Note: Descriptions are shown in the official language in which they were submitted.
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AIR JET-TEXTURING PROCESS FOR PRODUCTION
_ OF LOW-SHRINKAGE POLYESTER YARN
This invention relates to the production of air
jet-textured bulked polyester yarn from spin-oriented poly-
ester yarn and more particularly to the production of such
air jet-textured yarn having a low dry heat shrinkage.
The term "spin-oriented polyester yarn" as used
herein means such yarn prepared by melt-spinning polyeth-
ylene terephthalate into yarn while withdrawing the yarn
from the spinneret at a take-off speed of 3000 to 4000
yards/minute (2740 to 3660 metres/minute) as described by
Gorrafa in United States Patent No~ 3 973 386 issued 1976
August 10.
Measurements of "dry heat shrinkage" as used
herein are obtained by (a) suspending a weight from a skein
of yarn to produce a 0.1 g/denier (0.0883 dN/tex) load on
the yarn and measuring its length (Lo)~ (b) replacing the
weight by a lighter weight generating a 0.005 g/denier
20 (0.00441 d~/tex) load and placing the loaded yarn in an oven
at 250 + 5F (121 + 2.8C) for 5 minutes, (c) removing the
_
yarn, cooling it to room tem?erature, loading it again with
the original weight, and recording its new length (Lf), and
(d) calculating the shrinkage as follows:
Dry heat shrinkage (%) = (Lo - Lf)/Lo x 100
A prior art process for producing air jet-textured
yarn from spin-oriented polyester yarn involves the follow-
ing steps: ~a) hot-drawing the spin-oriented polyester yarn
e.g. over a heated draw pin at a draw ratio in the range of
30 from 1.3 to 2.0; (b) feeding the yarn to an air jet at 10%
to 40% overfeed; (c) jet-texturing the yarn with the air
jet; (d) drawing the jet-textured yarn at a draw ratio of
1.04 to 1.12 to reduce the size of large loops produced
during the jet-texturing step; (e) post-heating the jet-
textured yarn; and (f) winding up the resulting jet-taxtured
yarn.
The jet-textured polyester yarn produced by the
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above prior art process has a relatively high dry heat
shrinkage e.g. about 4.1% to about 4.5% for 400 dtex to 600
dtex yarn; about 4.8% to about 6.4% for 800 dtex to 1200
dtex yarn; and even higher for yarn above 1200 dtex. While
such dry heat shrinkages are satisfactory in many end uses
for the jet-textured polyester yarn, they are a disadvantage
when it is desired to use the yarn for applications which
require yarns having lower dry heat shrinkages.
Surprisingly it has now been found that by replac-
ing the hot drawing step in the above prior art process by acold drawing step followed by a preheating step at constant
yarn length, optionally without the post-heating step, jet-
textured yarns may be produced which have significantly
lower dry heat shrinkages e.g. about 2.2% to about 2.8% for
400 dtex to 600 dtex yarn; about 3.1~ to about 3.5% for 800
dtex to 1200 dtex yarn; and about 3.5% to about 3.9% for
1200 dtex to 2000 dtex yarn.
Accordingly the present invention provides a
process for producing an air jet-textured polyester yarn
having a low dry heat shrinkage, the process comprising the
steps of: (a) cold drawing a spin-oriented polyester yarn
at a draw ratio in the range of from 1.3 to 2.0; (b) pre-
heating the drawn yarn at substantially constant yarn
length; (c) feeding the yarn to an air jet at a 10% to 40%
overfeed; (d) jet-texturing the yarn with the air jet; (e)
drawing the jet-textured yarn at a draw ratio of 1-04 to
1.12; and (f) winding up the resulting jet-textured yarn.
The term "overfeed" to the air jet as used herein
means:
Feed sPeed to air iet - Removal sPeed from air iet
. x 100%
Removal speed from alr ~et
In one embodiment of the process of the present
invention a step of post-heating the jet-textured yarn is
included between step (e) and step (f).
