Note: Descriptions are shown in the official language in which they were submitted.
CA 02216527 1997-09-26 646-TY
SPECIFICATION
Anti-falsification Paper and A Method of
Manufacture Thereof
Field of the Invention
The present invention relates to anti-falsification
paper and a method of manufacture thereof, and more
specifically to anti-falsification paper, called "thread-
inserted, window paper," in which a thread inserted between
combined paper layers making up the anti-falsification paper
is exposed at windows provided in the outermost paper layer,
and to a method of making such anti-falsification paper.
Background Art
Anti-falsification paper called "thread-inserted paper"
is well known, in which an elongate element is inserted in
the thickness of paper. A typical example of the elongate
element' is a thread described hereinbelow. Paper with
inserted threads requires very sophisticated technologies to
manufacture and thus has a significant effect for anti-
falsification. It is therefore widely used for making bank
notes in many countries.
Thread-inserted paper may be classified largely into two
categories. The first is the paper which has an elongate
element embedded therein so that it is not exposed to the
surface of the paper. The second is the one called "thread-
inserted, window paper," in which a part of the inserted
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elongate element is exposed to the surface of the paper.
A variety of methods have been proposed for making the
first category of paper. They include a method disclosed in
Japanese Patent Laid-Open Specification No. 51-130309/1976,
in which a nozzle is laid in the flow of paper stock in a
slice portion of a Fourdrinier paper machine and an
elongate element~is supplied through the nozzle along with
running. water to be embedded in a web deposited on a wire
cloth; a method disclosed in Japanese Patent Laid-Open
Specification No. 2-169790/1990, in which an elongate
element incorporating device is used to incorporate an
elongate element into the paper stock flowing from a flow
box of a Fourdrinier paper machine by supplying the elongate
element with an air flow that keeps the elongate element and
the stock out of contact with each other; and a method
disclosed in Japanese Patent Publication No. 5-40080/1993,
in which a cylinder paper machine having two or more vats is
used to combine two or more paper layers and an elongate
element is fed from a pipe having pro~eetions and recesses
in its inner wall to be inserted between the paper layers.
As the methods of making the second category of paper,
the "thread-inserted, window paper", there are proposed a
method disclosed in Japanese Patent Publication No.
5-85680/1993, in which a grooved belt mechanism with an
elongate element passed through a raised end of a guide
having recessed and raised portions is immersed in a
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suspension of paper stock on wire cloth; a method disclosed
in U.S. Patent No. 4462866, in which a wire mesh having
raised portions is used for a face wire of a cylinder paper
machine and an elongate element is incorporated in the
thickness of paper as the elongate element is fed in contact
with the raised portions of the wire mesh so that the
elongate element is incorporated in paper and exposed at
window portions; and a method disclosed in Japanese Patent
Specification Laid-Open No. 6-272200/1994, in which a
compressed air nozzle is installed in a rotating drum of
wire cloth in a Fourdrinier paper machine to intermittently
blow away pulp slurry deposited over an elongate element
embedded in web so that the elongate element is exposed.
"Watermarked paper" having watermarks of letters or
pictures also requires a high level of technology to
manufacture and has long been used for anti-falsification.
Because the anti--falsification effectiveness increases with
the number of anti-falsification means employed in the
anti-falsification paper, a variety of anti-falsification
paper has been developed which combine the above-mentioned
"thread-inserted, window paper" technology with the
"watermarking" technology. One such example is sterling
notes used in England, which has thread-inserted windows at
predetermined locations and a watermarked portrait at a
different location.
These conventional paper has a common drawback that the
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paper cannot be rolled up in a great length. Because the
thread normally has a thickness of several tens of
micrometer and is continuously inserted or embedded at a
particular position of the paper, when the paper is rolled
up, the paper thickness at the location where the thread is
inserted progressively increases until cockles are produced
at that location. Our investigation has found that when a
thread of about 15 a m thick is continuously inserted in
paper of 100g/~2, rolling about 1000 meters of the paper
results in cockles being produced at the thread inserted
location. Once cockles are produced, the paper rolled up
thereafter is not adequate for use. Whether the paper can be
wound up in roll has a great effect on productivity at a
later process 'where the paper is subjected to printing,
since the paper must be bundle-finished if it cannot be
rolled up.
In anti-falsification paper that uses the "thread-
inserted, window paper" technology and the "watermarking"
technology at different locations, printing is difficult to
be performed at the "thread-inserted, window" portion and
the "watermarked" portion. If they are to be printed, only
very light colors can be used. This reduces the area on
paper where decorative printing can be made, giving rise to
a limitation on the design to be printed.
