Note: Descriptions are shown in the official language in which they were submitted.
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IMPROVEMENTS IN NMETHOOS OF MANUFACTURING SECURITY SUBSTRATES
The present invention relates to 'improvements in
methods of manufacturing security substrates having security
features. More specifically the present invention relates to
a method of incorporating a security feature into a fibrous
substrate, such as paper, by manufacturing a paper tape
provided with a security feature and incorporating the paper
tape during the forming process of the base substrate.
It is generally known to include elongate elements in
paper or other substrates, usually as a security feature.
Such elements can be threads, strips or ribbons of, for
example, plastics film, metal foil, metallised plastic,
metal wire. These elongate elements are included in the
thickness of the substrate to render imitation of documents
produced therefrom more difficult. These elements help in
the verification of the documents as they render the view of
the documents in reflected light different from that in
transmitted light. To increase the security provided by the
inclusion of such an elongate element, it is also known to
endow the element itself with one or more verifiable
properties over and above its presence or absence. Such
additional properties include magnetic properties,
electrical conductivities, the ability to absorb x-rays,
fluorescence, optically variable effects and thermochromic
behaviour.
As a further',security feature,"it has been found to be
~ 30 par,ticularly , adventageous to.provide , windows'in one side of , ..
ch , expose such el'ongate
the,surface , of the substrate, whi . , .
elements at spaced locations. Examples of methods of
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manufacturing paper incorporating security elements with or
without windows are described below. It should be noted
that references to "windowed thread paper" include windowed
paper incorporating any elongate security element.
EP-A-0059056 describes a method of manufacture
of windowed thread paper on a cylinder mould paper-making
machine. The technique involves embossing the
cylinder mould cover to form.raised regions and bringing an
impermeable elongate security element into contact with the
raised regions of the mould cover, prior to the contact
entry point into a vat of aqueous paper stock. Where the
impermeable security element makes intimate contact with the
raised regions of the embossing, no fibre deposition can
occur and windows are formed in the surface of the paper.
After the paper is fully formed and couched from the
cylinder mould cover, water is extracted from the wet fibre
mat and the paper is passed through a drying process. In the
finished paper the regions of the security element which are
exposed in the windows are visible in reflected light on one
side of the paper, which is commonly used for mainly
banknotes.
EP-A-0229645 describes a method using two cylinder
moulds to produce two separate plys of paper, with a
security thread introduced in between the two layers. The
option of incorporating holes in both layers by, for
example, incorporating drainage restriction devices on the
mould covers is disclosed in the specification. The
resulting holes can be registered.to produce windows on each
side of the thread. This method has a major drawback in that
the two cylinder moulds need to be exac'tly the same diameter
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and linked by a registration system which renders production
of the paper extremely expensive. This document also fails
to teach how to actually achieve registration.
Based on the desire to be able to display as much
information or indicia as possible in the exposed regions,
it has also been recognised that it would be highly
advantageous to be able to expose the elongate element on
both sides of the paper, or other substrate, in which it is
embedded. EP-A-0059056 suggests that this could be achieved
by using sufficiently large impervious projections on the
cylinder mould. The disadvantage with the method described
in this specification is that the holes produced by the
drainage limiting devices need to be covered up and this
means that rather wide threads have to be'used, which
increases the cost of the paper. Another disadvantage of
this method is that the windows on each side necessarily
coincide.
EP-A-1630285 describes an alternative method for
manufacturing a paper substrate incorporating an elongate
impermeable element which is exposed in windows in both
surfaces of the substrate. This method involves a
modification to the cylinder mould papermachine with the
requirement of an additional moving belt urider the
conventional cylinder mould. Such a modification is non-
ideal and increases'the cost and complexity of the process.
GB-A-2397582 describes a further alternative method for
30. manufacturing a.paper.substrate incorporating an elongate
imp , . .,. , ... . .,= , .
ermeable element which,exposed inwindows' on both
surfaces of the substrate. In this method the security
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element comprises a plurality of wide regions separated by
narrow regions, the wide regions being of a width which
obstruct the deposition of fibres. The elongate element is
brought into contact with a cylinder mould cover having
window forming means such that the narrow regions form
windows in the conventional manner as in EP-A-0059056 and
the wide regions, by virtue of obstructing deposition, form
windows in the opposing surface. The main limitation with
this method is that the profile of the elongate element has
to be tessellated. This tessellated profile increases the
expense for producing the elongate element as single
elements have to be produced using die-stamping or laser
cutting rather than simply slitting from a wide web.
The use of watermarks is also common in many security
documents. A multi-tonal watermark is typically created'
using a cylinder mould process and is formed by varying the
density of paper fibres so that in some areas the fibres are
denser and in others less dense than that of the base paper
layer which separates the denser and less dense areas. When
viewed in transmitted light the less dense areas are lighter
and the denser areas darker than the base paper, and the
contrasts can be seen very clearly.
A multi-tonal watermark is often a pictorial image such
as a portrait and can be very detailed and complex which
significantly reduces the risk of counterfeiting.
Cylinder-mould paper machines have been used for many
years to.mariufacture secur.ity substrates comprising.not only
the,aforementioned security elements.and watermarks, but
also a range of other security features. Whilst the use of
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the cylinder-mould paper machine has been successful in
manufacturing security substrates of a sufficient high
quality, the manufacturing process has to be tightly
controlled and the paper machine run at slower speeds than
would be typical for a plain substrate containing no
security features. For example, in the production of
cylinder-mould made watermarks, a relatively slow machine
speed is essential to ensure that the watermark exhibits a
full range of tones with a very high degree of clarity.
It has also been found that the production of paper
with wide elongate security elements, up to 6mm wide but
more commonly between 1 and 4mm wide, can limit the paper
machine speed. This is to allow adequate dewatering around
the security element, which prevents the security elements
delaminating from the paper along the edge of any windows in
the surface of the paper in which the thread is exposed, and
to ensure adequate coverage of fibre on the back of the
security element.
