JPS62278084A - Recording medium - Google Patents

Abstract

PURPOSE:To obtain a recording medium having information not visually discriminable and having excellent anti-forgery properties, by sequentially providing a thermal color forming layer comprising a leuco dye heat-sensitive material or a diazo heat sensitive material and a hiding layer on a base. CONSTITUTION:A thermal color forming layer 1, a hiding layer 2 and, if required, a protective layer 3 are sequentially provided on a base 10. The base 10 is formed from a plastic, a metal, a paper, an impregnated paper or the like, used either singly or as a composite material. The thermal color forming layer 1 functions as an information-recording layer for recording information through color forming by heating by a thermal head, and comprises a leuco dye heat-sensitive material or a diaso dye heat-sensitive material as a thermal color forming material and a binder containing necessary additives. The hiding layer 2 hides color-developed parts and undeveloped parts of the thermal color fomring layer, in an invisible state. From the viewpoint of heat resistance, a coloring agent used in the hiding layer 2 is preferably a pigment, and is preferably one having high reflectance in a visible light range and high transmittance in an IR region. The protective layer 3 for enhancing abrasion resistance is provided, if required, on the hiding layer 2.

Description

[Detailed description of the invention] 3. Detailed description of the invention (Industrial application field) The present invention relates to a recording medium on which information can be recorded and reproduced.

(Prior art) In a thermosensitive recording medium having a thermosensitive coloring layer made of a leuco dye, a diazo compound, etc. as a base material, information can be easily recorded on the thermosensitive coloring layer by heating with a thermal head, etc., and due to the convenience of the recording method. Widely used. however,
Since the information recorded on these cannot be recorded in a way that is invisible to the naked eye, it is limited to content that can be seen by a third party, and is not known to a third party such as recorded on a general magnetic card. Important information could not be recorded, causing inconvenience. That is, regardless of the simplicity of the recording method, it has not been possible to utilize a thermosensitive recording medium as a recording medium with excellent anti-counterfeiting properties that can contain information that cannot be determined visually.

(Problems that the invention attempts to solve) The present invention has been made in view of the above points.

The present inventor has discovered that a conventional heat-sensitive coloring layer made of a leuco dye or a diazo compound can be used with a thermal head even if a hiding layer made of a resin layer containing an ink pigment is provided on the layer.
Noting the good color development, various studies were conducted with the idea of utilizing this phenomenon in optical recording means. As a result, if a laminate consisting of a heat-sensitive coloring layer and a hiding layer is formed and an information pattern is printed with a thermal head, the information pattern formed by coloring on the heat-sensitive coloring layer cannot be seen visually due to the hiding layer, but it is irradiated with infrared rays. The researchers discovered that the colored areas have a low infrared reflectance, while the uncolored areas have a different infrared reflectance, and that this difference in reflectance can be used to read the printed information pattern, leading to the present invention. It was achieved.

(Means for Solving the Problems) The recording medium of the present invention is characterized in that a heat-sensitive coloring layer and a hiding layer made of a leuco dye-based heat-sensitive material or a diazo-based heat-sensitive material are sequentially laminated on a base material. It is something to do.

Hereinafter, the present invention will be described in detail based on Examples.

FIG. 1 is a cross-sectional view showing one embodiment of the present invention, in which a heat-sensitive coloring layer 1, a hiding layer 2, and a protective layer 3 provided as necessary are laminated in this order on a base material 10.

The base material 10 basically functions to support each layer to be laminated, but it can take various shapes depending on its intended use.For example, the recording medium of the present invention may be applied to other articles. A thin film is suitable for use as a storage medium such as a magnetic tape or as a recording medium such as a magnetic tape, and a card is suitable for use as a recording medium that can be easily handled in its own right. Suitable shapes include those for general plastic cards, paper cards, bankbooks, and other commonly used recording media.

For the reasons mentioned above, various materials can be used for the base material 10, such as polyvinyl chloride, polyvinylidene chloride, nylon, cellulose diacetate, ethylene vinyl acetate, cellulose triacetate, polystyrene, polypropylene, Plastics such as polyester, polyimide, polyamide, polymethyl methacrylate, polyacrylate, polyurethane, ionomer, polycarbonate, metals such as copper and aluminum, paper, impregnated paper, etc. can be used alone or in combination as a composite. A preferable material may be appropriately selected from among the above-mentioned materials in consideration of the physical properties required for the base material, such as strength and rigidity.

A thermosensitive coloring layer 1 is provided on the base material 10.

