Note: Descriptions are shown in the official language in which they were submitted.
~ ~376r~3
Ba~kground of the Invention
Polyester fi~ers have been produced in the past under a
variety of melt spiilning conditions. Both high stress and low
stress spinning processes have been employed. Under high stress
conditions the as-spun filamentary material is withdrawn from
the spinneret under conditions whereby substantial orientation
is imparted to the same soon after it is extruded and prior to
its complete solidification. See, for instance, United States
Patent Nos. 2,604,667 and 2,604,6~g. Such high stress cond:itions
of the prior art commonly yield a non-uniform filamentary material
having an internal structure wherein substantial radial non-
homogeneity exists across the iber diameter leading to self-
crimping characteristics upon heating, or less than desired
tensile properties.
Polyester spinning processes have also been proposed wherein
the cooling of the extruded filamentary material has been retarded
(i.e., prolonged) prior to complete solidification so as to alter
the properties thereof. See, for instance, United States Patent
Nos. 2,323,383; 3,053,611, and 3,361,859.
Heretofore, polyester fibers following extrusion and soli-
dification commonly have been drawn while at an elevated tempera-
ture to further enhance their tensile properties. Such drawing
may be conducted in an in-line fashion following fiber formation
or after the as-spun fiber is unwound from an intermediate collec-
tion device. Such drawing is commonly conducted upon contact with
an appropriate heating device~ heated gaseous atmosphere, or
heated liquid medium. Also, it has been known that previously
drawn polyester fibers may be heat treated with or without allowed
shrinkage (i.e., post-annealed) in order to modify their physical
properties.
-2-
.(;11;3~76ri'3
~ s-spun polyester filamentary material consisting princi-
pally of polyethylene terephthalate, because of its extremely slow
crystallization rate at room temperature, forms a stable fiber
package unlike an as-spun polyamide filamentary material. As-
spun polyamide filamentary materials have a marked tendency to
rapidly crystallize at room temperature with an accompanying
growth in fiber length thereby rendering wound fiber packages of
the same highly unstable and difficult to handle. See, for
instance, United States Patent No. 3,291,880 which discloses a
process for treating an as-spun polyamide yarn with steam so as
to render it capable of forming a stable fiber package. A com-
parable treatment of an as-spun polyester filamentary material
has been completely omitted, since the need for such intermediate
processing is absent. Also a polyamide filamentary material
commonly is taken up following melt extrusion and solidification
at a lower stress for a given take-up speed than a polyester
filamentary material formed using the same equipment because of
the varying extensional viscosities of the polymeric materials.
While the prior art has been capable of producing polyester
filaments suitable for use in commercial applications, no poly-
ester filament is known to have been heretofore produced havingthe internal structure and resulting property balance of the
polyester filament which forms the subject matter of the present
invention.
It is an object of the present invention to provide an
improved polyester filament possessing a unique microstructure.
It is an object of the present invention to provide an
improved polyester filament suitable for use in commercial
applications.
It is another object of the present invention to provide
an improved polyester filament exhibiting a bal~nce of properties
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,
-
~L~376~73
heretofore never achieved in prior polyester filaments.
These and other objects, as well as the scope, nature and utiliza-
tion of the invention, will be apparent to those skilled in the art from the
following description and appended claims.
Summary of the Invention
It has been found that an improved polyester filament suitable for
use in commercial applications comprises at least 85 mol per cent of poly-
ethylene terephthalate, has an interconnected highly oriented crystalline
microstructure coextensive with the length of the filament coexisting with
an interdispersed substantially disoriented non-crystalline phase, and
exhibits a propensity to undergo a low degree of shrinkage with a high degree
of force at an elevated temperature as evidenced by a modulus ratio of at
least 0.1.
It has been ound that an improved polyester filament suitable for
use :in commercial applications comprises at least 85 mol per cent of poly-
: ethylene terephthalate, has an interconnected highly oriented crystalline
microstructure coextensive with the length of the filament coexisting with
an interdispersed substantially disoriented non-crystalline phase, a mean
initial modulus when present in a multifilament yarn at 25C. of at least 55
grams per denier, a birefringence of about 0.10 to 0.14, a crystalline
orientation function of at least 0.88, and an amorphous orientation function
of not more than 0.35.
According to another embodiment of the present invention it has
been found that an improved polyester filament as defined above has a denier
of about 1 to 15.
