JP2003300385A - Laser thermal recording medium and recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly alteration-proof recording medium which is capable of recording the non-erasable frequency of use of a card or the non-erasable total sum (a balance) of charges for use of the card, when the preset frequency of the use and the preset total sum of charges for use of the card are close to the limits, although the history of use of the card can be repeatedly recorded until said frequency of the use and said total sum preset for the recording medium become close to the limits, and reminding the user that the limits to the frequency of use and the total sum of charges of the card are almost reached and further, is difficult to alter the card on account of the non-erasable records, and a recording method. <P>SOLUTION: The laser thermal recording medium comprises a light-absorptive layer, a heat-sensitive color developing layer, a heat-insulating intermediate layer, a reversible heat-sensitive color developing layer and a protecting layer laminated in that order on one side of a support. Also the recording method is provided. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser thermal recording medium and a recording method, and more particularly, it is possible to rewrite information when a card has a large usage frequency or usage balance. Further, the present invention relates to a laser thermal recording medium and a recording method capable of performing erasable recording when the amount near the end of the used balance.

[0002]

2. Description of the Related Art Conventionally, prepaid cards such as highway cards, stored fair cards, telephone cards, boarding tickets, coupons and amusement hall cards have been widely used. These cards can be used multiple times according to the usage frequency or the usage fee, and information such as the usage frequency or the usage fee is recorded on the recording surface of the card each time it is used, so that the usage history can be known. There is.

However, as the card becomes more expensive, the usage frequency naturally increases, and it is not possible to record the entire usage history on the back surface of the card. As a method of solving such a problem, there is also used a rewritable card which can erase old records in sequence to perform new records and repeat such erasing and recording.

[0004]

The above-mentioned rewritable card allows information to be easily erased and written by the thermal head of a commercially available thermal printer. On the other hand, the information recorded on the magnetic recording layer of the card cannot be erased. There is a fear that it will be modified and used as a modified card more than the specified frequency. Since such a modified card can be repeatedly rewritten, it is not easy to discover that it is a modified card.

Therefore, an object of the present invention is to repeatedly record the usage history of a card until the usage frequency or usage amount of the recording medium approaches a limit. When the amount of money used is near the limit, it is possible to record the usage frequency or the amount of money (balance) that cannot be erased, and it is possible for the user to know that the usage frequency or the amount of use of the card is near the limit.
(EN) Provided are a recording medium and a recording method which are excellent in tampering prevention, in which it is difficult to tamper with a card due to erasable recording.

[0006]

The above object can be achieved by the present invention described below. That is, the present invention is characterized in that a light absorbing layer, a thermosensitive coloring layer, a heat insulating intermediate layer, a reversible thermosensitive coloring layer, and a protective layer are laminated in this order on one surface of the substrate. A laser thermal recording medium is provided.

Further, the present invention is characterized in that a light-absorbing thermosensitive coloring layer, a heat insulating intermediate layer, a reversible thermosensitive coloring layer and a protective layer are laminated in this order on one surface of a substrate. A laser thermal recording medium is provided. In this embodiment, the thermosensitive coloring layer and the light absorption layer are the same layer in the above embodiment.

Further, in the present invention, a coloring layer, a thermosensitive destruction recording layer, a light absorbing layer, a heat insulating intermediate layer, a reversible thermosensitive coloring layer and a protective layer are laminated in this order on one surface of a substrate. Provided is a laser thermal recording medium characterized by the following. In this embodiment, the thermosensitive coloring layer in the above embodiment is a layer which disappears by heat like a vapor deposition layer of a metal or a metal compound, and information is recorded by a colored layer provided under the layer. In the above laser thermal recording medium, it is preferable that each layer formed on one surface of the substrate has substantially the same area as the surface of the substrate, and the recording area can be maximized.

According to the present invention, any one of the above laser thermal recording media of the present invention can be used for recording a reversible thermosensitive coloring layer with a thermal head up to the limit of the frequency of use or the amount of money used. Disclosed is a recording method characterized by performing irreversible recording on a thermosensitive coloring layer with a laser beam when erasing is repeated and the usage frequency or usage amount of the recording medium approaches a limit.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail with reference to the following preferred embodiments. 1 to 3 are diagrams schematically illustrating a cross section of a laser thermal recording medium of the present invention. The laser thermal recording medium of the present invention is most commonly in the form of a card, so a card will be described below as a typical example, but the laser thermal recording medium of the present invention is not limited to a card.

