EP1268888B1 - Method and device for the production of cellulose fibres and cellulose filament yarns - Google Patents

Abstract

A method for the production of cellulose fibers or filaments from cell material, by the dry-wet extrusion method with aqueous amine oxides, in particular, N-methylmorpholine-N-oxide as solve is described comprising the following steps: a) dispersion of a cell material, or a cell material mixture with a cuoxam DP from 250-3000, in aqueous amine oxide, b) transformation of the obtained dispersion, by water evaporation with shear, at elevated temperature, into a homogeneous solution with a zero shear viscosity of 600 to 6000 Pa.s and a relaxation time of 0.3 to 50 seconds all at 85° C., c) feeding the solution to a spinning jet, previous to which it is passed through flow chamber prior the jet(s), in which the retention time at the spinning temperature, d) forming the solution into at least one capillary in each spinning jet, drawing the capillary(ies) from each jet through anon-precipitating medium and then precipitating the cellulose fibers on drawing through a precipitating bath and e) at the end of the precipitating bath section drawing off the fibers by deflecting the precipitation flow. In stage d) the capillary bundle(s) are treated with a gas flow, just before the entry thereof into the precipitating bath, at an angle alpha to the capillary flow, wherein 45°<alpha<90°.

Description

The main application (WO 01/34885) relates to a process for the production of cellulose fibers or filaments from pulp by the dry Naßextrusionsverfahren with aqueous amine oxides, in particular N-methylmorpholine N-oxide as a solvent, in which a) pulp or a pulp mixture with b) dispersing the dispersion at elevated temperature with dehydration and shearing into a homogeneous solution having a zero shear viscosity in the range of 600 to 6,000 Pa · s and a relaxation time in the C) the solution at least one spinneret feeds and previously by a nozzle or the (n) common inlet chamber conducts, in which their residence time at least equal to their relaxation time at the spinning temperature d) the solution in each spinneret is deformed into at least one capillary and the capillary (s) of each nozzle are under Deflection by a non-precipitating medium and then leads to precipitation of the cellulose fibers through a precipitation bath, and e) separates the cellulose fibers at the end of Fällbadstrecke by deflection of the Fällbadströmen and stripping the threads. The main application further relates to an apparatus for producing cellulosic fibers or filaments of cellulose by the dry-wet extrusion process with aqueous amine oxides as solvent with a spin pack having a spinneret plate, spinnerets and a common upstream chamber arranged above the spinneret plate and the spinnerets arranged in a row, the volume of which satisfies the relation 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 at the frequency maximum of the relaxation spectrum of the spinning solution with a precipitation bath in two containers connected by a precipitation bath pump, a gap between the spinnerets and the precipitation bath surface in the upper of the two containers, and a withdrawal godet.

DE 199 54 152 discloses a process for the production of cellulose fibers after Dry-wet-extrusion process with aqueous aminoxides in which the pulp with a Cuoxam-DP is dispersed in the range of 250 to 3000 in aqueous amine oxide, the dispersion obtained at elevated temperature with dehydration and shear in a homogeneous solution having a zero shear viscosity in the range of 600 - 6000 Pa s at 85 ° Celsius is transferred, the dispersion in a solution having a relaxation time in the Range is transferred from 0.3 to 50 s. Subsequently, the solution of a spinneret supplied, wherein the solution is passed through a common inflow chamber, in which their Residence time is at least equal to their Retaxationszeit at the spinning temperature.

WO 96/21758 discloses a method for producing extruded articles according to the Lyocell method wherein a cellulose solution is passed through an air gap into a coagulation bath is extruded. The air gap comprises a first region in the region of the nozzle and a second area farther from the nozzle, wherein the moisture content of the air in the first Region is kept at a lower content than the moisture content in the air in the second region.

US-A-5,984,655 relates to a spinning apparatus for performing a dry NaB spinning process, comprising a spinneret and a coagulation bath. Furthermore, the Device a blowing device for cooling the extruded filaments within the Air gap between the nozzle and the coagulation bath. Furthermore, the device comprises Means for bundling the extruded filaments within the spinning bath.