In particular according to an embodiment of the present invention
there is provided an improved polye*hylene terephthalate filament of about 1
to 15 denier suitable for use in commercial applications having an inter-
connected highly oriented crystalline microstructure coextensive with the
length of said filament coexisting with an interdispersed substantially
disoriented non-crystalline phase, said filament exhibiting a propensity to
undergo a low degree of shrinkage with a high degree of force at an elevated
.~ ~ -4-
1376~73
temperature as evidenced by a modulus ratio of about 0.1 to 0.2, and exhibit-
ing when present in a multifilament yarn at 25C. a mean tenacity of at least
3.75 grams per denier, a mean initial modulus of at least 75 grams per denier,
a mean elongation of less than 50 percent, a mean longitudinal yarn shrink-
age at 100C. of less than 3.8 percent, and a mean longitudinal yarn shrink-
age at 175C. of less than 7.6 percent.
Description of the Drawing
The drawing is a schematic presentation of an apparatus arrangement
capable of forming the Lmproved polyester filament of the present invention.
, - 4a-
,~.. ~
1~376r~3
Descri~tion of Preferred Embodiments
The polyester filament of the present invention princi-
pally is composed of polyethylene terephthalate, and contains
at least 85 mol percent of polyethylene terephthalate, and pre-
ferably at least 90 mol percent polyethylene terephthalate. In
a particularly preferred embodiment of the process the polyester
filament is substantially all polyethylene terephthalate. Alter-
natively, during the preparation of the polyester minor amounts
of one or more ester-forming ingredients other than ethylene
glycol and terephthalic acid or its derivatives may be copoly-
merized. For instance, the melt-spinnable polyester may contain
85 to lO0 mol percent (preferably 90 to lO0 mol percent) poly-
ethylene terephthalate structural units and 0 to 15 mol percent
~preferably ~ to lO mol percent) copolymerized ester units other
than polyethylene terephthalate. Illustrative examples of other
ester-forming ingredients which may be copolymerized with the
polyethylene terephthalate units include glycols such as diethy-
lene glycol, tetramethylene glycol, hexamethylene glycol, etc.,
and dicarboxylic acids such as hexahydroterephthalic acid,
bibenzoic acid, adipic acid, sebacid acid, azelaic acid, etc.
The improved polyester filaments of the present invention
are suitable for use in textile or other commercial applications,
may be woven or knitted to form fabrics, and commonly possess
a denier per filament of about 1 to 15, e.g., about l to lO or
1.5 to 5. The polyester filaments conveniently may be provided
in the form of continuous multifilament yarns. For instance,
continuous multifilament yarns of about 6 to 200 filaments may
be provided, e.g., yarns of about 20 to 36 continuous filaments.
The improved polyester filaments of the present invention
possess a unique internal structure. A polyester filament in
--5--
.
,......
~-
~ .~376r~3
accordance with the present invention possesses an interconnected
highly oriented crystalline microstructure coextensive with its
length. The high degree of orientation of the crystalline
regions of the ilaments may be determined by standard wide
angle x-ray diffraction analysis. The region of the fiber
between the interconnected highly oriented crystalline micro-
structure is composed of non-crystalline (amorphous) polymeric
chains or chain segments in a substantially relaxed low orienta-
tion form as is evident by the low shrinkage and the low amor
phous orientation function exhibited by this structure at
elevated temperature. The relationship between low shrinkage
and low amorphous orientation is documented in the open litera-
ture. Seel for example, the article by Robert J. Samuels in
J. Polymer Science, A2, 10,781 ~1972). The interconnections
are generally non-crystalline in nature and serve the function
of further binding the polymeric highly crystalline regions
into a unitary microstructure. The presence of interconnections
may be deduced from the level of the mechanical and thermo-
merchanical properties exhibited by the filaments.
The internal structure possessed by the improved poly-
ester filaments of the present invention further manifests itself
in a balance of properties heretofore unattained in a polyester
filament. Discussed in detail below are various properties
exhibited by these filaments. The tensile and thermomechanical
properties reported taken individually have heretofore been
exhibited by polyester filaments of the prior art. However,
no polyester filament has been provided in the past having the
highly satisfactory tensile properties reported in combination
with the thermomechanical properties repc.rted. More spe~ifically,
the microstructure of the polyester filaments of the present
1~376~3
invention renders the same capable of undergoing only a limited
degree of shrinkage at an elevated temperature which occurs
under a high degree of force. This property balance of the
filament is summarized in its "modulus ratiol' as defined here-
after. The property balance exhibited renders the polyester
filaments of the present invention particularly suited for use
in general textile or other commercial applications.
