EP1232298B1 - Method and device for producing cellulose fibres and cellulose filament yarns - Google Patents

Abstract

The invention relates to a method for producing cellulose fibres or filaments from cellulose according to the dry-wet extrusion process, using aqueous amine oxides as the solvent. According to said method a) cellulose with a cuoxam-DP in the region of between 250 and 3000 is dispersed in an aqueous amine oxide, b) the dispersion obtained is converted at a high temperature by dehydration and shearing into a homogenous solution with a zero shear viscosity in the region of between 600 and 6000 Pa•s at 85 DEG C, c) the solution is fed to at least one spinneret, d) the solution in each spinneret is formed into at least one capillary and the capillary or capillaries of each spinneret are drawn through a non-precipitative medium and are subsequently guided through a spinning bath where the cellulose fibres are precipitated and e) at the end of the spinning bath section, the cellulose fibres are separated from the currents of the spinning bath by deviation and the threads are drawn off. The method is characterised in that the dispersion in step b) is converted into a solution with a relaxation time of between 0.3 and 50 s at 85 DEG C and that the solution in step c) is passed through a flow chamber, common to the spinnerets, in which the residence time of the solution is at least equal to its relaxation time at the spinning temperature.

Description

The invention relates to a process for the production of cellulose fibers or cellulose filament yarns of pulp by the dry wet extrusion process with aqueous amine oxides, in particular N-methylmorpholine-N-oxide, as solvent, in which a) pulp or a pulp mixture with a cuoxam DP between 250 and 3000 in aqueous amine oxide dispersed, b) the resulting dispersion at elevated temperature below Dehydration and shear in a homogeneous solution with a zero shear viscosity in the range of 600 to 6000 Pa · s at 85 ° C, c) the solution at least one spinneret feeds, d) the solution in each spinneret deformed at least one capillary and the capillary (s) of each nozzle delayed by a non-precipitating medium and then under Precipitation of cellulose threads leads through a Fällbadstrecke and e) the Cellulose threads at the end of Fällbadstrecke by distraction from the Fällbadströmen separates and pulls off the threads. The invention further relates to a Apparatus for producing cellulose fibers or filament yarns Pulp by the dry wet extrusion process with aqueous amine oxides as a solvent, with a spin pack with a spinneret plate and Spinnerets, a precipitation bath with two connected by a Fällbadpumpe Containers, a gap between the spinnerets and the Fällbadoberfläche in the upper of the two containers, and at least one withdrawal godet.

From US Pat. Nos. 4,246,221 and 4,416,698 dissolving cellulose in hydrous tertiary amine oxides, forming these solutions in spin capillaries with minimal shear, distorting the solution jets in a large air gap at low strain rate, precipitating the cellulose aqueous, amine oxide-containing spin bath and stripping the cellulose threads described on a godet. It is also pointed to the problem of sticking of the threads in the air gap and suggested a superficial moistening of the threads via a roller.
To avoid the sticking of the threads in the air gap, the addition of polyalkylene ether to the spinning solution is proposed in DD-A 218 121.
U.S. Patent No. 5,417,909 discloses a process which deforms the solution under medium to high shear in the spin capillaries, deforms the solution jets in a short air gap at medium to high strain rates, precipitates the cellulose, and passes the yarn through a spinning funnel detected and transported in DC. The relatively short air gap counteracts sticking and allows spinning with capillary densities up to 3 K / mm ² .
WO 96/20300 describes the relationships that result from the distance between two spinning capillaries and the path between spinneret and bundling element on the one hand and the air gap on the other hand and claims a device for stripping cellulose fibers at an angle <45 °. In the
Finally, EP-A 0 832 995 claims a device with a pivotable bundling element which ensures that, with a small air gap, the angle between the outermost filaments and the perpendicular bisector on the nozzle does not exceed 20 °.
To increase the capillary density, EP-A 0 584318 and 0 671492 claim the blowing of the threads in the air gap or a device for feeding the cooling gases. EP 795052 proposes the use of air with a defined water content for cooling. WO 94/28218 claims a method and a device for blowing in the air gap and WO 96/21758 finally the blowing in two zones.
All methods and devices pursue the goal of obtaining a very good spinning security when spinning fibers with a sufficient air gap and the largest possible spinneret of high capillary density. When spinning cellulose filament yarns, the requirements with regard to capillary density are lower, but the fineness-related limitation of the nozzle size leads to significantly higher demands on the take-off speed.

