Method and system for producing spinnable bast fibres or a bast thread

Abstract

The invention relates to a method for producing spinnable bast fibres and a method for producing a bast thread (10), wherein, in a first step, bast fibres (1) are provided as bast fibre bundles (2), and, in a second step, the bast fibre bundles (2) are processed in a batch washer system (4). The invention also relates to a system.

Description

[0001] Process and plant for producing spinnable bast fibres or a bast thread

[0002] The present invention relates to a method for producing spinnable bast fibers, a method for producing a bast thread and a plant for producing spinnable bast fibers or a bast thread, wherein bast fibers are provided as bast fiber bundles.

[0003] Long-staple bast fibers are gaining increasing attention for the production of fiber webs and spinnable bast fibers. Bast fibers are typically obtained from flax, linen, hemp, or even nettles. These plants are highly sustainable as a raw material source because they place few demands on their habitat.

[0004] After harvesting, the bast fibers are typically delivered in the form of bast fiber bundles. Before the bast fibers are processed, impurities such as soil, plant residues, and the like must be removed. Furthermore, for further processing of the bast fibers as bast threads and later as fiber webs, the fibers, which are typically up to 1200 mm long, must be shortened.

[0005] It is known from the prior art to clean the bast fiber bundles by combing. In this process, cylinders with needles arranged on their surface rotate and pass the needles through the bast fiber bundles. As they pass, the needles remove impurities from the bast fiber bundles, but also cause the bast fibers to break and tear. Combing is repeated until the desired purity or fiber length is achieved. In particular, the removal of the fiber impurities surrounding the individual fibers, which cause the individual bast fibers to stick together, leads to damage to the bast fibers. Often, however, both are not achieved simultaneously, so that sufficient cleaning of the bast fiber bundles leads to bast fibers that are too short or that impurities, particularly the fiber bast surrounding the bast fibers, are still left when combing is stopped when the desired fiber length is reached.

[0006] One prior art approach involves placing the bast fiber bundles in a pot-like container during or after combing, where they are exposed to fluids, such as water, and cleaned. This allows combing to be interrupted at the desired fiber length, and the desired purity can be achieved through cleaning. The disadvantage of this approach is that the cleaning process is highly discontinuous. Cleaning the bast fiber bundles, especially the removal of the fiber bast, inline with continuous further processing of the bast fibers is not possible.

[0007] It is therefore an object of the present invention to provide a method for producing spinnable bast fibers, a method for producing a bast thread and a plant for producing spinnable fibers or a bast thread, which overcome the aforementioned disadvantage of the prior art, reduce breaks in the supply of cleaned bast fibers and ensure improved continuity in the production of the bast thread.

[0008] This problem is solved by the features of claim 1, claim 2 and claim 10.

[0009] Spinnable in the sense of the present invention means that the bast fibers can be spun into bast threads, which can be spun into cotton threads like cotton, and wherein the bast threads can be further processed like cotton threads. According to the invention, bast fibers are provided as bast fiber bundles in a first step. Subsequently, the bast fiber bundles are processed in a second step in a cyclic washing system. By processing the bast fiber bundles with a cyclic washing system, a very uniform inflow of bast fibers for further steps such as drying and oriented deposition is possible. The highly discontinuous provision of processed bast fibers with long waiting times before further processing of the bast fibers after the second step, as is known from the prior art, can thus be significantly improved, which significantly increases the efficiency of the manufacturing process.

[0010] A cyclic washing system within the meaning of the present invention includes cyclic washing systems in the narrower sense, such as those used in industrial textile laundering. However, cyclic washing systems within the meaning of the present invention also include machines that continuously transport and clean bast fiber bundles from an input side, where the bast fiber bundles are fed into the machine, to an output side, where the bast fibers are discharged from the machine. For example, it is conceivable that a pulping drum, particularly for recycling cardboard, could be understood as a cyclic washing system within the meaning of the present invention.

