EP1520065B1 - Method and device for melt-spinning and cutting a tow - Google Patents

Description

The invention relates to a method for melt spinning and cutting a tow for the production of staple fibers according to the preamble of claim 1 and an apparatus for performing the method according to the preamble of claim 8.

In principle, two different types of processes and apparatus are known for the production of staple fibers. In a first type of process and apparatus, the staple fibers are produced in a single-stage process. Here, the spinning, drawing, curling and cutting a tow takes place immediately after each other. Such a method and apparatus are known for example from US 3,259,681, from which the invention proceeds.

In a second type of process and apparatus for making staple fibers, these are made in a two-step process. For this purpose, a tow is spun in a first stage, stretched and placed in a pot. In a second process step, several tows are drawn from the cans presented and combined to form a total tow, treated in a fiber line and then cut into staple fibers. Such two-stage processes are particularly suitable for processing very thick total titers having, for example, greater than 180,000 dtex (200,000 den.) And are known, for example, from US Pat. No. 4,639,347. In such methods, it is known that in the second process step, the fully drawn Gesamttow is exposed before cutting a steam atmosphere in order to perform a shrinkage treatment can.

In the single-stage process from which the invention is based, the maximum total titres to be processed are limited by the fact that both the removal of the tow from the spinning device and the stretching of the tow must essentially be carried out by a treatment device with several drafting rollers. In particular, with thicker total titers of the tows, unevenness in the physical properties of the fibers is particularly noticeable. In order to improve the physical properties, in the known process according to US Pat. No. 3,259,681 additional liquid baths are arranged before and within the draw zone, the drawing being carried out in a speed range up to 200 m / min. took place. In particular, it is emphasized that an improvement of the results could be achieved without additional heating of the tow by the fluid within the draw zone.

Today, speeds of up to 2,500 m / min are required to operate single-stage processes economically. reached. At such high stretching rates, however, the known fluid treatments remain without significant influence.

It is therefore an object of the invention to provide a method and an apparatus of the type mentioned, in which or which staple fibers in a single-stage process with relatively uniform physical properties can be produced.

This object is achieved by a method with the features of claim 1 and by a device having the features of claim 8.

The invention is based on the finding that the formation of the draw point and the position of the draw point during stretching of the tow have a significant influence on the uniformity of the has physical properties. Thus, it is known that when stretching the heating of the tow alone by draw rolls inevitably lead to irregularities, since in total titers of the tow of, for example, greater than 9,000 dtex (10,000 den.) Not all filament strands of the tow can be brought to a temperature simultaneously. By means of the method according to the invention, it is possible to influence a uniform heating of all filament strands of the tow and thus, in a targeted manner, the position and the formation of a draw point within the draw zone. Thus, a high uniformity of the physical properties and the individual titer of the staple fiber has been achieved in the melt spinning and cutting a tow of polyester, which at a speed of 200 m / min. withdrawn from the spinning device and over several draw rolls up to a speed of 1,200 m / min. was achieved by the inventive steam treatment in the treatment section between adjacent draw rolls can be achieved that the uniformity of strength could be improved by about 40%, the uniformity of the individual titers by about 50% and the uniformity of elongation by about 30% , The total denier of the tow was 11,700 dtex (13,000 den.).

For treatment and heating, the tow was exposed to a jet of steam from a nozzle. The steam is guided under an overpressure from the nozzle into the steam chamber, whereby it was found that the equalization of the physical properties of the fibers could be influenced by changing the overpressure. In order to maintain a positive effect, the overpressure of the steam should be set to a value in the range of 2 to 12 bar.

In order to obtain an intensive effect and an effect on the draw point within the tow, the steam should have a temperature in the range of 80 to 200 ° C.

A further possibility for improving the homogenization of the physical properties of the fibers is achieved by setting the differential speed of the draw rolls acting within the treatment zone at a specific ratio. The draw ratio may be set in a range between zero and six. In particular, at draw ratios of greater than four, a strong influence on the homogenization of the physical properties was found.

