Note: Descriptions are shown in the official language in which they were submitted.
PROCESS ~OR FOR~G A CO~I~IJOUS FILAMEe~T YARN ~OM A M~T SPI~ABLE
5YN~l~TIC POLY~ A~ID ~OVhl, POLYES~E~ YAR~S PRODIJCED :~f ~ EIOCESS
This invention relates to a process for forming
continuous filament ya~ns from molten melt-spinnable synthetic
linear polymers9 such yarns not requiring to be dræ~n subsequent
to winding up after spinning. It also relates to novel polyester
yarns which may be produced by the process. It further relates
to polyamide yarns producea by the process.
Polymeric filamenta~y yarns have been produced under
~ wide variety of melt extrusion conditions.
~ ~ærman Patent O~S 2 117 659 there is describea a
melt e~trusion process co~prising extruding a polymeric melt
through a multiorifice spinneret to form a plurality of fil~ments,
passing the filaments through a transverse current of a cooling gas -
in order to solidify the filaments, passing the solidified
filaments through a heating zone and winding up the fil~ments. In
one embodiment of the process, the heating zone comprises an air-
filled heated shaft through which the solidified filaments are
passed.
In ~ritish Patent Specification ~o 1 487 843 there is
described a somewhat s;~;lar process for forming a polyester
filamentary material comprising extruding a melt-spinnable polyester
material through a shaped orifice, passing the resulting molten
filamentary material through a solidification zone consisting of a
gaseous atmosphere at a temperature below the glass transition
temperature of the material, passing the resulting solidified
filamentary material through a conditioning zone provided with a
gas-eous atmosphere at a temperature above its glass transition
temperature and below its melting temperature, and withdrawing the
resulting crystallised filamentary material from the conditioning
zone. The gaseous atmosphere used in the conditioning zone of the
process described in Specification No 1 487 843, may, amongst other
gases, be static air or steam
Also in ~ritish Patent Specification 1~o.1574305 there
i8 described another process for producing filamentary materi~1
~3 ' '~
1~L5;~Z73
based on either polyamides or polyesters comprising extruding
the molten polymeric material to form filaments, advancing
the molten filaments through a solidification zone, advancing
the solidified filaments through a tensioning zone without
inducing substantial drawing thereof within the zone, advancing
the solidified filaments through a treatment zone comprising a
fluid atmosphere heated to a temperature above the glass
transition temperature of the filaments and withdrawing the
filaments from the treatment zone at a velocity of from 1000
1Q metres/minute. ~h~ flllid is preferably air but may be nitrogen
or steam.
,:
A further process is described in ~ritish Patent
Specification No 1 478 787 in which immediately after being
quenched, a spun yarn composed of polyhexamethylene adipamide
(Nylon-6,6) is subjected to a steam atmosphere in an open tube
preferably supplied with steam. m e steam at atmospheric pressure
serves to provide the yarn with a positive dry thexmal shrinkage
between 90 and 140C.
We have now found that considerable advantages can
be achieved by passing a melt-spun filamentary yarn through a
conditioning zone comprising a steam atmosphere at pressures
much higher than those used previously.
Aocording to the invention, therefore, we provide a
process for forming a continuous filament yaxn from a melt-
spinnable synthetio linear polymer comprising extruding themolten polymer through a shaped orifice to form a lten
filamentary material, passing the molten filamentary material in
the direction of its length through a solidification zone
wherein the molten filamentary material is ~olidified, passing
the solidified filamentary material in the direotion of its
length bhrough a oonditioning zone provided with a gaseous
atmosphere at a temperature above the glass transition temperature
of the material and below its melting temperature, withdrawing
the resulting filamentary yarn from the conditioning zone and
~5 winding up such yarn, characterised in that the gaseous atmosphere
in the conditioning zone is compressed steam at an absolute
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pressure in excess of 136 kW/m and more preferably in
excess of 170 kN/m2.
~he term "yarn" as used herein means a monofilament
ya~n, a multifilament yarn or a multifilament staple tow.
