U.S. patent number RE42,188 [Application Number 12/283,259] was granted by the patent office on 2011-03-01 for security articles.
This patent grant is currently assigned to Honeywell International Inc.. Invention is credited to Samir Z. Abdalla, Jiunn-Yow Chen, Sheldon Kavesh, Alexander Lobovsky, Huy X. Nguyen, Thomas Potrawa, Alfred Siggel, Thomas Y-T. Tam.
United States Patent |
RE42,188 |
Tam , et al. |
March 1, 2011 |
Security articles
Abstract
This invention provides security articles comprising fibers,
threads and fiber sections ("dots") possessing multiple
verification characteristics. The fibers possess unique and
difficulty duplicated combinations of complex cross-sections,
components, and multiple luminescent responses. The many verifiable
characteristics of the security fibers, threads and dots provide
high levels of protection against fraudulent duplication of
articles in which they are incorporated. The manifold security
features provide means of tailoring specific identity
characteristics for specific use and users.
Inventors: |
Tam; Thomas Y-T. (Chesterfield,
VA), Siggel; Alfred (Hanover, DE), Abdalla; Samir
Z. (San Diego, CA), Chen; Jiunn-Yow (Apex, NC),
Potrawa; Thomas (Seelze, DE), Nguyen; Huy X.
(Midlothian, VA), Kavesh; Sheldon (Whippany, NJ),
Lobovsky; Alexander (Westfield, NJ) |
Assignee: |
Honeywell International Inc.
(Morristown, NJ)
|
Family
ID: |
25149465 |
Appl.
No.: |
12/283,259 |
Filed: |
September 10, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
09790041 |
Feb 21, 2001 |
07122248 |
Oct 17, 2006 |
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Current U.S.
Class: |
428/397; 428/399;
428/373; 428/690; 428/374; 428/401; 428/913; 428/402 |
Current CPC
Class: |
D01F
1/04 (20130101); D01D 5/253 (20130101); D21H
21/48 (20130101); D01F 8/04 (20130101); B42D
25/355 (20141001); Y10T 428/2931 (20150115); Y10T
428/24802 (20150115); Y10T 428/2976 (20150115); Y10T
428/298 (20150115); Y10T 428/2929 (20150115); Y10T
428/2973 (20150115); Y10T 428/2982 (20150115); Y10S
428/913 (20130101) |
Current International
Class: |
B32B
1/00 (20060101); B32B 5/16 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1092119 |
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Sep 1994 |
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CN |
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677 711 |
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Jul 1939 |
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DE |
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1446851 |
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Nov 1968 |
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DE |
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066854 |
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Apr 1985 |
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EP |
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1569283 |
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Jun 1980 |
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GB |
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02-053908 |
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Feb 1990 |
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JP |
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7300722 |
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Nov 1995 |
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JP |
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8-226032 |
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Sep 1996 |
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JP |
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09111531 |
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Apr 1997 |
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JP |
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11003054 |
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Jan 1999 |
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JP |
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11081012 |
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Mar 1999 |
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JP |
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2000/096349 |
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Apr 2000 |
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JP |
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9611906 |
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Sep 1996 |
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KR |
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WO-97/11991 |
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Apr 1997 |
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WO |
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WO-99/37836 |
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Jul 1999 |
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WO |
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WO 9945200 |
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Sep 1999 |
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WO |
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Other References
UK. Res. Disc. (1998), 411 July, p. 871-872. cited by other .
U.K. Res. Disc. (1998), 411 July, p. 877-878. cited by
other.
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Primary Examiner: Tarazano; D. Lawrence
Assistant Examiner: Thompson; Camie S
Claims
What is claimed is:
1. A security fiber comprising at least one synthetic polymer
filament possessing multiple security elements comprising: a. a
filament cross-section having a complexity factor of at least 5;
and b. at least one said filament comprising at least one
luminescent substance dispersed therein; wherein said .[.fiber.].
.Iadd.filament .Iaddend.exhibits at least two luminescent spectral
response peaks when excited by at least one wavelength selected
from the region 200 to 2000 nanometers.
2. The security fiber of claim 1 wherein the filament cross-section
has a complexity factor of at least 10.
3. The security fiber of claim 1 wherein the filament cross-section
has a complexity factor of at least 15.
4. The security fiber of claim 1 wherein the filament cross-section
has a complexity factor of at least 20.
5. The security fiber of claim 1 wherein the filament cross-section
has a complexity factor of at least 25.
6. The security fiber of claim 1 wherein the filament cross-section
is a member selected from the group illustrated in FIGS. 1, 2, 3,
4, 5, 6 and 7.
7. The security fiber of claim 1 wherein the number of said
filaments is at least two.
8. The security fiber of claim 7 wherein said filaments are in a
side-by-side relationship.
9. The security fiber of claim 7 wherein said filaments comprise
the same polymer containing different luminescent substances.
10. The security fiber of claim 1 wherein the wavelength producing
a luminescent response is in the infra-red.
11. The security fiber of claim 1 wherein the wavelength producing
a luminescent response is in the visible.
12. The security fiber of claim 1 wherein the wavelength producing
a luminescent response is in the ultraviolet.