The card of the present invention, in the form shown in FIG.
A light absorbing layer 2, a thermosensitive coloring layer 3, a heat insulating intermediate layer 4, a reversible thermosensitive coloring layer 5, and a protective layer 6 are laminated on one surface of the card substrate 1 in this order. To do.
The form shown in FIG. 2 is one in which the thermosensitive coloring layer 3 and the light absorbing layer in FIG. 1 are integrated to form a light absorbing thermosensitive coloring layer 23, and the example shown in FIG. 3 is a layer recorded by laser light. Is a layer 24 that is destroyed by heat, such as a vapor-deposited layer of a metal or a metal compound having a relatively low melting point, and information is recorded by a colored layer 25 provided thereunder.

FIG. 4 illustrates a method of recording information on the card shown in FIG. 1 by using the thermal head 7 and the near infrared laser light 8. As shown in FIG. 4, the reversible thermosensitive coloring layer 5 develops color and information 9 such as characters is recorded by imagewise heating with a printer having a thermal head 7 through a protective layer 6 on the card surface. . This information can be, for example, date and time, location, fee,
The balance, etc. Such information is recorded, for example, at each use as shown in FIG. 5a, and as shown in FIG. 5b.
After the entire recording surface is recorded, the information of the old history is erased in order by heating by the thermal head 7 and the erasing head, and the following information is additionally recorded by the thermal head 7 in order in the erased recording area. This thermal head 7
The recording and erasing by means of recording and erasing are performed until the determined frequency and amount of money of the card are close to the limit (for example, about 1/2 of the recording surface going back from the limit).

When the card frequency or the amount of money approaches the limit, as shown in FIG. 4, a laser beam, for example, a near-infrared laser beam 8 is scanned and the heat generated by the photothermal conversion by the light absorption layer 2 causes heat. Information that cannot be erased on the thermosensitive coloring layer 1
0 is recorded. This information 10 is recorded as indicated by a triangle in FIG. 5c, the usage frequency and the remaining amount are recorded, and gives a warning to the user. As a result, the user can clearly know the remaining frequency or balance. On the other hand, by making the recorded information by the laser beam 8 unerasable, it becomes difficult to tamper with the card, and the excellent alteration prevention property of the card is exhibited.

Next, materials constituting the card of the present invention and the constitution thereof will be described. (Substrate) The substrate may be a conventional card substrate and is not particularly limited, and the material may be a conventionally known card substrate such as vinyl chloride resin, polyester resin, paper and nonwoven fabric. On the side of the base material 1 on which each recording layer is not provided, a route map, a map, various patterns, a card issuer, precautions, advertisements, and various other printings are applied in the same manner as a normal card. In general, it has a magnetic recording layer for recording the usage status of the card.

(Light Absorbing Layer) The light absorbing layer 2 in FIGS. 1 and 3 is a layer which, when recorded with the laser beam 8, efficiently absorbs the light and converts it into heat, and a thermosensitive coloring layer. It is preferable to use a colorless or light-colored light-absorbing material so as not to hinder the color development and suppress the background color. As such a light-absorbing material, a material that efficiently absorbs laser light, particularly laser light in the near-infrared region, and converts it into heat is used. Specifically, phthalocyanine-based, naphthalocyanine-based, metal complex System, metal sulfides and thiourea compounds, bisthiourea compounds, phosphorus compounds and copper compounds. You may mix these 2 or more types. The light absorption layer 2 is formed using ink or paint containing the above light absorption material and a binder. Its thickness is about 1
It is about 10 μm. The layer forming method includes gravure, roll coating, spray coating, dipping, and the like.

(Thermosensitive Coloring Layer) The thermosensitive coloring layer 3 (FIG. 1) is formed on the light absorbing layer 2. In the layer 3, the light absorbed by the light absorbing layer is converted into heat, and the heat causes recording in the layer 3. The layer 3 contains an electron-donating dye precursor and an electron-accepting compound which develop a color by a thermal melting reaction,
Further, if necessary, a sensitizer, an anti-fading agent, a filler such as a pigment or a lubricant, a dispersant and a binder are included. The thermosensitive coloring layer 3 is formed as a layer by coating, printing or the like on the light absorbing layer 2. The layer forming method is the same as described above.
As the electron-donating dye precursor, one applied to this type of heat-sensitive material as a leuco dye, and in the case of full color, one that develops yellow, cyan and magenta is selected (triphenylmethane type, fluorane type). System, phenothiazines, auramines, spiropyrans, indinophthalides, etc.).

