JP3413936B2 - Information recording medium - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention records invisible information by irradiating it with a high-energy light beam such as a laser beam so that the recorded information can be read by an infrared laser or the like which is different from the recording. The present invention relates to an information recording medium according to the above.

[0002]

2. Description of the Related Art In recent years, in addition to securities such as stock certificates, bonds, checks, passbooks, lottery tickets, boarding tickets, coupons, commuter tickets, plastic cards such as ID cards, credit cards, cash cards, gift cards, telephones. There are remarkable developments in securities-related products such as prepaid cards, which are typified by cards, as an alternative to cash vouchers, and inevitably, a method for effectively preventing counterfeiting of them and an easy way to determine their authenticity are possible. The importance of the technology is extremely high.

Several methods have been proposed as a technique aiming at such security. One of them is magnetic recording technology.

However, although magnetically recorded information cannot be visually inspected, it is possible to intentionally erase or rewrite the recorded information due to the popularization of general magnetic reading machines, which increases the risk. There is.

Information is also recorded by means of bar code, OCR, MICR, etc., but with such means, the code can be viewed and can be the subject of forgery and falsification. Therefore, the danger is unavoidable.

Therefore, recently, a proposal has been made to perform mechanical reading of information recorded centering on the infrared absorption leucothermal, by reading the difference in reflectance with a detector when irradiating infrared rays. There is.

However, since most of the recorded information of this kind has a color-developed part in black or dark color, in order to make the information invisible, it is prepared by mixing process inks. It is considered to hide with black ink.

However, when such a hiding layer is provided, it is difficult to print on the hiding layer, and it cannot be said that the hiding layer looks good, and the hiding layer is partially provided. However, if there is a black pattern that is unnatural in design, it makes it easy to imagine that the infrared readable code is hidden under it, so it is easy to be a target of forgery and tampering. There is also.

In the past, most of the above-mentioned recording information writing is direct printing centered on a thermal head. This is because it is easy to maintain and the printing device can be made compact at the time of designing, but when printing invisible information, a print mark is generated due to the contact of the head during printing, which causes writing. The choice of protective layer and thermal recording layer becomes very difficult to avoid viewing information.

For the above-mentioned reasons, it is strongly desired to develop a method for making recorded information visually unrecognizable without making the code unnaturally black.

In addition to securities such as stock certificates, securities, checks, passbooks, treasure lottery tickets, boarding tickets, coupons, commuter passes, plastic cards such as ID cards, credit cards, cash cards, gift cards, and telephone cards are typical. In securities related products such as prepaid cards that replace cash vouchers, it is strongly desired that the information is not fixed information but unique variable information for each securities related product in order to enhance security against counterfeiting and tampering. ing.

[0012]

As described above, in the conventional information recording method, not only is it unnatural in design, but also the recorded information is visually confirmed and easily becomes a target of forgery or falsification. Further, there is a problem that the record information cannot be recorded as variable information.

The present invention has been made in order to solve the above-mentioned problems, and can print invisible information while remaining close to a white background which is natural in design, and is unique as the invisible information. It is an object of the present invention to provide an information recording medium capable of non-contact printing of variable information and mechanically recognizing the printed and recorded information to remarkably enhance security against forgery and falsification.

[0014]

In order to achieve the above object, first of all, an information recording medium of the invention according to claim 1 has an infrared absorption layer for reading information on a substrate and an infrared region depending on temperature. Information that shows a change in the transmittance of the infrared-ray transmittance, a heat-sensitive recording layer that forms a recorded image by the difference in the infrared transmittance, and that selectively absorbs at a specific wavelength in the infrared region, and that transmits in other infrared regions. Is formed by stacking at least a photothermal conversion layer for writing.

An information recording medium according to a second aspect of the invention has an infrared absorption layer for reading information on a substrate,
The thermal transmittance of the infrared region changes depending on the temperature, and the heat-sensitive recording layer that forms a recorded image by the difference in the infrared transmittance, selectively absorbs at a specific wavelength in the infrared region, and transmits in other infrared regions. The photothermal conversion layer for writing the information indicating the property and the printing layer which transmits infrared rays and makes the recorded image invisible to the naked eye are laminated.

Further, the information recording medium of the invention according to claim 8 is the information recording medium of the invention according to claim 1, wherein a heat-resistant protective layer which transmits infrared rays is laminated on the photothermal conversion layer. .

