JP2759747B2 - Magnetic recording medium and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a prepaid card,
The present invention relates to a magnetic recording medium such as a D card, a cash card, a point card, a ticket (commuter pass, ticket, coupon), a magnetic card, a magnetic sheet, a magnetic roll paper used for a pass ticket, and a method of manufacturing the same. It is another object of the present invention to provide a magnetic recording medium having an unauthorized use preventing function.

[0002]

2. Description of the Related Art In recent years, prepaid cards, ID cards,
Cash card, point card, ticket (commuter pass,
In the field of magnetic recording media used for applications such as magnetic cards, magnetic sheets, magnetic roll paper, etc. used for tickets, coupons, pass tickets, etc., how to prevent unauthorized use such as counterfeiting, alteration, etc. It is a big theme. Conventionally, many methods have been proposed for imparting an unauthorized use preventing function to this type of magnetic recording medium, and each of these methods is roughly classified into the following two types. First, as a first type of method, there is a method of hiding regular magnetic information so that it cannot be read by a normal method. A second type of method is a method in which identification information for determining whether a magnetic recording medium is a legitimate one is given to the magnetic recording medium itself.

As one of the first types of methods, there is known a method in which a magnetic recording layer is multi-layered, and regular information and dummy information are recorded on different magnetic recording layers. In this method, if the regular information and the dummy information are recorded on the same track, the regular information cannot be read by the normal method because the dummy information is superimposed on the regular information when the information is read. Therefore, unauthorized use can be prevented. Also, as one of the second types of methods, a method of providing a magnetically readable barcode on a magnetic recording medium is known. According to this method, it is possible to determine whether or not the magnetic recording medium is legitimate based on the barcode information, thereby preventing unauthorized use.

[0004]

However, each of these conventional methods for preventing unauthorized use has a drawback and is not a satisfactory method. That is, first, in the magnetic recording medium provided with the unauthorized use prevention function according to the first type of method, once the method of reading the legitimate information has been clarified, a large amount of the magnetic recording medium can be copied. There is a problem that becomes possible. Further, the magnetic recording medium provided with the second type of unauthorized use prevention function has a large amount of magnetic recording medium because the magnetic recording medium itself has information for determining whether the magnetic recording medium is genuine. Although it is difficult to copy or use the medium, there is a problem that it is not possible to cope with unauthorized use due to alteration such as rewriting information of a legitimate medium.

The present invention has been made in view of the above circumstances, and unlike a conventional magnetic recording medium with a forgery prevention function, different forgery prevention information can be recorded on each magnetic recording medium. It is an object of the present invention to provide a magnetic recording medium capable of making it impossible to add or delete information for use, and having a very high forgery prevention capability, and a method of manufacturing the same.

[0006]

According to the first aspect of the present invention , at least one of the first and second aspects of the present invention is provided on a non-magnetic substrate.
In a magnetic recording medium having one magnetic layer formed,
The magnetic layer has a coercive force of 100 Oe or less;
A large number of magnets dispersed in the binder and the binder
Comprising magnetic particles in the binder of the magnetic layer.
High density of magnetic particles by distributing particles in specific shades
The protruding part formed by the dense magnetic particles
Which makes writing and erasing impossible
It is characterized by forming fixed information.

According to a second aspect of the present invention, in order to solve the above-mentioned problems, a protrusion formed by densely packed magnetic particles is provided.
And a bar-code pattern is formed .

According to a third aspect of the present invention, in order to solve the above-mentioned problems, a non-magnetic holding base material has a thickness of 250 to 5,000 elsters.
Forming a first magnetic layer having a coercive force of
Magnetic recording is performed on the first magnetic layer, and then on the first magnetic layer.
A magnetic paint having a coercive force of 250 to 5000 Oe, a magnetic paint for a second magnetic layer comprising a binder and a solvent, and applying the magnetic particles in the binder according to the strength of the magnetic field generated by the first magnetic layer. and causing the shade to the distribution of
Formed by densely packed magnetic particles in areas with high concentration of magnetic particles
Formed protrusions, and then the binder was evaporated by evaporation of the solvent.
Said first magnetic layer to the second magnetic layer by fixing a particular shade state magnetic particles in the second magnetic layer by drying the Zehnder
Fixed information corresponding to the magnetic information of
Form a magnetic transfer tape by forming an adhesive layer on the layer, and then
Using the magnetic transfer tape, the first
This is to transfer only two magnetic layers .

