U.S. patent application number 14/302050 was filed with the patent office on 2015-12-17 for antimicrobial multicomponent synthetic fiber and method of making same.
The applicant listed for this patent is Noble Fiber Technologies, LLC. Invention is credited to Greg Gianforcaro, Jeffrey Keane, Jon Pavlansky.
Application Number | 20150361595 14/302050 |
Document ID | / |
Family ID | 54835678 |
Filed Date | 2015-12-17 |
United States Patent
Application |
20150361595 |
Kind Code |
A1 |
Keane; Jeffrey ; et
al. |
December 17, 2015 |
Antimicrobial Multicomponent Synthetic Fiber and Method of Making
Same
Abstract
A method of producing synthetic threads and yarns which utilize
a multicomponent structure having silver in an external sheath. The
threads and yarns are then texturized via a false-twist process to
increase the amount of silver available at the exterior surfaces of
the threads and yarns. The resultant yarns and threads are also
provided.
Inventors: |
Keane; Jeffrey; (Darien,
CT) ; Pavlansky; Jon; (Yadkinville, NC) ;
Gianforcaro; Greg; (Clemson, SC) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Noble Fiber Technologies, LLC |
Scranton |
PA |
US |
|
|
Family ID: |
54835678 |
Appl. No.: |
14/302050 |
Filed: |
June 11, 2014 |
Current U.S.
Class: |
57/232 ; 57/255;
57/7 |
Current CPC
Class: |
D01F 1/103 20130101;
D01F 8/12 20130101; D01F 8/14 20130101; D02G 3/449 20130101; D02G
1/022 20130101 |
International
Class: |
D02G 3/44 20060101
D02G003/44; D02G 1/02 20060101 D02G001/02; D02G 3/04 20060101
D02G003/04; D02G 3/36 20060101 D02G003/36; D01F 8/14 20060101
D01F008/14; D01F 8/12 20060101 D01F008/12 |
Claims
1. A multi-component filament comprising: a core; and a sheath,
said sheath surrounding said core and including antimicrobial
particles therein; wherein said filament has been texturized by a
false-twist process, said false-twist process increasing the amount
of antimicrobial accessible at an exterior surface of said
sheath.
2. The filament of claim 1 wherein said core comprises Nylon.
3. The filament of claim 1 wherein said sheath comprises Nylon.
4. The filament of claim 1 wherein said core comprises
polyester.
5. The filament of claim 1 wherein said sheath comprises
polyester.
6. The filament of claim 1 wherein said antimicrobial particles
comprise silver metal.
7. The filament of claim 1 wherein said antimicrobial particles
comprise silver glass.
8. The filament of claim 7 wherein said silver glass comprises
glass particles coated with silver.
9. The filament of claim 7 wherein said silver glass comprises
glass particles including silver nitrate.
10. A filament bundle comprising a plurality of filaments of claim
1
11. A filament bundle comprising: a plurality of filaments, each of
said filaments comprising: a core; and a sheath, said sheath
surrounding said core and including antimicrobial particles
therein; wherein said filament bundle has been texturized by a
false-twist process to increase the amount of antimicrobial
accessible by a fluid in exterior surface contact with said
filament bundle.
12. The filament bundle of claim 11 wherein said core comprises
nylon.
13. The filament bundle of claim 11 wherein said sheath comprises
nylon.
14. The filament bundle of claim 11 wherein said core comprises
polyester.
15. The filament bundle of claim 11 wherein said sheath comprises
polyester.
16. The filament bundle of claim 11 wherein said antimicrobial
particles comprise silver metal.
17. The filament bundle of claim 11 wherein said antimicrobial
particles comprise silver glass.
18. The filament bundle of claim 17 wherein said silver glass
comprises glass particles coated with silver.
19. The filament bundle of claim 17 wherein said silver glass
comprises glass particles including silver nitrate.
