U.S. patent application number 09/993357 was filed with the patent office on 2003-09-18 for low surface energy fibers.
Invention is credited to Elliott, John, Fisher, W. Keith, Hancock, J. Gregory, Horn, David B..
Application Number | 20030175514 09/993357 |
Document ID | / |
Family ID | 28042501 |
Filed Date | 2003-09-18 |
United States Patent
Application |
20030175514 |
Kind Code |
A1 |
Hancock, J. Gregory ; et
al. |
September 18, 2003 |
Low surface energy fibers
Abstract
The present invention relates to a textile filament with a
contact angle greater than or equal to 90 degrees. Such filaments
are either water-repellent or resistant to chemicals, and yarns
made therefrom readily processible into fabrics. In a detailed
embodiment, the filaments are water-repellent and comprise a first
longitudinally-extending component comprising at least one polymer
selected from nylon, polyester, polypropylene, or other
filament-forming polymer, and a second longitudinally-extending
component, comprising a halogenated polymer. In a second detailed
embodiment, the filaments are chemical-resistant and comprise a
first longitudinally-extending component comprising at least one
fiber-forming polymer and a second longitudinally-extending
component comprising an olefin copolymer. In both embodiments, the
second longitudinally-extending component is present on the
exterior of the first longitudinally-extending component. The
present invention also relates to yarns made from the filaments,
and fabrics made from the yarns, as well as methods of making the
yarns and the fabric.
Inventors: |
Hancock, J. Gregory;
(Pensacola, FL) ; Fisher, W. Keith; (Suffield,
CT) ; Elliott, John; (New Orleans, LA) ; Horn,
David B.; (LongMeadow, MA) |
Correspondence
Address: |
Craig M. Lundell
Howrey Simon Arnold & White, LLP
P. O. Box 4433
Houston
TX
77210-4433
US
|
Family ID: |
28042501 |
Appl. No.: |
09/993357 |
Filed: |
November 16, 2001 |
Current U.S.
Class: |
428/373 ;
264/172.15; 264/172.17; 264/210.8; 264/211.14; 428/364 |
Current CPC
Class: |
D02G 3/38 20130101; Y10T
428/2913 20150115; D01F 8/10 20130101; Y10T 428/2929 20150115 |
Class at
Publication: |
428/373 ;
428/364; 264/172.15; 264/172.17; 264/210.8; 264/211.14 |
International
Class: |
D02G 003/00 |
Claims
What is claimed is:
1. A filament, comprising: a first longitudinally extending
component comprising at least one filament forming textile polymer;
and a second longitudinally extending component comprising at least
one polymer; wherein the second longitudinally extending component
is present on the surface of the first longitudinally extending
component, and wherein the filament has a contact angle greater
than or equal to 90 degrees.
2. The filament of claim 1, wherein the first longitudinally
extending component forms a core of the filament and the second
longitudinally extending component forms a sheath around the
circumference of the core.
3. The filament of claim 1, wherein the second longitudinally
extending component is in the form of at least one stripe on the
surface of the first longitudinally extending component.
4. The filament of claim 1, wherein the filament-forming polymer is
selected from nylon, polyester, or polypropylene.
5. The filament of claim 1, wherein the second longitudinally
extending component comprises a halogenated polymer.
6. The filament of claim 5, wherein the halogenated polymer is
poly(ethylene chlorotrifluoroethylene).
7. The filament of claim 1, wherein the second longitudinally
extending component comprises an olefin copolymer.
8. The filament of claim 1, wherein said filament comprises a
tenacity of at least 1.0 g/den.
9. A yarn comprising the filament of claim 1.
10. A fabric comprising the filament of claim 1.
11. A laminate comprising the filament of claim 1.
12. A method for producing a low surface energy filament
comprising, p1 melting a first component comprising at least one
filament-forming polymer; melting a second component comprising at
least one polymer; extruding said first component and said second
component to form a filament, wherein said second component is
formed on said first component; quenching said filament; and
drawing said filament; wherein said filament possesses a contact
angle greater than or equal to 90 degrees.
13. A method according to claim 12, wherein said filament is
produced using a single uninterrupted process.
14. A method according to claim 12, wherein spin finish is applied
to said filament.
15. A method according to claim 14, wherein said spin finish is
selected such that said finish does not decrease said contact angle
below 90 degrees.
16. A method according to claim 14, wherein said spin finish
comprises a halogenated polymeric compound.
17. A method according to claim 12, wherein said filament is used
to form continuous filament yams, staple yarns, melt-blown webs,
nonwoven fabrics or woven fabrics.
18. A method according to claim 12, wherein the first component
forms a core of the filament and the second component forms a
sheath around the circumference of the core.
19. A method according to claim 12, wherein the second component is
in the form of at least one stripe on the surface of the first
component.
20. A method according to claim 12, wherein the filament-forming
polymer is selected from nylon, polyester, or polypropylene.
21. A method according to claim 12, wherein the second component
comprises a halogenated polymer.
22. A method according to claim 21, wherein the halogenated polymer
is poly(ethylene chlorotrifluoroethylene).
23. A method according to claim 12, wherein the second component
comprises an olefin copolymer.
24. A method according to claim 12, wherein said filament comprises
a tenacity of at least 1.0 g/den.
25. A method for producing a low surface energy filament
comprising, melting a first component comprising at least one
filament-forming polymer; melting a second component comprising at
least one polymer; extruding said first component and said second
component to form a filament, wherein said second component is
formed on said first component; quenching said filament; and
drawing said filament at a speed of greater than about 1500 meters
per minute; wherein said filament possesses a contact angle greater
than or equal to 90 degrees.
26. A method according to claim 12, wherein said filament is
produced using a single uninterrupted process.
27. A method according to claim 12, wherein said filament is used
to form continuous filament yams, staple yams, melt-blown webs,
nonwoven fabrics or woven fabrics.
28. A method according to claim 12, wherein the first component
forms a core of the filament and the second component forms a
sheath around the circumference of the core.
29. A method according to claim 12, wherein the second component is
in the form of at least one stripe on the surface of the first
component.
30. A method according to claim 12, wherein the filament-forming
polymer is selected from nylon, polyester, or polypropylene.
31. A method according to claim 12, wherein the second component
comprises a halogenated polymer.
32. A method according to claim 21, wherein the halogenated polymer
is poly(ethylene chlorotrifluoroethylene).
33. A method according to claim 12, wherein the second component
comprises an olefin copolymer.
34. A method according to claim 25, wherein said speed is greater
than about 1800 meters per minute.
35. A method according to claim 25, wherein said speed is greater
than about 2000 meters per minute.
36. A method according to claim 25, wherein said speed is greater
than about 2300 meters per minute.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates generally to the fields of
synthetic filaments and products made therefrom. More particularly,
it concerns synthetic filaments that have both low surface energy
and high strength.
[0003] 2. Description of Related Art
[0004] Fabrics which are water-repellent (i.e. provide a barrier to
moisture) while allowing the passage of water vapor and other gases
are desirable for use in apparel, shoes, tents and camping
equipment, packaging, medical apparel, and medical supplies. Such
fabrics require fibers that have both a low surface energy to repel
water and a strength high enough to be processible into a useful
fabric. Other desirable fabrics are both water-repellent and do not
allow the passage of water vapor and other gases, for use in
packaging and medical supplies.
[0005] In packaging, protective apparel, and industrial filtration,
a need exists for fabrics that are stable to both heat and
chemicals. Such fabrics require fibers both low in surface energy
and high enough in strength to be processible into a useful fabric,
as well as heat and chemical resistance.
[0006] One class of water-repellent fabrics are those made by
applying a finish to a fabric or its component filaments before or
after the weaving or knitting process. The finish is intended to
provide the low surface energy needed to repel water. However, such
finishes tend to have poor durability and washfastness, and often
require environmentally taxing application or post-treatment
steps.
[0007] A second class of water-repellent fabrics is one comprised
of water-repellent materials. An example of this class is a fabric
comprising polytetrafluoroethylene (PTFE) sold by W. L. Gore Inc.
under the trade name GORE-TEX.RTM.. Known uses of PTFE fabrics are
chiefly lamination of the PTFE fabric to a textile fabric. This
suggests that PTFE fabrics, although having low surface energy, do
not have high enough strength to be useful fabrics per se.
[0008] Therefore, it is desirable to have a textile fabric made of
filaments that exhibit low surface energy and strength high enough
to be processible into useful fabrics. It is also desirable for
such filaments to be produced by high throughput, economical
spinning technology. Although filaments with a core/sheath
structure wherein the sheath comprises a halogenated polymer are
known (Chimura et al., U.S. Pat. Nos. 3,930,103 and 3,993,834), the
core of the known filaments comprises primarily methyl
methacrylate, and is not useful in forming textile fibers or
filaments. Although core/sheath filaments wherein the core
comprises nylon and the sheath comprises a grafted olefinic polymer
are known, such as Tabor et al., U.S. Pat. No. 5,372,885, no such
filaments are known to comprise a sheath useful in heat- and
chemical-resistant textile applications.
