JP2022108415A - anti-counterfeit media - Google Patents

Abstract

[Problem] To provide a highly secure counterfeit prevention medium that makes counterfeiting and copying difficult by increasing the luminescence intensity in visualizing the latent image for a specific wavelength and maintaining a state in which authenticity can be reliably determined by forming the latent image from a collection of thin lines, while reducing the visibility of the latent image ink printed portion under normal ambient light. [Solution] This counterfeit prevention medium comprises a printed layer on a substrate, in which a background portion and a latent image portion are formed, and is characterized in that the latent image portion is formed from at least one type of fluorescent ink having fluorescence, is made up of a collection of thin lines arranged with a constant line width, and expresses a pattern of solid lines or solid paint. [Selected Figure] Figure 1

Description

It relates to an anti-counterfeiting medium.

In the past, in order to prevent unauthorized use of media such as gift certificates, bank notes, stock certificates, securities such as bonds, various certificates, and valuable documents through counterfeiting and duplication, printing has been performed using sophisticated printing technology. However, in recent years, in view of the frequent occurrence of unauthorized use due to forgery and duplication, special anti-counterfeiting measures have been taken in addition to such sophisticated printing.

Known special anti-counterfeiting measures include a method of incorporating a member or structure that is difficult to form, such as a hologram or laser engraving, or a method of creating a latent image.

As a technology that applies latent images, for example, a latent image that cannot be observed with the naked eye under normal ambient light is created by using special inks made of materials that develop colors when irradiated with light of specific wavelengths, such as ultraviolet rays and infrared rays. and irradiating it with light of the specific wavelength to make the latent image stand out and visualize it, thereby determining authenticity.

However, in some cases, these latent images can be visually confirmed due to impregnation of ink used for latent image formation or glossiness of the ink or the medium itself.

If the latent image portion is easily identified in this way, it becomes easier to identify the material forming the latent image, which increases the risk of the medium being counterfeited.

As countermeasures to prevent this, proposals have been made to create the latent image portion in a deep layer portion of the medium (Patent Document 1 below), or to make the latent image portion difficult to see with a protective layer provided on the surface of the medium (Patent Document 2 below). is done.

In addition, by using negative-positive plates for the print design section and the varnish section and using a halftone dot pattern, the boundaries between the printed areas of the fluorescent ink can be clearly defined without relying on such a complicated structure in which a latent image is created in the vertical direction of the medium. A technique for performing invisible printing more inconspicuously has also been proposed (Patent Document 3 below).

Japanese Patent No. 4517109 Japanese Patent No. 4028851 Japanese Patent No. 5262961

However, the techniques of Patent Documents 1 and 2 above have the problem of increasing the manufacturing cost because a step of creating a latent image portion in the longitudinal direction of the medium is added.

In the technique of Patent Document 3, halftone dots are used in the latent image portion in order to make it difficult to see. There is a problem that the visualization of the image becomes insufficient and the determination becomes difficult.

Accordingly, the present invention has been made to address the above-described problems, and the latent image portion is formed of a set of fine lines to increase the emission intensity in visualizing the latent image with respect to a specific wavelength. To provide an anti-counterfeiting medium with high security that makes it difficult to forge and copy by lowering the visibility of the latent image printed part under normal ambient light while maintaining a state in which authenticity can be reliably determined by intended to

As a means for solving the above-mentioned problems, the invention according to claim 1 is a forgery prevention medium having a printing layer formed by forming a background portion and a latent image portion on a base material, wherein the latent image portion An anti-counterfeiting medium characterized in that the image portion is formed of a fluorescent ink having at least one type of fluorescence, consists of a set of fine lines arranged with a constant line width, and expresses a solid line or solid pattern. be.

In the invention according to claim 2, the printing layer comprises at least one near-white pigment that emits light of the same or different wavelength when irradiated with light of a predetermined wavelength, and an oxidized transparent base ink. the fluorescent ink of polymerization curing type;
2. The anti-counterfeiting medium according to claim 1, characterized by comprising a laminate of varnish having the same color as the fluorescent ink.

The invention according to claim 3 is the forgery prevention medium according to claim 1 or 2, wherein the printed layer is formed by offset printing.

In the invention according to claim 4, the solid line has a short side shorter than a solid line width, a width of 0.05 mm or more and 0.5 mm or less, preferably 0.1 mm or more and 0.5 mm or less, and a long side The thin line is a rectangle whose length is 100 times or less than the width, and the long side is in the normal direction of the solid line, the short side is in the tangential direction of the solid line, and the distance between the adjacent thin line is the above 4. The anti-counterfeit medium according to any one of claims 1 to 3, wherein the anti-counterfeit medium is arranged at intervals equal to the short side length of the fine wire.

