JP7233421B2 - Judgment sheet - Google Patents

Description

TECHNICAL FIELD The present invention relates to a judgment sheet capable of judging authenticity using microwaves.

Conventionally, counterfeit products of various products have been on the market, and various authenticity determination means have been adopted so as to distinguish genuine products from counterfeit products. As a means for judging authenticity, (1) special indication such as a label or print that can be visually judged by a human being is applied to the product, (2) label or printing that cannot be visually judged but can be judged by a judging device. For example, applying special indications such as

As the special display for authenticity determination in (1), for example, a polymer film laminate in which two types of polymer films, a first phase and a second phase, having different physical properties are alternately laminated on a base material. wherein at least one phase of the polymer film swells by absorbing liquid and shrinks by drying, and the surface of the polymer film laminate exhibits diffraction, interference and scattering. Examples include a display body having a fine concave-convex structure exhibiting at least one optical effect and having a stretchable base material (Patent Document 1).

As the special display for authenticity determination of (2) above, there is a display in which letters and the like emerge when LED light is applied (a product name of Dai Nippon Printing Co., Ltd., "DNP Hologram").

JP 2016-117185 A

However, the special indication that can be visually determined as in (1) above allows a forger to easily visually determine whether or not there is authenticity determination means. Therefore, such display itself tends to be easily forged. Furthermore, the display as in Patent Document 1 is a special display using a so-called hologram effect, but the production of such a special display is costly, and in reality, it cannot be used for relatively expensive products. do not get

In addition, special indications such as those described in (2) above, which cannot be determined visually, are difficult to forge themselves. is necessary. Therefore, in reality, special indications such as (2) above have to be used for relatively expensive products.

An object of the present disclosure is to provide a judgment sheet that can be manufactured at a low cost and that allows easy judgment of authenticity.

The judgment sheet of the present disclosure includes a heat-shrinkable sheet base material, a heat-generating ink layer provided on the sheet base material and having a function of heat-shrinking the sheet base material by microwave irradiation, and and a non-exothermic ink layer that is provided and does not have a function of thermally shrinking the sheet base material by microwave irradiation.

In the preferred judgment sheet of the present disclosure, the heat-generating ink layer shrinks the sheet base material by 10% or more by the microwave irradiation. In the preferred judgment sheet of the present disclosure, the heat-generating ink layer shrinks the sheet base material by 10% or more when the judgment sheet is irradiated with microwaves having a frequency of 2.45 GHz for 2 minutes. In a preferred judgment sheet of the present disclosure, the heat-generating ink layer is an ink layer having an imaginary part of a complex dielectric constant of 11 or more at a frequency of 2.45 GHz. A preferred judgment sheet of the present disclosure is that the non-heat-generating ink layer is an ink layer in which the imaginary part of the complex dielectric constant at a frequency of 2.45 GHz is less than 11. In a preferred judgment sheet of the present disclosure, the heat-generating ink layer is provided so as to partially overlap the non-heat-generating ink layer. In a preferred judgment sheet of the present disclosure, the heat generating ink layer and the non-heat generating ink layer are ink layers of similar colors. In a preferred judgment sheet of the present disclosure, the heat-generating ink layer contains a microwave absorber. In a preferred evaluation sheet of the present disclosure, the microwave absorber is at least one of carbon black, graphite, aluminum, zinc oxide, tin oxide, and iron oxide.

The judgment sheet of the present disclosure can be produced at a relatively low cost, and can be easily judged for authenticity.

FIG. 1 is a plan view of the judgment sheet of the first embodiment. FIG. 2 is an enlarged cross-sectional view cut along II-II in FIG. FIG. 3 is a perspective view showing a usage example of the judgment sheet. FIG. 4 is a perspective view showing a first example of a package with a judgment sheet. FIG. 5 is a perspective view showing a second example of a package with a judgment sheet. FIG. 6 is a reference plan view showing the state of the judgment sheet after microwave irradiation. FIG. 7 is a plan view of the judgment sheet of the second embodiment. FIG. 8 is an enlarged cross-sectional view cut along VIII-VIII in FIG. FIG. 9 is a perspective view showing a third example of a package with a judgment sheet. FIG. 10 is a plan view of the judgment sheet of the third embodiment. 11 is an enlarged cross-sectional view cut along XI-XI in FIG. 10. FIG. FIG. 12 is a plan view of the judgment sheet of the first example of the fourth embodiment. 13 is an enlarged cross-sectional view taken along line XIII-XIII of FIG. 12. FIG. FIG. 14 is a plan view of a second example judgment sheet according to the fourth embodiment. 15 is an enlarged cross-sectional view taken along line XV-XV of FIG. 14. FIG. FIG. 16 is a plan view of a judgment sheet of a third example of the fourth embodiment.

The present disclosure will be described below with reference to the drawings. In the present specification, "plan view" refers to viewing the front surface (or back surface) of the sheet substrate with the line of sight perpendicular to it, and "plan view shape" refers to the shape when viewed. Further, in this specification, the numerical range represented by “lower limit value X to upper limit value Y” means the lower limit value X or higher and the upper limit value Y or lower. When a plurality of numerical ranges are described separately, an arbitrary lower limit value and an arbitrary upper limit value can be selected, and "an arbitrary lower limit value to an arbitrary upper limit value" can be set.

[Overview of Judgment Sheet] The judgment sheet of the present disclosure includes a heat-shrinkable sheet base material, and a heat-generating ink layer and a non-heat-generating ink layer provided on the sheet base material. The exothermic ink layer is an ink layer that has the function of thermally shrinking the sheet substrate by microwave irradiation, and the non-exothermic ink layer is an ink layer that does not have the function of thermally shrinking the sheet substrate by microwave irradiation. . The term "ink layer" means a layer formed of ink and made of solidified ink.

The judgment sheet of the present disclosure is used after being processed into various forms. Typically, the judgment sheet is used as a packaging material used in the packaging field. Examples of the packaging material include packaging bodies (eg, packaging bags and packaging boxes) for packaging the products themselves, sealing materials attached to the packaging bodies, and labels and tags attached to the packaging bodies or the products.

[First Embodiment] A first embodiment relates to a judgment sheet processed into a sealing material. 1 and 2, the sealing material 1A (judgment sheet 1) has a heat-shrinkable sheet base material 2, and a heat-generating ink layer 3 and a non-heat-generating ink layer 4 provided on the sheet base material 2. . In this embodiment in which the judgment sheet 1 is used in the form of the sealing material 1A, the sheet base material 2 is formed, for example, in a strip shape in plan view.

A conventionally known heat-shrinkable film can be used as the heat-shrinkable sheet substrate 2 . Here, the heat-shrinkability means the property of shrinking when heated to a predetermined temperature (for example, 70° C. to 100° C.).

From the viewpoint of the material, the heat-shrinkable film is not particularly limited as long as it has flexibility and heat-shrinkability. Polyolefin film; polyvinyl chloride film; polyethylene terephthalate film and polylactic acid film (biodegradable film ) and other polyester films; polystyrene films; and other thermoplastic resin films. Preferably, a polyolefin film is used as the heat-shrinkable film.