It is therefore one object of the present invention to
provide an improved method of manufacturing fibrous security
substrates comprising security features which are fabricated
during the manufacturing process, such as watermarks and
windowed security elements, which overcome the
aforementioned disadvantages.
It is a second object of the present invention to
provide an improved"method of.manufacturing fibrous security
-substrates v,ihich~-enable the !generation 'of new security devices not
achievable with,known.paper making processes.
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It is a third object of the present invention to
provide an improved method of manufacturing fibrous security
substrates which enable the incorporation of an elongate
impermeable element which is exposed at windows in both
surfaces of the fibrous security substrate.
The invention therefore comprises a method of
manufacturing fibrous security substrates comprising the
steps of manufacturing an elongate fibrous tape and
fabricating at least one security feature in or on the tape,
forming a base substrate by depositing fibres onto a support
surface, wherein the tape is incorporated within the base
substrate to form the security substrate during the
formation of the base substrate.
The fabrication of the security feature occurs during
the manufacture of the tape, preferably as an integral part
of the tape manufacturing process.
The at least one security feature comprises a
watermark, an elongate security element at least partly
embedded with in the fibrous tape and/or perforations
produced in the tape during the forming process providing a
pattern, identifying indicia or the like.
The invention further comprises a security substrate
formed by the aforesaid method and security documents formed
from the said security substrate.
The invention will now be described, by way of example
only, with reference to'the'accompanying drawings, in which:
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Figure 1 is a flow chart illustrating the steps of the
method of the present invention;
Figure 2 is a plan view of a first fibrous web for use
in the method of the present invention;
Figures 3a and 3b are schematics of sections of
cylinder mould paper making machines used in the method of
the present invention;
Figure 4 is a plan view of one side of a security
substrate made by the method of the present invention;
Figure 5 is a cross-sectional side elevation of the
security substrate of Figure 4 on the line IV-IV of Figure
4;
Figures 6 to 8 and 10 to 13 are plan views of
alternative security substrates incorporating different
security features;
Figure 7a is a plan view of the security substrate of
Figure 7 viewed in transmitted light;
Figure 9 is a cross-sectional side elevation of a
further alternative security,substrate;
Figure'14 i's a :"schematic 'of 'a , section.,of a' cylinder mould paper
making machine.used in a further embodiment of
the metYio,d of, the;, present invention;
, , . . , ., .11: .y. . ... , r.+ . . . , .
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Figure 15 is cross sectional side elevation of a
portion of the cylinder mould cover of the machine of Figure
14 on the line XV-XV;
Figure 16 is a cross sectional side elevation of a
portion of the substrate produced on the machine of Figure
14 on the line XVI-XVI of Figures 17 and 18;
Figures 17 and 18 are plan views of the front and back
of the security substrate of Figure 16;
Figures 19 and 20 are plan views of the front and back
of an alternative substrate to that of Figure 16;
Figures 21 and 22 are front and rear elevations of a
portion of tape used in the method of the present invention;
Figure 23 is a cross sectional side elevation of a
section of the cylinder mould cover of the paper machine
used to produce the tape of Figures 21 and 22; and
Figures 24 and 25 are plan views of the front and back
of another alternative embodiment of a security substrate to
that of Figure 16.
The method of the present invention is used to
manufacture a security substrate 16, which comprises a base
fibrous substrate 15, preferably paper, and a fibrous,
preferably paper, tape 14 incorporating one or more security
features 11 which are fabricated in the tape 14.
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Referring to Figures 1 and 2, in the first part of the
method of the present invention a first paper web 10 is
produced from which a plurality of paper tapes 14 are
formed, each comprising one or more security features 11. At
least one of the security features 11 is one which is
fabricated in the tape 14 during its manufacture. This
security feature 11 is one which may limit the production
speed of the manufacturing process as compared to the speed
of the process when producing a plain substrate without the
feature 11. Examples of such security features include
multi-tonal watermarks, single tone watermarks commonly
known as electrotypes, patterned fibre free regions in the
form of holes or perforations, and polymeric elongated
elements (including embedded and partially embedded
threads). One or more further security features may be
fabricated in the tape 14 post manufacture.
The security feature 11 may also be one where the paper
fibres fully or partly define the security feature 11. In
the case of watermarks, the fibres fully define the feature,
whereas in the case of the polymeric elongate security
element, the paper fibres 21 only partly define the feature,
for example by forming the windows and bridges in a windowed
element or by concealing an embedded element when viewed in
reflection.
A number of security features 11 are preferably aligned
in parallelstrips 12 across the ~.web10 ~: Figure 2
illustrates a series of, aligned windowed polymeric security
elements (threads) ,across the-;:width of the 'web .10.
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An optional adhesive coating may be applied to the
first paper web 10, using a conventional size bath in which
the paper web 10 is submerged in an adhesive resin. A
conventional size press may also be used, comprising a pair
of rolls, into the nip of which an adhesive is applied
through which the dry or partially dry web 10 is passed.
Alternatively, the adhesive may be applied to the first
paper web 10 using conventional coating methods such as
gravure coating. An alternative to using an adhesive
coating is to add thermosoftening fibres to the furnish used
to make the paper web 10, such that on heat activation
during the drying of the security substrate 16 the fibres
from the tapes 14 (made from the paper web 10) fuse to the
base substrate 15.
The first paper web 10 is then slit along lines 13 on
either side of the security feature 11 to produce a series
of tapes 14. It is not essential for the tapes 14 to have a
linear edge and the edge of the tapes 14 could have a curved
or geometric pattern. One method of achieving a curved or
geometric pattern is by cutting the tapes 14 with a laser.
The paper web 10 is preferably made from cotton based
paper stock but alternatively wood based pulp or synthetic
fibres can be used. Paper tapes 14 of varying permeability
may be employed in the current invention with the only
strength requirement being that the final paper tape 14 has
sufficient handling strength to be integrated into the.base
substrate.
