JP2002178675A - Concealing seal and scratch medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of 'shaving refuse' at the time of scratching. SOLUTION: A concealing layer main body, which can not be viewed in an ordinary and general state but contains a light reflecting substance transparentizing a layer irreversibly when a transparentizing means is added from the upper surface of a transparent film and a light absorbing substance having a light absorbing function, is formed on the undersurface of the transparent film to constitute a concealing seal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to concealing seals and scratch media.

[0002]

2. Description of the Related Art Conventionally, a scratch card is used as a simple lottery card such as a lottery card, a speed lottery card for a merchandise lottery in a shopping district, a simple lottery for a prize such as a magazine, and the like.

In recent years, secret information such as a registration number is recorded on a card, such as a prepaid card such as an international telephone or a prepaid mobile phone, and a purchaser inputs the registration number of the prepaid card into a host computer. After that, a system is available in which calls can be made according to the balance of the prepaid card. In this prepaid card, a secret information (registration number) portion is concealed, so that a card buyer scratches and uses the card.

As these scratch cards, "silver paste printing" is mainly used. They are,
A fragile silver-colored concealing layer is formed on the secret information such as a hit or a loss printed on the base material, and the lower secret information is discarded by rubbing with a coin or the like.

[0005] However, these scratch cards use a coin or the like to scrape off the concealing layer.
Occurs. In applications where many cards are scratched at once such as a lottery ticket, or where applications such as a lottery in a shopping street are scratched outdoors, there are environmentally unfavorable problems such as a large amount of shavings being scattered.

In addition, since the concealment layer of the scratched card can be reproduced by a method such as reprinting, the used card can be made to look like an unused card, which is a security problem. There is.

As scratch cards free of dust, there are JP-A-2000-52676 and JP-A-7-32729. The former contains a very hard inorganic pigment on the base material, prints confidential information such as characters and pictures using the same color or colorless ink as the base material, and scrapes the character part with metal such as coins In this method, confidential information can be read by rubbing a metal part on a character portion.

[0008] On the other hand, in the latter case, the same color or transparent developer character as that of the base material is printed on the base material, the leuco dye-containing microcapsule ink is overprinted thereon, and the microcapsules are rubbed with a coin or the like. Is a method in which the developer is crushed to cause a developer and a leuco dye to react, thereby making it possible to read secret information.

However, these methods tend to cause subtle differences in color and glossiness between the character portion and the base material portion, and may cause confidential information to be read before scratching. There was a problem that was difficult. Also, it was not possible to simply obtain the scratch medium by attaching the concealing seal itself to the upper surface of one side of the base material.

[0010]

SUMMARY OF THE INVENTION The concealment seal and the scratch medium of the present invention, in view of the above-mentioned problems, have a first object of preventing generation of "scraping residue" at the time of scratching. Second, before scratching, the concealment is high,
It is another object of the present invention that the original state cannot be returned after scratching (the falsification is not easy). A third object is to easily obtain a scratch medium simply by attaching the concealing seal itself to the upper surface of one side of the base material. Fourth, it is an object of the present invention to provide an inexpensive scratch medium in which the concealment layer main body is made transparent by applying a physical stimulus from the outside and secret information such as concealed characters appears.

[0011]

The concealing seal of the present invention comprises:
On the lower surface of one side of the transparent film, it is not normally visible in a normal state, but a light reflecting material that irreversibly makes the layer transparent when a transparentizing means is added from the upper surface of one side and light having a function of absorbing light. A concealing layer main body containing an absorbing substance is formed.

In the concealing seal of the present invention, the transparent film cannot be seen on one side lower surface of the transparent film in a normal state, but when viewed from one side upper surface, the layer is irreversibly made transparent by adding a transparentizing means. Forming a concealing layer body including a light reflecting substance and a light absorbing substance having a function of absorbing light,
Furthermore, an attachment layer is formed on the lower surface of the concealing layer main body.

Further, the concealing seal of the present invention is such that a light can be irreversibly clarified by adding a clarifying means from one upper surface to the lower surface on one side of the transparent film, which cannot be visually observed in a normal state. A concealing layer main body including a reflective material, a light absorbing material having a function of absorbing light, and an organic polymer binder is formed.

In the concealing seal of the present invention, a transparent film is not normally visible on the lower surface of one side of the transparent film, but is irreversible when the transparent means is added from the upper surface of the transparent film. A concealing seal formed with a concealing layer main body having a layer containing a reflective substance and a light absorbing substance having a function of absorbing light, and at least one of an anchor layer and a primer layer.

Further, the scratch medium of the present invention is a scratch medium comprising a base material provided with characters and the like on one side upper surface and a concealing seal provided integrally with the base material so as to conceal the characters and the like. The concealing seal is formed on a transparent film and a lower surface of one side of the transparent film,
In addition, although it cannot be viewed in a normal state, the concealment includes a light reflecting material that irreversibly makes the layer transparent when a transparentizing means is added from one side upper surface, and a light absorbing material having a function of absorbing light. It is characterized by comprising a layer main body and an attachment layer formed on the lower surface of the concealing layer main body.

The above concealing seal and scratch medium are as follows:
The common subject of the invention is that no "scraping residue" is generated at the time of scratching, and the concealment property before scratch is high, but it is not possible to return to the original state after scratching (falsification is difficult).

The term "concealing seal" as used herein means a cover member for concealing characters and the like on a base material. Therefore, the shape such as length and width is not particularly limited. The “substrate” is not limited to a planar shape or a three-dimensional shape. Also "characters"
Means characters, numerals, symbols, colors, patterns, and pictures provided by printing means as described above. Further, "transparency means" means that one side of the concealing seal is externally pressurized,
Gives physical stimulus such as heating. In this case, pressurizing means (for example, rubbing with coins, rubbing with nails, etc.) and heating means (for example, thermal head, heating plate, flame of lighter, etc.)
Does not matter. The term “attachment layer” refers to an adhesive layer or an adhesive layer. Further, the “scratch medium” refers to a tangible object having a concealing layer main body regardless of a planar shape or a three-dimensional shape.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment (concealing seal 1) of the present invention will be described below in detail with reference to FIGS. First, the members (including layers) constituting the concealing seal 1 will be briefly described with reference to FIG. 2 is a transparent film, 3 is a concealing layer main body, 4 is a mounting layer, and 5 is a release paper.

