WO2005116309A1

WO2005116309A1 - Method for producing continuous molded bodies and spinning head

Info

Publication number: WO2005116309A1
Application number: PCT/EP2005/002087
Authority: WO
Inventors: Stefan Zikeli; Friedrich Ecker
Original assignee: Zimmer Aktiengesellschaft
Priority date: 2004-05-13
Filing date: 2005-02-28
Publication date: 2005-12-08
Also published as: WO2005116309A8; DE102004024065A1

Abstract

The invention relates to a method and a spinning head for producing continuous molded bodies from a spinning solution that contains water, cellulose and tertiary amine oxide. The spinning solution is first extruded to give continuous molded bodies (2), said continuous molded bodies (2) are guided through an air gap (26) in a spinning zone (32), thereby stretching them, and are then guided through a precipitation bath (28). The aim of the invention is to combine large air gap lengths with high spinning density and simultaneous high reliability of spinning. For this purpose, at least one gas flow (30, 44) flowing from outside the spinning zone (32) into the outlet area (32') directly adjacent to the extrusion openings (43) is blocked.

Description

Process for the production of continuous moldings and spinning head

The invention relates to a process for producing continuous moldings from a spinning solution containing water, cellulose and tertiary amine oxide, in which the spinning solution is first extruded to form continuous moldings, then the continuous moldings are passed through an air gap in a spinning zone, stretched and then passed through a precipitation bath ,

The invention also relates to a spinning head for spinning continuous moldings from a spinning solution flowing through the spinning head containing water, cellulose and tertiary amine oxide, with extrusion openings which adjoin a spinning zone in the direction of extrusion.

The basics of the production of continuous moldings, such as lyocell threads or fibers, from a spinning solution containing cellulose, water and tertiary amine oxide, preferably N-methylmorpholine-N-oxide (NMMNO), are described in US Pat. No. 4,246,221. Accordingly, the production of continuous moldings essentially takes place in three steps: First, the spinning solution is extruded through a large number of extrusion openings to form continuous moldings. Then the continuous molded articles are stretched in an air gap, whereby the desired fiber strength is set, and then passed through a precipitation bath, where they coagulate.

The advantage of lyocell threads or fibers lies on the one hand in the particularly environmentally friendly manufacturing process, which enables the amine oxide to be almost completely recovered, and on the other hand in the excellent textile properties of the lyocell fibers.

The problem with the method, however, is that the freshly extruded continuous moldings have a strong surface tack, which only decreases when they come into contact with a precipitant. When the continuous moldings are passed through the air gap, there is a risk due to the surface stickiness that the continuous moldings touch each other, stick to one another and clump together. The danger of sticking can be adjusted by adjusting the operating and process parameters such as tension in the air gap, air gap height, thread density, viscosity, temperature and Spinning speed can be reduced. However, if such bondings occur, this has a negative impact on the manufacturing process and the fiber quality, since bondings can lead to tears and thick spots in the continuous mold cores. In the worst case, the manufacturing process has to be interrupted and the spinning process started again, which causes high costs.

Nowadays, manufacturers of continuous moldings, such as the yarn manufacturers as part of the textile processing chain, are required to be free of sticking, i.e. the individual stacks of filaments must not be glued together, as this would lead to irregularities in the yarn thickness, for example.

The cost-effectiveness of producing Lyocell fibers, mainly staple fibers and filaments, can be improved if the distance between the extrusion openings is reduced. A smaller distance, however, increases the risk of sticking in the air gap due to accidental contact with the continuous moldings.

In order to improve the mechanical and textile properties of Lyocell fibers, it is again advantageous if the air gap is as large as possible, since with a large air gap the stretching of the threads is distributed over a longer length and tensions in the continuous moldings are more easily reduced after their extrusion can. However, the larger the air gap, the lower the spinning security or the greater the risk that the continuous moldings will touch, stick and that the manufacturing process will have to be interrupted due to spunbond gluing.

Based on the principles described in US Pat. No. 4,246,221, there are some solutions in the prior art which attempt to improve both the economy and the spinning safety in the production of continuous moldings from a spinning solution containing cellulose and tertiary amine oxide.

