Note: Descriptions are shown in the official language in which they were submitted.
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S P E C I F I C A T I 0 N
The present invention relate!s to filaments or
. fibres produced therefrom of polyester, preferably
: of polyethylene terephthalate, which can be drawn
with molecular orientation and to a process for
their productibn and to various uses of these fila-
ments or fibres.
The productlon of filaments of the type in
question is known for example from Swiss Patent
No. 354,202. In this known process, the melt-spun
undrawn filaments are passed through a watèr bath
kept at temperatures-of from 70 to 100C and are
: permanently plastlcally extended with a reduction
in their molecular orientation. Although, according
to Swiss Patent No. 354,202, the filaments are said
to be extended to between I5 and 20 times their
original length, the Examples show that the deniers
in which the filaments are spun are so high that it
is only possible to obtain individual deniers of
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greater -than 2.75 den (approximately 3 dtex) with
corresponding elongation. During the orien-ting
drawing step which, normally, always follows elon-
gation, it is only possible in this way to obtain
individual deniers of more than about o.6 dtex. A
denier such as this is not fine enough for a number
of new applications for synthétic filaments or fibres.
Nowadays much finer individual de!niers are required,
for example, for non-woven fabrics, which in various
fields of application (for example, outer clothing,
synthetic shaft material, fllter aids) have to show
a certain porosity in addition to low weights per
square metre. Unfortunately, it has hltherto only
been possible with considerable difficulty to obtain
individual deniers as fine as these by spinning
measures. Numerous other textile applications require
fine-denier continuous yarns, if posslble also with
a fibre yarn character, or fine-denier fibre yarns,
-the fineness of the individual denier of the filaments -
or fibres present in the yarns significantly affecting
the softness in feel of the yarns and/or sheet-form
materials produced therefrom.
Although there are already known processes for
- producing drawn filament structures of relatively
fine denier, in which matrix-fibril or matrix-filament
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systems are produced by two-component spinning tech-
niques and the matrix subsequen-tly removed (for
example by dissolution with a chemical solvent),
.these known processes are also unsuitable for the
production of filaments which can be drawn with
molecular orientation, quite apart from their com-
plexity and the problems involved in working with
solvents.
An object of the present invention is to provide
filaments of polyester and prefe~ably polyethylene
terephthalate, which can be drawn with molecular
orientation, from which:
(a) it is possible by molecule-orienting drawing to
produce textile filaments or fibres produced therefrom
whioh, as filament yarns, fibre-yarn-like filament
yarns or fibre yarns can be processed into sheet-form
- textiles having a particularly soft feel and an out-
standing appearance, the textile data of the filament
. . or fibres, i.e. their strength, elongation and
20 shrinkage, being typical of normal spun and drawn
filaments or fibres;
(b) it is possible by molecule-orienting drawing and
division known p~ se (e.g. cutting or tearing) to
produce staple fibres which may be processed into non-
wovens of particular softness and particular density,
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in addition to which unusually low weights per square
metre may be obtained;
(c) it is possible by division known per se without
molecule-orienting drawing to produce fibres which
by virtue of their very low crystallinity, in con-
trast to fibres produced from filaments drawn with
molecular orientation, are eminently suitable for
use as binding fibres in the production of non-wovens
without adversely affecting the softness of the non-
woven;(d) it is possible to produce bulky mixed fibre yarns.
Another object of the present inv~ention is to
provlde particularly fine-denier filaments or fibres
produced therefrom using conventional spinning outfits
and normal splnning speeds, the filaments being drawn
and/or divided at relatively high w~rking speeds. In
addition, drawing is intended to be carried out under
the most favourable energy-distribution conditions.
According to the present invention there is
provided filaments or fibres produced therefrom of
polyester, which can be drawn with molecular orien-
tation, and have a double refraction of from 0.004
to approximately 0.12 and an individual denier of less
than 2.5 dtex.