~he process of the invention can be used to produce
filament yarns from any of the usual synthetic linear
polymers which can be melt-spun into individual filaments
such as polyesters, polyamides or polyolefines,in particular,
for example, polyethylene terephthalate and its copolyesters,
-10 polyepsilon - caproamide, polyhexamethylene adipamide, polypropy_
lene and t~e like. ~hese polymers may be spun into very fine
individual filaments which may then be combined, according to
- end use, into yarns or tows which may then be processed in
the usual way.
qlhe process is particularly suitable for producing
filamentary fibres from melt-spinnable polyesters based on
polyethylene terephthalate and oontaining at least 85 mol
percent ethylene terephthalate and preferably at least 90 mol
percent ethylene terephthalate. In a particularly preferred
20 embodiment of the process the melt-spinnable polyester is
substantially all polyethylene terephthalate. Alternatively
during preparation of the polyester, minor amounts of one or
more ester-forming ingredients other than ethylene glycol or
terephthalic acid or its derivatives may be copolymerised. For
25 instance, the melt spinnable polyester may contain 85 to 100
mol percent (preferably 90 to 100 mol percent) ethylene
terephthalate structural units and 0 to 15 mol percent (pre~erably
O to 10 mol percent) copolymerised esber units other than
ethylene terephthalate. Illustrative examples of other ester-
forming ingredients which may be copolymerised with ethylene
terephthalate units include glycols such as diethylene glycol,
tetramethylene glycol, hexamethylene glycol, and dicarborylic
acids Puch as hexahydro terephthalic acid, diben~oic acid9
adipic acid, sebacic acid, acelaic acid.
~he melt-spinnable polyethylene terephthalate selected
_ 4 1~ 5~ 27 3
for use in the process preferably exhibits an intrinsic viscosity,
i.e. IV, of 0.45 to 1.0 dl/gm, and more preferably an IV of between
0.60 and 0.95 dl/gm. The IV of the melt spinnable polyester may
be conveniently determined by the formula:
IV - limit ln~
C
as C approaches zero,
where ~r is the "relative viscosity~ obtained by dividing the
viscosity of a dilute solution of thepolymer by the viscosity
of the solvent employed (measured at the same temperature) and C
is the polymer conce~tration in the solution expressed in grams/
100 ml.
The polyethylene terephthalate additionally commonly
exhibits a glass transition temperature of 75-80C and a meltlng
. point of 250 to 265C e.~g. about 260C.
The extrusion orifice may be selected from those
spinnerets commonly used to extrude fibres. The spinneret wlll
be provided with a plurality of extrusion orifices - in the case
of a filament yarn up to about 40 orifices will be used and in
the case of a tow, several thousand orifices will be used.
For instance, a standard spinneret containing a
multiplicity of orlfices, such as commonly used in the melt
spinning of polyethylene terephthalate, each orifice having a
diameter of 125-500 ~um may be utilised in the process. The
:" orifices may be circular or non-circular in cross-section.
The polyester material is supplied to the extrusion
orifice at a temperature above its melting point, more preferably
at a temperature of 270 to 310C and most preferably at a
temperature o~ 285 to 305C.
:~ Subsequent to extrusion through the shaped orifice the
resulting molten filamentary material is passed in the dlrection
of its length through a solidi~ication zone, often referred to
as a "quench" zone, provided with a gaseous atmosphere at a
temperature below the glass transition temperature thereof
?5 wherein the molten filamentary material is converted into a
solid filamentary material. Within the solidification zone the
;r ~ .
,
1152Z~3
molten material passes from the molten to a semi-solid
consistency and then from a semi-solid consiætency to a
solid consistency. While present as a semi-solid
the filamentary material undergoes substantial orientation.
Preferably the gaseous atmosphere of the solidification zone
is provided at a temperature of 10 to 40 C and most
preferably at ambient temperature. ~he chemical composition
of the gaseous atmosphere is not critical provided it iæ
not unduly reactive with the polyester material. In practice
air is usually used.