As indicated below, many of the tests whereby the poly-
ester filaments are characterized may be conveniently conducted
by the testing of continuous multifilament yarns consisting of
the polyester filaments. The number of filaments present in
the yarn undergoing testing may be varied, and my conveniently
range from about 10 to 30, e.g., 20. The filaments pre'sent in
the yarn during testing are untwisted. It will be appreciated
by those skilled in the art that particularly in the area of
tenacity and initial modulus measurement that slightly higher
mean values are produced if single filament testing is substi-
tuted for multifilament yarn testing.
The polyester filaments of the present invention commonly
exhibit when present in a multifilament yarn at room temperature,
i.e., 25C., the mean tensile properties indicated below:
Particularly
Pre~erred Preferred
Embodiment Embodiment
Tenacity at least 3.25 grams at least 3.75 grams
per denier per denier
Initial Modulus at least 55 grams at least 75 grams
per denier per denier
Elongation less than 75 percent less than 50 percent
The tensile properties may be determined through the utilization
of an InstronTM tensile tester (Model TM) using a 3-1/3 inch
gauge length and a strain rate of 60 percent per minute in
~037~3
accordance with ASTM D2256. The yarn prior to testing is
conditioned for 48 hours at 70F. and 65 percent relative
hymidity in accordance with ASTM D1776. It will be noted
that the tenacity and initial modulus values are comparable
to those encountered in commercial polyester filaments of
the prior art.
The polyester filaments of the present invention exhibit
highly desirable thermomechanical properties at elevated tem-
peratures which result in improved dimensional stability.
When present in a multifilament yarn in air, the filaments
shrink less than 5 percent at 100C. (preferably less than 3.8
percent), and less than 8 percent at 175C. (preferably less
than 7.6 percent). The above shrinkage values'may be determined
through the utilization of a duPont Thermomechanical Analyzer
(~Model 941) operated under zero applied load and at 10C./min.
heating rate with the gauge length held constant at 0.5 inch.
- Additionally the polyester filaments of the present
invention exhibit an unusually high internal tension or shrinkage
force when present at an elevated temperature. When present in
a multifilament yarn at 100C., the filaments exhibit a mean
internal tension of about 0.3 to 0.5 grams per denier. Commonly
a maximum internal tension of about 0.4 grams per denier is
observed. The above internal tension values may be determined
through the utilization of an InstronTM tensile tester fitted
with a programmed fast response oven. A yarn sample is clamped
into the jaws of the tester and heated in air at 10C./min.
while being held at a constant length. While the test is not
gauge length sensitive, a gauge length of about 6 inches con-
veniently may be selected. The force generated by the yarn
~0 while being heated is monitored as a function of the yarn
-8- ,
~37673
temperature on a suitable recording device. The force at a
given temperature divided by the yarn denier is defined as
the internal tension at that temperature. The internal ten-
sion is a measurement of the stress introduced into the yarn
during processing and as such reflects the stability of the
molecular chain conformations present in that structure,
especially of the interconnections and other species present
in the non-crystalline regions.
The thermomechanical properties of the polyester fila-
ments of the present invention may be summarized through the
computation of the "shrinkage modulus" parameter which is
defined as the mean internal tension at a given temperature
when present in a multifilament yarn divided by the mean per-
cent shrinkage at that temperature when present in a multifila-
ment yarn times 100. The polvester filaments of the present
invention when present in a multifilament yarn ~ommonly exhibit
a shrinkage modulus of at least about 9.0 grams per denier at
100C., and a shrinkage modulus of at least about 3.5 grams
per denier at 175C. Such values are higher than those encoun-
tered in the prior art. The shrinkage modulus as here defined
reflects the tautness of those molecular chains serving as
interconnections between crystalline regions as compared to
the overall orientation of the non-crystalline molecular chains.
A high shrinkage modulus implies taut, efficient interconnec-
tions co-existing with a generally relaxed non-crystalline
phase.
The unique balance of tensile properties and thermo-
mechanical properties of the filaments of the present invention
lS evidenced through the computation of the ~modulus ratio" for
the filaments which is defined as the shrinkage modulus of the
filaments at 100C. when present in a multifilament yarn divided
_g_
~ ~376~3
by the mean initial modulus of the filaments when present in
a multifilament yarn at room temperature (i.e., 25C.). The
pol~Jester filaments of the present invention exhibit a modulus
ratio of at least 0.1, e.g., about 0.1 to 0.2. Polyester
filaments of the prior art exhibit a substantially lower modu-
lus ratio. The modulus ratio reflects the relative load-
bearing efficiency of the fiber structure at elevated tempera-
tures as compared to room temperature.
