U.S. patent application number 10/390013 was filed with the patent office on 2004-01-29 for forgery-preventing film.
This patent application is currently assigned to YUPO CORPORATION. Invention is credited to Asakura, Takaaki, Shikano, Tamio, Ueda, Takahiko.
Application Number | 20040018355 10/390013 |
Document ID | / |
Family ID | 27531655 |
Filed Date | 2004-01-29 |
United States Patent
Application |
20040018355 |
Kind Code |
A1 |
Shikano, Tamio ; et
al. |
January 29, 2004 |
Forgery-preventing film
Abstract
Disclosed is a forgery-preventing film having, on one side of a
first layer (A) comprising a thermoplastic resin, a second layer
(B) comprising a thermoplastic resin wherein said film satisfying
at least one of the following conditions: Condition 1: one side of
said first layer (A) is treated to prevent forgery and said second
layer (B) is formed on the surface of the treated side of said
first layer (A); Condition 2: said second layer (B) comprises at
least two thermoplastic resins of different melt viscosities;
Condition 3: porosity of said second layer (B) is greater than
porosity of said first layer (A); and Condition 4: a polymer net is
formed on one side of said first layer (A) and said second layer
(B) is formed on the surface having the polymer net.
Inventors: |
Shikano, Tamio;
(Kashima-gun, JP) ; Asakura, Takaaki;
(Kashima-gun, JP) ; Ueda, Takahiko; (Kashima-gun,
JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
YUPO CORPORATION
Tokyo
JP
|
Family ID: |
27531655 |
Appl. No.: |
10/390013 |
Filed: |
March 18, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10390013 |
Mar 18, 2003 |
|
|
|
PCT/JP01/08101 |
Sep 18, 2001 |
|
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Current U.S.
Class: |
428/323 ;
428/327 |
Current CPC
Class: |
B32B 27/06 20130101;
Y10T 428/31855 20150401; Y10T 428/24355 20150115; B32B 7/02
20130101; Y10T 428/25 20150115; Y10S 428/916 20130101; Y10S 428/91
20130101; Y10T 428/24331 20150115; Y10T 428/31909 20150401; G03G
7/0026 20130101; G03G 7/0013 20130101; Y10T 428/24479 20150115;
Y10T 428/254 20150115; Y10T 428/28 20150115; Y10T 428/31913
20150401; B32B 27/08 20130101; Y10T 428/2495 20150115 |
Class at
Publication: |
428/323 ;
428/327 |
International
Class: |
B32B 005/16 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 18, 2000 |
JP |
2000-281933 |
Sep 18, 2000 |
JP |
2000-281934 |
Sep 18, 2000 |
JP |
2000-281935 |
Nov 2, 2000 |
JP |
2000-336161 |
Nov 2, 2000 |
JP |
2000-336162 |
Claims
What is claimed is:
1. A forgery-preventing film having, on one side of a first layer
(A) comprising a thermoplastic resin, a second layer (B) comprising
a thermoplastic resin wherein said film satisfying at least one of
Conditions 1 to 4 below: Condition 1: one side of said first layer
(A) is treated to prevent forgery and said second layer (B) is
formed on the surface of the treated side of said first layer (A);
Condition 2: said second layer (B) comprises at least two
thermoplastic resins of different melt viscosities; Condition 3:
porosity of said second layer (B) is greater than porosity of said
first layer (A); and Condition 4: a polymer net is formed on one
side of said first layer (A) and said second layer (B) is formed on
the surface having the polymer net.
2. The forgery-preventing film according to claim 1, wherein a
third layer (C) is formed on the back side of said first layer
(A).
3. The forgery-preventing film according to claim 1 wherein said
first layer (A) is of a multilayer structure.
4. The forgery-preventing film according to claim 1 satisfying
Condition 1.
5. The forgery-preventing film according to claim 4 wherein both
surfaces of said first layer (A) are treated to prevent forgery,
and said second layer (B) and said third layer (C) are formed on
each of the treated surfaces of said first layer (A).
6. The forgery-preventing film according to claim 4 wherein said
forgery-preventing treatment is embossing.
7. The forgery-preventing film according to claim 4 wherein said
forgery-preventing treatment is printing.
8. The forgery-preventing film according to claim 4 wherein the
opacity is from 1 to 60 percent.
9. The forgery-preventing film according to claim 4 wherein the
porosity of said first layer (A) is from 0 to 40 percent and the
porosity of said second layer (B) is greater than 20 percent and
less than or equal to 40 percent.
10. The forgery-preventing film according to claim 9 wherein a
third layer (C) with a porosity of greater than 20 percent and less
than or equal to 40 percent is formed on the back side of said
first layer (A).
11. The forgery-preventing film according to claim 9 which has an
opacity of greater than 60 percent and less than or equal to 99
percent.
12. The forgery-preventing film according to claim 1 satisfying
Condition 2.
13. The forgery-preventing film according to claim 12 wherein the
difference in the melt viscosity of said two thermoplastic resins
of differing melt viscosity contained in said second layer (B) is
greater than 50 Pa.multidot.s.
14. The forgery-preventing film according to claim 12 wherein a
third layer (C) comprising at least two thermoplastic resins of
different melt viscosities is formed on the back side of said first
layer (A).
15. The forgery-preventing film according to claim 14 wherein the
difference in melt viscosity of said two thermoplastic resins of
differing melt viscosity contained in said third layer (C) is
greater than 50 Pa.multidot.s.
16. The forgery-preventing film according to claim 12 which has an
opacity of from 1 to 60 percent.
17. The forgery-preventing film according to claim 1 satisfying
Condition 3.
18. The forgery-preventing film according to claim 17 wherein the
ratio (A/B) of the porosity of said first layer (A) to that of said
second layer (B) is less than or equal to 1/3.
19. The forgery-preventing film according to claim 17 wherein both
said first layer (A) and said second layer (B) comprise an
inorganic finepowder and/or an organic filler, and the average
particle diameter of the inorganic finepowder and/or the organic
filler contained in said second layer (B) is larger than the
average particle diameter of the inorganic finepowder and/or the
organic filler contained in said first layer (A).
20. The forgery-preventing film according to claim 17 wherein a
third layer (C) comprising a thermoplastic resin is formed on the
back side of said first layer (A) and the porosity of said third
layer (C) is greater than that of said first layer (A).
21. The forgery-preventing film according to claim 20 wherein the
ratio (A/C) of the porosity of said first layer (A) to that of said
third layer (C) is less than or equal to 1/3.
22. The forgery-preventing film according to claim 20 wherein both
said first layer (A) and said third layer (C) comprise an inorganic
finepowder and/or an organic filler, and the average particle
diameter of the inorganic finepowder and/or the organic filler
contained in said third layer (C) is larger than the average
particle diameter of the inorganic finepowder and/or the organic
filler contained in said first layer (A).
23. The forgery-preventing film according to claim 17 which has an
opacity of from 10 to 60 percent.
24. The forgery-preventing film according to claim 1 satisfying
Condition 4.
25. The forgery-preventing film according to claim 24 wherein said
polymer net is treated to prevent forgery.
26. The forgery-preventing film according to claim 24 wherein said
film is stretched in at least one direction.
27. The forgery-preventing film according to claim 24 wherein said
polymer net is comprised of a thermoplastic resin tape and has a
network structure in the form of a grid.
28. The forgery-preventing film according to claim 27 wherein a
constituent member (T) in the traverse direction of said polymer
net is unstretched thermoplastic resin tape.
29. The forgery-preventing film according to claim 24 which has an
average traverse and longitudinal tear strength as described in JIS
K7128 is greater than or equal to 20 gf.
30. The forgery-preventing film according to claim 24 wherein a
third layer (C) is formed on the back side of said first layer
(A).
31. The forgery-preventing film according to claim 24 wherein both
sides of said first layer (A) are treated to prevent forgery, and a
second layer (B) and a third layer (C) are formed on each of the
treated surfaces of said first layer (A).
32. The forgery-preventing film according to claim 24 wherein said
second layer (B) and said third layer (C) have an opacity of from 1
to 99 percent.
Description
TECHNICAL FIELD
[0001] The present invention relates to a forgery-preventing film
for use on bank notes, bills, checks, traveler's checks,
securities, cards and the like, which need to prevent forgery and
falsification.
BACKGROUND ART
[0002] In modern society, numerous documents and cards with forgery
and duplication being prohibited are in circulation, such as bank
notes, checks, securities, and cards. The forgery and duplication
of these items must not only be prohibited by law, but must also be
rendered technically impossible to maintain social order. However,
copying and duplication technologies have made alarming strides in
recent years, with the risk of forgery and duplication increasing
each year. The crime of forgery has been increasing of late, and
the techniques employed are becoming ever more sophisticated.
[0003] Accordingly, various techniques of preventing forgery and
duplication have been developed.
[0004] For example, there are techniques of visually detecting
forgery based on external appearance. Specifically, there are
techniques of incorporating fluorescent substances in printed
matter; a technique of printing with magnetic ink to permit visual
detection of the change in density of the ink by magnetic effects
(Japanese Unexamined Patent Publication (KOKAI) Heisei No.
5-177919); the technique of printing with ink comprising
photochromic light-sensitive pigments (Japanese Unexamined Patent
Publication (KOKAI) Showa No. 60-79992); techniques of printing
with ink having specific reflection spectroscopic characteristics
or two or more inks having differences in reflectance exceeding a
prescribed value; printed matter exhibiting change in color when
viewed from a certain angle (Japanese Unexamined Patent Publication
(KOKAI) Heisei No. 5-177919); printed matter imparted with a
watermark (latent image) (Japanese Examined Patent Publication
(KOKOKU) Heisei No. 4-18078, Japanese Unexamined Utility Model
Publication (JIKKAI) No. Showa 58-168457); and the like.
[0005] Further, printed matter that has been finely processed to
render reading of the text and images on a copied paper difficult,
and warning marks that appear on a copied paper have been developed
(Japanese Unexamined Utility Model Publication (JIKKAI) No. Showa
59-64271).
[0006] There are also materials that are printed with special
magnetic ink so that an error occurs when a copy is placed on a
discriminating device; printed materials that are printed so that
the density of printed halftones on copies differs from that of the
original (authentic note) (Japanese Examined Patent Publication
(KOKOKU) Showa No. 56-19273 and Heisei No. 2-51742); and materials
on which are printed characters that cannot be discerned by the
naked eye but on which hidden characters can be read with a
discriminating device (Japanese Unexamined Patent Publication
(KOKAI) Showa No. 62-130874).
[0007] Although such a variety of forgery-preventing strategies has
been developed, most of the originals can be duplicated by graphic
platemaking, and these forgery-preventing strategies cannot be
considered complete. Further, many items such as authentic notes
develop wrinkles during use, and are then rejected by the
discriminating device as "Unusable".
[0008] In consideration of these problems of prior art, the present
invention has for its object to provide a forgery-preventing film
that can be readily distinguished from copies, tends not to
wrinkle, and affords good print adhesion.