A polyolefin-based film has a polyolefin-based resin as a main component resin constituting the film. The polyolefin film is not particularly limited, and includes, for example, a polypropylene film made of polypropylene; a polyethylene film made of polyethylene, etc. Polypropylene film is preferred. Examples of the polypropylene include propylene homopolymers and propylene-ethylene copolymers, and examples of the polyethylene include polyethylene homopolymers and polyethylene copolymers. The heat-shrinkable film may be colorless and transparent, colored and transparent, or opaque.

From the viewpoint of shrinkability, the heat-shrinkable film may be either a uniaxial shrinkable film that shrinks mainly in the first direction or a biaxially shrinkable film that shrinks mainly in the first and second directions. For biaxially shrinkable films that heat shrink primarily in the first and second directions, either the first direction or the second direction may be the primary heat shrink direction, or both the first and second directions may be It may be the main heat shrink direction. In this case, the sheet base material 2 is thermally shrunk to substantially the same extent in both the first direction and the second direction. Hereinafter, the main heat shrinkage direction will be referred to as the main heat shrinkage direction. The main heat shrinkage direction is the direction in which the heat shrinkage rate is the largest in the sheet base material 2 . The first direction refers to one direction in the plane of the heat-shrinkable film, and the second direction refers to the direction orthogonal to the first direction in the plane of the heat-shrinkable film.

The thermal shrinkage in the first direction (main shrinkage direction) of the uniaxially shrinkable film and the biaxially shrinkable film is, for example, 20% or more, preferably 30% or more, more preferably 40% or more, and still more preferably 50% or more. is. The thermal shrinkage of the uniaxially shrinkable film in the second direction is, for example, 0 to 10%, preferably 0 to 5%. The thermal shrinkage of the biaxially shrinkable film in the second direction is, for example, 10% or more, preferably 20% or more, more preferably 30% or more.

However, in this specification, the heat shrinkage rate is the length (original length) of the film before heating (stored under standard conditions for 24 hours), and after being immersed in hot water at 90 ° C. for 10 seconds and taken out. The length of the film (length after immersion) is measured and substituted into the following formula. The length of each film is measured under standard conditions (23° C., 1 atm, 50% relative humidity).

Thermal shrinkage rate (%) = [{(original length in first direction (or second direction)) - ((length after immersion in first direction (or second direction))}/((first direction (or the original length in the second direction)]×100.

The thickness of the sheet base material 2 is not particularly limited, and is, for example, 8 μm to 120 μm, preferably 10 μm to 80 μm, more preferably 12 μm to 60 μm.

A heat-generating ink layer 3 and a non-heat-generating ink layer 4 are provided on the sheet base material 2 . Specifically, the heat-generating ink layer 3 and the non-heat-generating ink layer 4 are arranged so as to be in contact with the surface of the sheet base material 2 .

The heat-generating ink layer 3 is an ink layer having a function of thermally shrinking the sheet base material 2 by microwave irradiation. In other words, the heat-generating ink layer 3 is an ink layer that generates heat by microwave irradiation to heat the sheet substrate 2 and cause the sheet substrate 2 to substantially thermally shrink. The term “substantially thermally shrunk” means that the rate of thermal shrinkage of the sheet base material 2 before and after the microwave treatment is, for example, 10% or more, preferably 15% or more.

The heat shrinkage ratio of the sheet base material 2 before and after the microwave treatment, that is, the heat shrinkage ratio of the sealing material 1A (judgment sheet 1) is [{(unit length before microwave treatment in the main heat shrinkage direction of the sheet base material )−(unit length after microwave treatment in main heat shrinkage direction of sheet base material)}/(unit length before microwave treatment in main heat shrinkage direction of sheet base material)]×100. Each length is measured under standard conditions.

The unit length after microwave treatment means the unit length of the sheet base material 2 after microwave treatment. Specifically, the unit length of the sealing material 1A (judgment sheet 1) after being irradiated with microwaves having a frequency of 2.45 GHz for 2 minutes by a microwave irradiation device is means. If the sealing material 1A (judgment sheet 1) is capable of shrinking by 10% or more in the main heat-shrinking direction by microwave treatment under these conditions, it is possible to appropriately judge authenticity by visual inspection.

The non-heat-generating ink layer 4 is an ink layer that does not have the function of thermally shrinking the sheet base material 2 by microwave irradiation. In other words, the non-exothermic ink layer 4 is an ink layer that does not substantially generate heat and does not substantially thermally shrink the sheet substrate 2 even after the above-described microwave treatment. The term "substantially does not generate heat" means that the sheet base material 2 is not heated to the extent that the sheet base material 2 is substantially thermally shrunk, and does not mean that the non-heat generating ink layer 4 does not generate heat at all during microwave irradiation. .

The heat-generating ink layer 3 and the non-heat-generating ink layer 4 are appropriately set in consideration of the shrinkage characteristics of the sheet base material 2 . For example, when using a sheet substrate 2 that shrinks by 10% or more in the main heat shrink direction at a relatively low temperature (for example, about 70° C.), the sheet substrate 2 can be heated to at least 70° C. during microwave irradiation. A heat-generating ink layer 3 is used. Heat-generating ink capable of heating the sheet substrate 2 to at least 100° C. during microwave irradiation when using a sheet substrate 2 that shrinks by 10% or more in the main heat shrink direction at a relatively high temperature (for example, about 100° C.). Layer 3 is used.

From the viewpoint of dielectric properties, the heat-generating ink layer 3 preferably has an imaginary part of a complex dielectric constant of 11 or more at a frequency of 2.45 GHz. The imaginary part is more preferably 100 or more, still more preferably 130 or more, and particularly preferably 190 or more. Such a heat-generating ink layer 3 can heat the sheet substrate 2 to 100° C. or higher during microwave irradiation, and can be used for sheet substrates 2 having various shrinkage characteristics. In the exothermic ink layer 3, the upper limit of the imaginary part is not particularly limited.

From the viewpoint of dielectric properties, the non-heat generating ink layer 4 preferably has an imaginary part of a complex dielectric constant of less than 11 at a frequency of 2.45 GHz. The imaginary part is more preferably 10 or less, more preferably less than 9 ink layers. Such a non-heat-generating ink layer 4 does not generate enough heat to substantially heat-shrink the sheet base material 2 when irradiated with microwaves. In the non-heat generating ink layer 4, the lower limit of the imaginary part is not particularly limited, and the theoretical lower limit is zero.

In this specification, the imaginary part of the complex dielectric constant refers to the value obtained by measuring the ink layer at a frequency of 2.45 GHz under standard conditions (23° C., 1 atm, 50% relative humidity). For the details of the method for measuring the imaginary part of the complex dielectric constant, refer to Examples. Incidentally, the imaginary part of the complex dielectric constant is generally called dielectric loss.

From the viewpoint of color, the heat-generating ink layer 3 and the non-heat-generating ink layer 4 may have the same color system, or may exhibit different colors. The similar colors mean colors that are the same or similar to each other. Specifically, the two colors have a hue difference of 90 degrees on the color wheel, a saturation range of 2 to 14 on the Munsell hue cross section, and a lightness difference of ±3. More preferably, the hue is within the range of 75 degrees difference, particularly preferably the hue is within the range of 60 degrees difference, the saturation is within the range of 4 to 14, and the lightness difference is within the range of ±2.

