JPH1186283A - Information recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain higher security by preventing the criminally reading of magnetic information even in use for a normal magnetic recording by a method wherein an magnetic image is provided on a substrate and a magnetically shielding layer is provided partially or wholly on the magnetic image to magnetically shield the magnetic image. SOLUTION: To form a magnetic image on an on-demand basis, an indicator 1 is provided with an elution removable magnetic layer 2 that has a resin exhibiting the nature of being water-soluble under the presence of a removing liquid as main component of resin components and then, a part thereof is removed by elution using the removing liquid to obtain the magnetic image. A resistance to the removing liquid is applied to a required part in the elution removable magnetic layer 2 to form a magnetic image by removal using the removing liquid. So, a resist layer 3 is provided on the elution removable magnetic layer 2 by heat transfer printing. A magnetically shielding layer 6 is provided on a part or the whole of an upper layer of the magnetic image to shield lines of magnetic force of the magnetic image and a normal magnetic recording part. Thus, the reading of magnetic signals is made impossible by the normal reading method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a highly secure information recording medium using magnetically recognizable image information (or a magnetic image) as fixed magnetic information. Since the magnetic information of the recording medium is hidden by the magnetic shielding layer, the information recording medium achieves a high level of security.

[0002]

2. Description of the Related Art Magnetic recording systems are used in a wide range of industrial fields today. The main advantages of this magnetic recording method are that information can be rewritten, reading and writing can be performed at high speed, and unlike optical information, the surface is resistant to contamination. Although the magnetic recording method is widely used as described above, it is not without its problems. For example, in a field where an information recording medium such as a magnetic card is used, illegal use thereof may be a problem. This can be said to be an example in which the advantage of the magnetic recording system that magnetic information can be rewritten has turned into a disadvantage. To compensate for the drawbacks of the rewritable magnetic recording method, punch holes are provided in a part of the card,
Attempts have been made to provide magnetic cards with non-rewritable information, but such punched holes can be filled relatively easily, and even if the holes are incorrectly filled. Since it is difficult to detect such information, it is hard to say that it is sufficiently effective against unauthorized use.

[0003] Banknotes and the like are printed with ink containing a magnetic material in part, and confidential information is magnetically recorded. In this case, the specific image information has magnetic information and is used on the assumption that the information is not rewritten. Such a method of using magnetic information as non-rewritable information is very useful for the purpose of providing information for identification on an information recording medium in view of the advantages of the magnetic recording method described above. Until now, such magnetic information has been mainly obtained by forming a magnetic image by printing.

[0004]

The printing method described in the above-mentioned prior art is excellent when a large number of image recording media having the same information are manufactured, but is different for each image recording medium. It is not suitable when information is provided. However, if an attempt is made to use non-rewritable magnetic information formed as an image for security,
Having different information for each image recording medium greatly improves security, and an information recording medium using individual magnetic information has been desired.

Such a magnetic image does not need to be formed on the entire surface of the substrate of the information recording medium, but is formed as magnetic information fixed only on a part thereof, and a magnetic track capable of ordinary magnetic recording is formed on the remaining part. By recording rewritable magnetic information there, a more flexible and highly secure information recording medium can be realized. However, the introduction of such normal magnetic recording causes a danger that the magnetic information is read and analyzed because the recorded content is rewritable, and therefore, a countermeasure is required.

Accordingly, an object of the present invention is to overcome the drawbacks in forming magnetic information by the above printing method, to provide different magnetic information (magnetic images) for each information recording medium, and to provide the magnetic images with different information. It is an object of the present invention to provide an information recording medium that can prevent unauthorized reading of this magnetic information and ensure high security even when used in combination with normal magnetic recording.

[0007]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present invention has been made as follows.

(1) An information recording medium characterized in that a magnetic image is provided on a substrate, and a magnetic shielding layer for magnetically shielding the magnetic image is provided on a part or the entire surface of the magnetic image. An information recording medium, wherein the magnetic image is a magnetic image formed by eluting and removing a part of a magnetic layer coated on a substrate using a removing solution.

(2) An information recording medium characterized in that a magnetic image is provided on a substrate and a magnetic shielding layer for magnetically shielding the magnetic image is provided on a part or the entire surface of the magnetic image. An information recording medium, wherein the magnetic image is formed by transferring a magnetic thermal transfer ink ribbon containing a magnetic material to a substrate.

