MELT-SPINNING METHOD AND MELT-SPINNING APPARATUS FOR PRODUCING A CRIMPED YARN
A melt-spinning method and a melt-spinning apparatus produce a crimped yarn. In this case, by spinning of a plurality of filaments, at least one filament bundle is generated from a thermoplastic polymer, is cooled and drawn and is compressed by means of an air stream in a stuffing chamber into a yarn plug, the yarn plug being opened up into a crimped yarn and being wound into a bobbin. So that the tendency to shrinkage and the crimp resistance on the crimped yarn can be set independently of one another, before compression, the drawn filament bundle is heated, in a first heat treatment for expansion, to a relaxation temperature and, in a second heat treatment for preliminary thermo control, to a crimping temperature. For this purpose, at least one further treatment means for the heat treatment of at least one filament bundle before entry into the stuffing chamber is provided between a drawing device a texturing device.
The invention relates to a melt-spinning method 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 7.
A generic method and a generic apparatus are known from WO 2011/138 302 A1.
When crimped yarns, which are preferably used for production of carpets, are being produced in a melt-spinning process, all the treatment steps for generating the desired physical properties of the yarn usually take place in succession. First, a multiplicity of filaments are extruded from a polymer melt 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, in which the filament bundle is conveyed by means of a preferably heated air stream. Inside the stuffing chamber, the filaments are deposited in curves and loops to form the yarn plug, subsequent cooling of the yarn plug bringing about a fixing of the loops and curves of the filaments which causes crimping.
In the method known in the prior art and in the known apparatus, the godet pairs used for drawing the filament bundle are designed to be heated. Thus, the filament bundle is taken off from the spinning device by means of a take-off godet pair and is heated to a temperature necessary for drawing. The drawing of the filament bundle takes place between the take-off godet pair and a following drawing godet pair. The drawing godet pair is likewise designed with heated godets, so that thermally controlled expansion takes effect on the filament bundle. Subsequently, the drawn and expanded filament bundle is immediately compressed into the yarn plug by means of a hot air stream. The bends, loops and curves of the filaments within the yarn plug cause crimping. Depending on the process settings, different crimping intensities are obtained, the temperature of the yarn material having a decisive influence as a setting parameter. Thus, in general, the higher the yarn temperature is before compression, the more ductile the filaments are and the more easily crimping can be imparted.
In the prior art, there is, however, the problem that the yarn temperature of the filament bundle before compression depends essentially upon the expansion of the filament bundle at the heated drawing godet pair. Moreover, on top of this, the conveying medium, for example hot air, also gives rise to thermal effects on the filament bundle.
The object of the invention, therefore, is to develop a melt-spinning method and a melt-spinning apparatus of the generic type, in such a way as to ensure that crimping can be set in a stipulated way via the yarn temperature of the filament bundle.
A further aim of the invention is to make available a melt-spinning method and a melt-spinning apparatus in which the physical properties of the yarn can be set individually in terms of shrinkage and crimping.
This object is achieved, according to the invention, for the melt-spinning method in that, before compression, the drawn filament bundle is heated, in a first heat treatment of expansion, to a relaxation temperature and, in a second heat treatment for preliminary thermo control, to a crimping temperature.
The melt-spinning apparatus according to the invention offers the solution in that at least one further treatment means for the heat treatment of a filament bundle before entry into the stuffing chamber is provided between the drawing device and the texturing device.
Advantageous developments of the invention are defined by the features and feature combinations of the respective sub claims.
The invention is distinguished in that, before compression, two separate heat treatments are provided on the drawn filament bundle and are coordinated with those respective physical properties of the yarn material and of the filaments which are to be influenced. Thus, the first heat treatment provided immediately after drawing can be utilized in order to carry out desired expansion on the filament bundle in order to obtain a specific shrinkage on the yarn. Shrinkage in this case characterizes the ability of the yarn to reduce the yarn length under thermal load. The second heat treatment is independent of the first heat treatment and may advantageously be utilized in order to obtain on the filament bundle a crimping temperature which is desired for compression and therefore for crimping. Crimping is the capacity for resilience of the filaments after mechanical load.
In order, within the filament bundle, to heat each of the stringily guided filaments to a desired crimping temperature, the method variant is preferably used in which, for the second heat treatment, the filament bundle is guided in a plurality of loopings on a hot godet pair with heated godets. Owing to the number of loopings of the filament bundle on the hot godet pair, relatively long dwell times can be achieved, even at higher thread running speeds, and ensure uniform full heating of the entire filament bundle. The godet casings of the heated godets are in this case heated to the desired crimping temperature.
