EP1463851B1 - Spinning device and method having cooling by blowing - Google Patents

Abstract

The present invention relates to an apparatus for producing continuously molded bodies from a molding material, such as a spinning solution containing cellulose, water and tertiary amine oxide. The apparatus ( 1 ) comprises a die plate ( 3 ) including extrusion orifices ( 4 ) through which the molding material is extruded into substantially filament-like continuously molded bodies ( 5 ). The continuously molded bodies ( 5 ) are passed through an air gap ( 6 ) and guided in a precipitation bath ( 9 ) by a deflector ( 10 ) to a bundling means ( 12 ) where they are united into a bundle of fibers. In the air gap, a blowing means ( 14 ) is provided for directing a cooling gas stream ( 15 ) onto the continuously molded bodies ( 5 ) in a direction transverse to the direction of passage ( 7 ). To improve the spinning stability and mechanical properties of the continuously molded bodies, it is intended according to the invention that directly with respect to the extrusion orifices ( 4 ) a first shielding zone ( 20 ) is arranged by which the extrusion orifices are shielded against the action of the cooling gas stream.

Description

The invention relates to a device for the production of continuous molded articles a molding compound such as a dope containing cellulose, water and tertiary Amine oxide, with a variety of extrusion orifices through which in operation Molding composition is extrudable to continuous moldings, with a precipitation bath and with a between the extrusion openings and the precipitation bath arranged air gap, wherein in operation, the continuous moldings successively through the air gap and the Precipitation are passed and in the region of the air gap, a gas stream to the continuous moldings is directed.

The fundamentals of the production of continuous moldings, such as lyocell fibers a spinning solution containing cellulose, water and tertiary amine oxide, preferably N-methyl morpholine N-oxide (NMMNO) are described in US 4,246,221. Accordingly, the production of continuous moldings essentially in Three steps take place: First, the spinning solution is passed through a variety of extrusion orifices extruded into continuous moldings. Then the endless shaped bodies stretched in an air gap, thereby setting the desired fiber thickness and then passed through a precipitation bath where they coagulate.

The advantage of lyocell fibers or corresponding continuous molded articles is on the one hand in the particularly environmentally friendly manufacturing process, which is an almost complete recovery of the amine oxide, on the other hand to the excellent textile properties of lyocell fibers.

The problem with the process, however, is that the freshly extruded continuous moldings have a strong surface tackiness, which only on contact reduced with a precipitant. In the passage of the continuous molding through the air gap, therefore, there is the danger that the continuous molded body itself touch each other and stick together immediately. The danger of sticking can by adjusting the operating and process parameters such as tensile stress in the air gap, air gap height, thread density, viscosity, temperature and Spinning speed can be reduced. However, if such bonds occur, This affects the manufacturing process and the fiber quality negatively, since Adhesions lead to breaks and thick places in the continuous molded bodies can. In the worst case, the manufacturing process must be interrupted and the Spinning process are restarted, which causes high costs.

Nowadays is by the manufacturers of continuous moldings, such as the Gamherstellen as part of the textile processing chain, gluing freedom required i.e. the individual filament stacks must not be glued together Otherwise, there may be irregularities in, for example, the Gamdicke comes.

High efficiency in the production of lyocell fibers, mainly Staple fibers and filaments, however, can only be achieved if the spinneret openings are arranged at a small distance from each other. A lesser one Distance increases but the risk of bonding in the air gap due to accidental Touching the continuous moldings.

To improve the mechanical and textile properties of lyocell fibers It is advantageous if the air gap is as large as possible, as at a large air gap, the stretching of the threads over a longer run length spreads and tensions in the extruded Endlosformkörpern easier can be reduced. However, the larger the air gap is, the smaller it is the spinning safety or the greater the risk that the manufacturing process must be interrupted due to spun yarn bonds.

Based on the principles of US 4,246,221, there are in the prior art some solutions that are tried, both the profitability as well the spinning safety in the production of continuous moldings from a spinning solution containing cellulose and tertiary amine oxide to improve.

Thus, a method is described in US 4,261,941 and in US 4,416,698, in which the continuous moldings immediately after extrusion with a non-solvent be brought into contact to reduce the surface tautness. Subsequently, the continuous moldings are passed through a precipitation bath. The additional wetting of the continuous moldings by the non-solvent however, before passing through the precipitation bath is for commercial use too expensive and too expensive.

Another way to increase the spin density, i. the number of extrusion openings per unit area, is described in WO 93/19230: In the there described device, the continuous moldings immediately after Extrusion by horizontal blowing transverse to the extrusion direction with a Cooling air flow cooled. By this measure, the surface tack of the Continuous molding reduces and the air gap can be extended.

However, the problem with this solution is that the cooling air flow interacts with the extrusion process to the extrusion openings occurs and him can negatively influence. In particular, in the method of WO 93/19230 pointed out that the spun threads are not of uniform quality not all are detected in the same way by the cooling air flow. In any case, the danger of adhesions becomes in the process of WO 98/19230 not sufficiently reduced.

To a uniform blowing of the continuous molding immediately after To allow exit from the extrusion openings is in the device of the WO 95/01470 uses an annular nozzle, wherein the extrusion openings on a are distributed substantially annular surface. The blowing with a cooling air flow takes place through the center of the annular nozzle and the circular ring the continuous molded body in the radial direction horizontally outwards. The air flow is laminar at its exit from the blowing device held. The formation of a laminar air flow becomes obvious significantly enhanced by the listed in the patent louver.

