JPH08185648A - Thermosensitive transfer medium and information recording medium - Google Patents

Abstract

PURPOSE: To provide a thermosensitive transfer medium which allows the easy production of an information recording medium having arbitrary and desired magnetic information by transferring the magneto-optical thin film included in the transfer foil of a thermosensitive transfer medium of a separate body to the arbitrary place of an object, has an additional information function to permit the recording of additional information and a bar code information function, has a magneto-optical effect and makes possible the reading of the magnetic information as optical information. CONSTITUTION: This thermosensitive transfer medium 1 consists of the lamination of a base material 10 and the transfer foil 3. The transfer foil 3 consists of the lamination of a release film 6, a magneto-optical thin film 4 and an adhesive film 5 and, if necessary, a light reflection film. The transfer foil 3 is transferred to the information recording medium 2 side at need. The magneto- optical thin film 4 consists of a film contg. the powder of bismuth rare earth iron garnet and the film contg. the magnetic powder of the high-concn. bismuth substd. iron garnet particulates is used in order to improve light transmittance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer medium containing a magneto-optical thin film having a magneto-optical effect in a transfer foil for thermal transfer to an object, and a transfer formation using the magneto-optical thin film as an information recording layer. In particular, the present invention relates to a heat-sensitive transfer medium and an information recording medium to which information can be added, which is used as a magnetic code and which has an excellent magneto-optical effect.

[0002]

2. Description of the Related Art Conventionally, various information recording media on which marks, magnetic bar codes, characters and other magnetic patterns are recorded have been used. As a technique for forming an information recording layer on the surface of this information recording medium, various types have been known as publicly known techniques. For example, one that is transferred using a normal magnetic transfer foil, one that prints a magnetic barcode, one that is formed by transferring a magnetic barcode, or a magneto-optical film (MO film) having a magneto-optical effect is deposited or The things to apply are raised.

[0003]

The information recording media formed by the various methods described above have their respective characteristics, but each has some problems. That is, although various functions are required as an information recording medium, it is important that the information recording medium has an additional information function and a bar code information function, as well as being capable of converting magnetic information into optical information and having an anti-counterfeiting effect. Here, the additional information function is a function that allows information to be written later by using a magnetic head or the like, and is a function necessary for successive update of information. The bar code information function is a function capable of forming a magnetic bar code used as the most general information pattern. Although the present invention will be described in detail later by comparing the present invention with the above-mentioned various techniques, none of the conventional ones satisfies all the above-mentioned functions. Also,
As an information medium having a magneto-optical effect, a magneto-optical thin film (MO
Film) is used, but the conventional one has insufficient light transmittance, and since it is formed by vapor deposition or coating,
It was not possible to freely form additional information or barcode information as individual information that differs for each medium.

The present invention was devised in view of the above circumstances, and it is possible to transfer a magnetic pattern of an arbitrary shape to an arbitrary position of an object, and at the same time, to add the above-mentioned additional information function and bar code information. It is an object of the present invention to provide a heat-sensitive transfer medium and an information recording medium which can exhibit their functions sufficiently and are excellent in magneto-optical effect.

[0005]

In order to achieve the above object, the present invention provides a thermal transfer medium having at least a base material and a transfer foil laminated on the base material, which is used for thermal transfer processing of an object. There, the transfer foil is mainly composed of a magneto-optical thin film containing a magnetic powder having a magneto-optical effect, and is peelable from the base material by local heating, and adheres to the object to form a desired magneto-optical pattern. To form a heat-sensitive transfer medium on the surface of the object. More specifically, the magnetic powder is made of bismuth rare earth iron garnet. In addition, the transfer foil includes a heat-sensitive adhesive film formed on the upper surface of the magneto-optical thin film. Further, the transfer foil includes a heat-sensitive peeling film formed on the lower surface of the magneto-optical thin film.
Further, the transfer foil includes a light reflection film formed on an upper surface of the magneto-optical thin film having light transmittance. Further, the present invention has an information recording layer consisting of a pattern of a magneto-optical thin film thermally transferred from a transfer foil of the thermal transfer medium, and the magneto-optical thin film contains magnetic fine particles composed of bismuth rare earth iron garnet, It constitutes an information recording medium capable of optically reading information.

