U.S. patent application number 12/936266 was filed with the patent office on 2011-03-10 for method of fabricating a sheet comprising a region of reduced thickness or of increased thickness in register with a ribbon, and an associated sheet.
This patent application is currently assigned to ARJOWIGGINS SECURITY. Invention is credited to Henri Rosset.
Application Number | 20110056638 12/936266 |
Document ID | / |
Family ID | 39828991 |
Filed Date | 2011-03-10 |
United States Patent
Application |
20110056638 |
Kind Code |
A1 |
Rosset; Henri |
March 10, 2011 |
METHOD OF FABRICATING A SHEET COMPRISING A REGION OF REDUCED
THICKNESS OR OF INCREASED THICKNESS IN REGISTER WITH A RIBBON, AND
AN ASSOCIATED SHEET
Abstract
A method of fabricating a sheet by papermaking, the sheet
including at least one ply of a fiber substrate and at least one
ribbon, wherein the ribbon is introduced in a fiber suspension of a
vat former papermaking machine enabling the ply to be formed; or in
direct contact with the vat former; or in contact with the
already-formed ply; the point at which the ribbon is introduced
being selected so as to create at least one region of increased
thickness or of reduced thickness in the sheet in register with the
ribbon, the reduced thickness being due to a reduction in the
de-watering of the fiber suspension caused by the ribbon.
Inventors: |
Rosset; Henri; (Le Pin,
FR) |
Assignee: |
ARJOWIGGINS SECURITY
Issy les Moulineaux
FR
|
Family ID: |
39828991 |
Appl. No.: |
12/936266 |
Filed: |
April 7, 2009 |
PCT Filed: |
April 7, 2009 |
PCT NO: |
PCT/FR09/50594 |
371 Date: |
November 4, 2010 |
Current U.S.
Class: |
162/109 ;
162/140 |
Current CPC
Class: |
D21H 21/42 20130101;
D21F 11/08 20130101; D21F 11/06 20130101 |
Class at
Publication: |
162/109 ;
162/140 |
International
Class: |
D21H 21/42 20060101
D21H021/42 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 11, 2008 |
FR |
0852472 |
Claims
1. A method of fabricating a sheet by papermaking, the sheet
comprising at least one ply of a fiber substrate and at least one
ribbon, wherein the ribbon is introduced: a) in a fiber suspension
of a vat former papermaking machine enabling the ply to be formed;
or b) in direct contact with the vat former; or c) in contact with
the already-formed ply; the point at which the ribbon is introduced
being selected so as to create at least one region of increased
thickness or of reduced thickness in the sheet in register with the
ribbon, the reduced thickness being due to a reduction in the
de-watering of the fiber suspension caused by the ribbon; at least
one security element being incorporated in the region of reduced
thickness, the security element being of thickness that is
compensated at least in part by the reduced thickness or being
juxtaposed with the ribbon at the region of increased thickness,
the security element presenting a thickness that is compensated at
least in part by the increased thickness.
2. A method according to claim 1, the ribbon being introduced with
one of its faces in direct contact with the vat former prior to the
ribbon penetrating into the fiber suspension.
3. A method according to claim 1, the ribbon being introduced into
the fiber suspension after fibers have already become deposited on
the vat former at the point where the ribbon is introduced.
4. A method according to claim 1, the ribbon being introduced in
contact with the formed ply of the fiber substrate.
5. A method according to claim 1, the ribbon being a fiber
ribbon.
6. A method according to claim 1, the paper ply formed on the vat
former and comprising the ribbon being united in the wet portion of
the papermaking machine with another paper ply that overlies the
ribbon.
7. A method according to claim 1, the paper ply formed on the vat
former and comprising the ribbon being united by pasting with
another paper ply overlying the ribbon.
8. A method according to claim 1, the ribbon having at least one of
its faces that is not completely covered by fibers of the fiber
suspension at the outlet from the vat former papermaking
machine.
9. A method according to claim 1, the ribbon presenting thickness
that is less than the thickness of the vellum of the sheet.
10. A method according to claim 1, the ribbon having thickness
greater than the thickness of the vellum of the sheet.
11. A method according to claim 1, the ribbon being subjected to
embossing, in particular hot embossing.
12. A method according to claim 1, the thickness reduction having a
value greater than or equal to 15 .mu.m.
13. A method according to claim 1, the increase in thickness having
a value that is less than or equal to 20 .mu.m.
14. A method according to claim 1, the ribbon being a paper
ribbon.
15. A method according to claim 1, the ribbon comprising non-fiber
elements.
16. A method according to claim 1, the ribbon having width lying in
the range 2 mm to 60 mm.
17. A method according to claim 1, the ribbon having a thickness
greater than 10 .mu.m.
18. A method according to claim 1, the ribbon comprising an
electronic device.
19. A method according to claim 1, the ribbon comprising at least
one adhesive.
20. A method according to claim 1, the ribbon being fabricated from
a material that has previously been subjected to wet strength
treatment.
21. A method according to claim 1, the ribbon comprising one or
more openings.
22. A method according to claim 1, the sheet comprising on either
side of the ribbon a region of reduced thickness in which there
extends at least part of at least one security element.
23. A method according to claim 1, the security element comprising
a film extending parallel to the ribbon and in contact
therewith.
24. A method according to claim 1, the ribbon comprising an
opening, the security elements being observable, showing through
the ribbon.
25. A method according to claim 1, at least one electronic device,
being received at least in part in the region of reduced thickness,
the thickness reduction compensating the thickness of the
electronic device, at least in part.
26. A sheet comprising a fiber substrate and a ribbon, at least one
security element being placed in register with the ribbon, and
presenting thickness that is compensated at least in part by a
difference in thickness between the ribbon and the vellum of the
sheet and/or by an opening in the ribbon.
27. A sheet according to claim 26, the ribbon being a fiber
ribbon.
28. A security document comprising a sheet as defined in claim 26.
Description
[0001] The present invention relates to the field of security
documents and among others it relates to a method of fabricating a
security sheet, e.g. made mostly of paper.
[0002] In this description, the term "paper" means any sheet
obtained by a wet method from a suspension of fibers of natural
cellulose and/or mineral, vegetable, or organic fibers other than
cellulose fibers, possibly synthetic fibers, and possibly
containing a variety of fillers and a variety of additives as
commonly used in papermaking.
BACKGROUND
[0003] When fabricating security documents, and in particular
security sheets, it is common practice to seek to incorporate one
or more security element, e.g. by applying a security film or
thread on a security sheet or by coating it with a strip of
iridescent coating, or indeed by creating windows in the security
sheet and applying a transparent film over the windows. This
generally leads to regions of increased thickness being created on
security documents that may give rise to problems of flatness of
security documents or indeed may make printing steps difficult, for
example.
[0004] Various solutions have been proposed seeking to reduce the
thickness of a security sheet locally where the security elements
are to be placed, during fabrication of the sheet on the vat former
of a papermaking machine. In most cases, the solution proposed
consists in closing off a portion of the forming fabric used during
the method of fabricating the security sheet on a vat former.
[0005] International application WO 99/06629 describes a method of
fabricating a sheet using a flat bed (Fourdrinier) papermaking
machine fitted with a textile fabric that enables zones of low and
high weight to be obtained.
[0006] International application WO 93/00474 also describes a
method of fabricating a security sheet using a flat bed
(Fourdrinier) papermaking machine fitted with a fabric having
pellets added thereto that reduce de-watering, thereby enabling
zones of different weights to be formed.
[0007] European patent application EP 0 625 431 describes a method
of fabricating a security paper including a security thread
fabricated from a film and incorporated between two plies.
[0008] European patent application EP 0 549 384 describes a method
of fabricating a paper that comprises zones of reduced thickness
obtained by securing pellets to the forming fabric of the vat
former.
[0009] European patent application EP 1 122 360 describes a method
of fabricating a paper in which a watermark is made from
modifications made on the forming fabric of the vat former.
[0010] British patent application GB 2 433 469 describes
fabricating a fibrous security substrate having incorporated
therein a fiber ribbon including a plurality of openings.
[0011] European patent application EP 0 070 172 describes a method
of fabricating a security paper including a ribbon that presents
alternating zones enabling papermaking fibers to be deposited and
zones preventing papermaking fibers being deposited.
[0012] European patent application EP 0 773 320 describes inserting
a strip between two papermaking plies, one of which comprises a
watermark.
[0013] British patent application GB 2 395 724 describes
incorporating a polyester strip including an electronic chip in a
fiber substrate.
[0014] The solutions proposed in the prior art do not enable zones
of reduced thickness to be obtained in a security document by means
of a method that is relatively simple. The solutions proposed
require modifications and significant preparation of the forming
fabrics used on vat formers and they generally do not make it
possible to obtain thickness reductions of dimensions that are
sufficient for incorporating the above-mentioned security
elements.
SUMMARY
[0015] Consequently there exists a need to remedy at least some of
the above-mentioned drawbacks.
[0016] In particular, there exists a need to improve the
fabrication of security documents, in particular security sheets,
in particular for making zones of varying thickness in the
documents.
[0017] The invention seeks to satisfy these needs in full or in
part by incorporating a ribbon, optionally a fiber ribbon, in a
security sheet while it is being fabricated, the ribbon
advantageously being suitable for being located at or close to a
location where security elements are to be applied.