20. A method of metalizing a synthetic filament bundle, the method
comprising: providing a plurality of synthetic filaments, each of
said filaments comprising: a core; and a sheath, said sheath
surrounding said core and including silver particles therein;
texturized said filament bundle by a false-twist process to
increase the amount of silver accessible by a fluid in exterior
surface contact with said filament bundle.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This disclosure is related to the field of antimicrobial
fibers, threads, and yarns. Particularly to antimicrobial
multicomponent filament and filament bundles utilizing polymer
materials in a multi-component construction.
[0003] 2. Description of the Related Art
[0004] The world is full of microorganisms and while many of these
are beneficial, or even necessary, for human survival, a large
number are, in fact, detrimental and downright dangerous to humans.
It has long been recognized that a large number of human maladies
can be traced to microorganisms and specifically viruses and
bacteria. Maladies such as influenza, malaria, staphylococcus
(staph), athlete's foot, and even the common cold can be traced to
microorganisms or antigens acting on the human body. Further, even
more common conditions such as body odor can be traced to
microorganisms. The primary issue encountered with microorganisms
is that they are everywhere and it is often difficult to separate
the good from the bad. This can be particularly true in situations
where the human body is at an increased risk for infection. This
can occur when the skin is broken (either by accident, or
purposefully such as in surgery) or where a human has a decreased
immune response due to age, immunosuppressant drugs, or other
conditions.
[0005] The human immune system is incredibly effective at
destroying dangerous microorganisms and supplies a multitude of
different responses and attacks when the body is invaded by a
non-recognized microorganism. However, even with this powerful
response, there are microorganisms that the body can, and regularly
does, miss. There is also the issue that while the body may respond
to the presence of an antigen, the body may be unable to react fast
enough to prevent the human host from suffering permanent injury or
death.
[0006] In order to assist the body in the destruction of harmful
microorganisms, a variety of things are used. Many of these are
antibacterial compounds which target specific features of bacteria
to kill them off. These are commonly used in conjunction with the
human immune response to result in bacterial death. A concern with
antibacterials is that while antibacterials can be very effective,
they can have the side-effect of allowing bacteria to evolve which
are immune to particular antibacterials. For this reason, they are
commonly used sparingly.
[0007] Another classification of assistance devices are
antimicrobials. Antimicrobials, and specifically, non-specific
antimicrobials, have a major advantage over most antibiotics and
other antigen specific responses in that they often have a much
greater lethality which can readily prevent the spread of resistant
bacteria. Certain antimicrobials (such as chlorine bleach) are so
effective that they are readily accepted in widespread use.
[0008] Silver metal, silver nitride, and other forms of silver
which act as a source for silver ions, can be effective
non-specific antimicrobials. It is understood that the silver ion
deactivates structural and metabolic membrane proteins, which will
lead to microbial death and many microbes view certain forms of
silver as a food source, allowing the silver ion to enter the
microbe easier. The incorporation of silver and certain other
antimicrobial materials into a variety of products has, therefore,
become increasingly commonplace. One problem with silver as an
antimicrobial, however, is that it is relatively expensive, and, in
order to be effective, the silver particle (or silver ion) needs to
be capable of being in contact with the microbe.
[0009] One area where silver is seeing increased use is in fabrics
and textiles. This can include such mundane uses as in socks or
undergarments in order to destroy odor causing microbials, or in
wound dressings where the human immune response is being given an
aid in inhibiting dangerous microbes from entering the human body
and potentially causing complications from an injury or medical
procedure.
[0010] Traditionally, in order to provide for silver textiles, the
textile thread or resultant textile product is essentially soaked
in silver particles or otherwise coated with a thin film of metal.
This film adheres to the thread or textile through a variety of
forces such as electrostatics or by becoming wedged in small
openings. While this is effective to get silver into the fabric
and/or thread, it has a number of downsides. The most major of
which is that the presence of silver can result in a discoloration
or other modification of the fabric. For example, coating a thread
with silver will generally make a silver thread. This can be
visible in a resultant article of manufacture which may be
undesirable.