(3) A magnetic image formed by eluting and removing a part of the magnetic layer formed on the substrate by using a removing solution as described in (1) above, the magnetic image of the removing solution is formed on the substrate. An elution-removable magnetic layer containing a resin and magnetic particles as main components that can be washed and removed in the presence of water is provided, and a resist image corresponding to a magnetic image is formed on the elution-removable magnetic layer, and then a non-image portion is formed. An information recording medium characterized by being formed by eluting and removing lipase.

(4) An information recording medium, wherein the formation of the resist image according to (3) is a transfer of a resist layer by a thermal transfer method.

(5) A magnetic image formed by eluting and removing a part of the magnetic layer coated on the substrate by using the removing liquid according to (1) is formed on the substrate. An elution-removable magnetic layer mainly composed of resin and magnetic particles that can be removed by washing in the presence of water is provided. Then, the removal liquid is directly applied to the elution-removable magnetic layer by an inkjet method, and then the printed portion is washed with water. An information recording medium which is formed by removing.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is to provide an information recording medium having a high anti-counterfeit effect by forming a magnetic image on demand. An information recording medium having higher security and a wide range of applications can be provided by protecting magnetic information by magnetically shielding a part or all of the magnetic information and preventing unauthorized reading of information.

Next, the specific contents of the present invention will be explained in detail together with explanations of terms. First, the information recording medium of the present invention has a “magnetic image” formed on demand, and it can be said that this magnetic image is a non-uniform distribution of a magnetic substance formed on a substrate. it can. On the other hand, "normal magnetic recording"
In a magnetic layer having a uniform distribution of magnetic particles, regions having different magnetization directions are sequentially generated by a magnetic head or the like, and are read as magnetic signals. For this reason, the magnetic signal of “normal magnetic recording” can be rewritten any number of times,
Although it can be said to be an excellent aspect of magnetic recording, it is also a fact that the rewritable point of this "normal magnetic recording" allows for illegal acts called alteration. The “magnetic image” is image information that can be magnetically detected, and has a non-uniform distribution of a magnetic substance fixed on a substrate, and thus cannot be rewritten by a magnetic head or the like. And because it's magnetic information,
It also has the advantage of magnetic information, such as being resistant to dirt. In the present invention, it is very important that this magnetic image cannot be rewritten.

Next, a specific method for forming a magnetic image on demand according to the present invention will be described. Broadly speaking, it is a method based on “removal” and “transfer”. First, in the “removal”, an “elution-removable magnetic layer” having a resin that is water-soluble in the presence of the “removal solution” as a main component of the resin component is provided. This is a method of obtaining a “magnetic image” by eluting and removing a part using the “removal solution”. Therefore, the term “removal liquid” as used in the present invention refers to a liquid that can be made water-soluble by imparting solubility to water to the resin component of the elution-removable magnetic layer or swelling the resin component. In contrast to the “elution-removable magnetic layer”, a magnetic layer mainly composed of a resin and magnetic particles that cannot be washed and removed even in the presence of a removing solution is referred to as a “non-elution-removable magnetic layer”. I do.

By the "removal" by the "removal liquid",
In order to form a magnetic image, it is necessary to provide the "elution-removable magnetic layer" at an appropriate portion with resistance to a removing solution. In the present invention, as an example, a method of providing a resist layer on the “elution-removable magnetic layer” by thermal transfer printing is used.

Alternatively, when the “removal liquid” is directly applied onto the “elution-removable magnetic layer” by an ink jet method, only the portion printed with the “removal liquid” becomes water-soluble.
If this is washed with water, only the printed portion is washed and removed, and a magnetic image can be formed.

Another method of forming a "magnetic image" is "transfer", which is a method of forming a "magnetic image" by transferring the magnetic ink of a thermal transfer ink ribbon containing a magnetic material onto a substrate. It is.

The information recording medium of the present invention is characterized in that a "magnetic shielding layer" for magnetically shielding the "magnetic image" is provided on a part or all of the upper layer of the "magnetic image". As a medium, the "magnetic shielding layer" shields the magnetic field lines from the "magnetic image" and the "normal magnetic recording" portion, and as a result, it is impossible to read a magnetic signal by a magnetic viewer or the like. Also, when a magnetic shielding layer is provided on the magnetic image and the upper layer of the normal magnetic recording portion,
A signal cannot be read by a normal reading method using a magnetic head, and the signal must be read while a DC bias current is applied to the magnetic head.

