U.S. patent application number 13/278390 was filed with the patent office on 2012-02-16 for printable features formed from multiple inks and processes for making them.
This patent application is currently assigned to Cabot Corporation. Invention is credited to Rimple B. Bhatia, Richard Einhorn, Mark Hanpden-Smith, Scott Haubrich.
Application Number | 20120036702 13/278390 |
Document ID | / |
Family ID | 38779494 |
Filed Date | 2012-02-16 |
United States Patent
Application |
20120036702 |
Kind Code |
A1 |
Einhorn; Richard ; et
al. |
February 16, 2012 |
Printable Features Formed from Multiple Inks and Processes for
Making Them
Abstract
A process for forming a reflective feature includes the steps of
(a) providing a substrate having a first surface; (b) forming a
first coating on the first surface, the first coating having a
second surface; and (c) forming a reflective element on the second
surface, the reflective element having a third surface and
comprising nanoparticles
Inventors: |
Einhorn; Richard;
(Albuquerque, NM) ; Hanpden-Smith; Mark;
(Albuquerque, NM) ; Haubrich; Scott; (Albuquerque,
NM) ; Bhatia; Rimple B.; (Los Altos, CA) |
Assignee: |
Cabot Corporation
Boston
MA
|
Family ID: |
38779494 |
Appl. No.: |
13/278390 |
Filed: |
October 21, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11756225 |
May 31, 2007 |
8047575 |
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13278390 |
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11443248 |
May 31, 2006 |
8070186 |
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11756225 |
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Current U.S.
Class: |
29/458 |
Current CPC
Class: |
B42D 25/415 20141001;
Y10S 283/901 20130101; Y10T 29/49885 20150115; B42D 2033/18
20130101; B42D 25/378 20141001; B42D 25/29 20141001; B82Y 20/00
20130101 |
Class at
Publication: |
29/458 |
International
Class: |
B23P 25/00 20060101
B23P025/00 |
Claims
1. A process for forming a reflective feature, the process
comprising the steps of: (a) providing a substrate having a first
surface; (b) forming a first coating on the first surface, the
first coating having a second surface; and (c) forming a reflective
element on the second surface, the reflective element having a
third surface and comprising nanoparticles.
2. The process of claim 1, wherein the first surface comprises two
regions having different surface characteristics, and the first
coating covers at least a portion of both regions.
3. The process of claim 2, wherein the reflective element covers at
least a portion of the two regions.
4. The process of claim 1, wherein step (b) comprises depositing a
first ink onto the first surface and treating the deposited first
ink under conditions effective to form the first coating.
5. The process of claim 4, wherein the depositing comprises direct
write printing the first ink onto the first surface.
6. The process of claim 4, wherein the treating comprises heating
the deposited first ink.
7. The process of claim 4, wherein the treating comprises applying
UV radiation to the deposited first ink.
8. The process of claim 1, wherein step (c) comprises depositing a
second ink onto the second surface and treating the deposited
second ink under conditions effective to form the reflective
element.
9. The process of claim 8, wherein the depositing comprises direct
write printing the second ink onto the second surface.
10. The process of claim 8, wherein the treating comprises heating
the deposited second ink.
11. The process of claim 8, wherein the treating comprises applying
UV radiation to the deposited second ink.
12. The process of claim 1, wherein the first coating comprises a
material selected from the group consisting of: a varnish, an
offset varnish, a dry offset varnish, a shellac, latex, and a
polymer.
13. The process of claim 1, the process further comprising the step
of: (d) forming a second coating on the third surface, the second
coating having a fourth surface.
14. The process of claim 13, wherein the second coating is
transparent.
15. The process of claim 13, wherein the second coating comprises a
material selected from the group consisting of: a varnish, an
offset varnish, a dry offset varnish, a shellac, latex, and a
polymer.
16. The process of claim 1, wherein the nanoparticles comprise
phosphorescent nanoparticles.
17. The process of claim 1, wherein the nanoparticles comprise
metallic nanoparticles.
18. The process of claim 17, wherein a majority of the metallic
nanoparticles are necked with at least one adjacent metallic
nanoparticle.
19. The process of claim 17, wherein the metallic nanoparticles
comprise a metal selected from the group consisting of silver,
gold, zinc, tin, copper, platinum and palladium, and alloys
thereof.
20. The process of claim 17, wherein the metallic nanoparticles
have an average particle size of less than about 200 nm.
21. The process of claim 17, wherein the metallic nanoparticles
have an average particle size of from about 50 nm to about 100
nm.
22. The process of claim 17, wherein the reflective element
comprises a reflective layer that is at least partially
semitransparent.
23. The process of claim 17, wherein the reflective element
comprises a continuous reflective layer.
24. The process of claim 17, wherein the reflective element
comprises a non-continuous reflective layer.
25. The process of claim 17, wherein the reflective feature is more
reflective than it would be in the absence of the first
coating.
26. The process of claim 17, wherein at least one of the first
surface or the second surface has an image disposed thereon,
wherein at least a portion of the image is viewable through the
reflective element when viewed at a first angle relative to the
third surface, and wherein the at least a portion of the image is
at least partially obscured when viewed from a second angle
relative to the third surface.
27. The process of claim 26, wherein the second angle is about
180.degree. minus the angle of incident light, relative to the
third surface.
28. The process of claim 26, wherein the image is formed from a
printing process selected from the group consisting of direct write
printing, intaglio printing, gravure printing, lithographic
printing and flexographic printing processes.
29. The process of claim 26, wherein the image is selected from the
group consisting of a hologram, a black and white image, a color
image, a watermark, a UV fluorescent image, text and a serial
number.
30. The process of claim 17, wherein the reflective element
comprises a plurality of reflective images.
31. The process of claim 17, wherein the reflective element
comprises a plurality of reflective microimages, wherein the
plurality of reflective microimages has an average largest
dimension of less than about 0.5 mm.
32. The process of claim 31, wherein at least one microimage
comprises variable data.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 11/756,225, filed May 31, 2007, which is a
continuation-in-part of U.S. patent application Ser. No.
11/443,248, filed May 31, 2006. Both applications are incorporated
herein by reference in their entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to printable features and to
processes for making printable features. In particular, the
invention relates to reflective and non-reflective printable
features formed on substrates having regions with different surface
characteristics, to multi-layered features, and to processes for
making such features.
BACKGROUND OF THE INVENTION
[0003] Recent advances in color copying and printing have put
increasing importance on developing new methods to prevent forgery
of security documents such as banknotes. While there have been many
techniques developed, one area of increasing interest is in
developing reflective and non-reflective features that cannot be
readily reproduced, particularly by a color copier or printer.
[0004] One approach that has been taken is to formulate an ink for
creating a printed image that is visually distinct from its
reproduction. For example, U.S. Pat. Nos. 5,059,245, 5,569,535, and
4,434,010, the entireties of which are incorporated herein by
reference, describe the use of stacked thin film platelets or
flakes. Images produced with these pigments exhibit angular
metamerism. These pigments have been incorporated into security
inks used, for example, in paper currency. These pigments have also
been incorporated into plastics applications (see, for example, PCT
Publication WO 00/24580, published May 4, 2000). Additional inks
and reflective features are described in U.S. Pat. Nos. 4,705,356;
4,779,898; 5,278,590; 5,766,738; and 6,114,018, the entireties of
which are incorporated herein by reference.
[0005] Another approach used to produce security documents has been
to produce a "covert" image that contains a material which cannot
be seen by the naked eye but which can be made visible under
specific conditions. For example, U.S. Pat. Nos. 5,324,567,
5,718,754, and 5,853,464 disclose the use of Raman active
compounds. U.S. Pat. Nos. 5,944,881 and 5,980,593 describe
fluorescent materials that can be used in an ink. Also, U.S. Pat.
No. 4,504,084 discloses a document containing an information
marking comprised of a first color that is at least partially
opaque or visible in infrared light and a second color, which
conceals the first color in the visible spectrum, but is invisible
to infrared light.
[0006] While these efforts afford printed images that are difficult
to reproduce, advances in color copiers and color printers continue
to be made. Therefore, the need exists for new highly secure
features and for methods for producing such features, particularly
for security documents, which features cannot be easily reproduced,
and which are visually distinct from their reproductions.
[0007] Additionally, the need exists for providing the ability to
create reflective or non-reflective features that display variable
information, e.g., information that is individualized for a
specific product unit, such as a serial number, which variable
information cannot be easily or readily duplicated or copied.
[0008] The need also exists for features that are highly
reflective. Highly reflective features, particularly reflective
features that display variable information, are generally more
difficult to reproduce than non-reflective features.
[0009] The need also exists for highly durable reflective and
non-reflective features that can withstand the rigors of use, for
example, the extensive handling involved with widespread
circulation, or the repeated washing to which authenticated
garments may be subject.
SUMMARY OF THE INVENTION
[0010] In a first embodiment, the invention is to a reflective
feature, comprising: (a) a substrate having a first region and a
second region, the first and second regions having different
surface characteristics; (b) a first reflective element, preferably
comprising metallic nanoparticles, disposed on the first region;
and (c) a second reflective element, preferably comprising metallic
nanoparticles, disposed on the second region, wherein the first
reflective element is more adherent than the second reflective
element to the first region. Preferably, the second reflective
element is more adherent than the first reflective element to the
second region.
[0011] Optionally, the first reflective element is disposed
exclusively on the first region. The substrate may further comprise
a third region, and the reflective feature further comprises a
third reflective element disposed on the third region, wherein the
third reflective element is more adherent than the first reflective
element or the second reflective element to the third region.
[0012] The first region and/or the second region optionally
comprises a composition selected from the group consisting of foil,
film, UV-coated lacquer, paper, coated paper, polymer, and printed
paper.
[0013] The first reflective element and the second reflective
element optionally form a continuous graphical feature that spans
at least a part of the first region and at least a part of the
second region.
[0014] In a preferred embodiment, at least one of the first
reflective element and/or the second reflective element comprises
variable information.
[0015] The substrate optionally is selected from the group
consisting of a banknote, a brand authentication tag, a tax stamp,
an ID document, an alcoholic bottle, and a tobacco product.
[0016] In one embodiment, the first region comprises a first
undercoat. In this embodiment, the first reflective element
optionally exhibits enhanced reflectivity relative to the
reflectivity of the first reflective element on the first region in
the absence of the first undercoat. Additionally, the second region
optionally comprises a second undercoat. In this embodiment, the
second reflective element optionally exhibits enhanced reflectivity
relative to the reflectivity of the second reflective element on
the second region in the absence of the second undercoat.
[0017] In one embodiment, the feature further comprises a first
overcoat disposed on the first reflective element. In this
embodiment, the first reflective element optionally exhibits
enhanced reflectivity relative to the reflectivity of the first
reflective element without the first overcoat. Also, in this
embodiment, the first reflective element optionally exhibits
enhanced durability relative to the durability of the first
reflective element without the first overcoat. The first overcoat
may further be disposed on the second reflective element. In this
embodiment, the second reflective element optionally exhibits
enhanced reflectivity relative to the reflectivity of the second
reflective element without the first overcoat. Also, in this
embodiment, the second reflective element optionally exhibits
enhanced durability relative to the durability of the second
reflective element without the first overcoat. In another aspect,
the feature further comprises a second overcoat disposed on the
second reflective element, wherein the second reflective element
optionally exhibits enhanced reflectivity relative to the
reflectivity of the second reflective element without the second
overcoat. Also, in this embodiment, the second reflective element
optionally exhibits enhanced durability relative to the durability
of the second reflective element without the second overcoat.
[0018] Optionally, the first region is more or less porous than the
second region. In another embodiment, the first region is more or
less hydrophobic than the second region.
[0019] In another embodiment, the present invention is directed to
a process for forming a reflective feature, the process comprising
the steps of: (a) providing a substrate comprising a first region
and a second region; (b) direct write printing, e.g.,
piezo-electric, thermal, drop-on-demand, or continuous ink jet
printing, a first ink onto the first region to form a first
reflective element; and (c) direct write printing a second ink onto
the second region to form a second reflective element, wherein the
first ink is more adherent than the second ink to the first region.
Preferably, the second ink is more adherent than the first ink to
the second region. At least one of the first ink and the second ink
preferably comprises metallic nanoparticles. This process may be
employed, for example, to form the above-described reflective
feature.
[0020] Optionally, the process further comprises the step of direct
write printing a third ink onto a third substrate surface to form a
third reflective element, wherein the substrate further comprises
the third substrate surface, and wherein the third ink is more
adherent than the first ink or the second ink to the third
region.
