Title of Invention

A PROCESS AND A DEVICE FOR PRODUCING CELLULOSE FIBERS OR FILAMENTS FROM CELLULOSE

Abstract 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, wherein 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. FIGURE 1.
Full Text

The present invention relates to a process and a device 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. Accordingly the present invention provides a process for producing cellulose fibers or cellulose filament yam from cellulose by the dry-wet extrusion process with aqueous amine oxides, in particular N-methylmorpholine N-oxide, as the solvent, wherein a) cellulose or a cellulose mixture with a cuprammonium DP between 250 and 3000 is dispersed in an aqueous amine oxide, b) the resulting dispersion is converted to a homogeneous
solution with a zero shear viscosity in the range of 600 to 6000 Pa . s at an elevated
temperature of 85°C with removal of water, c) the solution is sent to at least one spinneret, d) the solution in each spinneret is shaped to form at least one capillary, and the capillary (capillaries) of each nozzle is (are) passed through a precipitation bath zone, with shaping through a medium that does not precipitate out and then with precipitation of the cellulose fibers, and e) the cellulose fibers are separated from the precipitation bath by deflection at the end of the precipitation bath zone and the fibers are drawn off. This invention also relates to a device for producing cellulose fibers or cellulose filament yams from cellulose by the dry-wet extrusion process using aqueous amine oxides as the solvent, with a spinning package having a spinneret plate and spinnerets, a precipitation bath having two containers connected by a precipitation bath pump, a gap between the spinnerets and the surface of the precipitation bath in the upper of the two containers, and at least one draw-off roller.
U.S. Patents 4,246,221 and 4,416,698 describes a process for dissolving cellulose in aqueous tertiary amine oxides, shaping these solutions into spinning capillaries with minimal shearing, drawing the solution jets in a large air gap at a low rate of extension, precipitating the cellulose through a spinning bath containing aqueous amine oxide and

drawing off the cellulose fibers over a roller. Reference is made to the problem of sticking in the air gap, and moistening of the surface of the fibers over a roller is proposed.
To prevent sticking of the fibers in the air gap, German Democratic Republic Patent 218 121 A proposes that polyalkylene ethers should be added to the spinning
solution.
U.S. Patent 5,417,909 describes shaping of the solution into spinning capillaries with moderate to high shearing, shaping the solution streams in a short air gap at a moderate to high elongation rate, precipitating the cellulose, combining and conveying the fibers or the group of fibers through a spinning funnel in a direct current. The relatively short air gap counteracts sticking and permits spinning with capillary densities of up to 3 K/mm .
International Patent WO 96/20300 describes the
relationships deriving from the distance between two
spinning capillaries and the path between the spinneret and
the bundling element on the one hand and the air gap on the
other hand, and it claims a device for drawing off
cellulose fibers at an angle of Patent Application 0 832 995 A describes a device having a
pivotable bundling element, which guarantees that the angle
.f between the outermost filaments and the center
perpendicular to the nozzle does not exceed 20^ at a small
air gap.
To increase capillary density, European Patent Applications 0584318 and 0671492 describe blowing gas onto the fibers in the air gap and a device for supplying the cooling gases, European Patent 795052 describes the use of air having a defined water content for cooling. International Patent WO 94/28218 describes a method and device for blowing air in

the air gap, and finally. International Patent WO 96/21758 describes blowing in two zones.
All the methods and devices pursue the goal of achieving a very good spinning reliability in spinning fibers with a sufficient air gap and the largest possible spinneret. In spinning cellulose filament yarns, the requirements with regard to capillary density are lower, but the limit to the size of the nozzle, which is determined by the fineness, leads to much higher requirements regarding the draw-off rate.
All these methods emphasize a non-contacting guidance of the filaments through an air gap, cooling and/or superficial precipitation of the cellulose in the air gap by blowing wet gases and the length of the air gap. The distance the filament must travel in the spinning bath and the resulting frictional force remain largely disregarded. Thus, for example, pivoting the bundling element in European Patent Application 0 832 995 leads to a definite increase in the size of the spinning bath distance while reducing the angle between filaments. Partial precipitation of cellulose in the air gap by blowing wet air onto it makes the orientation process significantly more difficult. This circumstance is taken into account only by U.S. Patent 5,417,909, where the filaments are guided by a spinning funnel through a bath flowing in the same direction. However, the frictional force between the filament and the spinning bath increases significantly with the distance and the filament speed and leads to a decline in the mechanical fiber values. When spinning fibers and filaments, an attempt is made to compensate for this circumstance by having low draw-off rates. When spinning filament yarn according to U.S. Patent 5,868,985, a precipitation bath length of 0.5 - 8 cm is proposed, flowing in the direction of travel of the filament, to make it possible to work with high draw-off speeds. This arrangement operates with an air

