Security sheet including an iridescent security mark

Abstract

A security sheet including an iridescent security mark observable on the surface of the sheet, the mark having at least one zone presenting an iridescent effect, the zone being colored in normal observation with the naked eye and including iridescent pigments that are practically colorless in normal observation and that present an iridescent effect visible only in oblique observation.

Claims

1. A security sheet comprising an iridescent security mark observable on a surface of the sheet, said mark comprising at least two zones, each presenting an iridescent effect, said zones having coloration observable by reflected light in normal observation with an unaided eye, said coloration making said zones perceptible in normal observation, and at least one of the zones including iridescent pigments that are intrinsically colorless in normal observation and that present an iridescent effect that is visible only in oblique observation, each of said zones including firstly a dye, said dye being such that said zones have the same hue, and secondly iridescent pigments, said pigments presenting in oblique observation iridescent effects that differ from one of the zones to another of the zones.

2. A security sheet according to claim 1, said two zones presenting iridescent effects that are visible only in oblique observation.

3. A security sheet according to claim 2, said two zones including iridescent pigments that are practically colorless in normal observation and that present iridescent effects that are visible only in oblique observation.

4. A security sheet according to claim 1, said zones being observable simultaneously.

5. A security sheet according to claim 1, said zones being juxtaposed.

6. A security sheet according to claim 1, wherein one of said zones is within another of said zones.

7. A security sheet according to claim 1, said zones being partially superposed.

8. A security sheet according to claim 1, each of said zones including a fluorescent compound, said compound differing from one zone to the other.

9. A security sheet according to claim 1, said at least one mark further including at least one tactile-effect element comprising a polyurethane first tactile effect present in one of the zones and an iridescent-pigment second tactile effect present in another of the zones.

10. A security sheet comprising an iridescent security mark observable on a surface of the sheet, said mark comprising at least two zones, each presenting an iridescent effect, said zones having coloration observable by reflected light in normal observation with an unaided eye, said coloration making said zones perceptible in normal observation, and at least one of the zones including iridescent pigments that are intrinsically colorless in normal observation and that present an iridescent effect that is visible only in oblique observation, said at least one mark further including at least one tactile-effect element comprising a polyurethane first tactile effect present in one of the zones and an iridescent-pigment second tactile effect present in another of the zones.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) The invention can be better understood with the help of the following Examples 1 to 8 of the invention and corresponding accompanying FIGS. 1 to 10.

(2) FIGS. 1, 3, 5, 7, and 9 are face views of security sheets of the invention in normal observation.

(3) FIGS. 2, 4, 6, 8, and 10 are views of security sheets of the invention in oblique observation.

EXAMPLE 1

(4) On a sheet of security paper having a weight of 100 g/m.sup.2, a security mark was printed by photogravure, the mark being in the form of a strip, with a void being left having the form 10, by applying an aqueous ink comprising a blue dye (blue Cartarene CBR 500 from the supplier Clariant) and iridescent pigments based on mica/TiO.sub.2 (Gold Iriodin 205 from the supplier Merck) presenting a gold iridescent effect that is visible only in oblique observation. The ink may contain other conventional additives such as a curing agent, an anti-foaming agent, binders (a hydrosoluble binder such as polyvinyl alcohol (PVA) and/or latex type binders such as a polyurethane), or indeed a viscosity regulator.

(5) The ink contained 44.8 grams (g) of iridescent pigments and 0.05 g of blue dye per 100 g of the ink composition by dry weight. The iridescent composition was deposited by photogravure at 12 g/m.sup.2, with the iridescent pigment being deposited at 5.4 g/m.sup.2; the dye was deposited at 0.11% by dry weight relative to the iridescent pigments.

(6) That produced a mark that appeared to be uniformly blue in normal observation (at an angle of 90 degrees relative to the plane of the region), with the pattern 10 appearing in negative (no ink) and with a gold iridescent effect appearing only in oblique observation.