Preferably the tape 14 is produced using a cylinder
mould paper machine (similar to that shown in Figures 3a and
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3b), although other papermaking processes could be used such
as the Fourdrinier process. The cylinder mould paper machine
comprises a vat 20 containing a suspension of paper fibres
21 in which dips the major portion of a cylinder 22 arranged
with its axis horizontal. The surface of the cylinder 22
comprises a cylinder mould cover 23, formed from a wire
mesh. Liquid is drawn through the mesh as the cylinder 22 is
rotated causing paper fibres to deposit on the mesh and form
a sheet which is couched from the cylinder 22 by the couch
roll 24 and conveyed away. The permeability of the paper can
be adjusted by varying the mesh size of the cylinder mould
cover 23. A substrate containing security features such as a
watermark and a partially embedded polymeric thread would
preferably be formed on a fine mesh with a typical mesh size
being 70 (warps per inch) by 48 (wefts per inch) (70/48).
The fine mesh results in a uniform well consolidated low
permeable sheet suitable to withstand the mechanical
handling experienced by a banknote in general circulation.
Typically a low permeable fibrous paper tape 14 suitable for
use in the current invention will have a Bendtsen porosity
in the range 0 to 100m1s/min.
Alternatively a high permeable paper web can be
produced by using a coarse mesh size for example a typical
mesh'size would be 20 (warps per inch) by 20 (wefts per
inch) 20/20. Paper produced from a coarse mesh comprises a
plurality of'discrete areas having a lower fibre density
than the rest.of the web. Water can more easily pass throu.gh
the areas'of low,er fibre density resulting in a high
permeab.le substrate:
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Other methods may be used to make high permeability
paper, including the use of electrotypes to produce small
regions of reduced grammage paper. Another method is to
apply water jets through a cylinder rotating on the formed,
but still wet, paper mat. The cylinder is partially blinded
by a patterned stencil. Where the pattern is open, water
passes through the cylinder and displaces the paper fibres
causing low, or even zero, grammage regions that are more
porous than adjacent regions. Such methods could result in
specific regions of the tape having high permeability
compared to other parts of the tape 14.
The base substrate 15 is subsequently produced,
preferably also using a cylinder-mould process, and one or
more of the tapes 14 is fed into the vat 20 of furnish 21
used to form the base substrate 15, in which rotates the
major portion of a cylinder 22 on a horizontal axis. The
surface of the cylinder 22 comprises a cylinder mould cover
23 formed from a wire mesh. Liquid is drawn through the mesh
as the cylinder 22 is rotated causing fibres 21 to deposit
on the mesh and form a continuous sheet of the base
substrate 15 which is couched from the cylinder 22 by the
couch roll 24 and conveyed away. The tape 14 can be brought
into contact with the cylinder mould cover 23 either before
the cylinder mould 22 enters the vat as shown in Figure 3b,
or more preferably, as shown in Figure 3a, after the
cylinder mould 22 has entered the vat. In the case of a low
permeable paper tape, once the tape 14 has made contact with
the cylinder mould cover 23, no more fibres deposit over the
tape 14.resulting in it being exposed on the back surface 18
of the finished security substrate'16. The back surface 18
of the substrate 16 is the surface of the substrate 16 which
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is facing away from the cylinder mould cover 23 during its
formation. The front surface 17 is the surface which is
facing towards the cylinder mould cover 23 during formation
of the substrate 16.
In an alternative embodiment the tape 14 may be formed
from a paper web that is sufficiently permeable that the
fibres continue to deposit over the tape 14 once it has made
contact with the cylinder mould enabling the possibility of
the tape 14 being wholly embedded.
The base substrate 15 can be produced at a production
speed higher than the speeds used when the security feature
11 is formed directly in the substrate 15, because there are
no complex processes required. The incorporation of a tape
14 in the substrate 15 is not detrimental to the machine
speed because of the high compatibility between the fibrous
tape 14 and the fibrous base substrate 15.
The security features 11 are incorporated into the
paper web 10 using the same methods as for a typical
banknote substrate. For example multi-tonal watermarks are
introduced by embossing the wire mesh face-cloth attached to
the cylinder mould. When the wire cloth is embossed with a
detailed image, the fibres deposit with a lesser or greater
thickness on the raised and depressed elements of the
embossing respectively to form a fully three-dimensional
watermark in the'paper. An alternativesecurity device is'a
single tone light element", commonly.,knowri as an electrotype.
This is created'~by attachingaJmetallicelectrotypeelement
, . , .
,..,.~. . .. , or a polymeric sealing corripound 'to ',th'e cylinder mould
cover,
resulting in a significant decrease in'drainage through the
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cover and reduced fibre deposition, forming a light mark in
the paper.
A further security feature 11 which is suitable for use
in the present invention is an array of patterned apertures
in the form of holes and perforations. WO-A-0039391
describes a method of making single ply paper with fibre-
free regions by blinding one or more selected areas of a
cylinder mould cover, and then depositing a layer of paper
fibres onto the cylinder mould cover around the blinded
areas. The blinded areas are impermeable which substantially
prevents the deposition of fibres. A similar method is
described in WO-A-03054297. The blinded areas can be created
by attaching a suitably shaped metallic or polymeric element
to the cylinder mould cover.
The presence of apertures in the tape 14 enables the
incorporation of a new security device in the finished
security substrate 16 which is not currently achievable by
known papermaking processes. Fibres from the substrate 15
fill at least one aperture in the tape 14 and form a fibrous
layer on the surface of the tape 14 around the perimeter of
the apertures such that the apertures are not well defined
and poorly resolvable in reflected light, but are clearly
visible in transmitted light.
In a further embodiment an elongated security element
or thread can be incorporated in the tape 14. Such,security' '
elements may be wholly or partially embedded into the tape
14. It is usual,to refer to partially embedded security,
elements as being windowed, as the security elementis .
exposed at regular intervals on the surface of the substrate
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in which it is embedded, like a series of windows. A number
of methods for producing security papers with so-called
windowed security elements have been described one of which
is described in EP-A-0059056. Paper is still regularly
produced by the method described within EP-A-0059056 and
sold commercially under the trade name Stardust by the De
La Rue Group.