gap of 18 cm, and is suitable only for simple spinning with a very low capillary density, only monofilament according to the examples.
The object of the present invention is to create a method and a device of the type defined in the preamble, by means of which it is possible to spin monofilament and multifilament yarns with good mechanical fiber properties. In particular the uniformity of the volume flows through each nozzle should be increased in comparison with the known processes. Furthermore, the goals mentioned above should be achieved without blowing cooling air or the like onto the extruded capillaries in the air gap. Other advantages are derived from the following description.
This object is achieved with the process according to this invention as defined in the preamble by the fact 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 shared by the nozzle(s), the dwell time of the solution in this chamber being at least equal to its relaxation time at the spinning temperature. The preferred relaxation time at 85 'C is in the range of 1 to 5 sec.
Spinning solutions of cellulose in an aqueous amine oxide have highly pronounced viscoelastic properties. As a result, a considerable portion of the energy required for conveyance and shaping of the spinning solution in the spinning channel is stored elastically and leads to reshaping after removal of the external constraint during the relaxation time. Since the dwell time in the inflow chamber exceeds the relaxation time λm, complete relaxation occurs and thus the zero shear viscosity prevails above each nozzle, and the applied pressure leads to an equal volume flow through each nozzle.

Determination of relaxation time from rheological data on a cellulose solution is described in detail in the literature (Ch. Michels, Das Papier [Paper] (1998) 1, p. 3-8). In practice, these solutions have relaxation time spectra, because cellulose has a molecular weight distribution. Figure 1 shows the relaxation time spectra, i.e., the relative frequency H* of the relaxation time λ of four solutions of different celluloses. The relaxation time λm is the relaxation time λ prevailing at the relative maximum frequency.
In one embodiment of the process according to this invention, the cellulose or the cellulose mixture is subjected to an enzymatic pretreatment, which in certain celluloses causes a decline in the heterogeneity of the molecular weight distribution. With a spruce sulfite cellulose, for example, the bimodal distribution is converted to a monomodal distribution.
In another embodiment of the process according to this invention, to prepare the cellulose mixture, first a cellulose with a cuprammonium DP in the range of 600 to 3000 can be dispersed in water, then a cellulose with a cuprammonium DP in the range of 250 to 600 is added and also dispersed, and then the cellulose mixture wet from the press is used in step a) after separating the water. The maximum relaxation time can be increased by adding the high-molecular cellulose component, thus making it possible to increase the gap width, as explained in greater detail below.
The extruded capillaries are expediently passed individually and largely in parallel through the non-precipitating medium and then through a precipitation bath zone less than 20 cm long. The spinnerets and the filament guide elements to be explained in greater detail below are arranged so that the filaments are guided essentially in