The polyester filaments of the present invention also
commonly exhibit a mean birefringence of about 0.10 to 0.14
(e.g., about 0.11 to 0.14), which is a range not commonly
exhibited by commercial polyester fibers. The bire~ringence
of the filaments can be determined by using a Berek compensator
; mounted in a polarizing light microscope, and expresses the
difference in the refractive index parallel and perpendicular
to the fiber axis.
The improved polyester filament of the present invention
may also be characterized without specific reference to its
thermomechanical properties. Such filaments exhibit a rela-
tively high initial modulus, coupled with a relatively highcrystalline orientation function, and a relatively low amorphous
orientation function. For instance, the polyester filament
may exhibit a mean initial modulus when present in a multifila-
ment yarn at 25C. of at least 55 grams per denier, a bire-
frin~ence of about 0.10 to 0.14, a crystalline orientation
function (fc) of at least 0.88 (e.g., about 0.88 to 0.95), and
an amorphous orientation function (fa) of not more than 0.35
(e.g., about 0.15 to 0.35).
As will be apparent to those skilled in the art, the
birefringence of the filament is a function of the filament
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1~376 ~3
crystalline portion and the filament amorphous portion. See,
for instance, the article by Robert J. Samuels in J. Polymer
Science, _, 10, 781 (1972). The birefringence may be expressed
by the equation:
An = Xf ~nc + (l-X)faAna + ~nf (1)
where
~n = birefringence
X = fraction crystalline
fc = crystalline orientation parameter
~n = intrinsic birefringence of crystal
(0.220 for polyethylene terephthalate)
fa = amorphous orientation parameter
~n = intrinsic birefringence of amorphous
a ~0~275 for polyethylene terephthalate)
~nf = form birefringence
(values small enough to be neglected
in this system)
The fraction cr~stalline, X, may be determined by conventional
density measurements. The crystalline orientation parameter,
fc, may be calculated from the average orientation angle, e,
as determined by wide angle x-ray diffraction. Photographs of
the diffraction pattern may be analyzed for the average angular
breadth of the (010) and (100) diffraction arcs to obtain the
average orientation angle, e. The crystalline orientation
parameter, fc~ may be calculated from the following equation:
fc = 1/2 (3 COS2 e - 1) (2)
Once ~n, X, and fc are known, fa may be calculated from equa-
tion (1). ~nc and ~na are intrinsic properties of a given
chemical structure and will change somewhat as the chemical
constitution of the molecule is altered, i.e., by copolymeriza-
tion, etc.
.~. ,,
~ ~,
~ Q37~r~3
In our commonly assigned Canadian Serial No. 210,027
filed concurrently herewith, and entitled "Improved Process
for the Expeditious Formation and Structural Modification
of Polymeric Fibers and Films" is claimed a process capable
of yielding the improved polyester filaments of the present
invention.
The melt-spinnable polyester utilized in the process
preferably exhibits an intrinsic viscosity, i.e., an I.V., of
about 0.45 to 1.0, and an I.V. of about 0.6 to 0.95 in a
particularly preferred embodiment of the process. The I.V. of
the melt-spinnable polyester may be conveniently determined by
the equation ciOm lnnr , where ~r is the "relative viscosity"
obtai'ned by dividing the viscosity of a dilute solution of the
polymer by the viscosity of the solvent employed (measured at
the same temperature), and c is the polymer concentration in
th~ ~l~tion expressed in grams/100 ml. The fiber-forming
polyester additionally commonly exhibits a glass transition
temperature of about 75 to 80C., and a melting point of about
250 to 265C., e.g., about 260C.
The spinneret selected for use in the process may con-
; tain one or preferably a plurality of extrusion orifices. For
instance, a standard conical spinneret containing 1 to 200
holes (e.g., 6 to 200 holes), such as commonly used in the melt
spinning of polyethylene terephthalate, having a diameter of
about 10 to 60 mils (e.g., 10 to 40 mils) may be utilized in
the process. Yarns of about 20 to 36 continuous filaments are
commonly formed. The melt-spinnable polyester is supplied to
the spinneret at a temperature above its melting point.
The mol_en polyester is preferably at a temperature of
about 270 to 310C., and most preferably at a temperature of
about 285 to 305C. (e.g., 300C.) when extruded through the
spinneret.
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.~
~37~i ~3
Subsequent to extrusion through the spinneret the
resulting polyester material is passed in the direction of
its length through a solidification zone provided with a
gaseous atmosphere at a temperature below the glass transi-
tion temperature thereof, e.g., below 80C., wherein the
molten filamentary material is transformed to a solid fila-
mentary material. Within the solidification zone the molten
material passes from the melt to a semi-solid consistency,
and from the semi-solid consistency to a solid consistency.