[0009]

In a magnetic layer formed on a nonmagnetic substrate and having a low coercive force of 100 Oe or less, magnetic particles are dispersed in a specific density within the magnetic layer so that the magnetic particles are densely aggregated in the magnetic layer. By forming the portion, the fixed information that cannot be written or erased by the density of the magnetic particles is recorded in the magnetic layer. The fixed information given to the second magnetic layer cannot be detected by a normal magnetic head because the magnetic material used in the second magnetic layer has a very low coercive force of 100 Oe or less. However, the fixed information can be magnetically read by reading with a magnetic head while applying a bias magnetic field. Therefore, it is possible to easily identify the magnetic recording medium by using the fixed information, and it is possible to prevent unauthorized use of the magnetic recording medium, such as forgery or falsification.

Next, according to the method of the present invention, the second magnetic layer having a low coercive force is formed on the first magnetic layer having a high coercive force on which magnetic recording has been performed on the holding substrate. Fixed information corresponding to the magnetic information can be provided to the second magnetic layer.
That is, when forming the second magnetic layer on the first magnetic layer, a magnetic paint containing magnetic particles, a binder and a solvent is applied on the first magnetic layer, the solvent is volatilized, and the binder is dried to form the second magnetic layer .
If Ru obtain magnetic layer, the binder before the solvent is evaporated
The magnetic particles to form a shading state matching the magnetic information of the first magnetic layer set and dispersed, high concentration of magnetic particles
Since the projections formed by the denseness of the magnetic particles are formed in the portions, the density of the magnetic particles forms the fixed magnetic information of the second magnetic layer.

Since the magnetic information to be written in the first magnetic layer can be arbitrarily changed using a magnetic recording element such as a magnetic head, the fixed magnetic information to be formed in the second magnetic layer can be arbitrarily selected. Therefore, for example, it is also possible to record unique fixed magnetic information corresponding to each magnetic recording medium.
Then, the magnetic recording medium having the second magnetic layer having the fixed information is obtained by attaching and transferring the second magnetic layer having the fixed information to the non-magnetic substrate using the adhesive layer.

An example of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of a magnetic recording medium according to the present invention, in which a card-shaped substrate 1, a normal magnetic recording magnetic stripe 2 formed in parallel on one surface of the substrate 1, and a fixed magnetic layer. The information magnetic stripe 3 is provided. The cross-sectional structure along the line YY ′ of the magnetic recording medium shown in FIG. 1 has a magnetic stripe 2 in a groove 1a on one corner side of the base 1 as shown in FIG.
The magnetic recording medium A has a structure in which the magnetic stripes 3 are embedded in the grooves 1b on the other corners. The magnetic stripe 2 of this example includes a band-shaped adhesive layer 4 on the bottom side of the groove 1a, a magnetic layer 6 and a protective film layer 7 sequentially laminated thereon, and the magnetic stripe 3 has a groove 1b. Is provided with an adhesive layer 8, a second magnetic layer 5, and a protective coating layer 9 in this order from the bottom side.

Here, since the protective coating layers 7, 9 are provided to protect the magnetic layers 5, 6, they may be omitted in some cases. Further, a colored layer or a metal deposited film may be formed between the magnetic layer 6 and the protective coating layer 7 or between the second magnetic layer 5 and the protective coating layer 9 as necessary. Further, in the magnetic recording medium A of this example, the adhesive layer 4, the magnetic layer 6, and the protective coating layer 7 are thermocompression-bonded and embedded in the base 1, and the adhesive layer 8, the second magnetic layer 5, and the protective coating layer 9 are embedded. Are thermocompression-bonded and embedded in the base 1,
Each is integrated with the base 1. As shown in FIG. 2B, the adhesive layer 4, the magnetic layer 6, and the protective film layer 7 (magnetic stripe 2 '), and the adhesive layer 8, the second magnetic layer 5, and the protective film are formed on the upper surface of the base 1'. A magnetic recording medium B having a structure in which a layer 9 and a (magnetic stripe 3 ′) are sequentially laminated, respectively.
It may be.