[0021] In another embodiment, the invention is to a reflective
feature, comprising: (a) a substrate having a first surface; (b) a
first coating disposed on the first surface and having a second
surface; and (c) a reflective element having a third surface and
comprising nanoparticles disposed, at least in part, on the second
surface.
[0022] Optionally, the feature further comprises a second coating,
which optionally is transparent, having a fourth surface disposed,
at least in part, on the third surface. The second coating
optionally comprises a material selected from the group consisting
of: a varnish, an offset varnish, a dry offset varnish, a shellac,
latex, and a polymer.
[0023] In this embodiment, the first surface optionally comprises
two regions having different surface characteristics, and the first
coating covers at least a portion of both regions, and the
reflective element optionally covers at least a portion of the two
regions.
[0024] Optionally, the first coating comprises a material selected
from the group consisting of varnishes, offset varnishes, dry
offset varnishes, shellacs, and polymers. In one aspect, the first
coating further comprises a colorant.
[0025] The nanoparticles optionally comprise phosphorescent
nanoparticles. In another embodiment, the nanoparticles comprise
metallic nanoparticles. In this embodiment, a majority of the
metallic nanoparticles optionally are necked with at least one
adjacent metallic nanoparticle. The metallic nanoparticles
optionally comprise a metal selected from the group consisting of
silver, gold, zinc, tin, copper, platinum and palladium, and alloys
thereof. The metallic nanoparticles may have an average particle
size of less than about 200 nm, e.g., an average particle size of
from about 50 nm to about 100 nm.
[0026] The reflective element optionally comprises a reflective
layer that is at least partially semitransparent. The reflective
element optionally comprises a continuous reflective layer or a
non-continuous reflective layer. Preferably, the reflective feature
is more reflective than it would be in the absence of the first
coating.
[0027] In one aspect, at least one of the first surface or the
second surface has an image disposed thereon, and at least a
portion of the image is viewable through the reflective element
when viewed at a first angle relative to the third surface, and the
least a portion of the image is at least partially obscured when
viewed from a second angle relative to the third surface. The
second angle may, for example, be about 180.degree. minus the angle
of incident light, relative to the third surface. The image
optionally is formed from a printing process selected from the
group consisting of direct write printing, intaglio printing,
gravure printing, lithographic printing and flexographic printing
processes. The image may be selected from the group consisting of a
hologram, a black and white image, a color image, a watermark, a UV
fluorescent image, text and a serial number.
[0028] In one embodiment, the reflective element comprises a
plurality of reflective images. Optionally, the reflective element
comprises a plurality of reflective microimages, wherein the
plurality of reflective microimages has an average largest
dimension of less than about 0.5 mm. At least one microimage
optionally comprises variable data.
[0029] In another embodiment, the invention is to a process for
forming a reflective feature, the process comprising the steps of:
(a) providing a substrate having a first surface; (b) forming a
first coating on the first surface, the first coating having a
second surface; and (c) forming a reflective element on the second
surface, the reflective element having a third surface and
comprising nanoparticles. This process may be employed, for
example, to form the above-described multi-layer reflective
feature.
[0030] In this embodiment, the first surface optionally comprises
two regions having different surface characteristics, and the first
coating covers at least a portion of both regions, and reflective
element optionally covers at least a portion of the two regions.
Step (b) optionally comprises depositing a first ink onto the first
surface and treating the deposited first ink under conditions
effective to form the first coating. The depositing preferably
comprises direct write printing the first ink onto the first
surface. The treating optionally comprises one or more of: drying
the deposited first ink, heating the deposited first ink, and/or
applying UV radiation to the deposited first ink. Step (c)
optionally comprises depositing a second ink onto the second
surface and treating the deposited second ink under conditions
effective to form the reflective element, wherein the depositing
optionally comprises direct write printing the second ink onto the
second surface, and the treating optionally comprises one or more
of: drying the deposited second ink, heating the deposited second
ink, and/or applying UV radiation to the deposited second ink.
Optionally, the process further comprises the step of: (d) forming
a second coating on the third surface, the second coating having a
fourth surface. The second coating optionally is transparent.
[0031] In another embodiment, the invention is to a reflective
feature, comprising (a) a substrate; (b) a reflective element
comprising metallic nanoparticles; and (c) an overcoat comprising a
colorant. The overcoat optionally is transparent. The overcoat
optionally comprises a material selected from the group consisting
of: a varnish, an offset varnish, a dry offset varnish, a shellac,
latex, and a polymer.
[0032] In another embodiment, the invention is to a process for
forming a reflective feature, the process comprising the steps of:
(a) providing a substrate; (b) forming a reflective element on the
substrate, the reflective element comprising metallic
nanoparticles; and (c) forming an overcoat on the reflective
element, the overcoat comprising a colorant. In this embodiment,
the step of forming the reflective element comprising metallic
nanoparticles optionally comprises direct write printing an ink
comprising the metallic nanoparticles onto the substrate. The step
of forming the overcoat comprising a colorant optionally comprises
direct write printing an ink comprising the colorant onto the
substrate and/or the reflective element.
[0033] Additionally, in another embodiment, the invention relates
to a process for forming a printed feature (which may be reflective
or non-reflective). The process comprises the steps of: (a)
providing a substrate comprising a first region and a second
region, the first and second regions having different surface
characteristics, (b) printing a first ink onto the first region to
form a first printed element, and (c) printing a second ink onto
the second region to form a second printed element, wherein the
first ink is more adherent than the second ink to the first region.
At least one of the printing of the first ink and the printing of
the second ink comprises direct write printing. Optionally, the
first printed element and the second printed element form a
continuous or non-continuous graphical feature that spans at least
a part of the first region and at least a part of the second
region. At least one of the first ink and the second ink optionally
comprises a non-reflective colorant, e.g., a non-reflective pigment
or dye.
[0034] In another embodiment, the invention is directed to a
printed security feature, which may be reflective or
non-reflective. The printed security feature comprises: (a) a
substrate having a first region and a second region, the first and
second regions having different surface characteristics, (b) a
first printed element disposed on the first region, and (c) a
second printed element disposed on the second region. In this
aspect, the first printed element and the second printed element
preferably form a continuous or non-continuous graphical feature
that spans at least a part of the first region and at least a part
of the second region.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] The present invention will be better understood in view of
the appended non-limiting figures, wherein:
[0036] FIG. 1 illustrates a reflective or non-reflective feature
disposed on a substrate having a first region and a second region,
the first and second regions having different surface
characteristics;
[0037] FIG. 2 illustrates another feature on a substrate having a
first region and a second region, the first and second regions
having different surface characteristics;
[0038] FIG. 3 illustrates a reflective or non-reflective feature
disposed on a substrate having a first region and a second region,
the first and second regions having different surface
characteristics, and the feature extending across the interface
between the two regions;
[0039] FIG. 4 illustrates an intermediate reflective or
non-reflective feature disposed on the first region of a substrate
having a first region and a second region, the first and second
regions having different surface characteristics;
[0040] FIG. 5 illustrates a wetting ink droplet on a substrate
surface;
[0041] FIG. 6 illustrates a non-wetting ink droplet on a substrate
surface;
[0042] FIG. 7 illustrates an exploded view of a multi-layered
feature according to another embodiment of the present invention;
and
[0043] FIG. 8 illustrates a non-exploded view of the feature of
FIG. 7.
DETAILED DESCRIPTION OF THE INVENTION
Introduction
[0044] The present invention relates to reflective and
non-reflective features. In one aspect, the invention relates to a
feature, e.g., a reflective or non-reflective security feature or a
reflective or non-reflective decorative feature, formed by printing
multiple inks onto multiple regions of a substrate, the regions
having different surface characteristics from one another.
[0045] In one aspect, the feature comprises a reflective feature
that includes a first reflective element disposed on a first region
and a second reflective element disposed on a second region,
wherein the first reflective element is more adherent than the
second reflective element to the first region. The second
reflective element preferably is similarly more adherent than the
first reflective element to the second region. As it is generally
difficult to form features on a substrate having multiple regions
with different surface characteristics, this embodiment of the
invention provides highly secure difficult-to-reproduce reflective
features having significant commercial value. The invention also
relates to processes for forming such reflective features.
[0046] In another embodiment, the invention relates to a printed
feature (which may or may not be reflective), preferably a security
feature or a decorative feature, formed by printing multiple inks
onto multiple regions of a substrate, the regions having different
surface characteristics from one another. The printed feature
includes a first printed element disposed on a first region and a
second printed element disposed on a second region, wherein the
first printed element is more adherent than the second printed
element to the first region. The second printed element preferably
is similarly more adherent than the first printed element to the
second region. As it is generally difficult to form printed
features on a substrate having multiple regions with different
surface characteristics, this embodiment of the invention provides
a highly secure difficult-to-reproduce features having significant
commercial value. In a preferred aspect of this embodiment, the
first printed element and the second printed element form a
continuous graphical feature that spans at least a part of the
first region and at least a part of the second region.
Alternatively, the first printed element and the second printed
element form a non-continuous graphical feature that spans at least
a part of the first region and at least a part of the second
region. The invention also relates to processes for forming such
printed features.
[0047] In another embodiment, the invention relates to a
multi-layered reflective or non-reflective feature, preferably a
reflective or non-reflective security feature or a reflective or
non-reflective decorative feature, formed from multiple inks The
multi-layered reflective or non-reflective features desirably are
highly durable and/or highly reflective. The invention also relates
to processes for forming such reflective or non-reflective
features.
[0048] As used herein, the term "security feature" means a feature
that is placed on or otherwise incorporated into an article (e.g.,
a tag or label, a document such as a passport, check, bond,
banknote, currency, ticket, etc.), directly or indirectly, for the
purpose of authenticating the article. As used herein, the term
"decorative feature" means a feature that is not provided primarily
for an authentication purpose, but rather primarily for a graphical
or decorative purpose. As used herein the term "reflective element"
means a reflective portion of a reflective feature.
[0049] Possible uses for the reflective or non-reflective features
of the present invention may vary widely. Generally, the features
of the invention may be employed as security features in any
product that is subject to counterfeiting, imitation or copying.
Thus, in one embodiment, the invention is to a banknote comprising
a feature of the present invention. In another embodiment, the
invention is to a fiduciary document comprising a feature of the
invention. In another embodiment, the invention is to a certificate
of authenticity comprising a feature of the invention. In another
embodiment, the invention is to a brand authentication tag
comprising a feature of the present invention. In another
embodiment, the invention is to an article of manufacture
comprising a brand authentication tag comprising a feature of the
present invention. In another embodiment, the invention is to a tax
stamp comprising a feature of the present invention. In another
embodiment, the invention is to an alcohol bottle comprising a tax
stamp comprising a feature of the present invention. In another
embodiment, the invention is to a tobacco product container
comprising a tax stamp comprising a feature of the present
invention. The present invention is not limited to the foregoing
examples, and a number of other substrates and/or substrate
surfaces may comprise the features of the present invention.
[0050] The reflective and non-reflective features of the present
invention are not limited to security applications. The features
may also be employed, for example, for brand protection, brand
personalization (e.g., short run personal care/cosmetics),
trademarks, or in graphics, decorative features, non-secure
documents (e.g., business cards, greeting cards, paper products,
etc.), advertisements, mass mailings, wall paper, ceramic tiles, to
name but a few. Thus, in one embodiment, the feature comprises a
decorative feature. The present invention is not limited to the
foregoing examples, and a number of other substrates and/or
substrate surfaces may comprise the features of the present
invention.
Printed Features Formed on Regions of a Substrate Having Different
Surface Characteristics
[0051] In a first embodiment, the invention is to a reflective
feature, preferably a reflective security feature or a reflective
decorative feature, comprising a substrate having a first region
and a second region, the first and second regions having different
surface characteristics. A first reflective element is disposed on
the first region and a second reflective element is disposed on the
second region. In this embodiment, the first reflective element is
more adherent than the second reflective element to the first
region, and, preferably, the second reflective element is more
adherent than the first reflective element to the second
region.
[0052] In another embodiment, the invention is to a printed
feature, preferably a security feature or a decorative feature,
that is not necessarily reflective, the feature comprising a
substrate having a first region and a second region, the first and
second regions having different surface characteristics. A first
printed element is disposed on the first region and a second
printed element is disposed on the second region. In this
embodiment, the first printed element is more adherent than the
second printed element to the first region, and, preferably, the
second printed element is more adherent than the first printed
element to the second region. In one embodiment, at least one of
the first region and the second region is reflective, e.g., a
metallic foil.
