EP1668175B1 - Method for processing natural fiber plants - Google Patents

Abstract

The invention relates to a method for processing natural fiber plants, during which: a) the freshly harvested plants are chopped; b) the chopped product is subsequently subjected to a sieving and/or sifting process whereby separating out fibers from the other plant parts, and; c) subsequently processing the separated out fibers and the remaining fiber/shive mixture separately. The novel method is advantageous in that particularly valuable fiber components can be obtained immediately after harvesting the natural fiber plants. It is also advantageous in that the fibers do not suffer any losses in quality (particularly losses in strength) by the preservation thereof.

Description

The present invention relates to a process for the treatment of natural fiber plants.

For the extraction of fiber from natural plants there are elaborate treatment processes. They all aim to separate the fibers from the shives - the wood components and other plant components - and to recycle both components separately. In the case of common methods, the natural fiber straw must be dried down to storage-stable dry substance contents for this purpose. Drying is generally carried out on the field, whereby the quality of the natural fiber straw depends heavily on the weather.

A method in which this weather dependence is excluded, is in the DE 197 560 46 A1 disclosed. In this wet process hemp is chopped at the harvest as a whole plant and then conserved. The separation of the adhesive bond between fibers and shives may, for example, take place in a disk mill, in which process the entire fiberized plant material is used for the production of products. However, separation of high quality fibers prior to further processing is not disclosed.

In DE 198 13 397 A1 a method is described in which the fiber plants are either cut in the harvest as in the conventional fiber crop with field drying and possibly roasting and pre-dissolved for faster field drying by hitting, kinking and squeezing. Due to the thus slightly accelerated field drying, the harvesting risk can be reduced. The pre-resolution However, it must be done carefully and without separating the fibers from the wood components in order to avoid the loss of the shives to the field. In addition, the straw can only be shortened to lengths of more than 300 mm, which otherwise can only be recovered with high losses after drying or with heavy contamination. Subsequently, the dried straw must be recovered and further processed. The disadvantage is that the actual separation (ie the dissolution or Entholzen) of fibers and shives can take place only during further processing, or that alternatively the fiber plants are intensively pre-dissolved and abbreviated only after harvesting with field drying and possibly roasting. Due to the strong mechanical stress caused by hitting, kinking and squeezing, this downstream prerelease can be largely separated from fibers and shives. The disadvantage is that the known harvesting risk is completely retained.

Furthermore, from the DE 198 41 092 A1 a method and an apparatus for processing fiber plant material is known in which a part of the fibers are already separated immediately after crushing. However, in this case the fiber plant material is pressed and thereby broken and then cut into sections of desired length. In this case, a part of the fiber material can be separated. In this method, it is necessary to introduce the plant material in the dry state in the crushing device. Damp, so freshly harvested plant stems would lead to a sticking of the internal parts of the device. This device is merely a conventional tobacco cutter. These tobacco cutters are designed to crush already dried and fermented tobacco.

In the WO 00/20667 describes a method that can be harvested harvested fresh stalks. In the process, the stems are first broken up lengthwise and then divided into smaller segments. This is done by means of rollers. An immediate shredding by shredding is not disclosed.

From the WO 97/45573 A1 Furthermore, a harvesting and processing method for green plant stems is known. In this method, the plant stems are broken up lengthwise and the outer components are separated from the inner ones and then crushed. Thus, for example, joins a debarking process and also the marrow is separated from the plants. Only then can the removal of the valuable fibers from the comminuted material take place at all.

In the two methods just described, there is the disadvantage that the plants in their entirety have to be broken up lengthwise.

The aforementioned methods of the prior art thus have considerable disadvantages.

It is therefore an object of the present invention to overcome the disadvantages of the prior art and to provide an economical process in order to obtain the valuable fibers from harvest-fresh natural fiber plants.

The object is achieved by a method having the features of the main claim. Advantageous embodiments of the method according to the invention are characterized in the subclaims.

1. a) die erntefrischen Pflanzen häckselt und
2. b) das Häckselgut anschließend im erntefrischen Zustand einem Sieb- und/oder Sichtverfahren unterzieht und dadurch Fasern von den anderen Pflanzenbestandteilen abtrennt und
3. c) die abgetrennten Fasern und das verbleibende Restfaser-Schäben-Gemisch getrennt weiterverarbeitet.

The present invention thus provides a process for the treatment of natural fiber plants, wherein

1. (a) chop the freshly harvested plants; and
2. b) then subjects the shredded material in a freshly harvested state to a sieving and / or visual process and thereby separates fibers from the other plant constituents and
3. c) the separated fibers and the remaining fiber-shives mixture further processed separately.