It must be regarded as surprising to the expert
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that filaments of fibres having as fine a denier as
this can be produced at all and that they may even
be technically further processed in such diverse
forms and without difficulty to form filament-like
or sheet-form textile materials having outstanding
optical and feel properties. The expert was not
encouraged by the prior art to approaoh the subject
of deniers as fine as these in filaments or fibres
which have not yet been drawn with molecular orien-
tation or, in particular, to formulate any ideasconcerning the use of structures such as these.
The preferred individual denier range extends
from 2.0 to 0.2 dtex, the upper limit applying to
filaments which are of course intended to have an
individual denier of less than 0.4 dtex after mole-
' cule-orienting drawing in the usual way, and the lower
limit applying to fibres (which have not been drawn
with molecular orlentation) because, below this limit,
staple f1bres can only be carded on special carding
machines. Accordingly, filaments preferably have
individual deniers of less than 2.0 dtex whilst fibres
preferably have individual deniers'of greater than
0.2 dtex (up to 2.5 dtex).
' For producing filaments of particularly fine
' 25 denier and bulky mixed yarns`'~and for use as binding
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fibres in the manufacture of no:n-wovens, the filaments
or fibres according to the invention are characterised
in particular by a molecule-orienting drawability of at
least 1:2Ø
The filaments according to the invention or the
fibres obtained therefrom may be produced using the
first stage of the process known from Swiss Patent No.
354,202, the spun filaments having to be extended
without any orientation to an individual denier of
less than 2.5 dtex and preferably to an individual
denier of from 2.0 to 0.2 dtex. However, a process
such as this is very difficult to carry out (parti-
cularly with regard to the uniformity of the structure
obtained) unless the measures specified below which
. describe the process according to the lnvention,are
taken. ~ .
According to a further aspect of the lnvention
there is provided a process`for the production of
filaments of polyester, preferably of polyethylene
terephthalate, which can be drawn with molecular
orientation by passing melt-spun undrawn filaments
through a water bath kept at temperatures of from
93 to 100C, the filaments being permanently plasti-
cally extended with a reduction in their molecular
orientation, wherein the filaments spun at a take-off
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rate of no more than 2500 metres per minute and pre-
ferably at a take-off rate of from 1000 to 2100 metres
per minute are extended in a ratio of at least 1:3.0
and preferably in a ratio of at least 1:5.0 to an
individual denier of less than 2.5 dtex and preferably
to an individual denier of from 2.0 to 0.2 dtex.
The above-mentioned spinning take-off rates are
critical. The upper limit indicated should not be
exceeded because otherwise excessive orientation would
occur which would result in a-lower crystallisation
.
temperature so that, at temperatures in the above-
mentioned range from 70 to 100C, there would be danger
of crystallisation which would run contrary to the
required disorientation. In the elongation of the
filaments provided in àccordance with the lnvention,
crystallisation and orientation are closely related to
one another. The higher the temperature, the gréater
the disorientation rate in relation to the further
orientation which ocours during elongation. For this
reason, the filaments are preferably extended in a
water bath at temperatures of from 96 to 99C. On the
other hand, the temperature should not be too high
because otherwise crystallisation would occur.
The filaments are preferably subjected to mole-
oule-orienting dr-wing lmmediatelv after elon,ation.
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In this case, it is particularly important to ensure
that the temperature of the filaments entering the
drawing zone from the elonga-tion zone is kept at
around 70C in order to obtain neck-free drawing.
Drawing may readily be carried out in a single stage.
The drawing rate should preferably amount to
between 80 and 200 metres per minute.
~ In thls connection, it is also preferred to
draw the filaments to an individual denier of less than
0.5 dte~ and preferably to an individual denier of less
than 0.3 dtex.
- These filaments are particularly suitable for the
production of filament yarns, fibre-yarn-like filament
yarns or, after conversion into staple fibres, for
the production of fibre yarns.
Fo~ producing staple fibres intended for the
production of non-wovens, the filaments are preferably
flrst drawn to an individual denier of from 0.ll5 to
0.3 dtex, subsequently crimped and converted into
fibres.
