JPH07118080B2 - Method of manufacturing magnetic recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention provides productivity by applying identification information, which cannot be added or erased later, to a magnetic recording medium at the time of applying a magnetic paint. The present invention also provides a method of manufacturing a magnetic recording medium that is high and excellent in forgery prevention.

<Prior Art> In recent years, magnetic recording media, particularly in the form of magnetic cards, are increasingly used as money vouchers in place of small amounts of money. The most important issue here is how to prevent unauthorized use by tampering with magnetic information or copying of cards.

Therefore, various countermeasures against illegal use are used. Among them, the simplest one is a method using software for encrypting magnetic recording information, but the effect of preventing illegal use is not so high.

Therefore, a method has been proposed in which the magnetic card itself has a function of preventing unauthorized use, which has a higher effect of preventing unauthorized use. These are roughly classified into two types. That is, the first method is a method of hiding the recorded magnetic information to make it unreadable, thereby making it difficult to falsify or copy the magnetic information, and the second method is to judge whether or not the magnetic card is a legitimate one. This is a method of preventing forgery by putting an identification function for doing so in the card itself.

For example, known as the fraud prevention measure of the first method is to analyze the legitimate information by shielding the legitimate information to make it unreadable or superimposing the dummy information by making the magnetic recording section multi-layered. There are things that make it difficult. Further, as a measure against fraud in the second method, there is a device provided with an optical bar code or a magnetic bar code.

However, each of these methods has drawbacks and is not yet sufficient. That is, the first method has drawbacks such as a complicated manufacturing process and a complicated recording and reading device. Further, if the details of the concealing method are known, it is possible to read and analyze the information if it is familiar to the magnetic recording, and thus the duplication becomes possible.
A product provided with the fraud prevention measure of the second method cannot be actually used even if the magnetic information can be forged unless it is a legitimate card having correct judgment information. However, this method also has the drawback that the manufacturing process is complicated and the determination information reading device is complicated.

<Problems to be Solved by the Invention> The magnetic recording medium according to the present invention has the function of preventing illegal use by the second method, overcomes the drawbacks of the conventional method, and is extremely difficult to illegally use. A method of manufacturing a magnetic recording medium is provided.

<Means for Solving the Problems> The present invention comprises a magnetic substance having a coercive force higher than that usually used as a magnetic recording material, that is, a coercive force higher than 3000 Oersted, on a substrate made of a non-magnetic substance. In addition, the first magnetic layer in which identification magnetic information for preventing forgery is written in advance, and a magnetic substance usually used as a magnetic recording material, that is, 25
A method of manufacturing a magnetic recording medium, which comprises sequentially laminating a second magnetic layer made of a magnetic material having a coercive force of 0 oersted or more and 3000 oersted or less, and comprising a magnetic material having a high coercive force of more than 3000 oersted. When the first magnetic layer is coated, a magnetic field is applied from the side opposite to the coated surface of the substrate by a magnetic head or a permanent magnet before the magnetic coating material is dried, and identification magnetic information for preventing forgery is written in a part of the magnetic layer. And then drying the magnetic layer, and then providing a second magnetic layer made of a magnetic material of 250 oersteds or more and 3000 oersteds or less on the first magnetic layer, the method for producing a magnetic recording medium. Is.

The magnetic recording medium obtained by the present invention has at least two magnetic layers. The first magnetic layer is a magnetic layer made of a magnetic material having a coercive force higher than that normally used as a magnetic recording material, and is applied to the substrate by a magnetic head or a permanent magnet during coating before the magnetic paint dries. It is manufactured by applying a magnetic field from the coated surface to previously perform magnetic recording on the magnetic layer as identification information for preventing forgery, and then drying the magnetic layer.

At this time, the magnetic layer may or may not be subjected to the magnetic field orientation treatment before the magnetic recording.

