U.S. patent application number 09/966145 was filed with the patent office on 2002-10-24 for stretchable polymeric fibers and articles produced therefrom.
Invention is credited to Figuly, Garret D., Goldfinger, Marc B., Mehta, Rakesh H., Samuelson, H. Vaughn, Soroka, Anthony J., Weeks, Gregory P..
Application Number | 20020155290 09/966145 |
Document ID | / |
Family ID | 27398810 |
Filed Date | 2002-10-24 |
United States Patent
Application |
20020155290 |
Kind Code |
A1 |
Figuly, Garret D. ; et
al. |
October 24, 2002 |
Stretchable polymeric fibers and articles produced therefrom
Abstract
A stretchable synthetic polymer fiber comprises an axial core
formed from an elastomeric polymer, and two or more wings formed
from a non-elastomeric polymer attached to the core. The fiber has
a substantially radially symmetric cross-section. Such fibers can
be used to form garments, such as hosiery.
Inventors: |
Figuly, Garret D.;
(Wilmington, DE) ; Soroka, Anthony J.; (Hixson,
TN) ; Goldfinger, Marc B.; (US) ; Mehta,
Rakesh H.; (US) ; Samuelson, H. Vaughn;
(US) ; Weeks, Gregory P.; (US) |
Correspondence
Address: |
E I DU PONT DE NEMOURS AND COMPANY
LEGAL PATENT RECORDS CENTER
BARLEY MILL PLAZA 25/1128
4417 LANCASTER PIKE
WILMINGTON
DE
19805
US
|
Family ID: |
27398810 |
Appl. No.: |
09/966145 |
Filed: |
September 28, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60236144 |
Sep 29, 2000 |
|
|
|
60236145 |
Sep 29, 2000 |
|
|
|
Current U.S.
Class: |
428/373 ;
428/395; 428/397 |
Current CPC
Class: |
D01F 8/04 20130101; Y10T
428/2969 20150115; Y10T 428/2973 20150115; D01F 8/14 20130101; Y10T
428/2929 20150115; D01F 8/16 20130101; D01F 8/12 20130101; D01D
5/30 20130101; D01D 5/253 20130101 |
Class at
Publication: |
428/373 ;
428/397; 428/395 |
International
Class: |
D02G 003/00 |
Claims
What is claimed is:
1. A stretchable synthetic polymer fiber having a substantially
radially symmetric cross-section and comprising an axial core
comprising a thermoplastic, elastomeric polymer, and a plurality of
wings comprising at least one thermoplastic, non-elastomeric
polymer attached to the core.
2. The fiber of claim 1, which comprises from 3 to 8 wings, has an
after-boil-off stretch of at least about 20%, requires less than
about 10% stretch to substantially straighten the fiber, has a
substantially circular core cross-section, and wherein the weight
ratio of non-elastomeric wing polymer to elastomeric core polymer
is in the range of about 10/90 to about 70/30.
3. The fiber of claim 1, wherein the non-elastomeric polymer is
selected from the group consisting of non-elastomeric polyamides,
polyolefins and polyesters, and the elastomeric polymer is selected
from the group consisting of thermoplastic polyurethanes,
thermoplastic polyester elastomers, thermoplastic polyolefins,
thermoplastic polyesteramide elastomers and thermoplastic
polyetheresteramide elastomers.
4. The fiber of claim 1, wherein the non-elastomeric polymer is
selected from the group consisting of a) poly(hexamethylene
adipamide) and copolymers thereof with 2-methylpentamethylene
diamine and b) polycaprolactam, and the elastomeric polymer is a
polyetheramide.
5. The fiber of claim 1, wherein the non-elastomeric polymer is
selected from the group consisting of poly(ethylene terephthalate)
and copolymers thereof, poly(trimethylene terephthalate), and
poly(tetramethylene terephthalate), and the elastomeric polymer is
selected from the group consisting of the reaction products of
poly(tetramethyleneether) glycol or
poly(tetramethylene-co-2-methyltetramethyleneether) glycol with
terephthalic acid or dimethyl terephthalate and a diol selected
from the group consisting of 1,3-propane diol and 1,4-butane
diol.
6. The fiber of claim 1, wherein the core includes on its outside
surface a sheath of a non-elastomeric polymer between points where
the wings contact the core.
7. The fiber of claim 1 further comprising an additive added to the
non-elastomeric polymer of the wings to improve adhesion of the
wings to the core, wherein this fiber has a delamination rating
below about 2.5.
8. The fiber of claim 7, wherein the non-elastomeric polymer is
selected from the group consisting of (a) poly(hexamethylene
adipamide) and copolymers thereof with 2-methylpentamethylene
diamine and (b) polycaprolactam, and the elastomeric polymer is a
polyetheresteramide.
9. A stretchable synthetic polymer fiber having at least about 35%
after boil-off shrinkage and which requires less than about 10%
stretch to substantially straighten the fiber.
10. A stretchable synthetic polymer fiber comprising an axial core
comprising an elastomeric polymer and a plurality of wings
comprising a non-elastomeric polymer attached to the core, wherein
the core includes on its outside surface a sheath of a
non-elastomeric polymer between points where the wings contact the
core.
11. A stretchable synthetic polymer fiber comprising an axial core
comprising an elastomeric polymer and a plurality of wings
comprising a non-elastomeric polymer attached to the core, wherein
the core has a substantially circular or regular polyhedron cross
section.
12. A stretchable synthetic polymer fiber comprising an axial core
comprising an elastomeric polymer and a plurality of wings
comprising a non-elastomeric polymer attached to the core, wherein
at least one of the wings has a T, C, or S shape.
13. A garment comprising the fiber of claims 1, 9, 10, 11 or
12.
14. A melt spinning process for spinning continuous polymeric
fibers comprising: passing a melt comprising at least one
thermoplastic non-elastomeric polymer and a melt comprising a
thermoplastic elastomeric polymer through a spinneret to form a
plurality of stretchable synthetic polymeric fibers having a
substantially radially symmetric cross-section and comprising an
axial core comprising the elastomeric polymer and a plurality of
wings comprising the non-elastomeric polymer attached to the core;
quenching the fibers after they exit the capillary of the spinneret
to cool the fibers, and collecting the fibers.
15. The process of claim 14, comprising an additional step, after
quenching, of heat-relaxing the fiber so that it exhibits at least
about 20% after-boil-off stretch.
16. The process of claim 15, wherein the heat-relaxing is carried
out with a heating medium of dry air, hot water or superatmospheric
pressure steam at a temperature in the range of about 80.degree. C.
to about 120.degree. C. when the heating medium is said dry air,
about 75.degree. C. to about 100.degree. C. when the heating medium
is said hot water, and about 101.degree. C. to about 115.degree. C.
when the heating medium is said superatmospheric pressure
steam.
17. The process of claim 14, comprising an additional step, after
the quenching, of drawing the fiber so that it exhibits at least
about 20% after-boil-off stretch.
18. The process of claim 14, comprising an additional step, after
the quenching, of relaxing the fiber by in the range of about 1-35%
based on the fiber length before relaxing.
Description
RELATED APPLICATIONS
[0001] This application claims priority of U.S. Provisional Patent
Applications 60/236,144 and 60/236,145, both filed Sep. 29,
2000.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to stretchable fibers,
including multiwing, stretchable synthetic polymer fibers formed
from at least two types of polymers. The invention also relates to
methods of producing such fibers. The invention also relates to
articles formed from the fibers, including yarns, garments, and the
like.
[0004] 2. Description of Related Art
[0005] It is desired to impart stretchability into many products
formed from synthetic fibers, including various garments, such as
sportswear and hosiery.
[0006] As disclosed in U.S. Pat. No. 4,861,660 to Ishii, various
methods are known for imparting stretchability to synthetic
filaments. In one method, the fibers are two- or
three-dimensionally crimped. In another such method, stretchable
filaments are produced from elastic polymers, for example, natural
or synthetic rubber, or a synthetic elastomer, such as polyurethane
elastomer. However, there are drawbacks associated with either of
these methods. Ishii attempts to overcome the drawbacks of such
filaments by imparting asymmetry to filaments which are formed from
two polymers. Asymmetry causes the composite lobe filamentary
constituents to be spirally coiled around the axial filamentary
constituent in alternately reversed different directions. Thus, the
resultant composite filament exhibits an improved stretchability
and a good touch and gloss. However, due to their asymmetrical
cross section, the Ishii fibers can develop, after mild heat
treatment, substantial three-dimensional or helical crimp in
addition to their axial spiral twist. This three-dimensional crimp
characteristic imparts a torque to the fibers and has been found to
impart a substantial and often undesirable `edge curl` to fabrics
constructed of such fibers. The inherent bulk and non-uniformity of
such fibers also makes it difficult to construct uniform low basis
weight or sheer fabrics from them. For these reasons the Ishii
fibers are often unsatisfactory in fabrics knitted or woven from
them.
[0007] U.S. Pat. No. 3,017,686 to Breen et al. also discloses a
filament made from two polymers. These polymers are thermoplastic
hard polymers, each having no elastomeric property. The polymers
are chosen in order to have a sufficient difference in shrinkage so
that the fin of the filament has a sinuous configuration, or
"ruffle". Breen is concerned with the frequency by which the fins
on a filament change direction so that close packing between
adjacent filaments is not possible, and is not concerned with
stretchability. Thus, the fiilaments disclosed in Breen do not
exhibit the high recovery desired in many of today's fabrics.
[0008] Thus, there is still a need for fibers and articles
therefrom, that are stretchable and have excellent stretch and
recovery power, preferably without undesired two- or
three-dimensional crimping characteristics, and for convenient
methods of making such fibers and articles.
SUMMARY OF THE INVENTION
[0009] The present invention solves the problems associated with
the prior art by providing a stretchable synthetic polymer fiber
having a substantially radially symmetric cross-section. This
imparts an unexpected combination of high stretch and high
uniformity without significant levels of 2- or 3-dimensional crimp.
As a result, the fibers of the invention are well-suited for use in
smooth, non-bulky, highly stretchable fabrics. Such a finding was
unexpected in view of the teaching to the contrary by U.S. Pat. No
4,861,660 to Ishii.
[0010] Thus, in accordance with the present invention, there is
provided a stretchable synthetic polymer fiber having a
substantially radially symmetric cross-section and comprising an
axial core comprising a thermoplastic elastomeric polymer and a
plurality of wings comprising at least one thermoplastic,
non-elastomeric polymer attached to the core.
[0011] There is further provided in accordance with the invention a
garment comprising the stretchable synthetic polymer fiber
described above.