Disclosure of the Invention
The present invention has been accomplished to provide
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novel and improved anti-falsification paper that can
eliminate the conventional problems described above and also
a method of manufacturing such anti-falsification paper.
The cause of cockles formed when winding the thread-
inserted paper in a roll during the process of manufacture
of the paper is that the thickness of paper locally
increases because of the inserted or embedded thread as
described above. The inventors of this invention have
conducted studies under the assumption that cockles could be
eliminated if the paper thickness was partially reduced in
such a way as to offset the localized increase in paper
thickness. The inventors have found that the above problem
can be solved by providing in the paper surface window
portions of particular size whose paper thickness is reduced
and inserting a thread so that it is exposed in these window
portions. With this method, however, when the paper is held
to the light, the windows as a whole look white and
transparent giving unnatural impressions. The inventors
conducted further research and found that this drawback can
be eliminated by watermarking letters or pictures in the
window portions and that restrictions on the printing design
can be eliminated by forming both the "thread-inserted
window" portions and the "watermarked" portions in the same
locations in the paper. Forming watermarks in the window
portions prevents the paper thickness of the entire window
portions from becoming small, which in turn effectively
CA 02216527 1997-09-26
prevents the formation of cockles when winding the paper in
a roll.
The anti-falsification paper of this invention
comprises: combination paper having at least two paper
layers including an outermost layer and the other layer;
window portions provided in the outermost layer so that they
are arranged at intervals in a longitudinal direction of the
outermost layer; watermarks of letters or pictures formed in
the window portions; and a thread inserted between the
outermost layer and the other layer, the thread being
exposed at the window portions.
At this time, the ratio between the length (X) of the
window portions in the longitudinal direction of the paper
and the length (Y) in the same direction of non-window
portions between the window portions is set at 3:1 to 1:2 to
thereby securely prevent the formation of cockles when
- winding. the paper continuously in a roll and also to offer
preferable effect on the design on the paper surface.
The method of manufacturing the above anti-falsification
paper according to this invention comprises the steps of:
in making combination paper having at least two paper
layers including an outermost layer and the other layer by
using a cylinder paper machine provided with multiple vats;
(a) forming the other layer in a vat in front of a
final vat and then forming in the final vat the outermost
layer having window portions arranged at intervals in a
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direction of flow of the paper layer and also having
watermarks of letters or pictures in the window portions; or
(b) forming in a first vat the outermost layer having
- window portions arranged at intervals in a direction of flow
of the paper layer and also having watermarks of letters or
pictures formed in the window portions, and then forming in
a second or subsequent vat the other layer; and
immediately before putting the outermost layer and the
other layer together, inserting a thread between the layers
so that the thread runs through the window portions of the
outermost layer;
whereby combination paper is produced, in which the
watermarks are formed in the window portions of the
outermost layer and the thread is exposed at the window
portions.
According to an aspect of the present invention there
is provided an anti-falsification paper comprising
combination paper having at least two paper layers
including an outermost paper layer and an inner paper
layer, window portions of reduced paper thickness provided
in the outermost layer so that they are arranged at
intervals in a longitudinal direction of the outermost
layer, watermarks of letters or pictures formed in the
window portions the watermarks being of increased
thickness, and a thread inserted between the outermost
layer and the inner paper layer, the thread being exposed
at the window portions.
According to another aspect of the present invention
there is provided a method of making anti-falsification
paper with a cylinder paper machine having a plurality of
vats, the plurality of vats including a first vat and a
second vat, the method comprising, forming an inner paper
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layer in the first vat forming, in the second vat, an
outermost paper layer having window portions arranged at
intervals along a longitudinal direction of the outermost
paper layer forming watermarks in the window portions, the
watermarks having increased paper thickness inserting a
thread between the outermost paper layer and the inner
paper layer so that the thread is exposed through the
window portions of the outermost paper layer, wherein the
windows extend laterally beyond longitudinal edges of the
thread and putting together the outermost paper layer and
the inner paper layer, after inserting the thread, to form
combination paper having at least two paper layers
including the outermost layer and the inner layer, wherein
the watermarks are formed in the window portions of the
outermost paper layer and the thread is exposed at the
window portions.