For producing binding fibres-for non-woven fabrios,
the filaments are crimped and converted into fibres
immediately after elongation.
The process is preferably carried out by running
the filaments into the water bath with a denier density
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of at least 50,000 dtex cm of entry width.
For numerous app-lications, the filaments may have
a cross-section differing from the circular form.
For the produotion of non-wovens, it is preferred to
use filaments or fibres ob~ained therefrom which have
a rectangular cross-section with a ratio of the longer
side to the shorter side of from 1.5:1 to 5:1.
The invention also relates to the use of the
filaments according to the invention which can be
drawn with molecular orientation for the production
of filaments drawn with molecular orientation having
an individual denier of less than 0.5 dtex and pre-
ferably less than 0.3 dtex.
The invention also relates -to the use of corres-
ponding fibres in conjunction with fibres drawn withmolecular orientation for the production of bulky
mixed-fibre yarns.
Finally, the invention relates to the use of
fibres according to the invention in conjunction with
fibres drawn with molecular-orientation for the pro-
duction of a non-woven fabric.
The lnvention is described in more de-tail in the
following with reference to the accompanying drawing.
Filamcnts run off from a spinning nozzle at a
rate of no more than 2500 metres per minute and in the
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form of bobbins 1, but preferably in the form of tows
2 in cans 3, are subjected to the process according
to the invention. In the case of tows 2 in cans 3,
the first roller system 4 (in this case in the form
of a duo) is preferably covered with a denier density
of at least 50,000 dtex per cm of entry width. The
filaments are.drawn through a water bath 6 over guide
rollers 7 to 10 by a second roller system 5 (in this
case in the form of a qinitet). The water has a
.10 temperature in the range from 93 to 100C and preferably
in the range from 96 to 99~C. The higher the tem-
perature, the more quickly the filaments are heated,
the flatter their SS-curve and the more quickly
draLting is completed (the filaments may be drafted
to 15 or 20 times their original length, as known
~_r se) On account of the very low degree of crys-
tallisation of the starting material, disorientation
still takes place in the above mentioned temperature
range, occurring more quickly than the elongation-
induce.d orientation.on account of the relatively slow
elongation. Accordingly, the level of orientation
and, as a measure thereof, the double refractlon of
the filaments decrease. The rollers of the second
roller system 5 are preferably operated at a surface
speed of up to about 50 metres per minute, whilst the
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rollers of the first roller sytem 4 are operated at a
- surface speed of from about 3.5 to 15 metres per minute.
The residence time of the filaments in the water bath
6,is generally less than 1 minute, a residence time
of less than 20 seconds being su~ficient in most
cases. The drafting of the filaments (diameter re-
duction) generally begins about 15 to 40 cm behind
the-point of entry.
After leaving the second roller system 5, the
filaments should have a double refraction which is
lower than it was before entry into the first roller
system 4. It amounts to between about 0.004 and
about 0.012. In addition, the filaments have an
individual denier of less than 2.5 dtex and preferably
from 2.0 to 0.2 dtex. The filaments are still capable
of being drawn with full molecular orientation and
have substantially the same low crystallinity as the
starting filaments.
Filaments with these properties may be run off
from one of the rollers of the roller system 5 and
delivered to-a further processing stage "Wl" where
the filaments are crimped in a stuffer box and sub-
sequently converted into staple fibres.' By virtue
of their relatively low melting and'softening tem-
perature, the crimped, undrawn fibres,are eminently
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suitable for use as binding fibres -for the production
o-f non-wovens and, by virtue o-f their high shrinkage
capacity, for the production of bulky fibre mïxed yarns.