SUMMARY OF THE INVENTION
[0009] In one embodiment, the present invention relates to a
textile filament comprising a first longitudinally extending
component formed of at least one filament-forming polymer, and a
second longitudinally extending component formed of at least one
polymer, wherein the second longitudinally extending component is
in contact with the surface of the first longitudinally extending
component, and wherein the filament has a contact angle greater
than or equal to 90 degrees. In one embodiment, the first
longitudinally extending component forms the core of the filament,
and the second longitudinally extending component is in the form of
a sheath that surrounds the circumference of the core. In another
embodiment, the second longitudinally extending component is in the
form of one or more stripes located on the surface of the first
longitudinally extending component.
[0010] In another embodiment, the present invention relates to a
yam, wherein the yams comprise a plurality of filaments as
described above. The yarn may possess a contact angle greater than
90 degrees. The present invention also relates to a fabric
comprising a plurality of said yarns. The spacing between the yarns
may be sufficiently small to provide a barrier to liquids and
sufficiently large to allow the passage of gases, or is
sufficiently small to provide a barrier to liquids and to gases.
The fabric may possess a contact angle greater than 90 degrees.
[0011] In a further embodiment, the present invention relates to a
laminate that comprises a plurality of yams, fabrics and/or
filaments as described above. The laminate may possess a contact
angle greater than or equal to 90 degrees.
[0012] Another embodiment of the present invention relates to a
process for making a method for producing a low surface energy
filament comprising, melting a first component comprising at least
one filament-forming polymer; melting a second component comprising
at least one polymer; extruding said first component and said
second component to form a filament, wherein said second component
is formed on said first component; quenching said filament; and
drawing said filament; wherein said filament possesses a contact
angle greater than or equal to 90 degrees.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The following drawings form part of the present
specification and are included to further demonstrate certain
aspects of the present invention. The invention may be better
understood by reference to one or more of these drawings in
combination with the detailed description of specific embodiments
presented herein.
[0014] FIG. 1, is a scanning election microscope (SEM) image
(magnification .times.1000) of cross-sections of filaments having a
nylon 6,6 core surrounded by a Halar.RTM. sheath. The bicomponent
filaments are not drawn.
[0015] FIG. 2 is a SEM image (magnification .times.1000) of
cross-sections of filaments having a nylon 6,6 core and a
Halar.RTM. sheath wherein the filaments are in the form of drawn
staple fiber.
[0016] FIG. 3 is a SEM image (magnification .times.1000) depicting
cross-sections of filaments having a nylon 6,6 core and a
Halar.RTM. sheath formed by a two-step process, the first step
being the spinning of partially oriented fibers, the second step
being the drawing of these fibers.
[0017] FIG. 4 is a SEM image (magnification .times.1000)
illustrating cross-sections of filaments having a nyon 6,6 core and
a Halar.RTM. sheath formed by a one-step process.
[0018] FIG. 5 is a graph demonstrating the water repellency of an
embodiment of the present invention compared to other conventional
outerware materials.
DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
[0019] The terms "filament" and "fiber" may be used interchangeably
as referenced to herein. The terms "fiber" and "filament" may
include continuous and/or staple fiber.
[0020] In one aspect, the present invention relates to a filament
comprising a first longitudinally extending component comprising at
least one filament-forming polymer and a second longitudinally
extending component comprising at least one polymer, wherein the
second longitudinally-extending component covers at least part of
the first longitudinally-extending component and the filament has a
contact angle greater than or equal to 90 degrees. Such a filament
may be herein termed a "bicomponent filament."Contact angle,
dispersive surface energy, and non-dispersive work of adhesion can
be measured by methods known in the art (Tate et al., J. Colloid
and Interface Sci., 177, 579-588 (1996)). Typically, filaments with
a contact angle greater than or equal to 90 degrees have a
non-dispersive work of adhesion in water equal to or less than 26
mN/m. In another aspect, the filament of the present invention may
possess a tenacity of more than 2.0 g/den. Tenacity can be measured
by techniques known to those skilled in the art. Exemplary
techniques are described in the Examples below or in procedures
such as ASTM D 3822-96 or later revisions.
[0021] In a first class of embodiments of this aspect, the present
invention is directed to filaments comprising a first
longitudinally extending component comprising at least one
melt-processible, fiber-forming polymer including, but not limited
to polyamides (e.g., nylons), polyesters (e.g., PET, PBT, 3GT, PTT,
etc.) and polyolefins (polypropylene, polyethylene, poly (methyl
pentene), etc.) or other filament-forming, melt-processible,
fiber-forming polymer, and a second longitudinally extending
component present on the surface of the first longitudinally
extending component, comprising a halogenated polymer. Such
filaments have a low surface energy and may have a high tenacity.
The low surface energy makes the filaments resistant to moisture,
and the high tenacity makes the filaments processible into yarns
and/or fabric. The term "yams" shall include woven, knitted,
twisted, intermingled or otherwise combined staple fibers,
continuous filaments, threads, yarns and/or combinations thereof.
The term "fabric" shall be synonomous with web, felt and/or
fabric-like materials and shall include woven, knitted, sewn and/or
nonwoven filaments, yarns and combinations thereof. The term
"laminate" shall include one or more of filaments, yarns or fabrics
formed by any lamination process, including but not limited to
compression, adhesion, stapling, bonding, sewing or other
acceptable lamination processes. The term "nonwoven" shall include
melt-blowing, wet-laying, air-intermingling and/or any other web
forming means.
[0022] A filament of the present invention has a contact angle
greater than or equal to 90 degrees. This provides for the filament
to be water repellent. In one embodiment, the filament has a
core/sheath structure in which the sheath surrounds the core.
Hereinafter, "surrounding the core" shall mean covering enough of
the core so as to give sufficient halogenated polymer on the
surface of the fiber to provide a contact angle greater than or
equal to 90 degrees. Typically, the sheath will cover about 90% or
more of the outer surface of the core, and preferably, the sheath
will cover 100% of the outer surface of the core. The core and
sheath can be of any sectional profile (e.g. circular, pentalobal,
etc.). A typical, but not limiting, profile is a circular core
surrounded by a ring of sheath.
[0023] In a second embodiment, the filament has a "racing stripe"
structure in which the halogenated polymer component is present in
the form of longitudinal stripes on the external face of the first
longitudinally extending component. The number of longitudinal
stripes is selected so as to give sufficient halogenated polymer on
the surface of the fiber to provide a contact angle greater than or
equal to 90 degrees.
[0024] The optimal sectional profile to be used in a filament will
depend on the intended application of the filament and will be
readily determined by one skilled in the art.
[0025] The first longitudinally extending component of the filament
comprises at least one melt-processible, fiber-forming polymer
including, but not limited to polyamides (e.g. nylons), polyesters
(e.g., PET, PBT, 3GT, PTT, etc.), polyolefins (e.g.,
polypropylenes, polyethylene, poly(methyl pentene), etc.), or other
filament-forming polymer. Any polymer known to those skilled in the
art to be useful in the melt or solution spinning production of
textile filaments can be used in the present invention. Polymers of
nylon, polyester, and polypropylene are known to have sufficiently
high tenacity to be useful in the production of textile filaments.
Typically, such polymers have poor light transmittance, in
distinction to the core polymers disclosed by Chimura et al., cited
above. It is desirable for a filament-forming polymer to have
crystallization rates and/or elongational viscosity similar to
those same properties of the halogenated polymer of the second
longitudinally-extending component in order to better share
spinning stress.
[0026] Filament-forming polymers that can be used in the first
longitudinally-extending component include, but are not limited to
polyamides such as nylon 6,6, other nylons, polyesters such as
polybutylene terephthalate, other polyesters, and polyolefins such
as polypropylene. Nylon 6,6 and polyester are preferred. Other
filament-forming polymers that may be used in the present invention
will be clear to one skilled in the art.
[0027] The first longitudinally-extending component of the filament
can also include additives such as nucleating agents, flame
retardants, lubricants, surface active agents and colorants, among
other additives. Additives can be added to the molten first
longitudinally-extending component prior to extrusion of the
filament. Nucleating agents may be useful in increasing the
crystallization rate of the first longitudinally-extending
component to more nearly match that of the second
longitudinally-extending component. If it is desired to color the
filament by coloring the first longitudinally-extending component,
then colorants can be added to the molten first
longitudinally-extending component before coextrusion with the
second longitudinally-extending component. Typically, colorants in
the present invention will be solid pigments dispersed in either a
carrier polymer or blended beforehand in the first
longitudinally-extending component polymer, wherein the carrier
polymer can be selected for compatibility with the first
longitudinally-extending component polymer by one skilled in the
art. Other additives that can be used in the first
longitudinally-extending component are a fluoroalcohol or a
halogenated polymer, in order to aid adhesion of the first
longitudinally-extending component and the second
longitudinally-extending component. Other additives can be used,
and their identity and the circumstances making their use desirable
will be clear to one skilled in the art. Typically, such additives
are added in amounts of less than about 20 wt %, and preferably
less than about 10 wt %, depending upon the type of additive
utilized.
