EP3844328B1 - Method and device for filament spinning with deflection - Google Patents

Description

The present invention relates to the shaping and treatment of extruded synthetic fibers after they have been consolidated.

Background of the Invention

Cellulose can be dissolved in aqueous solutions of amine oxides, in particular solutions of N-methyl-morpholine-N-oxide (NMMO), in order to produce spinning products, such as filaments, staple fibers, films, etc., from the spinning solution obtained. This is done by precipitating the extrudates in water or dilute amine oxide solutions after the extrudates are fed from the extruder through a gas gap into the precipitation bath. Usually, cellulose solutions in the range of 4% to 23% are used for processing into extruded products. In the further course, the precipitated extrudates are conveyed on in the form of film or filament strands, with suitable roller take-off units applying the necessary stretching forces (in the gas gap). This process is also referred to as the lyocell process or the cellulose filaments obtained as lyocell filaments.

The U.S. 4,416,698 relates to an extrusion or spinning process for cellulose solutions in order to form cellulose into filaments. Here, a fluid spinning material - a solution of cellulose and NMMO (N-methylmorpholine-N-oxide) or other tertiary amines - is formed by extrusion and placed in a precipitation bath for solidification and expansion.

The U.S. 4,246,221 and the UK 2913589 describe processes for the production of cellulose filaments or films in which the cellulose is stretched in fluid form.

The WO 94/28218 A1 describes a process for the production of cellulose filaments in which a cellulose solution is formed into several strands via a nozzle. These strands are brought into a precipitation bath through a gas-flow gap and continuously discharged.

In CA2057133A1 describes a process for the production of cellulose threads, in which a spinning mass is extruded and introduced via an air gap into a cooled water bath containing NMMO.

The WO 03/014432 A1 describes a precipitation bath with a central thread removal device underneath a cover film.

The EP 1 900 860 AI describes a 2-step coagulation bath a spinning device, wherein the baths can have different compositions of H ₂ S0 ₄ .

The WO 97/33020 A1 relates to a process for producing cellulosic fibers in which a solution of cellulose in a tertiary amine oxide is extruded through spinning holes of a spinneret, the extruded filaments are passed through an air gap, a precipitation bath and over a take-off device with which the filaments that are drawn are drawn Filaments are further processed into cellulosic fibers, the drawn filaments being subjected to a longitudinal tensile stress of not more than 5.5 cN/tex during further processing.

The DE 10200405 A1 describes a lyocell device with a blowing device in the gas gap. Mention is made of a precipitation bath device in which a filament curtain dips into the precipitation bath, is deflected in the precipitation bath and leaves the precipitation bath obliquely upwards to a bundling device. Since it is bundled onto a single strand, strong bundling is to be expected during the deflection.

In WO 02/12600 a spinning process is described in which the maximum economic spinning speed can be calculated from a formula reference, based on fiber titer, number of spinning hole rows and a variable operating parameter.

In WO 02/12599 describes a spinning process in which a curtain of threads is deflected in a coagulation bath and then brought together at points.

The WO 96/20300 describes deflection angles of filaments in the lyocell process according to a formula reference.

A problem of filament damage from deduction is reported in WO 2008/019411 A1 picked up and treated with the help of a mechanical take-off device installed in the spinning bath, whereby this take-off device is also intended to apply part of the take-off forces during operation. In addition to the complex construction, the danger should not be underestimated that individual very fine filaments get caught in the mechanical construction and thus impair the spinning process and the mechanical device in its function.

The WO 2014/057022 describes serial spin baths with different media.

Summary of the Invention

In previous lyocell processes, all individual filaments (individual extrudates) that are in direct contact with the deflection device (e.g. a round rod) are pressed against the deflection device by the normal forces resulting from the tensile force of the entire bundle. As a result of the frictional resistance that occurs, this can lead to tears and end breaks. Particularly in the case of strong bundling, the high normal force resulting from the total pull-off force is exerted on only a few individual filaments which are in direct contact with the deflection device. These few individual filaments can be severely damaged by the high frictional load, especially at high take-off speeds. To make matters worse, the filaments are swollen in the coagulation bath and may still be hot, which means that the mechanical strength is low.

The aim of the present invention is to minimize the frictional force load on each individual filament at the deflection points and thus enable higher productivity and higher spinning speeds. Such a frictional force occurs in spinning baths, in which rigid deflection devices must be used because of the medium, or deflection devices with driven or freely rotating rollers, such as in a take-off mechanism for the filaments.

The present invention provides the user with a computational ability to evaluate their system for the frictional load on the filaments and to take appropriate precautions to adjust the system to minimize the frictional load on all filaments in direct contact with the diverter.

A further aim of the present invention is to ensure manual handling of the filament curtain and accessibility to the deflection point in the treatment zone between spinneret and take-off unit without having to use complex and fault-prone piecing aids or take-off devices.

bestimmt ist, wobei L die Umlenkbreite des Bündels in mm, LZ die Anzahl der Extrusionsöffnungen, B der Umlenkwinkel berechnet aus 180° abzüglich des Umschlingungswinkels der Filamente um die Umlenkvorrichtung in Grad, v die Abzugsgeschwindigkeit der Filamente in Meter pro Sekunde, c_cell die Cellulosekonzentration des extrudierten Fluids in Masse-%, Q eine dimensionslose Lastzahl ist, wobei Q 15 oder kleiner ist. In Formel 1 hat ">" die Bedeutung von "größer als", "x" ist ein Muliplikationszeichen und "cos" bedeutet Kosinus.The invention provides a process for producing solid cellulosic filaments from a fluid of cellulosic, comprising extruding the fluid through a plurality of extrusion orifices to form fluid filaments, preferably passing the fluid filaments through a gas gap, and solidifying the filaments in a coagulation bath, wherein the Filaments in the coagulation bath are bundled and deflected as a bundle in order to be drawn off from the coagulation bath above the level of the coagulation bath, with the bundle of filaments occupying a deflection width L on a deflection device, which according to formula 1: $$\mathrm{L}>\left(2\times \mathrm{LZ}\times \cos \left(\mathrm{B}/2\right)\times {\mathrm{v}}^{2.5}\right)/\left(10\times {{\mathrm{c}}_{\mathrm{cell}}}^{0.5}\times \mathrm{Q}\right)$$

is determined, where L is the deflection width of the bundle in mm, LZ the number of extrusion openings, B the deflection angle calculated from 180° minus the angle of wrap of the filaments around the deflection device in degrees, v the take-off speed of the filaments in meters per second, c _cell the cellulose concentration of the extruded fluid in mass %, Q is a dimensionless load number, where Q is 15 or less. In Formula 1, ">" means "greater than", "x" is a multiplication sign, and "cos" means cosine.

