A fiber spinning method

Abstract

A method and system for intended for fiber spinning, said method comprising flushing a spinning head (4) with a liquid flush solvent before starting a fiber spinning procedure. The system comprises - a supply system (2), such as a tank, intended for liquid flush solvent - a spinning system (3) with a spinning head (4), - an inflow feeding line system (5) for supplying liquid to the spinning system (3) comprising the spinning head (4), said spinning system (3) also comprising a connection / disconnection unit (6), at an end position of the inflow feeding line system (5), said connection / disconnection unit (6) enabling switching connection of the inflow feeding line system (5) from the spinning system (3) to a recycling system or to waste (7), and vice versa.

Description

[0001] A FIBER SPINNING METHOD

[0002] Field of the invention

[0003] The present invention relates to a fiber spinning method.

[0004] Technical Background

[0005] There exist different types of fiber forming and fiber spinning processes. As an example, in WO2020 / 171767 there is disclosed a process for forming a fiber tow, said process involving a wet spinning procedure comprising dissolving cellulose pulp in an alkaline aqueous solvent to form a cellulose spin dope composition, spinning the cellulose spin dope composition in a coagulation bath having a pH of more than 7.0, preferably a pH of at least 10, to produce a fiber tow, and passing the produced fiber tow through a sequence of consecutive stretching and washing steps in which the fiber tow is washed with washing liquid having gradually lower alkalinity, preferably by a counter-current flow washing procedure.

[0006] One aim of the present invention is to provide a fiber spinning method which comprises one or more steps to optimize the fiber spinning method. Summary of the invention

[0007] According to one aspect of the present invention, the stated purpose above is achieved by a method intended for fiber spinning, said method comprising flushing a spinning head with a liquid flush solvent before starting a fiber spinning procedure.

[0008] Brief description of the drawings

[0009] In fig. 1 there is shown a schematic view of one embodiment of the method according to the present invention.

[0010] In fig. 2 there is shown a schematic view of one embodiment of the system according to the present invention.

[0011] Embodiments of the invention

[0012] Below embodiments of the present invention are provided.

[0013] According to one aspect, the present invention provides a method comprising cleaning out a spinning head by flushing it with a liquid flush solvent subsequent to a fiber spinning procedure. It should be noted that the present invention is directed to a method in which flushing of a spinning head with a liquid flush solvent is performed before starting a fiber spinning procedure and / or flushing of a spinning head with a liquid flush solvent is performed subsequent to a fiber spinning procedure.

[0014] Moreover, in relation to the present invention, it may be said that the flushing before spinning is important to ensure removal of any remaining dirt, particles or debris. Furthermore, according to the present invention, flushing subsequent to the fiber spinning procedure is relevant to remove possible residues of spinning dope in tubes and pumps. Such remaining spinning dope residues may form gelled material which coats the inner walls and is then difficult to remove in a controlled manner. Then there is an evident risk that such gelled material is released during a spinning procedure and will contaminate the spinning dope used.

[0015] According to yet another embodiment, the liquid flush solvent is a spinning dope solvent, preferably a spinning dope solvent comprising sodium hydroxide, more preferably a spinning dope solvent comprising sodium hydroxide in a concentration range of 5 - 12 wt.%, preferably in a range of 7 -10 wt.%, preferably the liquid flush solvent containing less than 2 wt.%, preferably less than 1 wt.%, of the fiber spinning component, such as dissolved cellulose. The present invention is especially directed to the use of cold alkali, such as cold sodium hydroxide, for fiber spinning. In this regard it may be mentioned that a typical spinning dope according to the present invention comprises cellulose in a concentration range of 4 - 12 wt.%, such as a range of 5 - 10 wt.%, and sodium hydroxide in a concentration range of 5 - 12 wt.%, preferably 6 - 9 wt.%, more preferably 7 - 8 wt.%, calculated on the total weight of the spinning dope. Other components, such as additives, e.g. zinc oxide may also be present.