According to a further aspect of the present invention
there is provided a method of making anti-falsification
paper using a cylinder paper machine having a plurality of
vats, the plurality of vats including a first vat and a
second vat the method comprising, forming an outermost
paper layer in the first vat, the outermost paper layer
including window portions arranged at intervals along a
longitudinal direction of the outermost paper layer forming
watermarks in the window portions of the outermost paper
layer, the watermarks having increased paper thickness
forming an inner paper layer in the second vat after
forming the outermost paper layer inserting a thread
between the outermost paper layer and the inner paper layer
such that the thread is exposed through the window portions
of the outermost paper layer and putting together the
outermost paper layer and the inner paper
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layer, after inserting the thread, to form combination
paper having at least two paper layers including the
outermost and the inner layers, wherein the watermarks are
formed in the window portions of the outermost paper layer
and the thread is exposed at the window portions.
Brief Description of the Drawings
Figure 1 is a plan view of an example of a gift
certificate that uses anti-falsification paper of this
invention;
Figure 2 is an enlarged view of a window portion of
Figure 1 as seen from above;
Figure 3 is an end view cut along the line A-A' of
Figure 2;
Figure 4 is a schematic view showing a cylinder paper
machine provided with multiple vats that can suitably be
used for the method of this invention;
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Figure 5 is a partial schematic view showing a mold for
making window portions and watermarks, mounted on a face
wire of a cylinder used in the cylinder paper machine of
Figure 4;
Figure 6 is a schematic view showing another example of
the cylinder paper machine provided with multiple vats that
can suitably be applied for the method of this invention;
and
Figure 7 is a partial schematic view showing a mold for
making window portions and watermarks, mounted on a face
wire of a cylinder used in the cylinder paper machine of
Figure 6.
Best Mode for Carrying out the Invention
The anti-falsification paper of this invention will be
described by taking an example of a gift certificate that
uses the anti-falsification paper comprising combination
paper having two paper layers, as shown in Figures 1, 2 and
3. The anti-falsification paper shown has two paper layers,
an outermost layer 3 and another layer 4, and the outermost
layer 3 has window portions 1 intermittently arranged in a
longitudinal direction (i.e., the flow direction of the
paper layer during paper making), with watermarks 2 of
letters or pictures in the window portions 1. A thread 5
is inserted between the outermost layer 3 and the layer 4
ad3acent thereto and is exposed at the window portions 1.
This invention also provides a method of securely and
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efficiently making anti-falsification paper of such a
construction as described above.
In practicing the method of making the anti-
falsification paper of this invention, a paper stock must
first be prepared. The stock is made by mixing and beating
an appropriate ratio of wood pulps such as conifer bleached
kraft pulp (NBKP), broad-leaved tree bleached kraft pulp
(LBKP) and conifer bleached sulfite pulp (NBSP) and non-wood
pulps such as hemp, cotton and straw, and adding appropriate
amounts of filler, dry paper strength agent, wet paper
strength agent, sizing agent, fixing agent, retention aid,
drainage aid, antifoaming agent, dye, coloring pigment,
fluorescent agent, etc. until the freeness is adJusted
ordinarily to 400-250 ml C.S.F.
In making combination paper having two or more paper
layers, a cylinder paper machine provided with multiple vats
is generally used. This invention, too, can use such a
cylinder paper machine. Figure 4 shows a cylinder paper
machine provided with two vats used to form combination
paper having two paper layers 3, 4 (Figure 3). This machine
includes a first vat 11 (in front of a final vat) to form a
paper layer 4, which has neither window portions 1 nor
watermarks 2, and a second vat 12 (final vat) for forming an
outermost paper layer 3 having window portions 1 and
watermarks 2.
The cylinder 12a in the vat 12 has a face wire 12b to
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which is attached by a fine metal wire, solder or bonding
agent a mold 13, as shown in Figure 5, that corresponds to
the window portion 1 and is made of metal, resin or paper.
Although the mold 13 corresponding to the window portion is
rectangular in this example shown, it may be formed square,
circle or oval or in other desired shapes. The mold 13 is
provided with perforated portions 13a that are formed by
through-holes to make watermarks 2 of letters or pictures.
In mounting the molds 13 of Figure 5 to the face wire
12b of the cylinder dipped in the vat 12 for making the
outermost layer 3, it is desirable that the molds 13 are
spaced from each other so that the ratio of a length X of
the window portion 1 in the direction of flow of the paper
layer (longitudinal direction of paper) indicated by an
arrow W to a length Y in the same direction of a non-window
portion 6 between the window portions is set in a range of
between 3:1 and 1:2. The reason why the space ratio of the
window portion 1 is set in this range is that this range of
the space ratio ensures the above-mentioned cockle
prevention effect when winding the paper in a roll and also
is desirable in terms of design on the paper surface.