WO 95/04173 relates to a constructive development of the annular nozzle and the Blowing device, essentially on the device of WO 95/01470 is based.

Although the solutions of WO 95/01470 and WO 95/04173 actually lead to a more uniform blowing, however, the ring assembly of the continuous molded body to problems in the passage of the continuous molded by the Fällbad: As the continuous moldings dip as a circular ring in the precipitation bath and the Draw precipitation liquid in the precipitation bath, arises in the area between the Endlosformkörpern an under-supplied with precipitation liquid area, which leads to a Equalization flow through the ring of Endformformkörper through and to a churned Fällbadoberfläche leads, which in turn the occurrence of Faserverklebungen entails. In addition, also in the solutions of WO 95/01470 and WO 95/04173 to observe that for the mechanical and textile product properties essential extrusion conditions to the Extrusion openings are difficult to control.

As an alternative to the annular nozzle arrangements are known in the art segmented rectangular nozzle arrangements have been developed, i. Nozzles, at those the extrusion openings on a substantially rectangular base are arranged substantially in rows. Such a segmented Rectangular nozzle arrangement is shown in WO 94/28218 in this device takes place a blowing with a cooling air flow transverse to the extrusion direction, wherein the cooling air flow along the longer side of the rectangular nozzle assembly extends. After passing through the continuous molding is at the Device of WO 94/28218 sucked off the cooling air flow again. The suction is necessary so that the air flow through the entire cross section of the Air gap can be directed.

In WO 98/18983 the concept of rectangular nozzles is arranged in rows Extrusion openings further developed. Here, the WO 98/18983 that the extrusion orifices are spaced differently in a row than the Rows of extrusion openings with each other.

Finally, in WO 01/68958, blowing is substantially transverse to Passage direction of the continuous moldings through the air gap with a different Goal described. The blowing by means of a stream of air does not serve to cool the continuous moldings, but to calm the Fällbadoberfläche of the precipitation bath in the area in which the continuous moldings in the Fällbad or immerse in the spinning funnel: According to the teaching of WO 01/68958 The length of the air gap can be significantly increased when the blowing on The immersion of the capillary shares in the precipitation is effective to the movement to calm the spin bath surface. It is believed that the for Spinning funnel typical strong Burburbulenzen by attaching a calming be reduced at the Spinnbadoberfläche by passing through the Blowing a liquid transport at the Fällbadoberfläche through the filaments is induced. For this purpose, according to the teaching of WO 01/68958 a merely weak air flow provided. Essential in the teaching WO 01/68958 in that the blowing just before the entry of the continuous molded body in the Spinning bath surface takes place. With the speeds given in WO 01/68958 the air flow and at the point where the air flow to Spinnbaderuhigung is used, but can be no cooling effects effect the Endlosformkörpern more.

Thus, in the device of WO 01/68958, in addition to that described therein Initiation shortly before the entry of the continuous tablets into the spin bath surface still a cooling of the filaments near the extrusion openings necessary as known from the prior art. The additional necessary Cooling, however, leads to a very complex system.

In view of the disadvantages of the solutions known from the prior art The object of the invention is to provide a device and a method create, through which at low design cost large air gap lengths can be combined with high spinning density combined with high spinning safety.

This object is achieved according to the invention for a spinning device mentioned above achieved in that the air gap immediately after the extrusion a shielding area and one through the shielding area from the extrusion ports having separate cooling area, wherein the cooling area through the designed as a cooling gas flow gas stream is determined.

The cooling area is therefore the area in which the cooling gas flow on the Endlosformkörper impinges and this cools.

This solution surprisingly leads to a higher spin density and to a longer air gap than in the conventional devices in which the Cooling area comes close to the extrusion openings and no shielding area is available.

It seems as if through the shielding area, so by the spacing the cooling gas flow boundary of the extrusion openings, a cooling of the Extrusion openings and thus a negative impact on the training the mechanical and textile properties of extremely important extrusion process is avoided at the extrusion openings. Thus can be with the inventive design of the extrusion process with exactly definable and exactly observable parameters, in particular with exact temperature control the molding compound to the extrusion openings, perform.

One reason for the surprising effect of the solution according to the invention could This is because the continuous moldings in a directly on the extrusion forming the following area. The tensile force that the stretching of the Endlosformform causes, begins to act only behind this expansion area. In the widening area itself, the continuous molded bodies have no orientation on and are largely anisotropic. Through the shielding area is apparently a damaging effect on the fiber properties of the cooling gas flow avoided in the anisotropic expansion area. The cooling effect seems to be used in the inventive solution only when the tensile force acting on the continuous molding and a gradual rectification of the Molecules of the continuous molded article effected.

To avoid that the surface of the precipitation bath by the cooling gas flow is churned, according to a particularly advantageous embodiment of the Device be provided that the air gap adjacent to the first shielding area a second shielding region through which the cooling region is separated from the Fällbadoberfläche. Through the second shielding area it is avoided that the cooling gas flow in the immersion region of the yarn sheets touches the Fällbadoberfläche and generates waves that the Endlosfonnkörper could mechanically load when entering the Fällbadoberfläche. Of the second shielding area is particularly useful when the cooling gas flow has a high speed.

