U.S. patent application number 11/093009 was filed with the patent office on 2005-10-13 for taggant fibers.
This patent application is currently assigned to Innovation Technology, Inc.. Invention is credited to Dugan, Jeffrey S..
Application Number | 20050227068 11/093009 |
Document ID | / |
Family ID | 35060884 |
Filed Date | 2005-10-13 |
United States Patent
Application |
20050227068 |
Kind Code |
A1 |
Dugan, Jeffrey S. |
October 13, 2005 |
Taggant fibers
Abstract
Multicomponent fibers are provided that include a plurality of
coextruded polymeric components arranged in discrete structured
domains. The polymer domains have one or more identifying
characteristics that can be varied to form a plurality of different
identifying patterns. A plurality of islands in the sea fibers can
be provided, the plurality of fibers including two or more subsets
of fibers, each subset comprising a uniquely identifiable cross
sectional pattern of island domains, each pattern being formed from
an array comprising a predetermined number of island domains in
predetermined locations within the array, wherein each pattern is
determined by classifying individual island domains within the
array as present or absent from the pattern. The plurality of
fibers can be meltspun simultaneously to form a filament yarn or
tow.
Inventors: |
Dugan, Jeffrey S.; (Erwin,
TN) |
Correspondence
Address: |
ALSTON & BIRD LLP
BANK OF AMERICA PLAZA
101 SOUTH TRYON STREET, SUITE 4000
CHARLOTTE
NC
28280-4000
US
|
Assignee: |
Innovation Technology, Inc.
|
Family ID: |
35060884 |
Appl. No.: |
11/093009 |
Filed: |
March 29, 2005 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
60557569 |
Mar 30, 2004 |
|
|
|
Current U.S.
Class: |
428/364 ;
264/172.13 |
Current CPC
Class: |
D06H 1/00 20130101; Y10T
428/2913 20150115; D01F 8/04 20130101; D01D 5/36 20130101 |
Class at
Publication: |
428/364 ;
264/172.13 |
International
Class: |
D01D 005/36 |
Claims
That which is claimed:
1. A multicomponent fiber comprising two or more coextruded
polymers arranged in discrete structured domains, wherein at least
one of the polymer domains has at least one identifier
characteristic that can be varied to form a plurality of different
identifying patterns.
2. The multicomponent fiber of claim 1, wherein said at least one
identifier characteristic comprises the number of polymer domains
present or absent in the fiber and the relative positions thereof
in the fiber cross section, and wherein said fiber includes a
sufficient number of polymer domains to provide a plurality of
different identifying patterns formed by selecting different
combinations of the domains be present or absent in the fiber.
3. The multicomponent fiber of claim 2, wherein the number of
polymer domains in the fiber is at least about 4 to provide at
least about 12 different identifying patterns.
4. The multicomponent fiber of claim 1, wherein said at least one
identifier characteristic comprises at least one polymer domain
having a distinctive cross section feature that can be varied to
form a plurality of different identifying patterns.
5. The multicomponent fiber of claim 1, further comprising at least
one polymer domain that further has an additional unique physical
characteristic that is different from that of other of the polymer
domains to provide an additional identifying feature to the
fiber.
6. The multicomponent fiber of claim 1, wherein said fiber is an
islands in the sea fiber having a plurality of island polymer
domains within a surrounding sea polymer domain.
7. A collection of multicomponent fibers according to claim 1,
wherein each fiber is derived from a common multicomponent fiber
construction comprising two or more coextruded polymers arranged in
discrete structured domains, at least one of said domains having at
least one identifier characteristic that can be varied to form a
plurality of different identifying patterns, wherein the collection
of fibers comprises a first subset of fibers exhibiting a first
variation of said at least one identifier characteristic and a
second subset of fibers exhibiting a second variation of said at
least one identifier characteristic such that the first subset and
the second subset are visually distinguishable from each other.
8. The collection of multicomponent fibers of claim 7, wherein said
at least one identifier characteristic comprises the number of
polymer domains present or absent in the fibers, and wherein said
different identifying patterns are formed by selecting different
combinations of the domains be present or absent in the fiber.
9. The collection of multicomponent fibers of claim 7, wherein said
at least one identifier characteristic comprises at least one
polymer domain having a distinctive cross section feature that can
be varied to form different identifying patterns.
10. The collection of multicomponent fibers of claim 7, wherein the
collection of multicomponent fibers further comprises one or more
additional subsets of fibers, each additional subset of fibers
exhibiting a variation of said at least one identifier
characteristic that is visually distinguishable from all other
subsets.
11. The collection of multicomponent fibers of claim 7, wherein the
collection of fibers are derived from a common filament yarn or tow
coextruded through the same spinneret.
12. A collection of multicomponent fibers according to claim 1,
wherein said multicomponent fibers are islands in the sea fibers,
and wherein the collection of fibers comprises a first subset of
fibers comprising a first uniquely identifiable cross sectional
pattern of island domains and a second subset of fibers comprising
a second uniquely identifiable cross sectional pattern of island
domains, each pattern being formed from an array of a predetermined
number of island domains in predetermined locations within the
array, wherein each pattern is determined by classifying individual
island domains within the array as present or absent from the
pattern.
13. The collection of multicomponent fibers of claim 12, wherein
the collection of fibers are derived from a common filament yarn or
tow coextruded through the same spinneret.
14. The collection of multicomponent fibers of claim 12, wherein
the collection of multicomponent fibers further comprises one or
more additional subsets of fibers, each additional subset of fibers
comprising a uniquely identifiable cross sectional pattern that is
visually distinguishable from all other subsets.