DISCLOSURE OF THE INVENTION
[0009] The present inventors conducted extensive research,
resulting in the discovery that the above-stated object can be
achieved by the forgery-preventing film of the present invention
which has, on one side of a first layer (A) comprising a
thermoplastic resin, a second layer (B) comprising a thermoplastic
resin, and satisfies at least one of Conditions 1 to 4:
[0010] Condition 1: one side of first layer (A) is treated to
prevent forgery and second layer (B) is formed on the surface of
the treated side of first layer (A);
[0011] Condition 2: second layer (B) comprises at least two
thermoplastic resins of different melt viscosities;
[0012] Condition 3: porosity of second layer (B) is greater than
porosity of first layer (A); and
[0013] Condition 4: a polymer net is formed on one side of first
layer (A) and second layer (B) is formed on the surface having the
polymer net.
[0014] In the forgery-preventing film of the present invention, a
third layer (C) is desirably formed on the back side of first layer
(A), and first layer (A) is desirably of a multilayer
structure.
[0015] In the forgery-preventing film of the present invention
satisfying Condition 1, both sides of first layer (A) are desirably
treated to prevent forgery, with second layer (B) and third layer
(C) being formed on the treated surfaces of the first layer (A). It
is further desirable that the treatment to prevent forgery is
embossing or printing. The opacity of the film used to prevent
forgery can be adjusted to from 1 to 60 percent. Additionally, the
porosity of first layer (A) can be made from 0 to 40 percent and
the porosity of second layer (B) can be made from greater than 20
percent to less than or equal to 40 percent (referred to
hereinafter as Condition 5). In the film for preventing forgery of
the present invention satisfying Condition 5, a third layer (C),
having a porosity of greater than 20 percent and less than or equal
to 40 percent, is desirably formed on the back side of first layer
(A). The opacity is desirably greater than 60 percent and less than
or equal to 99 percent.
[0016] In the forgery-preventing film of the present invention
satisfying Condition 2, the difference in melt viscosity of two
thermoplastic resins having different melt viscosities contained in
second layer (B) is desirably greater than 50 Pa.multidot.s. A
third layer (C) comprising at least two thermoplastic resins having
different melt viscosities is desirably formed on the back side of
first layer (A). Further, the difference in the melt viscosity of
the at least two thermoplastic resins of different melt viscosities
contained in third layer (C) is desirably greater than 50
Pa.multidot.s.
[0017] Further, the opacity of the forgery-preventing film is
desirably from 1 to 60 percent.
[0018] In the forgery-preventing film of the present invention
satisfying Condition 3, the ratio (A/B) of the porosity of first
layer (A) to that of second layer (B) is desirably less than or
equal to 1/3. Each of first layer (A) and second layer (B)
desirably comprises an inorganic finepowder and/or an organic
filler, with an average particle diameter of the inorganic
finepowder and/or the organic filler contained in second layer (B)
being desirably greater than the average particle diameter of the
inorganic finepowder and/or the organic filler contained in first
layer (A). Further, a third layer (C) comprising a thermoplastic
resin is desirably formed on the back side of first layer (A), with
the porosity of third layer (C) desirably being greater than that
of first layer (A). The ratio (A/C) of the porosity of first layer
(A) to that of third layer (C) is desirably less than or equal to
1/3. In particular, both first layer (A) and third layer (C)
desirably comprise an inorganic finepowder and/or an organic
filler, with the average particle diameter of the inorganic
finepowder and/or the organic filler contained in first layer (C)
desirably being greater than the average particle diameter of the
inorganic finepowder and/or the organic filler contained in third
layer (A). Further, the opacity of the forgery-preventing film is
desirably from 10 to 60 percent.
[0019] The forgery-preventing film of the present invention
satisfying Condition 4 is desirably treated to prevent forgery with
a polymer net. Further, the forgery-preventing film is desirably
stretched in at least one direction, with the polymer net being
desirably comprised of a thermoplastic resin and having a network
structure in the form of a grid. In particular, the structural
component (T) in the traverse direction of the polymer net is
desirably an unstretched thermoplastic resin tape. Further, an
average traverse and longitudinal tear strength as described in JIS
K7128 is desirably greater than or equal to 20 gf. Still further, a
third layer (C) is desirably formed on the back side of first layer
(A). In particular, first layer (A) is desirably treated to prevent
forgery on both surfaces, with second layer (B) and third layer (C)
being desirably formed on each of the treated sides of first layer
(A). Further, the opacity of second layer (B) and third layer (C)
is desirably from 1 to 99 percent.
BEST MODE FOR CARRYING OUT THE INVENTION
[0020] The forgery-preventing film of the present invention is
described in detail below with reference to suitable implementation
modes.
[0021] The forgery-preventing film of the present invention has a
structure in which a second layer (B) is formed on one side of
first layer (A). Further, a third layer (C) is desirably present on
the opposite side of first layer (A). The individual layers
constituting the forgery-preventing film of the present invention
will be described in order, along with their methods of manufacture
and application.
First Layer (A)
[0022] First layer (A) constituting the forgery-preventing film of
the present invention, comprises at least a thermoplastic
resin.
[0023] Examples of the thermoplastic resin employed in first layer
(A) are: high-density polyethylene, medium-density polyethylene,
low-density polyethylene, and other ethylene based resins;
propylene based resins, polymethyl-1-pentene, ethylene-cyclic
olefin copolymers, styrene grafted polyolefin resins, and other
polyolefin resins; nylon 6, nylon 6,6, nylon 6,10, nylon 6,12, and
other polyamide resins; polyethylene terephthalate and copolymers
thereof, polyethylene naphthalate, aliphatic polyester and other
thermoplastic polyester resins; and polycarbonates, atactic
polystyrene, syndiotactic polystyrene, polyphenylenesulfide, and
other thermoplastic resins. Two or more of these compounds may be
combined for use. Of these, the use of polyolefin resins is
preferred. Among the polyolefin resins, from the perspectives of
cost, water resistance, and chemical resistance, the use of
propylene based resin and high-density polyethylene is
preferred.
[0024] The propylene based resin employed is desirably a propylene
homopolymer (polypropylene) exhibiting isotactic, syndiotactic or
some degree of stereoregularity, metallocene propylene, or
copolymer comprising a principal component in the form of propylene
with ethylene, 1-butene, 1-hexene, 1-heptene, 4-methyl-1-pentene,
or some other .alpha.-olefin. These copolymers may be
two-component, three-component, or four-component systems, as well
as random copolymers or block copolymers.
[0025] In addition to a thermoplastic resin, first layer (A) also
desirably comprises an inorganic finepowder and/or an organic
filler.
[0026] An inorganic finepowder with an average particle diameter of
from 0.01 to 15 micrometers, preferably from 0.01 to 8 micrometers,
and more preferably, from 0.03 to 4 micrometers may be employed.
Specifically, calcium carbonate, calcined clay, silica,
diatomaceous earth, talc, titanium dioxide, barium sulfate,
alumina, or the like may be employed.
[0027] An organic filler with an average particle diameter
following dispersion of from 0.01 to 15 micrometers, preferably
from 0.01 to 8 micrometers, and more preferably from 0.03 to 4
micrometers may be employed. A resin differing from the
thermoplastic resin that is the principal component is desirably
selected as the organic filler. For example, when the thermoplastic
resin is a polyolefin resin, the organic resin for the organic
filler is desirably polyethylene terephthalate, polybutylene
terephthalate, polycarbonate, nylon 6, nylon 6,6, cyclic olefin
homopolymer, or the copolymer of a cyclic olefin and ethylene,
having a melting point of from 120 to 300.degree. C. or a glass
transition temperature of from 120 to 280.degree. C.
[0028] As needed, stabilizers, photostabilizers, dispersing agents,
lubricants, fluorescent whitening agents, colorants, and the like
may also be blended into first layer (A).
[0029] For example, 0.001 to 1 weight percent of a steric hindered
phenol-based, phosphorus-based, or amine-based stabilizer may be
blended in as the stabilizer. For example, 0.001 to 1 weight
percent of a steric hindrance amine, benzotriazole-based,
benzophenone-based, or other photostabilizer may be blended in as
the photostabilizer. For example, 0.01 to 4 weight percent of a
silane coupling agent, a higher aliphatic acid such as oleic acid
or stearic acid, a metal soap, polyacrylic acid, polymethacrylic
acid, or salts thereof may be blended in as the dispersing agent of
the inorganic finepowder. For example, 0.001 to 1 weight percent of
imidazole, imidazolone, triazole, thiazole, oxazole, oxadiazole,
cumarin, carbostyryl, thiadiazole, napthylimido, or pyrazolone may
be blended in as the fluorescent whitening agent; specific examples
are 2,5-bis[5-t-butylbenzooxazolyl(2)]thiophene, dicyclohexyl
phthalate, 4-methoxynaphthalic acid-N-methylimide,
diaminostylbenedisulfonic acid derivatives, and diaminostylbene
derivatives. Pellets that have been colored with various pigments
may be blended in a proportion of 5 to 30 weight percent as
coloring agents.
[0030] First layer (A) of the forgery-preventing film of the
present invention may have a single-layer structure or a multilayer
structure of two layers or more. First layer (A) or a portion of a
layer comprising first layer (A) is desirably stretched in at least
one direction.
[0031] When first layer (A) is comprised of a three-layer structure
(A1/A2/A3) of layer (A1), layer (A2), and layer (A3), the thickness
of (A1+A3) is desirably greater than or equal to 1 micrometer, and
the ratio of the thickness of (A1+A3) to A2 is desirably from 1:40
to 1:10. The thickness of first layer (A) is desirably from 25 to
100 micrometers, preferably from 30 to 75 micrometers, and more
preferably from 40 to 60 micrometers.
[0032] In the forgery-preventing film of the present invention that
satisfies Condition 1, one or both sides of first layer (A) is
treated to prevent forgery. The treatment to prevent forgery may be
a direct treatment of the surface of first layer (A), or a layer
that has been treated to prevent forgery may be formed over first
layer (A). The embossing or printing of the surface of first layer
(A) is preferred.
[0033] As examples of methods of embossing, various known presses
and embossers such as planographic presses and roll embossers may
be used to raise in relief the design of an embossing plate by
means of heat and pressure. In the roll embossing method, the
relief design of an embossing drum is imparted by heat and pressure
to the material being embossed. As a specific example, first layer
(A) is extruded in hot melt form as a film from a single-layer or
multilayer T-die or I-die connected to an extruder and then cooled
by cooling rolls to obtain a film. In the course of this process,
the film surface is pressed with embossing rolls to impart a shape
and cooled to fix the shape.
[0034] Portions of the film that contact raised areas of the
embossing rolls during this process are whitened during stretching.
Further, the film is misted by blowing water in mist form to
rapidly cool portions of the film with water droplets and cause
them to turn white. Following cooling of first layer (A), a shape
may also be stamped with hot rolls.