The quality of the continuous shaped bodies produced can be determined according to another surprisingly improve advantageous embodiment, when the inclination of the Cooling gas flow in Durchleitungs- or extrusion direction is greater than the expansion the cooling gas flow in the direction of flow. In this embodiment, the Cooling gas flow at any point in the field of continuous moldings in a passage direction pointing flow component, the stretching in the air gap supported.

A particularly good shielding of the extrusion process from the influence of the Cooling gas flow is achieved when the distance of the cooling area of each extrusion opening is at least 10 mm. At this distance you can even stronger cooling gas flows no longer on the extrusion process in the extrusion openings act.

In particular, the distance I of the cooling area of each extrusion opening in millimeters, according to a further advantageous embodiment, can fulfill the following (dimensionless) inequality: I> H + A • [tan (β) - 0.14], where H is the distance of the cooling gas flow upper edge from the plane of the extrusion openings to the outlet of the cooling gas flow in millimeters. A is the distance between the outlet of the cooling gas flow and the last row of continuous moldings in the flow direction in millimeters transverse to the direction of passage in which the continuous moldings are passed through the air gap, usually the horizontal direction. As β, the angle in degrees between the cooling steel direction and the direction transverse to the passage direction is designated. The cooling gas flow direction is determined essentially by the center axis, or - in plane cooling flows - the center plane of the cooling gas flow. By following this design formula, the spinning quality and the spinning safety can be surprisingly improved.

The angle β can assume a value of up to 40 °. The value H should regardless of the angle β in any case be greater than 0, in order to influence the To avoid extrusion process. The distance A may be at least one thickness E of the curtain of continuous moldings transversely to the direction of passage correspond. The thickness E of the thread curtain is at most 40 mm, preferably at most 30 mm, more preferably at most 25 mm. The distance A can in particular by 5 mm or, preferably, by 10 mm greater than the thickness E of Be thread curtain.

Likewise, it has surprisingly been found that increase the spinning quality and the spinning safety, if between the height L of the air gap in the direction of passage in millimeters, the distance I of the cooling area of the Endlosformkörpfem in passage direction in millimeters, the distance A between the outlet of the cooling gas flow and the in the flow direction of the last row of continuous moldings transverse to the direction of passage in millimeters and the height B of the cooling gas flow in the direction of passage in millimeters, the following (dimensionless) relationship is fulfilled in the region of the air gap occupied by the continuous moldings: L> I + 0.28 • A + B

The device according to the invention is in particular for the production of continuous moldings from a spinning solution which, before being extruded, has a zero shear viscosity of at least 10,000 Pas, preferably at least 15,000 Pas, have at 85 ° C measuring temperature. By adjusting the viscosity of the Molding material, which essentially by the selection of Zelfstofftyps and the Cellulose and water concentration takes place in the spinning solution is added to the extrudate given a certain intrinsic or basic strength, so that the default too Formkörpem can be done. At the same time you can still by adding stabilizers and by the reaction during the preparation of the solution the necessary Set the viscosity range.

According to a further embodiment of the spinning process can be improved be that the cooling gas flow as turbulent flow, in particular as turbulent Gas stream is formed. So far, one is well in the art It is assumed that cooling in Lyocell filaments only by a laminar Can be carried out cooling gas flow, as a laminar flow of cooling gas in the Endlosformkörpern produces less surface friction than a turbulent stream and the continuous moldings therefore less mechanically loaded and moved.

Surprisingly, it has now been found that at a turbulent and high speed emerging from the blowing device cooling gas flow at the same Cooling performance as in a laminar flow of cooling gas much lower blowing air or quantities of gas seem necessary as originally suspected. By the reduced Blasluftmenge, preferably due to small gas flow cross-sections is achieved, the surface friction on the Endformformkörpern despite keep turbulent inflating small, so that no negative influence of the Spinning process takes place.

The positive effect of the turbulent cooling gas flow is all the more astonishing since According to general fluid mechanics an improved cooling effect with turbulent Flow would have been expected only at a low number of rows. To the To economically operate a spinning process with a high hole density, it is necessary to provide a variety of rows, so that according to the fluid dynamics actually only a fraction of the continuous molded articles from the improved heat exchange conditions should benefit. Nevertheless, when using a turbulent cooling gas flow at high speed an improved spinning behavior also in the last, from the cooling gas flow farthest rows.

It would be at turbulent and high speed carried out Kühlbeblasung had to be expected that due to the high speeds the Filaments would fade and stick together. Surprisingly However, it was shown that no impairment of the filaments takes place, but on the contrary, in the use of small turbulent gas streams, the gas demand can be drastically reduced and the risk of sticking is very low. Fiber titers of less than 0.6 dtex can easily with turbulent cooling gas streams be spun. The aspect of turbulent gas flow cooling is in the spinning process taken independently of the other invention Developments advantageous.

One with the width of the cooling gas flow in the direction of passage and the speed the Reynolds number formed in the cooling gas flow can be at a training of the invention at least 2,500, preferably at least 3,000.