[0018] Thus, in one of its aspects, the invention provides a method
of fabricating a sheet by a papermaking technique, the sheet
comprising at least one ply of a fiber substrate and at least one
fiber ribbon, where the ribbon is introduced into a fiber
suspension of a vat former papermaking machine enabling the ply to
be formed or is introduced directly into contact with the vat
former, or in contract with the formed ply, in particular prior to
the ply leaving the lifting cylinder.
[0019] The point at which the ribbon is introduced may be selected
so as to create at least one region of reduced thickness or of
increased thickness in the sheet in register with the ribbon, e.g.
when it emerges from the fiber suspension or subsequently, the
thickness reduction being due to a reduction in the de-watering of
the fiber suspension caused by the ribbon.
[0020] By means of the invention, it is possible to obtain a
security sheet that presents at least one region of reduced
thickness or of increased thickness that is suitable for enabling
security elements to be incorporated without requiring the use of a
forming fabric that is modified or specific, in particular as a
result of using a fiber ribbon that is incorporated in the fiber
substrate during fabrication of the security sheet. As a result, it
is possible to use the forming fabrics that are normally fitted to
vat former papermaking machines that are used for fabricating
security sheets.
[0021] Furthermore, the use of a ribbon presenting varying width
and/or thickness may enable regions of reduced thickness or
increased thickness to be obtained that are likewise of varying
dimensions, for example.
[0022] The resulting regions of reduced thickness or of increased
thickness may extend all along the sheet.
[0023] The ply carrying the ribbon need not partially overlie the
ribbon, i.e. the fiber substrate does not cover the side portions
of the ribbon on its main faces on either side thereof over a
substantial width, e.g. greater than or equal to 1 mm.
[0024] By means of the invention, it is possible to incorporate one
or more security elements of any type in the security sheet close
to or in register with the regions of reduced thickness or
increased thickness without that giving rise locally to regions of
increased thickness associated with the presence of the security
element(s), for example. A region of reduced thickness may for
example make it possible to incorporate in register therewith at
least one security element of thickness that may be compensated, at
least in part, by the reduced thickness. A region of increased
thickness may, for example, make it possible to juxtapose at least
one security element with the ribbon, with the thickness thereof
being compensated at least in part by the increased thickness.
[0025] The invention also makes it possible to provide novel
security structures, independently of any thickness compensation as
mentioned above.
[0026] The ribbon may be introduced into the fiber suspension or it
may be put into direct contact with the vat former in various
ways.
[0027] The term "direct contact" is used to mean that the point
where the ribbon is introduced is in contact with the vat former
where it is not covered in fibers of the fiber suspension at the
point where the ribbon is introduced. In particular, the point of
introduction may be located in a zone of the vat former that is not
immersed in the fiber suspension. Preferably, and where
appropriate, the cohesion of the sheet that is formed may be
provided by a second fiber ply suitable for being placed adjacent
to the first ply to be formed and in particular on the face that
was in contact with the forming fabric during formation
("underside").
[0028] The fiber ribbon may be introduced with one of its faces in
direct contact with the vat former, prior to penetrating into the
fiber suspension. This ensures that none of the fibers of the fiber
suspension can be deposited on the face of the ribbon that is in
contact with the vat former. This serves to obtain a paper ply
having the face of the ribbon that was in contact with the vat
former visible on one of its faces. Under such circumstances, a
region of reduced thickness may be made in register with the other
face of the ribbon, the face facing away from the vat former.
[0029] The ribbon may also be introduced into the fiber suspension
at a ribbon introduction point where fibers are already deposited
on the vat former. The fibers may already be deposited on the vat
former over the entire surface thereof or over part of its surface.
As a result, it is possible that no face of the ribbon comes into
direct contact with the fabric of the vat former. The ribbon may on
the contrary have one of its faces in contact with fibers that have
already been deposited on the vat former prior to the ribbon being
introduced into the fiber suspension. Thus, the face of the ribbon
in contact with the fibers already deposited on the vat former need
not be observable on the security sheet after fabrication. Under
such circumstances, a region of thickness that is reduced or
increased relative to the thickness of the vellum, i.e. the
thickness of the zone of the sheet that does not comprise the
ribbon, in particular the thickness of the substrate, may be made
in register with the other face of the ribbon, the face facing away
from the vat former.
[0030] The face of the ribbon that is in direct contact with the
vat former or with fibers in the fiber suspension that have already
been deposited on the vat former may obstruct holes in the forming
fabric of the vat former and may thus prevent fibers being sucked
against the fabric from the fiber suspension.
[0031] The ribbon may be introduced into a two-ply papermaking
machine. Under such circumstances, the papermaking machine may, for
example, have two vat formers placed in line, or one vat former and
a flat bed, or indeed one vat former and a short former. In
particular, the ply of paper formed on the vat former and
comprising the ribbon may be united in the wet portion of the
papermaking machine with a second ply of paper that comes to
overlie the ribbon. The second ply may then serve to consolidate
the first ply of paper in the zone where the ribbon is introduced.
It may also constitute protection for elements present on or in the
ribbon, e.g. an electronic device, and in particular an integrated
microcircuit device, e.g. a radiofrequency identification (RFID)
device.
[0032] It is also possible to use a papermaking machine fitted with
a single vat former.
[0033] The ribbon may be introduced via a feeder device, e.g. such
as an unreeling system placed along the width of the vat and
leading into the vat close to the vat former, prior to the
beginning of de-watering the fiber suspension on the fabric of the
vat former. After de-watering, a security sheet is obtained that
may subsequently be pressed and then dried using the conventional
papermaking method.
[0034] The ply that is obtained may optionally be married in the
wet state, i.e. before drying, with other plies having fiber
compositions that may be identical or different and that may be
formed on flat bed (Fourdrinier), short former, or vat former
papermaking machines.
[0035] The ply that is obtained may be united by pasting with
another ply of paper that comes to overlie the ribbon.
[0036] The sheet may be fiber constituted by two plies of paper,
each comprising a ribbon with one or both of the sheets presenting
at least one region of reduced thickness or of increased thickness
in register with the ribbon. The two ribbons of the two plies may
optionally be in contact with each other after the plies have been
assembled together.
[0037] Advantageously, the ribbon may be introduced in the forward
direction of the sheet, thus making it easy to introduce any
security elements, where such elements are typically introduced in
the same direction during a method of fabricating a security
sheet.
[0038] The ribbon may have at least one of its faces that is not
entirely covered by fibers of the fiber suspension on leaving the
vat former papermaking machine.
[0039] The creation of a region of reduced thickness or of
increased thickness may result in fibers from the fiber suspension
being deposited in part only or not at all on at least one of the
faces of the ribbon. This may depend in particular on the angle at
which the ribbon is introduced, on its thickness, on a coating
present on its surface, and/or on a portion in relief present on
the vat former.
[0040] The thickness of the ribbon may be greater than or less than
the thickness of the vellum of the security sheet.
[0041] When the ribbon has thickness that is less than the
thickness of the vellum of the sheet in which the ribbon appears,
the sheet may present reduced thickness in register with the
ribbon, in particular in register with the face of the ribbon that
faces away from the vat former, in particular when the ribbon is
inserted in direct contact with the vat former or when the ribbon
is inserted into the fiber suspension where the thickness of the
fibers already present on the vat former is less than the
difference in thickness between the thickness of the vellum of the
sheet and the thickness of the ribbon.
[0042] In a variant, the sheet may present a region of increased
thickness in register with the ribbon, e.g. when the ribbon is
inserted into the fiber suspension at a point where the thickness
of fibers already present on the vat former is greater than the
difference in thickness between the thickness of the vellum and the
thickness of the sheet.
[0043] When the ribbon presents a thickness that is greater than
the thickness of the vellum of the sheet, the sheet may present
increased thickness in register with the ribbon, in particular in
register with the face of the ribbon that faces away from the vat
former.
[0044] As mentioned above, the deposit of fibers on one of the
faces of the ribbon, in particular its face facing away from the
vat former, may be non-existent because the presence of the ribbon
against the fabric of the vat former prevents de-watering, i.e.
prevents from the fiber suspension becoming deposited against the
fabric.
[0045] The deposit of fiber on one of the faces of the ribbon, in
particular the face facing away from the vat former, may also be a
partial deposit only, in particular because the ribbon may have
been previously treated, e.g. with a coating so as to reduce its
porosity, thereby preventing or slowing down the deposition of
fibers on the treated zone. By way of example, the treated zone may
correspond to the central zone of the ribbon, in particular on its
face facing away from the vat former.
[0046] The treatment of the zone may, for example, be the result of
applying a coating such as a composition comprising a hydrophobic
and/or pore-filling compound. By way of example, this application
may consist in a taking of latex or of a hydrophobic varnish.
[0047] The vat former need not have any portions in relief on which
the ribbon is placed, or in a variant it may comprise some. Where
appropriate, a portion in relief may be formed by embossing the
forming fabric. For example, the ribbon may be introduced in such a
manner that its center coincides with the center of the portion in
relief on the vat former.
[0048] By way of example, relief on the vat former may present a
shape in face view that is square, round, oval, or polygonal, with
outlines that are rectilinear or curvilinear, and it is preferably
rectangular. The portion in relief may be continuous or
discontinuous along the circumference of the vat former. The ribbon
may be of a width that is greater than that of the portion in
relief. As a result, it is possible for example to have at least a
portion of the ribbon, in particular both edges of the ribbon, not
overlying the portion in relief.
