JP2000268346A - Magnetic recording medium and production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic recording medium, in which two types of non-rewritable fixed information, i.e., a digital data and analog variation of the entire waveform of output, can be read out from on an identical track through a magnetic head, and a production method thereof. SOLUTION: The magnetic recording medium has first and second magnetic layers laminated sequentially on a basic material wherein the second magnetic layer contains a magnetic material in a specified sparse/dense pattern along a specified direction and the sparse/dense pattern includes a dense part having density of magnetic material varying along the specified direction. The magnetic recording medium is produced by forming a first magnetic layer on a basic material, performing desired magnetic recording on the first magnetic layer, subjecting a magnetic coating formed by applying a magnetic paint onto the first magnetic layer to magnetic orientation by applying a bias field along the specified direction while varying the strength, and then drying the magnetic coating to form a second magnetic layer having fixed information in a space/ dense pattern of a magnetic material, thereby forming a magnetic recording comprising first and second magnetic layers.

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, and more particularly to a magnetic recording medium which is difficult to forge and alter, and a method for manufacturing the same.

[0002]

2. Description of the Related Art A magnetic recording medium in which a magnetic recording layer is formed in an entire area on one side or both sides of a substrate or in a stripe shape is provided.
For example, prepaid cards, commuter passes, tickets, admission tickets,
It is widely used as vouchers, securities, such as car tickets, betting tickets, gift certificates, stock certificates, certificates, passbooks, magnetic tags, etc., cards such as ID cards, cash cards, credit cards, membership cards, and magnetic labels. Conventionally, such a magnetic recording medium writes information on a magnetic recording layer at a high recording density,
The recorded information cannot be easily read from outside.

[0003] However, due to the characteristics of the magnetic recording layer, the recorded information can be freely rewritten and erased, so that forgery and falsification are possible. In recent years, it has been highlighted as a major social problem. In particular, since it is now easy to obtain a magnetic stripe, it is possible to manufacture a similar card, and if the magnetic recording layer is exposed on the surface of the magnetic recording medium as in the current specification. There is also a problem that magnetic recording information can be easily read or magnetic recording information can be easily transferred to another magnetic recording layer by a magnetic transfer technique.

[0004] In order to solve the problem based on the essential drawback of the reversibility of magnetically recorded information, various methods for making it difficult to rewrite magnetically recorded information have been proposed. For example, by using a high coercive force magnetic material such as Ba ferrite or Sr ferrite, a high coercive force and low Curie point (high Hc and low Tc) magnetic material, or a magnetic material containing MnBi, magnetic information that is difficult to erase magnetic information is used. Media etc. are being developed.

Further, a magnetic recording medium has been developed in which magnetic recording information is provided by giving a physical change to a magnetic layer so that magnetic rewriting becomes impossible. For example, a magnetic recording medium provided with a magnetic barcode by printing,
Examples include a magnetic recording medium in which marking is performed on a magnetic layer with a laser or the like.

Further, a first magnetic layer containing a magnetic material having a relatively low coercive force is formed on a base material, and after performing magnetic recording on the first magnetic layer, a second magnetic layer containing a magnetic material having a high coercive force is formed. Magnetic recording media in which layers are applied and laminated are also being developed. In this magnetic recording medium, since the magnetic recording pattern of the first magnetic layer is copied (so-called magnetic transfer) to the second magnetic layer, it is difficult to rewrite with a magnetic head for forgery or falsification.

[0007]

However, a magnetic recording medium using only a high coercivity magnetic material as described above is
Although it is possible to prevent the erasure of magnetically recorded information due to the influence of an external magnetic field, it is difficult to magnetize when writing information with a magnetic head, which causes a new problem that the writing device can be limited. .

Further, in a magnetic recording medium having a high Hc / low Tc magnetic material or a MnBi-containing magnetic material, it is possible to perform magnetic writing under the condition by utilizing a sudden decrease in coercive force due to temperature. Since erasing and writing of magnetically recorded information cannot be performed at room temperature, there is a problem that the device becomes large-scale.

Further, in a magnetic recording medium in which a magnetic layer is physically changed like a magnetic bar code, erasing of magnetic recording information and writing of new information are impossible.

Further, a magnetic recording medium having magnetic recording information magnetically transferred to the second magnetic layer has a problem that when a very strong magnetic field is applied, the magnetic recording of the second magnetic layer by the magnetic transfer is erased. In addition, since it is difficult to efficiently perform magnetic transfer to the second magnetic layer containing a high coercive force magnetic material, there is a problem that a magnetic output required for reading cannot be obtained from the second magnetic layer.

The present invention has been made in view of such circumstances, and two types of non-rewritable fixed information, digital data and an analog change of the entire output waveform, are identical by reading with a magnetic head. It is an object of the present invention to provide a magnetic recording medium obtainable from a track and a method for manufacturing such a magnetic recording medium.

[0012]

In order to achieve the above object, a magnetic recording medium of the present invention has a base material and a magnetic recording layer on the base material, and the magnetic recording layer has a base material. A first magnetic layer and a second magnetic layer laminated in order from the material side, wherein the second magnetic layer contains a magnetic material in a predetermined dense / dense pattern along a predetermined direction; In the above, the content density of the magnetic material was changed along the predetermined direction.

Further, the magnetic recording medium of the present invention comprises:
A magnetic recording layer on the base material, wherein the magnetic recording layer is formed by laminating a first magnetic layer and a second magnetic layer in order from the base material side, and the second magnetic layer is made of a magnetic material. Sites containing a predetermined density pattern are arranged at predetermined intervals along a predetermined direction,
In each part, the density of the magnetic material in the dense portion of the dense / dense pattern is changed along the predetermined direction.

Further, the magnetic recording medium of the present invention has a structure in which two or more types of dense portions of a magnetic material exist in the dense / dense pattern, and a magnetic shield between the first magnetic layer and the second magnetic layer. It was configured to have a layer.