The invention also relates to a device suitable for carrying out this method, with an extrusion plate having a plurality of extrusion openings, a collecting container for a coagulation bath, preferably a gas gap between the extrusion openings and the collecting container, a deflection device in the collecting container for deflecting a filament bundle from the collecting container, and a bundling device , which requires a deflection width L of the filament bundle on the deflection device, wherein the filament bundle assumes a deflection width L on the deflection device, which satisfies the formula 1 already mentioned, where L, LZ, B, v, c _cell and Q have the meaning given above, Q is 15 or less and v is at least 35 m/min, for which the device is thus designed.

According to the invention, wide deflection widths L usually result, therefore the invention also relates to a method for producing solid cellulose filaments from a fluid of cellulose by extruding the fluid through a plurality of extrusion openings, resulting in fluid filaments, preferably passing the fluid filaments through a gas gap, and solidifying the Filaments in a coagulation bath, the filaments being bundled in the coagulation bath and deflected as a bundle in order to be drawn off from the coagulation bath above the level of the coagulation bath, the extrusion openings being arranged over a length LL and the bundle of filaments being on a deflection device occupies a deflection width L which is at least 70% of the length LL. Accordingly, the invention also relates to a device suitable for carrying out this method, with an extrusion plate having a plurality of extrusion openings, a collecting tank for a coagulation bath, preferably a gas gap between the extrusion openings and the collecting tank, a deflection device in the collecting tank for deflecting a filament bundle from the collecting tank, and a Bundling device which causes a deflection width L of the filament bundle on the deflection device, the extrusion openings being arranged over a length LL and the bundle of filaments on the deflection device occupying a deflection width L of at least 70% of the length LL.

The following detailed description relates to the devices and methods equally, e.g. preferred method features also correspond to properties or suitability of the device or its corresponding components and preferred device features also correspond to means that are used in the method according to the invention. All preferred features can be combined with one another, unless this has been explicitly excluded. All process features, including those mentioned above, can be combined with one another. All device features, including those mentioned above, can be combined with one another.

character description

• In 1 a liquid treatment zone is represented as a spinning funnel (6).
• Figure 2a shows a spinning tub system combined with a rectangular spinneret.
• Figure 2b shows a spinning tub system combined with a ring-shaped spinneret (5) and a straight deflection device (2).
• Figure 2c shows a spinning tub system combined with a ring-shaped spinneret, with the annular curtain of extrudate being deflected via a toroidal deflection device with a deflection angle (B') and the deflected curtain of extrudate being guided vertically upwards out of the spinning bath along the central axis of the ring-shaped nozzle.
• Figure 3a shows a trough system with deflection and bundling. At the bundling device, a spinning curtain with width L and deflection angle B deflected.
• Figure 3b shows a tub system with two deflection devices, where, in contrast to Figure 3a , no bundling is carried out at the second deflection. A spinning curtain with width L and deflection angle B is deflected at the second deflection.
• 3c shows a tank system with 3 spinning curtains, which are deflected at a common deflection device in the tank and at separate deflection devices at the edge of the tank, from which the bundles are drawn off, as indicated by the arrows.
• 4 shows a deflection in a take-off unit, which has driven rollers marked "M", in top view (left) and in side view (right). All rollers can be driven ( Figure 4a ) or some ( Figure 4b ). The transport of the filament bundles is indicated with an arrow. The bundles are deflected at an angle B (0° to 150°) on rollers. "L" indicates the width of the filament bundle on the roller.

Detailed description of the invention

The invention relates to the deflection of filament curtains or filament bundles that are bundled at least on one side. The diversion takes place in the coagulation bath in order to transport the filaments out of the bath again. During the deflection, the filaments are brought together in the normal to the deflection axis, so that the filaments in the first layer rest on a deflection device and in the other layers on top of each other. As already mentioned, this leads to material stress, especially at high speeds. According to the invention, the deflection width was increased in order to draw off the filaments at any speed, including high speeds of e.g. 35 m/min or higher.

During the deflection according to the invention, the filaments are guided as a wide band. The term "filament bundle" therefore includes bands of filaments guided together, which have a width and height in cross section, the width being greater than the height.

