KR20050119675A - Method and device for producing post-stretched cellulose spun threads - Google Patents

Abstract

The invention relates to a method and device for producing Lyocell(R) fibers from a spinning solution containing water, cellulose and tertiary amine oxide. The spinning solution is extruded to form spun threads (10). The spun threads (10) are stretched and guided through a precipitation bath (16) in order to precipitate the cellulose. It has been surprisingly revealed that the strength of the Lyocell(R) fibers can be increased when the stretched fibers are subjected to a post- stretching in a post-stretching means. The post-stretched Lyocell(R) fibers have a wet modulus of at least 260 cN/tex.

Description

Method and apparatus for producing post-extended cellulose spinning {METHOD AND DEVICE FOR PRODUCING POST-STRETCHED CELLULOSE SPUN THREADS}

The present invention relates to a method and apparatus for producing lyocell spun threads from spinning liquids containing water, cellulose and tertiary amine oxides, and to the spinning produced by the method.

In the present production method, the spinning solution is first extruded into the spinning, then the spinning is stretched and passed through the settling tank, after which the cellulose of the spinning solidifies.

Spinning from tertiary amine oxides, such as N-methyl-morpholine-N-oxide, and cellulose dissolved in water (hereafter, "fiber" and "thread" Is used synonymously, also called the lyocell method, US-A-4 142 913, US-A-4 144 080, US-A-4 211 574, US-A- 4 246 221, US-A-4 261 943 and US-A-4 416 698. In these patent publications, McCorsley provides the basics of producing lyocell fibers in three stages: spinning the spinning liquid into the air gaps, stretching the extruded spinning out of the air gaps, and precipitating cellulose in the precipitation bath. The principle was first described.

After precipitating and solidifying the cellulose, spinning can be further processed through additional processing steps. For example, spinning can be washed, dried and treated or infused with additives. The yarn can be cut for the production of staple fibers.

The advantages of the lyocell method are in good environmental compatibility and excellent mechanical properties of the spun or woven fiber. Efficiency can be significantly improved through the development of several other methods developed by McCorsley.

Lyocell fibers have different cellulosic fibers in terms of their structure and their fabric properties, and in their production, for example DE-A-100 16 307, DE-A-197 53 806, DE-A-197 21 609, Different from those described in DE-A-195 11 151 and DE-A-43 12 219.

A particular problem with the lyocell method compared to the methods described in this patent lies in the high surface adhesion of freshly drawn spinning. When the spinnings come into contact with each other in air, they stick to each other, causing unsatisfactory fiber quality or even disturbing the spinning process, causing the spinning to restart. As described in DE-A-284 41 63, McCorsley used spinning in the air gap through the roll with the settler solution. This configuration is however not practical at high spinning speeds. Another set of improvements to the McCorsley method are therefore related to the means of reducing the surface adhesion of radiation in air, and to increasing the operational reliability of the production method, also known as spinning reliability.

One method that is well known in the art for the production of existing lyocell fibers or yarns is to cool the surface of freshly drawn yarns and blow cooling gas into the spinning of the air gap to reduce the adhesion of the yarns. Cooling winds of this type are described, for example, in WO-A-93 9230, WO-A-94 2818, WO-A-95 01470 and WO-A-95 01473. According to this publication, various types and embodiments of ventilation are used depending on the configuration of the extrusion opening through which the spinning solution is extruded.

Another problem with the production of lyocell fibers is the design of the settling bath. Due to the high spinning speed, spinning enters the sediment bath solution at high speed and carries the surrounding sediment bath solution together. As a result, a flow is created in the settling tank, which stirs the surface of the settling tank and applies mechanical pressure to the spinning to tear them as they enter the settling tank.

In order to make the surface of the settling tank with the extruded port of the annular structure as calm as possible, the spinning in DE-A-100 60 877 and DE-A-100 60 879 is carried out by means of specially crafted spinning funnels filled with the settling tank. Pass). With a spin funnel, the settling bath solution flows out with spinning at the lower end. This gravity flow can be used for stretching the radiation, as described in DE-A-44 09 609.