The cylinder 11a in the vat 11 of the cylinder paper
machine of Figure 4 is provided with a face wire onto which
no mold is mounted. The paper layer 4 deposited on the
cylinder lla having the mold-free face wire is transferred
onto a blanket 14 and then carried to the cylinder 12a,
CA 02216527 1997-09-26
which is mounted with the molds 13 and,dipped in the vat 12,
where the outermost layer 3 formed by the cylinder 12a is
stacked on the first layer 4 to form a two-layer combined
sheet. A thread 5 is inserted at a location indicated by an
arrow V immediately before the layer 4 and the layer 3 are
combined together. It may be inserted at a location
indicated by an arrow V' before the cylinder 12a goes into a
suspension of paper stock in the vat 12. The methods of
inserting the thread 5 include one in which the thread is
fed through a supply pipe having projections and recesses in
its inner wall, as proposed by the above-mentioned Japanese
Patent Publication No. 5-40080/1993 filed by the same
applicant of this application, a method proposed by the
above-mentioned U.S. Patent No. 4462866, and the like.
Although the molds 13 attached to the cylinder 12a are
shown simplified only at scattered locations in Figure 4, it
is understood that they actually are attached to the entire
circumference of the cylinder 12a in a spaced configuration.
By using the above-described method of this invention,
the anti-falsification paper of a configuration shown in
Figures 1 to 3 can be manufactured. That is, the outermost
paper layer 3 deposited on the cylinder 12a having the molds
13 is formed with window portions 1 that are not deposited
with paper stock at locations corresponding to the molds 13
and in which are formed watermarks 2 of letters or pictures
deposited with the paper stock. The thread 5 is inserted
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between the paper layers 3 and 4 so that it runs through the
window portions 1. Hence, the thread 5 is exposed at window
portions 1 and embedded between the layers 3 and 4 at the
non-window portions 6.
In the method of manufacturing anti-falsification paper
according to this invention, it is possible to apply starch,
polyvinyl alcohol and various surface sizing agents to the
paper surface by using a size press device and the like
during paper making. Further, the paper may by subjected to
machine calender treatment or super calender treatment, as
required, to improve surface smoothness.
The thread 5 used in this invention may include a
variety of threads conventionally proposed for anti-
falsification, such as gold-silver thread, hologram thread,
magnetic thread, fluorescent thread and the like. The
gold-silver thread, for example, is made by vacuum-
evaporating and depositing metal aluminum over a polyester
film, applying a protective resin coating to the aluminum-
deposited surface, and slitting it into a thread by a
micro-slitter. By coloring the protective resin coating in
yellow, the thread thus formed has a golden color. The
thread is preferably applied with a heat sensitive adhesive,
which is activated by heat in the dry zone in the paper
making machine to make the adhesion between the thread and
the paper more secure.
As to the dimension of the mold 13 attached to the
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cylinder I2a of this invention, the length X in the
directioi~ of flow W of the paper layer shown in Figure 5 is
preferably set to 5-30 mm and the lateral length Z shown in
Figure 1 perpendicular to the flow direction to 10-50 mm.
This size of the mold 13 corresponds to that of the window
portion 1 of the paper shown in Figure 1. When the window
portion 1 is smaller than this range, the letters or
pictures watermarked in the window portion 1 become too
small; and when the window portion 1 is larger than this
range, the exposed length of the thread 5 becomes too long,
degrading the appearance in terms of balance of design.
The anti-fa7_sification paper of this invention is
manufactured ordinarily at a basis weight of 70-150 g/m2.
The ratio of combination between the outermost paper layer
and the other paper layer is preferably set in a range of
between 20:80 and 80:20. When, for example, two-layer
combination paper with a basis weight of 100 g/m2 has a
combination ratio of 20:80, this means that the paper
comprises 20 g/m2 of the outermost paper layer and 80g/m2 of
the other paper layer. If the combination ratio of the
outermost layer is less than 20, the watermarked letters or
pictures likely fail to be defined clearly. When the
combination ratio exceeds 80, the watermarks will easily
collapse.
In the above-described example method of this invention,
a plain paper layer with no windows or watermarks is formed
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in the first vat 11 (in front of the final vat), and then
the outermost layer having the window portions and the
watermarks is formed in the second vat 12 (the final vat),
as shown in Figure 4. This method, however, may be
transformed into the configuration shown in Figure 6, in
which the outermost paper layer having the window portions
and the watermarks is formed in the first vat 21 and the
plain paper layer is formed in the second vat 22 (final
vat). In this case, the molds 23 for forming the window
portions and watermarks are attached to the entire
circumference of the face wire of the cylinder 21a in the
first vat 21 by a means similar to the one described above.
