U.S. patent application number 14/421314 was filed with the patent office on 2015-08-06 for melt-spinning process and melt-spinning apparatus for producing a crimped yarn.
The applicant listed for this patent is Oerlikon Textile GmbH & Co. KG. Invention is credited to Friedrich Lennemann, Kirsten Prehn, Mathias Stundl.
Application Number | 20150218733 14/421314 |
Document ID | / |
Family ID | 48949143 |
Filed Date | 2015-08-06 |
United States Patent
Application |
20150218733 |
Kind Code |
A1 |
Stundl; Mathias ; et
al. |
August 6, 2015 |
MELT-SPINNING PROCESS AND MELT-SPINNING APPARATUS FOR PRODUCING A
CRIMPED YARN
Abstract
A melt-spinning process and a melt-spinning apparatus produce a
crimped yarn. By means of a spinning device, a filament bundle is
generated from a thermoplastic polymer, is drawn after cooling and
is compressed into a yarn plug in a stuffing chamber. The yarn plug
is opened up into a crimped yarn and wound into a bobbin. In order
to obtain as high a crimp resistance of the yarn as possible,
amorphous fractions in the molecular structure of the yarn material
are avoided after drawing. This is achieved by means of relaxation
treatment after drawing and before compression, a minimum yarn pull
force of >0.05 cN/dtex with a relaxation temperature in the
range of 120.degree. C. to 245.degree. C. being maintained.
Inventors: |
Stundl; Mathias; (Wedel,
DE) ; Lennemann; Friedrich; (Neumunster, DE) ;
Prehn; Kirsten; (Norderstedt, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Oerlikon Textile GmbH & Co. KG |
Remscheid |
|
DE |
|
|
Family ID: |
48949143 |
Appl. No.: |
14/421314 |
Filed: |
August 8, 2013 |
PCT Filed: |
August 8, 2013 |
PCT NO: |
PCT/EP2013/066607 |
371 Date: |
February 12, 2015 |
Current U.S.
Class: |
428/369 ;
264/103; 425/66 |
Current CPC
Class: |
D01D 5/22 20130101; D02G
1/168 20130101; Y10T 428/2922 20150115; D02J 1/22 20130101; D01D
10/02 20130101; D02G 1/12 20130101; D02J 13/005 20130101; D02G 3/22
20130101; D02G 1/127 20130101 |
International
Class: |
D02G 1/12 20060101
D02G001/12; D02G 3/22 20060101 D02G003/22 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 17, 2012 |
DE |
10 2012 016 368.1 |
Oct 27, 2012 |
DE |
10 2012 021 142.2 |
Claims
1. A melt-spinning process for producing a crimped yarn, in which
at least one filament bundle is generated from a thermoplastic
polymer by the spinning of a plurality of filaments, in which the
filament bundle is drawn after cooling and is compressed into a
yarn plug in a stuffing chamber, and in which the yarn plug is
opened up into a crimped yarn and wound into a bobbin, wherein,
after drawing and before compression, the filament bundle undergoes
relaxation treatment at a relaxation temperature in the range of
120.degree. C. to 245.degree. C. and with a minimum yarn pull force
of >0.05 cN/dtex.
2. The process as claimed in claim 1, wherein, during relaxation
treatment, the yarn pull force acting on the filament bundle lies
in the range of 0.1 cN/dtex to 2.0 cN/dtex, preferably in the range
of 0.2 cN/dtex to 0.7 cN/dtex.
3. The process as claimed in claim 1, wherein, for relaxation
treatment, the filament bundle is guided in a plurality of loopings
on a godet pair with heated godets and with conical godet
casings.
4. The process as claimed in claim 1, wherein, after relaxation
treatment, the filament bundle undergoes fixing treatment at a
fixing temperature in the range of 60.degree. C. to 240.degree. C.,
with a minimum yarn pull force of >0.05 cN/dtex being
maintained.
5. The process as claimed in claim 4, wherein, for fixing
treatment, the filament bundle is guided in a plurality of loopings
on a godet pair with cold godets.
6. The process as claimed in claim 1, wherein, before compression,
the filament bundle undergoes heat treatment at a treatment
temperature lying below the relaxation temperature, with a minimum
yarn pull force of >0.05 cN/dtex being maintained.
7. The process as claimed in claim 6, wherein, for the heat
treatment, the filament bundle is guided in a plurality of loopings
on a godet pair with heated godets.
8. The process as claimed in claim 1, wherein, for the compression,
the filament bundle is conveyed into the stuffing chamber by an air
stream of hot air or cold air.