parallel through the short precipitation bath zone without mutual contact and so that friction between the filaments and the precipitation bath is reduced significantly. Preferably, the precipitation bath zone is less than 5 cm. The amount of precipitation bath, which is in circulation for precipitation and conveyance of the filaments, is low at 1.5 to 7 liters per nozzle.
The cellulose filaments in step e) are preferably deflected out of the precipitation bath streams by an angle P > 10°, and the filaments are drawn off at a maximum fiber tension of 5 cN/tex. The filaments are separated by deflection by the angle P from the precipitation bath streams falling in laminar flow and are collected by the draw-off roller at this fiber tension and adjusted to the desired draw-off speed Va- The fibers drawn off can be washed individually as filament yarn, activated and dried or combined over thread guides to form a fiber cable and washed and cut and then washed, finished with an aftertreatment and dried as a thread.
This object is also achieved according to this invention with the device defined in the preamble by the fact that a common inflow chamber is arranged above the spinneret plate with the spinnerets arranged in one or more rows or groups, the volume of this chamber conforming to the equation:
V > VL*Xn, (I)
where V is the volume of the inflow chamber in cm3, VL denotes the volume flow of the cellulose solution in cm2/sec and λm denotes the relaxation time of the spinning solution at the maximum frequency of the relaxation time spectrum in sec. The relaxation time λm is a variable that is specific for the solution; determination of this variable is described in the aforementioned article by Ch. Michels, in particular in the section "Experimental

procedure" on pages 3 and 4. The description there is explicitly included in the disclosure content of the present patent application. These dimensions of the chamber volume yield an optimum uniformity of the volume flow of the spinning solution which is sent to two or more of these spinnerets through a spinning pump.
According to another aspect of the present invention, the device mentioned in the preamble is characterized according to this invention by the fact that the width of the air gap and the relaxation time of the spinning solution can be described by the following equation:
a>[5+16.λm0.6].e0.002 (II)
where a denotes the width of the gap in mm, λm is the relaxation time of the spinning solution at the maximum frequency of the relaxation time spectrum in sec, and Va is the draw-off speed in m/min. As shown by this equation, there is a correlation between the relaxation time λm and the width of the air gap such that the width of the air gap can be increased with an increase in the relaxation time λm without having to reduce the capillary density of the nozzle or the draw-off speed or having a negative effect on spinning reliability. Therefore, the air gap can be increased with an increase in the relaxation time 8^ at a
given capillary diameter, i.e., the width of the air gap

which is necessary for a high fiber quality with good spinning reliability (low rate of extension, no sticking of the capillaries) can be adjusted through the relaxation time of the solution.
The dimensions of the spinnerets, the gap width and the precipitation bath zone preferably comply with the following equation:


re X denotes the distance between two adjacent nozzle holes, a is the air gap width, w is the length of the precipitation bath zone and D is the nozzle hole diameter. Reference is made to Figure 6 to further explain the individual quantities.
In the preferred embodiment of the device according to this invention, fiber guide elements, preferably made of ceramic, are inserted into the bottom of the upper bath container. These fiber guide elements are passages through the bottom of the container, through which the precipitated groups of fibers leave the upper precipitation bath container together with precipitation bath streams. The fiber guide elements lead to an outflow of the precipitation bath in laminar substreams which are automatically clustered with and accelerated by the individual fiber bundles. The spinnerets and fiber guide elements expediently have the same arrangement. The fibers can pass through the precipitation bath zone without mutual contact and can be picked up almost in parallel from the draw-off roller. The fiber guide elements are preferably arranged in rows or groups. Spinning hats, e.g., with a diameter of 12.5 or 20 mm are arranged in the nozzle plate in one row (preferably filaments) or several rows (preferably fibers) so that the projection of the fibers leads to a line and the fibers can be picked up from the draw-off roller almost in parallel. In fiber spinning, preferably 360 or 1020 or more capillaries are arranged per hat on a nozzle area of 90 or 250 mm^, for example. The capillary density is thus approx. 4/mm^.
The spinnerets preferably have a hat shape and the nozzle area occupied by the spinning capillaries is equal to or less than the inlet area of the fiber guide elements. In

this way, the fibers are conveyed through the precipitation bath essentially in parallel to one another without any mutual contact.
The fiber guide elements preferably have a ratio of the diameters of the inlet area and outlet area E/e > 1 and their edges are preferably rounded at the outlet. These fiber guide elements are preferably used for fiber production. They generally extend at least over the total thickness of the bottom of the container. They have a height h of 2 to 20 mm.
In another embodiment, the fiber guide elements have a ratio of height to inside diameter of the outlet area h/e The upper bath container preferably has an inlet opening with an upstream settling chamber. The settling chamber may include, for example, a flow zone filled with packing bodies and a subsequent empty flow zone without any packing bodies. In the settling chamber, the precipitation bath which is pumped in circulation is slowed down to the extent that it enters the precipitation bath container essentially in laminar flow.
The upper precipitation bath container preferably has at least one overflow, the height of which is adjustable. The

