DE102013001262A1 - Bamboo fibers obtainable by wetting bamboo poles, crushing wetted poles, treating obtained bamboo material with alkaline agent, cutting material, washing and drying bamboo fibers and heating using microwave, useful e.g. for producing fleece - Google Patents

Abstract

Bamboo fibers obtainable by (i) wetting and optionally heating bamboo poles, (ii) crushing the wetted bamboo poles, (iii) treating the obtained bamboo material with an alkaline agent, (iv) cutting the bamboo material to fiber length, (v) washing and drying the obtained bamboo fibers, and (vi) heating using microwave, are claimed. An independent claim is also included for preparing the bamboo fibers from the bamboo poles.

Description

BACKGROUND OF THE INVENTION

1. TECHNICAL AREA

The invention relates to bamboo fibers suitable for the production of nonwovens, to a process for producing such bamboo fibers, and to the use thereof for the production of fluidized nonwovens, which in turn can be used for the production of molded articles and technical composite materials.

2. State of the art

Bamboo is now used increasingly in use. The exotic grass plant is used for parquet floors, roofs, toys, fittings in cars and furniture (eg Lufthansa exclusive 1/2013, pp. 60-65). Bamboo is a fast growing resource. In many southern countries there are large bamboo forests that are harvested and grow back quickly. In China, bamboo fibers are also used in textiles, but only in a very small amount because the manufacturing process is too expensive. As a rule, cotton fibers serve as a carrier fiber for the hard bamboo fibers. The fabric must no longer carry the designation of bamboo, since only 10% of the fiber is used. From bamboo poles are built in Asia very high scaffolding, which does not rot and therefore very safe (no water absorption).

Bamboo fibers are - despite their fundamental flammability - in contrast to many other natural fibers relatively flame retardant, which leads to a difficult inflammability even in a non-refined plastic according to the invention. Nevertheless, the plastics according to the invention can be burned for disposal purposes.

In addition, bamboo fibers in the dried state - again in contrast to many other natural fibers - have virtually no moisture absorption.

Bamboo fibers, unlike coal, glass, steel or aramid fibers have a large surface area due to their rough structure. This leads to a particularly intimate connection with the plastic matrix.

Bamboo fibers are also a renewable raw material, which is very inexpensive compared to the conventionally used fibers, but also compared to other natural fibers.

Moreover, bamboo fibers have an antibacterial effect, making their use in fiber-reinforced plastics for the medical field conceivable.

A method of bamboo preparation is in US 4,857,145 proposed to be dissolved by the combination of different chemicals with the application of increased pressure pre-shredded bamboo in its fiber components and then as bamboo fiber pulp for further process steps z. B. pulp production is available.

In the two German patent applications DE 101 15 831 A1 and DE 10 2005 060 500 A1 It is proposed to shred bamboo sticks and mix the resulting fibers with synthetic fibers and needles.

Furthermore, in the DE 10 2005 060 500 A1 And [0047] Proposed a prior quadrangle with a cross-cut to trigger the naturally-existing nodes. This process requires certain conditions in the automation and is not possible as described on an industrial scale, since each node in the rods has a different length and no predetermined dimensions.

Also, the so-called desizing with water is not a solution, since the necessary long storage in the water a digestion process is created which also attacks and damages the fibers. Thus, a dust-free opening is no longer possible. However, the bamboo fibers described in the abovementioned patent applications are not suitable for the production of nonwovens made of bamboo fibers.

It was therefore an object of the present invention to provide bamboo fibers which do not have the disadvantages of the previously known bamboo fibers and from which bamboo fibers can easily be produced.

These bamboo fibers are primarily intended for the production of fiber-reinforced molded parts, which are flame retardant and very light. The resulting composite materials should be shatter-proof. In addition, carbon fibers can be saved and thus the energy costs can be reduced.