The above formula 1 with Q of 15 or less relates in particular to the deflection in the coagulation bath, in which the fibers are particularly susceptible to the frictional influences mentioned in the summary due to the temperature control and the swelling conditions. The coagulation bath is a part of the treatment zone of the extruded filaments. In the lyocell process, the filaments have not yet reached their final structure and stability. The structure and stability initially change as a result of stretching (mainly in the gas gap) and solvent exchange (mainly in the coagulation bath). Even after exiting the coagulation bath, material changes can still occur, so that the path of the filaments/extrudates between the spinneret outlet and a washing out of solvent from the filaments/extrudates, including a take-off unit, is referred to as the treatment zone. Since the extruded filaments do not yet have their final shape, they are also referred to as "extrudates" in the treatment zone. A take-off unit is a device that applies the necessary drafting forces for thread formation and the frictional forces that occur on the filaments/extrudates during transport from the spinneret to the take-off unit. Within the coagulation bath, due to the hydrodynamic conditions, there is a very high risk of coiling in the case of driven or freely rotating deflectors, so that fixed deflectors are preferably used within the coagulation bath. Outside of the coagulation bath, fixed deflectors should be deflected as little as possible, or free-rotating or driven deflection devices should be used. In the case of freely rotating or driven deflection devices, the filaments/extrudates are less susceptible to friction effects, so that smaller deflection widths L than calculated according to formula 1 are also used. However, a certain width is still maintained, especially for the deflection at the trigger mechanism, since friction effects also occur here. The task of the take-off mechanism is to ensure the required take-off speed depending on the hole throughput (per extrusion opening). A take-off unit imparts the take-off speed to the filaments/extrudates using driven or multiple deflection devices such as rollers or cylinders. Here, the deflection force of the roller is first transferred to the filaments/extrudates on the inside, which in turn transfer the force to filaments/extrudates further to the outside. The inner filaments/extrudates are therefore more heavily stressed than the outer ones, an inequality that is minimized according to the invention by maintaining a deflection width such that the inner filaments/extrudates are only supported by a limited number of outer ones filaments/extrudates are superimposed, maintaining rapid and efficient operation. Extrusion openings can be bores or holes in an extrusion plate, as well as capillaries. For all of these options, the number of extrusion openings is also referred to as the number of holes. The withdrawal can take place in a gas space into which the filaments enter after removal from the coagulation bath.

According to the invention, a machine part is referred to as a deflection device which enables a change of direction of individual extrudates, of extrudate curtains or of extrudate bundles. The deflection width L of the deflected curtain is preferably not influenced by the deflection device itself.

In principle, such deflection devices can be designed as a rigid deflection device or rotating deflection device. Rotating deflection devices can be designed with or without a drive. Rotating deflection devices have the advantage that low frictional forces can arise between the extrudate and the deflection device and thus extremely gentle deflection can take place - with the exception of a deflection in a take-off unit when forces are transferred from the deflection device to the filaments/extrudates. The disadvantage of rotating deflection devices, however, is that due to the stickiness of individual extrudates, they can stick to the rotating deflection device, which can cause curling, tearing off and other problems. The use of rotating deflection devices in liquids (in the coagulation bath) is also problematic because, due to hydrodynamic turbulence in the area of the deflector surface, there is a very high risk that individual extrudates will be swept along by these turbulences on the circumference of the deflection device, causing curling, tearing off and other disturbances can become.

Rigid deflection devices, for example in the form of rods, coils, cage deflectors or any other form, are preferred for use in spinning bath liquids but also in the case of sticky, moist or otherwise adhering extrudate curtains or bundles.

All materials that have the lowest possible sliding friction values can be used as materials for rigid deflection devices. In addition to metals with and without coating Textile ceramics or plastic are also possible.

A deflection device is preferably used in the coagulation bath. Two or more deflection devices in the coagulation bath are also possible, as a result of which greater options for (larger) deflection angles B are possible for each deflection device. According to the invention, formula 1 is fulfilled by the first, preferably also the second or also each deflection device in the coagulation bath. "First", "second", etc. in this sense refers to the procedural proximity to extrusion and the order in which the filaments/extrudates pass the turning devices.

Even after the coagulation bath in the treatment zone, the filaments/extrudates are kept as a belt at a certain deflection width, since here too, especially in a take-off unit, frictional forces are at work that can cause damage during deflection. However, the deflection width after the coagulation bath can be less than in the coagulation bath, since the negative effects on filament stability due to temperature and swelling can be less. Preferably, according to the invention, outside of the coagulation bath at least at a deflection width L _outside which is L according to formula 1 (with Q less than or equal to 15) divided by 30, preferably divided by 20, preferably divided by 10, particularly preferably divided by 5, and/or or the filament bundle is kept at this width L _{on the outside} (also between the deflection) - at least up to a take-off mechanism and/or a washing device. Alternatively, L _outside can be calculated according to formula 1, in which case a higher value can be used for Q, namely Q here can have a value of up to 300 or up to 250, eg 10-300 or 40-250. In a washing device, the filament bundle is usually fanned out even more in order to promote the washing process. L _{on the outside} can also be at least L according to formula 1 (with Q to 15), for example in the washing process.

L _outside (deflection or bandwidth outside the coagulation bath) can also be defined independently of L according to formula 1. L _external is preferably selected so that at the given take-off speed there is a filament density per mm of deflection width of no more than 7000 dtex/mm, preferably no more than 6000 dtex/mm, no more than 5000 dtex/mm, particularly preferably no more than 4000 dtex/mm.

This deflection or bandwidth outside of the coagulation bath is L _outside preferably at the immediately next deflection after the filaments/extrudates have left the coagulation bath, since the filaments/extrudates are even more sensitive here, and/or in the take-off unit, since the filaments/extrudates are particularly impaired here due to a force transmission. After leaving the coagulation bath, the filament bundles are preferably always kept at least at the _width L outside in the entire treatment zone or during the entire processing of the filaments/extrudates until the end products are cut and/or wound up. The processing usually includes the following areas: spinning in the coagulation bath (as above), leading out of the coagulation bath, drawing off via a take-off device, washing, drying, winding and/or cutting of the filaments as end products.

Alternatively or additionally, a spinning process, including further processing, can have the following steps: extrusion through a spinneret, passing the filaments/extrudates through a gas gap (in which a gas stream is preferably blown in, see below) into a coagulation bath (precipitation bath), deflecting the filaments/extrudates in the precipitation bath, preferably attached by a deflection device opposite the spinneret, leading the coagulated filaments/extrudates out of the coagulation bath, deflecting the filaments/extrudates outside of the coagulation bath and without further bundling with other coagulated filaments/extrudates, feeding the filaments/extrudates to a take-off unit ( also referred to as a take-off element or take-off device) and/or drafting device, as well as continuation to a filament take-up unit and/or drafting system, washing, drying and, if necessary, further steps as desired. The device according to the invention has the appropriate apparatus for this. In a further embodiment, the process can have the following steps: extrusion through a spinneret, passing the filaments/extrudates through a gas gap (in which a gas stream is preferably blown in, see below) into a coagulation bath, deflection outside the coagulation bath, bundling or merging with other filaments /extrudates, feeding the filaments/extrudates to one or more take-off units, washing, drying and, if necessary, further steps or apparatus for this, as desired.

