Note: Descriptions are shown in the official language in which they were submitted.
i2~4635
This lnvention relates to a method for preparing a plu-
rality of continuous thermoplastic yarns ~hich are substantially
completely drafted, and suitable for use as warp on looms for
fabric manufacture. The method is characterized by starting from
continuous thermoplastic yarns with filaments which are substan-
tially parallel but not completely drafted, these being drafted
and simultaneously sized by immersion into a liquid generally
containing a siziny agent for the filaments which constitute the
actual yarn.
Known processes for preparing continuous yarns from
thermoplastic polymers for textile use comprise spinning the
polymer in its molten state into filaments, cooling it, combining
the filaments to form a yarn and then drafting them.
It is necessary to draft the filaments in order to give
the yarn the necessary physical and mechanical characteristics
for textile use by molecular orientation. Xnown processes for
preparing a drafted yarn use two different methods. Considera-
tion will only be given to that more pertinent to the presentinvention. According to this more pertinent known process, the
yarn produced during spinning is collected onto spools in a not
yet completely drafted state. Drafting takes place in a subse-
quent stage by means of suitable multi-position drafting or
drafting-twisting machines, each position acting on one lndivi-
dual yarn. With said machines it is very difficult to obtain
yarns of perfectly constant characteristics, presumably due to
the fact that each yarn is treated individually and is thus
influenced by minimum differences in the temperature and the
mechanical setting-up of each machine position.
In many cases, in order to be able to be used on looms,
yarns collected from drafting and drafting-twisting machines must
be subjected to a sizing operation in order
i2'~4i35
to prevent breakage of the individual filaments due to mechanical
stresses during weaving. This operation consists of impregnating
the yarns with special sizes according to the following process:
the beams on which the previously warped yarns are wound are
positioned on beam support creels. The yarns, parallel and pro-
perly ordered, are passed through suitable apparatus provided
with an impragnation tank and squeezlng rollers, then through hot
air driers or infrared ovens, or over hot cylinders, and are
finally collected again on beams by a winding machine.
'10
As stated, the method of the present invention enables
an incompletely drafted yarn, as would be obtained from the spin-
ning stage of the said known process, to be used as the starting
yarn for preparing said sized chalns or fractions for weaving,
thus dispensing with the normal stage in which the yarn is oper-
ated on by a drafting or drafting-twisting machine. The new
method combines the two separate drafting and sizing stages into
a single stage, with obvious technical and economical advantages.
According to the present invention therefore, there is
provided a method for preparing a plurality of completely drafted
continuous yarns made of a thermoplastic polymer selected from
the group of polyester, polyamide, polyethylene and polypropy-
lene, which method comprises: immersing continuous thermoplastic
yarns in which the filaments forming the yarns are substantially
parallel and are not completely drafted, into a tank containing a
liquid in which at least one sizing agent is present, the liquid
being at a temperature to enable the filaments forming the yarns
to be drafted; simultaneously substantially completely drafting
the yarns in said tank; and drying said drafted yarns to form a
plurality of continuous yarns suitable for use as a warp ~chain)
on looms for fabric manufacturing. Suitably the drafting is
carried out by two roller systems rotating at suitably different
speeds and disposed at the ends of the tank. Desirably the yarns
are drafted simultaneously by several traction systems in order
to correspondingly vary the drafting ratio. Suitably a polyester
.~ ~
B ~ -2 -
~"
:
3S
or acrylic sizing agent is used for the sizlng.