EXAMPLE 2

(7) On a sheet of security paper 1 having a weight of 100 g/m.sup.2, a security mark 2 was photogravure printed so as to produce a first zone 2a in the form of a strip while leaving a void in the form of a 1, by applying an aqueous ink A1 comprising a green dye (green Cartarene CVB from the supplier Clariant) and iridescent pigments based on mica/TiO.sub.2 (Blue Iriodin 225 from the supplier Merck) presenting a blue iridescent effect that is visible only in oblique observation, and also producing a second zone 2b in the form of a strip juxtaposed with the first strip, while leaving two voids side by side each having the form of a 0 and located beside the 1 of the zone 2a, by applying an aqueous ink B1 comprising said green dye and iridescent pigments based on mica/TiO.sub.2 (Lilac Iriodin 219 from the supplier Merck) presenting a violet iridescent effect that is visible only in oblique observation. The iridescent pigments themselves are practically colorless in normal observation. The inks may contain other conventional additives such as a curing agent, an anti-foaming agent, binders (a hydrosoluble binder such as polyvinyl alcohol (PVA) and/or latex type binders such as a polyurethane), or indeed a viscosity regulator. Each of the inks A1 and B1 comprised 44.8 g of iridescent pigments and 0.03 g of green dye per 100 g of ink composition by dry weight. The hue of the inks was adjusted by colorimetric measurements and by Gardner brightness measurements. The iridescent compositions A1 and B1 were deposited on the sheet by photogravure at 12 g/m.sup.2 (per composition), the iridescent pigments being deposited at 5.4 g/m.sup.2 and the dye at 0.005 g/m.sup.2; there was thus about 0.1% by dry weight of dye deposited relative to the iridescent pigments.

(8) The colorimetric data for the mark made up of the two strips is as follows:

(9) TABLE-US-00001 Gardner brightness at 75 degrees 28.5 CIE whiteness 40.8 ISO whiteness 70.4 Yellow degree 10.79 L 91.34 a* 5.87 b* 8.06

(10) A mark was thus obtained that was made up of two juxtaposed zones (2a, 2b), said mark appearing to be uniformly green in normal observation (at an angle of 90 degrees relative to the plane of the region) with the pattern 100 appearing in negative (no ink), as shown in FIG. 1, and with iridescent effects appearing only in oblique observation and differing between the zones as shown in FIG. 2, where the zone 2a has a blue effect and the zone 2b a violet effect.

EXAMPLE 3

(11) On a sheet of security paper 1, a security mark 2 was silkscreen printed to produce a first zone 2a in the form of a strip by applying an aqueous ink A2 comprising a red dye and iridescent pigments based on mica/TiO.sub.2 (Iriodin 235 from the supplier Merck) presenting a green iridescent effect visible only in oblique observation, and also producing a second zone 2b contained within the first zone, in the form of a hexagon having two voids presenting the shapes of an A and a W by applying an aqueous ink B2 comprising said red dye and iridescent pigments based on mica/TiO.sub.2 (Iriodin 205 from the supplier Merck) presenting a gold iridescent effect visible only in oblique observation. The iridescent pigments themselves are practically colorless in normal observation. As in Example 2, the inks A2 and B2 had the same hue, this hue being adjusted for each ink as a function of the other ingredients and in particular the iridescent pigments. The inks may contain other conventional additives such as a curing agent, an anti-foaming agent, binders (a hydrosoluble binder such as polyvinyl alcohol (PVA) and/or latex type binders such as a polyurethane), or indeed a viscosity regulator and glycerin. Each of the inks A2 and B2 comprised 28.4 g of iridescent pigments and 0.03 g of red dye per 100 g of the ink composition by dry weight. The hue of the inks was adjusted by colorimetric measurements and by Gardner brightness measurements. The iridescent compositions A2 and B2 were deposited by silkscreen printing at 12 g/m.sup.2 (per composition), with the iridescent pigments being deposited at 3.45 g/m.sup.2 and the dye being deposited at 0.0031 g/m.sup.2, so there was about 0.091% by dry weight of dye deposited relative to the iridescent pigments.

(12) That produced a mark made up of two zones, one within the other (2a, 2b), said mark appearing to be uniformly red in normal observation, with the pattern AW appearing in negative as shown in FIG. 3 and with iridescent effects visible only in oblique observation and differing between the zones as shown in FIG. 4 revealing the hexagon of the zone 2b within the strip 2a.