However, it was also possible to achieve a positive influence by the steam treatment within the treatment section, in which the differential speed of the drafting rollers acting in the treatment section led to a flow of the spinning cable into the treatment section. This variant of the method is particularly suitable for reducing stresses immediately after the tow has been drawn.

Thus, it is also advantageous to combine a plurality of steam treatments with one another, wherein a first steam treatment takes place in a treatment section with a high draw ratio and a second steam treatment in a treatment section with a low draw ratio or a feed of the tow. The steam used is preferably a saturated steam or a slightly superheated dry steam.

To carry out the method, the device according to the invention has a steam chamber which is arranged between adjacent draw rolls in the treatment section. The steam chamber is associated with a nozzle through which a steam is passed under an overpressure in the steam chamber.

In order to obtain an intensive treatment and effect on the tow, the nozzle is advantageously directed with a nozzle opening within the steam chamber directly on the tow. This can be through the nozzle generated steam flow both in the direction of the tow and counter to the direction of the tow introduce into the steam chamber. In order to obtain a possible turbulence of the filament strands within the tow, the die is preferably oriented perpendicular to the tow, so that the jet of steam is directed substantially perpendicularly within the steam chamber to the tow.

The development of the device according to the invention, in which the treatment device for stretching the tow has several Streckwalzenduos consisting of two equally driven draw rolls, has the advantage that high forces can be built to stretch the tow. Likewise, a favorable for removing the tow from the spinning device setting can be selected.

For removing the tow from the spinning device but also take-off rollers can be used with associated Beilaufrollen. Similarly, two deduction duos can be used at the same speed to pull off.

The treatment device for drawing the tow cable preferably has a plurality of stretch roll towers arranged one behind the other, between which different speeds of difference are preferably set. In this case, the heating means can advantageously be arranged in at least one of the treatment sections.

However, it is also possible to provide a plurality of heating means, which are arranged in different treatment distances between each two Streckwalzenduos.

In order to improve the spreading results, at least some of the drafting rollers of the drafting roller ducks are designed to be heatable.

The process according to the invention and the device according to the invention are fundamentally suitable for producing staple fibers from all polymers, preferably from polyester, polyamide or polypropylene. Depending on the particular polymer type, the steam, the overpressure of the steam and the nozzle setting for steam treatment are selected. Likewise, the speeds of the draw rolls and the number of heated and unheated draw rolls within the treatment device for drawing the tow are freely selectable. The method according to the invention and the device according to the invention thus offer a high degree of flexibility in the production of staple fibers, which are particularly distinguished by their high uniformity in properties such as titer, elongation and strength. This also results in a high homogenization of dyeability. Through targeted use of the steam treatment, stresses can also be reduced after the tow has been drawn.

The method according to the invention and the device according to the invention are described in more detail below with reference to a few exemplary embodiments with reference to the attached drawings.

Fig. 1

schematisch ein erstes Ausführungsbeispiel einer erfindungsgemäßen Vorrichtung

Fig. 2

schematisch das Heizmittel zur Dampfbehandlung des Ausführungsbeispiels nach Fig. 1

Fig. 3 und Fig. 4

weitere Ausführungsbeispiele der erfindungsgemäßen Vorrichtung

They show:

Fig. 1

schematically a first embodiment of a device according to the invention

Fig. 2

schematically the heating means for steam treatment of the embodiment of FIG. 1

FIG. 3 and FIG. 4

further embodiments of the device according to the invention

In Fig. 1, a first embodiment of a device according to the invention for the single-stage production of staple fibers is shown schematically. The Device comprises a spinning device 1 a plurality of successively arranged treatment device, which are explained in more detail below the reference numerals 2, 3, 4, 5 and 6, and a cutting device 7.