Next, the main part of the present invention will be briefly described with reference to FIGS. 6 is a light reflecting substance provided in the concealing layer main body 3; 7 is a light absorbing substance also provided in the concealing layer main body 3 and having a function of absorbing light entering the concealing layer main body 3 from outside; Reference numeral 8 denotes air which is provided in the concealing layer main body 3 and serves to make the concealing layer main body 3 transparent together with the light reflecting substance 6, and 9 and 9a denote light incident on the concealing layer main body 3 from the outside. Next, members constituting the concealing seal 1 will be described in order.

“Code 2—Transparent Film” (1) Function of Transparent Film—The transparent film 2 functions as a support for the concealing seal 1. Further, when the concealing seal 1 is handled as a main part of a scratch medium described later, a pressure (pressure) for discriminating characters 11 provided by printing or the like on one side of the base material 10 of the scratch medium is used. It also has a role as a protective layer for protecting the concealing layer main body 3 which is slightly vulnerable to rubbing, heating and the like.

(2) Transparency of Transparent Film The concealing seal 1 irreversibly makes the concealing layer main body 3 transparent in the present embodiment, so that the transparent film is required to be transparent in principle. As such a transparent film, an acrylic film, a PET film, a PEN film, a polyimide film, a polyamide film, a polyethylene film, a polypropylene film, a polycarbonate film, or the like can be used.

(3) Thickness of the transparent film: The thickness of the transparent film is preferably, for example, 5 to 100 μm, more preferably 1 to 100 μm, in the case of using a PET film.
0-50 μm is more preferred. For example, film thickness 5μm
If it is less than 100 mm, it will be destroyed constantly by the external pressure when pressurizing (for example, rubbing) using a metal such as a coin.
If it is more than μm, the transmission of the pressing force becomes poor, and it becomes difficult to make it transparent.

(4) Material selection: In this embodiment, polyethylene terephthalate is used as an example. The transparent film 2 has such a thickness as to have a function as a support so as not to be destroyed by pressurization from above, and may be any thickness that can easily reach the concealing layer main body.

"Reference numeral 3 ... concealing layer main body" (1) Position of concealing layer main body ... concealing layer main body is transparent film 2
And the attachment layer 4 are present in a sandwich shape. In this embodiment, a transparent film 2 having an appropriate shape (for example, a rectangle) is used.
Are formed integrally on the lower surface on one side.

(2) Main components of the concealing layer main body: Although the concealing layer main body cannot be normally viewed in a general state, it is internally deformed when a transparentizing means is added from one side upper surface, and the internal air is deformed. And a light-absorbing substance 7 having a function of absorbing light.

(3) Transmittance of concealing layer: Here, the portion from the transparent film 2 constituting the concealing seal 1 to the mounting layer 4 is referred to as a “concealing layer”. Thus, the concealing layer (2,
As for the transmittances of (3) and (4), the transmittance for any light having a wavelength of 380 to 750 nm is 0.01% to 10%, and the transmittance after pressurization is 20 to 95%. The concealing layer of the concealing seal 1 of the present embodiment is normally set so as to shield the light having the above-mentioned wavelength to a light transmittance of 10% or less in a general state. When affixed to base material 10 having characters 11 on the side upper surface,
It is no longer possible to visually recognize the characters 11 on the adhered member from the outside. Therefore, the concealment seal 1 has a function of blocking light so that confidential information such as characters to be concealed cannot be read or determined.

"Reference numeral 4 ... Mounting layer" (1) As the mounting layer 4, an adhesive layer or an adhesive layer is used. In this embodiment, an adhesive (layer) is employed as an example of the attachment layer. The attachment layer 4 is a formation layer for attaching the concealing seal 1 to a base material 10 having characters 11 as shown in FIG.

(2) There are various kinds of adhesives,
Since the concealing seal 1 itself becomes transparent by heating, a room temperature adhesive is generally used. Of course, if it is sticky when pasting, it is enough, then natural curing, moisture curing, heat curing to the extent that it does not become transparent,
There may be electron beam curing or ultraviolet curing.

(3) There are various methods for forming the attachment layer 4. For example, there are acrylic resin-based, polyester resin-based, vinyl acetate-based, ethylene vinyl acetate-based, and urethane resin-based adhesives. It may be used in combination with a curing agent such as an epoxy, epoxy, silane or metal alkoxide.

(4) In the case of the preceding paragraph, the thickness of the pressure-sensitive adhesive layer varies depending on the molecular structure of the pressure-sensitive adhesive and the required pressure-sensitive adhesive strength, but is generally formed in the range of several to several hundreds of μm. In the attachment layer 4 of the present invention, the adhesive layer is formed in consideration of the material, thickness, and the like.

(5) The attachment layer is not a specific requirement of the present invention. This is because, for example, the user may apply or coat an adhesive on the lower surface of the concealing layer of the present invention before use.

"Reference numeral 5 ... release paper or release member" The release paper 5 is not a specific requirement of the present invention. For example, concealment seal 1
Is not always necessary when the toilet paper type or the wound roll type is used. However, concealment seal 1
Is a tape having a required length as shown in FIG. 1, a release paper 5 is desirably provided on the lower surface of the mounting layer 4.

Reference numeral 6: Light-reflecting substance (1) Function of light-reflecting substance (a) The light-reflecting substance reflects light at the interface with the air inside the concealing layer main body, lowers the light transmittance, and reduces the light transmittance. (B) When the concealing seal is provided with a transparentizing means such as pressurization and heating from the outside, the air inside the concealing layer main body is unevenly distributed or reduced. After the shrinkage (including shrinkage here), it has a transparency function of irreversibly reducing the light reflection of the concealment layer main body to make the layer transparent.

(2) Characteristics of Polymer Particles: The polymer particles have a light reflection mechanism by an interface with the air 8. The size of the polymer particles is limited by the relationship between the wavelength of light and the layer thickness. The preferred range of the embodiment of the present invention is 0.05 to
2.0 μm. In order to effectively exhibit light reflection at the interface with air, a large refractive index is desirable.
In this embodiment, a refractive index of 1.4 to 1.7 (no unit) is preferable. Further, since the polymer particles are organic polymer materials, a certain thermal stability is required so that the concealing layer does not become transparent due to spontaneous fusion while the concealing seal 1 is left naturally. Therefore, it can be said that the preferred thermal stability of the examples of the present invention is a glass transition temperature of 20 ° C. or higher, but this numerical value is not a limiting requirement of the present invention.

