JP2000043301A - Information recording method and information erasing method of magnetic recording body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide recording or erasing method of a magnetic recording body, showing different light and shade in a magnetized part and an unmagnetized part, high and sharp in resolution, superior in the stability of a picture and capable of indicating reversibly. SOLUTION: An information is recorded by orientating flaky magnetic powder through heating and impressing a magnetism in parallel or orthogonal direction with respect to a magnetic recording layer 12 on a magnetic recording body 1 having the magnetic recording layer 12 containing micro capsules 15 encapsulating the flaky magnetic powder 22 and a dispersion medium in solid phase state at a normal temperature on a substrate while the information can be read by the contrast of reflecting light with the surrounding. On the other hand, the information can be erased by orientating the flaky magnetic powder 22 to either one of parallel or vertical direction in a whole or a predetermined are of the magnetic recording layer 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording method and an information erasing method for a reversibly displayable magnetic recording medium which records or erases information by applying magnetism together with heating, and which has excellent resolution and image stability. .

[0002]

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

[0003] However, in such a magnetic recording medium, when the suspension is sealed between two substrates and a character and a pattern are drawn from one of the substrates with a magnetic pen to actuate magnetism, the magnetic particles of the suspension are attracted. As a result, the same characters and patterns can be obtained, but the specific gravity of the magnetic particles is much larger than that of the dispersing medium, and the attracted magnetic particles have a drawback that the characters and patterns cannot be retained for a long time because they settle with time. .

[0004] Further, since all the magnetic particles that have been magnetized by the magnetic pen are attracted to the magnetic pen, the magnetic particles that are present away from the magnetic pen are also attracted, so that only unclear characters or patterns can be obtained. It also had disadvantages. In order to prevent sedimentation of the 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 is approximated to that of the dispersion medium, the magnetic force acting on the magnetic particles can be reduced. Since the force becomes extremely small, it becomes difficult to be sucked by the magnetic pen, and a defect occurs in that a high-density, clear character or pattern cannot be obtained.

Further, if the apparent specific gravity of the magnetic particles is approximated to that of the dispersion medium, it is difficult for the magnetic particles to be attracted to the opposite side of the substrate even when erasing a character or a pattern. Repeating it turned black overall, which was not practical.

As a form for solving these drawbacks, for example, Japanese Patent Publication No. 57-27463 and Japanese Patent Application Laid-Open No. 62-53
As described in JP-A-359, as a dispersion medium,
By using a liquid with a yield value equal to or higher than a certain value or a thickener, clear and high-contrast characters and images without blur can be displayed, the display can be maintained stably for a long time, and complete erasure can be performed. 2. Description of the Related Art A magnetic recording medium that can be neatly cleaned is known.

However, this magnetic recording medium is formed so that honeycomb-shaped cells each having a side and a depth of about 2 mm are provided on the entire surface of the transparent plastic sheet, and the magnetic particles and the white pigment are contained in the cells. Was injected into a dispersion medium, and the suspension was sealed with a transparent sheet, and had the following disadvantages. That is, since the image is formed by moving the magnetic particles from the back surface to the front surface in the honeycomb-shaped cells, it is impossible to make the resolution of the image smaller than that of the honeycomb-shaped cells. In addition, it is difficult to form the honeycomb-shaped cells, to enlarge or extremely reduce the size of the honeycomb-shaped cells, and to inject a suspension into the honeycomb-shaped cells.

As another mode, for example, Japanese Patent Laid-Open No. 2-14
No. 6082 and JP-A-4-233581, unlike a magnetic recording medium in which magnetic particles and a pigment are sealed in a honeycomb cell as described above, magnetic particles are encapsulated in microcapsules. A magnetic recording medium obtained by applying this on a support is known. According to this method, the resolution can be increased by controlling the particle diameter of the microcapsules, and the manufacturing process is easy. In addition, various films and the like can be selected for 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 side of the magnetic recording medium, and the light-reflecting non-magnetic particles remain on the surface of the magnetic recording medium. The color of the non-magnetic particles becomes the erased state. Next, by applying and recording magnetism from the surface of the magnetic recording medium with a permanent magnet, light-absorbing magnetic particles are attracted to the surface by the magnetism, and desired characters and images are formed. Therefore, in such an image formation, it takes a long time to attract the magnetic particles, resulting in a magnetic recording medium having low sensitivity.

