JPH08306037A - Magnetic recording medium and manufacturing method thereof - Google Patents

Abstract

PURPOSE: To produce a magnetic recording medium capable of easily imparting forgery preventing information incapable of addition and erasure and capable of preventing illegal use of magnetic information by duplication or alteration. CONSTITUTION: A magnetic layer is formed on the top of a base made of a nonmagnetic body by applying and drying a magnetic coating material contg. high coercive force magnetic powder having 250-5,000Oe coercive force and low coercive force magnetic powder having <=100Oe coercive force. At least part of the magnetic layer is magnetized before the coating material is dried.

Description

Detailed Description of the Invention

[Industrial applications]

The present invention relates to a shopping card, a deposit / savings card,
The present invention relates to a magnetic recording medium used for a magnetic card such as a commuter pass, a ticket, a coupon ticket, a prepaid card, a cash card, a credit card, an identification card, and a medical examination card, a magnetic sheet, a magnetic roll paper, and a manufacturing method thereof. ,
More specifically, by forming judgment information that cannot be added or deleted later in the magnetic paint application process,
The present invention relates to a magnetic recording medium excellent in forgery prevention and a manufacturing method thereof.

[0002]

2. Description of the Related Art In recent years, the field of application of magnetic recording media such as magnetic recording cards or magnetic roll paper has become wider and wider. The basic structure of this type of magnetic recording medium is
Recording is performed by forming a magnetic layer made of a magnetic substance and a binder on a base made of a non-magnetic substance and magnetizing the magnetic layer. Such a magnetic recording medium is
It is widely used as a recording medium because it can be repeatedly recorded and erased. However, since such a magnetic recording medium can be illegally used by copying or falsifying magnetic information, it is required to prevent this.

Under such a background, a method widely used as a forgery prevention method for a magnetic recording medium is as follows.
It is roughly classified into a method of making it difficult to record / reproduce magnetic recording information and a method of giving authenticity determination information to the magnetic recording medium itself. The former is a method of hiding recorded regular information and making it difficult to write and read information, making it difficult to copy or tamper with a normal magnetic recording device.
The latter is a method of preventing forgery and alteration by putting identification information for determining whether or not the magnetic card is legitimate into the magnetic card itself.

More specifically, in the former case, which is known as a measure for preventing unauthorized use by making it difficult to record and reproduce magnetically recorded information, a multi-layered magnetic recording layer is used to form regular information. There is known a technique for hiding the data to make it unreadable by an ordinary magnetic recording / reproducing apparatus. That is, if the dummy information is weighted and recorded on the regular information, it is difficult to analyze the regular information because the regular information and the dummy information are read in an overlapping manner at the time of reading by an ordinary magnetic recording / reproducing apparatus. . However, such a method has a drawback that a complicated magnetic recording / reproducing device is required. In addition, once the details of the method for reading the legitimate information are known, it is possible to read and analyze the information if it is familiar with magnetic recording, so that it is possible to prevent mass duplication of the magnetic recording medium. Was insufficient.

On the other hand, in the latter magnetic recording medium, authenticity determination information is applied to the magnetic card itself. In this system, for example, a magnetic card is provided with a magnetically readable bar code, and the authenticity of the card is determined by this bar code. In this method, since the medium itself has information for determining whether the magnetic recording medium is legitimate, a large amount of duplication can be prevented. However, this method has a problem that it cannot cope with alterations such as rewriting magnetic information of a regular medium.

As another example of the latter magnetic recording medium, the present inventors have disclosed, for example, in Japanese Patent Laid-Open No. 63-9016.
As disclosed in Japanese Patent Application Laid-Open No. 63-9017, there is a method of forming a portion having an orientation direction different from that of most of the magnetic recording medium by a method using a magnetic field. Kaihei 5-342567, JP-A-6-6
0372, JP-A-6-966443, JP-A-6-9
As disclosed in Japanese Patent No. 6444, etc., a method for producing a magnetic recording medium in which an oriented portion different from most of the orientation direction or a non-oriented portion is formed by a heat mode of a heat roll or a laser, and a method for producing the same. A patent application has been filed for the magnetic recording medium having the obtained anti-counterfeit information.