(3) Conditions for Polymer Particles The polymer particles have at least the following characteristics in view of the above-mentioned characteristics (scattering of light 9 at the interface with air 8). a) The average particle size is 0.05 to 2.0 μm, preferably 0.2 to 0.8 μm. b) Refractive index / 1.4 to 1.7 (no unit) c) Does not fuse completely at an ambient temperature of 20 ° C. or less (4) Specific description of conditions: Polymer particle diameter is visible light (380 to 750 nm) Is preferably a particle diameter (0.05 to 2 μm) for efficiently reflecting λ, and for more efficient reflection, an integer multiple of λλ (0.2 to 1.6 μm) with respect to the wavelength λ of visible and visible light is preferable. Further, it is necessary that the polymer particles 6 do not change in transparency at natural environmental temperatures (concealing properties and reliability). For example, in an environment of 20 ° C. or less, since fusion does not occur completely, it is desirable to maintain an interface with air 8. Specifically, it is desirable that the polymer particle material is not in a molten state under a temperature condition of 20 ° C. or less, and more specifically, in a glass state (glass transition temperature is 20 ° C. or more) at a temperature condition of 20 ° C. or less. Alternatively, even in the rubber state, the softening temperature is 20 ° C. or higher. in addition,
In order to reflect the light 9 efficiently, the refractive index of the polymer particles 6 needs to be 1.3 to 1.7, and the applied refractive index is 1.
4 to 1.7 (no unit). Note that the reflection of the light 9 increases as the refractive index increases.

(5) Polymer particles satisfying the conditions: The polymer particles satisfying the above conditions include acrylic resin (acrylate resin, acrylic styrene resin, acrylic urethane resin, etc.), polyester resin, urethane resin,
Polymer beads made of styrene resin, olefin resin (polyethylene, polypropylene, etc.), vinyl resin (vinyl chloride resin, polyvinyl alcohol, vinyl acetate resin, amide resin, amine resin, etc.), hollow particles or water-dispersed emulsion materials is there.

(6) In this embodiment, the resin type is
It may be a copolymer resin or a modified resin.

(7) Optimum form of polymer particles: A particularly preferable form of the polymer particles is a water-dispersed emulsion. Examples of the material include an acrylic emulsion having a large refractive index and a high Tg, an acryl-styrene emulsion, a styrene emulsion, and the like, and more preferably a core-shell structure. By the way, "core-shell structure"
The term “polymer particles” refers to a structure in which polymer particles have a multilayer structure of two or more layers, and an organic material (shell) having physical properties different from the core is formed around core particles (core).

(8) Core-shell structure emulsion: As a core-shell structure emulsion, it is preferable that the Tg of the core is higher than the Tg of the shell, and the difference in the refractive index between the core and the shell is 0.05 or more. When such a core-shell structured emulsion is used, a continuous film can be easily obtained in the process of forming the concealing layer main body 3 while keeping the spherical shape without substantially deforming the polymer particles. This is because the shell surrounding the core is melted by heat and partially adhered between the shells to form a continuous film, and the core has a higher Tg than the shell, so that the core can maintain a spherical shape. That's why. If the refractive index difference between the core portion and the shell portion is large, interface reflection (reflection of light) occurs between the core portion and the shell portion, and the reflection efficiency at the time of concealment is improved.

(9) Water-dispersed emulsion: When the polymer particles are water-dispersed emulsions, the polymer particles (emulsion particles) do not melt at a drying temperature of MFT (minimum film-forming temperature) or lower, so that the spherical shape is maintained. Under the drying temperature before and after the MFT, the polymer particles (emulsion particles) start to melt and partially adhere at the interface between the particles. Further, at a drying temperature equal to or higher than the MFT, the melting of the polymer particles progresses and the spherical shape is broken, and finally, the polymer particles are completely melted and no longer spherical. For this reason, by drying the polymer particles at a temperature around MFT, a coating film (continuous film) can be obtained with substantially no deformation and a spherical shape, and air 8 can be easily contained in the coating film. It is possible to make it. Thus, in this embodiment, the concealing layer main body 3 can be easily formed. Desirably, if the emulsion particles have a core-shell structure as described above, the concealing layer main body 3 can be further easily formed.

(10) Light-reflective substance of this embodiment: As the polymer particles as the light-reflective substance 6 of this embodiment, a polymer emulsion produced by an emulsion polymerization method or the like is employed.

"Sign 7: Light absorbing substance" (1) Light absorbing substance: The light absorbing substance 7 is mixed with the polymer particles 6 in the concealing layer main body 3. The light absorbing substance 7 is a dye material that absorbs light in a state that can be distinguished from the color tone of 11 such as characters on a substrate to be concealed.

(2) Dye material: The light-absorbing substance 7 is a dye or a pigment having a light-absorbing function (referred to herein as a "dye material"). The pigment material 7 is necessary to completely cover the characters 11 such as characters on the base material 10. Therefore, in this embodiment, the pigment material 7 is mixed in the concealing layer main body 3 together with the light reflecting substance 6.

(3) Optimal example of dye material: The light absorbing substance is
Depending on the correlation between the color tone (black, dark green, dark red, etc.) of the characters 11 such as characters on the base material 11 and the volume of the concealment layer main body 3, carbon particles are an optimal example.

(4) Weight fraction of light-reflecting substance and light-absorbing substance: The weight fraction in the concealing layer main body 3 when carbon particles are used as the coloring material 7 will be described.
The shielding of the light 9 and 9a of the concealing layer main body 3 in the present invention is based on both the light reflection function (mechanism) and the light absorption function (mechanism). However, the light absorbing function does not contribute to the transparency of the concealing layer main body 3 by pressurization (including “heating” as described above). Function is impaired. Therefore, for example, the polymer particles 6 and the carbon particles 7 in the concealing layer main body 3
Is limited, and the polymer particles 10
The range of 0.1 to 10 parts by weight of carbon particles is preferably based on 0 parts by weight.

"Code 8 ... air" (1) Air ... The concealing seal 1 also contains air 8 in the concealing layer main body 3.
With the light reflecting substance 6. The air 8 has a function of contributing to the transparency of the concealing layer main body 3 together with the light reflecting substance 6. That is, the air 8 contained in the concealing layer body 3
Is a specific requirement of the present invention because it has a light reflecting function at the interface with the polymer particles 6 having different refractive indexes.