The process according to the invention is particularly advantageous if the process steps a) and b) are carried out immediately after the harvest without a longer intermediate storage time.

It is furthermore particularly advantageous that process steps a) and b) are carried out in separate devices.

It is also advantageous that the separated fibers to high-quality processing products, namely building materials, insulation materials, packaging materials, fiber composites or composites, further processed.

It is also advantageous that the fibers suffer no loss of quality (in particular loss of strength) through the preservation.

It is particularly preferred that the separated fibers are dried prior to further processing.

It is also preferred that the separated fibers are subjected to further cleaning and fiber pulping prior to drying.

It is further preferred according to the invention that the separated fibers are subjected to biological (e.g., enzymatic) and / or chemical treatment prior to drying and further processing. As a result, the fiber quality in particular the fiber fineness is increased

In a further embodiment of the method according to the invention, it is preferred that the residual fiber shives mixture Preserved with or without additives in silos, roasted, plasticized and stored until processing. It is particularly preferred that one carries out the defibration of the stored residual fiber shives mixture without a separate Plastifizierungsprozess by shear stress. It is particularly preferred that the fiberization is carried out by means of twin-screw extruders or disk mills with a grinding gap of preferably 0.3 mm.

It is also preferred that the processing of the digested residual fiber shives mixture to processing products, namely building materials, insulation materials or packaging materials, without prior drying in a wet process.

Also preferred is a process in which the processing of the digested residual fiber shives mixture to processing products, namely building materials, insulation materials, packaging materials, fiber composites or composites, after prior drying in a dry process.

The present invention thus solves the problem of separation of wet fibers from the freshly chopped material. Thus, a new overall method for fiber use was realized.

Surprisingly, it was also found that in contrast to DE 197 56 046 A1 , which was still limited to the processing of hemp alone, the method of the invention can be applied for many other natural fiber plants largely independent of the weather in the harvest time.

• Der Häckselvorgang wird so eingestellt, das eine weitgehende Auflösung der Klebeverbindung zwischen Fasern und Schäben erfolgt.
• Durch das Separieren der hochwertigen Fasern vor der Weiterverarbeitung zum Endprodukt lässt sich eine breitere Palette von Produkten mit höherwertigen Gebrauchseigenschaften herstellen. In diesen Produkten können die spezifischen Stoffeigenschaften der Fasern wie z.B. ihre hohe Festigkeit gezielt ausgenutzt werden. Hierdurch wird eine deutlich höhere Wertschöpfung erzielt.
• Durch das Separieren der Fasern, die üblicherweise Längen von 20 bis 250 mm aufweisen, lässt sich dass verbliebene Restfaser-Schäben-Gemisch störungsfrei und unter reduzierten Energieeinsatz zerfasern.
• Durch das Separieren der Fasern können diese gesondert und aufgrund der günstigeren faserspezifischen Trocknungseigenschaften unter geringerem Energieeinsatz getrocknet werden. Der Energiebedarf für die Trocknung der separierten Fasern liegt bei weniger als 30 % der Kosten für die Trocknung des gesamten Häckselguts.

Essential differences according to the invention are thus:

• The chopping process is set so that there is a substantial dissolution of the adhesive bond between fibers and shives.
• By separating the high-quality fibers before further processing into the final product, a broader range of products with higher-quality performance properties can be produced. In these products, the specific material properties of the fibers, such as their high strength, can be specifically exploited. This results in a significantly higher added value.
• By separating the fibers, which usually have lengths of 20 to 250 mm, the remaining residual fiber-shives mixture can be disrupted without disruption and under reduced energy input.
• By separating the fibers they can be dried separately and due to the more favorable fiber-specific drying properties with lower energy input. The energy requirement for drying the separated fibers is less than 30% of the costs for drying the entire shredded material.

The method according to the invention furthermore has the following advantageous differences in particular DE 198 13 397 A1 on, namely
the material is shredded and disintegrated at harvest time from the freshly harvested stock (ie at a dry matter content of approx. 25 to 40% by mass) with a forage harvester by the working organs of the shredder so that the adhesive bond between fibers and wood components (shives) already largely destroyed here. For subsequent separation of the fibers no further dissolution or decarburization is necessary, which is of outstanding advantage over all previously known methods;
the shredder length preset for the harvested crop at the shredder is 5 to 150 mm and thus significantly below the usual cutting lengths of at least 300 mm of the known fiber crop with field drying and possibly roasting;
There is no field drying necessary whereby the harvesting risk is even significantly reduced even compared to the above-described pre-dissolution before the field drying.