The main application (WO 01/34885) was based on the object, a method and to provide a device by which at high capillary density, Spinning safety and take-off speed the spinning of fibers and the multiple spinning of filament yarns with good mechanical properties Fiber properties is possible. In particular, the uniformity should be and equality of the volume flows through each nozzle over the known ones Procedure be increased.

In the main application (WO 01/34885) it is stated that the gap width a on the one hand with the relaxation time λ _{m of} the spinning solution at the frequency maximum of Relaxationszeitpektrums at the spinning temperature and the take-off speed v _a (equation II) and on the other hand with the distance x between two adjacent nozzle holes , the length of Fällbadstrecke w and the nozzle hole diameter D (Equation III) correlates. Since the relaxation time in the second and the residence time of the deformed solution in the gap a move in the millisecond range, in practical operation much larger gap widths should be achievable than before. For the spinning of fibers and filaments, the maximum adjustable gap, ie the length at which the "solution thread" is oriented more or less strongly in accordance with the draft ratio, is of particular importance. As the gap width increases, the stretching speed and thus the thread tension decreases. This has a positive effect on the mechanical fiber parameters, in particular the elongation at break and loop tearing force. On the other hand, the spinning reliability decreases with increasing gap width, since the risk of touching the capillaries increases. This is especially true when spinning fibers, where you work anyway with the largest possible capillary density. It is therefore essential to set a maximum gap, which is consistent with the spinning safety, but also gives optimum mechanical fiber parameters. The decrease in yarn tension is also a prerequisite for increasing the take-off speed, especially when spinning filament yarns.

Object of the present invention is therefore in the context of the parent application the creation of a method and a device by with high capillary density, spinning safety and take-off speed the spinning of fibers and the multiple spinning of filament yarns with good mechanical fiber properties is possible. Especially if the spinning safety is observed, the mechanical fiber properties, namely the elongation at break and the loop tear strength improved become. In addition, an increase of the take-off speed, especially when spinning filament yarns are made possible.

This object is according to the invention in the aforementioned method solved in that in the step d) the capillary share (s) just before entering the precipitation bath with a gas at an angle α flows to the capillary running direction in the range 45 ° <α <90 °. Surprisingly, it has been found that, as a result, the gap width considerably, namely by 50 to 100% or more, without the spinning security is affected by this. By the larger gap width reduced strain rate and thread tension in the gap leads to the desired improvement of said mechanical Fiber parameters and the possibility of the withdrawal speed to increase.

In particular, the invention task is also solved by that one in stage d) the capillary flock just before their entry into the precipitation bath flows with a gas, wherein the precipitation bath at the interface to the air gap and the gas flow rectified flow components exhibit. The effect of increasing the maximum gap width is thus also achieved when the gas flow and the Fällbadströmung have rectified horizontal flow components.

Conveniently, one flows the capillary shares with a flat, even, over the entire width of the series of capillary shares reaching gas stream. It is important that the gas flow effective at the points of immersion of the capillary shares in the precipitation bath becomes. The spinning security affecting spinning dysfunctions, the almost exclusively by touching the capillaries at the entrance are caused in the spinning bath are significantly reduced. Surprisingly, it has been found that despite the flow of capillary shares with the gas flow, the movement of Spinnbadoberfläche Dipping the capillary flock is calmed. Generally it can be said that the flow of capillary shares a mechanical effect caused the immersion site; In particular, the cooling of the capillary shares plays not matter.

The object is further in the aforementioned device According to the invention solved in that in the gap a at least one Slot die with one at an angle α to Kapillarenlaufrichtung in the range 45 ° <α <90 ° directed nozzle slot to the flow the capillaries is arranged prior to their entry into the precipitation bath. The Slit width may be, for example, 0.05 to 5 mm, e.g. 1 mm. The Slot length corresponds at least to the length of the row of Kapill to be flown renscharen. These are preferably in a row (not in several one behind the other staggered rows) arranged so that all flocks in be flowed through the gas stream in the same way.