The thermosensitive coloring layer 1 functions as an information recording layer in which information is recorded by coloring when heated by a thermal head, and contains a thermosensitive coloring material such as a leuco dye-based thermosensitive material or a diazo dye-based thermosensitive material and necessary additives. It is formed from a binder that encapsulates.

The leuco dye-based thermosensitive coloring material used in the thermosensitive coloring layer 1 can be one consisting of a leuco dye and an acidic substance. For example, the leuco dye includes: (1) Leuco base of triphenylmethane dye; 3.3°-bis (p-dimethylaminophenyl)phthalide, 3.3'-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide, 3.3°
-bis(p-dimethylaminophenyl)-6-dibutylaminophenyl, 3,3'-bis(p-dimethylaminophenyl)-6-chlorophthalide, 3.3'-, bis(p-dibutylaminophenyl) phthalide, etc. , (2) Leuco base of fluoran dye; 6-cyclobenzylamino-6-chlorofluoran, 3-(N,N-dimethylamino)-5-methyl-7-(N.

N-dibenzylamino)fluoran, 3-diethylamino-5,7-dimethylfluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-7,8
-benzfluorane, etc., ■Fluoran dye; 3-diethylamino-6-methyl-7-chlorofluoran, 3-
Virolidino-6-methyl-7-ayurinofluorane, 2
- (N-(3''-trifluoromethylphenyl)aminoco-6-dinithylaminofluorane, 2-3.6-
Bis(diethylamino)-9-(O-chlorophenyl)
xantylbenzoic acid lactam, etc. ■Lactone compound; 3
-(2'-hydroxy-4''-dimethylaminophenyl)-3-(2'-methoxy-5'-chlorophenyl)
Phthalide, 3-(2'-bitroxy-4'-dimethylaminophenyl)-3-(2'-methoxy-5'-nitrophenyl)phthalide, 3-(2'-hydroxy-
4°-dimethylaminophenyl)-3-(2′-methoxy-5′-methylphenyl)phthalide, 3-(2”-
Methoxy-4'-dimethylaminophenyl)-3-(2
゛-Hydroxy-4°-chloro-5゛-methylphenyl)phthalide, etc. can be used. In addition, acidic substances that are coloring aids include boric acid, oxalic acid, maleic acid, tartaric acid, citric acid, succinic acid, benzoic acid, stearic acid, gallic acid, salicylic acid, 1-hydroxy-2-naphthoic acid,
0-hydroxybenzoic acid, m-hydroxybenzoic acid, 2
．． 4-dihydroxybenzoic acid, 2-hydroxy-P-toluic acid, 3.5-xylenol, thymol, p-t-
Butylphenol, 4-hydroxyphenoxide, methyl-4-hydroxybenzoate, 4-hydroxyacetophenone, β-naphthol, β-naphthol, catechol, resorcinol, hydroxylone, 4-t-octylcatechol, 4+ 4'-se c-butyl Lydenphenol, 2.2'-hydroxydiphenyl, 2.
2°-methylenebis(4-methyl-6-t-butylphenol), 2°2″-bis(4′-hydroxyphenyl)propane, 4.4°-5ec-butylidene diphenol, pyrogallol, phloroglycine, phloroglycine carbonate Acids etc. can be used.

Further, the diazo dye-based thermosensitive coloring material can be one consisting of a diazo compound, a coupler agent and a base agent, for example,
As a diazo compound, the general formula A r-N=N=X-M
In the linear formula, Ar is a substituted or unsubstituted phenyl, biphenyl, naphthyl, benzocarbazole, diphenyl sulfide group, X is a halogen or an acid residue such as HSO4, and M is zinc chloride. , cadmium chloride or boron tetrafluoride can be used.

Further, as the coupler agent, substituted or unsubstituted phenol, naphthol, resorcinol, catechol, etc. can be used.

Further, as the base agent, urea, thiourea, guanidine, etc. can be used.

Additives added to the above heat-sensitive coloring materials include calcium carbonate, silica, magnesium oxide, talc, barium sulfate, alumina, paraffin wax, microcrystalline wax, polyethylene wax, beeswax, autologous wax, carnauba wax, stearic acid, stearin. Acid amides, metal stearates, etc. can be used, and binders include polyvinyl alcohol, methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, polyvinylpyrrolidone, polyacrylamide, polyacrylic acid, starch, water-soluble resins such as gelatin, and polystyrene. , vinyl acetate-vinyl chloride copolymer, polybutyl methacrylate, and other aqueous emulsion resins can be used.

The thermosensitive coloring layer 1 is formed on the entire surface or a part of the base material using the above-mentioned materials by a suitable coating method, such as a roll coating method, an air knife coating method, or a gravure coating method, to a coating thickness of 1 to 20 μm.

