D E S C R I P T I O N
FORGERY PREVENTING MEMBER, FORGERY PREVENTING
SHEET, AND METHODS OF MANUFACTURING THE SAME
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Technical Field
The present invention relates to a forgerypreventing
sheet, i.e., a sheet having a forgery
preventing effect, and a fibrous or flaky forgery
10 preventing member usable in the manufacture of the
forgery preventing sheet, and methods of manufacturing
the same.
Background Art
Various forgery preventing sheets manufactured
15 from a stock containing cellulose fibers and fibrous or
flaky members providing a forgery preventing effect are
known.
i For example, International Publication WO
2009/119879 describes a sheet containing fibrous
20 members having a pearly luster. Japanese Patent
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No. 3075454 describes a sheet containing flaky members
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having a pearly luster. The pearly luster of the
above-mentioned members of these sheets cannot be
reproduced even when the sheets are copied by a color
25 copying machine, or scanned by a scanner and the
scanned images are printed out by using an inkjet
printer. Accordingly, these sheets are suitably usable
in printed matter required to have a forgery preventing
2
measure.
A sheet containing circular flaky members having a
diameter of 1 to 2 mm which are called planchettes is
described in Shun Uemura, "Bank Notes of the World", I
5 Insatsu Choyokai Foundation (1987), p. 356. The I
planchettes are obtained from a sheet-like material I
such as colored paper or fluorescent color generating J
paper that emits light when irradiated with ultraviolet J
rays. This sheet was used as, e.g., a 50-dollar bill
10 in Canada.
U.S. Patent No. 3565985 describes a special film
called a "multilayered light interference film". The
multilayered light interference film has a structure of
alternately stacked, a hundred and a few ten plastic I
15 layers having different refractive indices, and shows 1
an interference color derived from the structure. The I
multilayered light interference film is obtained by I
forming a multilayered structure by melt extrusion, and
drawing the structure. AS the multilayered light
20 interference film, "Aurora Film" (trade name) of
Engelhard and "MLF Film" (trade name) of Teijin DuPont
I are known. Flaky members punched out of the
multilayered light interference film are called
glitters. A sheet containing the glitters was used as
25 a 100-guilder bill in the Netherlands and a 200-peso
bill in Mexico.
A sheet into which are mixed thread products
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called security threads having a good forgery
| preventing effect is also widely known. There are two J
types of sheet. One is an embedded sheet described in,
e.g., Jpn. Pat. Appln. KOKOKU Publication No. 0 6-
5 062030, having the thread products embedded between
paper layers. The other is a sheet called "windowed
thread inserted paper" described in, e.g., Japanese
Patent No. 2845197, having a window formed in the
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| surface and the threaded products partially exposed to
10 this window.
As the materials of the threads, various special
films providing the forgery preventing effect are used.
A typical example is a hologram film. The threads have
| an adhesive layer formed on their surfaces. In a
15 papermaking step, therefore, the threads adhere to
cellulose fibers forming the paper. As a result, the
removal of the threads from the finished sheet is
prevented.
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Disclosure of Invention
20 The above-described sheets are required to prevent
the removal of the members providing the forgery
preventing effect from the sheet during printing, in
the stage of distribution, and the like. Various
measures have been taken for this purpose.
25 For example, International Publication WO
2009/119879 describes the concomitant use of fibrous
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members having a pearly luster, i.e., optically
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coherent fibers, cellulose fibers, and binder fibers.
The binder fibers play the role of preventing easy
removal of the optically coherent fibers from the
| paper. This literature describes that as the binder
5 fibers, use may be made of, e.g., ethylene-vinyl
alcohol copolymer fibers, core-sheath type binder
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fibers, or divided type binder fibers.
This measure does not improve the adhesion of the
optically coherent fibers themselves to the cellulose
10 fibers. Therefore, a sufficient effect can not be
! achieved unless the addition amount of the binder
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| fibers is increased to, normally, 10% or more. This
increases the cost and, in addition, readily poses the
problem that the binder fibers melt in a drying zone of
15 a paper machine and contaminate the surface of a canvas
or dryer.
Furthermore, International Publication WO
| 2009/119879 describes forming a resin layer covering at
least one surface of the paper. This resin layer
| 20 typically plays the role of covering the surface
containing the optically coherent fibers to prevent i
easy removal of the optically coherent fibers contained
in the surface region of the paper by, and the role of
improving the flatness of the paper to facilitate,
25 e.g., the formation of a printing layer. A transparent
resin is typically used as the material of this resin
layer. As the material of the resin layer, a polyester
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resin, a polyurethane resin, an acrylate ester resin, I
an acrylate ester copolymer resin such as a styrene- I
acrylate ester copolymer resin, a vinyl acetate resin, J
a polyacrylamide resin, a melamine resin, a urea resin, 1
5 polyvinyl alcohol and its derivative, starch and its I
| derivative, a cellulose derivative, and casein are §
used. The resin layer is formed by a size press
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| apparatus of a paper machine, or a coater such as a
gravure coater, roll coater, air knife coater, blade
| 10 coater, or bar coater.
! In this measure, the interference color of the
optically coherent fibers may weaken with the coating
of the paper with the transparent resin layer, so the
thickness of the transparent resin layer must be
15 minimized. However, such control is difficult. In
addition, the cost rises because the additional step of
coating the paper with the transparent resin layer is
necessary after the papermaking step.
As to the sheet containing the planchettes or
i 20 glitters, the planchettes or glitters may transfer to
the blanket during high ink tack printing such as
offset printing.
The present inventors have also discovered the
following fact. When fibrous or flaky members are
25 manufactured from a sheet-like material having adhesive
layers on both of its surfaces by using a method such
as cutting using a guillotine cutter or micro slitter,
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or punching, the frictional heat of the blade or the
pressure sometimes melts or softens the adhesive
layers, thereby adhering these members to each other.
| If paper is made by using such members as a part of the
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! 5 paper stock, the problem that these members exist in
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the form of a mass or they look connected to each other
arises.
It is an object of the present invention to solve
these problems. Specifically, it is an object of the
| 10 present invention to achieve a high offset
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printability, i.e., a property of preventing easy
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j removal of fibrous or flaky members providing a forgery
! preventing effect from a sheet when the sheet is
subjected to offset printing, and prevent these members
15 from adhering to each other when papermaking is carried
I out.