The spinning device 1 contains several spinning stations. In this embodiment, four spinning stations are represented by the reference numerals 1.1, 1.2, 1.3 and 1.4. In each of the spinning unit 1.1 to 1.4, a respective filament bundle 12 is spun from a polymer melt. The spinning stations 1.1 to 1.4 are constructed identically to this, so that the construction of the spinning stations 1.1 to 1.4 takes place on the example of the spinning station 1.1.

In each of the spinning units 1.1 to 1.4, a polymer melt is supplied under pressure to a spinneret 9 via a melt feed 8 and extruded through a plurality of annular or rectangular nozzle bores of the spinneret 9. For this purpose, the melt feed 8 is preferably connected directly to a spinning pump (not shown here). The spinning pumps of the spinning units 1.1 to 1.4 could be supplied, for example, by an extruder with the melt. Below the spinneret 9, a cooling shaft 25 and a subsequent chute 13 is arranged in the cooling shaft 25 is a blow candle 10 is disposed within the filament bundle 12, which is connected to a Kübllunzuführung 11. By the blow candle 10, a cooling air is blown radially outward through the filament bundle 12.

At the end of the chute 13, a pre-preparation device 14 is arranged, through which the filament strands of the filament bundle 12 are prepared and brought together.

The filament bundles 12 produced in each case in the spinning stations 1.1 to 1.4 are combined to form a tow 15 and drawn off from the spinning device 1 by means of a drafting device 2.

Between the drafting 2 and the spinning device 1, a preparation device 3 is arranged with a plurality of preparation rollers 16, through which the tow cable 15 is guided.

The drafting system 2 consists of several consecutively arranged Streckwalzenduos 17.1, 17.2, 17.3 and 17.4. Each of the stretch roll ducks 17.1 to 17.4 each have two draw rolls 19, which are looped around several times by the tow 15. The draw rolls 19 of one of the stretch roll ducks 17.1 to 17.4 are driven at substantially the same peripheral speed. For the treatment of the tow 15, the drafting rollers of the drafting rollers 17.1, 17.2, 17.3 and 17.4 are driven at different peripheral speeds, so that in each case a differential speed acts in the treatment sections formed between the drafting rollers 17.1 to 17.4. Usually, in this case, a high differential speed for stretching the tow is set in a first treatment section between the drafting roller duo 17.1 and the drafting roller duo 17.2. Lower or no differential speeds are set in the subsequent treatment sections between the stretch roller duos 17.2 to 17.4.

Between the drafting roller duo 17.1 and 17.2, a treatment agent 18 is arranged in the intermediate treatment section. The treatment agent 18 has a steam for the treatment and heating of the tow 15. The structure and function of the treatment agent 18 will be explained in more detail below.

The drafting 2 is followed by a crimping device 4. The crimping device 4 is usually designed as Stauchkammerkräuseleinrichtung in which the tow is pressed by a conveyor into a stuffer box. As a subsidy rollers could eg in a 2D crimping or delivery nozzles are used in a 3D crimping. The crimping device 4 is the drying device 5, the tensioning device 6 and at the end downstream of the cutting device 7. The use of a drying device depends on the polymer type.

For the production of staple fibers, in the apparatus example according to FIG. 1, a polymer melt, for example a polyester or a polyamide or a polypropylene, is melted in the spinning device 1 by an extruder and fed via spin pumps to the respective spinning nozzles 9 of the individual spinning stations 1.1 to 1.4 under pressure. The spinnerets 9 have on their bottoms a plurality of nozzle bores which are arranged in a ring or a rectangle and each extrude a plurality of strand-like filaments. The emerging from the spinneret 9 filament strands are cooled after cooling in the cooling shaft 25 by a cooling air generated by the blow candle 10 and combined into a respective filament bundle 12. At the end of the chute 13, the filament bundle 12 is wetted by the pre-preparation device 14 with a spin finish and combined with the adjacent filament bundles to form a tow 15. For this purpose, the tow 15 is withdrawn via a drafting system 2 from the spinning device 1. Before the tow 15 reaches the first pair of draft rollers 17.1 of the drafting system 2, the tow 15 is again conditioned in the preparation device 3 by preparation rollers 16. However, preparation sticks can also be used for conditioning. Subsequently, a stretching of the tow 15 in the drafting system 2, wherein between the drafting roller duo 17.1 and 17.2, a differential speed is set, which leads to the stretching of the tow in the treatment section formed between the Streckwalzenduos 17.1 and 17.2. In this case, the tow 15 is additionally treated in the treatment section between the drafting roller duo 17.1 and 17.2 with a steam and heated.