The hiding layer 2 is a layer provided on the thermosensitive coloring layer 1 in order to hide the colored portion and the uncolored portion of the thermosensitive coloring layer from visual visibility, and may be formed of a single layer of a colored layer, or,
It may be formed in a laminated structure, for example, in a plurality of layers in which a pattern layer for giving a designed appearance is provided on a colored layer.

Furthermore, since the concealing layer 2 comes into contact with the thermal head, it is necessary to have a certain degree of heat resistance and abrasion resistance.

In the concealing layer 2, it is desirable to use a pigment as the colorant from the viewpoint of heat resistance, and the optical properties of the pigment include high reflectance in the visible light region and high transmission in the infrared region. Something is desirable. Furthermore, dyes can be used as long as they have the above characteristics.

Such a hiding layer 2 is made of an ink composition obtained by kneading a pigment or dye having the above characteristics with a fluorine-containing resin, a silicon-containing resin, or ethyl cellulose, ethyl hydroxycellulose, cellulose acetate propionate, Cellulose derivatives such as cellulose acetate, styrene resins or styrene copolymer resins such as polystyrene and poly-α-methylstyrene, acrylic resins or methacrylates such as polymethyl methacrylate, polyethyl methacrylate, polyethyl acrylate, and polybutyl methacrylate. An ink composition formed by mixing an acid resin alone or with a copolymer resin,
Alternatively, it can be mixed with rosin, rosin-modified phenolic resin, rosin ester resin such as polymerized rosin, polyvinyl acetate resin, coumaron resin, vinyl toluene resin, vinyl chloride resin, polyester resin, polyurethane resin, vinyl butyral resin, butyral resin, etc. or an ink composition obtained by kneading the above resin with a fluororesin and a silicone resin, and a plasticizer, a stabilizer, a wax, a grease, a desiccant, a drying aid, a curing agent,
After adding thickeners, dispersants, etc., the ink prepared by sufficiently kneading with a solvent or diluent is used to print using an appropriate printing method, such as offset printing, silk screen printing, letterpress printing, static printing, etc. It is formed with a layer thickness of 1 to 20 μm by a printing method or coating method such as an electroprinting method, an intaglio printing method, a gravure coating method, a roll coating method, or a knife coating method.

A protective layer 3 can be provided on the concealing layer 2 if necessary to improve the abrasion resistance.

Such a protective layer 3 can be formed using a resin used for the concealing layer, or by using a resin mixed with a fluorine-based resin or a silicon-based resin, using a printing method or coating method similar to the method for forming the concealing layer. It is formed with a thickness of 0.5 to 10 μm.

Further, in the present invention, an infrared reflective layer 4 can be provided between the thermosensitive coloring layer 1 and the base material 10, as shown in a cross-sectional view in FIG.

The infrared reflective layer 4 has the function of amplifying the difference in infrared reflectance between the colored portion and the uncolored portion of the thermosensitive coloring layer, and can be made of a wide variety of materials as long as it reflects infrared rays, such as metal. A thin film layer, a titanium white layer, a plastic film containing metal powder, a plastic film with a high pigment content, etc. can be used.

The infrared reflective layer 4 is formed using the above-mentioned materials by an appropriate forming method, such as a vacuum evaporation method, a printing method, a coating method, or a lamination method, but its thickness is not particularly limited.

Further, the present invention can also adopt an embodiment in which the adhesive layer 5 is provided on the base material on the opposite side of the heat-sensitive coloring layer, as shown in a cross-sectional view in FIG.

The adhesive layer 5 is used when the recording medium of the present invention is bonded to other articles, and is formed of an adhesive or a pressure-sensitive adhesive including a heat-sensitive adhesive.

As the adhesive, a wide range of commonly used adhesives can be used, such as rubber resins such as polyisoprene rubber, polyisobutyl rubber, styrene-butadiene rubber, butadiene-acrylonitrile rubber, polyacrylic resins, and polyacrylic resins. Acid ester resin, polymethacrylic acid resin, polyvinyl resin, polyvinyl ether resin, polyvinyl acetate resin, vinyl chloride vinyl acetate copolymer resin, polystyrene resin, polyester resin, polyamide resin, polychlorine Any adhesive made of chemical olefin resin, polyvinyl butyral resin, etc. can be used.
Further, as the adhesive, a general adhesive can be used, and for example, an adhesive made of polyacrylic resin, rubber resin, etc. can be used.

The adhesive layer 5 is formed to an appropriate thickness of 1 to 10 mm by a conventional printing method or coating method using the above-mentioned adhesive or pressure-sensitive adhesive.
It is formed with a thickness of 0 μm.