In all methods, the contactless guidance of the filaments through an air gap, cooling and / or superficial precipitation of the cellulose in the air gap by blowing with moist gases and the length of the air gap is in the foreground. The path that the thread must travel in the spinning bath and the consequent frictional force remains largely unconsidered. Thus, the pivoting of the bundling element in EP-A 0 832 995 leads to a significant enlargement of the spinning bath path when the angle between the filaments is reduced. Partial precipitation of the cellulose in the air gap by blowing with moist air makes the orientation considerably more difficult. Only in US Pat. No. 5,417,909, where the threads are guided by means of a spinning cone through a bath flowing in the same direction, this circumstance is taken into account. However, the friction force thread / spinning bath increases significantly with the path and the thread speed and leads to a decrease in the mechanical fiber values. When spinning fibers one tries to compensate for this by low take-off speeds.
When spinning filament yarns according to USP 5,868,985, a precipitation bath section of 0.5-8 cm flowing in the yarn direction is proposed in order to be able to work at high take-off speeds. This arrangement works with an air gap of 18 cm, is only suitable for single spinning with very small Kapillardichten, according to the examples only for monofilaments.

The object of the present invention is to provide a method and a device of the type mentioned, by the at high Capillary density, spinning safety and take-off speed spinning of fibers and multi-filament spinning of filament yarns with good mechanical properties Fiber properties is possible. In particular, the uniformity should and equality of the volume flows through each nozzle over the known ones Procedure be increased. Furthermore, the stated objectives are to be achieved without the Blowing the extruded capillaries in the air gap by cooling air or dergl. be achieved. Further advantages result from the following Description.

This object is according to the invention in the aforementioned method in that the dispersion in stage b) is dissolved in a solution with a relaxation time in the range of 0.3 to 50 s at 85 ° C and the solution in step c) through one of the nozzle (s) common inflow chamber passes, in which their residence time at least equal their relaxation time at the spinning temperature. The preferred relaxation time at 85 ° C is in the range of 1 to 5 s.

Spinning solutions of cellulose in a water-containing amine oxide have a pronounced viscoelastic behavior. This has the consequence that a considerable part of the energy required to transport or deform the spinning solution in the spinning channel is stored elastically and, after removal of the external constraint during the relaxation time, leads to a return deformation. As a result of the residence time in the inflow chamber exceeding the relaxation time λ _m , complete relaxation occurs and thus the zero shear viscosity is present above each nozzle, and the applied pressure leads to an equal volume flow through each nozzle.

The determination of the relaxation time from rheological data of the cellulose solution is described in detail in the literature (Ch Michels, Das Papier, (1998) 1, pp. 3-8). In practice, relaxation time spectra are present in the solutions since the cellulose has a distribution of the molecular weights. FIG. 1 shows the relaxation time spectra, ie the relative frequency H * of the relaxation time λ of four solutions of different pulps. The relaxation time λ _m is the relaxation time present at the relative frequency maximum.

In one embodiment of the method according to the invention subjects one the pulp or the pulp mixture of an enzymatic Pretreatment. This increases the inconsistency of certain pulps the molecular weight distribution. In a spruce sulphite pulp is e.g. transformed the bimodal distribution into a monomodal distribution.

In a further embodiment of the method according to the invention one can first produce a pulp to produce the pulp mixture with a Cuoxam-DP in the range of 600 to 3000 in water, then a pulp with a cuoxam DP in the range of 250 to 600 and also disperse and then the pulp mixture After removal of water, use moist press in step a). By the Admixture of a high molecular weight pulp fraction, the relaxation time maximum be increased, thereby increasing the gap width possible will be explained in more detail below.

Conveniently, the extruded capillaries are carried out individually and largely parallel through the non-precipitating medium and then through a less than 20 cm long Fällbadstrecke. Here are the spinnerets and further explained below thread guiding elements arranged so that the threads without mutual contact substantially parallel through the short Fällbadstrecke are passed and the friction between thread and precipitation bath is significantly reduced. Preferably, the Fällbadstrecke less than 5 cm. The Fällbadmenge, which is for felling and transporting the threads is in circulation is low at 1.5 to 7 l / nozzle.