[0035] Various printing methods, such as hot melt transfer,
electrophotography, ink-jet, and laser marker, may be employed in
the treatment to prevent forgery. In particular, when printing a
wax-type or resin-type ink used in the hot melt transfer method,
the image is first transferred to a film with weak ink adhesion, a
heating roll or the like is employed from the back of the print
surface of this film to bring about hot pressure adhesion to the
unstretched film, thereby transferring the image. Accordingly, with
this method, it is possible not to provide a printing device in the
molding line.
[0036] Treatment to prevent forgery by printing is desirably
conducted while first layer (A) is in an unstretched state prior to
stretching. When first layer (A) is being uniaxially stretched,
printing is conducted before longitudinal stretching, and when it
is being biaxially stretched, printing is conducted before
longitudinal or traverse stretching.
[0037] In one form of treatment to prevent forgery of Condition 1,
a layer that has been treated to prevent forgery is sandwiched
between first layer (A) and second layer (B), and/or between first
layer (A) and third layer (C). The layer that has been treated to
prevent forgery may be a printed layer, for example. For example,
the layer that has been treated to prevent forgery may be deposited
following stretching of first layer (A) and then sandwiched in by
forming second layer (B) or third layer (C) thereover. When
preparing a forgery-preventing film comprising, for example, a
uniaxially stretched second layer (B), a biaxially stretched first
layer (A), and a uniaxially stretched third layer (C), following
the longitudinal stretching of layer (A) and immediately before the
hot melt lamination of layer (B), a preprinted film (D) may be
inserted to obtain a forgery-preventing film in the form of a
(B)/(D)/(A)/(D)/(B) or (B)/(D)/(A)/(B) laminate.
[0038] Printed film (D) may be an unstretched film, a uniaxially
stretched film, a biaxially stretched film, or a laminate thereof,
but a uniaxially stretched film is preferred from the perspective
of preventing increased traverse stretching stress in subsequent
processing. Methods of printing include electrophotographic
methods, hot melt transfer, and rewritable marking. An ink-jet
printer may be employed, as may letterpress printing, gravure
printing, flexo printing, solvent offset printing,
ultraviolet-setting offset printing, offset printing, screen
printing and various other forms of printing. The printed image is
desirably reduced in size by 1/(stretching ratio) in consideration
of the subsequent stretching ratio.
[0039] Hot marking the forgery-preventing film satisfying Condition
1 is also possible to prevent forgery. When the opacity of the
forgery-preventing film is made a low 1 to 60 percent, the opacity
of portions that have been hot marked decreases, rendering them
semitransparent or transparent. Portions that are not pressed
during hot marking retain their original semitransparency so that
when exposed to sunlight or a light source such as a fluorescent
lamp, a sharp mark is obtained and forgeries can be detected at a
glance. However, unclear marks are obtained in fully transparent
films, and it tends to be difficult to detect forgeries at a
glance. Further, when a large quantity of inorganic finepowder
and/or organic filler is incorporated, when mark pressing is
conducted at ordinary temperature, in contrast to hot marking,
voids within the film are crushed and the crushed areas become
opaque, with areas outside the pressed areas remaining
semitransparent. It is thus possible to obtain a sharp mark
permitting the detection of forgeries at a glance.
[0040] When the opacity of the forgery-preventing film is greater
than 60 percent and less than or equal to 99 percent, such as when
Condition 5 is satisfied, the pressed portions become less opaque
during hot marking, becoming semitransparent or transparent.
Portions that are not pressed during hot marking retain their
original opacity, so that when exposed to sunlight or a light
source such as a fluorescent lamp, a sharp mark can be recognized,
permitting the detection of forgeries at a glance. However, the
marks become unclear in completely transparent films, and it tends
to be difficult to detect forgeries at a glance.
[0041] The marking step with heating or at ordinary temperature not
only has the effect of preventing forgery, but also effectively
permits persons with impaired vision to readily determine the
denomination of a bill or the like by feeling it with the finger
tips.
Polymer Net
[0042] In the forgery-preventing film of the present invention
satisfying Condition 4, a polymer net is laminated on one side of
first layer (A), and second layer (B) is laminated over the surface
on which the polymer net has been laminated.
[0043] The method of treating the polymer net to prevent forgery is
not specifically limited. For example, a printed layer may be
provided on a thermoplastic resin film, a fluorescent whitening
agent or a fluorescent pigment may be kneaded in, or two or more of
such methods may be employed in combination. When printing is
employed, for example, a trademark, code, mark, patent number,
publisher, producer, material name, product number, product
specification number, lot number, bar code, or the like may be
printed. The size of the print is desirably smaller than the width
of the thermoplastic resin tape constituting the polymer net and
large enough to permit reading without missing print in the case of
a polymer net. Specifically, the print desirably falls within a
range of from 0.5 to 2 mm.
[0044] Methods of printing include electrophotographic methods, hot
melt transfer, rewritable marking, and ink-jet printer. Letterpress
printing, gravure printing, flexo printing, solvent offset
printing, ultraviolet-setting offset printing, offset printing,
screen printing and various other forms of printing may be
employed. The printed image is desirably reduced in size by
1/(stretching ratio) in consideration of the subsequent stretching
ratio.
[0045] The ink employed in printing of the printed layer is not
specifically limited. Common commercially employed inks may be
employed. To better prevent forgery, fluorescent ink,
phosphorescent ink, metallic ink, photochromic ink, thermochromic
ink, holographic ink, bubble ink, and other special inks are
desirably employed. A thermosetting, e-beam setting, or ultraviolet
setting resin is desirably employed as the binder.
[0046] The thermosetting resin film having a printed layer may be
cut using a known microslitter or tape slitter to obtain a
thermoplastic resin tape for use in the polymer net. Cutting is
desirably conducted in unprinted portions. The width of the
thermoplastic resin tape is not specifically limited, but is
normally about 1 to 5 mm.
[0047] There are no restrictions in the running direction or
traverse direction of the thermoplastic resin tape. Woven cloth may
be obtained by a known weaving machine manufacturing method or by
hot melt bonding strands of tape together into a grid. The method
of weaving when employing a weaving machine is not specifically
limited; plain weaving and twill weaving are both acceptable.
[0048] On the forgery-preventing film satisfying Condition 4, it is
also possible to conduct hot marking to prevent forgery. When the
opacity of the forgery-preventing film of the present invention is
made high, at greater than 60 percent and less than or equal to 99
percent, the opacity of areas that are pressed during processing
decreases during hot melt marking, becoming semitransparent or
transparent. Areas that are not pressed during hot melt marking
retain their original opacity, so that when exposed to sunlight or
a light source such as a fluorescent lamp, the mark can be clearly
discerned and forgeries can be detected at a glance. However, in
totally transparent films, the marks become unclear, tending to
make it difficult to determine forgeries at a glance.
[0049] This hot marking affords not only the above-described
forgery-preventing effect, but also effectively permits persons
with impaired vision to readily determine the denomination of a
bill or the like by feeling it with the finger tips.
[0050] One of the above-described forgery-preventing treatment
methods may be selected, or two or more may be selected for use in
combination in the forgery-preventing film of the present
invention. When one method is selected, a good forgery-preventing
effect can be imparted relatively inexpensively. When two or more
methods are selected for use in combination, more effective forgery
prevention can be achieved.
Second Layer (B) and Third Layer (C)
[0051] A second layer (B) is formed on one side of first layer (A)
constituting the forgery-preventing film of the present invention.
A third layer (C) is also formed, desirably on the opposite side of
first layer (A).
[0052] Second layer (B) and third layer (C) both contain
thermoplastic resins. Second layer (B) and third layer (C) also
desirably contain an inorganic finepowder and/or organic filler.
The thermoplastic resin, inorganic finepowder, and organic filler
employed in second layer (B) and third layer (C) may be identical
to those employed in first layer (A).
[0053] As needed, stabilizers, photostabilizers, dispersing agents,
lubricants, fluorescent whitening agents, colorants, and the like
may also be blended into second layer (B) and third layer (C).
[0054] Second layer (B) and third layer (C) may each have a
single-layer structure or a multilayer structure of two or more
layers. One or more of the layers comprising second layer (B) and
third layer (C) is desirably stretched in at least one axial
direction. The thickness of second layer (B) and third layer (C) is
desirably from 5 to 50 micrometers, preferably from 10 to 40
micrometers each. However, when Condition 5 is satisfied, the
thickness of second layer (B) and third layer (C) is desirably 10
to 50 micrometers, preferably 15 to 40 micrometers each.
[0055] In the forgery-preventing film of the present invention, the
structure is desirably one where second layer (B) and third layer
(C) are formed on either side of first layer (A). A
forgery-preventing film in which first layer (A) comprises 40 to
99.5 weight percent of polyolefin resin and 60 to 0.5 weight
percent of an inorganic finepowder and/or organic filler, and
second layer (B) and third layer (C) comprise from 25 to 100 weight
percent polyolefin resin and from 75 to 0 weight percent inorganic
finepowder and/or organic filler is particularly desirable. A
forgery-preventing film in which first layer (A) comprises from 50
to 97 weight percent polyolefin resin and from 50 to 3 weight
percent inorganic finepowder and/or organic filler, and second
layer (B) and third layer (C) comprise from 30 to 97 weight percent
polyolefin resin and from 70 to 3 weight percent inorganic
finepowder is further desirable. However, when the
forgery-preventing film of the present invention satisfies
Condition 5, a forgery-preventing film in which first layer (A)
comprises from 40 to 99.5 weight percent polyolefin resin and from
60 to 0.5 weight percent inorganic finepowder and/or organic
filler, and second layer (B) and third layer (C) comprise from 25
to 85 weight percent polyolefin resin and from 75 to 15 weight
percent inorganic finepowder and/or organic filler is desirable.
Further, a forgery-preventing film in which first layer (A)
comprises from 50 to 97 weight percent polyolefin resin and from 50
to 3 weight percent inorganic finepowder and/or organic filler, and
second film (B) and third film (C) comprise from 30 to 80 weight
percent polyolefin resin and from 70 to 20 weight percent inorganic
finepowder is preferred.
[0056] When the quantity of inorganic finepowder and/or organic
filler contained in first layer (A) exceeds 60 weight percent, the
stretched resin film tends to rupture during traverse stretching
following longitudinal stretching. When the quantity of inorganic
finepowder and/or organic filler in second layer (B) and third
layer (C) exceeds 75 weight percent, the surface strength of second
layer (B) and third layer (C) following traverse stretching
weakens, and second layer (B) and third layer (C) tend to be
damaged by mechanical impact during use.
[0057] Other layers may be provided between first layer (A) and
second layer (B) comprising the forgery-preventing film of the
present invention, between first layer (A) and third layer (C), on
second layer (B), and on third layer (C).
