JP4910374B2 - Method for manufacturing anti-counterfeit information recording medium - Google Patents

Description

The present invention relates to a method for manufacturing a forgery-preventing information recording medium that has a magnetic recording layer in part and can easily verify authenticity.

In recent years, holograms and diffraction gratings that can express stereoscopic images and special decorative images using light interference and diffraction, or thin films with different optical properties are stacked as anti-counterfeiting means, and the color changes depending on the viewing angle OVD (Optically Variable Device) such as a multilayer thin film that causes (color shift) has come to be used. These OVDs are widely used as effective anti-counterfeiting means because they require sophisticated manufacturing techniques, have a unique visual effect, and can determine authenticity at a glance.

On the other hand, as a magnetic information recording medium, there is a plastic magnetic card such as a credit card or a cash card. These magnetic cards are required to have a function capable of preventing tampering and forgery. For example, the above-described OVD is disposed in a part of the magnetic card for preventing forgery. However, magnetic cards have a standard shape, etc., record information in a limited space, display information such as usage, owner, expiration date, etc., and also ensure design as a card. Therefore, the installation space of the OVD such as a hologram arranged as a forgery prevention measure is restricted. An OVD integrated magnetic card (see, for example, Patent Document 1) in which an OVD layer is stacked on a magnetic recording layer portion is provided so as to cope with such restrictions. The magnetic card having such a configuration is supposed to exhibit an excellent effect in terms of decoration.

However, in recent years, the reality is that forgery cannot be reliably prevented with only a simple structure in which OVDs are integrated. Certainly, it is difficult to forge the OVD itself, but many cases have been reported in which a similar one is obtained and affixed to a magnetic card and used illegally. It is very difficult to copy the OVD in exactly the same way from the viewpoint of equipment and technology, but it is possible to make it look the same as the real one by diverting a commercially available OVD.

As a method for reliably distinguishing the genuine article from the above-mentioned problem, it is assumed that a printing layer made of an ultraviolet light emitting type fluorescent ink is provided between the hologram forming layer of the hologram and the metal reflecting layer. Proposals have also been made (see, for example, Patent Document 2). The use of the hologram according to this configuration makes it possible to determine authenticity by using the light emission obtained when the ultraviolet rays are irradiated for verification.
JP-A-6-167920 JP 7-199783 A (6th page)

However, the above-described configuration in which the fluorescent ink layer is provided on the metal reflective layer causes a difference in level between the formed portion and the peripheral portion, and the transparency is different. Therefore, the decorative image caused by OVD And the color shift phenomenon is partly damaged. Moreover, if a commercially available OVD similar to the OVD in the object to be counterfeited is printed with fluorescent ink, a counterfeit product having substantially the same effect as that of the above configuration is relatively easy. There is also a problem that it is manufactured.

The present invention made to solve the above-described problems of the prior art is provided with a verification function layer for verifying the authenticity, and a part thereof is provided so that its existence cannot be visually confirmed. It is an object of the present invention to provide an anti-counterfeit information recording medium provided so as not to impair a decorative image or the like related to an OVD layer and a transfer foil used for manufacturing the same.

In order to solve the above problems, the invention according to claim 1 is a method of manufacturing an information recording medium having a laminated portion of an OVD layer and a magnetic recording layer on at least a part of a substrate. , A step of forming a release layer 24 by a release layer forming material on a support made of a transparent polyethylene terephthalate (PET) film, a step of applying and forming an OVD formation layer by a gravure method using an OVD formation layer forming material, roll embossing After forming an OVD relief pattern on the surface of the OVD forming layer 20a by the method, a thin film layer (OVD effect layer 20b) made of Sn is formed in a sea-island shape by a vacuum deposition method . Ultraviolet fluorescence that emits visible light when irradiated with ultraviolet rays process and gravure printing to form a verification function layer using an ink obtained by adding a material (verification function layer forming material), the verification function Forming a magnetic recording layer and an adhesive layer with a magnetic recording material and an adhesive so as to cover, further, the release layer forming material, the OVD forming layer forming material, and the verification function layer forming material The method of manufacturing an information recording medium, wherein the magnetic recording material and the adhesive are composed of the following materials.
[Peeling layer forming material]
Acrylic resin 15 parts by weight Polyethylene WAX 0.2 part by weight MEK (methyl ethyl ketone) 54.8 parts by weight Toluene 30 parts by weight [Material for forming OVD forming layer]
Urethane resin 25 parts by weight MEK 50 parts by weight Toluene 25 parts by weight [material for verification function layer formation]
Polyester resin 20 parts by weight UV-emitting fluorescent pigment 1 part by weight MEK 59 parts by weight Toluene 20 parts by weight [magnetic recording material]
γ-Fe ₂ O ₃ 30 parts by weight Vinyl acetate copolymer 3 parts by weight Polyurethane elastomer 20 parts by weight Toluene 15 parts by weight MEK 15 parts by weight [adhesive]
Vinyl chloride / vinyl acetate copolymer 15 parts by weight Acrylic resin 5 parts by weight Ethyl acetate 50 parts by weight Butyl acetate 30 parts by weight