Preferably, the same color system is visually similar to the extent that a normal adult cannot visually distinguish between the two colors. It should be noted that, for example, even when the same color ink is printed on the printed matter, the color tone may differ between production lots. The same color system includes such a degree of color difference.

The ink forming the heat-generating ink layer 3 (hereinafter referred to as heat-generating ink) contains at least a microwave absorber and a binder resin, and may optionally contain a colorant, a solvent, and an additive.

Examples of the microwave absorber include, but are not limited to, carbon black, graphite, aluminum, aluminum oxide, zinc oxide, tin oxide, iron oxide, and conductive polymers. The microwave absorber is blended, for example, in an amount of 5 to 30 parts by weight with respect to 100 parts by weight of the binder resin. In addition, since microwave absorbers such as carbon black, graphite, aluminum, aluminum oxide, zinc oxide, tin oxide, and iron oxide also function as coloring agents, when such microwave absorbers are used, A separate coloring agent may be blended or may not be blended.

Binder resins for heat-generating inks are classified according to their curing performance, and include drying types, photopolymerization types such as ultraviolet curing types, and the like. Dry binder resins include acrylic resins, urethane resins, cellulosic resins such as nitrocellulose and cellulose acetate butyrate, vinyl chloride resins, vinyl acetate resins, polyester resins, and the like. Photopolymerizable binder resins include photopolymerizable resins such as acrylates and polymerization initiators. Examples of the solvent for the heat generating ink include esters such as ethyl acetate, propyl acetate and butyl acetate; alcohols such as methanol, ethanol, isopropyl alcohol and butanol; ketones such as acetone and methyl ethyl ketone; hydrocarbons such as toluene; water; a mixed solvent thereof, and the like. Colorants include known pigments or dyes. Additives for heat-generating inks include, for example, dispersants, plasticizers, anti-settling agents, antioxidants, ultraviolet absorbers, and flame retardants.

The ink forming the non-heat-generating ink layer 4 (hereinafter referred to as non-heat-generating ink) usually contains a colorant and a binder resin, and may optionally contain a solvent and an additive. The non-heat-generating ink layer 4 may be formed using a non-heat-generating ink containing no colorant. Conventionally known pigments and dyes can be used as the colorant of the non-heat-generating ink.

However, in general, many materials such as carbon black, graphite, aluminum, aluminum oxide, zinc oxide, tin oxide, iron oxide, etc. generate a large amount of heat when exposed to microwaves. For this reason, it is necessary to select a coloring agent for the non-heat-generating ink that can form the non-heat-generating ink layer 4 that does not substantially generate heat (for example, one whose imaginary part is less than 11). As the binder resin, solvent and additive for the non-heat generating ink, those exemplified for the binder resin, solvent and additive for the heat generating ink can be appropriately selected and used.

The thicknesses of the heat-generating ink layer 3 and the non-heat-generating ink layer 4 are not particularly limited, and are each independently, for example, 0.3 μm to 20 μm, preferably 0.4 μm to 10 μm, more preferably 0.5 μm. ~10 μm.

The heat-generating ink layer 3 and the non-heat-generating ink layer 4 as described above are each formed by printing ink on desired portions of the sheet base material 2 . Specifically, the heat-generating ink layer 3 and the non-heat-generating ink layer 4 can be formed by applying the heat-generating ink and the non-heat-generating ink to the sheet substrate 2 and solidifying them. The coating method is not particularly limited, and includes a plate printing method, a plateless printing method such as inkjet printing, and a coating method using a coater.

The plate printing method refers to a printing method using a printing plate, unlike a printing method that does not use a plate such as inkjet printing, and includes intaglio printing, letterpress printing, stencil printing, lithographic printing, and the like. . Representative examples of the intaglio printing method include gravure printing, examples of the letterpress printing method include flexographic printing and rotary letterpress printing, and examples of the stencil printing method include silk printing. Screen printing is exemplified, and lithographic printing is typically exemplified by offset printing.

Since the heat-generating ink layer 3 and the non-heat-generating ink layer 4 having a predetermined thickness can be formed with high accuracy, both the heat-generating ink layer 3 and the non-heat-generating ink layer 4 are plate-printed layers formed by a plate-printing method. preferable. In particular, since it is possible to design a wide range of ink transfer amounts, and it is possible to accurately form the heat-generating ink layer 3 and the non-heat-generating ink layer 4 with a predetermined thickness, the heat-generating ink layer 3 and the non-heat-generating ink layer 4 are formed by gravure printing. It is preferably a gravure printed layer. The plate printing layer including the gravure printing layer is composed of a group of dot-like solidified ink substances, and the state of adhesion of the solidified ink substances varies slightly depending on the printing method.

The heat-generating ink layer 3 and the non-heat-generating ink layer 4 may be independently formed by one coat of ink, or may be formed by two or more coats of ink. The heat-generating ink layer 3 and the non-heat-generating ink layer 4 are each independently preferably an ink layer formed by applying ink 1 to 20 times, more preferably 1 to 10 times, and even more preferably 1 to 5 times. , an ink layer formed by 1 to 3 coats is particularly preferred. The heat-generating ink layer 3 and the non-heat-generating ink layer 4 having a multi-layered structure may be formed by overcoating with one type of ink, or may be formed by overcoating with two or more types of ink.

The heat-generating ink layer 3 is provided on at least one of the surface and the back surface of the sheet base material 2 . Further, the heat-generating ink layer 3 may be provided on a part of the surface, or may be provided on the entire surface. The non-heat-generating ink layer 4 is provided on at least one of the front surface and the back surface of the sheet base material 2 . Further, the heat-generating ink layer 3 may be provided on a part of the surface, or may be provided on the entire surface.

Preferably, the heat-generating ink layer 3 is not provided on the entire sheet base material 2 but is provided on a part of the sheet base material 2 . In other words, the heat-generating ink layer 3 is not provided over the entire sheet base material 2, and the sheet base material 2 has a region having the heat-generating ink layer 3 and a region having no heat-generating ink layer 3. is preferred. This is because if the heat-generating ink layer 3 is provided over the entire sheet base material 2, the sheet base material 2 as a whole will thermally shrink during the microwave treatment, and the significance of providing the non-heat-generating ink layer 4 will be lost. .

When the heat-generating ink layer 3 is provided on the front surface and the back surface of the sheet base material 2, the heat-generating ink layer 3 is not provided on the entire sheet base material 2, but is provided on a part of the sheet base material 2 as viewed through a plan view. is preferably provided.

Conceptually, the plane see-through means that the line of sight is perpendicular to the surface of the sheet base material 2 and the ink layer in the direction of the line of sight is seen through. When the heat-generating ink layer 3 is provided on a part of the sheet base material 2 as viewed through a plan view, it means, for example, the following state. In the following, for the sake of explanation, the sheet substrate 2 is conceptually divided into three regions arranged in order in the surface direction (hereinafter, the conceptual three regions arranged in order are referred to as regions A, B, and C). ).