[0058] In the forgery-preventing film of the present invention
satisfying Condition 2, second layer (B) comprises at least two
thermoplastic resins of differing hot melt viscosity. In the
present Specification, the term "hot melt viscosity" refers to the
hot melt viscosity at 230.degree. C. at a shear rate of 1,220
s.sup.-1. Here, the difference in hot melt viscosity of the two
thermoplastic resins of differing holt melt viscosity contained in
second layer (B) is desirably greater than 50 Pa.multidot.s,
preferably greater than or equal to 70 Pa.multidot.s, and more
preferably, greater than or equal to 80 Pa.multidot.s. Third layer
(C) also similarly contains at least two thermoplastic resins of
differing hot melt viscosity, with the difference in hot melt
viscosity of the two thermoplastic resins of differing holt melt
viscosity being desirably greater than 50 Pa.multidot.s, preferably
greater than or equal to 70 Pa.multidot.s, and more preferably,
greater than or equal to 80 Pa.multidot.s. Making the difference in
hot melt viscosity greater than 50 Pa.multidot.s permits the
adequate formation of streaks in the flow generated during
extrusion film molding. These streaks can be used to effectively
prevent forgery.
[0059] The combination of thermoplastic resins of differing hot
melt viscosity is not specifically limited. The thermoplastic
resins employed in above-described first layer (A) may be suitably
combined for use. Specifically, the use of a combination of a
propylene homopolymer and an ethylene based resin, or a propylene
homopolymer and a styrene graft polyolefin resin is preferred. The
thermoplastic resin of higher hot melt viscosity desirably has a
hot melt viscosity of from 180 to 300 Pa.multidot.s, with from 200
to 280 Pa.multidot.s being preferred. The thermoplastic resin of
lower hot melt viscosity desirably has a hot melt viscosity of from
50 to 130 Pa.multidot.s, with from 60 to 120 Pa.multidot.s being
preferred.
[0060] When manufacturing the forgery-preventing film of the
present invention satisfying Condition 3, the average particle
diameter of the inorganic finepowder employed in second layer (B)
and third layer (C) is normally from 2 to 30 micrometers,
preferably from 3 to 20 micrometers, and more preferably from 3 to
15 micrometers. The average particle diameter following dispersion
of the organic filler employed in second layer (B) and third layer
(C) is normally from 2 to 30 micrometers, preferably from 3 to 20
micrometers, and more preferably from 3 to 15 micrometers. And the
average particle diameter of the inorganic finepowder and/or
organic filler employed in second layer (B) and third layer (C) is
desirably greater than the average particle diameter of the
inorganic finepowder and/or organic filler employed in first layer
(A).
Manufacturing and Processing of the Forgery-preventing Film
[0061] The forgery-preventing film of the present invention can be
manufactured by combining various methods known to those skilled in
the art. A forgery-preventing film manufactured by whatever method
only falls within the scope of the present invention if it
satisfies the conditions stated in the claims below.
[0062] An example of a conventional method is to conduct stretching
after the formation of the layers constituting the
forgery-preventing film.
[0063] The forming method is not specifically limited; any known
method may be employed. Specifically, a single-layer or multilayer
T-die or I-die connected to a screw extruder may be employed to
extrude the hot melt resin into film form by cast molding, calender
molding, rolling, inflation molding, cast molding or calendering of
a mixture of thermoplastic resin and organic solvent or oil
followed by removal of the solvent or oil, molding from a solution
of thermoplastic resin, molding by solvent removal, or the
like.
[0064] The stretching method is not also specifically limited; any
of various known methods may be employed. Specific examples of
stretching methods are: stretching between rolls exploiting the
difference in peripheral speed of a group of rolls and clip
stretching exploiting a tenter oven. More specifically,
longitudinal stretching exploiting the difference in peripheral
speed of a group of rolls, traverse stretching employing a tenter
oven, rolling, and simultaneous biaxial stretching by a combination
of a tenter oven and a linear motor may be employed. The stretching
of each layer may be uniaxial, biaxial, or greater. For example,
when manufacturing a film comprised of a three-layer structure
consisting of second layer (B)/first layer (A)/third layer (C), the
degrees of stretching of each layer may be any combination, such as
uniaxial/biaxial/uniaxial, uniaxial/uniaxial/uniaxial, or
biaxial/biaxial/biaxial.
[0065] The stretching ratio is not specifically limited, and may be
suitably selected based on the objective and the characteristics of
the thermoplastic resin employed. For example, when employing a
propylene homopolymer or a copolymer thereof as the thermoplastic
resin, during uniaxial stretching, a ratio of about 1.2 to 12-fold
is desirable, with 2 to 10-fold preferred. During biaxial
stretching, an area ratio of from 1.5 to 60-fold is desirable, with
from 10 to 50-fold being preferred. When employing other
thermoplastic resins, during uniaxial stretching, a ratio of from
1.2 to 10-fold is desirable, with from 2 to 5-fold being preferred.
During biaxial stretching, a surface area ratio of from 1.5 to
20-fold is desirable, with from 4 to 12-fold being preferred. As
needed, a heat treatment may be applied at elevated
temperature.
[0066] Drawing is conducted within a suitable known temperature
range of greater than or equal to the glass transition temperature
when an amorphous resin is employed and from greater than or equal
to the glass transition temperature of the amorphous component and
less than or equal to the crystal melting temperature of the
crystalline portion when a crystalline resin is employed.
Generally, stretching is desirably conducted at a temperature of
from 2 to 60.degree. C. lower than the melting point of the
thermoplastic resin employed. When employing a thermoplastic resin
in the form of a propylene homopolymer (with a melting point of
from 155 to 167.degree. C.), stretching is desirably conducted at
from 152 to 164.degree. C., when employing high-density
polyethelene (with a melting point of from 121 to 134.degree. C.),
stretching is desirably conducted at 110 to 120.degree. C., and
when employing polyethylene terephthalate (with a melting point of
from 246 to 252.degree. C.), stretching is desirably conducted at
from 104 to 115.degree. C.
[0067] Further, a stretching rate of from 20 to 350 m/min is
desirable.
[0068] The order of lamination and stretching of the individual
layers comprising the forgery-preventing film of the present
invention is not specifically limited. For example, first layer (A)
and second layer (B) may be separately stretched and then
laminated, or first layer (A) and second layer (B) may be laminated
and then collectively stretched. When third layer (C) is present,
the three layers may be separately stretched and then laminated,
laminated first and then collectively stretched, or first layer (A)
and third layer (C) may be laminated and stretched, after which
stretched or unstretched second layer (B) may be laminated to
manufacture the forgery-preventing film of the present invention.
These methods may also be suitably combined.
[0069] The preferred manufacturing method is to first laminate
multiple layers and then conduct stretching collectively. Greater
convenience is afforded and the cost is lower than when each layer
is separately stretched and then laminated.
[0070] When an inorganic finepowder and/or organic filler is
contained in the layers, stretching causes fine cracking of the
film surface, with fine voids being produced in the film. The
porosity of the forgery-preventing film of the present invention
following stretching is from 1 to 20 percent, preferably from 2 to
15 percent, when it is desirable to suppress opacity in a
forgery-preventing film satisfying Condition 1. The same is true
for forgery-preventing films satisfying Conditions 2, 3, and 4.
[0071] In a forgery-preventing film satisfying Condition 3, the
porosity of second layer (B) is made greater than that of first
layer (A). The use of such a configuration makes clear the presence
of voids nonuniformly distributed within second layer (B) or
produces white pattern in the second layer (B) that effectively
prevent forgery. To effectively generate white pattern, it is
desirable to keep the porosity (A/B) of first layer (A) to second
layer (B) to less than or equal to 1/3. In a forgery-preventing
film of the present invention comprising third layer (C), the
porosity of third layer (C) is desirably made greater than that of
first layer (A), with the porosity (A/C) being kept to less than or
equal to 1/3.
[0072] In a forgery-preventing film satisfying Condition 5, the
respective porositys of first layer (A), second layer (B), and
third layer (C) are desirably from 0 to 40 percent, greater than 20
percent and less than or equal to 40 percent, and greater than 20
percent and less than or equal to 40 percent, with respective
porositys of from 1 to 30 percent, 25 to 35 percent, and 25 to 35
percent being preferred. When each of these exceeds 40 percent, the
forgery-preventing treatment becomes difficult to make out with
transmitted light.
[0073] To improve the antistatic property and suitability to
various forms of printing of the thermoplastic resin layer
comprising the outermost layer of the forgery-preventing film of
the present invention, a surface treatment is desirably conducted
to modify the surface following molding of the laminate structure.
An example of a surface treatment method is the combination of a
surface oxidation treatment and treatment with a surface treatment
agent.
[0074] The surface oxidation treatment may be conducted by the use,
either singly or in combination, of generally employed corona
discharge treatment, flame treatment, plasma treatment, glow
discharge treatment, ozone treatment, or the like. Of these, the
corona treatment and flame treatment are preferred. The corona
treatment level is desirably from 600 to 12,000 J/m.sup.2 (10 to
200 W.multidot.min/m.sup.2), with from 1,200 to 9,000 J/m.sup.2 (20
to 150 W.multidot.min/m.sup.2) being preferred. The flame treatment
is desirably conducted at from 8,000 to 200,000 J/m.sup.2, with
from 20,000 to 100,000 J/m.sup.2 being preferred.
[0075] The surface treatment agent may be selected chiefly from
among the following primers and antistatic polymers, and may thus
be a single compound or a mixture of two or more components. From
the perspective of preventing static and improving adhesion in a
dry laminate, the preferred surface treatment agent is a primer or
a combination of primer and antistatic polymer.
[0076] Examples of primers constituting surface treatment agents
suitable for use are: polyethyleneimine, polyethyleneimines
modified with alkyls having from 1 to 12 carbon atoms,
ethyleneimine adducts of poly(ethyleneimine-urea) and
polyaminepolyamide and epichlorhydrin adducts of polyamine
polyamides, and other polyethyleneimine polymers; acrylic acid
amide-acrylic acid ester copolymers; acrylic acid amide-acrylic
acid ester-methacrylic acid ester copolymers, polyacrylamide
derivatives, oxazoline group-comprising acrylic acid ester
polymers, polyacrylic acid esters, and other acrylic acid ester
polymers; polyvinyl pyrrolidone, polyethylene glycol, polyvinyl
alcohol, and other water-soluble resins; and polyvinyl acetate,
polyurethane, ethylene-vinyl acetate copolymers, polyvinylidene
chloride, polypropylene chloride, acrylonitrile-butadiene
copolymers, and other water-dispersible resins.
[0077] Of these, the compounds of preference are the
polyethyleneimine polymers, urethane resins, and polyacrylic acid
esters. The compounds of greater preference are the
polyethyleneimine polymers. And the compounds of even greater
preference are polyethyleneimines having a degree of polymerization
of from 20 to 3,000, the ethyleneimine adducts of polyamine
polyimides, and modified polyethyleneimines obtained by modifying
these compounds with alkyl halides having from 1 to 24 carbon
atoms, alkenyl halides having from 1 to 24 carbon atoms, cycloalkyl
halides having from 1 to 24 carbon atoms, and halogenated benzyl
groups having from 1 to 24 carbon atoms.
[0078] Examples of antistatic polymers comprising surface treatment
agents are cationic polymers, anionic polymers, and amphoteric
polymers. Examples of cationic polymers are polymers having
quaternary ammonium salt or phosphonium salt structures,
nitrogenous acrylic polymers, and nitrogenous acrylic or
methacrylic polymers having a quaternary ammonium salt structure.