According to a first aspect of the present
invention, there is provided a method of manufacturing
a forgery preventing member, comprising forming a first
20 adhesive layer capable of adhering to paper, on one
surface of a sheet substrate which provides a forgery
preventing effect, forming a second adhesive layer
capable of adhering to the paper, on the other surface
of the sheet substrate, superimposing the sheet
25 substrate and a first water-soluble sheet or unsized
paper, with the first adhesive layer being sandwiched
therebetween, superimposing the sheet substrate and a
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second water-soluble sheet or unsized paper, with the I
second adhesive layer being sandwiched therebetween, J
and cutting or punching the sheet substrate on which 6
I the first adhesive layer and the second adhesive layer 1
| 5 are formed, with the sheet substrate being sandwiched I
between the first water-soluble sheet or unsized paper j
and the second water-soluble sheet or unsized paper, to J
produce a fibrous or flaky forgery preventing member. j
According to a second aspect of the present
10 invention, there is provided a method according to the
first aspect, wherein the sheet substrate has optical
coherence.
According to a third aspect of the present
invention, there is provided a method according to the
15 first or second aspect, further comprising adhering the
first water-soluble sheet or unsized paper to the sheet
substrate by the first adhesive layer before the
cutting or punching; and adhering the second watersoluble
sheet or unsized paper to the sheet substrate
20 by the second adhesive layer before the cutting or
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punching.
According to a fourth aspect of the present
invention, there is provided a method of manufacturing
a forgery preventing sheet, comprising forming a first
25 adhesive layer capable of adhering to paper, on one
surface of a sheet substrate which provides a forgery
preventing effect, forming a second adhesive layer
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capable of adhering to the paper, on the other surface
| of the sheet substrate, superimposing the sheet
substrate and a first water-soluble sheet or unsized
paper, with the first adhesive layer being sandwiched
5 therebetween, superimposing the sheet substrate and a
second water-soluble sheet or unsized paper, with the
second adhesive layer being sandwiched therebetween,
cutting or punching the sheet substrate on which the
first adhesive layer and the second adhesive layer are
! 10 formed, with the sheet substrate being sandwiched
| between the first water-soluble sheet or unsized paper
and the second water-soluble sheet or unsized paper, to
produce a fibrous or flaky forgery preventing member,
and carrying out papermaking by using the forgery
| 15 preventing member, a papermaking fiber and a
papermaking subsidiary material, as raw materials.
I According to a fifth aspect of the present
invention, there is provided a method according to the
fourth aspect, further comprising adhering the first
20 water-soluble sheet or unsized paper to the sheet
substrate by the first adhesive layer before the
cutting or punching, and adhering the second watersoluble
sheet or unsized paper to the sheet substrate
by the second adhesive layer before the cutting or
25 punching.
According to a sixth aspect of the present
invention, there is provided a method according to the
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fourth or fifth aspect, wherein the papermaking j
comprises producing a multilayered structure including 1
a pair of surface layers formed by using the forgery
preventing member, and an inner layer interposed
5 between the surface layers.
According to a seventh aspect of the present
invention, there is provided a fibrous or flaky forgery
preventing member comprising a substrate which provides
a forgery preventing effect, a pair of adhesive layers
10 disposed on both surfaces of the substrate, and a pair
of water-soluble sheets or unsized papers opposing each
other with the substrate and the pair of adhesive
layers being sandwiched therebetween, and joined to the
adhesive layers, respectively.
15 According to a eighth aspect of the present
! invention, there is provided a forgery preventing sheet
I comprising one or more first layers each obtained from j
| J
I a paper stock containing a papermaking fiber, a !
papermaking subsidiary material, water and a fibrous or j
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20 flaky forgery preventing member, the forgery preventing j
member including a substrate which provides a forgery s
preventing effect, a pair of adhesive layers formed on
both surfaces of the substrate, and a pair of watersoluble
sheets or unsized papers opposing each other
25 with the substrate and the pair of adhesive layers
being sandwiched therebetween, and joined to the j
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adhesive layers, respectively. <
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! According to a ninth aspect of the present
invention, there is provided a forgery preventing sheet
according to the eighth aspect, further comprising one
or more second layers interposed between the pair of j
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5 first layers. 1
According to a tenth aspect of the present j
invention, there is provided a forgery preventing sheet 18
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according to the eighth or ninth aspect, wherein the |
substrate has optical coherence. 1
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10 Brief Description of Drawings j
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FIG. 1 is a plan view schematically illustrating a j
i forgery preventing sheet according to an embodiment of
the present invention.
FIG. 2A is a sectional view schematically
15 illustrating an example of a structure adoptable to the i
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sheet illustrated in FIG. 1. I
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I FIG. 2B is a sectional view schematically j
illustrating another example of the structure adoptable
to the sheet illustrated in FIG. 1. j
20 FIG. 3 is a sectional view schematically
illustrating an example of a member providing a forgery
preventing effect to the sheet illustrated in FIG. 1.
FIG. 4 is a sectional view schematically
illustrating an example of a forgery preventing member
25 usable in the manufacture of the sheet illustrated in ;
FIG. 1.
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Modes for Carrying Out the Invention j
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Embodiments of the present invention will be j
described below with reference to the drawings.
Throughout the drawings, elements exerting the same or
5 similar function are labeled with the same reference
symbol, and their repeated explanations are omitted.
FIG. 1 is a plan view schematically illustrating a
forgery preventing sheet according to an embodiment of
the present invention. FIG. 2A is a sectional view
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10 schematically illustrating an example of a structure j
adoptable to the sheet illustrated in FIG- 1. FIG. 2B j
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is a sectional view schematically illustrating another j
example of the structure adoptable to the sheet I
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illustrated in FIG. 1. FIG. 3 is a sectional view j
! 15 schematically illustrating an example of a member for
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providing a forgery preventing effect to the sheet j I illustrated in FIG. 1. FIG. 4 is a sectional view j
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| schematically illustrating an example of a forgery j
j
I preventing member usable in the manufacture of the j
20 sheet illustrated in FIG. 1. j
A forgery preventing sheet 1 illustrated in FIG. 1
includes a sheet body 3, and fibrous or flaky forgery
preventing members 2. The sheet body 3 is constituted
of papermaking fibers, typically, cellulose fibers, and
25 a papermaking subsidiary material.
The sheet 1 illustrated in FIG. 2A has a single- j
layered structure. In the structure illustrated in j
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FIG. 2A, the forgery preventing members 2 are almost j
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evenly distributed over the entire sheet 1.