Perforated portions 23a in the molds 23 used to watermark
letters or pictures are, as shown in Figure 7, reversed from
those shown in Figure 5.
Example 1
Preparation of stock
20 parts by weight of NBKP and 80 parts by weight of
LBKP were mixed and beaten into slurry having 350 ml C.S.F.,
to which were added 10 parts by weight of china clay, 0.3
parts by weight of paper strength agent (trade name
"Polystron 191" manufactured by Arakawa Kagaku Kogyo K.K.),
1.0 part by weight of sizing agent (trade name "Sizepine E"
manufactured by Arakawa Kagaku Kogyo K.K.) and an
appropriate amount of aluminum sulphate to prepare paper
stock.
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Manufacture of wire cloth
A number of resin plates, 10 mm wide by 25 mm long by
0.3 mm thick, were prepared. They were perforated at
portions 13a 1.2 mm wide to form letters "A" and "B" and
these perforated portions were arranged at equal intervals
to form the molds 13 (Figure 5). Then, the face wire 12b
(1300 mm wide) of the cylinder of the cylinder paper machine
was bonded with the molds 13 of resin plates by using an
adhesive, so that the molds were arranged in line at 5 mm
intervals in the direction of flow W of the paper layer.
Six such lines of molds were arranged on the face wire 12b
at equal intervals in the lateral direction.
Paper forming
In the cylinder paper machine having two vats as shown
in Figure 4, the cylinder 11a in the first vat is provided
with a face wire that has no mold while the cylinder 12a in
the second vat is mounted with a face wire l2b having the
molds 13. The above-described paper stock was deposited on
these wires at the rate of 50 m/min. to form a first paper
layer 4 from the first vat and a second paper layer 3
(outermost layer) from the second vat, with the second layer
overlying the first layer to form two- layer combined sheet.
During this process, a gold-silver thread 1.0 mm wide and 15
,u m thick was inserted between the first layer (a dry weight
equivalent of 50 g/m2) and the second layer (a dry weight
equivalent of 50 g/m2) at a location corresponding to the
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center of the molds 13 by using a method proposed in the
above-described Japanese Patent Publication No. 5-40080/
1993. Next, the wet web was dewatered in the ordinary way
and then dried by a cylinder drier, thus forming the
anti-falsification paper made of two-layer combination
paper. The paper thus formed was found to have window
portions 1 whose length X in the longitudinal direction of
the paper is 10 mm and the non-window portions 6 whose
length Y in the same direction is 5 mm, with letters "A" and
"B~' 1,2 mm wide watermarked in the window portions 1 and
with the thread 5 exposed at the window portions 1 and
embedded between the paper layers at the non-window portions
6. When the paper was wound in a roll by a winder of the
paper making machine, no cockles formed even after 6000
meters of paper had been wound.
Industrial Applicability of the Invention
According to the method of this invention described
above and the anti-falsification paper produced with this
method, the following significant advantages are obtained.
1) Because the watermarked letters or pictures 2 and
the exposed portion of the thread 5 are both located inside
the window portions 1, the anti-falsification paper has good
appearance in terms of design. When the paper is subjected
to printing, the limitation on the design to be printed that
arises when the watermarks 2 and the exposed portions of the
thread 5 are formed in different locations can be
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eliminated. Such limitation includes, for example, a
problem that the printing area is reduced when printing of a
decorative design is desirable.
2) When the paper is wound continuously in a roll by
the winder of the paper making machine, this invention can
prevent the formation of cockles, which would otherwise be
produced due to localized increase in paper thickness caused
by the inserted thread. This permits the use of a rotary
printing machine to print the rolled paper, making a
significant improvement in printing efficiency over the use
of bundle-finished paper.
3) When securities and the like made of this paper are
stacked up in large numbers, the stack can be handled easily
and will not easily collapse because there is no localized
bulge at the thread-inserted portion. Similarly, when a
large number of securities are stacked for automatic OCR
reading machine, easy handling is assured as they have no
localized bulge at the thread-inserted portion.
Because of these advantages, the anti-falsification
paper of this invention can be suitably applied to bank
notes, checks, stock certificates, bonds, gift certificates,
cards, confidential documents, passports, identification
cards, etc.
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