The first heat treatment is advantageously carried out directly on a drawing godet pair of heated godets, so that there is no need for any additional treatment means for expansion of the filament bundle.
Since the properties of the filaments extruded from a thermoplastic polymer can be influenced vary greatly by the subsequent heat treatments, the melt-spinning method according to the invention offers high flexibility in the setting of various combinations of crimping and shrinkage. Thus, it is generally known that a low treatment temperature leads during expansion to increased shrinkage and during compression to low crimping.
Conversely, at relatively high treatment temperatures the filaments undergo low shrinkage during expansion and higher crimping during compression. In order to obtain a crimped yarn having balanced properties, the method variant is preferably used in which the relaxation temperature for the expansion of the thermal bundle is identical to the crimping temperature for the preliminary thermo control of the filament bundle.
Consequently, crimped yarns with low shrinkage and intensive crimping or crimped yarns with low crimping and increased shrinkage can be generated.
The method variant in which the relaxation temperature for the expansion of the filament bundle lies above the crimping temperature for the preliminary thermo control of the filament bundle is especially suitable for producing a crimped yarn with low shrinkage and low crimping. Since crimping not only determines the bulkiness of the yarn, but also has an appreciable influence upon the appearance of the yarn in the carpet, special color apparitions can consequently be generated in the carpet.
To produce crimped yarns with relatively high shrinkage and high crimping, the method variant is provided in which the relaxation temperature for the expansion of the filament bundle lies above the crimping temperature for the preliminary thermo control of the filament bundle, and in which the filament bundle is slightly drawn between expansion and preliminary thermo control. To that extent, the method according to the invention is especially suitable for implementing special effects both in the yarn and in the subsequent carpet end product.
The melt-spinning apparatus according to the invention, in principle, affords the possibility that the treatment means for the second heat treatment could be formed by conventional heating means known in the fiber industry. At the transition of the filament bundle from the drawing device to the texturing device, for example, a radiant heater or a steam nozzle can be used for heating the filament bundle to a crimping temperature.
However, the variant is especially advantageous in which the treatment means is designed as a hot godet pair with heated godets. Consequently, depending on the yarn titer, the dwell time for heat treatment can be varied in a simple way by the choice of the number of loopings. The melt-spinning apparatus is thus suitable for crimped yarns of any type.
The high flexibility in carrying out the heat treatments is also improved in that, according to an advantageous development, the drawing godet pair and the hot godet pair have in each case a heating control, by means of which a plurality of godet heating means can be controlled. Thus, the separate heat treatments by the drawing godet pair and by the hot godet pair can be controlled and regulated independently of one another.
For stipulating the desired relaxation temperature and the desired crimping temperature, the heating controls are preferably connected to a process control unit which stipulates the process parameters.
To fix the material variations triggered as a result of the heat treatments, the apparatus is preferably used with a texturing device which has a cooling drum for cooling a yarn plug lead out of the stuffing chamber. Only after all the compressed filaments within the yarn plug are thermally controlled to a desired cold temperature is the yarn plug opened up into the crimped yarn.
The melt-spinning method according to the invention and the melt-spinning apparatus according to the invention are suitable, in principle, for all thermoplastic polymers which are used for fiber production. Thus, crimped yarns can be produced from polyolefins, polyamides, polyesters or other polymers, such as, for example, PTT, PLA.
The melt-spinning method according to the invention and the melt-spinning apparatus according to the invention are explained in more detail below by means of some exemplary embodiments, with reference to the accompanying figures in which:
The exemplary embodiment, shown in
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 spinnerets next to one another.
Underneath the spinning device 1, a cooling device 5 is provided, which forms a cooling shaft 6 for the reception of 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 occur 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.
After cooling, the filaments 8 generated by the spinnerets 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 conventionally has a collective yarn guide and a wetting means. The wetting means used may be preparation pins or preparation rollers.
The preparation device 9 is followed in the yarn run by a drawing device 11 which is formed in this exemplary embodiment by a take-off godet pair 12 with two heated godets 12.1 and 12.2 and by a drawing godet pair 14 with the heated godets 14.1 and 14.2. The godet heating means used for heating the godets 12.1 and 12.2 of the take-off godet pair and the godets 14.1 and 14.2 of the drawing godet pair 14 are illustrated symbolically and are characterized by the reference symbols 12.3 and 14.3. The heated godets 12.1 and 12.2 and also 14.1 and 14.2 are arranged in each case in a godet box 13. There is in this case, in principle, the possibility that the godet pairs 12 and 14 are arranged in separate godet boxes or in one common godet box.