(2) Amount of air: Regarding the amount of air 8 contained in the concealing layer main body 3, if the amount is small, the reflectivity decreases and the concealing layer main body 3 becomes transparent. Conversely, if the amount is too large, the transmittance of the concealing layer main body 3 increases, and at the same time, the strength of the layer itself deteriorates. In the concealing seal 1 of this embodiment, the volume ratio of the concealing layer main body 3 needs to be in the range of 5 to 50%, and particularly preferably in the range of 10 to 25%.

(3) Amount of air according to the embodiment: Before and after the above-mentioned MFT or at a drying temperature lower than the MFT, the packing condition of the polymer particles can be easily adjusted by simply adjusting the drying conditions (solid content concentration of the emulsion, dry air volume). It is possible to adjust the state from a dense state (a hexagonal close approximate state) to a coarse state (a random state), and it is possible to fill the gap between the polymer particles by adjusting the amount of binder added.
Can be changed.

[Operation / Effect] First, a method of forming the concealing layer main body 3 of the present invention will be described. Offset printing, screen printing, gravure printing, or roll coating, spin coating, spray coating, die coating, gravure coating, micro gravure coating on the upper surface of one side of the transparent film 2 with the ink or paint for the concealing layer adjusted at an arbitrary ratio. , A flow coat, a nozzle coat, a knife coat and the like.

Next, the operation and effect of the present invention having the concealing layer main body 3 will be described. FIG. 3 conceptually or schematically shows the light situation of the concealing seal 1 before pressurization. In this case, the light passes through the transparent film 2 and reaches the interface between the polymer particles 6 of the concealing layer main body 3 and the air 8. Then, part 9 of the light is reflected (scattered) due to the difference in the refractive index. Also its afterglow 9
When “a” hits the light absorbing substance 7, it is absorbed by the light absorbing substance 7 as it is.

Therefore, if the concealing seal 1 is affixed to the upper surface of the base material 10 shown in FIG. 2, the light reaching the base material 10 becomes small. Therefore, the base material 1
Characters 11 provided on the upper surface of 0 are concealed as secret information.

On the other hand, FIG. 4 conceptually or schematically shows the state of light on the concealing seal 1 after pressurization. Now, a required pressure or heat is applied from the upper surface of the transparent film 2 of the concealing seal 1 by pressing (rubbing, heating, etc.). Then, the air 8 in the concealing layer main body 3 is discharged out of the concealing layer main body 3 depending on the pressurization (rubbing, heating, or the like), or is reduced (including shrinkage) or unevenly distributed, and is condensed with the polymer particles 6. Of the air interface is reduced. The light 9 is no longer reflected by the polymer particles 6 but passes through the concealing layer body 3 and
Reaches the top of However, the light 9a that hits the light absorbing material 6
Is absorbed by the light absorbing substance 6 and does not reach the upper surface of the substrate 40.

As a result, the hue due to the absorbing material slightly remains, but the transmittance of the concealing layer main body 3 is improved, and the characters 11 provided on the substrate 10 can be visually recognized. Then, "scraping waste" is not generated at the time of scratching.

[0054]

[Experimental results of the first embodiment] The experimental results of the first embodiment of the present invention have revealed the following. (A) As the light transmittance of the concealing layer main body 3, any one of light having a wavelength in the range of 380 to 750 nm
It has been found that 0% or less, for example, 0.01 to 10% is sufficient, and conversely, for visual recognition, a transmittance of 15% or more, preferably 20 to 95%, is sufficient. (B) In the preceding paragraph, the light having a light wavelength in the range of 380 to 750 nm is such that, for example, characters 11 as confidential information are not made of black ink but made of ink in a special light absorption region. In this case, there is no need to collect the entire wavelength range,
This is because it is sufficient that at least light having a wavelength within a range sufficient to visually recognize the concealed information is shielded. (C) The concealing layer main body 3 has a volume of 5 to 50 with respect to the entire volume thereof.
%, Preferably 10 to 25% air 23. When the air 8 in the concealing layer main body 2 is less than 5%,
The interface between the air 8 and the polymer particles 6 was reduced, and sufficient hiding properties and / or transparency change after scratching could not be obtained. (D) Further, if the content of air 8 is less than 5%, the reflection of light at the interface with the polymer particles 6 is reduced, and the transparency is increased. It was also found that it was necessary to increase the thickness of the concealing layer main body 3 or increase the thickness of the concealing layer main body 3. (E) However, an increase in the amount of the dye material 7 causes a decrease in transparency after scratching, and the character visibility becomes very poor. As the thickness of the concealing layer body 3 increases, the scratch sensitivity decreases (increase in applied pressure). Is not practical because it leads to
It has also been found that 0 μm or less, for example, 5 to 100 μm is preferable. (F) On the other hand, it was also found that when the air 8 in the concealing layer main body 3 was 50% or more, the coating film cohesion was extremely poor, and the practicability was poor. (G) To further elaborate on the matters found from the experimental results, the dye material 7 used in the concealing layer main body 3 absorbs at least any light having a wavelength of 380 nm to 750 nm, and the secret 11 of characters such as characters on the base material 10. Same color as the information display,
Alternatively, it was also found that it was necessary to contain one or more light absorbing materials of similar color or black. That is, by containing one or more kinds of light-absorbing dye materials 7 having the absorption wavelength of light such as letters, numbers and pictures of the secret information display portion and the same wavelength or an absorption wavelength range including the same. The light of the wavelength to be concealed reaches the information display unit. Therefore, the black pigment material 7 is most desirable as the light absorbing pigment material 7 used in the embodiment of the present invention because it absorbs light of all wavelengths in the visible light wavelength region. (H) From the experimental results, it was found to some extent that the pigment material 7 can be used regardless of an inorganic material or an organic material as long as it is not a colorless and transparent material. When carbon particles typified by carbon black are used as the pigment material 7, light in the widest wavelength range can be absorbed (this means that the concealment range is wide regardless of the characteristics of the concealment information). are doing). (I) To further explain, according to the experimental results, when the light-absorbing substance is carbon particles, it is preferable that the light-absorbing substance be contained in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the polymer particles as the light reflecting substance. understood. If the content of the carbon particles is less than 0.1 part by weight, sufficient light absorption cannot be obtained, so that the concealing property decreases. If the content is more than 10 parts by weight, the transparency after scratching and the background The contrast difference decreased and reading became difficult. (J) No "scraping residue" is generated at the time of scratching.