[0012] The invention further provides a melt spinning process for
spinning continuous polymeric fibers comprising: passing a melt
comprising at least one thermoplastic non-elastomeric polymer and a
melt comprising a thermoplastic elastomeric polymer through a
spinneret to form a plurality of stretchable synthetic polymeric
fibers, each having a substantially radially symmetric
cross-section and comprising an axial core comprising the
elastomeric polymer and a plurality of wings comprising the
non-elastomeric polymer attached to the core; quenching the
fibersafter they exit the capillary of the spinneret to cool the
fibers, and collecting the fibers.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a cross-sectional profile drawing of a six-wing
fiber of the invention.
[0014] FIGS. 2A and 2B show fibers of the invention in which the
spiral twist is almost completely circumferential (2A) and in which
the spiral twist is almost completely noncircumferential (2B).
[0015] FIG. 3 shows a fiber of the invention in which the fiber is
slightly wavy.
[0016] FIG. 4 is a representation of the cross-sectional shape of a
particular symmetrical two-wing fiber having a thin sheath around
the core and between the wings according to the invention.
[0017] FIG. 5 is a process schematic of an apparatus useful for
making fibers of this invention.
[0018] FIG. 6 is a representation of a stacked plate spinneret
assembly, in side elevation, that can be used to make the fiber of
the invention.
[0019] FIG. 6A is a representation of orifice plate A in plan view
at 90.degree. to the stacked plate spinneret assembly shown in FIG.
6, and taken across lines 6A-6A of FIG. 6.
[0020] FIG. 6B is a representation of orifice plate B in plan view
at 90.degree. to the stacked plate spinneret assembly shown in FIG.
6, and taken across lines 6B-6B of FIG. 6.
[0021] FIG. 6C is a representation of orifice plate C in plan view
at 90.degree. to the stacked plate spinneret assembly shown in FIG.
6, and taken across lines 6C-6C of FIG. 6.
[0022] FIG. 7 is a representation of a stacked plate spinneret
assembly, in side elevation, that can be used to make certain
fibers according to another embodiment of the present
invention.
[0023] FIG. 7A is a representation of orifice plate A in plan view
at 90.degree. to the stacked plate spinneret assembly shown in FIG.
7, and taken across lines 7A-7A of FIG. 7.
[0024] FIG. 7B is a representation of orifice plate B in plan view
at 90.degree. to the stacked plate spinneret assembly shown in FIG.
7, and taken across lines 7B-7B of FIG. 7.
[0025] FIG. 7C is a representation of orifice plate C in plan view
at 90.degree. to the stacked plate spinneret assembly shown in FIG.
7, and taken across lines 7C-7C of FIG. 7.
[0026] FIG. 7F is a representation of orifice plate F in plan view
at 90.degree. to the stacked plate spinneret assembly shown in FIG.
7, and taken across lines 7F-7F of FIG. 7.
[0027] FIG. 7G is a representation of orifice plate G in plan view
at 90.degree. to the stacked plate spinneret assembly shown in FIG.
7, and taken across lines 7G-7G of FIG. 7.
[0028] FIG. 7H is a representation of orifice plate H in plan view
at 90.degree. to the stacked plate spinneret assembly shown in FIG.
7, and taken across lines 7H-7H of FIG. 7.
[0029] FIG. 8 is a cross-sectional profile drawing of a fiber of
the invention as exemplified in Example 7.
[0030] FIG. 9 is a cross-sectional profile drawing of a six-wing
fiber of the invention as exemplifed in Example 7.
DETAILED DESCRIPTION OF THE INVENTION
[0031] In accordance with the present invention, there is provided
a stretchable synthetic polymer fiber, shown generally at 10 in
FIGS. 1, 2A, 2B, 3, 4, 8 and 9. The fiber of the present invention
includes an axial core, shown at 12 in FIG. 1, and a plurality of
wings, shown at 14 in FIG. 1. According to the present invention,
the axial core comprises a thermoplastic elastomeric polymer, and
the wings comprise at least one thermoplastic, non-elastomeric
polymer attached to the core. Preferably, the thermoplastic,
non-elastomeric polymer is permanently drawable.
[0032] As used herein, the term "fiber" is interchangeable with the
term "filament". The term "yarn" includes yarns of a single
filament. The term "multifilament yarn" generally relates to yarns
of two or more filaments. The term "thermoplastic" refers to a
polymer which can be repeatedly melt-processed (for example
melt-spun). By `elastomeric polymer` is meant a polymer which in
monocomponent fiber form, free of diluents, has a break elongation
in excess of 100% and which when stretched to twice its length,
held for one minute, and then released, retracts to less than 1.5
times its original length within one minute of being released. The
elastomeric polymers in the fiber of the invention can have a flex
modulus of less than about 14,000 pounds per square inch (96,500
kPascals), more typically less than about 8500 pounds per square
inch (58,600 kPascals) when present in a monocomponent fiber spun
according to ASTM standard D790 Flexural Properties at RT or
23.degree. C. and under conditions substantially as described
herein. As used herein, "non-elastomeric polymer" means any polymer
which is not an elastomeric polymer. Such polymers can also be
termed "low elasticity", "hard: and "high modulus". By "permanently
drawable" is meant that the polymer has a yield point, and if the
polymer is stretched beyond such point it will not return to its
original length.
[0033] The fibers of the invention are termed "biconstituent"
fibers when they are comprised of at least two polymers adhered to
each other along the length of the fiber, each polymer being in a
different generic class, e.g., polyamide, polyester or polyolefin.
If the elastic characteristics of the polymers are sufficiently
different, polymers of the same generic class can be used, and the
resulting fiber is a "bicomponent" fiber. Such bicomponent fibers
are also within the scope of the invention.
[0034] The fiber of the present invention is twisted around its
longitudinal axis, without significant two- or three-dimensional
crimping characteristics. (In such higher-dimensional crimping, a
fiber's longitudinal axis itself assumes a zig-zag or helical
configuration; such fibers are not of the invention). The fiber of
the present invention may be characterized as having substantially
spiral twist and one dimensional spiral twist. "Substantially
spiral twist" includes both spiral twist that passes completely
around the elastomeric core and also spiral twist that passes only
partly around the core, since it has been observed that a fully
360.degree. spiral twist is not necessary to achieve the desirable
stretch properties in the fiber. FIG. 2A shows a fiber 10 with a
substantially spiral twist which is almost completely
circumferential, and FIG. 2B shows a fiber 10 with a substantially
spiral twist which is almost completely noncircumferential. "One
dimensional" spiral twist means that while the wings of the fiber
can be substantially spiral, the axis of the fiber is substantially
straight even at low tension, in contrast to fibers having 2- or
3-dimensional crimp. However, fibers having some waviness are
within the scope of the invention, as illustrated by fiber 10 in
FIG. 3.
[0035] The presence or absence of two- and three-dimensional crimp
can be gauged from the amount of stretch needed to substantially
straighten the fiber (by pulling out any non-linearities) and is a
measure of the radial symmetry of fibers having spiral twist. The
fiber of the invention can require less than about 10% stretch,
more typically less than about 7% stretch, for example about 4% to
about 6%, to substantially straighten the fiber.
[0036] The fiber of the present invention has a substantially
radially symmetric cross-section, as can be seen from FIG. 1. By
"substantially radially symmetric cross-section" is meant a
cross-section in which the wings are located and are of dimensions
so that rotation of the fiber about its longitudinal axis by 360/n
degrees, in which "n" is an integer representing the "n-fold"
symmetry of the fibers, results in substantially the same
cross-section as before rotation. The cross-section is
substantially symmetrical in terms of size, polymer and angular
spacing around the core. This substantially radially symmetric
cross-section impartes an unexpected combination of high stretch
and high uniformity without significant levels of two- or
three-dimensional crimp. Such uniformity is advantageous in
high-speed processing of fibers, for example through guides and
knitting needles, and in making smooth, non-`picky` fabrics,
especially sheer fabrics like hosiery. Fibers which have a
substantially radially symmetric cross-section possess no
self-crimping potential, i.e., they have no significant two- or
three-dimensional crimping characteristics. See generally Textile
Research Journal, June 1967, p. 449.
[0037] For maximum cross-sectional radial symmetry, the core can
have a substantially circular or a regular polyhedral
cross-section, e.g., as seen in FIGS. 1, 4, 8, and 9. By
"substantially circular" it is meant that the ratio of the lengths
of two axes crossing each other at 90.degree. in the center of the
fiber cross-section is no greater than about 1.2:1. The use of a
substantially circular or regular polyhedron core, in contrast to
the cores of U.S. Pat. No. 4,861,660, can protect the elastomer
from contact with the rolls, guides, etc. as described later with
reference to the number of wings. The plurality of wings can be
arranged in any desired manner around the core, for example,
discontinuously as depicted in FIG. 1, i.e., the wing polymer does
not form a continous mantel on the core, or with adjacent wing(s)
meeting at the core surface, e.g., as illustrated in FIGS. 4 and 5
of U.S. Pat. No. 3,418,200. The wings can be of the same or
different sizes, provided a substantially radial symmetry is
preserved. Further, each wing can be of a different polymer from
the other wings, once again provided substantially radial geometric
and polymer composition symmetry is maintained. However, for
simplicity of manufacture and ease of attaining radial symmetry, it
is preferred that the wings be of approximately the same
dimensions, and be made of the same polymer or blend of polymers.
It is also preferred that the wings discontinuously surround the
core for ease of manufacture.
[0038] While the fiber cross-section is substantially symmetrical
in terms of size, polymer, and angular spacing around the core, it
is understood that small variations from perfect symmetry generally
occur in any spinning process due to such factors as non-uniform
quenching or imperfect polymer melt flow or imperfect spinning
orifices. It is to be understood that such variations are
permissible provided that they are not of a sufficient extent to
detract from the objects of the invention, such as providing fibers
of desired stretch and recovery via one-dimensional spiral twist,
while minimizing two- and three-dimensional crimping. That is, the
fiber is not intentionally made asymmetrical as in U.S. Pat. No.
4,861,660.
[0039] The wings protrude outward from the core to which they
adhere and form a plurality of spirals at least part way around the
core especially after effective heating. The pitch of such spirals
can increase when the fiber is stretched. The fiber of the
invention has a plurality of wings, preferably 3-8, more preferably
5 or 6. The number of wings used can depend on other features of
the fiber and the conditions under which it will be made and used.
For example, 5 or 6 wings can be used when a monofilament is being
made, especially at higher draw ratios and fiber tensions. In this
case the wing spacing can be frequent enough around the core that
the elastomer is protected from contact with rolls, guides, and the
like and therefore less subject to breaks, roll wraps and wear than
if fewer wings were used. The effect of higher draw ratios and
fiber tensions is to press the fiber harder against rolls and
guides, thus splaying out the wings and bringing the elastomeric
core into contact with the roll or guide; hence the preference for
more than two wings at high draw ratios and fiber tensions. In
monofilaments, five or six wings are often preferred for an optimum
combination of ease of manufacture and reduced core contact. When a
multifiber yarn is desired, as few as two or three wings can be
used because the likelihood of contact between the elastomeric core
and rolls or guides is reduced by the presence of the other
fibers.