[0028] The concentration of the polymer in the first
longitudinally-extending component can be varied depending on the
polymer selected for use, the presence of other additives in the
first longitudinally-extending component, and the composition of
the second longitudinally-extending component. Preferably, the
concentration of filament-forming polymer in the first
longitudinally-extending component can be from about 80.0 wt % to
100.0 wt %. The remaining 0.0 wt % to about 20.0 wt % can comprise
nucleating agents, colorants, halogenated polymers, and other
additives as described above. In a preferred embodiment, the first
longitudinally-extending component comprises about 95 wt % nylon
6,6 and about 5 wt % nylon 6.
[0029] The second longitudinally-extending component of the
filament comprises a melt-processible halogenated polymer.
Halogenated polymers that may be useful as the sheath polymer in
this invention include (but are not limited to) poly (ethylene
chlorotrifluoroethylene) (ECTFE), amorphous fluoropolymers (AF),
perfluoralkoxy perfluoropolymers (PFA), fluorinated
ethylene-propylene copolymer (FEP), poly(ethylene-tetrafluoro-
ethylene) (ETFE), chlorotrifluoroethylene polymer (CTFE),
poly(vinylidene fluoride) (PVDF), poly(vinyl fluoride) (PVF),
poly(vinyl chloride) (PVC), etc. Other useful halogenated polymers
may be based on the above or on combinations of various halogenated
monomers such as VDF, TFE (tetrafluoroethylene), HFP
(hexafluoropropylene), PMVE (perfluoromethyl vinyl ether), PVE
(perfluoropropyl vinyl ether), for example, THV terpolymer
(TFE-HFP-VDF). Further surface active polymers include mixes of the
above or similar polymers, or of non-halogenated polymers such as a
nylon, polyester, or polyolefin, with melt-blended additives such
as poly(tetrafluoroethylene) (PTFE), etc. A preferred
melt-processible halogenated polymer that can be used in the
present invention is a 1:1 alternating copolymer of ethylene and
chlorotrifluoroethylene (hereinafter "poly(ethylene
chlorotrifluoroethylene);" commercially available from Ausimont
Inc., trade name HALAR.RTM.). All references herein to "halogenated
polymers" should be taken to mean "melt-processible halogenated
polymers" unless otherwise indicated. All references herein to
"HALAR.RTM." should be taken to mean "poly(ethylene
chlorotrifluoroethylene)." Halogenated polymers in the second
longitudinally-extending component provide low surface energy to
the filament.
[0030] The second longitudinally-extending component can also
include additives such as flame retardants, lubricants,
surfactants, nucleating agents, colorants, and anti-microbial
additives, among others. Nucleating agents and colorants are as
described above. Anti-microbial additives, for example zinc oxide,
can be added to enhance the useful life of the filaments and
fabrics made therefrom in medical applications. Other additives can
be used, and their identity and the circumstances making their use
desirable will be clear to one skilled in the art. It is desirable
that any such additives not lower the contact angle below 90
degrees.
[0031] The concentration of the halogenated polymer in the second
longitudinally-extending component can be varied depending on the
halogenated polymer selected for use, the presence of other
additives in the second longitudinally-extending component, and the
composition of the first longitudinally-extending component.
Preferably, the concentration of halogenated polymer in the second
longitudinally-extending component can be from about 80.0 wt % to
100.0 wt %. The remaining 0.0 wt % to about 20.0 wt % can comprise
flame retardants, lubricants, surfactants, nucleating agents,
colorants, anti-microbial additives, and other additives as
described above.
[0032] It is to be noted that the first longitudinally extending
component can comprise two or more melt-processible, fiber-forming
polymers, including, but not limited to polyamides (e.g. nylons),
polyesters (e.g., PET, PBT, 3GT, PTT, etc.), polyolefins (e.g.,
polypropylenes, polyethylene, poly (methyl pentene), etc.) or other
filament-forming polymer, and that the second
longitudinally-extending component can comprise two or more
halogenated polymers. In either case, the sum of the concentrations
of polymers in the first longitudinally-extending component or in
the second longitudinally-extending component preferably will be
between about 80.0 wt % and 100.0 wt %. Additives as described
above can also be added to either or both of the first
longitudinally-extending component or the second
longitudinally-extending component. The two or more polymers in the
first longitudinally-extending component may be blended, or they
may form separate layers, e.g. an outer layer surrounding an inner
layer, the inner layer having a circular, pentalobal, or other
cross-section; an outer layer consisting of longitudinal stripes
over the inner layer; and other combinations of inner and outer
layers readily envisioned by one of skill in the art.
[0033] Preferably, the percentages by total filament weight of the
first longitudinally-extending component and the second
longitudinally-extendin- g component can be from about 30%/70%
(first/second component) to about 70%/30% (first/second component).
First longitudinally-extending component percentages of less than
about 30% will yield filaments with strength less than 2.0 g/den
due to high levels of halogenated polymers; first
longitudinally-extending component percentages of more than about
70% will yield filaments with first longitudinally-extending
components insufficiently surrounded by second
longitudinally-extending components to have a contact angle greater
than or equal to 90 degrees. In order to reduce the materials
expense associated with halogenated polymers, it is more preferable
to have percentages by total filament weight of first
longitudinally-extending component and second
longitudinally-extending component components to be at least about
50%/50% (first/second component), and even more preferably at least
about 60%/40% (first/second component).
[0034] The denier (g/9000 m) per filament ("dpf") of the filament
can be of any value known in textile filaments, typically in the
range of from about 0.7 dpf to about 5.0 dpf. Preferably, the
denier per filament ranges from about 1.0 dpf to about 4.0 dpf.
[0035] In one embodiment of the invention, the filament comprises a
core of 100 wt % polybutylene terephthalate (about 50% of filament
by weight) and a sheath of 100 wt % melt-processible halogenated
polymer (about 50% of filament by weight), in which the core has a
circular cross-section and the sheath surrounds the core.
[0036] In another embodiment of the invention, the filament
comprises a core of 100 wt % nylon 6,6 (about 50% of filament by
weight) and a sheath of 100 wt % melt-processible halogenated
polymer (about 50% of filament by weight), in which the core has a
circular cross-section and the sheath surrounds the core.
[0037] In further embodiment of the invention, the filament
comprises a core of about 95 wt % nylon 6,6 and about 5 wt %
solution-pigmented melt-processible halogenated polymer (about 50%
of filament by weight) and a sheath of 100 wt % melt-processible
halogenated polymer (about 50% of filament by weight), in which the
core has a circular cross-section and the sheath surrounds the
core.
[0038] In yet another embodiment of the invention, the filament
comprises a core of 100 wt % nylon 6,6 (about 50% of filament by
weight) and a sheath of about 95 wt % unpigmented melt-processible
halogenated polymer and about 5 wt % pigmented melt-processible
halogenated polymer (50% of filament by weight), in which the core
has a circular cross-section and the sheath surrounds the core.
[0039] In yet a further embodiment of the invention, the filament
comprises a core of a copolymer of about 95 wt % nylon 6,6 and
about 5 wt % nylon 6 (about 50% of filament by weight) and a sheath
of 100 wt % melt-processible halogenated polymer (about 50% of
filament by weight), in which the core has a circular cross-section
and the sheath surrounds the core.
[0040] In a second class of embodiments of the invention, the
present invention is directed to filaments comprising a first
longitudinally-extending component comprising at least one
filament-forming polymer as described above and a second
longitudinally-extending component comprising an olefin copolymer.
Preferably, the olefin copolymer is a random olefin copolymer
comprising 4-methyl-1-pentene and 2-5 mol % of a C14 alkene
comonomer (hereinafter the "random copolymer"). Such filaments have
a contact angle greater than or equal to 90 degrees and a high
tenacity. The contact angle greater than or equal to 90 degrees
makes the filaments resistant to chemicals, and the high tenacity
makes the filaments processible into a fabric. Hereinafter,
"processible into a fabric" shall mean readily knitted or woven or
both to form a fabric useful in textiles or packaging.
[0041] A filament of this embodiment has a contact angle and
tenacity as described above. This provides for the filament to be
both chemical-resistant and processible into a fabric. The first
longitudinally-extending component and second
longitudinally-extending component can be present in the
"core/sheath" or "racing stripe" structure of the filament as
described above.
[0042] The first longitudinally-extending component of the filament
comprises at least one filament-forming, melt processible polymer,
including, but not limited to polyamides (e.g. nylons), polyesters
(e.g., PET, PBT, 3GT, PTT, etc.), polyolefins (e.g.,
polypropylenes, polyethylene, poly (methyl pentene), etc.).