According to a fifth aspect of the invention, the solid pattern is formed by arranging a plurality of the solid lines so that the ink density is 40% or more and 90% or less. 5. The forgery prevention medium according to any one of 4.

In the sixth aspect of the present invention, the varnish is matte varnish, gloss varnish, or a mixture thereof, and halftone dots are present in a range of 40% or more and 100% or less regardless of the printing pattern of the fluorescent ink. 6. The anti-counterfeiting medium according to any one of claims 1 to 5, wherein the entire surface is solid.

According to the present invention, since only the latent image printing layer is processed, there is no need to use a special base material, so it is possible to suppress an increase in the manufacturing cost of the medium.

In addition, fluorescent printing can be applied to both the solid line pattern and the solid pattern without changing the appearance of the conventional latent image.

While maintaining the concealability of the latent image under ambient light and maintaining a high anti-counterfeiting effect, the density of the fluorescent printed area can be maintained at a high level. You can increase your credibility.

FIG. 2 is a schematic plan view showing a solid line portion in the embodiment; FIG. 2 is a schematic plan view showing a solid pattern portion in the embodiment; Emission spectrum obtained in Example 3.

A mode for carrying out the present invention will be described below.

FIG. 1 is an image diagram of a latent image portion formed by a solid line 1. FIG. The image in full size is shown in the lower left, and the enlarged image is shown in the upper right. By arranging the fine lines 2 at equal intervals so as to form a set of fine lines in the tangential direction of the solid line 1 instead of printing the pattern of the latent image on the solid line 1 entirely or by halftone dots, the solid line 1 can be printed. expresses

The sizes of the thin lines 2, each of which is a rectangle, are as follows. The length D of the short side is shorter than the width of the solid line 1 and is 0.05 mm or more and 0.5 mm or less, preferably 0.1 mm or more and 0.5 mm or less, and the length L of the long side is equal to the width W of the solid line 1. , not more than 100 times the length of said short side.

The arrangement of the thin wires 2 is as follows. The long side L is in the normal direction of the solid line 1, the short side D is in the tangential direction of the solid line 1, and the distance between each thin line 2 and the adjacent thin line 2 is the short side D of the thin line 2. Space them evenly so that they are equal.

For example, when the solid line 1 is placed horizontally, the direction of the fine line 2 is such that the short side D of the fine line is horizontal and the long side L is vertical.

A latent image portion as a solid line 1 is formed by arranging the above so as to form a set of fine lines 2 with respect to each portion of the solid line 1 .

FIG. 2 is an image diagram of a latent image portion composed of solid pattern 3 (hereinafter referred to as solid pattern 3). The image in full size is shown in the lower left, and the enlarged image is shown in the upper right. In this case as well, the pattern of the latent image is not printed on the entire solid pattern 3 or halftone dots, but is expressed as a set of juxtaposed solid lines 1 as a set of thin lines 2 formed by the above method.

In this case, the pitch P between the adjacent thin lines 2, that is, the sum of the width D of the thin lines 2 and the dimension S of the space without ink, is D/ In order for P to be 40% or more and 90% or less, the dimension S of the space is not necessarily the same as the width D of the fine line 2, but is 3/2 to 1/9 times D.

The space S is set between each solid line 1 and the adjacent solid line 1 . Also, the width W of each solid line 1 does not necessarily have to be the same in one solid pattern 3 , and can be selected according to the shape of the end of each solid pattern 3 . This makes it possible to express the edges of the solid pattern 3 more smoothly.

<Example 1>
An example in which UV fluorescent ink was used to create the latent image portion of the anti-counterfeiting medium is shown below.

Urite Natural F (registered trademark) manufactured by Nippon Paper Industries Co., Ltd. was used as the base material. The coat can be arbitrarily selected from the matte type, the gloss type, etc., but the matte type was used in this embodiment.

<Formation of latent image>
On this base material, a pattern layer was formed with UV fluorescent ink, and then a protective layer was formed with overcoat varnish by offset printing to form a latent image pattern.

As the fluorescent ink, UV fluorescent medium Y manufactured by T&K TOKA Co., Ltd. was used for the yellow fluorescent ink, and UV fluorescent medium B manufactured by the same company was used for the blue fluorescent ink.

As the overcoat varnish, UV161 Medium S manufactured by the same company was used. Matte varnish, gloss varnish, etc. can be arbitrarily selected, but the gloss type was used in this embodiment.

In order to investigate how the hiding power of the latent image under ambient light and the visibility under UV light change depending on the difference in print design, we printed a chart pattern with the print design changed as follows. formed.

