JPH0210516A - Magnetic recording medium and its manufacture - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having excellent charac- teristics against counterfeiting by inserting deciding information, which cannot be added or erased later, to a magnetic recording medium when a magnetic coating is applied. CONSTITUTION:On a substrate consisting of a non-magnetic substance, a first magnetic layer, which consists of a magnetic substance having higher coercive force than that of the ordinarily used magnetic recording material, namely, the higher coercive force than 3000 oersted, and to which discriminating magnetic information for counterfeiting prevention has been written beforehand, is provided. Further, a second magnetic layer consisting of the ordinarily used magnetic substance is laminated as the magnetic recording material. Since the first magnetic layer consists of the magnetic substance at the high coercive force, which is ordinarily used as the magnetic recording material, the magnetic recording and erasing is difficult by a generally used magnetic head or a permanent magnet excluding a period before the magnetic layer at the time of the coating is dried. Thus, the counterfeiting and unjust use are made difficult.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention improves productivity by inserting judgment information into a magnetic recording medium at the time of applying magnetic paint, which cannot be added or deleted later. The present invention provides a magnetic recording medium that is highly resistant to counterfeiting and provides a method for manufacturing the same.

<Prior Art> In recent years, magnetic recording media, particularly in the form of magnetic cards, have increasingly been used as money bills in place of small denomination coins. The biggest problem here is how to prevent unauthorized use due to falsification of magnetic information or duplication of cards.

Therefore, various measures are used to prevent unauthorized use, the simplest of which is a method using software that encrypts magnetically recorded information, but this method is not very effective in preventing unauthorized use.

Therefore, a method has been proposed in which the magnetic card itself has a function to prevent unauthorized use, which is more effective in preventing unauthorized use. These can be roughly divided into two types. That is, the first method is to hide the recorded magnetic information and make it unreadable, making it difficult to tamper with or copy the magnetic information, and the second method is to determine whether the magnetic card is genuine or not. This method prevents counterfeiting by incorporating an identification function into the card itself.

For example, known fraud prevention measures for the first method include multi-layering the magnetic recording section to shield legitimate information so that it cannot be read, and superimposing dummy information to analyze legitimate information. There are things that make it difficult. In addition, as a second method of preventing fraud, there is a method in which an optical bar code or a magnetic bar code is provided.

However, each of these methods has drawbacks and is still not sufficient. That is, the first method has drawbacks such as a complicated manufacturing process and a complicated recording/reading device. Furthermore, once the details of the concealment method are known, anyone familiar with magnetic recording will be able to read and analyze the information, thus making it possible to copy it.

The second method of fraud prevention cannot actually be used unless the card is a genuine card with correct determination information, even if the magnetic information can be forged. However, this method also has drawbacks in that the manufacturing process becomes complicated and the determination information reading device becomes complicated.

<Problems to be Solved by the Invention> The magnetic recording medium according to the present invention has the function of preventing unauthorized use by the second method, overcomes the drawbacks of the conventional method, and makes unauthorized use extremely difficult. magnetic recording medium,
The present invention provides a method for manufacturing the same.

Means for Solving the Problems> The present invention comprises a magnetic material having a coercive force higher than that normally used as a magnetic recording material, that is, a coercive force higher than 3000 oersteds, on a substrate made of a non-magnetic material. and a first magnetic layer on which identification magnetic information for preventing forgery is written in advance, and a second magnetic layer made of a magnetic material normally used as a magnetic recording material, that is, a magnetic material with a coercive force of 200 Oe or more and 3000 Oe or less. A magnetic recording medium is characterized in that layers are sequentially laminated, and when coating the first magnetic layer made of a magnetic material with a high coercive force of 3000 Oe or more, a magnetic head or permanent magnet is applied before the magnetic paint dries. By applying a magnetic field from the anti-coating side of the substrate, magnetic identification information for counterfeit prevention is written on a part of the magnetic layer.
This method of manufacturing a magnetic recording medium is characterized in that after drying the magnetic layer, a second magnetic layer made of a magnetic material with a magnetic field of 250 Oe or more and 3000 Oe or less is provided on the first magnetic layer.

