JPH06122272A - Recording method - Google Patents

Abstract

PURPOSE:To conduct the inscription of information and the input of recording, etc., simply and easily, and enable reading only by a specific means in spite of an unreadable state by naked eyes in general. CONSTITUTION:In the recording method of image information, in which a colored region consisting of infrared absorptive dyestuffs and a colored region composed of IR reflective dyestuffs are superposed and formed in parallel on an arbitrary base body, a thermal color developing system is used as the recording method, images such as characters numerals marks, patterns, etc., are formed in at least one of the colored regions, and two kinds of the colored regions cannot be discriminated or are difficult to be discriminated substantially by naked eyes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recording image information, and more particularly to a method for recording image information which is invisible to the naked eye and readable only by infrared rays.

[0002]

2. Description of the Related Art Conventional banknotes, checks, airline tickets, road tickets, tickets, admission tickets, prepaid cards, for example, telephone charge cards, ticket purchase cards, admission ticket purchase cards, games Cards related to automatic payments such as fee cards and identification cards, bank deposit number cards, etc., as well as concealment of confidential documents, materials, information, etc.
It may be necessary to keep the recorded image information such as letters, numbers, symbols, patterns, etc. secret to a third party and conceal it from being misused. In many cases, magnetic recording is performed using magnetic ink. Was.

However, in the system using the magnetic ink, there is a problem that the magnetic strength is changed or disappears when the magnetic material used is exposed to heat or exposed to a strong magnetic field environment. is there. Further, when forming a magnetic mark, it is quite difficult to evenly disperse the magnetic substance in the ink, and it is difficult to store it stably and apply it uniformly. There is a problem that is. Therefore, an object of the present invention is that the entry of information, the input of records, etc. can be performed easily and easily, and in general, it is unreadable by the naked eye,
An object of the present invention is to provide a recording method of image information that can be read only by a specific means.

[0004]

The above object can be achieved by the present invention described below. That is, the present invention is a method for recording image information in which a colored region made of an infrared absorbing dye and a colored region made of an infrared reflecting dye are formed in parallel or in layers on an arbitrary substrate, and the recording method is a thermosensitive coloring method. Yes,
At least one of the colored areas is an image of characters, numbers, symbols, patterns, etc., and the two types of colored areas are substantially indistinguishable or difficult to discern with the naked eye.

[0005]

Function: Information is written, recorded, etc. by recording image information consisting of a colored area composed of an infrared-absorbing dye and a colored area composed of an infrared-reflective dye on a desired substrate in parallel or in superimposition by a thermosensitive coloring system. Can be easily and easily input, and it is possible to record image information which is generally unreadable by the naked eye and can be read only by a specific means.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described in more detail with reference to preferred embodiments. Examples of the substrate used in the present invention include paper, synthetic fiber-mixed paper, synthetic paper,
A conventionally known recordable or recordable substrate such as a plastic film or a plastic sheet is used. The shape of the substrate to be used is not limited to each standard size, but may be a cut card size.

In the present invention, the method of recording information on the above-mentioned substrate with an infrared absorbing dye and an infrared reflecting dye which will be described later is a thermosensitive coloring system. To describe the dyes used in the recording method of the present invention, in the present invention, at least one of the above-mentioned two kinds of dyes utilizes an intermediate of the dyes which produces any of the above-mentioned dyes. The intermediate of the dye includes a case where the color is developed immediately and a case where the color is developed by separately acting a color developer. Infrared absorbing dyes used to form image information such as letters, numbers, symbols and patterns, or dyes formed from intermediates of dyes, have large absorption in the infrared region used for detection, and It is necessary that the reflectance of infrared rays be distinctly low or almost nonexistent.

Further, the infrared reflective dye used for hiding or deceiving the image information with the naked eye or the dye formed from an intermediate of the dye is in the infrared region utilized for the above detection. It is necessary to have sufficient reflectance to show a clear difference from the low reflectance due to absorption of For example, as the dye intermediate, all known dyes having the above-mentioned properties and intermediates that give rise to the dye can be used.

For example, compounds containing oxine and its derivatives such as oxine, alkyl oxine, and dichlorooxine and heavy metal ions such as ferric ion and vanadium ion, for example, water-soluble inorganic salts, lower fatty acid salts, higher fatty acid salts. By processing with a combination with etc.,
It forms a colored chelate compound that absorbs infrared rays.

As an infrared absorbing dye or an intermediate thereof used for inputting and recording image information, any conventionally known pigment or dye having such properties or an intermediate thereof can be used, and it is particularly preferable. Things are, for example,
Examples thereof include carbon black pigments, aniline black pigments, iron oxide black pigments, titanium oxide-based black pigments, spinel structure-based black pigments and the like, and intermediates thereof.

As the infrared-reflective dye or its intermediate used for hiding or deceiving image information with the naked eye to make it indistinguishable, use of a conventionally known dye or intermediate having such properties. Examples of organic pigments and dyes or intermediates include phthalocyanines, azos, azomethines, azomethinesazos, anthraquinones, perinones / perylenes, indigo / thioindigos, dioxazines, quinacridones, isoindones. It is a pigment or dye such as linone or an intermediate thereof, and the pigment or the intermediate thereof is used alone or in combination of two or more kinds.

