Classifications

• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
  • D01F2/00—Monocomponent artificial filaments or the like of cellulose or cellulose derivatives; Manufacture thereof
• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
  • D01D1/00—Treatment of filament-forming or like material
  • D01D1/06—Feeding liquid to the spinning head
  • D01D1/09—Control of pressure, temperature or feeding rate
• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
  • D01D4/00—Spinnerette packs; Cleaning thereof
  • D01D4/06—Distributing spinning solution or melt to spinning nozzles

Definitions

• the invention relates to a process for the production of cellulose fibers or cellulose filament yarns from cellulose by the dry-wet extrusion process with aqueous
• Amine oxides as solvents in which a) a dispersion of cellulose and aqueous amine oxide is transferred at elevated temperature with dehydration and shear into a homogeneous solution with a relaxation time in the range 0.3 - 90 s at 85 ° C, b) the solution via a spinning solution supply to a spinning package with at least one spinneret, c) the solution in the spinning package passes through a filter, a support plate, an inflow chamber and at least one spinning capillary at least one spinning nozzle, d) the solution jets deformed to capillaries with further delay through a non-falling medium , shortly before entering the precipitation bath, blowing approximately perpendicularly to the filament running direction with a gas stream, the cellulose precipitates in the precipitation bath, and e) the cellulose threads at the end of the precipitation bath section are deflected from the precipitation bath and the threads are drawn off.
• the invention also relates to a device for producing cellulose fibers or filament yarns from cellulose by the dry-wet extrusion process with aqueous amine oxides as a solvent, consisting of a solution supply and a spinning package with a screen filter pack, support plate, inflow chamber and spinneret (s), which after the inventive method works.
• EP 0 430 926, EP 0 494 852, EP 0 756 025 and WO 94/28 210 describe spin packs with round and rectangular nozzles with different spinning capillary geometry and arrangement.
• EP 0 662 166 a spinneret insert made of noble metal is arranged in a rotationally symmetrical manner and the thread family formed is cooled by an air stream supplied rotationally symmetrically via a baffle plate immediately after leaving the spinning capillaries. With this arrangement, an undefined cooling of the spinneret insert made of precious metal is inevitably to be expected.
• EP 0 584 318, EP 0 671 492, EP 0 795 052, WO 94/28 218 and WO 96/21 758 describe the most varied forms of treating the thread group in the gap between the spinneret and the precipitation bath with air having different water contents.
• All spin packs are heated electrically or through a double jacket filled with heating fluid.
• the nozzles or nozzle inserts arranged in stainless steel spinning plates are tempered by heat conduction via the spinning plate and this receives its heat via the spinning package. With this usual type of heating, one has to reckon with a more or less large temperature distribution over the spinning plate or the spinnerets.
• WO 99/47733 and DE 100 19 660 now describe devices which are to vary the temperature of the cellulose solution over the capillary cross section with the aid of a gaseous heating fluid.
• individual thin-walled spinning capillaries made of stainless steel are from an annular gap surrounded by hot air at a temperature above that of the spinning solution, for example of 150 ° C. and more, around the spinning capillaries and thereby producing a flow profile which should lead to fibers with a long loop tear length and low fibrillation.
• a disadvantage of this arrangement is the comparatively high space requirement for the individual spinning capillary and the relatively complex construction.
• fibers with high loop tensile strength and low fibrillation are to be obtained by controlling the average heat flow and / or the average acceleration over the air gap width at a certain level.
• the object of the present invention is to provide a method and a device which, through improved temperature control and consistency, allow the spinning of cellulose Solutions to fibers with improved properties, in particular with regard to uniformity, wet tensile strength and fibrillation behavior, are permitted.
• the assessment of the uniformity of the fiber properties is advantageously carried out via the coefficient of variation of the fineness or tear strength and the fibrillation behavior by measuring the wet scrub resistance.