Further, as other forms utilizing microcapsules, for example, JP-A-1-145637, JP-A-63-153197, JP-B-4-7518, JP-A-6-79986, and JP-A-6-79986. 6-9206
No. 8 or EyneS. Truble
P. S. & E. As described in U.S. Pat. No. 7 213 (1963), a magnetic recording medium in which light-absorbing magnetic particles and light-reflective non-magnetic particles are encapsulated in microcapsules is known.

In the image forming method of this embodiment, first, at the time of manufacturing a magnetic recording medium, the incident light is totally reflected by making the magnetic particles in the coated capsules parallel to the plane of the magnetic recording medium in advance to make the capsule appear bright. Next, by performing magnetic recording, the magnetic particles rotate and scatter the incident light,
As a result, contrast is generated and a black image is formed.

However, the magnetic recording medium obtained in this manner has a very low resolution compared to other recording methods using heat or light because the magnetic force is applied over a wide range. Furthermore, since the magnetic recording medium can be easily printed and erased by the magnetic force, the image can be easily read or erased by touching the magnet so that the unprinted portion is fogged or the image is erased. It has the disadvantage of poor stability.

[0013]

As described above, a conventional magnetic recording medium using a magnetic material as a display means cannot display a high-resolution image, and cannot display an image displayed by the influence of external magnetism. Since the image was erased partially or in a state where it could not be read, or the image was fogged in the unprinted portion, stable recording could not be performed. In addition, there has been no magnetic recording medium having both the mobility of the magnetic powder contained therein, that is, the good recording reactivity and the stability of the recorded image. Therefore, in the present invention, the magnetically applied portion and the non-applied portion show different light and shade, and have high resolution,
It is another object of the present invention to provide a method for recording or erasing a magnetic recording medium capable of reversible display, which has excellent image stability.

[0014]

Means for Solving the Problems The present invention has been made to achieve the above-mentioned object, and the invention according to claim 1 provides at least a flake-like magnetic powder on a support made of a non-magnetic material. And, at a place where the information of the magnetic recording layer formed by dispersing and disposing a microcapsule containing a dispersion medium exhibiting a solid phase state at room temperature and dispersed therein in a binder is visually displayed, heating and perpendicular or After applying a magnetic field in the horizontal direction and orienting the flake-like magnetic powder in the vertical or horizontal direction by heating and melting the dispersion medium, the temperature is returned to normal temperature, and information is recorded by fixing the orientation direction of the flake-like magnetic powder in the dispersion medium. And a method for recording information on a magnetic recording medium.

According to a second aspect of the present invention, a microcapsule containing at least a flake-like magnetic powder and a dispersion medium which is dispersed in a non-magnetic material and has a solid phase at room temperature is provided on a support made of a non-magnetic material. By heating and applying a magnetic field in the vertical or horizontal direction to the entire surface or a specific region of the magnetic recording layer dispersedly arranged therein, the flake-shaped magnetic powder is to be a magnetic recording layer showing a uniform orientation. This is a method for erasing information on a magnetic recording medium, which is a feature.

According to the method for recording or erasing a magnetic recording medium of the present invention, a magnetic recording layer including microcapsules containing a flake-like magnetic powder and a dispersion medium which exhibits a solid phase state at room temperature is provided between supports. The reflection of the incident light on the magnetic recording layer by the orientation of the flake-shaped magnetic powder in the parallel direction to the magnetic recording medium, and the scattering / absorption or incidence of the incident light by the orientation of the flake-shaped magnetic powder in the vertical direction. Visible information is displayed by contrast of light transmission through the magnetic recording layer and reflection from the surface of the support. By applying perpendicular or parallel magnetism to the magnetic recording layer together with heating, information can be recorded, and by uniformly orienting the flake-like magnetic powder on the entire surface of the magnetic recording layer or a predetermined region. Information recording can be erased.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing one embodiment of a magnetic recording medium used in the present invention, FIG. 2 is a cross-sectional view showing one embodiment of a microcapsule in a magnetic recording layer used in the present invention, and FIG. FIG. 4 is an explanatory view showing a state at the time of manufacturing a magnetic recording medium used in the present invention. FIG. 4 shows a state (erasing) in which flake-shaped magnetic powder is oriented parallel to a magnetic recording layer of the magnetic recording medium according to the present invention. FIG. 5 is an explanatory diagram showing a state (recording) in which the flake-shaped magnetic powder is oriented in a direction perpendicular to the magnetic recording layer of the magnetic recording medium according to the present invention.