When a part of the magnetic image is used for "normal magnetic recording" in the information recording medium of the present invention, this area is called "normal magnetic track". In "(3)", a resist image is formed in advance in an area used as a "normal magnetic track", and the resist image is protected so as not to be removed in an elution removal step. This is realized as one of the magnetic images formed in the image. In other words, this means that the magnetic image as the fixed magnetic information and the normal magnetic track are on the same surface. Alternatively, recording of a magnetic image by thermal transfer is realized by forming an area that becomes a “normal magnetic track” on the substrate by “transfer”.

Next, specific examples of the components of the information recording medium of the present invention are as follows.

The substrate of the information recording medium of the present invention is P
ET and other synthetic resin films, paper, various nonwoven fabrics, synthetic paper,
A metal plate, a foamed film, a synthetic resin laminated paper, glass, or the like, or a composite sheet combining these can be used according to the purpose, but is not limited thereto.

600 used in the information recording medium of the present invention
As the magnetic material having a coercive force equal to or higher than Oersted, a magnetic material used for a known magnetic recording material can be used. For example, a specific example of a magnetic material is γ-
Examples include Fe ₂ O ₃ , Fe ₃ O ₄ , Co-containing iron oxide, CrO ₂ , metal powder, and Ba ferrite.

The resin exhibiting the property of being removed by washing with a removing solution according to the present invention includes (meth) acrylic acid,
Acrylic resin composed of (meth) acrylic acid ester, vinyl acetate resin, copolymer of vinyl acetate and ethylene or vinyl chloride, copolymer of vinyl acetate and crotonic acid, vinyl chloride resin, vinylidene chloride resin, vinyl Acetal resins, polystyrene, copolymers of styrene with butadiene or (meth) acrylate, polyethylene, polypropylene and its chlorides, polyester resins such as polyethylene terephthalate and polyethylene isophthalate, polyamide resins, phenol resins, xylene resins, Examples thereof include alkyd resins, vinyl-modified alkyd resins, gelatin, cellulose ester derivatives, polycarbonate, and wax. The weight average molecular weight of these resins is preferably 5,000 to 250,000.

In the elution-removing magnetic layer, in addition to a resin which is said to have a property capable of being washed and removed with a removing solution, the rheology of the coating solution, the film strength, the dispersibility of the magnetic particles, the adhesion, etc. Other resins can be included as needed. In that case, as a usable resin, polyurethane resin such as urethane / acrylic copolymer, epoxy resin, phenol resin, phenoxy resin, melamine resin, urea resin, furfural resin, unsaturated polyester resin, alkyd resin, silicone resin, Xylene resin, toluene resin, acrylate / vinylidene chloride copolymer, methacrylate / vinylidene chloride copolymer, methacrylate / styrene copolymer, methyl methacrylate / butadiene copolymer, maleic acid-modified acrylic resin, etc. Acrylic resin, styrene / butadiene copolymer, styrene / butadiene copolymer, styrene / butadiene / methyl methacrylate copolymer, styrene / maleic acid copolymer, styrene / acrylic copolymer, styrene / butadiene / methyl Styrene resin such as methacrylate copolymer, fluorine resin, polyamide resin, polyether resin, polyester resin, polyolefin resin, polycarbonate resin, polyvinyl acetal resin, polyvinyl ether resin, polyvinyl butyral resin, vinylidene chloride / acrylonitrile copolymer, etc. Vinylidene chloride resin, vinyl chloride / vinyl acetate copolymer, vinyl chloride / vinyl acetate / maleic acid copolymer, vinyl chloride / vinylidene chloride copolymer, vinyl chloride / vinyl acetate / vinyl alcohol acid copolymer, vinyl chloride Acrylonitrile copolymer, vinyl chloride resin such as partially saponified vinyl chloride / vinyl acetate copolymer resin, vinyl acetate, melamine / formaldehyde copolymer resin, polyvinyl fluoride resin, butadiene / acrylonitrile copolymer, urine -Use a known resin such as formaldehyde resin, cellulose acetate resin, cellulose diacetate resin, cellulose triacetate resin, cellulose acetate propionate resin, methylcellulose resin, hydroxymethylcellulose resin, hydroxyethylcellulose resin, carboxymethylcellulose resin, and polyvinyl alcohol resin. However, the present invention is not limited to them.
However, in order to obtain good elution and removal properties of the magnetic layer, the ratio of the other resin component to the resin exhibiting properties that can be washed and removed with a removing solution is 0.8 or less, more preferably 0.5 or less. It is desirable to do.