The method, shown diagrammatically on the accompanylng
drawiny, can be described as follows:
- 2a -
B
_ 3 _ 1244~35
.
the cops of inco~pletely drafted yarn ori~inati~6 from the
spinnin~ operstion are loaded in a pre~eter~ined number on to
a fced creel (A) from which the yarns unwind ~ith con~tant
tension, and are disposed parDllel to each othcr by means of
a ~uide i~ the form of a comb (B); the yarns pas~ throu~h a
feed and 5upport roller sy~te~ (C) rotatin~ at co~stant
speed; then through a tDnk (D) filled with liquid containlng
~t least one cohesion agent kept at a temperature such as to
~llow drafting of the constituent filaments of the yarn; fro~
here the yarns pass through a system of trsction rollerR t~)
rotating at a constant peripheral speed which is 2reater than
that of the feed rollers (C). The roller sys'em (~) also
squeezes the excess liquid re~ininG in the yarn. The
required drafting action and ~olecular orlentation of the
filaments is obtai~ed simult~neously for all the indi~idual
fed y3rns between the feed rollers (C) and traction rollers
(o) by virtue of the tension ~enerated by the different
peripheral speeds and the softenin~ of the polymer due to
heat.
rhe present in~ention thus cna~les the separate drafti~s and
sizing operations of the prior art to be combined into s
sin~le simultaneous drafting and sizing operation.
;fter dra~ting and si~ing, the yarns are dried by pDSSa~e
tl-~ouOh ovens tF) which can be of variou-~ types, and/or oYer
hot cylinders (G) which also exert a thernal stabilislng
action on the yarn, and are finally collected on be~s or the
like by means of a ~inding nachine (H).
3o
~ ~odification to the present method con6ists of feedinG the
y3rn from be~ms, s~all beam6, lar~e reels or 3ny other support
pre ared in a previous p~ss~e by a winding ~ach-ne~ instead
of directly from the cops losded on to a creel.
In thi6 case~ it is also ~o~sible to conb~ne a nu~ber o$
fractlonal beams before enterlng the feed rollers (C) of the
draftlng stage. The new slmultaneous draftlng-slzlng method for
several con~lnuous thermoplastlc yarns dlsposed parallel to each
other, accordlng to the present Inventlon, enables conslderable
economles ~o be obtalned over conventlonal methods because It
completely elImlnates the need for a prevlous draftlng stage on
the Indlvldual yarns uslng draftlng or draftlng-twlstlng machlnes
accordlng to the known process mentloned In the Introductlon,
elther before collectlon from the splnnlng operatlon or after
10 collectlon.
Thls Is obtalned wlthout substantlally modlfylng the
conventlonal warplng and sIzIng systems whlch remaln substan-
tlally the same, but wlth the mere replacement of the conven-
tlonal Impregnatlon sectlon by the slmultaneous draftlng-slzlng
sectlon.
It has also been found from the numerous tests carrled
out that fabrlcs prepared from yarns treated by the new method
zO have excellent characterlstlcs In terms of compactness and unl-
formlty.
The Inventlon Is Illustrated further by the followlng
non-lImltlng Examples.
2~
EXAMPLE 1
800 cops of partlally orlented lucld polyester yarn
(POY) havlng the followlng characterlstlcs are loaded onto a
warplng feed creel:
Count: 8Z Dtex
Number of fllaments: 48
Fllament cross-sectlon: trlangular
Breaklng load: 260 grams
Ultlmate elongatlon: 147X
Theoretlcal resldual draft: 1.464 (82/56).
~2~35
The yarns are warped at a speed of 300 metres/mlnute
and wlth a tenslon of 10 grams after checking Irregularltles wlth
a Llndley apparatus, then collectln~ them In a slngle fractlon of
length 40,000 metres on a beam of hel~ht 180 mm.
The fractlon warped In thls manner Is placed on a
unwlndlng stand, and the yarns are passed $hrough the blades of a
rectlllnear comb.
The yarns are anchored and dragged wlth a tenslon of 10
grams by a system of three rollers, whlch rotate In unlson at a
constant perlpheral speed of 130 metresJmlnute.
The yarns are then Immersed In a tank contalning a bath
of hot slze conslstlng of a 10X aqueous solutlon of Adex-Twe
acryllc slze of the flrm Cesalplnla, kept at a constant tempera-
ture of 90C.
A system of three draftlng and squeezlng cyllnders
whlch rotate In unlson wlth a constant perlpheral speed of 200
metres/mlnute acts slmultaneously on all yarns so that they are
drafted to a ratlo of 1.538 relatlve to the feed.