[0011] A further problem with post-manufacture silver exposure is
that the silver may be washed away by necessary exposure or
laundering. For example, fabric or yarn that has been impregnated
with silver may have the silver particles held within spaces or
channels of the fabric or yarn. If the fabric or yarn is then used
to absorb a liquid to expose the liquid to the antimicrobial
silver, the liquid also competes to occupy the same space and
channels and may knock the silver particles loose so that they free
float in the liquid. In some applications, this may be perfectly
acceptable, but for other ones it can result in displacement of the
silver to a location where it's effect is lessened and can result
in the antimicrobial effect being decreased with use, such as
through repeated laundering.
[0012] In order to improve their holding power for silver, some
threads are manufactured with silver particles placed directly into
the material prior to thread formation. While this does not work
for many natural threads unless the silver is spun into the thread
with the fibers, it can work for a variety of synthetic polymer
threads such as polyester and Nylon where small particles of silver
are added to the polymer melt from which the original filaments are
extruded and then spun into filament bundles. This allows for the
silver to actually be contained as a part of the thread itself
which inhibits it from separating from the fabric made from the
thread.
[0013] While this internal assembly provides for a number of
benefits, it also creates some additional problems. For one, the
silver is expensive compared to the polymer and it must end up in
physical contact with material to which the fabric is in contact to
be effective. In many cases, where particularly small silver
particles are used, the silver may be small enough to be entirely
encased within the thread. In this case, the silver particle
provides no benefit. This effect is obviously increased as smaller
particles relative the size of the thread are used. However, with
larger particles, the thread may have less structural integrity,
the silver itself has less available surface area (nullifying cost
benefits), and the thread may be unsuitable for particular
tasks.
[0014] In manufacturing antimicrobial threads which will be formed
into antimicrobial fabrics, there is a benefit to maximizing the
surface exposure of silver on the thread and minimizing the amount
of silver that is entirely within the thread. For polymer threads
which are manmade, this can be accomplished through the process of
co-extrusion.
[0015] In co-extrusion, the filament is made from two different
materials. One of these materials includes silver, while the other
does not. The latter is used as the core of the material to provide
much of the strength and volume, while the other is used to
maximize surface exposure. Some such arrangements are described in
U.S. patent application Ser. No. 13/006,686, the entire disclosure
of which is herein incorporated by reference. In this case, silver
contact can be maximized while reducing the amount of silver used
in the resultant thread as non-reactive components do not include
any silver.
[0016] While these types of threads offer some potentially
significant reductions in silver usage (and thus cost of
manufacture) they can still have problems. In the first instance,
the silver exposure is not necessarily maximized as some silver is
still encased in the body of the sheath. Secondly, the silver
presence can often result in the discoloration of the underlying
thread. For example, the presence of significant amounts of silver
in Nylon threads can result in the Nylon thread yellowing. This can
result in in not being able to hold dyes as well and resulting in a
less attractive thread and product. This can in turn mean that the
total amount of silver used is reduced.
SUMMARY OF THE INVENTION
[0017] The following is a summary of the invention, which should
provide to the reader a basic understanding of some aspects of the
invention. This summary is not intended to identify critical
elements of the invention or in any way to delineate the scope of
the invention. The sole purpose of this summary is to present in
simplified text some aspects of the invention as a prelude to the
more detailed description presented below.
[0018] Described herein, among other things, is an extruded
filament which comprises a polymer core and sheath where the core
is substantially free of silver and the sheath includes silver.
Filament bundles formed from the filaments, or the filaments
themselves, are texturized to force silver particles to the surface
of the sheath, and/or lightly damage the exterior surface of the
sheath, to embed the silver particles where their exposure to the
exterior surface is increased. This is particularly useful for
Nylon filaments but can be used in any polymer filament forming a
synthetic yarn. The filament bundles can also be texturized to open
the filament bundle further increasing silver exposure.
[0019] In an embodiment there is described herein a multi-component
filament comprising: a core; and a sheath, said sheath surrounding
said core and including antimicrobial particles therein; wherein
said filament has been texturized by a false-twist process, said
false-twist process increasing the amount of antimicrobial
accessible at an exterior surface of said sheath.