A method is described in US Pat. No. 4,261,941 and US Pat. No. 4,416,698 in which the continuous moldings are brought into contact with a non-solvent immediately after the extrusion in order to reduce the surface tack. The continuous moldings are then passed through a precipitation bath. The additional wetting of the Endless moldings by the non-solvent before being passed through the precipitation bath reduce the risk of sticking, but are too complex and expensive for commercial use.

Another way to increase the spin density, i.e. the number of extrusion openings per unit area is described in WO 93/19230: Accordingly, the continuous moldings should be cooled immediately after the extrusion by blowing horizontally across the direction of extrusion with a cooling gas stream. This measure is intended to reduce the surface stickiness of the continuous moldings and to lengthen the air gap. For the effect described in WO-A-9319230, it is essential that the continuous molded bodies are exposed to the gas stream immediately after the extrusion and are cooled by the gas stream at this point.

A further development of WO 93/19230 is described in WO 95/01470. In order to enable uniform blowing of the continuous molded articles immediately after they exit the extrusion openings, an annular nozzle is used in the device of WO 95/01470, in which the extrusion openings are distributed over a substantially circular surface. The blowing with a cooling air flow takes place horizontally outwards in the radial direction through the center of the ring nozzle and the circular ring of the continuous moldings. The air flow is kept laminar at its outlet from the blowing device. WO 95/04173 relates to a design development of the ring nozzle and the blowing device, which is essentially based on the device of WO 95/01470.

As an alternative to the ring nozzle arrangements, segmented rectangular nozzle arrangements have also been developed, ie nozzles in which the extrusion openings are arranged essentially in a row on a substantially rectangular base area. Such a segmented rectangular nozzle arrangement is shown in WO 94/28218. In this device, blowing with a cooling air flow takes place parallel to the liquid level of the precipitation bath, the cooling air flow extending along the longer side of the rectangular nozzle arrangement. After passage through the continuous molded body, the cooling air flow is sucked off again in the device of WO 94/28218. The extraction is necessary so that the air flow can be directed through the entire cross section of the air gap. In WO 98/18983 the concept of rectangular nozzles with extrusion openings arranged in rows has been further developed. WO 98/18983 is based on the fact that the extrusion openings in a row are spaced differently than the rows of the extrusion openings among themselves.

The problem with all of the above-mentioned methods and devices is that the spun threads do not have a uniform spinning quality and the cost-effectiveness of the Lyocell method is in need of further improvement.

In view of this problem, the invention has for its object to provide a method and an apparatus by means of which large air gap lengths with a high spinning density can be combined with a low level of design complexity and at the same time high spinning reliability and spinning quality.

This object is achieved according to the invention for the method mentioned at the outset by blocking at least one gas stream flowing from outside the spinning zone in the outlet region immediately adjacent to the extrusion openings.

For the spinning head mentioned at the outset, this object is achieved according to the invention in that the spinning head comprises at least one shielding means by which a gas stream flowing from outside the spinning zone into the outlet area immediately adjacent to the extrusion openings is blocked.

These solutions surprisingly lead to a high spinning density and a long air gap with high spinning security and spinning quality. According to the invention, the continuous molded articles are prevented from being exposed to a gas stream immediately after the extrusion.

One reason for the surprising effect of the solution according to the invention could be that the continuous molded bodies expand in the exit area immediately after the extrusion. The widening of the continuous moldings, which is referred to as the barus effect, results from a relaxation of the continuous moldings after extrusion. In the expansion area, the chain molecules in the continuous form bodies have none Orientation on and are largely anisotropic. If, as in WO-A-93 19280, the continuous moldings are exposed to a gas stream and cooled in this sensitive area, this anisotropic orientation state is frozen and the textile-physical properties of the spun threads deteriorate. Such flows are blocked by the method according to the invention and the spinning head according to the invention, the continuous shaped bodies are only exposed to the gas flow when the molecules in the continuous shaped bodies have aligned. A cooling in front is prevented by the shielding agent.

One reason for flows that run from the outside into the exit area lies in the conventional spinning process itself: the spinning speed in the lyocell process used industrially is so high that the air surrounding the exit area of the continuous molded articles is swirled and carried away by the rapidly passed continuous molded articles. This also creates a flow into the outlet area. This flow is intensified by the fact that large quantities of water evaporate when the continuous molded articles, which have a temperature of over 100 ° C., exit the spinning head. The water vapor emerging from the endless mold bodies flows at the extrusion speed in the direction of extrusion, is swirled and additionally entrains air with the endless mold bodies. In this way, currents are formed which can run into the outlet area of the continuous molded bodies. In the method according to the invention and the spinning head according to the invention, this compensating flow is blocked in the area immediately after the endless molded bodies have emerged from the spinning head.