[0053] As used herein, the term "surface characteristic" is meant
to refer to any property that affects the level of adherence of a
substance, e.g., a fluid ink or a composition formed therefrom, to
a surface. By way of non-limiting examples, wetting
characteristics, porosity, surface energy, charge, bonding ability
and hydrophobicity are surface characteristics that may affect the
level of adherence of a substance to a surface. In one embodiment,
for example, the first region (and the first surface thereof) is
more porous than the second region (and the second surface
thereof). In another embodiment, the first region (and the first
surface thereof) is less porous than the second region (and the
second surface thereof). In another embodiment, the first region
(and the first surface thereof) is more hydrophilic (less
hydrophobic) than the second region (and the second surface
thereof). In another embodiment, the first region (and the first
surface thereof) is less hydrophilic (more hydrophobic) than the
second region (and the second surface thereof). In another
embodiment, the first region (and the first surface thereof) has a
surface energy that is greater than the surface energy of the
second region (and the second surface thereof). In another
embodiment, the first region (and the first surface thereof) has a
surface energy that is less than the surface energy of the second
region (and the second surface thereof).
[0054] For purposes of the present specification, the level of
adherence of the first and second reflective or non-reflective
(printed) elements to the first and second regions may be
determined by ASTM rub test: ASTM D-5264D92, the entirety of which
is incorporated herein by reference, wherein the adherence is rated
on a scale of 1 to 5, a rating of 5 indicating the highest level of
adherence. Under this test, the first element preferably has an
adherence to the first region that is rated a 2 or greater, 3 or
greater, 4 or greater or 5 on ASTM D-5264D92. Additionally, the
second element preferably has level of adherence to the second
region that is 2 or greater, 3 or greater, 4 or greater or 5 as
determined by ASTM D-5264D92. In another aspect, the durability of
the first and second elements may be determined by using a Scotch
tape test, in which pressure-sensitive tape is applied to an area
of the feature (e.g., the first and second reflective elements
thereof), which optionally is cross-hatched with scratched lines,
and then lifted off. Adhesion is considered to be adequate if the
coating is not pulled off by the tape when it is removed.
Substantial removal of the first and/or second elements with the
Scotch tape indicates durability failure under this test.
[0055] The specific form of the reflective or non-reflective
feature, e.g., reflective or non-reflective security features or
reflective or non-reflective decorative features, has myriad
possibilities. In a preferred embodiment, the reflective or
non-reflective feature comprises an image. The image may vary
widely, but may include, for example, a geometric image or shape,
alphanumeric characters, microimages, microprint (2 pt font size or
smaller, height less than about 400 .mu.m, e.g., less than about
300 .mu.m, less than about 200 .mu.m or less than about 100 .mu.m),
a personal image (e.g., image of an individual), photograph,
fingerprint, design, barcode, logo, trademark, pattern, e.g.,
guilloche pattern or rosette pattern, or other object. In a
preferred embodiment, the reflective or non-reflective features
exhibit variable information, as discussed in greater detail
below.
[0056] In a preferred embodiment, the first reflective or
non-reflective element (as well as the first ink used to form the
first element) is disposed exclusively on the first region. As the
second reflective or non-reflective element is optionally more
adherent than the first reflective element to the second region,
this embodiment minimizes the potential for beading, smearing,
over-saturation and/or overall poor adhesion that would likely
occur if the first element (or a portion thereof) was formed on the
second region. Forming the first element exclusively on the first
region, therefore, contributes to the desired reflectivity and/or
appearance of the overall reflective or non-reflective feature.
[0057] Similarly, in a preferred embodiment, the second reflective
or non-reflective element (as well as the second ink used to form
the second reflective or non-reflective element) is disposed
exclusively on the second region. As the first element is more
adherent than the second element to the second region, this
embodiment minimizes the potential for beading, smearing,
over-saturation and/or overall poor adhesion that would likely
occur if the second element (or a portion thereof) was formed on
the first region. Disposing the second element exclusively on the
second region, therefore, contributes to the desired reflectivity
and/or desired appearance of the overall reflective or
non-reflective feature.
[0058] The reflective or non-reflective features of the invention,
e.g., reflective or non-reflective security features or reflective
or non-reflective decorative features, are not limited to being
formed on substrates having two regions (e.g., two surfaces) with
different surface characteristics. In one embodiment, the substrate
further comprises a third region, the reflective or non-reflective
feature further comprising a third reflective or non-reflective
element disposed on the third region, wherein the third element (as
well as the ink used to form the third element) is more adherent
than the first element or the second element to the third region.
The presence of a third element disposed on a third region improves
the ability to reliably authenticate an item such as, e.g., a
banknote if such an item comprises a substrate comprising a first
region, a second region, and a third region. As discussed below,
the ability to form reflective or non-reflective elements on
different substrate surfaces, while maintaining a uniform overall
appearance of the reflective or non-reflective feature among the
several elements, is a particularly useful aspect of the present
invention, as it is difficult to reproduce such reflective or
non-reflective features. Of course, substrates having more than
three regions may also be employed.
[0059] In one embodiment, as indicated above, the first and/or
second elements are reflective. Preferably, in this aspect, the
first reflective element and/or the second reflective element are
specularly reflective or mirror-like. Specularly reflective
elements in general are desirable because they are readily
identifiable, yet generally difficult to form and, therefore, to
reproduce, for example, even with a sophisticated color
photocopier. Preferably, the reflective feature of this aspect of
the present invention comprises a first reflective element
comprising metallic nanoparticles. Additionally or alternatively,
the second reflective element comprises metallic nanoparticles. The
use of metallic nanoparticles to form the first and/or second
reflective features is also desirable in that inks comprising
metallic nanoparticles may be deposited using direct write printing
processes, e.g., ink jet printing, to form the reflective elements,
and in particular, to form reflective features comprising variable
information, as discussed below. Further, metallic nanoparticles
have been found to impart highly reflective properties to the
reflective features. Thus, this embodiment provides two aspects
that are difficult to reproduce and, therefore, can function to
verify the authenticity of an item. The first aspect that is
difficult to reproduce is forming a reflective feature disposed on
different regions of a substrate having different surface
characteristics. The second aspect that is difficult to reproduce
is the highly reflective nature of reflective elements comprising
metallic nanoparticles.
[0060] In those embodiments in which the features are reflective,
the reflective features, e.g., reflective security features or
reflective decorative features, preferably comprise metallic
nanoparticles. If present, the nanoparticles optionally are in the
form of a continuous reflective film, which may be formed through
removal of the liquid phase, e.g., ink vehicle, and/or through
post-deposition treating, e.g., curing. If the reflective features
comprise metallic nanoparticles, a majority (e.g., at least 50%, at
least 70%, at least 85% or at least 95%) of the metallic
nanoparticles optionally are necked with at least one adjacent
metallic nanoparticle in the continuous film. By necking it is
meant that adjacent particles are physically connected to one
another through a necking region, while retaining at least some
recognizable degree of their original, e.g., spherical, form. The
degree of necking will vary widely depending, for example, on the
composition (and melting point) of the nanoparticles and on the
treating, e.g., curing, conditions employed in forming the
reflective features. In another embodiment, a majority (e.g., at
least 50%, at least 70%, at least 85% or at least 95%) of the
metallic nanoparticles are independent from (meaning not necked
with) any adjacent nanoparticles in the continuous film.
[0061] In one embodiment, the reflective or non-reflective feature,
is disposed, e.g., positioned, formed or printed, over an
underlying element (e.g., an underlying image, optionally an
underlying reflective image), the underlying element preferably
being at least partially visible through the feature when viewed at
one angle (for example, if the reflective or non-reflective feature
is translucent or has gaps in it through which one can view the
underlying element). The underlying element may become obscured,
however, when viewed from another angle, relative to the surface of
the feature. The effect of obscuring an underlying element is
further described in co-pending U.S. patent application Ser. No.
11/331,233, filed Jan. 13, 2006, entitled "Reflective features,
Their Use and Processes for Making Them," the entirety of which is
incorporated herein by reference. Optionally, the underlying
element comprises metallic particles, e.g., metallic
nanoparticles.
[0062] In another embodiment, an overlying element (e.g., an
overlying image, optionally an overlying reflective image) is
disposed over, e.g., on top of, the first and/or second reflective
or non-reflective elements. Optionally, the overlying element is
clearly visible when viewed from one angle (a first angle) and the
overlying reflective or non-reflective element is at least
partially obscured when viewed from another angle (a second angle).
Optionally, the overlying element comprises metallic particles,
e.g., metallic nanoparticles.
[0063] In one embodiment of the present invention, the first
reflective or non-reflective element and the second reflective or
non-reflective element form a continuous graphical feature that
spans at least a part of the first region and at least a part of
the second region. As used herein, the term "graphical feature" is
meant to refer to the overall shape or outline of the reflective or
non-reflective feature. As use herein, the term "continuous" is
meant to refer to a single, discreet, connected object or part of
an object, optionally formed from one or more inks, substantially
free of gaps. Non-limiting examples of graphical features of the
present invention include any geometric image or shape, one or more
alphanumeric characters, microimages, microprint (2 pt font size or
smaller, height less than about 400 .mu.m, e.g., less than about
300 .mu.m, less than about 200 .mu.m or less than about 100 .mu.m),
image, personal image (e.g., image of an individual), photograph,
fingerprint, design, barcode, logo, trademark, pattern, e.g.,
guilloche pattern or rosette pattern, or other object.
Additionally, the first reflective or non-reflective element and
the second reflective or non-reflective element optionally form a
continuous graphical feature that extends across the interface
between the first region and the second region of a substrate to
form a continuous graphical feature that is difficult to reproduce,
and may serve to authenticate an item. FIG. 3, discussed below,
provides an example of a continuous graphical feature in which the
letter "A" extends continuously across the interface 11 between
first region 12 and second region 13. This embodiment is
particularly desirable for security applications if the first and
second regions exhibit substantially different surface
characteristics, as it is difficult to form a continuous graphical
feature, having a single uniform appearance, extending across
regions having substantially different surface characteristics.
FIGS. 1 and 2, discussed below, provide examples of non-continuous
graphical reflective feature having a first reflective or
non-reflective element 7 comprising the numbers "01" and a second
reflective or non-reflective element 8 comprising the numbers
"234," the second reflective or non-reflective element 8 being
separate from the first reflective or non-reflective element 7, but
forming a single reflective or non-reflective graphical
feature.
[0064] The substrate, as well as the compositions forming the first
and second regions thereof, may vary widely. In one embodiment, the
substrate is selected from the group consisting of a banknote, a
brand authentication tag, a tax stamp, an ID document, an alcoholic
bottle, and a tobacco product. Optionally, the first region and/or
the second region of the substrate may comprise foil, film,
UV-coated lacquer, paper, polymer, coated paper, or printed paper.
In terms of composition, the substrate optionally comprises one or
more of the following: a fluorinated polymer, polyimide, epoxy
resin (including glass-filled epoxy resin), polycarbonate,
polyester, polyethylene, polypropylene, bi-oriented polypropylene,
mono-oriented polypropylene, polyvinyl chloride, ABS copolymer,
wood, paper, metallic foil, glass, banknotes, linen, labels (e.g.,
self adhesive labels, etc.), synthetic paper, flexible fiberboard,
non-woven polymeric fabric, cloth and other textiles. Other
particularly advantageous substrates and substrate surfaces include
cellulose-based materials such as wood, paper, cardboard, or rayon,
and metallic foil and glass (e.g., thin glass). In another
embodiment, the substrate comprises a perforated or non-perforated
Teslin.TM. film or coating, a strong hydrophobic synthetic film or
coating manufactured by PPG Industries, Inc.
[0065] The compositions employed to form the substrate regions may
vary widely. In one embodiment, the composition of the substrate
forms a substrate region. In another embodiment, a separate coating
or material forms a substrate region. Non-limiting examples of
compositions that may employed to form the regions and surfaces of
the present invention, in addition to those provided above, include
foil, film, UV-coated lacquer, paper, coated paper, polymer, and
printed paper. In one embodiment, the reflective or non-reflective
feature of the present invention comprises a substrate comprising a
first region comprising a composition selected from the group
consisting of foil, film, UV-coated lacquer, paper, coated paper,
polymer, and printed paper. The second region similarly may
comprise a composition selected from the group consisting of foil,
film, UV-coated lacquer, paper, coated paper, polymer, and printed
paper (so long as it is a different composition than the first
region).
[0066] In one embodiment, the reflective or non-reflective feature
of the present invention comprises a substrate having a first
region comprising a first undercoat. The first undercoat optionally
comprises a composition selected from the group consisting of
varnishes, offset varnishes, dry offset varnishes, shellacs,
latexes, and polymers. As used herein, the term "undercoat" refers
to a coating disposed underneath a reflective or non-reflective
element and on top of a supporting substrate. If the first region
comprises a first undercoat, the first reflective element (in those
aspects in which the first element is reflective), which is
disposed on the first undercoat of the first region, exhibits
enhanced reflectivity relative to the reflectivity of the first
reflective element in the absence of the first undercoat. The
presence of the undercoat may also facilitate adhesion and
durability of the first reflective or non-reflective element.