[0007]

These manufacturing methods are
Since the anti-counterfeit information can be added at the same time during magnetic coating, the manufacturing process is simple, and since the anti-counterfeit information can be added only during magnetic coating, it cannot be added or erased afterwards. Since different anti-counterfeit information (fingerprint information) can be given to each final product of the recording medium, it has an excellent feature that it is inexpensive and has very high anti-counterfeit performance. However, in the above-mentioned conventional technique, the problem that the interface between the forgery prevention information portion and the normal orientation portion cannot be clearly identified and the recording density of the forgery prevention information is 1 mm.
There is a problem that it is difficult to form a fine pitch pattern as described below. The present invention has been made in view of the above circumstances, and it is possible to easily add anti-counterfeit information that cannot be added or erased, and prevent illegal use due to duplication or falsification of magnetic information. And its manufacturing method.

[0008]

DISCLOSURE OF THE INVENTION The present invention provides a magnetic recording medium overcoming the drawbacks of the above-mentioned conventional structures or methods and being extremely difficult to illegally use, and a method of manufacturing the same. The magnetic recording medium according to claim 1 comprises, on a base made of a non-magnetic material, a high coercive force magnetic powder having a coercive force of 250 to 5000 oersted and a low coercive force magnetic powder having a coercive force of 100 oersted or less. A magnetic layer is formed by applying and drying a magnetic paint containing magnetic powder, and at least a part of this magnetic layer is magnetized before the magnetic paint is dried. Further, in the magnetic recording medium according to claim 2, the magnetized portion of the magnetic layer according to claim 1 is
A magnetized portion comprising a high coercive force magnetic powder having a coercive force of 250 to 5000 oersted and a low coercive force magnetic powder having a coercive force of 100 oersted or less, and a low coercive force magnetic powder having a coercive force of 100 oersted or less around the magnetized part. And a portion formed by assembling at a high density.

According to a third aspect of the present invention, there are two types of magnetic recording media, a high coercive force magnetic powder having a coercive force of 250 to 5000 oersteds and a low coercive force magnetic powder having a coercive force of 100 oersteds or less, on a base made of a non-magnetic material. To form a magnetic layer by drying the magnetic coating material having the magnetic powder, and the magnetic layer is formed by orienting the magnetic field in the application direction of the magnetic coating material or in a direction deviated from the application direction before drying the magnetic coating material. And a magnetically altered portion in which a magnetic field is applied to the magnetic orientation portion to change the magnetic alignment state of the magnetic orientation portion before the magnetic paint is dried. According to the magnetic recording medium of the third aspect, in the magnetic recording medium, the forgery prevention information can be constituted by the magnetically altered portion. In the magnetic recording medium according to claim 4, the magnetized portion of the magnetic layer according to claim 1, 2 or 3 is composed of a random pattern or a regularly arranged pattern, and the forgery prevention information is formed by these patterns. Can be configured.

According to a fifth aspect of the present invention, there is provided a method of manufacturing a magnetic recording medium, wherein 250 to 500 is formed on a base made of a non-magnetic material.
A magnetic paint having two kinds of magnetic powder, a high coercive force magnetic powder having a coercive force of 0 oersted and a low coercive force magnetic powder having a coercive force of 100 oersted or lower, is applied to form a undried magnetic layer, which is subsequently undried. Before the magnetic layer is dried, a magnetic field is applied to a part of the undried magnetic layer to partially magnetize the undried magnetic layer, and then the undried magnetic layer is dried.