Extruded spheres consisting of rectangular cross sections, according to DE-A-100 37 923, achieved good results when the yarns formed essentially flat curtains and bent to the settling tank surface as flat curtains in the settling tank. Deflection elements are arranged in the settling bath in this structure.

Further processing of lyocell fibers after extrusion and coagulation of cellulose to obtain specific physical properties of spinning is described in less detail in patent documents.

In Lenzinger Berichte's April 94 edition, 37-40 pages basic article, "What's New in New Fibers of the Reocell Type?", Fiber structure and fiber properties are determined by molecular alignment during extrusion and stretching, the next step. Estimated. Here, the lyocell fibers are fibers described in DE-A-197 53 806, DE-A-197 21 609, DE-A-195 11 151, DE-A-100 16 307 and DE-A-43 12 219. And is crucially different.

This topic was adopted as a new patent document and actually carried out. For example, devices have been described in EP-A-823 945, EP-A-853 146, EP-A-100 23 391, in which coagulation of cellulose after post-extension of extruded spinning and in elongated spinning Afterwards they are kept free from tensile stress during further processing. This improvement stems from the idea that the physical properties of elongated and solidified radiations can no longer be modified.

One method that initially appeared to go in the opposite direction was proposed only in EP-A-494 851. In this publication, a method is described that is extruded essentially stress-free and the solidified cellulose is stretched. The point of this method is that no elongation occurs in freshly extracted radiation. Retrospective shaping is made possible through the method of EP-A-494 851, which is unusual for the lyocell method, and which is obviously no longer developed. The method of EP-A-494 851 is thus similar to the plastic deformation method, in which the initial material, the unstretched lyocell fiber, exhibits rubber-like consistency. The mechanical properties of the fibers produced according to the method of EP-A-494 851, however, do not meet the demands of the present age.

In DE-A-102 23 268, it has been described that if the wetting device is applied simultaneously in the stretching of the spinning, multistage settling and multistage stretching of the spinning will be realized. Although such means have reduced the need for treatment media and improved control of the precipitation process, the fabric properties are fundamentally unaffected by this type of retrostretch.

To change physical properties such as loop strength, tendency to fibrillation, and tensile strength of lyocell fibers, Lenzinger Berichte, Sep. 1994, page 31-35 “Amine Oxide Fundamental repertoires, such as those described in the article "Forming the Structure of Cellulose Fibers from Solution," are adopted. Thus, the fabric-related physical properties of lyocell fibers include variations in the cellulose concentration of the spinning solution (cf. WO-A-96 18760), changes in draw-off conditions (cf. DE-A-42 19 658) and By use of additives (cf. DE-A-44 26 966, DD-A-218 121, WO-A-94 20656) and modification of precipitation conditions (cf. AT-B-395 724). All these methods, however, allow only indirect control of the physical properties of lyocell yarns or fibers, resulting in very inaccurate process control.

1 is a schematic of a system for the production of post-extended lyocell fibers.

2 is a schematic representation of an embodiment of post-extension means.

3 is a schematic view of another embodiment of post-extension means.

Accordingly, it is an object of the present invention to improve the known methods and apparatus for producing lyocell fibers so that the physical properties of lyocell fibers, such as loop strength and tensile force, can be selectively influenced through an easy to control method.

This object is solved through a manufacturing process in which the elongated spinning mentioned in the introduction is post-extended and simultaneously heat treated.

With the device mentioned in the introduction, this object is solved, wherein the radiation extended by the first stretching means can pass through the second stretching means, post-extension during operation, and in the region of the second stretching means. A disposed heating device can be provided so that the radiation can be heated during post-extension during operation.

Surprisingly, the mechanical properties, here in particular the wet modulus, can be significantly improved over conventional lyocell fibers by first stretching in air and then post-solidification of the solidified spinning. Thanks to the heat treatment during post-extension, the initial experiments showed that the wet resistance slightly decreased, and the fibers were again slightly more elastic.