Examples of amphoteric polymers are nitrogenous acrylic or
methacrylic polymers having a betaine structure. Examples of
cationic polymers are styrene-maleic anhydride copolymers and their
alkali metal salts, alkali metal salts of ethylene-acrylic acid
copolymers, and alkali metal salts of ethylene-methacrylic acid
copolymers. Of particular preference are nitrogenous acrylic or
methacrylic polymers having a quaternary ammonium salt
structure.
[0079] The molecular weight of the antistatic polymer may be
adjusted as desired based on the polymerization temperature, the
type and quantity of polymerization initiator employed, the
quantity of solvent employed, the chain-transfer agent employed,
and other polymerization conditions. The molecular weight of the
polymer obtained is generally from about 1,000 to 1,000,000, with a
range of from 1,000 to 500,000 being preferred.
[0080] The surface treatment agent employed in the present
invention may comprise as needed a crosslinking agent, alkali metal
salt, alkaline earth metal salt, or the like.
[0081] The addition of a crosslinking agent to the surface
treatment agent further improves coating strength and water
resistance. Examples of crosslinking agents are glycidyl ether,
glycidyl ester, and other epoxy compounds; epoxy resin; and
isocyanate-based, oxazoline-based, formalin-based, and
hydrazide-based water-dispersible resins. The quantity of
crosslinking agent added normally falls within a range of less than
or equal to 100 weight parts per 100 weight parts of the active
components, excluding solvent, of the surface-modifying agent.
[0082] Examples of the alkali metal salts and alkaline earth metal
salts employed in the surface treatment agent are water-soluble
inorganic salts such as sodium carbonate, sodium bicarbonate,
potassium carbonate, sodium sulfite, and other alkali salts; and
sodium chloride, sodium sulfate, sodium nitrate, sodium
tripolyphosphate, sodium pyrophosphate, ammonium alum, and the
like. The quantity added is normally less than or equal to 50
weight parts per 100 weight parts of the active components,
excluding solvent, of the surface-modifying agent.
[0083] Surfactants, antifoaming agents, water-soluble and
water-dispersible finepowder substances, and other adjuvants may be
added to the surface-modifying agent. The quantity of these
components is normally less than or equal to 20 weight parts per
100 weight parts of the active components, excluding solvent, of
the surface-modifying agent.
[0084] The individual components of these surface treatment agents
may be dissolved for use in water or a hydrophilic solvent such as
methyl alcohol, ethyl alcohol, or isopropyl alcohol. Of these, use
in the form of an aqueous solution is conventional. The
concentration of the aqueous solution is normally from 0.1 to 20
weight percent, desirably from about 0.1 to 10 weight percent.
[0085] Coating may be conducted by roll coater, blade coater, bar
coater, air-knife coater, size press coater, gravure coater,
reverse coater, die coater, lip coater, spray coater, or the like.
As required, smoothing may be conducted and a drying step may be
employed to remove excess water or hydrophilic solvent.
[0086] The coating amount is 0.005 to 5 g/m.sup.2, desirably 0.01
to 2 g/m.sup.2, based on dry components.
[0087] The surface treatment may be conducted either before or
after longitudinal or traverse stretching. The surface treatment
agent may be applied in a single application or in a multistage
application.
[0088] Following the surface treatment, as needed, a
writability-imparting layer, print quality-enhancing layer, heat
transfer receiving layer, heat-sensitive recording layer, ink-jet
receiving layer, or the like may be applied by the same method as
used to apply the surface treatment agent.
[0089] When layers are formed on or over the surface of second
layer (B) or third layer (C) in the forgery-preventing film of the
present invention obtained as set forth above, a recording layer
may be provided on the surface of the outermost layer. This
recording layer may be printed by electrophotography, sublimation
heat transfer, hot melt heat transfer, direct thermal, rewritable
marking, ink-jet printer, letterpress printing, gravure printing,
flexo printing, solvent offset printing, ultraviolet-setting offset
printing, or a rotary method based on the form of the film or a
roller.
[0090] One or a combination of two or more of the above-described
forgery-preventing treatments may be applied to the
forgery-preventing film of the present invention. When one such
treatment is applied, a good forgery-preventing effect is achieved
relatively inexpensively. When two or more are combined, a better
forgery-preventing effect is achieved.
Application of the Forgery-preventing Film of the Present
Invention
[0091] The physical properties of the forgery-preventing film of
the present invention can be suitably adjusted based on the purpose
and environment of use.
[0092] In films satisfying Condition 1, where it is desirable to
keep the opacity low, the opacity (JIS P8138) of the
forgery-preventing film of the present invention is desirably from
1 to 60 percent, preferably from 5 to 55 percent, and more
preferably from 15 to 50 percent. When the opacity exceeds 60
percent, the printing and white pattern produced by embossing of
first layer (A) become unclear, tending to compromise the ability
to prevent forgery. In forgery-preventing films satisfying
Condition 2, the same range of opacity is desirable. When the
opacity exceeds 60 percent, the streaks formed in second layer (B)
and third layer (C) become unclear, tending to compromise the
ability to prevent forgery.
[0093] In forgery-preventing films satisfying Condition 3, the
opacity is desirably from 10 to 60 percent, preferably from 15 to
55 percent, and more preferably from 20 to 50 percent. When the
opacity exceeds 60 percent, the white pattern formed on second
layer (B) and third layer (C) become unclear, tending to compromise
the ability to prevent forgery. When opacity is less than 10
percent, the low number of voids and the unclear generation of
white pattern in second layer (B) and third layer (C) tend to
compromise the ability to prevent forgery. In forgery-preventing
films satisfying Condition 4, the opacity is desirably from 1 to 99
percent, preferably from 5 to 97 percent, and more preferably from
15 to 95 percent. When the opacity exceeds 99 percent, the printing
and fluorescent dyes applied to the polymer net are unclear,
tending to compromise the ability to prevent forgery. In
forgery-preventing films satisfying Condition 5, the opacity is
desirably greater than 60 percent and less than or equal to 99
percent, preferably from 65 to 97 percent, and more preferably from
70 to 95 percent. When the opacity exceeds 99 percent, the printing
and white pattern formed by embossing on first layer (A) become
visible when viewed either by reflected light or transmitted light,
tending to compromise the ability to prevent forgery. Further, at
less than or equal to 60 percent, the printing and white pattern
formed by embossing of first layer (A) become unclear when viewed
with reflected light, tending to compromise the ability to prevent
forgery.
[0094] Further, the whiteness (JIS L1015) of the forgery-preventing
film of the present invention is desirably 60-100 percent,
preferably 70 to 100 percent. When the whiteness is outside this
range, images and characters printed on second layer (B), third
layer (C), and the outermost layer become unclear and difficult to
recognize, and the external appearance tends to become
unappealing.
[0095] The thickness of the forgery-preventing film of the present
invention is desirably 50 to 200 micrometers, preferably 60 to 150
micrometers, and more preferably 80 to 120 micrometers. At a
thickness of less than 50 micrometers, strength is inadequate and
durability deteriorates. When a thickness of 200 micrometers is
exceeded, bank notes (paper money) become excessively stiff and
tend to be difficult to handle.
[0096] The tear strength (JIS K7128) of the forgery-preventing film
of the present invention satisfying Condition 5 is desirably
greater than or equal to 20 gf as an average longitudinal and
traverse value. When the tear strength is outside this range, for
example, in bank notes employing the present invention, tearing
tends to begin at notches and scratches produced by circulation,
tending to cause problems in the feeding of paper in automatic
vending machines and the like.
[0097] These physical properties can be adjusted by suitably
combining known methods.
[0098] Since first layer (A) is treated to prevent forgery in the
forgery-preventing film of the present invention, the advantage of
being able to readily detect copies is afforded.
[0099] For example, when a real bill that has been produced with an
embossed forgery-preventing film satisfying Condition 1, or a
forgery-preventing film satisfying Condition 2 or 3, is copied with
silver salt photographic paper, thermal transfer image receiving
paper, an OHP sheet comprised of polyethylene terephthalate
biaxially stretched film, or the like, when the pressing cover of
the copier is made of aluminum, the semitransparent portions of the
real bill are printed bluish black in the copy. Thus, the two are
readily distinguished by a visual comparison of the semitransparent
portions of the real bill and the copy. When the pressing cover of
the copier is a white plastic plate, cloth, or white cardboard, the
pattern and white stripes in the watermark portions of the real
bill end up becoming the color of the paper on the copy and are
lost, and become transparent and are lost on copied OHP film. Thus,
a visual comparison of the watermark portions of the original bill
and the copy reveals the presence or absence of the pattern and
white stripes, permitting ready distinction of the two.
[0100] When a real bill that has been produced with a
forgery-preventing film satisfying Condition 1 that has been
printed to prevent forgery is copied, the contrast of the copied
image of the printed portion of the real bill changes greatly. The
image is no longer sharp, and density decreases. Thus, a visual
comparison of the sharpness of the image of the real bill and the
copy permits the ready distinction of the two.
[0101] To reliably achieve the forgery-preventing effect of the
forgery-preventing film of the present invention, it is desirable
to intentionally provide portions (watermarks) where the recording
layer remains unprinted.
[0102] When a real bill that has been produced using a
forgery-preventing film satisfying Condition 4 is copied, the grid
pattern of the polymer net is not copied. Further, although
printing on the polymer net is copied, the contrast and resolution
of the copied image are quite different. Thus, the image becomes
unclear and the density decreases. Further, in bills that have been
processed to prevent forgery with fluorescent ink and fluorescent
whitening agents, the fluorescent colors cannot be reproduced or
copying is altogether precluded. Thus, the real item and the
forgery can be readily distinguished. Further, when photochromic
ink is employed as the above-described special ink, the printed
pattern of the photochromic portion can be viewed when exposed to
ultraviolet radiation in the form of a black light or the like
although the printed pattern can not be viewed under white light.
When a fluorescent pigment is employed as the special ink, the
printed pattern of the fluorescent pigment can be viewed under
white light and ultraviolet radiation.
[0103] Even when the fluorescent ink portion is copied without
copying the photochromic portion, exposure to ultraviolet radiation
in the form of a black light permits the distinction of real and
forged items.
[0104] Forgery-preventing films satisfying Condition 5 are treated
to prevent forgery so that the treatment of first layer (A) cannot
be seen with reflected light, but must be viewed with transmitted
light. Thus, the forgery-preventing treatment cannot be copied. A
further advantage is afforded in that even were such a treatment to
be copied, the copying would be readily apparent.
[0105] The forgery-preventing film of the present invention can be
broadly applied to any item the forging of which must be prevented.
Examples are bank notes, bills, checks, traveler's checks, lottery
tickets, product certificates, stock certificates, other
securities, various cards, entry tickets, tickets, national
identity cards, driver's licenses, resident cards, household
registers, official stamp certificates, passports, visas, deposit
certificates, and pledge certificates. When the forgery-preventing
film of the present invention is employed to make paper money, the
appearance of the original simple paper bill is maintained without
any sense of incompatibility. Water-repellency and durability are
good, and numerous applications are possible.