[0049] The ribbon may be introduced where fibers from the fiber
suspension are already deposited on the portion in relief of the
vat former. As a result, the ribbon need not come directly into
contact with the portion in relief of the vat former, since one of
its faces comes into contact with fibers that have already been
deposited on the vat former.
[0050] In a variant, the ribbon may be introduced where no fibers
from the fiber suspension have been deposited on the portion in
relief of the ribbon, in particular at the point where the ribbon
is introduced. As a result, one of the faces of the ribbon may come
directly into contact with the portion in relief on the vat former,
which face may be visible on the security sheet after it has been
fabricated.
[0051] When the vat former comprises a portion in relief and the
ribbon is wider than the portion in relief, then the fibers from
the fiber suspension may be deposited between the vat former and
the portion(s) of the ribbon that do not overlie the portion in
relief. As a result, it may be possible to create one or more
regions of reduced thickness in the sheet in register with the face
of the ribbon that faces the vat former. Under such circumstances,
it may also be possible to create one or more regions of reduced
thickness or of increased thickness in register with the face of
the ribbon facing away from the vat former, in particular as a
function of the thickness of the ribbon compared with the thickness
of the vellum of the sheet.
[0052] The presence of one or more regions of reduced thickness or
of increased thickness may make it possible to receive one or more
security elements, at least in part, either overlying said regions
or juxtaposed therewith. In particular, the security elements may
be placed between two regions of increased thickness, thereby
providing them with mechanical protection, e.g. against impacts,
printing such as copper-plate printing, or subsequent pressing or
lamination steps.
[0053] When the thickness of the security elements is substantially
identical to the difference in thickness between the thickness of
the vellum of the sheet and the thickness of the ribbon, it is
possible to obtain a security sheet that presents substantially no
regions of reduced or increased thickness.
[0054] In particular, the security sheet may comprise at least one
security element overlying the ribbon on the reduced thickness side
and presenting a thickness that is compensated at least in part by
the reduced thickness. The reduced thickness may completely
compensate the thickness of the security element.
[0055] Also in particular, the security sheet may comprise at least
one security element juxtaposed with the ribbon and of thickness
that is compensated at least in part by a region of increased
thickness. The increased thickness may compensate the thickness of
the security element completely.
[0056] The regions of increased thickness may for example serve to
obtain particular security effects as a result of applying
treatment to the fiber ribbon, e.g. embossing in register with the
regions of increased thickness.
[0057] The ribbon may be treated in the regions of increased
thickness to obtain a security sheet that presents substantially no
reduced thickness or increased thickness.
[0058] The ribbon may for example be subjected to embossing, in
particular hot embossing, in particular in register with a region
of increased thickness. Under such circumstances, the ribbon may
preferably comprise polyethylene fibers. Introducing a ribbon
comprising polyethylene fibers makes it possible in particular
subsequently to create particular portions in relief by hot
embossing while imparting better cohesion to the sheet since the
cohesion of a cellulose substrate is better than that of a
substrate made up of polyethylene fibers, for example.
[0059] The ribbon may present a region of increased thickness, in
particular prior to optional embossing of the ribbon, that extends
over at least 50%, better 80% or even more of the surface of the
face of the ribbon where the region of increased thickness appears.
The region of increased thickness may extend over all of one face
of the ribbon.
[0060] After embossing, the sheet need not have any region of
increased thickness. The surface of the face of the ribbon that
presented increased thickness prior to embossing may be
substantially plane.
[0061] The ribbon may present portions in micro-relief, e.g.
indentations or projections, in particular after it has been
embossed, and these portions may be of small dimensions, e.g. lying
in the range 1 micrometer (.mu.m) to 3 .mu.m. These portions in
micro-relief do not form a region of increased thickness or reduced
thickness in the meaning of the invention.
[0062] The reduced thickness or increased thickness may make it
possible to obtain respectively a setback or a projecting portion
in relief of the security sheet presenting a dimension of the order
of several micrometers. Where appropriate, the reduced thicknesses
or the increased thicknesses may be of values that are determined
depending on the thicknesses of the security elements that are to
be associated therewith. For example, printing or a security film
may be deposited in a region of reduced thickness or between two
regions of increased thickness. The looked-for purpose may in
particular be obtaining a finished sheet that is flat, i.e. that
comprises no regions of reduced thickness or of increased
thickness.
[0063] The thickness reductions that are obtained may for example
have values that are greater than or equal to 15 .mu.m, preferably
greater than or equal to 30 .mu.m, more preferably greater than or
equal to 60 .mu.m. For example, it is possible to obtain thickness
reductions that are greater than or equal to 44 .mu.m for a
substrate presenting thickness that is greater than or equal to 115
.mu.m.
[0064] The regions of increased thickness may be a function of the
point of introduction of the ribbon and of its thickness. For
reasons of machineability, it may be advantageous to limit regions
of increased thickness to less than 20 .mu.m even though the
protection of certain security elements may require thicker regions
of increased thickness.
[0065] The ribbon may also be introduced by bringing the ribbon
into contact with the papermaking ply present on the fabric of the
vat former at the outlet from the forming vat. By way of example,
the ribbon may be inserted between the ply leaving the forming vat
and a second ply that is assembled with the first between the
lifting cylinder and the vat former.
Ribbon
[0066] The term "ribbon" designates a ribbon made as a single piece
or made as an assembly, a stack, or a juxtaposition of strips or of
individual parts.
[0067] Advantageously, the fiber ribbon is a paper ribbon.
Introducing a paper ribbon, as contrasted with introducing a
plastics ribbon, for example, may enable a sheet to be obtained
that presents good cohesion because of the bonds that may develop
between the paper ribbon and the substrate. In particular, when a
second ply is applied to the ribbon, the fact that the ribbon is
made of paper, and not of a plastics material, for example, may
provide strong cohesion between the ribbon and the second ply.
[0068] The ribbon may be a fiber ribbon and it may comprise
non-fiber elements.
[0069] The ribbon may present weight lying in the range 5 grams per
square meter (g/m.sup.2) to 100 g/m.sup.2, preferably in the range
15 g/m.sup.2 to 55 g/m.sup.2, and more preferably in the range 20
g/m.sup.2 to 30 g/m.sup.2.
[0070] The width of the ribbon may lie in the range 2 millimeters
(mm) to 60 mm, preferably in the range 4 mm to 30 mm, and more
preferably in the range 10 mm to 20 mm.
[0071] The ribbon may present a width that is greater than the
width of a portion in relief on the vat former, where
appropriate.
[0072] The ribbon may present thickness that is greater than 10
.mu.m, preferably lying in the range 20 .mu.m to 120 .mu.m, and
more preferably in the range 30 .mu.m to 80 .mu.m.
[0073] The thickness of the ribbon may be different from the
thickness of the vellum of the sheet. For example, the ribbon may
present thickness that is greater than that of the vellum of the
sheet so as to enable regions of increased thickness to be created.
The ribbon may also have a thickness that is less than the
thickness of the vellum of the sheet so as to enable regions of
reduced thickness to be created.
[0074] The ribbon may also comprise at least one electronic device,
in particular an integrated microcircuit device. The electronic
device may be a detector. The electronic device may be a
radiofrequency identification device, commonly referred to as an
RFID device, and in particular it may be an electronic chip and/or
an antenna that may be printed on the ribbon, in particular. By way
of example, the electronic device may be deposited and fastened,
e.g. by means of adhesive, on one of the faces of the ribbon. The
electronic device may also be incorporated inside the ribbon, in
particular prior to the ribbon being introduced close to the vat
former, either in direct contact therewith or in the fiber
suspension.
[0075] The ribbon may be fabricated from a material, in particular
a paper, that has previously been subjected to wet strength (WS)
treatment.
[0076] The ribbon may present wet strength (WS) in traction that is
greater than 30%, in particular so as to avoid problems when
inserting the ribbon in the sheet. Wet strength in traction is
measured by dividing the wet strength value in traction as measured
using the standard NF Q 03.056 by the dry strength value in
traction as measured using the standard NF EN ISO 1924. This wet
strength may be provided in particular in conventional manner by
adding a wet strength agent, e.g. such as a polyamine amide
epichlorhydrine (PAAE) resin, a melamine formol resin, etc. . .
.
[0077] In a variant, additional wet strength (WS) may be obtained
by adding a fraction of the WS agent(s) in fibrous sheet surface
treatment baths, e.g. used in fabricating the ribbon.
[0078] The security elements that may be incorporated in the ribbon
or in the proximity of the ribbon may be of various types.
[0079] The security elements may show various patterns, e.g. one or
more alphanumeric characters, drawings, or logos, e.g. as present
elsewhere on the sheet.
[0080] The sheet may present at least two regions of reduced
thickness or two regions of increased thickness or one of each
facing each other and at least two security elements may be
incorporated in or in the proximity of each of these regions of
reduced thickness or of increased thickness, the security elements
possibly facing each other.
[0081] The security elements may be applied, for example by
printing in register. The term "printing in register" is used to
mean that the positions of the security elements on the ribbon are
determined.
[0082] The two security elements of the ribbon may enable differing
effects to be obtained, in particular optical effects, by virtue of
being complementary and observable in show-through.
[0083] The term "observable in show-through" is used to mean that
observation is performed using light that passes through the ribbon
in its thickness direction, e.g. light that is visible,
ultraviolet, or infrared.