precipitation bath zone can be altered by displacement of the overflow(s) in the vertical direction, which results in additional advantages, in particular in spinning.
Furthermore, the position of the upper precipitation bath container is adjustable vertically with respect to the spinning package. The width of the air gap can be altered in this way and also by displacement of the overflow in the vertical direction,
Furthermore, the draw-off roller arranged beneath the upper precipitation bath container may be adjusted vertically and/or horizontally. In particular, this makes it possible to alter the angle P of deflection of the fibers out of the precipitating bath streams.
The method and a device according to this invention will now be explained on the basis of the drawing and the examples. They show:
Figure 1: a graphic diagram of the relaxation time spectrum for four different cellulose solutions;
Figure 2: a schematic diagram of a device for implementing the process according to this invention;
Figure 3: a schematic top view of the device illustrated in Figure 2;
Figure 4: an axial section through an embodiment of the fiber guide element, preferably for spinning fibers;
Figure 5: an axial section through another embodiment of the fiber guide element, preferably for spinning filaments;
and
Figure 6: a geometric diagram of the spinning process to

illustrate the individual geometric quantities of equation [II).
Figure 1 shows the relative frequency H* over the relaxation time λm of four cellulose solutions in aqueous N-methyl-morpholine N-oxide from different celluloses, details of which are shown in the table included in Figure 1, where λm denotes the relaxation time at the maximum frequency in sec, DP is the degree of polymerization (cuprammonium) , Η0 is the zero shear viscosity of the solution in Pa • s and c is the cellulose concentration of the solution in %. The relaxation time λm which correlates with the width of the air gap is the relaxation time at the relative maximum frequency according to equations (I) and (II). The solution p9915102 contains a cellulose mixture in which the relaxation time of a spruce sulfite pulp (cuprammonium DP 470; Xm = 1.6 sec) has been increased to Xm = 2.1 sec by adding a high-molecular cellulose component.
Figure 2 shows the spinning device with an upper precipitation bath container 1, a lower precipitation bath container 2 and a spinning package 3. The spinning package 3 includes a supporting plate with filter 4, an inflow chamber 5 and several spinnerets 6 which are a distance away from the surface 7 of the precipitation bath such that it forms the air gap. The bottom 10 of the upper precipitation bath container 1 is designed to be reinforced and is equipped with several fiber guide elements 11 in accordance with the arrangement of the nozzles 6, the fiber bundles 12 leaving the container 1 through these fiber guide elements together with precipitation bath streams.
Beneath the container 1 there is a draw-off roller 13 which can be displaced vertically and horizontally; it deflects the fiber bundles of all fiber guide elements 11 from the precipitation bath streams 14 at an angle β and winds them

up at a suitable tensile stress. The precipitation bath streams 14 go into the lower container 2 and are pumped back through line 16 into the upper precipitation bath container 1 by means of pump 15. It can be seen here that the precipitation bath zone w through which the fiber bundles 12 pass extends up to the position beneath the fiber guide elements 11, where the fiber bundles 12 are separated from the precipitation bath streams 14. Line 16 opens first into a settling chamber 18 which is partially filled with packing bodies and out of which the precipitation bath fluid flows through opening 19 into container 1.
The top view in Figure 3 shows that the fiber guide elements are arranged with an offset in the bottom 10 and the fiber bundles 12 run side by side on the draw-off roller 13.
Figure 4 shows the fiber guide element 11, which is made of ceramic, for a fiber bundle. As this shows, the inside cross section of the element becomes narrower in the direction of flow. This is also true of the fiber element according to Figure 5, which is provided for gripping a filament yarn. The preferred rounding of the edges of the fiber guide elements 11 are not shown in these figures. The fiber bundles are separated from the precipitation bath stream immediately after passing the fiber guide elements.
Figure 6 shows schematically the geometric quantities contained in equation (III), where reference number 6' denotes two nozzle holes having hole diameter D; d denotes the center-to-center spacing of the capillaries on the outlet side of the nozzle hole 6' ; x is the distance between the two capillaries, and d' is the center-to-center spacing of the capillaries on entrance into the spinning bath; P is the point at which the fiber bundles separates from the precipitation bath stream; β is the deflection