So that the respective surface temperatures of the heated godet casings of the godets 12.1 and 12.2 can be set, the godet heating means 12.3 are coupled to a heating control appliance 27.1. The godet heating means 14.3 of the drawing godet pair 14 are likewise coupled to a separate heating control appliance 27.2. The heating control appliances 27.1 and 27.2 are connected to a process control unit 31.
Further along the yarn run, a further godet pair, which in this case is designated as a hot godet pair 26, is provided between the drawing device 11 and the texturing device 15.
The hot godet pair 26 has two heated godets 26.1 and 26.2 with the assigned godet heating means 26.3. In this exemplary embodiment, the godets 26.1 and 26.2 are likewise arranged in a godet box 13. To set the respective surface temperatures of the heated godet casings of the godets 26.1 and 26.2, the godet heating means 26.3 are connected to a further heating control appliance 27.3. The heating control appliance 27.3 is coupled to the process control unit 31.
In this exemplary embodiment, the texturing device 15 is formed by a conveying nozzle 16 and a stuffing chamber 17 which is arranged on the outlet side of the conveying nozzle 16 and which cooperates 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 into the stuffing chamber 17 by means of an air stream and to compress it into a yarn plug. The air stream for conveying the filament bundle is preferably heated. The yarn plug 18 is cooled on the circumference of the cooling drum 19 by cooling air.
The texturing device 15 is followed by a posttreatment device 20 which, on the one hand, opens up the yarn plug 18 by taking off a crimped yarn on the circumference of the cooling drum 19 and, on the other hand, performs intermingling of the yarn 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.
At the end, the crimped yarn 21 is wound into a bobbin 25 by means of the winding device 24. For this purpose, the winding device 24 has a reeling turret 28 with two projecting reeling spindles 29.1 and 29.2. The reeling spindles are guided successively into a winding region and a changing region in order to wind the crimped yarn continuously into bobbins. Such winding devices are generally known, and therefore there will be no further description in this respect at this juncture.
In the exemplary embodiment, illustrated in
The filament bundle 10 is taken off from the spinning device by means of the take-off godet pair 12. The godet heating means 12.3 are set via the assigned heating control appliance in such a way that the godets 12.1 and 12.2 have on their godet casings a surface temperature in the range of 90° C. to 100° C. In this case, the filament bundle 10 is guided with preferably 7 to 15 loopings on the take-off godet pair 12. The yarn material of the filaments is thereby heated to a temperature suitable for drawing.
For drawing the filament bundle 10, the drawing godet pair 14 is driven at a higher speed than that of the take-off godet pair 12, so that the filament bundle 10 is drawn in the yarn section between the take-off godet pair 12 and the drawing godet pair 13.
After drawing and before compression, the drawn filament bundle 10 is heated to a relaxation temperature in a first heat treatment for expansion. The first heat treatment after drawing is carried out directly by the drawing godet pair 14. For this purpose, the godet heating means 14.3 are set via the heating control appliance 27.2 at a relaxation temperature suitable for the yarn material. Depending on the type of polymer, the godet casings of the godets 14.1 and 14.2 have a surface temperature in the range of 120 to 240° C., preferably of 170 to 210° C. The surface temperature of the godet casings of the godets 14.1 and 14.2 constitutes at the same time the relaxation temperature at which the yarn material of the filaments within the filament bundle 10 is heated. For this purpose, the filament bundle 10 is preferably guided with overall 8 to 12 loopings on the godet pair 14. The number of loopings on the godet pair 14 in this case determines the dwell time for the expansion of the filaments.
In order to obtain thermo controls of the filament bundle which are especially suitable for the texturing operation, in a second heat treatment the filament bundle is heated to a crimping temperature. For this purpose, the godets 26.1 and 26.2 of the hot godet pair are heated by the godet heating means 26.3 to a predetermined surface temperature of the godet casings. The surface temperature of the godet casings of the godets 26.1 and 26.2 corresponds to the crimping temperature to which the yarn material of the filaments is heated. The instructions and settings take place in this case via the process control unit 31 which is coupled to the godet control appliance 26.3.
The setting of the crimping temperature in the second heat treatment on the drawn filament bundle is dependent upon the in each case desired yarn effect which is to be achieved on the crimped yarn. In this case, in principle, the following setting variants are possible.
In a first variant, the relaxation temperatures in the first heat treatment for expansion and the crimping temperature in the second heat treatment for preliminary thermo control of the filament bundle are set at an identical level. Depending on the absolute height of the temperature, different yarn types can be generated according to the yarn material. Thus, it is generally known that, at very high relaxation temperatures and crimping temperatures in the range of above 190° C., expansion leads to a very low shrinkage behavior. Shrinkage is the ability of the fibers to become shorter under thermal load.