According to the method of manufacturing a magnetic recording medium of the present invention, a first magnetic layer is formed on a base material, desired magnetic recording is performed on the first magnetic layer in a predetermined direction, and then the first magnetic layer is formed. A magnetic paint is applied on the layer, and a magnetic field is applied by applying a bias magnetic field along the predetermined direction while changing the strength of the magnetic coating, and then the magnetic coating is dried, and the magnetic coating is dried. A second magnetic layer having fixed information composed of a dense / dense pattern of a magnetic material corresponding to a magnetic recording pattern of one magnetic layer is formed, and a magnetic recording layer composed of the first magnetic layer and the second magnetic layer is formed. Configuration.

Further, according to the method of manufacturing a magnetic recording medium of the present invention, a first magnetic layer is formed on a base material, and a desired write current of a magnetic head is changed in the first magnetic layer along a predetermined direction. After performing magnetic recording, a magnetic paint is applied on the first magnetic layer, and a magnetic field is applied by applying a bias magnetic field to the magnetic coating along the predetermined direction. After the application, the magnetic coating film is dried to form a second magnetic layer having fixed information composed of a dense / dense pattern of a magnetic material corresponding to the magnetic recording pattern of the first magnetic layer. And a configuration in which a magnetic recording layer composed of the second magnetic layer is formed.

Further, in the method of manufacturing a magnetic recording medium according to the present invention, in the magnetic recording on the first magnetic layer, the structure may be such that a writing density is changed, and after forming a magnetic shield layer on the first magnetic layer. And the second magnetic layer is formed.

In the present invention as described above, the fixed information composed of the dense / dense pattern of the magnetic material recorded on the second magnetic layer is:
It has digital data that cannot be rewritten by a sparse / dense pattern, and by adding information to the analog change of the entire waveform of the output when the sparse / dense pattern is read by a magnetic head, two fixed information that cannot be rewritten are placed on the same track. Can be obtained from

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. Magnetic Recording Medium FIG. 1 is a perspective view of a card-shaped magnetic recording medium for explaining an embodiment of the magnetic recording medium of the present invention, and FIG. 2 is a sectional view taken along the line AA of FIG.

1 and 2, a magnetic recording medium 1 of the present invention includes a base material 2 and a magnetic recording layer 3 provided on one surface of the base material 2. The first magnetic layer 3a and the second magnetic layer 3b are stacked. On the magnetic recording layer 3, fixed information areas 4 are set in a stripe shape along the reading direction (the direction of arrow a in FIG. 1) by the magnetic head. And the second magnetic layer 3b
The fixed information area 4 has fixed information composed of a sparse and dense pattern of a magnetic material.

Base material 2 constituting magnetic recording medium 1 of the present invention
Considering heat resistance, strength, rigidity, etc. required as a base material, polyester such as PET, PET-G, PEN,
Resin such as vinyl chloride, polycarbonate, polyethylene, polypropylene, polystyrene, polylactic acid, etc., biodegradable resin, metals such as copper and aluminum, paper, impregnated paper, synthetic paper, etc. Or a composite. The thickness of the substrate 2 is 100 μm to 1 mm, preferably 1 μm.
It can be about 50 to 250 μm.

The first magnetic layer 3a constituting the magnetic recording layer 3 contains a magnetic material having a coercive force in the range of 300 to 6000 Oe. The coercive force of this magnetic material is 300 Oe
If less than, the resistance to the external magnetic field is insufficient,
If it exceeds 6000 Oe, stable recording by the magnetic head becomes difficult, which is not preferable. If the recording by the magnetic head can be performed stably, a magnetic material having a coercive force exceeding 6000 Oe can be used.

Examples of the magnetic material constituting the first magnetic layer 3a having a coercive force in the range of 300 to 6000 Oe include γ-Fe ₂ O ₃ and γ-Fe ₂ O coated with Co.
_{3, Fe 3 O 4, CrO} 2, Fe, Co, Ni, Fe-
Co, Co-Ni, Fe-Ni, Ba ferrite, Sr
Magnetic fine particles such as ferrite are exemplified.

The first magnetic layer 3a is coated with a magnetic paint obtained by dispersing the above magnetic fine particles in an appropriate resin or ink vehicle according to a known coating method such as a gravure method, a roll method, or a knife edge method. It can be formed by drying. Also, using the above magnetic material,
First by vacuum deposition, sputtering, plating, etc.
The magnetic layer 3a can also be formed.

When the first magnetic layer 3a is formed by a coating method, the thickness after drying is 1 to 50 μm,
Preferably it is about 3 to 20 μm. This first magnetic layer 3
In a, desired magnetic information is recorded along the direction of arrow a before the formation of the second magnetic layer 3b.

The magnetic material contained in the second magnetic layer 3b constituting the magnetic recording layer 3 is, for example, Al, S
i, magnetic alloy material composed of Fe, etc., permalloy, sendust, Mn-Zn ferrite, Co-Zn ferrite,
Ferrite such as Ni-Zn ferrite, γ-Fe ₂ O
₃ , iron oxides such as Co-coated γ-Fe ₂ O ₃ and Fe ₃ O ₄ , Fe, Co, Ni, Fe—Cr, Fe—Co, Fe
-Ni, Co-Cr, Co- Ni, CrO 2, Ba ferrite, the coercive force, such as Sr ferrite 1~10000O
e, a magnetic material having a coercive force of 1
Magnetic materials exceeding 0000 Oe can also be used.

The second magnetic layer 3b is formed by applying a magnetic coating material obtained by dispersing the above magnetic material in an appropriate resin or ink vehicle on the first magnetic layer 3a on which desired magnetic recording has been performed, by a gravure method or a roll method. Method, a knife-edge method, etc., and applying a bias magnetic field while changing the strength along the direction of arrow a to perform a magnetic orientation treatment on the magnetic coating, and then drying the magnetic coating. Can be formed. The thickness of the second magnetic layer 3b is about 1 to 50 μm, preferably about 3 to 20 μm after drying. Note that a magnetic head is preferably used for the alignment treatment.