angle at which this separation occurs; β* is the (very small) angle between two adjacent fibers in the precipitation bath.
Example 1
In a stirred container, 0.49 kg of an enzymatically pretreated spruce sulfite cellulose (cuprammonium DP 580, dry solids content 44.9 %) is suspended in 2.6 kg NMMO (dry solids content 65.0 %) containing 0.44 g stabilizer, and 0.93 kg water is distilled off at 90oC and 500 to 25 mbar with shearing. The resulting cellulose solution having the composition 10 % cellulose, 78.5 % NMMO and 11.5 % water does not contain any microscopically visible particles, and according to particle analysis by laser diffraction (cf. B. Kosan, Ch. Michels: Chemical Fibers International, 49 (1999) pp. 50-54) it has a content of 19 ppm with a particle diameter of
m/min and then washed at a thread tension of The filament yarns are characterized by the following
parameters:
fineness 40 dtex (30)
tensile strength 43,7 cN/tex
variation coefficient 2.3 %
tensile elongation 8.5%
knot tensile strength 34.1 cN/tex
Uster value (inert) 0.1 %
Example 2
0.18 kg of a cotton linters cellulose (cuprammonium DP 1907) is beaten in a 1:20 ratio with water in a jet mixer with shearing. To the homogeneous suspension is added 4.20 kg of a spruce sulfite cellulose (cuprammonium DP 4 50) slowly with shearing. The cellulose mixture is separated through a suction press.
The cellulose mixture is placed in a stirred container, and 30.42 kg NMMO (dry solids content 84 %) whose alkalinity had been adjusted to a pH of 11.2 by adding NaOH is added. While regulating the temperature, vacuum and shearing, 7.69 kg water are distilled off, whereby the suspension is converted to a clear solution having 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. Through a spinning pump (4.8 mL/r, 32.7 rpm) 157 mL/min spinning solution enters the inflow space of a filament yarn spinning station having four nozzles with a diameter of 20 mm arranged in a row, each with 90 spinning capillaries of 120 μm (L/D -- 1) . The dwell time in the inflow space of 13.0 x 4.0 x 0.35 cm was 2.3 Xm- The spinning solution was shaped to form a group of fibers with shearing of 42,900 1/sec in the spinning nozzles, then

drawn in a ratio of 11.7 in an air gap 28 mm long at an extension rate of 245 1/sec; then the cellulose was precipitated in a vertical precipitation bath 4.0 cm long, the fibers were conveyed through two fiber guide elements according to Figure 5 (e = 7 mm, h = 4 mm) in the bottom (E = 18 mm) of the upper spinning bath box, deflected out of the precipitation bath streams at an angle of 50°, sent in parallel to a draw-off roller at a thread tension of -3 cN/tex, drawn off at a speed of 4 50 m/min and then washed at a thread tension of The filament yarns are characterized by the following
parameters:
fineness 150 dtex f (90)
tensile strength 41,7 cN/tex
variation coefficient 3.2 %
tensile elongation 9.1 %
knot tensile strength 28.9 %
Uster value (inert) 0.1 %
Example 3
7.66 kg/h enzymatically activated and stabilized spruce sulfite cellulose (cuprammonium DP 480, dry solids content 50.0 %) and 29.0 kg/h N-methylmorpholine N-oxide (NMMO, dry solids content 84.0 %) are fed continuously to a heated Conti 25 CO-rotating processor (List AG, Arisdorf) and dispersed to form a homogeneous slurry. This then goes through a slurry metering pump into the heated dissolver of the Conti Diskotherm B 63 type (List AG, Arisdorf), where 27.0 L/h homogeneous cellulose solution of the composition 12.0 % cellulose, 76.3 % NMMO and 11.7 % water is formed at mass temperatures of 90 °C and a vacuum of 20 mbar while removing 4.7 kg/h water. The solution has a zero shear viscosity of 3100 Pas and a relaxation time of 1.9 sec at 85 °C.