In WO 93/19230, the gas stream is actively generated and directed onto the continuous molded articles, so that they are cooled immediately after the extrusion. In order to also improve the spinning quality of continuous moldings which, as in WO 93/19230, are exposed to a flow generated by a blowing device in the air gap, the gas flow of a blowing device or the shielding agent can be blocked in a particularly advantageous development of the method according to the invention be arranged in the region of the gas flow from the blowing device. Due to the advantageous development of the method according to the invention, flows caused directly by the blowing device, such as the cooling gas stream of WO 93/19230, in the area immediately after extrusion, in the area of the barus effect, blocked.

In order to achieve this advantage for a spinning head according to the invention, which comprises a blowing device, which is generated by the operation of a flow directed towards the endless mold, in an advantageous embodiment, at least one flow caused by the blowing device can be blocked in the shielding area. The easiest way to achieve this is to arrange the shielding means at least between a flow opening of the blowing device and the spinning zone. Furthermore, the shielding means can be arranged in the gas stream from the blowing device.

In an advantageous development of the method according to the invention, the flow extending from the outside of the spinning zone into the outlet area can be blocked in at least the expansion area of the continuous moldings, in which the continuous moldings expand in the extrusion direction after extrusion due to the Barus effect. This has the advantage that the widening area, which is particularly sensitive to the extrusion process of the continuous moldings, is completely protected from the gas flow, and the spinning quality of the continuous moldings is thereby further improved compared to the known methods. In order to ensure flow protection in the expansion area in the spinning head according to the invention, in an advantageous embodiment the shielding area can also include the expansion area of the continuous moldings.

Furthermore, the at least one shielding means can be arranged on the side of the spinning head facing the air gap and can extend in the extrusion direction away from the spinning head. As a result, the shielding means can be arranged at a short distance from the continuous moldings without the risk that the continuous moldings will touch the shielding means during operation and the spinning process will thereby be negatively influenced. The shielding means can be repeatedly detachably attached to the spinning head with fastening means such as screws. The position of the shielding means in relation to the spinning zone is preferably adjustable in order to enable adaptation to different spinning conditions. For this purpose, adjustment means such as elongated holes for screws and / or guides can be used, which prevent the shielding means from moving allow the extrusion openings to be provided. Alternatively, it can also be attached to the spinning head by welding, soldering or gluing.

A surprisingly effective blockage of the gas flow with a simple construction can be achieved if the at least one shielding means is designed in the form of a fence, flow guide plate or spoiler that at least partially delimits the outlet area. The shielding agent can e.g. be designed as a flat material web, for example as a plastic or sheet metal strip or as a doctor-like plastic plate. The shielding means can be designed such that the shielding means is not guided parallel to the spun threads, but can be directed outwards or inwards. The angle can be in the range - 30 ° or + 30 °. The shielding means can also be embodied in a correspondingly "bulbous" manner. The shielding means can also be provided with trace heating on the outside. The heating can expediently be designed as a soldered-on electric heating.

In a further advantageous embodiment, the shielding means can extend from the spinning head in the extrusion direction at least to the expansion area of the endless molded body. The height of the shielding means can be, for example, between 10 mm and 20 mm, preferably 15 mm. This has the advantage that the shielding agent protects the sensitive area of the endless body immediately after extrusion. Subsequent to this area, cooling by the gas flow remains possible. In particular, the height of the shielding means can be dimensioned such that the widening region of the endless molded body is in the slipstream of the shielding region with respect to the gas flow.

In addition to the described method and the described spinning head, the present invention also comprises a spinning installation or lyocell installation for producing continuous moldings from a spinning solution, with a mixing device in which water, cellulose and tertiary amine oxide are mixed to form the spinning solution during operation, with a spinning head , an air gap and a precipitation bath. In order to ensure a large air gap length with a high spinning density and at the same time high spinning security, it is provided according to the invention that the spinning head is designed according to one of the above-described embodiments. In the following, embodiments of the invention are described by way of example with reference to the drawings. The features as they are attributable according to the above individual advantageous embodiments of the invention can be combined with one another as desired and can also be omitted.