9. A melt-spinning apparatus for producing a crimped yarn, with a
melt-spinning device, with a cooling device, with a drawing device,
with a crimping device and with a winding device, the drawing
device having a take-up godet pair with at least one heated godet
and a drawing godet pair with two heated godets, wherein
charactcrizcd in that the heated godets, of the drawing godet pair
have in each case a stepped or conical godet casing, by means of
which relaxation treatment can be carried out on a filament bundle
guided in a plurality of loopings, with a minimum yarn tension of
>0.05 cN/dtex and a relaxation temperature in the range of
120.degree. C. to 245.degree. C.
10. The apparatus as claimed in claim 9, wherein, between the
drawing device and the crimping device, at least one further godet
pair is arranged, by means of which fixing treatment or heat
treatment can be carried out on a filament bundle guided in a
plurality of loopings.
11. The apparatus as claimed in claim 9, wherein, between the
drawing device and the crimping device a plurality of godet pairs
are arranged, by means of which fixing treatment and heat treatment
can be carried out on a filament bundle guided in a plurality of
loopings.
12. The apparatus as claimed in claim 9, wherein the crimping
device has a conveying nozzle and a stuffing chamber arranged on
the outlet side of the conveying nozzle.
13. The apparatus as claimed in claim 12, wherein crimping device
has a cooling drum for cooling a yarn plug guided out of the
stuffing chamber.
14. A crimped yarn which is made from a thermoplastic polymer and
which is produced by means of a single-stage melt-spinning process
as claimed in claim 1.
Description
[0001] The invention relates to a melt-spinning process for
producing a crimped yarn, according to the preamble of claim 1, and
to a melt-spinning apparatus for producing a crimped yarn,
according to the preamble of claim 9.
[0002] A generic process and a generic apparatus are known from WO
2011/138 302 A1.
[0003] In the production of crimped yarns, preferably used for
producing carpets, in a melt-spinning process, all the treatment
steps for generating the desired physical properties of the yarn
usually take place in succession. Thus, first, a multiplicity of
filaments are extruded out of a melt of a polymer and, after
cooling, are brought together as a filament bundle, prepared and
drawn. After the drawing of the filament bundle, compression of the
filament bundle takes place inside a stuffing chamber, so that the
individual filaments are deposited in the form of arcs and loops
within a yarn plug. The yarn plug is subsequently opened up into a
yarn, the loops and arcs of the filaments not breaking down
completely and giving the yarn a crimped structure. Depending on
the respective polymer, the individual treatment steps are carried
out under the influence of heat, particularly in order to influence
the crystal morphology of the yarn material in the desired way.
Thus, for example, a high crimp resistance of the yarn is desired.
Crimp resistance is the ability of the yarn to preserve the
existing crimping under mechanical load. Thus, low crimp resistance
causes a large part of the loops and arcs preserved in the
filaments to break down after being subjected to mechanical
load.
[0004] In the known melt-spinning process and the known
melt-spinning apparatus, the filament bundle is heated before
drawing and after drawing, so that an oriented molecular structure
can be formed within the yarn material. However, the heat treatment
of the filament bundle which is carried out after drawing has the
effect that uncontrolled expansion acts upon the filaments, causing
partial restitution into non-oriented and amorphous fractions of
the polymer material. However, such non-crystalline molecular
structures in the yarn material have the disadvantage of very low
crimp resistance.
[0005] In principle, it is known from the two-stage process for the
production of textured and crimped yarns that these yarns have high
crimp resistance. In this case, the crimping and drawing of the
yarn take place in a superposed treatment step, and therefore
attempts have also been made to apply this technique to the
single-stage melt-spinning processes. Thus, for example, DE 199 20
177 A1 discloses a process and an apparatus for producing a crimped
yarn, in which a conventional false-twist zone with a heating
device, with a cooling device and with a false-twist assembly is
arranged between a plurality of godet pairs. Consequently, although
similar effects to a two-stage process can be simulated, there is
the nevertheless the disadvantage that, at higher process speeds,
the generation of twist on the filament bundle leads to
considerable problems. The known process and the known apparatus
have therefore not proved successful in the production of carpet
yarns.
[0006] Furthermore, a process for producing a crimped yarn from a
polytrimethylene terephthalate (PTT) is known from DE 10 2008 051
738 A1. In this, the filament bundle does not undergo heat
treatment immediately before entry into the crimping chamber. Where
conventional polyester materials are concerned, however, the
unavoidable result of the absence of heat treatment is that the
internal stresses which have occurred during drawing may not take
effect until crimping takes place. To that extent, the PTT material
is in a separate position with a special molecular structure.