Assume that the heat-generating ink layer 3 is provided on the surface of the A region, the heat-generating ink layer 3 is provided on the back surface of the B region, and the heat-generating ink layer 3 is not provided on the front and back surfaces of the C region. In this case, the heat-generating ink layer 3 is provided in the A region and the B region of the sheet base material 2 and is not provided in the C region in plan view. This corresponds to the case where the heat-generating ink layer 3 is provided on a part of the sheet base material 2 when viewed through the plane.

The heat-generating ink layer 3 and the non-heat-generating ink layer 4 may be provided so as to overlap each other when viewed through a plan view, may be provided while being partially in contact with each other when viewed through a plan view, or may be provided apart from each other when viewed through a plan view. may be

In the case where the sheet base material 2 is divided into three areas as described above, the exothermic ink layer 3 is provided on the surface of the A area and the B area, and the B area and the C area are provided. When the non-heat-generating ink layer 4 is provided on the back surface of the region, the heat-generating ink layer 3 is provided on the surface of the A region and the B region, and the non-heat-generating ink layer 4 is provided on the surface of the B region and the C region. This applies to cases, etc. In these cases, the heat-generating ink layer 3 and the non-heat-generating ink layer 4 are provided so as to overlap each other in the B region when viewed through the plane.

As for the case where the sheet base material 2 is divided into three areas as described above, the heating ink layer 3 is provided on the surface of the area A, and the area B Examples include the case where the non-heat-generating ink layer 4 is provided on the back surface of the region, the case where the heat-generating ink layer 3 is provided on the surface of the A region, and the case where the non-heat-generating ink layer 4 is provided on the surface of the B region. In these cases, the heat-generating ink layer 3 and the non-heat-generating ink layer 4 are in contact with each other at the boundary between the A region and the B region when viewed from above.

As for the case where they are provided apart from each other in planar perspective, for the sake of explanation, if the sheet base material 2 is divided into three regions as described above, the heat-generating ink layer 3 is provided on the surface of the A region, and the back surface of the C region. The case where the non-heat generating ink layer 4 is provided on the surface of the A region, the case where the heat generating ink layer 3 is provided on the surface of the C region, and the case where the non-heat generating ink layer 4 is provided on the surface of the C region are applicable. In these cases, the heat-generating ink layer 3 and the non-heat-generating ink layer 4 are separated from each other in region B when viewed through the plane.

In the illustrated example, the heat-generating ink layer 3 and the non-heat-generating ink layer 4 are both provided on the surface of the sheet base material 2 and partially in contact with each other. In each drawing except the cross-sectional view, a large number of dots are added to the heat-generating ink layer 3 for the convenience of easily distinguishing between the heat-generating ink layer 3 and the non-heat-generating ink layer 4 .

In the illustrated example, the edge of the heat-generating ink layer 3 and the edge of the non-heat-generating ink layer 4 are represented as if they are butted against each other. However, it is difficult to precisely form the heat-generating ink layer 3 and the non-heat-generating ink layer 4 formed by the printing method such that the edges are butted against each other. For this reason, in practice, the edges of the heat-generating ink layer 3 and the non-heat-generating ink layer 4, which are partially in contact with each other, are often slightly separated from each other, or their near-edge portions are slightly overlapped. .

The planar shape of the heat-generating ink layer 3 and the non-heat-generating ink layer 4 is not particularly limited, and may be any symbolic shape such as arbitrary figures, characters, and patterns, or a chaotic shape (a shape that cannot be identified by humans). The heat-generating ink layer 3 and the non-heat-generating ink layer 4 may represent, for example, mechanically readable symbols such as barcodes and two-dimensional codes, sentences such as package inserts, and source indications such as trademarks and company names in a plan view. .

In the illustrated example, the heat-generating ink layer 3 and the non-heat-generating ink layer 4 are formed in a solid, substantially rectangular shape in plan view, and are arranged side by side so that their long sides are in contact with each other. The term "solid" means that the solidified ink forming the ink layer extends in the surface direction to form one continuous layer. However, when an ink layer is formed by a plate printing method such as gravure printing, the ink layer is composed of a collection of solidified ink particles adhered in countless dots, so macroscopically Then, the solidified material extends in the plane direction to form one continuous layer, but when viewed microscopically, there are cases where countless fine gaps exist within the plane. When viewed microscopically, even if there are fine gaps, if macroscopically one continuous layer is formed, it is included in the solid-like category.

The direction in which the heat-generating ink layer 3 and the non-heat-generating ink layer 4 are arranged is not particularly limited. It may be arranged side by side in the direction in which the sheet substrate 2 is oriented, or may be arranged side by side in a direction inclined with respect to the main heat shrinkage direction of the sheet base material 2 . In the illustrated example, for example, a sheet base material 2 whose first direction is the main heat-shrinking direction is used, and a heat-generating ink layer 3 and a non-heat-generating ink layer 4 are arranged side by side in the first direction.

Further, the sheet base material 2 may be provided with an ink layer (not shown) other than the heat-generating ink layer 3 and the non-heat-generating ink layer 4 . Hereinafter, the ink layers other than the heat-generating ink layer 3 and the non-heat-generating ink layer 4 are referred to as "other ink layers". The other ink layer is provided at desired locations on the front surface and/or the back surface of the sheet base material 2 by applying a conventionally known colored ink or transparent ink (medium ink). When another ink layer is provided, the other ink layer may be provided so as not to overlap the heat generating ink layer 3 and/or the non-heat generating ink layer 4, or part or all of it may be provided so as to overlap the heat generating ink layer 3 and/or the non-heat generating ink layer It may be provided so as to overlap with the heat-generating ink layer 4 .

Further, the other ink layer preferably includes an ink layer (conventionally known design printing layer) representing designs such as characters and patterns. The thickness of the other ink layer is, for example, 0.5 μm to 10 μm, preferably 1 μm to 5 μm.

<Usage Form of Sealing Material 1A (Judgment Sheet 1)> As shown in FIG. 3, the sealing material 1A (judgment sheet 1) is used, for example, to seal a package. The packaging body is not particularly limited, and includes a packaging box, a packaging bag, a container, and the like in which contents (contents are commodities that are substantially traded) are stored. Contents (products) are not particularly limited, and include machine parts, precision instruments, foods, accessories, cosmetics, and the like.

3 and 4 exemplify a packaging box 81 containing contents as a package. By winding the sealing material 1A around the packaging box 81 and fixing both ends of the sealing material 1A with an adhesive or the like, a package 9A with a judgment sheet as shown in FIG. 4 is obtained. Further, FIG. 5 illustrates a container 82 containing contents as a package. By similarly attaching the sealing material 1A around such a container, a package 9B with a judgment sheet is obtained.

When the sealing material 1A (judgment sheet 1) of the judgment sheet-equipped packages 9A and 9B is irradiated with microwaves, the area of the sheet base material 2 where the exothermic ink layer 3 is provided thermally shrinks. Although the packages 9A and 9B with judgment sheets may be exposed to the microwave irradiation device as they are, usually, the sealing material 1A (judgment sheet 1) is removed from the packaging, and microwaves are irradiated by the microwave irradiation device.