Furthermore, an information recording medium according to a ninth aspect of the present invention is the information recording medium according to the second aspect, in which a heat-resistant protective layer that transmits infrared rays is laminated on the print layer.

Here, particularly as the infrared absorbing layer,
At least, the photothermal conversion layer exhibits absorption properties in the infrared region other than the infrared absorption wavelength.

The infrared absorbing layer is composed of powdered phosphate glass containing at least phosphorus pentoxide as a main component and containing iron oxide and / or copper oxide in an amount of 1.0% by weight or more and a binder.

On the other hand, the heat-sensitive recording layer is composed of hollow microcapsules.

In addition, the heat-sensitive recording layer has a low infrared transmittance at room temperature, and the infrared transmittance increases due to destruction of the hollow microcapsules themselves at a predetermined temperature or higher.

Further, the heat-sensitive recording layer is formed by adding a substance that transmits infrared light.

[0023]

Therefore, in the information recording medium of the present invention, the two layers of the photothermal conversion layer provided for writing the information and the infrared absorption layer provided for reading the recorded information are used. The invisible information can be printed in a non-contact manner by a laser light beam that matches the absorption wavelength range, and the information can be read using infrared rays that are different from the absorption wavelength of the photothermal conversion layer. Invisible information can be printed in a contactless manner while remaining close to a white background, and recorded information can be mechanically recognized to improve security against forgery and falsification.

Further, in the information recording medium of the invention according to claim 2, recording is performed by providing a printing layer which transmits infrared rays on the photothermal conversion layer and which makes it impossible to visually identify a recorded image. Since it is difficult to detect such a pattern, it is possible to more reliably prevent counterfeiting and tampering.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The information recording medium of the present invention records invisible information by irradiating it with a high-energy light beam such as a laser beam, and reads the recorded information by an infrared laser or the like which is different from the recording. Is.

An embodiment of the present invention based on the above concept will be described below in detail with reference to the drawings.

(First Embodiment) FIG. 1 is a sectional view showing an example of the arrangement of an information recording medium according to the first embodiment of the present invention.

That is, as shown in FIG. 1, the information recording medium of this embodiment is capable of reading information showing absorptivity on the substrate 1 at least in the infrared region other than the infrared absorption wavelength of the photothermal conversion ink layer 5. Infrared absorptive ink layer 2 for heat transfer, the solvent in the ink of the heat-sensitive recording layer 3 and the light-heat conversion ink layer 5 which forms a recorded image due to the difference in the infrared transmittance due to the change of the infrared transmittance A barrier layer 4 for preventing the recording layer 3 from being damaged, a photothermal conversion ink layer for writing information which selectively absorbs at a specific wavelength in the infrared region and is transmissive in other infrared regions. 5. A heat-resistant protective layer 7 that transmits infrared rays is sequentially laminated.

Here, as the substrate 1, various types can be used depending on the application, but for example, paper, PET, plastic such as vinyl chloride, etc. can be used.

The infrared absorbing ink used in the infrared absorbing ink layer 2 is composed of an infrared absorbing dye / pigment or powdered phosphate glass, a binder resin, and a solvent.

Examples of the dyes include organic dye-based phthalocyanine dyes, naphthalocyanine dyes, aminium salt dyes, anthraquinone dyes, pyrylium dyes, squarylium dyes, and the like.
Among these, aminium salt dyes, which have low absorption in the visible region, are particularly preferable.

Further, as the powdered phosphate glass,
It contains phosphorus pentoxide as a main component and contains iron oxide and / or copper oxide in an amount of 1.0% by weight or more, but preferably phosphorus pentoxide in a weight percentage of 35.0 to 80.0%, iron oxide and copper oxide in weight percentages. It is preferable to contain each of 0 to 3.0% in percentage.

Further, the powdered phosphate glass described above optionally contains the following compounds.

Al ₂ O ₃ 2.0 to 10.0% by weight B ₂ O ₃ 1.0 to 30.0% by weight MgO 3.0 to 10.0% by weight ZnO 0 to 3.0% by weight K ₂ O 0 to 15.0% by weight BaO 0 to 10.0% by weight SrO 0 to 1.0% by weight Ni, Co, Se Trace powder phosphate glass is obtained by pulverizing the phosphate glass obtained above into a pigment. An ink can be used. And such powdered phosphate glass is preferably contained in the ink composition excluding the solvent in a weight percentage of 80% or less.