The result of setting relatively high crimping temperatures on the filament bundle is that the ductility of the filaments increases and therefore intensive bending and loop and curve formation occur during the compression of the filaments into the yarn plug. The outcome of this is relatively high crimping and crimp resistance of the crimped yarn.
Crimping can in this case be defined as resilience of the fiber after mechanical load. The higher is the degree of resilience of the fiber, the more crimp-resistant is the yarn.
In the first variant, with the relaxation temperature and the crimping temperature being identical, crimped yarns which are characterized by relatively high shrinkage and low crimping can also be produced by setting the temperature level. Thus, sufficient expansions of the filaments are not generated when the relaxation temperature of the first heat treatment is very low. The residual stresses remaining in the filaments then lead to a high tendency of the crimped yarn to shrinkage. During preliminary thermo control, low crimping temperatures have the effect of a lack of ductility of the filaments and lead to low crimping and crimp resistance of the yarn.
When the temperature level between the relaxation temperature and crimping temperature is different, a distinction can be made between two further variants for the production of crimped yarns. In a further variant, the heat treatment for expansion is carried out at a relaxation temperature which is substantially higher than the crimping temperature in the second heat treatment for preliminary thermo control of the filament bundle. A crimped yarn is consequently generated which is characterized by low shrinkage and low crimping.
In the variant in which the relaxation temperature in the heat treatment for expanding the filament bundle is higher than the crimping temperature in the second heat treatment for the preliminary thermo control of the filament bundle and in which the filament bundle is slightly drawn between expansion and preliminary thermo control, opposite effects occur, so that a yarn with high shrinkage and high crimping is generated. The amount of post drawing decisively influences the shrinkage of the yarn which could lie in the range of −1% to +5%.
It was shown that, by virtue of the method according to the invention, crimped yams can be produced which generate special effects, particularly in carpet production. Thus, it is generally known that crimping has an appreciable influence not only on the bulkiness of the yarn, but also on the appearance of the fibers in the carpet. Thus, color apparition is determined by the crimping. A highly crimped filaments tends in a carpet to produce duller, less high-contrast colors, since the eyes are drawn to an increased extent to more bent side faces of the filaments. However, increased shrinkage is undesirable, since otherwise, with a thermal load, the fiber contracts to too great an extent and therefore the pile height in the carpet is reduced. Carpets with high-contrast colors therefore tend to be produced with crimped yarns which are characterized by low crimping and low shrinkage.
In the exemplary embodiment of the melt-spin apparatus according to the invention, as shown in
For compression, the filament bundle 10 is conveyed through the conveying nozzle 16 into the stuffing chamber 17 and built up into a yarn plug. The conveyance of the filament bundle may in this case take place by means of a hot air stream or a cold air stream. In this case, the preliminary thermo control of the filament bundle to the crimping temperature must be taken into account. The yarn plug 18 formed by the compressed filaments of the filament bundle 10 is conveyed 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 posttreatment device 20 which has a first guide godet unit 23.1. Further along the run, 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.
In the exemplary embodiment according to
In the exemplary embodiment, as shown in
In the drawing device 11, the filament bundles 10.1, 10.2 and 10.3 are guided next to one another in parallel and jointly drawn. For this purpose, the drawing device 11 has a take-off godet pair 12 and a drawing godet pair 14. The take-off godet pair 12 is formed in this case by a heated godet 12.1 and an auxiliary roller 12.4. The heated godet 12.1 has a godet heating means 12.3 which can be controlled via a heating control appliance 27.1. The drawing godet pair 14 has the heated godets 14.1 and 14.2, the godet casings of which are heated by the godet heating means 14.3. The godet heating means 14.3 are coupled to a heating control appliance 27.2. The drawing godet pair 14 is to that extent identical to the abovementioned exemplary embodiment according to
Underneath the drawing device 11, a hot godet pair 26 is provided, which is likewise designed identically to the abovementioned exemplary embodiment according to
The following texturing device 15, the posttreatment device 20 and the winding device 24 are identical to the exemplary embodiment according to
In the exemplary embodiment illustrated in
The preliminary thermo control of the filament bundles 10.1 to 10.2 to the crimping temperature takes place by means of the hot godet pair 26, the filament bundles 10.1 to 10.3 likewise being guided next to one another in parallel with a plurality of loopings on the godets 26.1 and 26.2.
