12S0459P4 - 1 -
D E S C R I P T I O N
COLORING FORGERY PREVENTION STRUCTURE AND COLORING FORGERY
PREVENTION MEDIUM
5
Technical Field
The present invention relates to a colored forgery
prevention structure and a colored forgery prevention
medium which exhibit a high forgery prevention effect and a
10 high alteration prevention effect.
Background Art
A forgery prevention structure is used to prevent
forgery of valuable papers, brand-name products,
certificates, and personal authentication media, and
15 functions to prove articles to be genuine.
In recent years, a forgery prevention structure using
an optical element such as a diffraction grating or a
hologram is applied to various articles because a special
optical effect thereof can be distinguished at a glance. A
2 0 lot of optical elements include a micro structure, such as
a diffraction grating, a hologram, or a lens array. These
micro structures are difficult to analyze. In addition, an
optical element including a micro structure is manufactured
using an electron-beam lithography apparatus, and can
25 therefore exhibit an excellent forgery prevention effect.
However, a hologram which has a silver metallic luster
has been widely marketed for a packaging purpose and an
amusement purpose. Therefore, the security thereof is
deteriorating. To respond to these circumstances, for
example. Patent Literature 1 proposes a hologram which
partially comprises a reflection layer, as a hologram which
5 provides a forgery prevention effect. The hologram which
includes a reflection layer having a micro pattern is
considered difficult to counterfeit.
On the other hand, a proposal has been made for a
hologram which has a metallic luster in a vivid color tone
10 other than silver. For example. Patent Literature 1
proposes a hologram structure with which a desired color
tone is obtained and which is excellent in design and/or
security. Color tones can be more or less chosen by using
this method. However, the reflectance of a high-intensity
15 ink layer is lower than that of a vapor-deposited film of
aluminum and has a tendency to scatter. Therefore, there
is a defect that a colored metallic luster, e.g., a metal
luster of a vivid color tone such as gold or copper is not
obtained.
2 0 Further, a partially colored reflection layer is
difficult to provide on a hologram through the method
according to Patent Literature 1. This defect is caused by
the difficulty in oveirprinting a reflection layer of a
high-luminance ink in an identical pattern over a colored
25 layer with high positional accuracy, after pattern-printing
of the colored layer.
Another method has been considered in which a vivid
color reflection layer is formed of gold or copper by a
vacuum deposition method or a sputtering method, and
patterned by etching. However, forming a precious-metal
reflection layer by etching requires high costs and
5 exhibits low productivity.
Citation List
Patent Literature
Patent Literature 1: Jpn. Pat. Appln. KOKAI
Publication No. 2008-162260
10 Summary of Invention
An object of the invention is to provide a forgery
prevention structure which is excellent in design and/or
security.
According to the first aspect of the invention, there
15 is provided a forgery prevention structure configured by
layering a first reflection layer, a functional thin film
layer, a second reflection layer, and a protection layer,
in this order, characterized in that:
the relief forming layer has, on one side, a relief
20 structure which has an effect of diffracting, scattering,
absorbing, and polarizing/separating at least a part of a
wave-length range of visible light;
the first reflection layer and the functional thin
film layer are provided along a whole surface of an uneven
25 area of the relief structure;
the second reflection layer is provided in an
arbitrary area which covers a part of an uneven area of the
relief structure;
the protection layer is provided so as to cover only
an area of the second reflection layer; and
three layers of the first reflection layer, the
5 functional thin film layer, and the second reflection layer
cause at least a partial range of visible light to
interfere.
According to the second aspect of the invention, there
is provided a forgery prevention structure configured by
10 layering a first reflection layer, a functional thin film
layer, a second reflection layer, and a protection layer,
in this order, characterized in that:
the relief forming layer has, on one side, a relief
structure including a first relief and a second relief
15 which performs an effect of diffracting, scattering,
absorbing, and polarizing/separating a wavelength range of
at least a part of visible light;
the surface of the first relief has a smaller uneven
surface area in comparison with the surface of the second
20 relief;
the first reflection layer and the above functional
thin film layer are provided along a whole surface of an
uneven area of the relief structure; and
the second reflection layer and the protection layer
25 are provided so as to cover only a surface of the
functional thin film layer of the first relief; and
three layers of the first reflection layer, the
functional thin film layer, and the second reflection layer
cause at least a partial range of visible light to
interfere.
According to the third aspect of the invention, there
5 is provided the forgery prevention structure according to
claim 1 or 2, characterized in that the first reflection
layer includes at least one selected from a group of
tantalum oxide, niobium oxide, titanium oxide, indium oxide
tin, zirconium oxide, cerium oxide, and hafnium oxide, in
10 the first or second aspect.
According to the fourth aspect of the invention, there
is provided a forgery prevention structure characterized by
forming the first reflection layer of a high-intensity
transparent reflection paint which is made of high
15 refraction particles, in any one of the first to third
aspects.
According to the fifth aspect of the invention, there
is provided a forgery prevention structure characterized in
that the relief structure includes at least one of a
20 diffraction structure, a hologram, a convergence lens array,
a diffusion lens array, and a scattering structure at least
partially on an identical plane, in any one of the first to
fourth aspects.
According to the sixth aspect of the invention, there
25 is provided a forgery prevention structure layered at least
on the substrate, and the forgery prevention structure is
characterized by being a sticker configuration which layers
a relief forming layer, a first reflection layer, a
functional thin film layer, a second reflection layer, a
protection layer, and an adhesion layer, in this order on
the substrate, in any one of the first to five aspects.
5 According to the seventh aspect of the invention,
there is provided a forgery prevention structure layered at
least on the substrate, and the prevention structure is
characterized by being a sticker transfer foil
configuration which layers a relief forming layer, a first
10 reflection layer, a functional thin film layer, a second
reflection layer, a protection layer, and an adhesion layer,
in this order on the substrate, and which can be separated
from the substrate, in any one of the first to five aspects.
In the foregoing seventh and eighth aspects, a
15 separation protection layer may be provided between the
substrate and the relief forming layer, if needed. The
separation protection layer is to achieve smooth and stable
separation from the substrate, and a material having an
excellent mold-release characteristic relative to the
20 substrate may be selected.
According to the eighth aspect of the invention, there
is provided a forgery prevention medium to which the
forgery prevention structure in any one of the first to
seventh aspects is adhered.
25 According to the invention, a forgery prevention
structure can be provided which is excellent in design
and/or security.