The microwave treatment time is equal to or longer than the time required for the sheet base material 2 to start thermal shrinkage, and is, for example, about 10 seconds to 3 minutes. The microwave irradiation device is not particularly limited as long as it can irradiate microwaves (for example, frequencies of 300 MHz to 300 GHz), but it is preferable to use a microwave oven for home or commercial use because it is versatile. Generally, microwave ovens for home or business use irradiate microwaves with a frequency of 2.45 GHz. Those having high frequency output are widely used.

When the sealing material 1A (judgment sheet 1) is irradiated with microwaves, the heat-generating ink layer 3 generates heat, while the non-heat-generating ink layer 4 does not substantially generate heat. Therefore, as shown in FIG. 6, the area of the sheet substrate 2 provided with the heat-generating ink layer 3 thermally shrinks, while the area not provided with the heat-generating ink layer 3 (the non-heat-generating ink layer 4 is provided). (including the closed area) does not substantially heat shrink, and only a specific portion of the sealing material 1A becomes deformed. However, with the thermal contraction of the area provided with the heat-generating ink layer 3, the area not provided with the heat-generating ink layer 3 is also deformed due to the heat shrinkage, but this deformation is not caused by the non-heat-generating ink layer 4. do not have.

The thermal contraction of the area where the heat-generating ink layer 3 is provided proves that the sealing material 1A (judgment sheet 1) is a genuine product. In addition, FIG. 6 illustrates a case where the sheet base material 2 is used which has the first direction as the main heat shrink direction and does not substantially heat shrink in the second direction.

<Effect> The judgment sheet 1 of the present disclosure provides the heat-generating ink layer 3 on the sheet base material 2, and judges the authenticity based on the deformation of the sheet base material 2 after microwave irradiation. For example, a microwave oven can be used for the determination of authenticity, so the determination can be easily performed, and since the microwave oven is widely used, the person who determines the authenticity does not need to newly invest in equipment. There is no need to do so, or (since the microwave oven itself is inexpensive), the cost can be reduced by investing in new equipment. In addition, since the judgment sheet 1 of the present disclosure can be constructed by providing the heat-shrinkable sheet base material 2 with the heat-generating ink layer 3 and the non-heat-generating ink layer 4, it can be manufactured at a very low cost.

In general, since a counterfeiter can easily identify the presence of authenticity determination means that can be visually determined by a person, there is a drawback that a counterfeit product of the determination sheet 1 itself is immediately put on the market. In this regard, the judgment sheet 1 of the present disclosure can be easily formed so that the heat-generating ink layer 3, the non-heat-generating ink layer 4, and other ink layers provided as necessary can be formed into one design as a whole. It is difficult for a counterfeiter to easily visually determine whether or not the counterfeiter is provided with authenticity determination means. In particular, when the heat-generating ink layer 3 and the non-heat-generating ink layer 4 have similar colors, it is impossible to visually distinguish between the heat-generating ink layer 3 and the non-heat-generating ink layer 4, making it easier to determine whether the authenticity determination means is present or not. becomes difficult.

As a specific authenticity determination method, there is a method of distinguishing between genuine products and counterfeit products. When the judgment sheet 1 of the present disclosure undergoes microwave treatment, a portion of the judgment sheet is deformed as the heat generating ink layer 3 heats up, and the deformation can be visually confirmed. For this reason, for example, the seller of the genuine article asks the judge who judges the authenticity whether the shape of the judgment sheet 1 after microwave treatment, which part of the ink layer on the surface of the judgment sheet 1 is deformed, etc. etc. The judge who received the information performs microwave processing on the judgment sheet 1, confirms the shape change of the judgment sheet 1 due to the microwave processing, and compares it with the transmitted information. Thereby, the judge can judge whether the product to which the judgment sheet 1 is attached is a genuine product or a counterfeit product.

Another specific authenticity determination method is a method of determining whether or not the determination sheet 1 is irradiated with microwaves. That is, if the product is attached with the determination sheet 1 of the present disclosure, it can be easily confirmed whether or not the product has been irradiated with microwaves by a microwave oven or the like.

Hereinafter, another embodiment of the present disclosure will be described, but in the description, mainly different configurations and effects from the above-described embodiments will be described. The description of the configuration may be omitted.

[Second Embodiment] A second embodiment relates to a judgment sheet processed into a label. 7 and 8, the label 1B (judgment sheet 1) has a heat-shrinkable sheet base material 2, and a heat-generating ink layer 3 and a non-heat-generating ink layer 4 provided on the sheet base material 2. . In the present embodiment in which the judgment sheet 1 is used in the form of a label 1B, the sheet base material 2 has, for example, a substantially rectangular shape in a plan view as shown in the drawing, or a substantially circular shape or a substantially circular shape (not shown). It is formed in an elliptical shape, a substantially polygonal shape such as a substantially triangular shape or a substantially hexagonal shape, a substantially star shape, or any other shape.

The label 1B may have an adhesive layer or may not have an adhesive layer. The adhesive layer is a layer for adhering the label 1B to an adherend, and is formed of, for example, a pressure-sensitive adhesive or an adhesive. Also, the label 1B may have a single-layer structure, or may have a multi-layer structure in which two or more peelable labels 1B are laminated. In the case of a single-layer structure, the label 1B itself is produced from the judgment sheet 1. FIG.

The illustrated label 1B has a multi-layer structure having an adhesive layer 53 . This label 1B has, for example, a first piece 51 and a second piece 52 laminated on the back surface of the first piece 51, and the first piece 51 is peelable from the surface of the second piece 52. is glued with An adhesive layer 53 is provided on the back surface of the second piece 52 .

The planar shapes of the first piece 51 and the second piece 52 may be the same shape and size as shown, or may be different shapes and/or different sizes. If the sizes are different, the first piece 51 is usually formed smaller than the second piece 52 . Means for adhering the first piece 51 to the second piece 52 in a detachable state can be conventionally known, for example, pseudo-adhering the back surface of the first piece 51 to the surface of the second piece 52, Interposing a release layer and an adhesive layer between the first piece 51 and the second piece 52 can be mentioned.

In the illustrated example, the back surface of the first piece 51 is quasi-bonded to the surface of the second piece 52 . Specifically, for example, the resin layer 54 is provided on the back surface of the first piece 51 (or the surface of the second piece 52), and the second piece 5
2 (or the back surface of the first piece 51) is provided with a release layer 55, and the interface between the resin layer 54 and the release layer 55 is pseudo-bonded. can be peeled off from the

At least one of the first piece 51 and the second piece 52 is formed from the judgment sheet 1, preferably the first piece 51 is formed from the judgment sheet 1 and the second piece 52 is a conventionally known flexible label 1B substrate ( For example, it is formed from a non-heat-shrinkable synthetic resin film, paper, synthetic paper, etc.). The first piece 51 made of the judgment sheet 1 has a heat-shrinkable sheet base material 2, a heat-generating ink layer 3, and a non-heat-generating ink layer 4, as in the first embodiment. In addition, the code|symbol 56 of FIG. 7 shows another ink layer.