The second magnetic layer 3b contains a magnetic material in the fixed information area 4 in a predetermined dense / dense pattern along the direction of arrow a, and the dense / dense pattern is dense along the direction of arrow a. The density of the magnetic material in the portion changes. FIG. 3 is a diagram illustrating an example of such a sparse / dense pattern. In FIG. 3, the dense portion of the dense / dense pattern includes four types of dense portions 5 a, 5 b, 5 c, and 5 d in order from the one having the lowest magnetic material content density. In the direction of arrow a. The portion where the dense portion 5a with the lowest magnetic material content density is present corresponds to the portion where the intensity of the applied bias magnetic field is the lowest in the above-described magnetic orientation treatment, and the dense portion 5d with the highest content density is the same. The existing portion corresponds to a portion where the intensity of the applied bias magnetic field is the highest. However, when the intensity of the bias magnetic field is about half the coercive force of the first magnetic layer 3a, both the magnetic field intensity and the content density (reproduction output) of the magnetic material tend to increase. Since the magnetization of the magnetic layer 3a is lost and the density (reproduction output) of the magnetic material decreases, it is necessary to set the strength of the bias magnetic field in consideration of this.

In FIG. 3 and the following description, for easy understanding, the density of the magnetic material in the dense portion is set to four types for convenience. Depending on the change, the density of the magnetic material in the dense portion varies.

In the magnetic recording medium 1 of the present invention having the above-described structure, when the magnetic recording layer 3 reproduces the data on the fixed information area 4 in the direction of arrow a, as shown in FIG. The output waveform is a undulating waveform. FIG. 4 (B)
4A is an enlarged view of a part of the output waveform of FIG. 4A. Of the four types of dense portions 5a, 5b, 5c, and 5d, the denser portion having a higher magnetic material content density has higher output, The reproduction output changes according to the change in the material density.

According to the present invention, the above-mentioned undulating output waveform can be controlled to a desired shape by adjusting the intensity change of the bias magnetic field when the second magnetic layer is formed. By imparting information to analog changes in the entire waveform, fixed information that cannot be rewritten can be obtained. Therefore, in the magnetic recording medium 1 of the present invention, the above-mentioned analog fixed information can be obtained from the same fixed information area 4 in addition to the digital data based on the dense / dense pattern of the magnetic material. Moreover, the fixed information in the second magnetic layer 3b can be arbitrarily set for each magnetic recording medium by magnetic recording on the first magnetic layer 3a or by controlling the change in the intensity of the bias magnetic field.

In the magnetic recording medium 1 of the present invention,
Although the magnetic recording layer 3 is formed on the entire surface of the base material 2, the magnetic recording layer 3 may be formed in a part of the magnetic recording layer 3.

Further, as another embodiment of the magnetic recording medium 1 of the present invention, the following is possible. In the example of the magnetic recording medium 1 described above, the dense / dense pattern is continuous in the fixed information area 4, but the pattern is not limited thereto.
As shown in (1), there may be a portion 7 where no dense / dense pattern exists (a portion where no output is obtained) in the fixed information area 4. Further, in the example of the magnetic recording medium 1 described above, the four types of dense portions 5a, 5b, 5c, and
Although the recording density of the dense / dense pattern composed of 5d is constant,
As shown in FIG. 6, a mode in which the recording density changes (the interval between dense portions of the magnetic material is two or more) may be used. All of these aspects are made possible by the presence or absence of magnetic recording on the first magnetic layer 3a and the change in recording density in the manufacturing method of the present invention described later.

The magnetic recording medium of the present invention may have a magnetic shield layer provided between the first magnetic layer 3a and the second magnetic layer 3b. This magnetic shield layer can be formed by a coating method, a vacuum film forming method, or the like using a magnetic material having a high magnetic permeability such as Sendust or Permalloy as a magnetic material. The thickness of the magnetic shield layer is
In the case of a coating method, the thickness can be about 3 to 20 μm.

When the magnetic shield layer is provided as described above, in the dense / dense pattern of the magnetic material, for example, of the four types of dense portions 5a, 5b, 5c, and 5d having different contents densities of the magnetic material, for example, the contents density is the highest. The three types of dense portions 5b, 5b, 5d,
Only c and 5d will be present. Then, as shown in FIG. 7, in the reproduction output by the magnetic head, a part where no output is obtained appears, and in a part where the reproduction output is obtained, the waveform has an undulating waveform. This is because the bias magnetic field applied at the time of forming the second magnetic layer 3b does not reach the strength required to saturate the magnetic shield layer (when the magnetic shield layer is not present, the density of the magnetic material is the lowest. This is because the influence of the magnetization of the first magnetic layer 3a does not reach the second magnetic layer 3b due to the presence of the magnetic shield layer at the portion where the dense portion 5a is formed.

In the present invention, on the magnetic recording layer 3 of the magnetic recording medium 1, a protective layer, a colored layer and a picture for providing protection, hiding and decoration effects may be provided. The protective layer, the colored layer and the pattern are made of ethyl cellulose, cellulose nitrate, ethyl hydroxyethyl cellulose, cellulose acetate propionate, cellulose derivatives such as cellulose acetate, polystyrene, styrene resin such as poly-α-methylstyrene, or styrene copolymer resin, polystyrene. Acrylic resin such as methyl methacrylate, polyethyl methacrylate, polyethyl acrylate, polybutyl acrylate, etc., homopolymer or copolymer resin, rosin, rosin modified maleic resin, rosin modified phenol resin, rosin such as polymerized rosin Ester resin, polyvinyl acetate resin,
Coumarone resin, vinyl toluene resin, vinyl chloride resin,
Add various pigments to binders such as polyester resin, polyurethane resin and butyral resin according to the color to be colored, and use titanium oxide, alumina powder, micro silica, etc. Add, and if necessary, add a plasticizer, stabilizer, wax, grease, desiccant, drying aid, hardener, thickener, dispersant, and then knead well with a solvent or diluent. It can be formed on a desired portion by using a coloring paint or ink by a usual coating method such as a gravure method, a roll method, a knife edge method, and an offset method or a printing method.