BRIEF SUMMARY OF THE INVENTION

• (i) Befeuchten und gegebenenfalls Erwärmen von Bambusstangen,
• (ii) Zerkleinern der angefeuchteten Bambusstangen,
• (iii) Behandlung des so erhaltenen Bambusmaterials mit einem alkalischen Mittel, insbesondere mit ungelöschtem Kalk in Pulverform,
• (iv) Schneiden des Bambusmaterials auf Faserlänge,
• (v) Waschen und Trocknen der so erhaltenen Bambusfasern, und
• (vi) Erwärmen, wobei das Erwärmen durch Mikrowellen erfolgt.

The invention thus provides bamboo fibers suitable for producing nonwovens, which can be obtained by the following steps:

• (i) moistening and optionally heating bamboo sticks,
• (ii) crushing the moistened bamboo sticks,
• (iii) treating the bamboo material thus obtained with an alkaline agent, in particular with quicklime in powder form,
• (iv) cutting the bamboo material to fiber length,
• (v) washing and drying the bamboo fibers thus obtained, and
• (vi) heating, wherein the heating is done by microwaves.

The use of calcium oxide, also quick lime, quicklime, quicklime, lime or quicklime, facilitates the removal of the sugar components, especially lignin, and prevents fouling of the fibers and binder material. The white powder reacts with water with a strong evolution of heat, therefore it can be dispensed with prior lime when using quicklime. Through the reaction with water while calcium hydroxide (slaked lime, lime water) is formed.

Only after a certain residence time in this solution, the fibers are released from the line network and can be processed in the conventional method and disassembled into single fibers.

Preferably, for heating the treated and washed bamboo material, microwaves having a frequency of 2.45 GHz or 915 MHz and a microwave power of 0.8 kW to 9.6 kW (12 × 0.8 kW) are used.

The microwave used achieves a very uniform and rapid heating of the entire bamboo material, wherein overheating of the already dry surface can be avoided and the core water is transported by increasing the partial pressure of vapor in the product core quickly and continuously to the surface.

Subsequently, the fibers thus obtained in a conventional manner after moistening and optionally heating with one or more cascaded fiber openers, z. B. one or more sawtooth drums are opened.

This is preferably done by introducing the thus obtained bamboo material along its fiber direction.

• (a) Befeuchten und gegebenenfalls Erwärmen von Bambusstangen,
• (b) Zerkleinern der angefeuchteten Bambusstangen,
• (c) Beschichtung des so erhaltenen Bambusmaterials mit einem alkalischen Mittel, insbesondere mit ungelöschtem Kalk in Pulverform,
• (d) Schneiden des Bambusmaterials auf Faserlänge,
• (e) Waschen und Trocknen der so erhaltenen Bambusfasern, und
• (f) Erwärmen in der Mikrowelle.

The invention further provides a process for the production of bamboo fibers from raw bamboo, wherein the bamboo rods are successively subjected to the following steps:

• (a) moistening and optionally heating bamboo sticks,
• (b) crushing the moistened bamboo sticks,
• (c) coating the bamboo material thus obtained with an alkaline agent, in particular with quicklime in powder form,
• (d) cutting the bamboo material to fiber length,
• (e) washing and drying the bamboo fibers thus obtained, and
• (f) heating in the microwave.

This method makes it possible to produce a very large amount of nonwoven bamboo fibers economically and without environmental impact.

Furthermore, the method according to the invention makes it possible to defiberize large amounts of bamboo in an environmentally friendly manner. The fiber thus obtained naturally has a low water absorption. (no rotting), no odor (emulsions) and tensile strength, such as steel. This is the ideal fiber to arm plastic. Also as a building material it is suitable and much more.

Due to the method according to the invention it is possible to process several tons of bamboo with a plant in one day, preferably 2 to 20 tons, especially 5 to 15 tons, most preferably about 10 tons of bamboo per day and plant can be processed.

Another object of the invention is the use of the bamboo fibers according to the invention for producing a fluidized non-woven by mixing with binder fibers.

These nonwovens can be used for producing fiber-reinforced plastics and building materials. They can replace glass or carbon fibers, bonded thermally or duroplastically.

The short fibers resulting from the mechanical fibers can be sewn together again and processed as an endless mat.