In dispersing the magnetic particles, the resin used may sometimes serve as a dispersant, but if necessary, a fatty acid, an aliphatic amine, a fatty acid metal salt, Phosphate ester, polyester oligomer, ammonium salt of monocarboxylic acid, titanium coupling agent, silane coupling agent, lecithin,
Animal and vegetable proteins, polycarboxylic acids and salts thereof, sodium pyrophosphate, sodium hexametaphosphate, casein, sodium ligninsulfonate, dipolyoxyethylene alkyl ether phosphate, tripolyoxyethylene alkyl ether phosphate, polyester polyamine, Known compounds such as polyoxyethylene stearylamine, polyoxyethylene oleylamine, polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, and polyoxyethylene ceteryl ether can be used, but the present invention is not limited thereto. is not.

As a method for applying the elution-removable magnetic layer and the non-elution-removable magnetic layer of the information recording medium of the present invention, known techniques can be used. Specifically, a dipping method, a rod coating method, a bar coating method, Coating techniques such as curtain coating, slide hopper coating, roll coating, spray coating, air knife, blade coating, extrusion die coating, gravure coating, and squeeze coating can be used.

Additives to the elution-removing magnetic layer include surfactants, antioxidants, defoamers, leveling agents, preservatives, viscosity stabilizers, pH regulators, lubricants, abrasives, leveling agents, Antifoaming agents, thickeners, ultraviolet absorbers, antistatic agents,
Additives such as fillers can be used as appropriate.

As the removing liquid for the information recording medium of the present invention, an alkaline liquid can be used when the resin layer is soluble in alkali. Examples of the basic compound contained in the alkaline liquid include inorganic basic compounds such as alkali metal silicate, alkali metal hydroxide, phosphoric acid and alkali metal carbonate and ammonium salt, ethanolamines, ethylenediamine, propanediamine, and triethylene. Organic basic compounds such as tetramine and morpholine can be used. The above basic compounds can be used alone or as a mixture. Water can be advantageously used as a solvent for the alkaline liquid.

When the resin layer is not alkali-soluble, an organic solvent that dissolves the resin layer, such as alcohol such as methanol, ethanol, and propanol, dioxane, dioxolan, butyl cellosolve, acetone, and methyl ethyl ketone, is used as the removing solution. Can be.

In the information recording medium of the present invention, in order to form a magnetic image on the substrate by elution and removal, the resin layer which can be removed with a removing solution is washed away with water.
In this water washing, a surfactant, an antifoaming agent, a preservative, a viscosity stabilizer, a pH adjuster and the like may be added as additives. Further, in order to increase the removal efficiency, the water temperature may be increased within a range where the magnetic layer in the resist image area is not softened or dissolved. The preferred temperature range is 20-50 ° C.

As a component of the magnetic thermal transfer ink ribbon of the information recording medium of the present invention, the melting temperature is 50 to 110 ° C.
It contains at least one kind of wax or thermoplastic resin and magnetic particles, but can further contain oils and fats. When each of them is used in combination, the contents thereof are as follows: magnetic particles 2 to 65%, wax 0 to 70%, thermoplastic resin 0 to 60%, fats and oils 0 to 30
% Is appropriate. Specific examples of the wax include carbana wax, montan wax, paraffin wax, microcrystalline wax, and beeswax.

As the thermoplastic resin, ethylene-
Vinyl acetate copolymer, polyacetal resin, vinyl chloride resin, butadiene resin, polybutene, acrylic resin, styrene resin, polyvinyl butyral, carbamic acid ester, hard rosin, phenol resin, polyurethane resin, ketone resin, maleic acid resin, pentaerythritol ester , Ester gum, polyamide, ethyl cellulose and the like can be used.

Further, specific examples of fats and oils include mineral oil, dioctyl phthalate, tricresyl phosphate, dibutyl phthalate, lanolin and the like.

As a support for the magnetic thermal transfer ink ribbon, synthetic resin films such as PET, paper, various nonwoven fabrics, synthetic paper, metal foil, and the like can be used, but are not limited thereto.

When a protective layer is provided between the magnetic thermal transfer layer and the support of the magnetic thermal transfer ink ribbon used in the present invention, a release layer is further provided between the magnetic thermal transfer layer or the protective layer and the support. In such a case, the wax and the thermoplastic resin can be used alone or in combination as a material used for the protective layer and the release layer. In addition, an inorganic pigment such as silica, talc, or calcium carbonate can be added to the protective layer.