The electron-accepting compound used as a developer in combination with an electron-donating dye precursor includes phenolic substances such as bisphenol A, octylphosphonic acid, nonylphosphonic acid, decylphosphonic acid,
There are organic acids such as dodecylphosphonic acid, tetradecylphosphonic acid, octadecylphosphonic acid, and erotic tetradecanoic acid, metal complex compounds, thiodiphenylurea, and quinones.

Examples of the sensitizer include stearic acid amide, behenic acid amide, methylenebisstearic acid amide, dibenzyl oxalate, tolylbiphenyl ether, and fatty acid amides. Examples of the anti-fading agent include analogues of a developer having a hydroxyl group blocked, organic metal salts such as zinc salt, and hindered phenols. When a pigment is used in combination, the pigment is required to have no concealing property, a high oil absorption amount, a high pH, and no activity to a dye. Also,
The white pigment has an effect of scattering visible light and near-infrared light to the surroundings, promotes absorption of near-infrared light into the light absorption layer 2 and increases heat generation efficiency. Examples of the pigment include calcium carbonate, aluminum hydroxide, silicate, zeolite, silica, kaolin clay, urea formalin resin and the like.

To form the thermosensitive coloring layer 3, an ink or paint is prepared to form a layer composed of the thermosensitive coloring agent. As a binder for ink or paint, a water-soluble resin is the main component, and polyvinyl alcohol, starch,
Examples include methyl cellulose, hydroxyethyl cellulose, gelatin, casein, urea resin, melanin resin, amide resin, polyurethane resin and the like. Further, various auxiliary agents can be added as necessary. The thickness of the thermosensitive coloring layer 3 is about 2
It is about 20 μm. The layer forming method is the same as described above.

(Adiabatic Intermediate Layer) An adiabatic intermediate layer 4 is provided on the thermosensitive coloring layer 3. When recording or erasing information on the reversible thermosensitive coloring layer 5 by heat, the intermediate layer 4 blocks the heat to suppress the coloring of the thermosensitive coloring layer 3, and when the thermosensitive coloring layer 3 is recorded by a laser. In addition, it has the effect of suppressing the color development of the reversible thermosensitive coloring layer 5 due to the heat from the light absorption layer 2. Such a heat insulating intermediate layer 4 is a resin which is inactive to the dye of the thermosensitive coloring layer 3, for example, polyvinyl alcohol, starch, methyl cellulose, hydroxyethyl cellulose, gelatin, casein, urea resin, melanin resin, amide resin. , A substantially transparent solution such as polyurethane resin is applied on the light absorption layer 2. The thickness of the intermediate layer 4 is about 1 to 3 μm, and if the thickness is too thin, the above-mentioned object cannot be achieved. On the other hand, if the thickness is too large, a large amount of energy is required for color development of the thermosensitive color developing layer 3 located below. Become. The layer forming method is the same as described above.

(Reversible thermosensitive coloring layer) The heat insulating intermediate layer 4
A reversible thermosensitive coloring layer 5 is provided on the top. Reversible thermosensitive coloring layer 5
Is formed of a material in which information can be written and erased by heat, and such materials are known in the art and can be obtained from the market and used. A typical example is one composed of a resin and an organic low molecular weight substance dispersed in the resin (Japanese Patent Laid-Open No. Hei.
-92658, Japanese Patent Application Laid-Open No. 7-314899, etc.), those in which a leuco dye and a color developer are dispersed in a resin (see Japanese Patent Application Laid-Open No. 2000-5934, etc.) and the like. The reversible thermosensitive coloring layer 5 made of these materials has already been commercialized. For example, a reversible thermosensitive coloring layer having a thickness of 5 to 15 μm is coated on a base material sheet or film such as a polyethylene terephthalate film having a thickness of 25 μm. The formed product can be cut into an appropriate size for use.

(Protective Layer) On the above reversible thermosensitive coloring layer 5,
The protective layer 6 is provided in order to prevent heat and scratches from the outside during carrying and further damage to the reversible thermosensitive coloring layer 5 during recording or erasing of information. An anchor layer or the like may be provided between these layers in order to secure the adhesion of the protective layer 6 to the reversible thermosensitive coloring layer 5. As the protective layer 6, a thermoplastic resin sheet having excellent surface durability such as scratch resistance is used. Examples of the resin for the protective layer include polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and polyethylene terephthalate obtained by copolymerizing cyclohexanedimethanol (PET-
G), acrylic resin, polycarbonate resin, polystyrene resin, ABS resin, polypropylene, polyethylene, etc., and those having a hard coat layer made of a radiation curable resin on one surface of a sheet of these resins are used. It The thickness of these protective layers is usually about 30-
It is 200 μm. In the card of the present invention, the protective layer 6 must be transparent so that the infrared laser can pass through it and the displayed information can be clearly seen. The layer forming method is the same as described above.

