JP2000306233A - Magnetic recording medium and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a magnetic recording medium capable of preventing illicit actions such as forgery and falsification, capable of easily and reliably forming a compression pattern and excellent in magnetic characteristics such as output. SOLUTION: The magnetic recording medium has a 1st magnetic layer 31 with prescribed magnetic information temporarily recorded beforehand and a 2nd magnetic layer 35 formed on the 1st magnetic layer 31 directly or by way of a middle layer. The 2nd magnetic layer 35 is subjected to magnetic field orientation while it is in the undried state after coating and has fixed information recorded by the formation of a compression pattern of magnetic fine particles in accordance with the magnetic information of the 1st magnetic layer 31. The surface to be coated with the 2nd magnetic layer 35 is smooth.

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, high coercive force magnetic material such as Ba ferrite and Sr ferrite, high coercive force and low Curie point (high Hc and low Tc)
A magnetic recording medium or the like in which magnetic information is difficult to be erased by using a magnetic material of MnBi or a magnetic material containing MnBi has been 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 magnetically transferred to the second magnetic layer, which cannot be easily recorded by the magnetic head, 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. .

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.

In order to cope with such a problem, a medium utilizing magnetic transfer of magnetic information to an undried magnetic layer, that is, a first magnetic layer containing a magnetic material is formed on a base material. A magnetic recording medium has also been developed in which after performing magnetic recording on one magnetic layer, a second magnetic layer containing a magnetic material is applied and formed, and then subjected to a magnetic field orientation treatment in an undried state. In this magnetic recording medium, since the density pattern of the magnetic material is recorded as fixed information in the second magnetic layer using the magnetic recording pattern of the first magnetic layer, it is difficult to perform rewriting for the purpose of forgery or falsification. Yes, excellent security. However, to form the dense / dense pattern, it is necessary to determine how much the magnetic substance in the undried second magnetic layer is subjected to the action of the magnetization and the magnetic field during the coating for forming the second magnetic layer so that the magnetic substance is easily moved (magnetic powder). (Movement factor) is important, and in the conventional proposal, the factor was not always in a sufficient state.

The present invention has been made in view of such circumstances, and its purpose is to not only prevent fraudulent acts such as forgery and falsification, but also to form a dense pattern easily and reliably. An object of the present invention is to provide a magnetic recording medium having excellent magnetic characteristics such as output and a method for manufacturing the same.

[0013]

In order to achieve the above object, a magnetic recording medium according to the present invention comprises a first magnetic layer on which predetermined magnetic information is temporarily recorded in advance, and a first magnetic layer on which the predetermined magnetic information is temporarily recorded. A magnetic recording medium comprising a second magnetic layer formed directly on or through an intermediate layer, wherein the second magnetic layer comprises:
The second magnetic layer is coated and subjected to a magnetic field orientation treatment in an undried state, and fixed information is recorded by forming a fine and dense pattern of magnetic fine particles according to the magnetic information of the first magnetic layer. Is configured such that the surface to be coated is a smooth surface.

In a preferred embodiment of the present invention, the smooth surface on which the second magnetic layer is deposited has an average surface roughness R.
a is in the range of 500 to 4000 °.

In a preferred embodiment of the present invention, the intermediate layer is configured as a smooth surface promoting intermediate layer for forming a smooth surface.

Further, according to the present invention, a first magnetic layer is formed on a base material, and a master layer forming step of recording predetermined magnetic information on the first magnetic layer; Alternatively, a second magnetic layer is applied via an intermediate layer, and a magnetic field orientation treatment is performed while the second magnetic layer is in an undried state to form a dense / dense pattern of magnetic fine particles according to the magnetic information of the first magnetic layer. A fixed information forming step, wherein the surface to be coated with the second magnetic layer is subjected to a smoothing process for forming a smooth surface. Be composed.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic sectional view showing an example of a preferred embodiment of the magnetic recording medium of the present invention.

In FIG. 1, a magnetic recording medium 1 according to the present invention is shown.
Comprises a base material 2 and a recording layer 3 formed in a stripe shape on the base material 2. The recording layer 3 comprises a first magnetic layer 3.
1 and a second magnetic layer 35 directly formed thereon. In the drawing, the recording layer 3 employs a form in which the recording layer 3 is partially embedded in the base material 2.
May be formed on the surface.