Among the above infrared-reflecting dyes or intermediates, particularly preferred dyes having an azomethine group or intermediates thereof are described, for example, in JP-A-58-174446 and JP-A-59-4775. Patent No. 10638
16, Japanese Patent No. 1052019, Japanese Patent No. 11415114, Japanese Patent No. 1141515, Japanese Patent Application No. 60-168540, Japanese Patent Application No. 60-
And the dyes or intermediates disclosed in 277929.

Particularly, an azo pigment having an azomethine group, which uses 2-hydroxy-α-benzocarbazole-carborbonic acid allylamide and its derivative as a coupling component, shows a dark green to black color tone under visible light,
Particularly in black, it shows a clear black color with a high degree of blackness. However, it hardly absorbs infrared rays and exhibits high reflectivity. The dye having an azomethine group described above is excellent in heat resistance, light resistance, water resistance and chemical resistance, and further has high coloring power. Further, the pigment type dye further exhibits extremely excellent solvent resistance.

The above is an example of an infrared-reflecting dye or an intermediate thereof which is particularly preferably used in the present invention. However, in the present invention, other dyes or mixed colors such as red,
Blended colors obtained by mixing blue, yellow, orange, violet, green and brown dyes can also be used as the infrared reflective dye.
Incidentally, in the present invention, the "infrared reflective dye" means a case where the object itself reflects infrared light and the object itself transmits infrared light, but a substrate coated with the dye, for example, a paper or a plastic sheet, It means both a dye having a property of reflecting infrared rays by a metal or the like and transmitting the infrared rays again through the colored portion to emit infrared rays. Therefore, in the present invention, a dye having high infrared transparency is also included in the "infrared reflective dye" in the present invention.

The above-mentioned dye or dye intermediate is used as a recording ink or the like containing them or as a coating agent. For example, it is used in the same constitution as a conventionally known recording ink or the like and a coating agent system. For example, an aqueous system is an aqueous solution system, an aqueous emulsion system, an aqueous dispersion system or a mixed system thereof, and also in an oil system. , An oily solution system, an oily emulsion system, an oily dispersion system or a mixed system thereof.

The resin components used in these recording inks and coating agents are conventionally known, and as the aqueous resin, casein, sodium alginate, gum arabic, ethyl cellulose, hydroxyethyl cellulose, polyvinyl alcohol, styrene. -Water-soluble salt of maleic acid ester-based copolymer, water-soluble salt of (meth) acrylic ester-based (co) polymer, water-soluble salt of styrene- (meth) acrylic ester latex, water-soluble alkyd-based resin, styrene- Butadiene-based copolymer latex,
(Meth) acrylic ester-based copolymer latex, styrene- (meth) acrylic ester-based copolymer latex, ethylene-vinyl acetate-based copolymer latex, polyethylene-based disversion, ethylene-based copolymer-based disversion and the like. .

As the oil-based resin component, cellulose acetate butyrate resin, nitrocellulose resin, vinyl acetate (co) polymer, styrene (co) polymer, vinyl chloride-vinyl acetate copolymer Coal, ethylene-vinyl acetate copolymer, polyvinyl butyral resin, alkyd resin, phenol-modified alkyd resin, styrenated alkyd resin, aminoalkyd resin,
Polyester resin, polyurethane resin, acrylic polyol urethane polymer, soluble polyamide polymer, phenol resin, rosin-modified phenol resin,
Examples include rosin-modified maleic acid resins.

When a printing method is used as a method for coloring by applying an ink containing a dye intermediate or an ink containing a dye for hiding recorded image information, etc., letterpress printing or lithographic printing is used. , Intaglio printing, gravure printing, screen printing, etc. are used, and when a coating method is used, it is selected from conventionally known methods according to the coating ink, such as a blade coater, a rod coater, a knife coater, and a squeeze. Examples include coaters, air doctor coaters, gravure coaters, and spray coating.

As described above, the formed letters, numbers,
Regarding the infrared absorption of the image information such as a symbol pattern, that is, low reflectance, and the infrared reflectance of the colored surface applied to hide or deceive those image information with the naked eye, and their degree, It can be confirmed by an infrared reader or infrared photograph. For example, an infrared reader first uses a semiconductor laser that emits near infrared rays of 700 to 900 nm and an infrared light emitting diode that emits infrared rays of around 790 nm. These infrared rays are emitted as they are or in a form in which modulation is added to enhance the light receiving sensitivity.

Then, the infrared rays reflected by the colored portion of the base material, such as paper or a card, on which the image information is not recorded are received by the light receiving sensor and converted into an electric signal indicating the reflection. The irradiated infrared ray is absorbed in the recorded portion, and the infrared ray receiving sensor receives little or very little light, and shows no reflection or is converted into a low electric signal. These electric signals are connected to various recognition methods such as a display using a cathode ray tube and recognized as clear information.