To penetrate a multitude of rows of threads, it is very important that the cooling flow energy-intensive brought to the yarn sheets and passed becomes. To meet this requirement, a blowing device for Generation of the cooling gas flow to be configured such that on the one hand specific blowing force is high, and on the other hand from the blowing device generated distribution of individual cooling flows to the requirements of the cooled Threads of yarn correspond

The distribution of the individual cooling streams should according to an advantageous embodiment give a substantially flat jet pattern (flat jet), wherein the width of the substantially planar beam at least the width of the yarn curtain to be cooled must have. Preferably, the planar beam pattern distribution also by juxtaposed individual round, oval, rectangle - or other polygon rays be formed, even several superimposed Rows are according to the invention for the formation of a planar beam pattern distribution possible.

The specific blowing force is determined as follows: A nozzle for generating the Cooling gas flow with a rectangular (flat) beam pattern distribution and a maximum width of 250 mm is in the blowing direction perpendicular to one on one Weighing device mounted baffle plate with an area of 400 x 500 mm mounted. The nozzle outlet, the outlet of the cooling gas flow from the blowing device forms, is spaced at 50 mm to the baffle plate. The nozzle is with Compressed air subjected to 1 bar overpressure and acting on the baffle plate Force is measured and divided by the width of the nozzle in millimeters. Which Resulting value is the specific blowing force of the nozzle with the unit [m N / m m].

In an advantageous embodiment, a nozzle has a specific blowing force of at least 5-10 mN / mm.

The rectangular die may have multiple extrusion orifices arranged in rows have, wherein the rows may be staggered in the direction of cooling gas flow. Around a good effect of the cooling gas flow in the cooling gas flow direction The last row of continuous moldings can be achieved with the rectangular nozzle the number of extrusion openings in the row direction is greater than in Cooling gas flow direction.

When using rectangular nozzles, in particular the diversion of the continuous molding as a substantially planar curtain within the precipitation bath in Towards the Fällbadoberfläche take place, so that a bundling of the continuous molded, i.e. a merging of the continuous molding on an imaginary Point, can take place outside the Fällbades.

The above object is also achieved by a method for manufacturing of continuous molded articles of a molding composition, such as containing a spinning solution Water, cellulose and tertiary amine oxide, wherein first the molding composition to Continuous moldings is extruded, then the continuous moldings through an air gap passed, stretched there and blown with a gas stream and cooled, and then the continuous moldings are passed through a precipitation bath. The continuous moldings in the air gap are initially through a shielding and then passed through a cooling area where they pass through Cooling gas flow to be cooled in the cooling area.

In the following, the invention will be described with reference to exemplary embodiments and experimental examples described in more detail.

Fig. 1

eine perspektivische Darstellung einer erfindungsgemäßen Vorrichtung in einer schematische Übersicht;

Fig. 2

eine erste Ausführungsform der in Fig. 1 dargestellten Vorrichtung in einem schematischen Schnitt entlang der Ebene II-II der Fig. 1;

Fig. 3

eine schematische Darstellung der Vorrichtung der Fig. 1 zur Erläuterung von geometrischen Kenngrößen;

Fig. 4

eine schematische Darstellung zur Erläuterung der Vorgänge in einem Endlosformkörper unmittelbar nach der Extrusion.

Show it:

Fig. 1

a perspective view of a device according to the invention in a schematic overview;

Fig. 2

a first embodiment of the device shown in Figure 1 in a schematic section along the plane II-II of Fig. 1.

Fig. 3

a schematic representation of the apparatus of Figure 1 for explaining geometric characteristics.

Fig. 4

a schematic representation for explaining the processes in a continuous molding immediately after the extrusion.

First, the structure of a device according to the invention with reference to FIG. 1 described.

Fig. 1 shows an apparatus 1 for the production of continuous molded articles from a Molding compound (not shown). The molding composition may in particular be a spinning solution containing cellulose, water and tertiary amine oxide. As a tertiary amine oxide N-methyl-morpholine-N-oxide can be used. The zero shear viscosity of the Molding compound at about 85 ° C is between 10,000 to about 30,000 Pas.

The device 1 comprises an extrusion head 2, which at its lower end with a substantially rectangular, fully drilled nozzle plate 3 as Base is provided. In the nozzle plate 3 is a plurality of rows arranged extrusion openings 4 are provided. The one shown in the figures Row number is for illustrative purposes only.

The molding compound is heated and through the preferably heated extrusion openings passed, where through each extrusion opening an endless molded body. 5 is extruded. As shown schematically in FIG. 1, each continuous molding can 5 may be formed substantially filiform.

The continuous moldings 5 are extruded into an air gap 6, they in a Pass through passage or extrusion direction 7. According to Fig. 1, the Point extrusion 7 in the direction of gravity.

After passing through the air gap 6, the continuous moldings 5 dive as an im Essentially planar curtain in a precipitation 9 from a precipitating agent, for example Water, a. In Fällbad 9 is a deflection member 10, through the plane curtain 8 from the extrusion direction in the direction of the Fällbadoberfläche deflected as a curtain 11 and thereby to a bundling device 12th is directed. By the bundling device 12, the flat curtain to a bundle of threads 13 summarized. The bundling device 12 is outside the precipitation bath 9 is arranged.

As an alternative to the deflecting member 10, the continuous moldings can be in the direction of passage 7 are also passed through the precipitation bath and by a Spinning funnel (not shown) on the Fällbadoberfläche 11 opposite Exit the side at the bottom of the precipitation bath. However, this embodiment is disadvantageous in that the consumption of Fällbadflüssigkeit is high, in the Spinning funnel turbulences occur and the separation of precipitation bath and fiber cable is problematic at the funnel exit.