15. A collection of multicomponent fibers according to claim 1,
wherein said multicomponent fibers are islands in the sea fibers,
and wherein said collection of fibers comprises a first subset of
fibers comprising a first uniquely identifiable cross sectional
pattern of one or more island domains and at least one island
domain comprising an array of protrusions on the periphery thereof
and a second subset of fibers comprising a second uniquely
identifiable cross sectional pattern of one or more island domains
and at least one island domain comprising an array of protrusions
on the periphery thereof, each pattern being determined by
classifying individual protrusions on the at least one island
domain as present or absent from the pattern.
16. The collection of multicomponent fibers of claim 15, wherein
the collection of fibers are derived from a common filament yarn or
tow coextruded through the same spinneret.
17. The collection of multicomponent fibers of claim 15, wherein
the collection of multicomponent fibers further comprises one or
more additional subsets of fibers, each additional subset of fibers
comprising a uniquely identifiable cross sectional pattern that is
visually distinguishable from all other subsets.
18. The multicomponent fiber of claim 1, wherein at least one of
the polymer domains comprises at least one void formed by solvent
extraction of a soluble polymer.
19. A taggant material for identifying a product, comprising a
multicomponent fiber according to claim 1, or a portion
thereof.
20. A product comprising one or more multicomponent fibers
according to claim 1, one or more portions thereof, or both, having
a pattern formed by one or more of the shape, number, and
arrangement of polymer domains in the fiber cross section suitable
for use as a unique identifying pattern.
21. A method of making an identifier material useful for tagging
products, the method comprising: defining a multicomponent fiber
structure comprising a plurality of coextruded polymeric components
arranged in discrete structured domains, wherein at least one of
the polymer domains has at least one identifying characteristic
that can be varied to form a plurality of different identifying
patterns; selecting at least one of said identifying patterns; and
melt extruding at least two different polymers under conditions
selected to provide a multicomponent fiber having said selected
identifying pattern.
22. The method of claim 21, wherein said melt extruding step
comprises melt extruding said polymers to form a plurality of
multicomponent fibers comprising a first subset of fibers having a
first selected identifying pattern and a second subset of fibers
having a second selected identifying pattern, and wherein said
method further comprises forming the multicomponent fibers into a
yarn or tow.
23. A method for melt-spinning a series of islands in the sea
fibers using a unitary cross sectional fiber design based on an
array of a predetermined number of island domains in predetermined
locations within the array, comprising: (a) providing a
melt-spinning apparatus adapted for coextruding multiple flows of
molten polymer through a spinneret; (b) selecting a uniquely
identifiable pattern of island domains by determining which island
domains within the array will be present in the pattern and which
island domains within the array will be absent; (c) configuring the
melt-spinning apparatus to provide the flows of molten polymer
necessary to coextrude an islands in the sea fiber comprising the
selected pattern of island domains; (d) melt-spinning the islands
in the sea fiber comprising the selected pattern of island domains;
and (e) optionally, repeating steps (b)-(d) for one or more
additional uniquely identifiable patterns of island domains.
24. The method of claim 23, wherein two or more subsets of fibers,
each fiber subset comprising a uniquely identifiable pattern of
island domains, are simultaneously meltspun to form a filament yarn
or tow.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application claims the benefit of U.S.
Provisional Application No. 60/557,569, filed Mar. 30, 2004, which
is incorporated herein by reference in its entirety and for all
purposes.
FIELD OF THE INVENTION
[0002] The present invention relates generally to fibrous
structures including structured coextrudable polymeric components,
useful for making identifiers or taggants for a variety of
products, and to processes for making and using the same.
BACKGROUND OF THE INVENTION
[0003] Materials known generally as taggants have been proposed for
incorporation into products to identify and/or verify various
characteristics of the same. For example, taggants have been
proposed for the identification of products such as explosives,
certain bulk chemicals that can be used to make explosives,
ammunition, paint, petroleum products, and documents, among others.
Materials have also been applied to products to track point of
origin, authenticity, and distribution of the products. It also can
be useful to include in the identification information such as the
date of manufacture and, in case the products are made in different
batches or lots, the particular lot with which the product is
associated.
[0004] One method to identify and verify product information
involves the use of inks transparent to visible light. The inks are
applied to the product, and the presence (or absence) of the ink is
revealed by ultraviolet or infrared fluorescence.
[0005] Other identification and verification methods include
implanting microscopic additives that can be detected optically. As
an example, U.S. Pat. Nos. 4,053,433 and 4,390,452 describe a
method of marking a substance with microparticles, which are
encoded with an orderly sequence of visually distinguishable
colored segments that can be detected with a microscope or other
magnifying device.
[0006] Many of the methods for identifying and verifying articles
using taggant materials can be unsatisfactory. Often the methods
used to produce taggant materials are difficult to implement,
expensive and time consuming. The materials used to make the
taggant products can also be expensive and/or difficult to handle.
In addition, taggant materials can adversely affect or degrade the
performance of the tagged product. Still further, specialized
equipment is often required to manufacture the taggant materials
and/or to detect the presence of the same in a product, thereby
further increasing the costs associated with the use of such
materials.
[0007] U.S. Pat. No. 4,640,035 to Kind et al. is directed to
particulate coding materials stated to be useful in identifying the
origin of a product. The particulate coding material includes thin
transverse sections of an assembly of elongate elements, e.g.,
fibers. The individual fibers of the assembly are separately
extruded, combined, and heated to adhere the fibers to one another
to form a unitary structure. Alternatively, each fiber is
individually extruded and thereafter directed to an assembly where,
in a separate processing step, the fibers are bonded together via a
low melt matrix material.
[0008] The methods discussed in the '035 patent can be time
consuming and costly, as well as require specialized equipment.
Further, the methods of the '035 patent are limited to the
production of relatively simple shapes of the individual fibers,
e.g., round cross sections. The method cannot be readily adapted to
produce assemblies with individual components having complex
(non-round) cross sectional shapes.
