EP1456441B1 - Method and device for producing a low-shrinking smooth yarn - Google Patents

Abstract

A method and apparatus for producing a high-strength and low-shrinkage synthetic flat yarn. After melt spinning, the filaments are combined to a yarn and drawn. Subsequently, the yarn is compressed to form a plug under the influence of heat. This plug is transported over a certain distance, so that the yarn relaxes in a low-tension state and under the influence of the increased temperature. Finally the plug is disentangled under tension to form the flat yarn, which is wound into a package.

Description

The invention relates to a method for producing a low-shrink synthetic plain yarn according to the preamble of claim 1 and to an apparatus for carrying out the method according to the preamble of claim 10.

For example, high tenacity smooth yarns used in the manufacture of PVC coated tarpaulins, conveyor belts, or V-belts are required to have little shrinkage later during heat processing.

Therefore, in the production of these plain yarns, the yarn is again subjected to elevated temperature and reduced stress after melt-spinning and stretching so that the yarn can relax. Such a method is in the EP 0 164 624 B1 described.

It has been found that for the shrinkage of the yarn during relaxation, the parameters low yarn tension, temperature and time are important. With the in the EP 0 164 624 B1 shown device just the parameters thread tension, time and Teperatur can not be set arbitrarily First, a minimum thread tension must be maintained for a clean yarn path. On the other hand, especially at high yarn speeds, a long residence time would require a long running distance, which, moreover, can easily lead to an unstable yarn path at very low yarn tension. A reduction of the shrinkage in the yarn on the finished coil can cause after coils on such high forces in the coil act, that the coil can not be genonunen of the mandrel.

From the EP-A-0801159 It is also known that loops and loops formed during swirling of filaments can be largely eliminated when relaxing in later stages of heating, which is used in the production of plain yarns.

From the DE 101 00 762 A It is furthermore known that a thread can be brought together to form a compact stopper and conveyed as such, with permanent crimping being produced in the yarn upon dissolution of the stopper by cooling.

It is therefore an object of the invention to extend the known method and the known device to the effect that at the lowest possible yarn tension high residence times are achieved in the relaxation.

This object is achieved by a method with the features of claim 1 and by a device having the features of claim 10.

Advantageous variants of the method according to the invention are defined in the dependent claims 2 to 9 and advantageous developments of the device according to the invention are defined in the subclaims 11 to 14.

The invention is characterized in that even at relatively high yarn speeds a Relaxierbehandlung with long residence times is possible.Dabei the mulitifile thread is first stretched after melt spinning. For the subsequent relaxation of the thread is compressed in a relaxation device with a stuffer box to a stopper. For this purpose, the thread is conveyed under the action of heat in the stuffer box and compressed there. Due to the continuously conveyed yarn, the plug is conveyed without tension through the relaxation device. Since the plug has a significantly larger diameter than the thread, the speed of stuffing is orders of magnitude lower than the feeding speed of the thread because of the continuity condition. Thus, even with short guide lengths of the relaxation device relatively high residence times can be achieved under high temperature and in a tension-free state. Upon exiting the relaxation device, the plain yarn is pulled out of the plug under tension. Here, in contrast to a crimping device, where usually the plug is then cooled to fix the crimp, the yarn withdrawn here in the hot state from the relaxation and further processed with such high thread tension that no crimping remains in the yarn and thus a typical plain yarn is present.

Especially with the use of polyester can be produced even at relatively low withdrawal voltage from the plug a plain yarn. Thus, all polyester types are considered to be particularly suitable.

In order to guide the thread under the action of heat to a stopper, a hot medium is preferably used to convey the thread, which is guided by means of a delivery nozzle together with the thread in the stuffer box.

The medium can be formed from a hot air or a hot steam.

A process variant of the method according to the invention provides once again a post-stretching after relaxation. As a result, a latent residual crimp possibly still remaining in the yarn is broken down.

In a particularly advantageous variant of the method, the step of pulling the plug apart is supplemented and secured by additional method steps. Due to fluctuations in yarn or process parameters, different sizes of incoming and outgoing yarn mass flows can occur. This is to the effect that the length of the plug may possibly increase or decrease continuously. Therefore, in this variant of the method, the position of the stopper end is sensed and intervened in a correcting manner to the temperature of the medium.