Show it:

1 shows an embodiment of a spinning installation according to the invention for producing continuous moldings according to the Lyocell process in a schematic representation, the inventive method being executable by the embodiment;

2 shows a schematic representation of an embodiment of a spinning head according to the invention;

3 shows a schematic illustration of an endless molded body immediately after extrusion;

Fig. 4 is a schematic representation of a further embodiment of a spinning head according to the invention.

1 shows a spinning plant 1 for the production of continuous moldings 2, for example spun threads, from a spinnable cellulose solution containing water, cellulose and tertiary amine oxide.

First, cellulose in the form of sheets or plates 3 and / or rolls 4 is fed to a pulper 5 in batches. In the pulper 5, the cellulose 3, 4 is broken up with water, symbolically represented by the arrow 6, and a cellulose suspension, preferably still without a solvent or amine oxide, is formed. Enzymes can be added to homogenize and stabilize the cellulose suspension.

The amount of water 6 added is determined depending on the water content of the cellulose. The water content of the cellulose used is typically between 5 and 15 percent by mass. This fluctuation range is equal change in the addition of water compensated so that the water content of the cellulose suspension or the liquor ratio solid / liquid remains approximately constant or reaches a freely selected value.

From the pulper 5, the cellulose suspension is passed through a thick matter pump 7 via a line system 8 to a pressing device 9, the cellulose suspension of water and cellulose preferably being kept in a temperature range from 60 to 100 ° C.

In the pressing device 9, the cellulose suspension produced by the pulper 5 is pressed, for example, by rotating rollers 10. The squeezed water or press water 11 is collected by a collecting element 11 'and returned to the pulper 5 at least in part as water 6 by a conveying means 12, by an optional filter device 13 and by a mixing device 14. The pressing device 9 can also be provided with a suction device (not shown) with which excess water is sucked out of the cellulose suspension. In this embodiment, the extracted water, like the press water, is at least partially returned to the pulper 5.

The filter 13 may include one or more surface filters, depth filters, membrane filters, plate filters, gap filters, separators, centrifuges, hydrocyclones, belt filters and vacuum belt filters, candle filters, filter presses, rotary filters, backwash filters and multilayer filters. In addition, the press water 11 can be treated osmotically in the filter 13; alternatively or additionally, metal ions and particles can be filtered out of the press water 11 or metal-binding additives can be supplied to the press water 11.

The respective proportions of the recycled treatment medium 11 and the freshly supplied treatment medium 15, for example fresh water, in the water 6 supplied to the pulper 5 are set via the mixing device 14. In addition, the proportion of the treatment medium 11 is set by the mixing device 14, which is guided or discharged from the system 1 through a waste water line 16. The mixing device 14 can comprise, for example, a reusable valve or several valves. The mixing device 14 is controlled by a control device 17 so that, based on an output signal from the control device via at least one control line 18, the proportions of the press water 11 and the fresh water 15 in the water 6 supplied to the pulper 5 can be set to variably predeterminable values. After pressing, the cellulose suspension is transported further through the line system 8 into a stirring or conveying means 19, in which a shear stress acting on the cellulose suspension is generated via a stirring or conveying tool 20, such as screws, paddles or blades. No annular layer mixers can be used for the stirring and conveying means 19, such as those that come from DRAIS Misch- und Reaction Systems and are sold under the name CoriMix®. The annular layer mixers are only used to moisten or impregnate dry cellulosic materials that are not used in the process described here.

In the area of the shear stresses of the agitating and conveying means 19, in the so-called shear zone, a treatment medium such as tertiary amine oxide, in particular N-methylmorpholine-N-oxide, in aqueous form of the cellulose suspension with a molar ratio NMMNO / H ₂ O between a line 21 1: 1 and 1: 2.5 supplied as a solvent for the cellulose. In addition, additives such as stabilizers and enzymes, organic additives, matting agents, alkalis, solid or liquid alkaline earths, zeolites, finely powdered metals such as zinc, silver, gold, platinum can be used in the shear zone for the production of antimicrobial and / or electro- or thermally conductive fibers during and after the spinning process, and / or dyes are added to the cellulose suspension. The concentration of the additives can be controlled in the range from 100 to 100,000 ppm based on the fiber product.