Preferably, the device mentioned above is according to the invention characterized in that the upper bath container on the one hand the capillary shares at least one inlet opening for Fällbadflüssigkeit and on the other hand, the capillaries have at least an overflow and the slot die with respect to the row of capillary shares on the same side as the inlet opening (s) is arranged. Thereby have the Fällbadflüssigkeit and the gas stream in the gap gleichgerichtere horizontal flow components, what for the increase in the maximum Slit width is conducive.

Preferably, the slot die with the at least one overflow mechanically connected. The slot gas nozzle is therefore independent from the vertical setting of the overflow and thus the size of the Gap width always the same (small) distance from the Fällbadoberfläche.

in der a die Spaltbreite in mm, λ_m die Relaxationszeit am Häufigkeitsmaximum des Relaxationsspektrums der Spinnlösung, v_a die Abzugsgeschwindigkeit in m/min, N die Kapillardichte in cm^-2 und D den Düsenlochdurchmesser in mm bedeuten. Der gegenüber der Gleichung II der Hauptanmeldung addierte Term 1/ N·D berücksichtigt die erfindungsgemäß erreichte Vergrößerung der Spaltbreite durch die Anströmung der Kapillarscharen kurz vor ihrem Kontakt mit dem Fällbad. Es ist ersichtlich, daß diese Spaltverbreiterung mit zunehmender Kapillardichte geringer wird.The apparatus for the production of cellulose fibers or filaments mentioned above is further characterized in that the width of the gap a and the relaxation time of the spinning solution satisfy the following relationship

a is the gap width in mm, λ _{m is} the relaxation time at the frequency maximum of the relaxation spectrum of the spinning solution, v _{a is} the draw speed in m / min, N is the capillary density in cm ^-2 and D is the nozzle hole diameter in mm. The term added to equation II of the parent application 1 / N · D takes into account the invention achieved enlargement of the gap width by the flow of Kapillarscharen shortly before their contact with the precipitation bath. It can be seen that this gap broadening becomes smaller with increasing capillary density.

Preferably, the dimensions of the spinnerets, the gap width a and the Fällbadstrecke w satisfy the relationship x ≥ a + w w · 3.5D in the x the distance between two adjacent nozzle holes, a the gap width, w the length of the Fällbadstrecke and D denote the nozzle diameter. From the comparison with relationship III of the parent application shows that the flow of the capillary share (s), the distance between two adjacent nozzle holes of the nozzle can be reduced by 1/8, without the objectives of the invention, namely retention of the spinning safety in improving mechanical Fiber properties are impaired.

Figur 1 das Relaxationszeitspektrum einer Spinnlösung mit 12 Masse-% Cellulose (Cuoxam-DP 480) bei der Spinntemperatur von 85°C;

Figur 2 die schematische Darstellung einer Vorrichtung zur Herstellung von Cellulosefasern und -filamenten; und

Figur 3 die schematische Aufsicht der in Figur 2 gezeigten Vorrichtung.

The invention will be explained in more detail with reference to the drawing and the example. Show it

FIG. 1 shows the relaxation time spectrum of a spinning solution with 12% by mass of cellulose (Cuoxam-DP 480) at the spinning temperature of 85 ° C .;

Figure 2 is a schematic representation of an apparatus for producing cellulose fibers and filaments; and

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

Figures 2 and 3 show the upper Fällbadbehälter 1 of an inventive Spinning device. The spinnerets 6, of which in Figure 2 only is visible, are provided with Anströmkammern, as shown in the Main application is described and illustrated in detail. The exit sides the spinnerets 6 have from the Fällbadoberfläche 7 a the air gap a forming distance. The bottom 10 of the Fällbadbehälters 1 is corresponding the arrangement of the nozzles 6 equipped with a plurality of yarn guide elements 11, through the thread bundles 12 together with Fällbadflüssigkeitsströmen 14 from the Exit container 1. The thread bundles 12 of all yarn guide elements 11 are deflected from the Fällbadströmen 14 at an angle and under suitable Tension wound up. The Fällbadströme 14 get into the lower Fällbadbehälter (not shown) and are by means of a pump (not shown) via the line 16 pumped back into the upper Fällbadbehälter 1. The passing of the filament bundles 12 Fällbadstrecke w ranges from the bath surface to the point under the thread guide elements 11, where the filament bundles 12 separate from the Fällbadflüssigkeitströmen 14. The line 16 opens into a partially filled with packing (not represented) settling chamber 18, from which the Fällbadflüssigkeit through the openings 19 flows into the actual container 1. From FIG. 3 It can be seen that the yarn guide elements 11 in the bottom 10 in a Row are arranged and the thread bundles 12 parallel to each other to Deduction godet (not shown) run.