[0040] While it is preferred that the wings discontinuously
surround the core for ease of manufacture, the core may include on
its outside surface a sheath of a non-elastomeric polymer between
points where the wings contact the core. FIG. 4 shows a fiber 10
having a sheath 16. The sheath thickness can be in the range of
about 0.5% to about 15% of the largest radius of the fiber core.
The sheath can help with adhesion of the wings to the core by
providing more contact points between the core and wing polymers, a
particularly useful feature if the polymers in the biconstituent
fiber do not adhere well to each other. The sheath can also reduce
abrasive contact between the core and rolls, guides, and the like,
especially when the fiber has a low number of wings.
[0041] The core and/or wings of the multiwinged cross-section of
the present invention may be solid or include hollows or voids.
Typically, the core and wings are both solid. Moreover, the wings
may have any shape, such as ovals, T-, C-, or S-shapes (see, for
example, FIG. 4). Examples of useful wing shapes are found in U.S.
Pat. No. 4,385,886. T, C, or S shapes can help protect the
elastomer core from contact with guides and rolls as described
previously.
[0042] The weight ratio of total wing polymer to core polymer can
be varied to impart the desired mix of properties, e.g., desired
elasticity from the core and other properties from the wing
polymer. For example, a weight ratio of non-elastomeric wing
polymer to elastomeric core polymer in the range of about 10/90 to
about 70/30, preferably about 30/70 to about 40/60, can be used.
For high durability combined with high stretch in uses in which the
fiber is not used with a companion yarn (for example hosiery), a
wing/core weight ratio in the range of about 35/65 to about 50/50
is often preferred.
[0043] As noted above, the core of the fiber of the invention can
be formed from any thermoplastic elastomeric polymer. Examples of
useful elastomers include thermoplastic polyurethanes,
thermoplastic polyester elastomers, thermoplastic polyolefins,
thermoplastic polyesteramide elastomers and thermoplastic
polyetheresteramide elastomers.
[0044] Useful thermoplastic polyurethane core elastomers include
those prepared from a polymeric glycol, a diisocyanate, and at
least one diol or diamine chain extender. Diol chain extenders are
preferred because the polyurethanes made therewith have lower
melting points than if a diamine chain extender were used.
Polymeric glycols useful in the preparation of the elastomeric
polyurethanes include polyether glycols, polyester glycols,
polycarbonate glycols and copolymers thereof. Examples of such
glycols include poly(ethyleneether) glycol,
poly(tetramethyleneether) glycol,
poly(tetramethylene-co-2-methyl-tetramethyleneether) glycol,
poly(ethylene-co-1,4-butylene adipate) glycol,
poly(ethylene-co-1,2-propy- lene adipate) glycol,
poly(hexamethylene-co-2,2-dimethyl-1,3-propylene adipate),
poly(3-methyl-1,5-pentylene adipate) glycol,
poly(3-methyl-1,5-pentylene nonanoate) glycol,
poly(2,2-dimethyl-1,3-prop- ylene dodecanoate) glycol,
poly(pentane-1,5-carbonate) glycol, and poly(hexane-1,6-carbonate)
glycol. Useful diisocyanates include
1-isocyanato-4-[(4-isocyanatophenyl)methyl]benzene,
1-isocyanato-2-[(4-isocyanato-phenyl)methyl]benzene, isophorone
diisocyanate, 1,6-hexanediisocyanate,
2,2-bis(4-isocyanatophenyl)propane,
1,4-bis(p-isocyanato,alpha,alpha-dimethylbenzyl)benzene,
1,1'-methylenebis(4-isocyanatocyclohexane), and 2,4-tolylene
diisocyanate. Useful diol chain extenders include ethylene glycol,
1,3 propane diol, 1,4-butanediol, 2,2-dimethyl-1,3-propylene diol,
diethylene glycol, and mixtures thereof. Preferred polymeric
glycols are poly(tetramethyleneether) glycol,
poly(tetramethylene-co-2-methyl-tetrame- thyleneether) glycol,
poly(ethylene-co-1,4-butylene adipate) glycol, and
poly(2,2-dimethyl-1,3-propylene dodecanoate) glycol.
1-Isocyanato-4-[(4-isocyanatophenyl)methyl]benzene is a preferred
diisocyanate. Preferred diol chain extenders are 1,3 propane diol
and 1,4-butanediol. Monofunctional chain terminators such as
1-butanol and the like can be added to control the molecular weight
of the polymer. Useful thermoplastic polyester elastomers include
the polyetheresters made by the reaction of a polyether glycol with
a low-molecular weight diol, for example, a molecular weight of
less than about 250, and a dicarboxylic acid or diester thereof,
for example, terephthalic acid or dimethyl terephthalate. Useful
polyether glycols include poly(ethyleneether) glycol,
poly(tetramethyleneether) glycol,
poly(tetramethylene-co-2-methyltetramethyleneether) glycol [derived
from the copolymerization of tetrahydrofuran and
3-methyltetrahydrofuran] and poly(ethylene-co-tetramethyleneether)
glycol. Useful low-molecular weight diols include ethylene glycol,
1,3 propane diol, 1,4-butanediol, 2,2-dimethyl-1,3-propylene diol,
and mixtures thereof; 1,3 propane diol and 1,4-butanediol are
preferred. Useful dicarboxylic acids include terephthalic acid,
optionally with minor amounts of isophthalic acid, and diesters
thereof (e.g., <20 mol %).
[0045] Useful thermoplastic polyesteramide elastomers that can be
used in making the core of the fibers of the invention include
those described in U.S. Pat. No. 3,468,975. For example, such
elastomers can be prepared with polyester segments made by the
reaction of ethylene glycol, 1,2-propanediol, 1,3-propanediol,
1,4-butanediol, 2,2-dimethyl-1,3-propan- ediol, 1,5-pentanediol,
1,6-hexanediol, 1,10-decandiol, 1,4-di(methylol)cyclohexane,
diethylene glycol, or triethylene glycol with malonic acid,
succinic acid, glutaric acid, adipic acid, 2-methyladipic acid,
3-methyladipic acid, 3,4-dimethyladipic acid, pimelic acid, suberic
acid, azelaic acid, sebacic acid, or dodecandioic acid, or esters
thereof. Examples of polyamide segments in such polyesteramides
include those prepared by the reaction of hexamethylene diamine or
dodecamethylene diamine with terephthalic acid, oxalic acid, adipic
acid, or sebacic acid, and by the ring-opening polymerization of
caprolactam.
[0046] Thermoplastic polyetheresteramide elastomers, such as those
described in U.S. Pat. No. 4,230,838, can also be used to make the
fiber core. Such elastomers can be prepared, for example, by
preparing a dicarboxylic acid-terminated polyamide prepolymer from
a low molecular weight (for example, about 300 to about 15,000)
polycaprolactam, polyoenantholactam, polydodecanolactam,
polyundecanolactam, poly(11-aminoundecanoic acid),
poly(12-aminododecanoic acid), poly(hexamethylene adipate),
poly(hexamethylene azelate), poly(hexamethylene sebacate),
poly(hexamethylene undecanoate), poly(hexamethylene dodecanoate),
poly(nonamethylene adipate), or the like and succinic acid, adipic
acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid,
terephthalic acid, dodecanedioic acid, or the like. The prepolymer
can then be reacted with an hydroxy-terminated polyether, for
example poly(tetramethylene ether) glycol,
poly(tetramethylene-co-2-m- ethyltetramethylene ether) glycol,
poly(propylene ether) glycol, poly(ethylene ether) glycol, or the
like.
[0047] As noted above, the wings can be formed from any
non-elastomeric, or hard, polymer. Examples of such polymers
include non-elastomeric polyesters, polyamides, and
polyolefins.
[0048] Useful thermoplastic non-elastomeric wing polyesters include
poly(ethylene terephthalate) ("2G-T") and copolymers thereof,
poly(trimethylene terephthalate) ("3G-T"), polybutylene
terephthalate ("4G-T"), and poly(ethylene 2,6-naphthalate),
poly(1,4-cyclohexylenedimet- hylene terephthalate), poly(lactide),
poly(ethylene azelate), poly[ethylene-2,7-naphthalate],
poly(glycolic acid), poly(ethylene succinate),
poly(.alpha.,.alpha.-dimethylpropiolactone),
poly(parahydroxybenzoate), poly(ethylene oxybenzoate),
poly(ethylene isophthalate), poly(tetramethylene terephthalate,
poly(hexamethylene terephthalate), poly(decamethylene
terephthalate), poly(1,4-cyclohexane dimethylene terephthalate)
(trans), poly(ethylene 1,5-naphthalate), poly(ethylene
2,6-naphthalate), poly(1,4-cyclohexylidene dimethylene
terephthalate)(cis), and poly(1,4-cyclohexylidene dimethylene
terephthalate)(trans).
[0049] Preferred non-elastomeric polyesters include poly(ethylene
terephthalate), poly(trimethylene terephthalate), and
poly(1,4-butylene terephthalate) and copolymers thereof. When a
relatively high-melting polyesters such as poly(ethylene
terephthalate) is used, a comonomer can be incorporated into the
polyester so that it can be spun at reduced temperatures. Such
comonomers can include linear, cyclic, and branched aliphatic
dicarboxylic acids having 4-12 carbon atoms (for example
pentanedioic acid); aromatic dicarboxylic acids other than
terephthalic acid and having 8-12 carbon atoms (for example
isophthalic acid); linear, cyclic, and branched aliphatic diols
having 3-8 carbon atoms (for example 1,3-propane diol,
1,2-propanediol, 1,4-butanediol, and 2,2-dimethyl-1,3-propanediol);
and aliphatic and araliphatic ether glycols having 4-10 carbon
atoms (for example hydroquinone bis(2-hydroxyethyl) ether). The
comonomer can be present in the copolyester at a level in the range
of about 0.5 to 15 mole percent. Isophthalic acid, pentanedioic
acid, hexanedioic acid, 1,3-propane diol, and 1,4-butanediol are
preferred comonomers for poly(ethylene terephthalate) because they
are readily commercially available and inexpensive.
[0050] The wing polyester(s) can also contain minor amounts of
other comonomers, provided such comonomers do not have an adverse
affect on fiber properties. Such other comonomers include
5-sodium-sulfoisophthalat- e, for example, at a level in the range
of about 0.2 to 5 mole percent. Very small amounts, for example,
about 0.1 wt % to about 0.5 wt % based on total ingredients, of
trifunctional comonomers, for example trimellitic acid, can be
incorporated for viscosity control.