For the pattern layer, the fine lines have line widths of 0.1 mm, 0.2 mm, 0.3 mm, and 0.5 mm, and a set of five fine lines arranged at a pitch twice the line width, In addition, for comparison with the solid line, the chart shows the line widths of 0.1 mm, 0.2 mm, 0.3 mm, 0.5 mm, 0.7 mm and 1.0 mm. formed.

Also, a chart was formed using a plate whose halftone dot density was changed from 10% to 100% in increments of 10%.

As for the overcoat layer, three types of printing plates having halftone dot densities of 40%, 60% and 100% were used for comparison.

<Observation of latent image>
With respect to the chart pattern obtained as described above, the visibility of the visualized latent image was visually observed under UV light with a wavelength of 365 nm, and the hiding property was visually observed under visible light.

With respect to the visibility, no change in luminance was observed in the halftone dot density range of 60% to 100% of the pattern layer. In addition, no change in luminance was observed when the dot density of the overcoat layer was 40%, 60% or 100%.

Regarding the set of fine lines, no difference in emission luminance was observed between five lines with a line width of 0.1 mm arranged at a pitch of 0.2 mm and a single line with a line width of 1.0 mm.

Regarding the concealability, the formation of the overcoat layer makes it difficult to visually recognize any of the above picture layer patterns, but it is possible to visually check the fine line width in the range of 0.1 mm or more and 0.5 mm or less. Concealment was ensured to the extent that it could not be done.

From the above, rather than expressing the halftone dot density of the fluorescent ink at 60%, thin lines with a line width of at least 0.1 mm or more and 0.5 mm or less are spaced at intervals of the same size, that is, the existing density of the fluorescent ink is 50%. By repeatedly arranging such that , a latent image necessary for an anti-counterfeiting medium having both concealability under ambient light and visibility under UV light could be obtained.

<Example 2>
An example in which infrared fluorescent ink was used to create the latent image portion of the anti-counterfeiting medium is given below.

Urite Natural F (registered trademark) manufactured by Nippon Paper Industries Co., Ltd. was used as the base material. The coat can be arbitrarily selected from the matte type, the gloss type, etc., but the matte type was used in this embodiment.

<Formation of latent image>
On this base material, a pattern layer was formed using infrared fluorescent ink, and then a protective layer was formed using overcoat varnish by offset printing to form a latent image pattern.

SG-YS from Nemoto & Co., Ltd. is used as the fluorescent ink, and UV161 medium S from T&K TOKA Co., Ltd. is used as the medium. prepared.

Also for the overcoat varnish, UV161 medium S was used. Matte varnish, gloss varnish, etc. can be arbitrarily selected, but the gloss type was used in this embodiment.

In order to investigate how the opacity of the latent image under ambient light and the visibility under infrared light change depending on the difference in print design, chart patterns with the following changes in print design were prepared. Print formed.

For the pattern layer, the fine lines are 0.1 mm, 0.2 mm, 0.3 mm and 0.5 mm.
A set of five fine lines with a line width of 0.1 mm, 0.2 mm, 0.3 mm, 0.3 mm, and 0.1 mm, 0.2 mm, 0.3 mm, and 0.3 mm for comparison with the solid line. A chart was formed by arranging each one of 5 mm, 0.7 mm and 1.0 mm independently.

Also, a chart was formed using a plate whose halftone dot density was changed from 10% to 100% in increments of 10%.

As for the overcoat layer, three types of printing plates having halftone dot densities of 40%, 60% and 100% were used for comparison.

<Observation of latent image>
Regarding the chart pattern obtained as described above, the visibility of the visualized latent image was confirmed by an infrared camera having a sensitivity in the vicinity of a wavelength of 800 nm, and the hiding property was confirmed by visual observation under visible light.

With respect to the visibility, no change in luminance was observed in the halftone dot density range of 60% to 100% of the pattern layer. In addition, no change in luminance was observed when the dot density of the overcoat layer was 40%, 60% or 100%.

Regarding the set of fine lines, no difference in emission luminance was observed between five lines with a line width of 0.1 mm arranged at a pitch of 0.2 mm and a single line with a line width of 1.0 mm.

Regarding the concealability, the formation of the overcoat layer makes it difficult to visually recognize any of the above picture layer patterns, but it is possible to visually check the fine line width in the range of 0.1 mm or more and 0.5 mm or less. Concealment was ensured to the extent that it could not be done.

From the above, rather than expressing the halftone dot density of the fluorescent ink at 60%, thin lines with a line width of at least 0.1 mm or more and 0.5 mm or less are spaced at intervals of the same size, that is, the existing density of the fluorescent ink is 50%. By repeatedly arranging so as to obtain a latent image necessary for an anti-counterfeiting medium having both concealability under ambient light and visibility under infrared light.