Preferably, the cellulose fibers are deflected in step e) by an angle β> 10 ° from the Fällbadströmen and pulls the threads with a maximum thread tension of 5 cN / tex. The threads separate by deflecting by the angle β from the laminar falling Fällbadströmen and are detected by the Abziehgalette under this thread tension and adjusted to the desired take-off speed v _a . The withdrawn thread can be washed individually as a filament yarn, scavenged and dried, or combined via thread guides to the thread cable, washed, cut and washed as a fiber, aftertreated aviviert and dried.

The object is further achieved in the aforementioned device according to the invention that above the spinneret plate with the arranged in one or more rows or groups spinnerets a common Anströmkammer is arranged, the volume of the relationship V ≥ v L · λ m where V is the volume of the inflow chamber in cm ³ , v ˙ _{L is} the volume flow of the cellulose solution in cm ³ / s and λ _{m is} the relaxation time of the spinning solution at the frequency maximum of the relaxation time spectrum in s. The relaxation time λ _m is a size specific to the solution, the determination of which is described in the said article by Ch. Michels, in particular in the paragraph "Experimental Procedure" on pages 3 and 4. In this dimensioning of the chamber volume, the uniformity of the volume flow of the spinning solution, which is fed via a spinning pump, two or more of said spinnerets, reaches an optimum.

in der a die Spaltbreite in mm, λ_m die Relaxationszeit der Spinnlösung am Häufigkeitsmaximum des Relaxationszeitspektrums in s und v_a die Abzugsgeschwindigkeit in m/min bedeuten. Wie aus der Beziehung ersichtlich ist, besteht zwischen der Relaxationszeit λ_m und der Luftspaltbreite eine Korrelation derart, daß mit zunehmender Relaxationszeit λ_m die Luftspaltbreite vergrößert werden kann, ohne daß die Kapillardichte der Düse oder die Abzugsgeschwindigkeit verringert werden muß oder die Spinnsicherheit beeinträchtigt wird. Bei gegebenem Kapillardurchmesser kann daher mit zunehmender Relaxationszeit der Luftspalt vergrößert werden, d.h. der für eine hohe Faserqualität bei guter Spinnsicherheit (geringe Dehngeschwindigkeit, keine Verklebungen das Kapillaren) erforderliche Luftspaltbreite kann über die Relaxationszeit der Lösung eingestellt werden.According to a further aspect of the invention, the device mentioned above is characterized in that the width of the air gap and the relaxation time of the spinning solution satisfy the relationship:

a is the gap width in mm, λ _{m is} the relaxation time of the spinning solution at the frequency maximum of the relaxation time spectrum in s and v _{a is} the take-off speed in m / min. As can be seen from the relationship, there is a correlation between the relaxation time λ _m and the air gap width such that the air gap width can be increased with increasing relaxation time λ _m , without the capillary density of the nozzle or the withdrawal speed having to be reduced or the spinning reliability being impaired. For a given capillary diameter, the air gap can therefore be increased with increasing relaxation time, ie the air gap width required for a high fiber quality with good spinning reliability (low elongation rate, no adhesions to the capillaries) can be set via the relaxation time of the solution.

Preferably, the dimensions of the spinnerets, the gap width and the Fällbadstrecke satisfy the relationship x ≥ a + w w · 4D where x is the distance between two adjacent nozzle holes, a is the air gap width, w is the length of the precipitation bath section, and D is the nozzle hole diameter. For a more detailed explanation of the individual variables, reference is made to FIG.

In the preferred embodiment of the device according to the invention preferably made of ceramic thread guide elements are inserted into the bottom of the upper bath tank. These yarn guide elements represent openings in the container bottom, through which the precipitated yarn sheets leave the upper precipitation bath container together with precipitation bath streams. The thread guiding elements lead to a discharge of the precipitation bath in laminar partial flows, which independently detect and accelerate the individual bundles of filaments. Spinnerets and thread guide elements have expediently the same arrangement. The threads can pass through the Fällbadstrecke without mutual contact and are taken up almost parallel to the Abzugsgalette or take-off roll. The thread guiding elements are expediently arranged in rows or groups. In the nozzle plate, for example, having a diameter of 12.5 or 20 mm in one (preferably filaments) or more series (s) (preferably fibers), spinnerets are arranged so that the projection of the filaments in each case leads to a line and the filaments almost parallel can be absorbed by the take-off roll or -galette. In the case of fiber spinning, for example, 360 or 1020 or more capillaries are preferably arranged at 90 or 250 mm ² nozzle area per cap. The capillary density is thus about 4 / mm ² or more.