In the region of the air gap 6, a blowing device 14 is arranged, off a cooling gas flow 15 exits, the axis 16 transverse to the passage direction 7 runs or the at least one main flow component in this direction having. In the embodiment of FIG. 1, the cooling gas flow 15 is in essential just.

The term "plane gas stream" is understood to mean a cooling gas stream, the height B transverse to the direction 16 of the gas stream smaller, preferably is much smaller than the width D of the gas flow in the row direction and the spaced from solid walls. As can be seen in Fig. 1, the runs Width direction D of the gas flow along the long edge 17 of the rectangular nozzle Third

Through the two boundary regions 18a and 18b of the cooling gas flow 15, wherein 18a the nozzle plate 3 facing the upper limit region and 18b of the Fällbadoberfläche 11 facing lower limit region, becomes a cooling area 19 determined. Since the temperature of the planar gas flow 15 is lower as the temperature of the still molded by the extrusion process Endlosformkörper 5 finds in the cooling area an interaction of the planar gas flow 15th with the continuous moldings 5 and thus cooling and solidification of the continuous moldings instead of.

The cooling area 19 is from the extrusion openings 4 through a first shielding area 20 separated, in which no cooling of the continuous molded body. 5 takes place.

From the Fällbadoberfläche 11 of the cooling area 19 through a second shielding area 21 separated, in which also no cooling and / or no Air movement takes place

The first shielding region 20 has the function, the extrusion conditions directly at the extrusion openings as uninfluenced by the following Cooling to let through the cooling gas flow in the cooling area 19. The second In contrast, the shielding region 21 has the function of the precipitation bath surface 11 from Shield cooling gas flow and keep it as calm as possible. One way, the Keep precipitation bath surface 11 steady, it is in the second shielding area 21 to keep the air as still as possible.

The blowing device 14 for generating the cooling gas flow 15 has a single or multi-row multi-channel nozzle, as e.g. from the company Lechler GmbH in Metzingen, Germany. In this multi-channel nozzle is the cooling gas flow 15 formed by a plurality of circular individual streams with a diameter between 0.5 mm and 5 mm, preferably around 0.8 mm, which depends on one of its diameter and flow speed connect dependent running route to a planar gas flow. The individual streams occur at a speed of at least 20 m / s, preferably at least 30 m / s out. Speeds of more than 50 m / s are also available turbulent cooling gas flows possible. The specific blowing force of such a executed multichannel nozzle should be at least 5 mN / mm, preferably at least 10 mN / mm.

The thickness E of the curtain to be penetrated by the flow of cooling gas 5, measured transversely to the passage direction 7, in the embodiment of Fig. 1 less than 40 mm. This thickness is essentially determined by whether in the gas flow direction 16 last row 22 of the continuous moldings 5 a sufficient cooling effect by the cooling gas flow in the cooling area 16 is generated. Depending on the temperature and speed of the Cooling gas flow and the temperature and speed of the extrusion process in the area of the extrusion openings 4, thicknesses E are also less than 30 mm or less than 25 mm possible.

FIG. 2 shows a special embodiment of that shown in FIG Spinning device 1 described. In this case, for those already described in Fig. 1 Elements of the device 1 in Fig. 2 uses the same reference numerals. The embodiment is in a schematic section along the plane II of Fig. 1, which shows the plane of symmetry in the width direction D of the current 15th forms.

Between the measured in the passage direction 7 height I of the shielding region 20 in millimeters, the measured in the passage direction 7 height L of the air gap 6, the distance A from the outlet of the cooling gas flow 15 from the blowing device 14 to the last row 22 of the continuous molding 5 in millimeters and the width B of the cooling gas flow 15 in the direction transverse to the cooling gas flow direction 16 is the dimensionless relationship: L> I + 0.28 • A + B

The distance A can be at least the thickness E of the curtain of Endlosformkörpem 5, but also preferably 5 mm and 10 mm larger be as E The variables L, I, A, B are shown in FIG. 3.

If a cooling gas flow 15 with a round cross-section is used, then instead of the width B of the cooling gas flow 15 whose diameter are taken.

2, an embodiment is shown in which the direction 16 of the Cooling gas flow 15 at an angle β to the vertical 23 on the Passage direction 7 is inclined. In this way, the cooling gas flow 15th a velocity component facing in the direction of passage 7.

In the embodiment of FIG. 2, the angle β is greater than the propagation angle γ of the cooling gas flow. By this dimensioning rule, the boundary area runs 18 a between the gas flow 15 and the first shielding area 20 inclined in the direction of passage 7. The angle β shown in FIG. 2 can be up to 40 °. The cooling gas flow 15 has at each point in the cooling region 19 a in Durchleitungsrichtung 7 pointing component.

In the embodiment of FIG. 2, besides the already mentioned inequality for the air gap height L, the following inequality is always satisfied, by which the height I of the first shielding region 20 is determined in the direction of passage 7. The following applies: I> H + A • [tan (β) - 0.14], wherein the size H represents the distance in the passage direction 7 between the extrusion openings 4 and the upper edge of the cooling gas flow 15 directly at the outlet from the blowing device 14.