- 7 -
Brief Description of Drawings
FIG. 1 is a sectional view showing a forgery
prevention structure according to the first embodiment;
FIG. 2A is a sectional view showing a process of
5 manufacturing a forgery prevention structure according to
the first embodiment;
FIG. 2B is a sectional view showing a process of
manufacturing a forgery prevention structure according to
the first embodiment;
10 FIG. 2C is a sectional view showing a process of
manufacturing a forgery prevention structure according to
the first embodiment;
FIG. 3 is a sectional view showing another example of
the forgery prevention structure according to the first
15 embodiment;
FIG. 4 is a sectional view showing still another
example of the forgery prevention structure according to
the first embodiment;
FIG. 5 is a sectional view showing a forgery
20 prevention structure according to the second embodiment;
FIG. 6 is a sectional view showing a process of
manufacturing a forgery prevention structure according to
the second embodiment;
FIG. 7A is a sectional view showing a process of
25 manufacturing a forgery prevention structure according to
Comparative Example 1; and
FIG. 7B is a sectional view showing a process of
manufacturing the forgery prevention structure according to
the Comparative Example 1.
Description of Embodiments
First Embodiment
5 Hereinafter, a forgery prevention structure according
to the first embodiment of the invention will be described
with reference to the drawings. FIG. 1 is a sectional view
showing the forgery prevention structure according to the
first embodiment.
10 The forgery prevention structure 1 comprises a relief
forming layer 2, a first reflection layer 3, a functional
thin film layer 4, a second reflection layer 5, and a
protection layer 6 which are layered in this order. The
relief forming layer 2 has, on one side, a relief structure
15 7 having a micro uneven pattern. The relief structure 7
has an effect of diffracting, scattering, absorbing, and
polarizing/separating at least a part of a wave-length
range of visible light. The first reflection layer 3 and
the functional thin film layer 4 are provided along a whole
20 surface of an uneven area of the relief structure 7. In an
arbitrary area (first area) 8 of the relief structure 7,
the second reflection layer 5 is provided covering a part
of an uneven area of the relief structure 7. The
protection layer 6 is provided so as to cover only the
25 second reflection layer 5.
In the first area 8, the first reflection layer 3, the
functional thin film layer 4, the second reflection layer 5,
and the protection layer 6 are layered in this order, and a
colored reflection layer is obtained which makes three
layers of the first reflection layer 3, the functional thin
film layer 4, and the second reflection layer 5 cause
5 interference in at least a partial range of visible light.
The three layers allow a relief structure to be designed to
be capable of forming a reflection layer which causes a
color tone to change in accordance with view angles and has
a vivid color reflection layer.
10 The colored reflection layer exists only in the part
of the first area 8, and only the patterned second
reflection layer 5 is colored. In the first area 8, the
patterned second reflection layer 5 is colored in itself.
As a result, the second reflection layer 5 is a colored
15 pattern in itself, and therefore, the coloring ink is
patterned and printed. Accordingly, it is possible to
avoid positional misalignment which may be caused between a
colored pattern and a reflection layer 5 by employing a
conventional method of forming the reflection layer to be
20 aligned with the colored pattern.
The second area 9 includes neither the second
reflection layer 5 nor the protection layer 6 but is formed
of the first reflection layer 3 and the functional thin
film layer 4. Therefore, also in the second area 9, a
25 colorless optical effect owing to a relief structure can be
obtained.
A typical theory concerning a three-layer interference
- 10 -
film is described in Jpn. Pat. Appln. KOKAI Publication No.
2010-175812. This patent publication describes a multilayer
interference film including three or more layers. In
contrast, the forgery prevention structure according to the
5 first embodiment is limited to a three-layer interference
film. That is, there is an advantage that reflection of
the interference color can be enhanced as the total number
of reflection layers increases. However, in this case,
there is a problem that coloring occurs because at least
10 two reflection layers exist also in the second area where
the reflection layer of the top layer does not exist. That
is, in a multi-layer film of five or more layers, similar
interference colors appear in a part (first area) including
a high diffraction reflection layer in an uppermost layer
15 and a part (second area) not including the same. Therefore,
if a multi-layer film of five or more layers is applied to
the forgery prevention structure according to the first
embodiment, the first area 8 and the second area 9 tend to
have similar color tones.
20 In the forgery prevention structure according to the
first embodiment, the part (first area 8) including the
second reflection layer 5 is colored by interference while
the part (second area 9) not including the second
reflection layer 5 causes no interference and becomes
25 colorless. Accordingly, sufficient difference in color
tone can appear between the first area 8 and the second
area 9.
- 11 -
Therefore, the forgery prevention structure according
to the first embodiment can exhibit a high forgery
prevention effect by the colored reflection relief
structure in the first area 8 and by the colorless
5 reflection relief in the second area 9.
Next, a method of manufacturing a forgery prevention
structure according to the first embodiment will be
described with reference to FIG. 2A to FIG. 2C.
First Process
10 As shown in FIG. 2A, a relief forming layer 2 is
formed on the whole surface of a substrate 11. The relief
forming layer 2 can be formed by coating, e.g., by wet
coating on the substrate 11. In addition, the substrate
itself may serve as a relief forming layer.
15 Subsequently, an original relief plate made of metal
or resin and having an uneven shape is prepared. The
uneven shape of the original relief plate is transferred to
a surface of the relief forming layer 2, to form a relief
structure 7 having an uneven surface in the relief forming
2 0 layer 2 (see the same FIG. 2A).
The method of transfer may be a well-known method such
as a press method, a casting method, or a photopolymer
method, or a hybrid method which combines any of these
methods.
25 Second Process
As shown in FIG. 2B, a first reflection layer 3, a
functional thin film layer 4, and a thin film layer 12 for
- 12 -
a second reflection layer are formed in this order on a
surface of the relief structure 7.
The first reflection layer 3 and the functional thin
film layer 4 can be formed by well-known wet coating or dry
5 coating. The thin film layer 12 for the second reflection
layer can be formed by dry coating, preferably.
Third Process
A protection layer 6 which functions as an etching
mask is formed on the thin film layer 12 for the second
10 reflection layer. Subsequently, the thin film layer 12 for
the second reflection layers is selectively removed by
etching with an etching treatment agent, with the
protection layer 6 used as a mask, to form the second
reflection layer 5. That is, the thin film layer 12 for
15 the second reflection layer is left to remain in an area
under an area (first area 8) of the protection layer 6, as
the second reflection film 5. The thin film layer 12 for
the second reflection layer is removed from under the other
areas (second area 9). Here, the first reflection layer 3
20 need not be removed by etching.
Specifically, the thin film layer 12 for the second
reflection layer is formed on the whole surface of the
functional thin film layer 4, and thereafter, a protection
layer 6 is formed on the thin film layer 12 for the second
25 reflection layer by a well-known wet printing method.
Thereafter, the thin film layer 12 for the second
reflection layer is selectively subjected to etching with
- 13 -
the protection layer 6 used as an etching mask, to form a
patterned second reflection layer 5.