The concentration of the NMMNO supplied depends on the water content of the cellulose 3, 4 currently in the cellulose suspension. The stirring or conveying means 19 acts as a mixer in which the tertiary amine oxide is mixed with the cellulose suspension and the cellulose solution is prepared. Then the cellulose solution mixed with NMMNO is fed via the line system 8 to a second stirring or. Funding 22 funded. An evaporation stage can be included in the stirring or conveying means 22. From the stirring or conveying means 22, the line system can be be heated. In contrast to the unheated line system 8, the heated line system is provided with the reference symbol 8 'in FIG. 1. In particular, a line system can be used, as described in WO 01/88232 A1, WO 01/88419 A1 and WO 03/69200 A1.

The control device 17 compares the metal content measured by the sensors 23, 23 ′ with predetermined limit values and outputs a signal to the mixing device 14 as a function of this metal content. The control signal to the mixing device 14 adjusts the composition of the water 6 fed to the pulper 5 as a function of the metal content of the cellulose solution and regulates the dissolved metal content or the content of individual dissolved metal ions in the cellulose solution mixed with tertiary amine oxide to a predetermined value. Since the concentration of reactions in the cellulose solution increases after the evaporation stage, a sensor is preferably provided which monitors the dissolved metal content of the cellulose solution after addition of all components and after all evaporation stages.

If, for example, the dissolved metal content of the cellulose solution, as detected by sensors 23, 23 'or by wet chemical means, is too high, the proportion of fresh water in the water 6 fed to the pulper 5 is increased. The dissolved metal content is set by the control device 17 such that it remains below 20 mg / kg, preferably below 10 mg / kg and most preferably below 5 mg / kg. The dissolved metal content can also be determined before the formation of the cellulose solution, that is to say still in the cellulose suspension, this measurement being more appropriate than the measurement of the metal content directly in the cellulose solution.

When controlling the composition of the water 6, the control device 17 takes into account the previously determined dissolved metal content of the cellulose 3, 4 fed to the pulper 5. For this purpose, the dissolved metal content of the cellulose 3 just used, analyzed on the basis of individually dissolved metal ions or the total metal content, can be used , 4 can be entered into the control device 17. This presetting is taken into account when determining the proportions of the press water and the fresh water in the water supplied to the pulper 5. For example, cellulose with a high metal content has a higher proportion of fresh water from the outset 15 fed to the pulper 5 or certain metal-binding additives are added to the cellulose suspension.

If the dissolved metal content, as detected by the sensors 23, 23 'in the cellulose solution to which tertiary amine oxide is added, drops below a predetermined limit value, which is considered sufficient for safety against exothermic reactions, for example 10 mg / kg, so the proportion of the press water 11 in the water supplied to the pulper 5 is increased. With sufficient security against exothermic reactions, less fresh water is used and less press water is released into the environment.

After the stirring or conveying means 22, the now extrudable cellulose solution is passed to a spinning head 25, which is provided with a large number of extrusion openings (not shown in FIG. 1), which are arranged in the spinning head on a rectangular or circular surface. The highly viscous cellulose solution is extruded through each of these extrusion openings to form an endless molded body 2 in an air gap 26. The cellulose molecules are oriented by stretching the cellulose solution, which is still viscous after extrusion. For this purpose, the extruded cellulose solution is drawn away from the extrusion openings via a take-off mechanism 27 at a speed which is greater than the extrusion speed.

After the air gap 26 pass through the endless molded body 2 a precipitation bath 28 containing a non-solvent such as water, whereby the cellulose in the continuous molded bodies 2 is precipitated.

The spinning head 25 comprises a blowing device 29, by means of which a gas stream 30 directed towards the continuous molded bodies 2 is generated during operation. Furthermore, the spinning head 25 comprises shielding means 31, which surround the extrusion openings on the side facing the air gap 26 and protrude into the air gap 26. The area which the continuous molded bodies 2 occupy in the air gap 26 is referred to as the spinning or thread zone 32. The shielding means 31 is designed as a fence, flow baffle and / or spoiler. The gas flow 30 is blocked by the shielding means 31 of the spinning head 25. In the slipstream of the shielding means 31, a shielding area 33 is formed, in which flows from outside the spinning zone 32 into the exit area, ie the area of the spinning zone 32 which immediately adjoins the extrusion openings, are blocked. This is explained in more detail below with reference to FIGS. 2 and 4.