BRIEF SUMMARY OF THE INVENTION
[0009] The present invention provides multicomponent fibers
suitable for the production of taggant materials. The fibers of the
invention allow for the production of taggants having a desired
size and are particularly useful in the production of exceptionally
small taggants. The resultant taggants can be less noticeable in
use and further are less likely to degrade or interfere with the
performance of the tagged product. The fibers of the invention can
also provide taggants at relatively low costs and with good
productivity.
[0010] The present invention is based on a common multicomponent
fiber construction or structure, which includes a plurality of
polymeric components arranged in discrete structured domains. The
polymer domains have one or more identifier characteristics that
can be varied to form a plurality of different identifying
patterns. In one example, the multicomponent fiber structure can
have available for inclusion therein a sufficient number of polymer
domains to allow selection of various combinations of the domains
to be present or absent to form a number of different identifying
patterns for individual fibers derived therefrom. As another
example, the multicomponent fiber can include one or more polymer
domains having a distinctive cross sectional feature, which
distinctive feature can be varied to form a number of different
identifying patterns for individual fibers derived therefrom. In
this aspect of the invention, the distinctive cross section feature
of the multicomponent fiber structure can include one or more
features that can be present or absent, differently sized,
differently shaped, etc. The multicomponent fiber structure thus
provides a framework for the production of a group or collection of
different individual fibers derived therefrom, wherein the
identifier characteristics of fibers with a given pattern are
unique as compared to the identifier characteristics of fibers of
other patterns. The present invention also includes a collection,
series, or group of such fibers, each fiber or subset of fibers
within the collection having a unique pattern, which collection
includes at least two, and up to five or more, individual fibers or
fiber subsets, wherein the collection of fibers can optionally be
meltspun simultaneously in a single filament yarn or tow.
[0011] Generally the common multicomponent fiber structure includes
at least about 4 polymer domains or at least about 4 variations of
a distinctive polymer domain cross section, and can include up to
100 polymer domains or 100 variations of a distinctive polymer
domain cross section, or more, so as to provide at least about 12
different identifying patterns. The number of polymer domains
available for arrangement, combination, and/or modification thereof
to make different patterns is limited primarily by the cost of the
fiber spinning equipment needed to form a sufficient number of
different patterns.
[0012] In addition, the common multicomponent fiber structure of
the invention can include at least one polymer domain that has a
unique physical characteristic that is different from that of other
of the polymer domains. This can provide an additional variable to
choose when selecting various combinations of the polymer domains
to be present or absent and/or selecting variations of a
distinctive polymer domain cross section to create a particular
unique identifier pattern or design.
[0013] The present invention also provides a yarn or tow including
a plurality of fibers as described above. Advantageously all of the
fibers present in the yarn are multicomponent fibers having
discrete structured domains forming the same pattern, or the yarn
includes multiple subsets of fibers, wherein each fiber subset has
the same pattern.
[0014] The multicomponent fibers and yarns of the invention are
useful in producing a taggant material for identifying a product.
The taggant materials can include the fiber, and/or a yarn or tow
thereof, incorporated into the tagged product (for example, by
weaving or knitting the fiber, yarn and/or tow into a fabric). The
taggant materials of the invention can also include only a part or
portion of the fiber, and/or of a yarn or tow thereof, incorporated
into the tagged product.
[0015] The present invention also includes products tagged with one
or more of the multicomponent fibers of the invention.
Alternatively the product can be tagged with a portion of one or
more of the multicomponent fibers of the invention. The fibers, or
a portion thereof, can be dispersed in or adhered to the product or
material to be tagged. The fibers generally include a pattern
formed by one or more of the shape, number, and/or arrangement of
the polymer domains in the fiber cross section in a manner that is
suitable for use as an unique identifying pattern. In this aspect
of the invention, in the tagged product, at least some of the
fibers and/or portions thereof have cross section patterns that
differ from one another and form a unique identification by the
combination of the identifying patterns present in the fibers
associated with the product.
[0016] The present invention also provides methods of making an
identifier material for tagging products. This aspect of the
invention includes defining a multicomponent fiber structure having
a plurality of coextruded polymeric components arranged in discrete
structured domains. The polymer domains have one or more
identifying characteristics that can be varied to form a plurality
of different identifying patterns, as discussed above. At least one
of the identifying patterns is selected and at least two different
polymers are coextruded under conditions to provide a
multicomponent fiber having the selected identifying pattern.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)
[0017] Having thus described the invention in general terms,
reference will now be made to the accompanying drawings, which are
not necessarily drawn to scale, and wherein:
[0018] FIGS. 1A, 1B and 1C are transverse cross sectional views of
exemplary taggant fibers of the invention having an "islands in the
sea" construction; and
[0019] FIG. 2 is a transverse cross sectional views of another
exemplary taggant fiber of the invention also having an "islands in
the sea" construction.
DETAILED DESCRIPTION OF THE INVENTION
[0020] The present inventions now will be described more fully
hereinafter with reference to the accompanying drawings, in which
some, but not all embodiments of the invention are shown. Indeed,
these inventions may be embodied in many different forms and should
not be construed as limited to the embodiments set forth herein;
rather, these embodiments are provided so that this disclosure will
satisfy applicable legal requirements. Like numbers refer to like
elements throughout.
[0021] As used in the specification, and in the appended claims,
the singular forms "a", an "the", include plural referents unless
the context clearly dictates otherwise.
[0022] The term "fiber" as used herein means both fibers of finite
length, such as conventional staple fiber, as well as substantially
continuous structures, such as continuous filaments, unless
otherwise indicated. The fibers of the invention can be hollow
(including fibers with multiple discrete voids therein) or
non-hollow fibers, and further can have a substantially round or
circular cross section or non-circular cross sections (for example,
oval, rectangular, multi-lobed, and the like).