While present in the solidification zone the material under-
goes substantial orient~tion while present as a semi-solid
as discussed hereafter. The solidification zone could also
be termed a "quench zone". The gaseous a'tmosphere present
within the solidification zone preferably circulates so as
to bring about more efficient heat transfer. In a preferred
embodiment of the process the gaseous atmosphere of the
solidification zone is provided at a temperature of about
10 to 40C., and most preferably at about room temperature
(e.g., at about 25C.~. The chemical composition of the
gaseous atmosphere is not critical to the operation of the
process provided the gaseous atmosphere is not unduly reactive
with the polyester filamentaxy material. In a particularly
preferred embodiment of the process the gaseous atmosphere
of the solidification zone is air. Other representative
gaseous atmospheres which may be selected for utilization in
the solifification zone include inert gases such as helium,
argon, nitrogen, etc.
The gaseous atmosphere of the solidification zone prefer-
ably impinges upon the extruded polyester material so as to
produce a uniform quench wherein no substantial radial non-
homogeneity exists across the fiber diameter. The uniformity
-13-
'~
lQ37673
of the quench may be demonstrated through the ability of the
resulting filamentary material to exhibit no substantial
tendency to undergo self-crimping upon the application of
heat. A flat yarn accordingly preferably is produced.
The solidification zone is preferab:Ly disposed immedi-
ately below the spinneret and the extruded polyester material
is present while axially suspended therein for a residence
time of about 0.0008 to 0.4 second, and most preferably for
a residence time of about 0.033 to 0.14 second. Commonly
the solidification zone possesses a length of about 0.25 to
20 feet, and preferably a length of 1 to 7 feet. The gaseous
atmosphere is also preferably introduced at the lower end of
the solidification zone and withdrawn along the side thereof
with the moving continuous length of polyester material passing
downwardly therethrough from the spinneret. A center flow
; quench or any other technique capable of bringing about the
desired quenching alternatively may be utilized. If desired,
a hot shroud may be positioned intermediate the spinneret and
the solidification zone.
The resulting filamentary material is next passed in
the direction of its length through a conditioning zone provided
with a gaseous atmosphere at a temperature above the glass
transition temperature thereof and below the melting temperature
thereof, i.e., commonly at about 90 to 180C. ~e.g., 90 to 140C.3
for a residence time of about 0.0001 to 0.8 second wherein sub-
stantial crystallization of the previously solidifled filamentary
material takes place. The conditioning zone preferably is pro-
vided with a gaseous atmosphere at a temperature of about 110
to 120C. and ~he moving filamentary material axially suspended
therein. The preferred residence time for the filamentary
material within the conditioning zone is about 0.0016 to 0.6
~(1 376~;~3
second, and most preferably about 0.03 to 0.09 second. If
residence times much below about 0.0001 second are employed,
then a stable achievement of the desired property levels does
not result. Longer residence times may be utilized with no
commensurate advantage.
The chemical composition of the gaseous atmosphere
provided within the conditioning zone is not critical to the
operation of the process provided the gaseous atmosphere is
not unduly reactive with the polyester filamentary material.
Static air or steam conveniently may be selected. Other re-
presentative gaseous atmospheres which may be employed in the
conditioning zone include inert gases such as helium, argon,
nitrogen, etc. Band heaters or any other heating means may
be provided so as to maintain the conditioning zone at the
re~uired temperature. The conditioning zone commonly has a
length of abour 0.5 to 30 feet, and preferably a length of
about 5 to 12 feet.
The resulting filamentary material is withdrawn from
the conditioning zone at a rate of about 1000 to 6000 meters
20 per minute tpreferably 2500 to 3500 meters per minute) while
under a stress of about 0.15 to 0.6 gram per denier (prefer-
ably 0.2 to 0.4 gram per denier). Following extrusion the
filamentary material is maintained under constant tension and
throughout the process no stress isolation is utilized along
the length of the filamentary material intermediate the spin-
neret and the point of withdrawal from the conditioning zone
(i.e., the yarn is axially suspended in the absence of external
contact in the region intermediate the spinneret and the point
of withdrawal fr~m the conditioning zone). When withdrawn from
the conditioning zone the filamentary material commonly exhibits
-15-
1~1376r~3
a denier per filament of about 1 to 10, e.g., about 1.5 to 5.
The improved polyester formation process may be con-
veniently carried out in conventional nylon equipment provid-
ed with a heated conditioning chamber of adequate length be-
low the quench zone and having the required high stress take-up
equipment. The results achieved with the polyesters described
; herein are considered to be unexpected to those skilled in
; polyester fiber technology.