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 31 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, sufficient magnetic output required for magnetic transfer cannot be obtained, or resistance to an external magnetic field is insufficient,
If it exceeds 6000 Oe, stable recording by the magnetic head becomes difficult, which is not preferable.

The magnetic material constituting the first magnetic layer 31 and having a coercive force in the range of 300 to 6000 Oe as described above is, for example, γ-Fe ₂ O ₃ , Co-coated γ-Fe ₂ O
_{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 31 is coated with a magnetic coating material 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 31 can also be formed.

When formed by a coating method, the thickness of the first magnetic layer 31 is about 1 to 50 μm, preferably about 3 to 20 μm as a dry film thickness.

In the embodiment shown in FIG. 1, the second magnetic layer 35 is coated directly on the first magnetic layer 31, but in the present invention, the second magnetic layer 35 is coated. It is characterized in that the coating surface 31a of the first magnetic layer 31 to be deposited is a smooth surface. The term “smooth surface” in the present invention refers to a smooth surface that acts so that the magnetic fine particles contained in the second magnetic layer 35 can easily move in an undried state of the coating film due to an external magnetic field orientation. Say. More specifically, the smooth surface (coating surface 31a) on which the second magnetic layer 35 is deposited has an average surface roughness Ra.
But 500 to 4000, more preferably 200 to 2
It is configured to be within the range of 000 °. This value is
If it exceeds 4000 °, there arises a problem that the level of the formation of the dense / dense pattern in the magnetic field orientation is not improved (the dense / dense pattern is not clear), and the magnetic properties such as output are not improved. On the other hand, the average surface roughness Ra is desirably set to a value as small as possible. However, in consideration of economical aspects such as processing costs and the actual technical level, the lower limit is set to 50.
0 °. In order to form such a smooth surface, usually,
What is necessary is just to perform the process of a calender process, a grinder, etc. of a film surface. In addition, a so-called transfer foil method in which a release agent is smoothly coated on a smooth base material, a magnetic layer is applied thereon and formed, and an adhesive layer formed thereon is integrally transferred. It is also possible to take.

In the present invention, the average surface roughness Ra
Is defined in JIS B0601-1982.

First magnetic layer 31 having such a smooth surface
As described above, the second magnetic layer 35 is directly provided on the substrate.

The second magnetic layer 35 contains a magnetic material (magnetic fine particles) in the coated film as a predetermined dense / dense pattern. It is preferable that the coercive force of the magnetic material (magnetic fine particles) contained in the second magnetic layer 35 is appropriately selected from the magnetic material (magnetic fine particles) in the range of 1 to 10,000 Oe. These can be appropriately selected from the magnetic fine particles described for the first magnetic layer 31 and used. In addition,. The relationship between the average particle diameter d of the magnetic fine particles contained in the second magnetic layer 35 and the average surface roughness Ra in the present invention is desirably Ra <d. This is to make the movement of the magnetic fine particles easy to move.

The second magnetic layer 35 is formed by applying a magnetic coating material in which the above-mentioned magnetic material is dispersed in an appropriate resin or ink vehicle onto the first magnetic layer 31 on which desired magnetic recording has been performed, by a gravure method or a roll method. It can be formed by coating according to a known coating method such as a knife edge method or the like, applying a magnetic orientation treatment by a magnetic field in a predetermined direction (stripe direction), and then drying the magnetic coating film. This second magnetic layer 35
Has fixed information composed of a dense / dense pattern of a magnetic material (magnetic fine particles). The method of forming the fixed information will be described in detail in a manufacturing method described later. It is preferable to use a solenoid type electromagnet alignment device as the alignment device used for the magnetic field alignment process.

The thickness of the second magnetic layer 35 is 1 to 50 μm,
Preferably it is about 3 to 20 μm.

