ES2218507T3 - PRINTING PROCEDURE OF LATENT IMAGES. - Google Patents

Abstract

Printing a relief pattern on a printed document comprises printing at least one pattern of axial lines with a thick layer of ink containing a polymerizable material and a polymerization accelerator, and activating the polymerization accelerator by supplying energy.

Description

Image printing procedure latent.

Field of the Invention

The invention relates to the procedures intended to prevent fraudulent reproduction of documents authentic, such as identification documents, banknotes bank, credit cards, etc.

The invention relates more particularly to the application of a "latent image" on the surface of Documents of this type.

In the printing sector, it is understood by "latent image" an image that cannot be detected in "normal" observation conditions, that is when look at the document presenting this latent image under a angle perpendicular to its surface while the images latent only appear when the document is viewed under a defined angle

In print, this effect is obtained by printing of regular reliefs, obtained in particular by means of a support structure in light relief (sweet size print). The latent image appears by a simple parallax effect when they observe the reliefs from a point located near its axis of extension (or perpendicular to it).

One of the advantages of these latent images is that it is impossible to reproduce them from a simple copy (for photocopy or electronic scanning) of an authentic document.

State of the art

Numerous procedures have already appeared for Get this latent image effect. As specified previously, you can use the sweet size (intaglio) to mark reliefs on the document support.

US 5,199,744 describes a procedure in which the reliefs are made by engraving on relief.

US 5,582,103 and US 4,033,059 describe a procedure in which the support is marked with reliefs of which either the highlighted parts, or the parts Discounts are printed below.

All these procedures from the simplest at the most complex, they suffer from a disadvantage from the point of view of the arrangement of the relief required to obtain the effect of latent image. The realization of this relief implies in effect at least one operation with matrix, and also an alignment perfect inking with the reliefs produced.

Summary of the Invention

An attempt was made to perform a procedure that allow to obtain the necessary reliefs for the production of a latent image on any support.

The object of the invention is that the Image obtained is impossible to reproduce.

Another object of the invention is that the procedure is easy to use.

The object of the invention is constituted by a Embossed printing procedure, for printing images latent among others, on a document, which includes the following operations:

to)

select a substratum,

b)

select one ink containing a polymerizable material and a polymerization accelerator,

c)

select a printing procedure that allows ink transfer in thick layer,

d)

print at less a motif formed by spaced lines that extend according to at least one preferred axis with this ink with the help of this procedure, and

and)

Activate the polymerization accelerator by ad hoc energy input so that the ink polymerizes in a thick layer.

According to an advantageous embodiment, the motive comprises an area that has a first network of lines that extends along a preferred axis and at least a second zone which presents a second network of lines that extends along an axis different from the preferred axis, so that an image is produced latent on the document.

In this procedure, operation b can be preceded by a preliminary impression. According to a variant of embodiment, operation b may also be preceded by the application of a preliminary element such as a hologram.

The printing procedure is selected preferably from among the following procedures: silkscreen, flexography, heliogravure.

Advantageously, the accelerator of polymerization is activated by an energy contribution by electromagnetic radiation, selected from the following: Infrared, UV, microwave.

Other particularities and advantages of the invention will become apparent from the following description of particular embodiments of the invention, making reference to the attached plans, in which:

Figure 1 is a perspective view, with exaggerated dimensions of a substrate printed according to the method of the invention

Figure 1 shows how the procedure of the invention allows to realize a classic latent image.

A first reason A consisting of lines spaced 1 is formed in relief by the procedure of the invention on a substrate 2.

Embossed lines 1 extend along an axis preferred α.

A second is applied on the same substrate motif B, also consisting of spaced lines 3.

Embossed lines 3 extend according to another preferred axis?, clearly differentiated from?, even perpendicular to it.

By parallax effect, an observer who observes the document along the preferred axis? will have the impression of that reason A is less dense than reason B. The interval e between two lines l appears in effect throughout its width (typically, the interval e has a width of the order of 0.1 to 0.2 mm, of same order as the width of lines 1 and 3), while found partially masked between lines 3. The phenomenon it is obviously reversed when the document is observed according to the another preferred axis?.

To obtain the particular relief of device of the invention, an ink containing is used, in addition to pigments and a certain amount of solvents, some materials susceptible to polymerization ("varnishes", monomers), which are deposited on the appropriate substrate using a printing procedure that allows the transfer of a thick ink layer and the use of large pigments dimensions.

Among these procedures, one can cite, typically, screen printing, flexography and heliogravure.

Normal printing practice requires that, for obtain a maximum optical effect of the pigments dispersed in the ink, the ink layer is as thin as possible, and by Both virtually two-dimensional. A thin layer also offers, In general, the advantage of adhering better on the support.

This result is generally obtained by Classic drying

Completely opposed to this practice, in the procedure of the invention, a brief drying is carried out with intense energy contribution, so that you get a almost instantaneous polymerization of the ink layer, practically No volume reduction Therefore, some lines are obtained 1, 3-dimensional extension (of the order of a dozen \ mum). This energy contribution can be made in particular by increasing the temperature, by radiation Electromagnetic, by electron beam.

Moreover, the relief motifs A and B they can be performed above a classic printed motif, even about data that authenticates the document, such as an image holographic, which, by its presence alone (although it is a gross counterfeit) may be enough for an observer Unattentive deduce the authenticity of a document. It will be observed that the process of the invention also allows the identification and authentication of the document through the touch, giving the relief to the document a tactile sensation different.

Claims (7)

1. Embossing procedure for printing on a document characterized in that it comprises the following operations:

to)

select a substrate (2),

b)

select one ink containing a polymerizable material and a polymerization accelerator,

c)

select a printing procedure that allows ink transfer in thick layer,

d)

print at minus one motif (A, B) formed by spaced lines that are they extend along at least one preferred axis with this ink with help of this procedure,

and)

Activate the polymerization accelerator by ad hoc energy input so that the ink polymerizes in a thick layer.

2. Embossing method according to claim 1, characterized in that the motif comprises an area that has a first network of lines that extend along a preferred axis and at least a second area that has a second network of lines that extend along an axis different from the preferred axis, so that a latent image is produced on the document. 3. Embossing method according to any of claims 1 and 2, characterized in that operation b is preceded by a preliminary printing. 4. Embossing method according to any one of claims 1 and 2, characterized in that operation b is preceded by the application of a preliminary element. 5. Embossing method according to claim 4, characterized in that the preliminary element is a hologram. 6. Embossing method according to any of the preceding claims, characterized in that the thick layer printing method is selected from the following procedures: screen printing, flexography, heliogravure. 7. Embossing method according to any of the preceding claims, characterized in that the polymerization accelerator is activated by an energy input by electromagnetic radiation, selected from the following: infrared, UV, microwave.