In particular, the height should not be at any point in the area of the extrusion openings of the first shielding region 20 may be smaller than 10 mm.

The height I of the shielding region can be determined with the aid of FIG. 4, in which an embodiment is described, explain as follows. In Fig. 4 is the detail VI of Fig. 3, wherein only a single continuous molding 5 immediately after exiting an extrusion opening 4 in the air gap. 6 is shown as an example.

As can be seen in FIG. 4, the continuous molding 5 expands immediately afterward the extrusion in a widening region 24 before it under the action of Tensile force is reduced again to approximately the diameter of the extrusion opening 4. The diameter of the continuous molding transverse to the direction of passage 7 can be up to three times the diameter of the extrusion opening.

In the widening region 24, the continuous molding still has a relatively strong Anisotropy, which in the direction of passage 7 gradually under the action reduces the tensile force on the continuous molding.

In contrast to the known from the prior art Beblasungsverfahren and devices according to the invention extends according to 4, the shielding region 20 at least over the widening region 24. This avoids that the cooling gas flow 15 to the expansion area acts.

According to the invention, it is provided that the first shielding area 20 extends to a region 25 in which the expansion of the continuous molding 5 is only low or no longer exists. In Fig. 4 it is shown that the area 25 in the direction of passage 7 behind the largest diameter of the Expansion area is located. Preferably, the cooling area overlap 19 and the expansion area 25 not, but follow each other directly.

In the following, the effect of the spinning device according to the invention and the inventive method explained by comparative examples.

In the examples given and in Table 1, the spinning density, i.e. the number of extrusion openings per square millimeter, the take-off speed, with the thread bundle 12 is deducted, in meters / second, the molding compound temperature in degrees Celsius, the heating temperature the extrusion openings in degrees Celsius, the air gap height in millimeters, the Reynolds number, the speed of the cooling gas flow immediately at the exit from the blowing device in meters / second, the distance H in millimeters, the angle β in degrees, the spun fiber titer in dtex, the coefficient of variation in percent, the subjectively evaluated spinning behavior with grades between 1 and 5, the width of the cooling gas flow or at a round flow of cooling gas Diameter and the normalized with the width of the cooling gas flow gas quantity in liters / hour per mm nozzle width. With a grade 1, the spinning behavior as good, with a grade 5 rated as bad.

The coefficient of variation was according to DIN EN 1973 with the testing device Lenzing Instruments Vibroskop 300 determined

The Reynolds number as a measure of the turbulence of a gas stream was determined according to the formula Re = w ₀ * B / ν, where w _{0 is} the exit velocity of the air from the nozzle in m / s, B is the blow gap width, or the hole diameter of the blower in mm and ν represents the kinematic viscosity of the gas. The kinematic viscosity ν was assumed to be 153.5 x 10 ^-7 m ² / s for air at a temperature of 20 ° C. If other gases or gas mixtures are assumed to be m ² / s. If other gases or gas mixtures are generated to produce a cooling gas flow, the value of ν can be adjusted accordingly.

Table 1 summarizes the experimental results shown.

Comparative Example 1

A NMMNO spinning mass consisting of 13% cellulose type MoDo Crown Dissolving-DP 510-550, 76% NMMNO and 11% water was at a temperature of 78 ° C stabilized with propyl gallate of an annular spinneret supplied with a ring diameter of about 200 mm. The spinneret existed made up of several drilled individual segments, each containing the extrusion openings in Form of Kapillarbohrungen included. The extrusion openings were on a temperature of 85 ° C heated.

The space between the precipitation bath surface and the extrusion openings became formed by an air gap of about 5 mm in height. The continuous moldings went through the air gap without blowing. The coagulation of the continuous molded article was carried out in the spinning bath, in which a spinning funnel is arranged below the extrusion openings was.

The annular array of Endlosformkörpern was in the spinning funnel through the Bundled exit surface and led out of the spinning cone. The length of the spinning funnel in the direction of passage was about 500 mm.

The spinning behavior was very difficult because the spun fiber material had many bonds. The bad conditions also showed up in a strong dispersion of the fiber fineness, their variance in this comparative example was over 30%.

Comparative Example 2

In Comparative Example 2 was under otherwise the same conditions an externally inwardly directed blowing immediately after the extrusion made without a first shielding area. The blowing took place with a relatively low speed of about 6 m / s.

By blowing the height of the air gap could only slightly increased The spinning quality and the spinning safety remained compared to the comparative example 1 essentially unchanged.

Comparative Example 3

The molding compound used in Comparative Examples 1 and 2 was used in Comparative Example 3 at a temperature of also 78 ° C a rectangular nozzle fed, which consisted of several drilled individual segments. The rectangular nozzle had three rows of individual segments at one temperature held at about 90 ° C.

Below the extrusion openings was a precipitation bath, in which a deflection was appropriate. Between the precipitation bath surface and the extrusion openings was an air gap of about 6 mm formed, the continuous molding as a curtain went through. To support the spinning process was a Kühlbeblasung used parallel to the spin bath surface.

The coagulation of the continuous molding was carried out in the precipitation bath, where the curtain off Endlosformkörpern deflected by the deflection and obliquely upwards fed to a bundling device arranged outside the precipitation bath has been. By the bundling device, the curtain of the continuous molded body merged into a fiber bundle and then to further processing steps forwarded

Comparative Example 3 had a slightly improved spinning behavior, wherein However, spider problems occurred again and again. The endless molded bodies glued partially; the fiber fineness showed strong scattering.