The gaseous atmosphere in the solidification zone
preferably impinges upon the molten filamentar~ material so as
to provide a uniform quench so that no substantial radial
non-homogenity exists in the solidified product.
~he solidification zone is preferably disposed
immediately below the shaped extrusion orifice. If desired,
however, a hot shroud may be positioned intermediate the
shaped orifice and the solidification zone.
It is preferred that the extruded filamentary material
resides in the solidification zone, while axially suspended
therein, for a period of between 10 and 250 milliseconds and
m~re preferably between 30 and 150 milliseconds. Commonly
the solidification zone has a length of between 0.5 metre and 4
metres and preferably a length of between 1 and 3 metres.
~he solidified filamenta~y material is converged into
a yarn which is passed in the direction of its length through
a oonditioning tube containing an atmosphere of compre~ed
eteam having~ preferably~ an ab~olute pre~sure of be~ween 239
and 1548 k~/m2 and more preferably between 446 and 1176 kN/m2.
A suitable conditioning tube consists of a metal tube
fitted with valves at each end. ~he valves, when open~ permit
the yarn to be fed through the tube. ~he valves, when closed,
still allow free movement of the yarn. Inevitably, however,
there is a continuous, but small, loss of steam from the
conditioning tube.
.
~15Z273
The tube i5 fitted with appropriate means for
facilitating stea~pressure control at the required levels.
~ he tube may be lagged. Preferably, however, it
is provided with an insulation jacket into which is fed steam
from the same source of supply as that used in the conditioning
tube ~tself.
Preferably the tube is of circular section and has
a length in the range 10 cm to 1.5 metres and an internal
diameter in the range 3 mm to 40 mm.
The yarn is withdrawn from the conditioning zone at
~ a velocity in excess of 3000 metres/min and more preferably
in excesC of 3500 metres/min and is finally wound-up on a
suitable rotating bobbin winder, optionally after the
application of a suitable spin finish to the yarn.
Under the influence of the hot pressurised steam
within the conditioning zone and the tension applied to the
yarn by winding it up at a high wind-up speea, crystallisation
and orientation of the filaments within the yarn occurs, a
process which can be compared with a drawing process commonly
carried out on the yarn as a post wind-up stage in the processing
of yarn. ~hus in the process of the invention the filament
yarn is drawn while it is in, and immediately after leaving,
the conditioning zone so that there is a difference in speed
and thickness of the filaments before and after the conditioning
zone.
The distance of the conditioning zone from the spinneret
oan be selected within wide limits depending on the polymerio
material. When the polymerio material is polyethylene
terephthalate then we have found th~t an optimum distance between
the outlet of the spinneret and the commencement of the
oonditioning zone may be seleoted in the range 0.5 to 4.0 metres.
Furthermore the length of the oonditioning zone will
depend on the temperature of the steam atmosphere within the
oonditioning zone. However the length of the oonditioning zone
must in an~ case be such that the desired crystallisation and
orientation of the filament yarn can be achieved.
~152273
Using the process of the invention for processing a
polyester the following advantages are achievea.
1. Rapid and uniform heating of the filaments occurs
due to very good heat transfer and becau~e of this the
filaments can be converged and treated in the conditioning
zone as a yarn or tow so reducing filament to filament
variability.
2. ~ecause a considerable number of filaments are heated
at the same time at a uniform temperature we ensure that there
is more uniformity of properties between spinning positions
in addition to the increased uniformity between filaments within
a yarn gained by treating the filaments as a yarn instead
of individually.
.. .
A further advantage, however, is that the process
allows the production of novel fibres based on polyethylene
terephthalate.
According, therefore, to a further aspect of the
invention we provide a continuous filament yarn formed from a
melt spinnable polyethylene terephthalate characterised in that
the filaments have a birefringence ( ~ n) greater than Os105
and 5/0 modulus greater than 290 centi ~ewtons/tex and an initial
modulus (IM) defined by the function:
IM >, 260 cosh ~ ~ n
~irefringence, as will be known to those skilled in
the art, is a function of the orientation of a filamentary fibre
and expressed as the difference in the refractive index of a
filamentary fibre parallel to and perpendicular to its axis.