Next, another embodiment of the magnetic recording medium of the present invention will be described. FIG. 8 is a perspective view of a card-shaped magnetic recording medium for explaining another embodiment of the magnetic recording medium of the present invention, and FIG. 9 is a sectional view taken along the line BB of FIG.

8 and 9, the magnetic recording medium 11 of the present invention comprises a base material 12 and a magnetic recording layer 13 provided on the base material 12 in a stripe shape. The first magnetic layer 13a and the second magnetic layer 13b are stacked. The second magnetic layer 13b of the magnetic recording layer 13 has fixed information composed of a dense / dense pattern of a magnetic material along a reading direction (the direction of the arrow a in FIG. 8) by the magnetic head.

The base material 12 constituting the magnetic recording medium 11 of the present invention can be the same as the base material 2 constituting the above-described magnetic recording medium 1, and the description is omitted here.

The first magnetic layer 13a constituting the magnetic recording layer 13 is the first magnetic layer 13a constituting the magnetic recording layer 3.
The first magnetic layer 1a may be similar to the magnetic layer 3a.
Before forming the second magnetic layer 13b, desired magnetic information is recorded in 3a while changing the write current of the magnetic head along the direction of arrow a.

The second magnetic layer 13b of the magnetic recording layer 13 can be the same as the second magnetic layer 3b of the magnetic recording layer 3. However, the second magnetic layer 13b is formed by dispersing the above-mentioned magnetic material in an appropriate resin or ink vehicle on the first magnetic layer 13a on which magnetic recording has been performed while changing the write current of the magnetic head. By applying a paint and applying a bias magnetic field uniformly to the magnetic coating in the direction of arrow a to perform the magnetic alignment processing, or after performing the magnetic alignment processing, the magnetic coating is dried. Form. In such a second magnetic layer 13b, portions containing a magnetic material in a predetermined dense / dense pattern along the direction of the arrow a are arranged along the predetermined direction at desired intervals, and the magnetic material in the dense portion of the dense / dense pattern is formed at each portion. The content density of the material changes along the direction of arrow a.

FIG. 10 is a diagram showing an example of such a sparse / dense pattern. In FIG. 10, the dense / dense pattern portion 1
4 are arranged at a desired interval along the direction of arrow a. As dense portions of the dense / dense pattern portion 14, four types of dense portions 15a are arranged in ascending order of the magnetic material content density,
There are 15b, 15c and 15d, and these dense portions are arranged in the desired direction via the sparse portion 16 in the direction of arrow a. Such a dense / dense pattern portion 14 corresponds to a portion where magnetic recording has been performed under a condition of a predetermined write current value (minimum current value) or more capable of magnetic recording on the first magnetic layer. The location where the dense portion 15a where the content density of the magnetic material is the lowest corresponds to the location where the writing is performed at the minimum current value, and as the writing current value increases and shifts to the saturation current value side. The dense portions 15b, 15c, and 15d having a higher density of the magnetic material are formed.
Note that the number and density of the dense portions forming each dense / dense pattern portion 14 may be constant, or may be different for each individual dense / dense pattern portion 14.

In FIG. 10 and the following description, for easy understanding, the density of the magnetic material in the dense portion is set to four types for the sake of convenience. The density of the magnetic material in the dense portion varies depending on the change in the write current.

In the magnetic recording medium 11 of the present invention having such a structure, when the magnetic recording layer 13 is reproduced by the magnetic head in the direction of arrow a, as shown in FIG. And a portion that cannot be obtained appears, and a portion having a reproduced output has a undulating waveform. FIG. 11 (B)
FIG. 11A is an enlarged view of a part of the output waveform of FIG. 11A, and an output is obtained at a portion where the dense / dense pattern portion 14 of the magnetic material exists. Then, in one dense / dense pattern portion 14, four types of dense portions 15a, 15b, 15c, 1
Of 5d, a dense portion having a higher magnetic material content density indicates a higher output, and the reproduction output changes in accordance with a change in the magnetic material content density.

In the present invention, by adjusting the write current during magnetic recording on the first magnetic layer 13a, it is possible to control the analog change of the output obtained from the dense / dense pattern portion to provide information. is there. Thus, in the magnetic recording medium 11 of the present invention, the above-mentioned analog fixed information can be obtained from the same track of the magnetic recording layer 13 in addition to the digital data based on the dense / dense pattern of the magnetic material. Moreover, the fixed information in the second magnetic layer 13b can be arbitrarily set for each magnetic recording medium by controlling the write current for magnetic recording on the first magnetic layer 13a.

The magnetic recording medium 11 according to the present invention has a configuration in which the magnetic recording layer 13 in the form of a stripe is formed on the substrate 12, but the magnetic recording layer 13 is formed on the entire surface of the substrate 12. The formed structure may be used.

Further, as another embodiment of the magnetic recording medium 11 of the present invention, the following is possible. In the example of the magnetic recording medium 11 described above, the dense / dense pattern portion 1 of the magnetic material is used.
4, the recording density of the dense portion 15 is constant.
As shown in FIG. 2, a mode in which the recording density changes (the interval between the dense portions of the magnetic material is two or more) may be used. Such an aspect is made possible by a change in the recording density on the first magnetic layer 13a in the manufacturing method of the present invention described later.

In the magnetic recording medium 11 of the present invention, the above-described magnetic shield layer may be provided between the first magnetic layer 13a and the second magnetic layer 13b.

Further, the magnetic recording layer 1 of the magnetic recording medium 11
3 may be provided with a protective layer, a colored layer, and a pattern for providing protection, hiding, and decorative effects on the entire surface.

The method of manufacturing a magnetic recording medium Next, an embodiment of a method for manufacturing a magnetic recording medium of the present invention, the magnetic recording medium 1 described above will be described with reference to FIG. 13 as an example.