For example, as shown in FIG. 9, the label 1B (judgment sheet 1) of the present embodiment is used by being attached to a package via an adhesive layer 53. As shown in FIG. In addition, in FIG. 9, the blister container 83 in which the content was accommodated is illustrated as a package.

By removing the label 1B from the judgment sheet-equipped package 9C and irradiating it with microwaves, the region provided with the heat-generating ink layer 3 is thermally shrunk in the same manner as in the first embodiment, and authenticity can be judged. In particular, in the label 1B in which the first piece 51 and the second piece 52 are detachably laminated as described above, the first piece 51, which is the judgment sheet 1, can be peeled off and subjected to microwave treatment. In addition, a mode in which both pieces 51 and 52 are detachably adhered without providing an adhesive layer on the first piece 51 (for example, when the pseudo adhesion is performed as described above), the peeled off first piece 51 (determination The sheet 1) does not adhere to the microwave irradiation device, and the region provided with the heat-generating ink layer 3 can be thermally shrunk without restriction during the microwave treatment.

[Third Embodiment] A third embodiment relates to a judgment sheet processed into a tag. 10 and 11, a tag 1C (judgment sheet 1) has a heat-shrinkable sheet base material 2, and a heat-generating ink layer 3 and a non-heat-generating ink layer 4 provided on the sheet base material 2. .

The tag 1C may have a single-layer structure, or may have a multi-layer structure in which two or more peelable layers are laminated. In the case of a single-layer structure, the tag 1C itself is produced with the judgment sheet 1. FIG. The illustrated tag 1C has a multilayer structure.

This tag 1C has, for example, a first piece 61 and a second piece 62 laminated on the back surface of the first piece 61, and the first piece 61 is peelable from the surface of the second piece 62. is glued with The planar shapes of the first piece 61 and the second piece 62 may be the same shape and size, or may be different shapes and/or different sizes. The illustrated example illustrates a case where the first piece 61 and the second piece 62 having different shapes and sizes are used. For example, the first piece 61 has a shape in plan view different from that of the second piece 62 and is formed to have a smaller area than the second piece 62 .

Means for adhering the first piece 61 to the second piece 62 in a detachable state can employ conventionally known means. Interposing a release layer and an adhesive layer between the first piece 61 and the second piece 62 can be mentioned. For the same reason as in the second embodiment, an aspect in which both pieces are releasably adhered (for example, pseudo-adhesion) is preferable. In the illustrated example, the back surface of the first piece 61 is quasi-bonded to the surface of the second piece 62 via the resin layer 64 and the release layer 65, as in the second embodiment.

At least one of the first piece 61 and the second piece 62 is formed from the judgment sheet 1, preferably the first piece 61 is formed from the judgment sheet 1 and the second piece 62 is formed from a conventionally known tag base material. . A first piece 61 made of the judgment sheet 1 has a heat-shrinkable sheet base material 2, a heat-generating ink layer 3, and a non-heat-generating ink layer 4, as in the first embodiment. The tag base material that constitutes the second piece 62 may be a flexible base material or a hard base material that is difficult to bend. Examples of hard substrates include synthetic resin plates, cardboard, metal plates, wood plates, ceramic plates, and the like. Further, the second piece 62 may be formed with a hole 67 for inserting an attachment string or the like. In addition, the code|symbol 66 of FIG. 10 shows another ink layer.

The tag 1C (judgment sheet 1) of the present embodiment is also used by appropriately attaching it to a package or the like. Similar to the second embodiment, the tag 1C can also be authenticated by peeling off the first piece 61 (judgment sheet 1) and irradiating it with microwaves.

[Fourth Embodiment] The fourth embodiment relates to various specific examples of the arrangement pattern of the heat-generating ink layer and the non-heat-generating ink layer. In each of the above-described embodiments, the case where the exothermic ink layer 3 and the non-exothermic ink layer 4 are arranged side by side while being partially in contact with each other when viewed through the plane has been described in detail. For example, as shown in FIGS. , the heat-generating ink layer 3 and the non-heat-generating ink layer 4 may be provided so as to partially overlap each other when viewed through the plane. Various arrangement patterns of the fourth embodiment can be appropriately applied to the above-described first to third embodiments, but the drawing shows the sealing material 1A as an example.

12 and 13, the heat-generating ink layer 3 is composed of an overlapping portion partially overlapping the non-heating ink layer 4 and an independent portion not partially overlapping the non-heating ink layer 4. In FIGS. Similarly, the non-heat-generating ink layer 4 is composed of an overlapping portion partially overlapping the heat-generating ink layer 3 and an independent portion partially not overlapping the heat-generating ink layer 3 . In the overlapping portion, the heat-generating ink layer 3 may be laminated on the surface of the non-heat-generating ink layer 4 as shown, or the non-heat-generating ink layer 4 may be laminated on the surface of the heat-generating ink layer 3, although not shown. It may be laminated.

Moreover, as shown in FIGS. 14 and 15 , the entire heat-generating ink layer 3 may be provided so as to partially overlap the non-heat-generating ink layer 4 . In this case, the non-heat-generating ink layer 4 may be laminated on the entire surface of the heat-generating ink layer 3 as shown in the figure, or the heat-generating ink layer 3 may be laminated on a part of the surface of the non-heat-generating ink layer 4 although not shown. may be entirely laminated.

For example, the authenticity determination sheet 1 can be considered in which the heat-generating ink layer 3 is partially provided within the range of the non-heat-generating ink layer 4 which is solid and formed in a desired shape in plan view. As the partial exothermic ink layer 3, for example, a layer that represents characters or the like in a plan view can be used. When the authenticity determination sheet 1 is irradiated with microwaves, only the heat-generating ink layer 3 (for example, characters) shrinks and appears to float, allowing the authenticity to be determined. This is effective because a counterfeiter cannot visually determine that the heat-generating ink layer 3 is provided within the range of the solid non-heat-generating ink layer 4 .

When the heat-generating ink layer 3 and the non-heat-generating ink layer 4 of the same color are used, the overlapped portion is, in terms of appearance, whether there is an overlapped portion (both layers are overlapped, or only one of the layers is overlapped). ) can be effectively prevented from forgery.

Further, even when the heat generating ink layer 3 and the non-heat generating ink layer 4 are not of the same color system, the color of the ink layer laminated on the upper side is set to a color that hides the color of the lower ink layer, and the sheet is opaque. By using the base material 2, it becomes impossible to determine the presence or absence of the overlapping portion. For example, referring to FIGS. 14 and 15, the upper non-heat-generating ink layer 4 may be black, and the lower heat-generating ink layer 3 may be silver.

Moreover, as shown in FIG. 16, the heat-generating ink layer 3 and the non-heat-generating ink layer 4 may each be formed so as to represent a symbol in plan view. Symbols include numerals (symbols representing numbers), letters (symbols representing words), patterns (symbols representing shapes such as objects), and graphics (symbols having specific meanings such as squares). Preferably, they are numbers or letters.