The substrate 1 has a thickness of about 150 μm to 1 mm and is made of a non-magnetic material such as synthetic paper, wood pulp paper, laminated paper, polyester film, PVC sheet, polyethylene terephthalate, etc., depending on the intended use. An appropriate one may be used. Therefore, a sheet or film made of the above-mentioned material, a generally known material for a magnetic recording medium substrate, or a laminate thereof may be used. As the adhesive layer 4, a hot-melt type adhesive can be used. For example, an adhesive such as a vinyl chloride / vinyl acetate copolymer-based resin, a polyester-based resin, a polyamide-based resin, and a polyurethane-based resin is used alone or in combination. Can be used.

The first magnetic layer and the magnetic layer 6 have a thickness of 25
0 Oe (Oe) or more, for example, 250 to 500
The structure is such that magnetic particles (magnetic powder and the like) are dispersed in a binder so as to have a predetermined high coercive force within a range of 0 Oe. 250 to 40 as the magnetic particles
Gamma iron oxide (γ) having a coercive force of about 0 Oersted
-Fe ₂ O ₃ ) particles, cobalt-coated gamma iron oxide particles having a coercive force of about 600 to 700 Oe, 160
0-1900 Oersted or 2500-3000
Barium ferrite (BaO-6Fe ₂ O ₃ ) particles having a coercive force of about Oersted can be appropriately selected and used. In addition, particles of a known magnetic material such as chromium oxide and strontium ferrite may be used in addition to these materials.

The second magnetic layer 5 has a structure in which magnetic particles (magnetic powder and the like) are dispersed in a binder so as to have a predetermined low coercive force within a range of 100 Oe or less. As the above particles, carbonyl iron powder, zinc ferrite, manganese zinc ferrite, nickel powder, triiron tetroxide, permalloy, sendust, alpalm and the like are appropriately used.

The binder for dispersing and fixing each magnetic particle in the first magnetic layer and the magnetic layer 6 and the second magnetic layer 5 is a vinyl chloride / vinyl acetate copolymer resin, a polyurethane resin, a polyester resin, an epoxy resin. A binder obtained by adding a trace amount of an additive such as a pigment to a binder such as a resin can be used. In addition to these, a known binder for magnetic particles may be appropriately used. In addition, as the additive, an inorganic pigment such as silica or alumina, wax, silicon oil, or the like may be added.

On the bottom side of the second magnetic layer 5, a plurality of ridge-shaped protrusions 5a are formed at a predetermined interval as shown in FIG. Have been. These protrusions 5a are formed so that magnetic particles in the binder of the second magnetic layer 5 are densely swelled in this portion, and in the second magnetic layer 5, the portion of the protrusion 5a and the vicinity thereof are provided. Magnetic particles are densely aggregated. Therefore, in the second magnetic layer 5, the density of the magnetic particles is formed by the protrusions 5a, and a kind of magnetic barcode pattern is formed. The protective coating layer 7 can be used alone or in combination of acrylic resin, cellulose resin, urethane resin, polyester resin, epoxy resin, vinyl chloride / vinyl acetate copolymer resin, or the like.

FIG. 3 is an enlarged cross-sectional view of the magnetic recording medium of the present invention shown in FIG. 1 along the line XX '. The adhesive layer 8, the second magnetic layer 5, and the protective coating layer are formed on the upper surface of the base 1'. Reference numeral 9 denotes a structure that is sequentially laminated.

Next, an example of a method for manufacturing the magnetic recording medium having the above configuration will be described. In this example, an example of a method for manufacturing a magnetic recording medium B after manufacturing a magnetic transfer tape will be described. To manufacture the magnetic recording medium B, first, a holding substrate 10 made of a non-magnetic material as shown in FIG. 4 is used. The holding substrate 10 used here is, for example,
A polyester film having a thickness of about 5 to 500 μm can be used.

Next, 250-
A magnetic paint containing magnetic particles (magnetic powder), a binder and a solvent is applied so as to have a predetermined coercive force within the range of 5000 Oe, and the solvent is evaporated to dry the magnetic paint. To form a magnetic source having the same. At this time, the magnetic field orientation treatment may be performed on the first magnetic layer 11 to perform the magnetic powder orientation treatment. This magnetic field orientation processing
What is necessary is just to perform it using the magnet for orientation in the state where the said magnetic paint is not dried.

