JPH0990887A - Magnetic recording medium and method for erasing recording of magnetic recording medium as well as recording erasing device for magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic recording medium which displays darkness and brightness varying in the parts impressed with magnetism and the parts not impressed with the magnetism, has high resolution, is bright, has the excellent stability of images and is capable of making reversible display and color display and a method for recording the medium as well as a recording erasing device for the magnetic recording medium. SOLUTION: This magnetic recording medium 1 is constituted by dispersedly arranging microcapsules 14 contg. flaky magnetic particles 22, coloring agents, laser beam absorptive materials having absorption wavelengths varying with each color of these coloring agents and dispersion media which disperse these materials and exhibit a solid phase state at ordinary temp. or the microcapsules 14' contg. the laser beam absorptive materials having the absorption wavelengths varying with each color of the coloring agents in the wall parts of the microcapsules into binders 15, thereby forming a magnetic recording layer 12. The images corresponding to the respective colors of the microcapsules 14, 14' are recorded on this magnetic recording layer 12 by melting the dispersion media by the heat generated by the absorption of the laser beam in the laser beam absorptive material and orienting the flaky magnetic particles 22 by the impression of the magnetism in a horizontal or perpendicular direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium for displaying a pattern such as an image by applying a magnetism with heating, a recording method for the magnetic recording medium, and a recording / erasing apparatus for the magnetic recording medium. The present invention relates to a reversible magnetic recording medium capable of recording and erasing and color display, and having excellent resolution and image stability, a recording method for the magnetic recording medium, and a recording and erasing apparatus for the magnetic recording medium.

[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 material 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. An object of the present invention is to provide a recording method and a recording / erasing apparatus for a magnetic recording body.

[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. Characterized in that a magnetic recording layer is formed by dispersing and arranging microcapsules containing a colorant, a laser light absorbing substance, and a dispersion medium in which these are dispersed and showing a solid state at room temperature in a binder. And a magnetic recording medium.

According to a second aspect of the present invention, at least a flake-shaped magnetic particle, a colorant, and a dispersion medium having a solid state at room temperature, which is formed by dispersing these, are contained on a support made of a non-magnetic material, and A magnetic recording medium is characterized in that the magnetic recording layer is formed by disposing microcapsules containing a laser light absorbing substance on the wall portion in a binder.

According to a third aspect of the present invention, in the magnetic recording medium according to the first or second aspect, the number of the microcapsules corresponding to the color of the colorant is one or more, and the laser light absorbing substance for each color of the colorant. Are different in absorption wavelength.

According to a fourth aspect of the present invention, in the magnetic recording medium according to the first or second aspect, the dispersion medium has a melting point of 35 ° C. or higher.
It is characterized by being an organic compound in the range of 00 ° C or lower.

According to a fifth aspect of the invention, in the magnetic recording medium according to the first or second aspect, the colorant is a dye or a pigment.

According to a sixth aspect of the present invention, in the magnetic recording medium according to the first or second aspect, the average particle size of the microcapsules is between 10 μm and 1000 μm.

According to a seventh aspect of the present invention, in the magnetic recording medium according to the first or second aspect, the flaky magnetic particles have an average major axis of 5 μm to 30 μm and an average thickness of 0.1 μm.
It is characterized by being between m and 5 μm.

The invention of claim 8 is the magnetic recording medium according to claim 1 or 2, characterized in that a protective layer is formed on the magnetic recording layer.

According to the invention of claim 9, visible information is obtained by the orientation of the flaky magnetic particles from the melting of the dispersion medium in the microcapsules by applying a magnetic field to the magnetic recording layer of the magnetic recording material according to claim 1 or 2 and heating. In a method of recording and erasing a magnetic recording medium for performing recording and erasing, the recording of information by applying a vertical or horizontal magnetic field to the magnetic recording layer and partial irradiation of light corresponding to the absorption wavelength of the laser light absorbing material, and magnetic recording A method for erasing information on a magnetic recording medium, which comprises erasing information by applying a horizontal or vertical magnetic field to the layer and irradiating the entire surface with light corresponding to the absorption wavelength of the laser light absorbing material or heating the entire surface of a heating means.