13. The security fiber of claim 1 where at least one of the
luminescent responses is in the visible and at least one
luminescent response is in the infra-red.
14. The security fiber of claim 1 wherein there are two or more
excitation wavelengths producing luminescent responses and wherein
the excitation wavelengths lie within at least two different
members of group consisting of the infra-red, the visible and the
ultraviolet.
15. The security fiber of claim 1 wherein at least one of the
luminescent responses is fluorescence and at least one of the
luminescent responses is phosphorescence.
16. The security fiber of claim 1 wherein the effective diameter of
the filament(s) is in the range of 0.01 to 3 mm.
17. The security fiber of claim 1 prepared by the process
comprising: a. mixing a polymer and a luminescent substance in a
mixer in a dry state; b. extruding and spinning the mixture using a
twin screw extruder with mixing and kneading elements; and c.
cooling the melt filaments to solidify.
18. A security article containing the security fiber of claim
1.
19. A security thread comprising a plurality of the fibers of claim
1.
20. The security thread of claim 19 comprising at least one other
fiber.
21. A security article containing the security thread of claim
19.
22. The security fiber of claim 1 wherein said fiber comprises
different luminescent substances.
23. The security fiber of claim 1 herein said fiber comprises a
single luminescent substance.
24. A security fiber comprising at least one synthetic polymer
filament possessing multiple security elements comprising: a. a
filament cross-section having a complexity factor of at least 5;
and b. at least one said filament comprising at least one
luminescent substance dispersed therein; wherein said .[.fiber.].
.Iadd.filament .Iaddend.exhibits at least one luminescent spectral
response peak when excited by at least one wavelength selected from
the region 200 to 2000 nanometers.Iadd.; and wherein the number of
components present in said filament, C, is equal to
one.Iaddend..
25. The security fiber of claim 24 wherein the filament
cross-section has a complexity factor selected from the group
consisting of at least 10, at least 15, at least 20 and at least
25.
26. The security fiber of claim 24 wherein the filament
cross-section is a member selected from the group illustrated in
FIGS. 1,2,3,4,5, .Iadd.and .Iaddend.6.[.and 7.]. .
27. The security fiber of claim 24 wherein the number of said
filaments is at least two.
28. The security fiber of claim 27 wherein said filaments are in a
side-by-side relationship.
.[.29. The security fiber of claim 27 wherein said filaments
comprise the same polymer containing different luminescent
substances..].
30. The security fiber of claim 24 wherein the wavelength producing
a luminescent response is selected from the group consisting of the
infra-red, the visible and the ultraviolet regions of the
spectrum.
31. The security fiber of claim 24 wherein the effective diameter
of the filament(s) is in the range of 0.01 to 3 mm.
32. The security fiber of claim 24 prepared by the process
comprising: a. mixing a polymer and a luminescent substance in a
mixer in a dry state; b. extruding and spinning the mixture using a
twin screw extruder with mixing and kneading elements thereby
forming melt filaments; and c. cooling the melt filaments to
solidify.
33. An article containing the security fiber of claim 24.
34. A security thread comprising a plurality of the fibers of claim
24.
35. The security thread of claim 34 comprising at least one other
fiber.
36. A security article containing the security thread of claim
34.
37. A method of protecting documents or articles against fraudulent
duplication by incorporating therein security fiber comprising at
least one synthetic polymer filament possessing multiple security
elements comprising: a. a filament cross-section having a
complexity factor of at least 5; and b. at least one said filament
comprising at least one luminescent substance dispersed therein;
wherein said luminescent substance exhibits at least one
luminescent spectral response peak when excited by at least one
wavelength selected from the region 200 to 2000 nanometers;
.Iadd.and wherein the number of components present in said
filament, C, is equal to one.Iaddend..
38. A method of making security fiber comprising at least one
synthetic polymer filament and possessing multiple security
elements, said fiber comprising: a. a filament cross-section having
a complexity factor of at least 5; and b. at least one said
filament comprising at least one luminescent substance dispersed
therein; wherein said luminescent substance exhibits at least one
luminescent spectral response peaks when excited by at least one
wavelength selected from the region 200 to 2000 nanometers.Iadd.;
and wherein the number of components present in said filament, C,
is equal to one.Iaddend., prepared by the process comprising: a.
mixing a polymer and a luminescent substance in a mixer, b.
extruding and spinning the mixture using a twin screw extruder
having mixing and kneading elements to produce melt filaments; and
c. cooling the melt filaments to solidify.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to novel security articles comprising
fibers, threads and fiber sections ("dots") possessing multiple
verification characteristics. The fibers possess unique and
difficulty duplicated combinations of complex cross-sections,
components, and multiple luminescent responses. The many verifiable
characteristics of the security fibers, threads, and dots provide
high levels of protection against fraudulent duplication of
articles in which they are incorporated. The manifold security
features provide means of tailoring specific identity
characteristics for specific use and users.
2. Description of the Related Art
Security fibers are fibers incorporated in fiduciary documents or
other articles for the purpose of ensuring identification,
authentication, and protection against forgery, imitation or
falsification. The term "security thread" has been employed to
describe twisted or braided fibers or strips of films for the same
purposes.