In contrast to the method and apparatus of DE-A-102 23 268, the heat treatment performed during post-extension assists in the critical improvement of the fabric properties of lyocell fibers.

Thus, the lyocell fibers produced by the present invention have a wet resistance of at least 250 cN / tex and a wet abrasion number of at least 18 per 25 fibers. According to the method of the present invention, a wet resistance value of at least 300 cN / tex or 350 cN / tex is obtained. Wet maximum tensile force elongation can be considered here as a relatively low value, for example up to 12%.

If the yarn is post-extended or extended with a higher specific tensile force, the wetting resistance of the final yarn and the fiber is higher. If post-elongation is performed with a specific tensile force of at least 0.8 cN / tex, advantageous performance of the process of the present invention may result in significantly increased wetting resistance compared to existing fibers. According to another embodiment where the specific tensile force during post-elongation is at least 3.5 cN / tex, higher wetting resistance values can be obtained.

In general, higher levels of wetting resistance are obtained if spinning solidifies before post-elongation.

The heat treatment may be carried out as a drying process, ie so-called stress drying, in a step after the washing or addition process. Alternatively, the heat treatment may take place in a steam or dry vapor atmosphere. Steam or dry steam can include additives that act on spinning to cause chemically secondary treatment.

Preferably, the heat treatment can be carried out in an oven, in which the stretched and solidified spinning can be post-extended with a specific tensile force between two godets. Here, a hot inert gas, for example hot air, or steam, or dry vapor passes through the surface of the galettes on which the radiation lies.

After post-elongation the radiation can be crimped because the natural crimping of the radiation is considerably reduced due to post-elongation. Here, it is also possible to treat with dry steam simultaneously with crimping.

Finally, the yarn can be cut for the production of staple fibers.

The invention will hereinafter be described in more detail with reference to the drawings on the basis of examples and on the basis of experimental results and experimental examples.

First, the basic structure of the system 1 for lyocell fiber production will be described based on the schematic representation of FIG. The system 1 of Figure 1 is used for the production of lyocell staple fibers.

Highly viscous spinning liquid containing water, cellulose and tertiary amine oxides such as N-methyl-morpholine-N-oxide are passed through the pipe system 2. The pipe system 2 is assembled in a modular manner from a fluid pipe section 2a of a particular length which is connected via a standard flange 2b.

The fluid pipe section 2a is provided with an internal temperature stabilization device 3, which is fixed to the fluid pipe section 2 at the point of the central flow of the spinning liquid, through which the spinning liquid in the pipe system 2 is circulated. closed-loop).

The temperature regulated fluid passes through an internal temperature stabilization device through a supply module 4 located between two adjacent fluid pipe sections, as indicated by arrow 5. The feed module 4 is essentially dimensioned to a standard flange and can be fitted to this flange for connection.

Slightly apart, burst modules 6 such as disposed between the fluid pipe sections 2a replace the feed module 4. The explosion module 6 basically shows the same design as the supply module. They are fixed with an explosion element, not shown in FIG. 1, which explodes so as to divert pressure outside when a certain pressure is exceeded in the pipe system 2. Explosions can occur, in particular, during the natural exothermic reaction of the droplets due to over-aging or overheating. The spinning liquid spouted out during the explosion can be collected in the collecting container 7, where it can be recycled or removed.

The spinning liquid passes through a pipe system 2 to the spinning head 8. The spinneret 8 is secured with a spinneret 9 comprising a number of extruders, typically several thousand extruders (not shown). The spinning solution is extruded into the yarn 10 through the extrusion port. The arrangement of the extruder in the spinneret 9 can be circular, annular or rectangular; In the following references only the rectangular layout is given as an example.

In order to achieve the best spinning conditions at the extrusion port, the temperature stabilization device 3 of the pipe system 2, as well as the fluid pipe section 2a or the supply module 4 or the explosion module 6, through a standard flange Similarly, additional plant arrangements can be provided which can be easily connected. For example, a pressure equalizing container 11a is disposed in the pipe system 2 to compensate for pressure changes and volume flow changes in the spinning liquid in the pipe system 2 by changing its internal volume, thereby providing a spinning head ( It is possible to ensure a constant extrusion pressure in the extrusion port of 8).