[0084] By way of example, the two security elements may serve to
obtain a "moire" effect in show-through.
[0085] By way of example, a moire effect may reveal a pattern
produced by superposing two security elements, e.g. by combining
lines of both of the security elements. For example, a first
printing may be provided on the recto face of the ribbon and a
second print on the verso face of the same ribbon. The prints may
be performed in or in the proximity of regions of reduced thickness
or increased thickness. Then, when the ribbon is observed in
show-through, a complementary pattern may appear by the moire
effect between the first and second print.
[0086] The two security elements may also enable "combinatorial"
effects to be obtained in show-through.
[0087] A "combinatorial" effect results from observing a particular
pattern in show-through, which pattern results from combining two
patterns, each appearing on the recto and the verso of the ribbon.
For example, a first pattern may be printed on the recto of the
ribbon and a second pattern may be printed on the verso of the
ribbon. When observed in show-through, a third pattern may then be
revealed, as a result of combining the first and second
patterns.
[0088] The security elements may be printing, in particular printed
ink. The inks may comprise additional security elements, such as
specific pigments.
[0089] The security elements may also be films, e.g. plastic films
that are optionally transparent or that present reduced opaqueness,
e.g. less than or equal to 40%, preferably less than or equal to
30%, with measurement being performed in compliance with the ISO
2469 standard.
[0090] Whether made of fibers or otherwise, the ribbon may comprise
one or more openings, e.g. made in part or in full in the
ribbon.
[0091] These openings may be of various shapes, e.g. they may be
square, oval, round, rectangular, polygonal, or star shaped, among
other possibilities. The openings may correspond to holes, to
slots, to designs, to optionally through cavities, e.g. made by
embossing, cutouts in the form of patterns that are alphanumeric,
and of a variety of shapes and sizes. The openings may be through
openings. The openings may be made after the security sheet has
been formed. In a variant, the openings may be made in the ribbon
before it is introduced.
[0092] The openings may comprise one or more security elements, in
particular an electronic device, in particular an integrated
microcircuit device, e.g. an RFID device.
[0093] Where appropriate, the security elements may extend fully or
partially in the openings.
[0094] Security elements, in particular films, may be placed in or
in the proximity of regions of reduced thickness or of increased
thickness, in particular mutually facing regions of reduced
thickness or of increased thickness. In particular, the security
elements may be juxtaposed on either side of regions of increased
thickness or they may overlie regions of reduced thickness, with
the security elements facing one another.
[0095] The regions of reduced and/or increased thickness may then
compensate the thickness of the security elements, at least in
part.
[0096] The security elements, in particular films, may overlie
regions of reduced thickness in register with holes made in the
ribbon.
[0097] At least two security elements, in particular films, may
overlie at least two facing regions of reduced thickness, with at
least one opening being made in the ribbon in register with the two
regions of reduced thickness.
[0098] The sheet may in particular comprise regions of reduced
thickness on either side of the ribbon with at least part of at
least one security element extending therein, in particular a film
that extends parallel to the ribbon in contact therewith. A
security element, in particular a film, may extend at least in part
in each of the regions of reduced thickness of the sheet.
[0099] The security elements, in particular films, may be
complementary, i.e. when two elements are observed in show-through,
it is possible to obtain various optical effects, e.g. moire
effects and/or combinatorial effects, e.g. a pattern may appear
that is the result of superposing patterns present in the two
security elements.
[0100] By way of example, the security elements may present
opaqueness suitable for enabling particular optical effects to be
observed in show-through.
[0101] The security elements, in particular films, may be
introduced in the proximity of the vat former during formation of
the sheet.
[0102] By way of example, the films are of thickness that is
greater than or equal to 10 .mu.m, preferably greater than or equal
30 .mu.m.
[0103] The thickness of the films may be compensated at least in
part by the regions of reduced or increased thickness. For example,
the total thickness of a film plus a ribbon may be equal to the
thickness of the vellum of the sheet to within plus or minus 5
.mu.m, better to within plus or minus 3 .mu.m. That constitutes an
advantageous embodiment of the invention enabling a sheet to be
obtained that is essentially flat, thereby reducing problems that
can be caused by differences in thickness and that may occur during
possible subsequent steps: for example steps of rolling, unrolling
or cutting the sheet, or steps of stacking and printing sheets.
[0104] The films may comprise a specific material that collects
light. Such luminescent light-collecting materials that may be
suitable are referred to as "wave guides". By way of example, they
may be polycarbonate-based polymer films called Lisa.RTM. and sold
by the supplier Bayer.
[0105] The films may be inks, varnishes, resins, or cutout strips,
that are pasted or laminated, in particular hot-laminated, or
extruded.
[0106] The films may be colored, in particular they may have
different colors.
[0107] The ribbon may comprise at least one security thread, in
particular a security thread on which an electronic device appears,
in particular an integrated microcircuit device, e.g. an RFID
device.
[0108] An electronic device, in particular an integrated
microcircuit device, e.g. an RFID device, may be housed at least in
part in a region of reduced thickness, the thickness reduction
compensating for the thickness of the electronic device, at least
in part.
[0109] The ribbon may be perforated and fibers of the substrate may
appear in the perforations in the ribbon. In particular, the fibers
of the substrate that appear in the perforations of the ribbon may
have a color that is different from that of the ribbon.
[0110] The ribbon and/or the substrate may comprise a plurality of
particular characteristics as mentioned below. These
characteristics may apply to the entire ribbon and/or to the entire
substrate, or else to a portion only of the ribbon and/or of the
substrate, and more preferably to one or more portions of the
ribbon and/or the substrate where one or more regions of reduced
thickness or increased thickness appear.
[0111] By way of example, the ribbon may be combined with a strip
of thermoplastic and/or metal material, e.g. of polyethylene
terephthalate (PET), pasted or hot-laminated to the ribbon before
it is introduced in the proximity of the vat former.
[0112] The ribbon and/or the substrate may be deprived of any
watermark.
[0113] In a variant, the ribbon and/or the substrate may comprise
at least one watermark.
[0114] The watermark of the ribbon may be situated in a region of
reduced thickness or of increased thickness of the security
sheet.
[0115] When the ribbon and the substrate comprise a watermark,
causing the watermark of the substrate to be superposed relative to
the watermark of the ribbon may enable a pattern to be observed
that is the result of them being associated.
[0116] The ribbon watermark may also be juxtaposed with the
substrate watermark so that the juxtaposition creates a new
pattern.
[0117] The optional watermark of the ribbon and/or of the substrate
may be a pale watermark. Under such circumstances, the pale zones
of the watermark present a weight per unit area that is strictly
less than that of the vellum. In a variant, the watermark may be a
dark watermark. The watermark may also be a multi-tone effect
watermark comprising a set of pale zones arranged to form a
screened image presenting pale and dark tones. The screened image
may comprise screened patterns, e.g. made up of lines. Patent
application EP 1 122 360 discloses how such a watermark can be
made.
[0118] The optional watermarks of the ribbon and of the substrate
may also be superposed so as to obtain a moire effect.
[0119] The ribbon may present optical properties that are different
from those of the substrate, in particular in a region of reduced
thickness and/or a region of increased thickness, in particular
properties concerning color, fluorescence, phosphorescence,
magneto-optics, photochromy, thermochromy, piezochromy,
iridescence, or other properties.
[0120] For example, the substrate and the ribbon may have different
colors. Any color is possible. The ribbon and the substrate may
present a color or colorimetric difference .DELTA.E (using the CIE
Lab 1976 color space) that is greater than 0.2 and preferably
greater than 1. Nevertheless, the human eye is more sensitive to a
color difference on hues that are not saturated, and the person
skilled in the art may adapt the color difference so as to obtain
the desired level of "contrast".
[0121] The ribbon may comprise a conventional ink or a security
ink, in particular a fluorescent, phosphorescent, magnetic,
photochromic, thermochromic, piezochromic, iridescent,
transparentizing, or other ink. The ink may be applied in part or
completely to the ribbon, i.e. on only certain zones of the surface
of the ribbon or over the entire surface of the ribbon. The ink may
be applied to the ribbon by print means, e.g. offset, photogravure,
silkscreen, or ink-jet print means.
[0122] One or more security elements may be selected from the
above-mentioned inks and may be applied to the region of reduced
thickness or juxtaposed with the region of increased thickness.
[0123] The ribbon may also be coated in a varnish that is
transparent or colored.
[0124] The ribbon may include a fluorescent agent. The fluorescent
agent may optionally be colored, and may be visible or invisible in
visible light. By way of example the fluorescent agent may be
incorporated in the material of the ribbon. By way of example the
fluorescent agent may be visible under ultraviolet (UV) light
and/or infrared (IR) light.
[0125] Preferably, the ribbon may extend between two opposite edges
of the sheet.
[0126] The ribbon may present edges of irregular shape, e.g. in the
form of broken or undulating, crenellated, zigzag, or other lines.
The edges of the ribbon may be of shapes that are the same or
different, that are regular or irregular.
[0127] The ribbon may also present characteristics that are
perceptible, e.g. on sight, or to the touch.
[0128] By way of example, the ribbon may be embossed, thereby
serving to create a particular effect, e.g. a touch effect or a
surface relief effect. The effect may serve to form microportions
in relief on the ribbon, that are distinct from the regions of
reduced or increased thickness.