German Patent 19802588 describes cellulose fibers containing
luminescent additives for security purposes.
European Patent 066854 B1 describes cellulose acetate security
fibers and security papers containing the fibers. The security
fibers are spun from an acetone solution containing a lanthanide
chelate. The fibers are colorless under normal lighting but show
narrow-band emission in the visible or infra-red (IR) when excited
by ultraviolet (UV) light. A security thread twined of fibers
having different luminophors is described wherein coded information
is impressed on the security thread.
U.S. Pat. Nos. 4,655,788 and 4,921,280 describe security fibers
invisible in sunlight or artificial light, which under excitation
by IR, UV or x-rays, exhibit a luminescence. The security fibers
are prepared by a process of dyeing conventional textile fibers
such as polyester, polyamide and cellulosic fibers with rare earth
chelates.
German Patent DE-A 14 46 851 describes a security thread having a
microprint executed in several colors.
U.S. Pat. No. 4,897,300 describes a security thread having
luminescent colors that are invisible in normal lighting and are
provided along the security thread in successive and overlapping
portions which, when the colors are excited, have a length
recognizable to the naked eye and in the overlapping areas have
characteristic mixed luminescences. The security threads are
produced by printing strip shapes on flat sheets and then cutting
them up.
U.S. Pat. No. 6,068,895 describes a woven security label
incorporating a detectable filament made by adding about 20 weight
percent (wt. %) of an inorganic fluorescent substance to polyester
dope and spinning filaments out of the dope.
U.S. Pat. No. 4,183,989 describes a security paper having at least
two machine verifiable security features, one of which is a
magnetic material, and a second of which may be a luminescent
material. The luminescent material is dispersed in a lacquer and
coated onto a film. The film is divided into planchettes of
approximately 1 mm diameter and incorporated in the paper.
Korean Patent KR 9611906 and WO 9945200 describe methods of
preparing luminescent fibers by dyeing. Korean Patent KR 9611906
describes the incorporation of the fibers into paper material.
UK Res. Discl. (1998), 411 (July), P. 877-P. 878, discloses
bi-component fibers with differentially dyeable domains for
incorporation into security papers.
Chinese Patent No. CN 1092119 describes polyvinyl alcohol fibers of
1-10 mm length containing pigments, dyes and fluorescent
materials.
U.S. Pat. Nos. 5,876,068, 5,990,197, 5,990,930 and 6,099,930
describe yet other means of providing security elements involving
luminescent substances.
In a related area, British Patent 1,569,283 describes an apparatus
for verifying the authenticity of documents coded with fluorescent
substances.
Each of these patents represented improvements in the state of
their respective arts. However, as security technology has evolved,
parallel improvements have taken place in the capabilities of those
who would evade security measures. A need exists for security
fibers possessing unique and more difficulty duplicated
combinations of verifiable security characteristics. A further need
exists for means to tailor specific identity characteristics for
specific users.
Luminescent substances have also been incorporated into fibers for
purposes unrelated to security applications or for unspecified
purposes.
U.S. Pat. No. 4,781,647 describes a method of producing
phosphorescent filaments by mixing phosphors, preferably zinc,
cadmium or calcium sulfide into the polymer together with a
coupling agent prior to extrusion and spinning into fibers for
dolls' hair.
U.S. Pat. No. 5,321,069 describes a process for producing
phosphorescent bulked continuous filament (BCF) yarns of
thermoplastic polymers for textile applications by melt spinning.
The process comprises the steps of mixing the polymer pellets with
a wetting agent, preferably mineral oil, adding a phosphorescent
powder such as zinc sulfide to substantially uniformly coat the
pellets, and heating in an extruder to form and extrude a melt
whereby a uniform distribution of phosphorescent pigment is said to
be obtained throughout the filaments. The individual filaments may
be solid or hollow and may have any conventional shape.
U.S. Pat. No. 5,674,437 describes a method for preparing
luminescent fibers comprising the steps of combining in an extruder
a thermoplastic polymer with a luminescent metal aluminate pigment,
heating and mixing to melt the polymer, and extruding the melt to
form a fiber.
U.S. Pat. No. 3,668,189 describes fiber forming fluorescent
polycarbonamides prepared by co-polymerization of a fused ring
polynuclear aromatic hydrocarbon moiety having at least three fused
rings.
Japanese Patents 7300722 A2 and 2000096349 A2 describe sheath-core
fibers with the core containing the luminescent substance.
SUMMARY OF THE INVENTION
The invention provides security articles comprising security
fibers, threads and dots for security applications possessing
unique and difficulty duplicated multiple verification
characteristics including combinations of complex cross-sections,
components and multiple luminescent responses. The multiple
security features provide means of tailoring specific identity
characteristics for specific users.
A security fiber of the invention is comprised of at least one
synthetic polymer filament possessing multiple security elements
comprising: a filament cross-section having a complexity factor of
at least 5, and at least one component containing at least one
luminescent substance, wherein the luminescent substance exhibits
at least two luminescent spectral response peaks when excited by at
least one wavelength selected from the region 200 to 2000
nanometers.
The security dots are prepared by transversely sectioning the
filaments of the security fibers.
BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawing figures:
FIG. 1 shows a fiber cross-section having a five-pointed star
shape;
FIGS. 2A and 2B show the cross-sections of a trilobal and a
quadrilobal fiber, respectively, each having T-shaped lobes, as
described in U.S. Pat. No. 5,057,368;
FIG. 3 shows the cross-section of a trilobal fiber previously
described in U.S. Pat. No. 4,770,938 having an axially extending
(cylindrical) hole in each lobe;
FIG. 4 shows the cross-section of a trilobal fiber having hollow
lobes in the shape of a figure eight;
FIG. 5 shows the cross-section of a quadrilobal fiber having
semicircular cylindrical holes at the distal ends of each lobe and
elliptically shaped cylindrical holes in each lobe;
FIG. 6 shows the cross-section of a trilobal fiber having three
double rows of cylindrical holes in each lobe and a trio of
cylindrical holes at the center of the cross-section;
FIG. 7 shows the cross-section of a bi-component quadrilobal fiber
having four cylindrical holes (see U.S. Pat. No. 6,158,204);
FIG. 8 shows the excitation and fluorescence spectra of an
inorganic luminescent pigment La.sub.2O.sub.2S:Eu available
commercially as LUMILUX.RTM. Red CD 168;
FIG. 9 shows the excitation and fluorescence spectra of
ZnSiO.sub.4:Mn, available commercially from Honeywell International
Inc. as LUMILUX.RTM. Green CD 145;
FIG. 10 shows the excitation and fluorescence spectra of
YVO.sub.4:Nd, available commercially from Honeywell International
Inc. as LUMILUX.RTM. IR-DC 139; and
FIG. 11 shows the excitation and fluorescence spectra of a rare
earth oxysulfide, available commercially from Honeywell
International Inc. as LUMILUX.RTM. Red UC 6.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides security fibers, threads and dots
possessing combinations of complex cross-sectional shapes,
components and multiple luminescent responses that are unique and
difficulty duplicated. The security fibers of the invention are
single filaments (monofilaments) or assemblies of monofilaments.
Where fiber cross-section is discussed below, it will be understood
that reference is made to the monofilament cross-section unless
otherwise stated. The fibers, threads and dots of the invention are
inserted into papers, documents and other articles by appropriate
processes to provide enhance levels of security.
The security fibers of the invention are formed from synthetic
polymers by continuous processes, such as melt spinning, wet
spinning, dry spinning, gel spinning and others. Synthetic fibers
typically are conventionally spun with round cross-sections, but
triangular, rectangular, trilobal, quadrilobal, and other shapes
are known. Fiber cross-sections may also be multiply connected,
i.e., they may contain holes, preferably cylindrical, which extend
through the entire length of the fiber. The greater is the degree
of complexity of a fiber cross-section, the greater is the
difficulty of the design of a spinneret to produce same, and the
greater is the degree of difficulty to duplicate this design by a
fraudulent party.
For the purposes of this invention, the "complexity factor" of a
fiber cross-section is quantitatively defined as follows:
.function..times. ##EQU00001##
where: CF is the "complexity factor" of the fiber cross-section; L
is the number of lobes or projections of the cross-section; N is
the number of nodes or branch points; C is the number of components
of the fiber; H is the number of holes in the cross-section; and R
is the number of reversals of curvature upon traversing in one
direction once around the inner surface of a hole in the fiber
cross-section. A reversal of curvature is signaled by a change in
the position of the center of curvature from one side to the other
side of the tangent to the inner surface of the hole in the fiber
cross-section.
For example, a conventional solid round fiber cross-section is
perfectly symmetrical having no lobes (L=0), no nodes or branch
points (N=0), one component (C=1), no holes (H=0), and therefore no
reversals of surface curvature within a hole (R=0). Consequently,
this simple fiber has a complexity factor as defined above equal to
(0+0+1.sup.3).times.[1].sup.1=1.
The fiber cross-section shown in FIG. 1 has five lobes (L=5), one
node at its center (N=1), one component (C=1), no holes, and
therefore no reversals of surface curvature within a hole (R=0).
Therefore this fiber has a complexity factor equal to
(5+1+1.sup.3).times.[1].sup.1=7.times.1=7.
The quadrilobal fiber shown in FIG. 2B has four lobes (L=4), one
node at its center and one on each lobe (N=5), one component (C=1),
no holes (H=0) and no reversals of curvature (R=0) within a hole.
Therefore the complexity factor of this fiber is
(4+5+1.sup.3).times.[1].sup.1=10.times.1=10.
The trilobal fiber shown in FIG. 3 has three lobes (L=3), one node
at the center (N=1), one component (C=1), three holes (H=3), and no
reversals of curvature within a hole (R=0). The complexity factor
of this fiber is (3+1+1.sup.3).times.[3].sup.1=5.times.3=15.
The fiber shown in FIG. 4 has a cross-section having three figure
eight shaped hollow lobes. The number of lobes is three (L=3).
There is a branch point at the center (N=1). There is one component
(C=1). There are three holes in the cross-section (H=3). Traversing
in one direction around the inner surface of a hole, the center of
curvature reverses twice upon traversing the waist on each side of
the lobe, making four reversals of curvature in all (R=4).