The Fällbadbehälter 1 has two overflows 9, which are vertically adjustable and thus determine the Fällbadniveau and the width of the gap a. At the overflows 9 is by means of the holder 23, a nozzle tube 20 with a across the row of nozzles 6 and the row of capillary shares 26 reaching Slot 21 attached. The nozzle tube 20 is on both sides of the line 24 subjected to a slight flow of air through a needle valve (not shown) can be adjusted. The air flow 25 leaves the Slot 21 (outlet 150 mm x 1 mm) linear over the entire Width and inclined to the bath surface 7, so that the capillary shares directly before entering the precipitation bath with the air flow in contact come. The slot nozzle is located about 10 mm above the precipitation bath surface.

It was found that by using the device according to Figures 2 and 3, but first without Luftanblasung the capillary shares by means 20,21 in the direction of the immersion of the capillaries in the spinning bath, and using four Monofildüsen, ie four Hütchendüsen (0 = 12.5 mm), each with only one bore of 200 .mu.m diameter, the width of the gap a in spinning between 10 and 300 mm can be changed continuously without any spin disturbances are observed. A gap width a> 300 mm did not allow the spinning apparatus. The experiments were carried out with a 12% by mass cellulose solution in aqueous N-methylmorpholine N-oxide (NMMO) whose relaxation time spectrum is shown in FIG. 1 and whose λ _m was 3.0 s. To determine the relaxation time from the rheological data of the cellulose solution, reference is made to Ch. Michels, Das Papier, (1998) 1, pp. 3-8. The take-off speed was 100 m / min. Increasing the take-off speed to 300 m / min led to the same result. If one replaces the Hürchendüsen by those with each 30 holes of 140 microns in diameter, the maximum interference-free gap a goes back to about 40 or 60 mm.

With the same arrangement, but with linear, surface-shaped blowing the capillary flocks just before entering the precipitation bath is a clear Increase of the maximum possible gap width a from about 40 to 65 mm or from about 60 to 100 mm detectable. In addition to the increase in the maximum possible air gap is a significant calming of the Kapillarlaufes to be observed when entering the precipitation bath. The frequency of capillary contact is significantly lower and therefore the probability the appearance of spinning dysfunctions.

When using nozzles with a nozzle hole diameter of 90 microns, the maximum reliable adjustable gap width a increases, and when using nozzles with a diameter of 200 microns, this gap width decreases. In the transition to hatch nozzles ( = 20 mm) with the same number of holes, ie decreasing capillary density, an increase of the maximum adjustable gap is observed. With 30 holes per nozzle, the capillary density of the small nozzle nozzle is N = 47 cm ^-2 and that of the large nozzle nozzle is 15 cm ^-2 . With the capillary density of 15 cm ^-2 , but otherwise the same conditions, the maximum possible gap width increases again from about 65 to 90 mm and from 95 to 130 mm. These changes can be sufficiently described by the above-mentioned modified equation IIa. With the aid of the method according to the invention and the spinning device, it is therefore possible to increase the capillary density without the risk of the occurrence of spinning disorders increasing. For the distance between two adjacent nozzle holes then the empirical relationship IIIa applies.

Further investigations of the linear sheet-like blowing short Before entering the capillary flocks in the precipitation bath make it clear that the largely laminar flow of air in the direction of the capillary run a significant disorder experiences. The transition at the phase interfaces Capillary / gas or air and capillary / precipitation bath changes. The movement of Spinning bath surface when immersing the capillaries appears calmer. The Spider disorders, which begin almost exclusively in the mutual Touch the capillaries when entering the spin bath are thus much less likely.