A tenth aspect of the present invention provides visible information by orientation of the flake-shaped magnetic particles from melting of the dispersion medium in the microcapsules by applying a magnetic field to the magnetic recording layer of the magnetic recording body according to the first or second aspect and heating. In a recording / erasing apparatus for a magnetic recording body for performing recording / erasing, at least a vertical or horizontal magnetic field applying means, a laser beam irradiating means, or a heating means is provided. is there.

[0026]

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 the magnetic recording body of the present invention, and FIG. 2 is a sectional view showing an embodiment of microcapsules used in the magnetic recording layer of the magnetic recording body of the first invention of the present invention. FIG. 3 is a sectional view showing an embodiment of a microcapsule used in the magnetic recording layer of the magnetic recording medium of the second invention of the present invention, and FIG. 4 is an unrecorded state of the magnetic recording medium of the present invention. FIG. 5 is a sectional view showing a state, FIG. 5 is a sectional view showing a recording state of a first stage of the magnetic recording body of the present invention, and FIG. 6 is a sectional view showing a recording state of a second stage of the magnetic recording body of the present invention. FIG. 7 is a sectional view showing the recording state of the magnetic recording medium of the present invention in the third stage.

FIG. 1 shows the structure of a magnetic recording medium 1 of the present invention, in which a support 11 and microcapsules 14 or 14 'containing flaky magnetic particles or the like are dispersed in a binder 15 to apply a coating material. The magnetic recording layer 12 and the protective layer 13 are sequentially stacked. Here, the magnetic recording layer 12 includes a microcapsule 14 containing a laser light absorbing substance having a different absorption wavelength of the laser light for each color of the colorant, or a laser light absorption having a different absorption wavelength of the laser light for each color of the colorant. Two or more kinds of microcapsules 14 'containing a substance in the wall portion, for example, three kinds of microcapsules such as 14-A, 14-B, and 14-C are used. 12 are dispersed and arranged. In addition,
Here, for the sake of explanation, three types of microcapsules are arranged in order, but in reality, microcapsules that are fine particles are randomly arranged.

FIG. 2 is a sectional view showing an embodiment of the microcapsule 14 used in the magnetic recording layer 12 of the magnetic recording body 1 in the first invention. Micro capsule 14
Is a flaky magnetic particle 22, a colorant 23 composed of a pigment or a dye, a laser light absorbing substance 24, and a dispersion medium (eg, an organic compound such as wax) 2 that shows a solid state at room temperature.
This is a configuration in which a core substance 21 mainly composed of suspension dispersed in 5 is encapsulated with a shell substance 26 made of a polymer or the like.

FIG. 3 shows the magnetic recording layer 1 of the magnetic recording body 1.
FIG. 7 is a cross-sectional view showing one example of the microcapsule 14 ′ according to the second invention used in No. 2. The microcapsules 14 'are mainly composed of flaky magnetic particles 22, a coloring agent 23 made of a pigment or a dye, and a suspension dispersed in a dispersion medium (organic compound such as wax) 25 showing a solid state at room temperature. The core substance 21 'is encapsulated by a shell substance 26 made of a polymer or the like containing a laser light absorbing substance 24.

Next, the common structure of the microcapsules 14 and 14 'will be described. The flake-shaped magnetic particles 22 are, for example, stainless steel such as iron, nickel, iron / nickel, iron / nickel / chromium, fine particles of cobalt, cobalt / aluminum, samarium / cobalt alloy, or the like, which are flaky with an atomizer or a hammer mill. What was done 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. Flake-shaped magnetic particles 22 in the present invention
Considering the ease of rotation in the microcapsule due to the application of magnetism, the image contrast of the magnetic recording layer 12, etc., the particle size is 5 μm to 30 μm and the thickness is 0.1 μm.
It is preferably between m and 3 μm.

