|Title of Invention||
A SECURITY PAPER FOR PRODUCING DOCUMENTS OF VALUE, SUCH AS BANK NOTES, PASSPORTS, ID CARDS OR THE LIKE.
|Abstract||The present invention discloses security paper (1) for producing documents of value, such as bank notes, passports, ID cards or the like, which is provided at least partly with a coating (5) ensuring longer fitness for circulation. The coating (5) is provided at least on one of the raw paper surfaces (4) of the security paper (1), and consists of a composition containing only a binder and no fillers.|
|Full Text||This invention relates to a security paper for producing documents of value,
such as bank notes, passports, ID cards or the like, which is provided with a coating
ensuring longer fitness for circulation, and to a method for producing such a security
Bank notes are usually made of so-called security papers consisting of cotton
fibers and having special security features, such as a security thread at least partly
worked into the paper, and a watermark. The period of circulation of a bank note
depends on the stress it is subjected to. Certain denominations are preferably used in
trade and thus have a shorter period of circulation due to the greater impact of envi-
ronmental influences. The principal cause for the restricted period of circulation of
bank notes is deemed to be premature soiling. Since bank note paper is very porous
it has a large surface area or high surface roughness. Even if the resulting projections
and cavities are in orders of magnitude which cannot be resolved by the human eye,
they offer ideal conditions for dirt deposits in comparison with a smooth surface.
AU-PS 488,652 has therefore proposed making bank notes completely from a
plastic substrate. However, in this case one must do without customary and proven
security elements such as portrait watermarks and window security threads, as well
as special properties such as the sound and feel of bank note paper. Also, the steel
intaglio printing customary in bank notes, which serves as an additional tactile
authenticity mark due to the relief resulting from the inking, merely leads to a flat,
hardly perceptible relief on plastic substrates.
The problem of the invention is therefore to produce a security paper which is
dirt-repellent and therefore has a long period of circulation and which remains un-
changed in its other typical properties, such as printability, sound, color, etc.
Accordingly, the present invention provides a security paper for producing
documents of value, such as bank notes, passports, ID cards or the like, which is
provided at least partly with a coating ensuring longer fitness for circulation, the
coating being provided at least on one of the surfaces of the security paper,
characterized in that the coating consists of a composition containing a polyamide
lacquer or an acrylate system as the sole binder and no fillers and optionally one or
more visually or machine testable additives for security features and/or codings.
A binder within the meaning of the invention includes all substances which
form insoluble films or structures in common solvents. The essential thing is that the
binder, unlike customary coating materials, contains no fillers, i.e. pigments such as
titanium dioxide, in high concentrations. This composition wets the fibers in the sur-
face area of the paper, forming a complete surface film over the fiber. This mini-
mizes the access of dirt to the fiber.
The composition is applied in a layer thickness so as to form a sufficiently
smooth surface and minimize the possibilities of dirt deposit, on the one hand. On
the other hand, the layer thickness is so small as not to impair the other properties of
the paper, such as its feel and printability. The weight per unit area of the coating is
preferably about 1 to 6 g/m2, in particular 2 to 3 g/m2.
The small coating thicknesses leave the transmission properties of the paper
unchanged so that the recognizability of any portrait watermarks in the security pa-
per is not impaired. The coating additionally has the advantage that one can do with-
out the customary sizing of the paper. The kind of security paper is not subject to
any conditions either, so that one can use customary security papers made of annual
plant fibers, in particular cotton fibers, as well as security papers consisting at least
partly of plastic fibers, preferably polyamide fibers.
The binders used are preferably polyamide lacquers, acrylates or binder sys-
tems containing a high percentage of acrylates. If the binder system has several
polymer components, they can be present as a mixture or as copolymers. But one
can fundamentally use other binder systems as well. Chemically or physically
crosslinkable compositions have proved particularly useful.
Particularly acrylate systems have a number of advantages over other binder
systems, for example ones based on polyurethane. They thus have better printing
properties and contain fundamentally less solvent so that their processing involves
lower environmental impact. Acrylate coatings are in addition characterized by
higher surface hardness so that the dirt-repellent effect is improved. Finally, acrylate
systems offer the advantage of being considerably more cost-effective than other
binder systems and being readily mixable with other polymers.
The binder composition is knife-coated or printed on the paper after production
of the latter. This can be done directly subsequent to papermaking in the paper ma-
chine or in a separate operation, for example directly before printing the security
paper. If required, the smoothness of the surface can subsequently be increased by
corresponding calendering. The inventively coated paper offers an ideal printing sur-
face for high print resolution and very good ink adhesion in case of attempted physi-
cal and/or chemical attacks.