In another embodiment of the process of the
present invention the step of preheating the drawn yarn and
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the step of post-heating the jet-textured yarn are each
carried out on a contact heater plate operating at a surface
temperature in the range of from 180C to 220C.
In yet another embodiment of the process of the
present invention the yarn is fed to the air jet at a 20% to
30% overfeed.
In yet another embodiment of the process of the
present invention the jet-taxtured yarn is drawn at a draw
ratio of 1.06 to 1.10.
In yet another embodiment of the process of the
present invention the step of preheating the drawn yarn and
the step of post-heating the jet-textured yarn are each
carried out on the surface of a contact heater plate operat-
ing at a surface temperature in the range of from 205C to
215C.
In yet another embodiment of the process of the
present invention the yarn is fed to the air jet at a 23% to
27% overfeed.
In a further embodiment of the process of the
present invention the spin-oriented polyester yarn is cold
drawn at a draw ratio of from 1.6 to 1.8.
In a still further embodiment of the process of
the present invention the cold drawing step is carried out
at a draw ratio of from 1.6 to 1.8 on a draw roll operating
at a surface speed of at least 375 metres/minute and the
resulting air jet-textured yarn has a linear density in the
range of from 400 dtex to 600 dtex and has a dry heat
shrinkage in the range of from about 2.2% to about 2.8%.
In a still further embodiment of the process of
the present invention the cold drawing step is carried out
at a draw ratio of from 1.6 to 1.8 on a draw roll operating
at a ~urface speed of at least 375 metrestminute and the
resulting air jet-textured yarn has a linear density in the
range of from 600 dtex to 1200 dtex and ha6 a dry heat
shrinkage in the range of from about 2.8% to about 3.5%.
In a still further embodiment of the process of
the present invention the cold drawing step is carried out
at a draw ratio of from 1.6 to 1.8 on a draw roll operating
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at a surface speed of at least 375 metres/minute and the
resulting air jet-textured yarn has a linear density in the
range of from 1200 dtex to 2000 dtex and has a dry heat
shrinkage in the range of from about 3.5% to about 3.9%.
In a still further embodiment of the process of
the present invention the cold drawing step is carried out
at a draw ratio of from 1.6 to 1.8 on a draw roll operating
at a surface speed of at least 240 metres/minute and the
resulting air jet-textured yarn has a linear density in the
range of from 2000 dtex to 3500 dtex and has a dry heat
shrinkage of less than about 3.0%.
An embodiment of the present invention will be
described in greater detail with the aid of the accompanying
drawing which is a schematic representation of apparatus
suitable for carrying out the process of the present
invention.
In the drawing, spin-oriented polyester yarn 10 is
pulled from a supply package 11 over a yarn guide 12 by feed
; roll assembly 13, comprising a feed roll 14, a cot roll 15
and a separator roll 16. Yarn 10 is passed about cot roll
15 and separator roll 16 for a plurality of wraps. From
the feed roll assembly 13 the yarn 10 passes to a draw roll
- assembly 17, comprising draw roll 18 and separator roll 19.
The yarn 10 is passed about draw roll 18 and separator roll
19 for a plurality of wraps. Draw roll assembly 17 runs at
a faster speed than feed roll assembly 13 to draw the yarn
at a draw ratio in the range of from 1.3 to 2.0 and prefer-
ably in the range of from 1.6 to 1.8. From draw roll
assembly 17, the drawn yarn passes over a heater plate 20,
which operates at a temperature in the range of from 180C
to 220C and preferably in the range of from 205C to 215C,
to roll assembly 21, comprising driven roll 22 and separator
roll 23. The drawn yarn is passed about driven roll 22 and
separator roll 23 for a plurality of wraps. Preferably roll
assembly 21 runs at the same speed as draw roll assembly 17.
From roll assembly 21, the yarn passes over yarn guide 24
under guide pin 25 which is immersed in a bath 26 containing
water at room temperature. It then passes over yarn guide
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27, through air jet bulking device 28, to roll assembly 29,
comprising driven roll 30 and separator roll 31. The jet-
textured yarn is passed about driven roll 30 and separator
roll 31 for a plurality of wraps.