EXAMPLES
[0106] The characteristics of the present invention are
specifically described below through examples. The materials,
quantities employed, ratios, treatments, treatment sequences, and
the like indicated in the examples below may be suitably modified
while remaining within the spirit of the present invention.
Accordingly, the scope of the present invention is not to be
interpreted as being limited to these specific examples.
Example 1
[0107] Composition (A) was prepared by mixing 87 weight parts of
propylene homopolymer with a melt flow rate (MFR) of 4 g/10 min, 3
weight parts of heavy calcium carbonate with an average particle
diameter of 3 micrometers, 10 weight parts of high-density
polyethylene with an MFR of 10 g/10 min, 0.05 weight part of
3-methyl-2,6-di-t-butylphenol per a total of 100 weight parts of
the propylene homopolymer and the heavy calcium carbonate, 0.08
weight part of phenol stabilizer (made by Ciba-Geigy Co., product
name Irganox 1010) per a total of 100 weight parts of the propylene
homopolymer and the heavy calcium carbonate, and 0.05 weight part
of phosphorus-based stabilizer (made by G. E. Plastics, product
name Weston 618) per a total of 100 weight parts of the propylene
homopolymer and the heavy calcium carbonate. Composition (A) was
kneaded in an extruder set to 250.degree. C., extruded to
mirror-surface cast rolls through a T-die connected to an extruder
set to 230.degree. C. following extrusion, and while cooling the
back surface with a cooling device, herringbone-embossed with an
embossing roll 0.5 mm deep that had been heated to 100.degree. C.,
to obtain an unstretched film. The film was heated to 160.degree.
C. and stretched 4.6-fold in the longitudinal direction with a
longitudinal stretching device comprising a group of rolls of
varying peripheral speeds.
[0108] Compositions (B) and (C) that were identical in blending
composition to Composition (A) were melted and kneaded in an
extruder set to 240.degree. C. and extrusion laminated onto the
both sides of the stretched film of Composition (A) that had been
obtained as set forth above, to obtain a three-layer laminate
(B/A/C).
[0109] The three-layer laminate obtained was heated to 160.degree.
C. in a tenter oven and stretched 9-fold in the traverse direction.
It was then passed through a heat set zone (set to a temperature of
165.degree. C.) connected to the tenter oven.
[0110] The both surfaces of the film were treated by corona
discharge at an applied energy density of 90
W.multidot.min/m.sup.2. A roll coater was then used to apply to the
both surfaces an aqueous solution containing an equal-quantity
mixture of butyl-modified polyethyleneimine, an ethyleneimine
adduct of polyaminepolyamide, and an acrylic acid alkylester
copolymer having a quaternary ammonium salt structure in a coating
amount of about 0.1 g/m.sup.2 per side after drying and the coating
was dried. The thicknesses of the layers constituting the
three-layer laminate film obtained (B/A/C) was 25/50/25
micrometers.
[0111] The forgery-preventing film obtained had a regular pattern
of white stripes derived from embossing between layers (A) and (B)
and between layers (A) and (C).
Example 2
[0112] Composition (A), identical to that in Example 1, was kneaded
in an extruder set to 250.degree. C. and extruded to mirror-surface
cast rolls through a T-die connected to an extruder set to
230.degree. C., and the back surface thereof was cooled by a
cooling device to obtain an unstretched film. The film was heated
to a temperature of 160.degree. C., sprayed with water by a device
positioned in proximity to the roll for longitudinal stretching,
and longitudinally stretched 4.2-fold by rolls of differing
peripheral speeds. Operations identical to those in Example 1 were
then conducted to obtain a three-layer laminate film of 90
micrometers thick. The thickness of the layers constituting the
three-layer laminate film obtained (B/A/C) was 20/50/20
micrometers. The forgery-preventing film obtained had irregular
pattern of white stripes between layers (A) and (B) and between
layers (A) and (C).
Example 3
[0113] Composition (A) identical to that in Example 1,
ethylene-propylene copolymer (b) with an MFR of 4 g/10 min and a
melting point of 137.degree. C. (DSC peak temperature), and
metallocene polyethylene (c) with an MFR of 4 g/10 min, a density
of 0.91 g/cm.sup.3 and a melting point of 110.degree. C. (DSC peak
temperature) were coextruded through a T-die connected to an
extruder set to 230.degree. C. to obtain a (b)/(A)/(c) three-layer
laminate. The laminate was heated to 155.degree. C., longitudinally
stretched 4.6-fold with a longitudinal stretching device comprised
of a group of rolls of differing peripheral speeds, and wound onto
a roll. A uniaxially stretched film (D) with a thickness of 50
micrometers and an opacity of 20 percent was thus obtained. An
image reduced to {fraction (1/9)}.sup.th original size in a
direction perpendicular to the stretching direction was printed
with an on-site color printer CB-418-T1 made by TEC on the (b) side
of rolled film (D).
[0114] Separately, Composition (A) identical to that in Example 1
was kneaded in an extractor set to 250.degree. C., extruded to
mirror-surface cast rolls through a T-die connected to an extruder
set to 230.degree. C., and the back surface was cooled with a
cooling device to obtain an un stretched film. The film was heated
to 155.degree. C. and longitudinally stretched 4.6-fold with a
longitudinal stretching device comprised of a group of rolls of
differing peripheral speeds to obtain a longitudinally stretched
film of Composition (A).
[0115] The longitudinally stretched film of Composition (A) was
stacked on, and in contact with, the (c) side of uniaxially
stretched film (D) obtained as set forth above (uniaxially
stretched film (D) was fed from the roll) to obtain a two-layer
laminate (D/A). Compositions (B) and (C) of the same composition as
in Example 1 were extruded with an extruder set to 240.degree. C.
onto either side of laminate (D/A) to obtain a four-layer laminate
(B/D/A/C).
[0116] The four-layer laminate thus obtained was heated in a tenter
oven to 160.degree. C. and stretched 9-fold in the traverse
direction. It was then passed through a heat set zone (set to a
temperature of 165.degree. C.) connected to the tenter oven to
obtain a four-layer laminate film of 110 micrometers thick. The
thickness of the layers constituting the four-layer laminate film
(B/D/A/C) was 25/5/55/25 micrometers. The film obtained had a
forgery-preventing layer (D) between layers (A) and (B).
Test Example 1
[0117] The porosity, opacity, and whiteness of each of the
forgery-preventing films obtained in Examples 1-3 were measured.
The porosity was calculated from Equation (1) below:
Porosity (%)=((.rho..sub.0-.rho.)/.rho..sub.0).times.100 (Equ.
1)
[0118] .rho..sub.0 in Equation 1 denotes the true density of the
stretched film and .rho. denotes the density (JIS P-8118) of the
stretched film. So long as the material did not contain a large
amount of air prior to stretching, the true density was nearly
equal to the density before stretching.
[0119] Further, patterns were printed on both sides of each of the
forgery-preventing films with offset printing inks POP.multidot.K
black, POP.multidot.K indigo blue, POP.multidot.K red, and
POP.multidot.K yellow made by Dainippon Ink Kagaku Kogyo (K.K.).
Unprinted portions in the form of 20 mm circles were left so that
watermarks remained.
[0120] The above-described printed forgery-preventing films were
employed as originals and color copies were made with a color
copier (Docu Color 1250, made by Fuji Xerox Co.). Pulp paper and
OHP film comprised of biaxially-stretched polyethylene
terephthalate were employed as the copy medium. An evaluation was
conducted to determine whether the pattern of white stripes of the
watermarks was copied based on the following scale.
[0121] [Evaluation Scale for Films of Examples 1 and 2]
[0122] O: The irregular pattern of white stripes of watermarks was
not copied. The watermarks remained white when pulp paper was
employed as the copy medium, and the watermarks became transparent
when OHP film was employed.
[0123] X: The irregular pattern of white stripes of the watermarks
was copied.
[0124] [Evaluation Scale for Film of Example 3]
[0125] O: The internal printed areas of the watermarks became
unclear, differing from the original.
[0126] X: The internal printed areas of the watermarks were sharp,
and could not be distinguished from the original.
[0127] Further, an attempt was made to use the above-described
forgery-preventing film as a copy medium and make a copy of the
original with a color copier. As a result, the heat of the transfer
roll made it difficult for the forgery-preventing film to pass
(feeding was impossible), precluding color copies.
[0128] The results are given in Table 1:
1 TABLE 1 Thick- Copy medium ness forgery- (micro- Porosity Opacity
Whiteness Pulp preventing meters) (%) (%) (%) paper OHP film
Example 1 100 2 21 90 O O not feedable Example 2 90 4 30 91 O O not
feedable Example 3 110 5 35 93 O O not feedable
[0129] As will be understood from Table 1, when the
forgery-preventing film of the present invention is copied, changes
in the contrast and brightness of the identification pattern permit
the ready distinction of the forgery from the true item. The
forgery-preventing film of the present invention tends not to
develop wrinkles and is well suited to printing and watermarks.
Thus, it can be suitably employed in paper money, securities,
confidential documents, and the like.
Example 4
[0130] Forgery-preventing films were obtained by the same method as
in Example 1 with the exception that a composition was prepared by
blending 60 weight parts of propylene homopolymer with an MFR of 4
g/10 min, 40 weight parts of heavy calcium carbonate with an
average particle size of 3 micrometers, 3 weight parts of
high-density polyethylene with an MFR of 10 g/10 min, and 0.7
weight parts of titanium dioxide with an average particle diameter
of 0.2 micrometer, 0.05 weight part of
3-methyl-2,6-di-t-butylphenol per a total of 100 weight parts of
propylene homopolymer and heavy calcium carbonate, 0.08 weight part
of phenolic stabilizer (product name Irganox 1010, made by
Ciba-Geigy Co.) per a total of 100 weight parts of propylene
homopolymer and heavy calcium carbonate, and 0.05 weight part of
phosphorus-based stabilizer (product name Weston 618, made by G. E.
Plastics) per a total of 100 weight parts of propylene homopolymer
and heavy calcium carbonate, and the obtained composition was
employed as Compositions (B) and (C).
[0131] The forgery-preventing films obtained had white stripes in
regular patterns derived from embossing between layers (A) and (B),
and between layers (A) and (C).
Example 5
[0132] With the exception that the composition described in Example
4 was employed as Compositions (B) and (C), forgery-preventing
films were obtained by the same method as in Example 2. The
forgery-preventing films obtained had irregular pattern of white
stripes between layers (A) and (B) and between layers (A) and
(C).
Example 6
[0133] With the exception that the composition described in Example
4 was employed as Compositions (B) and (C), forgery-preventing
films were obtained by the same method as in Example 3. The
forgery-preventing films obtained had a printed forgery preventing
layer (D) between layers (A) and (B).
Test Example 2
[0134] The opacity, whiteness, and porosity of each layer were
measured for each of the forgery-preventing films of Examples 4-6.