Comparative Example 4

In Comparative Example 4 was otherwise identical to Comparative Example 3 Conditions on a long side of the rectangular nozzle a blowing device with a width B of 8 mm so attached that the cooling area up to the Extrusion openings extended, so no first shielding area available was.

The cooling gas flow had a speed at the exit from the blowing device of about 10 m / s.

Compared to Comparative Example 3, in the arrangement of Comparative Example 4, the air gap can be increased only insignificantly, the achieved spin security and the fiber data remained opposite to the values of the experimental example 3 unchanged.

Comparative Example 5

In this comparative example was as in Comparative Example 4 on a long Side of the rectangular nozzle a blowing device with a cooling gas flow width of 6 mm when exiting the blower mounted so that the Cooling area without interposition of a shielding area up to the extrusion openings extended. In contrast to Comparative Example 4 was instead a segmented rectangular nozzle uses a rectangularly drilled rectangular nozzle.

The speed of the cooling gas flow at the outlet at the blowing device was about 12 m / s.

In Comparative Example 5, the air gap could be increased to about 20 mm and the spinning security be significantly improved. However, fiber data did not improve observed, especially as repeatedly occurred bonds.

In the following Comparative Examples 6 to 8 by means of several, in a row next to each other arranged multi-channel compressed air nozzles generates a cooling gas flow. Of the Diameter of each compressed air nozzle was about 0.8 mm. The exit velocity of Single cooling gas flows from the blowing device was 6 to 8 in Comparative Examples more than 50 m / s. The individual cooling streams were turbulent. The gas supply to the nozzle took place By means of compressed air of 1 bar overpressure, to adjust the blowing speed was the Gas flow throttled by a valve.

The spinning head had a rectangular hole nozzle made of stainless steel drilled all over. Otherwise For example, the spinning system of Comparative Examples 3 to 5 was used.

Comparative Example 6

In Comparative Example 6, as in Comparative Example 5, the multi-port compressed air nozzle Mounted so that the cooling area directly to the extrusion openings extended, so no first shielding area was present.

With this arrangement, no improved results were observed, the spinning behavior could not be rated as satisfactory.

Comparative Example 7

In this experiment, the cooling gas flow was directed obliquely upwards in the direction of the nozzle and therefore had a component directed counter to the direction of transmission.

In Comparative Example 8, the spinning performance was deteriorated from Comparative Example 7.

Comparative Example 8

Compared to Comparative Example 7, the cooling gas flow had a direction of flow obliquely down in the direction of Spinnbadoberfläche on. The cooling gas flow therefore had a velocity component in the direction of transmission.

In the arrangement according to Comparative Example 8, the best results could be achieved. The coefficient of variation of the continuous molded articles was well below 10%. The spinning behavior was very satisfactory and left some room for finer titers or higher take-off speed too.

It should be noted in this context that in Comparative Examples 6, 7 and 8, there was a second shielding area between the cooling area and the precipitating bath surface in which the air substantially rested. example 1 2 3 4 5 6 7 8th hole density 1.86 1.96 1.86 0.99 2.81 3.18 3.18 3.18 off speed 40 30 30 32 34 31 35 40 Dope temperature 78 78 78 83 81 83 83 84 Düsenheiztemperatur 85 85 80 100 98 100 100 102 air gap L 5 6 6 16 20 18 16 22 Reynolds number 782 5211 4690 3388 3648 3908 Speed at the cooling gas flow outlet - - - 6 10 12 65 70 75 Distance between the outlet of the blowing device and the last row of continuous moldings A - - 35 23 22 32 32 32 Distance between the extrusion openings and the upper edge of the cooling gas outlet in the direction of passage H - - 0 0 0 0 10 10 Angle d. blowout β - - 0 0 0 0 -10 20 titres 1.72 1.66 1.74 1.55 1.4 1.47 1.35 1.33 Variation coefficient of the titer 30.3 23.5 25.8 18.5 24.3 18.6 21.1 7.6 spinning behavior 4-5 4 4-5 4 3 3-4 4 1-2 Cooling flow width / single bore diam. B 2 8th 6 0.8 0.8 0.8 Amount of gas per mm width 43 288 259 39 42 45

At the values of the summary table 1 is at the specified flow rates It can be assumed that at the high flow rates of Comparative Examples 6 to 8 a turbulent cooling gas flow was present.

Claims (21)