[0007] The object of the invention, therefore, is to develop a
melt-spinning process and a melt-spinning apparatus of the generic
type for producing a crimped yarn, in such a way that crimped yarns
can be produced with improved crimp resistance from conventional
polymer materials, such as, for example, PET.
[0008] This object is achieved, according to the invention, for the
melt-spinning process in that, after drawing and before
compression, the filament bundle undergoes relaxation treatment at
a relaxation temperature in the range of 120.degree. C. to
245.degree. C. and with a minimum yarn pull force of >0.05
cN/dtex.
[0009] The melt-spinning apparatus according to the invention
offers the solution whereby the heated godets of the drawing godet
pair have in each case a stepped or conical godet casing, by means
of which relaxation treatment can be carried out on a filament
bundle guided in a plurality of looping movements, with a minimum
yarn tension of >0.05 cN/dtex and a relaxation temperature in
the range of 120.degree. C. to 245.degree. C.
[0010] Advantageous developments of the invention are defined by
the features and feature combinations of the respective
subclaims.
[0011] The invention is based on the recognition that, in the
conventional melt-spinning processes of the generic type, a
complete collapse of yarn tension on the filament bundle occurs
during the transition of the filament bundle from the drawing godet
pair to the crimping device. Tension breakdowns of this kind on the
filament bundle have the direct result that, during expansion, the
yarn material is restructured into a state which is favorable in
energy terms, so that amorphous and semi-amorphous fractions occur
to an increased extent in the molecular structure. Such an absence
of crystallinity is therefore conducive to a lack of crimp
resistance. In the melt-spinning process according to the invention
and the melt-spinning apparatus according to the invention,
relaxation treatment is carried out on the filament bundle before
entry into the crimping device and ensures a minimum yarn pull
force of >0.05 cN/dtex. In this case, depending on the type of
polymer, the relaxation temperatures lie in the range of between
120.degree. C. and 245.degree. C.
[0012] The melt-spinning apparatus according to the invention
affords the great advantage, in particular, that relaxation
treatment with a minimum yarn pull force can be carried out
directly at the drawing godet pair. For this purpose, the godet
casings of the godets of the drawing godet pair have a conical or
stepped shape, so that a minimum yarn pull force is maintained each
time the filament bundle is wound around on the circumference of
the godet casings. Consequently, it is possible to heat the yarn
material, in the tensioned state of the filament bundle, to the
relaxation temperature in the range of between 120.degree. C. and
245.degree. C. Depending on the number of loopings around the godet
casings, on the yarn speed and on the overall yarn titer of the
filament bundle, the set surface temperature of the godet casings
lies somewhat higher than the relaxation temperature. The
temperatures at the godet surface are usually set at approximately
5.degree. C. to 15.degree. C. above the desired yarn
temperatures.
[0013] In order to obtain sufficient expansion in spite of the yarn
pull force acting on the filament bundle, an especially
advantageous process variant is one in which, during relaxation
treatment, the yarn pull force acting on the filament bundle lies
in the range of 0.1 cN/dtex to 2.0 cN/dtex, preferably in the range
of 0.2 cN/dtex to 0.7 cN/dtex. The desired expansion effects for
reducing internal stresses on the filaments of the filament bundle
can consequently be implemented.
[0014] In the melt-spinning process according to the invention, the
relaxation treatment of the filament bundle immediately before
compression can be carried out by means of all known devices for
the generation of minimum yarn pull forces and for the heat
treatment of the yarn. Especially advantageous, however, is the
process variant in which, for relaxation treatment, the filament
bundle is guided in a plurality of looping movements around a godet
pair having heated godets and conical godet casings. The conicity
of the godet casings ensures that, in the case of a plurality of
windings of the filament bundle, a defined yarn pull force prevails
during the heating of the yarn material.
[0015] It turned out to be especially advantageous that the
transformation of the molecular structure of the yarn material
during relaxation can also be stabilized by means of subsequent
fixing treatment. In that regard, the process variant is preferably
used in which the filament bundle, after relaxation treatment,
undergoes fixing treatment with a fixing temperature in the range
of 60.degree. C. to 240.degree. C., with a minimum yarn pull force
of >0.05 cN/dtex being maintained. This operation is preferably
achieved by guiding the filament bundle on cold godets of a godet
pair. In principle, the fixing temperature should lie at least
5.degree. C. below the relaxation temperature.