Next, magnetic recording is performed on the first magnetic layer 11 obtained as described above. This magnetic recording may be performed from the front side or the back side of the first magnetic layer 11 by a magnetic head in the same manner as in a normal magnetic recording system. As the magnetic head used at this time, a number of magnetic heads may be arranged in the width direction in accordance with the width of the magnetic material, or one magnetic head having a magnetic core large enough to record the entire width of the magnetic material may be used. May be. As a result of the magnetic recording, the first magnetic layer 11 has the structure shown in FIG.
Is formed as shown in FIG.

Next, a release layer 12 is formed on the first magnetic layer 11, and then a protective coating layer 7 is formed if necessary.
As the release layer 11, an acrylic resin, a cellulose resin, a urethane resin, a polyester resin, an epoxy resin, a vinyl chloride / vinyl acetate copolymer resin, or the like can be used alone or in combination.

Then, a second magnetic layer 16 is formed on the protective film layer 7. The second magnetic layer 16 is formed by applying a magnetic paint including a magnetic powder having a predetermined coercive force of 100 Oe or less, a binder, and a solvent on the protective coating layer 7. In the state where the solvent is still present, the magnetic powder in the magnetic paint gathers in the vicinity of the interface portions 17... Of the magnetization reversal by the magnetic recording performed on the first magnetic layer 11, and these portions become magnetic. Since it becomes a dense portion where the powder is gathered, the protrusion 16a as shown in FIG. 4 is formed corresponding to the magnetic recording contents of the first magnetic layer 11, and a kind of magnetic barcode pattern is formed.

Finally, a magnetic substrate of the magnetic transfer tape is formed by forming the adhesive layer 8 on the second magnetic layer 16. Then, the magnetic transfer tape 19 is obtained by cutting the magnetic material into a desired width. Next, the magnetic transfer tape 19 is adhered to the non-magnetic substrate 1, and then the holding substrate 10, the first magnetic layer 11, and the release layer 12 are peeled off as shown in FIG. A magnetic layer corresponding to the magnetic stripe 3 for fixed magnetic information shown in FIG. 1 and including the second magnetic layer 5 and the protective coating layer 9 can be formed. The formation of the normal magnetic recording magnetic stripe 2 'may be performed by the same means as the conventional magnetic card magnetic stripe forming method. When the magnetic stripe 2 'is formed, the magnetic recording medium B shown in FIG.
Can be obtained. The magnetic recording medium A can be manufactured by subjecting the magnetic recording medium A to a hot-press roll such as a hot roll process.

The magnetic recording medium of the present invention has at least one magnetic layer on a non-magnetic substrate, and the magnetic layer forms fixed information. However, in the magnetic recording media A and B of FIG. 2, the magnetic stripes 3 and 3 ′ for fixed magnetic information (corresponding to the second magnetic layer of FIGS. 3 and 4) are essential components of the present invention. Become. However, the magnetic stripes 3 and 3 'are layers for recording fixed magnetic information as described above. Therefore, when performing normal magnetic recording, it is necessary to separately form a magnetic recording layer having a coercive force of 250 to 5000 Oe on the same substrate. The magnetic recording layer for performing normal magnetic recording may be provided on the same surface as the magnetic stripes 3 and 3 'on the substrate, like the magnetic stripes 2 and 2' in FIG. 2, or provided on the opposite side. Is also good. The recording layer for performing normal magnetic recording may be provided in a stripe shape as shown in FIGS. 1 and 2, or may be provided on the entire surface of the base. Furthermore,
When ordinary magnetic recording is not performed, only the fixed magnetic information magnetic layer may be provided on the substrate. In this case, the magnetic recording information of the magnetic recording medium indicates fixed information of the magnetic layer, and the fixed information is used as read-only information.

In the magnetic recording media A and B, since the protrusions 5a are embedded in the adhesive layer 8 and face the base 1, the protrusions 5a. No irregularities appear on the surface side of the magnetic stripes 3, 3 '. Therefore, there is a feature that the presence of the protrusions 5a... And the bar-code-shaped magnetic pattern cannot be distinguished from the outside. Therefore, the magnetic recording media A and B having the above structure have magnetic pattern information that cannot be visually discriminated at all from the outside.