[0011] A cyclic washing system in the narrower sense has several washing drums that can rotate synchronously with one another about a common axis of rotation. The bast fiber bundles are fed into a first washing drum of the cyclic washing system. By oscillating the first washing drum about the axis of rotation and subjecting the bast fiber bundles in the first washing drum to a fluid such as water, the bast fiber bundles are wetted. Preferably, the bast fiber bundles are transported by a partial or complete rotation of the washing drums into a second washing drum of the cyclic washing system, which is arranged adjacent to the first washing drum. For this purpose, a chute-like guide track is preferably provided which connects the first washing drum to the second washing drum.If the first washing drum swings far enough that the bast fiber bundles are gripped by the guide track or that the bast fiber bundles are deposited on the guide track (e.g. with a complete rotation), the bast fiber bundles move via the guide track into the second washing drum. It is conceivable that the second washing drum swings synchronously with the first washing drum and synchronously with all other washing drums in the intermittent washing system. The bast fiber bundles are gradually transported from washing drum to washing drum, and in the process the contaminants to be removed, in particular the fiber bast surrounding the bast fibers, enter the surrounding fluid, the so-called wash liquor. The contaminants separated from the fiber bundles and bast fibers can then be removed from the intermittent washing system, for example with the liquor, and the bast fibers can be cleaned.Finally, the separated bast fibers can be discharged from the intermittent washing system at the last washing drum of the intermittent washing system. It is conceivable that additives are added to the water with which the bast fiber bundles are exposed in the washing drum(s), for example to clean the bast fiber bundles and / or to break down the fiber bast. It is also conceivable that the water is tempered, in particular heated. It is conceivable that the bast fiber bundles or the bast fibers are exposed to water in all washing drums. However, it is also conceivable that the bast fiber bundles or the bast fibers are not exposed to water in all washing drums. It is also conceivable that the bast fiber bundles or the bast fibers are not exposed to any liquid in some washing drums or that they are exposed to a liquid other than water.

[0012] For the production of a bast thread according to the invention, it is provided that in a third step the bast fibers of the processed bast fiber bundles are spun to form the bast thread, wherein the processed bast fibers (1) are preferably fed continuously to the third step

[0013] Furthermore, a method for producing a fiber web is disclosed, wherein spinnable bast fibers are provided according to a method according to claim 1 and laid to form the fiber web, preferably a nonwoven fabric web. The laying of the bast fibers to form the fiber web is preferably carried out dry. For example, it is conceivable that the bast fibers are laid using an airlaid process. However, it is also conceivable that the bast fibers are wetlaid. The bast fibers can also be laid as a carded layer or as pulp. Advantageous embodiments and further developments of the invention can be found in the dependent claims and the description with reference to the drawings.

[0014] According to a preferred embodiment of the present invention, it is provided that in the second step, impurities in the bast fiber bundles and / or fiber accompanying substances in the bast fiber bundles, in particular fiber bast and / or petals and / or seeds and / or inflorescences and / or roots, are removed. This enables reliable further processing of the bast fibers into high-quality bast fibers, bast threads and fiber webs. By using the indexing washing system, the cleanliness is increased from washing drum to washing drum as the bast fiber bundles pass through. In addition to cleaning by exposing the bast fiber bundles to water, effective removal of impurities and fiber accompanying substances can be achieved by using, for example, surfactants and by mechanical processing within the washing drums.For mechanical processing, for example, impact surfaces can be provided in the washing drums, which collide with the bast fiber bundles as the drums vibrate. This allows colloidal contaminants, in particular, to be loosened and carried away with the water.

[0015] According to a further preferred embodiment of the present invention, it is provided that in the second step the bast fibers of the bast fiber bundles are shortened for further processing in the third step. The bast fibers are preferably shortened to a fiber length of 1 mm to 50 mm and particularly preferably to a fiber length of 5 mm to 25 mm. In particular, it is provided that the bast fibers are shortened in the intermittent washing system. The bast fibers of the bast fiber bundles are typically too long to be spun into a bast thread or laid into a nonwoven fabric web. The mechanical processing of the bast fiber bundles in the intermittent washing system makes it possible to break the bast fibers into small pieces in a targeted manner. The fiber length can be determined by programming the intermittent washing system.The combination of the amplitude and frequency of the washing drum vibrations and the passage time of the bast fibers through the intermittent washing system is important, as is the amount of water added, which can influence the degree of cleaning and the achieved fiber length. With fiber lengths from 1 mm to 50 mm, and especially from 5 mm to 25 mm, the bast fibers can be processed effectively and easily.

[0016] In particular, it is envisaged that the bast fibers of the bast fiber bundles are degumming in the second step. Experts also refer to this as degumming, i.e. the removal of lignin and pigments from the bast fiber bundle. This separates the bast fibers from the bast fiber bundle, so that the bast fibers are cotonized. It is conceivable that sodium carbonate and / or caustic soda are added to the bast fiber bundles in the intermittent washing system for degumming. Preferably, the bast fibers are degumming in a sustainable manner without causing environmental pollution, by enzymatic degradation of the fiber bast instead of the aforementioned chemicals. It is conceivable that enzymes are added to the bast fiber bundles in the intermittent washing system for this purpose.