The forgery prevention structure according to the
first embodiment is manufactured through the first to third
5 processes above, but is not limited thereto.
Next, more detailed descriptions will be made of
materials, required characteristics, and specific
manufacturing methods of layers forming the forgery
prevention structure according to the first embodiment.
10 Substrate
The substrate used in the manufacturing method
described above is preferably a film substrate. As the
film substrate, a material which is less deformed or
degraded by heat, pressure, and electromagnetic waves which
15 are applied during formation of a micro uneven pattern
(relief structure) is used. A film made of plastic, such
as PET (polyethylene terephthalate), PEN (polyethylene
naphthalate), or PP (polypropylene), may be used for the
film substrate. Depending on necessity, a paper made of
2 0 multiple plastic layers or a paper impregnated with resin
may be used as a substrate.
Relief Forming Layer
On a surface of the relief forming layer, a relief
structure which has a micro uneven pattern is preferably
25 copied sequentially a great number of times. As a typical
method, the "press method" described in Patent Publication
No. 4194073, the "casting method" described in Utility
- 14 -
Model Registration No. 2524092, or the "photopolymer
method" described in Patent Publication No. 4088884 can be
employed.
Particularly in the "photopolymer method" (2P method:
5 a photosensitive resin method), radiation-cured resin is
poured between a relief die (die for copying a micro uneven
pattern) and a flat substrate (plastic film), and hardened
by radiation. Thereafter, the hardened film is separated
together with the substrate from the die for duplication.
10 The relief structure which has a high-definition micro
uneven pattern can be obtained by this method. The relief
structure obtained by this method provides a micro uneven
pattern with a higher forming accuracy than the "pressing
method" and the "cast method" which use thermoplastic resin,
15 and is excellent in heat resistance or chemical resistance.
Further, as a method of preparing a relief forming
layer having a novel relief structure, there is a method of
molding with use of an optical curing resin which is solid
or highly viscous at a normal temperature or a method of
20 adding a mold release material.
Used as a material for the relief forming layer can be,
for example: thermoplastic resin, such as acrylic-based
resin, epoxy-based resin, cellulose-based resin, or vinylbased
resin; urethane resin of acrylic polyol or polyester
25 polyol with a reactive hydroxyl group, added and bridged
with polyisocyanate as a crosslinking agent; or
theremosetting resin, such as a melamine-based resin, epoxy
- 15 -
resin, or phenol-based resin or a compound thereof. Any
other material than described can be used as long as a
micro uneven pattern can be formed of the material.
Used as a material of the relief forming layer
5 applicable to the photopolymer method described above can
be, for example, a monomer, an oligomer, or a polymer,
which has an ethylene unsaturated bond or an ethylene
unsaturated group. Used as the monomer can be, for example,
1,6-hexane diol, neopentylglycol diacrylate,
10 trimethylolpropane triacrylate, pentaerythritol triacrylate,
pentaerythritol tetraacrylate, dipentaerythritol
pentaacrylate, and dipentaerythritol hexaacrylate. The
oligomer may be, for example, epoxy acrylate, urethane
acrylate, or polyester acrylate. As the polymer, for
15 example, urethane denaturation acrylic resin and epoxy
denaturation acrylic resin can be used.
As a material of the relief forming layer using
optical cationic polymerization can be used, for example, a
monomer containing an epoxy group, an oligomer, a polymer,
20 a compound containing an oxetane skeleton, or vinyl ethers
can be used. When the ionizing radiation curing resin
described above is hardened with light such as ultraviolet
rays, a photo polymerization initiator can be added.
Depending on the types of resin, an optical radical
25 polymerization initiator, an optical cationic
polymerization initiator, or a combination thereof (hybrid
type) can be selected.
- 16 -
In addition, it is possible to use a mixture of a
monomer, an oligomer, and a polymer, each of which has an
ethylene unsaturated bond or an ethylene unsaturated group,
to provide the mixture of these components with a reactive
5 group in advance and to crosslink each other by an
isocyanate compound, a silane coupling agent, an organic
titanate crosslinker, an organic zirconium crosslinker, or
an organic aluminate, and to provide the bridged components
with a reactive group in advance and to bridge still
10 another resin skeleton by an isocyanate compound, a silane
coupling agent, an organic titanate crosslinker, an organic
zirconium crosslinker, or organic aluminate. According to
the method as described above, a polymer can be obtained
which exists in solid form at a normal temperature, has
15 good fabricability because of its lower tact, and leaves
little dirt on an original plate, with use of polymer
having an ethylene unsaturated bond or an ethylene
unsaturated group.
Used as the optical radical polymerization initiator
2 0 described above can be, for example: benzoin, or benzoin
methyl ether, a benzoin-based compound, such as benzoin
ethyl ether or anthraquinone, an anthraquinone-based
compound, such as methyl anthraquinone or acetophenone; a
phenyl-ketone-based compound, such as diethoxy acetophenone,
25 benzophenone, hydroxy acetophenone, 1-hydroxy cyclohexyl
phenyl ketone, alpha-amino acetophenone, 2-methyl-l-(4-
methylthiophenyl)-2-morpholino-propane-l-ON, benzyl methyl
- 17 -
ketal, thioxanthone, acyl phosphine oxide, or Michler's
ketone.
Used as the optical cationic polymerization initiator
in the case of using the compound described above capable
5 of optical cationic polymerization can be, for example, an
aromatic diazonium salt, an aromatic iodonium salt, an
aromatic sulfonium salt, an aromatic phosphonium salt, or a
mixed ligand metal salt. In the case of a so-called hybrid
material which uses both optical radical polymerization and
10 optical cationic polymerization, polymerization initiators
of both polymerizations can be used in a mixture. In
addition, it is possible to use an aromatic iodonium salt
or an aromatic sulfonium salt, which can start both
polymerizations with one type of initiator.
15 In a resin composite including a radiation-cured resin
and a photo polymerization initiator, a mixing rate of the
photo polymerization initiator may be appropriately
selected although 0.1 to 15 mass% is used in general. The
resin composite may be used together with a sensitizing dye
20 in combination with a photo polymerization initiator.
According to necessity, the resin composite may also
include a dye, a pigment, various additives (a
polymerization inhibitor, a leveling agent, an antifoaming
agent, an anti-sagging agent, an adhesion improvement agent,
25 a coated surface modifier, a plasticizer, a compound
containing nitrogen), and a crosslinking agent (for example,
epoxy resin). In addition, a non-reactive resin (including
- 18 -
thermoplastic resin or thermosetting resin described above)
may be added to improve fabricability.
In the manufacturing method described above, a
material for a relief forming layer may be selected, in
5 consideration of fluidity to some extent which allows
molding, and considering that thermostability and chemical
resistance desired by a coated film can be obtained after
molding.