On the other hand, as the binder resin, for example, vinyl chloride-vinyl acetate copolymer resin, saturated polyester, polyurethane elastomer or the like can be used.

Examples of the solvent include toluene, methyl isobutyl ketone, xylene, cyclohexanol, isobutyl acetate, cyclohexanone, methyl cyclohexanone, glycol derivatives such as ethylene glycol monobutyl ether, and the like, or a mixed solvent thereof.

The infrared absorbing ink used in the infrared absorbing ink layer 2 may contain an antifoaming agent, a lubricant, etc., if necessary, in addition to the above materials.

Examples of the solvent used for the infrared absorbing ink include toluene, methyl isobutyl ketone, xylene, cyclohexanol, isobutyl acetate, cyclohexanone, methyl cyclohexanone, glycol derivatives such as ethylene glycol monobutyl ether, and the like. A mixed solvent may be used.

Next, the thermal recording layer 3 laminated on the infrared absorbing ink layer 2 has a particle size of 0.05 to 1 μm.
An emulsion obtained by emulsifying and dispersing the hollow microcapsules of (1), which has a low infrared transmittance at room temperature and an increased infrared transmittance at a predetermined temperature or higher, and a thermosensitive recording that forms a recorded image by the difference in the infrared transmittance. Layers are provided.

That is, the heat-sensitive recording layer 3 of this embodiment is composed of a hollow microcapsule emulsion having a particle size of 0.05 to 1 μm prepared by an emulsion polymerization method or the like. Thermosensitive recording layer 3 in which such hollow microcapsules are emulsified and dispersed
At room temperature, the refractive index of light changes due to the presence of air in the hollow microcapsules with respect to the incidence of infrared light, and as a result, light scattering occurs and the infrared transmittance decreases. On the other hand, by heating above a predetermined temperature, that is, above the glass transition point of the resin forming the hollow microcapsules, the microcapsules are broken and fused, and the particle-air interface decreases and light scattering occurs. It is suppressed and becomes transparent, and the transmittance of infrared light is increased.

The wall material for forming such microcapsules has a glass transition temperature of 50 ° C. or higher.
It is preferably about 150 degrees, for example, polyurea, polyester, polycarbonate, urea-formaldehyde resin, melamine resin, polystyrene, styrene methacrylate copolymer, gelatin, polyvinylpyrrolidone,
Examples thereof include polyvinyl alcohol and the like, which may be selected according to the desired transparency temperature. Also, materials other than the above may be used as long as the transmittance changes in the infrared region depending on the temperature.

The heat-sensitive recording layer 3 is an emulsion obtained by emulsifying and dispersing these, and is coated on the infrared absorbing ink layer 2 on the substrate 1 by a method such as a screen printing method or a gravure printing method and dried. Can be formed by.

Next, the photothermal conversion ink layer 5 is an ink layer that selectively absorbs at a specific wavelength in the infrared region and efficiently transmits in other infrared regions. Reference numeral 5 is a light-heat conversion layer for writing information to the heat-sensitive recording layer 3. Therefore, the wavelength range that selectively absorbs may be selected according to the laser wavelength used during writing.

The infrared ray absorbing ink used in the photothermal conversion ink layer 5 is an ink containing an infrared ray absorbing dye / pigment which selectively absorbs in the infrared region, for example, offset printing method, screen printing method, gravure printing. It can be formed by a known coating method such as a method.

Here, as the infrared absorbing dye, for example, cyanine dyes and the like can be selectively absorbed in the vicinity of 780 nm and can be transmitted in other wavelength regions.

Further, as the binder when provided by the gravure printing method, for example, vinyl chloride-vinyl acetate copolymer resin, saturated polyester, polyurethane elastomer and the like are used. Further, in addition to the above materials, an antifoaming agent, a lubricant and the like can be added if necessary.

Further, as the solvent used for diluting the infrared absorbing ink used in the photothermal conversion ink layer 5 to an appropriate viscosity, for example, toluene, methyl isobutyl ketone, xylene, cyclohexanol, isobutyl acetate, cyclohexanone, methylcyclohexanone. , A glycol derivative such as ethylene glycol monobutyl ether, or a mixed solvent thereof.

When the offset printing method is used, the offset ink containing the above infrared absorbing dye can be used, for example, by the wet offset method or the dry offset method.