4 51 mL/min spinning solution with a mass temperature of 85 oC passes through the nozzle filter via a spinning pump (9-6 mL/r, 47 rpm), entering thirteen spinning hats arranged in three rows through an inflow space of 9.2 x 6.2 X 0.8 = 45.6 cm^ (dwell time t = 3 X^) / each with 350 spinning capillaries with a diameter of 100 jam. At a shearing rate of 16,850 1/sec, the solution is shaped in the 4550 nozzle channels and drawn in a ratio of 9.5 in an air gap of 20 mm at an elongation rate of 90 1/sec; the cellulose is precipitated in a spinning bath with a bath length of 6 cm; the fibers are separated from the laminar precipitation bath streams at an angle of 35o and sent for aftertreatment and drying at a draw-off speed of 120 m/min by means of the draw-off roller.
By analogy with the hat arrangement in the nozzle plate, thirteen fiber guide elements made of ceramic according to Figure 4 with E = 13 mm; e = 9 mm and h = 20 mm were used in the bottom of the spinning bath box-
The resulting staple fibers had the following mechanical
properties:
fineness dtex 1.3
tensile strength, dry cN/tex 43- 5
tensile strength, wet cN/tex 36.5
tensile elongation, dry % 14.5
tensile elongation, wet % 15.1
loop tensile strength cN/tex 15.6
cut length mm 38
Example 4
0.23 kg of a high molecular spruce sulfite cellulose (cuprammonium DP 1100) is beaten in a 1:16 ratio with water in a turbo mixer. Small portions of 4.45 kg of a spruce sulfite cellulose with a cuprammonium DP of 480 are added

to the homogeneous suspension and beating is continued. The homogeneous cellulose mixture is separated from the water through a traveling screen system, yielding 9,36 kg cellulose with a dry solids content of 50 %. This cellulose mixture is dosed uniformly over a period of one hour with 35.9 kg NMMO (dry solids content 84 %) which also contains 10 g of a stabilizer in a heated Conti 25 co-rotating processor (List AG, Arisdorf) and is dispersed to form a homogeneous slurry, while also removing 2-26 kg water. Slurry is added to the heated kneader at the rate of 43.0 kg/h through a slurry metering system; the kneader is a Conti B 63 Dickotherm model (List AG, Arisdorf), forming 39 kg/h of a homogeneous cellulose solution at a stock temperature of 93 '^C and 22 mbar vacuum with removal of 4,0 kg/h water; the cellulose solution has the following 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 sec. Cellulose precipitated from the solution had a cuprammonium DP of 506,
Spinning solution at a mass temperature of 85 °C passes through the nozzle filter at the rate of 547 mL/min via a spinning pump (9.6 mL/r, 57 rpm), then it goes to five spinning hats arranged in two rows through an inflow space of 9.2 X 6.2 X 0,8 = 45.6 cm^ (dwell time t = 2.4 K) , each spinning hat having 1020 spinning capillaries with a diameter of 80 jam. At a shearing rate of 13,77 0 1/sec, the solution is shaped in the 5100 nozzle channels and drawn in a ratio of 8.8 in an air gap of 22 mm at an elongation rate of 67 1/sec. The cellulose is then precipitated in a spinning bath with a bath length of 5 cm; the fibers are separated from the laminar precipitation bath streams at an angle of 30°, drawn off at a draw-off rate of 100 m/min, combined to form a thread cable, washed, cut into staple fibers, aftertreated and dried. In the upper spinning bath box there were five fiber guide elements according to Figure 5, arranged in two rows with h = 20 mm, E = 20 mm

and e == 10 mm.
Conveyance of the cooled precipitation bath (6-8 oC) between the lower and upper spinning bath containers was accomplished through a membrane pump at approx. 35 L/min.
The staple fibers had the following mechanical fiber
parameters:
fineness dtex 1.7
tensile strength, dry cN/tex 42.8
tensile strength, wet cN/tex 35.9
tensile elongation, dry % 15.5
tensile elongation, wet % 15.9
loop tensile strength cN/tex 15.1
cut length mm 38


WE CLAIM
I. 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, wherein
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 as claimed in claim 1, wherein the cellulose or the cellulose mixture is subjected to an enzymatic pretreatment.