In addition, a mechanical filter device 11b having a back-purgable filter element (not shown) may also be provided in the pipe system 2. The filter element exhibits a fineness between 5 μm and 25 μm. Thanks to this filter device 11b, when using continuous or alternative working buffer storage vessels (not shown), discontinuous filtration occurs.

The spinning is elongated by tensile pressure as freshly pulled spinning 10 passes through the extruded edge on the air gap 12. In the air gap 12, the cooling gas flow 13 produced by the blower device 14 is directed to the radiation 10. The temperature, humidity and composition of the cooling gas stream 13 can be adjusted to a predetermined or specified variable value by the climatic device 15.

The coolant gas flow 13 acts on the radiation 10 at a distance from the spinneret 9 and exhibits a velocity component in the extrusion direction E so that the radiation can be extended by the coolant gas flow 13. . The cooling gas stream 13 is turbulent in order to enable good heat transfer.

After passing through the air gap 12, the spinning 10 enters the settling tank 16. In order to prevent the surface of the settling tank 16 from being agitated, the cooling gas stream 13 is properly spaced from the surface 17 of the settling tank, so as not to hit the surface.

In the settling tank 16, the spinning 10 is bent into a bundle unit 19 outside the settling tank by means of a deflector 18, basically in the form of a roll, so that they pass through the surface 17 of the settling tank again. do. The bundle unit 19 is rotationally driven and exerts a tensile force on the spinning 10 which acts towards the extrusion port of the spinneret 9 via a diverter 18 as first stretching means, which stretches the spinning. Of course, the diverter 18 can also be driven as the stretching means.

In order to stretch the yarn 10 as smoothly as possible, a tensile force may also be produced only by the cooling gas flow 13 as the first stretching means. This has the advantage that the tensile force is transmitted to the yarn 10 as a frictional force distributed and acting throughout the yarn surface.

From the bundle unit 19, the yarns 10 are combined into a yarn bundle 20. Then, the spinning 10, which is still wet with the settling bath solution 16 and merged with the spinning bundle 20, is placed under pressure on the conveyor apparatus 21 and hardly given a tensile force thereon. Is moved to the state. While the spinning is carried on the conveyor apparatus 21, complete or almost complete solidification of the cellulose of the spinning takes place without any possible pressure.

The conveyor apparatus 21 may be a vibroconveyor, as shown in FIG. 1, which carries a spinning bundle 20, or optionally simultaneously carrying a plurality of spinning bundles 20, in a conveying direction. It carries by vibration to F. The vibration of the conveyor apparatus 21 is indicated by the double arrow 22. Thanks to the back and forth movement 21, the bundle 20 is placed on the conveyor device in alignment. Instead of the vibrating conveyor 22, other conveying devices, such as a plurality of continuously aligned wheels, may be used at circumferential speeds that are nearly constant or decrease in the conveying direction.

While being transported on the conveying device 21, a variety of treatments can be made to the spinning bundle 20, for example by means of a sprinkling system 23 which spouts treatment media with the spinning bundle 20, for example. (20) can be washed once or several times, dried and cleaned.

The spinning bundle 20 is lifted from the conveyor apparatus 21 by the stub 25 to be transferred to the second post-extension unit 26, and the fully solidified spinning is post-extended through it.

In the embodiment of FIG. 1, post-elongation occurs concurrently with drying in the form of heat treatment or pressure drying, since this would most preferably affect the physical properties of the spinning 10. Without post-extension heat treatment, slightly worse, but still significantly superior properties over the prior art are obtained.

The second post-extension means 26 is also provided immediately after the bundling unit 19, ie between the conveyor apparatus 21 and the settling tank 16, so that the post-extended spinning may undergo another treatment process first. It may be.