[0016] Depending on the type of polymer of the yarn material,
alternatively or additionally, further heat treatment is carried
out on the filament bundle immediately before compression. It is
therefore necessary that the filaments as far as possible have
ductility in order to be laid down in arcs and loops. For this
purpose, the process variant is especially suitable in which,
before compression, the filament bundle undergoes heat treatment at
a temperature lying below the relaxation temperature, with a
minimum yarn pull force of >0.05 cN/dtex being maintained. The
treatment temperature should lie in the range of between 5 and
100.degree. C. below the relaxation temperature previously set in
each case. This ensures that undesirable restructurings in the
molecular structure of the yarn material cannot occur.
[0017] This method step, too, is preferably carried out by means of
heated godets of a godet pair on which the filament bundle is
guided in the plurality of looping movements for heat
treatment.
[0018] In order to assist the temperature control operation during
the crimping of the filament bundle, for compression the filament
bundle is preferably conveyed into the stuffing chamber by a hot
air stream. Depending on the yarn material, however, there is also
the possibility of guiding the filament bundle with a cold air
stream.
[0019] In the melt-spinning apparatus according to the invention,
flexibility for carrying out the melt-spinning process according to
the invention is increased in that, according to an advantageous
development, one or more godet pairs are arranged between the
drawing device and the crimping device. Thus, in the case of an
additional godet pair between the drawing device and the crimping
device, fixing treatment or heat treatment can selectively be
carried out on a filament bundle guided in a plurality of looping
movements. For fixing treatment, the godet pair preferably has cold
godets. By contrast, heat treatment is carried out by means of a
heated godet pair.
[0020] In the event that the yarn material used in each case
requires fixing treatment and heat treatment of the filament bundle
before compression, the development of the melt-spinning apparatus
according to the invention is provided in which a plurality of
godet pairs are arranged between the drawing device and the
crimping device. The fixing treatment and heat treatment can thus
be carried out in succession.
[0021] To compress the filament bundle, the crimping device is
preferably designed with a conveying nozzle which cooperates on the
outlet side with a stuffing chamber. Such crimping devices have
proved successful, particularly in the case of high process speeds,
in order to generate continuous and uniform crimping of the
filament bundle.
[0022] In order to fix the arcs and loops, generated under the
influence of temperature, of the filaments, the yarn plug is
preferably guided on the circumference of a cooling drum for
cooling.
[0023] The melt-spinning process according to the invention and the
melt-spinning apparatus according to the invention are suitable for
producing crimped yarns in a single-stage process with high crimp
resistance which can otherwise be achieved on yarns solely in a
two-stage process.
[0024] The melt-spinning process according to the invention is
explained in more detail below by means of some exemplary
embodiments of the melt-spinning apparatus according to the
invention, with reference to the accompanying figures in which:
[0025] FIG. 1 illustrates diagrammatically a view of a first
exemplary embodiment of the melt-spinning apparatus according to
the invention
[0026] FIG. 2 illustrates diagrammatically a view of a further
exemplary embodiment of the melt-spinning apparatus according to
the invention
[0027] FIG. 3 illustrates diagrammatically a view of a further
exemplary embodiment of the melt-spinning apparatus according to
the invention
[0028] FIG. 4 illustrates diagrammatically a view of a further
exemplary embodiment of the melt-spinning apparatus according to
the invention.
[0029] FIG. 1 illustrates diagrammatically a view of a first
exemplary embodiment of the melt-spinning apparatus according to
the invention for producing a crimped yarn. The exemplary
embodiment of the melt-spinning apparatus according to the
invention is shown by the example of one thread run, although such
melt-spinning apparatuses are also used for producing a plurality
of yarns next to one another in parallel.
[0030] The exemplary embodiment shown in FIG. 1 has a spinning
device 1, a cooling device 5, a drawing device 11, a crimping
device 15, a post-treatment device 20 and a winding device 24,
which are arranged one behind the other to form a yarn run. In this
exemplary embodiment, the spinning device 1 is illustrated merely
by a spinning head 2. The spinning head 2 has at least one spinning
pump (not illustrated here) and a spinnerette 3 which on the
underside has a nozzle plate with a multiplicity of nozzle bores.
The spinnerette 3 arranged inside the heated spinning head 2 is
coupled to the spinning pump which is connected via a melt inflow 4
on the top side of the spinning head 2 to a melt source, not
illustrated here, for example an extruder.