In a further advantageous variant of the method, the speed of the godet pulling off the thread is acted upon alternatively or additionally. By this intervention, an immediate effect on the stopper length is achieved.

Characteristic of the invention is that the yarn speed in the yarn path behind the relaxation is less than the yarn speed in the yarn path before the relaxation. By contrast, the winding speed is again slightly higher than the thread speed behind the relaxation device. This results for the invention that the winding device is operated at a winding speed which is more than 85% of the peripheral speed of the last godet before the relaxation.

Of course, the method according to the invention can also be used for the production of 8 / ionofilaments, that is to say threads which consist only of one thick filament.

An apparatus for carrying out the method according to the invention consists of a spinning device in which the filaments are melt-spun, a Verstreclceinrichtung in which the thread is stretched into a high-strength thread, a compression chamber as relaxation and a winding device. The stuffer box is designed so that form as few loops and bows in the deposited filaments when upsetting the thread. Essential here is the possibility that the tempered thread is guided stress-free in the stuffer box as a plug for a long residence time as long as possible, so that a very low-shrinkage smooth yarn is present after dissolution of the plug.

In a further development of the device according to the invention, a Nachverstreckungeinrichtung is provided behind the relaxation, which raises the thread tension slightly to smooth the smooth yarn behind the stuffer box again. In the simplest case, this Nachverstreckungseinrichtung is formed from a pair of godets, which cooperates with the winding device. But it is also possible that two Galettenduos be used, the second pair of godets is operated at a slightly higher speed, so that a yarn tension is built up. Instead of the godet godets, godets with overflow rollers can also be used.

In order to obtain a uniform conveying of the thread with simultaneous heating of the thread, the relaxation device preferably has a delivery nozzle which is connected to a medium source and is acted upon by a hot medium. The thread can thus be heated, for example, by hot air or hot steam and promote.

The inventive method and an embodiment of the device according to the invention will be described in more detail below with reference to the accompanying drawings.

Fig. 1

schematisch ein erstes Ausführungsbeispiel der erfindungsgemäßen Vorrichtung, auf der das erfindungsgemäße Verfahren angewendet wird,

Fig. 2

schematisch eine Schnittansicht der Relaxiereinrichtung des Ausführungsbeispiels aus Fig. 1,

Fig. 3

schematisch ein weiteres Ausführungsbeispiel einer Relaxiereinrichtung.

They show:

Fig. 1

schematically a first embodiment of the device according to the invention, to which the method according to the invention is applied,

Fig. 2

1 is a schematic sectional view of the relaxation device of the embodiment of FIG. 1;

Fig. 3

schematically a further embodiment of a relaxation device.

In Fig. 1, a first embodiment of the device according to the invention is shown schematically, to which the inventive method is applied.

The device has a spinning device which is formed by a spinning head 1 and a plurality of spinning nozzles 15. The spinning head 1 is connected by a melt inlet 29 with a melt source, not shown here, for example, with an extruder. On the underside of the spinning head 1, a plurality of spinnerets 15 are mounted, each containing a plurality of spinneret holes, through which each a filament bundle 2 is extruded. In the embodiment, four spinnerets 1 are shown by way of example.

The filament bundle 2 is cooled after extrusion by a cooling air 3, wetted in a preparation device 4 with a preparation and combined to form a thread 5.

After the yarn 5 is formed, it is first pulled off a godet 6, which cooperates with an overflow roller 25. It is common that on such spinning plants several threads are made in a parallel process and are treated in parallel on the same godets. In the following description, the devices of the device and the method for simplifying a thread will be described.

After the godet 6 of the thread 5 is guided to a drawing device, which is formed by several Galettenduos 7.1, 7.2 and 7.3. In this case, the thread 5 is first stretched between two heated godet duos 7.1 and 7.2 in a first draw zone 8.1 and then between two heated godet ducks 7.2 and 7.3 in a second draw zone 8.2. After this treatment, the thread 5 has reached a high strength. He has, however, the desire to shrink under the influence of temperature. This is especially in the cases mentioned where the threads in the subsequent processing with hot coating materials be sheathed, undesirable. Therefore, the thread 5 is guided in a subsequent relaxation zone 16 with a relaxation device 9. Under temperature and in a tension-free state, the thread 5 in the relaxation device 9 is given the opportunity to relax, ie to reduce its shrinkage tendency. The thread shortens, depending on polymer and process parameters, by about 13%.