[0017] It is also conceivable that the bast fibres are bleached in the intermittent washing system, for example by adding sodium chloride and / or hydrogen peroxide to the debasted bast fibres in the intermittent washing system.

[0018] According to a further preferred embodiment of the present invention, the bast fiber bundles are delivered for preparation. No cleaning of the bast fiber bundles takes place between delivery and the second step. Thus, the bast fiber bundles do not undergo discontinuous cleaning in a pot-like container. This enables a very efficient production of the bast fibers, the bast thread, and the fiber web.

[0019] To increase cleaning performance in the second step, it is preferably provided that the bast fiber bundles are mechanically pre-cleaned in a pre-treatment room connected to the intermittent washing system before passing through the intermittent washing system. In particular, it is provided that an air stream is used for this purpose. This advantageously ensures that less contaminants are introduced into the intermittent washing system. Coarse contaminants can be removed before passing through the intermittent washing system, but directly at the intermittent washing system and, in particular, inline. Pre-cleaning using the air stream protects the bast fibers, so that despite pre-cleaning, the desired fiber length can be achieved with the set programming of the intermittent washing system.

[0020] In particular, it is envisaged that the bast fibers are fed continuously to the third step, which results in a significant increase in the efficiency of the manufacturing process. The efficiency of the manufacturing process is preferably further increased by carrying out the second step inline with the third step.

[0021] It is disclosed that the bast fibers are continuously fed into the laying of the fiber web, which results in a significant increase in the efficiency of the manufacturing process. The efficiency of the manufacturing process is preferably further increased by performing the second step inline with the laying of the fiber web.

[0022] A further object for achieving the initially stated problem is a system for producing a bast thread according to the method according to the invention. The system comprises a cyclic washing system for processing bast fiber bundles and a unit for spinning the bast fibers, arranged downstream of the cyclic washing system in the processing direction. Preferably, the cyclic washing system is arranged inline with the unit for spinning the bast fibers. This allows for a continuous transfer of bast fibers to the unit for spinning the bast fibers.

[0023] Furthermore, a system for producing a fiber web according to the method for producing a fiber web disclosed above is disclosed. The system for producing a fiber web comprises a cyclic washing system for processing bast fiber bundles and a unit for laying the fiber web, arranged downstream of the cyclic washing system in the processing direction. Preferably, the cyclic washing system is arranged inline with the unit for laying the fiber web. This makes it possible for bast fibers to be continuously transferred to the unit for laying the fiber web. In particular, it is provided that a pretreatment chamber is arranged upstream of the cyclic washing system in the processing direction, which pretreatment chamber is intended to mechanically pre-clean the bast fiber bundles before they pass through the cyclic washing system. It is conceivable that the pretreatment chamber is a washing drum of the cyclic washing system, in which the bast fiber bundles are not exposed to water.It is also conceivable that the pre-treatment room is a separate unit in the processing direction upstream of the intermittent washing system, which is connected to the intermittent washing system, for example via a conveyor belt.

[0024] Preferably, a dewatering unit for dewatering the bast fibers is provided downstream of the cyclic washing system and upstream of the unit for spinning the bast fibers. In particular, the dewatering unit comprises a press and / or a centrifuge and / or a screen belt with suction boxes arranged underneath.

[0025] In particular, it is envisaged that, in the processing direction, a drying unit for drying the bast fibers is provided downstream of the dewatering unit and upstream of the unit for spinning the bast fibers. It is conceivable that the bast fibers are heated for drying so that water evaporates from the bast fibers.

[0026] The features, details, and advantages previously mentioned in connection with the method according to the invention also relate to the system according to the invention. Furthermore, it is disclosed that the features, details, and advantages mentioned with the method according to the invention also relate to the disclosed method for producing a fiber web. Finally, it is disclosed that the features, details, and advantages disclosed in connection with the system according to the invention also relate to the disclosed system for producing a fiber web.