[0023] As used herein, the term "multicomponent fibers" includes
staple and continuous filaments prepared from two or more polymers
present in discrete structured domains in the fiber, as opposed to
blends where the domains tend to be dispersed, random or
unstructured. It should be understood that the scope of the present
invention is meant to include fibers with two or more structured
components. In a preferred embodiment, the two or more polymers
that form the multicomponent fiber are co-extruded using a
melt-spinning apparatus, meaning each polymer component is extruded
together in molten form through a spinneret in a predetermined
configuration to form the multicomponent fiber.
[0024] FIGS. 1A, 1B and 1C are transverse cross sectional view of
multicomponent fibers, designated generally as 10, 10', and 10",
respectively, representative of fibers of the present invention
having polymer domains with identifier characteristics that are
varied to form different identifying patterns or designs. The
different patterns or designs illustrated in FIGS. 1A, 1B and 1C
result from selecting specific combinations of polymer components
or domains to be present or absent available from a common fiber
structure.
[0025] Referring first to FIG. 1A, fiber 10 has a configuration
known generally in the art as an "islands in the sea" construction.
Generally islands in the sea fibers include a "sea" polymer domain
or component 12 surrounding a plurality of "island" polymer domains
or components 14. FIG. 1A illustrates an array of nine island
domains, although more or fewer island domains could be used, so
long as a sufficient number of island domains are available to
allow selection of various combinations thereof to be present or
absent to form the desired number of different identifying patterns
for individual fibers. For ease of discussion herein, each of the
individual island domains or components 14 has been assigned a
different letter designation, from "A" to "I." The cross sectional
configuration of the fiber of FIG. 1A can be prepared using methods
and fiber spinning apparatus as known in the art.
[0026] Sea component 12 generally forms the entire outer exposed
surface of the fiber, although the invention can also include fiber
constructions in which at least a portion of one or more of the
island domains also forms a part of the exposed surface of the
fiber. Sea domain or component 12 can be formed of any of the
polymers known in the art for the production of fibrous materials,
as discussed in more detail below. Generally such polymers are melt
extrudable, although the invention is not limited to the use of
melt extruded polymers. Island domains or components 14 can also be
formed of any of the types of polymers known in the art for fiber
production, but which are different from the sea polymer
domain.
[0027] FIG. 1B is a transverse cross sectional view of an islands
in the sea fiber 10', and also includes a sea polymer domain or
component 12' surrounding a plurality of island polymer domains or
components 14'.
[0028] Both fibers 10 and 10' are derived from a common
multicomponent fiber construction (namely, an islands in the sea
fiber having up to nine separate island components). The
illustrated pattern of island components 14' of fiber 10' is
different, however, from the pattern of island components 14 of
fiber 10. The specific pattern of fiber 10' is provided by
including some, but not all, of islands 14 of fiber 10 of FIG. 1A.
In this example, islands A, C, E, G, and I of fiber 10 are also
included in fiber 10'. Other of the island domains 14 of fiber 10
are excluded in fiber 10' (in this example, islands B, D, F, and H
are absent). To produce the fiber cross section of FIG. 1B, the
spinning apparatus is set up so that the island domain polymer flow
paths form a fiber with only five of the nine island domains
present in the desired locations. Again, the skilled artisan will
appreciate that more or fewer of the island domains can be present
in a given fiber.
[0029] The skilled artisan will appreciate that the invention is
not limited to the selection of the specific islands illustrated in
FIGS. 1A and 1B. Islands 14 of fiber 10 can also be present or
absent in other combinations to provide further variations of the
pattern shown in fiber 10. In this way a series or collection of
different fiber constructions can be derived from a common fiber
structure. FIG. 1C is provided as yet a further example of the
numerous and various patterns that can be achieved by selecting
different combinations of components to be present or absent in a
particular fiber derived from a common fiber structure. In this
example, fiber 10" includes island components 14" (I, E, and F
remain) within a sea polymer 12". The other possible islands
available for inclusion (A, B, C, D, G, and H) are absent in this
particular structure.
[0030] Thus, in one embodiment, the present invention provides a
plurality of uniquely identifiable islands in the sea
multicomponent fibers, each fiber cross section characterized by
one of a predetermined number of uniquely identifiable patterns
created by the relative position of an array of island domains,
wherein each uniquely identifiable pattern is determined by the
presence or absence of individual island domains. In the simplest
embodiment, each island domain is identical in all visible respects
except for relative placement within the matrix or sea polymer
(i.e., each island domain has the same cross sectional shape,
color, and the like) such that the number of island domains
determines the number of uniquely identifiable patterns that can be
created by the array of island domains. In essence, each pattern of
island domains is created by turning individual island domains "on"
or "off" in the array. Such a unitary fiber design is particularly
advantageous due to the ease in which individual patterns can be
created with relatively minor modifications to the fiber-forming
apparatus in order to adjust polymer flow paths such that
individual islands will be present or absent as desired. Thus,
switching between individual patterns can be accomplished
relatively quickly and without expensive equipment
modification.
[0031] In another embodiment, the number of patterns that can be
produced by the plurality of island domains will depend on both the
total number of island domains and the presence of additional
identifying features, such as particular colors or shapes, which
can increase the total number of patterns that are possible.
[0032] In yet another embodiment, the present invention provides a
plurality of uniquely identifiable multicomponent fibers, each
fiber cross section characterized by one of a predetermined number
of uniquely identifiable patterns created by the relative position
of an array of protrusions or bumps on the periphery of one or more
island domains, wherein each uniquely identifiable pattern is
determined by the presence or absence of individual protrusions on
the periphery of the island domain(s). In essence, each pattern is
created by turning individual protrusions "on" or "off" in the
array.