[0006]

The magneto-optical thin film contained in the heat-sensitive transfer medium is formed by dispersing the powder of bismuth rare earth iron garnet in the binder resin and has good light transmittance. By forming this from the one using the high-concentration bismuth-substituted iron garnet fine particles, the light transmittance is improved and the magneto-optical effect can be further enhanced. Since the transfer foil of the heat-sensitive transfer medium is formed so as to be peelable from the base material and has an adhesive film, it can be freely transferred to the information recording medium side by heat-sensitive transfer. Further, since the information recording layer of the information recording medium is formed by transfer, it is possible to freely attach a barcode. In particular, since this transfer foil has a magneto-optical effect, it can not only write additional information magnetically, but also can read information optically, so that it has a true / false determination function when applied to an information recording medium such as a card. Can be given.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a laminated structure and the like of an embodiment of the thermal transfer medium and the information recording medium of the present invention, FIG. 2 is a sectional view showing a specific example of each film shown in FIG. 1, and FIG. FIG. 4 is a sectional view showing a laminated structure of another embodiment of the thermal transfer medium, FIG. 4 is a perspective view showing an example of an information recording medium to which a magnetic bar code is transferred,
5 is a perspective view showing an example of an information recording medium with an arbitrary identification mark, FIG. 6 is a block diagram of a magnetic recording / reproducing apparatus used for reading a magnetic pattern or the like formed on the information recording medium, and FIG. FIG. 8 is a configuration diagram of a mark visualization device, and FIG. 8 is a flowchart for explaining a method for producing high-concentration bismuth-substituted iron garnet fine particles used in the magneto-optical thin film of the present invention.

(Embodiment 1) First, the laminated structure of the heat-sensitive transfer medium and the information recording medium of this embodiment will be described with reference to FIG. The thermal transfer medium 1 comprises a base material 10 and a transfer foil 3 provided thereon. The transfer foil 3 is composed of a release film 6 arranged on the base material 10 side, a magneto-optical thin film (MO film) 4 thereon, and an adhesive film 5 on the uppermost portion. The transfer foil 3 is peeled from the base material 10 during transfer. This heat-sensitive transfer medium is processed into, for example, a ribbon shape and transferred using a thermal head.

The information recording medium 2 is an information recording medium base 7
And the information recording layer 8 transferred thereon. The information recording layer 8 is formed by transferring the magneto-optical thin film 4 of the transfer foil 3.

The substrate 10 is made of a PET (polyethylene terephthalate) film having a thickness of 6 [μm].

The peeling film 6 is made of a mixed film of thermoplastic acrylic and polyester, and has a film thickness of about 0.5 [μm] to 5 [μm].

The magneto-optical thin film 4 is composed of a composition containing bismuth rare earth iron garnet powder, a copolymer of vinyl chloride and vinyl acetate (vinyl chloride), and a solvent.
It is 5 [μm] to 10 [μm].

The adhesive film 5 is made of a mixture of polyester and a solvent, and is a coating film of 0.5 [μm] to 4 [μm].

The above films are coated by using a coater such as a gravure roll coater or a knife coater.

FIG. 2 shows a specific structure of the heat-sensitive transfer medium 1 shown in FIG. The heat-sensitive transfer medium 1a comprises a base material 10, a heat-sensitive peeling film 6a, a magneto-optical thin film 4a, a heat-sensitive adhesive film 5a and the like. The heat-sensitive release film 6a is made of thermoplastic acrylic [for example, BR-1.
16, Mitsubishi Rayon Co., Ltd.] 15 parts (parts by weight) and polyester [eg, Byron 200, Toyobo Co., Ltd.]
3 parts) and 82 parts of a solvent [for example, MEK / toluene] are mixed and coated with a gravure roll coater or the like. The resin has Tg (glass transition temperature) = 70.
Anything below [° C] can be used. The magneto-optical thin film 4a is composed of bismuth rare earth iron garnet or 10 parts of high-concentration bismuth-substituted iron garnet particles described later, 10 parts of a vinyl chloride / vinyl acetate copolymer resin [VAGH: Union Carbide Co.], and a solvent (MEK / Toluene) 80
It is composed of a mixture of parts coated by a coater such as a gravure roll coater. In addition to the above-mentioned copolymer resin of vinyl chloride and vinyl acetate, resins such as polyester, acrylic and urethane can be used. Heat-sensitive adhesive film 5a
Is 15 parts of polyester [for example, Byron 200, manufactured by Toyobo Co., Ltd.] and silica particles [Syloid 244,
Fuji Devison Co., Ltd.] 1 part and a mixture of 84 parts of solvent (MEK / toluene) was applied by a gravure roll coater or the like.