Some steps can be combined: This means that washing can be carried out in the exhaust system. In each of the steps herein mentioned in detail described or preferred embodiments apply. Likewise, driven cylinders or rollers can be combined with non-driven ones in a take-off mechanism, such as in CN 105887226 (A ) described. Heat treatment, such as drying, e.g. as in CN 205133803 U _described, be made. When starting the process, a piecing aid, as in CN205258674U _described, used; however, this is only an aid and not essential.

Further steps or apparatus for this can be provided. For example, drying can be carried out after washing, or a dryer can be provided after the washing system, with one or more further treatment step(s) such as e.g. B. the finishing of the filaments / extrudates or a finishing device can be provided. In addition, other process steps such as dyeing, crosslinking, ultrasonic treatments can also be carried out before drying; or devices or apparatus are provided for this purpose.

At any process point up to drying, a cutting device (for cutting) or a winding device (for winding) can preferably be interposed in order to produce staple fibers or continuous yarns from the continuous filaments.

A pull of less than or equal to 3 cN/dtex, preferably less than or equal to 2 cN/dtex or less than or equal to 1.5 cN/dtex is preferably exerted on the filaments/extrudates in the take-off unit.

The filament bundles from several spinning positions can be combined to form a combined overall bundle. Such a combination usually takes place immediately after or upon exit from the coagulation bath, so that the downstream plant components, such as extraction or washing, can be applied to the entire bundle. The width L or L _outside is usually specified here in relation to a spinning position and increases accordingly after the combination. L _outside can be at least 8 mm, for example 8 mm to 100 mm, preferably 12 mm to 70 mm per spinning position.

The bundling device refers to a machine part which narrows and thereby expands the deflection width of the extrudate curtain due to the geometric shape of the bundling device forms an extrudate bundle with a flat or tubular or else round or other shaped curtain of extrudates. Optionally, the bundling device also forces a change in direction of the formed bundle of extrudates. Thus, the bundling device can also be a deflection device, to which the rules according to the invention and preferably embodiments apply. Bundling devices can be designed to be rigid or rotating, analogously to the description of the deflection device. The same materials can be used. Rigid bundling devices in the form of rods, coils, cage deflectors, hooks, eyelets, U-guides or any other form of devices are preferably used for use in spinning bath liquids but also in the case of sticky, moist or otherwise adhering extrudate curtains or bundles.

The load factor Q is an empirical measure for the filaments lying one on top of the other at the deflection device. The lower, the gentler the procedure. L must be selected all the larger. Q in the coagulation bath should be 15 or less, preferably Q is 12 or less, preferably 8 or less, or 5 or less. In connection herewith, Q is 2 or greater, preferably 3 or greater, or 4 or 5 or greater, more preferably wherein Q is 2-15, or more preferably 4-12. Possible values for Q are 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or any value in between. As mentioned above, Q can be larger outside the bath. Here, the sign L is used for L _{on the outside} with Q up to 300. Unless otherwise stated, Q refers to a deflection in the coagulation bath.

The number of extrusion openings (also referred to as the number of holes, abbreviated "LZ") determines the number of filaments that have to be deflected. The method according to the invention is designed in particular for large, industrially useful sizes. Preferably the number of extrusion openings LZ is 2000 or more, preferably 5000 or more or 10000 or more. Independently or in combination, LZ can be 500,000 or less, preferably 200,000 or less, 100,000 or less, or 50,000 or less. If larger quantities of product and thus a larger number of filaments are to be produced simultaneously, several extrusion devices according to the invention can be used in order to produce several parallel filament bundles or curtains, possibly in a common coagulation bath or even with a common deflection device. The hole numbers given above refer to a bundle or a group of filaments that are deflected and bundled together.

The deflection angle B results from the angle enclosed by the filaments fed to the deflection device and the deflected filaments (see figures). A more acute angle places greater shear and frictional forces on the filaments. The more acute the angle, the greater L must be increased (while the other parameters of formula 1 remain the same). The deflection angle B is preferably an angle of 10° to 90°, preferably 20° to 60° or 25° to 45°. Unless otherwise stated, angle B refers to a deflection in the coagulation bath. Outside, e.g. in a pull-off unit and/or during washing, the deflection angle can be 0° to 150°, in particular any angle in this range, such as was specified for the angles in the coagulation bath.

According to the invention, the large deflection widths L enable high take-off speeds. The filaments are drawn through the coagulation bath, usually with the help of a draw-off mechanism. The draw-off mechanism itself is usually outside of the coagulation bath, downstream of the deflection device and possibly also of the bundling device. A corresponding deflection width L is selected according to the take-off speed. The take-off speed (at the deflection device) is preferably at least 35 m/min. The take-off speed v can be 36 m/min or more, preferably 40 m/min or more or 45 m/min or 50 m/min or more. Regardless of this or in combination, the take-off speed v can be 200 m/min or less or 150 m/min or less.

An extrusion medium is used as the fluid in the method according to the invention. This is preferably a solution or mixture of cellulose and other medium components such as solvents. The cellulose concentration is selected in the ranges customary for lyocell processes. Thus, the cellulose concentration of the extruded fluid c _cell can be 4% to 23%, preferably 6% to 20%, in particular 8% to 18% or 10% to 16% (all percentages are by mass). In the lyocell process, the extrusion medium is usually a cellulose solution or melt with NMMO (N-methylmorpholine-N-oxide) and water, as described in the introduction. Other solutions of cellulose, especially ionic solvents of cellulose can also be used. Ionic solvents are for example in WO 2006/000197 A1 described and preferably contain organic cations such as ammonium, pyrimidium or imidazolium cations, preferably 1, 3-dialkyl-imidazolium halides. Here, too, water is preferably used as a solvent additive. A solution of cellulose and butyl-3-methylimidazolium (BMIM), for example with chloride as counterion (BMIMCl), or 1-ethyl-3-methylimidazolium (also preferably as chloride) and water is particularly preferred.