According to a sixth aspect of the present invention, there is provided a method of manufacturing a magnetic recording medium, wherein two types of magnetism, a magnetic powder having a coercive force of 250 to 5000 oersted and a magnetic powder having a coercive force of 100 oersted or less, are formed on a base made of a non-magnetic material. Before applying a magnetic coating material containing powder to form a undried magnetic layer, magnetic field orientation of the undried magnetic layer in a coating direction or in a direction deviated from the coating direction, and then before the undried magnetic layer is still dried The magnetic state of the undried magnetic layer is partially changed by applying a magnetic field to a part of the undried magnetic layer, and then the undried magnetic layer is dried.

[0012]

According to the present invention, as described above, two types of magnetic powder having a coercive force of 250 to 5000 oersteds and a low coercive force magnetic powder having a coercive force of 100 oersted or less are provided on the base made of a non-magnetic material. Before applying a magnetic coating material containing magnetic powder and before drying the magnetic layer, a magnetic field is applied to a part of the undried magnetic layer to partially magnetize a part of the magnetic layer, and then the undried magnetic layer. Is dried. That is, the magnetic layer is partially magnetized by an external magnetic field applied after the coating and before it is dried. At this time, 250-5
The high coercive force magnetic powder having a coercive force of 000 oersted is magnetized and oriented by a magnetic field applied from the outside, and this magnetization state is maintained from before the magnetic layer is dried to after the magnetic layer is dried. Also, the low coercive force magnetic powder with a coercive force of 100 Oersted or less,
A magnetic field partially applied from the outside and a magnetic field generated by the magnetization of the high coercive force magnetic powder having a coercive force of 250 to 5000 oersted in the magnetic coating material generate a dense portion in a pattern.

In another aspect of the invention, two types of magnetism, a high coercive force magnetic powder having a coercive force of 250 to 5000 oersteds and a low coercive force magnetic powder having a coercive force of 100 oersteds or less, are formed on a base made of a non-magnetic material. Apply a magnetic coating material containing powder to form a undried magnetic layer, and then, before the undried magnetic layer is still dry, uniformly coat the entire undried magnetic layer in the coating direction or in a direction deviated from the coating direction. Magnetic field orientation treatment is further performed, and then the undried magnetic layer is partially magnetized, and then the undried magnetic layer is dried. In this case, 250 ~
The high coercive force magnetic powder having a coercive force of 5000 oersted is magnetized by a magnetic field applied from the outside, and this state of magnetization is maintained from before drying to after drying the undried magnetic layer.
Further, the low coercive force magnetic powder having a coercive force of 100 oersted or less is caused by the magnetic field partially applied from the outside and the magnetic field generated by the magnetization of the high coercive force magnetic powder having a coercive force of 250 to 5000 oersted in the magnetic paint. , Densely patterned portions are formed in the magnetic layer.

As described above, due to the partial magnetization of the undried magnetic layer, the magnetic layer after drying has a partially different orientation state.
Further, the high coercive force magnetic powder in a high density state is physically fixed. This state is maintained even when the entire magnetic layer is DC-demagnetized or AC-demagnetized. For example, by reproducing the track portion on which the pattern is formed while applying a DC bias magnetic field, there is a peak corresponding to the pattern. You can get the signal. Then, the peak interval, the number, the position, etc. of this signal are digitized, and this value should be included in the information recorded in the ordinary magnetic recording portion performed on the normally oriented track portion of the magnetic recording medium. If
When this magnetic recording medium is used, the authenticity of the medium can be determined by comparing the value of the detected identification information with the value of the identification information mixed in with the magnetic information, eliminating the forgery of the medium. You can do it. This identification information is recorded during the coating process of the magnetic paint before the dried magnetic layer is dried, and then fixed by drying the dried magnetic layer, so that it can be added later or deleted. That is impossible information.

In the magnetic recording medium manufactured by the manufacturing method of the present invention, for example, a magnetic card, each card can have different forgery prevention information. That is, it can have fingerprint-like information. As a result, each individual card has its own judgment information that cannot be added or erased later.By using this judgment information, it is almost perfect for mass copying and falsification of data. It is possible to prevent it.