FIG. 1 shows the structure of a magnetic recording medium 1 according to the present invention. A magnetic recording layer to which a coating material obtained by dispersing a support 11, a microcapsule 15 containing flake-like magnetic powder and the like in a binder 16 is applied. 12, a protective layer 14 is sequentially laminated.

FIG. 2 is a sectional view showing an embodiment of the microcapsule 15 used for the magnetic recording layer 12 in the present invention. The microcapsules 15 are made of flake-like magnetic powder 2
Reference numeral 2 denotes a configuration in which a core material 21 mainly composed of a suspension dispersed in a dispersion medium (for example, an organic compound such as wax) 23 showing a solid phase state at normal temperature is encapsulated with a shell material 24 made of a polymer or the like.

The flake-like magnetic powder 22 is obtained by, for example, using iron, nickel, iron / nickel, iron / nickel / chromium, etc., stainless steel, cobalt, cobalt / aluminum, samarium / cobalt alloy, etc., with an atomizer or hammer mill. Flakes can be used. In particular, in order to enhance the affinity of the magnetic powder with an organic solvent, etc., higher ester treatment, silane coupling treatment,
It is preferable to perform titanate coupling treatment or the like.
The size of the flake-shaped magnetic powder 22 in the present invention has a particle size of 5 μm to 30 μm and a thickness of 0. Preferably it is between 1 μm and 3 μm. Further, a colored layer may be provided on the surface of the flake-shaped magnetic powder 22.

As the dispersion medium 23, room temperature (about 10 to 35
C.) and a solid (showing a solid phase state) and a fluid state when heated to a temperature higher than room temperature (about 40 to 80 ° C.). Commonly known materials satisfying the above conditions, such as natural or synthetic waxes such as paraffin wax and carnauba wax, natural or synthetic resins, and carboxylic acid esters can be used alone or in combination as appropriate. In addition, you may color in the range which does not obstruct light transmittance.

The above-mentioned flaky magnetic powder 22, dispersion medium 2
A core material 21 mainly composed of 3 or the like is covered with a shell material 24 such as a polymer, and is microencapsulated. This shell material 24
The resin used as, for example, commonly used resins, for example, acrylic resin, methacrylic resin, polystyrene, polyester resin, polyurethane resin, polyurea resin, polyamide resin, epoxy resin, natural resin and the like, and these may be used alone. , Or a mixture of two or more kinds.

Microcapsule 1 having the above-mentioned shell material
Examples of the production method 5 include a phase separation method in which a polymer rich phase is separated around a core substance dispersed in a polymer solution, and a liquid in which a polymer is cured around a core substance in a polymer solution with a polymer curing test agent or the like. Medium-curing coating method, in-situ polymerization method in which a monomer or a polymerization catalyst is supplied from one of the emulsions in which the core substance is dispersed, or the external phase is supplied, and the surface of the core substance is covered with a polymer, and the emulsion in which the core substance is dispersed. Microencapsulation techniques, such as interfacial polymerization, in which monomers are supplied from both the internal and external phases are preferred, but not limited to these methods.

In particular, the particles are produced by an in-situ polymerization method in which the flake-like magnetic powder 22 as the core substance 21 is uniformly dispersed in a dispersion medium 24 and monomers are supplied from an external phase of the suspension, or by a phase separation method. Microcapsules 15 having a uniform diameter and easy movement of the flake-shaped magnetic powder 22 can be manufactured. The polymerizable monomer used here is acrylic acid ester, methacrylic acid ester, styrene and its derivatives, isocyanate,
Various amines, compounds having an epoxy group, and the like are suitable.

The magnetic recording medium 1 used in the present invention comprises a support 1
The magnetic recording layer 12 is formed by applying the microcapsules 15 having the above-described configuration together with the binder 16 on the first layer 1, and the protective layer 14 is further laminated thereon.

The support 11 is a composite of 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, the shape can be selected according to the application such as a card shape or a sheet shape, a film shape, and further, in consideration of physical properties required according to the application, for example, strength, rigidity, concealing property, light opacity, etc., from the above materials, It can be selected as appropriate.

As the binder 16 for dispersing the microcapsules 15, an aqueous binder, a solvent binder, an emulsion binder and the like are appropriately used.
Further, as the protective layer 14, an epoxy resin, tetrafluoroethylene, or the like, or a synthetic resin such as polyvinyl chloride, polyester, polycarbonate, polymethyl methacrylate, polystyrene, or polyethylene terephthalate;
Natural resins and the like can be used. This protective layer 14 needs to hold the microcapsules 15 formed on the support 11 and have a light transmitting property so that the flake-like magnetic powder 22 in the microcapsules 15 can be seen from the outside. Any material that satisfies necessary conditions such as strength can be used.