The sheet 1 illustrated in FIG. 2B has a i
multilayered structure including an inner layer lb, and
5 a pair of surface layers la sandwiching the inner layer
lb. In the structure illustrated in FIG. 2B, the
forgery preventing members 2 are almost evenly
distributed over the entire surface layers la and lb,
respectively.
10 The forgery preventing member 2 is, e.g., fibrous.
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The member 2 may also be a flake having an arbitrary
shape, e.g., a circular or elliptical shape, or a
polygonal shape such as a square, rectangular, rhombic,
pentagonal, or hexagonal shape.
15 Note that the term "fibrous" used for the forgery
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preventing member 2 means that when the member 2 is I
viewed in its thickness direction, the member 2 has a j
short side having a smaller length (width), and a long I
side having a larger length. Usually, the length of j
20 the short side is set at about 0.05 to 2 mm, and that
of the long side is set at about 5 to 20 mm. Note also i
that the size of a flake is set at about 0.5 to 5 mm.
As illustrated in FIG. 3, the forgery preventing
member 2, which the sheet 1 contains, includes a
25 substrate 21, and a pair of adhesive layers 22 formed
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on the both surfaces of the substrate 21. j
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The substrate 21 is manufactured from a sheet j
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substrate providing the forgery preventing effect,
e.g., a polymer film, paper, or nonwoven fabric so j
prepared as to provide the forgery preventing effect.
The adhesive layers 22 adhere the substrate 21 to the
5 papermaking fibers in a drying zone of a paper machine,
thereby preventing the removal of the forgery
preventing members 2 from the sheet 1. Note that the
substrate 21 and adhesive layers 22 will be explained
later in detail.
10 The present inventors made extensive studies, and j
have found that the manufacture of the forgery
preventing members 2 poses the following problem. When
manufacturing the forgery preventing members 2 by
forming the adhesive layers on the two surfaces of the j
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15 sheet substrate which provides the forgery preventing j
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effect and cutting or punching the obtained stack, the j
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i j frictional heat of the blade sometimes melts or softens j i
the adhesive layers, or the pressure sometimes adheres j
j the forgery preventing members 2 to each other. If j
20 paper is made by using such members 2 as a part of the ]
paper stock, the problem that the members 2 exist in the form of a mass or they look connected to each other
arises.
In this embodiment, therefore, the sheet substrate
25 on the two surfaces of which the adhesive layers are
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formed is sandwiched between water-soluble sheets or j
unsized papers, and the sheet substrate sandwiched j
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between the water-soluble sheets or unsized papers is
cut or punched, thereby obtaining fibrous or flaky
forgery preventing members. During cutting or
| punching, the water-soluble sheet or unsized paper
| 5 prevents the above-mentioned problem caused by the
blade touching the adhesive layer, or reduces the
contact area between the blade and adhesive layer. In
addition, during cutting or punching, the water-soluble
sheet or unsized paper reduces the area of an exposed
10 portion of the adhesive layer. Accordingly, this j
j
method can avoid the aforementioned problem. I
In addition, when cutting or punching is performed
while the water-soluble sheets or unsized papers is in
contact with the adhesive layers by using this method,
15 a forgery preventing member 2 further including the cut
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or punched water-soluble sheets or unsized papers 31 is j
obtained as illustrated in, e.g., FIG. 4. When i
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bringing such forgery preventing member 2 into contact I
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with water, e.g., when preparing a paper stock j
20 containing the forgery preventing members 2, j
papermaking fibers, a papermaking subsidiary material,
and water, the water-soluble sheets dissolve in the
water, and the unsized papers disintegrates into
cellulose fibers. Therefore, the water-soluble sheets
25 or unsized papers 31 exerts no adverse effect on
papermaking.
Next, the materials of the forgery preventing i
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I sheet 1 and forgery preventing members 2 and methods of j
| manufacturing the same will be explained.
In the manufacture of the forgery preventing sheet
I 1, a sheet substrate is first prepared.
5 The sheet substrate includes a polymer film,
paper, or nonwoven fabric. The sheet substrate
provides the forgery preventing effect. For example,
the sheet substrate has undergone processing for (
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providing the forgery preventing effect. As the sheet j
I 10 substrate, it is possible to use any well-known, sheet
| product having a good forgery preventing effect. 1
I Examples of a polymer film usable as the sheet
| substrate are polymer films themselves having a good
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forgery preventing effect, including polyolefin films
I 15 such as a polyethylene film and polypropylene film; a I
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polyvinyl chloride film; polyester films such as a j
j
polyarylate film and polyethyleneterephthalate film; a j
polymethyl methacrylate film; a polycarbonate film; a ;
polyimide film; a polyether sulfone film; a polysulfone
20 film; a polystyrene film; a polyvinyl alcohol film; 1
cellulose films such as a cellulose acetate film, j
cellulose diacetate film, cellulose triacetate film, ;
and cellophane; a polymer film made of a liquid crystal
polymer; and a multilayered light interference film.
25 These polymer films may also contain, as an additive, a
coloring agent, white inorganic pigment, antioxidant, j
antistatic agent, lubricant or a combination thereof. j
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The thickness of the polymer film is normally 10 to I
40 |jm. I
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Paper usable as the sheet substrate is
manufactured by using a paper machine from a paper
5 stock containing papermaking fibers as a main
component, various papermaking subsidiary materials,
and a material providing the forgery preventing effect.
As the papermaking fibers, cellulose fibers are
typically used. As the cellulose fibers, a pulp is j
I !
| 10 typically used. In addition to the cellulose fibers, i j
I the paper stock can also contain one or more of j
j
synthetic fibers, metal fibers, glass fibers, and | 1
carbon fibers. It is also possible to use a plurality j
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| of types of pulps. Practical examples are papermaking j
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15 pulps such as Northern Bleached Kraft Pulp (NBKP), j
: Laubholz Bleached Kraft Pulp (LBKP), Northern Bleached j
Sulfite Pulp (NBSP), and Thermo Mechanical Pulp (TMP). j
These pulps are beaten by using a beater or disk
refiner, and a paper stock is prepared by adding !