First, the first magnetic layer 3a is formed on the substrate 2,
Desired magnetic recording is performed on the first magnetic layer 3a (FIG. 13).
(A)). Thereby, magnetic patterns having different magnetization directions are formed over the entire area of the first magnetic layer 3a in the predetermined direction.

The first magnetic layer 3a is formed by applying a magnetic coating material obtained by dispersing a magnetic material having a coercive force in the range of 300 to 6000 Oe in a suitable resin or ink vehicle by a gravure method, a roll method, a knife method, or the like. It can be formed by coating and drying according to a known coating method such as an edge method. As the resin or ink vehicle, butyral resin, vinyl chloride / vinyl acetate copolymer resin,
A urethane resin, a polyester resin, a cellulose resin, an acrylic resin, a styrene / maleic acid copolymer resin or the like is used, and a rubber-based resin such as a nitrile rubber or a urethane elastomer is added as necessary. Further, in consideration of heat resistance, a resin having a high glass transition temperature (Tg) such as polyamide, polyimide, or polyethersulfone, or a system in which Tg increases by a curing reaction can be used. If necessary, a dispersing agent, a plasticizer, a curing agent, an antistatic agent, a pigment, and the like may be appropriately contained in the magnetic paint in which the magnetic material is dispersed in the resin or the ink vehicle as described above. The first magnetic layer 3a can also be formed by using the above-mentioned magnetic material by a vacuum deposition method, a sputtering method, a plating method, or the like.

Next, a second magnetic layer 3b is formed. First,
A magnetic coating material in which the above-described magnetic material is dispersed in an appropriate resin or ink vehicle is coated on the first magnetic layer 3a on which desired magnetic recording has been performed by a known method such as a gravure method, a roll method, or a knife edge method. The coating is performed according to the coating method to form the magnetic coating 3′b. As the resin or ink vehicle used for the magnetic paint, those mentioned in the formation of the first magnetic layer 3a can be used, and if necessary, a dispersant, a plasticizer, a curing agent, an antistatic agent, A pigment or the like may be appropriately contained in the magnetic paint. Then, a bias magnetic field is applied in a fixed direction along the same direction as the recording direction of the first magnetic layer 3a, and the magnetic coating 3'b is subjected to a magnetic orientation treatment (FIG. 3).
(B)).

The above-mentioned magnetic orientation treatment can be performed by scanning the magnetic head on the back surface side of the substrate 2 and changing the intensity of the magnetic field generated from the magnetic head. The intensity range of the applied bias magnetic field is, for example, 150 to 30.
In the range of 00G, it can be appropriately set according to the magnetic material used so that the magnetic recording of the first magnetic layer 3a is not erased. In the illustrated example, the change in the intensity of the bias magnetic field is schematically shown by a chain line for easy understanding.

By this magnetic orientation treatment, the first magnetic layer 3a
The magnetic material moves and gathers at a position where the direction of the bias magnetic field coincides with the direction of magnetization existing in the magnetic coating film 3'b due to the lines of magnetic force generated from the magnetic field. It corresponds to the strength of.

Thereafter, by drying the magnetic coating 3'b, a dense / dense pattern (magnetic material) of a magnetic material corresponding to the magnetic recording pattern of the first magnetic layer 3a and corresponding to the intensity of the applied bias magnetic field is applied. The second magnetic layer 3b having fixed information composed of four types of dense portions 5a, 5b, 5c, and 5d is formed in ascending order of the content density (FIG. 1).
3 (C)).

Next, a bias magnetic field for erasing the magnetic recording of the first magnetic layer 3a is applied in a certain direction to erase the magnetic recording of the first magnetic layer 3a and to erase the magnetic recording of the first magnetic layer 3b.
The fixed information is magnetized to obtain the magnetic recording medium 1 (FIG. 13D). Note that the direction of the bias magnetic field is the same as the direction of the bias magnetic field in the above magnetic alignment processing.
Conversely, either may be used.

In the magnetic recording medium 1 of the present invention manufactured as described above, the fixed information in the second magnetic layer 3b of the magnetic recording layer 3 is formed by moving the magnetic material through the undried magnetic coating film. Because of the dense and dense pattern, it is not erased even when a strong magnetic field is applied. Then, the magnetic output waveform when read by the magnetic head is an output waveform in which the reproduction output changes and undulates. This output waveform corresponds to the second magnetic layer 3
Control is possible by adjusting the intensity change of the bias magnetic field at the time of forming b. The fixed information in the second magnetic layer 3b can be arbitrarily set for each magnetic recording medium by magnetic recording on the first magnetic layer 3a.

Incidentally, a resin film such as a polyethylene terephthalate film is used as a base material, and a first magnetic layer and a second magnetic layer are sequentially laminated on the base material by the above-described manufacturing method to form a magnetic recording layer. The magnetic recording medium may be manufactured by preparing a magnetic tape by providing the magnetic tape and bonding the magnetic tape to the entire surface or a part of a card base material or the like.

Next, another embodiment of the method for manufacturing a magnetic recording medium according to the present invention will be described with reference to FIG. 14 using the above-described magnetic recording medium 11 as an example. First, a striped first magnetic layer 13a is formed on the base material 12, and desired magnetic recording is performed on the first magnetic layer 13a while changing the write current of the magnetic head (FIG. 14A).

In such magnetic recording on the first magnetic layer 13a, under the condition that a current equal to or more than a predetermined write current value (minimum current value) capable of magnetic recording on the first magnetic layer 13a is applied to the magnetic head. Magnetic recording is performed in the area where the writing has been performed. Then, in the recorded area, a magnetic pattern having a different magnetization direction is formed, and the magnetic field intensity generated from this magnetic pattern changes corresponding to the change in the write current intensity. In the illustrated example, a change in current with respect to the above-described minimum current value is schematically indicated by a dashed line for easy understanding.