(Light-Absorbing Thermosensitive Coloring Layer) The light-absorbing thermosensitive coloring layer 23 shown in FIG. 2 is prepared by mixing the above-mentioned light-absorbing material with the thermosensitive coloring layer 3 shown in FIG. The layer structure is simplified in manufacturing the card. The layer 23 has the functions of both the light absorbing layer 2 and the thermosensitive coloring layer 3.
Its thickness is usually about 2 to 20 μm. The layer forming method is the same as described above.

(Thermal Breaking Recording Layer) The thermal breaking recording layer 24 shown in FIG. 3 is provided between the substrate 1 and the light absorbing layer 2 with the colored layer 25 interposed therebetween. The heat-sensitive destruction recording layer 24 is destroyed by heat to lose the layer, and the colored layer 2 formed thereunder
5 appears, and the colored layer 25 appears in an image shape to record information. As the material for forming the thermal destructive recording layer 24, in addition to metals such as tin-based, tellurium-based, and bismuth-based metals, which are generally used metal-based optical recording materials having a relatively low melting point, or oxides thereof, Examples include organic phthalocyanine dyes and naphthoquinone dyes. The thickness of the heat-sensitive destruction recording layer 24 is usually 100 to
It is about 1000Å. The layer formation method is preferably vapor deposition or sputtering.

(Coloring Layer) The coloring layer 25 shown in FIG. 3 may be any color such as black or blue, and can be formed by applying a suitable paint or ink on the surface of the base material. The thickness of the colored layer is not particularly limited as long as it is a concentration that can be easily recognized by the naked eye. In the above structure, the layers closer to the surface than the thermosensitive coloring layer 3 or the thermosensitive destruction recording layer 24 need to be transparent to the extent that the information 9 and 10 formed in these layers can be visually observed.

[0026]

EXAMPLES Next, the present invention will be described more specifically with reference to Examples and Comparative Examples. Example 1 As shown in FIG. 1, as a base material 1, a polyethylene terephthalate film having a thickness of 188 μm (E-20, manufactured by Toray).
An aluminum vapor deposition layer (not shown) having a thickness of several hundred liters was provided on the top. Using this as a support, a light absorbing layer 2, an irreversible thermosensitive coloring layer 3, a heat insulating intermediate layer 4, a reversible thermosensitive coloring layer 5 and a protective layer 6 having the following composition are sequentially formed by a gravure printing method, A card (laser thermal recording medium) was obtained.

The light absorbing layer 2 is made of a near infrared light absorbing material (S11).
0510, manufactured by ICI), a solvent (a 10% by weight aqueous solution of polyvinyl alcohol) and an isocyanate curing agent were mixed to form a film having a thickness of 1 to 2 μm after drying. The irreversible thermosensitive coloring layer 3 includes a black coloring dye (3- (N-ethyl-Nacylamino) -6-methyl-7-anilinofluorane), a developer (bisphenol A) and a solvent (polyvinyl alcohol 10% by weight aqueous solution). ) Was applied, dried, and then formed on the light absorption layer 2 so as to have a film thickness of 5 μm. At this time, both the dye and the color developer were sufficiently dispersed in a sand mill to form a paint having an average particle size of 0.3 μm so that the transmittance of visible light and near-infrared light was not disturbed as much as possible.

The heat insulating intermediate layer 4 was formed by using a 10% by weight aqueous solution of polyvinyl alcohol so as to have a film thickness of 2 μm after drying. The reversible thermosensitive coloring layer 5 is stearic acid,
A mixture of a vinyl chloride-vinyl acetate-phosphate ester copolymer and a solvent (tetrahydrofuran) was applied and dried to form a film thickness of 10 μm. Also,
A protective layer 6 for improving weather resistance and scratch resistance was formed from an ultraviolet curable resin (urethane acrylate) to a thickness of 3 μm.

For the card obtained as described above,
As shown in FIG. 4, when additional writing was performed with the semiconductor laser light 8 having a wavelength of 780 nm, additional writing only on the irreversible thermosensitive coloring layer 3 was possible. On the other hand, when writing was performed by the thermal head 7, recording was possible on the reversible thermosensitive recording layer 5. Further, erasing with the thermal head 7 made it possible to erase the information 9 on the reversible thermosensitive recording layer 5.