[0067] In a similar embodiment, optionally in addition to employing
a first undercoat, the second region optionally comprises a second
undercoat. As explained above, the first and second regions of this
embodiment of the present invention have different surface
characteristics, and in this embodiment the formulation of the
first undercoat creates the characteristics of the first region,
and the formulation of the second undercoat creates the
characteristics of the second region. Preferably, with the second
region comprising the second undercoat, the second reflective
element (in those aspects in which the second element is
reflective) exhibits enhanced reflectivity relative to the
reflectivity of the second reflective element in the absence of the
second undercoat.
[0068] In one embodiment, the reflective or non-reflective feature
of the present invention further comprises an overcoat, e.g., a
first overcoat, disposed on the first reflective or non-reflective
element. The overcoat optionally comprises a composition selected
from the group consisting of varnishes, offset varnishes, dry
offset varnishes, shellacs, latexes, and polymers. Preferably, if
the first element is reflective, the first overcoat disposed on the
first reflective element causes the first reflective element to
exhibit enhanced reflectivity relative to the reflectivity of the
first reflective element in the absence of the first overcoat. In
addition, with the first overcoat disposed on the first reflective
or non-reflective element, the first reflective or non-reflective
element preferably exhibits enhanced durability relative to the
durability of the first element in the absence of the first
overcoat. In this embodiment, for example, the overcoated first
reflective or non-reflective element preferably adheres
sufficiently to the first region to rate a score of 2 or greater, 3
or greater, 4 or greater, or 5 on the ASTM rub test D-5264D92. The
overcoated first element on the first region also preferably passes
the Scotch tape test, discussed above.
[0069] Optionally, the first overcoat also is disposed on the
second reflective or non-reflective element. Preferably, if the
second element is reflective, the first overcoat disposed on the
second reflective element causes the second reflective element to
exhibit enhanced reflectivity relative to the reflectivity of the
second reflective element in the absence of the first overcoat. In
addition, with the first overcoat disposed on the second reflective
or non-reflective element, the second reflective or non-reflective
element preferably exhibits enhanced durability relative to the
durability of the second element in the absence of the first
overcoat. In this embodiment, for example, the overcoated second
element preferably adheres sufficiently to the second region to
provide a score of 2 or greater, 3 or greater, 4 or greater, or 5
on the ASTM rub test D-5264D92. The overcoated second element on
the second region also preferably passes the Scotch tape test,
discussed above.
[0070] Optionally, the reflective or non-reflective feature further
comprises a second overcoat disposed on the second reflective
element. Preferably, if the second element is reflective, the
second overcoat disposed on the second reflective element causes
the second reflective element to exhibit enhanced reflectivity
relative to the reflectivity of the second reflective element in
the absence of the second overcoat. In addition, with the second
overcoat disposed on the second reflective or non-reflective
element, the second element preferably exhibits enhanced durability
relative to the durability of the second element in the absence of
the second overcoat. Optionally, the reflective or non-reflective
feature comprises a second overcoat disposed on the second
reflective or non-reflective element, but the feature does not
include a first overcoat (i.e., a separate overcoat covering any
portion of the first reflective element).
[0071] FIG. 1 illustrates a substrate 1 comprising a first region 2
and a second region 3. The first region 2 has a first surface 4 and
an interface surface 6, which acts to support the second region 3.
The second region 3 that is supported on interface surface 6 has a
second surface 5. The compositions of the first region 2 and the
second region 3 may vary widely. As a non-limiting example, the
first region 2 could comprise linen (e.g., in a bank note) and the
second region 3 could comprise a metallic foil disposed on top of
and adhered to the linen. Importantly, the first surface 4 and the
second surface 5 have different surface characteristics, meaning
they have different properties that affect the level of adherence
of a substance (e.g., an ink) to their respective surfaces.
[0072] In the linen/foil example provided above, the different
surface characteristics may comprise different porosities. The
linen may, for example, be substantially more porous than the foil.
Also, the different surface characteristics may comprise different
degrees of hydrophilicity; for example, the linen may be more
hydrophilic than the foil (which may be hydrophobic). These
different surface characteristics may render the two surfaces
intolerant to receiving a single type of ink because a single ink
may not possess properties that are compatible with both surfaces.
That is, depending on the degree of the difference between the two
surface characteristics, a single ink may not possess attributes
that render it suitable for printing on both first surface 4 and
second surface 5. A single ink may, however, be suitable for one
surface, but not the other.
[0073] FIG. 1 also illustrates a single non-continuous reflective
or non-reflective feature comprising the numbers "01234" disposed
on substrate 1. The feature comprises a first reflective or
non-reflective element 7 and a second reflective or non-reflective
element 8. Specifically, the first element 7 comprises the numbers
"01", and the second element 8 comprises the numbers "234".
Semantically, the number "1" (disregarding the number "0") also
could be considered a first element since it is disposed on the
first region 2, and the number "2" (disregarding the numbers "34")
could be considered a second element since it is disposed on the
second region 3. According to this embodiment of the present
invention, the first element 7 (however characterized) is more
adherent to the first region 2, e.g., the first surface 4 of the
first region 2, than the second element 8 would be if it were
formed on first surface 4 of first region 2. Similarly, the second
element 8 ideally is more adherent to the second region 3, e.g.,
the second surface 5 of the second region 3, than the first element
7 would be if it were formed on second surface 5 of second region
3.
[0074] Although it is contemplated that the optical properties
(e.g., color, hue and reflectivity) of the first reflective or
non-reflective element 7 may differ from the optical properties of
the second reflective or non-reflective element 8, preferably the
optical properties of the first element 7 are substantially the
same as the optical properties of the second element 8 such that
together the two elements form a single reflective or
non-reflective feature (e.g., the number "01234" in FIG. 1) that
has a uniform overall appearance to an observer. That is,
preferably the two elements appear to have similar or substantially
the same optical properties such that the two elements appear to a
lay observer to have been formed from a single ink. Desirably, the
formation of a single reflective or non-reflective feature having
an overall uniform appearance on a substrate having multiple
regions with different surface characteristics is very difficult to
reproduce for would-be counterfeiters.
[0075] The reflective or non-reflective feature shown in FIG. 1 may
be formed, for example, by depositing, e.g., printing, a first ink
on first surface 4 and optionally treating, e.g., curing, the
deposited first ink under conditions effective to form the first
reflective or non-reflective element 7, and by depositing, e.g.,
printing, a second ink on second surface 5 and optionally treating,
e.g., curing, the deposited second ink under conditions effective
to form the second reflective or non-reflective element 8.
Optionally, the first and second inks are deposited and then
treated, e.g., cured, in a single step. The first ink preferably is
more adherent to the first region 2, e.g., the first surface 4 of
the first region 2, than the second ink would be if it were
deposited on first surface 4 of first region 2. Similarly, The
second ink preferably is more adherent to the second region 3,
e.g., the second surface 5 of the second region 3, than the first
ink would be if it were deposited on second surface 5 of second
region 3. In various embodiments, the first ink may be deposited
before, after, simultaneously with or substantially simultaneously
with deposition of the second ink.
[0076] FIG. 2 illustrates another embodiment of the present
invention similar to the one described above with reference to FIG.
1, but in which the substrate 1 comprises a first region 9 (having
first surface 12) situated adjacent second region 10 (having second
surface 13), rather than having one of the regions disposed on top
of another region, e.g., a foil disposed on top of an underlying
linen supporting substrate. As in FIG. 1, the first surface 12 and
the second surface 13 preferably have different surface
characteristics. The two regions are connected, e.g., adhered, to
one another at interface 11.
[0077] FIG. 3 illustrates another embodiment of the present
invention in which the reflective or non-reflective feature
comprises a first reflective or non-reflective element 14, which
forms the left portion of the letter "A", and a second reflective
or non-reflective element 15, which forms the right portion of the
letter "A". This feature comprises a continuous graphical feature
spanning both the first region and the second region of a
substrate. That is, together, the first and second reflective
elements 14, 15 form a single continuous reflective or
non-reflective feature that extends across interface 11 unlike the
reflective feature "01234" shown in FIGS. 1 and 2, which comprises
elements ("01" and "234") that are non-continuous (e.g., separate)
with respect to one another.
[0078] FIG. 4 shows an intermediate feature that may be formed
during the fabrication of the feature shown in FIG. 3. As with the
embodiment shown in FIGS. 1 and 2, the first reflective or
non-reflective element 14 and the second reflective or
non-reflective element 15 shown in FIG. 3 preferably are formed
from a first ink and a second ink, respectively, the inks being
suited for deposition, e.g., printing, onto the first substrate
surface 12 and the second substrate surface 13, respectively. As
discussed above, the first ink may be deposited before, after,
simultaneously with or substantially simultaneously with deposition
of the second ink. The intermediate feature shown in FIG. 4 would
be formed after deposition of the first ink to form the first
reflective or non-reflective element 14, but prior to deposition of
a second ink to form the second reflective or non-reflective
element 15 (the right portion of the letter "A") shown in FIG.
3.
Processes for Forming Features on Regions of a Substrate Having
Different Surface Characteristics
[0079] In another embodiment, the invention is to a process for
forming a reflective feature, e.g., any of the features shown in
FIGS. 1-4, the process comprising the steps of: providing a
substrate comprising a first region and a second region, the two
regions preferably having different surface characteristics from
one another; direct write printing, e.g., ink jet printing
(piezo-electric, thermal ink jet, drop-on-demand or continuous ink
jet (CIJ) printing), a first ink onto the first region to form a
first reflective element; and direct write printing, e.g., ink jet
printing (piezo-electric, thermal, drop-on-demand or continuous ink
jet printing), a second ink onto the second region to form a second
reflective element, wherein the first ink is more adherent than the
second ink to the first region. Ideally, the second ink is more
adherent than the first ink to the second region.
[0080] Optionally, the substrate further comprises a third region
having a different surface characteristics than either the first
region or the second region, and the process further comprises the
step of direct write printing, e.g., ink jet printing
(piezo-electric, thermal, drop-on-demand ink jet, or continuous ink
jet (CIJ) printing), a third ink onto the third region to form a
third reflective element, and wherein the third ink is more
adherent than the first ink or the second ink to the third region.
Of course, more than three inks may be used to form, for example,
more than three reflective elements, as discussed above.
[0081] The process optionally includes steps of treating, e.g.,
curing, the deposited inks (e.g., one or more of the first, second
and/or optional third ink) so as to facilitate removal of the
liquid components of the inks (e.g., vehicles) and convert the
deposited inks to a highly robust, durable reflective features. The
treating optionally comprises simply allowing the deposited ink or
inks to dry. In this embodiment, the vehicle in the deposited inks
is allowed to vaporize (with or without application of one or more
of heat, pressure, IR radiation and/or UV radiation) into the
atmosphere to form the feature, e.g., security or decorative
feature. After drying, the nanoparticles yielded from the inks
during drying have a relatively high degree of reflectivity,
meaning the nanoparticle film or layer formed from the ink or inks
possesses a high degree of optical smoothness (e.g., having a
surface roughness less than 100 nm). With optional subsequent
additional treating steps, e.g., heating, rolling, pressing, UV
curing, IR curing, etc., the reflectivity increases, meaning that
the optical smoothness of the nanoparticle film or layer (e.g., the
first reflective element and/or the second reflective element) is
increased relative to the reflectivity in the case of just allowing
the deposited ink to dry without an additional treating step. If
the inks include metallic nanoparticles, the treating may also
allow adjacent nanoparticles to sinter or neck with one another so
as to provide increased reflectivity and durability. Surface
roughness of the feature (e.g., the first and second reflective
elements thereof) after curing by one or more of heating, rolling,
pressing, UV curing, or IR curing, may be on the order of 50 nm or
less. Thus, depending on how the deposited inks are treated, the
feature optionally comprises first and/or second reflective
elements comprising the nanoparticles, the first and/or second
elements having a route mean square surface roughness that is less
than about 100 nm, less than about 75 nm or less than about 50 nm.
In one embodiment, the deposited first and second inks may be cured
in a single treating step (after deposition of the inks) or in
multiple treating steps, e.g., a first ink may be deposited and
then cured, followed by deposition of a second ink and curing of
the second ink.