The passage of the filamentary material through the
conditioning zone in the precise manner as described surpris-
ingly has been found to beneficially enhance the same through
the modification of its internal structural morphology. More
specifically, the tensile properties of the Eilamentary mater-
ial are surprisingly improved thereby rendering a conventional
hot drawing step unnecessary. The tensile strength and modu-
lus of the filamentary material are improved and its shrinkage
characteristics are diminished.
While present in the conditioning zone, the filamentary
material is heat-treated under constant tension. Duri.ng this
heat treatment, small amounts of thermally induced elongation
may occur, but this process is differentiated from a draw pro-
cess because of the constant tension rather than the constant
strain criteria. The level of tension on the filamentary ma- ,
terial in the conditioning zone is extremely critical to the
development of the desired structure and properties and prima-
rily is influenced by the rate of withdrawal from the condition-
ing zone rather than friction with the surrounding gas. No
stress isolation results along the filamentary material inter-
mediate the spinneret and the point of withdrawal from the
3G c~nditioning zone (i.e., the filamentary material is axlally
-16-
~ 1 ~376r~3
suspended in the absence of external stress isolating de-
vices in the region intermediate the spinneret and the point
of withdrawal from the conditioning zone). Should one omit
the passage of the filamentary material through the conition-
ing zone, the denier and cross-sectional dimension of the
; filamentary material commonly are found to be identical.
- In the high stress melt spinning operation as described
the extruded filamentary material intermediate the point of
its maximum die swell area and its point of withdrawal from
the conditioning zone commonly exibits a drawdown ratio of
about 100:1 to 2000:1, and most commonly a drawdown ratio of
about 600:1 to 1700:1. The "drawdown ratio" as used above is
def;ined as the ratio of the maximum die swell cross-sect:ional
area to the cross-sectional area of the filamentary material
- as it leaves the conditioning zone. Such substantial change
in cross-sectional area occurs almost exclusively in the solidi-
fication zone prior to complete quenching. In some empodi-
ments of the process, however, up to about a 4:1 reduction in
cross sectional area of the filamentary material is observed
in the conditioning zone via heat induced elongation as dis-
cussed above.
The theory whereby the present process is capable of
producing polyester filamentary material exhibiting the pro-
perties recited is considered complex and incapable of simple
explanation. It is believed, however, that the stress exerted
upon the semi-solid filamentary material in the solidification
zone produces an oriented crystalline fibrillar microstructure
of polyester molecules within each fiber which serve to nucleate
the epitaxial growth of polymer crystals intermediate adjoin-
ing fibrils.
-17-
~37~t73
As the resulting filamentary material next passes through the
conditioning zone, as defined, substantial epitaxial crystal-
lization spontaneously occurs onto the oriented fibrillar
structure. Such rapid crystallization forms a lamella over-
growth on the existing fibrillar structure with lamellar
crystals extending between fibrils and with the lamellar
; crystals being joined by tie molecules.
The resulting filamentary material is amenable to
further processing through the use of additional processing
equipment or it may be used directly in applications re-
quiring a continuous filament textile yarn. If desired the~ilamentary material subsequently may be converted f~om a
flat yarn to a textured yarn, e.g., through the utilization
of known false twist texturing conditions. Illustrative con-
ditions for a yarn of 150 denier employ a yarn speed of 125
meters per minute, a feed roll heater plate temperature of
215C., an over feed into the heater of about 3.5 percent,
and a turn per inch of about 60.
The following examples are given as specific illustra-
tions of the invention. It should be understood, however,
that the invention is not limited to the specific details
set forth in the examples. Reference is made in the examples
to the apparatus arrangement illustrated in the drawing. The
claimed invention is not restricted to the utilization of
the apparatus illustrated in the drawing. In each example
the polyester was polyethylene terephthalate having an in-
trinsic viscosity ~I.V.) of 0.67. The intrisic viscosity
was determined from a solution of 0.1 gram of polymer in
100 ml. of ortho-chlorophenol at 25C. Th~ characterizatlon
of the polyester filament formed in each example is presented
in Table I, Table II and Table III which follow all of the
examples.
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,~ '~' ,.
JC~376~73
EXAMPLE 1
The polyethylene terephthalate polymer while in particu-
late form was placed in hopper 1 and was advanced toward spin-
neret 2 by the aid of screw conveyor 4. Heater 6 ca~sed the
polyethylene terephthalate particles to melt to form a homo-
; geneous phase which was further advanced toward spinneret 2 by
the aid of pump 8.
The spinneret 2 had a standard conical entrance andpossessed a ring of 20 extrusion holes, each having a diameter
or 20 mils. The molten polyethylene terephthalate was at a
; temperature of about 300 C. when extruded through spinneret 2.