[0016] According to the present invention, the expression “liquid flush solvent” may be something other than a spinning dope solvent or a spinning dope. One example is water-based systems. The method may then e.g. involve flushing with water combined with a viscous water-based solution, such as an aqueous solution comprising a cellulose derivative. Moreover, also in such a case a spinning dope solvent and / or a spinning dope may be used also in the flushing procedure according to the present invention. According to one embodiment, the method comprises flushing an inflow feeding line arranged preceding the spinning head when the spinning head is disconnected from said inflow feeding line, preferably by flowing the liquid flush solvent through the inflow feeding line and to a recycling system or to waste, such as to a waste container, then connecting the spinning head to said inflow feeding line and further flushing the spinning head during at least part of the procedure, preferably during the entire procedure of lowering the spinning head into the spin bath, preferably until the spinning head has been completely immersed under the surface of the spin bath, for starting the fiber spinning procedure. Moreover, according to yet another embodiment, a particle filter is arranged along the inflow feeding line and wherein the method comprises flushing the particle filter before connecting the spinning head. Furthermore, according to one embodiment, the method comprises flushing the spinning head with a liquid flush solvent during immersion of the spinning head into the spin bath, then, preferably after the spinning head has been completely immersed under the surface of the spin bath, starting to flow spinning dope into the inflow feeding line and further to the spinning head for replacing the liquid flush solvent when starting the fiber spinning procedure.

[0017] According to yet another embodiment, the method comprises a step of flushing the inflow feeding line with spinning dope, preferably comprising a fiber spinning component, such as cellulose in a concentration range of 4 -12 wt.%, such as a range of 5 - 10 wt.%, and a spinning dope solvent, such as sodium hydroxide in a concentration range of 5 - 12 wt.%, preferably 6 - 9 wt.%, more preferably 7 - 8 wt.%, calculated on the total weight of the spinning dope, subsequent to flushing the inflow feeding line with liquid flush solvent, preferably the step of flushing the inflow feeding line with spinning dope is followed by a new flushing of the inflow feeding line with liquid flush solvent, preferably the spinning head being disconnected from the inflow feeding line during said flushing of the inflow feeding line with spinning dope. As seen in the embodiment shown in fig. 1 , the liquid flush solvent suitably is a so-called spinning dope solvent.

[0018] In relation to the above it should be noted that a "liquid flush solvent” according to the present invention may be any type of solvent which enables to flush out debris, dirt, particles, fouling or the like from the spinning head, and possibly also parts connected to the spinning head. This means that a liquid flush solvent which is similar to the subsequently used spinning dope may also be used according to the present invention.

[0019] According to yet another embodiment, the method comprises, subsequent to said step of

[0020] - flushing the spinning head with a liquid flush solvent;

[0021] - starting the fiber spinning procedure by spinning a spinning dope in a spin bath having a pH of more than 7.0, preferably a pH of at least 10, to produce a fiber tow; and

[0022] preferably passing the produced fiber tow through multiple steps comprising stretching and washing,

[0023] preferably the method also comprises drying and crimping of the fiber tow after said multiple steps comprising stretching and washing, more preferably the method also comprises a final cutting step where the fiber tow is cut into staple fibers.

[0024] In relation to what has been disclosed above it should be noted that the present invention is also directed to use of a method as defined above.

[0025] According to one embodiment, the present invention is directed to use of a method intended for fiber spinning, said method comprising flushing a spinning head with a liquid flush solvent before starting a fiber spinning procedure. Further embodiments for this direction are provided above.

[0026] According to yet another embodiment, there is provided use, in a fiber spinning process, of a method comprising cleaning out a spinning head by flushing it with a liquid flush solvent subsequent to a fiber spinning procedure, for removal of possible residues of spinning dope in at least the spinning head. According to one embodiment, the liquid flush solvent is a spinning dope solvent, preferably a spinning dope solvent comprising sodium hydroxide, more preferably a spinning dope solvent comprising sodium hydroxide in a concentration range of 5 - 12 wt.%, preferably in a range of 7 - 10 wt.%, preferably the liquid flush solvent containing less than 2 wt.%, preferably less than 1 wt.%, of the fiber spinning component, such as dissolved cellulose. Moreover, according to yet another embodiment, the method comprises flushing an inflow feeding line arranged preceding the spinning head when the spinning head is disconnected from said inflow feeding line, preferably by flowing the liquid flush solvent through the inflow feeding line and to a recycling system or to waste, such as to a waste container, then connecting the spinning head to said inflow feeding line.