[0082] If one or more of the inks comprise reflective
nanoparticles, e.g., metallic nanoparticles, after drying, the
nanoparticles yielded from the inks during drying preferably have a
relatively high degree of reflectivity, meaning the nanoparticle
film or layer formed from the ink or inks possesses a high degree
of optical smoothness (e.g., having a surface roughness less than
100 nm). With optional subsequent additional treating steps, e.g.,
heating, rolling, pressing, UV curing, IR curing, etc., the
reflectivity increases, meaning that the optical smoothness of the
nanoparticle film or layer (e.g., the first reflective element
and/or the second reflective element) is increased relative to the
reflectivity in the case of just allowing the deposited ink to dry
without an additional treating step. If the inks include metallic
nanoparticles, the treating may also allow adjacent nanoparticles
to sinter or neck with one another so as to provide increased
reflectivity and durability.
[0083] In yet another embodiment, the invention is to a process for
forming a printed feature (which might not be reflective), e.g.,
any of the printed features shown in FIGS. 1-4, the process
comprising the steps of: providing a substrate comprising a first
region and a second region, the two regions preferably having
different surface characteristics from one another; printing, e.g.,
direct write printing (ink jet printing such as piezo-electric,
thermal ink jet, drop-on-demand or continuous ink jet (CIJ)
printing), a first ink onto the first region to form a first
printed element; and printing, e.g., direct write printing (ink jet
printing such as piezo-electric, thermal, drop-on-demand or
continuous ink jet printing), a second ink onto the second region
to form a second printed element, wherein the first ink is more
adherent than the second ink to the first region. Ideally, the
second ink is more adherent than the first ink to the second
region. This process may be used to form non-reflective features,
for example, by employing non-metallic inks, e.g., first and/or
second inks, comprising conventional colorants (e.g., pigments or
dyes).
[0084] Optionally, the substrate further comprises a third region
having a different surface characteristics than either the first
region or the second region, and the process further comprises the
step of direct write printing, e.g., ink jet printing
(piezo-electric, thermal, drop-on-demand ink jet, or continuous ink
jet (CIJ) printing), a third ink onto the third region to form a
third printed element (which might not be reflective), and wherein
the third ink is more adherent than the first ink or the second ink
to the third region. Of course, more than three inks may be used to
form, for example, more than three printed elements, as discussed
above.
[0085] This process, like the process described above for forming
reflective features, optionally further includes steps of treating,
e.g., curing, the deposited inks (e.g., one or more of the first,
second and/or optional third ink) so as to facilitate removal of
the liquid components of the inks (e.g., vehicles) and convert the
deposited inks to a highly robust, durable reflective or
non-reflective features. The treating optionally comprises simply
allowing the deposited ink or inks to dry. In this embodiment, the
vehicle in the deposited inks is allowed to vaporize (with or
without application of one or more of heat, pressure, IR radiation
and/or UV radiation) into the atmosphere to form the feature, e.g.,
security or decorative feature.
[0086] Surface roughness of the reflective or non-reflective
feature (e.g., the first and second reflective or non-reflective
elements thereof) after curing by one or more of heating, rolling,
pressing, UV curing, or IR curing, may be on the order of 50 nm or
less. Thus, depending on the ink compositions and on how the
deposited inks are treated, the feature optionally comprises first
and/or second reflective or non-reflective elements (which may or
may not comprise nanoparticles), the first and/or second elements
having a route mean square surface roughness that is less than
about 100 nm, less than about 75 nm or less than about 50 nm. In
one embodiment, the deposited first and second inks may be cured in
a single treating step (after deposition of the inks) or in
multiple treating steps, e.g., a first ink may be deposited and
then cured, followed by deposition of a second ink and curing of
the second ink.
[0087] The utilization of direct write printing to form the
reflective or non-reflective features of the present invention is
highly desirable in that it provides the ability to create features
that comprise variable information, meaning information that is
individualized for a product unit, such as, but not limited to,
serialized data. For example, a serial number is one non-limiting
type of variable information. Other types of variable information
include: counters, lettering, sequential symbols, alphanumeric
variable information, non-serialized variable information (variable
information that is not sequential), and combinations thereof.
Thus, in one embodiment, the reflective or non-reflective feature,
e.g., reflective or non-reflective security feature or reflective
or non-reflective decorative feature, comprises, exhibits or
displays variable information.
[0088] In addition to being able to individualize a document, tag,
etc., the ability to incorporate variable information in a feature,
e.g., reflective feature, provides even further anti-counterfeiting
measures not recognized or available until now. For even further
increased security, the feature optionally comprises variable
information such as a serial number comprising a plurality of
numbers, where at least one of the numbers is disposed or printed
on the first surface of the first region with a first ink, and at
least one of the numbers is disposed or printed on the second
surface of the second region with a second ink. In effect, a serial
number comprises multiple numbers, each of which may be
characterized as a separate element of the feature, at least two
numbers of which are formed from different inks specifically suited
for different surfaces.
[0089] As indicated above, the reflective or non-reflective
features preferably are formed from multiple inks, each ink
preferably being formulated to optimally adhere to a given
substrate surface (e.g., first or second surface of first or second
regions, respectively) and form a different reflective or
non-reflective element. Unlike the adherence test discussed above
for determining the level of adherence of a solid reflective
element onto a substrate region, the ability of a fluid ink to
adhere to a substrate surface may be characterized by the contact
angle formed between a respective ink droplet and the surface on
which the ink is deposited, e.g., printed. As used herein, the term
"contact angle" means the angle at which a liquid/vapor interface
meets the substrate surface (e.g., first surface or second
surface). The contact angle, .theta., of an ink with a surface is
determined primarily by the interfacial energies of the materials
involved, as related by the equation:
.gamma..sub.sv.gamma..sub.sl+.gamma..sub.lv cos .theta.
where .gamma..sub.sv is solid-vapor interfacial energy,
.gamma..sub.sl is solid-liquid interfacial energy, and
.gamma..sub.lv is liquid-vapor interfacial energy. For purposes of
the present specification and appended claims, the contact angle is
determined by using a Kruss Goniometer and measuring the static
contact angle for relatively smooth surfaces and dynamic contact
angles for Blighty rough surfaces.
[0090] Generally, if the contact angle is less than about
90.degree., the ink is considered "wetting" and desirably can
spread on the surface. For the liquid to completely wet the
surface, the contact angle should approach zero. For spreading to
occur, the surface energy of the solid must be greater than the
combination of the surface tension of the liquid and the
interfacial tension between the solid and the liquid. Although
there are exceptions, generally speaking, the more adherent
(wetting) an ink is to a particular substrate region, the more
adherent the resulting reflective or non-reflective element will be
to that substrate region.
[0091] FIG. 5 illustrates the contact angle, .theta..sub.1, for an
ink droplet 16 that exhibits good wetting characteristics on
substrate surface 17. Desirable wetting characteristics are
reflected by an ink having a contact angle with a certain substrate
surface that is less than 90.degree., preferably less than about
75.degree., more preferably less than about 45.degree., or less
than about 30.degree.. A contact angle of greater than 90.degree.
is generally indicative of a non-wetting ink. FIG. 6 illustrates a
non-wetting ink droplet 18 on substrate surface 17 with a contact
angle, .theta..sub.2, that is greater than 90.degree..
[0092] In a preferred embodiment, after deposition (e.g.,
printing), the first ink on first region, e.g., first surface of
the first region, preferably has a contact angle less than
90.degree. (is wetting), e.g., less than about 75.degree., less
than about 45.degree., less than about 30.degree., and most
preferably from about 1.degree. to about 20.degree.. Optionally,
the second ink on second region, e.g., second surface of the second
region, preferably has a contact angle less than 90.degree. (is
wetting), e.g., less than about 75.degree., less than about
45.degree., less than about 30.degree., and most preferably from
about 1.degree. to about 20.degree.. Hereinafter, the contact angle
of the first ink with the first region (e.g., first surface
thereof) is referred to as the first contact angle, and the contact
angle of the second ink with the second region (e.g., second
surface thereof) is referred to as the second contact angle.
[0093] As indicated above, the first ink preferably is more
adherent than the second ink to the first region, e.g., the first
surface of the first region. By "more adherent" it is meant that
the first contact angle is less than (optionally by at least about
5.degree., at least about 10.degree., at least about 20.degree., at
least about 30.degree., at least about 45.degree., at least about
60.degree. or at least about 80.degree.) the contact angle that
would be created if the second ink were deposited on the first
region, e.g., on the first surface of the first region. Conversely,
it has been indicated that the second ink preferably is more
adherent than the first ink to the second region, e.g., the second
surface of the second region. By this it is meant that the second
contact angle is less than (optionally by at least about 5.degree.,
at least about 10.degree., at least about 20.degree., at least
about 30.degree., at least about 45.degree., at least about
60.degree. or at least about 80.degree.) the contact angle that
would be created if the first ink were deposited on the second
region, e.g., on the second surface of the second region.
[0094] Many properties of inks and substrates will impact the
contact angle that is created therebetween. By way of non-limiting
examples, wetting characteristics, porosity, surface energy,
charge, bonding and hydrophilicity/hydrophobicity are surface
characteristics that may affect the level of adherence of a
substance to a surface. Properties of inks used to form the
reflective or non-reflective features of the invention that may
impact the level of adherence to a given substrate surface include
surface tension, hydrophilicity/hydrophobicity, charge, viscosity,
and vapor pressure.
[0095] Inks may be modified to provide the desired physical
characteristics that render them suitable for deposition on a
specific region by a variety of different methods. As one example,
the surface tension and hydrophilicity/hydrophobicity of an ink may
be modified by adding or reducing the amount of surfactant
contained in the ink. In another embodiment, the relative amounts
and types of vehicles employed in the ink may be modified to arrive
at an ink having the desired surface tension,
hydrophilicity/hydrophobicity, viscosity and vapor pressure. In
another embodiment, one or both the first region and the second
region are treated, e.g., by laser-treating, chemical treating,
e.g., with ozone, to improve the adherence of the first and second
inks, respectively, thereto.
[0096] The inks used to form the reflective or non-reflective
elements may comprise a variety of different compositions. In
various embodiments, an ink used to form a reflective or
non-reflective element may comprise one or more of the following:
particulates (preferably metallic nanoparticles if a reflective
element is to be formed), one or more metal precursors (if a
reflective element is to be formed), one or more vehicles,
colorants (e.g., dyes or pigments, particularly in those aspects in
which a non-reflective element is desired), an anti-agglomeration
agent, a reducing agent, one or more additives (such as, but not
limited to surfactants, polymers, biocides, thickeners, binders,
etc.) or other components.
[0097] In a preferred embodiment, for reflective features, either
or both the first ink and/or the second ink as well as the
reflective features formed therefrom comprise metallic
nanoparticles. Thus, in a preferred embodiment, either or both the
first reflective element and/or the second reflective element,
which are formed from the first and second inks, respectively, also
comprise metallic nanoparticles. Preferably, the metallic
nanoparticles in either or both the first reflective element and/or
the second reflective element form a highly reflective film or
films. By "highly reflective," it is meant that the nanoparticles
when formed in a film exhibit at least some degree of non-diffuse
or non-Lambertian reflectivity. That is, the nanoparticle film or
films (as well as the overall features of the invention) preferably
exhibit some degree of specular reflectivity, optionally some
degree of colored specular reflectivity. It is contemplated,
however, that the nanoparticle film(s), the first and/or second
reflective elements and/or the reflective features themselves may
exhibit some degree of diffuse reflectivity, in addition to
specular reflectivity. Reflective elements comprising metallic
nanoparticles have been found to exhibit enhanced reflectivity,
particularly enhanced specular reflectivity, over conventional
features.
[0098] As used herein, the term "metallic nanoparticles" means
particles comprising a metal or metallic characteristic and having
an average particle size of less than about 1 .mu.m. One skilled in
the art would appreciate that there are many techniques for
determining the average particle size of a population of particles,
scanning electron microscopy (SEM) being a particularly preferred
technique. The average particle size of particles smaller than
about 1 .mu.m is also determinable using quasi-elastic light
scattering (QELS) techniques (e.g., using a Malvern.TM.
ZetaSizer.TM.). By "comprising a metal" it is meant all or a
portion of the particles optionally included in the reflective
features of the present invention include, in whole or in part, a
metal (e.g., an elemental metal (zero oxidation state) or a mixture
or alloy of metals) or a metal-containing compound (e.g., a metal
oxide or metal nitride). Thus, in a preferred embodiment, the
optional metallic nanoparticles comprise a component selected from
the group consisting of a metal, a metal alloy, and a
metal-containing compound (e.g., a metal oxide). Additionally or
alternatively, the metallic nanoparticles may comprise a component
having a metallic characteristic. The term "metallic
characteristic" means a reflective or lustrous optical property
similar to a metal. For example, a component may exhibit a metallic
characteristic by virtue of it having a small electronic band
gap.