Then the inventive security paper is printed and possibly processed further in
accordance with the paper of value to be produced. A print or embossing, in par-
ticular if produced by intaglio printing, leads to a rough surface again and therefore
favors dirt deposits. In order to exclude this as well, it is proposed according to the
invention that the print be covered with a further binder layer, e.g. lacquer layer. The
lacquer layer is preferably adjusted in its composition to the inventive background
layer to permit a good bond of the two layers. The bond might be improved by an
additional crosslinking step. This can be done by the action of heat or irradiation
(e.g. UV radiation). Since the print can be produced with any printing process, such
as by steel intaglio or with a laser printer, it might be necessary to adapt the inven-
tive binder composition to the printing process used in order to ensure not only low
soiling but also improved adhesion of the inks to the substrate.
A further advantage of the invention is that one can do without further pre-
treatment of the inventive security paper when optically variable security elements
are to be provided on the paper. Optically variable devices or inks showing a view-
ing angle dependent interplay of colors due to diffraction or light interference re-
quire a smooth background for good visibility of this effect. Security elements of this
kind are for example holograms, kinegrams or other diffraction structures, as well as
inks containing interference layer or liquid crystal pigments or other special-effect
pigments such as glossy metallic-effect pigments.
In special cases, however, it may still be useful to provide a further background
layer in the area of said element. Liquid crystal pigments and interference layer pig-
ments consisting only of thin mica plates coated with titanium dioxide are transpar-
ent so that the color effect is not influenced by the smoothness alone but also by the
color of the background. A black background absorbs light transmitted by the pig-
ments, thereby increasing the brilliance of the colors reflected by the pigments. The
same applies to security elements constructed of several thin layers and likewise
showing an interplay of colors based on interference effects. For these and similar
elements it may therefore be necessary to provide the security paper with a further
background layer in the area of the security element to be applied.
Alternatively, it may also be expedient to underlay the security element with a
mechanically or visually detectable authenticity feature, as known for example from
The inventive coating furthermore has an advantageous effect on other security
elements. For example, it makes embossed structures more trenchant since the
smoother background makes the embossings more prominent. Embossings are also
more durable since not only the paper fibers are embossed.
According to a preferred embodiment, the coating composition additionally
contains a low concentration of at least one substance with a visually and/or me-
chanically detectable physical property. The substance can have for example mag-
netic, electroconductive, diffractive, light-polarizing or light-interfering properties
and be uniformly distributed all over the total coating or applied in the form of pat-
terns. One thereby preferably, in a first step, prints a certain pattern of a composition
containing small amounts in the manner of a doping ( stance with at least one visually and/or mechanically detectable physical property.
Only in a second step does one apply the same composition but not containing the
detectable additive to the remaining part of the surface of the paper in register with
the first pattern.
Said additives can be for example luminescent substances excitable with UV
light and emitting in the visible spectral region. In the case of a machine check,
however, one can also use luminescent substances emitting in the invisible spectral
region, preferably the IR spectral region. One can likewise use photochromic or
Instead of physically detectable substances one can also use chemically react-
ing additives. For example, one can admix a component of a color reaction system to
the binder composition and apply it to the paper. When one applies the second com-
ponent of the color reaction system at a later time, a colored area, pattern, writing or
the like becomes visible on the security paper. This can serve as an authenticity fea-
ture or as a cancellation mark for a check, airplane ticket or the like.
By using a plurality of additives and/or varying the concentration of one or
more additives one can very simply produce any kind of coding, for example a bar
code, on the security paper. Said coding can for example constitute an independent
additional security feature or serve as a reference feature for other data already pro-
vided on the security paper. Thus, information visible to the naked eye on the bank
note, such as denomination, the name of a person shown in the portrait or the like,
can be encrypted and stored on the paper in the form of the inventive coding invisi-
ble to the naked eye. In a machine check the coding is read, decrypted and tested for
identity with the corresponding information visible to the naked eye.
According to the inventive principle one can of course also produce a plurality
of different codings. For example, one applies the binder compositions containing
the particular additive to the paper in the form of the desired codings simultaneously
or successively. One prints or coats the remaining part of the paper surface with ad-
ditive-free binder composition, as explained above. Alternatively, the different cod-
ings can also be disposed on different surfaces-of the security paper. Double-sided
coating with the same additive is of course likewise possible.
According to a further embodiment, the inventive coating can also have gaps.