(Embodiment 2) FIG. 3 shows another embodiment of the present invention. The thermal transfer medium 1b includes a base material 10 and
The transfer foil 3b is composed of a peeling film 6, a magneto-optical thin film 4, a light reflecting film 9 and an adhesive film 5. It is characterized in that a light reflection film 9 is laminated above the magneto-optical thin film 4 as compared with the first embodiment. The light reflecting film 9 is formed by depositing a metal such as Al or Sn and has a thickness of 50 [nm] to 300 [nm]. When transferred, the light reflecting film 9 is arranged below the magneto-optical thin film 4. The light reflecting film 9 is effective for reflecting incident light and optically reproducing the magnetic recording content. The present embodiment is advantageous in that the magneto-optical pattern of the reflective film can be formed regardless of the background color on the information recording medium side.

FIGS. 4 and 5 simply show an embodiment of the information recording medium 2. When the thermal transfer media 1, 1a, 1b shown in FIGS. 1, 2 and 3 are heated by a heating means such as a thermal head, the peeling films 6, 6a are melted and the transfer foils 3, 3b are transferred from the base material 10 side. It can be easily peeled off. The information recording layer 8 is formed by bringing the adhesive films 5 and 5a side into contact with the information recording medium base 7 of FIG. FIG.
Shows the case where a magnetic bar code is adopted as the information recording layer 8, and FIG. 5 shows the case where an arbitrary identification mark 8a is adopted. Of course, other pictures, characters, marks, patterns, etc. may be used. In FIG. 5, the information recording layer 8b indicated by the dotted line indicates an additional information writing area that utilizes the fact that the information recording media 2 and 2a of this embodiment have the additional information function. As described above, it is possible to easily manufacture the information recording medium 2, 2a or the like provided with a desired arbitrary pattern or the like.

Table 1 shows a comparison of the effects of the information recording medium 2 of the present invention having the magneto-optical thin film (MO film) 4 produced as described above and the information recording medium produced by various conventional production methods. .

◎

[Table 1]

In Table 1, the above-mentioned additional information function, bar code information function and magneto-optical effect can be cited as effects. In addition, Table 1 shows the conventional techniques compared with the invention product.
Ordinary transfer foil, magnetic bar code by printing, magnetic bar code by transfer, MO by evaporation as shown in
Membranes and MO films by coating are mentioned. In the table, ∘ marks indicate those having the above-mentioned function (possible), and x marks indicate those having no function (impossible). The information recording media 2 and 2a of the present invention have both an additional information function and a bar code information function, and it is possible to additionally write arbitrary information later and easily form a magnetic bar code. Further, since the magnetic particles of bismuth rare earth iron garnet are used, the magneto-optical effect is good. In comparison with this, the conventional one is inapplicable to any item. Of course, even if the same MO film is used, it is not possible to form a magnetic bar code by vapor deposition or coating. As described above, it can be seen that the information recording medium of the present invention has excellent functions.

When the information pattern of the information recording layer 8 of the information recording medium 2 is a magnetic pattern such as a magnetic bar code, it can be read by an ordinary magnetic reader and can be written by a magnetic head. On the other hand, the magnetic information recorded on the magneto-optical thin film 4 can be read after being converted into optical information. FIG. 5 shows a mechanical reading device, and FIG. 6 shows a visual reading device. The magnetic pattern is optically read by these devices.

As shown in FIG. 6, the light emitted from the laser light source 11 passes through the condenser lens 12, is modulated by the light modulator 13, and then becomes polarized by the polarizer 14, and the half mirror 1
5, passing through the condenser lens 16 to reach the information recording medium 2 (2a). The information recording medium 2 receives the rotation of the plane of polarization due to the magneto-optical effect (Faraday effect), reflects the light, passes through the condenser lens 16 and the half mirror 15 again, and then the analyzer 17
And is converted into an electric signal by the photodetector 18. Two
One of the set photodetectors detects the sync signal and the other one detects the recorded content. It is output as a reproduction signal 20 via the amplifier 19. As described above, it is possible to optically reproduce the magnetic recording information. By transferring the light reflection film 9 together with the magneto-optical thin film 4, the magnetic recording content can be reproduced by the reflected light. In the case of an information recording medium such as a card, it is not necessary to record the magneto-optical recording content in a high density state, and therefore extremely stable reproduction can be ensured.