For this purpose, the thread 5 is upset within the relaxation device 9, which is described in detail in Figure 2, to a stopper. In a parallel treatment of several threads, it is possible to provide a separate relaxation device for each thread or to treat a plurality of threads in a common Relaxiereiririchtung.

After relaxation, the plug is pulled under tension to a plain yarn 22. For this purpose, a Nachverstreckeinrichtung 21 is provided, which is formed in this embodiment by another Galettendo 7.4. Subsequently, the plain yarn 22 is wound by means of a winding device 10 to form a coil 26.
Since, after the relaxation device 9, in particular between Galettendo 7.4 and winding device 10, a higher yarn tension level prevails, any curl which may have remained behind in the yarn is reduced. This process is referred to in this context as Nachverstreckung.

To dissolve the plug, the Nachverstreckeinrichtung 21 could also be formed by a godet with an overflow roller. For re-stretching then act the godet and the Aufspuleinrichtung together.

FIG. 2 shows in section a possible embodiment of a relaxation device 9 with the aid of which the method according to the invention can be realized. The relaxation device 9 has a delivery nozzle 17 to which a heated medium 18 is supplied via a line 28. The medium 18, which has been previously heated by heater 13, is passed into a thread channel 27 in order to convey the thread 5. The thread channel 27 opens into a stuffer box 19 of the Relaxing device 9. Within the stuffer box 19, the thread 5 is guided to a stopper 20. Here, the thread loops, which leads to a congestion and consequently to a compression, so that from the Faden5 the plug 20 is formed, which is slowly conveyed through the stuffer box 19 of the relaxation device 9. In this case, a hot fluid such as hot air or steam is used as the conveying medium 18 to provide the thread with the temperature required for relaxation. In a guide portion 23 of the stuffer box 19 a plurality of slots are introduced, through which the medium is discharged again. The plug 20 then leaves via the outlet opening 24, the relaxation device 9 and is dissolved into the plain yarn 22.

Assuming a yarn denier of 1000 dtex and a Zulafgeschwindigkeit of 5000 m / min, this corresponds to a tapering mass flow of 500 g / min. With a compression region volume of about 31 cm ³ at 2 cm diameter and 10 cm length, this results in a stopper density of 20% and polyester as polymer to a residence time of the yarn in the relaxation device 9 of about 1 second.

After leaving the relaxation device, the plain yarn 22, since it is then further promoted from the godet duo 7.4 shown in Figure 1 again at high speed, pulled out of the plug 20. Due to the high acceleration occurring occur inertial forces that cause tensile forces in the yarn and sufficiently stabilize the yarn. In this case, the speed at which the yarn is withdrawn, must be adjusted in such a way that the relaxation mass per unit time supplied yarn mass is identical to the discharged yarn mass.

If the discharged yarn mass is greater, the plug would be completely removed from the relaxation device. If the discharged yarn mass is lower, the stopper growth at the inlet of the stuffer box 19 would be greater than the stopper outlet at the outlet 24, so that the stopper would outgrow the relaxation device 9. In Fig. 3, another embodiment of the relaxation device 9 is shown, which would be used for example in a device according to Fig. 1 and which has a control of the plug formation. You relaxation facility 9 is constructed substantially identical to the embodiment of FIG. 2, so that only the differences are listed below.

At the outlet opening 24 of the relaxation device 9, a sensor 11 is provided, which senses a plug growth or a plug fading. The signaled value of the sensor 11 is compared in a comparator 30 with a desired value and supplied to a controller 12 in deviation. The regulator 12 is connected to a heater 13 which heats the medium 18 supplied to the delivery nozzle 17. The heating of the medium 18 can thus be corrected by way of the regulator 12. The controller 12 is also coupled to a godet drive 14 which drives the godet duo 7.4 Nachverstreckeinrichtung 21. In addition, the rotational speed of the godet drive 7.4 driving the godet drive 14 can be corrected accordingly.

An increase in the temperature of the medium 18 causes a higher relaxation of the thread, so that a shortening and thus a higher mass per length occurs. At a constant initial velocity of the godet dome 7.4 this leads to a higher mass outflow and thus to a regression of the plug.

An increase in the speed of the godet 7.4 directly causes a higher mass transport and thus also a regression of the plug 22. It should be noted that the speed of the godet 7.4 immediately affects the stopper length, while the temperature only with a time delay, the in approximately corresponds to the residence time of the yarn in the relaxation, acts on the plug length.