Said gaps can have any form, e.g. a striped form. Before or after application of the
inventive coating they are provided with a print having certain special-effect inks.
Said special-effect inks may be interference layer pigments, liquid crystal pigments
or other gloss pigments. Said print can cover the gaps all-over or only partly.
The inventive security paper can for example also be used advantageously for
producing ID cards and passports. Since it has increased tear strength and dirt resis-
tance, one might possibly do without the customary lamination with plastic foils. If
lamination is nevertheless effected, the inventive coating ensures a firm, inseparable
bond between paper and cover layer.
In the following some examples of the inventive composition will be explained.
A bank note paper made of 100% cotton with a filler content of 3.0% is used
for the coating test. The paper is adjusted to a wet strength of 50% based on the dry
strength by using commercial melamine resin (e.g. Madurit MW167).
The following formulation is used as the coating:
Acronal 320D (BASF) 400 ml
- aqueous dispersion of acrylic resin -
Softened water 600 ml
The mixture is prepared by stirring and applied to the surface of the paper. For
this purpose one uses a rotating pair of rolls whose lower side dips into a dish with
the diluted Acronal dispersion. Excess suspension is pressed off through the roll slit.
• The paper is subsequently dried with a commercial photo drier.
The treatment gives the paper the following properties:
A paper is coated in the same way as stated in Example 1 with the following
Neocryl-AC 72 (Zeneca) 900 ml
- aqueous dispersion of acrylate -
Water 80 ml
Crosslinker CX 100 (Zeneca) 20 ml
The paper can also be coated with the following binder composition:
Primal 1-545 (Rohm & Haas) 900 ml
- aqueous dispersion of acrylate -
Water 80 ml
Zirconium carbonate (Auer Remy) 20 ml
The inventive binder system can also consist of a mixture of several polymers.
As an example the following formulation is stated:
Glascol LS 26 (Ciba) 700 ml
- aqueous dispersion of acrylate-styrene copolymer -
Polyurethane U 400 N (Alberdink Boley) 200 ml
Water ' 100 ml
Further advantages and embodiments will be explained in more detail with ref-
erence to the figures. It is pointed out that the figures show the layer structure of the
inventive security paper only schematically.
Fig. 1 shows an inventive security paper from the front,
Fig. 2 shows a section along A - B through the inventive security paper ac-
cording to Fig. 1,
Fig. 3 shows a further embodiment of an inventive security paper from the
Fig. 4 shows a cross section along A - B through the inventive security paper
according to Fig. 3.
Fig. 1 shows a detail of inventive security paper web 1 as is used for example
for producing bank notes. Such security paper is usually made of cotton fibers or
other annual plant fibers. For some applications, however, it may be useful to re-
place part of said natural fibers by plastic fibers, in particular polyamide fibers. Pure
plastic fiber papers are also possible. During production of paper web 1 individual
security elements are already embedded in the paper, such as a portrait watermark or
security thread 2 shown in Fig. 1. Security thread 2 is quasi woven into the paper so
as to pass directly to the surface of the paper in areas 3 while being embedded com-
pletely in paper pulp in the dash-lined areas. Thread 2 can be provided with any de-
sired security features, such as an electroconductive, metallic layer, hologram or the
Fig. 2 shows a section through inventive security paper 1 along dash-dotted
line A - B in Fig. 1. Inventive security paper 1 consists of raw paper 4 as usually
leaves the paper machine, and inventive binder coating 5 which was knife-coated or
printed all over a surface of security paper 1 according to the shown embodiment.
Alternatively, coating 5 can also be applied to security paper 1 on both sides.
Figs. 3 and 4 show a further embodiment of inventive security paper 1. Fig. 4
shows a section through inventive security paper 1 along dash-dotted line A - B in
As shown in Fig. 4, security paper 1 likewise consists of customary paper web
4 provided with a pure binder composition without fillers according to the invention.
However, the binder layer is composed of different areas 6, 9. In areas 6 the binder
composition is doped with an additive which is testable visually and/or mechani-
cally, while remaining areas 9 of the binder composition contain no additive. As evi-
dent from Fig. 3, area 6 represented by the doped binder composition forms visually
readable information. Areas 7 likewise represented with the doped binder composi-
tion form coding 8 in the form of a bar code.
The additive may be for example a luminescent substance transparent in nor-
mal illumination but emitting in the visible spectral region and thus showing an in-
tensive tone when irradiated with UV light. In this case information 6, 8, as shown
in Fig. 3, is visible only in UV illumination.