The resulting extruded polyethylene terephthatlate 10
passes directly from the spinneret 2 through solidification
`~ zone 12. The solidification zone 12 had a length of 6 feet
and was vertically disposed. Air at room temperature(i.e.,
about 25C.) was continuously introduced into solidification
zone 12 at 14 which was supplied via conduit 16 and fan 18.
The air was continuously withdrawn through elongated conduit 20
vertically disposed in communication with the wall of solidi-
fication zone 12, and was continuously withdrawn through con-
duit 22. While passing tllrough the solidification zone the
ex~ruded polyethylene terephthalate was transformed into a con-
tinuous length of as-spun polyethylene terephthalate yarn.
The polymeric material was first transformed from a molten
to a semi-solid consistency, and then from a semi-solid con-
sistency to a solid consistency while passing through solidi-
fication zone 12. The extruded polyethylene terephthalate
was present in the ;solidification zone 12 for a residence time
of about 0 045 second.
Upon being withdrawn from solidification zone 12 the
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10376~3
continuous length of polyethylene terephthalate yarn 24 next
immediately was passed through vertically disposed condition-
ing zone 26 having a length of12 feet. A static air atmosphere
was maintained ~n conditioning zone 26 at a temperature of
120C. by the aid of band heater 28which surrounded the walls
of the same. me polyethylene terephthalate yarn was present in
the conditioning zone 26for a residence time of about 0.09
second where it was structurally modified.
The resulting polyethylene terephthalate yarn was under
a constant tension following extrusion and waswithdrawn from con-
ditioning zone26 at a rate of 2500 meters per minute while under
a stress of about 0.2 gram per denier. The extruded fila~entary
material intermediate the point of its maximum die swell area and
its point of withdrawal from the conditioning zone was drawn down
at a ratio of about 1400:1. The resùlting polyethylene terephthalate
yarn exhibited a denier per filament of 2, and was packaged at
30 after passing around godets 32 and 34, and contacting roller 36
which applied an anti-static lubricant.
The polyethylene terephthalate yarn was axially suspended
in t~e absence of external contact intermediate the spinneret and
the point of its withdrawal from condition zone26. There was accord-
ingly no stress isolation along the length of the same in this re-
gion and the fibrous material was under substantial stress through
its processing which was exerted by rotation of packaging equipment 30.
GOMPARATIVE EXAMPLE 2
For comparative purposes, Example 1 was repeated with
the exception that the static air atmosphere of conditioning
zone 26 was provided at room temperature (i.e., about 25C.)
instead of 120C. The extruded filamentary material inter-
mediate the point of its maximum die swell area and its point
-20-
~.. ;.~
~ 037~q3
of withdrawal from the conditioning zone was drawn down at
; a ratio of about 1400:1.
EXAMPLE 3
Example 1 was repeated with the exception that the
resulting polyethylene terephthalate yarn was withdrawn from
conditioning zone 26 at a rate of 3000 meters per minute
while under a stress of about 0.25 gram per denier. The ex-
truded polyethylene terephthalate yarn was present in the
so~idification zone 12 for a residence time of about 0.036
second. The polyethylene terephthalate yarn was present in
the conditioning zone 26 for a residence time of about 0.07
second. The extruded filamentary material intermediate the
point of its maximum die swell area and its point of with-
drawal from the conditioning zone was drawn down at a ratio
of about 1500:1.
COMPARATIVE EXAMPLE 4
For comparative purposes, Example 3 was repeated with
the exception that the static air atmosphere of the condition-
ing zone 26 was provided at room temperature (i.e., about 25C.)
instead of 120C. The extruded filamentary material inter-
mediate the point of its maximum die swell area and its point
of its maximum die swell area and its point of withdrawal from
the conditioning zone was drawn down at a ratio of about 1500:1.
COMPARATIVE EXAMPLE 5
For comparative purposes, Example 1 was repeated with
the exception that: The spinneret was provided with a ring of
36 extrusion holes each having a diameter of 20 mils, the con-
ditioning zone was provided at room temperature (i.e., at about
25C.) and the yarn was withdrawn from the conditioning zone
at a rate of 650 meters per minute while under a stress of about
0.018 grams per denier.
-21-
1~37~q3
COMPARATIVE EXAMPLE 6
For comparative purposes, Example 1 was repeated
with the exception that: The spinneret was provided with a
ring of 36 extrusion holes each having a diameter of 20
mils, the conditioning zone was provided at room temperature
(i.e., at about 25C.), and the yarn was withdrawn from the
conditioning zone at a rate of 1100 meters per minute while
under a stress of 0.038 grams per denier.