The colorant 23 is composed of a pigment or a dye, and is used as a pigment alone, a mixture of several kinds of pigments, a mixture of a pigment and a polymer, a single dye or a mixture of several kinds of dyes. 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 laser light absorbing substance 24 may be any substance having a light absorbing ability in the near infrared region and capable of photothermal conversion, such as polymethine dye (cyanine type), phthalocyanine type, dithiol metal complex salt type, naphthalocyanine. System, naphthoquinone, anthraquinone system, triphenylmethane system (derivative), indophenol system, aluminum diimmonium system, etc. are used, for example, absorption wavelength 700-80
At 0 nm, IR-750 (trade name) anthraquinone type; manufactured by Nippon Kayaku Co., Ltd., SIR114 (trade name) anthraquinone type; manufactured by Mitsui Toatsu Chemicals, CY-20 (trade name) cyanine type; manufactured by Nippon Kayaku Co., Ltd., At an absorption wavelength of 800 to 900 nm, KIR-103 (trade name) phthalocyanine type; manufactured by Mitsui Toatsu Chemicals, Inc., PA1005 (trade name) dithiol metal complex salt type; manufactured by Mitsui Toatsu Chemicals, NK-2911 (trade name)
Cyanine type; manufactured by Japan Photosensitive Dye Research Institute, absorption wavelength 900-
At 1100 nm, IRF-1000 (trade name); Fuji Photo Film Co., Ltd., IRG-003 (trade name) Diimmonium-based; Nippon Kayaku Co., CIR-1081 (trade name)
Cyanine-based; manufactured by Nippon Carlit Co., Ltd. and the like can be mentioned. In the present invention, a laser light absorbing substance is appropriately selected according to the color of the colorant, and a laser light absorbing substance having a different absorption wavelength (for example, 24-
A, 24-B, 24-C) are respectively included, or microcapsules containing in the wall portion are produced, and microcapsules having different coloring agents and laser light absorbing substances are produced separately, and finally, By mixing
The microcapsules of each color are randomly mixed.

The dispersion medium 25 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.

The core substance 21 containing the above-mentioned flaky magnetic particles 22, colorant 23, laser light absorbing substance 24, dispersion medium 25 and the like as main components is covered with a shell substance 26 such as a polymer,
Alternatively, the core substance 2 mainly composed of the flaky magnetic particles 22, the coloring agent 23, the laser light absorbing substance 24, the dispersion medium 25, etc.
1'is covered with a shell substance 26 such as a polymer containing a laser light absorbing substance 24 to be microencapsulated. In addition,
The laser light absorbing substance 24 may be contained in a microcapsule as a core substance and further contained in the wall portion of the microcapsule. Examples of the resin used as the shell material 26 include commonly used resins such as acrylic resin, methacrylic resin, polystyrene, polyester resin, polyurethane resin, polyurea resin, polyamide resin, epoxy resin, and natural resin. It is also possible to use these alone or in combination of two or more.

Microcapsules 1 having the above-mentioned shell material
4, 14 ', the phase separation method of separating the concentrated phase of the polymer around the core substance dispersed in the polymer solution, the polymer around the core substance in the polymer solution by a test agent for curing the polymer, etc. In-liquid curing coating method to cure, 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 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 of the emulsion is preferable, but the method is not limited to these methods.

In particular, the core materials 21, 21 'are uniformly dispersed in the dispersion medium 25, and the in-situ polymerization method in which the monomer is supplied from the outer phase of the suspension, or the phase separation method is used to produce the particles having uniform particle sizes. In addition, the microcapsules 14 and 1 in which the flaky magnetic particles 22 can easily move
4'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 preferable.

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 the support 11 together with the 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 composite of polyvinyl chloride, polyester, polycarbonate, polymethylmethacrylate, polystyrene, polyethylene terephthalate, and other synthetic resins, 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 and 14 'are dispersed, an aqueous binder, a solvent binder, an emulsion binder or the like is appropriately used. Further, as the protective layer 13, an epoxy resin,
Tetrafluoroethylene or the like, or synthetic resin such as polyvinyl chloride, polyester, polycarbonate, polymethylmethacrylate, polystyrene, polyethylene terephthalate or the like, natural resin or the like can be used. This protective layer 13
Holds the microcapsules 14 formed on the support body 11, and from the outside,
It is necessary that the flaky magnetic particles 22 in 4 ′ have a light-transmitting property so that the flaky magnetic particles 22 can be seen, and any one satisfying the necessary conditions such as strength can be used.