The magnetic recording medium according to the present invention has two magnetic layers. During coating, before the magnetic paint dries, a magnetic field is applied from the opposite side of the substrate using a magnetic head or permanent magnet to record magnetic information on the magnetic layer as identification information to prevent counterfeiting, and then the magnetic layer is dried. Manufactured by

At this time, the magnetic layer may or may not be subjected to magnetic field orientation treatment in the pre-stage of magnetic recording.

When magnetic fine particles are in a magnetic paint and can move freely, their coercive force appears to be low, and they can be magnetized, that is, magnetically recorded, by only applying a very weak magnetic field. For example, after dispersing a magnetic material with a coercive force of 500 oersteds to form a magnetic paint, the hysteresis curve is measured using a VSM (vibrating sample magnetometer) in the paint state, that is, without drying. saturate. However, when coating and drying a paint on a non-magnetic substrate and measuring the magnetic hysteresis curve, even if the magnetic layer is oriented in a magnetic field and
Magnetic saturation does not occur even when an external magnetic field of Oersted is applied. That is, when the magnetic paint dries and the magnetic particles are immobilized,
It cannot be magnetized unless a sufficiently strong magnetic field is applied according to the coercive force.

The first magnetic layer of the magnetic recording medium manufactured using the manufacturing method according to this patent is made of a magnetic material with a high coercive force, which is commonly used as a magnetic recording material. Otherwise, it would be extremely difficult to perform magnetic recording and erase the recording using commonly used magnetic heads or permanent magnets.

For magnetic recording for writing the identification information for preventing forgery, a magnetic head such as that shown in 1-a of FIG. 1 may be used, for example. At this time, a pulse current such as 2-a or 2-b in FIG. 2 may be applied to the magnetic head as the recording current.

When performing magnetic recording using permanent magnets, it is sufficient to use permanent magnets arranged in a roll shape, for example, as shown in 1-b of FIG.

In this way, identification magnetic information for counterfeit prevention, which is very difficult to add or erase later, is written in the first magnetic layer, and after drying the first magnetic layer, the second magnetic layer is Apply layers. The second magnetic layer is made of a magnetic material having a coercive force that is commonly used as a magnetic recording material, and the coating method may be the same as in the production of a common magnetic recording medium. In the magnetic recording medium manufactured in this way, the first magnetic layer is kept away from the medium surface by the second magnetic layer. That is, when the magnetic recording medium is actually used, the first magnetic layer is moved away from the magnetic head by the second magnetic layer, so it is difficult to perform magnetic recording later or erase written magnetic information. is even more difficult and almost impossible. That is, the first magnetic layer contains card authenticity identification information for preventing counterfeiting that cannot be added or erased later, and ordinary rewritable magnetic recording information is stored in the second magnetic layer. This means that it is possible to manufacture a magnetic recording medium having the following characteristics.

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 of the present invention, and 3-b is a plan view of the magnetic recording medium of the present invention.
- It is a sectional view on the X axis. In the figure, 3-1 is a track on the second magnetic layer for normal magnetic recording,
3-2 is a track of 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 a first magnetic layer;
-5 is a second magnetic layer, and 3-6 is a protective layer.

<Examples> The present invention will be described in detail below with reference to Examples. In addition, all blending parts shall indicate parts by weight.

Example 1 A paint for the first magnetic layer was prepared with the following formulation.

After dispersing the above mixture in a ball mill for 8 hours, 5 parts of polyisocyanate resin was added and dispersion was further carried out for 1 hour to obtain a magnetic paint for the first magnetic layer.

Next, using the apparatus shown in FIG. 4, a paint for the first magnetic layer was applied to one side of the polyester film substrate so that the coating thickness after drying was 15 microns. In FIG. 4, 4-1 is a roll of base film, 4-2 is a coating head, and the magnetic layer coated by the coating head passes through a magnetic field orientation device 4-3 and is subjected to orientation treatment. Afterwards, magnetic information was recorded using the magnetic head 1-a in FIG. 1 at position 4-4 before entering the drying device.

Magnetic information was recorded on the magnetic card while synchronizing the line speed of the coating device and the pulse current flowing through the magnetic head so that the recording density was 100 FCI. After the identification magnetic information is written by the magnetic head of 4-4,
It is dried while passing through the drying device No. 4-5, and is wound up onto the reel No. 4-6 to complete the application of the first magnetic layer.