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Since the anti-counterfeit information recording medium of the present invention is configured as described above, a verification function layer is provided so as not to damage the OVD and the presence thereof cannot be visually observed, thereby ensuring authenticity. It becomes possible to verify. Moreover, it is very difficult to manufacture a counterfeit product having the same verification function. The transfer foil of the present invention makes it possible to easily manufacture such an anti-counterfeit information recording medium.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory diagram showing a schematic cross-sectional configuration of a forgery prevention information recording medium according to the present invention, and FIG. 2 is an explanatory diagram of the transfer foil showing a schematic cross-sectional configuration of the transfer foil of the present invention.

The illustrated anti-counterfeit information recording medium is an information recording medium having a laminated portion of the OVD layer 2 and the magnetic recording layer 3 on at least a part of the base material 11, and the OVD layer 2 has optical transparency. In addition, at least a verification function layer 1 containing a luminescent material that emits visible light by an external stimulus is disposed on the lower surface thereof. The illustrated OVD layer 2 has a multilayer structure of an OVD formation layer 2a and an OVD effect layer 2b.

The verification function layer 1 is hidden by the OVD layer 2 and cannot be visually confirmed in a normal state. However, the verification function layer 1 emits visible light upon receiving an external stimulus, and is verified by confirming its presence. Is to be done. Although the verification function layer 1 may be provided over the entire surface as shown in FIG. 1, it is arranged so as to display an information pattern such as an arbitrary figure, number, character, etc., and corresponds to the information pattern in that portion. It is also possible to have predetermined information.

The verification function layer 1 is formed of a material obtained by dissolving or dispersing a light emitting material in a binder resin made of an organic polymer material.

Luminescent materials emit light in the visible range by external stimuli. Specifically, fluorescent light is emitted by external stimuli due to the action of ultraviolet rays, infrared rays, electron beams, X-rays, radiation, etc., and electric fields and chemical reactions. Such as body, phosphor and livestock. These luminescent materials are used by appropriately adding at least one of them to the binder resin constituting the verification function layer 1. The addition amount is preferably in the range of 0.5 to 80%. When the addition amount is 0.5% or less, sufficient light emission cannot be obtained, and when the addition amount is 80% or more, the binding force with the binder resin becomes weak.

Among various light emitting materials, the ultraviolet light emitting phosphor emits light having a spectrum peak in blue, green, red, or the like when excited with ultraviolet light and returns to a low energy level. Such phosphors are, for example, high-purity phosphors of zinc sulfide and alkaline earth metal sulfides with a trace amount of metals (copper, silver, manganese, bismuth, lead, etc.) to increase the emission. After adding as an activator, it is obtained by high-temperature firing. At this time, the hue, brightness, and degree of color attenuation can be adjusted by appropriately combining the base crystal and the activator.

On the other hand, infrared light emitting phosphors include an infrared visible conversion phosphor that emits visible light when excited by infrared light, and an infrared light emitting phosphor that emits light on a long wavelength side when excited by infrared light. The former infrared-visible conversion phosphor is a phosphor having a very special excitation mechanism, and emits visible light by using a plurality of infrared photons with low energy. There are two types of these light emission mechanisms, one is excited in multiple stages by activator ions, and the other is excited by multiple times of resonance energy transfer from the sensitizer. In the former type, light emission is observed when many host crystals having Er ³⁺ or Ho ³⁺ as an activator are excited, and in the latter type, the sensitizer Yb ³⁺ is used. Light emission is observed when infrared light is absorbed and the emission centers such as Er ³⁺ , Tm ³⁺ , and Ho ³⁺ are excited to a high level by multistage energy transfer.

In addition, a semiconducting substance having a high electron mobility, such as sulfide (ZnS, CdS) or oxysulfide (Y ₂ O ₂ S) as a base crystal, has photoconductivity as an electron beam excited phosphor. It is possible to use.