Subsequently, the continuous molded bodies 2 are treated further, for example washed, finished, chemically treated in a device 34 in order to influence the crosslinking properties, and / or dried and further pressed in a device 35.

The endless molded bodies 2 can optionally be fed to a second post-stretching means 36, by means of which the through-coagulated continuous molded bodies 2 are post-stretched and obtain greater strength. The second post-stretching means 36 can also be provided immediately after the take-off mechanism 27, that is to say between the device 34 and the precipitation bath 28, so that only the post-stretched endless body is subjected to further treatment steps.

In order to be able to carry out a heat treatment at the same time during the post-stretching, the post-stretching means 36 can have a heating device 37 in the entry region of the continuous molded body, which brings the continuous molded body 2 to a predetermined temperature and at the same time dries the continuous molded body 2 at least superficially.

In the post-stretching means, the endless molded bodies are guided over two godets 38, 39 which are driven in such a way that a predetermined post-stretching tensile stress is applied between them. The continuous molded bodies 2 subjected to this tensile stress are kept at a predetermined high temperature and can be impregnated during the post-stretching, in particular by a hot inert gas, such as air, or also by steam, for example dry steam, and with swelling agents or other agents for chemical fiber treatment, such as the arrows 40 is indicated. To support the drying effect, the godets 38, 39 can also be heated. Due to the post-stretching, the continuous moldings have a reduced crimp compared to conventional fibers, so that they are crimped by a stuffer box 41. Then the endless mold body 2 can be cut by a cutting device 42. If a continuous fiber is to be produced, crimping and / or cutting can of course also be dispensed with.

After crimping and cutting, the crimped continuous moldings can be used for further process steps such as Opening, pressing, being transported.

The entire conveyance of the cellulose solution in the line system 8 'takes place continuously, it being possible for buffer lines 8 "to be provided in the line system 8' in order to absorb fluctuations in the delivery quantity and / or the delivery pressure and to enable continuous processing without the formation of dead water areas. The line system 8 ' is equipped with a heating system (not shown) in order to keep the cellulose solution at a temperature during the conveying, in which the viscosity is sufficiently low for an economical conveying without decomposition of the tertiary amine oxide. The temperature of the cellulose solution in the line area is 8 " between 75 and 110 ° C.

In this temperature range, homogenization and uniform mixing of the cellulose solution is favored, which can be increased by static or rotating mixers.

The residence time of the cellulose suspension or solution in the line system 8, 8 'from the thick matter pump 7 to the spinning head 25 is between 5 minutes and 2 hours, preferably between 30 and 60 minutes.

FIG. 2 shows a schematic illustration of a spinning head 25 according to the invention from FIG. 1.

As described above with reference to FIG. 1, continuous molded bodies 2 are extruded from the extrusion openings 43 during operation and passed through the air gap 26 into a precipitation bath 28. The endless molded bodies 2 form a spinning or thread zone 32 in the air gap 26. The spinning speed of the endless molded bodies can be modern Spinning lines up to 500 m / min. Due to the high speed of the endless molded bodies 2, the air surrounding the spinning zone 32 is entrained and swirled in the air gap 26 by the endless molded bodies 2. This creates air flows 44, which can also run into the spinning zone 32 from the outside.

When the hot continuous moldings 2 exit from the extrusion openings 32, water evaporates in the spinning zone 32. The water vapor that emerges from the continuous mold bodies 2 has approximately the speed of the continuous moldings 2 and swirls with the air surrounding the continuous moldings 2, so that the ambient air is increasingly carried away.

The effect of the shielding means 31 is to prevent the continuous molded bodies 2 from being exposed to a gas flow in the exit region 32 ′ of the spinning zone 32 immediately following the extrusion openings 43. This is briefly explained below with reference to FIG. 3.

As can be seen in FIG. 3, the continuous molded body 2 expands in an expansion region 45 immediately after the extrusion and forms a thickening 45 ′ before its diameter decreases again under the action of the tensile force. The delay in the air gap can be controlled in the ratio of the exit speed of the polymer solution to the take-off speed in m / min to 1:40.