Next, the concealing seal 1A of the present invention (referred to as "second embodiment") will be described in detail with reference to FIGS. In the description of the second embodiment and thereafter, the first embodiment will be described.
The same components as those of the embodiment are denoted by the same or similar reference numerals for convenience, and the duplicate description will be omitted.

The main difference between the second embodiment and the first embodiment is that the concealing layer body 3A contains an organic polymer binder 15 as a binding element. In this case, the organic polymer binder 15 is a water-soluble resin or a water-dispersed emulsion.

Thus, the MFT (minimum film formation temperature) of the water-dispersed emulsion as the organic polymer binder is lower than the MFT of the polymer particles as the light reflecting material, and
It has a temperature difference of 5 ° C. or more. Here, “5 ° C or higher”
The upper limit is, for example, 20 ° C., 2
The temperature may be 2 ° C., 24 ° C., or the like, and means a value within the range of common sense for those skilled in the art. As the water-soluble resin as the organic polymer binder, polyvinyl alcohol can be given as an example.

Therefore, the addition of the organic polymer binder will be described in detail. The components of the concealing layer main body 3A, the polymer particles 6, the air 8 and the coloring material 7 do not have a binding function by themselves depending on the embodiment, and even if these three are simply mixed, a layer as a coating film is formed. No formation can take place. However, in practice, the concealing layer main body 3A is formed while applying a constant temperature, so that the surface layers of the adjacent polymer particles 6 are slightly fused to each other, and the form as the coating layer is maintained. However, since the polymer particles 6 essentially function as an element as a light reflecting material, a small amount of an organic polymer binder may be separately added in order to secure a necessary coating film (hiding layer) strength.

The material type of the organic polymer binder will now be described. Since the water-dispersible emulsion is used for the polymer layer forming the concealing layer main body 3A, a water-soluble polymer resin or a water-dispersible emulsion resin is used so as to serve as a binder when the water is heated and evaporated. .

However, regarding the characteristics of the water-dispersed emulsion resin, even with the same emulsion particles, the properties of the polymer particles functioning as a light reflecting material and the properties of the emulsion particles functioning as a binder of a coating film are different. As a binder, the particles must be immediately bonded to each other as a binder at the time of film formation. As a result, the MFT (film formation temperature) of each polymer particle needs to be different, and at least the MFT of the emulsion particles is smaller than that of the polymer particles. , And it is necessary to have a temperature difference of 5 ° C. or more. Further, among the water-soluble polymer resins described above, polyvinyl alcohol resins are most common.

In the concealing seal 1A of the second embodiment, the organic polymer binder 15 is a specific requirement of the invention depending on the embodiment. Therefore, the same operation and effect as those of the first embodiment are obtained. is there.

Next, the concealing seal 1B of the present invention (this is referred to as a "third embodiment") will be described in detail with reference to FIGS.

The third embodiment is different from the first embodiment mainly in that an anchor layer 20, a primer layer 21, and a lubricating layer 22 are provided on the concealing layer main body 3B. In addition, from the standpoint of adding another object to the main object of the present invention, any one or two of the first and second requirements are set to the first object.
The configuration requirements of the embodiment may be limited to the main part.

Therefore, additional specific requirements will be described. The basic configuration of the concealing seal (1, 1A, 1B) of the present invention is not limited as long as at least the concealing layer main body 3B and the mounting layer 4B are sequentially formed on one side surface of the transparent film 2B.

Accordingly, for example, the anchor layer 20 for improving the adhesiveness is formed between the transparent film 2B and the concealing layer main body 3B, or the concealing layer main body 3B and the attaching layer 4 are formed.
B, a primer layer 22 is formed to prevent the attachment layer 4B from penetrating into the concealing layer main body 3B, and a lubricating layer 22 is further formed on the upper surface of the transparent film 2B to reduce friction due to scratches. Accordingly, the transparent film 2B can be provided with a function of preventing scratches or the like. In the description, “do not impregnate” means that a barrier (impregnation prevention) effect is obtained so that the concealing layer main body 3B does not become transparent.

In the above configuration, the concealing seal 1B is also the first
Since the main part of the concealing seal 1 described in the embodiment is included as it is, the same operation and effect as in the first embodiment are obtained.

Next, referring to FIGS. 11 to 13, a scratch medium X (hereinafter referred to as a "fourth cover medium") mainly including the concealing seal 1 of the present invention (the concealing seal may be 1A or 1B).
Example ". ) Will be described in detail. Note that this fourth
Although the embodiment is an invention including the invention of the product (concealing seal) and the main part of the invention of the product as it is in relation to the first embodiment, the following embodiment is not excluded.

For example, a concealing layer is directly formed on the secret information formed on the medium in advance by printing or the like, and a scratch protective layer is printed thereon or a transparent film is laminated thereon. This is the case of the working example.
That is, the forming step of the concealing layer main body and the attaching step of the concealing layer main body are not particularly limited. Therefore, depending on the scratch medium, the concealing layer main body may not have the meaning of an ordinary seal (elongated planar shape).

Accordingly, an example of the scratch medium X according to the fourth embodiment will be described from the above-mentioned point. Scratch medium X
Is composed of a base material 10 provided with characters and the like on one side upper surface, and a concealing seal 1 provided integrally with the base material so as to cover the characters 11 and the like.

Then, as described above, the concealing seal 1
Is formed on the lower surface of one side of the transparent film 2 and is not visible in a normal state, but when a transparentizing means is added from the upper surface of one side, it is internally deformed to generate internal air. A concealing layer main body 3 including a light reflecting substance 6 for unevenly dispersing or reducing the size 8 and making the layer irreversibly transparent and a light absorbing substance 7 having a function of absorbing light, and formed on the lower surface of the concealing layer main body. Mounting layer 4 provided.

Therefore, the scratch medium X having the above structure
Then, for example, an example in which a dry laminating material or the like is directly used instead of the adhesive as the attachment layer 4 to directly adhere, or a concealment layer main body of a different color other than black is laminated, and concealment equivalent to a black concealment layer is performed. Examples in which the concealing property is obtained, and examples in which the light absorbing layer (dye material layer) is formed separately from the concealing layer main body to supplement the concealing property, can be said to be obvious (equivalent matters).

By the way, in the fourth embodiment, the base material 10
Is not particularly limited. Regardless of the shape and material, the concealing seal 1 can be used to attach characters 11
Secret information can be concealed.