In order to perform the heat treatment, the post-extension means 26 at the inlet of the spinning 20 is provided with a heating device 27 which causes the spinning bundle 20 to reach a certain temperature and at the same time dry at least the surface of the spinning bundle. can do.

In the post-extension means 26, the radiation passes between the two deflections 28, 29 which are driven to exert a predetermined post-extension tensile force Z _N between the spun bundles 20. This tensioned spinning bundle is maintained at a certain high temperature and during post-extension, by hot inert gas, such as air, or by steam, for example dry steam, and as an expander or other chemical fiber treatment agent, arrows 30 As indicated by). Gauges 28 and 29 may also be heated to assist the drying action.

Because of the post-extension, the spinning bundle 20 shows reduced crimping compared to conventional fibers, so that it is crimped in a stuffer box 31. The spinning bundle 20 is then cut by the cutting device 32. If it is desired to produce endless fibers, crimping and / or cutting can be omitted.

After crimping and cutting, the crimped staple fibers can be conveyed in any direction in the form of an endless cable 33 crimped on the conveyor device 34 for further processing steps.

2 shows a schematic diagram of an embodiment of the post-extension device 26. In this embodiment, the renal extension is in the form of pressure drying.

As already shown in FIG. 1, the post-extension device 26 has two hooks 28, 29, in which the bundle 20 is tensioned or at least 0.8 cN / tex, preferably at least It is driven to elongate between the fins with a predetermined tensile force Z _N of 3.5 cN / tex. In this regard, the gouge 29 positioned backwards relative to the conveying direction F can rotate at a predetermined speed higher than the gouge 28 positioned forward with respect to the conveying direction F, where the tensile force Z _N is basically A slippage may be determined between the striatum 29 and the spinning bundle 20 that wraps around the gallette.

Shrinkage of the spinning bundle 20 during drying is also available for its elongation: since the spinning bundle shrinks during the drying process, if this shrinkage is not compensated by the rotational speeds of the wheels 28 and 29 Then, kidney or post-extension occurs. In this way, post-elongation may also occur when the gallettes 28, 29 basically rotate at the same or only slightly different speeds.

One or two furnaces 28, 29 are provided with a surface 30 through which at least gas can pass, through which hot inert gas, vapor or dry vapor is forced out of the interior spaces of the furnace 28, 29. , And passes through the spinning bundles (20, 29).

Alternatively or additionally to the looping shown in FIG. 2, there are rolls 28a and 29a which can also pass steam and which rotate actively or passively with high pressure, as shown schematically in FIG. 3. As such, it may be disposed at a position facing each of the grooves 28 and 29. Rolls 28a and 29a also have a permeable surface through which inert gas or vapor can escape. Large drums may be provided instead of rolls.

It is also possible to use large drums or suction drums with perforated surfaces through which hot air can pass out instead of the drums 28, 29.

In the region between the hips 28 and 29, hot air or other hot inert gas, steam or dry vapor passes between the gas or the spinning bundle 20. The effect of post-kidney was demonstrated in a series of experiments.

Experiments were performed with a bundle of 79,270 single radiations and a total titer of 110,978 dtex, corresponding to a single titer of 1.4 dtex. Table 1 shows the overall experimental results.

In the first series of experiments (Experiments 1-7), the spinning bundles were dried at 73 ° C. for 15 minutes under various conditions.

In Experiment 1 the spinning bundle was dried without tension.

In Experiment 2, the spinning bundle was dried under tension, wetted again, and dried again under tension. To do this, the spinning bundle passed through two eyes 50 cm apart, with 19 kg of load at each end during drying.

In Experiment 3, the spinning bundles were dried under tension, and after being wet again, dried under tension. To do this, the spinning bundle passed through two eyes 50 cm apart, with a load of 38 kg at each end during drying.

In Experiment 4, the spinning bundle was pinched between two tongs 38 cm apart and then dried.

In Experiment 5, the wet spinning bundles were dried under tension. The radial bundle passed through two eyes 50 cm apart, with a load of 9 kg at each end.