[0020] In an embodiment of the filament, the core comprises
Nylon.
[0021] In an embodiment of the filament, the sheath comprises
Nylon.
[0022] In an embodiment of the filament, the core comprises
polyester.
[0023] In an embodiment of the filament, the sheath comprises
polyester.
[0024] In an embodiment of the filament, the antimicrobial
particles comprise silver metal.
[0025] In an embodiment of the filament, the antimicrobial
particles comprise silver glass which may comprise glass particles
coated with silver or glass particles including silver nitrate.
[0026] In an embodiment, a plurality of the above filaments are
bundled together into a filament bundle or yarn.
[0027] There is also described herein a filament bundle comprising:
a plurality of filaments, each of said filaments comprising: a
core; and a sheath, said sheath surrounding said core and including
antimicrobial particles therein; wherein said filament bundle has
been texturized by a false-twist process to increase the amount of
antimicrobial accessible by a fluid in exterior surface contact
with said filament bundle.
[0028] In an embodiment of the filament bundle, the core comprises
nylon.
[0029] In an embodiment of the filament bundle, the sheath
comprises nylon.
[0030] In an embodiment of the filament bundle, the core comprises
polyester.
[0031] In an embodiment of the filament bundle, the sheath
comprises polyester.
[0032] In an embodiment of the filament bundle, the antimicrobial
particles comprise silver metal.
[0033] In an embodiment of the filament bundle, the antimicrobial
particles comprise silver glass which may be glass particles coated
with silver or glass particles including silver nitrate.
[0034] There is also described herein a method of metalizing a
synthetic filament bundle, the method comprising: providing a
plurality of synthetic filaments, each of said filaments
comprising: a core; and a sheath, said sheath surrounding said core
and including silver particles therein; texturized said filament
bundle by a false-twist process to increase the amount of silver
accessible by a fluid in exterior surface contact with said
filament bundle.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] FIG. 1 depicts an embodiment of a multicomponent filament,
specifically a bi-component filament, comprising a core and sheath
with silver particles or other sources of silver ions embedded in
the sheath.
[0036] FIG. 2 depicts an embodiment of a multicomponent filament,
specifically a bi-component filament, with silver particles in the
sheath where a yarn including the filament has been texturized to
expose additional silver.
[0037] FIG. 3 depicts an embodiment of a "fiber bundle" comprised
of multicomponent fibers with silver particles showing opening of
the bundle via texturing to expose additional silver.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
[0038] Because of problems in the art of forming yarns including
sources of silver ions, there are described herein multi-component
synthetic filaments including an antimicrobial such as a source of
silver ions which utilize texturizing to increase antimicrobial
exposure.
[0039] Texturizing is a process whereby partially oriented filament
yarn (commonly called POY) or Fully Drawn Yarn (FDY) is stabilized
through heating and drawing. This produces a crimped continuous
filament yarn or Draw Textured Yarn (DTY). All types of synthetic
yarns can be textured and polymer filaments and filament bundles
such as, but not limited to, Nylon and polyester, are typically
texturized with texturized Nylon used primarily in the production
of ladies' hosiery although it has become much more common in a
variety of other areas recently. Texturized polyester is used in
various apparel and home furnishings products and, to a lesser
extent, in industrial fabric. There are two types of common
texturizing machines. As understood by one of ordinary skill in the
art, the most common texturizing is provided by false-twist
texturizing machines which serve to both twist the yarn one
direction, and then twist it back. The resulting yarn is therefore
not "twisted" in the conventional sense, but has still undergone a
twisting process and that tends to emulate a real twisted or spun
yarn and provides some material memory to the yarn.
[0040] As discussed herein, the terms "thread", "yarn" , and
"fiber" are often used interchangeably although those terms are
often provided with specific meaning in the art. The reason for
this is because the process discussed herein can be used to produce
any of these items. For the most part, however, this disclosure
will focus on the production of "filaments", which will be
considered single strand synthetic fiber or polymer extrusions, and
"yarns" or "filament bundles" which are structures comprising a
number of filaments combined together. For example, filaments which
are spun or otherwise interconnected, entangled, or arranged
together form a filament bundle or yarn.