The air jet bulking device 28 produces crunodal
surface loops. A preferred jet is disclosed by Agers in
United States Patent No. 4 157 605 issued 1979 June 12 (see
particularly Figures 6 and 7). The yarn is immersed in
water bath 26 in order to improve the efficiency of air jet
bulking device 28. Water bath 26 and air jet bulking device
28 may both be placed in an enclosed air jet-texturing chest
as disclosed by Wirsig in European Patent Application No.
A 0 004 781 published 1979 October 17. The overfeed of yarn
to the jet, which may be determined by
Speed of roll assemblY 21 - Speed of roll assemblY 29
Speed of roll assembly 29 x 100%
may be set as desired in the range of from 10% to 40%, but
is preferably in the range of from 20~ to 30%, especially
in the range of from 23% to 27%.
From the roll assembly 29, the jet-textured yarn
passes to draw roll assembly 32, comprising draw roll 33 and
separator roll 34. The jet-textured yarn is passed about
draw roll 33 and separator roll 34 for a plurality of wraps.
Draw roll assembly 32 runs at a faster speed than roll
assembly 29 to draw the jet-textured yarn at a draw ratio in
the range of from 1.04 to 1.12 and preferably in the range
of from 1.06 to 1.10. This post drawing step tends to
reduce the number of large and poorly formed crunodal
surface loops produced by the air jet bulking device 28 and
hence to improve the handling characteristics of the
jet-textured yarn. From draw roll assembly 32, the
jet-textured yarn passes over a heater plate 35, which
operates at a temperature in the range of from 180C to
220C and preferably in the range of from 205C to 215C, to
roll assembly 36, comprising driven roll 37 and separator
roll 38. The jet-textured yarn is passed about driven roll
37 and separator roll 38 for a plurality of wraps.
Preferably roll assembly 36 runs at the same speed as draw
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roll assembly 32. This post-heating step at substantially
constant yarn length tends to reduce the size of the surface
loops and to improve the stability of the jet-textured yarn.
The term "stability" as used herein means a measure of the
load carrying capacity of the jet-textured yarn before the
loops begin to straighten out throughout the yarn bundle.
It will be appreciated that the post-heating step
may be omitted if it is desired to produce jet-textured yarn
having larger surface loops. From roll assembly 36 the
jet-textured yarn is wound up on package 39.
The apparatus for carrying out the process shown
schematically in the drawing and described above may be
provided on two adjacent positions of a conventional draw
twister e.g. a Model 14S drawtwister manufactured by Zinser
Textilmaschinen GmbH by making the following modifications:
(a) adding separator roll 16 to the feed roll assembly
of the first position;
(b) converting the draw roll in each position to a
stepped draw roll by adding a smaller diameter
roll and adding an associated separator roll in
the first position;
(c) adding a heater plate above the draw roll in the
first position;
(d) adding a jet-texturing chest (containing water
bath 26 and air jet bulking device 28 as described
in aforementioned European Patent Application No.
A 0 004 781) above the draw roll in the second
position;
(e) adding two change-of-direction rolls and several
yarn guides; and
(f) modifying the wind-up device.
With the above modifications to two adjacent
positions on a Model 14S Zinser drawtwister: (1) feed roll
assembly 13 comprises the feed roll assembly of the first
position; (2) draw roll assembly 17 comprises the larger
diameter roll of the stepped draw roll of the first position
and its associated separator roll; (3) heater plate 20
comprises the heater plate added above the draw roll of the
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first position; (4) roll assembly 21 also comprises the
larger diameter roll of the stepped draw roll of the first
position and its associated separator roll; (5~ water pan 26
and air jet bulking device 28 are contained in the jet-
texturing chest added above the draw roll of the secondposition; (6) roll assembly 29 comprises the smaller diam-
eter roll of the stepped draw roll of the second position
and the separator roll of the second position; (7) draw roll
assembly 32 comprises the smaller diameter roll of the
stepped draw roll of the first position and its associated
separator roll; (8) heater plate 35 also comprises the
' heater plate added above the draw roll of the first
position; and (9) roll assembly 36 also comprises the
smaller diameter roll of the stepped draw roll of the first
position and its associated separator roll.