[0051] Useful thermoplastic non-elastomeric wing polyamides include
poly(hexamethylene adipamide) (nylon 6,6); polycaprolactam (nylon
6); polyenanthamide (nylon 7); nylon 10; poly(12-dodecanolactam)
(nylon 12); polytetramethyleneadipamide (nylon 4,6);
polyhexamethylene sebacamide (nylon 6,10); poly(hexamethylene
dodecanamide) (nylon 6,12); the polyamide of dodecamethylenediamine
and n-dodecanedioic acid (nylon 12,12), PACM-12 polyamide derived
from bis(4-aminocyclohexyl)methane and dodecanedioic acid, the
copolyamide of 30% hexamethylene diammonium isophthalate and 70%
hexamethylene diammonium adipate, the copolyamide of up to 30%
bis-(P-amidocyclohexyl)methylene, and terephthalic acid and
caprolactam, poly(4-aminobutyric acid) (nylon 4),
poly(8-aminooctanoic acid) (nylon 8), poly(hapta-methylene
pimelamide) (nylon 7,7), poly(octamethylene suberamide) (nylon
8,8), poly(nonamethylene azelamide) (nylon 9,9), poly(decamethylene
azelamide) (nylon 10,9), poly(decamethylene sebacamide (nylon
10,10), poly[bis(4-amino-cyclohexyl)-
methane-1,10-decanedicarboxamide], poly(m-xylene adipamide),
poly(p-xylene sebacamide), poly(2,2,2-trimethylhexamethylene
pimelamide), poly(piperazine sebacamide), poly(11-amino-undecanoic
acid) (nylon 11), polyhexamethylene isophthalamide,
polyhexamethylene terephthalamide, and poly(9-aminononanoic acid)
(nylon 9) polycaproamide. Copolyamides can also be used, for
example poly(hexamethylene-co-2-methylpentamethylene adipamide) in
which the hexamethylene moiety can be present at about 75-90 mol %
of total diamine-derived moieties.
[0052] Useful polyolefins include polypropylene, polyethylene,
polymethylpentane and copolymers and terpolymers of one or more of
ethylene or propylene with other unsaturated monomers. For example,
fibers comprising non-elastomeric polypropylene wings and an
elastomeric polypropylene core are within the scope of the present
invention; such fibers are bicomponent fibers.
[0053] Combinations of elastomeric and non-elastomeric polymers can
include a polyetheramide, for example, a polyetheresteramide,
elastomer core with polyamide wings and a polyetherester elastomer
core with polyester wings. For example a wing polymer can comprise
nylon 6-6, and copolymers thereof, for example,
poly(hexamethylene-co-2-methylpentamethy- lene adipamide) in which
the hexamethylene moiety is present at about 80 mol % optionally
mixed with about 1% up to about 15% by weight of nylon-12, and a
core polymer can comprise an elastomeric segmented
polyetheresteramide. "Segmented polyetheresteramide" means a
polymer having soft segments (long-chain polyether) covalently
bound (by the ester groups) to hard segments (short-chain
polyamides). Similar definitions correspond to segmented
polyetherester, segmented polyurethane, and the like. The nylon 12
can improve the wing adhesion to the core, especially when the core
is based on PEBAX.TM. 3533SN from Atofina. Another preferred wing
polymer can comprise a non-elastomeric polyester selected from the
group of poly(ethylene terephthalate) and copolymers thereof,
poly(trimethylene terephthalate), and poly(tetramethylene
terephthalate); an elastomeric core suitable for use therewith can
comprise a polyetherester comprising the reaction product of a
polyether glycol selected from the group of
poly(tetramethyleneether- ) glycol and
poly(tetramethylene-co-2-methyltetramethyleneether) glycol with
terephthalic acid or dimethyl terephthalate and a low molecular
weight diol selected from the group of 1,3-propane diol and
1,4-butane diol.
[0054] An elastomeric polyetherester core can also be used with
non-elastomeric polyamide wings, especially when an
adhesion-promoting additive is used, as described elsewhere herein.
For example, the wings of such a fiber can be selected from the
group of (a) poly(hexamethylene adipamide) and copolymers thereof
with 2-methylpentamethylene diamine and (b) polycaprolactam, and
the core of such a fiber can be selected from the group of (a)
polyetheresteramide and (b) the reaction products of
poly(tetramethyleneether) glycol or
poly(tetramethylene-co-2-methyltetram- ethyleneether) glycol with
terphthalic acid or dimethyl terephthalate and a diol selected from
the group of 1,3-propane diol and 1,4-butene diol.
[0055] Methods of making the polymers described above are known in
the art and may include the use of catalysts, co-catalysts, and
chain-branchers, as known in the art.
[0056] The high elasticity of the core permits it to absorb
compressional, torsional, and extensional forces as it is twisted
by the attached wings when the fiber is stretched and relaxed.
These forces will cause delamination of the wing and core polymers
if their attachment is too weak. Bonding can be enhanced by
selection of one or more of the wing(s) and core compositions or by
the use of a sheath as earlier described and/or the use of
additives to either or both polymers which enhance bonding.
Additives can be added to one or more of the wings, such that each
wing has the same or different degrees of attachment to the core.
Thus, typically the core and wing polymers should be selected such
that they have a sufficient compatibility that they will bond to
each other such that separation is minimized while the fibers are
made and used.
[0057] Also, additives can be added to the wing and/or core
polymers to improve adhesion, for example, nylon 12, e.g., 5% by
weight, based on total wing polymer, i.e., poly(12-dodecanolactam),
also known as "12" or "N12", commercially available as Rilsan
"AMNO" from Atofina. Also, maleic anhydride derivatives (for
example Bynel.RTM. CXA, a registered trademark of E. I. du Pont de
Nemours and Company or Lotader.RTM. ethylene/acrylic ester/maleic
anhydride terpolymers from Atofina) can be used to modify a
polyether-amide elastomer to improve it adhesion to a polyamide. As
another example, a thermoplastic novolac resin, for example
HRJ12700 (Schenectady International), having a number average
molecular weight in the range of about 400 to about 5000, could be
added to an elastomeric (co)polyetherester core to improve its
adhesion to (co)polyamide wings. The amount of novolac resin should
be in the range of 1-20 wt %, with a more preferred range of 2-10
wt %. Examples of the novolac resins useful herein include, but are
not limited to, phenol-formaldehyde, resorcinol-formaldehyde,
p-butylphenol-formaldehyde, p-ethylphenol-formaldehyde,
p-hexylphenol-formaldehyde, p-propylphenol-formaldehyde,
p-pentylphenol-formaldehyde, p-octylphenol-formaldehyde,
p-heptylphenol-formaldehyde, p-nonylphenol-formaldehyde,
bisphenol-A-formaldehyde, hydroxynapthaleneformaldehyde and alkyl-
(such as t-butyl-) phenol modified ester (such as penterythritol
ester) of rosin (particularly partially maleated rosin). See
allowed U.S. patent application Ser. No. 09/384,605, filed Aug. 27,
1999 for examples of techniques to provide improved adhesion
between copolyester elastomers and polyamide.
[0058] Polyesters functionalized with maleic anhydride ("MA") could
also be used as adhesion-promoting additives. For, example,
poly(butylene terephthalate) ("PBT") can be functionalized with MA
by free radical grafting in a twin screw extruder, according to J.
M. Bhaftacharya, Polymer International (August, 2000), 49: 8, pp.
860-866, who also reported that a few weight percent of the
resulting PBT-g-MA was used as a compatibilizer for binary blends
of poly(butylene terephthalate) with nylon 66 and poly(ethylene
terephthalate) with nylon 66. For example, such an additive could
be used to adhere more firmly (co)polyamide wings to a
(co)polyetherester core of the fiber of the present invention.
[0059] The polymers and resultant fibers, yarns, and articles used
in the present invention can comprise conventional additives, which
can be added during the polymerization process or to the formed
polymer or article, and may contribute towards improving the
polymer or fiber properties. Examples of these additives include
antistatics, antioxidants, antimicrobials, flameproofing agents,
dyestuffs, light stabilizers, polymerization catalysts and
auxiliaries, adhesion promoters, delustrants such as titanium
dioxide, matting agents, and organic phosphates.
[0060] Other additives that may be applied on the fibers, for
example, during spinning and/or drawing processes include
antistatics, slickening agents, adhesion promoters, hydrophilic
agents antioxidants, antimicrobials, flameproofing agents,
lubricants, and combinations thereof. Moreover, such additional
additives may be added during various steps of the process as is
known in the art.
[0061] The fibers of the invention can be in the form of continuous
filament (either a multifilament yarn or a monofilament) or staple
(including for example tow or spun yarn). The drawn fibers of the
invention can have a denier per fiber of from about 1.5 to about 60
(about 1.7-67 dtex). Fully drawn fibers of the invention with
polyamide wing typically have tenacities of about 1.5 to 3.0
g/dtex, and fibers with polyester wing, about 1-2.5 g/dtex,
depending on wing/core ratios. The resulting fibers of the
invention can have an after boil-off stretch of at least about 20%,
preferably of at least about 40% for improved comfort and fit in
the final garment.
[0062] While the above description focuses on advantages when the
fiber has a substantially radially symmetric cross-section, such
symmetry, while often desired, is not required for embodiments of
the invention where:
[0063] (a) the stretchable synthetic polymer fiber has at least
about 20% after boil-off shrinkage and requires less than about 10%
stretch to substantially straighten the fiber;
[0064] (b) the stretchable synthetic polymer fiber comprises an
axial core comprising an elastomeric polymer and a plurality of
wings comprising a non-elastomeric polymer attached to the core,
wherein the core includes on its outside surface a sheath of a
non-elastomeric polymer between points where the wings contact the
core;
[0065] (c) the stretchable synthetic polymer fiber comprises an
axial core comprising an elastomeric polymer and a plurality of
wings comprising a non-elastomeric polymer attached to the core,
wherein the core has a substantially circular or regular polyhedron
cross section; or
[0066] (d) the stretchable synthetic polymer fiber comprises an
axial core comprising an elastomeric polymer and a plurality of
wings comprising a non-elastomeric polymer attached to the core,
wherein at least one of the wings has a T, C, or S shape.
[0067] Such fibers according to these four embodiments can be made
and used and can provide one or more of the advantages described
herein.
[0068] When a yarn comprising a plurality of fibers is made, the
fibers can be of any desired fiber count and any desired dpf, and
the ratios of the elastomeric to non-elastomeric polymers can
differ from fiber to fiber. The multifilament yarn can contain a
plurality of different fibers, for example, from 2 to 100 fibers.
In addition, yarns comprising the fibers of the present invention
can have a range of linear densities per fiber and can also
comprise fibers not of the invention.