Next, a visual observation method of magnetic information by the magnetic mark visualization device will be described with reference to FIG. The light 21 used for observation is linearly polarized by the polarizer 22, and then passes through the half mirror 23 to obtain the information recording medium 2 (2a).
Reach The light 21 has its polarization plane rotated by the magneto-optical effect on the information recording medium 2, and then is reflected and reflected by the half mirror 2.
After passing through No. 3, it passes through the analyzer 24 and is visually observed. At this time, contrast of light and shade of light is generated according to the magnetic pattern, and the magnetic pattern can be visually observed. The magnetic mark may be any mark, character or pattern.
For example, when judging the authenticity of a posted card at a counter of a bank or the like, the authenticity of the card can be judged in an extremely short time by using the magnetic mark visualization device which is made compact.

The magneto-optical thin film 4 is not particularly limited as long as it is formed of a coating film having good light transmittance. For example, a coating film in which a magnetic powder made of bismuth rare earth iron garnet is dispersed in a binder resin as a material having a good light transmission property can be mentioned. Fine particles of bismuth rare earth iron garnet crystal are recognized as a material having an excellent magneto-optical effect, and thin film media using these fine particles are widely used. As the amount of bismuth increases, the optical absorption edge shifts to the shorter wavelength side, and the transparency in the visible region increases. However, bismuth iron garnet of the general formula _{R 3-x Bi x Fe 5} -y M y O 12 crystal structure represented by the fact of making those exceeding x = 1.8 which is a stoichiometric limit Was difficult. For example, as described in the paper “Basic characteristics of coating type magneto-optical recording medium” described in 9PG-1 of the 16th Japan Society for Applied Magnetics Academic Lectures (1992), generation of each Bi substitution amount is described. The garnet single-phase region existed in the phase up to the range of x = 1.8 substitution.
In substitution, in addition to garnet phase, orthoferrite and B
Formation of i ₂ Fe ₄ O ₃ was observed, and “the limit of Bi substitution is x
= 1.8. " On the other hand, as described above, fine particles of bismuth iron garnet are excellent in magneto-optical effect, but when using this, a binder (binder) is required, which lowers magneto-optical characteristics, and also causes light transmission. With regard to the above, there is a difference in refractive index because it consists of a mixed system of inorganic iron garnet fine particles and a binder that is an organic substance.Since this difference greatly affects the light transmission process, single phase films such as epitaxial thin films can be used. There is a problem that the transparency is lowered as compared with the above. Therefore, the value of x of bismuth rare earth iron garnet fine particles is 1.8 ≦ x <3.0
High concentration bismuth-substituted iron garnet fine particles or x =
It is extremely advantageous to prepare completely bismuth-substituted iron garnet fine particles of 3.0 and improve the magneto-optical characteristics and the light transmittance thereof as the MO film 4.

Next, the basic method for producing high-concentration bismuth-substituted iron garnet fine particles will be described with reference to the flow chart of FIG. Garnet crystal structure formula _{R 3-x Bi x Fe 5} -y M y
Represented by O ₁₂ . Here, R and Bi are mutually substituting elements, and Fe and M are mutually substituting elements. Fine particles having a desired garnet crystal structure can be produced by appropriately setting the values of x and y. R
Is Y, La, Ce, Pr, Nd, Pm, Sm, Eu, G
d, Tb, Dy, Ho, Er, Tm, Yb and one or more rare earth elements selected from the group consisting of Lu, M
Is Al, Ga, Cr, Mn, Sc, In, Ru, Rh,
Co, Fc (ll), Cu, Ni, Zn, Li, Si, G
e, Zr, Ti, Hf, Sn, Pb, Mo, V and N
It is one or more elements selected from the group consisting of b. In the garnet crystal structure, R and Bi occupy the c site, and F
e and M occupy a and / or d sites and O occupies h sites, respectively.

First, x <1.8 and 0 ≦ within the stoichiometry.
R-containing salt, Bi-containing salt, F so as to satisfy the range of y ≦ 5
The e-containing salt and the M-containing salt are prepared to prepare a mixed aqueous solution (step 100). Next, ammonia water is mixed (step 101), and the hydroxides of the respective elements are coprecipitated to form a mixed precipitate (step 102). Next, this precipitate is filtered and separated into a slurry and a filtrate (step 10).
3). Next, the slurry is mixed with water and repeatedly washed (step 104). Next, it is dried (step 105) and baked (step 106). As a result, seed crystals of the existing fine particles are obtained (step 107).