Therefore the complexity factor of the fiber of FIG. 4 is
(3+1+1.sup.3).times.[2+1].sup.3=5.times.27=135.
Similarly, the fiber cross-sections illustrated in FIGS. 5 and 6
have complexity factors of 30 and 70 respectively.
As a final illustration, the bi-component fiber shown in FIG. 7 has
four lobes (L=4), one node at the center (N=1), two components
(C=2), four holes (H=4) and no reversals of curvature within a hole
(R=0). Therefore the complexity factor of the fiber of FIG. 7 is
(4+1+2.sup.3).times.[2+1].sup.1=13.times.3=39.
It will be understood that the fibers of the invention generally
have a constant cross-section along their lengths.
One of the verifiable features of the security elements of this
invention is the fiber cross-section. The complexity factor of the
cross-section (as defined above) is preferably at least 5, more
preferably at least 10, yet more preferably at least 15, more
preferably at least 20 and most preferably at least 25. U.S. Pat.
Nos. 5,057,368 and 4,770,938 describe how to spin fibers having the
complex cross-sections shown in FIGS. 2 and 3 respectively and are
hereby incorporated by reference to the extent not incompatible
herewith.
A second group of security features that the fibers of the
invention possess is the number, location, composition and physical
properties of components. Bi-component fibers are known having two
distinct cross-sectional domains of two distinct polymer types
differing from each other in composition (e.g., polyester vs.
nylon) or in physical properties (e.g., color). Bi-component fibers
and methods for their manufacture are described for example in U.S.
Pat. Nos. 4,552,603, 4,601,949, and 6,158,204. The disclosures of
these patents are hereby incorporated by reference to the extent
not incompatible herewith. The components may be in a side-by-side
relationship or in a sheath-core relationship.
In one embodiment, the number of components in the security fibers
of the invention is at least two. It is preferred that the
components in a multi-component fiber be in a side-by-side
relationship with one another. FIG. 7 illustrates the cross-section
of one bi-component fiber described in U.S. Pat. No. 6,158,204. The
portions of the cross-sections labeled A and B represent different
components.
The components may be of different polymer compositions. However,
it is preferred that the components are comprised of the same basic
polymer but have different colors under normal lighting conditions
and different luminescent responses to UV or IR illumination. The
polymer constituents of the security fibers of the invention are
selected from the group consisting of polyamides, polyesters,
polyolefins, polyacrylics, polyalcohols, polyethers, polyketones,
polycarbonates, polysulfides, polyurethanes, and cellulosic and
polyvinyl derivatives. Polyolefins, polyesters and polyamides are
preferred. Most preferred polymers are polypropylene, polyethylene
terephthalate, polytrimethylene terephthalate, nylon 6 and nylon
66.
The security fibers of the invention have an "effective diameter"
of about 0.01 mm to about 3 mm. Effective diameter for the purposes
of this invention is the diameter of the smallest circle that can
circumscribe the fiber cross-section.
In one embodiment of the invention, the fibers are transversely
sectioned into cross-sectional slices of 0.005 mm to 0.5 mm
thickness. The resulting "dots" are incorporated into papers or
other articles where the unique cross-sections, components and
luminescent responses are readily identified with the naked eye or
under moderate magnification.
A third security feature of the fibers of the invention is multiple
luminescent responses. The luminescent responses are selected from
the group consisting of phosphorescence or fluorescence. The
luminescent responses include wavelengths in the infrared, the
visible and the ultra-violet regions of the spectrum. The infra-red
spectrum is taken to begin at wavelengths greater than 700
nanometers (nm) and for the purposes of this invention may be taken
to end at 2000 nm. The visible spectrum is taken to lie in the
wavelength region of 400 to 700 nm. The ultraviolet spectrum is
taken to lie in the region 200 to 400 nm.
Luminescent substances are incorporated in one or more of the
components of the security fibers of the invention. A single
luminescent substance may have multiple luminescent responses as
indicated by multiple intensity peaks in its luminescent spectrum.
For the purposes of this invention, spectral peaks having an
intensity less than about one-fifth of the maximum peak intensity
shall be disregarded.
In one embodiment, the security fiber has one component and this
component contains one or more luminescent substances presenting
differing luminescent responses to illuminations of the same or
differing wavelengths. In another embodiment, the security fibers
are multi-component fibers each containing a single luminescent
substance but with differing luminescent responses to the same or
differing wavelengths. In yet another embodiment, the security
fibers are multi-component fibers each containing multiple
luminescent substances with differing luminescent responses to
illuminations of the same or differing wavelengths.
Luminescence of the security fibers of the invention is obtained by
incorporation of luminescent copolymers, pigments or dyes prior to
or during spinning, or by dyeing of the spun fiber with luminescent
dyes. It is preferred that luminescent copolymers, pigments or dyes
are integrally incorporated into the fiber by mixing prior to or
during the fiber spinning operation. It is most preferred that the
luminescent substances be incorporated by mixing with the polymer
in a mixer, followed by extrusion and spinning using a twin screw
extruder having mixing elements.
The multiple luminescent responses are in one or more of the
infra-red, visible and ultraviolet regions of the spectrum.