Another method of manufacturing a magnetic recording medium of the present invention is
A magnetic coating is applied on a non-magnetic base to form a undried magnetic layer. Then, while the magnetic layer is undried, the moving direction of the base, that is, the magnetic recording direction of the magnetic layer (longitudinal direction) or the longitudinal direction Magnetic field orientation treatment is applied in the direction shifted from the direction,
Then, while the magnetic layer is still undried, a magnetic field is applied by an electromagnet to disturb the orientation of part of the undried magnetic layer, resulting in no orientation.
Alternatively, while forming a portion in a state close to this, a high density portion of the low coercive force magnetic body is formed in the magnetic layer by a magnetic field applied from the outside and a magnetic field generated by the magnetization of the high coercive force magnetic powder thereby. Then, the undried magnetic layer is dried. The electromagnet used here may have a ring head shape so as not to come into direct contact with the undried magnetic layer, and may be arranged on the back surface side (the side where the magnetic layer is not formed) of the base of the magnetic recording medium. Electromagnets may be arranged so as to sandwich the magnetic recording medium from both the front surface side and the back surface side of the recording medium.

The present invention will be described in more detail below with reference to the accompanying drawings. FIG. 1 shows an example of a manufacturing process of a magnetic recording medium according to the present invention. In this example, a high coercive force magnetic powder having a coercive force of 250 to 5000 oersteds and a low coercive force magnetic powder having a coercive force of 100 oersted or less are provided on a base 2 made of a non-magnetic material such as a white polyethylene terephthalate film sent from a reel 1. And a magnetic paint obtained by adding a binder, a solvent, and a trace amount of additive to the mixture are coated with the coating head 3 of the coating machine to form the undried magnetic layer 4,
Then, the undried magnetic layer 4 is moved in the traveling direction of the base 2 by a magnetic field orientation device 5 having a magnetic field generation capability of about 5K Oersted.
Is oriented. The magnetic field orientation device 5 is arranged at right angles to the advancing direction of the base 2 so that the undried magnetic layer 4 can be magnetically oriented in the advancing direction of the base 2. Angles other than 45, for example
If the angle is changed to 45 degrees, the magnetic field orientation processing can be performed in a direction having an inclination of 45 degrees with respect to the traveling direction of the base 2, that is, a direction deviated from the application direction of the magnetic paint by 45 degrees.

As the nonmagnetic base 2 used here, a sheet-shaped nonmagnetic material such as a polyester film, a vinyl chloride film, a synthetic paper, a wood pulp paper, a laminated paper having a thickness of about 150 to 1 mm can be applied. Also, 250 to 50
As the magnetic substance forming the high coercive force magnetic powder having a coercive force of 00 Oersted, γ-iron oxide, cobalt-doped γ-iron oxide, chromium oxide, barium ferrite, strontium ferrite, or the like can be applied. Carbonyl iron, manganese zinc ferrite, nickel, ferric tetroxide, permalloy, sendust, alperm and the like can be applied to the magnetic substance forming the low coercive force magnetic powder having a low coercive force.

The mixing ratio of the magnetic powders having different coercive force, that is, (high coercive force magnetic powder having coercive force of 250 to 5000 oersted) :( low coercive force magnetic powder having coercive force of 100 oersted or less) is , 50:50 to 95: 5 is preferable, and 80:20 to 90:10 is particularly preferable. When it is smaller than the mixing ratio of 50:50, the ratio of the high coercive force magnetic powder is too small and the performance of the magnetic recording medium itself is deteriorated. When it is larger than the mixing ratio of 95: 5, the ratio of the low coercive force magnetic powder is low. It becomes too small to read the forgery prevention information. Also, the binder is vinyl chloride
Known substances such as vinyl acetate copolymer, vinyl chloride / vinyl acetate / vinyl alcohol copolymer, polyurethane resin, polyester resin, epoxy resin, polyisocyanate resin can be used, and the solvent is known such as toluene or methyl ethyl ketone. Those can be used as appropriate.