In the illustrated example, for example, the number "1234567890" is represented on the front surface (or back surface) of the sheet base material 2 using the heat generating ink layer 3 and the non-heat generating ink layer 4 . Some of the numbers are formed by the heat-generating ink layer 3 and some numbers are formed by the non-heat-generating ink layer 4 . For example, the heat-generating ink layer 3 represents the number "5", and the non-heat-generating ink layer 4 represents nine numbers other than "5". In this case, if the heat-generating ink layer 3 and the non-heat-generating ink layer 4 of the same color system are used, the 10 numbers are just a list of numbers in appearance, but when irradiated with microwaves, the periphery of the number "5" becomes Heat shrinks and deforms.

It is easy for the forger to represent the number "1234567890", but it is difficult for the forger to easily visually determine whether or not the number "5" is provided with authenticity determination means. In particular, when the number "5" and other numbers are of the same color, it is difficult to visually distinguish between them, making it more difficult to determine whether or not there is authenticity determination means.

Such a judgment sheet 1 can be effectively used, for example, as follows. Taking the case of representing ten numbers as an example, the manufacturer of the judgment sheet 1 expresses only the number "1" in the heat-generating ink layer 3 for the judgment sheet 1 of the first lot, and the second lot As for the judgment sheet 1, the number to be formed by the heat-generating ink layer 3 is set for each manufacturing lot, such as expressing only the number "2" by the heat-generating ink layer 3. This setting is communicated to the user of the judgment sheet 1, and the user uses the judgment sheet 1 for each lot in association with the product.

For example, for products manufactured on a certain day, a judgment sheet 1 in which only the number "1" is represented by the heat-generating ink layer 3 is used, and for products manufactured on the next day, only the number "2" is used. For example, a judgment sheet 1 represented by an ink layer 3 is used. Then, the association information between the products and the judgment sheet 1 is transmitted to the person who judges the authenticity. In this way, the judgment sheet 1 that can be thermally shrunk around various numbers is provided to the market, so it is believed that counterfeiting can be reliably prevented.

In addition, as the symbols for the heat-generating ink layer 3 and the non-heat-generating ink layer 4, when using non-uniform symbols such as the manufacturing lot or manufacturing date as described above, the heat-generating ink layer 3 and the non-heat-generating ink layer 4 are: It is preferably formed using a plateless printing method such as an inkjet printing method, which allows flexible setting changes. However, such non-uniform symbols may be formed by a plate printing method such as a gravure printing method.

In addition, two or more configurations selected from the above various embodiments may be combined as appropriate, or one or two or more configurations selected from the above various embodiments may be replaced with other embodiments. may

Examples and comparative examples of the present disclosure are shown below to further describe the present disclosure in detail. However, the present disclosure is not limited to the following examples.

[Preparation of Ink Layer A and Measurement of Imaginary Part of Complex Permittivity] Black ink A obtained by adjusting a commercially available black ink by a known general method so as to be gravure printable was applied to a polypropylene film. (Kohjin Polyset AS, manufactured by KOHJIN FILM & CHEMICALS Co., Ltd.) was solidly printed using a gravure printing machine to form an ink layer A. Although the thickness of the film and the thickness of the ink layer are set in advance, please refer to the accurately measured values when measuring the imaginary part of the complex dielectric constant.

This polypropylene film was a biaxially shrinkable film, and had a heat shrinkage rate of about 16% in the MD direction and a heat shrinkage rate of about 20% in the TD direction. However, this thermal shrinkage rate is a value measured at 100° C. according to JIS Z 1709. Further, the ink layer A was formed in a rectangular shape of length×width=350 mm×80 mm in plan view.

The film partially formed with the ink layer A was used as an evaluation sample, and the imaginary part of the complex dielectric constant was measured according to the following method to evaluate the shrinkability described later. Table 1 shows the results.

In the evaluation sample, the area where the ink layer A is laminated is cut into a rectangle of length x width = 76 mm x 30 mm (this cut piece has an ink layer over the entire film), and the width direction is the circumferential direction. and set it in the cylinder of a cylindrical cavity resonator of the following cavity resonator perturbation method permittivity measurement system, and under standard conditions (23 ° C., 1 atm, relative humidity 50%), the following measurement method The imaginary part ε _S of the complex relative permittivity of the evaluation sample was measured according to .

<System configuration> Network analyzer: E8361A manufactured by Agilent Cylindrical cavity resonator: CP481 manufactured by Kanto Denshi Applied Development Co., Ltd. Measurement frequency: 2.45 GHz Measurement mode: TM020 Calculation program: CPMA-PNA

<Measurement conditions> Sample width input value: 30 mm. Sample thickness input value: actual thickness of sample t _S

<Measurement of Thickness> Film thickness: Spline micrometer SPM2-25MX manufactured by Mitutoyo Corporation Thickness of ink layer: 3D measuring laser microscope LEXT OLS4100 manufactured by Olympus Corporation. The measurement magnification was 2160 times, and the measurement field was 128 μm.

<Calculation of Imaginary Part of Complex Relative Permittivity of Ink Layer> From the obtained measured value ε _S , the imaginary part ε _A of the complex relative permittivity of the ink layer was calculated using Equation (1). The imaginary part ε _B of the complex dielectric constant of the film itself is obtained by measuring a polypropylene film having no ink layer as a blank using the above-described measurement system and measurement conditions. ε _A =(t _S ε _S −t _B ε _B )/t _A formula (1) ε _A : imaginary part of the complex relative permittivity of the ink layer ε _S : imaginary part of the complex relative permittivity of the evaluation sample (measured value ) ε _B : Imaginary part of complex dielectric constant of film (measured value) t _A : Thickness of ink layer (μm) t _S : Total thickness of evaluation sample (μm) t _B : Thickness of film (μm)

[Preparation of Ink Layer B and Measurement of Imaginary Part of Complex Relative Permittivity] Instead of black ink A, commercially available black ink was adjusted by a known general method so that gravure printing was possible. Ink layer B was prepared in the same manner as ink layer A except that black ink B was used, and the imaginary part of the complex dielectric constant was measured. Table 1 shows the results. The black ink is ink containing carbon black or graphite and exhibiting a black color.

[Preparation of Ink Layer C and Measurement of Imaginary Part of Complex Relative Permittivity] Instead of black ink A, commercially available black ink was adjusted by a known general method so that gravure printing was possible. Ink layer C was prepared in the same manner as ink layer A except that black ink C was used, and the imaginary part of the complex dielectric constant was measured. Table 1 shows the results.

[Preparation of Ink Layer D and Measurement of Imaginary Part of Complex Relative Permittivity] Instead of black ink A, commercially available black ink was adjusted by a known general method so that gravure printing was possible. Ink layer D was prepared in the same manner as ink layer A except that black ink D was used, and the imaginary part of the complex dielectric constant was measured. Table 1 shows the results.

[Preparation of Ink Layer E and Measurement of Imaginary Part of Complex Relative Permittivity] Instead of black ink A, commercially available black ink was adjusted by a known general method so that gravure printing was possible. Ink layer E was prepared in the same manner as ink layer A except that black ink E was used, and the imaginary part of the complex dielectric constant was measured. Table 1 shows the results.