At the exlt of the draftlng and squeezlng cyllnders,
the aqueous slzlng solutlon remalnlng on the yarns Is about 80X
of the welght of the dry yarn.
The yarns are then drled by passlng them through hot
alr ovens and are then fIxed thermally by belng passed over and
In contact wlth fIve hot rotatlng cyllnders kept by steam at a
temperature varylng from 105C at the fIrst to 90C at the last
cyllnder.
The speed of the hot cyllnders Is kept sllghtly less
than 200 m/mlnute so as to allow a certaln shrlnkage In the
length of the yarns before fIxln0.
12~35
At thelr exlt from the flxlng cyllnders the yarns are
wound on beams of helght 180 mm In elght fractlons of 5000 metres
each.
The average characterlstlcs of the yarns drafted and
slzed In thls manner are as follows:
Count: 55.6 Dtex
Breaklng strength: 254 grams
Ultlmate elongatlon: 30%
Shrlnkage In bolllng water: about 8%
Slze remalnlng on the yarn: 8/8.5X.
Durlng the next stage, the elght slzed fractlons are
comblned on a weavlng beam of helght 1550 mm wlth a total of 6400
yarns.
The beam Is loaded onto an LV/51 Nlssan water loom and
wefted wlth texturlzed polyester yarn of count 56 Dtex and 24
fllaments, at a speed of 360 beats~mlnute, wlth a cloth weave and
wlth a denslty of 33 wefts/cm.
The fabrlc Is then scoured In full wldth In a contlnu-
ous scourlng and washlng machlne at a speed of 15 m/mlnute. The
scourlng bath conslsts of water softened by treatment wlth lon
exchange resln, kept at 90C and contalnlng 10 cc/lltre of 36~38
Be caustlc soda, 5 cc/lltre of a detergent and 0.5 g/lltre of a
sequesterIng agent. Thls Is followed by two wash baths wlth hot
and cold water, and neutrallzatlon wlth acetlc acld.
The scoured fabrlc Is then dyed In a Jet cord dyelng
machlne (Mezzers). The dlspersed dye used Is Dlspers Blue Co~or
Index 056, dlssolved In a bath of softened water wlth a dye con-
centratlon of 2~ of the welght of the fabrlc and wlth the addl-
tlon of 2X of an evener and 0.2X of a dlspersln~ agent. The pH
Is adJusted to 4.5 by addlng formlc acld, and stablllzed wlth
monosodlum phosphate.
- 6 -
.~
12~35
Dying is carried out with the following temperature
cycle: starting from 60C, the temperature rises to 130C at a
rate of 1C/minute; 130C is maintained for 20 minutes; the tem-
perature falls to 80C at a rate of 1C/minute, the dyeing bath
is then discharged and the fabric washed with hot and cold water.
The fabric, centrifuged and dried in hot air, is passed
through a stenter machine and thermo-fixed at 180C at a speed of
25 m/minute. A fabric is obtained having a height of 140 cm with
a weight of 55 g/m2 and a chain shortening, from raw to finished,
of 5.5i6%. During passage over the evenness tester for detecting
any fabric defects, a high uniformity and compactness of the
chain yarns is noted, with total absence of lucid yarns.
EXAMPLE 2
The preceding experiment is repeated by feeding a yarn
with the following characteristics from a beam:
Count: 80 Dtex
Number of filaments: 36
Filament cross-section: triangular
Breaking strength: 251 grams
Ultimate elongation: 153%
Theoretical residual draft: 1.536 (80/52)>
The feed cylinders are rotated with a peripheral speed
of 126 m/minute, whereas the drafting-squeezing cylinders rotate
at 200 m/minute, with a drafting ratio of 1.587.
The sizing bath is constituted this time by an 11%
aqueous solution of Kodak 9519 polyester size kept at a tempera-
ture of 90C.
;
The temperature of the fixing cylinders varies between
105C and 90C, and their perlpheral speed is slightly less than
200 m/minute.