The step of passing the fluid filaments through a gas gap in the method according to the invention or the gas gap in the device according to the invention is optional, i.e. it may or may not be included/present. This step/means distinguishes between wet spinning and dry-wet spinning. With wet spinning, the filaments are fed directly into the coagulation bath. In dry-wet spinning, the gas gap is present and the filaments pass through it first before entering the coagulation bath.

Optionally (and preferably, in particular in the case of large, industrially relevant systems) a gas stream can be blown into the gas gap or a blower is provided for this purpose in the device. The injected gas stream preferably has a temperature of from 5°C to 65°C, preferably from 10°C to 40°C. The material fluid can be extruded at a temperature of 75°C to 160°C. Preferably, the gas gap has a lower temperature than that of the extruded material fluid. In particular, a gas flow is conducted in the gas gap at a lower temperature than the extruded material fluid.

Possible lengths of the gas gap, ie the distance between the extrusion openings and the coagulation bath or container for this, such as a trough, are preferably between 10 mm and 200 mm, in particular between 15 mm and 100 mm, or between 20 mm and 80 mm. It is preferably at least 15 mm. The gas in the gas gap is preferably air. The gas flow is preferably an air flow. Other inert gases are also possible. An inert gas is a gas that does not interact with the fluid filaments in the gas gap and preferably also not with the solidification medium, such as water or a diluted NMMO in water solution or other solvent components - depending on the extrusion medium used -, chemically reacted.

In wet spinning, the treatment zone essentially consists of liquid containers, liquid funnels or liquid channels. The extrudates emerging from the spinneret are introduced directly into the spin bath liquid for precipitation and/or cooling. The moist (precipitated and/or cooled) extrudates are fed to the take-off mechanism through washing baths and/or through a gas or air space.

In dry-wet spinning, the treatment zone essentially consists of a gas or air gap and downstream liquid containers, liquid funnels or liquid channels. The extrudates emerging from the extrusion openings pass through a gas gap and then through a coagulation bath, also referred to as a spinning bath. The moist (precipitated and/or cooled) extrudates are fed to the take-off unit through one or more washing baths and/or through a gas or air space.

In the wet or dry-wet spinning process, turbulence and vortices occur at higher speeds due to displacement and drag processes between the coagulation bath liquid and the extrudates. In addition, in the case of deflection points with rigid deflections, there is also the risk of dry running at the contact points between the extrudate and the deflector. The risk of running dry becomes greater the higher the take-off speed and the stronger the extrudate curtains or bundles thereof are pressed against the deflection device.

Preferably, the extrusion openings are arranged in an elongate form in order to form the extruded filaments in a geometry that is favorable for deflection and bundling during deflection. The longitudinal direction of the arrangement of the extrusion openings therefore preferably also corresponds to a longitudinal direction of the deflection device. This longitudinal direction of the deflection device therefore preferably corresponds to a deflection axis (or follows several deflection axes in the case of curved deflection devices). Possible shapes for the arrangement of the extrusion openings are a rectangular shape, a curved shape, a ring or a ring segment shape. The elongate shape may have a length to width ratio of from 100:1 to 2:1, preferably from 60:1 to 5:1 or from 40:1 to 10:1.

The extrusion orifices preferably have a diameter of 30 microns to 200 microns, preferably from 50 microns to 150 microns or from 60µm to 100µm. This can be used to produce filaments suitable for textiles (woven and non-woven).

The extrusion throughput is preferably adjusted in such a way that, at the given take-off speed, the individual fibers have a fineness of 1.3 dtex +/-50%, preferably +/-25% or +/-10%. The extrusion throughput can be adjusted by the pressure of the extruded mass, ie the cellulose solution. Possible pressures are, for example, 5 to 100 bar, preferably 8 to 40 bar.

An overall wide deflection width L is particularly preferred, also in the sense of an independent main inventive feature independent of formula 1. Depending on formula 1 or independently of it, the extrusion openings can be arranged over a length LL, with the deflection width L being at least 70% according to this characteristic of the invention. , preferably at least 80% or at least 90%, of the length LL. The deflection width can also be equal to the length LL or even greater, such as 110% of the length LL or more. L _outside is preferably at least 1%, at least 3%, preferably at least 5% or also at least 10% of the length LL. For bundling purposes, L _outside is preferably at most 50% of the length LL. All of the process parameters and device settings according to the invention can be combined with one another. For example, a particularly preferred combination is a take-off speed v of 40 m/min to 150 m/min and a load factor Q of 4 to 13 or 5 to 12. Of course, all of the values described herein are also possible within these ranges or outside of them.

Examples:

The liquid treatment zone in the dry-wet spinning process can be designed in various ways, some variants are based on the figures 1 , 2a , 2 B , 2c , 3a and 3b described. Test parameters and results are given in Table 1:
In 1 a first embodiment of the liquid treatment zone is shown as a spinning funnel. In this variant, the spin bath liquid is fed into a funnel-shaped container (6) via a feed point (1). The funnel-shaped container (6) has a bottom opening at the lower end. About a used in the bottom opening bundling device is a part of the supplied spinning bath together with derived from the extrudates (4) passed through the spinning funnel from top to bottom. The excess part of the spinning bath is discharged via an overflow edge (3). The overflow edge (3) is also used to adjust the air gap (7).
The extrudates emerging from the spinneret (5) are bundled vertically downwards and discharged from the spinning funnel via a bundling device. The cross section of the bundling device can be round, oval, polygonal or slot-shaped.

A deflection angle (B) results from the normal distance (H) between the nozzle outlet (5) and the bundling device and the given geometric conditions of the nozzle (5). The deflection width (L) is that section of the deflection device (2) on which the extrudates actually rest and are deflected or bundled. In the case of a toroidal bundling device, the deflection width (L) results from the product of the bundling diameter (D) and the circle number (3.1415...). The deflection angle (B) results from the chosen geometric conditions. The minimum required deflection width (L) is calculated using formula 1.