[0031] When a plurality of yarns are being produced next to one
another in parallel, the spinning head 2, which is also designated
by specialists as a spinning beam, carries a plurality of
spinnerettes next to one another.
[0032] Underneath the spinning device 1, a cooling device 5 is
provided, which forms a cooling shaft 6 for receiving freshly
extruded filaments, the cooling shaft 6 being assigned a blowing
means 7 for generating a cooling air stream. The cooling air may in
this case be provided from the outside inward by means of
cross-flow blowing or radial blowing. In principle, however, there
is also the possibility of conducting a cooling air stream through
the filament bundle radially from the inside outward.
[0033] After cooling, the filaments 8 generated by the spinnerettes
3 are brought together into a filament bundle 10. For this purpose,
a preparation device 9 is provided underneath the cooling device 5.
The preparation device 9 usually has a collecting yarn guide and a
wetting means. Preparation pins or preparation rollers may be used
as wetting means.
[0034] Underneath the preparation device 9, a drawing device 11 is
provided, which is formed from a take-up godet pair 12 with two
heated godets 12.1 and 12.2 and from a drawing godet pair 14 with
the heated godets 14.1 and 14.2. The heated godets 12.1 and 12.2 of
the take-up godet pair 12 and the heated godets 14.1 and 14.2 of
the drawing godet pair 14 are arranged in each case in a godet box
13.
[0035] In contrast to the heated godets 12.1 and 12.2 of the
take-up godet pair 12, which have a conventional cylindrical godet
casing, the heated godets 14.1 and 14.2 of the drawing godet pair
14 are designed in each case with a conical godet casing. The
conicity of the godet casings on the heated godets 14.1 and 14.2 is
selected in such a way that, after the drawing of the filament
bundle 10, a minimum yarn pull force of above 0.05 cN/dtex,
preferably of 0.1 cN/dtex, acts on the filament bundle in each
wind-around.
[0036] In this exemplary embodiment, the crimping device 15 is
formed by a conveying nozzle 16 and a stuffing chamber 17 arranged
on the outlet side of the conveying nozzle 16, said conveying
nozzle and said stuffing chamber cooperating with a following
cooling drum 19. The conveying nozzle 16 is coupled to a compressed
air source in order to convey the filament bundle 10 by means of an
air stream into the stuffing chamber 17 and compress it into a yarn
plug. The yarn plug 18 is cooled on the circumference of the
cooling drum 19 by cooling air.
[0037] The crimping device 15 is followed by a post-treatment
device 20 which, on the one hand, opens up the yarn plug 18 by
taking up a crimped yarn on the circumference of the cooling drum
19 and, on the other hand, carries out an intermingling of the yarn
in order to increase the yarn strength. For this purpose, an
intermingling nozzle 22 is arranged between two guide godet units
23.1 and 23.2. Each of the guide godet units 23.1 and 23.2 has a
godet and an auxiliary roller.
[0038] At the end, the crimped yarn 21 is wound up into a bobbin 25
by means of the winding device 24. For this purpose, winding
devices are usually used which have a winding turret 28 with two
projecting winding spindles 29.1 and 29.2 which are guided
successively into a winding region and thus lead to a continuous
winding of the crimped yarn. Such winding devices are generally
known and therefore not described in any more detail here.
[0039] In the exemplary embodiment, illustrated in FIG. 1, of the
melt-spinning apparatus, a granulate of a polymer material, for
example a polyester, is melted, for example via an extruder, and is
fed to the spinning head 2 via the melt inflow 4. Inside the
spinning head 2, the melt is conveyed under pressure to the
spinnerette 3 by means of a spinning pump, so that a multiplicity
of filaments 8 are extruded on the underside of the spinnerette 3.
The freshly extruded filaments 8 are cooled inside the cooling
device 5 by means of a cooling air stream and are brought together
at the end into a filament bundle 10. For this purpose, the
filaments 8 undergo wetting which is preferably an oil/water
emulsion.
[0040] The filament bundle 10 is pulled out of the spinning device
1 by the take-up godet pair 12. The godets 12.1 and 12.2 of the
take-up godet pair 12 have a surface temperature at the godet
casings in order to heat the yarn material to a desired yarn
temperature in the range of 80.degree. C. to 120.degree. C. In this
case, the filament bundle is guided on the take-up godet pair 12 in
10 to 15 looping movements.
[0041] For drawing the filament bundle 10, the drawing godet pair
14 is driven with a speed difference, so that the filament bundle
10 is drawn in the yarn section between the take-up godet pair 12
and the drawing godet pair 13.