However, the extended filaments may also be con-
tinuously delivered -from the second roller system 5
to a third roller system 11 (in this case in the form
of a quintet) which operates at a speed of 80 to 200
metres per minute and subjects the filaments to molecule-
orienting drawing. As a result of this treatment, the
filaments acqulre normal textile properties (elongatlon,
strength, shrinkage), but unusually low individual
deniers of less than 0.5 dtex and preferably less than
0.3 dtex, Individual deniers of less than 0.1 dtex
can be obtained without di-fficulty. The filaments are
then delivered to a further process1ng stage "W2"
where they may either be crimped in a stuffer box and
converted into staple fibres, as in "Wl", or simply
wound into packages or otherwise textured and subseq~ently
- wound into packages, the texturing treatment comprising
2Q for example the formation of loops and proj-ecting fibre
ends (production of fibre-yarn-like yarn).
EXAM~'LE
.
A tow 300,Q00 dtex thick of polyethylene tere-
phthalate filaments w~ic-h have been spun at a rate of
2~ 1300 metres per mi~nute and whlch have a double refraction
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of 0.0090 and individual denier of 6 . 5 dtex, is
delivered from cans to a first roller system consisting
of three rollers driven at a peripheral speed of 5 . 5
metres per minute. The filaments are passed through
5 a 2 ~ 5 metres long water bath kept at a temperature of
97C. They are run off by a second roller system at
38 . 5 metres per minute and are permanently extended
in the water bath with a reductio~ in their degree
of orientation. The filaments now have a double re-
fraction of only 0.0080, their individual denier
having been reduced to 0.8 dtex. The filaments have
a strength of approximately 10 cN/tex and,an elongation
of 280%. As filaments or staple fibres, they are
suitable for use as binding fibres for non-woven
, 15 fabrics.
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" E~MPLE 2
A tow corresponding to ~xample 1 is extended
, between the first and second rolle,r systems as des-
cribed in that Example. The filaments are then
deIivered with a temperature of about 75 to 85C to
a continuously adjoining drawing zone from which they
are run off by a third roller system at 100 metres per
, minute. The filament now have a denler of~0.45 dtex,
- , a strength of 40 cN/tex, an elongation of 25% and a
25 shrinkage in hot air at 190C of 8%. The filaments
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are suitable for the productlon of very fine fibre
yarns (for example havlng a count of 160).
EXAMPLE 3
A tow 1750 dtex thick of polyethylene tere-
, phthalate fila~ments, which have been spun at a rate
of 1000 metres per minute and which have a double
refraction of 0.0078 and an individual denier of 7.5
dtex, is delivered from cans to a!first roller system
consi'sting of three rol,lers driven at a peripheral
,10 speed of 5 metres per minute. The filaments are
passed through a 2.5 metres long water bath kept at a
temperature of 98C. They'are run off by a second
roller system at 35 metres per minute and are per-
manently extended in the water bath with a reduction
in their degree of orientation. The filaments now
have a double refraction o~f only 0.0068, their in-
dividual denier having been reduced to 1.1 dtex. The
filaments are delivered with a temperature of about
, 75 to 85C to the continuously adjoining drawing zone '
- 20 from which they run off by a third roller system at ~ '
- 87.5 metres per minute. The filaments,now have a'
'denier of approximately 0.4 dtex, a strength of 35
c~/tex, an elongation of approximatèly 30% and a
shrinkage ln hot air at 190C of approximately 10%.
The filaments,are sultab~le'for the production of special
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plush fab~ics.
- EXAMPLE 4
A tow of polyethylene terephthalate filaments with
an individual denier of 6.7 dtex spun at a rate of 1365
metres per.minute is permanently.extended between the
first two rollers systems in a 2.5 metres long water
bath kept at 97C. The second roller system operates
at 38.5 metres per min~te. The filaments are then
continuously delivered to the third roller system
operating at 100 metres per minute where they are
subjected to molecule-orienting drawing in a ratio of
1:2.6. The properties (individual denier, strength,
elongation) of the extended filaments obtained with
different extenslon ratios and orthe subsequently
drawn filaments are shown in Table 1.
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TABLE 1
Example Extension Extended filaments
No ratio
. Individual Strength Elongation
denier dtex c/Ntex %
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4a 1 : 3 1.93 9.3 264 .