[0069] The synthetic polymer fibers of the present invention may be
used to form fabrics by known means including by weaving, warp
knitting, weft (including circular) knitting, or hosiery knitting.
Such fabrics have excellent stretch and power of recovery. The
fibers can be useful in textiles and fabrics, such as in
upholstery, and garments (including lingerie and hosiery) to form
all or a portion of the garment, including narrows. Apparel, such
as hoisiery, and fabrics made using the fibers and yarns of the
present invention have been found to be smooth, lightweight, and
very uniform ("non-picky") with good stretch and recovery
properties.
[0070] Further in accordance with the present invention, there is
provided a melt spinning process for spinning continuous polymer
fibers. This process will be described with respect to FIG. 5,
which is a schematic of an apparatus which can be used to make the
fibers of the present invention. However, it should be understood
that other apparatus may be used. The process of the present
invention comprises passing a melt comprising an elastomeric
polymer through a spinneret to form a plurality of stretchable
synthetic polymeric fibers including an axial core comprising the
elastomeric polymer and a plurality of wings attached to the core
and comprising the non-elastomeric polymer. With reference to FIG.
5, a thermoplastic hard polymer supply, which is not shown, is
introduced at 20 to a stacked plate spinneret assembly 35, and a
thermoplastic elastomeric polymer supply, which is not shown, is
introduced at 22 to a stacked pflate spinneret assembly 35.
Precoalescence or post coalescence spinneret packs can be used. The
two polymers can be extruded as undrawn filaments 40 from stacked
plate spinneret assembly 35 having orifices designed to give the
desired cross section. The process of the present invention further
includes quenching the filaments after they exit the capillary of
the spinneret to cool the fibers in any known manner, for example
by cool air at 50 in FIG. 5. Any suitable quenching method may be
used, such as cross-flow air or radially flowing air.
[0071] The filaments are optionally treated with a finish, such as
silicone oil optionally with magnesium stearate using any known
technique at a finish applicator 60 as shown in FIG. 5. These
filaments are then drawn, after quenching, so that they exhibit at
least about 20% after boil-off stretch. The filaments may be drawn
in at least one drawing step, for example between a feed roll 80
(which can be operated at 150 to 1000 meters/minute) and a draw
roll 90 shown schematically in FIG. 5 to form a drawn filament 100.
The drawing step can be coupled with spinning to make a fully-drawn
yarn or, if a partially oriented yarn is desired, in a split
process in which there is a delay between spinning and drawing.
Drawing can also be accomplished during winding the filaments as a
warp of yarns; called "draw warping" by those skilled in the art.
Any desired draw ratio, (short of that which interferes with
processing by breaking filament) can be imparted to the filament,
for example, a fully oriented yarn can be produced by a draw ratio
of about 3.0 to 4.5 times, and a partially oriented yarn produced
by a draw ratio of about 1.2-3.0 times. Herein, draw ratio is the
draw roll 90 peripheral speed divided by the feed roll 80
peripheral speed. Drawing can be carried out at about
15-100.degree. C., typically about 15-40.degree. C.
[0072] The drawn filament 100 optionally can be partly relaxed, for
example, with steam at 110 in FIG. 5. Any amount of heat-relaxation
can be carried out during spinning. The greater the relaxation, the
more elastic the filament, and the less shrinkage that occurs in
downstream operations. The drawn, final filament, after being
relaxed as described below, can have at least about 20% after
boil-off stretch. It is preferred to heat-relax the just-spun
filament by about 1-35% based on the length of the drawn filaments
before winding it up, so that it can be handled as a typical hard
yarn.
[0073] The quenched, drawn, and optionally relaxed filaments can
then be collected by winding at a speed of 200 to about 3500 meters
per minute and up to 4000 meters per minute, at a winder 130 in
FIG. 5. Or if multiple fibers have been spun and quenched, the
fibers can be converged, optionally interlaced, and then wound up
for example at up to 4000 meters per minute at winder 130, for
example in the range of about 200 to about 3500 meters per minute.
Single filament or multifilament yarns may be wound up at winder
130 in FIG. 5, in the same manner. Where multiple filaments have
been spun and quenched, the filaments can be converged and
oprtionally interlaced prior to winding as is done in the art.
[0074] At any time after being drawn, the biconstituent filament
may be dry- or wet-heattreated while fully relaxed to develop the
desired stretch and recovery properties. Such relaxation can be
accomplished during filament production, for example during the
above-described relaxation step, or after the filament has been
incorporated into a yarn or a fabric, for example during scouring,
dyeing, and the like. Heat-treatment in fiber or yarn form can be
carried out using hot rolls or a hot chest or in a jet-screen
bulking step, for example. It is preferred that such relaxed
heat-treatment be performed after the fiber is in a yarn or a
fabric so that up to that time it can be processed like a
non-elastomeric fiber; however, if desired, it can be heat-treated
and fully relaxed before being wound up as a high-stretch fiber.
For greater uniformity in the final fabric, the fiber can be
uniformly heat-treated and relaxed. The heat-treating/relaxation
temperature can be in the range of about 80.degree. C. to about
120.degree. C. when the heating medium is dry air, about 75.degree.
C. to about 100.degree. C. when the heating medium is hot water,
and about 101.degree. C. to about 115.degree. C. when the heating
medium is superatmospheric pressure steam (for example in an
autoclave). Lower temperatures can result in too little or no
heat-treatment, and higher temperatures can melt the elastomeric
core polymer. The heat-treating/relaxation step can generally be
accomplished in a few seconds.
[0075] As noted above, the spinneret capillary has a design
corresponding to the desired cross-section of the fibers of the
present invention, as described above, or to produce other
biconstituent or bicomponent fibers. The capillaries or spinneret
bore holes may be cut by any suitable method, such as by laser
cutting, as described in U.S. Pat. No. 5,168,143, drilling,
Electrical Discharge Machining (EDM), and punching, as is known in
the art. The capillary orifice can be cut using a laser beam for
good control of the cross-sectional symmetry of the fiber of the
invention. The orifices of the spinneret capillary can have any
suitable dimensions and can be cut to be continuous
(pre-coalescence) or non-continuous (post-coalescence). A
non-continuous capillary may be obtained by boring small holes in a
pattern that would allow the polymer to coalesce below the
spinneret face and form the multi-wing cross-section of the present
invention.
[0076] For example, the filaments of the invention can be made with
a precoalescence spinneret pack as illustrated in FIGS. 6, 6A, 6B
and 6C. In FIG. 6, a side elevation of the stacked plate spinneret
assembly as shown in FIG. 5, the polymer flow is in the direction
of arrow F. The first plate in the spinneret assembly is plate D
containing the polymer melt pool and is of a conventional design.
Plate D rests upon metering plate C (shown in cross sectional view
FIG. 6C), which in turn rests upon optional distribution plate B
(shown in cross sectional view FIG. 6B), which rests on spinneret
plate A (shown in cross sectional view FIG. 6A), which is supported
by spinneret assembly support plate E. Metering plate C is aligned
and in contact with distribution plate B below the metering plate,
the distribution plate being above, aligned with, and in contact
with spinneret plate A having capillaries there through but lacking
substantial counterbores, the spinneret plate(s) being aligned and
in contact with a spinneret support plate (E) having holes larger
than the capillaries. The alignments are such that a polymer fed to
the metering plate C can pass through distribution plate B,
spinneret plate A and spinneret support plate E to form a fiber.
Melt pool plate D, which is a conventional plate, is used to feed
the metering plate. The polymer melt pool plate D and spinneret
assembly support plate E are sufficiently thick and rigid that they
can be pressed firmly toward each other, thus preventing polymer
from leaking between the stacked plates of the spinneret assembly.
Plates A, B, and C are sufficiently thin that the orifices can be
cut with laser light methods. It is preferred that the holes in the
spinneret support plate (E) be flared, for example at about
45.degree.-60.degree., so that the just-spun fiber does not contact
the edges of the holes. It is also preferred that, when
precoalescence of the polymers is desired, the polymers be in
contact with each other (precoalescence) for less than about 0.30
cm, generally less than 0.15 cm, before the fiber is formed so that
the cross-sectional shape intended by the metering plate C,
optional distribution plate D, and spinneret plate design E is more
accurately exhibited in the fiber. More precise definition of the
fiber cross-section can also be aided by cutting the holes through
the plates as described in U.S. Pat. No. 5,168,143, in which a
multi-mode beam from a solid-state laser is reduced to a
predominantly single-mode beam (for example TM.sub.00 mode) and
focused to a spot of less than 100 microns in diameter and 0.2 to
0.3 mm above the sheet of metal. The resulting molten metal is
expelled from the lower surface of the metal sheet by a pressurized
fluid flowing coaxially with the laser beam. The distance from the
top of the uppermost distribution plate to the spinneret face can
be reduced to less than about 0.30 cm.
[0077] To make filaments having any number of symmetrically placed
wing polymer portions, the same number of symmetrically arranged
orifices are used in each of the plates. For example in FIG. 6A,
spinneret plate A is shown in a plan view oriented 90.degree. to
the stacked plate spinneret assembly of FIG. 5. Plate A in FIG. 6A
is comprised of six symmetrically arranged wing spinneret orifices
140 connected to a central round spinneret hole 142. Each of the
wing orifices 140 can have different widths 144 and 146. Shown in
FIG. 6B is the complementary distribution plate B having
distribution orifices 150 tapering at an open end 152 to optional
slot 154 connecting the distribution orifices to central round hole
156. Shown in FIG. 6C is metering plate C with metering capillaries
160 for the wing polymer and a central metering capillary 162 for
the core polymer. Polymer melt pool plate D can be of any
conventional design in the art. Spinneret support plate E has a
through hole large enough and flared away (for example at
45-60.degree.) from the path of the newly spun filament so that the
filament does not touch the sides of the hole, as is shown in FIGS.
5 and 6 side elevation. The stacked spinneret plate Assembly,
plates A through D, are aligned so that core polymer flows from
polymer melt pool plate D through central metering hole 162 of
metering plate C and through the 6 small capillaries 164, through
central circular capillary 156 of distribution plate B, through
central circular capillary 142 of spinneret assembly plate A, and
out through large flared hole in spinneret support plate E. At the
same time, wing polymer flows from polymer melt pool plate D
through wing polymer metering capillaries 160 of metering plate C,
through distribution orifices 150 of distribution plate B (in
which, if optional slot 154 is present, the two polymers first make
contact with each other), through wing polymer orifices 140 of
spinneret plate A, and finally out through the hole in spinneret
assembly support plate E.
[0078] The spinneret pack of the invention can be used for the melt
extrusion of a plurality of synthetic polymers to produce a fiber.