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 uniformly magnetized in the traveling direction, that is, in the coating direction. Magnetic recording was performed by selecting the polarity of the current so that the magnetic head applied a magnetic field in the opposite direction to the magnetization direction to the magnetic layer, and by passing a pulsed current 2-b in FIG. 2 through the magnetic head. At this time, the magnetic head and current intensity were selected so that a magnetic field of 500 oersted could be applied to the magnetic layer. After coating the first magnetic layer, the second magnetic layer is coated with a coating material for the second magnetic layer prepared by the method described below so that the coating thickness after drying is 15 microns. Obtained a recording medium.

After dispersing the mixture in a ball mill for 8 hours, 5 parts of polyisocyanate resin was added, and the mixture was further dispersed for 1 hour to obtain a magnetic paint for a second magnetic layer. Since the second magnetic layer is a magnetic layer for performing normal magnetic recording, coating may be performed in accordance with a normal method. The original fabric of the magnetic recording medium of the present invention manufactured in this way was punched out to JIS size,
A magnetic card was obtained, and using a magnetic card recording/reproducing device compatible with high coercive force, it was possible to reproduce magnetic information of 100 FCI recorded on the first magnetic layer at the time of coating the magnetic layer.

We attempted to override and erase this information using the same device, but it was not possible to record new information by overriding or erase the information recorded during coating. Normal magnetic recording was possible in the second magnetic layer.

Example 2 A paper roll made of aluminum, which is a non-magnetic material, was
A magnet roll having a cross section 1-b in FIG. 1 was prepared by arranging and pasting plate-shaped rubber magnets each having a width of 10 inches. The magnet was selected to be able to provide a magnetic field of 500 oersted when applying the magnetic layer. This magnet roll was set at the position 4-4 in FIG. 4 in place of the magnetic head 5-2 in FIG. 5 of Example 1, and a magnetic card was manufactured in the same manner as in Example 1.

Using a magnetic card recording/reproducing device compatible with high coercive force, the first
It was possible to reproduce the 10PCI magnetic information recorded on the magnetic layer when the magnetic layer was applied. We attempted to override and erase this information using the same device, but it was not possible to record new information by overriding or erase the information recorded during coating. Normal magnetic recording was possible in the second magnetic layer.

<Effects of the Invention> The magnetic recording medium according to the present invention is extremely difficult to counterfeit or fraudulently use because judgment information that cannot be added or erased later can be inserted at the time of applying the magnetic paint. In addition, the manufacturing equipment is simply a simple magnetic recording device added to the normal magnetic recording medium manufacturing equipment, and no special technology is required, resulting in high productivity.

[Brief explanation of the drawing]

FIG. 1 shows a magnetic head and a permanent magnet for writing magnetic information for identification into the first magnetic layer constituting the present invention, and FIG. 2 shows a state diagram of a pulse current applied to the magnetic head. FIG. 3 shows the structure of the magnetic recording medium of the present invention, FIG. 4 shows a magnetic paint coating device, and FIG. 5 is an enlarged view of the magnetic field orientation device and magnetic head shown in FIG. 4. 1-a...Magnetic head 1-b...Permanent magnet 2
-a...Pulse current 2-b...Pulse current 3
-1...Track 3-2...First on the second magnetic layer
7/ 3-3...Base 3-5...Second magnetic layer 4-3...Magnetic field orientation device 5-2...Magnetic head 3-4...First magnetic layer 3 -6...Protective layer 4-4...Magnetic head Fig. 1

Claims (1)

[Scope of Claims] 1) A first magnetic layer made of a magnetic material having a high coercive force of 3000 Oe or more on a substrate made of a non-magnetic material, and in which identifying magnetic information for preventing forgery is written in advance, and 2.
A magnetic recording medium characterized in that a second magnetic layer made of a magnetic material having a coercive force of 50 Oe or more and 3000 Oe or less is sequentially laminated. 2) When coating a first magnetic layer coating material made of a magnetic material with a high coercive force of 3000 Oe or more on a substrate made of a non-magnetic material, before the magnetic coating material dries, a magnetic head or a permanent magnet is used to A magnetic field is applied from the anti-coating side of the substrate to write identification magnetic information for counterfeit prevention on a part of the magnetic layer, and then the first magnetic layer is dried. 1. A method for manufacturing a magnetic recording medium, comprising providing a second magnetic layer made of a magnetic material having a coercive force of greater than or equal to Oe and less than 3000 Oe.