1. An Apparatus (1) for producing continuously molded bodies (5) from a molding material, such as a spinning solution containing cellulose, water and tertiary amine oxide, comprising a multitude of extrusion orifices (4), through which during operation the molding material can be extruded into continuously molded bodies (5), a precipitation bath (9) and an air gap (6) arranged between the extrusion orifices (4) and the precipitation bath (9), the continuously molded bodies (5) being passed during operation in successive order through the air gap (6) and the precipitation bath (9), and a gas stream (15) being directed at the continuously molded bodies (5) in the area of the air gap (6), characterized in that the air gap (6) directly after extrusion comprises a shielding area (20) and a cooling area (19) separated by the shielding area (20) from the extrusion orifices (4), the cooling area (19) being defined by the gas stream (15) designed as the cooling gas stream (15).
2. The apparatus according to claim 1, characterized in that, in addition to the first shielding area (20), the air gap (6) comprises a second shielding area (21) by which the cooling area (19) is separated from the precipitation bath surface (11 ).
3. The apparatus according to claim 1 or 2, characterized in that the width of the shielding area (20) in the direction of passage (7) is dimensioned such that the shielding area (20) in the direction of passage (7) extends at least over an expansion area (24) of the continuously molded bodies (5) which directly follows extrusion and extends in the direction of passage (7).
4. The apparatus according to any one of the aforementioned claims, characterized in that the extrusion orifices (4) are arranged on a substantially rectangular base in rows in a direction transverse to the direction (16) of the cooling gas stream (15).
5. The apparatus according to claim 4, characterized in that the number of the extrusion orifices (4) in row direction is greater than in the cooling gas stream direction (16).
6. The apparatus according to any one of the aforementioned claims, characterized in that within the precipitation bath (9) a deflector (10) is arranged by which during operation the continuously molded bodies (5) are deflected as a substantially planar curtain (8) to the precipitation bath surface (11), and that outside of the precipitation bath there is provided a bundling means (14) by which during operation the continuously molded bodies (5) are united to form a fiber bundle (13).
7. The apparatus according to any one of the aforementioned claims, characterized in that the width (D) of the cooling gas stream (15) in a direction transverse to the direction of passage (7) of the continuously molded bodies (5) through the air gap (6) is larger than the height (B) of the cooling gas stream in the direction of passage.
8. The apparatus according to any one of the aforementioned claims, characterized in that the cooling gas stream (15) is composed of a plurality of individual cooling gas streams.
9. The apparatus according to claim 8, characterized in that the individual cooling gas streams are arranged side by side in row direction.
10. The apparatus according to any one of the aforementioned claims, characterized in that the cooling gas stream is designed as a turbulent gas flow in the area where the continuously molded bodies (5) are passed through the air gap (6).
11. The apparatus according to any one of the aforementioned claims, characterized in that the cooling gas stream (15) has a velocity component oriented into the direction of passage (7).
12. The apparatus according to any one of the aforementioned claims, characterized in that the inclination (β) of the cooling gas stream (15) in the direction of passage (7) is greater than the expansion (γ) of the cooling gas stream (15).
13. The apparatus according to any one of the aforementioned claims, characterized in that the molding material prior to its extrusion has a zero shear viscosity of at least 10000 Pas, preferably of at least 15000 Pas, at 85°C.
14. The apparatus according to any one of the aforementioned claims, characterized in that the distance of the cooling area (19) from each extrusion orifice (4) is at least 10 mm in the direction of passage (7).
15. The apparatus according to any one of the aforementioned claims, characterized in that the distance I of the cooling area (19) in the direction of passage (7) from each extrusion orifice (4) in millimeters satisfies the following inequality: I > H + A • [tan(β) - 0.14] where H is the distance of the upper edge of the cooling gas stream in the direction of passage from the plane of the extrusion orifices at the exit from the blowing means (14) in millimeters, A is the distance in a direction transverse to the direction of passage between the exit of the cooling gas stream (15) of the blowing means (14) in millimeters and the row (22) of the continuously molded bodies (5) that is the last one in flow direction (16), in millimeters, and β is the angle in degrees between the cooling gas stream direction (16) and the direction transverse to the direction of passage (7).
16. The apparatus according to any one of the aforementioned claims, characterized in that the height L of the air gap (6) in the direction of passage (7) in millimeters satisfies the following inequality: L > I + 0.28 • A + B where I is the distance of the cooling area (19) from the extrusion orifices (4) in the area where the continuously molded bodies (5) are passed through the air gap (6), A is the distance in a direction transverse to the direction of passage (7) between the exit of the cooling gas stream (15) from the blowing means (14) and the row (22) of the continuously molded bodies (5) that is the last one in flow direction (16), in millimeters, and B is the height of the cooling gas stream (15) in a direction transverse to the cooling gas stream direction (16) in the direction of passage (7) at the exit of the cooling gas stream (15) from the blowing means (14).
17. The apparatus according to any one of the aforementioned claims, characterized in that the first shielding area consists essentially of air.
18. A method for producing continuously molded bodies (5) from a molding material, such as a spinning solution containing water, cellulose and tertiary amine oxide, the molding material being first extruded to obtain continuously molded bodies, the continuously molded bodies then being passed through an air gap (6) and being stretched in said air gap and being blown at with a gas stream (15) while passing the air gap (6), and subsequently the continuously molded bodies being guided through a precipitation bath (9), characterized in that the continuously molded bodies (5) in the air gap (6) are first passed through a shielding area (20) and then through a cooling area (19), the blowing operation being performed in the cooling area by means of the gas stream designed as the cooling gas stream.
19. The method according to claim 18, characterized in that the continuously molded bodies (5) after the cooling area (19) are passed through a second shielding area (21) before they immerse into the precipitation bath.
20. The method according to claim 18 or 19, characterized in that the velocity of the cooling gas stream, w₀, in dependence upon its width B, is set in the direction of passage of the continuously molded bodies through the air gap such that the Reynolds number formed with w₀ and B is at least 2500.
21. The method according to any one of claims 18 to 20, characterized in that the specific blowing force of the cooling gas stream (15) is set to a value of at least 5 mN/mm.

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