Preferably, the filament-forming polymer is nylon 6,6. Nylon 6,6 is
known to have sufficiently high tenacity to be useful in the
production of textile filaments. Nylon 6,6 used in the first
longitudinally-extending component is heat stable in environments
up to about 180.degree. C. (360.degree. F.) for up to 6 h, which
allows it to retain tensile strength during curing in mold release
applications. It is desirable for a filament-forming polymer to
have crystallization rates and/or elongational viscosity similar to
those same properties of the olefin copolymer of the second
longitudinally-extending component in order to better share
spinning stress.
[0043] The first longitudinally-extending component of the filament
can also include additives as described above. Additional additives
that can be used include the olefin copolymer, in order to aid
adhesion to the olefin copolymer of the second
longitudinally-extending component. The concentrations of the
filament-forming polymer and any additives in the first
longitudinally-extending component are as described above.
[0044] The second longitudinally-extending component of the
filament comprises an olefin copolymer. Preferably, it comprises a
melt-processible random olefin copolymer comprising
4-methyl-1-pentene and 2-5 mol % of a C14 alkene comonomer. The
olefin copolymer provides a contact angle greater than or equal to
90 degrees to the filament. In addition, the olefin copolymer can
be blended with other polyolefins. The components of the olefin
copolymer are commercially available (e.g., from Airtech).
[0045] The second longitudinally-extending component can also
include additives such as nucleating agents, colorants, and
anti-microbial additives, among others. Nucleating agents, flame
retardants, lubricants, surfactants, colorants, and anti-microbial
additives are as described above. Other additives can be used, and
their identity and the circumstances making their use desirable
will be clear to one skilled in the art. It is desirable that any
such additives not make the contact angle less than 90 degrees.
[0046] It is desirable that the second longitudinally-extending
component includes a polypropylene copolymer to improve the
modulus. A preferred polypropylene copolymer is
CH.sub.3--(CH.sub.2--CH(CH.sub.3)).sub.n--(CH.-
sub.2--CH.sub.2).sub.x--CH.sub.3, wherein n and x can be any
integer greater than zero. Preferred polypropylene copolymers are
produced by Millennium Petrochemicals Inc. under the trade name
FLEXATHENE TP4380HR, and by Airtech. In one embodiment, the second
longitudinally-extending component comprises about 90 wt % olefin
copolymer and about 10 wt % polypropylene copolymer.
[0047] The concentration of the olefin copolymer in the second
longitudinally-extending component can be varied depending on the
presence of other additives in the second longitudinally-extending
component and the composition of the first longitudinally-extending
component. Preferably, the concentration of the olefin copolymer in
the second longitudinally-extending component can be from about
80.0 wt % to 100.0 wt %. The remaining 0.0 wt % to about 20.0 wt %
can comprise nucleating agents, flame retardants, lubricants,
surfactants, colorants, anti-microbial additives, the polypropylene
copolymer, and other additives as described above.
[0048] It is to be noted that the first longitudinally-extending
component can comprise two or more polymers selected from
polyamide, polyester, polypropylene, or other filament-forming
polymer. In this case, the sum of the concentrations of polymers in
the first longitudinally-extending component preferably will be
between about 80.0 wt % and 100.0 wt %. Additives as described
above can also be added to the first longitudinally-extending
component. The two or more polymers in the first
longitudinally-extending component may be blended, or they may form
separate layers, e.g. an outer layer surrounding an inner layer,
the inner layer having a circular, pentalobal, or other
cross-section; an outer layer consisting of longitudinal stripes
over the inner layer; and other combinations of inner and outer
layers readily envisioned by one of skill in the art.
[0049] Preferably, the percentages by total filament weight of the
first longitudinally-extending component and the second
longitudinally-extendin- g component can be from about 30%/70%
(first/second component) to about 70%/30% (first/second component).
First longitudinally-extending component percentages of less than
about 30% will yield filaments with strength less than 2.0 g/den
due to high levels of the olefin copolymer; first
longitudinally-extending component percentages of more than about
70% will yield filaments with first longitudinally-extending
component insufficiently surrounded by second
longitudinally-extending component to have contact angle greater
than or equal to 90 degrees and chemical resistance. In order to
reduce the materials expense associated with the olefin copolymer,
it is more preferable to have percentages by total filament weight
of the first longitudinally-extending component and the second
longitudinally-extending component to be at least about 50%/50%
(first/second component), and even more preferably at least about
60%/40% (first/second component).
[0050] The denier (g/9000 m) per filament ("dpf") of the filament
can be of any value known in textile filaments, typically in the
range of from about 0.7 dpf to about 5.0 dpf. Preferably, the
denier per filament ranges from about 1.0 dpf to about 4.0 dpf.
[0051] In an embodiment of this class of the invention, the
filament comprises a core of 100 wt % nylon 6,6 (50% of filament by
weight) and a sheath of about 90 wt % olefin copolymer and 10%
polypropylene copolymer, in which the core has a circular
cross-section and the sheath surrounds the core.
[0052] In a further aspect, the present invention relates to yarns
comprising a plurality of filaments, wherein each filament is as
described above.
[0053] The present invention also relates to a method for melt
spinning the yarns comprising a plurality of filaments, the method
comprising coextruding (1) a first molten stock comprising at least
one filament-forming polymer, and (2) a second molten stock
comprising at least one polymer, whereby the second molten stock
forms a second longitudinally-extending component located on the
first molten stock, thereby forming molten filaments, and quenching
the molten filaments, a plurality of which are formed into yarn.
The method can further comprise drawing the yam. Such yarns can be
melt-spun using bicomponent melt-spin techniques known in the
art.
[0054] To briefly summarize an exemplary method, the stock of
polymers and additives to comprise the first
longitudinally-extending component (the "first stock," "first
polymer formulation," or "first polymer stream") and the stock of
polymers and additives to comprise the second
longitudinally-extending component (the "second stock," "second
polymer formulation," or "second polymer stream") are in the molten
state in separate extruders. The separate first and second polymer
streams are then extruded into a spin pack, the spin pack
comprising separate chambers for the first and second polymer
streams, each chamber containing filter media; the spin pack also
comprises one or more distribution plates and a spinneret. The
distribution plates divide each of the first and second polymer
streams into a number of smaller melt streams equal to the number
of filaments to be spun. The distribution plates direct each of
these smaller melt streams into the desired filament configuration
above the spinneret. The combined melt streams are then each
extruded through capillaries in the spinneret. The combined melt
streams are then quenched or solidified in a chimney via cross-flow
air, at which point they may be at or near the final spun-yarn
denier. If needed in order to achieve the desired denier and
physical properties, this spun yarn may be drawn (stretched) either
during the spinning process or in a separate step thereafter.
Finish may then be applied and the quenched melt streams taken up
onto bobbins to form the spun yarn.
[0055] A typical yarn comprises from about 25 to about 100
filaments. Also, the yam can further comprise a lubricating finish
to aid in further processing. The finish can be any standard finish
known in the art. A typical, but non-limiting, finish is an
emulsion of 10 wt % to 25 wt % modified vegetable oils in water,
applied to a concentration of <0.2 wt % to 1.5 wt % oil per
total yarn. It is to be noted that the finish is distinct from the
second longitudinally-extending component, in that the second
longitudinally-extending component is applied to the first
longitudinally-extending component by coextrusion, whereas the
finish is applied to the yarn after quenching of the coextruded
bicomponent filaments to form the yarn and is typically removed in
subsequent fiber and fabric processing steps.
[0056] In another embodiment of the present invention, the
filaments may possess tenacities of less than 2.0 g/den if the
desired product is a nonwoven fabric or web. Such a fabric or web
may include filaments that contain less than about 30 wt % of the
first longitudinally-extending component and greater than about 70%
wt % of the second longitudinally-extending component.
Additionally, the filaments of such a nonwoven fabric or web may
not need to be drawn, but merely melt-blown, or its equivalent, on
to a moving substrate or belt, such as described in U.S. Pat. No.
4,828,911, the entire subject matter of which is incorporated
herein by reference.
[0057] According to the present invention, it has been discovered
that subsequent to application of typical finish (e.g., vegetable
oils, ethoxylated vegetable oils, etc.) to the filament and/or
yarn, such finish being applied to the filament/yarn to aid in
processing, the finish must be removed in order to provide the
filament/yarn with desirous low surface energy. By removing the
finish, the surface of the filament/yarn is exposed, thereby
providing the filament/yam with a contact angle greater than or
equal to 90 degrees. The finish removal may be conducted at any
time subsequent to filament/yarn postproduction, but it is
preferably removed subsequent to fabric formation. The finish may
be removed by scouring, etching, agitating, blasting, or
combination thereof in an aqueous environment and may additionally
include a solvent that aids in finish removal. The finish is
preferably removed by scouring in an aqueous bath.