The protrusions 5a are formed so that the magnetic particles can move before the solvent evaporates when the magnetic paint for the second magnetic layer 5 is applied and dried. Since the magnetic particles cannot move after the solvent is volatilized and the magnetic particles are fixed, the magnetic information based on the density of the magnetic particles recorded in the second magnetic layer 5 is not available after the second magnetic layer 5 is formed. It becomes fixed information that cannot be written or erased.
The magnetic information of the second magnetic layer 5 can be freely selected by appropriately selecting a magnetic recording pattern to be formed on the magnetic layer 11 by a magnetic head during its manufacture. That is, the same information can be repeatedly formed as in the case of forming fixed information by a printing method, and random information that cannot be formed by a printing method can be formed. When random information is recorded, completely different individual information (fingerprint information and the like) can be added to each card in a magnetic recording medium that is a final product, for example, a magnetic card. That is, by using the fingerprint information as the ID information of the magnetic recording medium, forgery by copying the information of the magnetic recording medium to another magnetic recording medium becomes impossible. Therefore, it is possible to provide the magnetic recording media A and B which cannot be forged or altered.

In the above example, the first magnetic layer 1
1 is described as an example of in-plane magnetic recording.
Depending on the type of the magnetic layer, there may be a layer that can be perpendicularly magnetized.
1 may be subjected to magnetic recording by perpendicular magnetization, and fixed information may be given to the second magnetic layer 5 using the magnetic information due to the perpendicular magnetization.

Example 1 The present invention will be described in more detail with reference to the following examples. A paint for forming the first magnetic layer was prepared in the following mixing ratio. Barium ferrite (BaO · 6Fe ₂ O ₆ ) (coercive force 2750 Oersted Specific surface area 8 m ² / g) 100 parts by weight Carbon black 3 parts by weight Lecithin 1 part by weight Vinyl chloride / vinyl acetate / vinyl alcohol copolymer 20 parts by weight Polyurethane resin 20 parts by weight Toluene 60 parts by weight Methyl ethyl ketone 60 parts by weight Methyl isotyl ketone 60 parts by weight After the paint of the mixture having the above composition was dispersed by a ball mill for 8 hours, 5 parts by weight of a polyisocyanate-based curing agent was added and further dispersed for 1 hour. Was performed to obtain a magnetic paint for forming a first magnetic layer. The coating operation may be performed according to a normal method for manufacturing a magnetic recording medium. That is, a magnetic layer is applied to the protective layer by a gravure coater, and a magnetic field orientation treatment is performed before the coating is dried. Then, the coating is dried in a drying apparatus to form a magnetic layer having a thickness of 12 μm, and is wound as a raw material.

Next, a paint for forming a release layer was prepared in the following compounding ratio. Acrylic polyol resin 15 parts by weight Isocyanate curing agent 1 part by weight Silicon oil 1 part by weight Toluene 40 parts by weight Methyl ethyl ketone 40 parts by weight A coating material of the above-mentioned composition is applied on the first magnetic layer by a gravure coater, dried, and dried. A 1 μm release layer was formed.

Subsequently, a paint for a protective film was prepared in the following mixing ratio. Nitrocellulose resin 10 parts by weight Polyurethane resin 9 parts by weight Isocyanate curing agent 1 part by weight Toluene 40 parts by weight MEK 40 parts by weight Next, a coating for forming a protective film having the above composition is applied on the release layer by a gravure coater and dried. Let the thickness 1μm
Was formed.

Subsequently, a paint for forming the second magnetic layer was prepared with the following composition. Carbonyl iron powder (coercive force 40 Oersted Specific surface area 1 m ² / g) 100 parts by weight Carbon black 3 parts by weight Lecithin 1 part by weight Vinyl chloride / vinyl acetate / vinyl alcohol copolymer 20 parts by weight Polyurethane resin 20 parts by weight Toluene 60 parts by weight 60 parts by weight of methyl ethyl ketone 60 parts by weight of methyl isobutyl ketone The above mixture was dispersed by a ball mill for 8 hours, then 5 parts by weight of a polyisocyanate-based curing agent was added, and the mixture was further dispersed for 1 hour to obtain a magnetic coating material for forming a second magnetic layer. Was. This paint was applied on the protective layer using a gravure coater, and dried to form a second magnetic layer having a thickness of 6 μm.