~ irefringence is measured using a polarisln~ microscope
and a ~erek compensator as de~cribed for example by R C Faust
in "Physical Methods of Investigating Textiles't, Edited by
R Meredith and J W S ~earle and published by ~extile ~ook
Publishers Inc.
Modulus is defined as the ratio of load to extension.
However~ for polymers, since the load-extension curve is not a
straight line the modulus must be referred to in relation to a
~1~2273
portion of the curve. Modulus may be measured on an Instron
testing machine.
Tn;tial Modulus is defined as the maximum slope of
the load-extension curve within the region 0-2~ extension.
~he ~/o Modulus is the slope of the line joining the
origon of the load-extension curve to the point on the curve
corresponding to a 5/0 extension.
~oth modulii are measures of the resistance of
the filamentary material under test to extension and bending.
A long-period spacing (IPS) of less than 200 ~ is
a characteristic of most and probably all of the filament
yarns of the invention produced from polyethylene terephthalate.
The long-period spacing is obtained from small angle
-=~Y~ Ga~eriII~ patterns made by known photographic proce~ures.
x-radiation of wavelength 1.54 ~ is passed through a parallel
bundle of filaments mounted in a Kratky low-a~gle camera in a
direction perpendicular to the filament axis and the diffraction
pattern is recorded on photographic film mounted 29~5 cm from
the filaments. Discrete meridional scattering is obtained at
angles of less than about 1. ~he intensity pattern is de~
smeared by known mathematical procedures, and from a knowledge
of the geomet~y of the apparatus and the measured diffraction
~ygles~ the long period spacing is calculated as described~
for example, in the book "X-ray Diffraction Methods in Polymer
Science" by ~ E Alexander, published by J Wiley and Sons,
~ew York (1969).
~he process of the invention, as stated previously,
is also eminen-tly suited to the processing of filament yarn of
polyhexamethylene adip~mide (~ylon-6~6) and polyepsilon-
~0 caproa~ide (~ylon-6).
Ihe extruded and solidified filamentary material
prepared in a manner similar to that already described for
polyethylene terephthalate is next passed through the conditioning
zone provided by an atmosphere of compressed steam having
~5 preferably an absolute pressure of between 170 and 618 kN/m
and more preferably between 200 and 580 k~/m2.
l~SZ273
The filament yarn is withdrawn and wound-up as for poly-
ethylene terephthalate.
The invention will now be described with reference to the
accompanying drawings wherein
Figure 1 shows diagrammatically an apparatus for use in
the prepaxation of filamentary fibres according to the invention, and
Figure 2 is a graphical representation of the results
obtained in the Examples described hereinafter.
In Figure 1, filaments 1 are extruded from a spinneret
assembly 2 into a solidification (quench) zone comprising a chimney
3 in which the filaments are quenched by air, at room temperature,
flowing (not shown) from one side of the chimney to the other side
of the chimney.
The filaments are solidified and converged into a yarn by
a guide 4 and the pass into a conditioning zone 5.
The conditioning zone is a metal tube fitted with valves
(not shown) at each end. The valves, when open, permit the yarn to
be fed through the tube. The valves, when closed, still allow free
movement of the yarn. Inevitably, however, there is a continuous,
but small, loss of steam from the conditioning tube. Means (not
shown) are provided for feeding steam from an appropriate source
(not shown) into the tube at various required pressures.
The tube may be lagged. Alternatively, however, it is
provided with a jacket into which pressurised steam can be fed from
the same steam source as is used for the conditioning tube itself.
In this way uniform temperatures may be maintained in the condition-
ing tube.
After leaving the conditioning zone the yarn optionally
passes through a guide 6, over a finish roller 7, partially im~sed
in a finishing bath 8, through a guide 9, wrapped around high-speed
puller rollers 10 and 11 and then is wound up as a package 12 on a bobbin 13.