On the other hand, separately, the R-containing salt, the Bi-containing salt, the Fe-containing salt and the M-containing are added so as to satisfy the ranges of 1.8 ≦ x ≦ 3.0 and 0 ≦ y ≦ 5, which are stoichiometrically excessive in Bi. Salts are blended to form these aqueous solutions (step 10).
8). The suspension containing the existing fine particles prepared in the above step 107 is added to this aqueous solution (step 10).
9). Next, it is mixed with aqueous ammonia (step 11
0), a precipitate is generated (step 111), separated into a slurry and a filtrate (step 112), washed with water (step 113), dried (step 114) and calcined (step 115). As a result, epitaxial crystal growth occurs around the seed crystal that serves as the nucleus, and high-concentration bismuth-substituted iron garnet fine particles are created (step 11).
5). Further, completely bismuth-substituted iron garnet fine particles can be prepared by setting x = 3.0 (that is, excluding the R-containing salt) and performing the same treatment as described above.

[0028]

According to the present invention, the following remarkable effects are obtained. 1) A heat-sensitive transfer medium mainly composed of a magneto-optical thin plate can be produced, and this transfer foil can be peeled off from a base material and transferred to an arbitrary place on an information recording medium. Therefore, it is possible to easily manufacture an information recording medium that records any necessary information pattern as needed. 2) Since the information recording layer of the information recording medium is formed of a magneto-optical thin film having a magneto-optical effect, it can fulfill the function of writing magnetic additional information and the function of forming bar code information. 3) Further, by using the magneto-optical thin film, it is possible to change the magnetic information into optical information and read the information pattern.
As a result, authenticity determination is performed. 4) Since the thermal transfer medium can be thermally transferred by a thermal head or the like, it can be handled freely and is applied to various uses. 5) By using a magnetic powder of high-concentration bismuth-substituted iron garnet fine particles as the magneto-optical thin film, it is possible to form an information recording layer having excellent light transmittance. This improves the forgery prevention effect.

[Brief description of drawings]

FIG. 1 is a sectional view showing a laminated structure and the like of an embodiment of a thermal transfer medium and an information recording medium according to the present invention.

FIG. 2 is a cross-sectional view showing one specific example of each layer in FIG.

FIG. 3 is a sectional view showing a laminated structure of another embodiment of the thermal transfer medium of the present invention.

FIG. 4 is a perspective view showing an example of an information recording medium to which a magnetic barcode is transferred.

FIG. 5 is a perspective view showing an example of an information recording medium with an arbitrary identification mark.

FIG. 6 is a configuration diagram of a magnetic recording / reproducing apparatus for optically reading a magnetic pattern or the like transferred to an information recording medium.

FIG. 7 is a configuration diagram of a magnetic mark visualization device for visual observation.

FIG. 8 is a flow chart for explaining a method for producing high-concentration bismuth-substituted iron garnet fine particles used for the magneto-optical thin film of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thermal transfer medium 2 Information recording medium 2a Information recording medium 3 Transfer foil 3a Transfer foil 4 Magneto-optical thin film 4a Magneto-optical thin film 5 Adhesive film 5a Adhesive film 6 Release film 6a Release film 7 Information recording medium base 8 Information recording layer 8a Information recording Layer 9 Light-reflecting film 10 Base material 11 Laser light source 12 Condenser lens 13 Light modulator 14 Polarizer 15 Half mirror 16 Polarization plane 17 Analyzer 18 Photodetector 19 Amplifier 20 Reproduction signal 21 Light 22 Polarizer 23 Half mirror 24 Detection photon

Claims (6)

[Claims] 1. A thermal transfer medium having at least a base material and a transfer foil laminated on the base material, which is used for thermal transfer processing of an object, wherein the transfer foil contains magnetic powder having a magneto-optical effect. Characterized in that it is mainly composed of the magneto-optical thin film, and can be peeled off from the substrate by local heating, and can adhere to the object to form a desired magneto-optical pattern on the surface of the object. A thermal transfer medium. 2. The heat-sensitive transfer medium according to claim 1, wherein the magnetic powder is magnetic fine particles made of bismuth rare earth iron garnet. 3. The heat-sensitive transfer medium according to claim 1, wherein the transfer foil includes a heat-sensitive adhesive film formed on the upper surface of the magneto-optical thin film. 4. The heat-sensitive transfer medium according to claim 1, wherein the transfer foil includes a heat-sensitive peeling film formed on the lower surface of the magneto-optical thin film. 5. The heat-sensitive transfer medium according to claim 1, wherein the transfer foil includes a light reflection film formed on an upper surface of the magneto-optical thin film having light transparency. 6. An information recording layer having a pattern of a thermo-sensitive transferred magneto-optical thin film is provided, and the magneto-optical thin film contains magnetic fine particles made of bismuth rare earth iron garnet so that optical information can be read out. Information recording medium.