Example 2 A polyethylene terephthalate film (E-20, manufactured by Toray) having a thickness of 188 μm was used as the substrate 1, and a black ink made of a polyester resin containing carbon black was used to form a film having a thickness of 2 μm on the surface thereof. The colored layer 25 was formed. Further, an anchor layer having a thickness of 0.5 μm was formed on this with a resin of vinyl chloride-vinyl acetate copolymer. Using this as a support, the thermosensitive recording layer 2 having the following composition
4, a heat insulating intermediate layer 4, a reversible thermosensitive recording layer 5 and a protective layer 6 were sequentially formed to obtain a card (laser thermal recording medium) of the present invention.

The heat-sensitive destructive recording layer 24 was formed by vacuum-depositing tin having a thickness of 800 Å on the anchor layer. Next, the light absorption layer 2 is coated on the metal thin film layer 24 with a mixture of a near infrared light absorption substance (S110510, manufactured by ICI), a solvent (10% by weight polyvinyl alcohol aqueous solution) and an isocyanate curing agent, and dried. After that, it was formed to have a film thickness of 1 to 2 μm. Example 1 after the heat insulating intermediate layer 4
Was prepared in the same manner as in.

For the card thus obtained,
When additional recording was performed with the semiconductor laser beam 8 having a wavelength of 780 nm, additional recording was possible only on the thermal break recording layer 24. On the other hand, when writing was performed by the thermal head 7, recording was possible on the reversible thermosensitive recording layer 5. Furthermore, when the above-mentioned recording was erased by the thermal head 7, it was possible to erase the recording of the reversible thermosensitive recording layer 5.

[0033]

According to the present invention, the usage history of the card can be repeatedly recorded until the determined usage frequency or usage amount of the recording medium approaches the limit. When the amount used is near the limit,
It is possible to record the usage frequency or usage amount (balance) that cannot be erased, so that the user can know that the usage frequency or usage amount of the card is close to the limit, and it is difficult to alter the card due to the non-erasable recording. It is possible to provide a recording medium and a recording method excellent in alteration prevention property.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a cross section of an example of a laser thermal recording medium of the present invention.

FIG. 2 is a diagram illustrating a cross section of another example of the laser thermal recording medium of the present invention.

FIG. 3 is a diagram illustrating a cross section of another example of the laser thermal recording medium of the present invention.

FIG. 4 is a diagram illustrating a method of the present invention.

FIG. 5 is a diagram illustrating a method of the present invention.

[Explanation of symbols]

1: Base material 2: Light absorption layer 3: Thermosensitive coloring layer 4: Adiabatic middle layer 5: Reversible thermosensitive coloring layer 6: Protective layer 7: Thermal head 8: Near infrared laser light 9: Information 10: Information 23: Light-absorbing thermosensitive coloring layer 24: Thermosensitive recording layer 25: Colored layer

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme coat (reference) B41J 3/20 109E F term (reference) 2C005 HA01 HB04 JA01 JA09 JA25 JB40 JC02 JC03 KA02 KA03 KA06 KA15 KA27 KA28 KA53 KA54 KA70 LB04 LB07 LB08 LB18 LB25 LB33 LB36 2H026 AA07 AA24 BB01 BB21 DD53 FF01 FF11 FF13 FF22 2H111 HA07 HA14 HA18 HA22 HA23 HA35

Claims (5)

[Claims] 1. A laser comprising a light absorbing layer, a thermosensitive coloring layer, a heat insulating intermediate layer, a reversible thermosensitive coloring layer, and a protective layer, which are laminated in this order on one surface of a substrate. Thermal recording medium. 2. A laser thermal comprising a light-absorbing thermosensitive coloring layer, a heat insulating intermediate layer, a reversible thermosensitive coloring layer, and a protective layer, which are laminated in this order on one surface of a substrate. recoding media. 3. A substrate comprising a colored layer, a thermosensitive recording layer, a light absorbing layer, a heat insulating intermediate layer, a reversible thermosensitive coloring layer, and a protective layer, which are laminated in this order on one surface of the substrate. Characteristic laser thermal recording medium. 4. The laser thermal recording medium according to claim 1, wherein each layer formed on one surface of the substrate has substantially the same area as the surface of the substrate. 5. The laser thermal recording medium according to claim 1, wherein a reversible thermosensitive coloring layer is formed on the laser thermal recording medium by a thermal head up to the limit of the frequency of use or the amount of money used. A recording method characterized by performing irreversible recording on a thermosensitive color developing layer with a laser beam when recording and erasing are repeated and when the usage frequency or the usage amount of the recording medium approaches a limit.