The present invention is illustrated by the
following examples.
EXAMPLE I
A composite 590 dtex, 68 filament, spin-oriented
polyester yarn was cold drawn in a drawing zone, preheated
on a heater plate, jet-textured with an air jet, drawn in a
post drawing zone, post-heated on a heater plate and wound
up on a package. The spin-oriented polyester yarn had been
prepared by melt spinning polyethylene terephthalate into
yarn while withdrawing the yarn from the spinneret at 3110
metres/minute. The apparatus used, which is shown schemati-
cally in the drawing, was provided on two adjacent positions
of a Model 14S drawtwister (manufactured by Zinser Textil-
! maschinen GmbH) by making the modifications described here-
inabove. The air jet bulking device 28 was substantially
the same as that shown in Figures 6 and 7 of aforementioned
United States Patent No. 4 157 605. The feed rate of spin-
oriented polyester yarn 10 provided by feed roll assembly 13
was 237 metres/minute. Draw roll assembly 17 was operated
at a speed of 391 metres/minute to give a draw ratio of
391 = 1.65. Heater plate 20, which was 63.5 cm in
237
length, was operated at a temperature of 210C and roll
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assembly 21 was operated at 391 metres/minute so that the
yarn was preheated at constant length. Air jet 28 was
operated with an air pressure of 1146 kPa (150 psig). Roll
assembly 29 was operated at a speed of 312.8 metres/minute
so that the overfeed of the yarn to the air jet 28 was
391 - 312.8 x 100~ = 25%. Draw roll assembly 32 was
312.8
operated at a speed of 336.3 metres/minute so that the
jet-textured yarn was drawn at a draw ratio of 336.3 = 1.075.
312.8
Heater plate 35, which was 63.5 cm in length, was operated
at a temperature of 210C and roll assembly 36 was operated
at a speed of 336.3 metres/minute so that the jet-textured
yarn was post-heated at constant length. The jet-textured
yarn was wound up on a surface driven package 39 by a driver
roll (not shown). The surface speed of the driver roll was
344 metres/minute; however, slippage between the driver roll
and the package 39 may have occurred. The linear density of
the air jet-textured yarn on package 39 was found to be
404.0 dtex and the dry heat shrinkage thereof (obtained by
the method described hereinbefore) was found to be 2.19%.
EXAMPLE II
A composite 885 dtex, 102 filament, spin-oriented
polyester yarn was treated on the same apparatus and in the
same manner as the yarn in Example I. The spin-oriented
polyester yarn had been prepared under the same conditions as
that of Example I. The linear density of the resulting jet-
textured polyester yarn on package 39 was found to be 600.5
dtex and the dry heat shrinkage thereof was found to be
2.86%.
EXAMPLE III
A composite 1180 dtex, 136 filament, spin-oriented
polyester yarn was treated on the same apparatus and in the
same manner as the yarn in Example I. The spin-oriented
polyester yarn had been prepared under the same conditions as
that of Example I. The linear density of the resulting jet-
textured polyester yarn on package 39 was found to be 802.8
dtex and the dry heat shrinkage thereof was found to be
3.06%.
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EXAMPLE IV
A composite 1770 dtex, 204 filament, spin-oriented
polyester yarn was treated on the same apparatus and in the
same manner as the yarn in Example I. The spin-oriented
polyester yarn had been prepared under the same conditions
as that of Example I. The linear density of the resulting
jet-textured polyester yarn on package 39 was found to be
1209.5 dtex and the dry heat shrinkage thereof was found to
be 3.52%.
EXAMPLE V
A composite 2950 dtex, 340 filament, spin-oriented
- polyester yarn was treated on the same apparatus and in the
same manner as the yarn in Example I. The spin-oriented
polyester yarn had been prepared under the same conditions
j 15 as that of Example I. The linear density of the resulting
jet-textured polyester yarn on package 39 was found to be
2014.5 dtex and the dry heat shrinkage thereof was found to
be 3.85%.