In a process of forming a relief forming layer, a
10 coating method may be used. In that case, the material for
a relief forming layer may be coated on the substrate. In
particular, wet coating allows formation at low costs. A
material diluted with a solvent may be coated and dried in
the course of forming a relief forming layer, to adjust
15 thickness.
The thickness of the relief forming layer is
preferably set within, for example, a range of 0.1 to 10 \im.
Though depending on the method of manufacturing the relief
forming layer as described above, too great a thickness
2 0 causes protrusions and wrinkles of resin due to the
pressure during processing for transferring a relief
structure. On the other hand, if too thin, fluidity at the
time of transferring the relief structure may be
insufficient to achieve molding. Though transfer
25 properties of the micro uneven pattern change depending on
the shape of the pattern, the thickness of the relief
forming layer is preferably 1 to 10 times, or more
- 19 -
preferably 3 to 5 times a desired depth of unevenness.
After the relief forming layer is brought into contact
with an original relief plate having a desired relief
structure, the shape of the original relief plate is
5 transferred to one side of the relief forming layer by
using heat, pressure, or microwaves. The relief structure
may be formed not only on one side but also two sides, i.e.,
front and back surfaces of the relief forming layer.
A well-known method may be used as the method of
10 manufacturing the original relief plate to be used. A
rolled original plate allows continuous molding.
First Reflection Layer
The first reflection layer functions to reflect
electromagnetic waves. In the case of reflecting light
15 which has penetrated the relief forming layer and the
relief structure with a micro uneven pattern, a higher
refractive-index material than the refractive index of the
substrate or the relief forming layer is used. In this
case, the difference in refractive index between the first
20 reflection layer and the relief forming layer is preferably
0.2 or more. By setting the difference in refractive index
to be 0.2 or more, refraction and reflection occur at the
interface between the relief forming layer and the first
reflection layer. In addition, the first reflection layer
25 which covers the relief structure may emphasize an optical
effect created by the micro uneven structure.
Metal materials, such as Al, Sn, Cr, Ni, Cu, Au, and
- 20 -
Ag, can be used singularly or in the form of a compound
thereof, as a material for the first reflection layer.
The first reflection layer preferably has a
transmittance of 40% or less. An interference color is
5 generated by the three-layer interference film made of the
first reflection layer, the functional thin film, and the
second reflection layer. Therefore, the first reflection
layer preferably has transparency and also preferably has a
diffractive difference of 0.2 or more relative to the
10 relief forming layer and the functional thin film layer, to
cause reflection at both interfaces.
The first reflection layer which has such transparency
can be realized by forming a thin film made of one or a
compound of the metal materials described above.
15 Examples of materials other than described above, each
of which can be used for the transparent first reflection
layer, are cited below. Numerals in parentheses each
indicate a refractive index n. Ceramics which can be used
are, for example: Sb203 (3.0), Fe203 (2.7), Ti02 (2.6), CdS
2 0 (2.6), Ce02 (2.3), ZnS (2.3), PbCl2 (2.3), CdO (2.2), Sb203
(5.0), WO3 (5.0), SiO (5.0), Si203 (2.5), In203 (2.0), PbO
(2.6), Ta203 (2.4), ZnO (2.1), Zr02 (5.0), MgO (1.0), Si02
(1.45), Si202 (10), MgF2 (4.0), CeF3 (1.0), CaF2 (1.3-1.4),
AIF3 (1.0), AI2O3 (1.0), and GaO (2.0). Organic polymers
25 which can be used are, for example, polyethylene (1.51),
polypropylene (1.49), polytetrafluoroethylene (1.35),
polymethyl methacrylate (1.49), and polystyrene (1.60).
- 21 -
The first reflection layer needs resistance against an
etching treatment agent used to perform a pattern
processing on the second reflection layer in the
manufacturing method described above. For example, the
5 reflectance of the first reflection layer in a second area
needs not to change due to dissolution, corrosion,
deterioration, or separation but needs to be stable.
Therefore, the first reflection layer may be appropriately
selected from the materials described above. Depending on
10 the case, a plurality of materials may be used.
Resistance against the etching treatment agent of the
first reflection layer in the second area may be
strengthened by the functional thin film layer arranged so
as to cover the first reflection layer. That is, even if
15 the first reflection layer has low resistance against the
etching treatment agent, the reflection function of the
first reflection layer in the second area can be prevented
from deterioration by protecting the first reflection layer
from the etching treatment agent by multi-layering with the
2 0 functional thin film layer.
Since the first reflection layer is formed as a thin
film with a uniform thickness on the micro uneven surface
of the relief forming layer in the manufacturing method
described above, a dry coating method, such as a vacuum
25 deposition method, a sputtering method, or a CVD method, is
preferably employed.
For the first reflection layer, it is possible to use
- 22 -
a high-luminance optical reflection ink, an organic polymer,
or fine particles of the organic polymer, which is obtained
by dispersing micro powder, sol, or metal nano particles of
the metals described above, ceramics, or an organic polymer.
5 This first reflection layer can be formed by a well-known
printing method, such as a gravure printing method, a flexo
printing method, or a screen printing method. To provide
the first reflection layer by such a printing method as
described, adjustment may be performed so as to set the
10 dried film thickness to 0.001 to 10 jim or so.
Functional Thin Film Layer
The functional thin film layer comprises a function to
allow light, which has penetrated the substrate, the relief
forming layer having a micro uneven pattern, and the first
15 reflection layer, to further penetrate. Further, the
functional thin film is a middle layer in the three-layer
interference film since an interference color is caused by
the three-layer interference film made of the first
reflection layer, the functional thin film layer, and the
2 0 second reflection layer. In general, the three-layer
interference film is configured by a layered structure made
of a high-refraction layer, a low-refraction layer, and a
high-refraction layer. Therefore, the functional thin film
as the middle layer preferably has a refractive index which
25 is lower by 0.2 or more than refractive indices of the
first and second reflection layers. By setting the
difference in refractive index to be 0.2 or more.
- 23 -
refraction and reflection can be caused at the interface
between the relief forming layer and the first reflection
layer.
In the second area, two layers of the first reflection
5 layer and the functional thin film are layered. Therefore,
an interference color is not obtained.
The functional thin film layer is the middle layer in
the three-layer interference film made of the first
reflection layer, the functional thin film layer, and the
10 second reflection layer, and is therefore preferably a lowrefraction
film with a high transparency. Specifically,
the functional thin film layer has a refractive index equal
to or lower than the first reflection layer, and can cause
reflection on both interfaces.
15 Examples of materials which can be used for the
transparent functional thin film layer are cited below.
Numerals in parentheses each indicate a refraction index n.