The magnetic thermal transfer ink ribbon used in the present invention may contain a lubricant, a leveling agent, a defoaming agent, a thickener, an antioxidant, an ultraviolet absorber, an antistatic agent, if necessary.
Additives such as preservatives and fillers can be used as appropriate.

The magnetic shielding layer of the information recording medium of the present invention is provided on one or all of the upper part of the magnetic image. The main components of such a magnetic shielding layer include Fe, Ni, Mn-Zn
Ferrite, Ni-Zn ferrite, Mn ferrite,
A high magnetic permeability soft magnetic material such as Zn ferrite, sendust, and permalloy is used. The magnetic shielding layer made of such a soft magnetic material may be a thin film formed by vapor deposition, sputtering, or the like, or may be provided by coating a coating liquid in which soft magnetic fine particles are dispersed. In the case of coating, the same known technique as described above for the method of applying the elution-removable magnetic layer can be used.

As the resin component of the magnetic shielding layer, polyurethane resin such as urethane / acrylic copolymer, epoxy resin, phenol resin, phenoxy resin, melamine resin,
Urea resin, furfural resin, unsaturated polyester resin, alkyd resin, silicon resin, xylene resin, toluene resin, acrylate / vinylidene chloride copolymer, methacrylate / vinylidene chloride copolymer,
Acrylic resins such as methacrylic acid ester / styrene copolymer, methyl methacrylate / butadiene copolymer, maleic acid modified acrylic resin, styrene / butadiene copolymer, styrene / butadiene copolymer, styrene / butadiene / methyl methacrylate copolymer Coalescence, styrene
Maleic acid copolymer, styrene / acrylic copolymer, styrene / butadiene / methyl methacrylate copolymer,
Such as styrene resin, fluorine resin, polyamide resin, polyether resin, polyester resin, polyolefin resin, polycarbonate resin, polyvinyl acetal resin, polyvinyl ether resin, polyvinyl butyral resin, vinylidene chloride resin such as vinylidene chloride / acrylonitrile copolymer, chloride Vinyl / vinyl acetate copolymer,
Vinyl chloride / vinyl acetate / maleic acid copolymer, vinyl chloride / vinylidene chloride copolymer, vinyl chloride / vinyl acetate / vinyl alcohol acid copolymer, vinyl chloride / acrylonitrile copolymer, partially saponified vinyl chloride / vinyl acetate Vinyl chloride resin such as copolymer resin, vinyl acetate, melamine / formaldehyde copolymer resin, polyvinyl fluoride resin, butadiene / acrylonitrile copolymer, urea / formaldehyde resin, cellulose acetate resin, cellulose diacetate resin, cellulose triacetate resin, Known resins such as cellulose acetate propionate resin, methylcellulose resin, hydroxymethylcellulose resin, hydroxyethylcellulose resin, carboxymethylcellulose resin, and polyvinyl alcohol resin can be used. These resin components may be used alone or in combination of two or more.

In the magnetic shielding layer, other additives such as a dispersant, a surfactant, an antioxidant, an antifoaming agent, a leveling agent,
Additives such as preservatives, viscosity stabilizers, pH regulators, lubricants, abrasives, leveling agents, defoamers, thickeners, ultraviolet absorbers, antistatic agents and fillers can be used as appropriate.

The information recording medium of the present invention comprises at least a magnetic image and a magnetic shielding layer thereon as constituents on a support, but between the support and the magnetic image, between the magnetic image and the magnetic shielding layer. An undercoat layer or an intermediate layer may be provided between them for the purpose of adhesiveness, durability and the like. Further, a protective layer or a print layer may be provided on the magnetic shielding layer according to the purpose of improving abrasion resistance, chemical resistance, durability and design.
At this time, the protective layer may be transparent so that magnetically recognizable image information can be viewed, or may be opaque with a concealing power that makes it invisible. Further, the undercoat layer, the intermediate layer, and the protective layer may be composed of two or three or more layers. The magnetic shielding layer need not be provided on the entire surface of the magnetic image, but may be provided only on a part of the magnetic image.

[0042]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings, but the present invention is not limited to these embodiments.

Embodiment 1 In this embodiment, the information recording medium of the present invention is applied to a magnetic card. FIGS. 1, 2, 3, and 5 sequentially illustrate the manufacturing process of the present embodiment as changes in the cross-sectional view of the card-shaped information recording medium of the present embodiment. FIG. 2 is a cross-sectional view when a magnetic layer is formed, FIG. 2 is a cross-sectional view when a resist image is formed on the elution-removable magnetic layer in FIG. 1, and FIG. FIG. 4 is a cross-sectional view of a card-shaped information recording medium having a magnetic image formed on a non-resist image portion, which is taken along a dotted line AA ′ shown in a plan view at the time when a non-resist image portion is eluted and removed. Is shown. Thereafter, a magnetic shielding layer is provided on the entire surface of the support. FIG. 5 shows a cross section of the magnetic card of this embodiment at this point.