[0021]

EXAMPLES Next, the present invention will be described in detail with reference to examples. In the text, parts or% are based on weight unless otherwise specified. Example 1 1 part of oxine encapsulated with 30 parts of gelatin-gum arabic-stearic acid (weight ratio 1: 1: 4) and 1 part of powder and 1 part of ferric stearate, 1.6 parts of ethyl cellulose. A heat-sensitive color-forming ink using a binder and acetone as a solvent was coated on a sheet of synthetic paper to a thickness of about 3 μm to form a pale yellow sheet. When it is heated to develop color, it changes to black. Before and after color development of this sheet, the reflectance in the visible part-near-infrared part was measured with a Hitachi Model 330 self-recording spectrophotometer in order to see the properties with respect to visible light and infrared light. The reflectance at each wavelength is shown in Table 1 below.

[0022]

[Table 1]

In the above table, wavelengths are given in nm and R
-1 is a sheet before color development, and A-1 is a sheet that has been color-formed by heating. The reflectance was measured by applying an alumina white plate from the back. The above results show high reflectance in the visible part and near-infrared part before coloring by heating, but those which are colored by heating show almost no reflection in the visible part and are absorbed, showing black. It also shows a large absorption in the near infrared region in the range of about 800 to 1,000 nm.

Separately, 3- (4'-aminophenylimino)
It was obtained by diazotizing -1-oxo-4,5,6,7-tetrachloroisoindoline and coupling it with 2-hydroxy-α-benzocarbazole-3-carbo- (4'-methoxy) anilide. A black ink R-2 containing 1 part of a black pigment, 3 parts of ethyl cellulose as a binder, and acetone as a solvent was prepared. This was coated on paper to a thickness of about 3 microns. The reflectance of the visible part and the near infrared part of this black coated paper was measured in the same manner with the spectrophotometer. The reflectance at each wavelength is shown in Table 1 below.
It was the street.

[0025]

[Table 2]

In Table 2 above, wavelengths are given in nm and R
-2 shows black coated paper. In the visible region, almost no reflection is shown, and since it absorbs, it naturally shows black, but in the near infrared region, it shows very high reflection.
The above black ink was applied on the above-mentioned sheet coated with the thermosensitive color-forming ink so as to have a thickness of about 3 μm and applied to obtain a black sheet. This sheet was heat-printed with a thermal recording device. However, this print could not be read with the naked eye because the sheet was applied in black. Therefore, the reflectance of the visible part and the near-infrared part of the non-colored part of the black sheet and the printed part of the black sheet were measured by the spectrophotometer in the same manner. The reflectance at each wavelength is shown in Table 3 below.

[0027]

[Table 3]

In Table 3 above, wavelengths are given in nm,
R-3 is a portion of the black sheet which is not colored by heating,
A-3 is a portion of the black sheet which has been colored by heating. The above results show that the black sheet shows a black color as it absorbs almost no reflection in the ultraviolet and visible regions, but shows a very high reflection in the near infrared region. On the other hand, the heat-colored portion absorbs almost no reflection in the ultraviolet and visible regions and absorbs black, but also shows a large absorption in the near infrared region of 800 to 1,000 nm. There is.

From the above, the heat-sensitive recording sheet coated with the black ink R-2 shows black when viewed with the naked eye, and it is indistinguishable from both the non-heat-developed part and the heat-developed part. The portion which is not colored by heating with respect to the irradiation of infrared rays shows a high reflection, whereas the portion which is colored by heating has a coloring portion A-1 at about 800 to 1,000 nm.
The absorption caused by the phenomenon occurs and the reflection is remarkably lowered, which is extremely large in the both properties. Based on the above findings, a thermosensitive coloring ink was applied to a sheet made of synthetic paper, and then black ink R-2 was applied on the sheet.
It was cut into a card shape having a length of 5 mm and a length of 54 mm.

Image information such as characters, numbers, symbols and patterns was recorded on this card with a thermal printer. However, since the entire appearance of this recording body was black, the recorded information was invisible to the naked eye, but an infrared reader could read the information clearly. The above infrared reader uses an infrared light emitting diode (for example, TLN105 manufactured by Tokyo Shibaura Electric Co., Ltd.) to generate infrared rays, which is modulated to increase the luminous intensity, and the infrared light reflected by the recording medium is received by a light receiving sensor (for example, Tokyo Shibaura Electric Co., Ltd. The TPS703) manufactured by the Company receives light, converts the presence or absence of reflection and the degree of reflection into an electric signal so that information can be recognized.

[0031]

[Effect] According to the recording method of the present invention as described above, since the recorded information formed is colored in the same or a darker hue so as to be concealed or deceived with the naked eye, it can be distinguished with the naked eye. However, it can be identified only by infrared rays. Therefore, it is very useful as a method of recording image information that requires high confidentiality.

Claims (1)

[Claims] 1. A method for recording image information in which a colored region made of an infrared absorbing dye and a colored region made of an infrared reflecting dye are formed in parallel or in an overlapping manner on an arbitrary substrate, and the recording method is a thermosensitive coloring system. A recording method, wherein at least one of the colored areas is an image of characters, numbers, symbols, patterns, etc., and the two types of colored areas are substantially indistinguishable or difficult to discriminate with the naked eye.