WO2012104041A1

WO2012104041A1 - Fibre-reinforced plastic material

Info

Publication number: WO2012104041A1
Application number: PCT/EP2012/000354
Authority: WO
Inventors: Michael Ludwig GASS
Original assignee: Biowert Ag
Priority date: 2011-02-02
Filing date: 2012-01-26
Publication date: 2012-08-09
Also published as: DE102011010193A1; EP2670792A1

Abstract

The invention relates to fibre-reinforced plastic material comprising natural fibres that are prepared from biomass and that are embedded in the plastic material, said natural fibres being produced from a fibrous biomass with a low lignin content and being embedded in the plastic material and bonded thereto. The invention is characterised in that the fibre-reinforced plastic material has a higher tensile elastic modulus than the plastic material without natural fibres.

Description

Fiber reinforced plastic material

The invention relates to a fiber-reinforced plastic material, comprising natural fibers produced from biomass and a method for producing the fiber-reinforced plastic material.

From the prior art it is known to mix a thermoplastic such as polyethylene natural fibers such as hemp, flax or wood fibers. Such natural fibers have the advantage of complete biodegradability and low

specific weight. So far, however, was disadvantageous that provided with natural fibers plastic material compared to a pure plastic material or even reinforced with glass fibers

Plastic had deteriorated mechanical properties. Therefore, natural fibers have hitherto been regarded predominantly as a filler, merely used to reduce the proportion of non-organic material. In addition, the field of use was limited due to the poor mechanical properties of such compounds. A major field of application of conventional natural fiber-coated plastic materials is in automotive engineering

For example, panels are made in the interior of a motor vehicle from such materials.

In principle, different forms of natural fibers

be distinguished:

CONFIRMATION COPY Wood fibers consist of elongated wood cells, with wood fibers containing about one fifth of lignin and four fifths of cellulose depending on the type of wood. - Bast fibers consist of multicellular fiber bundles. They are long-drawn and thick-walled cells that are unharvested. The main ingredient of bast fibers are essentially

different thickness layers of elongated

Cellulose fibrils enclosed by hemi-cellulose. Typical natural fibers based on bast fibers are, for example, hemp fibers

Natural fibers from green cuttings, in particular grass cuttings or rye cuttings, consist predominantly of hard fibers which are also essentially based on cellulose. Hard fibers usually have a higher hardness than bast fibers, but the hard fibers are more sensitive to bending stress.

The invention has for its object to provide a fiber-reinforced plastic material based on natural fibers, which has improved mechanical properties.

This object is achieved with the features of claims 1 and 7. In advantageous embodiments, each of the dependent claims.

The fiber-reinforced plastic material according to the invention comprises fibrous biomass with a low lignin content

Natural fibers, which are treated and embedded in the plastic material and connected to this, that the fiber-reinforced plastic material compared to the plastic material without natural fibers has a higher tensile modulus. Under low Lignin content is based on the total mass of natural fibers, a lignin content of less than 5 wt.% To understand.

According to the invention, the fiber-reinforced plastic material has a tensile modulus according to ISO 527 of at least 3,000 MPa, preferably of at least 4,000 MPa. With the invention

Natural fibers, a tensile modulus of up to 6,000 MPa can be achieved. These values are twice to four times the tensile modulus of a virgin virgin polypropylene.

Due to the various possibilities of shaping the plastic material is preferably as thermoplastic

Plastic material formed, wherein in the group of

thermoplastics polypropylene and polyethylene for a variety of applications particularly commonly used

thermoplastic plastics are. Recycled plastics are also considered here.

Grass clippings and rye greens are characterized by a particularly low content of lignin. The natural fibers of these substances consist mainly of alpha and hemi-cellulose. Further advantageous raw materials for the biomass are bargasse, ie ensiled sugar cane waste and spent grains, in particular spent grains from husks. These are processed by the process according to the invention

Natural fibers are present in a particularly high purity, so that these natural fibers, provided with a primer, as

Fiber reinforcement in plastics lead to a significant improvement in the mechanical properties of the plastic. This is surprising in that the grass fibers and rye fibers, which consist predominantly of hard fibers, could be expected to have a lower strength than, for example, bast fibers-based

Hemp fibers. In experiments, however, has surprisingly have shown that the tensile strength of a grass or rye-fiber-reinforced thermoplastic test specimen is better than that of a hemp-fiber-reinforced test specimen

thermoplastic. Furthermore, the provided with the natural fibers plastic material on conventional systems for

Plastic processing can be processed, in particular, provided with the natural fibers plastic material can be processed in conventional injection molding and extrusion equipment.

The fiber-reinforced plastic material described above is supplied as a raw material, preferably in the form of pellets for further processing, wherein the fiber-reinforced plastic material by injection molding and extrusion a variety of different

Plastic articles can be produced. It is particularly advantageous that the fiber-reinforced plastic material conventional

Production machines of plastics processing like

Injection molding machines and extrusion machines can be supplied.

The method according to the invention for the provision and processing of natural fibers comprises the following steps:

1) providing a biomass containing natural fibers having a dry matter content of at most 50% by weight;

2) adding water to make the biomass

containing suspension;

3) extraction of natural fibers from the biomass;

4) separating the liquid from the suspension;

5) at least one repetition of steps 2) to 4), wherein in the last repetition of steps 2) to 4) the suspension at least one means for equipping the Natural fibers containing at least one adhesion promoter;

6) drying the natural fibers;

7) mixing the natural fibers with a plastic granulate;

8) pelletizing the plastic provided with the natural fibers.