However, before the coating material for the second magnetic layer is applied, that is, before the raw material on which the protective film layer has been formed reaches the gravure coating head for applying the second magnetic layer, the first magnetic layer is coated. Magnetic recording is previously performed on the layer using a magnetic head. This magnetic head has a head gap of 50 μm.
The recording was performed by applying a pulse current capable of sufficiently recording the first magnetic layer in saturation using a recording magnetic head of m. Because the web is eventually cut into magnetic tape,
Magnetic recording was performed by arranging recording magnetic heads in the width direction of the raw material so that magnetic recording could be performed on each magnetic tape. The magnetic recording was performed by the 100 bpi FM method, but a barcode pattern corresponding to the magnetic recording was formed on the second magnetic layer and fixed as fixed information as described later. As a result, a bar code pattern was formed and fixed on the second magnetic layer.

Finally, a paint for forming an adhesive layer was prepared according to the following formulation. 5 parts by weight of vinyl chloride / vinyl acetate copolymer resin 15 parts by weight of polyester resin 40 parts by weight of toluene 40 parts by weight of methyl ethyl ketone The above coating composition for adhesion is coated on the second magnetic layer with a gravure coater, and dried to obtain a thickness. A hot melt adhesive layer having a thickness of 10 μm was formed to obtain a magnetic substrate.

The magnetic raw material obtained in this way was 6.5
The resultant was cut into a tape having a width of mm to obtain a magnetic transfer tape. Using this magnetic transfer tape, a laminate of the second magnetic layer was thermally transferred to a vinyl chloride sheet having a thickness of 100 μm. That is, a 25 μm-thick polyester film as a holding
The magnetic layer and the release layer were peeled off, and a second magnetic layer having a magnetic stripe for fixed magnetic information was formed on a substrate made of a vinyl chloride sheet. In addition, in order to form a magnetic stripe for performing normal magnetic recording, a normal magnetic transfer tape is used to thermally transfer to another portion of the vinyl chloride sheet to form a magnetic layer, and a magnetic stripe for magnetic recording is formed. Was formed.

The thus obtained vinyl chloride sheet having a magnetic stripe for recording fixed information and ordinary magnetic recording, a vinyl chloride plate for a center core having a thickness of 560 μm, and a vinyl chloride sheet for an oversheet having a thickness of 100 μm The sheets are overlaid, heated and compressed to a thickness of 760 μm, and then punched out in a card shape.
Magnetic recording medium (card) with IS standard magnetic stripe
I got

Subsequently, the following evaluation test was performed on the above-mentioned card. 1 in the magnetic stripe for fixed magnetic information
When reading was performed with a reproducing magnetic head while applying a bias magnetic field of kG, a reproduced signal in a barcode-like pattern fixed to the second magnetic layer could be read. This information corresponded to the magnetic recording information performed on the high coercivity magnetic layer used before applying the second magnetic layer. Also, this information could not be added or deleted later. Next, using a recording magnetic head, normal magnetic recording was performed at a recording current capable of sufficiently saturation recording the magnetic layer of the magnetic stripe for magnetic recording, and reading was performed with a reproducing magnetic head. The information could be read without problems.

[0039]

As described above, according to the present invention, a magnetic layer having a coercive force of 100 Oe or less is laminated on a non-magnetic substrate, and this magnetic layer has a specific density within the magnetic layer. the magnetic particles were dispersed densely to set the magnetic particles in the magnetic layer and by forming a protrusion protruding to the substrate side, was recorded magnetic bar code pattern of the fixed information of the write and erasable magnetic layer Will be. Therefore, it is possible to easily identify the magnetic recording medium by using the fixed information, and it is possible to prevent unauthorized use of the magnetic recording medium, such as forgery or falsification. Furthermore, when the protrusion formed on the magnetic layer is directed toward the base, the presence thereof cannot be confirmed by visual observation from the outside, which is advantageous in preventing unauthorized use. In addition, the magnetic layer
Bar-shaped due to the protrusions formed by the compaction of conductive particles
By forming a pattern, the pattern can be easily identified
To prevent forgery and tampering.
You.