In the area of the thickening 45 ′, the diameter of the continuous molded body 2 transversely to the extrusion direction E can be up to three times the diameter of the extrusion opening 43.

In the widening area 45, in particular in the thickening 45 ′, the continuous molded body still has a relatively strong anisotropy, which gradually decreases in the direction of extrusion E under the action of the tensile force on the continuous molded body 2, since the chain molecules in the continuous molded bodies 2 increasingly align in the direction of extrusion. A gas stream, which strikes the cooling body in the expansion area 45 and cools it, can have a negative impact on the spinning quality of the continuous molding 2. Such a gas flow in the expansion area 45, which corresponds approximately to the exit area 32 ′ of the spinning zone 32, is blocked by the shielding means 31. The shielding means 31 are, as shown in FIG. 2, attached to an extrusion side 46 on the spinning head 25 with fastening means 47, such as screws, and can preferably be adjusted in their positions relative to the spinning zone 32 in guides. In the embodiment shown in FIG. 2, the shielding means 31 are specially designed as metal angles or as mentioned above. Alternatively, the shielding center! 31 can also be configured, for example, from a suitable plastic and / or in strip form like a doctor blade. The fastening means 31 can furthermore also be attached to the spinning head 25 in a cohesive manner, for example by welding, soldering or gluing, but then do not allow their position to be adapted to the respective spinning conditions.

The shielding means 31 is attached to the spinning head 25 in such a way that it at least partially delimits the exit region 32 ′ of the endless molded body 2, preferably in the form of a fence or flow guide plate. In the embodiment shown in FIG. 2, the two fastening means 31 delimit the outlet area 32 'on two opposite sides. Alternatively, the exit area 32 'e.g. also be bordered on all four sides or only on one side. If the extrusion openings 43 are arranged on a circular surface, an annular shielding means can also be used. Furthermore, a shielding means 31 ′ can also be arranged in the middle of the spinning zone 32, between the continuous mold bodies, in order to more effectively block the gas flow immediately after the continuous molded bodies 2 have emerged.

The shielding means 31 form a shielding area 33 directly below the spinning head 25, in which flows that are generated due to the thread movement in the extrusion direction are suppressed. In the shielding area 33, in particular flows 36 that run from the outside into the spinning zone 32 are blocked. The shielding means 31 is designed in such a way that the shielding region 33 includes the widening region 37 (FIG. 3) of the endless molded body 2.

In order to protect the expansion area 45 at the same time and still ensure adequate cooling of the continuous molded bodies 2, the shielding means 31 in the extrusion direction E should not be too long. It has been found that a particularly suitable height H of the shielding means 31 extends into the region of the Cover 45 ', preferably in the extrusion direction E beyond. The height H can in particular be between 10 mm and 20 mm, preferably about 15 mm.

FIG. 4 shows a further embodiment of a spinning head 25 according to the invention, which, in contrast to the spinning head of FIG. 2, is additionally provided with a blowing device 29. For FIG. 4, the reference numerals of FIGS. 1 and 2 are used below for the same or similar elements. For the sake of clarity, only the differences from the embodiment in FIG. 2 are discussed.

The blowing device 29 of the spinning head 25 generates a gas stream 30 during operation, which is directed onto the continuous molded body 2. The shielding means 31 prevent the continuous molded bodies 2 in the shielding area 33 from being exposed to the gas flow 30, which has a negative influence on the extrusion process and causes unfavorable fiber properties.

The shielding means 31 is arranged between the flow outlet 50 of the blowing device 29 and the outlet region 32 'such that the outlet region 32' and thus the region of the continuous molded bodies 2 remains in the slipstream 51 of the shielding agent or body immediately after the outlet from the extrusion openings. The shielding means 31 on the side of the spinning or thread zone 32 facing away from the blowing device 29 prevents a release vortex from being able to supply gas from the rear into the exit region 32 ′.

4 shows that one shielding means is arranged directly in the gas stream 30 on the blowing device. However, if the flow outlet 50 is shifted further in the direction of the precipitation bath 28, the shielding means can remain in place without protruding into the gas stream 30.

The shielding means 31 does not have to be completely impermeable to air in order to develop its effect. Close-meshed filter or mesh materials or other bodies with high flow resistance are also suitable. In addition, the shielding means can be inclined towards the extrusion direction E, for example between −30 ° and + 30 °, or curved in the extrusion direction E in order to deflect the gas flow without swirling. Furthermore, the shielding means 31 in the plane of the extrusion openings are inclined or curved to better deflect the gas flow to the sides.