EXAMPLE 4

(13) The inks of Example 2 were used again, with a fluorescent compound being added to each of the inks: a red fluorescent compound was added to the ink A1; and a blue fluorescent compound was added to the ink B1. As in Example 2, a security mark was produced on a sheet. Under UV illumination, the mark appeared to be red in the zone 2a and blue in the zone 2b.

EXAMPLE 5

(14) The same inks were used as in Example 3 with a fluorescent compound being added to each of the inks: a red fluorescent compound was added to the ink A2; and a blue fluorescent compound was added to the ink B2. As in Example 3, a security mark was produced on a sheet. Under UV illumination, the mark appeared red in the zone 2a and blue in the zone 2b.

EXAMPLE 6

(15) On a sheet of security paper 1, a security mark 2 was photogravure printed, producing a first zone 2a in the form of a strip by applying an ink A5 comprising a green dye and iridescent pigments based on mica/TiO.sub.2 (Iriodin 205 from the supplier Merck) presenting a gold iridescent effect, visible only in oblique observation, and also producing a second zone 2b juxtaposed with the first, in the form of a hexagon having two voids in the form of an A and a W by applying an ink B5 comprising a blue dye and the same iridescent pigments as in ink A5. The iridescent pigments themselves are practically colorless in normal observation. The inks A5 and B5 were thus of different hues.

(16) That produced a mark made up of two zones, one within the other, said region appearing in the form of two zones of different hues in normal observation, one zone being green and the other blue in the shape of a hexagon including the pattern AW appearing in negative, as shown in FIG. 5, and with iridescent effects visible only in oblique observation and similar in both zones, the hexagon no longer being different, as shown in FIG. 6.

EXAMPLE 7

(17) On a sheet of security paper 1, a security mark 2 in the form of a strip was photogravure printed, by producing a first zone 2a in the form of a strip having voids in the form 100 and voids in the form AW, by applying an ink comprising a green dye (green Catarene from the supplier Clariant) and iridescent pigments based on mica/TiO.sub.2 (Lilac Iriodin 219 from the supplier Merck) presenting a violet effect visible only in oblique observation. A second zone 2b was also produced in the form of a pattern 100 by applying an ink comprising the same green dye (green Catarene from the supplier Clariant) and iridescent pigments based on mica/TiO.sub.2 (Iriodin 225 from the supplier Merck) presenting a blue effect visible only in oblique observation, said patterns 100 being applied in register with the voids in the form 100 in the first zone 2a, so as to coincide. The iridescent pigments of the zones 2a and 2b are practically colorless in normal observation.

(18) That produced in normal observation, a mark that appeared as a green strip with 100 as voids, as shown in FIG. 7. In oblique observation, a strip was obtained presenting a violet effect, with (ink-free) voids in AW form and 100 patterns presenting a blue effect as shown in FIG. 8.

EXAMPLE 8

(19) On a sheet of security paper 1, a security region 2 in the form of a strip was printed by photogravure, producing a first zone 2a in the form of a strip including hexagonally-shaped voids, by applying an ink comprising a green dye (green Catarene by the supplier Clariant) and iridescent pigments based on mica/TiO.sub.2 (Lilac Iriodin 219 from the supplier Merck) presenting a violet effect visible only in oblique observation. A second zone 2b was also made by applying within each hexagonally-shaped void an AW pattern using an ink comprising a green dye (green Catarene from the supplier Clariant) and iridescent pigments based on mica/TiO.sub.2 (Iriodin 225 from the supplier Merck) presenting a blue effect visible only in oblique observation. The iridescent pigments of the zones 2a and 2b are practically colorless in normal observation.

(20) That produced, in normal observation, a mark that appeared as a green strip with (ink-free) voids of hexagonal shape, each hexagon containing an AW pattern having the same color as the strip, as shown in FIG. 9. In oblique observation, a strip was obtained presenting a violet effect with (ink-free) voids of hexagonal shape and AW patterns presenting a blue effect, as shown in FIG. 10.