[0027] The present invention also refers to a system intended for fiber spinning, said system comprising

[0028] - a supply system, such as a tank, intended for liquid flush solvent, preferably spinning dope solvent, more preferably a spinning dope solvent comprising sodium hydroxide, most preferably a spinning dope solvent comprising sodium hydroxide in a concentration range of 5 - 12 wt.%, or even 7 - 10 wt.%; preferably the liquid flush solvent containing less than 2 wt.%, preferably less than 1 wt.%, of the fiber spinning component, such as dissolved cellulose,

[0029] - a spinning system with a spinning head;

[0030] - an inflow feeding line system for supplying liquid to the spinning system comprising the spinning head;

[0031] said spinning system also comprising a connection I disconnection unit, preferably a quick connection unit, at an end position of the inflow feeding line system, said connection I disconnection unit enabling switching connection of the inflow feeding line system from the spinning system to a recycling system or to waste, and vice versa.

[0032] According to one embodiment, the system comprises a 3-way valve arrangement, such as a 3-way valve, being connected to the tank intended for liquid flush solvent and a spinning dope supply line intended for spinning dope, preferably comprising a fiber spinning component, such as cellulose in a concentration range of 4 - 12 wt.%, such as a range of 5 - 10 wt.%, and a spinning dope solvent, such as sodium hydroxide in a concentration range of 5 - 12 wt.%, preferably 6 - 9 wt.%, more preferably 7 - 8 wt.%, calculated on the total weight of the spinning dope, the 3-way valve arrangement being arranged for supplying either liquid flush solvent or spinning dope to an inflow feeding line being connectable via said connection / disconnection unit to the spinning head, preferably the system further comprising a pump arranged for pumping liquid flush solvent from the tank to the inflow feeding line. In relation to the above it should be noted that alternatives are possible according to the present invention. For instance, several 2-way valves may be used instead. The preferred alternative according to the present invention is an arrangement providing a 3-way valve effect. Moreover, by using a 3-way valve, the spinning procedure according to the present invention may be automated without direct involvement from operators when handling the spinning head. This automated operation may also be accomplished by implementing multiple 2-way valves, however using a 3-way valve may be somewhat more efficient in this regard.

[0033] Moreover, according to one embodiment, the system is arranged for enabling flushing a spinning head with the liquid flush solvent before starting a fiber spinning procedure.

[0034] Furthermore, according to one embodiment, the system is arranged for enabling cleaning out a spinning head by flushing it with the liquid flush solvent subsequently to a fiber spinning procedure.

[0035] Moreover, according to yet another embodiment, the system comprises a particle filter along the inflow feeding line system, preferably in close proximity to the connection I disconnection unit.

[0036] Detailed description of the drawings

[0037] In fig. 1 there is shown a schematic view of one embodiment of the method according to the present invention, for properly preparing a spinning head and an inflow feeding line adapted for supplying spinning dope to the spinning head for a spinning operation. According to this method, in step 1 , there is a first flushing performed, namely a flushing of the tubes and connections of the inflow feeding line with spinning dope solvent. The flushing of the tubes of the inflow feeding line implies a cleaning procedure and thus removal of dirt, particles and / or debris in the tubes. Moreover, it is also relevant not to connect different parts of the system according to the present invention before full flushing is ensured. As an example, suitably the spinning head is not connected to the flushing line when performing step 1. Moreover, suitably a pump arranged along the inflow feeding line system is used for enabling the flushing of the tubes and connections. In a step 2, a second flushing of the inflow feeding line is performed, in this case with spinning dope. Again, the pump is suitably used to enable the flushing of the system. The higher viscosity of the spinning dope may help to remove particles / dirt / debris which did not detach during the spinning dope solvent flushing of step 1. Also in this step 2, suitably the spinning head is disconnected to avoid that any removed dirt reaches the spinning head.

[0038] In a subsequent step 3, a third flushing of the inflow feeding line with spinning dope solvent to flush out the spinning dope used in step 2 is performed. Also in this step 3, suitably the spinning head is disconnected to avoid that any removed dirt reaches the spinning head.

[0039] Then, in a step 4 there is performed a flushing of the spinning head being connected to the inflow feeding line to remove any microscale dirt particles that may still remain. Spinning dope solvent is used. It may be mentioned that this step may be regarded more as a filling step, as in an optimal situation no dirt particles remain inside of the inflow feeding line. Then the spinning procedure may be initiated by lowering down the spinning head into the spin bath while the flushing with spinning dope solvent is continued.