Next, before the coating film of the undried magnetic layer 4 made of magnetic paint is dried, a rectangular wave current is intermittently applied to the ring-shaped electromagnets 6 ... As shown in FIG. By applying a magnetic field from the back surface side of the base 2 of the film, a magnetic field is partially applied to the undried magnetic layer 4 to form patterned magnetized portions 9. The undried magnetic layer 4 thereafter passes through the drying device 7 and is dried and solidified to form the magnetic layer 10.
The magnetic reduction 11 is obtained and wound on the winding device 8. If the current applied to each of the electromagnets 6 is too small, the electromagnets 6
The magnetic field generated by is too weak to disturb the orientation sufficiently. If the current is too large, the generated magnetic field is too strong, and large ruggedness is formed on the undried undried magnetic layer 4. Further, if the gap G of the ring-shaped electromagnet 6 is too small, the reaching distance of the generated magnetic field becomes short, and a sufficient magnetic field cannot be given from the back surface side of the non-magnetic film 2. If too large, the electromagnet 6 becomes large. The current must be passed, and the device becomes oversized. The electromagnet 6 for forming the forgery prevention information is shown in FIG.
It is sufficient to arrange as many tracks as necessary in the width direction.

The rectangular wave current flowing through the electromagnet 6 may be a random pattern or may be based on some law. The same pattern of current may be supplied to each track, or a completely different pattern of current may be supplied. Further, as shown in FIG. 2, if a current having a completely different pattern is applied to each track, a magnetic recording medium obtained from the magnetic material roll 11 thus manufactured, for example, a magnetic card, can be used for all magnetic cards. You will have different anti-counterfeit information. That is, it has fingerprint information. The fact that there is no other magnetic card having the same information makes it more difficult to forge the magnetic card. In this case, it is preferable that the portions of which the orientation is disturbed are arranged on a certain track when punched into a magnetic card.

FIG. 3 shows an example of how to apply a magnetic field when the magnetized portions 9 are formed in a pattern in the above manufacturing method. In this example, the entire undried magnetic layer 4 is simultaneously magnetized uniformly in one direction by the magnetic field orientation device 5, but the magnetized portion 9 magnetized by the electromagnet 6 is referred to as the magnetization direction by the orientation process of the magnetic field orientation device 5. Magnetize in the opposite direction. FIG.
An example of the planar arrangement state of the magnetized portions 9 ... In this example, since the magnetic paint in which the low coercive force magnetic powder and the high coercive force magnetic powder are mixed is used, the magnetized portion 9 is mainly formed of the high coercive force magnetic powder, and the magnetized portion 9 is surrounded by the low coercive force magnetic powder as shown by diagonal lines. A portion 9 ′ is formed which is formed as a high concentration portion of the coercive force magnetic powder.

Next, FIG. 5 shows an example of an arrangement structure of a magnetic head for partially magnetizing in a direction opposite to the magnetization direction oriented by the magnetic field orientation device 5. As shown in FIG. 5A, a ring head type magnetic head 6 may be installed on the side opposite to the coating surface to apply a magnetic field to the undried magnetic layer 4, or as shown in FIG. 5B. Ring head type magnetic head 6, 6 '
It may be installed on both sides of the non-magnetic tape 2 so as to sandwich the coating surface from above and below. Further, as shown in FIG. 5 (c), rod-shaped electromagnets 6 ″ and 6 ″ are provided so as to give opposing magnetic fields of the same polarity.
May be arranged.