[0033] FIG. 2 is a transverse cross sectional view of another
exemplary multicomponent fiber, designated generally as 20, useful
in the present invention. Multicomponent fiber 20 is also an
"islands in the sea" fiber including a "sea" polymer domain or
component 22 surrounding a plurality of "island" polymer domains or
components 24. FIG. 2 illustrates a variation of the fibers
constructions of FIGS. 1A, 1B, and 1C, in which the fiber of the
invention can include at least one component having a distinctive
cross sectional feature, for example shape, that is different from
that of other of the polymer domains or components. This difference
can impart an additional identifier feature to an individual
fiber.
[0034] For example, an islands in the sea fiber, such as that
illustrated in FIG. 2, can include one or more island domains that
differ in some respect from other of the island domains. One or
more island domains can differ from other of the island domains,
for example, with regard to polymer composition, location, size,
shape, color and the like. As a non-limiting example, FIG. 2
illustrates an island domain or core 26, which differs in shape and
location from the other of the island domains 24. Core 26 can be
substantially centrally located as illustrated, although the
invention also contemplates eccentrically located cores. Core 26
can also be formed of any suitable fiber-forming polymer. Although
not illustrated, a series or collection of different fiber
constructions based upon fiber 20 can be derived in a manner
similar to that as described above with respect to FIGS. 1A, 1B and
1C, by selecting different combinations of domains or components 24
and/or 26 to be present or absent in a particular fiber
construction, and/or by varying the unique cross sectional shape of
core 26 or the cross sectional shape of one or more of island
domains 24.
[0035] In another embodiment of the invention, one or more of the
individual island domains shown in the appended figures can be
replaced with voids by utilizing a soluble polymer component to
form one or more of the island domains. As would be understood in
the art, a solvent extraction technique can be used to remove the
soluble polymer component at any point following fiber formation.
For example, one or more island domains could be formed from a
polymer that is soluble in an aqueous caustic solution such as,
without limitation, polyglycolic acid (PGA), polylactic acid (PLA),
polycaprolactone (PCL), and copolymers or blends thereof. In
another embodiment, the island domains could be formed form a
polymer that is soluble in water at a temperature of 70.degree. C.
or above such as, without limitation, sulfonated polyesters (e.g.,
sulfonated polyethylene terephthalate), polyvinyl alcohol,
sulfonated polystyrene, and copolymers or polymer blends containing
such polymers. A commercially available example of a sulfonated
polyester is the Eastman AQ line of copolyesters, such as Eastman
AQ 55S.
[0036] Other structured fiber configurations as known in the art
can also be used, so long as the structured fiber domains or
components provide a pattern or design to the fiber when viewed in
cross section so as to impart an identifier feature thereto,
thereby rendering the fibers useful for the production of taggant
materials. The cross section of the fiber is typically circular,
since the equipment typically used in the production of synthetic
fibers normally produces fibers with a substantially circular cross
section. However, the fibers of the invention are not limited to
those with a circular cross section.
[0037] Another suitable multicomponent fiber construction includes
sheath core fibers that include one or more inner core polymer
domains and a surrounding sheath polymer domain. In the present
invention, the sheath is generally continuous, e.g., completely
surrounds the core and forms the entire outer surface of a sheath
core fiber, but this is not required. In addition, the core domain
can be substantially concentric, or alternatively, the core can be
eccentric. The fibers of the invention also include multilobal
fibers having three or more arms or lobes extending outwardly from
a central portion thereof. Such multilobal fibers can also include
a substantially centrally located core component, which can be
concentric or eccentric. Side-by-side fibers comprising two polymer
domains adjacent to one another, with each polymer domain forming a
portion of the outer surface of the fiber, can also be used in the
invention. In one embodiment of the invention, the interface
between the two polymer components of the side-by-side fiber can
provide an identifying characteristic, such as a certain shape,
that can be used as a distinguishing feature of the fiber.
[0038] Any of these or other multicomponent fiber constructions may
be used, so long as the polymer domains are configured so as to
impart the desired pattern to the fiber when viewed in cross
section and thus to provide an identifier functionality to the
fiber, particularly when sectioned to form multicomponent fiber
taggants. Island polymer domains can also be incorporated into any
of the multicomponent fiber configurations described above, such as
sheath/core fibers (wherein the island domains can be in the sheath
and/or the core sections) or side-by-side fibers (wherein the
domains can be in one or both of the adjacent polymer domains).
[0039] When present, a core domain or component can be either
concentric or eccentric. Generally centrally located domains are
substantially or completely surrounded by an encapsulating polymer
domain having a generally uniform thickness. This is in contrast to
an eccentric configuration, in which the thickness of any
surrounding polymer domain surrounding and encapsulating the core
varies so that the core domain or component does not lie in the
center of the fiber. Concentric multicomponent fibers can be
defined as fibers in which the center of the core component is
biased by no more than about 0 to about 20 percent, preferably no
more than about 0 to about 10 percent, based on the diameter of the
multicomponent fiber, from the center of the surrounding or
encapsulating domain.
[0040] The polymer domains of the multicomponent fibers of the
invention can be selected from any of the types of polymers known
in the art that are capable of being formed into fibers, including
polyolefins, polyesters, polyamides and the like. Examples of
suitable polymers useful in the practice of the present invention
include, without limitation, polyolefins including polypropylene,
polyethylene, polybutene, and polymethyl pentene (PMP), polyamides
including nylon, such as nylon 6 and nylon 6,6, polyacrylates,
polystyrenes, polyurethanes, acetal resins, polyvinyl alcohol,
polyesters including aromatic polyesters, such as polyethylene
terephthalate, polyethylene naphthalate, polytrimethylene
terephthalate, poly(1,4-cyclohexylene dimethylene terephthalate)
(PCT), and aliphatic polyesters such as polylactic acid (PLA),
polyphenylene sulfide, thermoplastic elastomers, polyacrylonitrile,
cellulose derivatives, acetals, fluoropolymers, copolymers and
terpolymers thereof and mixtures or blends thereof.