20 papermaking subsidiary materials to the beaten pulps. j
Examples of the papermaking subsidiary materials are J
various fillers such as white clay, kaolin, calcium
carbonate, titanium dioxide, and aluminum hydroxide;
synthetic fibers; a dry strengthening agent; a wet
25 strengthening agent; a sizing agent; a retention aid;
an antifoaming agent; a coloring dye; a coloring j
pigment; a fluorescent brightening agent; and a fixing i
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agent. It is also possible to mix, in the paper stock, |
a well-known material for providing the forgery j
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preventing effect, e.g., fibers that emit fluorescence j
when irradiated with ultraviolet rays, or fine j
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5 particles that emit fluorescence when irradiated with j
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ultraviolet rays. J
Paper is manufactured from the above-mentioned
paper stock by using a well-known paper machine such as
1 a Fourdrinier paper machine, cylinder paper machine, j
I 10 tanmo paper machine, or twin wire paper machine. The !
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| surface of the paper is coated with a sizing agent or j
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paper-strengthening agent by using a size press i
apparatus or the like during the drying step. The
basis weight of the paper is normally set at 20 to
| 15 200 g/m2.
Nonwoven fabric used as the sheet substrate can be 1
manufactured by, e.g., a wet method. The nonwoven {
fabric can also be manufactured by a well-known dry j
method such as a spunbond method, melt-blown method, j
20 spunlace method, needle punch method, or stitchbond ]
method. Fibers as the material of the nonwoven fabric j
can also be used together with a substance providing
the forgery preventing effect, e.g., fibers that emit
fluorescence when irradiated with ultraviolet rays.
25 The basis weight of the nonwoven fabric is normally set
at 20 to 100 g/m2. j
Various kinds of processing can be made on the
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! surface of the sheet substrate. For example, the 1
surface of the paper can be coated with a coating !
solution made of a pigment such as kaolin, titanium !
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oxide or calcium carbonate, an adhesive such as starch,
5 styrene-butadiene rubber (SBR) latex, methacrylate
ester-butadiene rubber (MBR) latex, or acrylic I
emulsion, and other coating subsidiary materials, by !
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using a coater such as a blade coater, air knife i
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coater, or roll coater. The coating amount is normally i
9 i
10 set at 3 to 20 g/mz on the dry mass basis. j
Processing for preventing forgery can be made on j
the surface of the sheet substrate. For example, ink I
containing a pearl pigment, a color pigment, a j
j
cholesteric liquid crystal pigment, a magnetic powder, j
]
15 a metal powder, or a dye or pigment that emits j
fluorescence when irradiated with ultraviolet rays, a
binder, and other additives can be printed by using a
well-known printing method such as an offset printing
method, plate printing method, relief printing method,
20 screen printing method, gravure printing method, or
flexo printing method.
It is also possible to combine a plurality of
kinds of inks. For example, when using a pearl
pigment, it is possible to prepare two or more kinds of
25 inks by using pigments having different interference
colors, and print stripe patterns. Similar patterns
can also be printed by using, instead of the pearl
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\ pigment, fluorescent materials of two or more colors
that emit fluorescence when irradiated with ultraviolet
1 rays. Patterns can also be printed by using a
combination of two or more kinds of pigments, e.g., a
5 combination of a pearl pigment and metal powder, or a
J combination of a magnetic powder and color pigment.
Furthermore, the sheet substrate itself can be dyed by
using a well-known method.
When the sheet substrate includes a film, it is
10 possible to form, e.g., a hologram, metal vapor
deposition layer, multilayered vapor deposition layer,
or cholesteric liquid crystal layer on the film.
;
j Patterning such as demetallized processing can also be
made on the metal vapor deposition layer or
15 multilayered vapor deposition layer. Patterns of a
fluorescent material, magnetic powder, or pearl pigment
; can be printed on the film or these layers. In
particular, a forgery preventing member obtained by
using an optically coherent substrate that changes the
:; 20 intensity or color of reflected light or scattered
light in accordance with a viewing angle provides a
good forgery preventing effect to the sheet, and shows
- a high visibility.
Then, adhesive layers capable of adhering to paper
j 25 are formed on the both surfaces of the sheet substrate.
The adhesive layers melt or soften in the drying
zone of a paper machine, and adhere to the papermaking
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fibers as a main component of paper. As the adhesive,
it is possible to use known adhesives that soften, melt
or swell when heated by the dryer of a paper machine,
and strongly adhere to the papermaking fibers.
5 Examples are water-based and solvent-based known
adhesives such as a polyvinyl acetate resin-based
; adhesive, polyvinyl chloride resin-based adhesive,
polyester resin-based adhesive, polyacrylic ester
• resin-based adhesive, ethylene-vinyl acetate copolymer
10 resin-based adhesive, and polyvinyl alcohol resin-based
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adhesive. Adhesive layers are formed by coating the
I surfaces of the substrate with one or more of these
adhesives by using a known coater such as a roll coater
', or gravure coater. The coating amount is normally 0.1
15 to 10 g/m^ on the dry mass basis. To improve the
adhesion between the sheet substrate and adhesive
layers, a corona discharge processing or primer agent
coating can be made before the adhesive coating. When
using a thermoplastic adhesive, it is possible to
20 preferably use a resin having a glass transition point
of -30°C to 50°C, and more preferably, a resin having a
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glass transition point of -20°C to 30°C. If the glass
transition point is less than -30°C, the adhesive
layers have adhesiveness even at room temperature. If
25 the glass transition point exceeds 50°C, the adhesive
layers hardly adhere to the papermaking fibers in the
dryer zone of a paper machine.
j
The solubility of a water-soluble or hot watersoluble
resin such as a polyvinyl alcohol resin
strongly depends on the polymerization degree and
saponification degree, particularly, the saponification
5 degree. For example, a resin having a saponification
degree of 88% or less completely dissolves in water at
about 20°C. By contrast, to dissolve a resin having a
saponification degree of 97% in water, the water
temperature must be increased to about 50°C or more.
10 Also, to dissolve a completely saponified resin in
water, the water temperature must be increased to about
80°C or more. It is preferable to use a resin having a
minimum dissolution temperature, i.e., a hot water
dissolution temperature of 60°C to 80°C. If a resin
15 having a hot water dissolution temperature of less than
60°C is used, the resin may excessively swell or
; dissolve in the drying zone of a papermaking step.
Also, if the dissolution temperature of a resin exceeds
80°C, high-temperature heating is necessary to prepare
20 a paper stock from collected spoilage or waste paper.
Such heating is difficult and dangerous. Note that
when using a polymer film as the sheet substrate and a
polyvinyl alcohol resin-based adhesive as the adhesive,
; a well-known primer agent layer made of a polyurethane
25 resin or the like can be formed between them in order
to improve the affinity between them.