In FIG. 6, a card-shaped magnetic recording medium is punched out from a magnetic raw material including a magnetized portion 9 magnetized in a direction opposite to the magnetization due to the orientation of the magnetic field orientation device 5 as described above, and the entire card is degaussed by direct current. Then, a magnetic recording / reproducing apparatus equipped with a recording / reproducing dual-purpose magnetic head was used to reproduce data on a track on which the magnetized portions 9 were lined up, and the result was displayed on a synchroscope. It is shown. As shown in FIG. 6, a pulsed output can be detected at the edge portion of the magnetized portion 9. Such an output waveform is information that cannot be added or deleted after the card has been manufactured. If the number and interval of this output are digitized and used as card ID information, the authenticity of the card can be determined. It becomes possible to do. Moreover, since this waveform is a peak waveform, it is easy to detect, and magnetic information due to the presence of the magnetized portions 9 ... Can be detected with high sensitivity.

FIG. 7 shows a cross-sectional structure of a magnetic reduction member obtained by the method shown in FIGS. 3 and 5 (a) punched out into a card shape. In the magnetic layer 10 shown in FIG. 7, the protrusions 12 are intermittently formed.
It has a structure in which many are formed. This is a portion where the concentration of the low coercive force magnetic powder is high is formed in a convex shape, and corresponds to the portion 9 ′ in FIG.

FIG. 8 shows an example of a sectional structure of a magnetic card to which the structure shown in FIG. 7 is applied. In the structure of this example, a magnetic layer 10 is formed on a base 2 via an under layer 15, and a magnetic concealment concealing layer 16 known as a silver coloring layer or a white layer is formed on the magnetic layer 10. A thermal recording layer 17 such as a leuco dye type and a protective layer 18 are laminated.
The structure of this example corresponds to the structure of an actually used magnetic card, and the surface or the lower surface of the protective layer 18 is appropriately printed according to the purpose of use. The under layer 15 is used to prevent the magnetic paint from penetrating into the base 2 when the base 2 is made of a material such as paper. In the present invention, the structure in which the thermal recording layer 17 is provided on the back surface side of the base 2, the structure in which only the protective layer 18 is provided on the magnetic layer 10, and the hiding layer 16 and the protective layer 18 only on the magnetic layer 10 are provided. Needless to say, the structure may be provided.

In the manufacturing method described above with reference to FIGS. 1 to 5, the undried magnetic layer 4 is formed by using the magnetic field orientation device 5.
The entire magnet is magnetized once in its longitudinal direction and then the electromagnet 6 ...
, But the magnetic field orientation device 5 is omitted, and the magnetized portion 9 is formed by the electromagnets 6 ... May be created. Even in the magnetic card obtained by manufacturing in this manner, the peak output waveform shown in FIG. 4 can be obtained.

[0028]

【Example】

 (Example 1) A magnetic coating material having the following composition was prepared. Magnetic powder Barium ferrite Coercive force 2750 Oe 80 parts by weight Carbonyl iron powder Coercive force 10 Oe 20 parts by weight Carbon black 3 parts by weight Lecithin 1 part by weight Vinyl chloride / vinyl acetate / vinyl alcohol copolymer (Eslec A manufactured by Sekisui Chemical Co., Ltd.) 20 20 parts by weight Polyurethane resin (Nipporan N-2304 manufactured by Nippon Polyurethane Industry) Polyisocyanate resin (Coronate L manufactured by Nihon Polyurethane Industry) 5 parts by weight Toluene 60 parts by weight Methyl ethyl ketone 60 parts by weight Methyl isobutyl ketone 60 parts by weight

A magnetic coating material having this composition was applied onto a polyester film having a thickness of 188 μm by the method shown in FIG. 1, and then a magnetic field was partially applied using a ring-shaped electromagnet. The structure of the ring-shaped electromagnet and its driving conditions are described below.

A card was punched out from the magnetic material obtained in this way, and a DC bias magnetic field was applied by a recording / playback head with a recording / playback head for a magnetic card onto a track including a portion where a magnetic field was applied in a pattern. However, when reproduction was performed, a pulsed reproduction output could be detected at the position of the forgery prevention information section. This pulsed output has a sufficient output level as anti-counterfeit information, and it was possible to prevent forgery of the card by this information.