[0058] In a preferable embodiment according to the present
invention, a finish is applied to the filament/yarn during
processing that reduces the surface energy of the filament yarn or
fabric made therefrom. The finish is preferably a partially or
fully halogenated polymeric compound, and more preferably a
partially or fully fluorinated polymeric compound, such as PTFE,
halogenated or fluorinated oil, halogenated or fluorinated silicone
oil, halogenated or fluorinated acrylic compounds, emulsifying
agents or combinations thereof and the like. The halogenated
polymeric compound may be applied in the form of an emulsion. FIG.
5 demonstrates the expected water-repellency behavior of an
embodiment of this invention (permanent ECTFE/nylon bicomponent
fabric) versus several other outerwear materials. The ECTFE sheath
material would be expected to maintain its contact angle over the
life of the fiber/fabric, though its initial contact angle is
dependent upon the processing oils used in its manufacture (and
whether or not they are subsequently removed). PTFE coatings give
higher contact angles initially and for some period of time, but
eventually wash and wear off. Pure nylon typically shows a surface
contact angle of around 60.degree., much too low for water to bead
and run off.
[0059] It is desirable to manipulate the method of making the yarn
in order to match the quenching and crystallization rates of the
first and second polymer formulations. This will enhance the
elongation and tenacity of the filaments, as is known to those
skilled in the art. Varying the level of airflow through the
chimney during the quenching step can modify the quenching rates.
Quenching and crystallization rates can be modified by altering the
temperatures of the molten forms of each of the first and second
polymer formulations prior to extrusion. The addition of nucleating
agents and other additives may also affect quenching and
crystallization rates. Altering the parameters of the spinning
machine or the speed of spinning can affect quenching and
crystallization rates as well. It is desirable to make the
crystallization rates of the first longitudinally-extending
component and the second longitudinally-extending component
similar, and to make the overall quench rate not too high to
produce breaks. The various ways of modifying the quenching and
crystallization rates, and their results, will be clear to one
skilled in the art in view of the goal of a yarn comprising
filaments each with a tenacity of at least 2.0 g/d, and preferably
at least about 3.0 g/d, and an elongation of 15%, and preferably at
least 25%.
[0060] The filaments during or after quench may be lubricated
and/or cooled with a finish stream. This applied finish can be
composed of a material or a mixture of materials that aid in
lubrication for the spinning process or downstream processes. This
finish medium may also aid in static control or other surface
properties of the yarn.
[0061] The package of yarn (the "bobbin") made via this process may
then be further processed into the final yarn form using several
methods: (1) continuous filament drawn or fully oriented yarn (FOY)
may be produced by drawing to the final yarn strength, orientation,
and residual elongation on a separate drawing machine; (2) the
drawing system may include a texturing step to impart crimp or body
to the yam; (3) the drawing system may include a method of twisting
the yarn along its longitudinal axis; (4) the spun yarn may be used
alone or when combined with other spun packages to supply a staple
draw-line. In every case, the spun yarn or POY is usually not in a
form usable by a textile converter or other fiber/yam customer,
unless that customer converts the yarn into a drawn yarn or
FOY.
[0062] In one embodiment of the method for melt-spinning yarns of
the present invention, the quench (air flow) rate is from 0
m.sup.3/min to about 2.832 m.sup.3/min (0 scfm (standard cubic feet
per minute) to about 100 scfm), and preferably from about 0.708
m.sup.3/min to about 1.416 m.sup.3/min (about 25 scfm to about 50
scfm) for a yarn of 26-52 filaments, at a windup speed of 1000-3000
m/min (mpm), for a total polymer throughput of 1.8-2.8 kg/hr (4-6
pounds/hr) per threadline position and a final spun yarn denier of
150-350. This yarn is then drawn on a drawing stand using heated,
powered rolls, at an appropriate draw ratio to give the final yarn
properties described above, at winder takeup speeds of 500-2000
mpm.
[0063] In a preferred embodiment, the yarn of the present invention
is fabricated in a continuous single step process. Single-step
production of FOY is effected in a process which combines all the
steps above into a single process. This combination of steps does
not mean the different machines described above are combined, but
that the spinning from melt, quenching, drawing and/or texturing,
and final product package collection are done in a single
uninterrupted process. There is no intermediate "spun yarn" package
formed; rather, the final drawn, oriented, and usable fiber or yarn
package made in a process fed by raw material feedstock (the
polymer source) and culminating in a package of material that can
be utilized by the final customer.
[0064] In another embodiment, the yarn of the present invention is
fabricated in a continuous process. Drawn yarn or FOY can be made
using spun yarn or POY as the feedstock. Typically, when using POY
as the feedstock, the drawing step consists of (1) a means of
supplying the yarn to the drawing machine; (2) a series of rolls or
other conveying units and/or pins, barriers, etc. to stretch the
feed yarn and align to some extent the polymer molecules in the
filaments; (3) an optional intermingling or tangling device to
intertwine the individual filaments at points along the length of
the threadline; and (4) a device such as a winder to take up the
drawn and/or textured material onto a final product package. During
the drawing of the yarn, heat may be added to increase the
pliability of the yarn; typically, this can be done by using heated
rolls, hated stationary or rotating pins, or radiant heat at some
point in the threadline path.
[0065] There are some polymers which do not lend themselves to easy
conversion to fiber via a single step process, whether due to
inherent polymer properties or due to the demands of the final
fiber, which may require extra handling or extra care in
processing. Halogenated polymers possess physical properties (e.g.,
rheological , etc.) that are significantly different from typical
fiber-forming polymers, such as polyamides, polyesters and
polyolefins. These differences in properties present difficulties
in bicomponent fiber formation, and affect the resulting fiber
characteristics. For example, low flux capillaries in the spin pack
from which each component issues may lead to inconsistent and
halting flow, thereby causing ripples, ridges or even interruptions
in one or both components, which results in inadequate surface
properties, especially for textile applications. Because
halogenated polymers typically possess rheological properties much
different from fiber-forming polymers, problems with surface
properties are further exacerbated , especially in sheath-core type
configurations. Halogenated polymers are typically amorphous in
nature and tend to deform readily during processing, especially
when utilized as the sheath. Most of the deformation occurs during
the drawing step of the fiber, as is demonstrated by FIGS. 1 and 2.
FIG. 1 is a scanning electron micrograph of bicomponent fiber
cross-sections of spun but not drawn fibers in which nylon 6,6 is
utilized as the core and Halar.RTM. is utilized as the sheath. FIG.
2 depicts such a bicomponent fiber after being drawn in a separate
step and readily demonstrates fiber cross-sections that deviate
considerably from circular shape, which fibers are not suitable for
certain textile applications. The artisan would not have expected
amorphous or largely amorphous polymers to form smoother and more
concentric fiber products at higher drawing speeds. However,
according to the present invention, it has been discovered that
single-step processes produce bicomponent fibers having
cross-sections superior than those produced in multiple-step
processes. For example, FIG. 3 represents cross-sections of nylon
6,6 core and Halar.RTM. sheath fibers produced utilizing a two-step
process. FIG. 4 depicts cross-sections of the same fiber produced
using a single-step process. The cross-sections of the fibers are
significantly more circular and provide greater consistency and
predictability in shape. The processing conditions for the fibers
pictured in FIGS. 3 and 4 are set forth in Examples 30 and 31.
[0066] In a preferred embodiment of the present invention the
bicomponent fibers are drawn at speeds of greater than 1500 meters
per minute (mpm), preferably greater than 1800 mpm, and more
preferably, greater than 2300 mpm. Because of the amorphous nature
(e.g., crystallization is difficult to induce) of halogenated
polymers, the artisan would not have expected higher draw speeds to
provide improved shape retention. In contrast, the artisan would
have expected increased drawing speeds to result in increased
deformity of the fiber shape and a less concentric fiber
cross-section. FIG. 5 pictures cross-sections of nylon 6,6 core and
Halar.RTM. sheath drawn at a speed of 1300 mpm. As is readily
apparent, the cross-sections of the fibers are highly irregular and
the surfaces of such fibers include abnormalities, such as dimples
and ripples or discontinuities. These fibers are not suitable for
various textile applications. FIG. 6 depicts such bicomponent
fibers drawn at a speed of about 1800 mpm. The fiber cross-sections
maintain their circular shape as spun and provide smooth surface
properties suitable for use in a variety of textile applications.
FIG. 7 depicts such bicomponent fibers drawn at a speed of about
2300 mpm. The fiber cross-sections also maintain their circular
shape and possess uniform sheath coverage with smooth surface
properties. These fibers advantageously may be utilized in a
variety of textile applications.