After the adhesive layers are formed on the both
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surfaces of the sheet substrate, the sheet substrate is
sandwiched between unsized papers or water-soluble
sheets. It is also possible to form an adhesive layer
on one surface of the sheet substrate, superpose the
5 sheet substrate and the unsized paper or water-soluble
sheet with this adhesive layer being sandwiched between
them, form another adhesive layer on the other surface
of the sheet substrate, and superpose the sheet
substrate and the unsized paper or water-soluble sheet
10 with this adhesive layer being sandwiched between them.
When manufacturing the forgery preventing members
2, the unsized paper or water-soluble sheet plays a
role of preventing the above-described problem, i.e.,
i
; preventing the forgery preventing members 2 from
15 directly adhering to each other. Note that even when
: the unsized paper or water-soluble sheet adheres to the
adhesive, the unsized paper or water-soluble sheet
disintegrates or dissolves when added to the paper
stock for manufacturing the forgery preventing sheet 1.
20 Accordingly, the use of the unsized paper or watersoluble
sheet poses no problem.
The unsized paper is, e.g., paper containing no
: sizing agent. The unsized paper has a characteristic
that it decomposes into cellulose fibers within an
25 extremely short time. As will be explained below, the
I unsized paper is manufactured from a paper stock
containing cellulose fibers as a main component by
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using a paper machine.
As the papermaking fibers, a pulp is typically
used. It is also possible to use a plurality of types
of papermaking fibers. Practical examples are
5 papermaking pulps such as Northern Bleached Kraft Pulp
(NBKP), Laubholz Bleached Kraft Pulp (LBKP), Northern
Bleached Sulfite Pulp (NBSP), and Thermo Mechanical
Pulp (TMP). The unsized paper is manufactured by,
e.g., the following method. First, a pulp is beaten to
10 have a freeness of, usually, 200 to 500 mL C.S.F. by
using a beater or disk refiner. Then, a paper stock
containing cellulose fibers obtained by the beating is
I prepared basically without using any other papermaking
subsidiary material. Thereafter, unsized paper having
15 a basis weight of, e.g., 20 to 80 g/n\2 is manufactured
i
j from the above paper stock by using a well-known paper
machine such as a Fourdrinier paper machine, cylinder
paper machine, tanmo paper machine, or twin wire paper
machine.
20 So-called water-disintegratable paper can also be
used as the unsized paper. The water-disintegratable
• paper means paper having the properties that in a dried
i state, the adhesive force between the fibers forming
the paper is strong enough to maintain the form of
25 paper, but, when the paper is dipped in water, the
adhesive force extremely decreases, and the paper
: readily decomposes or disperses if an external force is
I I
i
applied. As the water-disintegratable paper, it is
possible to use any water-soluble paper disclosed in
Jpn. Pat. Appln. KOKAI Publication Nos. 2006-002296,
2006-307384, 2006-180983, 2006-002277, and the like.
5 In the manufacture of the unsized paper, it is
preferable to use a pulp having a short fiber length.
An example of the pulp having a short fiber length is
the above-mentioned Laubholz Bleached Kraft Pulp
(LBKP). The fiber length of a softwood pulp is
10 normally about 1.5 to 5.5 mm. By contrast, the fiber
length of a hardwood pulp is normally about 0.5 to
2.5 mm. This fiber length is shorter than the normal
length of the fibrous forgery preventing members 2.
! When performing cutting or punching described later,
; 15 therefore, this advantageously decreases the rate of
the pulp fibers adhering to the cut section of the
adhesive layer by the pressure or frictional heat.
When manufacturing the fibrous forgery preventing
•
members 2, it is preferable to use the unsized paper
20 having a high aspect ratio, and perform cutting or
punching such that the longitudinal direction of the
unsized paper matches the long-side direction of the
forgery preventing members 2. This decreases the rate
•
of the pulp fibers adhering to the cut section of the
'•
25 adhesive layer by the pressure or frictional heat.
; The water-soluble sheet is a water-soluble film or
'• sheet, and dissolves or disintegrates in water.
•
' I
. * 25
Examples of a well-known, water-soluble film or sheet
are a cellulose-based, water-soluble film or sheet such
as sodium salt of carboxymethylcellulose, a polyvinyl
alcohol-based, water-soluble film or sheet, a
5 polyether-based, water-soluble film or sheet such as
polyethyleneoxide, and a polysaccharide-based, watersoluble
film or sheet such as pullulan. Any of these
films or sheets can be used in the present invention.
A typical example of the water-soluble sheet is
10 water-soluble paper. As the water-soluble paper, it is
possible to use, e.g., paper manufactured by a method
1 (e.g., Jpn. Pat. Appln. KOKOKU Publication No. 40-968)
\ in which carboxymethylcellulose is mixed in a
papermaking material such as a pulp, making paper
15 therefrom and converting the carboxymethylcellulose
into its alkali metal salt by an alkali agent. As the
water-soluble paper, it is also possible to use waterdispersible,
water-soluble paper (Japanese Patent
No. 2549159) manufactured by incorporating, into fibers
20 such as wood pulp fibers, an alkali metal salt of
carboxymethylcellulose, and one or more salts selected
from the group consisting of water-soluble salts of an
alkaline earth metal, manganese, zinc, cobalt and
nickel. The thickness of the water-soluble film is
25 usually 10 to 50 |^m. The basis weight of the watersoluble
paper is usually 30 to 80 g/mz.
Examples of the method of superposing the unsized
i
-
I
1
i
!
. ** 26
paper or water-soluble sheet on the adhesive layer will
be described below.
Method Al:
The unsized paper or water-soluble sheet and the
5 sheet substrate on the both surfaces of which the
adhesive layers are formed are cut into an appropriate
size. Then, these materials are superimposed by, e.g.,
manual procedures such that each cut sheet substrate is
sandwiched between a pair of the cut unused paper or
10 water-soluble sheets.
Method A2:
Two or more rolls of the unsized paper or watersoluble
sheet and one or more rolls of the sheet
substrate having the adhesive layers formed on the both
15 surfaces are prepared. Then, the unsized paper or
water-soluble sheet and the sheet substrate are fed
i from these rolls, and superimposed such that each sheet
substrate is sandwiched between the unsized paper or
water-soluble sheets. After that, the obtained
20 multilayered structure is cut by using a cutter or
punched.