[0129] The ribbon may be coated in a thermoplastic polymer and then
optionally embossed after it has been coated.
[0130] The ribbon may be printed with drops of varnish, of resin,
or of hot-puff ink, among others.
[0131] When the ribbon comprises printed marks, this may make it
possible to obtain variable optical effects, for example.
[0132] The ribbon may comprise a hot-puff ink serving to create at
least one portion in relief, the ink being activated prior to
introducing the ribbon. Activation prior to incorporation serves to
reduce the risk of the sheet being destroyed as the ink swells.
[0133] The ribbon may comprise particles, e.g. detectable to the
naked eye or to the touch, that are introduced into the material of
the ribbon, e.g. in the form of beads, e.g. beads of synthetic
material, e.g. polyurethane, or of inorganic material, e.g. glass,
the beads presenting a size of less than 300 .mu.m, for example, or
being provided by silkscreen or photogravure deposition, e.g. in
the form of beads, e.g. presenting a size of less than 100
.mu.m.
[0134] The ribbon may comprise a textile strip, e.g. a knitted
strip, that is incorporated in the ribbon or is pasted thereto. The
ribbon may comprise textile fibers. The ribbon may be a woven
fabric or a non-woven fabric.
[0135] The ribbon may comprise printing in relief, e.g. silkscreen
printing.
[0136] The ribbon may present a greasy, rough, smooth, silky,
smooth, or other feel.
[0137] The ribbon may in particular comprise deposits of polymers,
in particular in the form of beads, e.g. beads of polyurethane
(PU), beads of glass, polyamide 6 or polyamide 12, styrene-acrylic
pigments, waxes, or beads of polypropylene (PP), of polyethylene
(PE), of polyvinyl chloride (PVC), of polymers based on methyl
methacrylate.
[0138] The ribbon may advantageously conserve its own cohesion
after being introduced into the fiber substrate. After it has been
introduced into the fiber substrate, the structure of the ribbon
may be observable under certain conditions, e.g. in section or by
viewing in reflection or in transmission. Thus, it is possible to
observe the ribbon by differences in optical properties, e.g.
differences in contrast, hue, saturation, paleness, or opaqueness,
that make the frontier between the ribbon and the substrate visible
or that characterize the presence of the ribbon.
[0139] The ribbon may also be observable topographically in the
sheet.
[0140] Where appropriate, the ribbon may also be observable in
transparency through the sheet, in particular to the naked eye.
[0141] In order to obtain the ribbon, it is possible for example to
fabricate a fiber sheet, preferably of low weight, e.g. of weight
lying in the range 15 g/m.sup.2 to 90 g/m.sup.2, using a
conventional papermaking method, e.g. by de-watering a suspension
of fibers possibly comprising fillers and conventional papermaking
additives, optional specific security elements, then pressing the
fiber mass that is obtained, and then drying it. The sheet is then
optionally calendared serving in particular to reduce its
thickness, and then cut to form the ribbons that are then wound
onto reels.
[0142] The ribbon may comprise cellulose fibers (in particular
cotton fibers) and/or natural organic fibers other than cellulose
fibers and/or synthetic fibers, e.g. such as polyester or polyimide
fibers and/or inorganic fibers, e.g. such as glass fibers. The
ribbon may be deprived of fibers of polyvinyl alcohol (PVA).
[0143] The fibers may be hydrophilic, in particular so as to
develop chemical bonds, mainly hydrogen bonds, with the fiber
substrate.
[0144] The ribbon may have at least 50% cellulose fibers in dry
weight.
[0145] The ribbon may comprise perforations, in particular to
enhance de-watering during fabrication of the sheet or indeed to
add an additional optical effect, in particular in combination with
at least one watermark. For example, these perforations may be
located at the border of said ribbon or in such a manner as to form
a pattern or a code.
[0146] The ribbon may comprise a watermark and perforations around
the watermark.
[0147] The ribbon may comprise at least one security element on one
of its faces, or indeed on each of its faces. The ribbon may
comprise different security elements on each of its faces.
[0148] The ribbon may comprise one or more security elements
superposed on the ribbon in a region of reduced thickness or
juxtaposed with a region of increased thickness of the ribbon
and/or security elements incorporated in the ribbon or placed on
the ribbon independently of the regions of reduced or increased
thickness. These security elements may be as described below.
[0149] Among security elements, some are detectable to the naked
eye, in visible light, without using any particular appliance. By
way of example, these security elements include a watermark,
colored fibers or flakes, printed, metal-plated or holographic
threads, holographic foils, or variable optical effects printed
marks.
[0150] Such security elements are said to be "first-level"
elements.
[0151] Other types of security element may be detected solely with
the help of an appliance that is relatively simple such as a lamp
emitting ultraviolet or infrared light. By way of example such
security elements comprise fibers, flakes, strips, threads, or
particles. These security elements may optionally be visible to the
naked eye, e.g. luminescing when illuminated with a Wood lamp
emitting at a wavelength of 365 nanometers (nm).
[0152] These security elements are said to be "second level"
elements.
[0153] Still further types of security elements require a more
sophisticated detector appliance in order to be detected. By way of
example, these security elements are capable of generating a
specific signal on being subjected simultaneously or otherwise to
one or more external excitation sources. Automatic detection of the
signal enables a document to be authenticated, where
appropriate.
[0154] By way of example, these security elements comprise tracers
that are present in the form of active material, particles, or
fibers capable of generating a specific signal when the tracers are
subjected to optronic, electric, magnetic, or electromagnetic
excitation.
[0155] These security elements are said to be "third level"
elements.
[0156] The security elements carried by the ribbon, whether fibrous
or otherwise, may be first, second, or third level.
[0157] The security elements may in particular be selected from
tracers, in particular nanometric tracers, security fibers, in
particular fibers that are metallic, magnetic (with soft and/or
hard magnetism), or absorbent or excitable in the ultraviolet (UV),
the visible or the infrared (IR), and in particular in the near
infrared (NIR), security elements that are flat and of relatively
small format such as flakes, pigments or agglomerations of pigments
in particular those that are absorbent or excitable under laser
illumination or illumination in the ultraviolet (UV), visible, or
infrared (IR), and in particular in the near infrared (NIR), and
security threads (based on plastics, in particular polyester)
comprising in particular an at least partial coating, being
metallic, metal-plated, iridescent, or magnetic (with soft and/or
hard magnetism), the coating potentially including positive or
negative patterns, and said patterns being obtainable in particular
by removing metal, chemical or biochemical reagents for countering
falsification and/or for authentication, in particular being
suitable for reacting with at least one falsification and/or
authentication and/or identification agent, respectively, and
optically variable elements, in particular holograms, liquid
crystals, iridescent pigments, or mirror effect structures, in
particular dielectric structures, and combinations thereof.
[0158] The ribbon may comprise a series of parallel security
threads, and more particularly the succession of spaces between the
threads and/or the series of different widths of security thread
may constitute a code, in particular of the bar code type.
[0159] The ribbon may also comprise an antitheft thread with soft
magnetism.
[0160] The ribbon may also comprise at least one chemical or
biochemical reagent for countering falsification and/or for
authentication and/or for identification that reacts in colored
manner with at least one falsification and/or authentication and/or
identification agent.
[0161] The ribbon may comprise perforations in a pattern or a code.
Depending on differences in opaqueness and color between the
substrate and the ribbon, the pattern or code is observable or is
observable only in transmitted light or is observable both in
transmitted light and in reflected light. If the ribbon possesses
invisible fluorescent printing, the pattern may also be visible
only under UV illumination.
[0162] In particular, the pattern made by perforation may comprise
at least one alphanumeric character or ideogram.
[0163] When the ribbon comprises at least one opening, the opening
may overlie at least in part a corresponding opening formed in a
second ply of paper placed against the first ply in which the
ribbon is incorporated. The opening in the ribbon may correspond,
for example, exactly with the opening in the second ply. At least
one security element may overlie the opening, with the security
element being received in a region of reduced thickness created in
the first ply of paper by the ribbon, for example. The presence of
the opening in the second ply may make it possible, for example, to
observe the inside face of the security element, facing towards the
ribbon. The ribbon may optionally be a fiber ribbon.
[0164] The invention enables a security sheet to be made that
comprises two plies of paper each provided with a respective ribbon
that has served to create a region of reduced thickness. These two
plies of paper may be united in such a manner that the ribbons
overlie each other at least in part, and preferably substantially
exactly. Each region of reduced thickness may receive a security
element. Each of the ribbons may comprise at least one zone of
reduced opaqueness, e.g. defined by an opening, and the two
security elements disposed on either side of the set of ribbons may
be observed by looking through zones of reduced opaqueness of the
ribbons. By way of example, this may enable additional patterns to
be observed. The ribbons may be made of fiber, or be deprived of
fibers.
[0165] The invention may enable a security sheet to be made by
uniting two papermaking plies, each provided with a ribbon defining
a region of reduced thickness. The two plies may be adjacent via
faces that present regions of reduced thickness, and these regions
of reduced thickness may receive a third ribbon introduced between
the plies. The third ribbon is thus situated between the ribbons
that are incorporated within each of the plies.
[0166] The invention may also enable a security sheet to be made
that comprises two ribbons that are disposed in such a manner as to
leave a space between them, these ribbons forming regions in one
face of the sheet that are of thickness that is increased, relative
to the fiber substrate, with a security element being located
between the projecting portions of the ribbons. The presence of the
ribbons serves to protect the security element from a risk of being
flattened, for example.