[0041] Filaments are generally formed by the melting of polymer
pellets or another source of polymer which is then forced through
an extrusion die to produce a continuous fiber. A filament can be a
single continuous extrusion, or may be a chopped apart extrusion
such as to form a staple. This fiber can then be texturized
directly (which is uncommon), or can be combined with other
filaments to form a filament bundle with the resultant filament
bundle can then be texturized.
[0042] It is important to recognize that the texturizing process's
effect on a yarn can be two-fold. It serves to both modify the
structure of the yarn itself (the relationship between filaments in
the bundle) and the structure of each filament. For this reason,
this disclosure discusses modification of the filament as occurring
on a single filament. While the modification may occur on a single
filament (e.g. a filament which is not in a filament bundle), this
disclosure contemplates that it may also occur on some or all of
the filaments within a filament bundle. Further, this disclosure
contemplates that the modifications to filaments within a filament
bundle may occur in different amounts or at slightly different
times depending on the nature of the texturing occurring and the
specific arrangement of filaments in the filament bundle
[0043] FIG. 1 provides for an embodiment of a polymer filament
(100), formed from a synthetic material such as, but not limited
to, polyester, Nylon (polyamide 6 or polyamide 6,6), another
polymer or combinations thereof. The filament (100) generally has a
multicomponent structure including at least two, and potentially
more, distinct regions. In particular, the filament (100) of FIG. 1
comprises a bi-component filament formed from an inner core (101)
which is surrounded by an outer sheath (103) although side-by-side
(adjacent) structures and other shapes and structures, such as, but
not limited to, those that are not rounded in cross-section can
also be used.
[0044] These two components of the filament (100) are generally
formed by co-extrusion, although alternative manufacturing
techniques can be used in alternative embodiments. When formed via
co-extrusion, the inner core (101) is effectively extruded from a
first material supply while the sheath (103) is extruded
simultaneously, and in relative position to the core (101), from a
second material supply. Thus, it is possible to manufacture the
filament (100) from two different materials in a single step or
from two different sources of the same material. The materials used
will generally be synthetic polymers suitable for
thread-making.
[0045] In a preferred embodiment, the underlying polymer materials
will be the same, e.g. both the core (101) and sheath (103) will be
of the same polymer (e.g. polyester or Nylon) but this is by no
means required. Alternatively, the core (101) and sheath (103) will
generally comprise different materials. However, regardless of
their respective base materials, the material of the sheath (103)
will include an additive therein that is generally not present in
the material of the core, or is present in the core in a far
smaller percentage. The additive will comprise an antimicrobial
material and generally a particulate silver (301) material acting
as a source of silver ions. The silver (301) can be in metallic
form, or can be included within or on another material, but it
ultimately will be provided in the form of a generally solid
particulate. In an embodiment, the silver (301) is provided in the
form of silver glass. Generally, a majority of the material in the
multi-component filament will be in the core and the core may
comprise 50% or more, 60% or more, 70% or more, 80% or more or 90%
or more of the multi-component filament, but this is by no means
required.
[0046] Silver glass comprises small beads of glass which may either
be coated or partially coated with silver metal, or which may
include silver as a metal (either internally or as a coating) or as
a compound of silver, for example silver nitrate or nitride, within
their structure in such fashion that silver ions are available at
the glass surface and the silver glass acts as an antimicrobial.
Silver glass is a product well understood by those of ordinary
skill in the art and is available in a variety of sizes, shapes,
and compositions such as, but not limited to, products produced by
Potters Industries, LLC.
[0047] As can be seen in FIG. 1, upon extrusion, the silver
particles (301) will generally be positioned in one of three
positions. Firstly, some of silver (301A) will either be positioned
at the exterior surface (105) of the thread either extending
outward from the exterior surface, flush with the surface, or
otherwise in position that the silver ions can exit the exterior of
the thread. Depending on the form of silver (301) used and
properties of the polymer, this can allow the silver (301A) to be
below the level of the exterior surface (105), while still
providing exterior ions. The specific distance may depend on the
polymer's hydrophilicity (e.g. absorbency) with water.