FIG. 2 shows a modification of FIG. 2, an intermediate layer 40 is interposed between the first magnetic layer 31 and the second magnetic layer 35.
0 has the effect of smoothing the surface to be coated on which the second magnetic layer is deposited. That is, the intermediate layer 40 functions as a smooth surface promoting intermediate layer for forming a smooth surface. Such an intermediate layer 40 may be made of any of inorganic or organic materials as long as it functions as a smooth surface. However, in consideration of adhesiveness with a magnetic layer, an organic material, particularly Formed by coating polyurethane resin, butyral resin, vinyl chloride resin, vinyl acetate resin, vinyl chloride-vinyl acetate copolymer resin, polyester resin, cellulose resin, acrylic resin, styrene-maleic acid copolymer resin, etc. Things are desirable. Further, a radiation-curable resin such as an ultraviolet-curable type or an electron beam-curable type may be used.

When such an intermediate layer 40 is used, there is an advantage that an average surface roughness Ra in the above-mentioned range can be generally obtained only by coating, and a subsequent smoothing treatment is usually unnecessary. However, with coating alone,
If the average surface roughness Ra in the above range cannot be obtained, a predetermined smoothing process may be performed thereafter.

The thickness of the intermediate layer 40 is 1 to 10
μm, preferably about 1 to 4 μm. If this value is too large, the presence of the intermediate layer leads to spacing loss and adversely affects the magnetic output. If this value is too small, the surface cannot be maintained smooth. In FIG. 2, members having the same reference numerals as those in FIG. 1 indicate the same members (the same applies to the following drawings).

In the magnetic recording medium of the present invention,
Although the recording layer 3 is formed in a stripe shape on a part of the base material 2, the recording layer 3 is formed on the entire surface of one surface of the base material as shown in FIGS. It may be a configuration. Incidentally, when classified according to the method of forming the surface to be coated, FIG. 3 corresponds to FIG. 1 and FIG. 4 corresponds to FIG.

A magnetic material (magnetic fine particles) is formed on the second magnetic layer 35 of the magnetic recording medium 1 of the present invention having such a structure.
Is formed as fixed information.

In the present invention, on the 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 cellulose derivatives such as ethyl cellulose, cellulose nitrate, ethyl hydroxyethyl cellulose, cellulose acetate propionate, cellulose acetate, polystyrene, poly-α-
Styrene resin such as methylstyrene, or styrene copolymer resin, acrylic resin or methacrylic resin such as polymethyl methacrylate, polyethyl methacrylate, polyethyl acrylate, polybutyl acrylate or copolymer resin, rosin, rosin modified Color to be colored on binders such as maleic acid resin, rosin-modified phenol resin, rosin ester resin such as polymerized rosin, polyvinyl acetate resin, coumarone resin, vinyl toluene resin, vinyl chloride resin, polyester resin, polyurethane resin, butyral resin, etc. Various kinds of pigments are added as needed, and titanium oxide, alumina powder, micro silica, etc. are added so as to have a cleaning effect of the magnetic head as needed, and further, if necessary, a plasticizer, a stabilizer, a wax, Grease,
After adding a drying agent, a drying aid, a curing agent, a thickening agent, and a dispersing agent, knead well with a solvent or diluent, and then use a coloring paint or ink. It can be formed on a desired portion by a coating method such as a method or an offset method or a printing method.

Next, an embodiment of a method for manufacturing a magnetic recording medium according to the present invention will be described with reference to FIG. The embodiment shown in FIG. 5 is essentially the same as that of FIG.

First, the first magnetic layer 31 is formed on the substrate 2 (FIG. 5A). The first magnetic layer 31 is formed by applying a magnetic coating material obtained by dispersing a magnetic material having the above-described coercive force range in an appropriate resin or ink vehicle by a known coating method such as a gravure method, a roll method, or a knife edge method. It can be formed by coating and drying according to the method.
As the resin or ink vehicle, butyral resin, vinyl chloride / vinyl acetate copolymer resin, urethane resin, polyester resin, cellulose resin, acrylic resin, styrene / maleic acid copolymer resin, etc. are used.
If necessary, a rubber-based resin such as a nitrile rubber or a urethane elastomer is added. 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 31 can also be formed by using the above magnetic material by a vacuum deposition method, a sputtering method, a plating method, or the like.