[0167] The ribbon need not have a surface coating, in particular it
need not have a pigmented layer. Good affinity between the fiber
substrate and the ribbon is thus enhanced.
[0168] The ribbon may present wet strength (WS) in traction that is
greater than 30%, in particular so as to avoid giving rise to
problems while being introduced in the sheet.
[0169] The ribbon may comprise an adhesive, e.g. a heat-sealing
agent, in order to improve its cohesion within the fiber
substrate.
[0170] When the ribbon comprises an adhesive, the adhesive may
serve to enhance adhesion of the ribbon in the sheet.
[0171] By way of example, the adhesive may be a heat-sealing
coating, e.g. a heat-sealing varnish, a UV-curable agent, an
irradiation-sensitive adhesive, a pressure-sensitive adhesive
(PSA), a solvent-based varnish, e.g. of the polyester type, an
aqueous phase adhesive, etc. . . .
[0172] As aqueous phase adhesive, mention may be made in particular
of the following trademarks: Mowilith DC (an aqueous dispersion of
vinyl acetate homopolymer with particles having a size lying in the
range 0.3 .mu.m to 2 .mu.m and a glass transition temperature
T.sub.g of about 38.degree. C., and a solid matter dry content
lying in the range 55% to 57%), and Vinamul 3265 from the supplier
Celanese; DH9004, DH9017, DH9044, and DL5001 from the supplier
Collano; Primal NW1845, Primal LC40, Primal P308M, and Primal
EP6000 from the supplier Rohm & Haas; 006SDW078-2 from the
supplier BASF.
[0173] The adhesive may advantageously be an adhesive based on
polyvinyl acetate, such as Mowilith DC.
[0174] The Applicant has observed that among the above-mentioned
adhesives, Vinamul 3265, Mowilith DC, Collano DL5001, Primal
NW1845, and Primal P308M present very good results in the dry
crease test, i.e. the adhesion of the ribbon in the paper is not
excessively affected by creasing.
[0175] Furthermore, Vinamul 3265 and Mowilith DC also present very
good results in the wet crease test. Mowilith DC presents very good
results in the washing test.
[0176] Also, Mowilith DC provides very good results in terms of
adhesive power, but the invention is not limited to any particular
adhesive.
[0177] In an embodiment of the invention the adhesive is not
present in the form of fibers nor in the form of particles.
[0178] The adhesive may be added to the security ribbon in
particular by a coating method, by a surface-application method,
e.g. coating, or by methods derived from techniques for printing a
paper base after it has been fabricated, e.g. air-knife coating,
photogravure, silkscreen-printing, curtain coating, flexography,
among others.
[0179] The adhesive may be applied, e.g. on a fiber sheet used for
fabricating the ribbon, e.g. at a rate of 2 g/m.sup.2 to 15
g/m.sup.2 per face, preferably at a rate of 3 g/m.sup.2 to 8
g/m.sup.2 per face.
[0180] The sealing temperature may lie in the range 70.degree. C.
to 135.degree. C., for example, depending on the adhesive used, and
the sealing may take place while the security sheet is being
dried.
[0181] The surface application may be performed on the surface, or
at least in part to the core, i.e. it may penetrate deep, possibly
over the entire ribbon.
[0182] Preferably, the surface application is performed on the
medium that is used for fabricating the ribbon prior to cutting up
said medium. In a variant, the surface application may be performed
while fabricating the medium that is used for fabricating the
ribbon.
[0183] The surface application may be performed on a single face of
the medium or on both faces thereof. The adhesive may cover
completely the face on which it is deposited.
[0184] The adhesive may also be incorporated in the ribbon by
impregnation, by immersing the ribbon or the medium used for
fabricating it in a bath.
[0185] In an embodiment of the invention, a 20 g/m.sup.2 fiber
sheet that has been subjected to wet strength (WS) treatment is
coated with an aqueous phase adhesive at 5 g/m.sup.2 per face,
using a photogravure method, for example. This obtains a
satisfactory compromise between adhesive power and the quantity of
coated material.
[0186] In order to detect the presence of adhesive in a security
sheet of the invention, it is possible to observe the adhesive,
e.g. the heat-sealing varnish, in the form of bubbles, e.g. using a
scanning electron microscope (SEM).
Substrate
[0187] The term "substrate" designates a fiber sheet that may in
particular comprise one or more fiber layers. In particular, the
term "ply" is used to designate layers that are produced
continuously on a given papermaking machine and then associated
while in the wet state.
[0188] The substrate may comprise at least one security element as
described above, for example selected from tracers, in particular
nanometric tracers, security fibers, in particular fibers that are
metallic, magnetic (with soft and/or hard magnetism), or absorbent
or excitable in the ultraviolet (UV), the visible or the infrared
(IR), and in particular in the near infrared (NIR), security
elements that are flat and of relatively small format such as
flakes, pigments or agglomerations of pigments in particular those
that are absorbent or excitable under laser illumination or
illumination in the ultraviolet (UV), visible, or infrared (IR),
and in particular in the near infrared (NIR), and security threads
(based on plastics, in particular polyester) including in
particular an at least partial coating, being metallic,
metal-plated, iridescent, or magnetic (with soft and/or hard
magnetism), the coating potentially including positive or negative
patterns, and said patterns being obtainable in particular by
removing metal, chemical or biochemical reagents for countering
falsification and/or authentication, in particular being suitable
for reacting with at least one falsification and/or for
authentication and/or identification agent, respectively, and
optically variable elements, in particular holograms, liquid
crystals, iridescent pigments, or mirror effect structures, in
particular dielectric structures, and combinations thereof.
[0189] The ribbon substrate may in particular comprise security
elements that are visible to the naked eye, but it may also
comprise tracers that are in the form of active material,
particles, or fibers, capable of generating a specific signal when
the tracers are subjected to an optronic, electric, magnetic, or
electromagnetic excitation. Such "tracers" constitute a substance
that is identifiable by means of a distinctive property and that is
used to mark an element (here a security document) and to enable it
to be tracked, its evolution to be tracked, or enabling it to be
recognized, authenticated, or identified.
[0190] Mirror dielectric structures are constituted by alternating
layers of high and low refractive index, e.g. respective layers of
hafnium dioxide and of silicon dioxide, and may in particular be
obtained by ion etching.
[0191] In a particular embodiment of the invention, the fiber
substrate comprises at least one chemical or biochemical reagent
for countering falsification and/or for authentication and/or for
identification that reacts in colored manner with at least one
agent respectively for falsification and/or authentication and/or
identification.
[0192] The fiber substrate may be based on fibers such as those
described above for the ribbon.
[0193] In particular embodiment of the invention, the fiber
substrate and the ribbon are based on the same fibers, i.e. their
fiber composition is the same in terms of nature and preferably in
terms of proportions, thus ensuring good affinity between the
components and possibly also constituting additional authentication
means.
Security Sheet
[0194] In another of its aspects, the invention also provides a
sheet comprising a fiber ribbon incorporated in part in a fiber
substrate made using a single ply papermaking machine, the ribbon
having at least one face situated set back or projecting relative
to the vellum of the sheet and that is not entirely covered by the
substrate.
[0195] In another of its aspects, the invention also provides a
sheet comprising a fiber ribbon and a fiber substrate, at least one
security element being placed in register with the ribbon, in
particular overlying the ribbon and having a thickness that is
compensated at least in part by a thickness difference between the
ribbon and the vellum of the sheet and/or by an opening in the
ribbon.
[0196] In another of its aspects, the invention also provides a
sheet comprising first and second fiber plies adjacent to each
other, the first ply comprising an optionally fiber ribbon forming
at least one region of reduced thickness in the face of the first
ply facing away from the second ply, and the second ply comprising
an opening that overlies an opening in the ribbon at least in part
and preferably exactly.
[0197] In another of its aspects, the invention also provides a
sheet comprising two mutually adjacent fiber plies, each of the
plies comprising an optionally fiber ribbon, each ribbon forming a
region of reduced thickness in each of the faces of the plies that
are not adjacent to each other, each ribbon comprising an opening,
the openings overlying at least in part and preferably exactly.
[0198] In another of its aspects, the invention also provides a
sheet comprising two mutually adjacent fiber plies, each including
an optionally fiber ribbon, each ribbon creating a region of
reduced thickness, the regions of reduced thickness overlying each
other at least in part and preferably exactly so as to leave
between the plies a cavity suitable for receiving another
optionally fiber ribbon.
[0199] In another of its aspects, the invention also provides a
sheet comprising a fiber substrate with two optionally fiber
ribbons forming two regions of increased thickness on the surface
of the sheet, the ribbons being spaced apart from each other in
such a manner as to enable a security element to be placed between
the two ribbons.
[0200] The sheet may be obtained by the above-described method. In
particular, the sheet may comprise any one of the above-mentioned
characteristics.
Security Document
[0201] The invention also provides a security document including a
sheet as defined above.
[0202] The document may be fabricated by cutting, associating,
binding, laminating, adhesively bonding, and/or pasting said
sheet.
[0203] More particularly, the security document may constitute
payment means, such as a bank note, a check, or a meal ticket, an
identity document such as an identity card or a visa or a passport
or a driver's license, a lottery ticket, a transport ticket, or
indeed a ticket for entry to cultural or sporting events.