[0048] Secondly, some of the silver (301B) will generally be
positioned entirely within the sheath (103). This silver (301B) is
not in contact with any surface of the sheath and sufficiently
internal that it generally cannot supply silver ions to a material
exterior of the sheath (103). Finally, some of the silver (301C)
will be in contact with the interior surface (113) of the sheath
and thus in contact with the core (101). In most cases, the silver
(301C) will not be entirely within the core (101) as the core
initially included no silver (301), but it is possible that a
significant percentage of the silver particle (301C) could extend
beyond the sheath (103) and either be located in a void between the
core (101) and sheath (103), or extend into the structure of the
core (101). When the filament (100) is formed by co-extrusion of
similar underlying materials, the later would be the expected case
as the dividing line (interior surface (113) of the sheath (103))
between the core (101) and the sheath (103) would generally not be
immediately clear.
[0049] As should be visible from FIG. 1, to the extent that this
filament (100) is to be used in an antimicrobial yarn or textile,
only the silver (301A) which is in the first position, that is
having at least a portion of this structure in ionic transfer with
something outside the exterior surface of the sheath (103), has any
chance of providing antimicrobial properties to the filament (100).
As the silver (301) would need to be able to transfer ions to the
microbes in order to kill them, silver (301B) and (301C) which is
buried within the filament (100) simply cannot have ion-transfer
with a microbe and thus cannot produce any significant
antimicrobial effect.
[0050] It should be apparent from the discussion of FIG. 1 that in
order to provide for a certain level of antimicrobial effect, a
certain amount of silver (301A) needs to be present at the exterior
surface (105) of the sheath (103). To the extent this needs to be
increased, the prior methodology was simply to increase the amount
of silver (301) present in the sheath (103) material. As this
amount went up, the amount at the exterior surface (105) would
necessarily increase proportionally.
[0051] The problem with simply increasing the amount of silver
(301) used is that silver (301), as a precious metal, is quite
expensive compared to the polymer making up the thread (100). Thus,
a need to increase the antimicrobial capacity of a thread (100)
three-fold could result in a significant extra expense since as
little as one-third of the silver (301) used may be present on the
outer surface. Further, if too much silver (301) was placed in the
sheath (103), the silver (301) could affect the properties of the
thread (100). Most notably, with Nylon threads, a greater
percentage of silver (301) could result in a discoloration of the
thread (100) with it tending to appear more yellow.
[0052] The discoloration can present a number of major problems. In
the first instance, it can make the thread (100) appear to be old
or brittle, which can lead to it being less marketable. In a second
instance, the silvered Nylon was often unable to take on dye as
well as white nylon and resulting colored threads or fabrics often
could not be provided with particular color combinations or
results. Because of this, most synthetic threads and yarns which
include silver are made from polyester. Silvered Nylon was
generally only produced by coating the Nylon in silver (giving it a
metallic silver color). While this is superb for certain
applications, it is not useable in a variety of others.
[0053] In the present arrangement, by having a reduced amount of
silver particles (301) in the sheath (103), and then by shrinking
the relative projection of the sheath (103) to the core (101) the
yellowing can be substantially reduced. In particular, Nylon is
generally semi-translucent, thus, as the sheath (103) is decreased
in proportional volume, its thickness is reduced allowing more
light to pass through and the core (101) to be more visible. As the
core (101) includes essentially no silver, its white appearance
(which can be changed or altered by dye) will serve to "whiten" the
filament (100) as a whole.
[0054] While the multicomponent filament (100) of FIG. 1 manages to
create a significant improvement on the amount of silver (301)
needed without further modification, since no silver (301) is
provided as part of the core (101) material, the necessity of
having to have the sheath (103) have a definitive thickness still
means that not all silver (301) of the sheath (103) material is
generally useable. Further, while the silver (301) particles are
often very small (being on the general scale of 1-5 microns in an
embodiment), it is generally a manufacturing reality that the
sheath (103) cannot be made sufficiently thin so as to be less than
the diameter of the silver or silver glass particles (301) used.