-- 7
~2~ 5
The average final characterlstlcs of the drafted and
slzed yarn are as follows:
Count: 52.4 Dtex
Breaklng strength: 238 grams
Ultlmate elongatlon: 31X
Shrlnkage In bolllng water: about 8X
Slze remalnlng on the yarn: 9/9.2X
The slzed fractlons are then comblned and woven In the
same manner as In the precedlng Example.
Scourlng, dyelng and fIxln~ are then carrled out as In
the precedlng Example, the only dlfference belng that the scour-
lng bath contalns 0.5 g/l of sodlum carbonate Instead of caustlc
soda.
A fInlshed fabrlc of helght 140 cm Is obtalned, wlth a
welght of 53 g/m2 and a chaln shortenlng, from raw to flnlshed,
of 5.5/6X.
Durlng passage of the fabrlc through the evenness
tester, an almost perfect unlformlty of the chaln yarns Is agaln
observed In thls case.
EXAMPLE 3
The precedlng experIment Is repeated by feedlng a yarn
wlth the followlng characterlstlcs from a beam:
Count: 103 Dtex
Number of fllaments: 24
Fllament cross-sectlon: trlangular
Breaklng strength: 262 grams
UltImate elongatlon: 176
Theoretlcal resldual draft: 1.776 (103/58).
The feed cyllnders are rotated at a perlpheral speed of
~ 3 5
110 m/minute, whereas the draftiny-squeezing cyllnders rotate at
200 m/minute, with a drafting ratio of 1.~18.
The sizing bath is the same as in Example 2, and the
fixing cylinder temperature varies from 110C to 90C.
The final average characteristics of the drafted and
sized yarn are as follows:
Count: 58.2 Dtex
sreaking strength: 257 grams
Ultimate elongation: 28.5%
Shrinkage in boiling water: about 8.5%
Size remaining on the yarn: 8.9/9.2%.
The slzed fractions are then combined and woven in the
same manner as in the preceding Example.
Scouring, dyeing and finishing are also carried out in
the same manner as in Example 2.
A finished fabric of height 140 cm is obtained, with a
weight of 56 g/m2 and a chain shortening, from raw to finished,
of 6%.
Good uniformity of the chain yarns was again noted in
this case during passage of the fabric through the evenness
tester.
EXAMPLE 4
: 96 cops of partially oriented lucid polyester yarn (POY) with the following characteristics are loaded onto eight creel carriages
with yarn guides and disc tensioning devices:
Count: 127 Dtex
Number of filaments: 24
Filament cross-section: triangular
g
~2~4~;35
Breaklng strength: 328 grams
Ultlmate elongatlon: 163X
Theoretlcal resldual draft: 1.628 ~127~78~.
6 The yarns are passed through a perforated warplng table
and then through the blades of a rectlllnear comb.
The yarns are then anchored and dragged wlth a tenslon
of 11 grams by the feed rollers of the slmultaneous draftlng and
slzlng system of the precedlng Example.
The feed cyllnders are rotated at a perlpheral speed of
117 m/mlnute, whlle the draftlng-squeezlng cyllnders rotate at
200 m/mlnute wlth a draftlng ratlo of 1.709.
The slzlng bath Is constltuted by a 10X a~ueous solu-
tlon of Wlsacrll PNS acryllc slze of the fIrm Bozzetto, kept at a
temperature of 90C.
The temperature of the flxlng cyllnders varles between
115C and 95C, and their perlpheral speed Is sllghtly less than
200 m/mlnute. The flnal average characterlstlcs of the drafted
and slzed yarn are as follows:
Count: 77.2 Dtex
Breaklng strength: 820 grams
Ultlmate elongatlon: 31.4X
ShrInkage In bolllng water: about 8.3X
Slze remalnlng on the yarn: 8.1/8.4X.
Thls test was llmlted to determlnlng the fInal charac-
terlstlcs of the yarn, as the total number of yarns was not slg-
nlfIcant for a weavlng test. However, the characterIstlcs found
by analyzlng 32 yarns out of 96 Indlcated a very low dlsperslon.
~5
:
-- 10 --