Next, the protective layer 7 is transparent to infrared rays and has heat resistance in order to improve the resistance of the information recording material to abrasion and the like. As the material of the protective layer 7, for example, acrylic resin, vinyl chloride resin, nitrocellulose, hydroxycellulose, carboxymethyl cellulose, polyvinyl alcohol, styrene-maleic acid copolymer, polyester resin, ABS resin and the like can be used. The protective layer 7 having heat resistance can be formed by dissolving or dispersing in a solvent such as xylene, coating by a gravure method, a roll coating method, or the like and drying.
Further, a curable resin such as a thermosetting resin, an ultraviolet curable resin, or an electron beam curable resin may be used.

Next, in the information recording medium according to the present embodiment, the photothermal conversion layer 5 becomes a photothermal conversion layer that absorbs light and emits heat in the portion irradiated with light such as an infrared laser. Information may be recorded by forming a recorded image on the thermosensitive recording layer 3.

That is, when the thermal recording layer 3 is in a state where the infrared transmissivity is small, it is heated to the glass transition temperature of the hollow microcapsules by the thermal head, and the hollow microcapsules themselves are broken, and the heated portion is heated. 2 has a large infrared transmittance, and a portion having a large infrared transmittance forms a recorded image as shown in FIGS. 2 (a) and 2 (b).

Since this recorded image has a small spectral change in the visible region, it is difficult to discern with the naked eye, and the printed recorded image is completely invisible, and the confidentiality of information is maintained.

On the other hand, when the recorded image printed as described above is read, an infrared laser beam having a wavelength range different from that of the infrared laser used for recording information is irradiated to absorb the infrared rays with the thermosensitive recording layer 3. The difference between the reflected light rays caused by the contrast with the photographic ink layer 2 may be detected by an infrared sensor.

That is, the incident infrared rays are reflected and scattered at the portion having a small infrared ray transmittance, but the incident light ray is not absorbed at the portion having a large infrared ray transmittance by the infrared absorbing ink layer 2 and thus the recording is not performed. The presence or absence of an image can be identified. Also, when reading the recorded image,
The photothermal conversion layer 5 efficiently transmits the irradiating infrared laser.

Next, a specific example of the information recording medium of this embodiment will be described.

(Specific Example 1) The information recording medium of this specific example is
To prevent the thermal recording layer 3 from being destroyed by the solvent in the infrared absorbing ink layer 2, the thermal recording layer 3, and the material coated on the thermal recording layer 3 on the substrate 1 made of paper or plastic. The barrier layer 4, the light-heat conversion layer 5, and the protective layer (overcoat) 7 are laminated.

Here, as the infrared absorbing ink layer 2, P ₂ O ₅ ... 78.0 wt%, Al ₂ O ₃ ... 5.2 wt%, BaO ... 9.0 wt%, MgO ... 5.4. weight%,
A mixture of CuO ... 1.7 wt% and SrO ... 0.05 wt% was melted and vitrified to obtain a pigment.

As the heat-sensitive recording layer 3, an acrylic hollow microcapsule resin emulsion (average particle size of 0.
5μ, solid content ratio 33.6%) was applied to a thickness of 20μ.

Further, as the barrier layer 4, a water-dispersible urethane resin ... Hydran AP30 (manufactured by Dainippon Ink Co., Ltd.) 19 parts Epoxy curing agent CR-5L (manufactured by Dainippon Ink Co., Ltd.) 1 part The resin was applied and dried by a bar coater so that the dry film thickness was 1 μm.

Further, as the photothermal conversion layer 5,   Infrared absorber CY-20 (manufactured by Nippon Kayaku Co., Ltd.) 2 parts   Acrylic resin BR-56 (manufactured by Mitsubishi Rayon Co., Ltd.)                                                                 18 copies   Isocyanate curing agent D24A100 (manufactured by Asahi Kasei Corporation) 2 parts   Solvent Toluene 78 parts Was made into an ink and applied.

Further, as the protection tank 7, FDT
COP varnish (manufactured by Toyo Ink Co., Ltd.) was applied to a thickness of 2 to 5 μm.

Next, a pattern was printed on the information recording medium obtained as described above by using a semiconductor laser of 780 nm with energy of 100 mV, 150 mW and 200 mW. The printed pattern could not be recognized with the naked eye, but when viewed through a visible cut filter that transmits only light of 850 nm or more with an IR scope (manufactured by Ikegami Tsushinsha), the printed pattern could be recognized. .

Further, when measured with a spectrophotometer, sufficient contrast was confirmed in the infrared region.