The protective layer 14 may be colored in a range that does not affect the reading and reading of the lower magnetic recording layer, or may be provided with a colored layer (not shown) having a light transmitting property. For the coloring of the protective layer, a pigment or a dye is mixed,
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 on the magnetic recording layer 12. As the pigment or dye, a pigment alone, a mixture of several kinds of pigments, a mixture of a pigment and a polymer, a dye alone, a mixture of several kinds of dyes, and the like can be used. For example, pigments commonly known as titanium dioxide, zinc sulfide, lead titanate, zirconium oxide, lead white,
Fine particles of inorganic pigments such as cadmium red and cadmium yellow, organic pigments such as phthalocyanine pigments, and various known pigments and dyes such as azo dyes, quinoline dyes, and phthalocyanine dyes are used as the dyes. When a pigment or a mixture of a pigment and a polymer is used, the above-described pigment or the pigment and the polymer are kneaded and then pulverized, or the pigment or the pigment-dispersed monomer is subjected to emulsion polymerization, suspension polymerization, or dispersion polymerization. A method such as polymerization is used. In this case, the polymer is preferably crosslinkable. As the binder for dispersing and dissolving these pigments or dyes, an aqueous binder, a solvent binder, an emulsion binder and the like are used.

The magnetic recording layer 12, the protective layer 14, and the colored layer (not shown) may be formed by a known printing method such as an offset printing method, a gravure printing method, a silk screen printing method, or a roll coating method. A coating method such as a knife edge method, a transfer method using a transfer sheet having a transfer layer mixed with the microcapsules 15 described above, an ink jet method in which the ink mixed with the microcapsules 15 is sprayed onto a substrate, a support 11 and protection It can be formed by a forming method such as a method of filling a solution in which the above-described microcapsules 15 are mixed with the layer 14, and can be appropriately selected from the above methods according to the use and the number of information recording media to be formed. Can be.

Next, a method for recording information on a magnetic recording medium of the present invention, that is, a method for forming a display image will be described. First, FIG. 3 is an enlarged view of a part of the magnetic recording medium 1 used in the present invention in which a microcapsule 15 containing a suspension in which a flake-shaped magnetic powder 22 is dispersed in an organic solvent as a dispersion medium 23 is applied on a support 11. It is an explanatory view showing a cross-sectional view. When the magnetic recording medium 1 is initially manufactured, the flake-like magnetic powder 22 is fixed in the dispersion medium 23 in the microcapsule 15 in a state of being uniformly dispersed.

FIG. 4 is an explanatory diagram showing a state (erasing) in which the flake-like magnetic powder 22 in the microcapsule 15 is oriented in parallel to the magnetic recording layer 12. When the magnetic recording layer 12 is heated by the thermal / magnetic recording head 30, the dispersion medium 23 in the microcapsule is in a molten state, and the flake-shaped magnetic powder 22 can be oriented or moved (rotated).
Then, the orientation state becomes the same as the magnetic application direction. Therefore, in the drawing, the magnetic recording layer 12 is uniformly heated and magnetism applied in the parallel direction causes the flake-like magnetic powder 22 in the microcapsule 15 to be oriented parallel to the magnetic recording layer 12. As a result, the surface of the magnetic recording medium has a uniform color tone in which most of the incident light is reflected by the flake-like magnetic powder 22.

FIG. 5 shows a state (recording) in which the flake-like magnetic powder is oriented in a direction perpendicular to the magnetic recording layer of the magnetic recording medium according to the present invention, and the information of the magnetic recording layer 12 of the magnetic recording medium 1 is shown. Is heated by a thermal / magnetic recording head to bring the dispersion medium 23 in the microcapsule into a molten state, and the flake-like magnetic powder 22
Can be moved (rotated), and the orientation state becomes the same as the direction of the applied magnetic field due to the applied magnetic field. Therefore, in the figure, the flake-shaped magnetic powder 22 in the microcapsule 15 at the place where the information of the magnetic recording layer 12 is visually displayed is
2 is oriented vertically. As a result, the incident light is hardly reflected (or absorbed) by the flake-like magnetic powder 22. Therefore, the flake-like magnetic powder 22 oriented in the direction parallel to the magnetic recording layer 12 and the flake-like magnetic powder oriented in the perpendicular direction. A difference in reflection from the powder 22, that is, a contrast is obtained, and thereby, visible display information can be recorded. The thermal / magnetic head 30 is, for example, a method of performing recording by applying heat only to a recording portion at the same time as forming a uniform magnetic field as a whole, or applying a magnetic field only to the recording portion after applying heat uniformly to the whole or simultaneously. There is a method of forming and recording,
(1) Specifically, an optical head capable of thermally converting laser light or the like and a magnetic field forming means capable of applying a uniform magnetic field, (2) a thermal head and a magnetic field forming means capable of applying a uniform magnetic field ,
(3) There are a magnetic head and a heat applying means capable of uniformly applying heat, and a configuration in which heat and a magnetic field are scanned in a line may be used, which can be appropriately selected according to the application. In particular, the heating means for applying heat only needs to have a heating ability enough to melt the above-described dispersion medium 23 such as a wax or an organic compound.