Next, the manufacturing process of the first embodiment will be described more specifically. (A) Synthesis of Resin for Elution-Removable Magnetic Layer A mixture of 40 parts by weight of methyl methacrylate, 40 parts by weight of butyl acrylate, 20 parts by weight of acrylic acid and 2 parts by weight of AIBN (azobisisobutyronitrile) is mixed with a nitrogen gas atmosphere. 1,4- which was kept at 100 ° C under
The mixture was added dropwise to 90 parts by weight of dioxane over 3 hours, and 0.5 parts by weight of AIBN and 10 parts by weight of 1,4-dioxane were added. The resulting resin was obtained. The weight average molecular weight of this resin was 22,000.

(B) Elution-removing magnetic layer 215 parts of the resin synthesized in (A) and the following materials were mixed and dispersed for 4 hours using a paint conditioner. Magnetic material (Ba ferrite, coercive force 2750 Oersted) 100 parts Dispersant (phosphate ester) 5 parts MEK 100 parts Toluene 50 parts Cyclohexanone 50 parts White dispersion (thickness: 188 μm)
m) was applied to a thickness of 5 μm. In applying the magnetic layer, an orientation magnetic field of 3000 G was applied immediately after the application to orient the magnetic particles.

(C) Formation of resist image and elution removal of non-resist image area A bar code image and a rectangular image for a magnetic track were formed on the elution-removable magnetic layer thus formed by a fusion heat transfer printer. Thereafter, the magnetic card on which the resist image was formed was immersed in a removing solution having the following composition for 8 seconds, washed with water, and the non-resist image portion was eluted and removed to form a barcode magnetic image.

(D) Preparation of Removal Solution Sodium silicate 20 parts Sodium hydroxide 10 parts Ion-exchanged water 40 parts

(E) Magnetic Shielding Layer The following materials were mixed and dispersed for 4 hours using a paint conditioner. Soft magnetic material (Mn-Zn ferrite, initial magnetic permeability 1800) 100 parts Dispersant (phosphate ester) 5 parts Polyurethane resin 30 parts MEK 100 parts Toluene 50 parts Cyclohexanone 50 parts A magnetic image was formed from the dispersion liquid thus formed. The whole surface of the substrate was coated to a thickness of 25 μm.

(E) Reading of Magnetically Recorded Information of a Magnetic Image In order to read out magnetically recorded information written on a formed magnetic image with a magnetic head, a DC bias current must be applied to the magnetic head. FIG. 6 shows the result of reading the magnetic signal written in the magnetic image, and it can be seen that the signal from the normal magnetic track is observed with a sufficient output. In the same manner, the signal of the magnetic bar code portion can be read, and the measurement result is shown in FIG.

Embodiment 2 This embodiment also applies the information recording medium of the present invention to a magnetic card. FIGS. 8, 9, 10, and 12 sequentially illustrate the manufacturing process of the present embodiment as a change in the cross-sectional view of the card-shaped information recording medium of the present embodiment. It is formed as. FIG. 8 is a cross-sectional view showing a case where an elution-removable magnetic layer is formed on a support,
FIG. 9 is a cross-sectional view when an image is formed on the elution-removable magnetic layer of FIG. 8 using a removing solution, and FIG. 10 is a card having a magnetic image finally formed after the image recording portion of FIG. 10 are cross-sectional views of the magnetic information recording medium, each showing a cross-sectional view along the dotted line AA ′ in the plan view 11 of the magnetic card at the time of FIG. Thereafter, a magnetic shielding layer is provided on the entire surface of the support. FIG. 12 shows a cross section of the magnetic card of this embodiment at this point.

Next, the manufacturing process of this embodiment will be described more specifically. (A) Synthesis of Resin A mixture comprising 40 parts by weight of methyl methacrylate, 40 parts by weight of butyl acrylate, 20 parts by weight of acrylic acid and 2 parts by weight of AIBN (azobisisobutyronitrile) is kept at 100 ° C. under a nitrogen gas atmosphere. 1, 4-
The mixture was added dropwise to 90 parts by weight of dioxane over 3 hours, and 0.5 parts by weight of AIBN and 10 parts by weight of 1,4-dioxane were added. The resulting resin was obtained. The weight average molecular weight of this resin was 22,000.