Conveniently, the spinnerets have a Hütchenform and is the nozzle area occupied by the spinning capillaries is equal to or less than the entrance surface of the thread guide elements. As a result, the threads in the essentially parallel to each other without mutual contact by the Transporting precipitation bath.

Preferably, the thread guide elements have a ratio of the diameter of entrance surface and exit surface E / e≥1 and is their edge rounded off at the exit. These thread guide elements are preferably for fiber production is used. They generally extend at least over the entire thickness of the container bottom. you have one Height h from 2 to 20 mm.

In another embodiment, the thread guide elements Ratio of height to light diameter of the exit surface h / e <1 and their edges are rounded at the entry and exit. These thread guide elements are used for filament yarn production and have in general, a height h of 2 to 5 mm. The inlet diameter E in the thread guide or the associated bottom plate opening is in general in the range of 12 to 20 mm. The diameter e on the Exit side of Fadenleitelements is generally in the area from 4 to 10 mm. The surface structure of the yarn guide elements is so procure that between their surfaces and the passing thread and Precipitation bath creates minimal friction. This purpose is also served by the rounded ones Edge.

Preferably, the upper bath tank on an inlet opening, the a calming chamber is connected upstream. The settling chamber may e.g. a filled with packing flow path and a subsequent filler body-free, i. include empty flow path. In the calming chamber the pumped-down precipitation is slowed down so that it substantially laminar enters the Fällbadbehälter.

Conveniently, the upper Fällbadbehälter has at least one Overflow whose overflow height is adjustable. By shifting the or the overflows in the vertical direction can change the Fällbadstrecke become, which results in further advantages, especially when piecing.

Preferably, the position of the upper Fällbadbehälters is also vertically adjustable relative to the spinning package. Through this and through Displacement of the overflow in the vertical direction can change the air gap width to be changed.

Furthermore, the arranged below the upper Fällbadbehälters Deduction godet can be adjusted vertically and / or horizontally. hereby In particular, the angle β of the deflection of the threads from the falling Fällbadströmen be changed.

Figur 1 eine graphische Darstellung des Relaxationszeitspektrums für vier verschiedene Celluloselösungen;

Figur 2 die schematische Darstellung einer Vorrichtung zur Durchführung des erfindungsgemäßen Verfahrens;

Figur 3 die schematische Draufsicht der in Figur 2 gezeigten Vorrichtung:

Figur 4 einen Axialschnitt einer Ausführungsform des Fadenleitelements bevorzugt für die Fasererspinnung;

Figur 5 einen Axialschnitt einer weiteren Ausführungsform des Fadenleitelements bevorzugt für die Filamenterspinnung; und

Figur 6 eine geometrische Darstellung des Spinnvorgangs zur Erläuterung einzelnen geometrischen Größen der Beziehung (III).

The inventive method and apparatus will now be explained with reference to the drawings and the examples. Show it

Figure 1 is a graphical representation of the relaxation time spectrum for four different cellulose solutions;

Figure 2 is a schematic representation of an apparatus for carrying out the method according to the invention;

3 shows the schematic plan view of the device shown in FIG. 2:

FIG. 4 shows an axial section of an embodiment of the thread guiding element, preferably for fiber spinning;

FIG. 5 shows an axial section of a further embodiment of the thread guiding element, preferably for filament spinning; and

Figure 6 is a geometric representation of the spinning process to explain individual geometric quantities of the relationship (III).

Figure 1 shows the relative abundance H * over the relaxation time of four cellulose solutions in aq. N-methylmorpholine N-oxide from different pulps, the details of which can be seen from the table contained in Figure 1. Where λ _{m is} the relaxation time at the frequency maximum in s, DP is the degree of polymerization (cuoxam), η _{o is} the zero shear viscosity of the solution in Pa · s, and c is the cellulose concentration of the solution in%. The relaxation time λ _m given in relationships (I) and (II), which correlates with the air gap width, is the relaxation time present at the relative frequency maximum. The solution p9915102 contains a pulp mixture in which the relaxation time of a spruce sulfite pulp (Cuoxam-DP 470, λ _m = 1.6 s) was raised to λ _m = 2.1 s by admixing a high-molecular pulp fraction.