Ceramics which can be used are, for example: Sb203 (3.0),
Fe203 (2.7), Ti02 (2.6), CdS (2.6), Ce02 (2.3), ZnS (2.3),
20 PbCl2 (2.3), CdO (2.2), Sb203 (5.0), WO3 (5.0), SiO (5.0),
Si203 (2.5), In203 (2.0), PbO (2.6), Ta203 (2.4), ZnO (2.1),
Zr02 (5.0), MgO (1.0), Si02 (1.45), Si202 (10), MgF2 (4.0),
CeF3 (1.0), CaF2 (1.3-1.4), AIF3 (1.0), AI2O3 (1.0), and
Ga02 (2.0) . Organic polymers which can be used are, for
25 example, polyethylene (1.51), polypropylene (1.49),
polytetrafluoroethylene (1.35), polymethyl methacrylate
(1.49), and polystyrene (1.60).
- 24 -
The functional thin film layer is the middle layer of
the three-layer interference film, and functions as a layer
for adjusting an optical path difference, which controls an
interference color. Therefore, the functional thin film
5 can be formed to be thin with a uniform thickness along the
micro uneven surface of the relief forming layer.
Therefore, a gaseous phase method (dry coating method),
such as a vacuiim deposition method, a sputtering method, or
a CVD method, is preferably employed to form the functional
10 thin film.
Second Reflection Layer
The second reflection layer is provided along the
relief structure, and reflects light which has penetrated
the relief forming layer, the first reflection layer, and
15 the functional thin film layer. For the second reflection
layer, a material having a higher refractive index than
that of the functional thin film is used. In this case,
the difference in refractive index between both layers is
preferably 0.2 or more. By setting the difference in
20 refractive index to be 0.2 or more, refraction and
reflection can be caused at the interface between the
functional thin film and the second reflection layer.
For example, metal materials, such as Al, Sn, Cr, Ni,
Cu, Au, and Ag, can be used in sole or in form of a
2 5 compound thereof, as a material for the second reflection
layer.
Examples of other materials than the metals and
- 25 -
chemical compounds described above, which can be used for
the transparent second reflection layer, are cited below.
Numerals in parentheses each indicate a refraction index n.
Ceramics which can be used are, for example: Sb203 (3.0),
5 Fe203 (2.7), Ti02 (2.6), CdS (2.6), Ce02 (2.3), ZnS (2.3),
PbCl2 (2.3), CdO (2.2), Sb203 (5.0), WO3 (5.0), SiO (5.0),
Si203 (2.5), In203 (2.0), PbO (2.6), Ta203 (2.4), ZnO (2.1),
Zr02 (5.0), MgO (1.0), Si02 (1.45), Si202 (10), MgF2 (4.0),
CeF3 (1.0), CaF2 (1.3-1.4), AIF3 (1.0), AI2O3 (1.0), and
10 Ga02 (2.0). Organic polymers which can be used are, for
example, polyethylene (1.51), polypropylene (1.49),
polytetrafluoroethylene (1.35), polymethyl methacrylate
(1.49), and polystyrene (1.60).
The second reflection layer may be appropriately
15 selected among the foregoing materials in consideration of
patterning by changing a reflectance or a transparency
through dissolution, corrosion, or deterioration with an
etching treatment agent, in accordance with the
manufacturing method described above. Depending on the
20 case, a plurality of materials may be used. When
patterning the second reflection layer, it is preferable to
select appropriately a material and a process which do not
degrade the reflection effect of the first reflection layer.
A method of performing a wet etching treatment on the
25 second reflection layer made of any of the metals or metal
oxides described above can be adopted as a method of
changing a reflectance or a transparency of the second
- 26 -
reflection layer by dissolution. Well-known acids, alkalis,
organic solvents, oxidizing agents, and reducing agents can
be used for etching. Depending on materials of the second
reflection layer, a dry etching method may be used. Also
5 in such a patterning process of the second reflection layer
as described above, only the second reflection layer is
patterned, and the first reflection layer does not change.
As a method of changing the reflectance or
transparency of the second reflection layer, for example,
10 it is possible to employ a method of oxidizing a second
reflection layer made of copper, by an oxidizing agent, to
be changed into copper oxide, or a method of oxidizing a
second reflection layer made of aluminum, by an oxidizing
agent, to be changed into boehmite. Also in such a
15 patterning process of the second reflection layer as
described above, only the second reflection layer is
patterned, and the first reflection layer does not change.
Apart from the method of changing a dissolution
characteristic and a deterioration characteristic of the
20 second reflection layer, it is also possible to change
optical characteristics, such as a refractive index, a
reflectance, or a transmittance, or a practical durability,
such as weather resistance or interlayer tightness.
The second reflection layer is formed as a thin film
25 with a uniform film thickness on a micro uneven surface of
a relief forming layer in the manufacturing method
described above. A dry coating method, such as a vacuum
- 27 -
deposition method, a sputtering method, or a CVD method is
preferably employed.
Protection Layer
The protection layer is light-transmissive and
5 functions as a mask layer when forming the second
reflection layer by patterning.
A material which has resistance to an etching
treatment agent when etching the second reflection layer
may be used for the material of the protection layer, and
10 may be provided with such a film thickness that can ensure
resistance. For example, when the protection layer is
formed by wet coating such as printing, for example,
thermoplastic resin, thermosetting resin, moisture curing
resin, ultraviolet curing resin, or electron-beam curing
15 resin can be used. Specifically, acrylic resin, polyester
resin, or polyamide imide resin can be used. Further, a
lubricant, e.g., wax such as polyethylene powder or carnaba
wax may be added. The lubricant can be added up to a
quantity of 2 0 parts by weight to an extent of not being
20 clouded. Such resin can be diluted with a solvent to an
adequate viscosity and can then be applied to wet coating.
On the other hand, when the protection layer is formed by
dry coating, e.g., a transparent inorganic material such as
silica or alumina can be used. Photosensitive resin can be
25 used as a material other than those described above.
The protection layer of the forgery prevention
structure shown in FIG. 1 is preferably formed by the wet
- 28 -
coating described above.
As a method of forming a pattern for the second
reflection layer using a protection layer, a method of
forming a pattern by changing the reflectance or
5 transparency of the second reflection layer by dissolution,
corrosion, or deterioration, as described above, can be
employed.
Typically, wet etching or dry etching is assumed, and
in such a pattern forming method as described above, a
10 protection layer may be formed in a patterned part of the
second reflection layer in a part to remain.
In the above, layers which form the forgery prevention
structure according to the first embodiment have been
described specifically. However, a reflection film may be
15 provided on the outermost surface in order to improve
optical characteristics. The surface protection film or
reflection film can be provided by using a well-known
coating method.