In a further embodiment of the present invention the
fibrous tape 14 has an elongate element partially embedded
therein and at least one discrete aperture extending through
the fibrous tape 14 exposing at least a part of the elongate
element, wherein at least one edge of the elongate element
is exposed in the aperture(s). A method for producing a
paper web, with an elongate element exposed in an aperture,
is disclosed in WO-A-4001130.
As the first part of the method of the present
invention is only concerned with generating the webs 10 from
which the tapes 14 are cut, and not the final security
substrate 16, the polymeric security elements (or other
security features 11) can be positioned very close together
on the paper web 10. This highly efficient arrangement of
the security features 11 further compensates for the paper
machine being run at a reduced speed to successfully
incorporate the security features 11. This'avoids the usual
trade-off that occurs when the security features 11 are
incorpora;ted,during the production of the final substrate,
i.e.,between running at high,speeds to increase production
and,low .speeds to ensure the quality of the security feature
11.
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Experimental work has shown that where the edge of the
tape 14 has a thinner fibrous layer than the main body of
the tape 14 a higher level of adhesion to the base substrate
15 is observed than for a tape 14 with a uniform thickness.
This is because, when the tape 14 is rewetted on insertion
into the vat during the production of the base substrate 15,
the fibres in the thin fibrous layer of the tape 14 have an
increased freedom of movement compared to a thicker layer
and can entangle and bond more efficiently with the base
substrate 15.
A preferred method for manufacturing a paper tape 14
with a thin fibrous edge is to attach continuous thin wires
circumferentially around the cylinder mould cover to mark
the edge of each paper tape 14. The wire will result in a
significant decrease in drainage and fibre deposition
forming a light line 13 in the paper web 10 defining the
edge of each tape 14. The paper is significantly thinner
along these lines 13 and can be torn by a suitable roller
and rewind arrangement..The tearing action, as opposed to a
slitting action, results in a frayed fibrous edge which
further enhances the bonding of the tape edge into the base
substrate 15.
A further advantage of the present invention is that
the production of the paper web 10 for the tape 14 is solely
.concerned with the generation of the security features 11.
This allows paper fibres of a specific.type or
characteristic to be used in order to optimise the security
feature 11. This is particularly useful for watermarks,
where short fibres lead to improved watermark definition:
However, whilst short fibres would normally result in a
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degradation in strength and durability of traditionally made
paper, the proposed method enables the fibres in the base
substrate 15 to be optimised for strength and durability
whilst using short fibres in the tape 14. It is well-known
in the papermaking art that the doublefold and tensile
strength properties are generally improved by the addition
of longer fibres or synthetic fibres and therefore for
example the strength of the base substrate 15 could be
optimised by using synthetic PVOH fibres as described in EP-
A-0073448.
The resultant final security substrate 16 will contain
a higher quality security feature 11 and exhibit a higher
strength and durability compared to when the security
feature 11 is incorporated directly into the paper during
the production of the finished substrate.
In a further embodiment the paper tape 14 may be given
different aesthetic properties to the base substrate 15. For
example the tape 14 may be formed from red coloured fibres
resulting in a red paper tape 14 comprising a security
feature 11 as defined previously. In further examples the
tape 14 could be fully or partly formed from phosphorescent
or fluorescent fibres.
The tape 14 may go undergo a number of optional
processing steps prior to being incorporated into the base
substrate 15. In order'to-provide additional security,
images may be printed onto the tape 14 using conventional
~security printing-techniques such_as,gravure,, screen
printing, litho, iritaglio etc.;The surface of the tape 14
could be modified by embossing or applying:tactile inks such
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that in the final substrate 16 the tape 14 can be identified
by touch. The tape 14 may also be perforated to provide
improved bonding with the base substrate 15 or to produce a
decorative effect.
In order to ensure the tape 14 is fully bonded to the
base substrate 15, a heat sealable or water soluble adhesive
may be applied to one or both sides of the tape 14 by
standard coating or printing processes. In the preferred
embodiments where the tape 14 is to be incorporated into the
base substrate 15 such that it surfaces on the back surface
18 of the finished security substrate 16, the adhesive may
be applied only over the edge of the tape 14 on the side
that surfaces to adhere the fibres from the base substrate
15 that overlap the edge of the tape 14.
There is no width or thickness restriction to the tape
14 of the present invention but preferably the width of the
tape 14 is in the range 5-50mm and more preferably 10-30mm.
The thickness of the tape 14 is preferably between 20-
70% of the thickness of the base substrate 15 and more
preferably between 40-70% of the thickness of the base
substrate 15.
In a preferred embodiment a well consolidated low
permeable paper tape 14 is arranged to enter the liquid in
the vat 20 prior to contacting the cylinder mould cover 23,
so that the surface of the cylinder mould cover 23 has
already acquired a substantial coating of paper fibres.21
before the tape 14 makes contact', as shown in Figure 3a.
Preferably between 20-70% and more preferably between 20-50%
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of the desired thickness of paper fibres 21 of the base
substrate 15 have been deposited on the cylinder mould cover
23 before the tape 14 contacts the cylinder mould cover 23.
As the cylinder 22 continues to rotate, few or no fibres 21
are deposited on the back surface of the tape 14, although
fibres 21 continue to accumulate adjacent to the tape 14,
with the result that the tape 14 is exposed on the back
surface 18 of the finished security substrate 16.
The incorporation of the tape 14 as shown in Figure 3a,
such that there is a substantial coating of fibres on the
front surface of the tape 14, improves the durability of the
finished security substrate 16.