4b 1 : 4 1.60 9.3 245 .
4c 1 : 5 1.20 10.7 234
4d 1 : 6 0,97 ! 10.8 214
4e 1 : 7 0.88 9.9 212
/If 1 : 8 10.78 9.9 214
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TABLE 1 (Continued)
No l Drawn filaments (1:2.6)
. ¦ Individual Strength Elongation
¦ denier dtex c/Ntex %
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4a 0.77 30.2 44
4b 0.60 32.8 33
4c 0,46 33.1 29
4d 0.40 32.3 22
4e 0.38 29.7 21
4f 0.37 29.9 18
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EXAMPLE 5
This Example is intended to demonstrate the in-
fluence of the temperature of` the,water bath. The
filaments extended were spun at a rate of 2000 metres
5 per minute (degree of crystallisation 6. 7%~ double
refraction 0.0147),
a) Water bath temperature 85C
TAB LE II
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Extension Double Degree of
ratio refraction crystallisation .
,
. ~ 1: 1,5 0.0148 4.8
' . , 1: 2.0 0,0325 .9.3
1 : 2.5 0.1520 29.8
1: 3.0 ' 0.170 3.5' .
1: 3.5 ' 0.176 . 3.5
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Table II shows that, even with minimal extension,
the double,refraction increases with a rapid increase
20 in the degree OI crystallisatlon.
b) Water bath temperature 90C
TABLE III
Extension- Double Degree of
. ratio refract'ion, crystallisation
' 1: 1,5 ' 0.0114 - 4,9
1: 2.0 0.0156 ' 5.7
1: 2.5 0.0180 5.2 .
1: 3.0 0.169 ' 30.8 .
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Table III shows that, at a water bath temperature
of 90C and with minimal extension ratios, the double
refraction decreases slightly but, in the technically
interesting range, increases considerably in the same
way as the degree of crystallisation, so that molecule-
orienting drawing after elongation is only possible
to a minimal extent.
c) Water bath temperature 97C !
: TABLE IV
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Extension Double Degree of
ratio refractlon crystallisation
1 : 1,5 0.0068 4.0
. 1 : 2.0 0.0062 1.4
1 : 2.5 0.0085 2.4
. 1 : 3.0 0.0075 . 3.6
. 1 : 3.5 0.0075 3.6
1 : 4.0 o.oo69 4.5
. 1 : 4.5 0.0073 4.5
1 : 5.0 0.0074 4.8
1 : 5.5 ~0.0088 4.0
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Table IV shows that, in the temperature range
according tQ the invention, an extension o-f more than
1:3.) is possible with a reduction in double refraction
and degree of crystallisation.
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EXAMPLE 6
In order to demonstrate the critical significance
of the spinning rate, a tow of -filaments spun at 2500
metres per minute lS first extended. The starting
material has a double refraction of 0,0224 and a degree
o-f crystallisation of 7.5%. The results are set out
in Table V. It can be seen that filaments which have
been spun at 2500 metres per minute can only be extended
in a ratio of 1:1.5 without significant molecular
orlentation occurring. Extension in a ratio of only
1:2.0 is su-fflcien-t to produce a considerable increase
in double refraction and degree of crystallisation.
In this case, it lS no longer a question of extension,
but rater of drawing.
.
An attempt to extend a bundle of filaments spun at
3500 metres per minute without orientation was un-
successful. Molecule-orie~ting drawing was always
observed.
TABLE V
Example Water Extension Double Degree of
No. bath ratio refrac- crystalli-
tempera- tion sation
ture C ~ %
6a 85~ 1:1.5 0.0214 8.1
6b 85C 1:2.0 0.1384 29.2
6c 90C 1:1.5 0.0242 7.8
6d 90C 1:2.0 0.1349 31.2
6e 97C 1:1,5 0,0131 8.6
6f 97C 1:2.0 0.1331 33.8
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