In order to improve interlayer sealing tightness, a
20 corona treatment, a frame treatment, a plasma treatment,
and primer painting may be performed. In order to improve
optical characteristics, an antireflection treatment may be
performed on the outermost layer.
To further improve the design, a multilayer
2 5 interference film may be formed by coloring a layer or by
configuring the reflection layer in a multilayer
configuration.
- 29 -
Next, a modification of the forgery prevention
structure according to the first embodiment will now be
described with reference to FIG. 3 and FIG. 4. The same
members as in FIG. 1 described above will be denoted at the
5 same reference signs, and descriptions thereof will be
omitted herefrom.
FIG. 3 is a sectional view showing a forgery
prevention sticker. The forgery prevention structure 21
comprises a substrate 22, a relief forming layer 2, a first
10 reflection layer 3, a functional thin film layer 4, a
second reflection layer 5, a protection layer 6, and an
adhesion layer 23, which are layered in this order.
The forgery cancellation sticker 21 configured as
described above is used when transferring the relief
15 forming layer 2, the first reflection layer 3, the
functional thin film layer 4, the second reflection layer 5,
and the protection layer 6 to another substrate (transfer
target), and the adhesion layer 23 is used for adhesion to
yet another substrate. After transfer, the substrate 21
20 may be separated.
By using such a forgery prevention sticker 21 as
described above, a forgery prevention medium to which the
forgery prevention structure is adhered can be obtained.
FIG. 4 is a sectional view showing a forgery
25 prevention transfer foil. A forgery prevention transfer
foil 31 has a structure in which a separable substrate 32,
a relief forming layer 2, a first reflection layer 3, a
- 30 -
functional thin film layer 4, a second reflection layer 5,
a protection layer 6, and an adhesion layer 33 are layered
in this order.
By pressing a heat medium such as a heat roll or a
5 heat plate to the substrate 32 and by heating the medium to
a transfer temperature, the adhesion layer of the forgery
prevention transfer foil 31 is pressed in contact with
another substrate as a transfer target. Simultaneously,
the substrate 32 is separated at the interface between the
10 substrate 32 and the relief forming layer 2.
By using such a forgery prevention transfer foil 31 as
described above, the forgery prevention medium in which the
forgery prevention structure is adhered to the transfer
target can be obtained.
15 In the foregoing forgery prevention structures in
FIG. 3 and FIG. 4, a separation protection layer may be
provided between the substrate and the relief forming layer,
if needed. The separation protection layer is for
achieving a smooth and stable separation from the substrate.
20 Therefore, the separation protection layer is made of a
material with a good mold-release characteristic relative
to the substrate.
The substrate used for the forgery prevention sticker
and forgery prevention transfer foil is preferably a film
2 5 substrate, as described above. As the film substrate, a
material which is less deformed or degraded by heat,
pressure, and electromagnetic waves, which are applied
- 31 -
during formation of a micro uneven pattern (relief
structure), is used. A film made of plastic, such as PET
(polyethylene terephthalate), PEN (polyethylenenaphthalate) ,
or PP (polypropylene), may be used for the film substrate.
5 Depending on the need, a paper made of multiple plastic
layers or a paper impregnated with resin may be used as a
substrate.
Second Embodiment
FIG. 5 is a sectional view showing a forgery
10 prevention structure according to the second embodiment.
A forgery prevention structure 41 comprises a relief
forming layer 42, a first reflection layer 43, a functional
thin film layer 44, a second reflection layer 45, and a
protection layer 46, which are layered in this order. One
15 side of the relief forming layer 42 has a relief structure
comprising a first relief 47 and a second relief 48 with a
micro uneven pattern which performs an effect of
diffracting, scattering, absorbing, and
polarizing/separating a wavelength range of at least a part
20 of visible light. The surface of the first relief 47 has a
smaller uneven surface area in comparison with the surface
of the second relief 48. That is, the first relief 47 has
gentle concave and convex parts, and there are wide
intervals between the concave and convex parts. On the
25 other hand, the second relief 48 has a shape with steeper
concave and convex parts in comparison with the first
relief 47, and intervals between the concave and convex
- 32 -
parts are smaller in comparison with the first relief 47.
The first reflection layer 43 and the functional thin
film layer 44 are provided along the micro uneven surface
of the relief structure 7 (the first and second reliefs 47
5 and 48). The second reflection layer 45 and the protection
layer 46 are provided so as to cover only the surface of
the functional thin film layer 44 of the first relief 47.
That is, in the first area 49, the first reflection
layer 43, the functional thin film layer 44, the second
10 reflection layer 45, and the protection layer 46 are
layered in this order on the uneven surface of the relief
forming layer 42. A colored reflection layer is obtained
which causes at least a partial range of visible light to
interfere, through three layers of the first reflection
15 layer 43, the functional thin film layer 44, and the second
reflection layer 45. The three layers allow a relief
structure to be designed to be capable of forming a
reflection layer which causes a color tone to change in
accordance with the angle of view and a vivid-color
2 0 reflection layer.
The colored reflection layer exists only in the first
area 49, and only the patterned second reflection layer 45
is colored. In the first area 49, the patterned second
reflection layer 45 is colored in itself. As a result, the
25 second reflection layer 45 is a colored pattern in itself,
and therefore, a coloring ink is patterned and printed.
Accordingly, it is possible to avoid positional
- 33 -
misalignment between a colored pattern and a reflection
layer in the conventional method of forming the reflection
layer in alignment with the colored pattern.
The second area 50 is an area where only the first
5 reflection layer 43 and the functional thin film layer 44
are layered on the micro uneven surface of the second
relief 48 of the relief forming layer 42 and where neither
the second reflection layer 45 nor the protection layer 46
exist. Therefore, also in the second area 50, a colorless
10 optical effect owing to a relief structure can be obtained.
In addition, the first area 49 and the second area 50
have different relief structures (the first area 49: the
first relief 47, the second area 50: the second relief 48,
and the uneven surface area: the first relief 47 surface <
15 the second relief 48 surface). For example, both
structures are reliefs of diffraction gratings and
therefore have different uneven surface areas. Accordingly,
both structures exhibit different color change effects.
Further, in the forgery prevention structure 41, a
20 boundary between the first area 49 and the second area 50
is a boundary between different relief structures.
Therefore, there is no positional misalignment among the
pattern of the second reflection layer 45, the colored
pattern, and the pattern (first relief 47) of the relief
25 structure of the first area 49.
Therefore, in the forgery prevention structure
according to the second embodiment, a more precise and
- 34 -
complex optical effect can achieve a high forgery
prevention effect by the colored reflection relief
structure in the first area 49, the colorless reflection
relief structure in the second area 50, or different color
5 change effects between the second areas 40 and 50. A much
higher forgery prevention effect can be exhibited.