[0040] In step 5 spinning is started when the spinning head is immersed fully into the spin bath. Spinning dope slowly replaces the spinning dope solvent in the spinning head. It should be noted that the method according to the present invention brings about the advantage that the timing of when to start the spinning and spinning dope flow is not crucial. As the spinning head contains spinning dope solvent, it is possible according to the present invention to start the procedure of supplying spinning dope when the spinning head is at different positions, immersed or not into the spin bath.

[0041] In fig. 2 there is shown one embodiment of a system 1 according to the present invention. The system 1 comprises a supply system 2, such as a tank, intended for liquid flush solvent, a spinning system 3 with a spinning head 4, and an inflow feeding line system 5 for supplying liquid to the spinning system 3 comprising the spinning head 4, wherein the spinning system 3 also comprises a connection I disconnection unit 6 at an end position of the inflow feeding line system 5, said connection I disconnection unit 6 enabling switching connection of the inflow feeding line system 5 from the spinning system 3 to waste 7, and vice versa. In this case the system 1 comprises a 3-way valve arrangement 8, such as a 3-way valve, being connected to the supply system 2 intended for liquid flush solvent and to a spinning dope supply line 12 intended for spinning dope, the 3-way valve arrangement 8 being arranged for supplying either liquid flush solvent or spinning dope to the inflow feeding line 9. The inflow feeding line system 5 comprises the spinning dope supply line 12, the connection I disconnection unit 6 and the inflow feeding line 9. Moreover, according to this embodiment, the system 1 further comprises a pump 10 arranged for pumping liquid flush solvent from the supply system 2, in this case a tank, to the inflow feeding line 9. Furthermore, according to this embodiment, the system 1 also comprises a particle filter 11 provided along the inflow feeding line system 5, preferably in close proximity to the connection I disconnection unit 6. This implies that in this specific case, the pump 10 and the particle filter 11 are provided as part and along the inflow feeding line system 5.

Claims

Claims1. A method intended for fiber spinning, said method comprising flushing a spinning head with a liquid flush solvent before starting a fiber spinning procedure.

2. A method intended for fiber spinning, said method comprising cleaning out a spinning head by flushing it with a liquid flush solvent subsequent to a fiber spinning procedure.

3. The method according to claim 1 or 2, wherein the liquid flush solvent is a spinning dope solvent, preferably a spinning dope solvent comprising sodium hydroxide, more preferably a spinning dope solvent comprising sodium hydroxide in a concentration range of 5 - 12 wt.%, preferably in a range of 7 - 10 wt.%, preferably the liquid flush solvent containing less than 2 wt.%, preferably less than 1 wt.%, of the fiber spinning component, such as dissolved cellulose.

4. The method according to any of claims 1-3, wherein the method comprises flushing an inflow feeding line arranged preceding the spinning head when the spinning head is disconnected from said inflow feeding line, preferably by flowing the liquid flush solvent through the inflow feeding line and to a recycling system or to waste, such as to a waste container, then connecting the spinning head to said inflow feeding line and further flushing the spinning head during at least part of the procedure, preferably during the entire procedure, of lowering the spinning head into the spin bath, preferably until the spinning head has been completely immersed under the surface of the spin bath, for starting the fiber spinning procedure.

5. The method according to claim 4, wherein a particle filter is arranged along the inflow feeding line and wherein the method comprises flushing the particle filter before connecting the spinning head to the inflow feeding line.

6. The method according to claim 4 or 5, wherein the method comprises flushing the spinning head with a liquid flush solvent during immersion of the spinning head into the spin bath, then, preferably after the spinning head has been completely immersed under the surface of the spin bath, starting to flow spinning dope into the inflow feeding line and further to the spinning head for replacing the liquid flush solvent when starting the fiber spinning procedure.

7. The method according to any of claims 4-6, wherein the method comprises a step of flushing the inflow feeding line with spinning dope, preferably comprising a fiber spinning component, such as cellulose in a concentration range of 4 - 12 wt.%, such as a range of 5 - 10 wt.%, and a spinning dope solvent, such as sodium hydroxide in a concentration range of 5 - 12 wt.%, preferably 6 - 9 wt.%, more preferably 7 - 8 wt.%, calculated on the total weight of the spinning dope, subsequent to flushing the inflow feeding line with liquid flush solvent, preferably the step of flushing the inflow feeding line with spinning dope is followed by a new flushing of the inflow feeding line with liquid flush solvent, preferably the spinning head being disconnected from the inflow feeding line during said flushing of the inflow feeding line with spinning dope.