FIG. 2 shows the spinning device with an upper precipitation bath container 1, a lower Fällbadbehälter 2 and a spin pack 3. The spin pack 3rd comprises a support plate with filter 4, a Anströmkammer 5 and more Spinnerets 6, the outlet side of the Fällbadoberfläche 7 a the Air gap forming distance. The bottom 10 of the upper Fällbadbehälters 1 is reinforced and according to the arrangement of the nozzles 6 equipped with a plurality of yarn guide elements 11 through which the filament bundles 12 exit together with Fällbadströmen from the container 1.

Below the container 1 is a vertically and horizontally displaceable Abzugsgalette 13 arranged, the thread bundles of all yarn guide elements 11 deflects from the Fällbadströmen 14 at an angle β and wound up under suitable tension. The Fällbadströme 14 get in the lower container 2 and are by means of pump 15 via the line 16 pumped back into the upper Fällbadbehälter 1. It is obvious that the passing of the filament bundles 12 Fällbadstrecke w up to the Place under the yarn guide elements 11 extends, where the filament bundles 12 from the Fällbadströmen 14 separate. The line 16 first opens in a partially filled with packing cavities 18, from the the Fällbadflüssigkeit flows through the opening 19 into the container 1.

From the top view of Figure 3 it can be seen that the yarn guide elements are arranged offset in the bottom 10 and the thread bundles 12th accrue next to each other on the Abzugsgalette 13.

FIG. 4 shows the ceramic thread guide element 11 for a Fiber bundles. As can be seen, the clear cross-section of the narrows Elements in the flow direction. This also applies to the thread element after Figure 5, which is provided for detecting a filament yarn. The preferred Rounding of the edges of the yarn guide elements 11 are in the figures not shown. The filament bundles separate immediately after passing the thread guide elements of the Fällbadstrom.

FIG. 6 schematically shows those contained in the relationship (III) geometric sizes. The reference numerals 6 'mean two nozzle holes with the hole diameter D. d means the central distance of the capillaries on the exit side of the nozzle hole 6 '. x is the distance between the both capillaries, and d 'is the central distance of the capillaries at entry in the spinning bath. P is the point where the fiber bundle of separates the Fällbadstrom. β is the deflection angle under which this separation β * is the (very small) angle between two adjacent threads in the precipitation bath.

example 1

In a stirred tank 0.49 kg of an enzymatically pretreated Fichtesulfitzelistoff (Cuoxam DP 580, dry content 44.9%) in 2.6 kg of NMMO (solids content 65.0%) containing 0.44 g of stabilizer, suspended and at 90 Distilled off ° C. and 500 to 25 mbar under shear 0.93 kg of water. The resulting cellulose solution of the composition 10% cellulose, 78.5% NMMO and 11.5% water contains no microscopic visible particles and shows after particle analysis by laser diffraction (see B. Kosan, Ch Michels Chemical Fibers International 49 [1999] s 50-54) has a content of 19 ppm with a particle diameter <9 μm. The zero shear viscosity of the solution was 3450 Pas, its relaxation time 4.1 s. Via a spinning pump (1.2 ml / rev, 25.8 rpm), 31 ml / min of spinning solution were introduced into the flow space of a filament yarn spinning station with 2 hatch nozzles of 12.5 mm diameter arranged in series, each with 30 spinning capillaries of 130 μm (L / D ≅ 1). The residence time in the Anströmraum with 5.4 cm  and 0.4 cm height was 4.3 λ _m . The spinning solution was deformed in the spinnerets to a yarn sheet under a shear of 39 900 1 / s, in an air gap of 35 mm in length with a strain rate of 220 1 / s in the ratio 12.9 warped, the cellulose in the vertical precipitation bath with a length of 3.5 cm precipitated, the threads transported by 2 Fadenleitelemente according to Figure 5 (e = 5 mm, h = 4 mm) in the bottom (E = 13 mm) of the upper spin bath, at an angle of 40 ° from the nearly laminar flowing Fällbadstrahlen deflected, parallel fed under a thread tension of ~ 2, 5 cN / tex the Abzugsgalette, withdrawn at a speed of 500 m / min and then under a thread tension ≤ 1.25 cN / tex, dried, aviviert and wound up.
The filament yarns are characterized by the following parameters: fineness 40 dtex (30) tear strength 43.7 cN / tex coefficient of variation 2.3% elongation at break 8.5% Knot breaking strength 34.1 cN / tex Uster (lethargic) 0.1%