In an alternative embodiment, as shown in Figure 3b,
the fibrous tape 14 is arranged to contact the cylinder
mould cover 23 prior to the cylinder mould 22 entering the
liquid in the vat with the result that the tape 14 is
exposed on the front surface 17 of the finished security
substrate 16. In the case of a well consolidated low
permeable tape 14 the restricted drainage results in few or
no fibres 21 being deposited on the back surface of the tape
14, although fibres 21 will continue to accumulate adjacent
to the tape 14, with the result that the tape 14 is also
substantially exposed on the back surface 18 of the finished
security'substrate 16. In this case an additional paper
layer may be applied to the back surface 18 of the security
substrate 16 to cover,the exposed back surface of the tape
The additional layer can be applied by a separate
30..'-laminatz'on process or produced parallel to the production of
the main substrate on a short former and brought together in
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the wet section of the paper machine. In the case where a
high permeable fibrous tape 14 contacts the mould cover
prior to entry into the vat 20 the drainage will not be
restricted and fibres 21 will be deposited on the back
surface of the tape 14.
In yet another alternative embodiment a well
consolidated low permeable fibrous tape 14 is incorporated
into the base substrate 15 in the same manner as that
described for elongate elements in EP-A-00059056. The
technique involves embossing the cylinder mould cover 23 to
form raised regions and bringing the tape 14 into contact
with the raised regions of the mould cover 23, prior to the
contact entry point into a vat of aqueous paper stock 21.
Where the low permeable tape 14 makes intimate contact with
the raised regions of the embossing, no fibre deposition can
occur and windows are formed in the front surface of the
base substrate 15. After the finished substrate 16 is fully
formed and couched from the cylinder mould cover 23, water
is extracted from the wet fibre mat and the finished
substrate 16 is passed through a drying process. In the
finished substrate 16 the regions of the tape 14 which are
exposed in the windows are visible in reflected light when
viewed from the front surface 17 of the substrate 16.
Figures 4 to 13 show a number of embodiments of
different security documents produced from a security
substrate 16 made by the method of the present invention.
Figures 4 and 5 show a'document made from the finished
security substrate 16 in which a tape 14 is embedded within.
the base substrate 15 such that one surface of the tape 14
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is exposed at the back surface 18 of the finished security
substrate 16. In this example the tape 14 comprises a
security feature 11 in the form of a multitonal pictorial
watermark 11a. The tape 14 is made from the same furnish as
the base substrate 15 and therefore the finished security
substrate 16 has a uniform appearance.
Figure 6 shows an alternative embodiment in which the
tape 14, exposed at the back surface 18 of the finished
security substrate 16, is made from a different coloured
furnish to the base substrate 15 and is therefore clearly
observable within the finished security substrate 16. In the
example shown in figure 6 the tape 14 also comprises a
plurality of security features ll,.in the form of a multi-
tonal watermark 11a and a single tone light.electrotype
watermark llb.
In the embodiments shown in Figures 4 and 6 the tape 14
is preferably made from a well consolidated low permeable
paper such that it restricts drainage during papermaking and
is subsequently exposed on the back-surface of the finished
security substrate 16. Alternatively if the tape 14 is made
from a high permeable paper it will not significantly
restrict drainage resulting in it being wholly embedded
within the substrate. The use of an embedded paper tape 14
enables one or both of the watermarks 11a, 11b to be
positioned in the middle of the document and therefore less
susceptible to damage in.circulation.
In Figure 7 the finished security substrate 16
com rises a well consolidated low permeable paper tape14,
p
which contains a security'feature 11 ifn the form of a
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partially embedded security thread lid that is exposed in
windows 30. The tape 14 is incorporated into the base
substrate as described with reference to Figure 3a with the
windows 30 facing away from the mould cover 23 such that the
tape surfaces on the back surface 18 of the finished
security substrate 16, which is the surface shown in Figure
7. As the tape 14 surfaces on the back surface of the
finished security substrate 16 the windows 30 are not
covered by the fibres of the base substrate 15 and the
optical characteristics of a traditional windowed thread lld
are maintained. Between the windows 30 are bridges 31 that
cover the security thread 11d. The bridges 31 of paper have
an increased grammage compared to the main body of the tape
14, and conversely the paper on either side of a windows 30
has an area 32 of reduced grammage compared to the main body
of the paper sheet made from the base substrate 15. When
viewed in transmission, as shown in Figure 7a, the thread
11d can be seen as a dark vertical strip running through a
series of alternate horizontal dark and light tracks with
the bridges 31 appearing darker than the main body of the
document formed from just the base substrate 15. The areas
32 adjacent to the windows 30, with reduced grammage, appear
lighter. The alternating dark and light regions make up what
is known as a thread track.
The windowed security thread lld can comprise a range
of functional properties in order to enhance the security
associated with a traditional windowed security,thread'and
well known to those skilled in the art. Public security
threads include thos,e having demetallised designs; thin film
interference structures, liquid crystallayers;thermochromic layers,
photochromic
layers,.iridescent
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layers, multiple different coloured metal layers,
holographic and diffractive structures and print layers. The
use of security threads with covert properties is also
applicable to the current invention and examples include
those with magnetic properties, luminescent properties,
conductivity or other machine detectable characteristics.
The tape 14 illustrated in Figure 7 can be made from
the same furnish as the base substrate 15 with the finished
security substrate 16 appearing substantially uniform apart
from the windowed thread lld. In an alternative embodiment
the furnish of the tape,14 is of a different colour to the
base substrate 15, as illustrated in Figure 8. When the
document is viewed in reflection, from the same side as the
surfacing tape 14, a coloured stripe is observed in the
middle of which is a windowing polymeric thread. The colour
of the tape provides additional security as well as
attracting the attention of the general public to the
security thread lid. In alternative embodiments the tape 14
may be coloured by a conventional printing process prior to
insertion into the base substrate 15. A conventional
printing process enables a design to be applied to the tape
14 rather than an all-over colouring.
Small perforations may be added to the tape 14 on
either.side of the polymeric thread to enable drainage
during papermaking and therefore allow fibres to form on the
bottom surface of the tape 14 in,the non-window regions.