<Example 3>
In order to perform a more quantitative evaluation, each set of halftone dots and fine lines was printed with UV fluorescent ink, and the amounts of light emitted were compared using a spectroscope.

Urite Natural F (registered trademark) manufactured by Nippon Paper Industries Co., Ltd. was used as the base material. The coat can be arbitrarily selected from the matte type, the gloss type, etc., but the matte type was used in this embodiment.

<Formation of latent image>
On this base material, a pattern layer was formed with UV fluorescent ink, and then a protective layer was formed with overcoat varnish by offset printing to form a latent image pattern.

As the fluorescent ink, UV fluorescent medium B manufactured by T&K TOKA Co., Ltd., which emits blue fluorescence, was used.

As the overcoat varnish, UV161 Medium S manufactured by the same company was used. Matte varnish, gloss varnish, etc. can be arbitrarily selected, but the gloss type was used in this embodiment.

In order to investigate how the emission intensity, which affects the visibility of the latent image under UV light, changes depending on the difference in print design, the following two types of pattern layers were formed by printing.

First, as an embodiment of the present invention, the short side D of the thin line 2 is 0.4 mm, the distance between the thin lines adjacent in the tangential direction of the solid line is 0.74 mm, that is, the fluorescent ink density of the solid line 1 is about 35%. A pattern of a solid line 1 was formed by arranging fine lines as shown.

As a comparative example for the present invention, a pattern having the same solid line width as the solid line 1 was formed using a plate having a dot density of 60%.

As for the overcoat layer, three types of printing plates having halftone dot densities of 40%, 60% and 100% were used for comparison.

<Observation of latent image>
For the two patterns obtained as described above, an emission spectroscopic spectrum for UV light was measured using a USB2000 spectrometer manufactured by Ocean Photonics Co., Ltd. with the measurement area set equal and constant. The results are shown in FIG.

The emission intensity was obtained by integrating the intensity at wavelengths of 430 nm to 490 nm corresponding to blue emission in the obtained spectrum. As a result, the luminous intensity of the solid line portion of the set of fine lines according to the present invention was 34.5 μW/cm ² /nm, and the luminous intensity of the solid line portion of halftone dots as a comparative example was 30.6 μW/cm ² /nm. Got.

From the above, when performing transparent printing with fluorescent ink on coated paper, it is better to express with a set of fine lines than to express the halftone dot density at 60%, even though the fluorescent ink printing area ratio is as low as 35%. However, since a higher emission intensity can be obtained, the concealability under ambient light is maintained by the low printing area ratio, and the visibility at the time of visualization is more reliable due to the high emission intensity. It was confirmed that a latent image for anti-counterfeiting medium can be obtained.

1 solid line portion forming the latent image portion 2 thin line forming the solid line portion 3 solid pattern portion forming the latent image portion

Claims (6)

An anti-counterfeiting medium comprising a printed layer comprising a background portion and a latent image portion formed on a substrate, wherein the latent image portion is formed of at least one type of fluorescent ink having fluorescence and is constant A forgery prevention medium characterized by comprising a set of thin lines arranged with a line width of , and expressing a solid line or solid pattern. the fluorescent ink of the oxidative polymerization curing type, wherein the printed layer is composed of at least one nearly white pigment that emits light of the same or different wavelength when irradiated with light of a predetermined wavelength, and a colorless transparent base ink;
2. The anti-counterfeiting medium according to claim 1, wherein the anti-counterfeiting medium comprises a laminate of varnish having the same color as the fluorescent ink. 3. The anti-counterfeit medium according to claim 1, wherein the printed layer is formed by offset printing. The solid line has a short side length shorter than the solid line width, a width of 0.05 mm or more and 0.5 mm or less, preferably 0.1 mm or more and 0.5 mm or less, and a long side length of 100 times or less of the width. the long side in the normal direction of the solid line, the short side in the tangential direction of the solid line, and the interval between adjacent thin lines is equal to the length of the short side of the thin line 4. The anti-counterfeiting medium according to any one of claims 1 to 3, characterized by comprising: 5. The anti-counterfeiting medium according to claim 1, wherein the solid pattern is formed by forming the solid line so that the ink density is 40% or more and 90% or less, and a plurality of such solid lines are arranged side by side. . The varnish is made of matte varnish, gloss varnish, or a mixture thereof, etc., and is formed by a solid plate on the entire surface in which halftone dots are present in a range of 40% or more and 100% or less, regardless of the printing pattern of the fluorescent ink. The forgery prevention medium according to any one of claims 1 to 5.

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