The first magnetic layer 13a is formed by applying a magnetic coating material obtained by dispersing a magnetic material having a coercive force in the range of 300 to 6000 Oe in an appropriate resin or ink vehicle by a gravure method, a roll method, or the like. It can be formed by coating and drying according to a known coating method such as a knife edge method. As the resin or the ink vehicle, the materials mentioned in the above-mentioned production method can be used. Further, the first magnetic layer 13a can also be formed by a vacuum evaporation method, a sputtering method, a plating method, or the like.

Next, a second magnetic layer 13b is formed. First, a magnetic coating material in which the above-described magnetic material is dispersed in an appropriate resin or ink vehicle is coated on the first magnetic layer 13a on which desired magnetic recording has been performed by a gravure method, a roll method,
Apply according to a known application method such as a knife edge method,
A magnetic coating 13'b is formed. Then, the first magnetic layer 13
A magnetic field is applied to the magnetic coating 13'b by uniformly applying a bias magnetic field in the same direction as the recording direction a (FIG. 13B). As the resin or ink vehicle used for the magnetic paint, those mentioned in the formation of the first magnetic layer 13a can be used, and if necessary, a dispersant,
A plasticizer, a curing agent, an antistatic agent, a pigment and the like may be appropriately contained in the magnetic paint.

The above-described magnetic orientation treatment can be performed by a magnetic head from the back side of the substrate 12, or a solenoid type electromagnet orientation device may be used. The applied bias magnetic field is in the range of 150 to 3000 G,
It can be set appropriately according to the magnetic material used so that the magnetic recording of a is not erased.

By this magnetic orientation treatment, the first magnetic layer 13
In the portion where the magnetic recording has been performed, the magnetic material moves to a portion where the direction of the bias magnetic field and the direction of magnetization existing in the magnetic coating film 13'b coincide with the lines of magnetic force generated from the first magnetic layer 13a. To form a dense portion of the magnetic material in the magnetic coating film 13'b. Moreover, this dense portion corresponds to the magnetic field intensity generated from the magnetic pattern recorded on the first magnetic layer 13a, and therefore, the first magnetic layer 13a
This corresponds to the current intensity at the time of writing to a.

The magnetic coating 13′b is dried while performing the magnetic alignment treatment or after the magnetic alignment treatment is performed, so that the density of the magnetic material corresponding to the magnetic recording pattern of the first magnetic layer 13a is reduced. Patterns (four types of dense portions 15a, 15b, 15
c and 15d are present).
The magnetic layer 13b is formed (FIG. 14C).

Next, a bias magnetic field for erasing the magnetic recording of the first magnetic layer 13a is applied in a certain direction to erase the magnetic recording of the first magnetic layer 13a and to fix the second magnetic layer 13b to the fixed state. The information is magnetized and the magnetic recording medium 11
(FIG. 14D). The direction of the bias magnetic field may be the same as, or opposite to, the direction of the bias magnetic field in the magnetic alignment processing.

In the magnetic recording medium 11 of the present invention manufactured as described above, the fixed information in the second magnetic layer 13b of the magnetic recording layer 13 is formed by moving the magnetic material through the undried magnetic coating film. Because of the dense and dense pattern, it is not erased even when a strong magnetic field is applied. Then, the magnetic output waveform when read by the magnetic head is an output waveform in which the reproduction output changes and undulates. This output waveform can be controlled by adjusting the write current at the time of magnetic recording on the first magnetic layer 13a, and can impart information to such a change in analog reproduction output. The fixed information in the second magnetic layer 13b can be arbitrarily set for each magnetic recording medium by controlling the current during magnetic recording on the first magnetic layer 13a.

Incidentally, a resin film such as a polyethylene terephthalate film is used as a base material, and a first magnetic layer and a second magnetic layer are sequentially laminated on the base material by the above-described manufacturing method to form a magnetic recording layer. The magnetic recording medium may be manufactured by preparing a magnetic tape by providing the magnetic tape and bonding the magnetic tape to the entire surface or a part of a card base material or the like.

[0070]

Next, the present invention will be described in more detail with reference to examples.

Example 1 First, as a base material,
8 μm polyethylene terephthalate (E by Toray Industries, Inc.)
-22) was prepared, and a magnetic paint for forming a first magnetic layer having the following composition was applied to one surface of the base material by a gravure coating method and dried to form a first magnetic layer having a thickness of 15 μm.

(Magnetic paint for forming first magnetic layer) Ba ferrite (coercive force = 4000 Oe) 80 parts by weight Vinyl chloride / vinyl acetate copolymer resin 10 parts by weight Urethane resin 10 parts by weight Methyl ethyl ketone 50 parts by weight Toluene 50 parts by weight Methyl isobutyl ketone 50 parts by weight Isocyanate-based curing agent 3 parts by weight

Next, a write current of 100 is applied to the first magnetic layer.
Magnetic recording D was performed at 0 mA. The recording density at this time is 2
00 bpi (FM recording).

Next, a magnetic paint for forming a second magnetic layer having the following composition was applied by gravure coating on the first magnetic layer to form a magnetic coating film.

(Magnetic paint for forming the second magnetic layer) Ba ferrite (coercive force = 1000 Oe) 80 parts by weight Vinyl chloride / vinyl acetate copolymer resin 10 parts by weight Urethane resin 10 parts by weight Methyl ethyl ketone 50 parts by weight Toluene 50 parts by weight Methyl isobutyl ketone 50 parts by weight Isocyanate-based curing agent 3 parts by weight

Next, a magnetic orientation treatment was performed on the magnetic coating film by scanning the back surface of the substrate with a magnetic head. In this magnetic alignment process, the magnetic field applied from the magnetic head in
It was changed continuously within the range of 0 to 2000G. Then, the second magnetic layer (thickness 1) is dried by drying the magnetic coating film.
0 μm). The second magnetic layer formed in this way corresponds to the magnetic recording D of the first magnetic layer, and corresponds to the fixed information D ′ composed of a sparse-dense pattern having a different density of the magnetic material in accordance with the intensity of the above-mentioned alignment magnetic field. It had the following. As a result, a magnetic recording layer composed of a laminate of the first magnetic layer and the second magnetic layer was formed on the substrate.