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 method, gravure printing method, silk screen printing method, roll coating method, knife edge method or the like. Method, a transfer method using a transfer sheet having a transfer layer containing the microcapsules 14 described above, and a plurality of types of microcapsules 14, 14 '(for example, 14-A, 1
4-B, 14-C) is mixed with an ink jet method of spraying an ink on a base material, a method of filling a solution containing the microcapsules 14 and 14 'described above between the support 11 and the protective layer 13, and the like. It can be produced by the forming method, and can be appropriately selected from the above-mentioned methods depending on the use and quantity of the information recording medium to be produced.

Next, a method of forming a display image on the magnetic recording medium of the present invention will be described. FIG. 1 shows microcapsules 14 containing a suspension in which the flaky magnetic particles 22, the coloring agent 23, and the laser light absorbing substance 24 shown in FIG. 2 are dispersed in an organic solvent as a dispersion medium 25, and / or FIG.
The flaky magnetic particles 22 and the colorant 23 shown in FIG.
5, a part of the magnetic recording medium 1 of the present invention in which a suspension dispersed in an organic solvent is contained and a microcapsule 14 ′ containing a laser light absorbing substance 24 on a wall portion is applied on a support 11 is enlarged. It is explanatory drawing showing the cross-sectional view. At the beginning of production, inside the microcapsules 14, 14 ',
The flake-shaped magnetic particles 22 and the colorant 23 are fixed in a dispersion medium 24 in a uniformly dispersed state. The microcapsules 14 and 14 ′ contain a coloring agent 23 in addition to the flaky magnetic particles 22 in the dispersion medium 25, and further, the coloring agent 2
Microcapsules 14-A, 14-in which microcapsules contain laser light absorbing substances 24 having different absorption wavelengths according to three colors, for example, three colors (yellow, red, blue), or in the wall portion of the microcapsules. B and 14-C, which are randomly distributed. In this description, for convenience, three types of microcapsules are arranged in order, but in reality, the microcapsules, which are the above-described fine particles, are randomly arranged.

FIG. 4 generally shows a state in which an image is not recorded, that is, a state in which the image is erased or unrecorded. The microcapsule 1 is perpendicular to the magnetic recording layer 12.
It is explanatory drawing which shows the state formed by orienting the flaky magnetic particle 22 in 4,14 '. In this case, the temperature at which the dispersion medium 25 of the microcapsules 14-A, 14-B, and 14-C is all melted, that is, laser light irradiation means 31 for irradiating all the laser light absorbing substances 24 with wavelength light that causes laser light absorption. Alternatively, the recording / erasing head 30 is composed of a heating means 32 such as a thermal head at the melting temperature of the dispersion medium 25 and a magnetic applying means 33 capable of applying magnetism vertically and horizontally to the magnetic recording medium 1. When 12 is heated, the dispersion medium 2 in all the microcapsules 14, 14 '
As a result, 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 heated uniformly, and by the magnetic field applied in the vertical direction, the microcapsules 14, 1
The flake-shaped magnetic particles 22 in 4'are oriented perpendicular to the magnetic recording layer 12. As a result, the incident light is hardly reflected on the surface of the magnetic recording medium and is scattered / absorbed to have a dark color tone, or the incident light is transmitted through the magnetic recording layer and the color of the support is displayed by the reflection on the surface of the support. To be done. Support 11
Is a dark color here, for example, black.

FIG. 5 is a cross-sectional view showing the first-stage recording state of the magnetic recording medium 1 of the present invention. The recording / erasing head 30 is used to identify the magnetic recording layer 12 of the magnetic recording medium 1. Laser light absorbing material 2 of microcapsules 14-A
4 is irradiated with laser light having a wavelength that can be absorbed and magnetic force is applied in the vertical direction, and heat is generated due to the laser light absorption of the laser light absorbing material 24, so that the magnetic recording layer 12 is partially recorded according to the recorded image in the first stage. While the dispersion medium 25 of the microcapsules 14-A becomes in a molten state, the magnetic field in the horizontal direction allows the flaky magnetic particles 22 to move (rotate). Is the same as Therefore, in the figure, the dispersion medium 25 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 magnetically applied by the horizontal direction. 12 horizontally oriented. Therefore, most of the incident light is reflected by the flake-shaped magnetic particles 22, and the color of the colorant 23 included in the microcapsules 14 and 14 'appears.