FIG. 3 is a characteristic diagram showing an example of a spectral reflection spectrum obtained by the information recording medium having the configuration of FIG.

As described above, the information recording medium of this embodiment has the infrared absorption for reading the information having the absorptivity on the substrate 1 at least in the infrared region other than the infrared absorption wavelength of the photothermal conversion ink layer 5. Of the heat-sensitive ink layer 2, the transmittance of the infrared region changes depending on the temperature, and the solvent in the ink of the heat-sensitive recording layer 3 and the photothermal conversion ink layer 5 that forms a recorded image by the difference in the infrared transmittance changes the heat-sensitive recording layer 3 to the heat-sensitive recording layer 3. A barrier layer 4 for preventing corrosion, a photothermal conversion ink layer 5 for writing information that selectively absorbs at a specific wavelength in the infrared region and is transmissive in other infrared regions, and infrared rays. The transparent heat-resistant protective layer 7 is sequentially laminated.

Therefore, since the photothermal conversion layer 5 provided for writing information and the infrared absorption layer 2 provided for reading recorded information have a two-layer structure, a laser having the same absorption wavelength range as the photothermal conversion layer 5 is used. The non-contact information can be printed by the light beam by the contactless light and the information can be read by using the infrared ray different from the absorption wavelength of the photothermal conversion layer 5, so that a natural white background with a large degree of freedom in design can be obtained. It is possible to print invisible information in a non-contact manner as it is, and to mechanically recognize recorded information to remarkably enhance security against forgery and falsification.

Further, as the invisible information, variable information unique to each securities-related product can be printed.

Furthermore, not only is it difficult to detect a pattern such as a recorded code, but there is no fear that a pattern for preventing forgery and tampering will be detected. Therefore, forgery and tampering are surely prevented. It becomes possible.

(Second Embodiment) FIG. 4 is a sectional view showing an example of the arrangement of an information recording medium according to the second embodiment of the present invention. The same elements as those of FIG. 1 are designated by the same reference numerals. ing.

That is, as shown in FIG. 4, the information recording medium of the present embodiment is capable of reading information showing absorptivity on the substrate 1 at least in the infrared region other than the infrared absorption wavelength of the photothermal conversion ink layer 5. Infrared absorptive ink layer 2 for heat transfer, the solvent in the ink of the heat-sensitive recording layer 3 and the light-heat conversion ink layer 5 which forms a recorded image due to the difference in the infrared transmittance due to the change of the infrared transmittance A barrier layer 4 for preventing the recording layer 3 from being damaged, a photothermal conversion ink layer for writing information which selectively absorbs at a specific wavelength in the infrared region and is transmissive in other infrared regions. 5, a printing layer 6 which transmits infrared rays and makes it impossible to visually identify a recorded image, and a heat-resistant protective layer 7 which transmits infrared rays
Are sequentially laminated.

Here, the printing layer 6 means a layer which transmits infrared rays that can be read by an infrared sensor and blocks visible rays to the extent that a recorded image cannot be discriminated by the naked eye. The transmittance is higher than that of visible light, and because the infrared sensor has excellent sensitivity, the recorded image can be identified with the naked eye even if the transmittance of infrared light is lower than that of visible light. Instead, it can be identified by an infrared sensor.

Examples of such a printing layer 6 include a gelatin film, Orazole Black BV and Orazole 2RG.
A coating material containing an infrared-transmissive dye, such as a normal UV-curable process ink, can be used.

Examples of the ultraviolet curable process ink include FDOL yellow and FD manufactured by Toyo Ink Mfg. Co., Ltd.
OL magenta, FDOL cyan, etc. can be used.

The print pattern may be a print pattern such as a tint block pattern, a fine pattern pattern, or an image. The visible light blocking layer is formed of an ultraviolet curable process ink by, for example, a screen printing method or an offset printing method. Immediately after printing, it can be formed by irradiating with ultraviolet rays and curing. The thickness is 1
It may be at least μm.

Next, in the information recording medium according to the present embodiment, the photothermal conversion layer 5 becomes a photothermal conversion layer that absorbs light and emits heat in a portion irradiated with light such as an infrared laser. Information may be recorded by forming a recorded image on the thermosensitive recording layer 3.