Method A3:
; First, the both surfaces of the sheet substrate
are coated with the adhesive by using a gravure
25 coater/laminator including a floating dryer zone.
; Then, in the laminator section, the unsized paper or
•
water-soluble sheets are fed from rolls, and weakly
;
;
I
j
. w 27
adhered on the both surfaces of the sheet substrate.
After that, the obtained multilayered structure is
passed through cooling rolls, and subsequently wound
around a roll. In addition, this multilayered j
5 structure is cut by using a cutter or punched.
As described above, any method can be adopted as
long as the adhesive layer formed on the surface of the
1 sheet substrate is not brought into direct contact with
I the adhesive layer formed on the surface of another
. 10 sheet substrate.
In methods A2 and A3, the unsized paper or watersoluble
sheets are overlaid, by weak adhesion or no
: adhesion, on the adhesive layers formed on the both
surfaces of the sheet substrate, and the obtained
15 multilayered structure is cut or punched. This cutting
:
or punching can be performed by using any known method.
, Typical examples of the method will be described below.
Method Bl:
A cutter called a guillotine including a
20 vertically movable blade is used. This method can form
:<
'}
the forgery preventing members 2 into fibrous members,
\ and also flaky members such as rectangular and square
I members.
Method B2:
25 A micro slitter is used. This method can also
form the forgery preventing members 2 into fibrous
members, and also flaky members such as rectangular and
:
• 28
square members.
Method B3:
A punching machine including a punching mechanism
is used. This method can form the forgery preventing
5 members into flaky members such as circular and
hexagonal members.
Method B4:
This method manufactures flaky forgery preventing
members 2 by performing punching by using a rotary
10 cutter.
Method B5:
! This method manufactures flaky forgery preventing
members 2 by using a feeding mechanism that
] intermittently feeds the substrate, and a punching
15 apparatus including a plurality of blades. These
i blades include a plurality of first blades that extend
in the feeding direction of the feeding mechanism and
are arranged in the widthwise direction perpendicular
to the feeding direction, and a second blade installed
i
20 after the first blades and extending in the widthwise
direction. This method can manufacture square or
rectangular forgery preventing members. Note that by
changing the layout or the like of these blades, it is
also possible to manufacture forgery preventing members
25 having a shape other than the square or rectangle,
5 e.g., forgery preventing members having the shape of a
triangle, rhombus, pentagon, hexagon, star, circle, or
:
• 29
crescent.
In methods A2 and A3, the adhesive layers are
protected from contacting other articles by the unsized
paper or water-soluble sheets. When manufacturing the
5 forgery preventing members 2 by using these methods,
therefore, the adhesive layers neither melt nor soften
by the frictional heat of the blade, and the forgery
preventing members 2 do not adhere to each other by the
pressure.
10 Next, the manufacture of the forgery preventing
sheet 1 using the forgery preventing members 2 will be
) explained.
i First, a paper stock containing one or more pulps
•
; as a main component and a papermaking subsidiary
15 material is prepared by a conventional method. As the
• pulps, it is possible to use wood pulps such as
Northern Bleached Kraft Pulp (NBKP), Laubholz Bleached
! Kraft Pulp (LBKP), Northern Bleached Sulfite Pulp
(NBSP), and Thermo Mechanical Pulp (TMP); non-wood
•
20 pulps such as a cotton pulp, hemp pulp, and straw pulp;
or a mixture thereof. Examples of the papermaking
subsidiary material are fillers such as white clay,
•
kaolin, calcium carbonate, titanium dioxide, and
•
aluminum hydroxide; a sizing agent such as a rosin-
25 based sizing agent; a dry strength agent such as a
polyacrylamide-based dry strength agent; a wet strength
agent such as a polyamide epichlorohydrin resin; a
i
. 30
fixing agent; a retention aid; a drainage aid; an
antifoaming agent; or a combination thereof. The
freeness of the paper stock is set at, e.g., 550 to
250 mL C.S.F.
5 The forgery preventing sheet 1 can be manufactured
by using the above-mentioned paper stock or another
paper stock as will be explained below.
Method CI:
First, the forgery preventing members 2 are mixed
10 in the above-described paper stock. From the paper
stock thus obtained, a sheet is made by using a paper
machine such as a Fourdrinier paper machine, cylinder
i paper machine, or tanmo paper machine.
\ Method C2:
: 15 The forgery preventing members 2 are sprinkled
over a web obtained from the above-described paper
! stock at the wet part or wire part of a Fourdrinier
paper machine.
Method C3:
i 20 The above-described paper stock is supplied from a
\ flow box to a Fourdrinier of a Fourdrinier paper
;
s
machine, and a paper stock containing the forgery
preventing members 2 is discharged toward the
I
Fourdrinier from a plurality of nozzles arranged in the
: 25 widthwise direction in a position immediately before or
after the slice.
• 31
Method C4:
Immediately before the press roll of a paper
machine such as a Fourdrinier paper machine, cylinder
paper machine or tanmo paper machine, the forgery
5 preventing members 2 are sprinkled over wet paper
obtained from the above-described paper stock.
Method C5:
A web obtained from the above-described paper
; stock is coated with a coating solution containing the
•
10 forgery preventing members 2 by size press coating by
using a paper machine such as a Fourdrinier paper
machine, cylinder paper machine or tanmo paper machine.
Method C6:
In the manufacture of combination paper performed
15 by using a cylinder paper machine having a multi-bath
! structure, a paper layer as an inner layer is formed
from the abovementioned paper stock, and a paper layer
as an outermost layer or surface layer is formed from a
paper stock containing the forgery preventing members
20 2.
Method C7:
At a position immediately before the cylinder of a
cylinder paper machine enters a paper stock and/or a
position immediately before the cylinder comes out from
<
25 the paper stock, a paper stock containing the forgery
preventing members 2 is discharged toward the cylinder
from a plurality of nozzles arranged in the widthwise
• 32
direction.
In these methods, it is also possible during
papermaking to coat the web with, e.g., starch,
polyvinyl alcohol, or various surface sizes by using a
5 size press apparatus or the like, in order to improve
the size degree or surface strength. In addition, the
surface smoothness is appropriately improved as needed
by performing a machine calendering process or supercalendering
process.
: 10 It is also possible to add, to the paper stock, a
well-known forgery preventing material such as fibers
or particles that emit fluorescence when irradiated
with ultraviolet rays, and a forgery preventing
taggant. Also, it is possible to properly mix forgery
15 preventing threads in the sheet, or form a watermark on
the sheet.