I-n'afurther embodiment a co;loured.ink or coating which
containsa'component that becomes mobkle when wetted could
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be applied to the tape 14. The tape 14 is rewetted when it
is inserted into the vat 20 during the production of'the
base substrate 15. On rewetting the tape 14 the mobile
component of the ink migrates through the tape 14. The
extent of the migration of the mobile component will be
dependent on the thickness of the paper of the tape 14 and
therefore regions of different paper thicknesses will appear
to have a different colour or shade of colour.
A cross-section of a tape 14 incorporating a polymeric
security thread 11d exposed in windows 30 on one surface is
shown in Figure 9. A layer 33 of coloured ink containing a
mobile and non-mobile component is applied to the opposite
surface of the tape 14. In one example the tape 14 could be
printed with an orange ink containing a non-mobile green
component and a mobile red component. On rewetting the tape
14 the red component will migrate through the tape 14 and
will be visible at a higher concentration in the low
grammage light regions of the thread track compared to the
high grammage thread bridges 31. The final document will
comprise a thread track with two alternating colours along
the track.
Figure 10 shows an example of a secure document
comprising a well consolidated low permeable tape 14 in
which the tape 14 comprises a first security feature 11 in
the form of patterned holes llc, which provide identifying
information, and a second security feature in the form.of 'a
traditional multi-tonal watermark 11a. The holes 11c in the
tape 14 can be created during the original papermaking,
process by blinding or sealing the cylinder mould cover 23.,
Alternatively the holes 11c can be created,by perforating
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the tape 14 after it has been formed, prior to incorporating
it into the base substrate 15. Examples of methods of
perforating the tape include stamping, die-cutting and laser
cutting.
In another preferred embodiment, the security feature
11 of the tape 14 comprises identifying information in the
form of patterned holes lic such as stars, and the tape 14
is made from a low permeable paper produced from a different
coloured furnish to the base substrate 15. The holes llc are
formed during the paper making process for the tape 14 by
blinding the cylinder mould cover 23 on which the paper
fibres 21 are deposited. If the base substrate 15 is
substantially white and the tape 14 is a shade of blue, then
on viewing the base substrate 15 in reflection, from the
exposed tape 14 side, a blue strip will be observed
comprising white stars. However, because the white fibres
from the base substrate 15 fill the holes 11c of the tape 14
and form a fibrous layer on the tape around the perimeter of
the holes 11c, the edge of the holes lic appear blurred and
poorly defined when viewed in reflection. The fact that the
presence of the white fibres around each hole 11c can be
identified with the naked eye against the blue background of
the tape 14 provides an additional security benefit. A
counterfeiter simply printing white stars on a blue
background cannot replicate this blurred fibrous edge. In
contrast, on viewing the document in transmission, as shown
in Figure ll, a sharp image of the stars can be clearly seen
against the background of the,'coloured tape. The fact that
e 14,1s ~of a.different colour to.the base substrate
the tap
. ,.;. , ., ..,. ~~ ' 15 provides additional.s,
ecurity and substantially increases
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the contrast for the patterned holes/perforations 11c when
viewed in transmissive light.
Alternatively, the tape 14 can be made from the same
colour furnish as the base substrate 15, but differ in
another characteristic such as porosity, opacity or density.
In this case the identifying information formed from the
outline of the holes 11 will be virtually invisible in
reflected light, but easily distinguishable in transmitted
light.
In yet a further embodiment, the paper tape 14
comprises an array of small circular perforations 11c
arranged to form the numeral 5 as shown in Figure 12. In
this example the tape 14 is made from a low permeable paper
produced from a furnish with a lower opacity than the base
substrate 15. The perforations 11c are formed during the
paper making process for the tape 14 by blinding the
cylinder mould cover 23 on which the paper fibres 21 are
deposited. The patterned tape 14 is subsequently
incorporated into the base substrate 15 as described with
reference to Figure 3a. Some fibres from the base substrate
15 form in the perforated regions 11c of the tape 14 and
slightly overlap the edges of the perforations such that
when viewed in reflection the perforated regions lic are not
clearly defined and a virtually imperceptible "blurred".
image of the number "5" is present, as shown in Figure 12.
However on viewing in transmission, the presence of the tape
14 is immediately noticeable due to the difference in'
to the base substrate 1,5',an
' opacity compared d,the perforat,ed
reglons 11c of the tape 15 are clearly defined within .the
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tape 15 as sharp circles defining the numeral "5", as shown
in Figure 13.
An additional benefit of the perforations 11c in a low
permeable tape 14 is that it increases the adhesion of the
tape 14 to the base substrate 15 due to the fact there are
substrate fibres present on both sides of the tape 14.
Without the perforations 11c the fibres from the base
substrate 15 would only be attached to one surface of the
tape 14, i.e. the surface that is not exposed on the back 18
of the security substrate 16. However with the perforations
llc present, the fibres from the base substrate 15 fill the
perforations llc and become attached to the tape 14 on the
opposite side of the tape 14. A preferred embodiment to
enhance adhesion between a low permeable tape 14 and a
fibrous base substrate 15 comprises a series of perforations
along one or both long edges of the tape 14. Alternatively
there could be a series of perforations along the middle of
the tape, or an array of perforations covering the whole
surface of the tape 14. Experimental work has shown that the
adhesion of the tape 14 to the base substrate 15 is
optimised if the perforations are of a size in the 0.5 - 2mm
wide by 0.5 - 4mm long and the space between the
perforations is in the range 1-3mm.
A further advantage of the embodiments utilising a
perforated tape'14 is that the perforations l1c assist in
the dewatering of the security substrate 16 on papermaking
machines without sophisticated double felt presses.
30,
Tn,a further embodiment'of the current invention the
tape 14, made from a low permeable paper, comprises a first
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security feature 11 in the form of one or more holes 11c.