Claims

claims

1. A process for producing continuous moldings (2) from a spinning solution containing water, cellulose and tertiary amine oxide, in which the spinning solution is first extruded into extrusion bodies (2), then the continuous moldings (2) in a spinning zone (32) through an air gap ( 26), thereby stretched and then passed through a precipitation bath (28), characterized in that at least one gas stream (30 ') flowing from outside the spinning zone (32) into the outlet region (32') immediately adjacent to the extrusion openings (43) 44) is blocked.

2. The method according to claim 1, characterized in that a shielding area (33) is formed in the outlet area (32 ') of the endless molded body (2), in which a cooling gas flow is blocked.

3. The method according to claim 1 or 2, wherein the continuous moldings (2) in the air gap (26) are exposed to a gas stream (30) generated by a blowing device (29), characterized in that at least the exit region (32 ') of the continuous moldings (2) directed part of the gas stream (30) is blocked.

4. The method according to any one of the above claims, characterized in that the gas stream (30, 44) in a widening area (45) of the continuous molding (2), in which the continuous molding (2) in the direction of extrusion (E) after extrusion expand, is blocked.

5. spinning head (25) for spinning continuous moldings (2) from a spinning solution (water) flowing through the spinning head (25) containing water, cellulose and tertiary amine oxide, with extrusion openings (43) which adjoin a spinning zone (32) in the direction of extrusion (E) characterized in that the spinning head (25) comprises at least one shielding means (31) through which a gas stream (30, 44) flowing from outside the spinning zone (32) into the outlet area (32 ') immediately adjacent to the extrusion openings (35) is blocked.

6. Spinning head (25) according to claim 5, characterized in that the outlet region (32 ') comprises a widening region (45) of the continuous moldings (2), in which the continuous moldings (2) expand in the extrusion direction (E) after extrusion ,

7. spinning head (25) according to claims 5 or 6, with a blowing device (29), by means of which a gas stream (30, 44) directed towards the continuous molded body (2) can be generated during operation, characterized in that the shielding means (31) in the gas stream (30, 44) generated by the blowing device (29) is arranged.

8. Spinning head (25) according to claim 7, characterized in that the shielding means (31) is arranged at least between a flow outlet (50) of the blowing device (29) and the spinning zone (32).

9. spinning head (25) according to one of claims 5 to 8, characterized in that the at least one shielding means (31) on the air gap (26) facing side of the spinning head (25) is arranged and in the extrusion direction (E) from the spinning head (25) extends away.

10. Spinning head (25) according to one of claims 5 to 9, characterized in that the at least one shielding means (31) is designed in the form of a fence which at least partially delimits the spinning zone (32).

11. Spinning head (25) according to one of claims 5 to 10, characterized in that the at least one shielding means (31) extends from the spinning head (25) in the extrusion direction (E) to at least the area in which the endless molded body (2) extends Expand operations after extrusion.

12. Spinning head (25) according to one of claims 5 to 11, characterized in that the shielding means (31) excludes the area of the extrusion openings.

13. Spinning head (25) according to one of claims 5 to 12, characterized in that the shielding means (31) is designed to be heatable.

14. Spinning head (25) according to claim 13, characterized in that the shielding means (31) comprises a heater.

15. Spinning head (25) according to claim 14, characterized in that the heater is arranged on the side of the shielding means (31) facing away from the spinning zone (32).

16. Spinning head (25) according to one of claims 5 to 15, characterized in that the shielding means (31) extends at an angle relative to the extrusion direction (E).

17. spinning head (25) according to any one of claims 5 to 16, characterized in that the shielding means (31) is bulbous.

18. Spinning head (25) according to one of claims 5 to 17, characterized in that the shielding means (31) extends at an angle between - 30 ° and + 30 ° relative to the spinning threads.

19. Spinning plant (1) for producing continuous moldings (2) from a spinning solution, with a mixing device (5, 19), in which water, cellulose and tertiary amine oxide can be mixed to form the spinning solution during operation, with a spinning head (25), one Air gap (26) and a precipitation bath (28), characterized in that the spinning head (25) is designed according to one of claims 5 to 12.