COMPARATIVE EXAMPLE 7
For comparative purposes, Example 1 was repeated with
the exception that: The spinneret was provided with a ring
of 36 extrusion holes each having a diameter of 20 mils, the
conditioning zone was provided at room temperature (i.e., at
about 25C.), and the yarn was withdrawn from the condition-
ing zone at a rate of 4000 meters per minute while under a
stress of about 0.15 grams per denier.
COMPARATIVE EXAMPLE 8
For comparative purposes, Example 1 was repeated with
the exception that the spinneret was provided with a ring of
36 extrusion holes each having a diameter of 20 mils and the
as-spun yarn was collected on a bobbin after-being withdrawn
from the solidification zone at a rate of 2500 meters per
minute while under a stress of about 0.2 grams per denier
without passage through the conditioning zone. The yarn was
unwound from the bobbin and passed through the conditioning
zone maintained at 125C. while under a stress of about 0.2
grams per denier and taken up at a rate of 200 meters per
minute. The yarn was present in the conditioning zone for a
residence time of about 1 second. No drawing took place
while the yarn was present in the conditioning zone.
-22-
~)376~73
COMPARATIVE EXAMPLE 9
For comparative purposes, Example 3 was repeated withthe exception that the as-spun yarn was collected on a bobbin
after being withdrawn from the solidification zone at a rate
of 3000 meters per minute while under a stress of about 0.25
grams per denier without passage through the conditioning
zone. The yarn was unwound from the bobbin and passed through
the conditioning zone maintained at 120C. while under a
stress of about 0.25 grams per denier and taken up at a rate
of 200 meters per minute. The yarn was present in the con-
ditioning zone for a residence time of about 1 second. The
as-spun yarn was drawn at a draw ratio of about 2.6:1 while
present in the conditioning zone.
COMPARATIVE EXAMPLE 10
Comparative Example 5 was repeated with the exception
that the as-spun yarn was drawn 3.3 times its length by con-
tinuous passage over a 12 inch hot shoe maintained at 80C.
while present in an air atmosphere. The as-spun yarn was
supplied to the hot shoe at a rate of 50 meters per minute,
and was in contact with the surface of the hot shoe for about
0.1 second.
COMPARATIVE EXAMPLE 11
Comparative Example 6 was repeated with the exception
that the as-spun yarn was drawn 2.27 times its length by con-
tinuous passage over a 12 inch hot shoe maintained at 100C.
while present in an air atmosphere. The as-spun yarn was
supplied to the hot shoe at a rate of 50 meters per minute,
and was in contact with the surface of the hot shoe for about
C.l second.
-23-
lQ376r~3
COMPARATIVE EXAMPLE 12
For comparative purposes, Example 1 was repeated with
the exception that the spinneret was provided with a ring of
36 extrusion holes, each having a diameter of 20 mils and the
as-spun yarn was collected on a bobbin after being withdrawn
from the solidification zone at a rate of 1000 meters per
minute while under a stress of about 0.008 gram per denier
without passage through the conditioning zone. The yarn was
unwound from the bobbin and was hot drawn 5 times its length
by continuous passage over a 12 inch hot shoe maintained at
90C. while present in an air atmosphere. The yarn was supplied
to the hot shoe at a rate of 50 meters per minute, and was in '
contact with ~he surface of the hot shoe ~or 0.1 second.
COMPARATIVE EXAMPLE 13
Comparative Example 12 was repeated with the yarn pro-
duct of that example being relaxed 20 per cent by continuous
passage over a hot roll maintained at 120 C.
The characterization of the polyester filament formed
in Examples 1 through 13 is presented in Table 1, Table II,
and Table III which follow.
-24-
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Only Example Nos. 1 and 3 produced a polyester
filament in accordance with the present invention. In
comparative Examples 8 and 9 it is demonstrated that the
desired filament cannot be produced if one should attempt
to divide the presently claimed process by collection
of the filamentary material after it leaves the solidi-
fication zone, and by subsequent passage o~ the same
while under a comparable stress through the conditioning
zone provided at a comparable temperature. Additionally,
Comparative Examples 2, 4, 5 to 7, and 10 to 13 demon-
strate that the desired filament is not produced under
a variety of differing processing conditions.
Although the invention has been described with
preferred embodiments, it is to be understood that vari-
ations and modi~ications may be resorted to as will be
apparent to those skilled in the art. Such variations
and modifications are to be considered within the purview
and scope of the claims appended hereto.
-28-
~`J ~