[0027] Further details, features, and advantages of the invention will become apparent from the drawings and the following description of preferred embodiments with reference to the drawings. The drawings merely illustrate exemplary embodiments of the invention, which do not limit the inventive concept. They show:

[0028] Fig. 1 : a schematic view of a system according to an exemplary

[0029] Embodiment of the present invention for carrying out a method according to an exemplary embodiment of the present invention and

[0030] Fig. 2: a schematic view of a plant for producing a fiber web according to an exemplary embodiment of the above disclosure for carrying out a method for producing a fiber web disclosed above.

[0031] Figure 1 shows a system 100 according to exemplary embodiments of the present invention for carrying out a method according to an exemplary embodiment of the present invention. The system 100 is intended for producing a bast thread 10 from spinnable bast fibers 1.

[0032] To produce the bast thread 10, in a first step I, bast fiber bundles 2 are delivered directly from the field and fed, for example, via a conveyor belt (not designated), into a pretreatment room 3. A second step II of producing the fiber web 10 begins in the preparation room 3. The bast fiber bundles 2 are mechanically pre-cleaned. For this purpose, an air stream inside the pretreatment room 3 captures coarse dirt particles and foreign matter and removes them from the fiber bundles 2. This pre-cleaning serves to reduce the amount of contamination introduced into subsequent cleaning steps of the second step II.

[0033] After passing through the pre-treatment room 3, the pre-cleaned bast fiber bundles 2 reach a cyclic washing system 4. The cyclic washing system 4 has a plurality of washing drums 4.1, 4.2, 4.3, 4.4, 4.5, which are arranged adjacent to one another along the processing direction Z. The washing drums 4.1, ..., 4.5 can rotate synchronously or independently of one another about a rotation axis D. First, the bast fiber bundles 2 reach a first washing drum 4.1 of the cyclic washing system 4. The first washing drum 4.1 oscillates about the rotation axis D. Inside the first washing drum 4.1, the bast fiber bundles 2 are subjected to water. In addition, as the first washing drum 4.1 oscillates, the bast fiber bundles 2 strike stop surfaces 7 inside the first washing drum 4.1. This removes impurities from the bast fiber bundles 2 and fiber accompanying substances from the bast fiber bundles 2, such as fiber bast, petals, seeds, inflorescences or roots.The mechanical processing further shortens the bast fibers 1 of the bast fiber bundles 2. Depending on the programming of the intermittent washing system 4, the washing drums 4.1, ..., 4.5 rotate such that the bast fiber bundles 2 or the bast fibers 1 are transported by a guide track 8 from the first washing drum 4.1 along the processing direction Z into a second washing drum 4.2. In the second washing drum 4.2, the bast fiber bundles 2 or the bast fibers 1 are also processed by oscillating the second washing drum 4.2 and, at the appropriate time, are transported further along the processing direction Z into the next washing drum 4.3 of the intermittent washing system 4. In this way, the bast fibers 1 pass through all washing drums 4.1, ..., 4.5 of the entire intermittent washing system 4. It is conceivable that the bast fiber bundles 2 are debasted in the intermittent washing system 4. For this purpose, it can be provided, for example, that in one of the washing drums 4.1, ..., 4.5 Instead of or in addition to water, a chemical for debasting, for example, aqueous solutions of sodium carbonate or sodium hydroxide, or a correspondingly suitable enzymatic solution, is used. It is also conceivable that the bast fibers 1 are bleached in one of the washing drums 4.1, ..., 4.5, and that, instead of or in addition to water, oxidative or reductive bleaching agents such as sodium chloride, hydrogen peroxide, or sodium dithionite are used for this purpose.

[0034] The intermittent washing system 4 can be adjusted to achieve a desired cleaning performance of the bast fiber bundles 2, a desired degumming, and a desired shortening of the fiber length of the bast fibers 1. For this purpose, appropriate vibration frequencies, vibration amplitudes, water levels in the washing drums 4.1, ..., 4.5, or water temperatures are adjusted.

[0035] After passing through the intermittent washing system 4, the bast fibers 1 are fed to a dewatering unit 5. In the dewatering unit 5.1, the bast fibers 1 are mechanically dewatered. This can be done, for example, by pressing, centrifuging, or by suction in the dewatering unit 5.1.

[0036] In processing direction Z, the dewatering unit 5.1 is followed by the drying unit 5.2. In the drying unit 5.2, the dewatered bast fibers 1 are dried by heating. This heating ensures that adhering surface water from the bast fibers 1, which cannot be removed mechanically, evaporates.