However, there is also the possibility that the relaxation device 9 shown in FIG. 3 can only be used in conjunction with a temperature control of the pumped medium or only with a speed control of the godet hood.

The illustrated relaxation devices in FIGS. 2 and 3 are exemplary. Thus, any relaxation device could be used in the apparatus of FIG. 1, in which the thread is guided by means of a conveying means within a stuffer box to a stopper and heated. By the Aufstauchung the thread can be sufficient even at high Fadengeschwindiglceiten To reach residence times for the relaxation of the thread. The compression of the thread is preferably carried out with a low stuffing density in order to obtain a complete dissolution of the loops and loops in the filaments upon dissolution of the plug, so that after the dissolution of the yarn contains no crimp more.

LIST OF REFERENCE NUMBERS

1.

spinning head

2

filament bundle

3

Kühllüft

4

preparation device

5

thread

6

Galette

7.1, 7.2, 7.3, 7.4

godet duo

8.1, 8.2

stretching zone

9

relaxation device

10

takeup

11

sensor

12

regulator

13

heater

14

godet

15

spinneret

16

relaxation zone

17

feed nozzle

18

conveying medium

19

stuffer

20

Plug

21

Nachverstreclceinrichtung

22

flat yarn

23

guide section

24

outlet opening

25

Guide roll

26

Kitchen sink

27

thread channel

28

management

29

melt inlet

30

comparator

Claims (14)

1. Method of producing a high-strength, low-shrinkage synthetic flat yarn,
   comprising the steps of:

   1.1 melt spinning a plurality of filament yarns from a molten polymer;

   1.2 cooling and combining the filaments to a yarn;

   1.3 drawing the yarn;

   1.4 compressing the yarn to a plug at an increased temperature;

   1.5 advancing the plug;

   1.6 disentangling the plug under a tension to a flat yarn; and

   1.7 winding the flat yarn to a package.
2. Method of claim 1,
   characterized in that
   the molten polymer for melt spinning the filaments is extruded from a polyester.
3. Method of claim 1 or 2,
   characterized in that
   the compression of the yarn to the plug occurs with the aid of a medium, which advances the yarn for forming the plug.
4. Method of claim 3,
   characterized in that
   the medium consists of a hot air or a hot vapor.
5. Method of one of the foregoing claims,
   characterized in that
   the flat yarn is additionally drawn after disentangling the plug.
6. Method of one of the foregoing claims,
   characterized in that
   while disentangling the plug, the position of the plug end is sensed, and that as a function of the position of the plug end, the temperature of the medium is controlled.
7. Method of one of the foregoing claims,
   characterized in that
   while disentangling the plug, the position of the plug end is sensed, and that as a function of the position of the plug end, the withdrawal speed of the flat yarn from the plug is controlled.
8. Method of one of claims 1-7,
   characterized in that
   before being compressed, the yarn is guided by a godet, and that the ratio of the takeup speed for winding the flat yarn to the circumferential speed of the godet is greater than 0.85 to 1.
9. Method of one of the foregoing claims,
   characterized in that
   the yarn is formed from a single filament.
10. Apparatus for producing a high-strength, low-shrinkage flat yarn,
    comprising a spinning device (1; 15), a draw zone (7.1-7.3), a relaxation device (9), and a takeup device (10),
    characterized in that
    the relaxation device (9) comprises a stuffer box chamber (19), in which the yarn (5) is compressed to a plug (20).
11. Apparatus of claim 10,
    characterized in that
    a final draw zone (20) downstream of the relaxation device (9) is provided for withdrawing and drawing the flat yarn (22).
12. Apparatus of claim 11,
    characterized in that
    the final draw zone (20) is formed by at least one pair of godets (7.4), or at least one godet with a guide roll, which cooperates with the takeup device (10).
13. Apparatus of one of claims 10-12,
    characterized in that
    the relaxation device (9) comprises a feed nozzle (17) upstream of the stuffer box chamber (19), which advances the yarn (5) into the stuffer box chamber (19) by means of a tempered medium, preferably hot air.
14. Apparatus of claim 13,
    characterized in that
    the stuffer box chamber (19) comprises a gas permeable guide section (23), through which the medium leaves the stuffer box chamber (19).

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