[0042] So that relaxation treatment can be carried out on the
filament bundle 10 immediately after drawing, the godets 14.1 and
14.2 of the drawing godet pair 14 are heated in such a way that a
yarn temperature on the filament bundle in the range of 120 to
245.degree. C., preferably of 170 to 230.degree. C., is reached. In
order to compensate the length changes occurring during the heating
of the yarn material, the two godet casings of the godets 14.1 and
14.2 may be designed to be slightly conical. The variation in the
guide diameter of the godet casings of the godets 14.1 and 14.2 is
selected as a function of the 8 to 12 loopings of the filament
bundle, in such a way that at least one yarn pull force of 0.05
cN/dtex, preferably of 0.1 cN/dtex, acts in each looping. The
diameter variation of the godet casings in the godets 14.1 and 14.2
is dimensioned in such a way that a maximum yarn pull force of 2.0
cN/dtex is not exceeded. It was shown that advantageous relaxation
treatment is possible in a range of 0.2 to 0.7 cN/dtex. The
relaxation temperature of yarn treatment, which is determined by
the surface temperature of the godet casings of the godets 14.1 and
14.2, is set at a temperature of between 120.degree. C. and
245.degree. C. Relaxation treatment on the filament bundle 10 leads
to uniform restructuring of the molecular structure without major
fractions of amorphous or semi-amorphous regions. The high
crystallinity of the yarn material ensures a stable crimping
behavior with correspondingly high crimp resistance in the crimped
yarn.
[0043] For crimping, the filament bundle 10 is conveyed through the
conveying nozzle 16 into the stuffing chamber 17 and is compressed
into a yarn plug. Depending on the temperature of relaxation
treatment, the conveyance of the filament bundle may take place by
means of a hot air stream or by means of a cold air stream. The
crimped filaments of the filament bundle 10 are conveyed as a yarn
plug 18 out of the stuffing chamber 17 and cooled on the
circumference of the cooling drum 19. The opening up of the yarn
plug 18 into the crimped yarn 21 takes place by means of the
post-treatment device 20 which has a first guide godet unit 23.1.
Further along, the crimped yarn 21 is intermingled in the
intermingling nozzle 22 and is subsequently guided via the second
guide godet unit 23.2 to the winding device 24. In the winding
device 24, the crimped yarn 21 is wound into the bobbin 25.
[0044] The exemplary embodiment, illustrated in FIG. 1, of the
melt-spinning apparatus according to the invention thus makes it
possible to carry out the melt-spinning process according to the
invention, the filament bundle running into the crimping device
under the temperature control stipulated by the relaxation
treatment. As already mentioned above, there is in this case the
possibility of guiding the filament bundle 10 into the stuffing
chamber 17 by means of a cold air stream. Consequently, in
particular, the effects of the relaxation treatment can be fixed in
the yarn material. In order nevertheless to obtain a pronounced
crimping of the filament bundle, the yarn plug is preferably heated
inside the stuffing chamber.
[0045] In order to obtain a temperature control of the filament
bundle which is especially suitable for the crimping operation, in
the apparatus and process illustrated in FIG. 1 the conveying
nozzle 16 is alternatively operated by means of a hot air stream.
In this case, however, only limited temperature changes of the yarn
material can be achieved.
[0046] So that the relaxation of the filament bundle and the
compression of the filament bundle can be set independently of one
another, the exemplary embodiment of the melt-spinning apparatus
according to the invention, as shown in FIG. 2, is especially
suitable. The exemplary embodiment, illustrated in FIG. 2, of the
melt-spinning apparatus according to the invention is essentially
identical in set-up to the abovementioned exemplary embodiment
according to FIG. 1, and therefore only the differences are
explained at this juncture in order to avoid repetition.
[0047] In the exemplary embodiment, illustrated in FIG. 2, of the
melt-spinning apparatus according to the invention, the spinning
device 1, the drawing device 11, the crimping device 15, the
post-treatment device 20 and the winding device 24 are designed
identically to the exemplary embodiment according to FIG. 1.
Reference may be made in that respect to the abovementioned
description.
[0048] A further godet pair is provided between the drawing device
11 and the crimping device 15 and is designated in this case as a
temperature control godet pair 27. The temperature control godet
pair 27 has two heated godets 27.1 and 27.2 with cylindrical godet
casings. The godets 27.1 and 27.2 are arranged in a godet box 13.