In Figure 2a , 2 B , 2c , 3a and 3b a liquid treatment zone is shown as a spin tub. In these variants, the spinning bath liquid (coagulation liquid) is fed via a feed point (1) into a trough-shaped container (8) of any shape. The liquid is discharged from the container again via an overflow edge (3). The overflow edge (3) is also used to adjust the air gap (7). A deflection device (2) and/or possibly a bundling device is fitted inside the spinning tub (8). The extrudates (4) emerging from the spinneret (5) are introduced vertically downwards into the trough (8). The extrudates (4) are deflected at the deflection device (2) in the spin bath tub, bundled if necessary, guided upwards out of the spin bath and fed to the further treatment steps. The deflection or bundling device can have a round, oval or polygonal cross-section. A deflection device (2) can, for example, also be a cage or bar roller consisting of several bars; a deflection roller with ribs arranged transversely to the extrudate conveying direction is also possible. According to a further embodiment, the deflection device (2) also be designed concave in the axial direction in order to cause not only the deflection of the extrudates (4) but also a bundling to form an extrudate strand. Since rotating elements in the spin bath liquid inevitably lead to spin bath turbulence and subsequently to winders, tear-offs and other disturbances, deflection devices (2) in the spin bath are generally preferably designed as rigid deflection devices.

The normal distance (H) between the nozzle outlet (5) and the bundling device is set in such a way that the nozzle pull-off angle results in a value of less than 45°, less than 30°, less than 15° or preferably less than 10°. This measure ensures that the extrudates can be removed from the nozzle channel gently and with little deflection. Depending on the normal distance (H) and the nozzle take-off angle, the deflection angle (B) is set for the given geometric conditions. The deflection width (L) is that portion of the length of the deflection device (2) on which the extrudates lie directly and are deflected or bundled. In the case of a curved (concave) deflection device (2), this is accordingly the extended length of the contact line occupied by the extrudates. The deflection angle (B) results from the chosen geometric conditions. The minimum deflection width (L) is calculated using formula 1.

Figure 2a shows a spinning tub system combined with a rectangular arrangement of the extrusion openings (on the extruder, spinneret). Small deflection angles (B) with a large deflection width (L) are typical for the tub system with rectangular nozzle.

Figure 2b shows a spin tub system combined with an annular extrusion orifice arrangement. In contrast to the system with a rectangular nozzle ( Figure 2a ) there are disadvantages in this embodiment. The nozzle take-off angle is compared to the rectangular nozzle design Figure 2a much larger, which means that there is no longer a gentle discharge from the nozzle channel. In the case of large annular nozzle diameters in particular, it is therefore necessary to significantly increase the normal distance (H) between the nozzle and the deflection device (2). Since the normal distance (H) required for large ring dies can be more than 1 meter, manual access to the deflection device (2) is more difficult, and the strong frictional forces between the extrudates and the coagulation bath have a negative effect on the overall tension in the filament bundle. Another disadvantage of execution after Figure 2b is the requirement that, in the case of a ring die in the spin bath, not only deflection but also bundling must be carried out in order to be able to provide the same conditions as possible for all ring-shaped extrudates. Small deflection angles (B) with a small deflection width (L) are typical for the tank system with ring nozzle and centric bundling in the spinning bath.

Figure 2c shows a spinning tub system combined with a ring-shaped spinneret, with the annular curtain of extrudate being deflected via a toroidal deflection device (2) with a deflection angle (B') and the deflected curtain of extrudate being guided vertically upwards out of the spinning bath along the central axis of the ring nozzle. The extrudate curtain can be bundled at an advantageously large deflection angle (B") above the ring nozzle and thus outside the spin bath. Since the bundling or deflection takes place outside of the spinning bath liquid, the bundling or deflection can also be implemented with freely rotating rollers, which means that there is no sliding friction between the extrudate bundle and the deflection device (2).A further embodiment for bundling above the ring spinneret, similar to the spinning funnel, is to provide a toroidal bundling device (9) and, if necessary, to install a freely rotating deflection roller downstream Figure 2c can many disadvantages which a system after Figure 2b has to be eliminated. The nozzle take-off angle (A) is compared to the ring nozzle design Figure 2b greatly reduced, resulting in a gentle extraction from the nozzle. Even with large nozzles, the normal distance (H) can be kept small, which allows manual access to the deflection device (2). A bundling of the extrudate curtain in the spin bath is not required. Small deflection angles (B) with a large deflection width (L) are typical for the tub system with ring nozzle and toroidal deflection device (2) in the spin bath.

Figure 3a shows a comparative example in the form of a spinning tub system, combined with a rectangular nozzle, with the extrudate curtain being deflected twice in the spinning tub. The first deflection process, viewed in the direction of production, is analogous to the design Figure 2a designed, the second deflection serves to further change direction and at the same time to bundle the extrudate curtain into an extrudate strand. Rather moderate deflection angles are typical for the deflection system with bundling shown (B) with a small deflection width (L) due to the bundling. Due to the strong bundling, it was necessary to choose a high number of loads of 20. The spinning behavior turned out to be unsatisfactory.

Figure 3b shows a spinning tub system as in Figure 3a shown, however, the second deflection was dimensioned based on a significantly smaller number of loads (no or little bundling). Due to the greater length (L) of the deflection device (2), in contrast to the version according to Figure 3a a very satisfactory spinning behavior can be achieved.

After exiting the coagulation bath, the bundles are taken to a take-off mechanism and a washing station, which can also be combined with one another, for joint take-off and washing. The first take-off mechanism after the bath conveys the take-off speed of the threads during spinning. 4 shows a possible take-off unit, with 5 rollers, 3 with a motor ("M" in a circle), being shown schematically here. Any number of rollers adapted to the system can be used, for example 1 to 60 is usual. The bundles are deflected at the rollers at an angle B of 0° to 150°. Here, too, the width of the filament bundles according to formula 1 is preferably maintained, where Q can be higher than in the coagulation bath, for example 40 to 300. All rollers can be driven or only some of the rollers. All driven rollers can be driven together or separately. With simultaneous washing, a different speed is recommended, at least for the rotation of the roller surface, and for rollers of the same size also for the rotation speed of the rollers themselves, since the filaments lose solvent and shrink during washing. The shrinking process should be represented by falling speeds so that the filaments do not tear. Non-driven rollers can be freely rotating rollers. With driven rollers, static friction occurs between the filaments and the roller; in the case of non-driven rollers, there is sliding friction between the filament and the roller.