As a result, only the flake-shaped magnetic particles 22 in the recorded microcapsules 14-A are horizontally oriented, and the flake-shaped magnetic particles 22 in the other microcapsules 14 and 14 'are vertically oriented. Because
Microcapsules 14-A in the dark tone of the support 11
A bright image is formed by the color of the colorant 23 included in the first visible display information.

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. The recording recording / erasing head 30 is used to identify the magnetic recording layer 12 of the magnetic recording medium 1. Of the microcapsules 14-B of the first embodiment is irradiated with a laser beam having a wavelength that can be absorbed by the laser light absorbing substance 24 and is applied with magnetic force in the vertical direction, so that heat generated by the laser light absorbing substance 24 absorbs the laser light, and thus the first-stage recording is performed. The dispersion medium 25 of the microcapsules 14-A of the magnetic recording layer 12 is partially melted in accordance with the image, and the flake-shaped magnetic particles 22 are movable (rotatable) by applying a magnetic field in the horizontal direction. By doing so, the orientation state becomes the same as the magnetic application direction. Therefore, in the figure, the dispersion medium 25 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 magnetically applied by the horizontal direction. 12 horizontally oriented. Therefore, most of the incident light is reflected by the flaky magnetic particles 22,
Colorant 23 contained in the microcapsules 14, 14 '
Appears.

As a result, only the flaky magnetic particles 22 in the recorded microcapsules 14-B are oriented horizontally, and the flaky magnetic particles 22 in the other microcapsules 14 are oriented vertically. , Support 1
In the dark color tone of 1, a bright image is formed by the color of the colorant 23 included in the microcapsules 14-B, whereby the second visible display information can be recorded.

Further, FIG. 7 shows a third magnetic recording medium of the present invention.
FIG. 3 is a cross-sectional view showing a recording state at a stage, which is a wavelength that can be absorbed by the laser light absorbing substance 24 of a specific microcapsule 14-C using the recording / erasing head 30 for the magnetic recording layer 12 of the magnetic recording body 1. Of the laser light and the application of the magnetic force in the vertical direction, the heat generated by the absorption of the laser light of the laser light absorbing material 24 causes the magnetic recording layer 12 to partially cover the magnetic recording layer 12 in accordance with the recording image of the third stage by the recording / erasing head. Heat
While the dispersion medium 24 in the heated microcapsules 14-C is in a molten state, the flake-shaped magnetic particles 22 are movable (rotatable), and by applying magnetism, the orientation state thereof 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. Therefore, most of the incident light is reflected by the flake-shaped magnetic particles 22, and the color of the colorant 23 included in the microcapsules 14 and 14 'appears.

As a result, only the flaky magnetic particles 22 in the recorded microcapsules 14-C are horizontally oriented, and the other unrecorded microcapsules 14, 1
Since the flake-shaped magnetic particles 22 in 4'are vertically oriented, a bright image is formed in the dark tone of the support 11 by the color of the colorant 23 contained in the microcapsules 14-C. Third visible display information can be recorded.

The above recording is sequentially performed on the magnetic recording layer 12 in which a plurality of types of microcapsules using the laser light absorbing substances 24 having different absorption wavelengths set for each color of the colorant are arranged. By doing so, it is possible to record a plurality of visible display information for each color by the microcapsules according to the recorded image, and it is possible to use two or more colors. That is, the present invention enables display of multicolored color images.

The recording / erasing head 30 used for recording on the magnetic recording medium 1 of the present invention is, for example, an entire erasing method in which a uniform magnetic field is formed as a recording method and then a laser beam is irradiated only to a recording portion. There is a method of erasing by irradiating a laser beam on the entire surface or a necessary portion after forming a uniform magnetic field, or by heating the entire surface after forming a uniform magnetic field on the entire surface. It is also possible to adopt a method in which heat is applied uniformly to the entire surface and then a magnetic field is formed only in the recording portion for recording. For example, in the former method, (1) specifically, laser light irradiation means capable of heat conversion of laser light and the like, magnetic field forming means capable of applying a uniform magnetic field, and (2) heating means and uniform magnetic field. There is a magnetic field forming means capable of applying the magnetic field, and the latter has (3) a magnetic head and a heating means capable of applying uniform heat, and may be configured to scan the heat and the magnetic field linearly. Can be appropriately selected. In particular, the heating means for applying the heat of (2) and (3) only needs to have a heating capacity for melting the above-mentioned dispersion medium 26 such as wax or an organic compound.