The image formation as information recording on the magnetic recording medium 1 is simple due to magnetism and low-energy heat that reduces the viscosity of the dispersion medium. By controlling the diameter, it is possible to form an image with high resolution. In addition, since the image formed by the thermal / magnetic head is in a fixed state at the same time when the dispersion medium returns to normal temperature, its recording stability is good, and since it is not possible to form an image only with magnetism except in a molten state, No fogging is caused by touching the magnet. The magnetic recording medium according to the present invention is provided with both the mobility at the time of recording of the flake-like magnetic powder contained therein, that is, both the good recording reactivity and the stability of the recorded image. Further, information can be recorded by setting the orientation of the flake-shaped magnetic powder to the magnetic recording layer based on one of the parallel direction and the perpendicular direction and partially setting the other as the other direction. Based on the fact that the orientation state of the flake-shaped magnetic powder is in the vertical direction, the visible state information may be recorded by partially changing the orientation state in the parallel direction.

Furthermore, since the microcapsules can be made into a coating liquid 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 application can be expanded. In particular, when applied on paper, it can be used as information recording paper for household faxes and the like, and printing and erasing can be easily and reversibly performed by applying heat and magnetism, so that it can be used as recycled paper.

Hereinafter, specific examples of the present invention will be described.
This will be described in detail. <Example 1> 60 parts by weight of flake-shaped nickel powder subjected to silane coupling treatment was uniformly dispersed in 80 parts by weight of paraffin wax melted by heating to 60 ° C, and this dispersion was heated to 60 ° C. 10% gelatin aqueous solution 200
In a weight part, the number of rotations was 2000 using a homogenizer.
The particles were dispersed for about 5 minutes so that the average particle size became 75 μm at rpm. A 10% aqueous solution of gum arabic 20 was added to the resulting dispersion.
0 parts by weight, and further add 1000 parts by weight of water,
While maintaining the temperature at 40 ° C., a 10% aqueous acetic acid solution was added dropwise to adjust the pH to 4. Thereafter, the liquid temperature was cooled to 5 ° C., 10 parts by weight of a 30% aqueous formalin solution was added, and a 10% aqueous sodium hydroxide solution was added dropwise to adjust the pH to 9, thereby producing microcapsules having a gelatin-arabic gum wall.

Next, on a black polyethylene terephthalate (PET) film, a coating liquid in which the above microcapsules were dispersed in polyvinyl alcohol was applied to form a magnetic recording layer, and a protective layer made of an acrylic resin was sequentially formed. A magnetic recording medium to be used was obtained. The entire surface of the magnetic recording medium is heated, and a magnetic field that is parallel to the magnetic recording layer is applied from the outside to orient the flake-like magnetic powder in the microcapsules so as to be parallel to the magnetic recording layer. Reflected light from the support by partially heating according to the visible display information and applying a magnetic field in the perpendicular direction to the magnetic recording layer to orient the flake-shaped magnetic powder so as to be perpendicular to the magnetic recording layer A clear image was obtained from the contrast between the light and the reflected light of the flake-shaped magnetic powder.

Example 2 60 parts by weight of a flaky cobalt-aluminum alloy treated with oleic acid was
2 parts by weight of a yellow dye were dissolved and heated at 50 ° C. and uniformly dispersed in 80 parts by weight of a mixed solvent of paraffin wax and dibutyl phthalate, and this dispersion was heated to 50 ° C.
% Polyvinyl alcohol in an amount of 200 parts by weight using a homogenizer at a rotation speed of 2000 rpm and an average particle size of 750 μm.
m for about 5 minutes. To the resulting dispersion was added 100 parts by weight of a melamine-formalin prepolymer aqueous solution, and a 20% acetic acid aqueous solution was added dropwise to adjust the pH to 6. Thereafter, the temperature of the solution was raised to 65 ° C., and a polymerization reaction was carried out for 30 minutes to produce microcapsules having a melamine-formalin wall.