However, one can also provide a plurality of additives which are singly detect-
able. The mixture ratio of the additives can be used to produce an additional coding.
It is likewise conceivable to produce information 6, 8 with different additives. Thus,
one can produce information 6 with the aid of a luminescent substance emitting in
the visible spectral region, as explained above, while representing bar code 8 with
the aid of a substance detectable solely by machine, e.g. a luminescent substance
emitting in the IR spectral region. Marks 6 visible to the naked eye in UV illumina-
tion can represent for example a picture, pattern or readable information. Machine-
readable code 8, however, could represent certain information characteristic of the
individual document of value, optionally in encrypted form. Said information could
be properties inherent to the paper material, such as transmission properties, thick-
ness distribution, etc., or other information essential to the particular document of
value, such as denomination or the like.
1. A security paper for producing documents of value, such as bank notes, passports,
ID cards or the like, which is provided at least partly with a coating ensuring longer
fitness for circulation, the coating being provided at least on one of the surfaces of
the security paper, characterized in that the coating consists of a composition
containing A polyamide lacquer/ or an acrylate system as the sole binder and no
fillers and optionally one or more visually or machine testable additives for security
features and/or codings.
2. A security paper as claimed in claim 1, wherein the composition is present on the
security paper in a coating weight of 1 to 6 g/m2, preferably 2 to 3 g/m2.
3. A security paper as claimed in claim 1 or 2, wherein the composition contains
acrylates or a mixture of polymers or copolymers with a high acrylate content as a
4. A security paper as claimed in at least one of claims 1 to 3, wherein the
composition contains a low concentration of at least one substance with a visually
and/or machine detectable property for security features and/or codings.
5. A security paper as claimed in claim 4, wherein the substance has luminescent,
magnetic, electroconductive, diffractive, light-interfering or light-polarizing
6. A security paper as claimed in claim 4 or 5, wherein the substance or substances
are provided in the coating only partly, preferably in the form of a pattern.
7. A security paper as claimed in at least one of claims 1 to 6, wherein the security
paper consists of fibers of annual plants, in particular cotton fibers.
8. A security paper as claimed in at least one of claims 1 to 7, wherein the security
paper consists at least partly of plastic fibers, preferably polyamide fibers.
9. A security paper as claimed in at least one of claims 1 to 8, wherein the security
paper is an unsized paper.
10. A security paper as claimed in at least one of claims 1 to 9, wherein the coating is
applied to the security paper only in certain areas and the coating-free areas are
printed with an ink containing special-effect pigments.
11. A document of value, such as a bank note, check, ID card or the like, wherein the
document of value has a security paper as claimed in any one of claims 1 to 10.
12.A document of value as claimed in claim 11, wherein the document of value has
over the coating a print which is in turn covered by a coating, such as a lacquer
13.A method for producing a security paper as claimed in at least one of claims 1 to
10, wherein a paper layer is produced in a paper machine and subsequently a
coating applied at least partly to at least one of the surfaces of the paper, the
coating consisting of a composition containing a polyamide lacquer or an acrylate
system as the sole binder and and no fillers and optionally one or more visually or
machine testable additives for security features and/or codings.
14. A method as claimed in claim 13, wherein the paper is sized before application of
15. A method as claimed in claim 13 or 14, wherein the coating is printed on.
16. A method as claimed in any of claims 13 to 15, wherein the coating is applied in a
plurality of steps.
17. A method as claimed in claim 16, wherein a composition containing small amounts
of at least one substance with at least one visually and/or machine detectable
physical property for security features and/or codings is applied in the form of a
pattern in a first step, and the remaining part of the surface of the paper is provided
with the same composition without the detectable substance in register with the
pattern in a second step.
The present invention discloses security paper (1) for producing documents of value,
such as bank notes, passports, ID cards or the like, which is provided at least partly
with a coating (5) ensuring longer fitness for circulation. The coating (5) is provided
at least on one of the raw paper surfaces (4) of the security paper (1), and consists of a
composition containing only a binder and no fillers.
|Indian Patent Application Number||IN/PCT/2000/577/KOL|
|PG Journal Number||34/2008|
|Date of Filing||30-Nov-2000|
|Name of Patentee||GIESECKE & DEVRIENT GMBH,|
|Applicant Address||PRINZREGENTENSTRASSE 159, D-81677, MUNCHEN|
|PCT International Classification Number||D21H 19/10|
|PCT International Application Number||PCT/EP 1999/04471|
|PCT International Filing date||1999-06-28|