.

FIG. 6 is a sectional view showing a second-stage recording state of the magnetic recording body of the present invention.

FIG. 7 is a cross-sectional view showing a fixed state of recording in the second stage of the magnetic recording body of the present invention.

FIG. 8 is a cross-sectional view showing a recording state at a third stage of the magnetic recording body of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnetic recording medium 11 Support 12 Magnetic recording layer 13 Protective layer 14 Microcapsule 14-A Microcapsule A 14-B Microcapsule B 14-C Microcapsule C 15 Binder 21 Core substance 22 Flake-like magnetic particle 23 Colorant 24 Dispersion Medium 25 Shell material 30 Thermal / magnetic head

Claims (7)

[Claims] 1. A support comprising a non-magnetic material, at least flakes of magnetic particles, a colorant, and a dispersion medium which is in a solid state at room temperature and is dispersed therein.
Further, a magnetic recording layer is formed by disposing two or more kinds of microcapsules expressing different hues using dispersion media having different melting points for each color of the colorant in a binder to form a magnetic recording layer. body. 2. The melting point of the dispersion medium is 35 ° C. or higher and 100 ° C.
The magnetic recording medium according to claim 1, which is an organic compound within the following range. 3. The magnetic recording medium according to claim 1, wherein the colorant comprises a dye or a pigment. 4. The average particle size of the microcapsules is 10 μm.
The magnetic recording medium according to claim 1, wherein the magnetic recording medium is between m and 1000 μm. 5. The flaky magnetic particles have an average major axis of 5 μm.
2. The magnetic recording medium according to claim 1, wherein the magnetic recording medium has an average thickness of 0.1 μm to 30 μm and an average thickness of 0.1 μm to 5 μm. 6. The magnetic recording medium according to claim 1, wherein a protective layer is formed on the magnetic recording layer. 7. A support comprising a non-magnetic material, at least flakes of magnetic particles, a colorant, and a dispersion medium which is in a solid state at room temperature and which is dispersed therein.
In addition, a magnetic recording medium is obtained in which a dispersion medium having a different melting point for each color of the colorant is used and two or more kinds of microcapsules representing different hues are dispersed in a binder to form a magnetic recording layer. A recording step in which the dispersion medium is partially heated and melted in order of the melting point of the magnetic recording layer in accordance with the recorded image and the flaky magnetic particles are oriented by magnetically applying in the horizontal or vertical direction, 2. A recording method for a magnetic recording medium, characterized in that an image is recorded in correspondence with the color of the microcapsule by heating the entire surface of the recording medium and a fixing process by applying a magnetic force in the vertical or horizontal direction.