For the temperature control of the filament bundle 10, the latter
is likewise guided on the circumference of the godet casings of the
godets 27.1 and 27.2 in a plurality of loopings, preferably 10 to
15 loopings.
[0049] By means of the exemplary embodiment, illustrated in FIG. 2,
of the apparatus according to the invention, a variant of the
process according to the invention can be operated in which, after
the relaxation of the filament bundle, additional heat treatment
takes place before the compression of the filament bundle. The
godets 27.1 and 27.2 of the temperature control godet pair 27 are
set at a treatment temperature which lies below the relaxation
temperature. The selected difference must be between 5.degree. C.
and 100.degree. C., depending on the type of polymer. It is
essential in this case that the relaxation temperature set during
relaxation is not exceeded. If the relaxation temperature is
exceeded during subsequent heat treatment, there is the risk that
renewed restructuring of the molecular structure of the yarn
material commences. As a result of the heat treatment of the
filament bundle immediately before compression, the production of
the crimping can be carried out independently of the relaxation
treatment. Thus, by means of the heat treatment, targeted
temperature control can be carried out on the yarn material of the
filament bundle, in order to obtain a uniform and intensive
formation of filament loops.
[0050] In the selection of the treatment temperatures, however,
care must be taken to ensure that the differences between the
treatment temperature and the relaxation temperature are not too
small, so that no fixing effects for the stability of the
restructured molecular structure of the yarn material can occur. In
order to fix the molecular structures of the yarn material which
are generated after drawing and relaxation, the exemplary
embodiment of the melt-spinning apparatus according to the
invention, as shown in FIG. 3, has proved especially
appropriate.
[0051] In the exemplary embodiment according to FIG. 3, two godet
pairs are provided between the drawing device 11 and the crimping
device 15. A first godet pair directly on the outlet side of the
drawing device 11 is designated as a fixing godet pair 26. The
fixing godet pair 26 has the godets 26.1 and 26.2, the godet
casings of which are unheated. In this exemplary embodiment, the
following godet pair is likewise a temperature control godet pair
27 with the heated godets 27.1 and 27.2. As compared with the
exemplary embodiment according to FIG. 2, a further process step is
provided between the relaxation and compression of the filament
bundle. Thus, the fixing godet pair 26 with the cold godets 26.1
and 26.2 is used in order to cool the yarn material of the filament
bundle 10. The surface temperatures of the godet casings of the
godets 26.1 and 26.2 are set for this purpose at a yarn temperature
of between 60 and 240.degree. C. The material structure of the yarn
material can consequently be fixed advantageously before
compression.
[0052] In the additional process steps of fixing and temperature
control, described in FIG. 2 and in FIG. 3, it is essential that a
minimum yarn pull force of >0.05 cN/dtex, preferably of >0.1
cN/dtex, is maintained during the entire treatment. This ensures
that the undesirable restitutions of the molecular structure which
occur in the tension-free state are avoided. In the event that a
reduction in tension takes place in the case of a large number of
loopings of the filament bundle on the fixing godet pair 26 or the
temperature control godet pair 27, there is likewise the
possibility of designing the godets 26.1 and 26.2 of the fixing
godet pair and the godets 27.1 and 27.2 of the temperature control
godet pair 27 with a conical godet casing.
[0053] It may be mentioned expressly at this juncture that the
diameter variations on the godet casings of the godets 14.1 and
14.2 of the drawing godet pair 14 may also be achieved by means of
a different shaping of the godet casings. Thus, for example in the
case of multiple looping by a plurality of yarns, a stepped shaping
of the godet casings of the godets 14.1 and 14.2 could
advantageously be used in order to ensure a minimum pull force.
Likewise, zones of conical casing portions on the godet casings and
of cylindrical casing portions may be used alternately in order to
avoid a reduction in tension on the filaments of the filament
bundle. Since stepped and conical godet casings in godets for the
guidance of yarns are sufficiently known, a further explanation is
dispensed with at this juncture.
[0054] In the exemplary embodiments according to FIGS. 1 to 3, the
melt-spinning process according to the invention and the
melt-spinning apparatus according to the invention are illustrated
by the example of a crimped yarn which is generated from a filament
bundle. Crimped yarns of this kind are preferably produced as
single-color yarns. To generate multicolor yarns, which are
preferably used for the production of carpets, preferably a
plurality of filament bundles are generated from differently
colored polymer melt or different cross-sectional shapes, numbers
of filaments or filament titers and are combined before being wound
up into a crimped composite yarn. Such an exemplary embodiment of
the melt-spinning apparatus according to the invention is
illustrated diagrammatically in FIG. 4.