That is, when the heat-sensitive recording layer 3 is in a state where the infrared transmittance is small, it is heated to the glass transition temperature of the hollow microcapsule by the thermal head, and the hollow microcapsule itself is destroyed, and the heated portion is heated. Infrared transmittance becomes large, and a portion having a large infrared transmittance forms a recorded image as shown in FIGS. 4 (a) and 4 (b).

Since this recorded image has a small spectral change in the visible region, it is difficult to discern with the naked eye. Further, by providing the print layer 6 such as the tint block and the fine pattern, the printed record image becomes completely invisible. , The confidentiality of information is maintained.

On the other hand, when the recorded image printed as described above is read, an infrared laser beam having a wavelength range different from that of the infrared laser used at the time of recording information is applied to the thermal recording layer 3 and the infrared absorption. The difference between the reflected light rays caused by the contrast with the photographic ink layer 2 may be detected by an infrared sensor.

That is, the incident infrared rays are reflected and scattered at the portion having a small infrared transmittance, but the incident light is not absorbed at the portion having a large infrared transmittance by the infrared absorbing ink layer 2 so that no reflection occurs. The presence or absence of an image can be identified. Also, when reading the recorded image,
The photothermal conversion layer 5 efficiently transmits the irradiating infrared laser.

(Specific Example 2) The information recording medium of this specific example is
In order to prevent the thermal recording layer 3 from being destroyed by an infrared absorbing ink layer 2, a thermal recording layer 3 and a solvent content applied on the thermal recording layer 3 on a substrate 1 made of paper or plastic. The barrier layer 4, the light-heat conversion layer 5, the printing layer 6 made of an infrared transmitting process ink, and the protective layer (overcoat) 7 are laminated.

Here, the infrared absorbing ink layer 2, the heat-sensitive recording layer 3, the barrier layer 4, the photothermal conversion layer 5 and the protective layer 7 were formed in the same manner as in the case of Specific Example 1 above.

Further, as the printing layer 6 of the infrared transmitting process ink, a tint block pattern was formed using yellow FDOL, yellow magenta color, FDOL, red cyan color, FDOL indigo (all of which are manufactured by Toyo Ink Co., Ltd.).

Next, a pattern was printed on the information recording medium obtained as described above by using a semiconductor laser of 780 nm with energy of 100 mV, 150 mW and 200 mW. This printed pattern could not be recognized with the naked eye more than in Specific Example 1, but I
When viewed through an R-scope (made by Ikegami Tsushin Co., Ltd.) through a visible cut filter that transmits only light of 850 nm or more, the print pattern was clearly recognizable.

As described above, the information recording medium of the present embodiment has an infrared absorption for reading information showing absorptivity on the substrate 1 at least in the infrared region other than the infrared absorption wavelength of the photothermal conversion ink layer 5. Of the heat-sensitive ink layer 2, the transmittance of the infrared region changes depending on the temperature, and the solvent in the ink of the heat-sensitive recording layer 3 and the photothermal conversion ink layer 5 that forms a recorded image by the difference in the infrared transmittance changes the heat-sensitive recording layer 3 to the heat-sensitive recording layer 3. A barrier layer 4 for preventing corrosion, a photothermal conversion ink layer 5 for writing information that selectively absorbs at a specific wavelength in the infrared region and is transmissive in other infrared regions, and infrared rays. A printing layer 6 that allows transmission of light and a recorded image that is invisible to the naked eye, and a heat-resistant protective layer 7 that transmits infrared light are sequentially laminated.

Therefore, since the photothermal conversion layer 5 provided for writing information and the infrared absorption layer 2 provided for reading recorded information have a two-layer structure, a laser having the same absorption wavelength range as the photothermal conversion layer 5 is used. The non-contact information can be printed by the light beam by the contactless light and the information can be read by using the infrared ray different from the absorption wavelength of the photothermal conversion layer 5, so that a natural white background with a large degree of freedom in design can be obtained. It is possible to print invisible information in a non-contact manner as it is, and to mechanically recognize recorded information to remarkably enhance security against forgery and falsification.

As the invisible information, variable information unique to each securities-related product can be printed.

Further, not only is it difficult to detect a pattern such as a recorded code, but there is no fear of detecting the existence of a pattern for preventing forgery and tampering, so that forgery and tampering are surely prevented. It becomes possible.

Furthermore, since the printing layer 6 is provided on the photothermal conversion layer 5 to transmit infrared rays and to make it impossible to visually identify the recorded image, it becomes more difficult to detect the recorded pattern. At the very least, it becomes possible to more reliably prevent counterfeiting and falsification.