The invention will now be described with reference to
the following Examples:-
EXAMPLES 1-16
In a process for melt spinning a filament yarn from
molten polyethylene terephthalate through a spinneret at 291C
'~',~3
~52273
employing an ambient air quench zone immediately below the
spinneret to effect solidification of the filaments, the
solidified filaments were passed through a conditioning
zone. ~he zone consisted of a vertically disposed tube,
about 0.5 metre in length and 0.5 cm in diameter, located
(entry point) 2.2 metres below the exit from the spinneret.
~he yarn entered and exited from the tube through suitable
valves located at each end of the tube. Within the tube
was an atmosphere of pressurised steam which was continuously
fed into the tube from a suitable source. A continuous
leakage of steam occurred through the valves.
After the application of a spin finish, the yarns
produced were finally wound-up on a bobbin at velocities
of 4,000 to 6,000 metres/minute.
qhe process conditions were varied considerably and
the resultæ obtained tabulated in ~able 1.
l~ SZZ73
~ABIE 1
_ _ ~ S~EAM __
_ ~ ~ ~ ~ ~ ~ æ ~ ~ ~ ~ ~ ~ ~ ~ ~ _
_ . ~ _ _
1 4489 4.75 0.64 92.1 20 446 147 112 3o4 615 -
2 4493 4-75 o.64 92.0 20 79o 166 131 418 835135
3 4497 4-75 o.64 91.7 20 962 177 125 419 791 -
4 4611 5.o 0.62 93.o 20 652 162 110 295 632 _
4620 5.o 0.62 49.6 20 652 162 115 351 648 _
1 o - 6 465 - o- ~ 0.62 91.o 20 1101 184 123 315 652 -
7 4671 5-o 0.60 88.7 20~ 1272 189 110 33 695 ~
8 4684 5.o 0.62 63.7 3o 1203 186 116 292 639 -
9 4687 5.0 0.62 63.3 3o 1203 186 119 3oo 65p -
4690 5- o.63 63.7 3o 928 173 119 295 658 -
11 4691 5.o 0.62 63.2 3o 928 173 120 293 649 _
12 4700 5.0 0.62 51.2 20 1203 186 121 368 745 -
13 4702 5.o 0.62 51.4 20 1203 186 113 297 643 _
14 474 5.o 0.62 51.6 20 1410 195 116 342 651 _
475 5.o 0.62 51.4 20 1410 195 119 381 767155
16 4706 5.5 0.62 51.1 20 1410 195 116 372 745 _
_ .. . . ~ _ . _ _
EXAMPIE 17
Polyethylene terephthalate was melt spun into a yarn
using the process described in ~xa-mples 1 to 16, but with a steam
pressure in the conditionin~ tube of only 239 kN/m2. The properties
25 of the yarn were as follows.
.
_ ~ -- ~ b ~
..... .. .
3o 4 75 o .64 91.5 20 239 126 95 53
,
:1~52Z73
12
EXAMPLE 18
Polyethylene terephthalate was melt spun into a yarn
using the process described in Examples 1 to 16 but replacing
the steam conditioning tube by an open-ended tube 1 metre long
5 and 20 mm diameter. Hot air at a temperature of 200c was
introduced into the bottom of the tube so that i~ flowed up the
tube at a flow rate of 90 litres/min. lhe yarn properties produced
were as follows.
~ _ u.~ ~- , ~ .
10 ~ ~ 1~ h ~ ~ i~ !~ ~
. ~
3.5 o.63 56 20 133 668
15 EXAMPLES 19-28
Polyethylene te~ephthalate was melt spun into yarns
using a conventional ~I~inning process without a conditioner tube.
These yaxns were then drawn on a conventional draw frame using
a hot roll ,~nd hot plate. The properties of the resultant ,varns
are sho-~n in ~able 2.