This image formation is simple by heat of low energy enough to reduce the magnetism and the viscosity of the dispersion medium.
Recording and erasing are easy because the heat source is heat generated by the laser light absorbing substance, and high-resolution image formation is possible by controlling the particle size of the microcapsules. The image formed by the recording / erasing 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 the image formation cannot be performed only by magnetism except in the melted state. It does not cause fogging by touching. 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. In addition, the colorant 2 is applied to the microcapsules 14 and 14 '.
By using the laser light absorbing substances 24 having different absorption wavelengths set for each of the three colors, it is possible to record an image for each absorption group length, and it is possible to make clear multi-color recording such as recording according to the number of colors. Alternatively, it is also possible to record a color image in each color of yellow (yellow), red (magenta), and blue (cyan) as in printing.

Further, 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 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 letters, numbers, marks, patterns, pictures, photographs, etc., and the incident light is transmitted through the magnetic recording layer and supported by 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.

[0055]

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, 1 part by weight of a yellow pigment (Bentzin Yellow YT564), a near infrared absorbing agent CY-20 (trade name) as a laser light absorbing material, made in Japan Yakusha's absorption wavelength of 780 nm was uniformly dispersed in 80 parts by weight of paraffin wax having a melting point of 80 ° C., which was heated to 80 ° C. and melted, and this dispersion was added to 200 parts by weight of an aqueous 10% gelatin solution heated to 80 ° C. Rotation speed 2000 rp using homogenizer
It was dispersed for about 5 minutes so that the average particle diameter was 75 μm. 200% 10% aqueous solution of gum arabic was added to the obtained dispersion.
1 part by weight of water and 1000 parts by weight of water were added,
The temperature was kept at 0 ° C. and a 10% aqueous acetic acid solution was added dropwise to adjust the pH to 4. Thereafter, the liquid temperature was cooled to 7 ° C., 10 parts by weight of a 30% formalin aqueous solution was added, and a 10% sodium hydroxide aqueous solution was added dropwise to adjust the pH to 9 to prepare microcapsules A having a gelatin-arabic gum wall.

Next, a yellow pigment (Bentzin Yellow YT56
4) and near-infrared absorber CY-20 (trade name) manufactured by Nippon Kayaku Co., Ltd., instead of absorption wavelength 780 nm, magenta pigment (Watching Red RT761D) and near-infrared absorber NK-
2911 (trade name) Made by Japan Photosensitive Dye Research Institute, absorption wavelength 8
Microcapsules B were produced in the same manner except that 30 nm was used.

Furthermore, a yellow pigment (Bentzin Yellow YT5
64), instead of cyan pigment (phthalocyanine blue)
And the near-infrared absorber CIR-1081 (trade name) manufactured by Nippon Carlit Co., Ltd .. Microcapsules C were produced in the same manner except that the absorption wavelength was 900 to 1000 nm.

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 portion of 780 nm in accordance with the first visible display information to be recorded.
Of the first microcapsule A by irradiating the laser beam of 10
The visual display information was recorded.

Next, the entire surface of the magnetic recording layer or the second recording
Laser light of 830 nm is partially irradiated according to the visible display information, and a magnetic field is applied in the horizontal direction of the magnetic recording layer to orient the flaky magnetic particles so that they are horizontal to the magnetic recording layer. The second visible display information of B was recorded. Furthermore, the entire surface of the magnetic recording layer or 950 is partially formed according to the third visible display information to be recorded.
The third visible display information was recorded by irradiating a laser beam of nm 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. 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.

[0062]

According to the magnetic recording material and the recording method of the magnetic recording material of the present invention, the flaky magnetic particles, the coloring agent, the laser light absorbing substance having different absorption wavelength for each color of the coloring agent, and these are dispersed. Microcapsules or flake-shaped magnetic particles containing a dispersion medium that exhibits a solid state at room temperature,
A microcapsule containing a colorant and a dispersion medium which is in a solid state at room temperature and in which the colorant is dispersed, and the wall portion of which contains a laser light absorbing substance having an absorption wavelength different for each color of the colorant. Is dispersed in a binder to have a magnetic recording layer, and the flake-shaped magnetic particles of these microcapsules are oriented horizontally or vertically with respect to the magnetic recording layer to record an image by contrast of reflected light. In this case, color display can be performed by including a colorant contained in the microcapsules, and multicolor display and further full-color display can be performed by using different color microcapsules.