Next, desired magnetic recording is performed on the first magnetic layer 31 (FIG. 5B). Thus, a magnetic pattern having a different magnetization direction is formed on the first magnetic layer 31. In the present invention, this step is particularly referred to as a master layer forming step of forming the first magnetic layer 31 on the base material and recording predetermined magnetic information on the first magnetic layer 31. The surface of the first magnetic layer 31 has been subjected to a smoothing process for forming a smooth surface. As a specific processing method, as described above, a calendar processing and the like are preferable examples. Providing the smooth surface promoting intermediate layer 40 is also one mode of the smoothing process.

Next, a second magnetic layer 35 is formed. First,
A magnetic coating material in which a magnetic material (magnetic fine particles) having the above-described coercive force is dispersed in an appropriate resin or ink vehicle is applied onto the first magnetic layer 31 on which desired magnetic recording has been performed.
The magnetic coating film 35a is formed by coating according to a known coating method such as a gravure method, a roll method, and a knife edge method (FIG. 5C). As the resin or ink vehicle used for the magnetic paint, those mentioned in the formation of the first magnetic layer 31 can be used. If necessary, dispersants, plasticizers, curing agents, antistatic agents, A pigment or the like may be appropriately contained in the magnetic paint.

Next, while the coating film is in an undried state, a magnetic field for orientation is applied in a certain direction (in FIG. 5, the direction of arrow (α)) to perform a magnetic field orientation treatment (FIG. 5D). As a result, the magnetic fine particles move and gather at a site where the direction of the magnetic field line where the magnetic coating line 35a is affected by the line of magnetic force generated from the first magnetic layer 31 and the direction of the orientation magnetic field (the direction of the arrow (α)) coincide. The dense portion 36 of the magnetic fine particles is formed in the magnetic coating film 35a. That is, in the portion where the magnetic field lines generated from the magnetic information recorded on the first magnetic layer 31 and the alignment magnetic field method coincide, the magnetic field line component is increased, and the magnetic fine particles in the magnetic coating film 35a gather to form a dense portion 36 in this portion. Is done. Conversely, the lines of magnetic force in the portions where the directions do not match are canceled out to form a coarse portion 37 (a portion where there is almost no magnetic fine particles). In the present invention, since the surface to be coated with the second magnetic layer is configured to be a smooth surface, the movement of the magnetic fine particles based on the orientation magnetic field is extremely smooth, and a clear dense-dense pattern is formed. Is done. The applied orientation magnetic field is in the range of 150 to 3000 G, so that the magnetic recording of the first magnetic layer 31 is not erased.
It can be set appropriately according to the magnetic material used.
Thereafter, the magnetic coating film 35a is dried to form the second magnetic layer 35 having fixed information composed of a dense / dense pattern of a magnetic material corresponding to the magnetic recording pattern of the first magnetic layer 31.

Next, a demagnetizing magnetic field for erasing the magnetic recording of the first magnetic layer 31 is applied in a certain direction, and the first magnetic layer 3
In addition to erasing the magnetic recording of No. 1, the fixed information of the second magnetic layer 35 is magnetized to obtain the magnetic recording medium 1 (FIG. 5).
(E)).

In the magnetic recording medium 1 of the present invention manufactured as described above, the fixed information written on the second magnetic layer 35 of the recording layer 3 is the density information formed by the movement of the magnetic fine particles in the magnetic coating film. Since it is composed of a pattern, it is not erased even when a strong magnetic field is applied.

In the present invention, the second magnetic layer 35
Can be arbitrarily set for each magnetic recording medium by magnetic recording on the first magnetic layer 31, so that it can be distinguished from other magnetic recording media.

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.