To produce the cellulose solution, an ionic solution was produced as an alternative and parallel to the lyocell method using NMMO/water as the solvent. The cellulose used was of the eucalyptus pulp type and was suspended in deionized water. After the cellulose fibers had been completely suspended in the water, the excess water was removed by filtration and the cellulose cake obtained was pressed to a solids concentration of approx. 50% cellulose. After dewatering, the pulp cake was passed over a needle roller and shredder for defibration. The finely fibrillated moist cellulose obtained was continuously discharged into the aqueous ionic liquid 1-N-butyl-3-methylimidazolium chloride (BMIMCl) in order to produce the pre-mix. annular layer mixer and/or turbulent mixers are suitable devices for this.

In the further course of the process, the mixture of water, cellulose and BMIMCl was introduced into a continuously operating vertical kneader of the Reactotherm type from Buss-SMS-Canzler GmbH to produce the cellulose solution. Similar devices of kneading and reactor technology as well as all types of extruders, high-viscosity thin layerers, stirred tanks and/or disc reactors can be used individually or in combination in various reactor zones and process stages for the production of cellulose solutions. In this vertical Reactotherm kneader, the cellulose solution could be continuously produced without lumps through intensive mixing and kneading. Treatment times in the individual reactor zones of 20 to 80 minutes led to the complete dissolution of the cellulose.

To ensure reliable process control, further stabilizers were added to the aqueous mixture of ionic liquid and cellulose before it was transferred from the pre-mix to the cellulose solution to stabilize the solvent and prevent cellulose degradation. The continuously produced pre-mix was converted into a highly viscoelastic solution by applying temperature and reduced pressure (vacuum) and by shearing. The temperatures used in the individual process stages varied between 85° C. and 150° C., with the removal of excess water taking place at a reduced pressure of between 10 and 150 mbar. The shear rates applied ranged from 20 to 200 rpm to homogenize the pre-mix, while maintaining the set shear power and torque. This ensured that the cellulose dissolved in the ionic liquid. The highly viscous cellulose solution obtained in this way was subjected to additional process steps such as degassing and filtration before spinning. To set the appropriate cellulose dope quality, the solution was additionally fed via one or more high-viscosity heat exchangers of the Sulzer SMR/SMXL type, which were adapted to the process stages. In addition to setting the temperature, these are primarily used to set the desired spinning viscosity and the degree of polymerization of the cellulose. These heat exchangers were therefore used for efficient temperature adjustment, such as cooling or heating the highly viscous cellulose solution, as they allowed effective mixing and controlled heat transfer.

The cellulose solution was spun into filaments and further processed according to the invention, with the spinning solution being fed by means of a spinning pump to a heated spinning pack consisting of a spinneret filter, distribution plates and the spinneret. The spinning temperatures were in the range of 85°C - 150°C, preferably in the range of 95°C - 115°C. After the solution preparation step, attention was paid to short residence times at elevated temperatures in the process system in order to adapt the cellulose solution to the processing speed and the undesirable degradation of the cellulose.

The spinning process used is described according to the invention and is usually referred to as a dry-wet spinning process, with the adjustable, height-adjustable air gap being arranged between the spinneret and the aqueous coagulation bath containing the ionic liquid. The gas flow fed to the air gap and thus passing through the filaments takes place in a conditioned state and can either be conditioned air or another inert spinning gas. According to the invention, the filaments are guided through the coagulation bath, removed from the bath and fed to further treatment as described above. The parameters and product properties of the experiments with BMIMCl and NMMO as solvents are summarized in Table 2. <b>Table 2:</b> Ionic Liquid (BMIMCl) N-Methyl Morpholine N-Oxide (NMMO) cellulose eucalyptus eucalyptus DP Cuoaxam [-] 535 646 α cellulose content [%] 95.2 94.8 carboxyl group content [µmol/g] 17 27 carbonyl group content [µmol/g] 23 29 ash content [%] 0.4 0.2 Degree of whiteness WCIE [-] 82 84 fiber data Solids content of cellulose in ionic liquid [%] 13:27 12.8 DP Cuoxam [-] 521 584 Zero shear viscosity at 85°C [Pas] 39,720 19,250 dope temperature [°C] 102 95 nozzle hole diameter [µ] 90 90 spin print [bar] 37 27 air gap [mm] 43 38 spin bath temperature [°C] 20 18 fiber fineness [dtex] 1.63 1.71 Tear strength conditioned [cN/tex] 51.2 41.0 elongation conditioned [%] 13.9 15.2 wet module [cN/tex] 297 185 wet abrasion [U] 54 38

Claims (15)

1. Method for producing solid cellulose filaments from a fluid of cellulose by extruding the fluid through a plurality of extrusion openings to form fluid filaments, preferably passing the fluid filaments through a gas gap, and solidifying the filaments in a coagulation bath, the filaments being bundled in the coagulation bath and being deflected as bundles in order to be drawn off from the coagulation bath above the level of the coagulation bath, characterised in that the bundle of filaments on a deflection device (2) assumes a deflection width L which is controlled according to the formula: $$\mathrm{L}>\left(2\times \mathrm{LZ}\times \cos \left(\mathrm{B}/2\right)\times {\mathrm{V}}^{2.5}\right)/\left(10\times {{\mathrm{C}}_{\mathrm{cell}}}^{0.5}\times \mathrm{Q}\right)$$