Article to be Authenticated
[0204] The invention also provides an article to be authenticated
that comprises the sheet as defined or obtained above, the article
being selected from a security label, packaging, in particular
packaging for medication or for food or for cosmetics or for
perfume or for electronic components or for spare parts, a sheet
used in the medical or hospital field, in particular a sheet used
for making sterilization packages, or indeed art paper.
[0205] The invention can be better understood on reading the
following description of non-limiting embodiments of the invention
and on examining the diagrammatic and fragmentary figures of the
drawings, in which:
[0206] FIG. 1 is a section view showing an example of a ribbon of
the invention being incorporated;
[0207] FIGS. 2 and 3 are section views showing other examples of
the ribbon of the invention being incorporated;
[0208] FIGS. 4 to 10 are section views showing examples of sheets
of the invention;
[0209] FIG. 11 is a view from above the FIG. 10 sheet;
[0210] FIG. 12 is a view from below of the FIG. 10 sheet; and
[0211] FIGS. 13 to 15 are section views showing various sheets of
the invention.
[0212] FIG. 1 is a section view showing an example of a ribbon 3
being incorporated in a method of fabricating a sheet 1 in
accordance with the invention.
[0213] The method is implemented on a papermaking machine, shown in
part, fitted with a lifting cylinder 40 and a vat former 4 that is
partially immersed in a fiber suspension 5 and that serves to form
a sheet 1 comprising a ply of a fiber substrate 2 and a fiber
ribbon 3.
[0214] In this example, the fiber ribbon 3 is introduced in direct
contact with the vat former 4 via one of its faces 9 prior to
penetrating into the fiber suspension 5 used for forming the
substrate 2.
[0215] In this way, no fiber of the fiber suspension 5 can become
deposited on the face 9 of the ribbon 3 that is in contact with the
vat former 4, in particular because the face 9 obstructs the holes
in the forming fabric of the vat former 4. The face 9 of the ribbon
3 can then be visible on the sheet 1 after fabrication.
[0216] Thus, only the face 6 of the ribbon 3, i.e. the face facing
away from the vat former 4, may optionally be covered by the fibers
of the fiber suspension 5.
[0217] The ribbon 3 may have been subjected to treatment on at
least part of its face 6 that prevents any deposition of fibers in
the fiber suspension 5.
[0218] One or more regions of reduced or increased thickness may be
formed in the ribbon 3 and one or more security elements may be
applied to the ribbon 3, in particular elements that are superposed
on regions of reduced thickness or juxtaposed with regions of
increased thickness.
[0219] After the sheet 1 has been formed on the vat former 4 and
after the fiber suspension 5 has been de-watered on the fabric of
the vat former 4, the sheet 1 may be pressed and then dried by the
usual papermaking method.
[0220] In an advantageous embodiment of the invention, the sheet 1
obtained prior to drying is married while in the wet state with
other plies of ribbon compositions that may be identical or
different and that may be formed on flat bed (Fourdrinier), short
former, or vat former papermaking machines.
[0221] FIG. 2 shows another example of a ribbon 3 being
incorporated in a method of fabricating a sheet 1 of the
invention.
[0222] By way of example, the method may be implemented on the same
papermaking machine as that shown in FIG. 1.
[0223] In this example, the ribbon 3 is introduced into the fiber
suspension 5 close to the vat former 4 but after fibers have
already been deposited on the vat former 4.
[0224] As a result, neither of the faces 6 and 9 of the ribbon 3
comes into contact with the vat former 4. The ribbon 3 is in
contact with fibers that have already become deposited on the vat
former 4 prior to the ribbon 3 being introduced in the fiber
suspension 5. The face 9 of the ribbon 3 then need not be visible
on the sheet 1 once it has been fabricated.
[0225] Thus, both faces 6 and 9 of the ribbon 3 may be covered at
least in part by fibers of the fiber suspension 5.
[0226] It is possible to obtain one or more regions of reduced or
increased thickness in the ribbon 3 by any of the techniques
described above.
[0227] One or more security elements may be incorporated at or
close to the regions of reduced or increased thickness.
[0228] After being formed, the sheet 1 may be processed in the same
manner as described above.
[0229] FIG. 3 shows the possibility of incorporating the ribbon 3
in the sheet 1 by bringing it into contact with the ply 2a formed
on the vat former 4 at the outlet from the cylinder vat.
[0230] The ribbon 3 may be inserted between the ply 2a leaving the
cylinder vat and a ply 2b that may be made using any papermaking
means.
[0231] Under such circumstances, a region of increased thickness
may be formed on the sheet 1 in register with the ribbon 3, this
increased thickness projecting, e.g. from the outside face of the
ply 2b and/or of the ply 2a.
[0232] FIGS. 4 and 5 are section views of examples of each one
obtained by a method of the invention.
[0233] FIG. 4 shows a sheet 1 that may be obtained by the method
shown in FIG. 1.
[0234] The sheet 1 comprises a ribbon 3 with its face 9 not covered
by fibers of the fiber suspension 5, thus remaining visible on the
sheet 1.
[0235] The ribbon 3 may have a thickness e.sub.R that is less than
the thickness e of the vellum of the sheet 1 or it may have been
subjected to prior special treatment. As a result, a region of
reduced thickness 7 is created in the sheet 1 in register with the
ribbon 3.
[0236] In this example in particular, the thickness e of the vellum
of the sheet 1 is greater than the total thickness e.sub.2 of the
sheet 1 in the region of the sheet 1 where the ribbon 3 appears,
this thickness e.sub.2 corresponding, for example, to the thickness
e.sub.R of the ribbon 3, for example. The thickness e of the vellum
of the sheet 1, in particular of the substrate 2, corresponds to
the sum of the thickness e.sub.2 plus the value .DELTA.e.sup.- of
the reduction in thickness 7.
[0237] FIG. 5 shows a sheet 1 that may be obtained by the method
shown in FIG. 2.
[0238] The sheet 1 comprises a ribbon 3 having its face 9
completely covered in fibers of the fiber suspension 5, and is thus
not visible on the sheet 1.
[0239] The ribbon 3 may have a thickness e.sub.R that is less than
the thickness e of the vellum of the sheet 1 or it may have been
subjected to prior special treatment. As a result, a region of
reduced thickness 7 is created in the sheet 1 in register with the
ribbon 3.
[0240] In this example in particular, the thickness e of the sheet
1, in particular of the substrate 2, is greater than the thickness
e.sub.2 of the sheet 1 where the ribbon 3 appears. The thickness e
is in particular equal to the sum of the value .DELTA.e.sup.- of
the region of reduced thickness 7 plus the thickness e.sub.2 of the
sheet 1 where the ribbon 3 appears, this thickness itself being
equal to the sum of the thickness e.sub.R of the ribbon 3 plus the
thickness e.sub.3 of the fibers of the fiber suspension 5 in
contact with the face 9 of the ribbon 3.
[0241] The resulting regions 7 of reduced thickness may enable one
or more security elements to be incorporated on the sheet 1 of
FIGS. 4 and 5.
[0242] In the examples described above and below, the various
thicknesses may be equal to the above-mentioned value.
[0243] In particular, the thickness e.sub.R of the ribbon 3 may be
greater than 10 .mu.m, preferably lying in the range 20 .mu.m to
120 .mu.m, and more preferably in the range 30 .mu.m to 80
.mu.m.
[0244] The value .DELTA.e.sup.- of the region 7 of reduced
thickness may be greater than or equal to 15 .mu.m, preferably 30
.mu.m, more preferably 60 .mu.m.
[0245] FIG. 6 shows an example of a sheet 1 that may be obtained
for example by the method shown in FIG. 1.
[0246] The sheet 1 comprises a ribbon 3 in register with a region 7
of reduced thickness.
[0247] The ribbon 3 comprises an electronic device 20, e.g. in the
form of an RFID device, e.g. incorporated in the ribbon 3 during
fabrication of the ribbon 3.
[0248] One or more security elements may be incorporated in the
sheet 1 in register with the face 6 of the ribbon 3 particularly in
order to protect the electronic device 20.
[0249] In addition, a second ply or a film may overlie the
substrate 2 on the side of the face 6 of the ribbon 3 in order to
protect the electronic device 20.
[0250] In this example, the thickness e.sub.2 of the sheet 1 where
the ribbon 3 appears corresponds to the thickness e.sub.R of the
ribbon 3.
[0251] FIG. 7 shows another example of a sheet 1, in which the
ribbon 3 comprises an electronic device 20, in particular in the
form of an RFID device, which device is fastened to the face 6 of
the ribbon 3, e.g. by adhesive.
[0252] The electronic device 20 has a width that is substantially
equal to the width of the ribbon 3, for example.
[0253] The value .DELTA.e.sup.- of the region 7 of reduced
thickness may for example compensate the thickness e.sub.D, of the
electronic device 20 completely.
[0254] The thickness e.sub.2 of the sheet 1 where the ribbon 3
appears may be equal to the sum of the thickness e.sub.D, of the
electronic device 20 plus the thickness e.sub.R of the ribbon
3.
[0255] FIG. 8 shows an example of a sheet 1 that may be obtained by
the method shown in FIG. 1.