The magnetic fine particles are apparently low in coercive force in a state in which they can freely move around in a magnetic paint, and can be magnetized, that is, magnetically recorded, only by giving a very weak magnetic field. For example, when a magnetic material with a coercive force of 8000 Oersted is dispersed to form a magnetic paint, the hysteresis curve is measured with a VSM (vibrating sample magnetometer) in the state of the paint, that is, without drying, and an external magnetic field of 500 Oersted Magnetically saturated. However, when the magnetic hysteresis curve is measured by coating the coating material on a non-magnetic substrate and drying the coating, the magnetic layer is not magnetically saturated even if the magnetic layer is oriented in a magnetic field and an external magnetic field of 10,000 oersted is applied in that direction. That is, when the magnetic paint is dried and the magnetic fine particles are fixed, it cannot be magnetized unless a sufficiently strong magnetic field is applied according to the coercive force.

Since the first magnetic layer of the magnetic recording medium manufactured by the manufacturing method according to the present patent is made of a magnetic material having a higher coercive force than that normally used as a magnetic recording material, the magnetic layer during coating dries. If not before, magnetic recording and erasing of the recording will be very difficult with a commonly used magnetic head or permanent magnet.

For the magnetic recording for writing the forgery prevention identification information, for example, a magnetic head as shown in 1-a of FIG. 1 may be used. At this time, as the recording current, a pulse current such as 2-a or 2-b in FIG. 2 may be applied to the magnetic head.
When magnetic recording is performed using a permanent magnet, a permanent magnet arranged in a roll may be used as shown in 1-b of FIG. 1, for example.

In this way, forgery prevention identification magnetic information, which is very difficult to add or erase to the first magnetic layer afterwards, is written, the first magnetic layer is dried, and then the second magnetic layer is dried. Apply layers. The second magnetic layer is made of a magnetic substance having a coercive force that is usually used as a magnetic recording material, and the coating method may be the same as in the case of manufacturing a normal magnetic recording medium. In the magnetic recording medium manufactured as described above, the first magnetic layer is separated from the medium surface by the second magnetic layer. That is, when the magnetic recording medium is actually used, the first magnetic layer is kept away from the magnetic head by the second magnetic layer, so that the magnetic recording can be performed later or the written magnetic information can be erased. Is even more difficult and almost impossible. That is, the first magnetic layer has authentic identification information of a card that cannot be added or erased later for the purpose of preventing forgery, and normal rewritable magnetic recording information is stored in the second magnetic layer. It is possible to manufacture the magnetic recording medium of the present invention.

An example of the structure of the magnetic recording medium of the present invention obtained by the above method is shown in FIG. That is, 3-a in FIG. 3 is a plan view of the magnetic recording medium obtained by the present invention, 3-b
FIG. 3B is a cross-sectional view taken along line XX of 3-a. In the figure 3-
Reference numeral 1 is a track on the second magnetic layer for performing normal magnetic recording, and 3-2 is a track on the first magnetic layer for performing magnetic recording according to the present invention. 3-3 is a base made of a non-magnetic material such as a polyester film, 3-4 is the first
Magnetic layer, 3-5 is a second magnetic layer, and 3-6 is a protective layer.

<Examples> Hereinafter, the present invention will be described in detail with reference to Examples. It should be noted that all compounding parts are shown as parts by weight.

Example 1 A coating material for the first magnetic layer was prepared with the following composition.

After the above mixture was dispersed by a ball mill for 8 hours, 5 parts of polyisocyanate resin was added and further dispersed for 1 hour to obtain a magnetic coating material for the first magnetic layer.

Next, using the apparatus shown in FIG. 4, the coating material for the first magnetic layer was coated on one surface of the substrate made of polyester film so that the coating thickness after drying was 15 μm. In FIG. 4, 4-1 is a roll of the substrate film, 4-2 is a coating head, and the magnetic layer coated by the coating head passes through the magnetic field orientation device 4-3 to perform orientation treatment. After that, magnetic information was recorded by the magnetic head 1-a in FIG. 1 at the position 4-4 before entering the drying device.

The magnetic information was recorded while synchronizing the line speed of the coating device and the pulse current flowing to the magnetic head so that the recording density of 100 FCI was recorded on the magnetic card. After the identification magnetic information is written by the magnetic head of 4-4, it is dried while passing through the drying device of 4-5 and wound on the reel of 4-6 to apply the first magnetic layer. Complete.