On the other hand, phosphors (Zn, Cd) S: Ag, which can emit light with high efficiency when irradiated with radiation such as X-rays and particle beams, and electroluminescent phosphors that directly convert electric energy into luminescence are also described above. Can be used as In addition to the above fluorescent materials, organic pigments and dyes such as diaminostilbenzyl sulfonic acid and other stilbene, diaminodiphenyl, imidazole, thiazole, coumarin, naphthalimide, and thiophene are used. Also good.

Among these, since it is relatively easy to manufacture or obtain a verification machine for verifying authenticity, a fluorescent material that emits light by irradiation with ultraviolet rays or infrared rays is preferable, but considering that it can be obtained at low cost, ultraviolet rays are preferred. A luminescent material that emits fluorescence is more preferable.

The verification function layer 1 containing such a light emitting material is formed with a thickness of about 0.1 to 50 μm by a known printing method such as a gravure printing method or a screen printing method or a coating method.

The OVD layer 2 is laminated over the entire verification function layer 1 having such a configuration. This OVD layer 2 is layered with holograms and diffraction gratings that can express stereoscopic images and special decorative images using light interference and diffraction, or thin films with different optical characteristics. It is a layer made of OVD such as a multilayer thin film that causes (shift).

More specifically, a relief hologram in which interference fringes of light are recorded on a plane as a fine uneven pattern, a volume hologram in which interference fringes are recorded in the volume direction, or a ceramic or metal material having different optical characteristics. An optical multilayer thin film or the like in which thin films are stacked and changes in color (color shift) depending on the viewing angle. Among these, in consideration of mass productivity and cost, a relief hologram (diffraction grating) or a multilayer thin film is preferably used.

Relief-type holograms (diffraction gratings) are generally obtained by mass-production using a duplication press plate produced from a relief-type master plate having a fine diffraction pattern produced by an optical imaging method. .

That is, the OVD formation layer 2a is obtained by pressing such a press plate against a thin film formed with a uniform thickness and forming a concave / convex pattern of the press plate on the surface thereof. Therefore, the OVD forming layer 2a is formed of a constituent material such as a thermoplastic resin, a thermosetting resin, an ultraviolet ray or an electron beam curable resin, which can be shaped with a concavo-convex pattern. More specifically, polyisocyanate is added as a crosslinking agent to a thermoplastic resin such as an acrylic resin, an epoxy resin, a cellulose resin, a vinyl resin, an acrylic polyol or a polyester polyol having a reactive hydroxyl group, and then crosslinked. It is formed from a urethane resin, a thermosetting resin such as a melamine resin or a phenol resin, an ultraviolet ray or electron beam curable resin such as epoxy (meth) acrylic or urethane (meth) acrylate, or a composite thereof. It is also possible to use materials other than the above as long as the uneven pattern can be shaped.

In forming these OV D, or 3D hologram for reproducing a three-dimensional image, a technique of production of such a grating image to give high bright feeling to express a diffraction grating in a fine dot used. Recently, a method of forming minute dots of a diffraction grating with a specific shape such as a star shape, a method of drawing with fine characters that cannot be seen with the naked eye, called micro characters, and a plurality of images that are completely different depending on the viewing angle are expressed. A technique called changing, a technique of forming a diffraction grating with a saw blade shape called a blazed grating with high light diffraction efficiency, and the like have been developed. These techniques can also be used as appropriate.

On the other hand, the OVD effect layer 2b provided on the lower surface of the OVD formation layer 2a having the above-described configuration is, for example, a layer formed from a material having a refractive index different from that of the polymer material constituting the OVD formation layer 2a having a relief surface. Thus, this layer is provided to increase the diffraction efficiency of the OVD image.

The anti-counterfeit recording medium of the present invention is a medium in which a specific external stimulus is applied when verifying its authenticity, and the light emission state is verified to determine authenticity. It is necessary to provide a transparent material or a structure that partially transmits light.

Accordingly, the constituent material of the OVD effect layer 2b is different from the OVD formation layer 2a described above, and has a high refractive index material such as transparent TiO ₂ , Si ₂ O ₃ , SiO, Fe ₂ O ₃ , ZnS, etc. Examples thereof include metal materials such as Al, Sn, Cr, Ni, Cu, and Au, which can obtain a higher reflection effect than these materials.

The OVD effect layer 2b may be provided on one surface using these materials and by a known thin film forming technique such as vacuum deposition or sputtering so that the film thickness is about 50 to 10,000 mm. It is also possible to form predetermined information such as patterns, numbers, characters, etc. in an inherent information pattern. Thereby, while improving designability, processing can be complicated and a higher forgery prevention effect can be exhibited.