[0048]

Next, the present invention will be described in more detail with reference to examples. [Experimental example 1] Polyethylene terephthalate (E-22 manufactured by Toray Industries, Inc.) having a thickness of 188 µm was prepared as a substrate.
A magnetic paint for forming a first magnetic layer having the following composition is applied to one surface of this base material by a gravure coating method and dried,
A first magnetic layer having a thickness of 20 to 40 μm was formed. (Coating liquid for forming the 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 Part by weight Toluene 50 parts by weight Methyl isobutyl ketone 50 parts by weight Isocyanate-based curing agent 3 parts by weight Next, the surface of the first magnetic layer is uniformly ground with a grinder, and various kinds of materials shown in Table 1 below are prepared. Average surface roughness Ra
A sample provided with was prepared. Next, magnetic recording D was performed on the first magnetic layer at a write current of 1000 mA. The recording density at this time was 200 bpi (FM recording). Next, a magnetic paint for forming a second magnetic layer having the following composition was applied on the first magnetic layer by a gravure coating method to form a magnetic coating film. (Second coating liquid for forming a magnetic _{layer) · γ-Fe 2 O 3} ( coercivity = 300 Oe) ... 40 parts by weight vinyl / vinyl acetate copolymer resin chloride 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, a magnetic field (magnetic field) orientation treatment was performed by applying a DC magnetic field of 2000 G by a solenoid in one direction along the recording direction of the first magnetic layer. afterwards,
The second magnetic layer having a thickness of 15 μm was formed by drying the magnetic coating film. The second magnetic layer had fixed information D 'composed of a dense / dense pattern of a magnetic material corresponding to the magnetic recording D of the first magnetic 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 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, thereby erasing the magnetic recording D of the first magnetic layer. Then, the fixed information D 'portion composed of a dense and dense pattern of the magnetic material of the second magnetic layer was magnetized.

Thus, various magnetic recording samples as shown in Table 1 below (Examples I-1 to I-2; Comparative Example I-
1) was produced. Comparative Example I-1 was a sample in which the first magnetic layer was not subjected to the grinder treatment, and the thickness of the first magnetic layer was 20 μm. In addition, the sample which performed the grinder process has adjusted so that it may be set to the same conditions as Comparative Example I-1. This is the result of adjusting the cutting amount of the grinder process so that the same output is obtained for each sample in the magnetic writing after the formation of the first magnetic layer. In addition, the surface properties of the sample subjected to the grinder treatment are changed by changing the roughness of the cutting element (grinding wheel) of the grinder.

The magnetic output of the fixed information of each sample was measured, and the results are shown in Table 1 below. The magnetic output was compared and displayed as a relative value when Comparative Example I-1 was set to 1.00.

[0054]

[Table 1]

From the results shown in Table 1, the effect of the present invention is clear. [Experimental example 2] As a substrate, polyethylene terephthalate (E-22 manufactured by Toray Industries, Inc.) having a thickness of 188 µm was prepared.
A magnetic paint for forming a first magnetic layer having the following composition is applied to one surface of this base material by a gravure coating method and dried,
A first magnetic layer having a thickness of 20 μm was formed. At this time, the first
The average surface roughness Ra of the magnetic layer was 5000 °. (Coating liquid for forming the 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 Part by weight Toluene 50 parts by weight Methyl isobutyl ketone 50 parts by weight Isocyanate-based curing agent 3 parts by weight Next, on the first magnetic layer, a non-smooth surface promoting intermediate layer for forming a smooth surface is used. A magnetic polyurethane coating was applied to a thickness of 2 μm. The average surface roughness Ra of the coating film made of this polyurethane was 2,100 °. Next, magnetic recording D was performed on the first magnetic layer via the intermediate layer at a write current of 1000 mA. The recording density at this time was 200 bpi (FM recording). Next, a magnetic coating having the following composition for forming a second magnetic layer was applied on the intermediate layer by a gravure coating method to form a magnetic coating. (Second coating liquid for forming a magnetic _{layer) · γ-Fe 2 O 3} ( coercivity = 300 Oe) ... 40 parts by weight vinyl / vinyl acetate copolymer resin chloride 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, a magnetic field (magnetic field) orientation treatment was performed by applying a DC magnetic field of 2000 G by a solenoid in one direction along the recording direction of the first magnetic layer. afterwards,
The second magnetic layer having a thickness of 15 μm was formed by drying the magnetic coating film. The second magnetic layer had fixed information D 'composed of a dense / dense pattern of a magnetic material corresponding to the magnetic recording D of the first magnetic layer. As a result, a magnetic recording layer composed of a laminate of the first magnetic layer, the intermediate 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 magnetic field of 12000 G is applied to the magnetic recording layer of the magnetic recording medium in one direction along the recording direction of the first magnetic layer by a solenoid to erase the magnetic recording D of the first magnetic layer. Then, the fixed information D 'portion composed of a dense and dense pattern of the magnetic material of the second magnetic layer was magnetized.