As a general base material, a plastic material such as paper, synthetic paper, PET or the like is often used, and secret information such as characters 11 is formed on the base material by printing, an ink jet printer, or the like. Often. Further, when forming secret information such as characters 11 on the scratch base 10, an ink absorbing layer for improving the fixability of the secret information forming ink, improving the adhesiveness, and obtaining a sealing effect for paper and the like. A primer layer or the like is provided on the anchor layer and the secret information for the purpose of improving the smoothness, abrasion, and releasability (or adhesion) of the substrate 10. In addition to these processes, tint block, colored layer,
A metal deposition layer or the like may be provided.

Therefore, also in the fourth embodiment, it is possible to use a substrate on which the secret information, the ink absorbing layer, the anchor layer, the primer layer, the tint block, the colored layer and the like are formed.

By the way, as can be said in common to the respective embodiments of the present invention, for example, the protective layer 2 formed on the concealing layer main body 3 of the present invention may be formed of the characters 11 of the base material 10 after scratching. There is no particular limitation as long as the material has transparency so that the secret information portion can be visually recognized. However, a material having good scratch resistance and heat resistance that does not destroy the protective layer due to pressure by a scratch is desirable. These materials include UV (ultraviolet) / EB (electron beam) curable or heat curable, natural curable and moisture curable organic high molecular materials and organic low molecular materials having a high crosslinking density. Further, if necessary, an inorganic or organic lubricant is added, and used in the form of a printing ink, a coating type ink or the like.

Although these materials can be used in the present invention, a preferable form (a scratch medium free from dust) is realized by using an organic polymer transparent film.

However, the organic polymer transparent film of the present invention is superior in abrasion and denseness as compared with printing inks and coating type inks, and has a remarkable effect that shavings hardly appear when scratching with a coin 16 or the like. There is. Hereinafter, an actual example will be described.

[0078]

[Construction of concealing film and composition of concealing layer: Here, "Example 1"] First, the transparent film 2 was made of Diafoil Hoechst Co., Ltd.
G (thickness: 25 μm), and the anchor layer 20 was used as the simple adhesive layer.

Next, the following concealing layer solution was applied onto the anchor layer 20 and then aged in a constant temperature bath at 100 ° C. for 2 minutes to form a concealing layer 3 having a thickness of 20 μm. A 3 μm aqueous solution of polyvinyl alcohol (polymerization degree: 500) having a solid content of 10% was formed thereon as a primer layer 21.
Acrylic resin adhesive BPS5896 manufactured by Toyo Ink
Were sequentially laminated to form a lubricating layer 22 on the non-easily-adhesive treated surface of the transparent PET to a thickness of 2 μm as an offset ink release OP varnish SE made by Toka to produce the concealing seals of Examples 1- (1) to (3). .

Next, the transparent film 2 was made of transparent PET (no surface treatment) and T100 (thickness 2) manufactured by Diafoil Hoechst.
5 μm), and the concealing layer solution used in Examples 1- (1) to (3) was applied thereon, followed by aging in a thermostat at 100 ° C. for 2 minutes to form a concealing layer 3 having a thickness of 20 μm. . The pressure-sensitive adhesive layer 4 is formed on the release film in advance by BPS.
5896 was formed to a thickness of 10 μm and transferred to the concealing layer to prepare concealing seals of Examples 1- (4) to (5).

The secret information base material 10 is made of Toray 188 μm
A black ink character formed by offset printing on white PET E28 was used.

The concealing seal (1, 1A, 1B) is
Paste so as to cover the upper characters 11 etc., Example 1- (7)
(12) scratch cards were prepared.

At this time, Examples 1- (1) and (4) of the experimental object were the concealing layer dispersion 1, Example 1- (2) and (5) were the concealment layer dispersion 2, and Example 1- (1). (3) and (6) show the case where the concealing layer dispersion liquid 3 is applied, and the cards on which the examples 1- (1) to (6) are respectively attached are examples 1- (7) to (12). is there. At this time, the card to which the example 1- (1) is attached is the example 1- (7), and (2) is (8), (3) is (9), (4) is (10), and so on.
(5) corresponds to (11), and (6) corresponds to (12). In addition, the transparency (scratch) uses a 10-yen coin from above the concealing seal (the lubricating layer surface or the PET surface side), and
This was performed by rubbing.

Thus, at the time of scratching, the actual example 1- (7)
The non-scratch portions of (12) could not read 11 secret information such as characters, and the scratch portions could clearly read characters. In addition, when these scratch cards were rubbed with a 10-yen coin, no generation of dust (shavings) was observed at all.

“Hidden layer solution 1” Aromatex E432 (46.5 wt% acrylic water-based emulsion) manufactured by Mitsui Chemicals, Inc. was used for polymer particles 6, and carbon black SC ULT manufactured by Columbian Carbon Co., Ltd. was used for pigment material 7.
RA (dry powder) was used. Carbon black was used by dispersing it in Joncryl 63 (30 wt% water-soluble acrylic resin) manufactured by Johnson Polymer Co., Ltd., and these were mixed in the following mixing ratio to obtain a hiding layer solution. 2. Aromatex E432 100.00 (46.5) parts by weight Carbon black dispersion 18.72 (1.44) parts by weight "Carbon black dispersion" SC ULTRA 0.32 (0.32) parts by weight John Krill 63 73 (1.12) parts by weight Ion-exchanged water 14.67 (0.00) parts by weight The content in parentheses is the weight ratio of solids. "Concealing layer solution 2" Polyvinyl alcohol (degree of polymerization 50
0) An aqueous solution was added. These were mixed in the following mixing ratio to obtain a hiding layer solution. Aromatex E432 100.00 (46.5) parts by weight Carbon black dispersion 18.72 (1.44) parts by weight Polyvinyl alcohol 12.25 (2.45) parts by weight Layer Solution 3 "Dye Material 7 in Hidden Layer Solution 1
Was replaced with the following water-soluble dye. These were mixed in the following mixing ratio to obtain a hiding layer solution. Aromatex E432 100.00 (46.5) parts by weight Dye aqueous solution 1 33.00 (0.33) parts by weight "Dye aqueous solution 1" Methylene blue 0.11 (0.11) parts by weight Rhodamine 6G 0.11 (0. 11) parts by weight Thioflavin T 0.11 (0.11) parts by weight ion-exchanged water 32.67 (0.00) parts by weight

[0086]

[Method for measuring transmittance of concealing film: Here, "Example 2"
Here, an example of a method of measuring the transmittance using the concealing seals (1, 1A, 1B) of the above-described examples 1- (1) to (3) will be described.