• the method for determining wet scrub resistance has been described in the literature [Mieck KP; Langner H.; Nechwatal A. "Melliand textile reports” 74 (1993) p. 945; “Lenzinger reports” 74 (1994) pp. 61-68; and Mieck KP; Nicolai A; Nechwatal A.; “Lenzinger reports” 76 (1997) p. 103] described in detail.
• the measure of wet scrub resistance is the required number of revolutions of a roller of a particular geometry covered with a cellulose fabric, which leads to the breakage of a moistened fiber under defined tension.
• the lyocell fibers usually reach A level of 5-35 scrubbing cycles.
• the focus of the present invention is not primarily on maintaining a certain temperature, but rather on minimizing the deviations from a desired value both over the cross section of the solution supply and between and within the nozzles or the spinning capillaries
• the expansion viscosity is of primary importance for the structure formation in the gap, and this corresponds to at least 3 times the value of the zero shear viscosity, the high demands on the temperature control during spinning are underlined.
• the significant change in viscosity with temperature is additionally superimposed by the dependence on the shear rate when flowing or on the rate of expansion when deforming in the gap.
• Cellulose solutions have an extremely viscoelastic behavior and the relaxation times after shear are significantly higher than those of other polymers. For this reason, when transporting and deforming the cellulose solutions, both temperature and shear and stretching speed as well as the relaxation time must be taken into account.
• the relaxation times of the cellulose solutions can be calculated from the oscillographically recorded deformation curves of the dependence of the storage and loss modulus on the shear (the determination is described in detail by Ch. Michels, Das Toilet, 1998/1 page 3 - 8).
• the chemical nature of the cellulose solution requires stainless steel or precious metals for the manufacture of the devices. Precious metals are only used in the exceptional case of the "cone nozzles". However, because of their comparatively low thermal conductivity, stainless steels can lead to considerable problems when heating / tempering the cellulose solution during transport and when deforming in the spin pack.
• the solution in stage b) is the Solution supply (3) designed as a heat exchanger, optionally temperable, flows through, in stage c) first a support plate (1) designed as a heat exchanger with flow channels (1.1) at a shear rate of - ⁇ 30 [5 _1 J, then passes through the support plate (1) and intermediate ring (5) formed flow chamber (5.1) with a residence time of t v ⁇ passes through and then in at least one spinning capillary at least one cap spinneret (6), which is provided with a separate nozzle temperature control (2), including insulation (2.1), the temperature of which is preferably below that of the cellulose solution inside the cap nozzle, to the filament or filament bundle deformed and weakly blown in step d) shortly before entering the precipitation bath with a flat gas flow of 2 - 20 1 / min and cone nozzle (6) at an almost right angle.
• a support plate (1) designed as a heat exchanger with flow channels (1.1) at a shear rate of - ⁇ 30 [5 _1 J,
• the transport of the solution through the solution supply (3) and support plate (1), which is designed as a heat exchanger, in connection with the inflow chamber (5.1) ensures that all spinning capillaries of the cone nozzle (s) are flowed through by a completely relieved solution of the same temperature and via the Nozzle temperature control (2) with insulation (2.1) can be used to control heat radiation through the precious metal nozzle surface. It was found that the temperature equalization via the support plate (1) and solution supply (3) designed as a heat exchanger in combination with the complete relaxation of the solution in the inflow chamber (5.1) leads to a significant improvement in the uniformity of the fiber properties. This is reflected in the significantly lower variation coefficients of the fiber properties, for example the tear strength from 15 - 25 to 3 - 10%.
• the thread tension in the gap between the spinning capillary outlet and the precipitation bath inlet is within wide limits via the nozzle temperature control (2) can be varied, in particular if the temperature of the nozzle temperature control (2) is less than or at most equal to that of the spinning mass.
• the experimentally accessible thread tension is primarily determined by the product of stretch viscosity and stretch speed.
• the stretching speed can be determined from the relationship a where v s is the spraying speed, a the length of the gap between the spinneret outlet and the precipitation bath inlet and SV a the spinning distortion in the gap.
• v s is the spraying speed
• a the length of the gap between the spinneret outlet and the precipitation bath inlet
• SV the spinning distortion in the gap.