Thus, a magnetic recording sample of the present invention (Example II-1) was produced. For comparison with the sample of the present invention, a comparative sample II-1 was prepared by removing the smooth surface promoting intermediate layer from Example II-1.

When the magnetic output of the fixed information of these two samples was measured, the output of Example II-1 was compared with that of Comparative Example II-
The output was 1.5 times that of the output of No. 1. Originally, the dense / dense pattern of the second magnetic layer is generated under the influence of the first magnetic layer. Therefore, it is not preferable to provide an intermediate layer that causes a spacing loss on the first magnetic layer. . Nevertheless, considering the results of Experimental Example 2, the effect of improving the surface properties of the coated surface of the present invention is as follows.
This is more than the disadvantageous situation of output reduction due to spacing loss, and as a result, it can be seen that extremely good output is obtained.

[0061]

As described in detail above, the magnetic recording medium of the present invention has a first recording medium in which predetermined magnetic information is temporarily recorded in advance.
A magnetic recording medium comprising a magnetic layer and a second magnetic layer formed directly or via an intermediate layer on the first magnetic layer, wherein the second magnetic layer is formed by coating the second magnetic layer. In the undried state, a fixed surface information is recorded by forming a magnetic fine particle according to the magnetic information of the first magnetic layer and subjected to a magnetic field orientation treatment, and the coated surface on which the second magnetic layer is applied. Has a smooth surface, so that it is possible to prevent fraudulent acts such as forgery and falsification, as well as to easily and surely form a dense / dense pattern, and to provide a magnetic recording medium having excellent magnetic properties such as output. Is obtained.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of an embodiment of a magnetic recording medium of the present invention.

FIG. 2 is a schematic sectional view showing another embodiment of the magnetic recording medium of the present invention.

FIG. 3 is a schematic sectional view showing another embodiment of the magnetic recording medium of the present invention.

FIG. 4 is a schematic sectional view showing another embodiment of the magnetic recording medium of the present invention.

FIG. 5 is a process chart showing one example of an embodiment of a method for manufacturing a magnetic recording medium of the present invention over time.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Magnetic recording medium 2 ... Base material 3 ... Recording layer 31 ... 1st magnetic layer 35 ... 2nd magnetic layer 40 ... Intermediate layer

 ──────────────────────────────────────────────────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 HA01 HA09 KA06 KA08 KA10 KA16 KA19 KA21 LA11 5D006 BA19 BA20 DA01 EA01 FA00 5D112 AA05 AA11 AA28 CC17 DD04

Claims (4)

[Claims] 1. A magnetic recording medium comprising: a first magnetic layer on which predetermined magnetic information is temporarily recorded in advance; and a second magnetic layer formed directly or via an intermediate layer on the first magnetic layer. In the second magnetic layer, the second magnetic layer is coated and subjected to a magnetic field orientation treatment in an undried state to form fixed information by forming a fine and dense pattern of magnetic fine particles according to magnetic information of the first magnetic layer. Wherein the surface to be coated on which the second magnetic layer is applied is a smooth surface. 2. The smooth surface on which the second magnetic layer is deposited,
2. The magnetic recording medium according to claim 1, wherein the average surface roughness Ra is in the range of 500 to 40,000. 3. The magnetic recording medium according to claim 1, wherein the intermediate layer is a smooth surface promoting intermediate layer for forming a smooth surface. 4. A step of forming a first magnetic layer on a base material and forming a master layer for recording predetermined magnetic information on the first magnetic layer; and forming a direct or intermediate layer on the first magnetic layer. Through the second
A fixed information forming step of applying a magnetic layer and performing a magnetic field orientation treatment while the second magnetic layer is in an undried state to form a dense / dense pattern of magnetic fine particles according to the magnetic information of the first magnetic layer. A method for manufacturing a magnetic recording medium, comprising: a surface to be coated on which the second magnetic layer is to be coated has been subjected to a smoothing process for forming a smooth surface. Method.