As a method of forming the information pattern-shaped OVD effect layer 2b, (1) a soluble resin is formed in a pattern on the OVD formation layer, and further provided so as to cover the metal thin film thereon; A method of cleaning and removing the metal thin film layer of the portion, (2) After providing an information pattern-shaped etching resistant film using an acid resistant or alkaline resistant resin on the metal thin film layer, a part of the metal thin film layer is acidified (3) After applying a thin film made of a resin material that dissolves or becomes difficult to dissolve by exposing light, and then exposing the thin film to light through a desired mask. And a method of removing unnecessary portions by washing or etching, and (4) a method of printing the atomized OVD forming layer material in a pattern by various printing techniques. The above is only an example, and the present invention is not limited to these, and any other method for partially forming a metal thin film layer can be used as appropriate.

The use of a metal thin film as the OVD effect layer 2b is excellent in that it provides a light reflection effect and a function of hiding the verification function layer 1. However, since a metal thin film is difficult to transmit light, in forming the metal thin film, (1) a thin film having a thickness enough to transmit light is provided, or (2) fine metal thin film portions are arranged in a sea island shape. It is necessary to consider such as making the OVD effect layer partially transmitting light. The degree of light transmission of the OVD effect layer 2b varies depending on the degree of light emission of the verification function layer 1, but it is desirable to transmit 5% or more of light. On the other hand, in order to hide the verification function layer 1, the transmittance is preferably 80% or less.

As a method of providing the metal thin film layer (OVD effect layer) formed by arranging the fine metal thin film portions in a sea-island shape as described above, in addition to the vacuum evaporation method, (1) a uniformly formed metal thin film is partially And (2) a method of printing and providing a sea-island pattern made of a metallic glossy ink in which metal fine particles are dispersed in an organic polymer resin. These methods can be said to be suitable methods in the present invention because they can improve the design properties by changing the design and shading (light transmittance). Furthermore, it is difficult to confirm each minute thin film portion with the naked eye, and it can be confirmed with a magnifying glass or the like, and a verification function can be given to each. In order to enhance the metallic luster, it is also possible to provide a black layer with a black dye or pigment added to the lower surface of the OVD effect layer so that transmitted light is not scattered.

On the other hand, when the multilayer thin film having the color shift effect described above is adopted as the OVD formation layer, as described above, it is composed of a large number of thin film layers having different optical characteristics, and is appropriately laminated with a metal thin film, a ceramic thin film, or these. A composite multilayer thin film is applied. For example, when thin films having different refractive indexes are stacked, a high refractive index thin film and a low refractive index thin film may be combined, or a specific combination may be stacked alternately. These combinations are determined in consideration of optical characteristics such as refractive index, reflectance, and transmittance of the materials used, required weather resistance, interlayer adhesion, and the like.

As a means for forming a thin film layer, a normal vacuum deposition method capable of controlling a film thickness, a film forming speed, the number of stacked layers, an optical film thickness (= n · d, n: refractive index, d: film thickness) and the like. However, other thin film forming means can be used as appropriate as long as it is a known means. In the multilayer thin film method, as described in the previous examples of holograms and diffraction gratings, a part is formed into an information pattern such as an arbitrary pattern, figure, letter, number, etc., resulting from the formed pattern. It is possible to provide information, to provide a sea-island structure, or to form a specific minute information pattern in the shape of each minute thin film portion itself.

On the other hand, the magnetic recording layer 3 provided in the lower layer of the verification function layer 1 is provided by a printing or coating method using a known magnetic paint, for example. Examples of magnetic paints include γ-Fe ₂ O ₃ , Co-containing Fe ₂ O ₃ , Fe ₃ O ₄ , barium ferrite, strontium ferrite, Co · Ni · Fe · Cr or alloys thereof, rare earth Co magnetism And the like are dispersed and kneaded in a polymer resin such as butyral resin, vinyl chloride / vinyl acetate copolymer, urethane resin. Moreover, it is also possible to add together chemical substances and pigments, such as surfactant, a silane coupling agent, a plasticizer, wax, silicone oil, and carbon, as needed.

In addition to those formed with such a magnetic paint, a metal thin film type magnetic recording layer formed by vapor deposition that has been attracting attention in recent years from the viewpoint of high-density recording, particularly oblique vapor deposition, can also be used. Specific examples thereof include a magnetic recording layer made of an obliquely deposited film of nickel, cobalt, or an alloy thereof.