Next, a coating liquid in which the above microcapsules are dispersed in an acrylic emulsion resin is applied on black coated paper to form a magnetic recording layer, and a protective layer made of acrylic resin is sequentially formed on the magnetic recording layer. To obtain a magnetic recording medium. The entire surface of the magnetic recording medium is heated, and a magnetic field that is parallel to the magnetic recording layer is applied from the outside to orient the flake-like magnetic powder in the microcapsules so as to be parallel to the magnetic recording layer. Reflected light from the support by partially heating according to the visible display information and applying a magnetic field in the perpendicular direction to the magnetic recording layer to orient the flake-shaped magnetic powder so as to be perpendicular to the magnetic recording layer A clear image was obtained from the contrast between the light and the reflected light of the flake-shaped magnetic powder.

[0039]

The recording method and the erasing method of the magnetic recording medium according to the present invention comprise a magnetic recording layer including a flake-like magnetic powder and a microcapsule containing a dispersion medium in which the flake-like magnetic powder is dispersed and shows a solid state at room temperature. Then, by heating the dispersion medium in the microcapsule to a molten state and orienting the flake-shaped magnetic powder in parallel or perpendicular to the magnetic recording layer in accordance with the location where the information to be recorded is visually displayed, the reflected light is Image information can be recorded and displayed from the contrast. In addition, information can be erased by aligning the orientation of the flake-shaped magnetic powder in one of parallel and perpendicular to the magnetic recording layer.

That is, according to the present invention, with respect to the magnetic recording medium, the contrast is high and the resolution is high, so that the portion to which magnetism is applied is clearly different from the portion to which no magnetism is applied.
It is clear and has excellent image stability.

Further, since the magnetic recording medium used in 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 microcapsules for the recording layer, The resolution can be increased by controlling the particle size of the microcapsules. In addition, since the magnetic powder is dispersed in the dispersion medium that shows a solid phase state at room temperature in the microcapsule and is fixed except when recording or erasing, even if magnetism such as a magnet is applied from outside after information recording, the inside of the microcapsule can be maintained. No magnetic powder moves, and a stable recording can be obtained. Since the movement (orientation) of the magnetic powder can be almost limited only to the portion where heating and magnetism are applied, the use of a dispersion medium having a high resolution and showing a solid phase state at normal temperature provides excellent image stability.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a magnetic recording medium used in the present invention.

FIG. 2 is a sectional view showing one embodiment of a microcapsule in a magnetic recording layer used in the present invention.

FIG. 3 is an explanatory view showing a state when a magnetic recording medium used in the present invention is manufactured.

FIG. 4 is an explanatory diagram showing a state (erase) in which flake-shaped magnetic powder is oriented in parallel to a magnetic recording layer of a magnetic recording medium according to the present invention.

FIG. 5 is an explanatory diagram showing a state (recording) in which flake-shaped magnetic powder is oriented in a direction perpendicular to a magnetic recording layer of a magnetic recording medium according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnetic recording body 11 Support 12 Magnetic recording layer 14 Protective layer 15 Microcapsule 16 Binder 21 Core material 22 Flaky magnetic powder 23 Dispersion medium 24 Shell material 30 Thermal / magnetic head

Claims (2)

[Claims] 1. A microcapsule containing at least a flake-like magnetic powder and a dispersion medium in a solid state at room temperature, which is obtained by dispersing the flake-like magnetic powder, is dispersed and arranged in a binder on a support made of a nonmagnetic material. Heating and vertical or horizontal magnetism are applied to the entire surface of the magnetic recording layer or a portion where information is visually displayed, and the flake-shaped magnetic powder is vertically or horizontally oriented by heating and melting the dispersion medium. A method for recording information on a magnetic recording medium, comprising: returning the temperature to room temperature, and fixing the orientation direction of the flake-like magnetic powder in the dispersion medium. 2. A microcapsule enclosing at least a flake-like magnetic powder and a dispersion medium, which is in a solid state at room temperature and is dispersed therein, is dispersed and arranged in a binder on a support made of a nonmagnetic material. A magnetic recording layer in which the flake-like magnetic powder shows a uniform orientation by heating and applying a magnetic field in a vertical or horizontal direction to the entire surface or a specific region of the magnetic recording layer. How to erase body information.