Preferably, the peak intensities of the multiple luminescent
responses of the security fibers of the invention are separated in
wavelength by at least 20 nm, more preferably by at least 50 nm,
and yet more preferably by at least 100 nm. It is most preferred
that the multiple luminescent responses have peak wavelengths in at
least two different regions of the spectrum. Most preferably, the
multiple luminescent responses are in the infra-red and visible
regions of the spectrum.
The multiple luminescent responses of the security fibers of the
invention are excited by one or more illumination wavelengths
selected from the infra-red, the visible and the ultraviolet
regions of the spectrum. Preferably, the luminescent responses are
excited by one or more wavelengths in the infra-red and the
ultraviolet.
Luminescent pigments or dyes may be organic or inorganic
substances. Examples of thermally stable organic substances useful
in the security fibers of the invention are the compounds
4,4'-bis(2 methoxystyryl)-1,1'-biphenyl,
4,4'-bis(benzoaxazol-2-yl)stilbene, and 2,5-thiophenediylbis
(5-tert-butyl-1,3-benzoxazole). These compounds are sold
commercially by Ciba Specialty Chemicals Inc. under the trade names
UVITEX.RTM. FP, UVITEX.RTM. OB-ONE, and UVITEX.RTM. OB
respectively. They are excited by ultraviolet radiation and
fluoresce in the ultraviolet and visible regions of the
spectrum.
Examples of inorganic substances useful in the security fibers of
the invention are the materials La.sub.2O.sub.2S:Eu, ZnSiO.sub.4:
Mn, and YVO.sub.4:Nd. These materials are sold commercially by
Honeywell Specialty Chemicals under the trade names LUMILUX.RTM.
Red CD 168, LUMILUX.RTM. Green CD 145 and LUMILUX.RTM. IR-DC 139,
respectively. FIGS. 8-10 show their excitation and fluorescence
spectra. Each is excited by ultraviolet radiation. LUMILUX.RTM. Red
CD 168 and LUMILUX.RTM. Green CD 145 fluoresce in the visible.
LUMILUXE.RTM. IR-DC 139 fluoresces in the infra-red.
Another substance useful in the security fibers of the invention is
a rare earth oxysulfide sold commercially by Honeywell Specialty
Chemicals under the trade name LUMILUX.RTM. Red UC 6. This material
is excited by infra-red and fluoresces in the visible. Its
excitation and fluorescence spectra are shown in FIG. 11.
Examples of luminescent copolymers useful in the security fibers of
the invention are described in U.S. Pat. Nos. 3,668,189 and
5,292,855 and 5,461,136. Described are thermally stable
co-polyamides, co-polyesters and co-polyester-amides having
fluorophoric compounds copolymerized therein. The copolymers of
U.S. Pat. No. 5,292,855 are excited by and fluoresce at wavelengths
in the near infra-red region of the spectrum.
U.S. Pat. Nos. 5,424,006 and 5,674,437 describe phosphorescent
substances and methods of their manufacture useful in the security
fibers of the invention. Fluorescent substances cease fluorescing
virtually instantaneously, in less than about a thousandth of a
second, upon cessation of excitation. Phosphorescent substances may
continue luminous emissions for some tens or hundreds of minutes
after cessation of excitation. An example is the material
SrAl.sub.2O.sub.4: Eu Dy described in U.S. Pat. No. 5,424,006. The
rate of decay of luminescence is one of the verifiable features of
the fibers of the invention.
The security fibers of the invention are formed into security
threads by conventional fiber processes such as twisting, cabling,
braiding, texturizing and heat setting. The same or different
security fibers may be incorporated in a security thread.
The security article of the invention can be security threads or
other items, such as passports, currency, or other important
documents. The threads can be used to reproduce luminescent logos
in fabrics or clothing, or may include such a logo as a complex
cross-section. A cabled security thread can be tailored to specific
end uses through any combination of colors and cross-sections. By
way of example, a security thread could have a star cross-section
(FIG. 1) with a red luminescent response. Such a security thread
could be targeted for the Chinese passport since the national color
of Chinese flag is red and its flag has five stars. For Italy, the
security thread could be a combination of security fibers having
red and green luminescent responses with a white fiber, to target
the national colors of the Italian flag.
The following examples are presented to provide a more complete
understanding of the invention. The specific techniques,
conditions, materials, proportions and reported data set forth to
illustrate the principles of the invention are exemplary and should
not be construed as limiting the scope of the invention.
In the accompanying examples the formic acid viscosity (FAV) is
determined via ASTM-D789-97, with the following changes. A
Cannon-Fenske viscometer, otherwise called a modified Ostwald
viscometer, was utilized in lieu of the calibrated pipet-type
viscometer specified. 5.50 g per 50.0 mL of 90% formic acid was
utilized in lieu of the specified quantity of 11.00 g per 100 mL of
90% formic acid.
EXAMPLE 1
Honeywell International Inc. nylon 6 (grade MBM, 55 FAV) is tumble
blended in a twin shell dry mixer with 2.5 wt. % of an inorganic
luminescent pigment La.sub.2O.sub.2S:Eu, and 2.5 wt. % of second
inorganic luminescent pigment YVO.sub.4:Nd. The pigments are
manufactured by Honeywell Specialty Chemicals and designated
LUMILUX.RTM. Red CD 168 and LUMILUX IR-CD 139 respectively. 95 wt.