EXAMPLE VI
A composite 4720 dtex, 544 filament, spin-oriented
polyester yarn was treated on the same apparatus and in the
same manner as that of Example I except that the operating
yarn speeds were slower. The spin-oriented polyester yarn
had been prepared under the same conditions as that of
Example I. The feed rate of spin-oriented polyester yarn 10
provided by feed roll assembly 13 was 146.5 metres/minute.
Draw roll assembly 17 was operated at a speed of 252
metres/minute to give a draw ratio of 252 = 1.72. Roll
146.5
':
30 assembly 29 was operated at a speed of 201.6 metres/minute
~o that the overfeed of yarn to the air jet was 252 - 201.6
201.6
x 100% = 25%. Draw roll assembly 32 was operated at a speed
2I6.7 metres/minute so that the jet-textured yarn was drawn
; 35 at a draw ratio of 216.7 = 1.075. Roll assembly 36 was
,! 201.6
operated at a speed of 216.7 metres/minute 80 that the jet-
textured yarn was post-heated at constant length. The jet-
textured yarn was wound up on a surface driven package 39 by
a driver roll (not shown). The surface speed of the
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driver roll was 230 metres/minute; however, slippage between
the driver roll and the package 39 may have occurred. The
linear density of the air jet-textured yarn on package 39
was found to be 3206 dtex and the dry heat shrinkage thereof
(obtained by the method described hereinbefore) was found to
be 2.68%.
EXAMPLE VII
For comparative purposes five tests (A to E) were
run with the same composite spin-oriented polyester yarns as
in Examples I to V respectively. However, these tests (A to
E) were run according to a prior art process by modifying
the apparatus shown in the drawing as follows: (1) a hot
draw pin was inserted between feed roll assembly 13 and draw
roll assembly 17 and (2) the heater plate 20 and the roll
assembly 21 were removed. In each test the hot draw pin was
operated at 125C with a 360 yarn wrap about the pin and
the hot draw ratio was 1.65. Other conditions were main-
tained substantially the same as those for Examples I to V.
The results are summarized below in the Table, which also
includes the results for Examples I to V.
TA3LE
: AIR JET TEXTURED YARN PRODUCED
Dry Heat
Test Linear Density Shrinkage
. (dtex) (~)
A 401.5 4.15
B 608.2 4.58
C : 814.6 4.77
D 1227.3 6.41
E 2024.2 15.17
Example I 404.0 2.19
Example II 600.5 2.86
Example III 802.8 3.06
Example IV 1209.5 3.52
Example V ~ 2014.5 3.85
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The dry heat shrinkage~ of the air jet-textured
yarn produced in tests A to E (prior art process) are much
higher than the dry heat shrinkages of the air jet-textured
yarn produced in corresponding Examples I to V (process of
present invention).
EXAMPLE VIII
In order to determine the effect of omitting the
step of post-heating the yarn at substantially constant yarn
length, EXAMPLE VI was repeated with the exception that
heater plate 35 and roll assembly 36 were not utilized i.e.
the jet-textured yarn was wound up on package 39 directly
from draw roll assembly 32. The linear density of the air
jet-textured yarn on package 39 was found to be 3242 dtex and
the dry heat shrinkage thereof was found to be 2.57%. The
comparative figures for EXAMPLE VI were a linear density of
3206 dtex and a dry heat shrinkage of 2.68%.
From the above, it is apparent that the dry heat
shrinkage of the air jet-textured yarn was just as low when
the step of post-heating the yarn at substantially constant
yarn length was omitted as it was when the step was included.
A visual examination of the air jet-textured yarn, however,
indicated that the surface loops in the yarn produced in
EXAMPLE VIII i.e. with the post-heating step omitted, were
considerably larger in size than the surface loops in the
yarn produced in EXAMPLE VI i.e. with the post-heating step
included.
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