: When the forgery preventing members 2 have optical
characteristics such as optically coherence or metallic
luster, it is usually impossible to observe clear
20 optical characteristics, e.g., a bright interference
' color unless the forgery preventing members 2 are
distributed on or near the surface of the sheet 1. In
such a case, therefore, a method by which the forgery
preventing members 2 are distributed on or near the
25 surface of the sheet 1 is preferably used in
papermaking. As an example, it is preferable to use a
, cylinder paper machine including three or more baths,
-
; 33
and manufacture a combination sheet including a pair of
surface layers containing the forgery preventing
members 2, and an inner layer interposed between the
surface layers and containing no forgery preventing
5 members 2.
After papermaking, a resin coating layer can be
formed on the surface of the sheet 1. This makes it
possible to further increase the adhesion of the
forgery preventing members 2 to the sheet 1, and
i
10 increase the effect of preventing the removal of the
forgery preventing members 2 during printing. It is
•
also possible to improve the transfer foil aptitude,
: e.g., the adhesion strength of a foil. The resin is
' preferably transparent, and it is possible to use known
, 15 resins such as a polyester resin, a polyurethane resin,
an acrylic ester copolymer resin, a styrene-acrylate
ester copolymer resin, a vinyl acetate resin, a
polyacrylamide resin, a melamine resin, a urea resin,
•
polyvinyl alcohol and its derivatives, starch and its
20 derivatives, a cellulose derivative, and casein. The
coating amount of the resin is preferably 0.1 to 5 g/m^
on the dry mass basis.
As a coater for forming the resin coating layer,
it is possible to use a water-based or organic solvent-
: 25 based material coater such as a gravure coater, roll
coater, air knife coater or blade coater, or a gravure
press.
i
w
34
It is also possible to obtain forgery preventing
printed matter by performing processing such as pattern
printing, forgery preventing printing, transfer of,
e.g., a hologram having the forgery preventing effect,
5 or laser perforation, on the surface of the forgery
preventing sheet 1 manufactured as described above.
Practical examples of the present invention will
be described below.

10 A roll of an 18-jam thick multilayered light
interference film (trade name: "Aurora Film" available
from Engelhard) made of a multilayered film including a
polyethyleneterephthalate resin layer and acrylic resin
layer was prepared as a sheet substrate. This film
! 15 looks red when reflected light is observed, and looks
] cyan, a complementary color of red, when transmitted
light is observed. Since the film has such property,
forgery preventing members manufactured from the film
have the same property. A forgery obtained by, e.g.,
i 20 color-copying such forgery preventing members cannot
reproduce the colors of the authentic product.
Accordingly, the abovementioned forgery preventing
members provide a good forgery preventing effect.
; Then, the wettability index of the surface of the
25 abovementioned film was increased by carrying out a
corona discharge processing on the film. Subsequently,
the surface was coated with a coating solution
i
containing an adhesive. The adhesive used can adhere
to papermaking fibers forming paper by softening or
melting in the drying zone of a paper machine. More
specifically, a polyester-based, heat-sensitive
5 adhesive manufactured under the trade name: "Vylon
2310" by T0Y0B0 and having a glass transition
temperature of 26°C was used as the adhesive. The
coating solution was prepared by mixing 150 parts by
mass of the adhesive, a proper amount of an isocyanate-
10 based hardener, 300 parts by mass of toluene, and 200
parts by mass of methyl ethyl ketone. The film surface
was coated with 3 g/m^ of the coating solution on the
: dry mass basis by using a gravure coater/laminator.
Subsequently, in this gravure coater/laminator,
15 water-soluble paper was laminated on the film on one
surface of which the adhesive layer was formed as
described above. More specifically, water-soluble
; paper manufactured under the trade name: "30CD-2" by
NIPPON PAPER PAPYLIA and having a basis weight of
! 20 30 g/m^ was used. This water-soluble paper was fed
* from a roll and supplied together with the
aforementioned film to a combiner roll for lamination.
Then, these materials were bonded by pressure at a
'. heating temperature of 80°C, and taken up to a roll.
25 The film laminated with the water-soluble paper as
described above was fed from the roll, and an adhesive
layer was formed by the same method as above on the
5
•^
. W 36
surface opposite to the surface on which the watersoluble
paper was laminated. Subsequently, this film
and water-soluble paper were laminated by the same
method as above, and taken up to a roll.
5 Thus, roll paper having a multilayered structure j
of "water-soluble paper/adhesive layer/multilayered
light interference film/adhesive layer/water-soluble
paper" was obtained.
Then, this roll paper was cut into sheets having a
10 predetermined size by using a sheet cutter, and these
sheets were piled up. Subsequently, the piled sheets
were cut into a width of 1.0 mm by using a cutter
called a guillotine including a vertically movable
: blade. A bundle thus obtained was further cut into a
15 length of 4 mm by using the same guillotine. As
described above, a large amount of 1.0-mm wide x 4-mm
long flaky forgery preventing members were
: manufactured.
Note that the adhesive layers of some forgery
20 preventing members weakly adhered to the water-soluble
• paper of some forgery preventing members at the
positions of their sections due to the pressure applied
! by the edge of the blade during cutting and the
frictional heat generated during cutting. When these
25 forgery preventing members were placed in water,
i however, the water-soluble paper dissolved in the
water, and the forgery preventing members dispersed.
. 37
Then, a mixture containing 30 parts by mass of
NBKP (Northern Bleached Kraft Pulp and 70 parts by mass
of LBKP (Laubholz Bleached Kraft Pulp) was beaten into
360 mL C.S.F. by using a refiner. A paper stock was
5 prepared by adding, to this mixture, 15 parts by mass
of kaolin, 0.5 parts by mass of a paper-strengthening
agent, 1.0 part by mass of a sizing agent, and an
appropriate amount of aluminum sulfate. As the paperstrengthening
agent, "Polystron 117" (trade name)
10 manufactured by ARAKAWA CHEMICAL INDUSTRIES was used.
As the sizing agent, "Sizepine E" (trade name)
manufactured by ARAKAWA CHEMICAL INDUSTRIES was used.
This paper stock will be called a "first paper stock"
hereinafter.
15 Subsequently, the abovementioned forgery
preventing members were added to the first paper stock.
The addition amount of the forgery preventing members
was 1.5 mass% with respect to the dry mass of the
sheet. A paper stock thus obtained will be called a
20 "second paper stock" hereinafter.