Next, according to the method of the present invention, a second magnetic layer having a coercive force of 100 Oe or less is formed on the first magnetic layer having a coercive force of 250 to 5000 Oe upon which magnetic recording has been performed. Fixed information corresponding to the magnetic information of the layer can be provided to the second magnetic layer. That is, when forming the second magnetic layer on the first magnetic layer, if the magnetic paint for the second magnetic layer containing the magnetic particles, the binder and the solvent is applied on the first magnetic layer, the solvent is volatilized. Previously, the magnetic particles of the second magnetic layer in the binder form light and shade in a state in accordance with the magnetic information of the first magnetic layer, disperse and assemble, and the dense portion of the magnetic particles
Since a protrusion is formed in the minute, the solvent is volatilized
By drying the binder, the protrusions due to the density of these magnetic particles can be fixed.
There is formed a stationary magnetic information of the second magnetic layer. In addition, 250
Since 5000 the magnetic information to be written to the first magnetic layer Oersted coercivity can be arbitrarily changed by using the magnetic recording element such as a magnetic head, dense magnetic particles forming the second magnetic layer
Any fixed magnetic information consisting of projecting portions can be selected. Therefore, for example, fixed magnetic information unique to each magnetic recording medium can be recorded. Further, the method of the present invention can be carried out only by adding a simple magnetic recording device to a conventionally used device for manufacturing a magnetic recording medium, so that no special device or technique is required. It is characterized by high productivity and low cost.

[Brief description of the drawings]

FIG. 1 is a front view showing an example of a magnetic recording medium according to the present invention.

2A is a cross-sectional view of the magnetic recording medium shown in FIG. 1 taken along the line YY ′, and FIG. 2B is a cross-sectional view showing another structural example.

FIG. 3 is an enlarged cross-sectional view of the magnetic recording medium shown in FIG. 1, taken along line XX '.

FIG. 4 is a cross-sectional view for describing an example of a method for manufacturing a magnetic recording medium.

[Explanation of symbols]

 A, B magnetic recording medium, 1 base, 2 normal magnetic recording magnetic stripe, 3 fixed magnetic information magnetic stripe, 4, 8 adhesive layer, 5 second magnetic layer, 6 magnetic layer, 7, 9 protective coating layer, Reference Signs List 10 holding base material, 11 first magnetic layer, 12 release layer, 16 second magnetic layer, 17 interface, 18 adhesive layer, 19 magnetic transfer tape.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ Identification code FI G11B 5/842 G06K 19/00 B (56) References JP-A-4-3283 (JP, A) JP-A-2-302930 ( JP, A) JP-A-7-121864 (JP, A) JP-A-6-20264 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G11B 5/70 B42D 15/10 501 G06K 19/06 G11B 5/80 G11B 5/842

Claims (3)

(57) [Claims] 1. A magnetic recording medium comprising at least one magnetic layer formed on a nonmagnetic substrate, wherein the magnetic layer has a coercive force of 100 Oe or less, and is dispersed in the binder. It has a large number of magnetic particles , and the magnetic particles are specified in the binder of the magnetic layer.
Distribution in high and low magnetic particles
A magnetic recording medium characterized in that a protrusion formed by the concentration of particles is formed to protrude toward the substrate , thereby forming fixed information that cannot be written or erased. 2. A projection formed by densely packed magnetic particles.
2. The magnetic recording medium according to claim 1 , wherein a bar-code-like pattern is formed . 3. A non-magnetic holding base material having a thickness of 250 to 5,000
Forming a first magnetic layer having a Rousted coercive force;
Magnetic recording is performed on the first magnetic layer of the lever, and then the first magnetic layer is
Has a coercive force of 250-5000 Oersted on the conductive layer
The magnetic paint for the second magnetic layer was applied to bring about shading on the distribution of magnetic particles in a binder according to the strength of the first magnetic field magnetic layer generates a magnetic comprising magnetic particles and a binder and a solvent that Due to the concentration of magnetic particles in the high particle concentration area
Formed protrusions, and then the solvent evaporates
The binder is dried to fix the magnetic particles in the second magnetic layer in a specific density state, whereby the first magnetic layer is fixed to the second magnetic layer.
Fixed information corresponding to the magnetic information of the magnetic layer is added, and
2Make a magnetic transfer tape by forming an adhesive layer on the magnetic layer
Then, using this magnetic transfer tape,
And transferring only the second magnetic layer to the magnetic recording medium.