[0055] In the exemplary embodiment, shown in FIG. 4, of the
melt-spinning apparatus according to the invention, the spinning
device 1 has a spinning head 2, on the underside of which three
spinnerettes are held next to one another. Each of the spinnerettes
3 is connected to a spinning pump, not illustrated here, which is
coupled in each case to a separate extruder via a separate melt
inflow 4. The filaments 8 extruded by the spinnerettes 3 are guided
jointly through a cooling shaft 6 of the cooling device 5 and are
cooled by means of a cooling air stream.
[0056] Underneath the cooling device 5, a preparation device 9 is
provided, which for each spinnerette 3 brings together in each case
the extruded filaments to form a separate filament bundle 10. The
filament bundles 10 are subsequently taken up from the spinning
device 1 by a spinning godet unit 30 provided for each spinnerette
3 and are fed to a drawing device.
[0057] In the drawing device 11, the filament bundles 10 generated
by the three spinnerettes 3 are guided next to one another in
parallel and jointly drawn. For this purpose, the drawing device 11
has a take-up godet pair 12 and a drawing godet pair 14. The
take-up godet pair 12 is in this case formed by a heated godet 12.1
and an auxiliary roller 12.3. the drawing godet pair 14 has the
heated godets 14.1 and 14.2 which in each case possess a conical
godet casing. In that respect, the drawing godet pair 14 is
designed identically to the abovementioned exemplary embodiments
and is arranged inside a godet box 13.
[0058] Underneath the drawing device 11, a temperature control
godet pair 27 is provided, which is likewise designed identically
to the abovementioned exemplary embodiment according to FIG. 2.
[0059] The subsequent devices 15, 20 and 24 are likewise identical
to the exemplary embodiment according to FIG. 2, and therefore
reference is made at this juncture to the abovementioned
description.
[0060] In the exemplary embodiment, illustrated in FIG. 4, of the
melt-spinning apparatus according to the invention, the filament
bundles 10 are compressed jointly into a yarn plug 18 by means of
the conveying nozzle 16. Thus far, the yarn plug 18 is generated
from differently colored filament bundles and, after cooling, is
opened up into the crimped yarn. In principle, however, there is
also the possibility of compressing the differently colored
filament bundles separately in each case into a separate yarn plug
and of opening it up into a plurality of crimped yarns which are
subsequently combined into a composite yarn in the post-treatment
device 20 with the aid of the intermingling nozzle 22. In this
case, the filament bundles could also have different individual
titers and different filament cross sections and could additionally
also be formed from different polymer materials.
[0061] The process according to the invention and the apparatus
according to the invention therefore extend to crimped monocolor
yarns and to crimped multicolor yarns. It is essential in this case
that, after drawing and before compression, the filaments of the
filament bundle undergo relaxation treatment with a minimum yarn
pull force. The process according to the invention and the
apparatus according to the invention are suitable, in principle,
for all thermoplastic polymers which are used for fiber production.
However, especially good crimp resistance results can be achieved
particularly in the production of crimped polyester yarns.
LIST OF REFERENCE SYMBOLS
[0062] 1 Spinning device
[0063] 2 Spinning head
[0064] 3 Spinnerette
[0065] 4 Melt inflow
[0066] 5 Cooling device
[0067] 6 Cooling shaft
[0068] 7 Blowing means
[0069] 8 Filament
[0070] 9 Preparation device
[0071] 10 Filament bundle
[0072] 11 Drawing device
[0073] 12 Take-up godet pair
[0074] 12.1, 12.2 Heated godets
[0075] 12.3 Auxiliary roller
[0076] 13 Godet box
[0077] 14 Drawing godet pair
[0078] 14.1, 14.2 Heated godets
[0079] 15 Crimping device
[0080] 16 Conveying nozzle
[0081] 17 Stuffing chamber
[0082] 18 Yarn plug
[0083] 19 Cooling drum
[0084] 20 Post-treatment device
[0085] 21 Crimped yarn
[0086] 22 Intermingling nozzle
[0087] 23.1, 23.2 Guide godets
[0088] 24 Winding device
[0089] 25 Bobbin
[0090] 26 Fixing godet pair
[0091] 26.1, 26.2 Godets
[0092] 27 Temperature control godet pair
[0093] 27.1, 27.2 Godets
[0094] 28 Winding turret
[0095] 29.1, 29.2 Winding spindle
[0096] 30 Spinning godet unit
* * * * *