In particular, by setting a laser light absorbing substance having a different absorption wavelength for each color of the colorant, an image can be recorded for each color, so that the colors are not mixed and a clear color display is possible. Is. 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, the magnetic recording medium of the present invention can easily form an image by heating at a low temperature and applying a magnetism, so that the energy consumption is low, and by using the microcapsules in 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.

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 first invention.

FIG. 3 is a cross-sectional view showing an example of microcapsules used in the magnetic recording layer of the magnetic recording medium of the second invention.

FIG. 4 is a sectional view showing an unrecorded state of the magnetic recording body of the present invention.

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

[Explanation of symbols]

 1 Magnetic Recording Material 11 Support 12 Magnetic Recording Layer 13 Protective Layer 14, 14 ′ Microcapsule 14-A Microcapsule A 14-B Microcapsule B 14-C Microcapsule C 15 Binder 21, 21 ′ Core Material 22 Flake Magnetic Particles 23 Colorant 24 Laser light absorbing substance 25 Dispersion medium 26 Shell substance 30 Recording / erasing head 31 Laser light irradiating means 32 Heating means 33 Magnetic applying means

Claims (10)

[Claims] 1. A support comprising a non-magnetic material, and at least flakes of magnetic particles, a coloring agent, a laser light absorbing substance, and a dispersion medium which is a solid state at room temperature and is dispersed therein. A magnetic recording medium comprising microcapsules dispersed in a binder to form a magnetic recording layer. 2. A support made of a non-magnetic material contains at least flake-shaped magnetic particles, a colorant, and a dispersion medium which is in a solid phase state at room temperature and is dispersed in the dispersion medium. A magnetic recording medium comprising microcapsules containing a light absorbing substance dispersed in a binder to form a magnetic recording layer. 3. The microcapsule corresponding to the color of the colorant is one or more kinds, and the absorption wavelength of the laser light absorbing substance is different for each color of the colorant. The magnetic recording material according to 1. 4. The melting point of the dispersion medium is 35 ° C. or higher and 100 ° C.
The magnetic recording medium according to claim 1 or 2, which is an organic compound within the following range. 5. The magnetic recording medium according to claim 1, wherein the colorant comprises a dye or a pigment. 6. The average particle size of the microcapsules is 10 μm.
The magnetic recording medium according to claim 1 or 2, wherein the magnetic recording medium has a thickness of between m and 1000 µm. 7. The average major axis of the flaky magnetic particles is 5 μm.
3. The magnetic recording medium according to claim 1, wherein the magnetic recording medium has a thickness of m to 30 μm and an average thickness of 0.1 μm to 5 μm. 8. The magnetic recording medium according to claim 1, wherein a protective layer is formed on the magnetic recording layer. 9. The recording and erasing of visible information by the orientation of the flake-shaped magnetic particles from the melting of the dispersion medium in the microcapsules by applying and heating a magnetic field to the magnetic recording layer of the magnetic recording medium according to claim 1 or 2. In the method of recording and erasing a magnetic recording medium, recording of information by applying a vertical or horizontal magnetic field to the magnetic recording layer and partially irradiating light corresponding to the absorption wavelength of the laser light absorbing material, and recording the information horizontally on the magnetic recording layer. Alternatively, a method of erasing information on a magnetic recording medium, characterized in that a perpendicular magnetic field is applied and information is erased by irradiating the entire surface with light corresponding to the absorption wavelength of the laser light absorbing material or heating the entire surface of a heating means. 10. Recording and erasing of visible information from the melting of the dispersion medium in the microcapsules by applying and heating a magnetic field to the magnetic recording layer of the magnetic recording medium according to claim 1 or 2 by the orientation of the flaky magnetic particles. A recording / erasing apparatus for a magnetic recording medium, comprising at least a vertical or horizontal magnetic field applying means, a laser beam irradiating means, or a heating means.