• the dry and wet tear strength, the tear strength ratio and the wet abrasion resistance increase with increasing stretch viscosity.
• fibers with a tensile strength ratio of dry / wet of 100% could be spun.
• the method according to the invention permits a significant expansion of the viscosity range in which the cellulose solutions can be spun without problems, or it permits spinning at comparatively lower temperatures or higher cellulose concentrations.
• the solution feed (3) is formed from a tube filled with one or more, optionally heatable, bodies (s) of high thermal conductivity, through which flow channels pass, that the support plate (1) consists of a material with high thermal conductivity, the dimensioning of the flow channels (1.1)
• the relaxation time of the solution at 85 ° C at the maximum frequency of the relaxation time spectrum means that the cone nozzle [n] (6) is surrounded by a separate nozzle temperature control (2) with insulation (2.1).
• the solution supply it consists of a steel tube into which one or more thin-walled stainless steel tubes are drawn in for transporting the solution and where the spaces are cast with aluminum for heat exchange and pressure stabilization.
• 4 shows the nozzle temperature control for a filament spinning position.
• the cone spinneret (6) is of the nozzle temperature control (2), consisting of a high material
• the nozzle temperature control is as in (6.1), Fig. 4 shown exaggerated, slightly conical to ensure a tight fit of the nozzle temperature control on the cone nozzle.
• the thickness of the nozzle temperature control is usually 3 - 6 mm.
• Low-voltage voltage, preferably 24 V, is used to operate the resistance heater.
• nozzle temperature control (2) is shown with a row-shaped arrangement of the cone spinnerets (6).
• the temperature is controlled by the heating cartridges (2.2). As shown in FIG. 2, this arrangement can be used both for staple fibers and for filament yarns.
• Fig. 5 finally shows a preferred arrangement for spinning fibers of the nozzle temperature control (2) with heating cartridges (2.2) and cone spinnerets (6).
• the circularly shaped blowing nozzle (12) is arranged analogously to FIG. 2 and blows the filament bundles radially shortly before entering the precipitation bath.
• the diameter of the cone spinnerets is preferably 12 and 20 mm for textile filament yarns and preferably 20 and 35 mm for technical filament yarns and staple fibers.
• the spinning capillary density is between 15 and 400 spinning capillaries / cm 2 . No special requirements are imposed on the spinning capillaries themselves. According to the material thickness of the cone nozzles of preferably 0.5 mm, the total length of the spinning capillaries is also 0.5 mm.
• the ratio of capillary inlet and capillary outlet cross section is preferably 2: 1 to
• the transition is preferably continuous, the cylindrical spinning capillary outlet has a diameter D of preferably 80-140 ⁇ m and the L / D ratio is preferably 1.
• Nickel-plated or anodized aluminum has proven to be cheap. Copper and brass, also with a surface finish, are excluded due to their lack of chemical resistance. Also with the most careful surface finishing, the formation of copper ions can be observed on contact with the cellulose solution, which can lead to an unacceptable safety risk.
• copper or brass preferably in surface-refined form, can also be used for nozzle temperature control.
• the method and the device according to the invention are intended to explain exemplary embodiments.
• a suspension of spruce sulfite pulp and aqueous N-methylmorpholine-N-oxide (NMMO) is removed under vacuum, elevated temperature and shear until water is removed until a homogeneous solution consisting of 12.4% cellulose (Cuoxam DP 530), 76.2% NMMO and 11.4% water are formed.
• NMMO N-methylmorpholine-N-oxide
• the spinning head, with double jacket heating optionally contained a support plate made of stainless steel or nickel-plated aluminum of 64 mm 0 and 10 mm thickness, on which 40 flow channels with 3 mm 0 are arranged in 3 rows of holes.
• a ring between the support plate and the nozzle plate for receiving 2 cone nozzles formed an inflow chamber with a volume of 23 cm 3 .
• the cone nozzles had a total of 60 spinning capillaries with an output diameter of 130 ⁇ m, the ratio of the inlet to outlet cross-sectional area was 2.7.
