CZ104492A3 - method of security printing - Google Patents

Abstract

This protective element for printing securities consists of at least two parts independently printed by printing colours the colour of which in visible areas looks identical, however in the bordering area of the visible and infrared spectrum they are different which is evident during investigation through a dark red filter or electronically.<IMAGE>

Description

The invention falls within the field of the printing industry, in particular the printing of securities, with a view to preventing their illegal reproduction. Its focus is on the sphere of interest, the Federal Ministry of the Interior and the State Bank of Czechoslovakia.

Description of the prior art

The main protection against counterfeiting is the still complex graphic design of the original (image and font), highly demanding for accurate registration of individual colors, the use of gravure printing, transparencies, metal fibers incorporated into paper, as well as the use of special paper. While selecting pigments for printing securities, especially banknotes, the main care is given to color fastness to light, abrasion resistance, health safety, constant purity of color shade and yield of individual production batches, a number of physical-chemical parameters are evaluated, while rapid development modern reproduction methods, especially xerocopy systems, did not significantly affect the choice of pigments for printing securities. The pigments used for banknote printing are of the best quality and there was no reason to look for a replacement.

Modern xerographic copiers capture the image of the original with a laser beam, which allows you to faithfully reproduce even the most complex graphics with hairlines completely automatically in seconds. There is no need for laborious production of printing blocks for individual basic inks, need for printing presses, color preparation and other work requiring solid theoretical and practical knowledge and technical equipment. Even a layman can make a perfect copy on a xerographic copier after a short training in the machine operator.

2. SUMMARY OF THE INVENTION

The present invention is based on a method of printing securities, in particular banknotes, shares, bonds, passports, identity cards and driving licenses, technical certificates and other certificates, characterized in that at least one is used for printing. ϊ pigment (dye or colored lacquer), which in the borderline of the visible spectrum; exhibits a sudden rise or fall in the remission curve, or a combination of at least one pair of printing mixtures, one of which contains such a pigment, and which exhibits the same spectral reflectance (remission) in the visible range of the spectrum, i.e. saturation, but in the peripheral part of the spectrum R, the course of remission is different, i. There is a clear contrast, which makes it not only difficult: counterfeiting, and at the same time making it possible to quickly detect counterfeit.

Both the prior art machinery and the printing technique can be used to realize the printing of the present invention. The only difference is that it is; special pigments are used whose spectral reflectance (remission) is characterized by a sudden change in the visible spectrum at the boundary of the visible spectrum (figure 1, 2), whereby one or more of these pigments can be used for printing, or The color shade of two printing compositions whose color tones appear identical in the visible area, but show a difference in the remission value ZS, which is a measure of the contrast that both mixtures appear when viewed through a selective color filter, at the edge of the visible spectrum. In this case, it is preferable to use a printing ink containing type A pigment to print one part of the graphic pattern / image and / or font and use a type B pigment in the printing mixture for the other part of the image and / or font, the pigment concentration of both types being : chosen in individual printing mixtures so that the set hue and saturation of printing of both parts of the image and font appear in the visible area the same.

In this case, the color photocopy or xerox copy reproduces both parts of the image or text with the same color shade, whose emission values are exactly the same throughout the spectrum, including the peripheral areas of its visible part, even using any color filter, because in xerographic. In contrast, the original, seen through a dark red filter, exhibits both portions of the image or font in contrast, one portion light to white, the other dark to black.

If, for example, an ink containing type A or C pigment is used to indicate a banknote series, while the number> of the banknote is printed with ink containing type 3 or D pigment, the entire designation will appear visually the same shade but under; the dark red filter will only show the number marking, while the series marking will not be visible, it will disappear. However, both color marking and color xerox copy are both about marking, ie the series marking and number are equally visible. the misleading conclusion that the copy 'fully corresponds to the original.

It can be seen from the graphs in Figs. 1 and 2 that, while in the visible part of the spectrum, the remission pattern of all the black pigments is the same, the wavelength starts at 700 nm, the A and C pigments start to rise. is 70% (Fig. 1), respectively. 62% (Fig.2). This difference is noticeable visibly below the dark red filter, or may be. a simple device consisting of a light source, a dark red filter and a photocell was used for detection. Clarification of drawings

The course of spectral reflectance (remission) of a given surface (on color) relative to a white standard which is a barium sulphate (BaSO4) or oxide plate; magnesium (MgO), is expressed by a remission curve, which represents the remission spectrum of the sample. The remission is given in relative percentages, with the standard remission at each wavelength being 100.

R

UR = vz. 100 vz - ^R smear - remission of sample vz

R = standard remission

St

Fig. 1 Semis spectra of pigments:

A —-— Anthraquinone Black, according to the C.olour Index:

0.1. Pigment Black 20 chemical structure or classification not given

B ............... Aniline Ser

WHOSE. 50550 C.I. Oxidation Base 1

CI Pigment, Black 1 chemical classification: azine α, »o ^! ó ^r ó ^r ó

X - acid radical, probably chromate

Fig. 2 Semis spectra: pigments:

σ ---— antimony black, antimony simik

Sb ₂ S ₃

D ——— soot

<e

- 5 Examples

Example no

The base concentrate for printing paste preparation may have the following composition:

Perm resin hardener 50% synthetic alkyd 25% pigment 25%

After spreading on a friction mill, it is diluted: 25% pigment concentrate 7.0% wax paste 3% aluminum hydrate 3% printing oil 3 $ siccativ / 0.5% Co / 3% varnish 18%

100% Ex.

The mixture is rubbed in the usual manner on a three-cylinder

Example No. 2

Printing ink of the customary composition in which anthraquinone black is used as pigment

Example 3

Printing ink of conventional composition in which antimony black is used as pigment

Example 4

Printing ink of a conventional composition in which a pigment with a low remission in the infrared region, such as aniline black or carbon black, is used as the pigment

Example 5

Pair of printing inks of the usual composition and of the same hue and saturation, one of which contains a pigment of the type shown in Example 2 or 3, while the other mixture contains a pigment of the type shown in Example 4 · One part of the image and / or font is printed a composition comprising a pigment of the type shown in Example 2 or 3, a second portion of the image and / or font, a composition with a pigment of the type shown in Example 4.

Claims (2)

1. A method of printing securities, in particular banknotes, shares, bonds, passports, identity cards and driving licenses, technical certificates as well as other certificates, characterized by:. to print them. at least one pigment (dye or colored lacquer) which exhibits a sudden increase in the chest area of the visible spectrum ^? or decrease in the remission curve. 2. A method of printing securities according to claim 1, characterized in that a combination of at least one pair of printing compositions is used for printing, one of which comprises the pigment of point 1 as an active component, while the other comprises the pigment (s) with significantly different Both mixtures show in the visible part of the spectrum: the same course of remission, ie the eye of the observer appears to have the same color shade and saturation, but in the border area of the visible spectrum both mixtures show the course of remission: different, ie they show a distinct contrast.