(Example 2) Instead of the magnetic powder used in Example 1, magnetic powder barium ferrite, coercive force 1750 Oe 80 parts by weight, carbonyl iron powder, coercive force 10 Oe 20 parts by weight were used. Other than that, the same composition as in Example 1 was used, the card was punched out from the magnetic raw material obtained under the same conditions as in Example 1, and the reproduction output was measured by the same measuring means. I got the same result as.

Example 3 In place of the magnetic powder used in Example 1, magnetic powder barium ferrite coercive force 1750 Oe 80 parts by weight magnetite powder coercive force 25 Oe 20 parts by weight was used. Is a composition similar to that of Example 1, a card is punched out from the magnetic raw material obtained under the same conditions as in Example 1, and the reproduction output is measured by the same measuring means. I was able to get the same result.

[0033]

As described above, the invention according to claim 1 is provided with a magnetic layer obtained by applying a magnetic coating material having a low coercive force magnetic powder and a high coercive force magnetic powder onto a base and drying it. Part of the magnetic layer is magnetized before it is dried, and a magnetized portion is formed in the magnetic layer according to the magnetic form before the magnetic layer is dried and solidified. Since it is physically fixed by solidification, it cannot be erased or changed after it is dried, and this magnetized portion becomes the forgery prevention information of the magnetic recording medium.
Therefore, according to the invention described in claim 1, it is possible to provide a magnetic recording medium that cannot be forged or altered. Furthermore,
The magnetized part is composed of low coercive force magnetic powder and high coercive force magnetic powder.
Since a unique magnetic output formed by the types of magnetic powder is generated, magnetic information due to the presence of the magnetized portion can be detected with high sensitivity.

In the magnetic recording medium according to claim 3,
Since the magnetically oriented portion formed before the magnetic layer is dried and the magnetically altered portion in which the magnetically oriented state of the magnetically oriented portion is different are present, the existence of the altered magnetic portion serves as anti-counterfeit information. Since the magnetically oriented portion and the magnetically altered portion are physically fixed by the solidification of the magnetic paint by drying, they cannot be erased or changed after drying. The information is forgery prevention information that cannot be changed or changed. Further, since the magnetization orientation altered portion is included in the magnetization orientation portion, it is possible to easily detect the magnetization orientation altered portion.
In addition, this magnetically oriented degenerated portion produces a unique magnetic output formed by two types of magnetic powder, low coercive force magnetic powder and high coercive force magnetic powder, so that magnetic information due to the presence of the magnetized portion can be detected with high sensitivity. can do. Further, by forming the magnetized portion from a random pattern or a regularly arranged pattern as described in claim 4, these patterns serve as anti-counterfeit information, and a signal waveform corresponding to these patterns can be obtained. Authenticity information of the magnetic recording medium can be obtained.

Next, according to the manufacturing method of the fifth aspect,
By applying a magnetic field to a part of the undried magnetic layer made of magnetic paint applied on the base, magnetizing a part, and then drying,
A magnetic recording medium provided with the forgery prevention information according to claim 1 can be manufactured. Further, according to the manufacturing method of claim 6, a magnetic field is formed by applying a magnetic field to the undried magnetic layer made of a magnetic coating material applied on the base, and then a magnetic field is applied to a part of the magnetically oriented part to form a magnetization. A magnetic recording medium provided with the forgery prevention information according to claim 5 can be manufactured by drying a part of the orientation portion after the magnetization orientation alteration portion.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an example of an apparatus for carrying out a manufacturing method according to the present invention.

FIG. 2 is an enlarged perspective view showing a positional relationship between a magnetic field orientation device and a magnetic head provided in the device shown in FIG.

FIG. 3 is an explanatory view showing a state in which a part of the undried magnetic layer oriented by the magnetic field orientation apparatus shown in FIG. 2 is oriented in the opposite direction by a magnetic head to form a magnetized portion.

4 (a) is a plan view showing an arrangement state of magnetic parts partially formed in the undried magnetic layer in the magnetic head shown in FIG. 3, and FIG. 4 (b) shows the same magnetic arrangement state. FIG.