3. The process as claimed in claim 1 or 2, wherein 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 as claimed in any one of claims 1 to 3, wherein 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 as claimed in any one of claims 1 to 4, wherein the cellulose fibers in step e) are deflected out of the precipitation bath streams by an angle β > 10o 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

-1
where V is the volume of the inflow chamber in cm , VL denotes the volume flow of the cellulose solution in cm2/sec and λm denotes the relaxation time of the spinning solution at the maximum frequency of the relaxation time spectrum.
7, 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 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, λm is the relaxation time of the spinning solution at the maximum frequency of the relaxation time spectrum and Vg is the draw-off rate in m/min.
8. The device as claimed in claims 6 or 7, wherein the dimensions of the
spinnerets (6), the gap width (a) and the precipitation bath zone (w) are defined by the
equation


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 as claimed in any one of claims 6 to 8, wherein fiber guide elements
(11), preferably made of ceramic, are inserted into the bottom (10) of the upper bath
container (1).
10. The device as claimed in claim 9, wherein the fiber guide elements (11) are
arranged in rows or groups.
11. The device as claimed in claim 9 or 10, wherein 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 as claimed in any one of claims 9 to 11, wherein the fiber guide
elements (11) have a ratio of the diameter of the inlet area and outlet area E/e ^ 1 and
their edge is rounded at the outlet.
13. The device as claimed in any one of claims 9 to 11, wherein the ratio of the height the fiber guide elements (11) to the inside diameter of the outlet area is h/e 14. The device as claimed in any one of claims 6 to 13, wherein the upper bath container (1) has an inlet opening (19) downstream from a settling chamber (18).
15. The device as claimed in any one of claims 6 to 14, wherein the upper bath container (1) has at least one overflow (9) the height of which is adjustable.

16. The device as claimed in any one of claims 6 to 15, wherein the position of the
upper precipitation bath container (1) is adjustable vertically with respect to the
spinning package (3).
17. The device as claimed in any one of claims 6 to 16, wherein the draw-off roller
(13) arranged beneath the upper precipitation bath container (1) is adjustable vertically
and horizontally.


Documents:

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in-pct-2002-684-che- abstract.pdf

in-pct-2002-684-che- claims duplicate.pdf

in-pct-2002-684-che- claims original.pdf

in-pct-2002-684-che- correspondence others.pdf

in-pct-2002-684-che- correspondence po.pdf

in-pct-2002-684-che- descripition complete duplicate.pdf

in-pct-2002-684-che- descripition complete original.pdf

in-pct-2002-684-che- drawings.pdf

in-pct-2002-684-che- form 1.pdf

in-pct-2002-684-che- form 19.pdf

in-pct-2002-684-che- form 26.pdf

in-pct-2002-684-che- form 3.pdf

in-pct-2002-684-che- form 5.pdf

in-pct-2002-684-che- pct.pdf


Patent Number 205615
Indian Patent Application Number IN/PCT/2002/684/CHE
PG Journal Number 26/2007
Publication Date 29-Jun-2007
Grant Date 05-Apr-2007
Date of Filing 08-May-2002
Name of Patentee M/S. THÜERINGISCHES INSTITUT FÜR TEXTIL- UND KUNSTSTOFF-FORSCHUNG E.V.
Applicant Address Breitscheidstrasse 97 07407 Rudolstadt
Inventors:
# Inventor's Name Inventor's Address
1 MICHELS, Christoph Gabelsbergerstrasse 7 07407 Rudolstadt
2 KOSAN, Birgit Gustav Lilienthalstrasse 9 07407 Rudolstadt
PCT International Classification Number D01F 2/00
PCT International Application Number PCT/DE2000/003817
PCT International Filing date 2000-10-28
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 199 54 152.3 1999-11-10 Germany