• the finenesses 1.2 and 1.6 dtex were spun at a take-off speed of 100 m / min in variants A - with a support plate made of stainless steel, B - with a heat spreader made of nickel-plated aluminum and C - with a heat spreader and nozzle temperature control.
• the temperature of the spinning mass in the inflow space and that of the nozzle temperature was 86 ° C.
• the amount of blowing air was 5 1 / min and nozzle.
• Table 1 The test data and the properties of the spun fibers are shown in Table 1.
• a suspension of cotton linters pulp in aqueous NMMO is transferred analogously to Example 1 into a solution consisting of 12.0% cellulose (Cuoxa DP 579), 76.5% NMMO and 11.5% water.
• the zero shear viscosity was 6630 Pas and the relaxation time was 1.7 s at 85 ° C (see Fig. 7).
• the spinning arrangement essentially corresponded to variant C in Example 1 with the difference that for spinning a cone nozzle (25 x 20 x 9.5 x 0.5 mm) with 750 spinning capillaries with an outlet diameter of 90 ⁇ m and a ratio of inlet to outlet cross section of 6.25 served.
• a fineness of 1.2 dtex was spun at a spinning mass temperature of 76 ° C and various temperatures of the nozzle temperature (43, 60 and 86 ° C). A spinning this Solution at melt temperatures below 80 ° C is not possible without additional nozzle temperature control.
• the filament bundle was blown with 8 1 / min of air from a slot nozzle.
• the test data and fiber parameters are shown in Table 2.
• Example 3 Analogously to Example 1, a suspension consisting of aqueous amine oxide and finely divided eucalyptus pulp was converted into a homogeneous solution of 11.8% cellulose (Cuoxam DP 605), 76.9% NMMO and 11.3% water , The zero shear viscosity was 6800 Pas, the relaxation time 18.6 s at 85 ° C (see FIG. 9).
• the 4 cone nozzles in the spin pack were surrounded by a nozzle temperature control with heating rods designed as a plate (see FIG. 3).
• the nozzle temperature control set to 60 ° C, consisted of nickel-plated brass and was insulated from the nozzle plate by a 0.5 mm thick Teflon film. Without nozzle temperature control, capillary cracks develop continuously. The results are shown in Table 3.
• Example 4 1) measured on the individual filaments
• Example 4 A LIST - Diskotherm B ® - kneader are metered continuously in 1110 g / min to a suspension consisting of 11.9% cellulose, 66.1% NMMO and 22% water, under vacuum, elevated temperature and shear 135 g / min of water withdrawn and removed via a discharge designed as a twin screw conveyor 975 g / min homogeneous solution with a melt temperature of 90 ° C, consisting of 13.5% cellulose, 75.2% NMMO and 11.3% water and formed as a "tube bundle heat exchanger" via the solution feed "with 9 thin-walled stainless steel tubes of 1.5 cm 0, cast with aluminum, fed to the spinning station while cooling to 85 ° C.
• the relaxation time spectrum of the solution corresponds to FIG. 10, the relaxation time is 84.7 s.
• the spinning package is designed as a ring (see FIG. 5), 9 cone nozzles (43 x 35 x 9.5 x 0.5 mm), each with 2500 spinning capillaries, are arranged in a circle.
• the outlet diameter of the spinning capillaries is 90 ⁇ m (L / D ⁇ 1), the ratio of inlet to outlet cross section is 4: 1.
• the nozzle temperature control forms a gold-plated copper plate, which is heated to 70 ° C with heating cartridges and insulated against the nozzle plate with a silicone layer has been.
• the anodically oxidized aluminum support plate which is designed as a ring, contains 1750 flow channels with 0.3 cm 0.
• the volume flow of 13.9 cm 3 / s results in a shear rate of 3.0 s "1.
• the inflow chamber with a volume of 1670 cm 3 led to a residence time of 1.4 x ⁇ s ° c .

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• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Artificial Filaments (AREA)
• Spinning Methods And Devices For Manufacturing Artificial Fibers (AREA)

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