According to the present invention, it is thus possible to process harvest-fresh plants containing natural fibers and to recover the valuable natural fibers already at this stage.

Suitable natural fiber plants are, for example, flax (linen), hemp, jute, sunn, kenaf, Urena, rosella and ramie.

In the context of the present invention, fresh harvesting is understood as meaning plant material which is present before completion of seed ripening and without prior drying.

Surprisingly, it has also been found that it is particularly advantageous if initially the shredded material is produced and the separation of the fibers, that is to say the subsequent sieving or screening process, takes place at a certain time interval from the actual shredding. It has been found that if further processing of the shredded material occurs after too long a time delay (e.g., 24 hours), spoilage processes reduce fiber yield and quality.

This makes it possible to make the natural fiber crop in a conventional manner. This means having a corresponding shredder and a means of transport the first step of the method can be carried out in a conventional manner. The transport then brings the chopped plant parts to a collection point at which the sieve or viewing device is permanently installed. At the moment when the means of transport delivers the shredded material to the sieve or sighting device, natural fibers can also be readily made available by the corresponding sieving or visual process.

A particular advantage of the method according to the invention is also that both for chopping and for separating the fibers from the shredded conventional, already used in agriculture or fiber industry devices can be used. Also, the implementation of the method for the farmer is not a particular difficulty.

This is a particular advantage, since no expensive and expensive devices, such as tobacco cutters, must be purchased. Conventional chopping devices and common screening and screening equipment can be used.

Particularly preferred for fiber separation is a Kammschüttel (shaking machine), which is used in the fiber industry. But other devices which act on the principle of Kammschüttel are particularly suitable.

In the FIG. 1 a block diagram of the method according to the invention is shown. First, it is chopped up from the plant stock. The shredded material thus obtained is treated in such a way that separation of the defeced fibers from the harvest-fresh shredded material takes place. Thereafter, the components, namely the separated fibers and the Residual fiber shives mixture are processed in a conventional manner.

The separated fibers can be processed directly into finished products. Preferably, however, a drying process may precede before the actual processing process. On the other hand, it is also possible that subjecting the separated fibers to further purification and possibly a fiber pulping. Which of the described process sequences according to the invention is the most favorable for the particular natural fiber can be easily ascertained by the person skilled in the art. The cheapest processing process also depends on the product to be produced.

The same applies to the further processing of the residual fiber shives mixture. Here usual methods can be used. For example, these residual fiber shives mixtures are stored in silos, preserved, thereby roasted and plasticized. The subsequent further processing of the residual fiber shives mixture is known per se. Thus, a further work-up by Plastifizierungsprozesse and further processing both in the wet process without prior drying or after prior drying in dry process can be performed. Such measures are known to those skilled in the art.

Claims (11)

1. Method for conditioning natural fibre plants,
   wherein

   a) the freshly harvested plants are chopped, and

   b) the chopped material in the freshly harvested state is subsequently subjected to a screening and/or assorting procedure and thereby fibres are separated from the other plant components, and

   c) the separated fibres and the remaining residual fibre - shive mixture are processed separately.
2. Method according to claim 1, characterized in that the method steps a) and b) are performed in separate devices.
3. Method according to at least one of the preceding claims, characterized in that the separated fibres are further processed into processing products namely building materials, insulating materials, packaging materials, fibre reinforced materials or composites.
4. Method according to at least one of the preceding claims, characterized in that the separated fibres are dried before further processing.
5. Method according to at least one of the preceding claims, characterized in that before drying the separated fibres are subjected to a further purification and/or a fibre pulping.
6. Method according to at least one of the preceding claims, characterized in that before drying and further processing the fibres are subjected to a biological and/or chemical treatment.
7. Method according to at least one of the claims 1 or 2, characterized in that the residual fibre - shive mixture is preserved, roasted, plasticized in silos with or without additives, and stored until processing.
8. Method according to claim 7, characterized in that the defibration of the stored residual fibre - shive mixture is performed without a separate plastification process by exposure to shearing.
9. Method according to claim 8, characterized in that the defibration is performed by means of twin screw extruders or disk mills preferably with a grinding gap of 0,3 mm.
10. Method according to at least one of claims 7 to 9, characterized in that the processing of the pulped residual fibre - shive mixture into processing products namely building materials, insulating materials, packaging materials is performed without prior drying in a wet process.
11. Method according to at least one of claims 7 to 9, characterized in that the processing of the pulped residual fibre - shive mixture into processing products namely building materials, insulating materials, packaging materials, fibre reinforced materials or composites is performed after prior drying in a dry process.

Images