Specifically the filament will often be on the order of 100 microns
to a millimeter in diameter with the sheath comprising from 10% to
50% of the total diameter.
[0055] In order to increase the silver (301) percentage accessible
at the exterior surface (105) of the sheath (103), the filament
(100) of FIG. 1 is textured, generally using a false-twist
texturing process which is performed on the filament bundle or yarn
(300). In this process, a continuous run of yarn is drawn through a
rotating die, belt, or similar structure which serves to twist it
(generally in the manner of a helix). This is commonly done under
heat in order to allow for thermosetting of the yarn (300). Once
the yarn (300) has passed the rotation, it continues to be drawn.
However, because the yarn (300) is drawn after the rotating die,
the yarn (300) after the die is effectively rotated in the opposite
direction to the same yarn (300) prior to the die. This serves to
effectively untwist it so that at the end of the process, the
filaments (100) making up the yarn (300) have been twisted and
untwisted by essentially the same amount. Thus, as opposed to a
real twist process, where the yarn (300) is actually twisted, the
yarn (300) really has no resultant twist. However, it has been
observed that the twist is still visible and thus the filament
(100) has been structurally altered by the process. Specifically,
each filament in the yarn (300) is twisted (and untwisted) to some
extent resulting in a filament with some "memory" of twisting.
Further, each filament (100) is drawn or "stretched" by the
texturing process reducing its mass in any given length
(denier).
[0056] In addition to texturing the filament (100) using the
false-twist process, it is also the case that a filament bundle
(300), made from a plurality of filaments (100), that has been
texturized alters the arrangement between the filaments (100). This
can also improve the reactivity of a resultant yarn. Specifically,
in texturing a filament bundle (300) the component filaments (100)
will tend to pull from each other and the bundle (300) will open or
"fluff-up." This process is often referred to as "entangling" and
may result from blowing air on the filaments. Thus, external
surfaces (115) of the component filaments (100) are generally more
exposed as they are not interacting with each other. This can
result in an increased surface area of available silver (301). This
is illustrated in FIG. 3.
[0057] It has, however, been determined that running a
multicomponent thread (100) through a false-twist texturing process
will cause the percentage of silver (301) accessible at the
exterior surface (115) to increase as compared to a non-texturized
multicomponent thread including an identical amount of silver by a
greater amount than is to be expected solely by opening the
filament bundle (300). Without being bound by any particular theory
of operation, it is believed this is caused via multiple potential
structural changes to the filament (100). The first of these is
because the false-twisting process acts like the effect of wringing
a fabric. In particular, as the filament (100) is initially
twisted, components of the filament (100) are pushed closer
together. Generally, the interior of the filament (100) is more
crushed by this process that the outer surfaces of the filament
(100) due to the conservation of angular momentum.
[0058] As the multicomponent filament (100) core (101) is twisted,
the core (101) will simply compress eliminating any space within
the components of the core (101). As the core (101) includes no
additives, it will simply twist as expected. Further, as the twist
occurs, the inclusion of heat will generally exceed the glass
transition temperature of the polymer, but will generally not
surpass the melting temperature of the polymer. This is believed to
allow for material within the polymer of the core (101) to move
within the core (101) as the molecular chains of the polymer are
allowed to move past each other. The outer sheath (103) reacts
similarly. However, the outer sheath (103) includes the silver
particles (301) which are essentially contaminants in the flowable
polymer. As the silver particles (301) are still a solid, these
particles (301) are not affected by the heat but are now present in
an environment where the polymer can more readily flow.