For the treatment of the tow 15, the treatment means 18 arranged in the treatment section is formed according to the embodiment shown schematically in FIG. The treating agent 18 has a steam chamber 20 having an inlet opening 24 and an outlet opening 23. The inlet opening 24 and the outlet opening 23 face each other in the steam chamber 20 so that the tow 15 can be guided through the steam chamber 20 substantially in a straight run. Between the inlet opening 24 and the outlet opening 23 opens one or more nozzles 22 in the steam chamber 20. The nozzle 22 is connected to a steam source, not shown here. Through the nozzle 22, a pressurized steam 21 is ejected into the steam chamber 20. The nozzle 22 has a nozzle opening 26, which is preferably directed directly to the tow 15, so that the steam flow directly hits the tow 15. The steam 21 has a temperature of at least 80 ° C and a maximum of 200 ° C.

Due to the high energy of the steam jet within the steam chamber, a uniform and intensive treatment and heating of all filament strands within the tow 15 is achieved despite the tensioned filament strands of the tow 15. Thus, the intensive steam treatment of the tow '15 in the treatment section during the stretching of the tow advantageously affects the formation of a draw point. The tow cable 15 can hereby be withdrawn both cold and preheated from the draw godets 19 of the first draw roll end 17.1.

For further treatment of the tow 15, a further treatment is carried out via the draw rolls 17.2, 17.3 and 17.4 shown in FIG. In this case, a differential speed set to a further retightening of the tow 15 is preferably also effective between the draft rollers 17.2 and 17.3. The stretch roller duos 17.3 and 17.4 are preferably driven at the same peripheral speed to allow relaxation of the tow 15.

The stretched tow is crimped for further treatment in the crimping means 4. For this purpose, the crimping means 4 is preferably designed as a stuffer box crimping, in which the tow is pressed into a stuffer box by means of a conveying means. The crimped tow is then fed to a drying device 5 and fed by a tensioning device 6 with a defined tension of the cutting device 7. In the cutting device 7, the cutting of the tow 15 takes place in staple fibers.

To produce a staple fiber made of polyester, a spinning cable with a total titer of about 13,000 was first used in a product example with the spinning device 1. spun. The tow was at a speed of 200 m / min. withdrawn from the spinning device 1. To stretch the tow 15, the differential speed to a draw ratio of 4.7 was set between the pair of draft rollers 17.1 and 17.2. The differential speed between the stretch roll duo 17.2 and 17.3 resulted in a draw ratio of 1.1. There was no differential speed between the draft rollers 17.3 and 17.4. The tow was at a speed of 1,200 m / min. removed from the drafting system 2. For heat treatment of the tow 15, the draw rolls 19 of the first Streckwalzenduos 17.1 were at 80 ° C, the Streckwalzenduo 17.2 to 125 ° C, the Streckwalzenduo 17.3 heated to 170 ° C and the Streckwalzenduo 17.4 to 120 ° C.

The tow was at a speed of 1,220 m / min. crimped in the crimping device 4 and then dried and cut into staple fiber. In a first series of experiments, no further additional treatment was carried out in the treatment section between the first drafting roller duo 17.1 and the second drafting roller duo 17.2. In a second series of experiments then the treatment agent 18 in the treatment line used. For this purpose, a saturated steam at an overpressure of 6 bar was passed through the nozzle 22 into the steam chamber 20. The temperature of the steam was about 160 ° C.