FIG. 5 shows an arrangement configuration of a magnetic head that applies a magnetic field to a undried magnetic layer on a non-magnetic substrate. FIG. 5A shows an example in which a magnetic head is disposed on the back surface side of the non-magnetic substrate. 5 (b) is an explanatory view showing an example in which magnetic heads are arranged above and below a non-magnetic substrate, and FIG. 5 (c) shows bar-shaped magnets above and below the non-magnetic substrate. It is explanatory drawing which shows an example.

FIG. 6 is a diagram showing an output waveform obtained from one structural example of the magnetic recording medium obtained according to the present invention.

FIG. 7 is a cross-sectional view showing an example of a magnetic card obtained by the manufacturing method of the present invention.

FIG. 8 is a cross-sectional view showing another example of a magnetic card obtained by the manufacturing method of the present invention.

[Explanation of symbols]

 2 base, 4 undried magnetic layer, 5 magnetic field orientation device, 6, 6 ', 6' 'magnetic head, 7 drying device, 10 magnetic layer, 11 magnetic material roll,

Claims (6)

[Claims] 1. On a base made of a non-magnetic material, 250 to
High coercive force magnetic powder with coercive force of 5000 Oersted and 10
A magnetic layer is formed by applying and drying a magnetic paint having two types of magnetic powder, a low coercive force magnetic powder having a coercive force of 0 Oersted or less, and at least a part of this magnetic layer is magnetized before drying. A magnetic recording medium characterized by the following: 2. The magnetized portion of the magnetic layer is 250 to 5
High coercive force magnetic powder with coercive force of 000 oersted and 100
A magnetized portion composed of a low coercive force magnetic powder having a coercive force of not more than Oersted, and a portion formed around the magnetized portion by gathering a low coercive force magnetic powder having a coercive force of not more than 100 Oersted at a high density. The magnetic recording medium according to claim 1, wherein the magnetic recording medium is configured as described above. 3. A base made of a non-magnetic material, and
High coercive force magnetic powder with coercive force of 5000 Oersted and 10
A magnetic layer is formed by drying a magnetic paint having two types of magnetic powder, a low coercive force magnetic powder having a coercive force of 0 Oersted or less, and the magnetic layer is formed in the coating direction of the magnetic paint or before the magnetic paint is dried. A magnetic orientation portion formed by magnetic field orientation in a direction deviated from the coating direction, and a magnetization in which a magnetic orientation state of the magnetic orientation portion is changed by applying a magnetic field to the magnetic orientation portion before drying the magnetic paint. A magnetic recording medium comprising an altered portion. 4. The magnetized portion of the magnetic layer comprises a random pattern or a regularly arranged pattern,
4. The magnetic recording medium according to claim 1, 2 or 3, wherein forgery prevention information is constituted by these patterns. 5. A base made of a non-magnetic material, 250
High coercive force magnetic powder with coercive force of ~ 5000 Oersted and 1
A magnetic coating material having two types of magnetic powder, a low coercive force magnetic powder having a coercive force of not more than 00 Oersted, is applied to form a undried magnetic layer, and then the undried magnetic layer is dried before the undried magnetic layer is dried. A method for manufacturing a magnetic recording medium, comprising partially magnetizing the undried magnetic layer by applying a magnetic field to a part thereof and then drying the undried magnetic layer. 6. A base made of a non-magnetic material, 250 to
High coercive force magnetic powder with coercive force of 5000 Oersted and 10
A magnetic coating material having two types of magnetic powders having a low coercive force of 0 Oersted or less is applied to form a undried magnetic layer, and the undried magnetic layer is applied in a direction or a direction deviated from the application direction. The magnetic state of the undried magnetic layer is partially changed by applying a magnetic field to a part of the undried magnetic layer before the undried magnetic layer is still dried, and then,
A method of manufacturing a magnetic recording medium, which comprises drying the undried magnetic layer.