JPH09156268A - Sheet for preventing forgery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable determination of authenticity by making confidential information emit fluorescence by black light, although the confidential information can not recognized visually under visible light, and also to enable determination of the authenticity by a simple method without using ultraviolet irradiation equipment. SOLUTION: A sheet for preventing forgery which has confidential information such as a character, a numeral, a figure, a sign or a pattern having transparency under visible light and formed of a transparent ink film emitting fluorescence under ultraviolet irradiation and of which the transparent ink film contains microcapsules of leuco dye crystal violet lactone.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-counterfeit sheet capable of determining authenticity, and more specifically, a certificate sheet such as banknotes, securities, cash vouchers, checks, tickets, and cards such as ID cards and credit cards. A sheet for use as a base material for forgery, and even if these sheets are forged or altered by a color copier, digital color printer, etc., they can be easily discovered by a simple method. Regarding prevention sheet.

[0002]

2. Description of the Related Art In recent years, due to the rapid improvement in performance of digital color printers and color copying machines, color reproducibility, resolution,
The range of preparation such as light and dark copy density is remarkably improved and expanded, and it is difficult to identify a falsified or counterfeit product at a glance. Therefore, as an example of measures for preventing such forgery and alteration, various technologies relating to an anti-counterfeit sheet formed by printing secret information on the sheet surface with fluorescent ink have been proposed. According to this technique, it is difficult to visually recognize the secret information printed with the fluorescent ink under the visible light, but by irradiating the sheet with ultraviolet rays (black light), the secret information is protected. It is made visible by making it fluorescent so that the authenticity of the seat can be determined.

[0003]

However, according to such a conventional anti-counterfeit sheet using a fluorescent ink, there is no authenticity judging method other than irradiating a black light for the confirmation of secret information. If so, the authenticity can be judged only in the place where the ultraviolet irradiation device is installed,
If the device fails, the authenticity cannot be determined.

Therefore, according to the present invention, based on such a conventional forgery prevention method using a black light, the secret information cannot be visually recognized under visible light, but the black light fluoresces the secret information to verify the authenticity. An object of the present invention is to provide a sheet for preventing forgery, which can judge whether or not it is authentic and can judge the authenticity by a simple method without using an ultraviolet irradiation device.

[0005]

DISCLOSURE OF THE INVENTION As a result of intensive studies conducted by the present inventor in view of the above problems, a leuco dye crystal violet lactone (hereinafter abbreviated as CVL), which is conventionally known in the field of pressure-sensitive copying paper, is used. In the microcapsules, the conditions such as the composition ratio of the conventional capsule wall material and the core material, the thickness of the wall material, etc. are not particularly changed, and the CVL concentration in the organic solvent of the capsule core material is measured by the conventional pressure-sensitive copying paper. The concentration is set higher than the applicable concentration (around 2% by weight), and the microcapsule-containing oil-based ink production technique already developed by the present inventors (Japanese Patent Laid-Open No. 7-216273) and other techniques are used. When a transparent ink containing microcapsules in a dispersed state is used to form an ink film on the surface of a sheet substrate, it is difficult to see under the visible light with the naked eye. The capsule core material is fluorescent by preparative, its fluorescence is visible to the naked eye it through the capsule wall film,
As a whole, they have found that the entire ink film is uniformly fluorescent and visible, and have conceived the present invention.

That is, the anti-counterfeit sheet of the present invention is
It has secret information such as letters, numbers, figures, symbols, patterns, etc. formed on a predetermined part of the surface of the sheet base material with a transparent ink film that is transparent under visible light and fluoresces under ultraviolet irradiation. The transparent ink film contains CVL microcapsules.

The anti-counterfeit sheet of the present invention utilizes the fluorescence phenomenon of an organic solvent containing CVL in a specific concentration range against black light, and is manufactured by the encapsulation technique known in the field of pressure-sensitive copying paper. CVL
By printing secret information with transparent ink that contains microcapsules in a dispersed state in the ink vehicle, the secret information is difficult to see under the visible light with the naked eye, but it is uniformly illuminated by black light. To do. further,
When the secret information portion is brought into contact with a color-developing sheet (developing agent application sheet) of pressure-sensitive copying paper which has been conventionally used and rubbed while being pressed, CVL is transferred to the developer and the coloring sheet is colored. Therefore, the authenticity can be determined.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the structure of the anti-counterfeit sheet of the present invention will be described in detail with reference to the preferred embodiments. First, a method for preparing a CVL microcapsule-containing ink for forming a transparent ink film will be described. To illustrate.

[Method for preparing ink containing CVL microcapsules] A styrene-maleic anhydride copolymer was dissolved together with a small amount of sodium hydroxide, and 200 parts of an aqueous solution containing 5% by weight of this solution was added to 194 parts of alkylnaphthalene to obtain CVL6. Part was dissolved by heating and dispersed to obtain an emulsion having an average particle size of 1.8 μm. Next, 60 parts of melamine-formalin prepolymer was added to this emulsion, and the system was stirred at a temperature of 75 ° C. for 2 hours to give CVL microcapsules 5.
A 0% by weight aqueous solution was prepared. Furthermore, this aqueous solution 80
Part, 20 parts of glycerin, and 20 parts of UV-curing varnish were added, and while removing water by a method combining vacuum distillation under predetermined conditions, 30 parts of a preparation agent for printing ink was further added,
Disperse the microcapsules in the vehicle to form CVL
An ink containing microcapsules was prepared.