   

   where L is the deflection width of the bundle in mm, LZ is the number of extrusion openings, B is the deflection angle calculated from 180° minus the angle of wrap of the filaments around the deflection device (2) in degrees, v is the draw-off speed of the filaments in metres per second, C_cell is the cellulose concentration of the extruded fluid in mass % and Q is a dimensionless load number, where Q is 15 or less.
2. Device for carrying out a method according to claim 1, comprising an extrusion plate having a plurality of extrusion openings, a collecting vessel (8) for a coagulation bath, preferably having a gas gap between the extrusion openings and the collecting vessel (8), a deflection device (2) in the collecting vessel (8) for deflecting a filament bundle from the collecting vessel (8), and a bundling device (9) which causes a deflection width L of the filament bundle on the deflection device (2), wherein the filament bundle on the deflection device (2) assumes a deflection width L which fulfils the formula: $$\mathrm{L}>\left(2\times \mathrm{LZ}\times \cos \left(\mathrm{B}/2\right)\times {\mathrm{V}}^{2.5}\right)/\left(10\times {{\mathrm{C}}_{\mathrm{cell}}}^{0.5}\times \mathrm{Q}\right)$$

   

   where L, LZ, B, v, C_cell and Q are as defined in claim 1, Q is 15 or less and v is at least 35 m/min.
3. Method or device according to either claim 1 or claim 2, characterised in that Q is 12 or less, preferably 8 or less or 5 or less, and/or in that Q is 2 or more, preferably 3 or more or 4, or 5 or more, particularly preferably where Q is 2 to 15 or more preferably 4 to 12.
4. Method or apparatus according to any of claims 1 to 3, characterised in that the number of extrusion openings LZ is 2,000 or more, preferably 5,000 or more or 10,000 or more, and/or in that LZ is 500,000 or less, preferably 100,000 or less or 50,000 or less.
5. Method or apparatus according to any of claims 1 to 4, characterised in that the deflection angle B is an angle of 10° to 90°, preferably 20° to 60° or 25° to 45°.
6. Method or apparatus according to any of claims 1 to 5, characterised in that the draw-off speed v is 36 m/min or more, preferably 40 m/min or more or 45 m/min or 50 m/min or more, and/or 200 m/min or less or 150 m/min or less.
7. Method or apparatus according to any of claims 1 to 6, characterised in that the cellulose concentration of the extruded fluid C_cell is 4% to 23%, preferably 6% to 20%, in particular 8% to 18% or 10% to 16% (all percentages in mass %) and/or the extruded fluid containing cellulose, NMMO and water or cellulose, an organic cationic solvent and water.
8. Method or apparatus according to any of claims 1 to 7, characterised in that a gas flow is blown in the gas gap or a blower is provided in the device for this purpose, the gas flow preferably having a temperature of 5°C to 65°C, preferably of 10°C to 40°C.
9. Method or apparatus according to any of claims 1 to 8, characterised in that the extrusion openings are arranged in an elongate shape, preferably in rectangular shape, curved shape, annular shape or annular segment shape, the elongate shape preferably having a ratio of length to width of 100:1 to 2:1, preferably of 60:1 to 5:1 or of 40:1 to 10:1.
10. Method or apparatus according to any of claims 1 to 9, characterised by the further steps of removing the coagulated filaments from the coagulation bath, deflecting the filaments outside the coagulation bath with or without further bundling with other coagulated filaments, feeding the filaments onto a draw-off mechanism and/or a drawing device, and further guiding said filaments to a filament-receiving unit, washing and drying the filaments, further steps preferably being optionally provided: finishing, dyeing, crosslinking, ultrasonically treating, cutting, and/or winding the filaments/extrudates in each case.
11. Method or apparatus according to any of claims 1 to 10,
    characterised in that the extrusion openings have a diameter of 30 µm to 200 µm, preferably of 50 µm to 150 µm or of 60 µm to 100 µm.
12. Method or apparatus according to any of claims 1 to 11,
    characterised in that the extrusion openings are arranged on a length LL and the deflection width L is at least 80%, preferably at least 90%, of the length LL.
13. Method for producing solid cellulose filaments from a fluid of cellulose by extruding the fluid through a plurality of extrusion openings to form fluid filaments, preferably passing the fluid filaments through a gas gap, and solidifying the filaments in a coagulation bath, the filaments being bundled in the coagulation bath and being deflected as bundles in order to be drawn off from the coagulation bath above the level of the coagulation bath, characterised in that the extrusion openings are arranged on a length LL and the bundle of filaments on a deflection device (2) assumes a deflection width L which is at least 80% of the length LL.
14. Device for carrying out a method according to claim 13, comprising an extrusion plate having a plurality of extrusion openings, a collecting vessel (8) for a coagulation bath, preferably having a gas gap between the extrusion openings and the collecting vessel (8), a deflection device (2) in the collecting vessel (8) for deflecting a filament bundle from the collecting vessel (8), and a bundling device (9) which causes a deflection width L of the filament bundle on the deflection device (2), characterised in that the extrusion openings are arranged on a length LL and the bundle of filaments on a deflection device (2) assumes a deflection width L of at least 80% of the length LL.
15. Method or apparatus according to any of claims 1 to 14,
    characterised in that the bundle of filaments on a deflection device (2) outside the coagulation bath assumes a deflection width L_außen which is controlled according to the formula: $${\mathrm{L}}_{\mathrm{außen}}>\left(2\times \mathrm{LZ}\times \cos \left(\mathrm{B}/2\right)\times {\mathrm{v}}^{2.5}\right)/\left(10\times {{\mathrm{C}}_{\mathrm{cell}}}^{0.5}\times \mathrm{Q}\right)$$

    

    where L_außen is the deflection width of the bundle in mm, LZ is the number of extrusion openings, B is the deflection angle calculated from 180° minus the angle of wrap of the filaments around the deflection device (2) in degrees, v is the speed of the filaments in metres per second, C_cell is the cellulose concentration of the extruded fluid in mass % and Q is a dimensionless load number, where q is 300 or less;

    preferably at least during a first deflection after the filaments have exited the coagulation bath and/or at least during a deflection in a draw-off mechanism.

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