~LE 2
¦ ~! R I I r
192.0 5.31 88 ~ 204140j24 1250 183
205.2 4.63 81 220* 138/36 840 174
218.1 3.22 83 170 84/15 799 160
223-5 2.5 9o _ 85/17 447 105
233.5 3.o 9o _ B7/17 631 140
3o 243 - 5 3.o 9o170 84/17 669 145
253.5 3.5 9o 170 84/17 861 164
263-5 3.5 90 _ 85/17 892 169
273-5 4.o 9o 170 86/17 1079 181
283.5 4. o go _ B8/17 969 187
35 *~ot roll followed by 5.6% relax.
.
S~2~3
It should be noted that Examples 22, 23, 26 and 28
were prepared without the use of a hot plate.
A graph was produced (Eig 2) by plotting Initial
Modulus against ~irefringenoe for all the samples prepared
in aocordance with Examples 1 to 28. On the graph is also
shown lines A'and ~'which'together serve to define the boundary
limits of the novel polyethylene terephthalate fibres of the
invention ie line A corresponds to the minimum birefringence
of 0.105 and line B co~responds to 260 cosh ~0~07n84 3.
It ca,n be seen that examples 1-16 fall within the scope
-of the invention but tEat Examples 17-28 are all outside
-- -the scope of the invention.
EXAMPIES 29-41
In a process for melt spinning a filament yarn from
molten nylon 6,6 polyamide through a spinneret at 288C employing
am ambient air quench zone immediately below the spinneret to
effect solidification of the filaments, the solidified filaments
were passed through a oonditioning tube as described in Examples
1 to 16.
After application'of a spin finish, the yarrsproduced
were finally wound up on a bobbin at velocities of 4.0-5.0 ~ min.
The prooess oonditions were varied oonsiderably and
the results obtained tabulated in ~able 3. These results show that
both the tenaoity and the modulus are increased with increased
steam pressure/temperature in the conditioning zone.
~ Z~7 3
AslE ~ 14
_ ~ li, S~F ~AM ~ H MODUI~ ~ ~ . .
~o REF ~ ~ DTEX ~ ~ ~_ ~ ~ æ/0 50/o 1~/o
. i~ _ _ . ~ _
29 1551 5. o 44.2 13 352 137 39 03 52.0 333 244 162
3o 1552 5.o 44.o 13 239 124 37.87 45.o 334 298 185
31 1553 5.o 44.4 13 204 119 38.41 43.o 353 3o9 199
32 1556 5. o 46.5 13 101 100 37.52 55.0 327 232 156
33 1657 4.5 68.6 20 445 147 39.86 54.1 329 226 157
34 1659 4.5 68.6 20 342 137 38.58 53.7 364 226 156
1661 4.5 68.6 20 239 124 37.89 53.7 363 z8 151
- - - -- 36 1665 4.5 68.7 20 171 114 37.09 59.7 357 217 143
3~ -f6Gg- -~- 568.2 20 101 100 36.64 64.3 338 201 129
38 1566 4.o 4o.5 13 239 124 39.20 45.2 315 237 162
39 1567 4.o 45.2 13 342 137 40.33 54.2 331 212 147
4o 1569 4.o 44.8 13 171 114 43.75 50 7 350 263 171
41 1572 4.o 45.2 13 101 100 38.16 54.1 ~25 217 139
In the above Table 3 it should be noted that Examples
- 32, 37, 41 are outside the scope of the present invention.
EX~MæLES 42-4~
Ex2mples 1-16 were repeated using slightly different
processing conditions. ~he results obtained are tabulated in
Table 4.
~~,ABLE 4
25 ¦ ~ ~ ~ H ~ H ~ _ _ ~b ~N~ ~ô ~ _ ~ ~ ~ _
_ _ _ _~ __ __ _ _
42 1955 5.o 0.63 49.5 20 79o 166 146 460 892 140
43 1946 5oo o.63 49.7 20 79o 166 126 402 826 160
3o 44 1950 5.o 0.63 48.8 20 823 171 131 386 879 160
1949 5.o o.63 49.7 20 790 166 117 351 820 135
_ _ _ _ __ _
..