[0059] It is believed that as the filament (100) is twisted,
particles (301) which are in the sheath (100) (e.g. particles
(301B)) will generally be forced upward (more exterior) in the
sheath (103). This likely occurs because the material of the sheath
(103) which is more interior will be more tightly compressed than
that toward the exterior. Thus, the inner layers are progressively
more dense. As the silver particle (301) is generally rigid within
the viscous liquid environment, it cannot crush under the twisting
action and will instead seek to move through the structure of the
filament (100) toward the exterior surface (105). In effect, the
polymer will flow around the particle (301) and toward the interior
of the filament (100). Thus, silver particles (301B) and (301C) in
the interior of the sheath (103), or on the interior surface (113)
of the sheath (103), will generally be pushed more toward the
external surface (105).
[0060] Thus, once twisted, particles (301B) which were near the
external surface (105), but still too far away to be reactive, will
be pushed into proximity with the exterior surface (105) and may be
pushed to a point where they are now capable of ion transfer with
an exterior compound. In the false twisting process, once the twist
has been completed and is being reversed, the filament (100) has
been thermoset and the silver particles (301) will be held more
rigidly because the flowable nature of the polymer is decreased.
However, even if this is not the case, as the filament (100) is
untwisted, the silver particles (301) will generally have no reason
to move back toward their initial position and will instead remain
in the later position migrated toward the exterior surface.
[0061] Secondly, it is believed that the texturing process reduces
the diameter of the filament (100). Specifically, it has been
observed that a yarn which has been texturized has a lower denier
than the same yarn prior to texturizing. Thus, as the material
flows, the yarn is clearly gaining length. It is theorized, that
the texturizing process will likely cause the sheath (103) to both
thin out (increasing the silver in ionic transfer distance) and
become "damaged." By damaged, the sheath (103) will have an
increase in cavities, voids, holes, and other related structures
which will generally increase its effective surface area. The
presence of these structures (401) will exposure further internal
silver as indicated in FIG. 2.
[0062] Once the texturing process is complete, it should be
apparent that a greater percentage of silver particles (301A) is
now in proximity to or extending from an exterior surface of the
filament (100) than was prior to texturing. Thus, the silver
reactivity and antimicrobial effect of the thread has increased
without altering the amount of silver present. This is generally
shown by comparing FIG. 1 to FIG. 2.
[0063] While the above contemplates the effect of texturing on a
single filament (100), it should also be recognized that the
false-twist process will generally be used on a yarn (300) made up
of multiple filaments (100) (whether continuous filaments or
chopped-up filaments in the form of staple). Without being bound to
a particular theory of operation, applying the false-twist process
to a multithread yarn (300) will serve to provide each filament
(100) in the yarn (300) with a slight memory of the twist. The
filaments (100) will then seek to push apart from each other after
the process. This act of texturing will effectively create small
air spaces between the filaments (100). As each filament (100) has
silver particles in the sheath (103) surrounding it, by separating
the filaments (100) (even by a very small amount) the yarn (300)
will have an improved ability to absorb fluid and there will be a
dramatically increased available silver surface area due to the
increased surface area of each of the filaments (100) in the yarn
(300).
[0064] It should be recognized that utilizing the false twist
texturing process on a single component filament (100) and
associated filament bundle (300) comprised of single component
filaments (100) is also expected to increase the amount of silver
accessible from the exterior of each filament (100), however, the
effect will be significantly less. To use a simple comparison, in
the multicomponent yarn (300), 100% of the silver in the sheath
(103) would effectively be in surface contact before any material
in the core would be in surface contact. Thus, in a multicomponent
filament (100), the amount of silver present on the surface
compared to the amount of silver used in the filament (100)
construction is dramatically improved.
[0065] While the above contemplates that the purpose of the
texturing is to increase silver contact, it should be recognized
that if silver glass is used as the form of silver (301), the glass
component can also provide for valuable characteristics, and the
amount of glass available at the exterior surface will also be
increased.
[0066] While the invention has been disclosed in conjunction with a
description of certain embodiments, including those that are
currently believed to be the preferred embodiments, the detailed
description is intended to be illustrative and should not be
understood to limit the scope of the present disclosure. As would
be understood by one of ordinary skill in the art, embodiments
other than those described in detail herein are encompassed by the
present invention. Modifications and variations of the described
embodiments may be made without departing from the spirit and scope
of the invention.
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