In Experiment 6, the wet spinning bundles were dried under tension. The spinning bundle passed through two eyes 50 cm apart, with a load of 19 kg at each end.

In Experiment 7, the wet spinning bundles were dried under tension. The spinning bundle passed through two eyes 50 cm apart, with a load of 38 kg at each end.

In a second series of experiments, the spinning bundles were treated with caustic soda (NaOH) solution before drying. First, the spinning bundles were treated with 5% NaOH solution for 5 minutes and then washed with fully deionized water. The NaOH solution was neutralized with 1% formic acid solution and then washed again with fully deionized water.

The spinning bundle was then dried at 73 ° C. for 30 minutes in a dryer.

In Experiment 8, the spinning bundles were dried without tension.

In Experiment 9, the spinning bundle was dried under tension, then wet again and dried under tension. To do this, the bundle of bundles passed through two eyes 50 cm apart, with a load of 19 kg at each end.

In Experiment 10, the spinning bundle was dried under tension, then wet again and dried under tension. To do this, the bundle of bundles passed through two eyes 50 cm apart, with a load of 38 kg at each end.

In Experiment 11, the spinning bundles were pinched between two tongs 38 cm apart and then dried.

In Experiment 12, the wet spinning bundles were dried under tension. The spinning bundle passed through two eyes 50 cm apart, with a load of 9 kg at each end.

In Experiment 13, the wet spinning bundles were dried under tension. The spinning bundle passed through two eyes 50 cm apart with a 19 kg load at each end.

In Experiment 14, the spinning bundles were dried under tension. The spinning bundle passed through two eyes 50 cm apart, with a load of 38 kg at each end.

With dry spinning bundles, the titer, denier related maximum tensile force, maximum tensile force elongation, denier related wet maximum tensile force, wet maximum tensile force Wet maximum tensile force strain, denier related loop maximum tensile force, wet modulus and wet abrasion number were measured. The experimental details of performing these are as follows.

Titer was measured according to DIN EN ISO 1973. (Wet) maximum tensile strength and (wet) maximum tensile strength were measured according to DIN EN ISO 5079. Loop maximum tensile force was measured according to DIN 53843 Part 2.

In accordance with DIN EN ISO 1973, wetting resistance was measured for fiber bundles that could be used. The process was in accordance with the experimental design ASG N 211 of Alceru Schwarza GmbH. Experiments for the measurement of wet resistance were performed with a tension test machine with constant elongation and low displacement power measurements. The length of clamping the fiber bundle was 10.0 mm ± 0.1 mm. The pretension force related denier of one titer above 2.4 dtex was 2.5 mN / tex ± 0.5 mN / tex. For a titer of up to 2.4 dtex, a pretension mass of 50 mg was used. Elongation was 2.5 mm / min mean wet elongation when tearing up to 10%, 5.0 mm / min mean wet elongation when tearing 10-20%, and tearing above 20%. , Average wet elongation was 7.5 mm / min.

Five spinning bundles were placed on a flat plate containing a humectant solution for at least 10 seconds, before which a total amount of tension was applied to one end of each spinning bundle. The experimental sample placed for the relatively longest time was removed from the dish and used for the tension experiment, and after each experiment a new experimental sample was placed in the dish for wetting.

The clamped spinning bundles were subjected to a total amount of tension in the tension test machine, at both ends of the bundle, while the force was in effect, and then the dip tank with the lower tongs closed and the humectant solution in place. Raised so that the liquid surface is as far as possible from the upper tong to reach a height that does not touch it. The distance between the tongs increased continuously until the elongation mentioned above reached 5%. At this point, the movement of the lower tongs was stopped, and the wet tension was measured in mN to the first decimal place.

Wet resistance M was calculated from the wet tensile force F in millinewtons and the arithmetic mean of the average denier T in tex units calculated for the tested spun fiber, described in units of mN / tex rounded to an integer: M = F / (T * 0.05)

Wet wear counts were measured with a fiber wet wear tester FNP from SMK Prazisionsmechanik Gera GmbH. The wet wear water is the number of revolutions of the wear shaft until the fibers fixed under the predetermined electric strength in the wet wear test apparatus break. The electric field weight to the titer of 1.2 to 1.8 dtex was 70 mg. The rotational speed of the wear shaft was 400 rpm and the contact angle was 45 degrees. The wear shaft was fixed to the fabric tube.