After measuring the physical properties such as strength and elongation, a significant homogenization of the values was found. The scatter of the measured values could be improved by more than 20% up to 50% by the method according to the invention. In particular, a 50% improvement in the uniformity of the filament titer could also be achieved.

The structure of the embodiment of FIG. 1 for the device according to the invention is exemplary in the number and choice of treatment facilities. In principle, there is the possibility of introducing additional treatments and treatment stages. Essential for the process according to the invention and the device according to the invention is intensive steam treatment of the tow within the stretch and relax zone. Essential for the success of the method according to the invention is, in particular, an only slightly pre-oriented molecular structure of the filament strands.

In Fig. 3, a further embodiment of the device according to the invention is given. Here, Fig. 3 shows only the drafting system 2 with the total of four Streckwalzenduos 17.1 to 17.4. The treatment devices, not shown here, as well as the spinning device 1 and the cutting device 7 correspond to the preceding embodiments according to FIG. 1. In that regard, reference is made to the preceding description and at this point only the differences.

In the embodiment of the device according to the invention for carrying out a variant for the method according to the invention shown in Fig. 3, the treatment agent 18 in a treatment section between the Streckwalzenduo 1.7.3 and the Streckwalzenduo 17.4 arranged. This treatment section is essentially not used for drawing but for subsequent treatment of the spin tow 15. Surprisingly, however, an improved homogenization of the physical properties of the tow as well as an improved uniformity of the filament titer could also be achieved. In particular, it has been shown that setting a differential speed of 0 between the drafting roller duo 17.3 and 17.4 a higher homogenization could be achieved compared to a differential speed, which led to a flow of the tow in the treatment section. The intensity and uniformity of the steam treatment of the tow is thus significantly influenced by the tension state of the filaments.

The embodiment according to FIG. 4 is therefore particularly suitable for producing an optimized staple fiber in a single-stage process. The illustrated in Fig. 4 embodiment of the device according to the invention is also shown only in section through the drafting system 2. All other devices correspond to the embodiment of FIG. 1, so that reference is made to the previous description at this point.

In the exemplary embodiment illustrated in FIG. 4, a first treatment agent 18.1 is arranged in the first treatment path between the drafting roller duo 17.1 and the drafting roller duo 17.2. At the exit of the drafting system 2, a second treatment agent 18.2 is provided in the last treatment section between the drafting roller duo 17.3 and the drafting roller duo 17.4. The treatment means 18.1 and 18.2 have the structure shown in Fig. 2. In this case, the nozzle in the treatment agent 18.1 is oriented such that the steam jet flows in the running direction of the tow 15. In contrast, the treatment agent 18.2 has an embodiment in which the nozzle in the steam chamber against the direction of the Spinnkabels 15 flowing steam jet generated. However, it is also possible to carry out the treatment means 18.1 and 18.2 identical in their construction.

In the exemplary embodiments shown in FIGS. 1, 3 and 4, the formation of the treatment agent and the adjustment of the steam treatment depend essentially on the polymer to be processed. Thus, staple fiber can preferably be produced from polyester, polyamide or polypopylene.

LIST OF REFERENCE NUMBERS

1

spinner

1.1, 1.2, 1.3, 1.4

spinning unit

2

drafting system

3

preparation device

4

crimping

5

drying device

6

Zugstelleinrichtung

7

cutter

8th

melt feed

9

spinneret

10

blow candle

11

Cooling air supply

12

filament bundles

13

chute

14

Vorpräpariereinrichtung

15

tow

16

preparation rollers

17.1, 17.2, 17.3, 17.4

Streckwalzenduo

18

treatment agents

19

stretching rolls

20

steam chamber

21

steam

22

jet

23

outlet

24

inlet port

25

cooling shaft

26

nozzle opening

Claims (14)