% of the La.sub.2O.sub.2S:Eu (LUMILUX.RTM. Red CD 168) pigment is
of particle size less than 8.0 micrometers. 95 wt. % of the
YVO.sub.4:Nd (LUMILUX.RTM. IR-CD 139) pigment is of particle size
less than 11.0 micrometers.
The blended mixture is fed to a Leistritz twin screw extruder of 18
mm diameter and 40:1 L/D. The extruder screws have mixing and
kneading elements as well as conveying elements. The extruder
barrel zone temperatures are set at 250-255.degree. C. The polymer
melt is delivered to a Zenith gear pump and then passed through a
graded screen pack consisting of 17 screens ranging from 20 mesh
down to 325 mesh (44 micrometer opening). After passing through the
screen pack, the polymer melt issues from a 14 hole spinneret to
produce the filament cross-section shown in FIG. 1. The issuing
melt filaments are solidified by cocurrent quench air flow at
19.5.degree. C. The extrusion rate is 9.46 g/min and the initial
fiber take-up speed is 500 meters/min. The fiber is drawn 2.8:1
in-line with spinning. Final fiber dimensional and tensile
properties (measured by ASTM D2256) are as follows:
TABLE-US-00001 Denier/filament: 4.3 Effective Diameter: 0.12 mm
Tenacity: 3.9 g/d Initial Modulus: 49 g/d Ultimate Elongation
16%
The filaments of this example have the complex cross-section shown
in FIG. 1 (complexity factor of 7), one component, and when
illuminated by a mercury UV lamp, has multiple fluorescent
responses with peaks at 622 nanometers (red) and at 880 and 1060
nanometers in the infra-red. The filaments are essentially
colorless under normal illumination.
EXAMPLE 2
Example 1 was repeated with the following changes: BHS grade, 90
FAV nylon 6 polymer with 5% Lumilux.RTM. red CD 740; extruder
barrel zone temperature at 310.degree. C.; and filament
cross-section as shown in FIG. 2A. A first fiber (Example 2X) was
drawn offline at a draw ratio of 3.6:1. A second fiber (Example 2Y)
was drawn offline at a draw ratio of 5.6:1. Final fiber dimensional
and tensile properties (measured by ASTM D2256) are as follows:
TABLE-US-00002 Example 2X 2Y Denier/filament: 22 15 Tenacity:
3.3-3.6 g/d 5.4-5.8 g/d Initial Modulus: 19-22 g/d 28 g/d Ultimate
Elongation 62% 15-19%
The filaments of this example have the complex cross-section shown
in FIG. 2A, and when illuminated by a mercury UV lamp, have a
visible red color The filaments are essentially colorless under
normal illumination.
EXAMPLE 3
The fibers of Example 1 are transversely sectioned at intervals of
0.2 mm to produce "dots" having the complexity factor and multiple
fluorescent responses as in Example 1.
EXAMPLE 4
Honeywell International Inc. nylon 6 (Grade MBM, 55 FAV) is tumble
blended in a twin shell dry mixer with 5.0 wt. % of an inorganic
luminescent pigment La.sub.2O.sub.2S:Eu (LUMILUX.RTM. Red CD 168).
A second batch of the same nylon 6 is tumble blended with 5.0 wt. %
of a different inorganic luminescent pigment ZnSiO.sub.4:Mn
designated LUMILUX.RTM. Green CD 145. 95 wt. % of the
ZnSiO.sub.4:Mn (LUMILUX.RTM. Green CD 145) pigment is of particle
size less than 7.0 micrometers.
Each of the blended mixtures is fed to a twin screw extruder with
barrel zone temperatures at 250-255.degree. C. The separate polymer
melts are conveyed through separate Zenith gear pumps and screen
packs, and into a common spin block. The melt streams are combined
as described in U.S. Pat. No. 6,158,204 to produce a bi-component
fiber having the filament cross-section illustrated in FIG. 7.
Fourteen filaments are spun at the same combined extrusion rate and
the same take-up speed as in Example 1. The fiber is drawn 2.8:1
in-line. Final fiber dimensional and tensile properties (measured
by ASTM D2256) are the following:
TABLE-US-00003 Denier/filament: 4.3 Effective Diameter: 0.042 mm
Tenacity: 4.1 g/d Initial Modulus: 40 g/d Ultimate Elongation
20%
The filaments of the invention have the complex cross-section shown
in FIG. 7 (complexity factor of 39), two components, and when
illuminated by a mercury UV lamp, show side-by-side fluorescent
responses with peaks at 622 nanometers (red) in one component and
at 525 nanometers (green) in the other component. The filaments are
essentially colorless under normal illumination.
EXAMPLE 5
The fibers of Example 4 are transversely sectioned at intervals of
0.2 mm to produce "dots" having the complexity factor and multiple
fluorescent responses as in Example 4.
EXAMPLE 6
A bi-component fiber having the complex cross-section shown in FIG.