Next, a method of using the recording medium of the present invention configured as described above will be explained.

First, desired information is converted into a pattern, such as a dot representing 1°0, a bar code, an OCR character, a general character, or a symbol, and is printed from the hidden layer base using a thermal head. Although the information recorded at this time cannot be visually observed, it is recorded on the thermosensitive coloring layer in the form of color development of the thermosensitive coloring layer.

Next, an infrared projector (one that emits infrared rays with a wavelength of 700 nm or more, preferably 900 nm or more) scans the recording medium to read information, and then passes through the hiding layer to the thermosensitive coloring layer. The reflected infrared rays are detected by a receiver, and the recorded information is read from the amount of received light.

(Effects of the Invention) Since the recording medium of the present invention can record information invisibly, it can be used in the same way as general magnetic tape, and like magnetic tape, it can be used with commercially available instruments and devices such as Magnetic Pure. The information cannot be easily read and has extremely high anti-counterfeiting properties.

Furthermore, if a card substrate is used as the base material of the present invention, it can be used as an information recording card that can be used in the same way as a general magnetic card.

Furthermore, there are many conversion patterns for the information to be recorded, and anything from a dot representing 1.0 to a letter can be arbitrarily selected, and the recording method can be easily performed using a thermal head.

Furthermore, if the recording medium of the present invention is provided on a recording medium such as a magnetic card, an IC card, an optical card, or a magnetic passbook using the adhesive of one embodiment of the present invention, further information can be added. At the same time, the anti-counterfeiting properties are also improved.

The present invention will be explained in more detail with reference to specific examples.

Example 1 Ink A and ink B having the following composition were placed on a 250 μm thick polyethylene terephthalate film as a base material.
Using the ink obtained by mixing and stirring so that it becomes 2,
A thermosensitive coloring layer was formed with a thickness of 5 μm by gravure coating.

A concealing layer was formed with a thickness of 3 μm using a gravure coating method.

Next, a protective layer was formed on the hiding layer to a thickness of 1 μm by gravure coating using an ink having the composition shown below to obtain a recording medium of the present invention.

[Thermosensitive coloring layer ink A]

Fluorane leuco dye 20 parts Polymethyl methacrylate resin 20 parts Paraffin wax 4 parts Toluene
56 parts [Thermosensitive coloring layer ink B] 2.4 dihydroxybenzoic acid 20 parts Polymethyl methacrylate 20 parts Paraffin wax
4 parts toluene
56 parts [Hidden layer] Tetrafluoroethylene powder 5 parts Urethane resin 20 parts Isocyanate curing agent 1 part Pigment
10 parts Methyl ethyl ketone 30 parts Toluene 30 parts [Protective layer] Tetrafluoroethylene powder 10 parts Polyvinyl butyral resin 10 parts Moisture-curing urethane resin 10 parts Methyl ethyl ketone
30 parts toluene 30 parts ethyl acetate 30 parts Example 2 Tin was formed at 100 OA on polyethylene terephthalate with a thickness of 250 μm as a base material by vacuum evaporation method,
An infrared reflective layer was formed.

Next, a protective layer was formed on the infrared reflective layer in the same manner as in Example 1 to obtain a recording medium of the present invention.

Example 3 A protective layer was formed on polyethylene terephthalate having a thickness of 250 μm as a base material in the same manner as in Example 2.

Next, an adhesive layer was formed on the opposite side of the base material to a thickness of 10 μm by gravure coating using an ink having the composition shown below to obtain a recording medium of the present invention.

[Adhesive layer]

Vinyl chloride vinyl acetate copolymer 20 parts Polyacrylic resin 10 parts Ethyl acetate
20 parts toluene
50 copies

[Brief explanation of drawings]

1, 2 and 3 are cross-sectional views of the recording medium of the present invention. 1...Thermosensitive coloring layer 2...Hidden layer 3...Protective layer 4...Infrared reflective layer 5...Adhesive layer 10...Base Figure 1 Figure 2 Figure 2

Claims (4)

[Claims] (1) A recording medium characterized in that a heat-sensitive coloring layer and a hiding layer made of a leuco dye-based heat-sensitive material or a diazo-based heat-sensitive material are sequentially laminated on a base material. (2) The recording medium according to claim (1), characterized in that a protective layer is provided on the hiding layer. (3) The recording medium according to claim (1) or (2), characterized in that an infrared reflective layer is provided between the base material and the thermosensitive coloring layer. (4) The recording medium according to any one of claims (1) to (3), characterized in that an adhesive layer is provided on the opposite side of the thermosensitive coloring layer of the base material.