The invention is further illustrated by the following example.

example

A moist mixture (dry content 50.2%), consisting of 188 g spruce sulphite pulp (Cuoxam-DP 480), 10 g cotton linters pulp (Cuoxam-DP 1907) and 0.4 g of stabilizer is added in 1850 g of NMMO (Dry content 75%) dispersed, in a kneader with a vertical kneader shaft registered under vacuum and shear at a temperature of 90 ° C. Distilled off 1255 g of water and by further "shear stirring" in a microscopic homogeneous cellulose solution of the composition 11.0% cellulose, 77.1% NMMO and 11.9% water. The relaxation time at a Spinning temperature of 85 ° C was 3.0 s, the zero shear viscosity 3450 Pa · s. The deformation of the solution into threads takes place in a piston spinning apparatus, their hot water heated spinneret intake either four spiders with 12.5 mm (30 mm pitch center of the nozzle to the center of the nozzle) or 3 spinnerets with 20.0 mm diameter (40 mm pitch) can accommodate. Below the spinning part is the spin box according to Figures 2 and 3.

For each experiment, the maximum gap width a _{max was determined} without and according to the invention with air inflow. After spinning, the filaments were spooled, washed, cut into 50 mm stacks, cured and dried. They were then subjected to textile testing. The results are shown in Tables 1 and 2. The application of air took place in the manner described above with reference to FIGS. 2 and 3. The nozzle outlet opening was 150 mm x 1 mm. The capillaries were contacted with the air stream immediately before entering the precipitation bath. The air nozzle was directed obliquely downwards with the slot. The slot nozzle was located approx. 10 mm above the precipitation bath surface.

From the tables it can be seen that by blowing a considerable broadening of the air gap a, namely by at least 50% to a maximum of 200% is possible without disturbances occur in the spinning operation. This is accompanied by a considerable improvement in the elongation at break, dry, and the loop tearing force.  hat  bore capillary density Abzugsgesch. a _max. [Mm] number [Mm] [Mm] cm ^-2 m / min without With 1 12 0,200 --- 100/300 > 300 > 300 2 12 0.140 47 100 40 60 3 12 0.140 47 300 60 90 4 20 0.140 15 5 100 40 80 5 20 0.140 15 300 60 130 6 20 0.140 15 500 80 180 7 12 0,090 47 100 40 70 8th 12 0,090 47 300 60 105 9 20 0,090 350 100 10 30 number Fineness [dtex] Tensile strength tr. [CN / tex] Elongation at break tr. [%] Loop tearing force [cN / tex] without With without With without With 1 1.63 41.2 17.8 19.7 2 1.62 42.5 41.5 13.3 16.9 13.9 15.9 3 1.68 44.1 42.7 11.9 15.4 11.7 14.7 4 1.67 41.6 40.6 14.5 17.4 14.3 16.5 5 1.61 43.2 42.4 12.7 15.9 11.9 15.1 6 1.63 44.8 43.9 10.2 14.7 9.7 14.3 7 1.65 42.8 42.1 13.1 17.0 13.8 14.9 8th 1.64 44.9 43.1 11.3 15.1 11.8 13.9 9 1.40 43.9 43.1 12.8 16.1 14.1 15.9

Claims (7)

1. A method for the production of cellulose fibers or filaments from cellulose according to the dry-wet-extrusion method with an aqueous amine oxide, in particular N-Methylmorpholin-N-oxid, as a solvent, by:

   a) dispersing cellulose, or a mixture of celluloses, with a Cuoxam-DP in the range of 250 to 3000 in aqueous amine oxide to form a dispersion;

   b) converting the dispersion at an increased temperature under dehydration and shearing into a solution with a zero shear viscosity in the range of 600 to 6000 Pa·s and with a relaxation time in the range of 0.3 to 50 s, at 85° C. respectively;

   c) supplying the solution to at least one spinning nozzle and in advance guiding the solution through an impaction chamber connected to said nozzle(s), where the dwelling time of the solution is at least equal to its relaxation time at the spinning temperature;

   d) forming the solution in each nozzle to at least one capillary assemblage and guiding the capillary assemblage(s), under draught through a non-precipitating medium and then through a downstream spinning bath with a precipitating medium for precipitation of cellulose threads;