[0099] As indicated above, the optional metallic nanoparticles have
an average particle size of less than about 1 .mu.m. In another
embodiment, the metallic nanoparticles have an average particle
size of less than about 500 nm, more preferably less than about 250
nm, even more preferably less than about 100 nm, and most
preferably less than about 80 nm. The metallic nanoparticles
optionally have an average particle size greater than about 5 nm,
greater than about 10 nm, greater than about 20 nm, greater than
about 25 nm, greater than about 30 nm, greater than about 40 nm,
greater than about 50 nm, greater than about 100 nm, greater than
about 250 nm or greater than about 500 nm. In terms of ranges, the
metallic nanoparticles optionally have an average particle size in
the range of from about 20 nm to about 1 .mu.m, from about 25 nm to
about 1 .mu.m, from about 30 nm to about 1 .mu.m, from about 40 nm
to about 1 .mu.m, from about 50 nm to about 500 nm, from about 20
nm to about 100 nm, from about 50 nm to about 100 nm, or from about
50 nm to about 80 nm. The metallic nanoparticles may have a
unimodal or multi-modal (e.g., bimodal, trimodal, etc.) particle
size distribution.
[0100] Non-limiting examples of metals for use in the optional
metallic nanoparticles and features of the present invention
include transition metals as well as main group metals such as, for
example, silver, gold, copper, nickel, cobalt, palladium, platinum,
indium, tin, zinc, titanium, chromium, tantalum, tungsten, iron,
rhodium, iridium, ruthenium, osmium, lead and mixtures thereof. The
metallic nanoparticles optionally comprise an alloy comprising at
least two metals being selected from the group consisting of:
silver, gold, copper, nickel, cobalt, palladium, platinum, indium,
tin, zinc, titanium, chromium, tantalum, tungsten, iron, rhodium,
iridium, ruthenium, osmium, and lead. Non-limiting examples of
preferred metals for use in the present invention include silver,
gold, zinc, tin, copper, nickel, cobalt, rhodium, palladium and
platinum--silver, copper and nickel being particularly preferred.
The metallic nanoparticles optionally comprise a metal selected
from the group consisting of silver, gold, zinc, tin, copper,
platinum and palladium (including combinations thereof).
Non-limiting examples of metal-containing compounds or components
that exhibit metallic characteristics and that may be useful as
metallic nanoparticles of the features and inks of the present
invention include metal oxides, metal nitrides, metal carbides
(e.g., titanium nitride or tantalum nitride), metal sulphides and
some semiconductors. The metal-containing compound(s) preferably
have a small electronic band gap that gives rise to metallic
properties or characteristics. A non-limiting list of exemplary
metal oxides includes bronzes such as tungsten bronzes including
hydrogen tungsten oxide, sodium tungsten oxide and lithium tungsten
oxide as well as other bronzes such as phosphor bronzes. Additional
tungsten oxides are described in Published U.S. Patent Application
No. 2005/0271566A1, which published Dec. 8, 2005, the entirety of
which is incorporated herein by reference. In one aspect, the
metallic nanoparticles comprise a mineral having a metallic
characteristic. A non-limiting list of exemplary minerals suitable
for the metallic nanoparticles includes marcasites and pyrites. In
another embodiment, the metallic particles and/or the metallic
nanoparticles comprise an enamel or a glass/metal composite that
provides a metallic characteristic. In one embodiment, the metallic
nanoparticles comprise a pearlescent material and/or an opalescent
material that provides a metallic characteristic.
[0101] The features of the present invention (as well as the inks
used to make, form, print, or create the features of the present
invention) also, in one embodiment, comprise mixtures of two or
more different metallic nanoparticles. In another embodiment, the
features of the present invention comprise metallic nanoparticles
that comprise two or more metals in the form of an alloy or a
mixture of metals or metal containing compounds. Non-limiting
examples of alloys useful as metallic nanoparticles of the
invention include Cu/Zn, Cu/Sn, Ag/Ni, Ag/Cu, Pt/Cu, Ru/Pt, Ir/Pt
and Ag/Co. Optionally, the metallic particles and/or nanoparticles
comprise an alloy such as bronze, tungsten bronzes or brass. Also,
in an embodiment, the metallic nanoparticles have a core-shell
structure made of two different metals such as, for example, a core
comprising nickel and a shell comprising silver (e.g. a nickel core
having a diameter of about 20 nm surrounded by an about 15 nm thick
silver shell). In another embodiment, the core-shell structure may
be comprised of a metal oxide core with another metal oxide
coating. A non-limiting example is a nanoparticle core-shell
structure comprising a mica core and a titania coating. In another
embodiment, the metallic nanoparticles comprise metal-effect
particles and/or pigments. One method for creating metal effect
pigments is to deposit thin layers of one metal oxide or ceramic on
the surface of another (e.g. TiO.sub.2 on mica). Metal-effect
pigments are further described in CENEAR Vol. 81, No. 44, pp. 25-27
(Nov. 3, 2003) (ISSN 0009-2347), the entirety of which is
incorporated herein by reference.
[0102] Metallic nanoparticles that optionally are included in the
inks to form reflective features can be produced by a number of
methods. For example, the metallic nanoparticles may be formed by
spray pyrolysis, as described, for example, in U.S. Provisional
Patent Application No. 60/645,985, filed Jan. 21, 2005, or in an
organic matrix, as described in U.S. patent application Ser. No.
11/117,701, filed Apr. 29, 2005, the entireties of which are fully
incorporated herein by reference. A non-limiting example of one
preferred method of making metallic particles and metallic
nanoparticles, is known as the polyol process, and is disclosed in
U.S. Pat. No. 4,539,041, which is fully incorporated herein by
reference. A modification of the polyol process is described in,
e.g., P.-Y. Silvert et al., "Preparation of colloidal silver
dispersions by the polyol process" Part 1--Synthesis and
characterization, J. Mater. Chem., 1996, 6(4), 573-577; Part
2--Mechanism of particle formation, J. Mater. Chem., 1997, 7(2),
293-299, both disclosures of these documents are fully incorporated
by reference herein. Briefly, in the polyol process a metal
compound is dissolved in, and reduced or partially reduced by a
polyol such as, e.g., a glycol, at elevated temperature to afford
corresponding metal particles. In the modified polyol process, the
reduction is carried out in the presence of a dissolved
anti-agglomeration substance, preferably a polymer, most preferably
polyvinylpyrrolidone (PVP).
[0103] A particularly preferred modification of the polyol process
for producing metallic particles, especially metallic
nanoparticles, is described in co-pending U.S. Patent Applications
Ser. Nos. 60/643,577 filed Jan. 14, 2005, 60/643,629 filed Jan. 14,
2005, and 60/643,578 filed Jan. 14, 2005, and co-pending U.S.
patent applications Ser. No. 11/331,211 filed Jan. 13, 2006, Ser.
No. 11/331,238 filed Jan. 13, 2006, and Ser. No. 11/331,230 filed
Jan. 13, 2006, which are all herein fully incorporated by
reference. See also U.S. patent application Ser. No. 11/755,720
filed May 30, 2007, the entirety of which is incorporated herein by
reference. In a preferred aspect of a modified polyol process, a
dissolved metal compound (e.g., a silver compound such as silver
nitrate) is combined with and reduced by a polyol (e.g., ethylene
glycol, propylene glycol and the like) at an elevated temperature
(e.g., at about 120.degree. C.) and in the presence of a polymer,
preferably a heteroatom-containing polymer such as PVP.
[0104] In some embodiments at least one of the first ink and the
second ink comprises a colorant (e.g., a pigment or dye).
Optionally, at least one of the first ink and the second ink
comprises a colorant (e.g., a pigment or dye), but does not
comprise metallic nanoparticles. This aspect of the invention is
particularly desirable for the formation of non-reflective
features, since conventional colorants do not impart reflective
properties.
[0105] Each of the first and second inks preferably comprises a
vehicle for imparting desired flow characteristics to the ink.
Typically, the vehicles will be carefully selected to provide first
and second ink formulations that possess desirable properties for
interacting with the first and second regions, respectively, on
which they are deposited. Since the surface characteristics of the
first and second regions differ from one another, the vehicles
selected for the first and second inks typically will differ from
one another, whether by type or relative amounts, so as to impart
the desired properties for interacting with the first and second
regions, respectively.
[0106] In those aspects in which the ink comprises metallic
nanoparticles, the vehicle for use in the ink, e.g., direct write,
thermal, piezo-electric or continuous ink jet ink or digital ink,
preferably is a liquid that is capable of stably dispersing the
metallic nanoparticles. For example, vehicles are preferred that
are capable of affording an ink dispersion that can be kept at room
temperature for several days or even one, two, three weeks or
months or even longer without substantial agglomeration and/or
settling of the metallic nanoparticles. To this end, it is also
preferred for the vehicle to be compatible with the surface of the
metallic nanoparticles. It is particularly preferred for the
vehicle to be capable of dissolving the anti-agglomeration
substance, if present, to at least some extent, without removing it
from the metallic nanoparticles. In one embodiment, the vehicle
comprises (or predominantly consists of) one or more polar
components (solvents) such as, e.g., a protic solvent, or one or
more aprotic, non-polar components, or a mixture thereof. The
vehicle, in an embodiment, is a solvent selected from the group
consisting of alcohols, polyols, amines, amides, esters, acids,
ketones, ethers, water, saturated hydrocarbons, unsaturated
hydrocarbons, and mixtures thereof.
[0107] Where the features of the invention are printed, formed or
created through direct-write printing, such as ink-jet printing
e.g., thermal, piezo-electric or continuous ink jet printing, or
digital printing, the vehicle is preferably selected to effectively
work with direct-write printing tool(s), such as, e.g., an ink jet
head, a digital head, and cartridges, particularly in terms of
viscosity and surface tension of the ink composition.
[0108] In a preferred aspect, for piezo-electric ink jet inks
containing metallic nanoparticles, the vehicle comprises a mixture
of at least two solvents, optionally at least two organic solvents,
e.g., a mixture of at least three organic solvents, or at least
four organic solvents. The use of more than one solvent is
preferred because it allows, inter alia, to adjust various
properties of a composition simultaneously (e.g., viscosity,
surface tension, contact angle with intended substrate etc.) and to
bring all of these properties as close to the optimum values as
possible. In one embodiment, the vehicle comprises a mixture of
ethylene glycol, ethanol and glycerol. Non-limiting examples of
vehicles are disclosed in, e.g., U.S. Pat. Nos. 5,853,470;
5,679,724; 5,725,647; 4,877,451; 5,837,045 and 5,837,041, the
entire disclosures of which are incorporated by reference
herein.
[0109] For thermal ink jet inks, the vehicle optionally comprises a
mixture of at least two solvents, optionally at least two organic
solvents, e.g., a mixture of at least three organic solvents, or at
least four organic solvents. The use of more than one solvent is
preferred because it allows, inter alia, to adjust various
properties of a composition simultaneously (e.g., viscosity,
surface tension, contact angle with intended substrate etc.) and to
bring all of these properties as close to the optimum values as
possible--particularly so that the first and second inks,
respectively, are well-suited for deposition onto the first and
second regions, respectively. Preferably, for thermal ink jet
printing applications, the vehicle comprises water, optionally with
one or more other vehicles. In one embodiment, the vehicle
comprises a mixture of propylene glycol and water.
[0110] In a preferred embodiment, particularly for thermal ink jet
printing applications, the vehicle comprises water. For example,
the vehicle optionally comprises at least 30 wt. % water, at least
40 wt. % water, at least 50 wt. % water, at least 60 wt. % water,
or at least 70 wt. % water, based on the total weight of the
vehicle.
[0111] It is desirable to also take into account the requirements,
if any, imposed by the deposition tool (e.g., in terms of viscosity
and surface tension of the ink) and the surface characteristics
(e.g., acidity, hydrophilicity or hydrophobicity) of the intended
substrate in selecting the vehicle of choice. Although the desired
ink viscosity may depend greatly on the specific deposition tool
implemented, inks used to form the features of the present
invention, particularly those intended for ink jet printing with a
piezo head, preferably have a viscosity (measured at 20.degree. C.)
that is not lower than about 2 centipoise (cP), e.g., not lower
than about 12 cP, or not lower than about 15 cP, and optionally not
higher than about 50 cP, e.g., not higher than about 40 cP, not
higher than about 30 cP, or not higher than about 25 cP. In one
embodiment, the ink has a viscosity (measured at 20.degree. C.)
that is greater than about 0.5 cP, e.g., greater than about 1.0 cP,
or greater than about 1.3 cP, and less than about 10 cP, e.g., less
than about 7.5 cP, less than about 5 cP, or less than about 4
cP.