For texturing, the filament bundles 10.1 to 10.3 are jointly compressed by a conveying nozzle 16 into a yarn plug 18. The yarn plug 18 is thus 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 10.1 to 10.3 separately in each case into a separate yarn plug and of opening up said yarn plugs into a plurality of crimped yarns which are subsequently combined in the posttreatment device 20 into a composite yarn with the aid of the intermingling nozzle 22.
The melt-spinning method according to the invention and the melt-spinning apparatus according to the invention thus extend to crimped single-color yarns and to crimped multicolor yarns. There may be yarns with different physical properties, such as individual titer, cross section, color or else different types of polymer. It is essential in this case that the heat treatments for the relaxation of the filaments and the heat treatment for the preliminary thermo control of texturing take place in separate treatment steps. This ensures that the expansion of the filaments and the crimping of the filaments can be set independently of one another. The melt-spinning method according to the invention and the melt-spinning apparatus according to the invention are suitable, in principle, for all thermoplastic polymers which are used for fiber production.
LIST OF REFERENCE SYMBOLS
- 1 Spinning device
- 2 Spinning head
- 3,3.1,3.2,3.3 Spinneret
- 4,4.1,4.2,4.3 Melt inflow
- 5 Cooling device
- 6 Cooling shaft
- 7 Blowing means
- 8 Filament
- 9 Preparation device
- 10,10.1,10.2,10.3 Filament bundle
- 11 Drawing device
- 12 Take-off godet pair
- 12.1,12.2 Heated godets
- 12.3 Godet heating means
- 12.4 Auxiliary roller
- 13 Godet box
- 14 Drawing godet pair
- 14.1,14.2 Heated godets
- 14.3 Godet heating means
- 15 Texturing device
- 16 Conveying nozzle
- 17 Stuffing chamber
- 18 Yarn plug
- 19 Cooling drum
- 20 Post treatment device
- 21 Crimped yarn
- 22 Intermingling nozzle
- 23.1,23.2 Guide godets
- 24 Winding device
- 25 Bobbin
- 26 Hot godet pair
- 26.1,26.2 Heated godets
- 26.3 Godet heating means
- 27.1,27.2,27.3 Heating control appliance
- 28 Reeling turret
- 29.1,29.2 Reeling spindle
- 30.1,30.2,30.3 Spinning godet unit
- 31 Process control unit
Claims
1. A melt-spinning method 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, after cooling, the filament bundle is drawn and is compressed by means of a thermally controlled air stream in a stuffing chamber into a yarn plug, and in which the yarn plug is opened up into a crimped yarn and wound into a bobbin, wherein, before compression, the drawn filament bundle is heated, in a first heat treatment of expansion, to a relaxation temperature and, in a second heat treatment for preliminary thermo control, to a crimping temperature.
2. The method as claimed in claim 1, wherein, for the second heat treatment, the filament bundle is guided in a plurality of loopings on a hot godet pair with heated godets.
3. The method as claimed in claim 1, wherein, for the first heat treatment, the filament bundle is guided in a plurality of loopings on a drawing godet pair with heated godets.
4. The method as claimed in claim 1, wherein the relaxation temperature for the expansion of the filament bundle is identical to the crimping temperature for the preliminary thermo control of the filament bundle.
5. The method as claimed in claim 1, wherein the relaxation temperature for the expansion of the filament bundle lies above the crimping temperature for the preliminary thermo control of the filament bundle.
6. The method as claimed in claim 1, wherein the relaxation temperature for the expansion of the filament bundle lies above the crimping temperature for the preliminary thermo control of the filament bundle, and in that the filament bundle is slightly drawn between expansion and preliminary thermo control.
7. A melt-spinning apparatus for producing a crimped yarn, with a melt-spinning device, with a cooling device, with a drawing device, with a texturing device which has a conveying nozzle and a stuffing chamber, and with a winding device, the drawing device having a take-off godet pair and a drawing godet pair with heated godets, wherein at least one further treatment means for the heat treatment of at least one filament bundle before entry into the texturing device is provided between the drawing device and the texturing device.
8. The apparatus as claimed in claim 7, wherein the treatment means is designed as a hot godet pair with heated godets.
9. The apparatus as claimed in claim 7, wherein the drawing godet pair and the hot godet pair have in each case a heating control appliance, by means of which a plurality of godet heating means can be controlled.
10. The apparatus as claimed in claim 9, wherein the heating control appliances are connected to a process control unit.
11. The apparatus as claimed in claim 7, wherein the texturing device has a cooling drum for cooling a yarn plug guided out of the stuffing chamber.
Type: Application
Filed: Aug 8, 2013
Publication Date: Aug 20, 2015
Inventor: Mathias Stündl (Wedel)
Application Number: 14/421,316