In the spinneret pack of the present invention, the polymers can be
fed directly into the spinneret capillaries, since the spinneret
plate does not have a substantial counterbore. By no substantial
counterbore is meant that the length of any counterbore present
(including any recess connecting the entrances of a plurality of
capillaries) is less than about 60%, and preferably less than about
40%, of the length of the spinneret capillary. Directly metering
multicomponent polymer streams into specific points at the backside
entrance of the fiber forming orifice in the spinneret plate
eliminates problems in polymer migration when multiple polymer
streams are combined in feed channels substantially before the
spinneret orifice, as is the norm.
[0079] It can be useful to combine the functions of two plates into
one through the use of recessed grooves, on one or both sides of
the single plate with appropriate holes through the plate to
connect the grooves. For example, recesses, grooves and depressions
can be cut in the upstream side of the spinneret plate (for example
by electrodischarge machining) and can function as distribution
channels or shallow, insubstantial counterbores.
[0080] A variety of fibers comprising two or more polymers can be
made with the spinneret pack of the present invention. For example,
other biconstituent fibers and bicomponent fibers not disclosed
and/or claimed herein can be so made, including the cross-sections
disclosed in U.S. Pat. Nos. 4,861,660, 3,458,390, and 3,671,379.
The resulting fiber cross-section can be for example side-by-side,
eccentric sheath-core, concentric sheath-core, wing-and-core,
wing-and-sheath-and core, and the like. Moreover, the spinneret
pack of the invention can be used to spin splittable or
non-splittable fibers.
[0081] In FIG. 7 a side elevation of the spinneret assembly stacked
plates as shown in FIG. 5 is represented, where the polymer flow is
in the direction of the arrows. The use of this assembly is
exemplied in Example 6 below. The first plate in the spinneret
assembly is plate D containing the polymer melt pool. This plate is
of a conventional design known in the art and contains passages 20
and 22 for introduction of the non-elastomeric wing and sheath
polymer and the elastomeric polymer respectively. Plate D rests
upon metering plate H, which in turn rests upon distribution plate
G, which rests on spinneret plate F, which rests upon plate C,
which rests upon plate B, which rests upon the spinneret or plate
A, which is supported by spinneret assembly support plate E. The
polymer melt pool plate D and spinneret assembly support plate E
are sufficiently thick and rigid and pressed firmly toward each
other, thus preventing polymer from leaking between the stacked
plates of the spinneret assembly. All other plates are sufficiently
thin so that the orifices can be cut using laser light machining
methods. FIGS. 7A-7C and FIGS. 7F-7H represent a plan view an
alternative stacked plate spinneret assembly useful in making
certain fibers of the present invention represented by the cross
sectional view in FIG. 5. The elastomeric core polymer and
non-elastomeric wing and sheath polymers are joined in FIGS. 7A-7C
and FIGS. 7F-7H using a precoalescence spinneret plate pack
assembly of the same general type illustrated in the side elevation
view of FIG. 6. In this alternative stacked plate spinneret
assembly, a spinneret assembly support plate E, spinneret plate A,
and polymer melt pool plate D are used, but five plates replace
distribution plate B and metering plate C. Through spinneret plate
A, shown in FIG. 7A are cut wing orifices 210, a central core
polymer and sheath polymer hole 214, and connecting slots 212.
Plate B, as shown in FIG. 7B, is cut through with wing orifices 220
and a central core polymer and sheath polymer hole 222 centered
above spinneret plate A. Centered above plate B is plate C, as
shown in FIG. 7C, cut through it are cone-shaped wing and sheath
polymer orifices 230, a central core polymer and sheath polymer
hole 232. An annular shaped portion of the plate 234 remains
connected to the plate. Centered above plate C is plate F, shown in
FIG. 7F, cut through with wing orifices 240 and central core
polymer and sheath polymer hole 242. Centered above plate F is
plate G, as shown in FIG. 7G, cut through with wing orifices 250,
cone-shaped wing polymer and sheath polymer orifices 252, and a
central core polymer hole 254. Centered above plate G is plate H,
as shown in FIG. 7H, cut through it are wing polymer orifices 260,
wing polymer and sheath polymer orifices 262, and a central core
polymer hole 264.
[0082] The invention is illustrated by the following non-limiting
examples. The following test methods were used in the Examples.
Test Methods
[0083] The term after boil-off stretch is used interchangeably in
the art with the following terms: "% stretch", "recoverable
stretch", "recoverable shrinkage" and "crimp potential". The term
"non-recoverable shrinkage" is used interchangeably with the
following terms: "% shrinkage", "apparent shrinkage" and "absolute
shrinkage".
[0084] Stretch properties (after boil-off stretch, after boil-off
shrinkage and stretch recovery after boil-off) of the fibers
prepared in the Examples were determined as follows. A 5000 denier
(5550 dtex) skein was wound on a 54 inch (137 cm) reel. Both sides
of the looped skein were included in the total denier. Initial
skein lengths with a 2 gram weight (length CB) and with a 1000 gram
weight (0.2 gldenier) (length LB) were measured. The skein was
subjected to 30 minutes in 95.degree. C. water ("boil off"), and
initial (after boil off) lengths with a 2 gram weight (length
CA.sub.initial) and with a 1000 gram weight (length LA.sub.initial)
were measured. After measurement with the 1000 gram weight,
additional lengths were measured with a 2 gram weight after 30
seconds (length CA.sub.30sec) and after 2 hours (length
CA.sub.2hrs). Shrinkage after boil-off was calculated as
100.times.(LB-LA)/LB. Percent after boil-off stretch was calculated
as 100.times.(LA-CA@30 sec)/CA@30 sec. Stretch recovery after
boil-off was calculated as
100.times.(LA-CA.sub.2hrs)/(LA-CA.sub.initial).
[0085] The test for unload force at 20% and 35% available stretch
was performed as follows. A biconstituent fiber skein having a
total denier of 5000 (5550 dtex) after boil off was prepared. Both
sides of the looped skein were included in the total denier. An
Instron tensile tester (Canton, Mass.) was used at 21.degree. C.
and 65% relative humidity. The skein was placed in the tester jaws,
between which there was a 3 inch (76 mm) gap. The tester was cycled
through three stretch-and-relax (load-and-unload) cycles, each load
cycle having a maximum of 500 grams force (0.2 grams per denier),
and then the force on the 3.sup.rd unload cycle was determined. An
effective denier (that is, the actual linear density at the test
elongation) was determined for 20% and 35% available stretch on the
3.sup.rd unload cycle. "20% and 35% available stretch" means that
the skein had been relaxed 20% and 35%, respectively, from the 500
gram force on the 3.sup.rd cycle. The unload force at 20% and 35%
available stretch was recorded in milligrams per effective denier
(mg/denier).
[0086] Delamination of the wings from the core of a fiber was
determined by first winding a 5000 denier (5550 dtex) skein (the
skein size included both sides of the resulting loop) on a 1.25
meter reel. The skein was subjected to 102.degree. C. steam in an
autoclave for 30 minutes. A 20 cm length individual fiber was
selected from the skein and folded once in half. The open end of
the resulting loop was taped together at the bottom, and the taped
loop was hung vertically on a hook. A weight of 1 gram per denier
(50 grams for a 25 denier loop) was attached to the bottom (taped)
end of the loop. The weight was raised to the point at which the
loop was slack, and then lowered gently to stretch the loop and
apply the full weight. After 10 such cycles the loop was examined
for delamination under magnification and rated. Three samples were
rated as follows:
[0087] 0=No wing/core delamination visable along the fiber
[0088] 1=Slight delamination observed at one or more of the node
reversals
[0089] 2=Delamination observed where the fiber rubbed against the
hook from which it was hanging
[0090] 3=Marginal delamination (in small loops, and only in a few
spots)
[0091] 4=Small loops indicating delamination along the entire
fiber
[0092] 5=Gross delamination (large loops all along the fiber)
[0093] The results from the three samples were averaged.
[0094] R.sub.1 and R.sub.2 were measured by superimposing two
circles on a photomicrograph of a cross-section of the fiber so
that one circle (R.sub.1) circumscribed the approximate outermost
extent of the core polymer and the other circle (R.sub.2) inscribed
the approximate innermost extent of the wing polymer.
EXAMPLE 1.A
[0095] A biconstituent fiber of the invention having a symmetrical
six-wing cross-section substantially as shown in FIG. 1 was spun
using an apparatus as illustrated in FIG. 5. A single fiber 40 was
spun using spinneret plate 35 and a spinneret temperature of
265.degree. C. At 20 in FIG. 5 a melted nylon polymer
conventionally prepared and having a relative viscosity of about
45-60, was introduced to the spin pack assembly 30. The nylon
polymer which formed the wing portion of the biconstituent filament
was poly(hexamethylene-co-2-methylpentamethylene adipamide) in
which the hexamethylene moiety was present at 80 mol %
(6/MPMD(80/20)-6) to which 5% by weight based on total wing
polymer, nylon 12 (poly(12-dodecanolactam)) (also known as "12" or
"N12") (Rilsan.RTM. "AMNO" from Atofina) had been added. The nylon
12 was added to aid wing-to-core cohesion. The wing portions were
45 wt % of the fiber. A second polymer, which formed the core of
the fiber, was introduced at 22 to spin pack assembly 30 in FIG. 5.
The core polymer was an elastomeric segmented polyetheresteramide
(PEBAX.TM. 3533SN from Atofina; flex modulus 2800 psi (19,300
kPascals)) and was metered volumetrically to create a core which
was 55 wt % of the biconstituent fiber.
[0096] Precoalescence spinneret pack assembly 30 was comprised of
stacked plates labeled A through E in FIG. 6. Orifices were cut
through 0.015 inch (0.038 cm) thick stainless steel spinneret plate
A as six wings arranged symmetrically at 60 degrees, around a
center of symmetry using a process as described in U.S. Pat. No.
5,168,143. As illustrated in FIG. 6A, each wing orifice 140 was
straight with a long axis centerline passing through the center of
symmetry and had a length of 0.049 inches (0.124 cm) from tip to
the circumference of a central round spinneret hole 142 (diameter
0.012 inches [0.030 cm]) with origin of radius the same as the
center of symmetry. There was no counterbore at the entrance to the
spinneret capillary. The wing length 144 from tip to 0.027 inches
(0.069 cm) was 0.0042 inches (0.0107 cm) wide; the remaining length
146 of 0.022 inches (0.056 cm) was 0.0032 inches (0.0081 cm) wide.