Example 2

0.18 kg of a cotton linter pulp (Cuoxam-DP 1907) are sheared with water at a ratio of 1:20 with water. 4.20 kg of a spruce sulphite pulp (Cuoxam-DP 450) are slowly added to the homogeneous suspension with further shearing. A suction press separates the cellulosic mixture.
Into a stirred tank, carry the cellulosic mixture and 30.42 kg of NMMO (dry content 84%) whose alkalinity was adjusted to pH 11.2 by addition of NaOH. Under temperature, vacuum and shear, 7.69 kg of water are distilled off, the suspension in a clear solution of the composition 13.0% cellulose, 75.9% NMMO and 11.1% water with a zero shear viscosity of 3850 Pas and a relaxation time of 3.1 s passes over.
Using a spinning pump (4.8 ml / U, 32.7 rpm), 157 ml / min of spinning solution were introduced into the flow space of a filament yarn spinning station with 4 sleeve nozzles of 20 ° arranged in series, each with 90 spinning capillaries of 120 μm (L / D -1). , The residence time in the flow-through space of 13.0 × 4.0 × 0.35 cm was 2.3 λ _m . The spinning solution was deformed in the spinnerets at a shear rate of 42 900 1 / s to the yarn sheet, in an air gap of 28 mm length and a strain rate of 245 1 / s in the ratio 11.7 warped, the cellulose in a vertical Fällbadstrecke of 4, 0 cm precipitated, transported by 2 Fadenleitelemente according to Figure 5 (e = 7mm, h = 4 mm) in the bottom (E = 18 mm) of the upper spinning bath box, deflected at an angle of 50 ° from the Fällbadströmen, parallel under a thread tension of - 3 cN / tex fed to a take-off godet, withdrawn at 450 m / min and then washed under a yarn tension ≤ 1.5 cN / tex, dried, scoured and reeled.
The filament yarns had the following properties: fineness 150 dtex f (90) tear strength 41.7 cN / tex coefficient of variation 3.2% elongation at break 9.1% Knot breaking strength 28.9% Uster (lethargic) 0.1%

Example 3

7.66 kg / h enzymatically activated and stabilized Fichtesulfitzellstoff (Cuoxam DP 480, solids content 50.0%) and 29.0 kg / h of N-methylmorpholine N-oxide (NMMO, solids content 84.0%) are continuously heated CO-ROTATING PROCESSOR 25 CONTI (LIST AG ARISDORF) and dispersed into a homogeneous mash. This passes through a mash metering pump in the heated dissolver DISKOTHERM B 63 CONTI (LIST AG ARISDORF), where at mass temperatures of 90 ° C and 20 mbar vacuum under 4.7 kg / h of water removal 27.0 l / h homogeneous cellulose solution of the composition 12.0% cellulose, 76.3% NMMO and 11.7% water are formed. The solution has a zero shear viscosity of 3100 Pas and a relaxation time of 1.9 s at 85 ° C.
About 451 ml / min spinning solution with 85 ° C melt temperature pass through the nozzle filter via a spinning pump (9.6 ml / U, 47 rpm) and pass through an area of 9.2 × 6.2 × 0.8 = 45.6 cm ³ (Residence time t ≅ 3 λ _m ) to 13 in 3 rows arranged spinneret with each 350 spinning capillaries of 100 pm diameter. At a shear rate of 16,850 1 / s, the solution is deformed in the 4550 nozzle channels, distorted in an air gap of 20 mm at a strain rate of 90 1 / s in a ratio of 9.5, the cellulose precipitated in a spinning bath with 6 cm Badstrecke, at an angle of 35 °, the threads separated from the laminar Fällbadströmen and fed at a withdrawal speed of 120 m / min by means of Abzugsgalette the aftertreatment and drying.
In the bottom of Spinnbadkastens were similar to the Hütchenanordnung in the nozzle plate 13 Fadenleitelemente gem. FIG. 4 with E = 13 mm; e = 9 mm and h = 20 mm used in ceramic.
The resulting staple fibers had the following mechanical properties: fineness dtex 1.3 Tensile strength tr. CN / tex 43.5 Wet tensile strength CN / tex 36.5 Elongation at break tr. % 14.5 Wet elongation at break % 15.1 Loop tensile strength CN / tex 15.6 cutting length mm 38