Bamboo fibers in hole shapes can be deformed into contours by applying a negative pressure, in particular from vacuum. The resulting structured bamboo materials are particularly suitable for the production of insulation materials and / or filling material for seat cushions.

BRIEF DESCRIPTION OF THE DRAWINGS

1 shows a side view of a preferred embodiment of an apparatus for Carrying out the method according to the invention for the continuous production of a comminuted bamboo material treated with an alkaline agent.

2 shows a schematic representation of a same preferred embodiment of the above with subsequent microwave.

3 shows a side view of the same preferred embodiment, wherein the treated bamboo material is fed to stay several silos.

DETAILED DESCRIPTION OF THE INVENTION

• (A) das Bambusmaterial in Schritt (iii) mit Pulver aus gebranntem Kalk beschichtet wird, insbesondere werden dabei auf 10 kg Bambusstangen 0,1 bis 1,5 kg ungelöschter Kalk eingesetzt;
• (B) die Bambusfasern im Wesentlichen Lignin-frei sind; und/oder
• (C) die nach Schritt (vi) erhältlichen Bambusfasern nach Befeuchten und gegebenenfalls Erwärmen mit einem oder mehreren Faseröffnern behandelt werden.

Preferred embodiments of the nonwoven bamboo fibers according to the invention are those wherein

• (A) the bamboo material in step (iii) is coated with quick lime powder, in particular 0.1 to 1.5 kg of quicklime is used on 10 kg of bamboo poles;
• (B) the bamboo fibers are essentially lignin-free; and or
• (C) the bamboo fibers obtainable after step (vi) are treated with one or more fiber openers after wetting and optionally heating.

• (I) in Schritt (b) die angefeuchteten Bambusstangen mit Hilfe von gefederten Brechwalzen, die sich elastisch auf die Dimension der Bambusstangen einstellen, zerkleinert werden;
• (II) die Bambusstangen über ein fahrbares Bambuslager mit einer Materialhebeeinrichtung in eine Einzugsrille zugeführt werden;
• (III) ein fahrbarer Materialzubringer ein oder mehrere Lagersilos gleichmäßig mit dem beschichteten Bambusmaterial füllt;
• (IV) zwei oder mehrere in einer Reihe oder einem Kreis angeordnete Silos zur Lagerung des mit Kalk beschichteten Bambusmaterials dienen;
• (V) das beschichtete Bambusmaterial mit fließendem Wasser in einem Kaskadenabscheider gewaschen wird, wobei der eingesetzte Kalk zurückgewonnen werden kann; und/oder
• (VI) das gewaschene Bambusmaterial einem Trockner mit vorgeschaltetem Reinigungsgebläse dem Mikrowellenofen zugeführt wird.

Preferred embodiments of the method according to the invention for the production of nonwoven bamboo fibers are those wherein

• (I) in step (b), the moistened bamboo rods are crushed by means of spring-loaded crushing rollers which adjust elastically to the dimension of the bamboo rods;
• (II) the bamboo rods are fed via a mobile bamboo bearing with a material lifting device in a feed groove;
• (Iii) a moveable material feeder evenly fills one or more storage silos with the coated bamboo material;
• (IV) serve two or more silos arranged in a row or circle for storage of the lime-coated bamboo material;
• (V) washing the coated bamboo material with running water in a cascade separator, whereby the lime used can be recovered; and or
• (VI) the washed bamboo material is fed to a dryer with upstream cleaning fan the microwave oven.

In the 1 2 shows a lateral view of a preferred embodiment of an apparatus for carrying out the method according to the invention for continuously producing a comminuted bamboo material treated with an alkaline agent, comprising a height-adjustable bamboo magazine ( 1 ) for manual or automatic removal of bamboo poles. The system according to the invention may have 1, 2 or more such magazines.

The in the magazine ( 1 ) bamboo rods are placed over the water spray device ( 2 ), by means of the lifting device ( 13 ) directly above the centered oblique inlet to the crusher rolls ( 3 . 5 ) moistened.