'•• Then, four-layered combination paper was
i
manufactured by using the first and second paper
stocks. More specifically, a four-bath cylinder paper
machine including first to fourth baths was used. The
: 25 second paper stock was supplied to the first and fourth
baths. The first paper stock was supplied to the
second and third baths. A web including four paper
. W 38
layers sequentially formed by the first to fourth baths
was subjected to drying in a first dryer part, size
press, and drying in a second dryer zone. In the size
press, the web was coated with a 5% aqueous solution of
5 polyvinyl alcohol. As the polyvinyl alcohol, "KURARAY |
PVA117" (trade name) manufactured by KURARAY was used.
In drying in the first and second dryer parts, a multicylinder
dryer was used.
As described above, the four-layered combination
10 paper which had a basis weight of 100 g/m^ and in which
each paper layer had a basis weight of 25 g/m^ was
obtained. In this sheet, the inner layers contained no
forgery preventing members, and only the surface layers
: contained the forgery preventing members.
15 When this sheet was copied by a color copying
machine, the copy did not exhibit the interference
colors of the forgery preventing members. Accordingly,
it was possible to clearly distinguish between them
(the sheet and copy) by visual judgment.
20 Then, the offset printability was tested by using
i this sheet. Consequently, a phenomenon in which the
' forgery preventing members removed to a blanket did not
occur.

i
: 25 Forgery preventing members were manufactured
following the same procedures as in Example 1 except
that no adhesive layers were formed. Then, a sheet was
c
• 39
manufactured following the same procedures as in
Example 1 except that these forgery preventing members
were used.
The offset printability was tested in the same
5 manner as in Example 1 by using this sheet.
Consequently, a phenomenon in which the forgery
preventing members removed to a blanket occurred.
The forgery preventing members and forgery
preventing sheet explained above are preferably usable
10 in applications such as banknote paper, gift
certificate paper, stock certificate paper, credit
paper, check paper, passport paper, paper for various
tickets, passenger ticket paper, and brand protection
label paper. The forgery preventing sheet can be used
\ 15 singly, and can also be used as it is supported by
' another material. In the latter case, the forgery
preventing sheet can be used in the form of a card
obtained by adhering the sheet to another material,
; e.g., paper.
20 Additional advantages and modifications will
readily occur to those skilled in the art. Therefore,
the invention in its broader aspects is not limited to
the specific details and representative embodiments
shown and described herein. Accordingly, various
25 modifications may be made without departing from the
spirit or scope of the general inventive concept as
defined by the appended claims and their equivalents.

40
We Claim:
1. A method of manufacturing a forgery preventing
member, comprising:
forming a first adhesive layer capable of adhering
5 to paper, on one surface of a sheet substrate which
provides a forgery preventing effect;
forming a second adhesive layer capable of
adhering to the paper, on the other surface of the
sheet substrate;
10 superimposing the sheet substrate and a first
water-soluble sheet or unsized paper, with the first
adhesive layer being sandwiched therebetween;
superimposing the sheet substrate and a second
water-soluble sheet or unsized paper, with the second
15 adhesive layer being sandwiched therebetween; and
cutting or punching the sheet substrate on which
the first adhesive layer and the second adhesive layer
are formed, with the sheet substrate being sandwiched
between the first water-soluble sheet or unsized paper
20 and the second water-soluble sheet or unsized paper, to
produce a fibrous or flaky forgery preventing member.
2. The method according to claim 1, wherexn the
sheet substrate has optical coherence.
3. The method according to claim 1 or 2, further
25 comprising:
adhering the first water-soluble sheet or unsized
paper to the sheet substrate by the first adhesive
0
• 41
layer before the cutting or punching; and
adhering the second water-soluble sheet or unsized
paper to the sheet substrate by the second adhesive
layer before the cutting or punching.
5 4. A method of manufacturing a forgery preventing
sheet, comprising:
forming a first adhesive layer capable of adhering
to paper, on one surface of a sheet substrate which
provides a forgery preventing effect; I
10 forming a second adhesive layer capable of adhering to the paper, on the other surface of the
sheet substrate;
superimposing the sheet substrate and a first
water-soluble sheet or unsized paper, with the first
15 adhesive layer being sandwiched therebetween;
superimposing the sheet substrate and a second
water-soluble sheet or unsized paper, with the second
adhesive layer being sandwiched therebetween;
cutting or punching the sheet substrate on which
20 the first adhesive layer and the second adhesive layer
are formed, with the sheet substrate being sandwiched
between the first water-soluble sheet or unsized paper
and the second water-soluble sheet or unsized paper, to
produce a fibrous or flaky forgery preventing member;
25 and
carrying out papermaking by using the forgery
preventing member, a papermaking fiber and a
papermaking subsidiary material, as raw materials.
5. The method according to claim 4, further
comprising:
adhering the first water-soluble sheet or unsized
5 paper to the sheet substrate by the first adhesive
layer before the cutting or punching; and
adhering the second water-soluble sheet or unsized
paper to the sheet substrate by the second adhesive
layer before the cutting or punching.
10 6. The method according to claim 4 or 5, wherein
the papermaking comprises producing a multilayered
structure including a pair of surface layers formed by
using the forgery preventing member, and an inner layer
interposed between the surface layers.
15 7. A fibrous or flaky forgery preventing member
comprising:
a substrate which provides a forgery preventing
effect;
a pair of adhesive layers disposed on both
20 surfaces of the substrate; and
a pair of water-soluble sheets or unsized papers
opposing each other with the substrate and the pair of
adhesive layers being sandwiched therebetween, and
joined to the adhesive layers, respectively.
25 8. A forgery preventing sheet comprising one or
more first layers each obtained from a paper stock
containing a papermaking fiber, a papermaking
43
subsidiary material, water and a fibrous or flaky
forgery preventing member, the forgery preventing
member including a substrate which provides a forgery
preventing effect, a pair of adhesive layers disposed
5 on both surfaces of the substrate, and a pair of watersoluble
sheets or unsized papers opposing each other
with the substrate and the pair of adhesive layers
being sandwiched therebetween, and joined to the
adhesive layers, respectively.
10 9. The forgery preventing sheet according to
claim 8, further comprising one or more second layers
interposed between the pair of first layers.
10. The forgery preventing sheet according to
•
claim 8 or 9, wherein the substrate has optical
15 coherence.