Example 4

0.23 kg of a high molecular weight Fichtesulfitzellstoffes (Cuoxam DP 1100) are whipped in a turbomixer in the ratio 1:16 with water. For homogeneous suspension, 4.45 kg of a Fichtesulfitzellstoffes with a Cuoxam DP of 480 and beats on in small portions. The homogeneous pulp mixture is separated from the water via a sieve belt system and receives 9.36 kg of pulp with a solids content of 50%. This pulp mixture is metered for 1 hour together with 35.9 kg NMMO (dry content 84%), which simultaneously contains 10 g of a stabilizer in a heated CO-ROTATING PROCESSOR 25 CONTI (LIST AG ARISDORF) and dispersed with simultaneous removal of water from 2, 26 kg to a homogeneous mash. By means of a mash metering, 43.0 kg / h of mash enter the heated kneader of the type DICKOTHERM B 63 CONTI (LIST AG ARISDORF), where at melt temperatures of 93 ° C. and 22 mbar vacuum under 4.0 kg / h of water removal 39 kg / h homogeneous cellulose solution of the composition 12.0% cellulose, 77.3% NMMO and 10.7% water. The solution has a zero shear viscosity of 3750 Pas and a relaxation time of 2.1 s. Cellulose precipitated from the solution has a cuoxam DP of 506.
Via a spinning pump (9.6 ml / rev, 57 rpm), 547 ml / min of spinning solution at a melt temperature of 85 ° C. pass through the nozzle filter and pass through an area of 9.2 × 6.2 × 0.8 = 45.6 cm ³ (Residence time t ≅ 2.4 λ _m ) to 5 in 2 rows arranged spinneret each with 1020 spinning capillaries of 80 microns in diameter. At a shear rate of 13,770 1 / s, the solution is deformed in the 5100 nozzle channels, distorted in an air gap of 22 mm at a strain rate of 67 1 / s in a ratio of 8.8, the cellulose precipitated in a spinning bath with 5 cm Badstrecke, at an angle of 30 °, the threads are separated from the laminar precipitation bath streams, withdrawn at a draw-off speed of 100 m / min, combined into a thread cable, washed, cut into staple fibers, aftertreated and dried.
In the upper Spinnbadkasten 5 Fadenleitelemente gem. Figure 5 arranged in 2 rows with h = 20 mm, E = 20 mm and e = 10 mm.
The transport of the cooled precipitation bath (6 - 8 ° C) between the lower and upper spin bath tanks was carried out via a membrane pump with approx. 35 l / min.
The staple fibers had the following mechanical fiber parameters: fineness dtex 1.7 Tensile strength tr. CN / tex 42.8 Wet tensile strength CN / tex 35.9 Elongation at break tr. % 15.5 Wet elongation at break % 15.9 Loop tensile strength CN / tex 15.1 cutting length mm 38

Claims (17)

1. A process for producing cellulose fibers or filaments from cellulose by the dry-wet extrusion process with aqueous amine oxides, in particular N-methylmorpholine N-oxide as the solvent, whereby

   a) cellulose or a cellulose mixture with a cuprammonium DP in the range of 250 to 3000 is dispersed in aqueous amine oxide,

   b) the resulting dispersion is converted to a homogeneous solution having a zero shear viscosity in the range of 600 to 6000 Pa·s at 85 °C at an elevated temperature while removing water,

   c) the solution is sent to at least one spinneret,

   d) the solution is shaped in each spinneret to form at least one capillary, and the capillary (capillaries) of each nozzle is (are) passed through a non-precipitating medium while drawing and then passed through a precipitation bath where the cellulose fibers are precipitated, and

   e) the cellulose fibers are separated by deflection from the precipitation bath streams at the end of the precipitation bath zone, and the fibers are drawn off,