First, the concealing seal prepared in Example 1 was replaced with a transparent PET / T100 made by Diafoil Hoechst (thickness: 2).
5 μm) to prepare a test piece for non-scratch transmittance measurement.

Next, the test pieces were measured for spectral transmittance at each wavelength of 370 nm to 750 nm using a spectrophotometer U4000 manufactured by Hitachi, Ltd. At this time, the reference was a transparent PET / T100 (25 μm thick)
m) was used.

The transmittance after scratching was determined by heating the test piece using a thermal gradient tester HG100 manufactured by Toyo Seiki Co., Ltd., and making it completely transparent. Was measured. In this example, the heating temperature is 120 ° C. and the load is 1 kgf / cm.
^2. Transparency was performed under the processing time of 1 minute. Then, the transmittances of the non-scratch portion and the scratch portion (heating portion) of the examples 1- (1) to (3) and the examples 1- (7) to (9)
Table 1 shows the evaluation results of the concealment information read visibility when the above-mentioned card (the card on which Examples 1- (1) to (3) were pasted) was subjected to the heat treatment.

The transmittance in Table 1 is a measured value at a wavelength of 370 to 750 nm where the transmittance is naturally low. At this time, the change in hiding / transparency before and after the scratch was good.

Further, in Example 1- (3), 420 nm
Light absorption peaks of thioflavin T, rhodamine 6G, and methylene blue were observed at 30 nm (the lowest transmittance measurement peak) and around 660 nm, respectively. By mixing, the transmittance in the wavelength range of 370 nm to 700 nm became 10% or less on average, and it was possible to hide characters formed with black ink. It is as shown in Table 1 below.

[0092]

[Table 1]

[0093]

[Amount of black pigment added: Here, "Example 3"] A concealing seal and a scratch card were prepared in the same manner as in Example 1 except for the composition of the concealing layer. The hiding layer is Aromatex E432,
A carbon black dispersion was mixed at an arbitrary ratio to 100 parts by weight to form a mixture.

Accordingly, Table 2 below shows the transmittance of the concealing seal and the scratch card on which each concealing layer was formed, and the results of the scratch test. At this time, the non-scratch portion of the scratch card to which Comparative Examples 3- (1) and (2) were attached could read 11 pieces of secret information such as characters, and the concealment was insufficient.

On the other hand, Examples 3- (1) and (2)
The non-scratch portion of the scratch card to which the was attached could not read 11 secret information such as characters, and the scratch portion could clearly read characters. Also,
When these scratch cards were rubbed with a 10-yen coin, no generation of dust (shavings) was observed.

Thus, Example 3 according to the present invention
It can be said that (1) and (2) are excellent as concealment media for scratch cards without dust. On the other hand, in Comparative Example 3- (1) prepared using the polymer particles alone and Comparative Example 3- (2) having insufficient light absorption (less dye), sufficient hiding power was not obtained, and the hiding medium was not obtained. Can be said to be inappropriate. Table 2 is as follows. ○ good, × bad.

[0097]

[Table 2]

[0098]

[Hidden layer composition and secret information base material: "Example 4"
The transparent film (2, 2B) is made of Diafoil Hoechst, Inc.
G (thickness: 25 μm), and the anchor layer 20 was used as the simple adhesive layer. The following concealing layer solution was applied onto the anchor layer 20 and then aged in a constant temperature bath at 100 ° C. for 2 minutes to form a concealing layer 3 having a thickness of 20 μm. On this, a 3 μm aqueous solution of polyvinyl alcohol (polymerization degree: 500) having a solid content of 10% was used as a primer layer 21, and an acrylic resin adhesive BPS5896 manufactured by Toyo Ink was used as an adhesive layer 5.
0 μm sequentially, and as a lubricating layer 22 on the non-easy-adhesion treated surface of the transparent PET, an offset ink release OP varnish S made by Toka
E was formed to have a thickness of 2 μm to prepare the concealing seal of Example 4- (1).

The secret information base material 10 is made of Daishowa Paper
Toshiki F1 CARD (160 g / m ^TwoOffset on)
Forming characters of cyan ink (blue ink) by printing
Was used. Apply the concealing seal to the character portion on the base material 10
Paste, create the scratch card of Example 4- (2)
Was. Transparency (scratch) from the concealing seal lubrication layer side
This was performed by rubbing with a 10-yen coin.

Since the dye material used for printing the confidential information and the dye material 7 used for the concealment layer have substantially the same light absorption wavelength at this time, the non-scratch portion in Example 4- (2) is a character or the like. Eleven confidential information could not be read, and the scratch part could clearly read characters.
In addition, when these scratch cards were rubbed with a 10-yen coin, no generation of dust (shavings) was observed at all.

"Hidden layer solution 1" Aromatex E432 (46.5wt% acrylic water-based emulsion) manufactured by Mitsui Chemicals, Inc. was used for the polymer particles 6, and a mixture of methylene blue and rhodamine 6G (dye aqueous solution 2) was used for the pigment material 7. ) Was used. Methylene blue was used by dissolving it in ion-exchanged water (in a 1 wt% aqueous solution). These were mixed in the following mixing ratio to obtain a hiding layer solution. Aromatex E432 100.00 (46.5) parts by weight Dye aqueous solution 2 33.00 (0.34) parts by weight "Dye aqueous solution 2" Methylene blue 0.17 (0.17) parts by weight Rhodamine 6G 0.17 (0. 17) Parts by weight Ion-exchange water 32.66 (0.00) Parts by weight () indicates the weight ratio of solid content

[0102]

As described above, the concealing seal (1, 1A, 1B) of the present invention does not generate shavings at the time of scratching, has high concealing properties before scratching, and has a high concealing property before scratching. There is a remarkable effect such as the difficulty of falsification that cannot be returned to the state of.

[Brief description of the drawings]

1 to 4 are explanatory views showing a concealing seal according to a first embodiment of the present invention. 5 to 7 are explanatory views showing a concealing seal according to a second embodiment of the present invention. 8 to 10 are explanatory views showing a concealing seal according to a third embodiment of the present invention. FIGS. 11 to 13 are explanatory views showing a scratch medium according to a fourth embodiment of the present invention.
Each embodiment shows an example.