8. The method according to any of claims 1-7, wherein the method comprises, subsequent to said step of flushing the spinning head with a liquid flush solvent;- starting the fiber spinning procedure by spinning a spinning dope in a spin bath having a pH of more than 7.0, preferably a pH of at least 10, to produce a fiber tow; andpreferably passing the produced fiber tow through multiple steps comprising stretching and washing,preferably the method also comprises drying and crimping of the fiber tow after said multiple steps comprising stretching and washing, more preferably the method also comprises a final cutting step where the fiber tow is cut into staple fibers.

9. A system (1) intended for fiber spinning, said system comprising- a supply system (2), such as a tank, intended for liquid flush solvent, preferably spinning dope solvent, more preferably a spinning dope solvent comprising sodium hydroxide, most preferably a spinning dope solvent comprising sodium hydroxide in a concentration range of 5 - 12 wt.%, or even 7 - 10 wt.%; preferably the liquid flush solvent containing less than 2 wt.%, preferably less than 1 wt.%, of the fiber spinning component, such as dissolved cellulose,- a spinning system (3) with a spinning head (4);- an inflow feeding line system (5) for supplying liquid to the spinning system (3) comprising the spinning head (4), said spinning system (3) also comprising a connection I disconnection unit (6), preferably a quick connection unit, at an end position of the inflow feeding line system (5), said connection I disconnection unit (6) enabling switching connection of the inflow feeding line system (5) from the spinning system (3) to a recycling system or to waste (7), and vice versa.

10. The system (1) according to claim 9, wherein the system (1) comprises a 3-way valve arrangement (8), such as a 3-way valve, being connected to the supply system (2), such as a tank, intended for liquid flush solvent and to a spinning dope supply line (12) intended for spinning dope, preferably comprising a fiber spinning component, such as cellulose in a concentration range of 4 - 12 wt.%, such as a range of 5 - 10 wt.%, and a spinning dope solvent, such as sodium hydroxide in a concentration range of 5 - 12 wt.%, preferably 6 - 9 wt.%, more preferably 7 - 8 wt.%, calculated on the total weight of the spinning dope, the 3-way valve arrangement (8) being arranged for supplying either liquid flush solvent or spinning dope to an inflow feeding line (9) being connectable via said connection / disconnection unit (6) to the spinning head (4), preferably the system (1) further comprises a pump (10) arranged for pumping liquid flush solvent from the supply system (2), such as a tank, to the inflow feeding line (9).

11. The system (1 ) according to any of claims 9-10, wherein the system (1 ) is arranged for enabling flushing a spinning head (4) with the liquid flush solvent before starting a fiber spinning procedure.

12. The system (1 ) according to any of claims 9-11 , wherein the system (1 ) is arranged for enabling cleaning out a spinning head (4) by flushing it with the liquid flush solvent subsequently to a fiber spinning procedure.

13. The system (1) according to any of claims 9-12, wherein the system (1) comprises a particle filter (11 ) along the inflow feeding line system (5), preferably in close proximity to the connection I disconnection unit (6).

14. Use, in a fiber spinning process, of a method comprising cleaning out a spinning head by flushing it with a liquid flush solvent subsequent to a fiber spinning procedure, for removal of possible residues of spinning dope in at least the spinning head.

15. The use according to claim 14, wherein the liquid flush solvent is a spinning dope solvent, preferably a spinning dope solvent comprising sodium hydroxide, more preferably a spinning dope solvent comprising sodium hydroxide in a concentration range of 5 - 12 wt.%, preferably in a range of 7 - 10 wt.%, preferably the liquid flush solvent containing less than 2 wt.%, preferably less than 1 wt.%, of the fiber spinning component, such as dissolved cellulose.

16. The use according to claim 14 or 15, wherein the method comprises flushing an inflow feeding line arranged preceding the spinning head when the spinning head is disconnected from said inflow feeding line, preferably by flowing the liquid flush solvent through the inflow feeding line and to a recycling system or to waste, such as to a waste container, then connecting the spinning head to said inflow feeding line.

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