(B) Elution-removing magnetic layer 330 parts of a resin containing a monomer having an anionic functional group synthesized in (A) as a polymerization component, and the following materials were mixed, and dispersed for 4 hours using a paint conditioner. did. Magnetic material (barium ferrite, coercive force 2700 Oersted) 370 parts Phosphoric acid ester 18 parts MEK 100 parts Toluene 100 parts
On T, it was applied to a thickness of 5 μm by a gravure coater.
Immediately after coating, a magnetic field of 2000 G was applied to the magnetic layer to orient the magnetic particles.

(C) Removal liquid 20 parts of sodium silicate 10 parts of sodium hydroxide 40 parts of ion-exchanged water

(D) Printing of Image Data and Removal of Elution of Printed Area by Removal Solution The removal layer (C) is applied to the formed elution-removable magnetic layer using an inkjet printer (MJ-510C; manufactured by EPSON). A barcode image was printed. The portion printed by this removing liquid is slightly discolored and its pattern can be recognized from the surface of the elution-removable magnetic layer. Thereafter, the card-shaped recording medium on which the image was formed was washed off with water and removed to form a bar-coded magnetic image. (E) Magnetic Shielding Layer Thereafter, a coating liquid of a magnetic shielding layer having the same composition as in Example 1 was applied to a thickness of 25 μm on the entire surface of the substrate on which the magnetic image was formed. (F) Confirmation of Magnetic Shielding Effect and Signal Reading The recorded contents of the card-shaped information recording medium prepared in Example 2 above cannot be viewed with a viewer or the like because of the magnetic shielding layer, and can be read even with a normal magnetic head. Could not read the magnetic signal. Next, as in Example 1, a DC bias current was applied to the magnetic head, and the magnetic information was read. As a result, both the normal magnetic track and the magnetic barcode could be observed with a good S / N ratio.

Embodiment 3 This embodiment also applies the information recording medium of the present invention to a magnetic card. FIGS. 13 and 15 illustrate the manufacturing process of the present embodiment in order as a change in the cross-sectional view of the card-shaped information recording medium of the present embodiment. The magnetic image information is formed as bar-code image information. I have. FIG. 13 is a cross-sectional view of a magnetic card in which a barcode-shaped magnetic image is formed by transferring a part of a magnetic thermal transfer ink ribbon on a support, and FIG. 15 is a cross-sectional view of a magnetic card having a magnetic shielding layer provided thereon.
Both show cross-sectional views along the dotted line AA 'in the plan view 14 of the magnetic card at the time of FIG. (A) Preparation of Magnetic Thermal Transfer Ink Ribbon A release layer was formed on a 6 μm-thick polyester film with a composition of carnauba wax: acrylic resin = 1: 1 to a thickness of 2 μm. The liquid was applied to form a magnetic thermal transfer layer. At this time, before the magnetic thermal transfer layer was dried, the magnetic particles in the magnetic thermal transfer layer were oriented in the coating direction by passing the magnetic thermal transfer layer through a magnetic field of 2500 Gauss by a repelling opposing magnet. The thickness of the dried magnetic thermal transfer layer was 5 μm.

(B) Magneto-thermal transfer layer 100 parts of magnetic material (barium ferrite, coercive force 2750 Oersted) 5 parts of dispersant (sodium polycarboxylate) 106 parts of water The above composition was dispersed for 4 hours using a paint conditioner, and The dispersion was prepared. Next, the following composition was added to this preliminary dispersion, and the mixture was stirred to obtain a magnetic coating liquid. Carnauba wax emulsion (40%) 400 parts Acrylonitrile-butadiene copolymer (40%) 200 parts

(C) Writing of magnetic image information The magnetic thermal transfer ink ribbon is made of 188 μm white PET.
After press bonding, the print head KJT-256-8 manufactured by Kyocera
Okura Electric Thermal Printing Tester TH-PMD with MGF1
, An applied pulse width of 2.0 milliseconds and an applied voltage of 20.
Under a condition of 0 V, a barcode-shaped magnetic image was printed.

(D) Magnetic Shielding Layer Thereafter, a coating liquid for a magnetic shielding layer having the same composition as in Example 1 was applied to a thickness of 25 μm on the entire surface of the substrate on which the magnetic image was formed.