   characterized in that the dispersion in step b) is converted to a solution with a relaxation time in the range of 0.3 to 50 sec at 85 °C, and
   the solution in step c) is passed through an inflow chamber in which its dwell time is at least equal to its relaxation time at the spinning temperature.
2. The process according to Claim 1, characterized in that the cellulose or the cellulose mixture is subjected to an enzymatic pretreatment.
3. The process according to Claim 1 or 2, characterized in that to produce the cellulose mixture, first a cellulose having a cuprammonium DP in the range of 600 to 3000 is dispersed in water, then a cellulose having a cuprammonium DP in the range of 250 to 600 is added and dispersed, and next the cellulose mixture, wet from the press, is used in step a) after removing the water.
4. The process according to one of Claims 1 through 3, characterized in that the capillaries are passed individually and largely in parallel through the non-precipitating medium and then through a precipitation bath zone less than 20 cm long.
5. The process according to one of Claims 1 through 4, characterized in that the cellulose fibers in step e) are deflected out of the precipitation bath streams by an angle β > 10° and are drawn off at a maximum thread tension of 5 cN/tex.
6. A device for producing cellulose fibers or filaments from cellulose by the dry-wet extrusion process with aqueous amine oxides as the solvent, having
   a spinning package (3) with a spinneret plate and spinnerets (6),
   a precipitation bath in two containers (1, 2) connected by a precipitation bath pump (15),
   a gap (a) between the spinnerets (6) and the surface (7) of the precipitation bath in the upper container of the two containers (1, 2), and
   a draw-off speed roller (13),
   characterized in that a common inflow chamber (5) is arranged above the spinneret plate with the spinnerets (6) arranged in one or more rows or groups, the volume of this inflow chamber being described by the equation V ≥ v L • λm where V is the volume of the inflow chamber in cm³, v ˙_L denotes the volume flow of the cellulose solution in cm³/sec and λ_m denotes the relaxation time of the spinning solution at the maximum frequency of the relaxation time spectrum.
7. The device for producing cellulose fibers or filaments from cellulose by the dry-wet extrusion process with aqueous amine oxides as the solvent, having
   a spinning package (3) with a spinneret plate with spinnerets (6),
   a precipitation bath in two containers (1, 2) connected by a precipitation bath pump (15),
   a gap (a) between the spinnerets (6) and the surface (7) of the precipitation bath in the upper container of the two containers (1, 2), and
   a draw-off speed roller (13),
   characterized in that the width of the gap (a) and the relaxation time of the spinning solution are defined by the equation

   

   where a is the gap width in mm, λ_m is the relaxation time of the spinning solution at the maximum frequency of the relaxation time spectrum and v_a is the draw-off rate in m/min.
8. The device according to Claim 6 or 7, characterized in that the dimensions of the spinnerets (6), the gap width (a) and the precipitation bath zone (w) are defined by the equation x ≥ a + w w ·4D where x denotes the distance between two adjacent nozzle holes (6'), a is the air gap width, w is the length of the precipitation bath zone, and D is the nozzle hole diameter.
9. The device according to one of Claims 6 through 8, characterized in that fiber guide elements (11), preferably made of ceramic, are inserted into the bottom (10) of the upper bath container (1).
10. The device according to Claim 9, characterized in that the fiber guide elements (11) are arranged in rows or groups.
11. The device according to Claim 9 or 10, characterized in that the spinnerets (6) have a cap shape and the nozzle area covered by the spinning capillaries is equal to or less than the inlet area of the fiber guide elements (11).
12. The device according to one of Claims 9 through 11, characterized in that the fiber guide elements (11) have a ratio of the diameter of the inlet area and outlet area E/e ≥ I and their edge is rounded at the outlet.
13. The device according to one of Claims 9 through 11, characterized in that the ratio of the height the fiber guide elements (11) to the inside diameter of the outlet area is h/e < I, and their edges are rounded at the inlet and outlet.
14. The device according to one of Claims 6 through 13, characterized in that the upper bath container (1) has an inlet opening (19) downstream from a settling chamber (18).
15. The device according to one of Claims 6 through 14, characterized in that the upper bath container (1) has at least one overflow (9) the height of which is adjustable.
16. The device according to one of Claims 6 through 15, characterized in that the position of the upper precipitation bath container (1) is adjustable vertically with respect to the spinning package (3).
17. The device according to one of Claims 6 through 16, characterized in that the draw-off roller (13) arranged beneath the upper precipitation bath container (1) is adjustable vertically and/or horizontally.

Images