The present invention is not limited to the above embodiments, but can be implemented in the same manner as described below.

(A) In each of the above examples, the heat-resistant protective layer 7 is not essential to the present invention, and may be provided as needed.

(B) In each of the above embodiments, the barrier layer 4
Is not essential to the present invention, and may be provided as needed.

[0092]

As described above, according to the present invention, the infrared absorption layer for reading information on the substrate, the transmittance in the infrared region changes depending on the temperature, and recording is performed by the difference in the infrared transmittance. A heat-sensitive recording layer that constitutes an image, a photothermal conversion layer for writing information that selectively absorbs at a specific wavelength in the infrared region, and is transparent in other infrared regions,
If necessary, heat radiation that transmits infrared light and at the same time laminates a printing layer that makes it impossible to identify the recorded image with the naked eye, and if necessary, transmits infrared light on the photothermal conversion layer or printing layer. Since the protective layer is laminated, the invisible information can be printed in a non-contact manner while being close to a white background which is natural in terms of design, and the variable information peculiar to the invisible information can be printed. An information recording medium capable of mechanically recognizing information and significantly improving security against forgery and falsification can be provided.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of an information recording medium of the present invention.

FIG. 2 is a schematic diagram for explaining writing of information and reading of information on the information recording medium in the first embodiment.

FIG. 3 is a characteristic diagram showing an example of a spectral reflection spectrum obtained by the information recording medium in the first embodiment.

FIG. 4 is a sectional view showing a second embodiment of the information recording medium of the present invention.

FIG. 5 is a schematic diagram for explaining writing of information and reading of information on the information recording medium in the second embodiment.

[Explanation of symbols]

1 ... Substrate, 2 ... Infrared absorbing ink layer, 3 ... Thermal recording layer, 4 ... Barrier layer, 5 ... Photothermal conversion layer, 6 ... Infrared transmitting process ink printing layer, 7 ... Protective layer.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-4-189196 (JP, A) JP-A-1-251445 (JP, A) JP-A-2-289924 (JP, A) JP-A-3- 293194 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B41M 5/26 B42D 15/10 G11B 7/24

Claims (8)

(57) [Claims] 1. An infrared absorption layer for reading information on a substrate, a thermosensitive recording layer whose infrared transmittance varies depending on temperature, and a recorded image is formed by a difference in the infrared transmittance. At least a photothermal conversion layer for writing information that selectively absorbs light at a specific wavelength and is transparent in other infrared regions is laminated, and the infrared absorption layer is an infrared ray of the photothermal conversion layer. Below absorption wavelength
An information recording medium characterized by exhibiting absorption in the outside infrared region . 2. An infrared absorption layer for reading information on a substrate, a thermal recording layer which changes a transmittance in the infrared region depending on temperature, and forms a recorded image by the difference in the infrared transmittance, and an infrared recording layer in the infrared region. A photothermal conversion layer for writing information that selectively absorbs light at a specific wavelength and is transparent in other infrared regions, transmits infrared light, and makes printing of recorded images impossible with the naked eye. At least layers, and the infrared absorption layer has a wavelength equal to or less than the infrared absorption wavelength of the photothermal conversion layer.
An information recording medium characterized by exhibiting absorption in the outside infrared region . 3. The infrared absorption layer is at least
Phosphorus pentaoxide as the main component, iron oxide and / or oxidation
Powdered phosphate glass and bar containing 1.0% by weight or more of copper
Claim 1 or claim characterized by comprising an inder
Item 2. The information recording medium according to item 2 . 4. The heat-sensitive recording layer is hollow micro
Claim 1 or Claim which consists of a capsule
Item 2. The information recording medium according to item 2 . 5. The heat-sensitive recording layer is infrared at room temperature.
The hollow microcapacitor has a low linear transmittance and is above a certain temperature.
Infrared transmittance increases due to destruction of the capsule itself
The information recording medium according to claim 4, which is characterized in that: 6. The thermosensitive recording layer transmits infrared light.
5. The method according to claim 1, further comprising a substance to be attached.
Is the information recording medium according to claim 2 . 7. The information recording medium according to claim 1,
And a heat-resistant protective layer that transmits infrared rays on the photothermal conversion layer.
An information recording medium characterized by being formed by stacking . 8. The information recording medium according to claim 2,
There are, on the printing layer, the product of the heat-resistant protective layer which transmits infrared
An information recording medium comprising layers .