According to Table 1, from the experiments, there was a surprising increase in the wet wear as well as the wet resistance of the post-extended fibers compared to the post-extended conventional fibers (Experiment 1). Spinned bundles that were dried without tension, then wetted again and dried again under tension (Experiments 2, 3, 9, and 10) were subjected to a load of 38 kg (corresponding to 3.12 cN / tex). Compared to the load (corresponding to 1.6 cN / tex), the number of wet wear decreased slightly and the wet resistance increased. The heavier the load, the more wetting resistance could be obtained than the wet cloth bundle dried under tension in Experiments 5-7, 12-14.

The maximum tensile force, measured on wet and dry, did not change basically compared to the fiber of Experiment 1, which was not post-extended. It can be concluded that the post-extended fibers are more brittle and more flexible than the non-extended fibers from reduced maximum tensile strength and reduced loop maximum tensile force in connection with the wet resistance and the wet wear water.

Thus, the experiments showed that fibers with improved wet resistance and improved wet wear can be produced by post-extension or pressure drying.

Fibers with improved wet resistance and improved wet wear water can be produced by post-extension or pressure drying by the process of the invention.

Claims (17)

As a method for producing lyocell fibers from a spinning solution containing water, cellulose and tertiary amine oxides, Extruding the spinning solution into yarn 10; Stretching the yarn (10); The method of carrying out the step of passing the spinning through the settling tank 16, wherein the method comprises: A heat treatment of the elongated yarn 10 simultaneously with post-elongation after passing through the settling tank 16. The method of claim 1, comprising the step of solidifying the cellulose in the yarn (10) prior to stretching. The process for producing lyocell fibers according to claim 1 or 2, characterized by post-extension with a tensile force of at least 0.8 cN / tex. 4. The method of claim 3, characterized by post-extension with a tensile force of at least 3.5 cN / tex. 5. The method of claim 1, comprising treating the spinning with a hot inert gas during heat treatment. 6. 6. The method of claim 1, comprising treating the spinning with steam during heat treatment. 7. Method according to any one of the preceding claims, characterized in that it comprises passing an air gap (12) before passing the spinning (10) through the settling tank (16). . 8. A method according to claim 7, comprising blowing a cooling gas stream (13) into the yarn (10) in an air gap (12). 9. The method of claim 1, wherein the spinning comprises conveying without tension between stretching and post-extension steps. 10. 10. The method according to any one of the preceding claims, comprising crimping the post-extended yarns (10). The method of any one of claims 1 to 10, comprising cutting the post-extended spin to form staple fibers. Apparatus (1) for producing spinning (10) from spinning liquids containing cellulose, water and tertiary amine oxides, spinnerets (9), cellulose, which can be extruded to become spinning (10) during operation By a settling tank 16 through which the radiation passes during operation, by the first stretching means 13, 18, 19 and the first stretching means 13, 18, 19 for extending the radiation during operation. In a device having second elongation means (28, 29) for post-extending elongated radiation during operation, A radiation production apparatus, characterized in that it is arranged in the zone of the second elongation means 28, 29, thereby allowing heating devices 27, 30 to be heated during post-extension elongation during operation. . A lyocell fiber produced according to the method of any one of claims 1 to 11, wherein the lyocell fiber has a wet resistance of at least 250 cN / tex and a wet wear number of at least 18 per 25 fibers. The lyocell fiber of claim 13 having a wetting resistance of at least 300 cN / tex. 15. The lyocell fiber of claim 14 having a wet resistance of at least 350 cN / tex. The lyocell fiber according to any one of claims 13 to 15, wherein the wet tensile strength is up to 12%. The lyocell fiber according to any one of claims 13 to 16, wherein the number of wet wears per 25 fibers is at most 25.