The porosity was obtained from a ratio of voids area determined by
an image analyzer (Model Luzex IID, made by Nireko (K.K.)) that can
analyze the voids observed in a photograph taken by electron
microscopy. Each of the forgery-preventing films was evaluated
under fluorescent light on the following scale:
[0135] O: Forgery-preventing layer invisible in reflected light,
visible in transmitted light.
[0136] X: Forgery-preventing layer visible in both reflected and
transmitted light.
[0137] XX: Forgery-preventing layer invisible in both reflected and
transmitted light.
[0138] The results are given in Table 2.
2 TABLE 2 Thick- ness (micro- Opacity Whiteness Porosity (%)
Evaluation meters) (%) (%) A B C result Example 4 100 83 90 4 30 31
O Example 5 90 75 87 4 23 23 O Example 6 110 87 93 7 37 37 O
[0139] In the forgery-preventing film of the present invention, the
identification pattern cannot be seen in reflected light. However,
since the brightness or contrast of the identification pattern
changes in transmitted light, a forgery and the real item are
readily distinguished. Further, the forgery-preventing film of the
present invention tends not to develop wrinkles and is well suited
to printing and watermarks. Thus, it can be suitably employed in
paper money, securities, confidential documents, and the like.
Example 7
[0140] Composition (A) was prepared by blending 87 weight parts of
propylene homopolymer with an MFR of 4 g/10 min, 3 weight parts of
heavy calcium carbonate with an average particle diameter of 3
micrometers, 10 weight parts of high-density polyethylene with an
MFR of 10 g/10 min, 0.05 weight part of
3-methyl-2,6-di-t-butylphenol per a total of 100 weight parts of
propylene homopolymer and heavy calcium carbonate, 0.08 weight part
of phenolic stabilizer (product name Irganox 1010, made by
Ciba-Geigy Co.) per a total of 100 weight parts of propylene
homopolymer and heavy calcium carbonate, and 0.05 weight part of
phosphorus-based stabilizer (product name Weston 618, made by G. E.
Plastics) per a total of 100 weight parts of propylene homopolymer
and heavy calcium carbonate. Composition A was extruded and kneaded
at 250.degree. C., and extruded through a T-die connected to an
extruder set to 230.degree. C. to obtain an un stretched film. This
film was heated to 155.degree. C. and longitudinally stretched
4.6-fold in a longitudinal stretching device comprised of a group
of rolls of differing peripheral speeds to obtain a stretched
film.
[0141] In an extruder set to 240.degree. C., 50 weight parts of
propylene homopolymer (B1) with a melt viscosity of 200
Pa.multidot.s and 50 weight parts of metallocene polyethylene (B2)
with a melt viscosity of 100 Pa.multidot.s were melted and kneaded.
This Composition (B), which had a difference in melt viscosity of
100 Pa.multidot.s, was extruded onto both surfaces of the stretched
film of Composition (A), to obtain a three-layer laminate (B/A/B).
The melt viscosities of the thermoplastic resins were measured at
230.degree. C. at a shear rate of 1220 S.sup.-1 with a Capillograph
1C (9.55 mm cylinder diameter, L/D=10) made by Toyo Seiki
(K.K.).
[0142] The three-layer laminate obtained was heated to 160.degree.
C. in a tenter oven and then stretched 9-fold in the traverse
direction. It was then passed through a hot set zone (set to
165.degree. C.) connected to the tenter over.
[0143] Both sides of the film were corona discharge treated at an
applied energy density of 90 W.multidot.min/m.sup.2. A roll coater
was then used to apply to the both surfaces an aqueous solution
containing an equal-quantity mixture of butyl-modified
polyethyleneimine, an ethyleneimine adduct of polyaminepolyamide,
and an acrylic acid alkylester copolymer having a quaternary
ammonium salt structure to a coating amount of about 0.1 g/m.sup.2
per side after drying and the coating was dried. The thicknesses of
the layers constituting the three-layer laminate film obtained
(B/A/B) were 20/50/20 micrometers.
[0144] The forgery-preventing film obtained had a transparent
streak pattern in the run direction for use in preventing
forgery.
Example 8
[0145] In an extruder set to 240.degree. C., 50 weight parts of
propylene homopolymer (B1) with a melt viscosity of 200
Pa.multidot.s under a shear rate of 1220 S.sup.-1 at 230.degree. C.
and 50 weight parts of 230.degree. C. styrene graft polyethylene
(B2) with a melt viscosity of 100 Pa.multidot.s under a shear rate
of 1220 S.sup.-1 at 230.degree. C. were melted and kneaded. This
Composition (B), which had a difference in melt viscosity of 100
Pa.multidot.s, was extruded by an extruder and laminated onto both
surfaces of a stretched film of Composition (A) obtained in the
same manner as in Example 7, to obtain a three-layer laminate
(B/A/B). The same operations as in Example 7 were then conducted to
obtain a three-layer laminate film. The thicknesses of the layers
(B/A/B) were 23/50/23 micrometers.
[0146] The forgery-preventing film obtained had a streak pattern in
the run direction for use in preventing forgery.
Test Example 3
[0147] Porosity defined by Equation (1), opacity, and whiteness of
the forgery-preventing films obtained in Examples 7 and 8 were
measured.
[0148] Further, patterns were printed by the same method as in Test
Example 1 on the various forgery-preventing films, and copying was
attempted onto pulp paper and OHP film. Evaluation was conducted
according to the same scale as employed for the film of Examples 1
and 2.
[0149] An attempt was also made to employ the above-described films
for forgery prevention as a copy medium and make a copy of an
original with a color copier. As a result, the heat of the transfer
roll made it difficult for the forgery-preventing film to pass
(feeding was impossible), precluding color copies.
[0150] The results are given in Table 3:
3 TABLE 3 Thick- Copy medium ness forgery- (micro- Porosity Opacity
Whiteness Pulp preventing meters) (%) (%) (%) paper OHP film
Example 7 90 4 25 90 O O not feeddable Example 8 96 5 45 91 O O not
feeddable
[0151] As will be understood from Table 3, when the
forgery-preventing film of the present invention is copied, change
in the brightness of the identification pattern permits the ready
distinction of the forgery from the true item. The
forgery-preventing film of the present invention tends not to
develop wrinkles and is well suited to printing and watermarks.
Thus, it can be suitably employed in paper money, securities,
confidential documents, and the like.
Example 9
[0152] Composition (A) was prepared by blending 87 weight parts of
propylene homopolymer with an MFR of 4 g/10 min, 3 weight parts of
heavy calcium carbonate with an average particle diameter of 3
micrometers, 10 weight parts of high-density polyethylene with an
MFR of 10 g/10 min, 0.05 weight part of
3-methyl-2,6-di-t-butylphenol per a total of 100 weight parts of
propylene homopolymer and heavy calcium carbonate, 0.08 weight part
of phenolic stabilizer (product name Irganox 1010, made by
Ciba-Geigy Co.) per a total of 100 weight parts of propylene
homopolymer and heavy calcium carbonate and 0.05 weight part of
phosphorus-based stabilizer (product name Weston 618, made by G. E.
Plastics) per a total of 100 weight parts of propylene homopolymer
and heavy calcium carbonate.
[0153] Next, Composition (B) was prepared by blending 65 weight
parts of propylene homopolymer with an MFR of 4 g/10 min, 30 weight
parts of heavy calcium carbonate with an average particle diameter
of 10 micrometers, 5 weight parts of high-density polyethylene with
an MFR of 10 g/10 min, 0.05 weight part of
3-methyl-2,6-di-t-butylphenol per a total of 100 weight parts of
propylene homopolymer and heavy calcium carbonate, 0.08 weight part
of phenolic stabilizer (product name Irganox 1010, made by
Ciba-Geigy Co.) per a total of 100 weight parts of propylene
homopolymer and heavy calcium carbonate and 0.05 weight part of
phosphorus-based stabilizer (product name Weston 618, made by G. E.
Plastics) per a total of 100 weight parts of propylene homopolymer
and heavy calcium carbonate.
[0154] Compositions (A) and (B) were extruded and kneaded at
250.degree. C., and extruded through a T-die connected to an
extruder set to 230.degree. C. to obtain a three-layer laminate
(B/A/B). This film was heated to 155.degree. C. and longitudinally
stretched 4.6-fold in a longitudinal stretching device comprised of
a group of rolls of differing peripheral speeds to obtain a
stretched film.
[0155] Additionally, Composition (D) of the same blend composition
as Composition (A) was melted and kneaded in an extruder set to
240.degree. C. and then extrusion laminated onto both sides of the
three-layer laminate stretched film obtained above to obtain a
five-layer laminate (DIB/A/B/D).
[0156] The five-layer laminate was heated to 160.degree. C. in a
tenter oven, stretched 9-fold in the traverse direction, and then
passed through a heat set oven (set to a temperature of 165.degree.
C.) connected to the tenter oven.
[0157] The two surfaces of the film were treated by corona
discharge at an applied energy density of 90
W.multidot.min/m.sup.2. A roll coater was then used to apply to the
both surfaces an aqueous solution containing an equal-quantity
mixture of butyl-modified polyethyleneimine, an ethyleneimine
adduct of polyaminepolyamide, and an acrylic acid alkylester
copolymer having a quaternary ammonium salt structure to a coating
amount of about 0.1 g/m.sup.2 per side after drying and the coating
was dried. The thicknesses of the layers constituting the
five-layer laminate film obtained (D/B/A/B/D) was 24/2/48/2/24
micrometers.
[0158] The forgery-preventing film obtained had an irregular
pattern of white stripes derived from voids in the (B) layers.
Example 10
[0159] In the same manner as in Example 9, Composition (A) was
kneaded in an extruder set to 250.degree. C. and extruded through a
T-die connected to an extruder set to 230.degree. C., and the back
side was cooled with a cooling device to obtain an un stretched
film. The film was heated to a temperature of 160.degree. C. and
longitudinally stretched 4.6-fold by rolls of differing peripheral
speeds.
[0160] Above-described Composition (A) and Compositions (D) and (B)
of the same blend compositions as in Example 9 were coextruded from
an extruder set to 240.degree. C. to laminate the stretched film of
Composition (A) obtained as set forth above, to obtain a five-layer
laminate (B/D/A/D/B). The same operations were then conducted as in
Example 9 to obtain a five-layer laminate film. The thickness of
the layers (B/D/A/D/B) was 2/20/50/20/2 micrometers.
[0161] The film obtained had irregular pattern of white stripes
derived from voids in the B layers.
Test Example 4
[0162] The porosity, opacity, and whiteness of the various
forgery-preventing films obtained in Examples 9 and 10 were
measured. The porosity was obtained from a ratio of voids area
determined by an image analyzer (Model Luzex IID, made by Nireko
(K.K.)) that can analyze the voids observed in a photograph taken
by electron microscopy. Further, a pattern was printed by the same
method as in Text Example 1 on each of the forgery-preventing films
obtained and attempts were made to make copies on pulp paper and
OHP film. Evaluation was conducted on the same scale as for the
films of Examples 1 and 2.
[0163] Further, an attempt was made to use the above-described
forgery-preventing film as a copy medium and make a copy of the
original with a color copier. As a result, the heat of the transfer
roll made it difficult for the forgery-preventing film to pass
(feeding was impossible), precluding color copies.