[0067] In another embodiment the yarn of the present invention is
comprised of staple filament. Staple filament can be made either
via the multiple step, discontinuous process, or a single step
continuous process. The main difference in end product is the form
of the fiber: continuous filament, as the name implies, is an
uninterrupted filament product usually wound onto a package (the
bobbin), with cut ends only at the outside of the package and at
the start of the package. Staple filament is cut into discrete
lengths and compressed or bound into bales or other such storage
packages, and is further processed into a spun yarn (not to be
confused with the spun POY above) at or for the final yarn
customer.
[0068] A discontinuous staple production method would start with
POY as described above. This yarn would be drawn and/or textured
(making the tow), treated as required with finish, steam, or other
media, and cut into discrete lengths. This cut staple would then be
formed into a package or placed into a container for further
processing as a usable textile yarn.
[0069] A continuous staple production method would be similar to
the single step continuous filament described above, but rather
than sending the continuous filament product to a wound package,
the fiber (the tow) would be cut into discrete lengths and formed
into a package or placed into a container for further processing as
a usable textile yarn.
[0070] In some cases, drawing the yarn before cutting into staple
lengths is not required, e.g., for staple feedstocks which are used
to make melt-blown webs, pads, or fabrics; or for tufted or
needlepunched fabrics, pads, or webs. In these cases, the staple
would be formed from POY manufactured as or similar to the above,
and cut to appropriate lengths and packaged.
[0071] There are several reasons fiber users and converters would
choose staple over continuous filament. (1) fabrics made from
staple yarn usually have a distinctly noticeably different feel and
appearance than fabrics made from continuous filament; (2) staple
fiber may be blended with other staple fiber types to give unique
end product yams and fabrics; (3) the end-user may have staple
conversion capacity available rather than continuous filament
capacity; (4) the yarn diameter and packing can be modified more
easily when starting with staple fiber than with continuous fiber,
for many applications.
[0072] In a second embodiment of this aspect, the yarns comprise a
plurality of filaments, wherein the filaments comprise a first
longitudinally-extending component comprising at least one
filament-forming polymer and a second longitudinally-extending
component comprising the olefin copolymer. The yarns can be
melt-spun using substantially the same technique as described
above, with the substitution of the olefin copolymer for the
halogenated polymer.
[0073] A special case of filament formation is that identical or
similar to the spinning process, which supplies a melt-blown or
other non-woven fabric, web, mat, or other process. In this case,
the extruded filaments are expelled from the spinneret, possibly
with quenching and possibly without, to a conveying or forming
step. These filaments are not collected and packaged as fibers, but
rather they are collected and formed into a fabric or fabric-like
structure such as a web, mesh, etc. almost directly below the
fiber-forming die or spinneret. The product of this process may be
useful by itself as a nonwoven material or substrate for another
material; as a support or scrim for other materials; as a liner or
layer of material in other textile applications; or for a number of
other final product uses.
[0074] The present invention is also directed to a fabric
comprising a plurality of yarns as described above. In one
embodiment, the filaments comprise a first longitudinally-extending
component comprising at least one melt-processible, fiber forming
polymer including but not limited to polyamides (e.g., nylons),
polyesters (e.g., PET, PBT, 3GT PTT, etc.) and polyolefins (e.g.,
polypropylene, polyethylene, poly(methyl pentene), etc.), or other
fiber-forming polymer and a second longitudinally-extending
component comprising a halogenated polymer. In another embodiment,
the filaments comprise a first longitudinally-extending component
comprising at least one filament-forming polymer and a second
longitudinally-extending component comprising the olefin copolymer.
In either of the foregoing, in one embodiment, in the fabric the
spacing between the yarns is sufficiently small to provide a
barrier to liquids and sufficiently large to allow the passage of
gases. This allows the fabric to resist moisture but still be
breathable. In another embodiment, in the fabric the spacing
between the yarns is sufficiently small to provide a barrier to
both liquids and gases. This allows the fabric to function as an
air-tight packaging material.
[0075] The present invention also relates to a method of making the
fabric, comprising providing a plurality of yarns as described
above, and weaving or knitting the plurality of yams to provide a
spacing between the yarns sufficiently small to provide a barrier
to liquids and sufficiently large to allow the passage of gases, to
yield the fabric. Alternatively, the weaving or knitting step may
be performed to provide a spacing between the yarns sufficiently
small to provide a barrier to both liquids and gases, to yield the
fabric.
[0076] The weaving or knitting pattern and the spacing between
yarns to provide a barrier to liquids, or to provide a barrier to
both liquids and gases will vary depending on the composition of
the filaments, the number of filaments per yarn, the parameters of
the melt-spinning of the yam, and the desired density and thickness
of the fabric. The appropriate pattern and spacing under a given
set of conditions can be readily determined by one skilled in the
art.
[0077] The following examples are included to demonstrate preferred
embodiments of the invention. It should be appreciated by those of
skill in the art that the techniques disclosed in the examples
which follow represent techniques discovered by the inventor to
function well in the practice of the invention, and thus can be
considered to constitute preferred modes for its practice. However,
those of skill in the art should, in light of the present
disclosure, appreciate that many changes can be made in the
specific embodiments which are disclosed and still obtain a like or
similar result without departing from the spirit and scope of the
invention.
EXAMPLE 1
[0078] A halogenated sheath threadline was spun, comprising 60%
core, 40% sheath by cross-sectional area (50%/50% by measured
weight at pumpout). The core was 100% nylon 6,6, and the sheath was
100% HALAR.RTM.. The halogenated polymer temperature at the
extruder discharge was controlled at 250.degree. C., and the nylon
polymer discharge temperature was controlled at 282.degree. C.
Threadlines of 26 filaments were generated at a total spun yarn
denier of 200.+-.30, 1000 mpm spinning speed, and with quench flow
set at 50 fpm. The quenched yarn was treated with an aqueous oil
emulsion spin finish of 12% oil concentration, giving 0.8% oil on
yarn by weight. This yarn was in turn drawn on a separate
draw-winding machine to a final denier of 90, giving 3.46 dpf for
the 26 filament items. The draw ratio was therefore 2.22. Drawn
items from these runs gave the following properties as measured
using an Instron 5500 tabletop tensile property testing unit:
1TABLE 1 Property Drawn Yarn Average Spun Yarn Average Breaking
strength, g 303.9 216.6 Denier 91.5 191.4 Tenacity (glden) 3.33
1.13 Elongation (%) 24.4 110.0
[0079] Table 1 indicates that a drawn yarn comprising filaments
comprising a core comprising at least one polymer selected from
nylon, polyester, polypropylene, or other fiber-forming polymer,
and a sheath comprising a halogenated polymer, has a tenacity
greater than 3.0 g/den, and an elongation of at least 15%. Such a
yarn is suitable for use in a fabric of the present invention.
EXAMPLE 2
[0080] A halogenated sheath threadline was spun according to
Example 1, with the exception that the core was 95% nylon 6,6 and
5% nylon 6 on a molar basis of monomers. This yarn was in turn
drawn on a separate draw-winding machine to a draw ratio of 3.00.
Drawn items from these runs gave the following properties:
2TABLE 2 Property Drawn Yarn Average Spun Yarn Average Breaking
strength, g 269.0 211.6 Denier 80.1 193.0 Tenacity (g/den) 3.35
1.12 Elongation (%) 18.1 125.4
[0081] Table 2 indicates that a drawn yarn comprising filaments
comprising a core comprising at least one polymer selected from
nylon, polyester, polypropylene, or other fiber-forming polymer,
and a sheath comprising a halogenated polymer, has a tenacity
greater than 3.0 g/den, and an elongation of at least 15%. Such a
yarn is suitable for use in a fabric of the present invention.
EXAMPLE 3
[0082] The threadline of Example 2 was spun as described with the
exception of being drawn to a draw ratio of 2.20. Drawn items from
these runs gave the following properties, as tested as described in
Example 2:
3TABLE 3 Property Drawn Yarn Average Spun Yarn Average Breaking
strength, g 310.0 211.6 Denier 104.8 193.0 Tenacity (g/den) 2.97
1.12 Elongation (%) 21.4 125.4
[0083] Table 3 indicates that a drawn yarn comprising filaments
comprising a core comprising at least one polymer selected from
nylon, polyester, polypropylene, or other fiber-forming polymer,
and a sheath comprising a halogenated polymer, has a tenacity
greater than 2.0 g/den, and an elongation of at least 15%. Such a
yarn is suitable for use in a fabric of the present invention.
EXAMPLE 4
[0084] A halogenated sheath threadline was spun as in Example 2,
with the exception that the core was 95% nylon 6,6 and 5%
HALAR.RTM.. Drawn items from these runs gave the following
properties:
4TABLE 4 Property Drawn Yarn Average Spun Yarn Average Breaking
strength, g 422.6 280.9 Denier 104 267.7 Tenacity (g/den) 4.1 1.05
Elongation (%) 15.7 155.3
[0085] Table 4 indicates that a drawn yarn comprising filaments
comprising a core comprising at least one polymer selected from
nylon, polyester, polypropylene, or other fiber-forming polymer,
and a sheath comprising a halogenated polymer, has a tenacity
greater than 3.0 g/den, and an elongation of at least 15%. Such a
yarn is suitable for use in a fabric of the present invention.