The tip of each wing was radius-cut at one-half the width of the
tip. Distribution plate B of 0.015 inches (0.038 cm) thickness was
aligned with the spinneret plate A so that its distribution
orifices were congruent with the spinneret orifices in the
spinneret plate A. The six wing orifices of plate B were 0.094 inch
(0.239 cm) long and 0.020 inch (0.051 cm) wide, and their wing tips
were rounded to a radius one-half their width. As illustrated in
FIG. 6B, each of the six wing orifices 150 of distribution plate B
tapered to a rounded (0.006 inch [0.015 cm] diameter) open end 156
and then continued as a slot of 0.013 inch (0.033 cm) length and
0.0018 inch (0.0046 cm) length to central hole 156. The central
hole 156 in this plate was 0.0125 inches (0.032 cm) in diameter. A
slot 154 connected the central hole with the end of each wing
distribution orifice. Metering plate C was of 0.010 inch (0.025 cm)
thickness (see FIG. 6C). Each of the metering holes was centered
above a wing long axis centerline or above the center of symmetry
in distribution plate B. The central metering hole 152 and one hole
per wing 160 were 0.010 inch (0.025 cm) diameter; the centers of
holes 160 were 0.120 inch (0.305 cm) from the center of hole 162.
The central metering hole was fed filtered melted elastomeric
polymer from a conventional melt pool plate D (see FIG. 6) and
formed the core element within the final fiber. The outer six
metering holes of plate C were fed a non-elastomeric polymer from
melt pool plate D to become the polymer wings. Large holes
(typically 0.1875 inches (0.4763 cm) in diameter) in spinneret
support plate E (see again FIG. 6) were aligned with the spinneret
orifices in spinneret plate A and were flared at 45.degree..
Spinneret plate A, distribution plate B, and metering plate C were
sandwiched by melt pool plate D and spinneret support plate E.
Typically, plate E was 0.2-0.5 inches (0.4-1.3 cm) thick, and plate
D was 0.02-0.03 inches (0.05-0.08 cm) thick.
[0097] A single freshly spun fiber 40 (see FIG. 5) was cooled to
solidify it by a flow of air 50, and a finish (about 5 wt % based
on fiber) comprising silicone oil and a metal stearate was applied
at 60. The fiber was forwarded to a draw zone between feed roll 80
and draw roll 90, taking several wraps about each roll. The speed
of draw roll 90 was four times that of feed roll 80 for a draw
ratio of 4.times.; the latter speed was 350 meters per minute. The
fiber was then treated with steam at 6 pounds per square inch 0.87
kilopascal) in a chamber 110; winder 130 was operated at a speed
20% lower than that of draw roll 90 so that the fiber was partly
(20%) relaxed in order to reduce shrinkage in the final fiber. The
drawn and partly relaxed fiber 120 was wound up at winder 130 and
had a linear density of 27 denier (30 dtex).
EXAMPLE 1.B
[0098] A biconstituent yarn of the invention having 10 fibers, each
with 6 radially symmetric wings of nylon 6-12 (poly(hexamethylene
dodecanamide)), (intrinsic viscosity 1.18), Zytel.RTM. 158, a
registered trademark of E. I. du Pont de Nemours and Company; flex
modulus 295,000 psi (2.0 million kPascals) and a core of PEBAX.TM.
3533SA was spun using the apparatus of FIG. 5 in substantially the
same way as in Example 1.A, except that the spinneret temperature
was 240.degree. C., distribution plate B had no slot 154, and 4 wt
% of a polyetherester-based finish was applied in place of the
finish applied in Example 1.A, the draw ratio was 3.75.times., and
the yarn was relaxed 15%. The drawn and partly relaxed yarn had a
linear density of 80 denier (88 dtex). A photomicrograph of the
cross-section of the resulting fiber is shown in FIG. 8.
EXAMPLE 1.C
[0099] A biconstituent yarn of the invention of 10 filaments with
five radially symmetric wings on each filament of poly(butylene
terephthalate) (4G-T) (Crastin.RTM. Type 6129, a registered
trademark of E. I. du Pont de Nemours and Company; 350,000 psi flex
modulus (2.4 million kPascals)) and having a HYTREL.RTM. (a
registered trademark of E. I. du Pont de Nemours & Company,
Inc.) 3078 elastomeric polyetherester core was prepared analogously
to that of Example 1.A except that: each plate had five holes for
wing polymer supply arranged symmetrically at 72.degree. apart; the
metering plate C had an additional set of holes, one per wing on
the centerline of the wing; the 4G-T wings had no cohesion
additive; 4 wt % of a finish comprising polysiloxane as described
in U.S. Pat. No. 4,999,120 was used in place of the finish applied
in Example 1.A; the feed roll speed was 250 meters per minute; the
draw ratio was 3.6.times.; and the steam pressure for relaxation
was 20 pounds per square inch 2.9 kilopascal). The drawn and partly
relaxed yarn had a linear density of 150 denier (165 dtex).
[0100] With regard to the additional set of holes on the metering
plate C, one per wing on the centerline of the wing, each hole was
0.005 inches (0.013 cm) in diameter and 0.0475 inches (0.121 cm)
from the center of symmetry of the holes. However, the additional
holes were not fed melted polymer by melt pool plate D.
[0101] The yarns prepared in Example 1.A-C were compared for after
boil-off stretch, after boil-off shrinkage, and stretch recovery
after boil-off. The test was carried out by first preparing a 5000
denier (5550 dtex) skein of yarn which was wound on a 54 inch (137
cm) reel. Both sides of the looped skein were included in the total
denier. The initial skein length with a light and a heavy weight
were measured and the following measurements were recorded:
[0102] CB=measured skein length with 2 gram weight
[0103] LB=measured skein length with 1000 gram weight (0.2 grams
per denier).
[0104] The following initial and final lengths were measured after
hot aqueous treatment or "boil off" which subjected the skein to a
30 minute dip in 95.degree. C. water:
[0105] CA (initial)=measured skein length after treatment with 2
gram weight
[0106] LA=measured skein length after treatment with 1000 gram
weight applied (0.2 grams per denier)
[0107] CA (30 seconds)=measured skein length 30 seconds after LA
measured with 1000 gram weight removed and 2 gram weight
applied
[0108] CA (2 hrs)=measured skein length 2 hours after LA measured,
with 2 gram weight applied
[0109] These measurements were used to calculate the yarn
characteristics as follows:
[0110] Percent Stretch after boil
off=100.times.(LA-CA@30sec)/CA@30sec
[0111] Boil-Off Shrinkage=100.times.(LB-LA)/LB.
[0112] Percent Recovery after boil-off=100.times.(LA-CA@2hrs)
(LA-CA@initial)
[0113] The yarn properties of boil-off shrinkage, percent after
boil-off stretch and stretch recovery reported in Table 1 for the
yarns of Example 1.A-1.C are suitable for hosiery and apparel
applications.
1 TABLE 1 Example 1.A Example 1.B Example 1.C Drawn 27 den. 80 den.
150 den. denier/no. of (30 dtex)/1 (88dtex)/10 (165dtex.)/10 fibers
Number of 6 6 5 Wings Wing 6/MPMD-6 + 6-12 4G-T 5% N12 Core PEBAX
.TM. PEBAX .TM. HYTREL .TM. 3533SN 3533SA 3078 % stretch after 78
76 75 boil off % Boil-Off 19 16 17 Shrinkage % recovery 94 92 94
after boil off
EXAMPLE 2
[0114] A sheer hosiery leg blank was knitted using four fibers
prepared in Example 1.A. A commercial four-feed hosiery machine
(Lanoti Model 400, 402 needles) was used. The fibers were knit in a
typical four-feed, every-course jersey leg construction typical for
commercial pantyhose.
[0115] The filaments were knit directly from the wound package and
behaved like a "hard" yarn, that is, without elastomeric character.
The four filaments were independently fed to the machine needles
directly through standard creel guides, each of which had a
conventional dancer ring tensioner typically used for feeding
non-elastomeric yarns to hosiery knitting machines. The hose blanks
were knit at 700 rpm in the thigh area and 800 rpm in the ankle.
Each blank was knit in about 2 minutes, including a panty portion
in a standard nylon spandex panty style.
[0116] The griege size of the hose blank was adjusted by
conventional means to meet standard size specifications. Next, the
greige hosiery leg blanks were heat-treated to activate the latent
stretch characteristic in the biconstituent fiber. This was done in
one of two ways. In one method, the greige pantyhose blanks were
placed in a cloth bag and agitated in a water bath at room
temperature. The bath was raised in temperature with steam to
85.degree. C. over 45 mintues and then cooled with room temperature
water while agitated. The bagged blanks were dewatered in a
centrifuge and dried in an oven at 100.degree. C. In another
method, the blanks were shrunk by tumble steaming using atmospheric
pressure steam for 30 minutes. In either case, the fiber of the
invention was made highly stretchable but not bulky by the relaxed
hot treatment. The blanks were then removed from the bags and sewn
into pantyhose in a conventional way. The garments were then
rebagged and dyed using standard acid dye procedures for nylon
hosiery with a maximum dye bath temperature of 99.degree. C. The
dyed garments were dewatered, dried, and boarded on standard 4 inch
(10.2 cm) base width hosiery boards. The boarding autoclave was set
to treat the hose for 4 seconds at 102.degree. C., followed by
drying at 99.degree. C. for 30 seconds. The pantyhose were placed
on the boards so that they remained as small as possible while
holding the fabric in a wrinkle-free state. The appearance of the
finished garments was suitable for sheer hosiery applications, and
they showed good stretch and recovery. Their shrinkage at each
stage of finishing was measured as described below, and the
magnitude and consistency of sizing of the finished goods was found
suitable for the commercial manufacture of hosiery products.
[0117] Cross-stretch measurements were taken on the greige fabric
and again after a ten-minute hot aqueous treatment (boil off) to
assess shrinkage and potential to meet typical size standards. The
cross-stretch measurements were made by slipping each blank over
the jaws of a Dinema S.R.L. instrument, separating the jaws, and
measuring the percent stretch when the force on the jaws reached
4500 grams. Measurements were taken 3 inches (7.6 cm) below the
crotch ("Thigh"), 1/2 way between the toe and the crotch ("Knee"),
and about 3.5 inches (8.9 cm) up from the toe ("Foot"). The leg
pull stretch was measured similarly except that each blank was
clamped length-wise between the jaws of the instrument. The stretch
values were 22% for the thigh, 21% for the knee, 17% for the foot,
and 138% for the leg pull. A shrinkage level of approximately
17-24% from greige to boil-off dimension was determined for the
thigh, knee, foot, and leg pull and was little changed after
further boarding and dyeing, indicating that the blanks were
dimensionally stable, as needed for commercial use.
EXAMPLE 3
[0118] Yarns from Example 1.B were used to construct a weft-stretch
woven fabric on a shuttle loom in a "Crowfoot" construction with
TACTEL.RTM. a registered trademark of E. I. du Pont de Nemours and
Company) 70 denier (78 decitex) 6-6 nylon in the warp with 102 ends
per inch (40/cm). The Example 1.B 80 denier (89 decitex) 10
filament biconstituent yarn was the weft fiber at 100 picks per
inch (39/cm). The greige woven fabric width was 62.5 inches (159
cm). This fabric was finished using a relaxed state scour at
71.degree. C., followed by a second relaxed scour at 118.degree. C.