The CVL microencapsulation method in the present invention is not limited to the exemplified method, and may be a conventionally known encapsulation technology in the field of pressure-sensitive copying paper such as in situ method and interfacial condensation polymerization method. Also, the capsule particle size, the thickness of the capsule wall material, etc. may be similar to those used in conventional pressure-sensitive copying paper, and are not particularly limited. However, the concentration of CVL contained in the organic solvent of the microcapsule core substance must be at least 2% by weight in order to fully exhibit the fluorescence function, while the saturated concentration of the microcapsule core substance relative to the organic solvent (at room temperature). ), CVL precipitates, and the fluorescent function cannot be efficiently extracted. Furthermore, from the relationship with the solubility in the organic solvent that constitutes the core substance, or the cost, etc., 5% by weight
Is not preferable, and therefore a range of 2 to 5% by weight is necessary, preferably 2.5 to 3.5% by weight, and more preferably around 3% by weight.

Next, regarding the technique relating to the method of preparing an ink for CVL microcapsules, the exemplified method is based on the technique for producing an oil-based ink containing microcapsules of the present inventor (JP-A-7-216273). In the above, the method is not limited to this method, and a conventionally known method for preparing an ink may be used. However, the exemplified method having good capsule dispersibility in the vehicle is most suitable for the preferable printing performance of the confidential information or for the fluorescent information to be uniformly and uniformly fluorescently emitted when the black light is irradiated. Incidentally, the transparent ink film in the present invention, even when the ink itself is somewhat colored,
What is necessary is that the ink film formed on the surface of the sheet is transparent to the extent that it is difficult to visually recognize it.

An example of the anti-counterfeit sheet according to the present invention will be described below in detail as a promissory note.
2 is a schematic perspective view of the promissory note, FIG. 2 is a sectional view taken along line XX of FIG. 1, FIG. 3 is a schematic explanatory view of an authenticity determination method using a black light for the promissory note of FIG. 1, and FIG. FIG. 1 is a schematic explanatory diagram of an authenticity determination method using a color developing sheet for the promissory note of FIG. 1, and FIG. 5 is a schematic explanatory diagram of a secret information state transferred to the developer application surface of the color developing sheet of FIG. .

First, as shown in FIGS. 1 and 2, the promissory note 1 of this embodiment has a surface of a sheet base material 2 having predetermined information A such as an amount column, a payee information column, and a payer information column. The secret information B consisting of "# 123 *" composed of numbers and symbols printed with the CVL microcapsule-containing transparent ink exemplified above is applied to a predetermined portion of No. 3 by a usual printing means. It is a thing. Since this secret information B is composed of a transparent ink film, under visible light,
It is very difficult to see with the naked eye.

There are two types of authenticity determination methods for this promissory note 1. That is, as shown in FIG. 3, when the surface 3 of the promissory note 1 is irradiated with black light (wavelength 370 nm) by the ultraviolet irradiation device E, the secret information B is fluorescent and "# 123 *" becomes visible. . Further, when the ultraviolet irradiation device is not used, as shown in FIG. 4, a color-developing sheet S (color developer coating sheet) of a commercially available pressure-sensitive copying paper is used.
While contacting the confidential information B, the confidential information B is transferred to the developer application surface 4 of the coloring sheet S by pressing and rubbing with the bottom of the writing instrument P, as shown in FIG. The mirror image B ′ of “# 123 *” is formed by coloring.
In addition to the present embodiment, the secret information B may be a simple figure such as a rectangle or a circle, and in this case, the coloring sheet may be simply rubbed to check the presence or absence of the coloring.

[0015]

As described above, the anti-counterfeit sheet of the present invention contains CVL microcapsules manufactured by the encapsulation technique known in the field of pressure-sensitive copying paper in a dispersed state in the ink vehicle. Since the confidential information is printed with the transparent ink formed as described above, the confidential information is difficult to be visually recognized by the naked eye under visible light, but uniformly fluoresces when irradiated with black light. Furthermore, when the confidential information section is brought into contact with a color-developing sheet of pressure-sensitive copying paper which has been conventionally used and is rubbed while being pressed, the color-developing sheet develops color. The authenticity can be easily determined even in a place where the device is not operated or when the device fails.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of a promissory note that is an example of the anti-counterfeit sheet of the present invention.

FIG. 2 is a sectional view taken along line XX of FIG.

FIG. 3 is a schematic explanatory diagram of an authenticity determination method using black light for the promissory note of FIG. 1;

FIG. 4 is a schematic explanatory diagram of an authenticity determination method using a coloring sheet for the promissory note of FIG. 1;

FIG. 5 is a schematic explanatory view of a secret information state transferred onto the surface of the color development sheet of FIG.

[Explanation of symbols]

 1 Counterfeit Prevention Sheet 2 Sheet Base Material 3 Sheet Base Material Surface A Predetermined Information B Confidential Information B'Mirror Image of Confidential Information E Ultraviolet Irradiation Device S Coloring Sheet

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location G03G 21/04 G03G 21/00 554

Claims (1)

[Claims] 1. A letter, number, figure, symbol, pattern or the like formed on a predetermined portion of the surface of a sheet substrate with a transparent ink film that is transparent under visible light and that emits fluorescence under ultraviolet irradiation. A forgery prevention sheet, which is a sheet having secret information, wherein the transparent ink film contains microcapsules of leuco dye crystal violet lactone.