FIG. 5 is an enlarged view of portions 4-3 and 4-4 in FIG. By passing through the magnetic field orientation device 5-1, the magnetic layer is magnetically oriented in the traveling direction, and is evenly magnetized in the traveling direction, that is, the coating direction. The magnetic recording was performed by selecting the polarity of the current so that a magnetic field in the direction opposite to the magnetizing direction was applied to the magnetic layer by the magnetic head, and applying the pulse current of 2-b in FIG. 2 to the magnetic head. At this time, the magnetic head and the current strength were selected so that a magnetic field of 500 Oersted could be applied to the magnetic layer. The second magnetic layer is formed by applying the first magnetic layer and then applying the second magnetic layer coating material prepared by the following method so that the coating thickness after drying is 15 μm. A recording medium was obtained.

The mixture was dispersed for 8 hours in a ball mill, 5 parts of polyisocyanate resin was added, and the mixture was further dispersed for 1 hour to obtain a magnetic coating material for the second magnetic layer. Since the second magnetic layer is a magnetic layer for performing ordinary magnetic recording, coating may be performed according to an ordinary method. The raw material of the magnetic recording medium of the present invention thus manufactured is punched into a JIS size to obtain a magnetic card, and the magnetic layer is applied to the first magnetic layer using a magnetic card recording / reproducing apparatus compatible with high coercive force. Recorded at 10
The magnetic information of 0FCI was able to be reproduced. Attempts were made to overwrite and DC erase this information using the same device, but it was not possible to record new information by overwriting nor to erase the information recorded during coating.
Magnetic recording was normally performed on the second magnetic layer.

Example 2 1/10 for a paper roll made of non-magnetic aluminum
A magnet roll having a cross section of 1-b in FIG. 1 was produced by lining up and pasting plate-shaped rubber magnets having an inch width. The magnet was selected to provide a magnetic field of 500 Oersted when applying the magnetic layer. A magnetic card was manufactured in the same manner as in Example 1 by setting this magnet roll at the position 4-4 in FIG. 4 instead of the magnetic head 5-2 in FIG. 5 of Example 1.

The magnetic information of 10FCI recorded when the magnetic layer was applied to the first magnetic layer can be reproduced from the JIS size magnetic card manufactured in this way using a magnetic card recording / reproducing device compatible with high coercive force. It was Attempts were made to overwrite and DC erase this information using the same device, but it was not possible to record new information by overwriting nor to erase the information recorded during coating. Normal magnetic recording was possible on the second magnetic layer.

<Effects of the Invention> In the present invention, since the magnetic recording medium can contain identification information that cannot be added or erased later when the magnetic paint is applied, it is extremely difficult to forge or illegally use. . In addition, the manufacturing facility is high in productivity because it requires only a simple magnetic recording device to be added to the conventional magnetic recording medium manufacturing device and does not require any special technology.

[Brief description of drawings]

FIG. 1 shows a magnetic head and a permanent magnet for writing magnetic information for identification on the first magnetic layer, FIG. 2 is a state diagram of a pulse current applied to the magnetic head, and FIG. The structure of the magnetic recording medium obtained in FIG. 4 is a magnetic paint coating device, and FIG. 5 is an enlarged view of the magnetic field orientation device and the magnetic head portion of FIG. 1-a ... magnetic head, 1-b ... permanent magnet 2-a ... pulse current, 2-b ... pulse current 3-1 ... track on second magnetic layer 3-2 ... first 3-3 ... substrate, 3-4 ... first magnetic layer 3-5 ... second magnetic layer, 3-6 ... protective layer 4-3 ... magnetic field orientation device, 4-4 ... Magnetic head 5-2 ... Magnetic head

Claims (1)

[Claims] 1. A magnetic head for applying a coating material for a first magnetic layer made of a magnetic material having a high coercive force of more than 3000 Oersted on a base material made of a non-magnetic material before the magnetic coating material dries. Alternatively, a magnetic field is applied from the side opposite to the coated surface of the substrate by a permanent magnet to write identification magnetic information for preventing forgery on a part of the magnetic layer, and then the first magnetic layer is dried, and then the first magnetic layer is dried. Over 250 Oersted on magnetic layer 3000
A method of manufacturing a magnetic recording medium, comprising providing a second magnetic layer made of a magnetic material having a coercive force equal to or less than Oersted.