Each supply of bamboo tubes has an upper rigid crusher roller ( 3 ) and a lower sprung breaker roller ( 5 ), which are based on the dimensions of the bamboo poles due to the roll suspension ( 12 ) with adjustable spring pressure. After passing through the crusher rollers ( 3 . 5 ) is the bamboo material by the rotary cross cutter ( 10 ) further crushed. If necessary, the bamboo material can then over the supply line ( 4 ) are moistened with further water.

In the container ( 6 ) is the powdery means for alkalinizing the moistened bamboo material to make the material fissile (preferably uncalcified lime powder) with integrated agitating means for transporting the powder. The in 3 illustrated fan ( 17 ) accelerates the spreading of the powdered lime to achieve a uniform coating. The mobile shredder is on rails ( 14 ) to several silos ( 9 ) to fill.

In the 2 represented guides ( 15 ) for the central guidance of the inserted bamboo rods make it possible to moisten the bamboo material centrally. The likewise in 2 represented workers ( 16 ) the bamboo rods lead to the crusher rollers.

About the in 2 and 3 shown, flexible filling hoses ( 7 ) the bamboo material ( 8th ) evenly into the stacking containers ( 9 ). The acceleration fan ( 11 ) that the cut material is evenly layered in the container.

The material is stored in the stack container 1 to 5, preferably 2 or 3 days.

After staying in the silos ( 9 ) the bamboo material is like in 3 illustrated with running water ( 18 ) and after drying the microwave oven ( 19 ).

The bamboo fibers produced in this way can be selected in particular for producing a fluidized nonwoven by mixing with binding fibers are from the group of polypropylene and polyethylene / polypropylene bicomponent fibers.

Such webs can be used for the production of moldings by compression in a thermobonding process, or for the production of an industrial composite material as a replacement for steel fibers in concrete or cement.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 4857145 [0008]
• DE 10115831 A1 [0009]
• DE 102005060500 A1 [0009, 0010]

Claims (12)

(B) wetting and optionally heating bamboo sticks, (ii) crushing the wetted bamboo sticks, (iii) treating the resulting bamboo material with an alkaline agent, (iv) cutting the bamboo material to fiber length (v) washing and drying the bamboo fibers thus obtained, and (vi) heating, characterized in that the heating is done by microwaves. Bamboo fibers according to claim 1, characterized in that the bamboo material in step (iii) is coated with powder of quick lime. Bamboo fibers according to claim 1 or 2, characterized in that they are substantially lignin-free. Bamboo fibers according to any one of claims 1 to 3, characterized in that the bamboo fibers obtainable after step (vi) have been treated with one or more fiber openers after wetting and optionally heating. A method for producing bamboo fibers according to any one of claims 1-4, characterized in that the bamboo rods are successively subjected to the following steps: (a) moistening and possibly heating bamboo rods, (b) crushing the moistened bamboo rods, (c) treating the so (b) cutting the bamboo material to fiber length, (e) washing and drying the bamboo fibers thus obtained, and (f) heating by microwaves. A method for producing bamboo fibers from a raw bamboo according to claim 5, characterized in that in step (b) the moistened bamboo rods are crushed by means of spring-loaded crushing rollers which adjust elastically to the dimension of the bamboo rods. A method according to claim 5 or 6, characterized in that the bamboo poles are fed via a mobile bamboo bearing with a material lifting device in a feed groove. Method according to one of claims 5 to 7, characterized in that a movable material feeder one or more storage silos evenly filled with the coated bamboo material. Method according to one of claims 5 to 8, characterized in that two or more in a row or a circle arranged silos are used for storage of the coated bamboo. Method according to one of claims 5 to 9, characterized in that the coated bamboo material is washed with running water in a cascade separator, wherein the lime used can be recovered. Method according to one of claims 5 to 10, characterized in that the washed bamboo material is fed to a dryer with upstream cleaning fan the microwave oven. Use of bamboo fibers obtainable according to any one of claims 1-4 for the preparation of a cyclone fleece by mixing with binder fibers.

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