7 is prepared as in Example 4 with the exception that one component
contains 5.0 wt. % of La.sub.2O.sub.2S: Eu (LUMILUX.RTM. Red CD
168) pigment. The second component contains 2.5 wt. % of
YVO.sub.4:Nd (LUMILUX.RTM. IR-CD 139) pigment and 2.5 wt. %
ZnSiO.sub.4:Mn (LUMILUX.RTM. Green CD 145) pigment. The filaments
of the invention have the complex cross-section shown in FIG. 7
(complexity factor of 39), two components, and when illuminated by
a mercury UV lamp, show side-by-side fluorescent responses with
peaks at 622 nanometers (red) in one component and at 525
nanometers (green) in the second component. Furthermore, the second
component also fluoresces in the infra-red at 880 and 1060
nanometers. The filaments are essentially colorless under normal
illumination.
EXAMPLE 7
A bi-component fiber having the complex cross-section shown in FIG.
7 is prepared as in Example 4 with the exception that one component
contains 5.0 wt. % of La.sub.2O.sub.2S: Eu (LUMILUX.RTM. Red CD
168) pigment. The second component contains 5.0 wt. % of
CaAl.sub.2O.sub.4:Eu,Sm phosphorescent phosphor prepared as in U.S.
Pat. No. 5,424,006, hereby incorporated by reference to the extent
not inconsistent herewith. The filaments of the invention have the
complex cross-section shown in FIG. 7 (complexity factor of 39),
two components, and when illuminated by a mercury UV lamp, show
side-by-side fluorescent responses with peaks at 622 nanometers
(red) in one component and at 450 nanometers (blue) in the second
component. Furthermore, the second component continues to glow with
a blue phosphorescence for tens of minutes after the cessation of
illumination. The filaments are essentially colorless undernormal
illumination.
EXAMPLE 8
Honeywell International Inc. nylon 6 (Grade MBM, 55 FAV) is tumble
blended in a twin shell dry mixer with 5.0 wt. % of a
phosphorescent phosphor CaAl.sub.2O.sub.4:Eu,Sm (see Example 7). A
second batch of Honeywell International polyethylene terephthalate
(PET) (0.85 intrinsic viscosity) is tumble blended in a twin shell
dry mixer with 5.0 wt. % of a different inorganic luminescent
pigment La.sub.2O.sub.2S:Eu (LUMILUX.RTM. Red CD 168). Each of the
blended mixtures is fed to a twin screw extruder with barrel zone
temperatures at 250-255.degree. C. for the nylon 6 and
285-300.degree. C. for the PET. The separate polymer melts are
conveyed through separate Zenith gear pumps and screen packs, and
into a common spin block. The melt streams are combined as
described in U.S. Pat. No. 6,158,204 to produce a bi-component
fiber. Fourteen filaments are spun at the same extrusion rate and
take-up speed as in Example 1. The fiber is not further drawn. The
final filaments are 12 denier/filament and have an effective
diameter of 0.070 mm. The fiber is a bicomponent fiber having the
complex cross-section shown in FIG. 7. The fiber is dyed in a dye
bath using an acid dye of Burconyl Yellow M-R 250% produced by
Burlington Chemical Inc. Under normal illumination the nylon 6 half
of the fiber is yellow but the PET half is essentially colorless.
When illuminated by a mercury UV lamp, the PET portion of the fiber
fluoresces in the red and the nylon 6 portion is a phophorescent
green.
EXAMPLES 9-14
Other security fibers of the invention are prepared having the
constructions described in Table 1 below.
Having thus described the invention in rather full detail, it will
be understood that such detail need not be strictly adhered to but
that further changes and modifications may suggest themselves to
one skilled in the art, all falling within the scope of the
invention as defined by the subjoined claims.
TABLE-US-00004 TABLE 1 Peak Example Cross- Components Complexity
Luminescent Luminescence No. section Polymer/Luminescent* Factor
Excitation Responses, nm Type 9 FIG. 2B PET/Copolymer A 10 Laser
diode 672 nm 687, 755 fluorescence 10 FIG. 3
N6/Zn.sub.2SiO.sub.4:Mn; 15 mercury lamp UV 525, 860, 1060
fluorescence YVO.sub.4:Nd 11 FIG. 4 N6/Zn.sub.2SiO.sub.4:Mn; 135
Mercury lamp UV 525, 860, 1060 fluorescence YVO.sub.4:Nd 12 FIG. 5
PP/LUMILUX Red UC 6; 30 IR laser diode 980 nm; 660, 680
fluorescence YVO.sub.4:Nd mercury lamp UV 860, 1060 13 FIG. 6
N66/CaAl.sub.2O.sub.4:Eu,Sm; 70 mercury lamp UV 450, 622
phosphorescence, La.sub.2O.sub.2S:Eu fluorescence 14 FIG. 7 1.
TMT/Copolymer A 39 Laser diode 672 nm 1. 687, 755 1. fluorescence
2. TMT/CaAl.sub.2O.sub.4:Eu,Sm mercury lamp UV 2. 450 2.
phosphorescence Copolymer A = Example 16 of U.S. Pat. No. 5,461,136
PET = polyethylene terephthalate N6 = polycaprolactam (nylon 6) N66
= polyhexamethylene adipate (nylon 66) PP = polypropylene TMT =
polytrimethylene terephthalate
* * * * *