Next, the transfer foil of the present invention that makes it possible to easily manufacture the anti-counterfeit recording medium of the present invention will be described. As shown in FIG. 2, in the transfer foil of the present invention, a release layer 24, an OVD layer 20, a verification function layer 21, a magnetic recording layer 23, and an adhesive layer 25 are sequentially laminated on one side of a support 28. It will be.

By using the transfer foil having such a configuration, it becomes possible to simultaneously form a genuine verification part and a magnetic recording part in a forgery prevention information recording body using a hot stamp transfer machine or a hot roll transfer machine. . That is, the transfer foil adhesive layer can be brought into contact with a part of the base material constituting the forgery-preventing recording medium, embedded and bonded by heat and pressure, and then the transfer foil support can be peeled off. . The release layer 24 is a layer that is peeled off from the support 28 and is a layer for protecting the OVD layer 20 thereafter. The adhesive layer 25 has a function of adhering to the base material constituting the forgery-preventing recording medium with heat and pressure. The support 28, the release layer 24, and the adhesive layer 25 are composed of the same materials as those constituting each layer of a known transfer foil. In addition, as a method for forming each layer using them, a conventionally used method can be appropriately employed.

As described above, the forgery-preventing recording medium and the transfer foil according to the present invention have been described. However, each layer may be colored or printed on the surface in order to improve the design. In consideration of adhesiveness between layers, an adhesive anchor layer may be provided between the layers. Furthermore, a black dye or pigment may be added to the layer located on the lower surface of the verification function layer so as to prevent the transmitted light from being scattered in order to enhance the metallic luster.

Hereinafter, the present invention will be described in detail with specific examples.

On the support 28 made of a transparent polyethylene terephthalate (PET) film having a thickness of 25 μm, the release layer 24 is formed by a release layer forming material having the following composition, and each of the OVD formation layers 20a is formed by an OVD formation layer forming material. It was applied and formed by a gravure method so that the thickness became 1 μm. Next, an OVD relief pattern was formed on the surface of the OVD formation layer 20a by a roll embossing method, and then a thin film layer (OVD effect layer 20b) made of Sn having a thickness of 0.05 μm was provided in a sea island shape by a vacuum deposition method. After that, using an ink added with an ultraviolet fluorescent material that emits visible light when irradiated with ultraviolet rays, the letters “OK” were gravure-printed with a thickness of 3 μm to form the verification function layer 21. Next, a magnetic recording layer 23 and an adhesive layer 24 are provided with a thickness of 10 μm and 2 μm, respectively, with a magnetic recording material having the following composition and an adhesive so as to cover the verification function layer 21, thereby producing a transfer foil of the present invention. (See FIG. 2).
[Peeling layer forming material]
Acrylic resin 15 parts by weight Polyethylene WAX 0.2 part by weight MEK (methyl ethyl ketone) 54.8 parts by weight Toluene 30 parts by weight [Material for forming OVD forming layer]
Urethane resin 25 parts by weight MEK 50 parts by weight Toluene 25 parts by weight [material for verification function layer formation]
Polyester resin 20 parts by weight UV-emitting fluorescent pigment 1 part by weight MEK 59 parts by weight Toluene 20 parts by weight [magnetic recording material]
γ-Fe ₂ O ₃ 30 parts by weight Vinyl acetate copolymer 3 parts by weight Polyurethane elastomer 20 parts by weight Toluene 15 parts by weight MEK 15 parts by weight [adhesive]
Vinyl chloride / vinyl acetate copolymer 15 parts by weight Acrylic resin 5 parts by weight Ethyl acetate 50 parts by weight Butyl acetate 30 parts by weight

A transfer foil according to Example 2 for comparison was produced using the same material and method as in Example 1 except that the OVD effect layer was formed of an evaporated thin film made of aluminum having a thickness of 0.05 μm.

After providing a release layer with a thickness of 1 μm using a release layer constituting material having the above composition on a support made of a transparent PET film having a thickness of 25 μm, using the verification function layer forming material having the above composition Then, the letters “OK” were gravure printed with a thickness of 3 μm to form a verification function layer. Then coating with a thickness of 1μm to OVD forming layer by OVD forming layer forming material having the composition described above, to form, then, after Fugata the OVD relief pattern by roll embossing method on the upper surface, a vacuum evaporation method using A thin film layer (OVD effect layer) made of aluminum having a thickness of 0.05 μm was provided thereon. Finally, a magnetic recording layer and an adhesive layer were provided with thicknesses of 10 μm and 2 μm, respectively, to produce a transfer foil according to Example 3 for comparison. The materials and methods used were the same as in Example 1.