[0037] This is followed by a unit 6 for spinning the bast fibers 1 into bast thread 10, in which the bast thread 10 is spun in a third step III. The use of the cyclic washing system 4 makes it possible to continuously transfer cleaned and shortened bast fibers 1 to the unit 6 for spinning the bast fibers 1 for further processing without major interruptions. Unlike what is known from the prior art, the cleaning of the bast fiber bundles 2, the degumming of the bast fiber bundles 2 into bast fibers 1, and the shortening of the bast fibers 1 to a length suitable for further processing all take place inline. This makes the production process for the fiber web 10 significantly more efficient.

[0038] Figure 2 shows a system 101 for producing a fiber web 11, as disclosed above, with which a method for producing a fiber web 11 is carried out, as disclosed above. The system 101 for producing the fiber web 11 corresponds to the system 100 shown in Fig. 1 except for the feature that, instead of a unit for spinning the bast fibers, a unit 9 for laying the fiber web 11 is provided in a further third step IIIa.

[0039] The unit 9 for laying the fiber web 11 can be designed to lay the fiber web 10 dry, for example, using an airlaid process. However, it is also conceivable that the unit 9 for laying the fiber web 11 is designed to lay the fiber web 11 wet. Reference symbols:

[0040] 1 Bast fibers

[0041] 2 bast fiber bundles

[0042] 3 Pre-treatment room

[0043] 4 cycle washing system

[0044] 4.1 first washing drum

[0045] 4.2 second washing drum

[0046] 4.3 Washing drum

[0047] 4.4 Washing drum

[0048] 4.5 Washing drum

[0049] 5.1 Drainage unit

[0050] 5.2 Drying unit

[0051] 6 Unit for spinning the bast fibers

[0052] 7 Impact surface

[0053] 8 Guideway

[0054] 9 Unit for laying the fiber web

[0055] 10 raffia threads

[0056] 11 Fibrous tract

[0057] 100 system

[0058] 101 Appendix

[0059] D rotation axis

[0060] Z processing direction

[0061] I first step

[0062] II second step

[0063] III third step

[0064] Illa further third step

Claims

Patent claims:

1. Method for producing spinnable bast fibers (1), wherein in a first step bast fibers (1) are provided as bast fiber bundles (2), in a second step the bast fiber bundles (2) are processed in a cyclic washing system (4).

2. A method for producing a bast thread (10), wherein spinnable bast fibers (1) are provided according to a method according to claim 1, wherein in a third step the spinnable bast fibers (1) of the processed bast fiber bundles (2) are spun to form the bast thread (10), wherein the processed spinnable bast fibers (1) are preferably fed continuously to the third step.

3. Method according to claim 1 or 2, characterized in that in the second step, impurities of the bast fiber bundles (2) and / or fiber accompanying substances of the bast fiber bundles (2), in particular fiber bast and / or petals and / or seeds and / or inflorescences and / or roots are removed.

4. Method according to one of the preceding claims, characterized in that in the second step the bast fibers (1) of the bast fiber bundles (2) are shortened for further processing in the third step, wherein the bast fibers (1) are preferably shortened to a fiber length of 1 mm to 50 mm and particularly preferably to a fiber length of 5 mm to 25 mm.

5. Method according to one of the preceding claims, characterized in that in the second step the bast fibers (1) of the bast fiber bundles (2) are debasted.

6. Method according to one of the preceding claims, characterized in that the bast fiber bundles (2) are delivered for provision and between the delivery and the second step no cleaning of the bast fibre bundles (2) takes place.

7. Method according to one of the preceding claims, characterized in that the bast fiber bundles (2) are pre-cleaned mechanically, in particular with the aid of an air stream, in a pre-treatment room (3) connected to the cyclic washing system (4) in the second step before passing through the cyclic washing system (4).

8. Method according to one of the preceding claims, characterized in that the bast fibers (1) are mechanically dewatered in a dewatering unit (5.1), in particular by pressing and / or centrifuging, and / or dried in a drying unit (5.2) in the second step after passing through the cyclic washing system (4).

9. Method according to one of the preceding claims, characterized in that the second step is carried out inline with the third step.

10. Plant (100) for producing spinnable fibers (1) and preferably a bast thread (10) according to a method according to one of the preceding claims, wherein the plant (100) has a cyclic washing plant (4) for processing bast fiber bundles (1) and preferably a unit (6) for spinning the bast fibers (1) into the bast thread (10), arranged downstream of the cyclic washing plant (4) in the processing direction (Z).

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