Next, a method of manufacturing a forgery prevention
structure according to the second embodiment will be
described.
10 First Process
A relief forming layer is formed on the whole surface
of a substrate. The relief forming layer can be formed by
coating, e.g., by wet coating on the substrate. In
addition, the substrate may serve as a relief forming layer
15 in itself.
Next, an original relief plate made of a metal or
resin and having an uneven shape is prepared. The uneven
shape of the original relief plate is transferred to a
surface of the relief forming layer, to form a relief
20 structure comprising first and second reliefs having an
uneven surface in the relief forming layer. The surface of
the first relief has a smaller uneven surface area in
comparison with the surface of the second relief. That is,
intervals between concave and convex parts of the first
25 relief are wider than those of the second relief.
The method of transferring the shape may be a wellknown
method described in the first embodiment, such as a
- 35 -
press method, a casting method, or a photopolymer method,
or a hybrid method which combines these methods.
Second Process
On the surface of the relief structure of the
5 reflection forming layer, a first reflection layer, a
functional thin film layer, and a thin film layer for a
second reflection layer are formed in this order.
The first reflection layer and the functional thin
film layer can be formed by well-known wet coating or dry
10 coating. The thin film layer for the second reflection
layer can be formed by dry coating, preferably.
Third Process
A protection layer which functions as an etching mask
is formed on the thin film layer for the second reflection
15 layer. Subsequently, the thin film layer for the second
reflection layer is selectively removed by etching with an
etching treatment agent, with the protection layer used as
a mask, to form the second reflection layer. That is, the
thin film layer for the second reflection layer is left to
20 remain in an area under the area (first area 49) of the
protection layer, to form the second reflection film 5.
The thin film layer for the second reflection layer is
removed from under the other areas (second area 50). Here,
the first reflection layer need not be removed by etching.
25 The forgery prevention structure according to the
second embodiment is manufactured through the first to
third processes described above, though is not limited
- 36 -
thereto.
The patterned protection layer and second reflection
film can be formed by another method, as follows. This
method will now be described with reference to FIG. 6.
5 After forming a thin film layer 51 for a second reflection
layer on the whole surface of a functional thin film layer
44 by a gaseous phase method, such as a vacuum deposition
method or a sputtering method, a protection layer 46 is
formed on the whole surface also by a gaseous phase method,
10 such as a vacuum deposition method or a sputtering method.
At this time, a relief structure of a relief forming layer
42 comprises a first relief 47 and a second relief 48
having a shorter interval between concave and convex parts
than the relief 47, as shown in FIG. 6. Therefore, the
15 thin film layer 51 for the second reflection layer and the
protection layer 46 are formed with a sufficient thickness
in the first area 49, and are formed thinly only at tip
ends of convex parts of the uneven shape in the second area
50 where the second relief 48 is present. Therefore, when
20 a subsequent etching treatment is performed on the whole
surface, the protection layer 46 and the thin film layer 51
for the second reflection layer which are formed thinly
only at tip ends of convex parts of the uneven shape in the
second area 50 are removed by etching preferentially. The
25 thin film layer 51 for the second reflection layer (which
functions as the second reflection layer 45) and the
protection layer 46 remain only in the first area 49,
- 37 -
thereby forming a pattern.
A transparent inorganic material such as silica or
alumina is used as a material of the protection layer 46
described above.
5 According to the method as described above, the second
reflection layer 45 (and protection layer 46) can be formed
on the first relief (first area) in accordance with shapes
of the preset first and second reliefs 47 and 48.
Therefore, coloring can be effected only in the first area,
10 and optical effects of different reliefs in the first and
second areas can be obtained.
Materials and required characteristics of individual
layers forming the forgery prevention structure according
to the second embodiment are the same as those described in
15 the first embodiment.
Alternatively, the forgery prevention structure
according to the second embodiment may be modified as shown
in FIG. 3 (forgery prevention sticker) and FIG. 4 (forgery
prevention transfer foil). By using such a forgery
20 prevention sticker or a forgery prevention transfer foil, a
forgery prevention medium to which the forgery prevention
structure is adhered can be obtained.
Hereinafter, Examples of the invention will be
described.
25 Example 1
Example 1 will be described with reference to a
configuration of FIG. 3 as a typical example. An ink made
- 38 -
of a composite described below was applied to a substrate
11 made of a 25-//m-thick transparent polyethylene
terephthalate (PET) film to obtain a film thickness of 2 yym
after drying. The ink was then dried to form the relief
5 forming layer 2. Subsequently, a relief pattern of a
diffraction grating was formed on the surface of the relief
forming layer 2 by a roll embossing method. A first
reflection layer 3 having a film thickness of 50 nm was
formed along the relief pattern by performing vacuum
10 deposition of titanium oxide (Ti02) to the relief forming
layer 2. Further, a functional thin film layer 4 having a
13 0 nm film thickness was formed on the first reflection
layer 3 by performing vacuum deposition of silica (Si02).
Subsequently, an aluminum layer having a film thickness of
15 50 nm was formed on the functional thin film layer 4 by
performing vacuum deposition of aluminum. Subsequently, an
ink made of a composite described below was printed on the
aluminum layer to form a protection layer 6 having a star
pattern. The thickness of the protection layer 6 was 1 \im
20 as a dry film thickness. Thereafter, a second reflection
layer 5 having a star pattern was formed by etching an
aluminum layer part which was exposed by performing an
alkaline etching treatment with the protection layer 6 used
as an etching mask. Thereafter, an ink made of a composite
25 described below was printed on the functional thin film 4
including the protection layer 6 by a gravure printing
method, and was dried to form an adhesion layer 23 having a
- 39 -
film thickness of 3 \im, to obtain a forgery prevention
sticker 21.
"Relief forming-layer ink composite"
Acrylic resin 20.0 weight part
5 Methyl ethyl ketone 50.0 weight part
Ethyl acetate 3 0.0 weight part
"Protection layer ink composite"
Polyamide resin 20.0 weight part
Ethanol 50.0 weight part
10 Toluene 3 0.0 weight part
"Adhesion layer ink composite"
Acrylics adhesive 50 weight part
Silica 10 weight part
Methyl ethyl ketone 40 weight part
15 Comparative Example 1
As shown in FIG. 7A, an ink made of a composite
described below was printed on a substrate 101, to form a
colored layer 102 having a star pattern. Subsequently, a
relief forming layer 103 was formed on the substrate 101
2 0 including the colored layer 102 by the same method as in
Example 1. The relief structure 104 which had micro
unevenness on one side of the relief forming layer 103 was
formed. Subsequently, an aluminum layer having a film
thickness of 50 nm was formed on the relief forming layer
25 103 by performing vacuum deposition of aluminum.