Each of the transfer foils according to Examples 1 to 3 obtained as described above was pressure-bonded and bonded to a vinyl chloride card having a thickness of 0.8 mm using a hot roll, and then a support for the transfer foil. The anti-counterfeit information recording medium of the present invention and information recording media according to Examples 2 and 3 for comparison were produced.

Each of these information recording media was irradiated with ultraviolet rays, and the light emission state was confirmed. Table 1 shows the results and the status of visual appearance under visible light.

表からの明らかなように、実施例２の情報記録媒体においてはＯＶＤ効果層に光が遮蔽され発光が観察されず、実施例３の情報記録媒体においては検証機能層が目立ち、目視でもその存在が確認できてしまい、かつその部分のＯＶＤの画像を損なう構成となっていた。一方、実施例１に係る偽造防止情報記録媒体は検証機能層の有無が可視光下（目視）では判らず、紫外線照射により真偽の検証が可能な媒体であった。この実験により実施例２および３の手法で情報記録媒体が偽造されたとしても、その外観あるいは検証状況から、容易に偽造品と判断できることが分かった。

As is clear from the table, in the information recording medium of Example 2, light is shielded by the OVD effect layer and no light emission is observed, and in the information recording medium of Example 3, the verification function layer is conspicuous and visually present. Can be confirmed, and the OVD image in that portion is damaged. On the other hand, the anti-counterfeit information recording medium according to Example 1 was a medium in which the presence or absence of the verification function layer could not be determined under visible light (visual observation), and authenticity verification was possible by ultraviolet irradiation. From this experiment, it was found that even if the information recording medium was counterfeited by the methods of Examples 2 and 3, it could be easily determined to be a counterfeit product from its appearance or verification status.

It is explanatory drawing which shows the general | schematic cross-section structure of the forgery prevention information recording medium of this invention. It is explanatory drawing which shows the general | schematic cross-section structure of the transfer foil of this invention.

DESCRIPTION OF SYMBOLS 11 ... Base material 1, 21 ... Verification function layer 2, 20 ... OVD layer 2a, 20a ... OVD formation layer 2b, 20b ... OVD effect layer 28 ... Support body 3, 23 ... Magnetic recording layers 4, 24 ... Peeling layers 5, 25 ... Adhesive layers

Claims (1)

A method for manufacturing an information recording medium having a laminated portion of an OVD layer and a magnetic recording layer on at least a part of a substrate, wherein a release layer forming material is formed on a support made of a transparent polyethylene terephthalate (PET) film. Forming a release layer 24;
Applying and forming an OVD forming layer by a gravure method using an OVD forming layer forming material;
A step of forming an OVD relief pattern on the surface of the OVD formation layer 20a by a roll embossing method, and then providing a thin film layer (OVD effect layer 20b) made of Sn in a sea island shape by a vacuum deposition method ;
A process of forming a verification functional layer by gravure printing using an ink (a material for forming a verification functional layer) that contains an ultraviolet fluorescent material that emits visible light when irradiated with ultraviolet rays ;
Forming a magnetic recording layer and an adhesive layer with a magnetic recording material and an adhesive so as to cover the verification function layer,
Further, the release layer forming material, the OVD forming layer forming material, the verification function layer forming material, the magnetic recording material, and the adhesive are composed of the following materials. Production method.
[Peeling layer forming material]
Acrylic resin 15 parts by weight Polyethylene WAX 0.2 part by weight MEK (methyl ethyl ketone) 54.8 parts by weight Toluene 30 parts by weight [Material for forming OVD forming layer]
Urethane resin 25 parts by weight MEK 50 parts by weight Toluene 25 parts by weight [material for verification function layer formation]
Polyester resin 20 parts by weight UV-emitting fluorescent pigment 1 part by weight MEK 59 parts by weight Toluene 20 parts by weight [magnetic recording material]
γ-Fe ₂ O ₃ 30 parts by weight Vinyl acetate copolymer 3 parts by weight Polyurethane elastomer 20 parts by weight Toluene 15 parts by weight MEK 15 parts by weight [adhesive]
Vinyl chloride / vinyl acetate copolymer 15 parts by weight Acrylic resin 5 parts by weight Ethyl acetate 50 parts by weight Butyl acetate 30 parts by weight

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