[0041] The weight ratio of the respective polymeric components of
the fibers of the invention can vary. For example, in bicomponent
fibers, the weight ratio of the polymeric components can range from
about 10:90 to 90:10. In other examples the weight ratio of the
polymeric components can range from about 30:70 to about 70:30 and
from about 25:75 to about 70:25.
[0042] The polymeric components of the multicomponent fibers of the
invention can optionally include other components or materials not
adversely affecting the desired properties thereof. Exemplary
materials that can be present include, without limitation,
antioxidants, stabilizers, surfactants, waxes, flow promoters,
solid solvents, particulates, and other materials added to enhance
processability or end-use properties of the polymeric components.
Such additives can be used in conventional amounts.
[0043] One or more of the polymer domains of the multicomponent
fibers of the invention can optionally include one or more
colorants as known in the art as an additional identifier feature.
For example, useful colorants include luminescent colorants, such
as fluorescent colorants, phosphorescent colorants, and mixtures
thereof. Numerous types of phosphorescence and fluorescence
colorants are known, and include without limitation
photoluminescence colorants, electroluminescence colorants,
chemiluminescence (i.e., luminescence resulting form a chemical
reaction); bioluminescence (i.e., luminescence resulting from a
living organism typically mediated by enzymatic or other biological
system); and triboluminescence (i.e., luminescence resulting from
friction such as by crushing, rubbing or scratching a crystal). Any
of the types of colorants known in the art can be used in
conventional amounts.
[0044] Methods for making multicomponent fibers are well known and
need not be described here in detail. Generally the multicomponent
fibers of the invention are prepared using conventional
multicomponent textile fiber spinning processes and apparatus and
optionally utilizing mechanical drawing techniques as known in the
art. Processing conditions for the melt extrusion and
fiber-formation of fiber forming polymers are well known in the art
and may be employed in this invention.
[0045] To form the multicomponent fiber of the invention, at least
two polymers are melt extruded separately and fed into a polymer
distribution system wherein the polymers are introduced into a
spinneret plate. The polymers follow separate paths to the fiber
spinneret and are combined in a spinneret hole. The spinneret is
configured so that the fiber has the desired shape.
[0046] An exemplary fiber spinning apparatus useful for producing
the multicomponent fibers of the invention with polymer domains
designed to have specified patterns as identifiers is described in
U.S. Pat. No. 6,361,736, issued Mar. 26, 2002, the entire
disclosure of which is hereby incorporated by reference. This
spinning apparatus generally includes a distribution plate for
distributing flowable material in a direction perpendicular to the
spinning direction and a metering plate positioned downstream of
the distribution plate and likewise oriented perpendicular to the
spinning direction. The distribution plate contains at least one
flow path which is in fluid flow connection with at least one exit
hole. The metering plate contains one or more orifices which are
desirably positioned immediately downstream of an exit hole of the
distribution plate.
[0047] The orifices in the metering plate are adapted to moderate
the pressure of a material flowing from an exit hole of the
distribution plate through the metering plate. For example, the
metering plate can be positioned downstream of the distribution
plate so that plural orifices of the metering plate are immediately
downstream of each of the distribution plate exit holes. In
addition, the diameter of at least a portion of the metering plate
orifice can also be smaller than the diameter of the distribution
plate exit hole so that it moderates the pressure of a material
flowing from the distribution plate through the metering plate,
thereby providing a flow of material to a downstream spinneret at a
relatively more consistent pressure.
[0048] The distribution plate holes can be "shaped" (i.e.,
non-circular) to produce multicomponent fibers of the invention
having selectively shaped regions of specific components as
described above. Similarly, the flow paths can assume any
configuration chosen by the plate designer to achieve the desired
fiber shape, composition and cross-section, and can be of greater
complexity than practicable using prior art spin pack assemblies,
as will be readily recognized by those having ordinary skill in the
art.
[0049] Because the spinning apparatus can serve to equilibrate the
pressure of the flow of a plurality of flowable materials, the
apparatus can allow production of intricate and/or precisely shaped
components, such as the crescent shaped core of FIG. 2 above. To
this end, advantageously the polymer stream exiting the
distribution flowpath through multiple metering orifices affords a
high degree of precision in feeding the polymer stream to the
spinneret backhole. This can allow production of a plurality of
flowable material streams that collectively substantially maintain
the shape of the stream exiting the distribution plate.
[0050] The present invention allows the ready manufacture of
multicomponent fibers having different cross sectional patterns by
proper selection of polymer flow distribution plates in the spin
pack. In this regard, a particular multicomponent fiber cross
sectional pattern or design can be selected, and the spinning
apparatus can be readily set up to make fibers with the selected
pattern by addition or removal of appropriate polymer distribution
plates. In this way a large number of multicomponent fibers, each
with a different cross sectional pattern or design, can be readily
and economically manufactured.
[0051] Following extrusion through the die, the resulting thin
fluid strands, or filaments, remain in the molten state before they
are solidified by cooling in a surrounding fluid medium, which may
be chilled air blown through the strands, or ambient air, or
immersion on a bath of liquid such as water. Once solidified, the
filaments are taken up on a godet or another take-up surface. In a
continuous filament process, the strands are taken up on a godet
which draws down the thin fluid streams in proportion to the speed
of the take-up godet.