[0112] The vehicle optionally provides the inks with a surface
tension (measured at 20.degree. C.) ranging from about 10 to about
60 dynes/cm, e.g., from about 10 to about 50 dynes/cm or from about
10 to about 40 dynes/cm.
[0113] The inks, e.g., thermal or piezo-electric ink jet inks or
digital inks, in an embodiment can further comprise one or more
additives, such as, but not limited to, adhesion promoters,
rheology modifiers, surfactants, wetting angle modifiers,
humectants, crystallization inhibitors, binders, and the like. The
inks optionally further comprise a protective coating material such
as a lacquer, polymer or a varnish. Such additives are fully
described in co-pending U.S. patent application Ser. No.
11/331,233, previously incorporated herein by reference. Other ink
formulations are provided in co-pending U.S. patent application
Ser. No. 11/331,185, filed Jan. 13, 2006, the entirety of which is
incorporated herein by reference.
[0114] A preferred additive for inclusion in either or both the
first ink and/or the second ink includes surfactants. The amount
and type of surfactant may be carefully controlled so as to provide
first and/or second inks that are well-suited for deposition on the
first and second regions, respectively, of the substrate. The types
of surfactant(s) that may be included in the first and/or second
ink may vary widely. Some non-limiting examples of preferred
surfactants for use in this embodiment of the present invention
include fluoronated surfactants, such as FLUORAD.RTM. (3M),
ZONYL.RTM. (duPont); non-ionic surfactants such as TERGITOL.RTM.,
SURFYNOL.RTM., or siloxanes; and ionic surfactants. Other
surfactants suitable for inclusion in the first and/or second inks
are listed in U.S. Provisional Patent Applications Ser. No.
60/643,577 filed Jan. 14, 2005, 60/643,629 filed Jan. 14, 2005, and
60/643,578 filed Jan. 14, 2005, the entireties of which are
incorporated herein by reference, and in co-pending Non-Provisional
U.S. patent applications Ser. No. 11/331,211 filed Jan. 13, 2006,
Ser. No. 11/331,238 filed Jan. 13, 2006, and Ser. No. 11/331,230
filed Jan. 13, 2006, the entireties of which are incorporated
herein by reference.
Multi-Layered Features
[0115] In another aspect, the present invention is directed toward
a reflective feature comprising a substrate having a first surface;
a first coating disposed on the first surface and having a second
surface; and a reflective element having a third surface and
comprising nanoparticles, preferably metallic nanoparticles,
disposed, at least in part, on the second surface. The first
surface may exhibit a wide range of surface characteristics in
terms of porosity, hydrophilicity/hydrophobicity, acidity, etc. The
primary purpose of the first coating is to planarize and/or reduce
the porosity of the underlying substrate. It has been discovered
that by planarizing and/or reducing the porosity of the substrate
with the first coating, the reflectivity of the subsequently formed
reflective element (preferably comprising metallic nanoparticles)
is greater than it would be in the absence of the first coating.
That is, the reflective feature preferably exhibits enhanced
reflectivity relative to the reflectivity of the reflective feature
in the absence of the first coating.
[0116] In yet another aspect, the present invention is directed
toward a non-reflective printed feature comprising a substrate
having a first surface; a first coating disposed on the first
surface and having a second surface; and a printed element, which
is not necessarily reflective, having a third surface, disposed, at
least in part, on the second surface. The first surface may exhibit
a wide range of surface characteristics in terms of porosity,
hydrophilicity/hydrophobicity, acidity, etc. Again, the primary
purpose of the first coating is to planarize and/or reduce the
porosity of the underlying substrate.
[0117] In one embodiment, the substrate comprises a first surface
comprising two regions having different surface characteristics,
and the first coating covers at least a portion of both regions so
as to provide a uniform (second) surface covering at least a
portion of both regions. Subsequently, a single ink may then be
applied, e.g., printed, onto the uniform (second) surface and over
the two regions so as to form a reflective or non-reflective
element that spans both regions notwithstanding the different
surface characteristics of the two regions. In this embodiment,
rather than providing separate first and second inks for forming
first and second reflective elements, respectively, as described
above with reference to FIGS. 1-4, the coating is formed of a
single material that is capable of adhering to both regions, and a
single ink is then applied, e.g., printed, directly on the first
coating and over both regions.
[0118] The first coating preferably has a porosity less than the
porosity of the substrate and the first surface of the substrate.
In one embodiment, the first coating comprises a material selected
from the group consisting of varnishes, offset varnishes, dry
offset varnishes, shellacs, latexes and polymers. The invention,
however, is not limited to first coatings comprising these
materials, as the first coating may comprise any material that
lowers the porosity or which can planarize the first surface of the
substrate. As the reflective or non-reflective element may be at
least partially semitransparent, a portion of the first coating may
be viewable through the reflective or non-reflective element.
Optionally, the first coating comprises a colorant. By way of
non-limiting examples, the colorant may be a dye or pigment.
Utilizing a colorant affects the appearance of the reflective
feature by changing the apparent color thereof The color of the
substrate when viewed through a first coating comprising a colorant
may differ from the color of the substrate viewed through the first
coating in the absence of a colorant. Additionally, the presence of
the colorant in the first coating may modify the apparent color of
the nanoparticles, if any, contained in the element that is
disposed on top of the first coating. For example, if a yellow
colorant is contained in the first coating, and the element
comprises silver nanoparticles, a reflective feature may be formed
in which the overall reflective feature exhibits a gold metallic
luster, rather than the silver native color of silver
nanoparticles.
[0119] In one embodiment, an element is reflective and comprises
metallic nanoparticles, as fully described above. By way of
non-limiting examples, the metallic nanoparticles may comprise a
metal selected from the group consisting of silver, gold, zinc,
tin, copper, platinum, and palladium, and alloys thereof
Optionally, a majority of the metallic nanoparticles are necked
with at least one adjacent metallic nanoparticle. Optionally, the
average distance between adjacent metallic particles is less than
about 700 nm, e.g., less than about 400 nm, less than about 200 nm,
less than about 100 nm, less than about 30 nm, less than about 10
nm, or less than about 1 nm. Optionally, the metallic nanoparticles
have an average particle size of less than about 200 nm, e.g., less
than about 150 nm, less than about 100 nm, less than about 75 nm or
less than about 50 nm. Preferably, the metallic nanoparticles have
an average particle size of from about 5 nm to about 100 nm. In
another embodiment, the nanoparticles comprise phosphorescent
nanoparticles.
[0120] In one embodiment, the reflective or non-reflective feature
further comprises a second coating having a fourth surface disposed
at least in part on the third surface. By way of non-limiting
examples, the second coating may comprise material selected from
the group consisting of varnishes, offset varnishes, dry offset
varnishes, shellacs, latexes and polymers. Preferably, the second
coating is transparent. As used herein, the term "transparent"
means capable of allowing light to pass therethrough, e.g., through
a translucent layer. The primary purpose of the second coating is
to protect the underlying layers from, for example, moisture, and
everyday wear-and-tear. Additionally, in those aspects in which the
feature is reflective, the second coating may enhance the
reflectivity of the feature if, for example, the fourth surface
possesses specular reflectance. Optionally, the second coating
further comprises a colorant, e.g., a dye, pigment or phosphor,
which modifies the color or photoluminescence of the feature.
[0121] FIG. 7 illustrates an exploded view of a multi-layered
structure of a feature according to this embodiment of the
invention, and FIG. 8 illustrates a non-exploded view of the same
feature. FIGS. 7 and 8 illustrate a substrate 19 having first
surface 20. First surface 20 may be substantially porous or
comprise a rough surface on a microscopic level, the surface
comprising multiple peaks and valleys, as shown in inset 27. A
first coating, which comprises a second surface 22, is disposed on
the first surface 20. As shown in inset 27, the second surface 22
preferably is less porous than the first surface 20 and/or acts to
planarize substrate 19. A reflective or non-reflective element 23,
which has a third surface 24, optionally comprising nanoparticles,
e.g., metallic nanoparticles, is disposed on second surface 22. The
reduced porosity and/or more planar nature of the second surface
relative to the first surface 20 causes the nanoparticles and/or
colorant (e.g., pigment particles) in the reflective or
non-reflective element 23, to be retained on the second surface,
thereby concentrating the nanoparticles and/or colorant in a single
plane. If the ink comprises metallic nanoparticles, this
concentrating of the nanoparticles desirably may enhance
reflectivity. FIGS. 7 and 8 also illustrate optional second coating
25, which comprises fourth surface 26, disposed on second surface
22 of first coating 21 as well as on top of third surface 24 of
reflective or non-reflective element 23. The second coating 25 acts
to protect the reflective or non-reflective element 23 as well as,
in those aspects in which the feature is reflective, provide
enhanced reflectivity to the overall feature.
[0122] Optionally, the feature is highly reflective. In one
embodiment, the reflective element comprises a reflective layer.
The reflective layer optionally is at least partially
semitransparent. As used herein, the term "semitransparent" means
capable of allowing at least some light to pass therethrough, e.g.,
through openings and/or through a translucent layer, while
optionally absorbing a portion of the light. The reflective layer
may also be continuous or non-continuous.
[0123] In another embodiment, the reflective or non-reflective
element comprises a plurality of reflective or non-reflective
images, e.g., a plurality of reflective or non-reflective
microimages having an average largest dimension of less than about
0.5 mm, e.g., less than about 0.4 mm, less than about 0.3 mm, less
than about 0.2 mm, or less than about 0.1 mm. Optionally, at least
one microimage comprises variable data.
[0124] In one embodiment, an image is disposed on at least one of
the first surface or the second surface, and at least a portion of
the image is viewable through a reflective element when viewed at a
first angle relative to the third surface, and at least a portion
of the image is at least partially obscured when viewed from a
second angle relative to the third surface. In this embodiment,
therefore, the reflective element at least partially obscures the
image, depending on the viewing angle. Optionally, the second angle
is about 180.degree. minus the angle of incident light, relative to
the third surface. By way of non-limiting examples, the image may
be formed by direct write printing, intaglio printing, gravure
printing, lithographic printing, and flexographic printing, and, by
way of non-limiting examples, the image may be a black and white
image, a color image, a hologram, a watermark, and a UV fluorescent
image. Optionally, the image is in the form of text or a serial
number.
[0125] In other embodiments, the invention includes the first
coating and the reflective element but not the second coating. In
another embodiment, the invention includes the reflective element
and the second coating disposed thereon, but not the first
coating.
[0126] In other embodiments, the invention includes the first
coating and a printed element (which might not be reflective) but
not the second coating. In another embodiment, the invention
includes the printed element and the second coating disposed
thereon, but not the first coating.
[0127] In one aspect, the invention relates to processes for
forming the above-described multi-layered reflective or
non-reflective features, one process comprising the steps of:
providing a substrate having a first surface; forming, e.g.,
printing, optionally through a direct write printing process, e.g.,
a piezo-electric, thermal, drop-on-demand or continuous ink jet
printing process, a first coating on the first surface, the first
coating having a second surface; and forming, e.g., printing,
optionally through a direct write printing process, e.g., a
piezo-electric, thermal, drop-on-demand or continuous ink jet
printing process, a reflective or non-reflective element on the
second surface, the reflective or non-reflective element having a
third surface optionally comprising nanoparticles, e.g., metallic
nanoparticles. In one embodiment, the reflective or non-reflective
element formed comprises a reflective or non-reflective layer that
is at least partially semitransparent. The reflective or
non-reflective layer may be continuous or non-continuous.
Preferably, if the feature is reflective, the first coating formed
renders the reflective feature formed more reflective than it would
be in the absence of the first coating.
[0128] Optionally, the nanoparticles optionally employed in the
process of the invention comprise metallic nanoparticles.
Optionally, a majority of the metallic nanoparticles in the formed
reflective element are necked with at least one adjacent metallic
nanoparticle. By way of non-limiting examples, the metallic
nanoparticles may comprise a metal selected from the group
consisting of silver, gold, zinc, tin, copper, platinum, and
palladium, and alloys thereof.
[0129] In one embodiment, the step of the forming the first coating
comprises depositing a first ink onto the first surface and
treating the deposited first ink under conditions effective to form
the first coating. The first ink may comprise, for example, a
material selected from the group consisting of a varnish, an offset
varnish, a dry offset varnish, a shellac, latex, and a polymer. In
other embodiments, the first ink comprises a lacquer, an enamel, a
glass, a glass/metal composite, or polymer, which may be applied
(optionally printed). Other non-limiting exemplary substances
useful for inclusion in the first ink include lacquers,
fluorosilicates, fluorinated polymers (e.g., Zonyl products),
shellac (or other similar clear coat technologies), acrylates, UV
curable acrylates, polyurethanes, etc., or a combination thereof.