(E) Confirmation of Magnetic Shielding Effect and Signal Reading The recorded contents of the card-shaped information recording medium prepared in the second embodiment cannot be viewed with a viewer or the like because of the magnetic shielding layer, and the ordinary magnetic head Could not read a magnetic signal. Next, as in Example 1, a DC bias current was applied to the magnetic head, and the magnetic information was read. As a result, both the normal magnetic track and the magnetic barcode could be observed with a good S / N ratio.

[0060]

According to the present invention, each card has separate non-rewritable magnetic information, and furthermore, the recorded contents recorded on the magnetic layer are concealed by the magnetic shielding layer, so that very high security information is obtained. A recording medium was realized.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a magnetic card when an elution-removable magnetic layer is provided on a support.

FIG. 2 is a cross-sectional view at the time when a resist image is formed on an elution-removable magnetic layer of the magnetic card of FIG. 1;

FIG. 3 is a cross-sectional view of the magnetic card of the card system of the present invention after a resist image has been formed and a non-resist image portion of the elution-removable magnetic layer has been eluted and removed.

FIG. 4 is a plan view of the magnetic card at the time of FIG. 3;

FIG. 5 is a cross-sectional view of the magnetic card when a magnetic shielding layer is provided on the magnetic card of FIG. 4;

6 is a diagram showing a read signal of a magnetic signal of a normal magnetic track (reference numeral 4) in FIG. 4;

FIG. 7 is a view showing a read signal of a magnetic signal of the magnetic bar code (reference numeral 5) in FIG. 4;

FIG. 8 is a cross-sectional view of the magnetic card at the time when an elution-removable magnetic layer is provided on a support.

FIG. 9 is a cross-sectional view of the magnetic card at the time when a barcode pattern is printed on the elution-removed magnetic layer of FIG. 8 by using a removing liquid.

FIG. 10 is a cross-sectional view of the magnetic card at the time when the printed portion of the barcode-like pattern of FIG. 9 has been washed away.

FIG. 11 is a plan view of the magnetic card at the time of FIG. 9;

FIG. 12 is a cross-sectional view of the magnetic card when a magnetic shielding layer is provided on the magnetic card of FIG. 10;

FIG. 13 is a cross-sectional view of a magnetic card at the time when a barcode-shaped magnetic image is formed by transferring a part of a magnetic thermal transfer ink ribbon onto a support.

FIG. 14 is a plan view of the magnetic card at the time of FIG. 13;

FIG. 15 is a cross-sectional view of the magnetic card at the time when a magnetic shielding layer is provided on the magnetic card of FIG. 13;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 support 2 elution-removable magnetic layer 3 resist image 4 magnetic track for normal magnetic recording 5, 9 barcode-like magnetic image 6 magnetic shielding layer 7 printed part with removed liquid 8 part where printed part with removed liquid was washed away 10 magnetism Magnetic image by thermal transfer layer

Claims (5)

[Claims] 1. An information recording medium comprising: a magnetic image provided on a substrate; and a magnetic shielding layer for magnetically shielding the magnetic image provided on a part or the entire surface of the magnetic image. An information recording medium, wherein the magnetic image is a magnetic image formed by eluting and removing a part of a magnetic layer coated on a substrate using a removing solution. 2. An information recording medium comprising: a magnetic image provided on a substrate; and a magnetic shielding layer for magnetically shielding the magnetic image provided on a part or the entire surface of the magnetic image. An information recording medium, wherein the magnetic image is formed by transferring a magnetic thermal transfer ink ribbon containing a magnetic material to a substrate. 3. A magnetic image formed by eluting and removing a part of a magnetic layer coated on a substrate using a removing liquid according to claim 1, wherein the magnetic image is present on the substrate. An elution-removable magnetic layer containing a resin and magnetic particles that can be washed and removed under water as main components is provided, and a resist image corresponding to a magnetic image is formed on the elution-removable magnetic layer, and then a non-image portion is formed. An information recording medium formed by elution and removal. 4. An information recording medium according to claim 3, wherein the formation of the resist image according to claim 3 is a transfer of a resist layer by a thermal transfer method. 5. A magnetic image formed by eluting and removing a part of a magnetic layer coated on a substrate using the removing solution according to claim 1, wherein a magnetic image is formed on the substrate. After providing an elution-removable magnetic layer having a resin and magnetic particles as main components that can be washed and removed under water, and then applying a removing liquid directly to the elution-removable magnetic layer by an inkjet method to form a printed portion, An information recording medium formed by washing and removing the printed portion.