After drying, this fabric had a relaxed width of 36 inches (91 cm).
This fabric was dyed at 100.degree. C. with standard acid dyes for
nylon. The after dyeing wet width was 33 inches (84 cm). Finally,
this fabric was air dried without heat setting. The final width was
33.25 inches (84 cm). This fabric was non-bulky, smooth and
non-wrinkled after only air drying. The fabric showed good stretch
and recovery, and excellent hard fiber hand and aesthetics. In the
relaxed finished state, this fabric had the following
properties:
2 Basis weight: 4.45 oz./yard.sup.2 (151 grams/m.sup.2); Thickness:
0.0103 inch (0.0262 cm); Fill Count: 112 weft threads per inch
(44/cm); Warp Count: 192 warp threads per inch (76.8/cm).
[0119] A 5 cm width by 10 cm length of this fabric was evaluated
for hand stretch to full extension in the weft. The fabric could be
stretched 65% of its relaxed length and showed recovery after hand
stretching of greater than 95% of the difference between its
stretched and relaxed length.
EXAMPLE 4
[0120] Yarns from Example 1.C were used to construct a weft-stretch
woven fabric on a shuttle loom in a plain weave construction with
DuPont TACTEL.RTM. 70 denier (78 decitex) 6-6 nylon in the warp
with 102 ends per inch (40/cm). The Example 1.C 150 denier (166
decitex) 10 filament biconstituent yarn was the weft fiber at 50
picks per inch (19.7/cm). The greige woven fabric width was 63.5
inches (161 cm). This fabric was finished using a relaxed state
scour at 82.degree. C. for 20 minutes. The fabric was dyed at
100.degree. C. for 60 minutes with standard acid dyes for nylon,
and dried at 93.degree. C. The final dry width was 33.5 inches (85
cm). This fabric was non-bulky, smooth and non-wrinkled. The fabric
showed good stretch and recovery, and excellent hard fiber hand and
aesthetics. In the relaxed finished state, this fabric had the
following properties:
3 Basis weight: 4.5 oz./yard.sup.2 (152 grams/m.sup.2); Thickness:
0.0115 inch (0.0292 cm); Fill Count: 60 weft threads per inch
(23.6/cm); Warp Count: 204 warp threads per inch (80/cm).
[0121] A 5 cm width by 10 cm length of this fabric was evaluated
for hand stretch to full extension in the weft. The fabric could be
stretched 72.8% of its relaxed length and showed recovery after
hand stretching of greater than 97% of the difference between its
stretched and relaxed length.
EXAMPLE 5
[0122] This example illustrates the benefit of using an adhesion
promoter (see Example 5B) in making the fiber of the invention.
Biconstituent fibers were spun using the apparatus illustrated in
FIG. 5 and the conditions and spinneret pack analogous to those
described for Example 1.A. Each drawn fiber had a linear density of
26 denier (28.6 dtex). After-boil-off properties and delamination
ratings are reported in Table 2.
EXAMPLE 5.A.
[0123] The elastomeric core polymer was an elastomeric
polyetheresteramide (PEBAX.TM. 3533SN, from Atofina) and was
metered volumetrically during spinning to create a core which was
51 wt % of each fiber. The nylon blend, which formed the six wings,
was poly(hexamethylene-co-2-methylpent- amethylene adipamide), as
described in Example 1.A. A photomicrograph of the cross-section of
the resulting fiber is shown in FIG. 9.
EXAMPLE 5.B.
[0124] A fiber having 6 wings of 6/MPMD(80/20)-6 polyamide
(poly(hexamethylene-co-2-methylpentamethylene adipamide) in which
the hexamethylene moiety was present at 80 mol %) and a core of
elastomeric polyetheresteramide (PEBAX.TM. 3533SN) was spun
substantially as in Example 5.A. except that 5 wt %
poly(12-dodecanolactam as described in Example 1.A was added to the
wing polymer to aid in wing-to-core cohesion.
[0125] Delamination of the wings from the core of a fiber was
determined by first winding a 5000 denier (5550 dtex) skein (the
skein size included both sides of the resulting loop) on a 1.25
meter reel. The skein was subjected to 102.degree. C. steam in an
autoclave for 30 minutes. An individual fiber having a length of 20
cm was selected from the skein and folded once in half. The open
end of the resulting loop was taped together at the bottom, and the
taped loop was hung vertically on a hook. A weight of 1 gram per
denier (0.9 dN/tex) (50 grams for a 25 denier [28 dtex] loop) was
attached to the bottom (taped) end of the loop. The weight was
raised to the point at which the loop was slack, and then lowered
gently to stretch the loop and apply the full weight. After 10 such
cycles the loop was examined for delamination under magnification
and rated. Three samples were rated as follows:
[0126] 0=No wing/core delamination visable along the fiber
[0127] 1=Slight delamination observed at one or more of the node
reversals
[0128] 2=Delamination observed where the fiber rubbed against the
hook from which it was hanging
[0129] 3=Marginal delamination (in small loops, and only in a few
spots)
[0130] 4=Small loops indicating delamination along the entire
fiber
[0131] 5=Gross delamination (large loops all along the fiber)
[0132] The results from the three samples were averaged and are
reported in Table 2.
4 TABLE 2 Example Example 5.A 5.B Wing polymer 6/MPMD-6 6/MPMD-6 +
5% N12 Core polymer PEBAX .TM. PEBAX .TM. 3533SN 3533SN % stretch
66.7 92.1 after boil off % shrinkage 31 19 after boil off
Delamination 3.8 1.2 rating
[0133] The results show that using selected pairs of core and wing
polymers can give a fiber that resists delamination (Example 5.A)
and that using an adhesion promoter can have a beneficial effect on
further reducing the delamination rating of the fiber, for example
to below a rating of about 2.5 (Example 5.B).
EXAMPLE 6
[0134] This example illustrates a fiber of the invention having a
particular two-wing cross-section and the use of a thin sheath
comprising the same polymer as the wings and continuously
connecting the wings. In this case a side of each wing (as distinct
from an end of the wing) is attached to the core so the wing has a
T-shape (See FIG. 4). The thin sheath encapsulates the core and
eliminates the contact of the elastomer with surfaces.
[0135] In making the fiber in this Example, poly(hexamethylene
dodecanamide) (Zytel.RTM. 158) was used as the wing polymer and a
polyetherester having a
poly(tetramethylene-co-2-methyltetramethylene ether) glycol soft
segment and butylene terephthalate (4G-T) hard segment, prepared
substantially as described in U.S. Pat. No. 4,906,721 was used as
the core. The amount of 3-methyltetrahydrofuran incorporated into
the copolyether glycol was 9 mol %, the glycol number average MW
was 2750, and the mole ratio of 4G-T to copolyether glycol was
4.6:1.
[0136] The polymers were spun using the configuration of spinneret
plates as shown in FIGS. 7A-7C and FIGS. 7F-7H. In spinneret plate
A (FIG. 7A), the sheath-core hole had a diameter of 0.011 inches
[0.028 cm]. The core-and-sheath hole of first plate B (FIG. 7B) had
a diameter of 0.008 inches [0.020 cm]. The core-and-sheath hole of
first plate B (FIG. 7B) had a diameter of 0.025 inches [0.064 cm],
and the annulus of this plate had an outer diameter of 0.100 inches
[0.254cm]. The core-and-sheath hole of third plate F (FIG. 7F) had
a diameter of 0.125 inches [0.318 cm]. The central core hole of
fourth plate G (FIG. 7G) had a diameter 0.025 inches [0.064 cm])
and the annulus of this plate had an outer diameter of 0.100 inches
[0.254 cm]. The central core hole of the fifth plate H (FIG. 7H)
had a diameter of 0.033 inches [0.084 cm].
[0137] The central holes and annuli were of dimensions such that
the polymer flows were as follows. Core polymer was fed straight
through the central core holes of each of the plates.
Wing-and-sheath polymer was fed to the wing orifices and outer part
of the core hole of spinneret plate A by the wing orifices and the
outer part of central hole of plate B, respectively. The first
contact between wing and core was therefore in spinneret plate A.
The cone-shaped wing-and-sheath orifices of plate C fed part of the
polymer downward into the wing orifices of plate B and fed part of
the polymer upward to the outer edge of central hole of plate F,
thus forming part of the sheath. The cone-shaped wing-and-sheath
orifices of plate C were fed by the orifices of plate F. The
orifices of plate F were fed by the orifices of plate G. The
cone-shaped orifice of plate G fed the outer edge of the central
hole of plate F, thus forming the other part of the sheath. The
first contact between sheath and core was therefore at plate F. The
orifices in plate H fed the orifices, respectively, in plate G.
[0138] In the fibers made in this example, the weight ratio of wing
to core was 56/44, and the sheath was about 10 wt % of the total
wing content. This percent can be varied from about 2 to about 20
wt %. Ten filaments were spun, drawn 3.6.times. without relaxation,
and wound up at 900 meters per minute. Upon relaxed exposure to
atmospheric pressure steam, the fiber immediately shrank and
thereafter exhibited good stretch and recovery.
EXAMPLE 7
[0139] This example shows that fully circumferential spiral twist
is unnecessary to achieve the stretch and recovery desired in the
fiber of the invention.
[0140] The wing and core polymers used in Example 1.C were spun
through a spinneret pack similar to that used in Example 1.A, with
the following differences: the wing orifices in spinneret plate A
had a length of 0.023 inches (0.058 cm), and the central round hole
had a diameter of 0.008 inches (0.200 cm); distribution plate B
lacked slots 154 (see FIG. 6B); ten fibers were spun to form a
yarn, each fiber being 33 wt % wing polymer; the yarn was drawn
3.3.times. without relaxation and wound up at 1040 meters/minute.
FIGS. 8 and 9 are photomicrographs of the resulting fibers in the
yarn, showing both circumferential spiral twist and
noncircumferential spiral twist of the wings. Circumferential twist
sections and noncircumferential twist sections had similar
responses to full relaxation: a 10 cm length subjected to
atmospheric pressure steam shrank to 4.8 cm. Repeated
stretch-and-relax cycles (to 10 cm) resulted in a length of 6.5 cm,
which however again shrank to 4.8 cm on renewed exposure to
atmospheric pressure steam, indicating a reversible set.
[0141] While the invention has been described in conjunction with
the detailed description thereof, it is to be understood that the
foregoing description is exemplary and explanatory in nature, and
is intended to illustrate the invention and its preferred
embodiments. Through routine experimentation, the artisan will
recognize apparent modifications and variations that may be made
without departing from the spirit of the invention.
* * * * *