[0052] Generally the thin fluid streams are drawn down in a molten
state, i.e., before solidification occurs to orient the polymer
molecules for good tenacity. Typical melt draw down ratios known in
the art may be utilized. Where a continuous filament or staple
process is employed, it may be desirable to draw the strands in the
solid state with conventional drawing equipment, such as, for
example, sequential godets operating at differential speeds.
[0053] Following drawing in the solid state, the continuous
filaments may be crimped or texturized and cut into a desirable
fiber length, thereby producing staple fiber. The length of the
staple fibers generally ranges from about 25 to about 75
millimeters, although the fibers can be longer or shorter as
desired.
[0054] The fibers of the invention can be staple fibers or
continuous filaments. In general, staple fibers and continuous
filaments formed in accordance with the present invention can have
a fineness of about 0.5 to about 100 denier.
[0055] Advantageously the fibers or filaments are directed to a
suitable apparatus as known in the art to form a yarn or tow of the
fibers or filaments, which can be optionally crimped. The resultant
yarn and/or tow can include a plurality of multicomponent fibers in
accordance with the present invention in which each of the fibers
has the same identifier pattern when viewed in cross section. Other
types of fibers or filaments, however, can also be present in the
yarn.
[0056] The filament yarn or tow prepared according to the present
invention can comprise a plurality of multicomponent fibers
according to the invention wherein each fiber has the same
identifying characteristic, such as the same cross sectional
pattern. Alternatively, the filament yarn or tow may comprise a
plurality of multicomponent fibers wherein each fiber exhibits a
uniquely identifiable pattern as compared to each of the remaining
fibers in the yarn or tow. In this manner, a large number of
uniquely identifiable fibers can be formed quickly and efficiently
by simultaneously coextruding the plurality of fibers through the
same spinneret. For example, the filament yarn or tow may comprise
a plurality of fibers, wherein the cross section of each fiber is
visually distinguishable from the remaining fibers within the yarn
or tow, each fiber comprising a uniquely identifiable cross
sectional pattern of island domains, each pattern being formed from
an array of a predetermined number of island domains in
predetermined locations within the array, wherein each pattern is
determined by classifying individual island domains within the
array as present or absent from the pattern. In another example,
each individual filament of the yarn or tow has a fiber cross
section characterized by one of a predetermined number of uniquely
identifiable patterns created by the relative position of an array
of protrusions or bumps on the periphery of one or more island
domains, wherein each uniquely identifiable pattern is determined
by the presence or absence of individual protrusions on the
periphery of the island domain(s). Thus, where the desired taggant
will comprise more than one fiber cross section having a uniquely
identifiable feature, the present invention provides a convenient
and efficient method of producing the multiple fibers that will be
used together as the taggant.
[0057] In a further embodiment, a collection of fibers is provided
by the invention, wherein the collection of fibers comprises two or
more subsets of fibers, each subset of fibers characterized by a
fiber cross section that is uniquely identifiable as compared to
each of the other subsets of fibers. Each subset of fibers within
the collection can be meltspun separately and then collected.
Alternatively, the entire collection of fibers can be derived from
the same filament yarn or tow. In this manner, a relatively small
number of fiber cross sections can be selected and manufactured
quickly and efficiently in a single processing run with a single
filament yarn or tow. For example, if a particular fiber cross
section design has 12 possible uniquely identifiable patterns, but
only 2 of the patterns are desired, a single filament yarn or tow
can be formed that includes a first subset of fibers characterized
by the first desired cross section pattern and a second subset of
fibers characterized by the second desired cross section pattern,
the two subsets forming the entire filament yarn or tow. As would
be appreciated, the number of subsets can be varied as desired
depending on the desired number of patterns. Each subset may
comprise one or more individual filaments, preferably a plurality
of individual filaments.
[0058] The present invention also provides a set of a plurality of
distribution plates for use in a melt-spinning apparatus, wherein
the set of distribution plates are configured to form a common
multicomponent fiber cross section design exhibiting at least one
identifying characteristic that can be varied to form a plurality
of different identifying patterns. The plurality of distribution
plates can be manipulated in order to change the identifying
characteristic and thereby form a variety of identifying patterns.
For example, one or more distribution plates could be exchanged in
the melt-spinning apparatus, or the relative placement of one or
more distribution plates could be modified, such that a new
identifiable pattern is formed in the multicomponent fiber cross
section. The set of distribution plates are useful for providing a
means for quickly and efficiently changing the fiber cross section
in a manner that alters the identifiable characteristics of a fiber
or a subset of fibers within a filament yarn or tow.
[0059] The multicomponent fibers and/or yarns including the same
are suitable for the production of taggant materials for
identification and/or security applications and can be incorporated
in any suitable manner into a product to be tagged. For example,
the fibers and/or yarns and/or tows including the same can be
included as is in the product to be tagged, for example, by
knitting or weaving the fiber, yarn, and/or tow into a fabric.
Alternatively a portion of the fiber, yarn and/or tow can be
removed from the fiber using suitable techniques and incorporated
into the product to be tagged. For instance, the fiber may be cut
into very short lengths and dispersed in or adhered to the product
or material to be tagged.
[0060] The multicomponent fibers and/or yarns and/or tows of the
invention can be useful in providing taggant materials for
identifying many types of materials or objects, including without
limitation bulk materials (e.g., fertilizer, chemicals, paints,
oils, plastics, pigments, clays, fertilizers, explosives, etc.),
prepackaged materials (e.g., shampoo, conditioner, lotion, motor
oils, pharmaceuticals, etc.) and individual product units (e.g.
stereos, cameras, computers, VCRs, furniture, motorized vehicles,
livestock, etc.). This can allow a user to trace products diverted
from their intended distribution routes, to identify the
manufacturer and/or distributor of a product, to identify a given
batch of a product, and the like. The multicomponent fibers and/or
yarns and/or tows of the invention can also provide taggants useful
for authentication, for example, to authenticate the genuine nature
of a given product to combat counterfeiting, for warranty purposes,
and the like. The multicomponent fibers and/or yarns and/or tows of
the invention can also be useful as taggants in law enforcement and
other arenas, for example, as identifiers for evidence materials,
high security documents, tracing of hazardous materials and
explosives, and the like. The present invention also includes
products or materials including the fibers and/or portions thereof
dispersed in, adhered to, or otherwise incorporated therein. It is
preferable for the uniquely identifying characteristic of each
fiber cross section prepared according to the invention to be
readable by a machine vision system, meaning a machine vision
system can discern one pattern from another.