The substrate on which the magnetic recording layer was formed as described above was punched into a card having a size of 86 mm × 54 mm to obtain a magnetic recording medium of the present invention.

Next, a DC bias magnetic field of 12000 G by a solenoid is applied to the magnetic recording layer of the magnetic recording medium in one direction along the recording direction of the first magnetic layer to erase the magnetic recording D of the first magnetic layer. At the same time, magnetization was performed on the fixed information D 'composed of a dense and dense pattern of the magnetic material of the second magnetic layer.

As a result of reading this magnetic recording medium using a card reader without a bias magnetic field, the reproduced output showed an undulating whole waveform, and the maximum output was about five times the minimum output. At the same time, digital data corresponding to the above sparse / dense pattern was obtained.

Example 2 First, a 15 μm-thick first magnetic layer was formed on a substrate in the same manner as in Example 1, and magnetic recording D was performed on the first magnetic layer at a write current of 1000 mA. The recording density at this time is 200 bpi (FM recording)
And

Next, a magnetic paint for a magnetic shield layer having the following composition is applied on the first magnetic layer by a gravure coating method and dried to form a magnetic shield layer (about 10 mm thick).
μm).

(Magnetic paint for forming magnetic shield layer) Permalloy (coercive force = 10 Oe) 80 parts by weight Vinyl chloride / vinyl acetate copolymer resin 10 parts by weight Urethane resin 10 parts by weight Methyl ethyl ketone 50 Parts by weight-Toluene ... 50 parts by weight-Methyl isobutyl ketone ... 50 parts by weight-Isocyanate curing agent ... 3 parts by weight

Next, on this magnetic shield layer, the embodiment 1
In the same manner as in the above, a magnetic paint for the second magnetic layer was applied to form a magnetic coating film. Next, a magnetic head was scanned on the back surface of the substrate to perform a magnetic orientation treatment on the magnetic coating film. In this magnetic alignment treatment, the magnetic field applied in a fixed direction from the magnetic head was continuously changed within the range of 0 to 2000 G. Then, the magnetic coating film is dried to obtain a second 10 μm thick film.
A magnetic layer was formed. The second magnetic layer thus formed is
In addition to the magnetic recording D of the first magnetic layer, the fixed information D ′ has a dense / dense pattern in which the content density of the magnetic material differs according to the intensity of the above-mentioned orientation magnetic field. However, the fixed information D 'did not exist in a portion where the applied magnetic field did not reach the intensity required to saturate the magnetic shield layer. As a result, a magnetic recording layer composed of a laminate of the first magnetic layer and the second magnetic layer was formed on the substrate.

The substrate on which the magnetic recording layer was formed as described above was punched into a card having a size of 86 mm × 54 mm to obtain a magnetic recording medium of the present invention.

Next, a DC bias magnetic field of 12000 G by a solenoid is applied to the magnetic recording layer of the magnetic recording medium in one direction along the recording direction of the first magnetic layer to erase the magnetic recording D of the first magnetic layer. At the same time, magnetization was performed on the fixed information D 'composed of a dense and dense pattern of the magnetic material of the second magnetic layer.

As a result of reading the magnetic recording medium using a card reader without a bias magnetic field, reproduced outputs appear at predetermined intervals, and undulate (see FIG. 7) at a portion where reproduced outputs are obtained. ) An output waveform was obtained. At the same time, digital data corresponding to the sparse / dense pattern was obtained at each output unit.

Example 3 First, a 15 μm-thick first magnetic layer was formed on a substrate in the same manner as in Example 1. A write current of 0 to 1000 mA is applied to the first magnetic layer.
The magnetic recording was performed while continuously changing in the range. The recording density at this time was 200 bpi (FM recording).

Next, a magnetic coating for the second magnetic layer was applied on the first magnetic layer in the same manner as in Example 1 to form a magnetic coating. Thereafter, a magnetic field was applied to the magnetic coating film by applying a bias magnetic field of 2000 G in a certain direction. Next, the second magnetic layer having a thickness of 10 μm is dried by drying the magnetic coating film.
A magnetic layer was formed. In the second magnetic layer, a region where writing has been performed on the first magnetic layer under the condition that a current equal to or more than the minimum current value (100 mA) at which magnetic recording on the first magnetic layer is possible is applied to the magnetic head, It had fixed information D 'consisting of a dense / dense pattern of a magnetic material corresponding to the magnetic recording D of the first magnetic layer. In addition, the density of the magnetic material in the dense portion of the dense / dense pattern forming the fixed information D 'changes continuously in response to the change in the write current to the first magnetic layer. On the other hand, in the second magnetic layer,
In the portion where the magnetic recording was performed on the first magnetic layer under the condition that the current less than the above minimum current value was applied to the magnetic head,
No fixed information was recorded. As a result, a magnetic recording layer composed of a laminate of the first magnetic layer and the second magnetic layer was formed on the substrate.

The substrate on which the magnetic recording layer was formed as described above was punched into a card having a size of 86 mm × 54 mm to obtain a magnetic recording medium of the present invention.

Next, a DC bias magnetic field of 12000 G by a solenoid is applied to the magnetic recording layer of the magnetic recording medium in one direction along the recording direction of the first magnetic layer to erase the magnetic recording D of the first magnetic layer. At the same time, magnetization was performed on the fixed information D 'composed of a dense and dense pattern of the magnetic material of the second magnetic layer.

As a result of reading this magnetic recording medium using a card reader without a bias magnetic field, reproduced outputs appear at predetermined intervals, and undulate (see FIG. 11) at a portion where reproduced outputs are obtained. ) An output waveform was obtained.
At the same time, digital data corresponding to the sparse / dense pattern was obtained at each output unit.