The holes 11c in the tape 14 can be created during the
original papermaking process by blinding or sealing the
cylinder mould cover 23. The tape 14 is then incorporated
into the base substrate 15 in combination with a
conventional elongate impermeable element 40 such that the
elongate impermeable element 40 contacts the cylinder mould
cover 23 through the holes llc in the tape 14 and thereby
the regions 41 of the elongate impermeable element 40,
coincident with the holes 11c in the tape 14, surface on the.
front side 17 of the finished substrate 16 forming windows.
The regions 42 of the elongate polymeric element 40 not
coincident with the holes llc in the tape 14 and positioned
on the surface of the tape 14 away from the mould cover 23
will surface on the back side 18 of the base substrate 15 as
no fibres will deposit over the low permeable paper tape 14.
In this manner the elongate impermeable element 40 is
exposed in one or more windows on both the front and back
side 17, 18 of the finished substrate 16.
Figures 14 to 18 illustrate an embodiment of the
present invention which enables the incorporation of an
elongate impermeable element 40 such that it is exposed at
windows in both surfaces 17,18 of the finished substrate 16.
A fibrous tape 14 made from a low permeable paper comprises
a first security feature 11 in the form of a series.of holes
11d positioned along the tape 14. The holes 11c are formed
during the paper mak,ing process for the-tape 14 by blinding
the cylinder mould cover 23 on which the paper fibres are
deposited
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The tape 14 is incorporated into the base substrate 15
as shown in Figure 14. In this example the tape 14 and the
base substrate 15 are made from the same furnish 21. The
tape 14 is combined with an elongate impermeable element 40
immediately before the tape 14 contacts the cylinder mould
22. The elongate impermeable element 40 and tape 14 are
brought together such that the elongate element 40 contacts
the tape 14 on the side of the tape 14 away from the
cylinder mould cover 23. The elongate impermeable element 40
is positioned such that it lies across one or more of the
holes lic in the tape 14. The combined structure is then
brought into contact with the cylinder mould cover 23
(Figure 15) prior to the cylinder mould 22 entering the
liquid in the vat 20 with the result that the tape 14 is
exposed on the front surface 17 of the finished security
substrate 16 (Figure 16). Furthermore the regions 41 of the
elongate impermeable element 40 lying across the holes 11c
in the tape 14 also contacts the cylinder mould cover 23 and
likewise are exposed on the front surface 17 of the finished
security substrate 16. In the case of a well consolidated
low permeable tape 14 the restricted drainage results in few
or no fibres 21 being deposited on the back surface of the
tape 14, although fibres 21 will continue.to accumulate
adjacent to the tape 14, with the result that the tape 14 is
substantially exposed on the back surface 18 of the finished
security substrate 16. Fibres forming the base substrate 15
will continue to form in the holes llc in the tape 14.
If the elongate impermeable element 40 is sufficiently
narrow not to interfere with,fibre deposition then fibres'21
will also from,over regions 41 of the impermeable elongate
element 40 such that it is only exposed on the front side'17
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of the final substrate 16 (Figure 16). This results in the
elongate impermeable element 40 being exposed in alternate
windows on the front and back of the finished substrate 16
as shown in Figure 17 (Front) and Figure 18 (Back). In order
to allow fibre deposition the impermeable elongate element
40 will preferably have a width less than 3mm, and more
preferably less than 2mm.
Alternatively if the elongate element 40 is
sufficiently large to interfere with fibre deposition as
they are too wide to be bridged by the fibres 21, regions 41
of the impermeable element 40 will be exposed on both the
front and back surface 17, 18 of the final substrate 16
(Figures 19 and 20). In this case the impermeable elongate
element 40 preferably has a width greater than 3mm and even
more preferably greater than 6mm.
For the embodiments described with reference to Figures
14 to 20 the tape 14 and the elongate impermeable element 40
may be delivered into the papermachine in a number of ways.
In one method the tape 14 and the elongate impermeable
element 40 will be delivered on separate rolls with guide
reels being used to ensure they are brought into contact at
the correct point. Alternatively the tape 14 and the
elongate impermeable element 40 may be brought into contact
in a separate step prior to the papermaking process.and
delivered into the papermachine from the same roll. Although
not.essential an adhesive layer can be used to bond the tape.
14 to the elongate impermeable element 40, this adhesive
.bond could be formed prior to entry into the papermachine,
for'example using an adhesive lamination process, orduring
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the papermaking process using a moisture or heat activated
adhesive.
In a preferred embodiment the elongate impermeable
element 40 is incorporated into the fibrous tape 14 during
its fabrication. This can be achieved using the method of
making fibrous substrates described in WO-A-04001130. The
tape 14, illustrated in Figures 21 and 22 viewed from the
front surface 45 and back surface 46, comprises a partially
embedded elongate impermeable element 40 and one or more
holes llc which expose both surfaces of regions 43 of the
elongate impermeable element 40. The tape 14 also comprises
traditional windows 30, as described in EP-A-0059056, in
which only one surface of regions 44 of the security element
40 are exposed.
The method of manufacturing the low permeable tape 14
illustrated in Figures 21 and 22 is shown in Figure 23. A
porous support surface, for example in the form of a
cylinder mould cover 23, is produced in a known way. The
mould cover 23 has a plurality of drainage restriction
regions 47. These can, for example, be provided by fixing a
blinding material to the mould cover 23. The blinding
material is typically a metal which is welded to the
cylinder mould cover 23. Other suitable blind materials are
wax, polymer or any other material which can be securely
attached to the cylinder mould cover 23 to prevent drainage
of water from fibrous stock 21 and hence fibre deposition.
These drainage restriction regions define the shape of the'
holes 11c formed in the tape 14.
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The cylinder mould cover 23 also comprises embossed
raised regions 48 which are used to generate the
conventional windows 30. The elongate impermeable element 40
is brought into contact with both the raised regions 48 and
drainage restricted regions 47 on the mould cover 23 prior
to the contact entry point into a vat 20 of aqueous paper
stocka Where the elongate impermeable element 40 makes
intimate contact with the raised regions 48 of the
embossing, no fibre deposition can occur and windows 30 are
formed in the front surface 47 of the paper tape 14 that was
in contact with the mould cover 23.Assuming that the
impermeable elongate element 40 is not sufficiently wide to
prevent fibre deposition, fibres 21 will be deposited over
the impermeable element 40 in contact with the raised
regions 48 such that it will not be exposed on the back
surface 48 of the paper tape 14. In the drainage restricted
regions 47 there is little or no covering of fibres 21.