EXAMPLE 5
[0086] A halogenated threadline was spun as described in Example 2,
with the exception that the core consisted of 100% delustered nylon
6,6, wherein the nylon 6,6 was delustered with the addition of 2.5
wt % particulate pigment into the monomers either prior to
polymerization or during the polymerization stage. Drawing was done
to a draw ratio of 3.5, at draw-wind processing seeds of 1000 mpm.
Drawn items from these runs gave the following properties:
5TABLE 5 Property Drawn Yarn Average Spun Yarn Average Breaking
strength, g 248.6 172.4 Denier 85.1 266.4 Tenacity (g/den) 2.92
0.65 Elongation (%) 11.4 139.4
[0087] Table 5 indicates that a drawn yarn comprising filaments
comprising a core comprising at least one polymer selected from
nylon, polyester, polypropylene, or other fiber-forming polymer,
and a sheath comprising a halogenated polymer, has a tenacity
greater than 2.0 g/den, and an elongation of at least 10%.
EXAMPLE 6
[0088] A halogenated polymer threadline was spun as described in
Example 1, with the exceptions that the core was 100% PBT, 1.6 iv
(Aristech), the sheath was 100% HALAR.RTM., and the quench flow was
210 scfm. The spun yarn was drawn to a draw ratio of 2.01. Drawn
items from these runs gave the following properties:
6TABLE 6a Property Drawn Yarn Average Spun Yarn Average Breaking
strength, g 360 268 Denier-No. 134-26 262-26 of filaments Tenacity
(g/den) 2.7 1.1 Elongation (%) 22 108
[0089] Table 6a indicates that a drawn yarn comprising filaments
comprising a core comprising at least one polymer selected from
nylon, polyester, polypropylene, or other fiber-forming polymer,
and a sheath comprising a halogenated polymer, has a tenacity
greater than 2.0 g/den, and an elongation of at least 15%. Such a
yarn is suitable for use in a fabric of the present invention.
[0090] The wetting data for the spun and drawn yarns, as well as
for pure undrawn PBT and pure melt-processible halogenated polymer,
were also determined. Dispersive surface energy was measured in
methylene iodide, a purely dispersive liquid. Non-dispersive work
of adhesion and contact angle were measured using water as the
wetting liquid. The fibers were rinsed to remove spin finish before
measurement. The method of measuring surface energetics of fibers
is given by Tate et al., J. Colloid and Interface Sci., 177,
579-588 (1996).
[0091] Dispersive energy is a measure of oleophobicity (resistance
to wetting by oils), with lower values indicating more oleophobic
character. Dispersive surface energy is equivalent to the critical
surface energy often reported in the literature. Non-dispersive
work of adhesion in water is a measure of the polar interactions of
water with surfaces and is strongly related to water wetting
behavior. Lower values of work of adhesion mean less wetting. The
contact angle in water is also related to wetting behavior, with
higher values of contact angle indicating less wetting. Contact
angles greater than 90.degree. are indicative of a hydrophobic
surface.
[0092] The dispersive energy, non-dispersive work of adhesion, and
contact angle for spun and drawn PBT/HALAR.RTM. yarns, undrawn pure
PBT, and pure HALAR.RTM. are given in Table 6b.
7TABLE 6b Dispersive Surface Non-dispersive Contact Energy Work of
Adhesion angle Fiber (mN/m) (mN/m) (.degree.) pure PBT (undrawn) 27
29 85 PBT/HALAR .RTM. 27 14 97 spun PBT/HALAR .RTM. 27 6.3 103
drawn pure HALAR .RTM. 27 109
[0093] As can be seen from the dispersive surface energies,
HALAR.RTM. does not contribute additional oleophobic character over
that of pure PBT. However, HALAR.RTM. significantly increases the
hydrophobic nature of the fiber surfaces, as indicated in the lower
values of non-dispersive work of adhesion and increased contact
angle for the PBT/HALAR.RTM. fibers over pure PBT. Such yarns are
suitable for use in the present invention.
EXAMPLE 7
[0094] A halogenated polymer threadline was spun as described in
Example 6, with the exception that an electrically heated collar
was placed in the quench chimney to retard the quench rate. The hot
collar temperature was 240.degree. C. The spun yarn was not drawn.
The properties of the spun yarn were as follows:
8 TABLE 7 Property Spun Yarn Average Breaking strength, g 294
Denier-No. of filaments 275-26 Tenacity (glden) 1.07 Elongation (%)
173
EXAMPLE 8
[0095] A bicomponent threadline was spun, comprising 60% core, 40%
sheath by cross-sectional area (50%/50% by measured weight at
pumpout). The core was 100% nylon 6,6, and the sheath was an olefin
copolymer/polyolefin blend (90%: 10% wt). Two threadlines of 13
filaments were generated at a total spun yarn denier of 85, 958 mpm
spinning speed, and with quench flow set at 120 cfm. The quenched
yarn was treated with an aqueous oil emulsion spin finish of 10%
oil concentration, giving 2.6% oil on yarn by weight. This yarn was
in turn drawn on a separate draw-twisting machine to a final denier
of 45, giving 3.46 dpf for the 13 filament items. The draw ratio
was therefore 1.89. Drawn items from these runs gave the following
properties as measured using an Instron 5500 tabletop tensile
property testing unit:
9TABLE 8a Property Drawn Yarn Average Spun Yarn Average Breaking
strength, g 129.6 126.0 Denier 45.3 85.8 Tenacity (g/den) 2.86 1.47
Elongation (%) 57.9 201.9
[0096] Table 8a indicates that a drawn yarn comprising filaments
comprising a core comprising at least one polymer selected from
nylon, polyester, polypropylene, or other fiber-forming polymer,
and a sheath comprising an olefin copolymer/polyolefin blend, has a
tenacity greater than 2.5 g/den, and an elongation of at least 15%.
Such a yarn is suitable for use in a fabric of the present
invention.
[0097] The wettability data for the nylon 6,6/olefin copolymer yarn
and a pure nylon control were determined as described in Example 6.
The results are as follows:
10TABLE 8b Dispersive Surface Non-dispersive Contact Energy Work of
Adhesion angle Fiber (mN/m) (mN/m) (.degree.) nylon 6,6/olefin 20
26 93 copolymer pure nylon 22 49 61
[0098] As can be seen from the dispersive surface energies, the
olefin copolymer contributes negligible additional oleophobic
character over that of pure nylon. However, the olefin copolymer
significantly increases the hydrophobic nature of the fiber
surfaces, as indicated in the lower values of non-dispersive work
of adhesion and increased contact angle for the nylon 6,6/olefin
copolymer fibers over pure nylon. Such yarns are suitable for use
in the present invention.
EXAMPLE 9
[0099] A bicomponent threadline was spun according to Example 8,
with the exception of a 35% sheath, by cross-sectional area, of an
olefin copolymer/polyolefin blend (90%:10% wt). This yarn was in
turn drawn on a separate draw-winding machine to a draw ratio of
2.07. Drawn items from these runs gave the following
properties:
11TABLE 9 Property Drawn Yarn Average Spun Yarn Average Breaking
strength, g 229.0 219.1 Denier 73.0 143.1 Tenacity (g/den) 3.14
1.53 Elongation (%) 59.5 245.2
[0100] Table 9 indicates that a drawn yarn comprising filaments
comprising a core comprising at least one polymer selected from
nylon, polyester, polypropylene, or other fiber-forming polymer,
and a sheath comprising an olefin copolymer/polyolefin blend, has a
tenacity greater than 3.0 g/den, and an elongation of at least 15%.
Such a yarn is suitable for use in a fabric of the present
invention.
EXAMPLE 10
[0101] A bicomponent threadline was spun according to Example 9,
with the exception of a 26% sheath, by cross-sectional area. This
yarn was in turn drawn on a separate draw-winding machine to a draw
ratio of 2.07. Drawn items from these runs gave the following
properties:
12TABLE 10 Property Drawn Yarn Average Spun Yarn Average Breaking
strength, g 193.3 222.0 Denier 87.3 181.6 Tenacity (g/den) 2.21
1.22 Elongation (%) 92.0 339.8
[0102] Table 10 indicates that a drawn yarn comprising filaments
comprising a core comprising at least one polymer selected from
nylon, polyester, polypropylene, or other fiber-forming polymer,
and a sheath comprising an olefin copolymer/polyolefin blend, has a
tenacity greater than 2.0 g/den, and an elongation of at least 15%.
Such a yarn is suitable for use in a fabric of the present
invention.