[Preparation of Ink Layer F and Measurement of Imaginary Part of Complex Relative Permittivity] Instead of black ink A, commercially available black ink was adjusted by a known general method so that gravure printing was possible. Ink layer F was prepared in the same manner as ink layer A except that black ink F was used, and the imaginary part of the complex dielectric constant was measured. Table 1 shows the results.

[Preparation of Ink Layer G and Measurement of Imaginary Part of Complex Relative Permittivity] Instead of black ink A, commercially available silver ink was adjusted by a known general method so as to enable gravure printing. Ink layer G was prepared in the same manner as ink layer A except that silver ink G was used, and the imaginary part of the complex dielectric constant was measured. Table 1 shows the results. The silver ink is an ink containing an aluminum paste containing aluminum powder, which is a metal powder, and has a silver color.

[Preparation of Ink Layer H and Measurement of Imaginary Part of Complex Relative Permittivity] In place of black ink A, commercial silver ink was adjusted by a known general method so as to enable gravure printing. Ink layer H was prepared in the same manner as ink layer A except that silver ink H was used, and the imaginary part of the complex dielectric constant was measured. Table 1 shows the results.

[Preparation of Ink Layer I and Measurement of Imaginary Part of Complex Relative Permittivity] In place of black ink A, commercial silver ink was adjusted by a known general method so that gravure printing was possible. Ink layer I was prepared in the same manner as ink layer A except that silver ink I was used, and the imaginary part of the complex dielectric constant was measured. Table 1 shows the results.

[Heat shrinkability of film having ink layers A to I] Each evaluation sample (each film having ink layers A to I) was placed in a commercially available microwave oven (frequency 2.45 GHz, rated high frequency output 500 W). and microwaved for 2 minutes. The results are shown in the "Evaluation of shrinkage" column of Table 1. "A" means that a shrinkage rate of 10% or more was confirmed before and after microwave treatment in the main heat shrinkage direction of the polypropylene film that is the sheet base material, and "N" means that no shrinkage was confirmed. means

As a result, the film having the ink layer A, the film having the ink layer B, the film having the ink layer C, the film having the ink layer E, the film having the ink layer G, and the film having the ink layer H shrunk, but The film with ink layer D, the film with ink layer F, and the film with ink layer I did not shrink. Ink layers A to C, E, G and H can be used as exothermic ink layers, and ink layers D, F and I can be used as non-exothermic ink layers.

In addition, the ink layers A to F all looked black and could not be distinguished from each other by the naked eye. Even if there is, it can be seen that some have heat shrinkability and some do not. Similarly, the ink layers G to I all looked like silver layers, but the heat shrinkability of each ink layer was completely different as described above.

[Example 1] Black ink A was solidly gravure-printed on the surface of the polypropylene film (heat shrinkage in the MD direction: about 16%, heat shrinkage in the TD direction: about 20%) to obtain a thickness of 0. An ink layer A having a rectangular shape in a plan view of 5 μm and length×width=5 mm×60 mm was formed. Further, black ink D was gravure-printed solidly on the surface of the film at a distance of 15 mm in the vertical direction from the ink layer A, resulting in a rectangular ink having a thickness of 0.5 μm and a length×width=5 mm×60 mm in plan view. Layer D was formed.

The film with the ink layer was placed in a commercially available microwave oven (frequency 2.45 GHz, rated high frequency output 500 W) and irradiated with microwaves for 2 minutes. Otherwise the film did not shrink.

[Example 2] A film with an ink layer was produced in the same manner as in Example 1 except that the black ink A was replaced with the black ink B, and microwave irradiation was performed. The film shrunk at 20°C, but the film did not at any other time.

[Example 3] A film with an ink layer was produced in the same manner as in Example 1 except that the black ink A was replaced with the black ink C, and microwave irradiation was performed. The film shrunk at 20°C, but the film did not at any other time.

[Comparative Example 1] A film with an ink layer was produced in the same manner as in Example 1 except that the black ink A was replaced with the black ink D. When the film was irradiated with microwaves, the film did not shrink as a whole. rice field.

[Comparative Example 2] A film with an ink layer was produced in the same manner as in Example 1, except that the black ink D was replaced with the black ink A. When the film was irradiated with microwaves, one ink layer A was laminated. The film shrunk both at the location where the ink layer A was laminated and at the location where another ink layer A was laminated.

In each of the films with ink layers of Examples 1 to 3 and Comparative Examples 1 and 2, the two ink layers were black, and the two ink layers could not be visually distinguished from each other. The films with ink layers of Examples 1 to 3 can be used as judgment sheets because only the portion where one ink layer is laminated shrinks when irradiated with microwaves.

The film with an ink layer of Comparative Example 1 cannot be used as a judgment sheet because it does not change in appearance even when irradiated with microwaves. The film with an ink layer of Comparative Example 2 cannot be used as a judgment sheet because both portions where the two ink layers are laminated shrink when irradiated with microwaves.

Normally, only one type of ink of a predetermined color such as black is used (for example, there is no meaning in using two or more different types of black ink to express the same black color). He discovered that some inks of the same color system have heat shrinkability and others do not, and he invented a method for inexpensively and easily authenticating inks by using two or more types of inks. It is.

Reference Signs List 1, 1A, 1B, 1C Judgment sheet 2 Sheet substrate 3 Heat-generating ink layer 4 Non-heat-generating ink layer

Claims (9)

a heat-shrinkable sheet base material; a heat-generating ink layer provided on the sheet base material and having a function of thermally shrinking the sheet base material by microwave irradiation; A judgment sheet, comprising: a non-exothermic ink layer that does not have a function of thermally shrinking the sheet base material. 2. The judgment sheet according to claim 1, wherein said exothermic ink layer shrinks said sheet base material by 10% or more by said microwave irradiation. 3. The judgment sheet according to claim 1, wherein the heat-generating ink layer shrinks the sheet base material by 10% or more when the judgment sheet is irradiated with microwaves having a frequency of 2.45 GHz for 2 minutes. The determination sheet according to any one of claims 1 to 3, wherein the heat-generating ink layer is an ink layer having an imaginary part of a complex dielectric constant of 11 or more at a frequency of 2.45 GHz. 5. The judgment sheet according to any one of claims 1 to 4, wherein the non-heat generating ink layer is an ink layer having an imaginary part of a complex dielectric constant of less than 11 at a frequency of 2.45 GHz. The judgment sheet according to any one of claims 1 to 5, wherein the heat-generating ink layer is provided so as to partially overlap the non-heat-generating ink layer. The judgment sheet according to any one of claims 1 to 6, wherein the heat-generating ink layer and the non-heat-generating ink layer are ink layers of similar colors. The judgment sheet according to any one of claims 1 to 7, wherein the exothermic ink layer contains a microwave absorber. 9. The judgment sheet according to claim 8, wherein the microwave absorber is at least one of carbon black, graphite, aluminum, aluminum oxide zinc oxide, tin oxide, iron oxide, and a conductive polymer.

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