However in the flat freely draining regions fu11 fibre
coverage is obtained. Thus when the substrate used to form
the paper tape 14 is removed from the cylinder mould 23 the
elongate impermeable element 40 is exposed from both sides
of the tape 14 in the holes llc corresponding to the
drainage restrictive regions and exposed from one surface of
the paper tape 14 in the windows 30 corresponding to the
raised embossed raised regions 48. In the regions between
the windows 30 and the holes llc the elongate element 40 is
wholly embedded within the tape 14.
The low permeable tape 14, illustrated in Figures 21
and,22,i.s.then incorporated into the base substrate 15 as
de
d,with reference
scribe' eference to.Figure 3b, prior tothe cylinder
mould 22 entering the liquid in thevat 20, with the
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conventional windows 30 facing away from the mould cover 23.
The tape 14 is exposed on the front surface 17 of the
finished security substrate 16. Furthermore the regions 43
of the elongate element 40 lying across the holes llc in the
tape 14 also contact the cylinder mould 23 and likewise are
exposed on the front surface 17 of the finished security
substrate 16 (Figure 24). If the elongate impermeable
element 40 is sufficiently narrow not to interfere with
fibre deposition then fibres 21 will also from over regions
43 of the impermeable elongate element 40 such that it is
only exposed on the front side 17 of the final substrate 16.
Fibres forming the base substrate 15 will continue to form
in the holes 11c in the tape 14. As the tape 14 is of low
permeability it is also exposed on the back surface 18 of
the finished security substrate 16 and therefore the
conventional windows 30 are not covered by the fibres of the
base substrate 15 and therefore regions 44 of the security
element 40 are exposed on the back surface 18(Figure 25).
The inventive method, for the incorporation of an
elongate impermeable element 40 into a base substrate 15
such that it windows on both surfaces, described in the
various embodiments in Figures 14 to 25, allows total
control of the degree and position of exposure of the
elongate impermeable element 40 within the security
substrate 16. For example the elongate impermeable element
40 can be exposed on both surfaces of the final substrate.16
in an alternating manner (Figures 15 to 18), or coincident
manner (Figures 19 and 20), or where the elongate
impermeable element 40 can be exposed in a plurality of
windows 30 on one'surface and only a single window 30 on...the,
second surface (Figures 24 and 25).
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Thus, substrates 16 made according to the present
invention are advantageous in that it is possible to
increase the exposure of the elongate element 40, not just
on one surface of the substrate 16, but two sides, which
means that it can be used to its best extent. This is
important because such elongate impermeable elements 40 can
be expensive to provide.
The elongate impermeable elements 40 are preferably
made of clear polyester, although other materials may be
used, such as polyethylene or polypropylene, and may have a
constant or variable width. The elongate impermeable
elements 40 typically have a layer of adhesive, which help
the embedment within the tape and/or final substrate 16.
The elongate elements 40 can incorporate a wide variety
of known security features which may include the following:-
- a metallic layer, indicia or designs, which appear
dark, when the substrate is viewed in transmitted
light, compared to the lighter, partly light-
transmitting, substrate. When viewed in reflected
light, the shiny metallic parts will be clearly
seen in the windows;
- de-metallised indicia or designs, which may
comprise,areas of substantially removed metal to
take advantage of the transparency of the base
film a, nd provide a large area of transparent
wiridow;
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- holographic or diffractive designs, which may
comprise areas of full metal and half-tone screens
to provide partial transparency and/or no metal;
- front to back print registration, in which
features are printed which would clearly exhibit
Moire patterns from both front and back if a
counterfeit were attempted. Alternatively, such
patterns could be produced on a transparent film
prior to insertion of the element into the paper
as a security feature itself. The exact
reproduction of such patterns are very difficult
to mimic;
- luminescent, iridescent, thermochromic, liquid
crystal or magnetic materials;
- designs or indicia created by printed inks;
- dichroic materials which can have different
colours when viewed in transmission and refection,
for example as described in GB-A-1552853. These
materials are particularly useful where the
windows on the front and back of the substrate
coincide to form an aperture (as shown in Figure
16);
- thin film interference devices, as described in
EP-A-227423 or liquid crystal polymer films,or
liquid crystal pigmented inks, such as described
' .,.,, . , .
in EP-A-435029 or EP-A-863815:
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The elongate impermeable elements 40 may be oriented,
which means that each side of the element 40 may carry
different information, materials or optical effects.
Examples include:-
- holographic or diffractive materials on a first
side of the element, with a thin film
interference device on a second side;
- liquid crystal film over a black or dark
background on a first side and plain metal on a
second side;
- different coloured metals on each side, e.g.
aluminium on the first side and another metal
on the second side. Alternatively one or more
coloured transparent lacquers over a metal
layer could be used to create a variety of
colours;
- a magnetic micrometallised thread, such as
described in GB-A-2375078;
- repeating indicia or security features located
in either window or bridge regions on one or
both sides of the substrate.
Many other options are available'and with such a large
'exposed area of the element available, it is possible to
combine'many;;,sec orative features together , ... .,
urit dec on one
Y or
element 40.
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In all of the embodiments described, if the finished
security substrate 16 undergoes further standard security
printing processes, then the colour and/or design of the
tape 14 can be correlated to the design of the final printed
document. Standard security printing processes include one
or all of the following; wet or dry lithographic printing,
intaglio printing, letterpress printing, flexographic
printing, screen printing, and/or gravure printing. The
printed designs are preferably printed both on the substrate
and the exposed regions of the paper tape 14. The
patterns and designs on the security tape 14 and document
may be registered with each other, which makes it very
difficult to counterfeit.