[0092]

As described in detail above, according to the present invention, the magnetic recording layer provided on the substrate is obtained by laminating the first magnetic layer and the second magnetic layer on the substrate in this order, The second magnetic layer has fixed information composed of a dense / dense pattern of a magnetic material. Since the fixed information changes the density of the magnetic material in a dense portion of the dense / dense pattern along the reading direction, the magnetic information is recorded by a magnetic head. The entire waveform of the output due to the reading of the layer changes in an analog manner, and by adding information to this change, two types of non-rewritable fixed information of digital data and an analog change in the entire output waveform are obtained. The magnetic recording medium can be obtained from the same track, which makes it difficult to alter the magnetic recording medium.

[Brief description of the drawings]

FIG. 1 is a perspective view of a card-shaped magnetic recording medium for explaining an embodiment of the magnetic recording medium of the present invention.

FIG. 2 is a sectional view of the magnetic recording medium shown in FIG.

FIG. 3 is a diagram showing an example of a sparse / dense pattern of the magnetic recording medium of the present invention.

FIG. 4 is a diagram showing an example of a reproduction output waveform of the magnetic recording medium of the present invention, wherein (B) is an enlarged view of a part of (A).

FIG. 5 is a diagram showing another example of the dense / dense pattern of the magnetic recording medium of the present invention.

FIG. 6 is a diagram showing another example of the dense / dense pattern of the magnetic recording medium of the present invention.

FIG. 7 is a diagram showing another example of the reproduction output waveform of the magnetic recording medium of the present invention.

FIG. 8 is a perspective view of a card-shaped magnetic recording medium for explaining another embodiment of the magnetic recording medium of the present invention.

FIG. 9 is a sectional view of the magnetic recording medium shown in FIG.

FIG. 10 is a diagram showing another example of the dense / dense pattern of the magnetic recording medium of the present invention.

11A and 11B are diagrams showing another example of the reproduction output waveform of the magnetic recording medium of the present invention, and FIG. 11B is an enlarged view of a part of FIG.

FIG. 12 is a diagram showing another example of the dense / dense pattern of the magnetic recording medium of the present invention.

FIG. 13 is a process chart showing an example of a method for manufacturing a magnetic recording medium of the present invention.

FIG. 14 is a process chart showing another example of the method for manufacturing a magnetic recording medium of the present invention.

[Explanation of symbols]

1,11 ... magnetic recording medium 2,12 ... base material 3,13 ... magnetic recording layer 3a, 13a ... first magnetic layer 3b, 13b ... second magnetic layer 4 ... fixed information area 5a, 5b, 5c, 5d ... magnetic Dense portions having different material content densities 6 ... Dense portions of dense / dense patterns 14 ... Dense portions of dense / dense patterns 15a, 15b, 15c, 15d ... Dense portions with different content densities of magnetic materials 16 ... Dense portions of dense / dense patterns

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Nobuaki Wakamatsu, 1-1-1, Ichigaya-Kagacho, Shinjuku-ku, Tokyo Inside Dai Nippon Printing Co., Ltd. (72) Hiroyuki Yamaguchi 1-1-1, Ichigaga-cho, Shinjuku-ku, Tokyo No. 1 Dai Nippon Printing Co., Ltd. F term (reference) 2C005 HA04 HB01 HB10 HB11 JA02 KA16 5D006 BA19 BA20 CA05 DA01 FA00 5D112 AA05 AA06 AA11 AA28 CC19 DD04 DD08

Claims (8)

[Claims] 1. A magnetic recording layer comprising: a base material; and a magnetic recording layer on the base material, wherein the magnetic recording layer is formed by laminating a first magnetic layer and a second magnetic layer in order from the base material side. The second magnetic layer contains a magnetic material in a predetermined dense / dense pattern along a predetermined direction, and the content density of the magnetic material in a dense portion of the dense / dense pattern changes along the predetermined direction. Magnetic recording medium. 2. A base material comprising: a base material; and a magnetic recording layer on the base material, wherein the magnetic recording layer is formed by laminating a first magnetic layer and a second magnetic layer in order from the base material side. In the second magnetic layer, portions containing a magnetic material in a predetermined dense / dense pattern are arranged at predetermined intervals along a predetermined direction, and the density of the magnetic material in a dense portion of the dense / dense pattern in each portion is increased in the predetermined direction. A magnetic recording medium characterized in that the magnetic recording medium changes along the length. 3. The magnetic recording medium according to claim 1, wherein in the dense / dense pattern, two or more types of intervals exist between dense portions of the magnetic material. 4. The magnetic recording medium according to claim 1, further comprising a magnetic shield layer between the first magnetic layer and the second magnetic layer. 5. After forming a first magnetic layer on a base material and performing desired magnetic recording on the first magnetic layer along a predetermined direction, applying a magnetic paint on the first magnetic layer; After applying a bias magnetic field along the predetermined direction while changing the strength of the magnetic coating, the magnetic coating is dried, and the magnetic coating is dried to correspond to the magnetic recording pattern of the first magnetic layer. Forming a second magnetic layer having fixed information comprising a dense / dense pattern of a magnetic material and forming a magnetic recording layer comprising the first magnetic layer and the second magnetic layer. Method. 6. After forming a first magnetic layer on a base material and performing desired magnetic recording on the first magnetic layer while changing a write current of a magnetic head along a predetermined direction, the first magnetic layer is formed. Applying a magnetic paint on the layer, applying a bias magnetic field to the magnetic coating along the predetermined direction while performing the magnetic alignment treatment, or after performing the magnetic alignment treatment, drying the magnetic coating. Forming a second magnetic layer having fixed information composed of a dense / dense pattern of a magnetic material corresponding to the magnetic recording pattern of the first magnetic layer;
A method for manufacturing a magnetic recording medium, comprising forming a magnetic recording layer comprising a magnetic layer. 7. In the magnetic recording on the first magnetic layer,
7. The method for manufacturing a magnetic recording medium according to claim 5, wherein the writing density is changed. 8. The method according to claim 5, wherein the second magnetic layer is formed after forming a magnetic shield layer on the first magnetic layer.