1. Process for melt spinning and cutting of a tow for production of staple fibres in which a multiplicity of filament strands are spun from a polymer melt and merged to form the tow and in which the tow is continuously treated in a plurality of treating appliances after spinning and before cutting, at least one of the treating appliances feeding the tow for drawing over a plurality of draw rolls and the tow being treated with a fluid in a treating sector formed between draw rolls, characterized in that the tow is for treatment and heating in the treating sector fed into a vapour chamber and in that the fluid is fed into the vapour chamber by means of a nozzle as a vapour under an overpressure.
2. Process according to Claim 1, characterized in that the vapour jet generated by the nozzle is within the vapour chamber directed directly at the tow.
3. Process according to Claim 1 or 2, characterized in that the overpressure of the vapour is set to a value in the range from 2 to 12 bar.
4. Process according to any one of Claims 1 to 3, characterized in that the vapour is a saturated vapour or a superheated dry vapour and has a temperature in the range from 80°C to 200°C.
5. Process according to any one of Claims 1 to 4, characterized in that the tow is drawn to a draw ratio in the range from 0 to 6 by the differential speed of the draw rolls which acts on the tow within the treating sector.
6. Process according to any one of Claims 1 to 4, characterized in that the tow is fed with an overfeed into the treating sector by the differential speed of the draw rolls which acts on the tow within the treating sector.
7. Process according to any one of Claims 1 to 6, characterized in that the tow is additionally heated by at least one heated draw roll prior to the vapour treatment or after the vapour treatment or additionally by a second downstream vapour treatment.
8. Apparatus for carrying out the process according to any one of Claims 1 to 7, comprising a spinning appliance (1) for melt spinning of the tow (15), comprising a plurality of treating appliances (2, 3, 4, 5, 6) for treating the tow (15) and comprising a cutting appliance (7) for cutting of the tow (15), one of the treating appliances (2) comprising a plurality of draw rolls (19) for drawing of the tow (15) and, in a treating sector, a treating means (18) comprising a fluid (21), characterized in that the treating means (18) is disposed between adjacent draw rolls (19) in the treating sector and in that the treating means (18) is formed by a vapour chamber (20) and a nozzle (22) which empties into the vapour chamber (20) and which feeds the fluid as a vapour (21) under an overpressure into the vapour chamber (20).
9. Apparatus according to Claim 8, characterized in that the vapour chamber (20) has an inlet opening (24) and an outlet opening (23) through which the tow (15) is feedable, and in that the nozzle (22) directs a nozzle opening (26) at the tow (15) within the vapour chamber (20).
10. Apparatus according to Claim 8 or Claim 9, characterized in that the vapour (21) is formed by a saturated vapour or a superheated dry vapour which has a temperature in the range from 80°C to 200°C.
11. Apparatus according to any one of Claims 8 to 10, characterized in that the treating appliance (2) for drawing of the tow (15) comprises a plurality of draw roll couples (17.1 - 17.4) each consisting of two equally driven draw rolls (19), a first roll couple (17.1) being disposed downstream of the spinning appliance (1) to withdraw the tow (15) from the spinning appliance (1).
12. Apparatus according to Claim 11, characterized in that it is between adjacent draw roll couples (17.1, 17.2) that the treating sector in which a differential speed set between the draw roll couples (17.1, 17.3, 17.4) acts is formed, in that the first draw roll couple is followed by a plurality of further draw roll couples such that a plurality of treating sectors are formed, and in that the treating means (18) is disposed in at least one of the treating sectors.
13. Apparatus according to Claim 12, characterized in that there are a plurality of treating means (18.1, 18.2) which are each disposed in one of the treating sectors.
14. Apparatus according to any one of Claims 11 to 13, characterized in that the draw rolls (19) are heatable by at least one of the draw roll couples (17.1 - 17.4).

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