   e) separating precipitated cellulose threads from a flow of the precipitating medium by deflection at the end of the spinning bath drawing frame and drawing the threads off,

   characterised in that
   in step d) the capillary assemblage(s) is (are) impacted with a gas under an angle α to the direction of the capillary run in a range of 45°<α<90° shortly before the capillary assemblage(s) enters the downstream spinning bath.
2. A method for the production of cellulose fibers or filaments from cellulose according to the dry-wet-extrusion method with an aqueous amine oxide, in particular N-Methylmorpholin-N-oxid, as a solvent, by:

   a) dispersing cellulose, or a mixture of celluloses, with a Cuoxam-DP in the range of 250 to 3000 in aqueous amine oxide to form a dispersion;

   b) converting the dispersion at an increased temperature under dehydration and shearing into a homogeneous solution with a zero shear viscosity in the range of 600 to 6000 Pa·s and with a relaxation time in the range of 0.3 to 50 s, at 85° C. respectively;

   c) supplying the solution to at least one spinning nozzle and in advance guiding the solution through an impaction chamber connected to said nozzle(s), where the dwelling time of the solution is at least equal to its relaxation time at the spinning temperature;

   d) forming the solution in each nozzle to at least one capillary assemblage and guiding the capillary assemblage(s), under draught through a non-precipitating medium and then through a downstream spinning bath with a precipitating medium for precipitation of cellulose threads;

   e) separating precipitated cellulose threads from a flow of the precipitating medium by deflection at the end of the spinning bath drawing frame and drawing the threads off,

   characterised in that
   in step d) the capillary assemblage(s) is (are) impacted with a gas shortly before the capillary assemblage(s) enters the downstream spinning bath, whereby the gas flow and the spinning bath have parallel flow components at the gas gap boundary.
3. The method according to claim 1 or 2, characterised in that the capillary assemblage(s) is (are) impacted by a flat, level gas flow that reaches across the entire width of the capillary assemblage(s).
4. A device for the production of cellulose fibers or filaments from cellulose according to the dry-wet-extrusion method with aqueous amine oxides as solvents, with
   a spinning package with a spinning plate, spinning nozzles and arranged above the spinning plate and the spinning nozzles a shared impaction chamber, wherein the impaction chamber has a volume according to the following equation V ≥ vL ·λm wherein V represents the volume of the impaction chamber in cm³, v_L the volume flow of the cellulose solution in cm³/s and λ_m the relaxation time at the frequency maximum of the relaxation spectrum of the spinning solution,
   a spinning bath in two vessels linked via a spinning bath pump;
   a gap positioned between the spinning nozzle(s) (6) and the surface of the spinning bath (7) of the upper of the two vessels and
   (d) a drawing-off godet, characterised in that
   at least one wide-slot nozzle is arranged in the gap to impact the capillary assemblage(s) with a gas flow directed under an angle λ in relation to the capillary assemblage running direction in the range 45°<λ<90° before the at least one capillary assemblage enters the spinning bath and wherein the gas gap has a width according to the equation

   

   wherein a represents the width of the gap in mm, λ_m represents the relaxation time at the frequency maximum of the relaxation spectrum of a spinning solution, ν_a represents the drawing-off speed in m/min, N represents the capillary density in cm^-2 and D represents the diameter of a nozzle hole in mm.
5. The device according to claim 4, characterised in that the upper bath container (1) features on one side of the capillary assemblages (26) at least one inlet opening (19) and on the other side of the capillary assemblages (26) at least one overflow (9) and that the wide-slot nozzle is arranged on the same side as the inlet opening(s) (19) with respect to the flow of capillary assemblages (26).
6. The device according to claim 4 or 5, characterised in that the wide-slot nozzle is mechanically connected to the at least one overflow (9).
7. The device according to one of the claims 4 to 6, characterised in that the dimensions of the spinning nozzle(s) (6), the width of the gap a, and the spinning bath drawing frame length w meet the equation x ≥ ((a+w)/w)·3,5·D wherein x represents the distance between two adjacent nozzle holes, a represents the width of the air gap, w represents the length of the spinning bath drawing frame and D represents the diameter of the nozzle hole.

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