EXAMPLE 11
[0103] A bicomponent threadline was spun according to Example 10,
and was in turn drawn on a separate draw-winding machine to a draw
ratio of 2.07. Drawn items from these runs gave the following
properties:
13TABLE 11 Property Drawn Yarn Average Spun Yarn Average Breaking
strength, g 213.0 221.1 Denier 89.7 186.8 Tenacity (g/den) 2.37
1.18 Elongation (%) 115.1 356.5
[0104] Table 11 indicates that a drawn yarn comprising filaments
comprising a core comprising at least one polymer selected from
nylon, polyester, polypropylene, or other fiber-forming polymer,
and a sheath comprising an olefin copolymer/polyolefin blend, has a
tenacity greater than 2.0 g/den, and an elongation of at least 15%.
Such a yarn is suitable for use in a fabric of the present
invention.
EXAMPLES 12-17
[0105] Bicomponent threadlines for Examples 12-17 are spun
according to Example 1, except that the threadlines are not drawn.
The threadlines have the following properties:
14TABLE 12 Example Denier BrkStr Elong Tenacity #Fils dpf 12 344.6
586.5 60.8 1.7 26 13.25 13 422.2 725.3 88.5 1.72 26 16.24 14 487.7
835 84.3 1.71 26 18.76 15 487.5 797.5 91.4 1.64 26 18.75 16 429.4
673.9 85.4 1.57 26 16.52 17 356 585.6 98.5 1.65 26 13.69
EXAMPLES 18-29
[0106] Fully drawn bicomponent yarns were produced with process
conditions summarized in the following table. The sheath polymer
melt was controlled to 250.degree. C. (unless shown otherwise),
while the core polymer melt was controlled to 282.degree. C.
Threadlines of varying filament counts and varying final product
deniers were produced as shown.
[0107] In every case, the molten polymers are combined in a
combination of metering plates and the filament spinneret to form
the bicomponent fibers (in all examples shown these were
sheath-core round cross-sections, though other examples of
non-round cross-sections have been obtained). The combined
filaments are quenched using cross-current air, and the now-solid
filaments are conveyed through finish applicators by the first
machine roll (the so-called spin roll). Drawing the fibers to the
final denier is done in two subsequent stages: between the spin
roll and first draw roll, and between the first draw roll and
second draw rolls. Total draw ratio is approximately equal to the
ratio of final draw roll speed to spin roll speed. The drawn fibers
are further conveyed by tensioning rolls to the winder, from which
is removed the sample package which can be converted to fabrics or
other fiber-based materials via a number of processes.
[0108] In examples 18, 19, 24, 25, 26, and 27, the sheath polymer
was pure Halar ECTFE, and the core was pure (commercial grade)
Nylon 6,6. Note that some examples varied the amount of sheath
polymer present based on weight (i.e. sheath/core ratio was
changed).
[0109] In examples 22 and 23, a compounded flake of Halar with ZnO
(25% by weight) was added to pure Halar ECTFE to obtain the flake
mixtures shown. In these two examples, "5% ZnO" means that of the
sheath component, 5% was the compounded Halar and 95% was pure
Halar. Likewise, "2% ZnO" means that of the sheath polymer, 2% is
the ZnO compounded material and 98% is pure Halar ECTFE.
[0110] In examples 28 and 29, pure ECTFE was blended as a flake
with the nylon 6,6 carrier at the ight percentage shown.
15TABLE 13 Example 18 19 20 21 22 23 Outer Halar Halar Halar Halar
Halar Halar polymer(s) ECTFE ECTFE ECTFE ECTFE ECTFE + ECTFE + 5%
ZnO 2% ZnO in ECTFE in ECTFE Wt % Outer 50 50 50 50 50 50 Inner
Nylon 6,6 Nylon 6,6 90% 95% Nylon 6,6 Nylon 6,6 polymer(s) Nylon +
Nylon + 10% 5% pigmented pigmented ECTFE ECTFE Filament Sheath-
Sheath- Sheath- Sheath- Sheath- Sheath- core core core core core
core Quench (cfm) 100 100 75 75 75 75 Residual oil 1.0% 1.0% 1.0%
1.0% 0.5% 0.6% level (oil on yarn) % Nominal total 2.35 2.35 2.35
2.35 2.35 2.35 draw ratio inline) Takeup speed 2560 2560 2600 2540
2290 2290 (mpm) Yarn denier 101 104 90 90 90 90 Yarn # 13 19 38 38
38 38 filaments Yarn dpf 7.77 5.46 2.37 2.37 2.37 2.37 Yarn 47.3
45.6 31.4 26.3 30.6 28.9 elongation % Yarn tenacity 2.05 2.50 2.11
2.40 3.02 3.00 g/d Yarn purpose Dental Dental Apparel Apparel
Apparel Apparel and test use floss or floss or filter filter media
media
[0111]
16TABLE 14 Example 24 25 26 27 28 29 Outer Halar Halar Halar Halar
Halar Halar polymer(s) ECTFE ECTFE ECTFE ECTFE ECTFE ECTFE Wt %
Outer 30 40 50 50 50 50 Inner Nylon 6,6 Nylon 6,6 Nylon 6,6 Nylon
6,6 Nylon Nylon polymer(s) 6,6 + 1% 6,6 + 2% ECTFE ECTFE Filament
Sheath- Sheath- Sheath- Sheath- Sheath- Sheath- core core core core
core core Quench (cfm) 100 100 75 75 75 75 Residual oil 0.6% 0.6%
0.6% 0.6% 0.5% 0.5% level (oil on yarn) % Nominal total 2.35 2.35
2.35 2.35 2.33 2.33 draw ratio (inline) Takeup speed 2587 2587 2587
2603 2048 2048 (mpm) Yarn denier 45 50 80 90 90 90 Yarn # 26 26 52
52 38 38 filaments Yarn dpf 1.73 1.92 1.54 1.73 2.37 2.37 Yarn 46.6
40.9 46.1 40.9 38.0 43.8 elongation % Yarn tenacity 3.20 2.78 2.45
2.35 2.78 2.87 g/d Yam purpose Apparel Apparel Apparel Apparel
Apparel, Apparel, and test use other other
EXAMPLE 30
[0112] This two step fiber item started with a 480 denier, 26
filament spun yam, drawn to 190 denier. The spun (POY yarn) was
generated on a pilot machine fed by two extruders, each feeding one
polymer--the two polymer streams are combined at the spin-pack
spinneret as sheath-core bicomponent filaments.
17TABLE 15 Spun Feedstock Settings Item Spun yarn feedstock Core
polymer (large xtdr) Nylon 66 Sheath polymer (small ECTFE xtdr)
Chimney air CFM 75 Pack type Bicomponent Finish type 10% oil
emulsion Finish-on-yarn Target 0.50% Sheath/Core weight ratio 50/50
Target denier/thdln 240 Filaments/threadline 26 Roll 1 mpm 1000
Roll 2 mpm 1010 Winder mpm 1020
[0113]
18TABLE 16 Drawing Settings Roll Speed Ratio T(.degree. C.) Feed
cyl. 410 1.022 A-roll 419 1.718 80 B-roll 720 1.375 90 C-roll 990
1.040 120 D-roll 1030 0.971 80 Fric. Roll 1000 Total draw 2.51
ratio
EXAMPLE 31
[0114] This one step fiber is produced on a spin-draw unit with the
same two extruders and polymer transport systems as in the previous
example, with similar polymer temperature settings. The filaments,
after extrusion as sheath-core filaments from the spinneret, are
quenched, lubricated with finish, conveyed by a heated "spin roll"
through a series of draw rolls at progressively higher speeds, onto
the final drawn yam package. There is no intermediary spun
package.
19TABLE 17 Spin Draw (One Step) Example Settings Spun yarn Roll
Item feedstock Temperature (.degree. C.) Core polymer (large xtdr)
Nylon 66 Sheath polymer (small xtdr) ECTFE Chimney air CFM 75 Pack
type Bicomponent Finish type 10% oil emulsion Finish-on-yarn Target
0.50% Sheath/Core weight ratio 50/50 Target denier/thdln 100
Filaments/threadline 38 Roll 1 mpm 1137 NA Roll 2 mpm 1140 80 Draw
Roll 1 mpm 2320 120 Draw Roll 2 mpm 2650 90 Relaxation Roll mpm
2565 80 Takeoff Roll mpm 2510 Winder mpm 2560
[0115] All of the compositions and methods disclosed and claimed
herein can be made and executed without undue experimentation in
light of the present disclosure. While the compositions and methods
of this invention have been described in terms of preferred
embodiments, it will be apparent to those of skill in the art that
variations may be applied to the compositions and methods and in
the steps or in the sequence of steps of the method described
herein without departing from the concept, spirit and scope of the
invention. More specifically, it will be apparent that certain
agents which are chemically related may be substituted for the
agents described herein while the same or similar results would be
achieved. All such similar substitutes and modifications apparent
to those skilled in the art are deemed to be within the spirit,
scope and concept of the invention as defined by the appended
claims.
* * * * *