[0164] The results are given in Table 4.
4 TABLE 4 Copy medium Porosity (%) White- forgery- All Layer Layer
Layer Opacity ness Pulp preventing layers A B D (%) (%) paper OHP
film Example 9 6 9 40 1 35 90 O O not feedable Example 10 6 7 28 1
34 90 O O not feedable
[0165] As will be understood from Table 4, when the
forgery-preventing film of the present invention is copied, change
in the brightness of the identification pattern permits the ready
distinction of the forgery from the true item. The
forgery-preventing film of the present invention tends not to
develop wrinkles and is well suited to printing and watermarks.
Thus, it can be suitably employed in paper money, securities,
confidential documents, and the like.
Example 11
[0166] Composition (A) was prepared by blending 87 weight parts of
propylene homopolymer with an MFR of 4 g/10 min, 3 weight parts of
heavy calcium carbonate with an average particle diameter of 3
micrometers, 10 weight parts of high-density polyethylene with an
MFR of 10 g/10 min, 0.05 weight part of
3-methyl-2,6-di-t-butylphenol per a total of 100 weight parts of
propylene homopolymer and heavy calcium carbonate, 0.08 weight part
of phenolic stabilizer (product name Irganox 1010, made by
Ciba-Geigy Co.) per a total of 100 weight parts of propylene
homopolymer and heavy calcium carbonate and 0.05 weight part of
phosphorus-based stabilizer (product name Weston 618, made by G. E.
Plastics) per a total of 100 weight parts of propylene homopolymer
and heavy calcium carbonate. Composition (A) was kneaded in an
extruder set to 250.degree. C., extruded to mirror-surface cast
rolls through a T-die connected to an extruder set to 230.degree.
C., and the one side was cooled with a cooling device to obtain an
un stretched film. The film was heated to 160.degree. C. and
longitudinally stretched 4.6-fold with a longitudinal stretching
machine comprised of a group of rolls of differing peripheral
speeds.
[0167] Next, a biaxially stretched polyester film of 12 micrometers
thick (product name FE2000, made by Nimura Kagaku Kogyo (K.K.)) was
corona treated on both sides and an acrylic emulsion was coated
thereon using a bar coater in 1 g/m.sup.2. The film was then
gravure printed with characters in the size of 0.7 mm around using
fluorescent pigment ink. The film was cut to a width of 1.0 mm with
a microslitter, and the thermoplastic resin tape obtained was
employed as a structural component (M) in the run direction of a
polymer net.
[0168] Similarly, unstretched metallocene polyethylene film of 40
micrometers thick and containing 200 ppm of the fluorescent
whitening agent East Brite OB-1 (made by Eastman Kodak) was cut to
a width of 1.0 mm with a microslitter and the thermoplastic resin
tape obtained was employed as a structural component (T) in the
traverse direction of the polymer net.
[0169] The tapes were plain woven and heat fused with a hot press.
The obtained cloth (D) had a warp and woof of 12 mesh and an
opening ratio of about 28 percent.
[0170] Cloth (D) was placed on, and in contact with, the surface of
the longitudinally stretched film of Composition (A) (Cloth (D) was
fed from a roll on which it had been wound) to obtain a two-layer
laminate (D/A). Compositions (B) and (C) identical in Composition
to Composition (A) were melted and kneaded in an extruder set to
240.degree. C. and extruded onto either side of this laminate (D/A)
to obtain a four-layer laminate (B/D/A/C).
[0171] The four-layer laminate obtained was heated to 160.degree.
C. in a tenter oven and then stretched 9-fold in the traverse
direction. It was then passed through a heat set zone (set to a
temperature of 165.degree. C.) connected to the tenter oven.
[0172] The two surfaces of the film were treated by corona
discharge at an applied energy density of 90
W.multidot.min/m.sup.2. A roll coater was then used to apply to the
both surfaces an aqueous solution containing an equal-quantity
mixture of butyl-modified polyethyleneimine, an ethyleneimine
adduct of polyaminepolyamide, and an acrylic acid alkylester
copolymer having a quaternary ammonium salt structure in a coating
amount of about 0.1 g/m.sup.2 per side after drying and the coating
was dried. The thicknesses of the layers constituting the
four-layer laminate film obtained (B/D/A/C) were 10/15/50/25
micrometers.
[0173] The forgery-preventing film obtained had a regular grid
pattern derived from the polymer net between layers (A) and
(B).
Example 12
[0174] Hot melt adhesive was applied with a bar coater to a
thickness of about 10 micrometers to a polyimide film of 12.5
micrometers thick (product name: Apical 12.5H, made by Kanegafuchi
Kagaku Kogyo (K.K.)). The film was then gravure printed with
characters in the size of 0.7 mm around using fluorescent pigment
ink. The film was cut to a width of 1.0 mm with a microslitter, and
the thermoplastic resin tape obtained was employed as the
structural component (M) in the run direction of a polymer net. The
remainder of the process was conducted as in Example 11. The
thickness of the layer constituting the four-layer laminate film
obtained (B/D/A/C) of about 10/15/50/25 micrometers.
Example 13
[0175] Composition (A) was prepared by blending 75 weight parts of
propylene homopolymer with an MFR of 4 g/10 min, 14.6 weight parts
of heavy calcium carbonate with an average particle diameter of 3
micrometers, 0.4 weight parts of titanium dioxide with an average
particle diameter of 0.21 micrometer, 10 weight parts of
high-density polyethylene with an MFR of 10 g/10 min, 0.05 weight
part of 3-methyl-2,6-di-t-butylphenol per a total of 100 weight
parts of propylene homopolymer and heavy calcium carbonate, 0.08
weight part of phenolic stabilizer (product name Irganox 1010, made
by Ciba-Geigy Co.) per a total of 100 weight parts of propylene
homopolymer and heavy calcium carbonate and 0.05 weight part of
phosphorus-based stabilizer (product name Weston 618, made by G. E.
Plastics) per a total of 100 weight parts of propylene homopolymer
and heavy calcium carbonate. Composition (A) was kneaded in an
extruder set to 250.degree. C., extruded to mirror-surface cast
rolls through a T-die connected to an extruder set to 230.degree.
C., and the one side was cooled with a cooling device to obtain an
un stretched film. The film was heated to 160.degree. C. and
longitudinally stretched 4.6-fold with a longitudinal stretching
machine comprised of a group of rolls of differing peripheral
speeds.
[0176] Next, a biaxially stretched polypropylene film of 25
micrometers thick (product name P2261, made by Toyo Hoseki (K.K.))
was corona treated on both sides and an acrylic emulsion was
applied with a bar coater in 1 g/m.sup.2. The film was then gravure
printed with characters in the size of 0.7 mm around using
fluorescent pigment ink. The film was cut to a width of 1.0 mm with
a microslitter, and the thermoplastic resin tape obtained was
employed as a structural component (M) in the run direction of a
polymer net.
[0177] Similarly, unstretched polypropylene film of 40 micrometers
thick that contains 200 ppm of the fluorescent whitening agent East
Brite OB-1 (made by Eastman Kodak) was cut to a width of 1.0 mm
with a microslitter and the thermoplastic resin tape obtained was
employed as a structural component (T) in the traverse direction of
the polymer net. The remainder of the process was conducted as in
Example 11. The four-layer laminate film obtained had individual
film thicknesses (B/D/A/C) of about 20/10/50/25 micrometers.
Test Example 5
[0178] The Equation (1) porosity, opacity, and JIS K7128 tear
strength of the various forgery-preventing films obtained in
Examples 11-13 were measured. The following tests were also
conducted.
[0179] (1) Copying Test on a Color Copier
[0180] Color copies were made using a color copier (Docu Color
1250, made by Fuji-Xerox) with the various forgery-preventing films
as the originals. Pulp paper and OHP film comprised of
biaxially-stretched polyethylene terephthalate film were employed
as the copy media. The grid pattern of the polymer net and whether
or not the printing on the polymer net was copied were evaluated on
the following scale.
[0181] Impossible: The grid pattern derived from the polymer net
was not copied and the printing applied to the polymer net was
printed but unclear.
[0182] Possible: Both the grid pattern derived from the polymer net
and the printing on the polymer net were copied.
[0183] (2) Color Copier Paper Feeding Test
[0184] Copying was attempted with a color copier using the various
forgery-preventing films as copy media and the paper feed property
was evaluated on the following scale.
[0185] Impossible: Paper feeding was difficult due to heat from the
toner fixing rolls (there was fusion to the roll and distortion),
precluding color copying.
[0186] Possible: There was no difficulty in feeding paper and color
copying was possible.
(3) The Possibility of Recognition With UV Light
[0187] The appearance when exposed to ultraviolet lamp UVGL-58
(made by Ultraviolet Co.) of each of the forgery-preventing films
was evaluated by naked eye based on the following scale.
[0188] O: Structural components in the traverse direction of the
polymer net that were invisible under white light glowed bluish
white and were recognized.
[0189] X: No change was observed with UV exposure.
[0190] The results are given in Table 5.
5 TABLE 5 Thick- ness Tear Recognition (micro- Porosity strength
Opacity Whiteness Copying by Paper feeding under UV meters) (%)
(gf) (%) (%) color copier in color copier radiation Example 11 100
4 45 30 90 Impossible Impossible O Example 12 100 5 60 32 91
Impossible Impossible O Example 13 105 12 30 84 93 Impossible
Impossible O
[0191] Since the pattern derived from the polymer net and the
brightness and contrast of printed areas changed when the
forgery-preventing film of the present invention was copied, the
copy and the real item were readily distinguishable. Further, the
forgery-preventing film of the present invention tends not to
develop wrinkles, is suited to printing, and has substantial tear
strength.
[0192] As described above, the forgery-preventing film of the
present invention permits the ready distinction of copies from
original items. Further, since the forgery-preventing film of the
present invention tends not to develop wrinkles, is well suited to
printing, and has substantial tear strength, it can be
advantageously employed on paper money, securities, confidential
documents, and the like.
[0193] The present disclosure relates to the subject matter
contained in PCT Application PCT/JP01/08101 filed on Sep. 18, 2001,
Japanese Patent Application No. 281933/2000 filed on Sep. 18, 2000,
Japanese Patent Application No. 281934/2000 filed on Sep. 18, 2000,
Japanese Patent Application No. 281935/2000 filed on Sep. 18, 2000,
Japanese Patent Application No. 336161/2000 filed on Nov. 2, 2000
and Japanese Patent Application No. 336162/2000 filed on Nov. 2,
2000. These applications are expressly incorporated herein by
reference in its entirety.
[0194] The foregoing description of preferred embodiments of the
invention has been presented for purposes of illustration and
description, and is not intended to be exhaustive or to limit the
invention to the precise form disclosed. The description was
selected to best explain the principles of the invention and their
practical application to enable others skilled in the art to best
utilize the invention in various embodiments and various
modifications as are suited to the particular use contemplated. It
is intended that the scope of the invention not be limited by the
specification, but be defined claims set forth below.
* * * * *