FIG. 1 is a schematic explanatory view showing a concealing seal of a first embodiment from a perspective.

FIG. 2 is an explanatory view conceptually showing a cross-sectional structure of a concealing seal for a base material for convenience.

FIG. 3 is an explanatory view conceptually showing the internal structure of the concealing seal before pressurization for convenience.

FIG. 4 is an explanatory view conceptually showing the internal structure of the concealing seal after pressurization for convenience.

FIG. 5 shows a cross-sectional structure of a concealing seal for a base material of a second embodiment.
Explanatory drawing which shows notionally for convenience.

FIG. 6 is an explanatory view conceptually showing the internal structure of the concealing seal for a base material before pressurization for convenience.

FIG. 7 is an explanatory view conceptually showing the internal structure of the concealing seal for a base material after pressurization for convenience.

FIG. 8 shows a sectional structure of a concealing seal for a base material of a third embodiment,
Explanatory drawing which shows notionally for convenience.

FIG. 9 is an explanatory view conceptually showing the internal structure of the concealing seal for the base material before pressurization for convenience.

FIG. 10 is an explanatory view conceptually showing the internal structure of the concealing seal for a base material after pressurization for convenience.

FIG. 11 is an explanatory view showing an example of a scratch medium including a specific invention.

FIG. 12 is an explanatory view conceptually showing the cross-sectional structure of a scratch medium for convenience.

FIG. 13 is an explanatory view conceptually showing an example of pressurization in FIG. 12 for convenience.

[Explanation of symbols]

1, 1A, 1B ... concealing seal, 2, 2B ... transparent film, 3, 3A, 3B ... concealing layer main body, 4, 4B ... mounting layer, 5 ... release paper, 6 ... light reflecting material, 7 ... light absorbing material, 8
... air, 9, 9a ... light, 10 ... base material, 11 ... letters, etc.
15: Organic polymer binder, 20: Anchor layer, 21
... Primer layer, 22 ... Lubricant layer, X ... Scratch medium.

Claims (16)

[Claims] 1. A light-reflecting substance and a light-absorbing material which make the layer irreversibly transparent when a transparentizing means is added from one upper surface to the lower surface of the transparent film, which cannot be seen in a normal state on the one side. A concealing seal formed with a concealing layer main body containing a light absorbing substance having a function of performing the following. 2. The light-reflecting material according to claim 1, wherein the light-reflecting material is a polymer particle which unevenly reduces the amount of interface with air in response to pressurization or heating by the transparentizing means. A concealing seal, wherein the light-absorbing substance mixed in the particles is a dye material that absorbs light in a state that can be discriminated after pressurizing or heating with respect to the color tone of the confidential information to be concealed. 3. The method according to claim 1, wherein the shielding layer has a wavelength of 38.
The transmittance for any light of 0 to 750 nm is 0.01
-10%, and the transmittance after pressurization is 20-95%
A concealing seal characterized by the following. 4. The concealing seal according to claim 1, wherein the light reflecting substance is a polymer particle, and the polymer particle satisfies at least the following conditions a) and b). a) Average particle diameter / 0.05-2.0 μm b) Refractive index / 1.4-1.7 (no unit) 5. The transparent film according to claim 1, wherein the transparent film is polyethylene terephthalate and has a thickness of 5 to 100 μm.
m. 6. A light-reflecting substance which absorbs light and a light-reflecting material which makes the layer irreversibly transparent when a transparentizing means is added from one upper surface to the lower surface of one side of the transparent film, which cannot be seen in a normal state. A concealing seal comprising: a concealing layer main body including a light absorbing substance having a function of performing the following; and a mounting layer formed on a lower surface of the concealing layer main body. 7. The light-reflecting material according to claim 6, wherein the light-reflecting material is a polymer particle that unevenly reduces an interface amount with air in response to pressurization or heating by the transparentizing means. The concealing seal, wherein the mixed light-absorbing substance is a pigment material that absorbs light so that the color tone of the confidential information to be concealed can be distinguished after the pressure or the heating. 8. The mixing ratio of the polymer particles as the light reflecting material and the carbon particles as the coloring material according to claim 6, wherein the mixing ratio of the carbon particles is 0.1 to 10 parts by weight with respect to 100 parts by weight of the polymer particles. Concealment seal characterized by being a part. 9. The concealing seal according to claim 6, wherein a release paper is provided on the mounting layer. 10. A light-reflecting material and a light-absorbing material which make the layer irreversibly transparent when a transparentizing means is added from one upper surface to the lower surface of the transparent film, which cannot be seen in an ordinary state. A concealing seal characterized by forming a concealing layer main body containing a light-absorbing substance having a function of performing the following and an organic polymer binder. 11. The light reflecting material according to claim 10, wherein
Polymer particles that unevenly reduce the amount of interface with air in response to pressurization or heating by the clarifying means. On the other hand, a concealing seal characterized in that it is a dye material that absorbs light in a state that can be discriminated after the pressurization or heating, and the organic polymer binder is a water-soluble resin or a water-dispersed emulsion. 12. The method according to claim 10, wherein the MFT (minimum film forming temperature) of the water-dispersed emulsion as the organic polymer binder is lower than the MFT of the polymer particles and has a temperature difference. Concealment seal. 13. The concealing seal according to claim 10, wherein the water-soluble resin as the organic polymer binder is polyvinyl alcohol. 14. A light-reflecting substance which absorbs light and a light-reflecting material which irreversibly makes a layer irreversible when a transparentizing means is added from one upper surface to the lower surface of one side of the transparent film, which is not normally visible in a normal state. A concealing seal characterized by forming a concealing layer main body having a layer containing a light-absorbing substance having a function of performing the above operation and at least one of an anchor layer and a primer layer. 15. The light reflecting material according to claim 14, wherein
A scratch medium, comprising polymer particles which unevenly reduce the amount of interface with air in response to pressurization or heating by a transparentizing means, wherein the polymer particles are a water-dispersed emulsion. 16. A scratch medium comprising: a base material provided with characters and the like on one side upper surface; and a concealing seal provided integrally with the base material so as to conceal the characters and the like.
The concealing seal is formed on a transparent film and a lower surface of one side of the transparent film, and cannot be visually observed in a normal state, but when a transparentizing means is added from one upper surface, the layer is irreversibly transparent. A concealing layer body including a light-reflecting material and a light-absorbing material having a function of absorbing light;
And a mounting layer formed on the lower surface of the concealing layer main body.