[0256] In this example, the ribbon 3 has a thickness e.sub.R that
is greater than the thickness e of the vellum of the sheet 1 such
that a region of increased thickness 8 is created in the face 6 of
the ribbon 3. The increased thickness 8 may have a value
.DELTA.e.sup.+ that corresponds to the difference between the
thickness e.sub.R of the ribbon 3 and the thickness e of the vellum
of the sheet 1. The thickness e.sub.2 of the sheet 1 where the
ribbon 3 appears corresponds to the thickness e.sub.R of the ribbon
3.
[0257] The value .DELTA.e.sup.+ of the increased thickness 8 may be
less than 20 .mu.m.
[0258] Advantageously, the ribbon 3 may comprise polyethylene
fibers.
[0259] As a result of the face 6 of the ribbon 3 being embossed
hot, the polyethylene fibers may melt and be made transparent.
[0260] As a result, it is possible to create a particular portion
in relief 11 at the surface of the face 6 of the ribbon 3 that may
eliminate the previously-existing increased thickness 8. By way of
example, the embossing may enable a face 6 of the ribbon 3 to be
obtained that is substantially plane and substantially flush with
the substrate 2, or indeed to form a window or a strip of reduced
opaqueness without obtaining any difference in thickness relative
to the substrate.
[0261] It is also possible to make the face 6 of the ribbon 3
transparent, thereby enabling visual effects to be created that can
be observed both in reflection and in transmission.
[0262] In addition, the portion in relief 11 that is created also
serves to obtain touch effects on the face 6 of the ribbon 3.
[0263] FIG. 9 shows a sheet 1 comprising two plies 2a and 2b.
[0264] The ply 2a carries the ribbon 3, which is incorporated in
the ply 2a, e.g. by using the method described above with reference
to FIG. 1.
[0265] The second ply 2b is adjacent to the first ply 2a, e.g. on
the side thereof that is opposite from the region 7 of reduced
thickness. As shown, the second ply 2b may include an opening, e.g.
a window 22b for coming into register with an opening, e.g. a
window 22a in the ribbon 3.
[0266] The region 7 of reduced thickness may receive a security
element 21 and the presence of the window 22b in register with the
window 22a may enable the inside face 21a of the security element
21 to be observed from outside the ply 2b.
[0267] In order to fabricate the sheet 1 shown in FIG. 9, it is
possible to fabricate the first ply 2a with the ribbon 3 and to
marry the first and second plies 2a and 2b while wet. The assembly
made up of the two plies 2a and 2b and the ribbon 3 may be
perforated so as to create the openings 22a and 22b, and the
security element 21 may be laminated with the first ply 2a so as to
be in register with the ribbon 3, e.g. so as to be assembled
therewith.
[0268] In a variant that is not shown, the second ply 2b does not
comprise the opening 22b, but may for example include an imprint of
ink seeking to make it transparent.
[0269] By way of example, the security element is a transparent
film 21 that is thicker than the transparent films usually used in
the prior art.
[0270] The transparent film 21 may be introduced in line, e.g.
between two papermaking plies or on a single ply when it is
sufficiently formed. In a variant it may be introduced off-line,
e.g. by a method of lamination and/or pasting.
[0271] By way of example, the transparent film 21 may be made of
stretched polyester or of stretched polycarbonate, and it may have
a thickness e.sub.S that is greater than or equal to 30 .mu.m,
preferably greater than or equal to 40 .mu.m. The transparent film
21 may also include patterns, e.g. obtained by laser etching or by
copperplate printing on the transparent film 21.
[0272] The transparent film 21 may also be an ink, a varnish, or a
resin.
[0273] In the configuration (not shown) in which the ribbon
comprises an electronic device, the transparent film 21 may serve
to protect the electronic device.
[0274] The transparent film 21 may also be made of a textile that
is stuck or fastened in the region 7 of reduced thickness.
[0275] In this example, the thickness e.sub.S of the transparent
film 21 corresponds substantially to the value .DELTA.e.sup.- of
the reduced thickness 7, e.g. being equal to 40 .mu.m.
[0276] The ply 2a may have a thickness e of 115 .mu.m.
[0277] FIG. 10 shows a variant embodiment of a sheet 1 of the
invention comprising two paper plies 2a and 2b, each including a
corresponding ribbon 3a or 3b, the ribbons 3a and 3b being inserted
in the corresponding plies using the method described with
reference to FIG. 1, for example.
[0278] Each ply 2a and 2b comprises a respective corresponding
region 7a or 7b of reduced thickness associated with the presence
of the respective ribbon 3a or 3b.
[0279] In the example shown, the two plies 2a and 2b are assembled
together so that the regions 7a and 7b of reduced thickness formed
in the respective substrates are directed towards the opposite
faces of the sheet 1.
[0280] Each region 7a or 7b of reduced thickness receives a
corresponding security element 21 or 23. The respective thicknesses
e.sub.S and e.sub.S' of the security elements 21 and 23 correspond
substantially to the reduced thicknesses 7a and 7b, for
example.
[0281] Each of the ribbons 3a and 3b may comprise a corresponding
opening 22a or 22b, these openings possibly being at least
partially in register, and preferably exactly in register.
[0282] The security elements 21 and 23 are preferably not entirely
opaque so as to make it possible to observe special show-through
effects via the openings 22a and 22b.
[0283] By way of example, the transparent film 21 may have a
thickness e.sub.S of 20 .mu.m. By way of example, the transparent
film 23 may have a thickness e.sub.S' of 15 .mu.m. By way of
example, the ribbon 3 may have a thickness e.sub.R of 60 .mu.m. The
values .DELTA.e.sup.- and .DELTA.e.sup.-' of the reduced
thicknesses 7 may respectively compensate the thicknesses e.sub.S
and e.sub.S' of the films 21 and 23 completely.
[0284] The thickness e of the vellum of the sheet 1 may correspond
to the sum of the thicknesses e.sub.S and e.sub.S' of the films 21
and 23 plus the thickness e.sub.Ra and e.sub.Rb of the ribbons 3a
and 3b.
[0285] In a particular embodiment, the transparent films 21 and 23
may be fluorescent with different colors.
[0286] The transparent films 21 and 23 may make it possible to
obtain the above-described effects. For example, they may include
patterns enabling other patterns to be observed by moire and/or
combinatorial effects.
[0287] Although not shown, in a variant, in the examples of FIGS. 9
and 10, one or more security elements 21 and 23 may extend at least
in part into one or more of the openings 22a and 22b.
[0288] FIGS. 11 and 12 are respectively a view from above and a
view from beneath of the sheet 1 of FIG. 10.
[0289] From these two figures, it can be seen that a show-through
color appears in the openings 22a and 22b, which color corresponds
to the sum of the colors of the two transparent films 21 and
23.
[0290] In contrast, away from the openings 22a and 22b, but still
in the ribbon 3, it is the color of the transparent film 21 that is
observed in FIG. 11 and the color of the transparent film 23 that
is observed in FIG. 12.
[0291] FIG. 13 shows a variant embodiment in which the sheet 1
comprises two plies 2a and 2b, each including a corresponding
ribbon 3a or 3b that has been used to create a corresponding region
7a or 7b of reduced thickness.
[0292] In the example of this figure, the two plies 2a and 2b are
assembled so that the regions 7a and 7b of reduced thickness are in
register with each other so as to leave a cavity between the two
plies suitable for receiving a third ribbon 3c, as shown.
[0293] Each ply 2a and 2b may be made with its corresponding ribbon
3a and 3b, and the third ribbon 3c may be introduced between the
plies when they are assembled together.
[0294] The third ribbon 3c may be constituted by any security
element.
[0295] FIG. 14 shows a variant embodiment in which the substrate
ply 2 is made in contact with a vat former in which the fabric T
includes a portion in relief R that enables a recess 50 to be made
in the substrate 2.
[0296] The ribbon 3 is incorporated in the fiber suspension after a
certain thickness e.sub.3 has accumulated on the portion in relief
R of the fabric T. This makes it possible to obtain a paper ply
that includes a region 7 of reduced thickness beside the ribbon 3,
and on the opposite side another region 50 of reduced thickness,
associated with the presence of the portion in relief R.
[0297] The ply as fabricated in this way may receive any security
element in the region 7 of reduced thickness, as in the
above-described examples.
[0298] FIG. 15 shows a sheet 1 in which the substrate 2 carries two
ribbons 3 that are spaced apart by a distance d that may lie in the
range 3 m to 20 mm, for example.
[0299] The thickness e.sub.3 of the substrate under each ribbon 3
is identical, as shown, but in a variant it could be different, if
the ribbons are introduced in contact with ribbons that have
accumulated on the vat former at different locations and/or if the
thicknesses of the ribbons 3 are different.
[0300] In the example described, each of the ribbons 3 forms a
region of increased thickness .DELTA.e.sup.+ and the space 60
formed between the regions of increased thickness created by the
ribbons 3 receives a security element 21, which may be of any kind,
and in particular one of those described above.
[0301] The security element 21 presents a thickness e.sub.S that
may for example be less than .DELTA.e.sup.+ or equal thereto, so as
to be protected from any risk of flattening by the presence of the
ribbons 3.
[0302] Naturally, the invention is not limited to the embodiments
described above.
[0303] In the above-described embodiments, the ribbon(s) of the
sheet of the invention is/are made of fiber. In a variant, such a
ribbon need not be made of fiber, for example it could be a
synthetic ribbon, e.g. by being cut out from a thermoplastic
film.
[0304] The term "comprising a" is synonymous with "comprising at
least one".
* * * * *