[0061] Many modifications and other embodiments of the inventions
set forth herein will come to mind to one skilled in the art to
which these inventions pertain having the benefit of the teachings
presented in the foregoing descriptions and the associated
drawings. Therefore, it is to be understood that the inventions are
not to be limited to the specific embodiments disclosed and that
modifications and other embodiments are intended to be included
within the scope of the appended claims. Although specific terms
are employed herein, they are used in a generic and descriptive
sense only and not for purposes of limitation.
[0062] The following examples are provided to illustrate certain
embodiments of the invention and are not intended to limit the
scope of the invention as defined by the appended claims.
EXAMPLE 1
[0063] In a multicomponent fiber spinning apparatus as described in
U.S. Pat. No. 6,361,736, which is incorporated by reference in its
entirety, distribution plates and metering plates were formed so as
to produce a round cross section fiber with twelve round "island"
polymer domains in a "sea" polymer domain, said twelve island
domains positioned around the perimeter of the fiber and
surrounding a central core comprising an additional domain of the
"island" polymer, said core being predominantly circular but having
a substantial indentation as well as a fully-enclosed domain
comprising the "sea" polymer, such that the shaped core resembled a
"Pac-Man" shape similar to that of the computer game character.
Plasticized polyvinyl alcohol was extruded through the distribution
plate channels to form the "sea" polymer domains, and polylactic
acid was extruded through the distribution plates to form the
"island" polymer domains. The fiber was melt extruded through 175
round-hole spinneret capillaries, solidified (quenched) in a
transverse stream of air, taken up on godets and wound onto a
bobbin. The resulting fibers were then cut into very short lengths
and adhered to a number of different products, where they were
analyzed by a microscopic machine vision system capable of
identifying the number and position of the twelve islands in the
cross section.
EXAMPLE 2
[0064] In the same spinning apparatus as used in Example 1, a
single distribution plate was replaced by a new distribution plate
that prevented the "island" polymer from flowing into position for
three of the twelve circumferential islands formed in the fiber of
Example 1. In all other respects, the production of the fiber was
identical to that of the fiber of Example 1. The resulting fiber's
cross section had the same shaped core domain, and had "island"
polymer domains in the same positions as in Example 1, in the case
of only nine of the twelve "islands," whereas only "sea" polymer
was present where the missing three "islands" appeared in the fiber
of Example 1. This fiber was also subsequently cut into short
lengths and adhered to products, where they were analyzed by the
same machine vision system, which was able to distinguish the cross
section of these fibers from those of Example 1 by virtue of the
number and position of the missing islands.
EXAMPLE 3
[0065] The fibers of Examples 1 and 2 were alternately processed
with a step that exposed the fibers to water, which dissolved and
removed the polyvinyl alcohol "sea" component. As a result, the
twelve and nine (respectively) "islands" were dissociated from the
shaped core, and the "eye" of the shaped core was made hollow.
Without the association of the twelve or nine (respectively)
islands with the core, the fibers lost their ability to be
distinguished by the machine vision system.
EXAMPLE 4
[0066] In a multicomponent fiber spinning apparatus as described in
U.S. Pat. No. 6,361,736, distribution plates and metering plates
were formed so as to produce a round cross section fiber with a
central first polymer domain enclosing a single "island" domain of
a second polymer. A sheath of the second polymer also encloses the
first polymer domain. The distribution and metering plates were
formed to further modify the first polymer domain so as to contain
twelve peripheral indentions, the indentions being filled with the
second polymer. One of the twelve indentions was substantially
deeper than the other eleven. The distribution plates were formed
so that by replacing a single plate with a plate of minor design
difference, flow of the second polymer to the position of any one
or any combination of the peripheral indentions would be impeded,
thereby resulting in a fiber cross section with the corresponding
indention(s) missing. Polylactic acid was extruded through the
distribution plate channels to form the first polymer domain, and
plasticized polyvinyl alcohol was extruded through the distribution
plates to form the second polymer domains, namely the single island
within the first polymer domain, the twelve peripheral indentions,
and the outer sheath of the fiber. The fiber was melt extruded
through 175 round-hole spinneret capillaries, solidified (quenched)
in a transverse stream of air, taken up on godets, and wound onto a
bobbin. The resulting fibers were then cut into very short lengths
and adhered to a number of different products, where they were
analyzed by a microscopic machine vision system capable of
identifying the number and position of the twelve indentions in the
fiber cross section.
EXAMPLE 5
[0067] The fibers of Example 4 were alternately processed with a
step that exposed the fibers to water, which dissolved and removed
the polyvinyl alcohol polymer. The resulting fiber cross section
includes the central core of polylactic acid, with a hollow island
formed therein, wherein the core of polylactic acid has a serrated
circumference comprising twelve indentations (i.e., a series of
protrusions are present around the periphery thereof). Particles of
this fiber cut to very short length were adhered to a number of
different products and analyzed by a machine vision system capable
of identifying the presence and position of each of the twelve
indentations, thereby rendering this fiber more suitable than that
of Example 3 for applications involving exposure to water.
* * * * *