Subsequently, a protection layer ink composite which is the
same as that in Example 1 was printed on the aluminum layer.
- 40 -
to form a protection layer 105 having a star pattern. The
thickness of the protection layer 105 was 1 iim as a dry
film thickness. Subsequently, a second reflection layer
106 was formed by etching an aluminum layer part which was
5 exposed by performing an alkaline etching treatment with
the protection layer 105 used as an etching mask (see
FIG. 7B). Thereafter, the same adhesion layer ink
composite as in Example 1 was printed on the functional
forming layer including the protection layer by a gravure
10 printing method, and was dried to form an adhesion layer
having a film thickness of 3 ym, to thereby obtain a
forgery prevention sticker.
Between the colored layer of the star pattern and the
protection layer of the star pattern, matching was
15 performed as much as possible by overprinting (overlay
registration printing).
"Pattern colored layer ink composite"
Urethane printing ink/yellow 50.0 weight parts
Methyl ethyl ketone 25.0 weight parts
20 Ethyl acetate 25.0 weight parts
Forgery prevention was evaluated for the forgery
prevention stickers according to Example 1 and Comparative
Example 1.
Evaluation of Forgery Prevention Characteristics
25 After taking an enlarged photograph by a microscope,
an area ratio was evaluated between the "colored reflection
layer area" and the "reflection layer area (the area of the
41
10
15
second reflection layer in Example 1 and the area of the
reflection layer in Comparative Example 1)" (colored
reflection layer area mm^/reflection layer area mm^ (the
area of the second reflection layer in Example 1 and the
area of the reflection layer in Comparative Example 1)).
After taking an enlarged photograph by a microscope,
photograph image analysis was conducted, and a positional
misalignment width (mm) between the "area of the colored
reflection layer" and the "area of the second reflection
layer" was measured.
The area ratio (mm^/mm^) and the positional
misalignment width (mm) each were measured at 2 0 portions,
and averaged values and maximum values were obtained for
the ratio and width.
The following table 1 shows results thereof.
Table 1
Area ratio of colored
layer/reflection layer.
Averaged values (n = 20)
Area ratio of colored
layer/reflection layer.
Maximum values (n - 20)
Positional misalignment
between colored layer &
reflection layer.
Averaged values (n = 20)
Positional misalignment
between colored layer &
reflection layer.
Maximum values (n = 20)
Example 1
1.00
1.00
0.00 mm
0.00 mm
Comparative
Example 1
1.00
1.02
0.76 mm
1.00 mm
As is apparent from Table 1, the forgery prevention
structure according to Example 1 achieves an excellent area
ratio of 1.00 and positional misalignment of 0.00 mm (less
- 42 -
than 0.01 mm below the limit of measurement). In contrast,
the forgery prevention structure according to Comparative
Example 1 achieves an area ratio of 1.02 and causes
positional misalignment of 1.00 mm at maximum.
5 Through visual observation of the forgery prevention
structure according to Comparative Example 1, misalignment
of the coloring layer relative to a reflection layer was
checked.
Industrial Applicability
10 According to the present invention, a forgery
prevention structure with high design quality and high
security can be provided with a reflection layer of a
desired color tone and an arbitrary pattern, and a forgery
prevention structure which is excellent in design and/or
15 security can be provided. Hence, applications to valuable
papers, brand-name products, certificates, and personal
authentication media are available.
Reference Signs List
1, 41... Forgery prevention structure, 2, 42... Relief
20 forming layer, 3, 43... First reflection layer, 4, 44...
Functional thin film layer, 5, 45... Second reflection
layer, 6, 46... Protection layer, 8, 49... First area, 9,
50... Second area, 47... First relief, 48... Second relief,
11, 22, 32... Substrate.
25

1 •, ^.'
C L A I M S
1. A forgery prevention structure configured by
layering at least a relief forming layer, a first
reflection layer, a functional thin film layer, a second
5 reflection layer, and a protection layer, in this order,
characterized in that:
the relief forming layer has, on one side, a relief
structure which has an effect of diffracting, scattering,
absorbing, and polarizing/separating at least a part of a
10 wave-length range of visible light;
the first reflection layer and the functional thin
film layer are provided along a whole surface of an uneven
area of the relief structure;
the second reflection layer is provided in an
15 arbitrary area which covers a part of the uneven area of
the relief structure;
the protection layer is provided so as to cover only
an area of the second reflection layer; and
three layers of the first reflection layer, the
20 functional thin film layer, and the second reflection layer
cause at least a partial range of visible light to
interfere.
2. A forgery prevention structure configured by
layering at least a relief forming layer, a first
25 reflection layer, a functional thin film layer, a second
reflection layer, and a protection layer, in this order,
characterized in that:
the relief forming layer has, on one side, a relief
structure comprising a first relief and a second relief
which perform an effect of diffracting, scattering,
absorbing, and polarizing/separating a wavelength range of
5 at least a part of visible light;
a surface of the first relief has a greater uneven
surface area in comparison with a surface of the second
relief;
the first reflection layer and the functional thin
10 film layer are provided along a whole surface of an uneven
area of the relief structure;
the second reflection layer and the protection layer
are provided so as to cover only a surface of the
functional thin film layer of the second relief; and
15 three layers of the first reflection layer, the
functional thin film layer, and the second reflection layer
cause at least a partial range of visible light to
interfere.
3. The forgery prevention structure according to
20 claim 1 or 2, characterized in that the first reflection
layer includes at least one selected from a group of
tantalum oxide, niobium oxide, titanium oxide, indium oxide
tin, zirconium oxide, cerium oxide, and hafnium oxide.
4. The forgery prevention structure according to any
25 one of claims 1 to 3, characterized in that the first
reflection layer is formed by a high-luminance transparent
reflection painting material, which is made of high
^0I0P^
1 'm -1''3
refraction particles.
5. The forgery prevention structure according to any
one of claims 1 to 4, characterized in that the relief
structure comprises at least one of a diffraction structure,
5 a hologram, a convergence lens array, a diffusion lens
array, and a scattering structure at least partially on one
unique plane.
6. The forgery prevention structure according to any
one of claims 1 to 5, characterized by a sticker
10 configuration in which a relief forming layer, a first
reflection layer, a functional thin film, a second
reflection layer, a protection layer, and an adhesion layer
are layered in this order on a substrate at least,
7. The forgery prevention structure according to any
15 one of claims 1 to 5, characterized in that at least a
substrate is provided, at least a relief forming layer, a
first reflection layer, a functional thin film, a second
reflection layer, a protection layer, and an adhesion layer
are layered in this order on the substrate, and the layers
20 as an object have a transfer foil configuration which can
be separated from the substrate.
8. A forgery prevention medium to which the forgery
prevention medium according to any one of claims/!P\o 7 is
adhered.