The first ink optionally is deposited on the first surface by a
printing process selected from the group consisting of direct write
printing (e.g., ink jet (e.g., piezo-electric, thermal,
drop-on-demand or continuous ink jet printing) or digital
printing), intaglio printing, gravure printing, offset printing,
lithographic printing and flexographic printing processes.
Preferably, the depositing comprises direct write printing (e.g.,
ink jet (e.g., piezo-electric, thermal, drop-on-demand or
continuous ink jet printing) or digital printing) the first ink
onto the first surface. In one embodiment, one or more dyes or
pigments are included to the first ink and provide color to the
first coating and ultimately formed feature. See Ernest W. Flick,
Printing Ink and Overprint Varnish Formulations, Recent
Developments (Noyes Publications 1991) (ISBN 0-8155-1259-7), and
Ernest W. Flick, Printing Ink and Overprint Varnish Formulations,
Second Edition (Noyes Publications 1999) (ISBN 0-8155-1440-9), the
entireties of which are incorporated herein by reference, or an
overview of various coating formulations that may be employed for
the first ink. The treating of the deposited first ink preferably
comprises drying, optionally with heating and/or application of UV
radiation to the deposited first ink. Some specific preferred first
ink compositions for forming the first coating include RJE A8070
lacquer medium cvec12414 from Cavalier Inks and Coatings (Richmond,
Va.); CK-49HG-1 and CK-1250 from Cork Industries Inc. (Folcroft,
Pa.); and NiCoat (noncurl 8020) from Gans Ink and Supply Co. (Los
Angeles, Calif.).
[0130] In another embodiment, the step of forming the reflective or
non-reflective element comprises depositing a second ink onto the
second surface and treating the deposited second ink under
conditions effective to form the reflective or non-reflective
element. The composition and properties of the second ink may be as
described above with reference to the inks used to form the
reflective or non-reflective elements of the other features of the
present invention. Optionally, the depositing comprises direct
write printing, e.g., a piezo-electric, thermal, drop-on-demand or
continuous ink jet printing, the second ink onto the second
surface. Optionally, the treating comprises allowing the second ink
to dry, heating the deposited second ink and/or applying UV
radiation to the deposited second ink. In another embodiment, the
treating comprises applying UV radiation to the deposited second
ink.
[0131] In one embodiment, the process further comprises the step of
forming a second coating on the third surface, the second coating
having a fourth surface. Optionally, the second coating is
transparent. In one embodiment, the step of the forming the second
coating comprises depositing a third ink onto the second surface
and treating the deposited third ink under conditions effective to
form the second coating. The third ink may comprise, for example, a
material selected from the group consisting of a varnish, an offset
varnish, a dry offset varnish, a shellac, latex, and a polymer. In
other embodiments, the third ink comprises a lacquer, an enamel, a
glass, a glass/metal composite, or polymer, which may be applied
(optionally printed). Other non-limiting exemplary substances
useful for inclusion in the third ink include lacquers,
fluorosilicates, fluorinated polymers (e.g., Zonyl products),
shellac (or other similar clear coat technologies), acrylates, UV
curable acrylates, polyurethanes, etc., or a combination thereof.
The third ink optionally is deposited on the second surface by a
printing process selected from the group consisting of direct write
printing (e.g., ink jet (e.g., piezo-electric, thermal,
drop-on-demand or continuous ink jet printing) or digital
printing), intaglio printing, gravure printing, offset printing,
lithographic printing and flexographic printing processes.
Preferably, the depositing comprises direct write printing (e.g.,
ink jet (e.g., piezo-electric, thermal, drop-on-demand or
continuous ink jet printing) or digital printing) the third ink
onto the second surface. In one embodiment, one or more dyes or
pigments are included to the third ink and provide color to the
second coating and ultimately formed feature. See Ernest W. Flick,
Printing Ink and Overprint Varnish Formulations, Recent
Developments (Noyes Publications 1991) (ISBN 0-8155-1259-7), and
Ernest W. Flick, Printing Ink and Overprint Varnish Formulations,
Second Edition (Noyes Publications 1999) (ISBN 0-8155-1440-9), the
entireties of which are incorporated herein by reference, or an
overview of various coating formulations that may be employed for
the third ink. The treating of the deposited third ink preferably
comprises drying, optionally with heating and/or application of UV
radiation to the deposited third ink. Some specific preferred third
ink compositions for forming the second coating include RJE A8070
lacquer medium cvec12414 from Cavalier Inks and Coatings (Richmond,
Va.); CK-49HG-1 and CK-1250 from Cork Industries Inc. (Folcroft,
Pa.); and NiCoat (noncurl 8020) from Gans Ink and Supply Co. (Los
Angeles, Calif.).
[0132] In one embodiment, at least one of the first surface or the
second surface has an image disposed thereon and the feature
comprises a reflective element. In this embodiment, at least a
portion of the image preferably is viewable through the reflective
element when viewed at a first angle relative to the third surface,
and at least a portion of the image is at least partially obscured
when viewed from a second angle relative to the third surface. The
reflective element formed by this process, therefore, at least
partially obscures the image, depending on the viewing angle.
Optionally, the second angle is about 180.degree. minus the angle
of incident light, relative to the third surface. By way of
non-limiting examples, the image may be formed from a printing
process selected from the group consisting of direct write
printing, intaglio printing, gravure printing, lithographic
printing, and flexographic printing. By way of non-limiting
examples, the image may be selected from the group consisting of a
black and white image, a color image, a hologram, a watermark, a UV
fluorescent image, text, and a serial number.
[0133] In another embodiment, the reflective or non-reflective
element formed comprises a plurality of reflective or
non-reflective images. In a related embodiment, the reflective or
non-reflective element formed comprises a plurality of reflective
or non-reflective microimages, wherein the plurality of microimages
has an average largest dimension of less than about 0.5 mm.
Optionally, at least one microimage comprises variable data.
[0134] In one aspect, the present invention relates to a reflective
feature comprising a substrate, a reflective element comprising
metallic nanoparticles, and an overcoat comprising a colorant. The
overcoat optionally comprises a material selected from the group
consisting of a material selected from the group consisting of a
varnish, an offset varnish, a dry offset varnish, a shellac, latex,
and a polymer. By way of non-limiting examples, the colorant may be
a dye or pigment. The overcoat comprising the colorant may have the
effect of changing the color of the reflective element and/or the
substrate. For example, a reflective element comprising metallic
nanoparticles that appear silver in the absence of a colorant, may
appear gold if the overcoat comprises a colorant. In a preferred
embodiment, the overcoat is transparent. Although a transparent
overcoat allows light to pass through such that the reflective
element remains visible, the overcoat still may create the effect
of changing the apparent color of the reflective element. In
addition to affecting the apparent color of the reflective element,
the overcoat may have the synergistic effect of protecting the
reflective element, and/or increasing the reflectivity of the
reflective element.
[0135] In another aspect, the present invention relates to a
process for forming a reflective feature, the process comprising
the steps of: providing a substrate; forming a reflective element
comprising nanoparticles, preferably metallic nanoparticles, on the
substrate; and forming an overcoat, optionally comprising a
colorant, on the reflective element. Optionally, the step of
forming the reflective element, preferably comprising the metallic
nanoparticles, comprises direct write printing an ink comprising
the nanoparticles onto the substrate. Optionally, the step of
forming the overcoat comprises direct write printing, e.g., ink jet
printing, an ink, optionally comprising the colorant, onto the
substrate and/or the reflective element. Optionally, the overcoat
comprising a colorant is transparent. The colorant employed in this
process may be selected from virtually any pigment or dye that is
compatible with a direct write printing process.
EXAMPLES
Example 1
Lacquer Undercoat to Form Highly Reflective Feature
[0136] A multi-layer reflective feature comprising a substrate, an
undercoat and a reflective feature was formed. The substrate
comprised glossy Epson photopaper, which was made substantially
non-porous by forming a non-porous lacquer undercoat on the surface
of the paper. The coating was formed by applying RJE A8070 Lacquer
Medium cvec 12414 (Cavalier Inks and Coatings, Richmond, Va.) onto
the Epson photopaper and allowing it to dry.
[0137] An ink comprising silver nanoparticles (average particle
size=20-80 nm) and rhodamine dye was ink jet printed onto the
coated substrate. The ink was ink jet printed onto the
lacquer-coated paper utilizing a Hewlett-Packard thermal ink jet
printing head (Model HP45A cartridge) and allowed to dry. The
printing pattern comprised a repeating pattern of microprinted
numbers (2 Pt. font size or smaller). The ink had the formulation
shown in Table 1, below.
TABLE-US-00001 TABLE 1 SILVER NANOPARTICLE/RHODAMINE INK JET INK
FORMULATION Ingredient Weight Percent Rhodamine 4.3 Silver
Nanoparticles 9.5 Glycerol 16.4 Ethanol 44.0 Ethylene Glycol
25.8
[0138] Visibly, the feature was surprisingly reflective and
unexpectedly exhibited a color shift between a dark red metallic
color and a green metallic color as the viewing angle changed.
Example 2
Lacquer Undercoat to form Highly Reflective Feature
[0139] A multi-layer reflective feature comprising a substrate, an
undercoat and a reflective feature was formed. The substrate
comprised glossy Epson photopaper, which was made substantially
non-porous by forming a non-porous lacquer undercoat on the surface
of the paper. The coating was formed by applying RJE A8070 Lacquer
Medium cvec 12414 (Cavalier Inks and Coatings, Richmond, Va.) onto
the Epson photopaper and allowing it to dry.
[0140] An ink comprising silver nanoparticles (average particle
size=20-80 nm) and basic fuchsin dye was ink jet printed onto the
coated substrate. The ink was ink jet printed onto the
lacquer-coated paper utilizing a Hewlett-Packard thermal ink jet
printing head (Model HP45A cartridge) and allowed to dry. The
printing pattern comprised a repeating pattern of microprinted
numbers (2 Pt. font size or smaller). The ink had the formulation
shown in Table 2, below.
TABLE-US-00002 TABLE 2 SILVER NANOPARTICLE/BASIC FUCHSIN INK JET
INK FORMULATION Ingredient Weight Percent Basic Fuchsin 4.3 Silver
Nanoparticles 9.5 Glycerol 16.4 Ethanol 44.0 Ethylene Glycol
25.8
[0141] Visibly, the feature was surprisingly reflective and
unexpectedly exhibited a color shift between a dark red metallic
color and a green metallic color as the viewing angle changed.
Example 3
Lacquer Overcoat to Form Durable Reflective Feature
[0142] A reflective feature was formed by ink jet printing an ink
comprising silver nanoparticles (average particle size=20-80 nm)
and treating the first layer to form a first coating, and then
forming a second layer comprising a colored lacquer on top of the
first layer. The substrate comprised (uncoated) glossy Epson
photopaper.
[0143] The ink had the formulation shown in Table 3, below.
TABLE-US-00003 TABLE 3 SILVER NANOPARTICLE INK JET INK FORMULATION
Ingredient Weight Percent Silver Nanoparticles 10.0 Glycerol 17.0
Ethanol 46.0 Ethylene Glycol 27.0
[0144] The ink was deposited on the substrate utilizing a
Hewlett-Packard thermal ink jet printing head (Model HP45A
cartridge) and allowed to dry. The printing pattern comprised a
repeating pattern of microprinted numbers (2 Pt. font size). After
drying, a colored lacquer coating was deposited on the surface of
the paper with a draw bar and allowed to dry. The colored coating
was formed by adding rhodamine dye to RJE A8070 Lacquer Medium cvec
12414 (Cavalier Inks and Coatings, Richmond, Va.) to obtain a 5 wt
% rhodamine concentration, based on the total weight of the colored
lacquer coating. The reflective feature formed in Example 3 thus
had two layers, a first silver nanoparticle layer, and a colored
lacquer overcoat disposed thereon. The feature was surprisingly
reflective and appeared to have a lustrous red metallic color. The
feature was also surprisingly durable, exhibiting a rating of 5 on
the ASTM D-5264D92 rub test.
[0145] While the present invention has been described with
reference to exemplary embodiments, it is understood that the words
that have been used are words of description and illustration,
rather than words of limitation. Changes may be made, within the
purview of the appended claims, as presently stated and as amended,
without departing from the scope and spirit of the present
invention in its aspects. Although the invention has been described
herein with reference to particular means, materials, and
embodiments, the invention is not intended to be limited to the
particulars disclosed herein. Instead, the invention extends to all
functionally equivalent structures, methods, and uses, such as are
within the scope of the appended claims.
* * * * *