In step 1, biomass containing natural fibers is provided. These may be natural fiber-containing plant parts of various plants. Especially suitable for that

The methods described are plant parts which are not woody and therefore contain only small amounts or no lignin. Also advantageous are plant parts that are not horny to a small extent or not at all. Cornification is usually triggered by drying in plant fibers. Due to the removal of water between the cellulose molecules, covalent bonds form, causing the plant fibers to become brittle and the tendency to break increase. Therefore, it is proposed to use such plant parts

use that was not dried. On the one hand, freshly cut grass and, on the other hand, ensiled grass are particularly suitable for the process according to the invention. In this way fiber qualities are used as starting material

provided, the dry matter contents are between 25 and 40 wt.%. Dry matter content refers to the content of dry substance that remains when all water is removed. A content of dry matter of 25 to 40% by weight therefore conversely corresponds to a water content of between 75 and 60% by weight. The advantage of ensiling is that the grass, which is only available at certain seasons, can be processed throughout the year without any loss of quality. Another suitable substance is rye green cuttings, with other renewable fiber-containing raw materials available depending on the region can be. However, these should have a low content of lignin, preferably less than 5 wt.% And consist mainly of hard fibers. Against this background, other conceivable raw materials are Bargasse, in particular ensiled

Sugar cane waste and grains, especially spelled-containing brewer's grains advantageous.

In step 2, a suspension containing the biomass is prepared by adding water. This will be the biomass

For example, added to a mixing tank, added water and by means of an arranged in the mixing tank agitator in

Brought suspension. This suspension facilitates the further

Treatment of biomass. In the method according to the invention, the preparation of the suspension takes place exclusively with water, this also forms in the subsequent steps, the solvent which absorbs the soluble components of the biomass. In this step, also a first purification of the biomass takes place, wherein adhering to the biomass impurities and unwanted

Accompanying substances are dissolved in the water. In this context, it is particularly advantageous that the release of the cellulose fibers from the biomass takes place without the use of potentially environmentally hazardous chemicals. Solvent is water only.

In step 3, the natural fibers are extracted from the biomass. For dissolution, a macerator is preferably used, which separates the macerator supplied biomass into individual components and due to the friction generated opens the cells filled with cell liquid and leaves the cell juice. For this purpose, a macerator on a rotating cutting knife, which strikes along with or without touching a counter knife. The counter knife can also be designed as a sieve. The result of maceration is a suspension in which the biomass contained natural fibers and the liquid components contained in the biomass in the aqueous suspension go into solution. The isolated individual natural fibers exist in the

Essence of alpha-cellulose and hemi-cellulose, wherein the relationship between these two types of cellulose of the

Cutting time of biomass is dependent. For the use of natural fibers as a reinforcing fiber in a plastic compound both types of cellulose are relevant: the alpha-cellulose allows a high mechanical stability of the fibers and the hemi-cellulose allows uniform incorporation of the finishing agent, such as the primer or the flame retardant.

Furthermore, hemi-cellulose improves the processability of the plastic compound, in particular its flowability in one

thermoplastic processing. Preferred proportions of alpha-cellulose and hemi-cellulose are, in each case based on the total mass of 20 to 30 wt.% Alpha-cellulose and 15 to 25 wt.% Hemi-cellulose, most preferably the fibrous biomass contains 25 wt.% Alpha-cellulose and 15% by weight hemi-cellulose. Overall, the proportion of alpha-cellulose should be greater than that

Amount of hemi-cellulose.

In step 4, a separation of the liquid from the

Suspension. For this purpose, the suspension is fed to a press, preferably a screw press. In the press there is a

Separation of the liquid with those dissolved in the liquid

Ingredients such as cell water, carbohydrates, proteins and

Impurities from the solid contained in the biomass, the solid in particular includes the natural fibers. In step 5, steps 2 to 4 are repeated at least once, preferably twice. Purified water is used to prepare the suspension. By repeating the steps 2 to 4, which can also be referred to as a purification process, results in a particularly high purity of natural fibers. This high purity of natural fibers is characterized by a particularly low content of natural fibers in carbohydrates and proteins. Experiments have shown that adhering to the natural fibers or firmly connected to the natural fibers

Contaminants, in particular from carbohydrates and

Proteins are formed, the fixability of an agent for

Equipment on the natural fibers deteriorate. Overall, it has been shown that the finer the degree of purity of the natural fiber composed of cellulose compounds, the better the fixability of the finishing agent. Furthermore, natural fibers with a high purity are particularly durable even without additional equipment.

The degree of purity of a natural fiber can be determined by the degree of

Coloring ability can be quantified. For this purpose, natural fibers are dyed with a dye and then investigated, in which way the dye has incorporated or deposited in the natural fibers.

In the last repetition of steps 2 to 4 is the

Suspension added a means of equipping the natural fibers. It is also conceivable to add to the suspension a combination of different agents. The finishing agent is deposited from the

Suspension, ie from the wet phase, to the natural fibers. In this case, it is particularly advantageous that the natural fibers have hitherto been kept moist and no keratinization of the fibers has yet occurred. Thus, there are no or only few hydrogen bonds between them

Zellulosemolekülen emerged, which the accessibility of the Cellulosic molecules complicate and an attachment of the

Can stop equipment on the natural fibers.

Due to the treatment of natural fibers in the wet phase, the agent penetrates into the matrix of natural fibers and is after

final drying firmly attached to the natural fibers. As a means of equipping a variety of additives in question, the natural fibers special properties, such as increased mechanical strength values, special color design,

Light fastness, improved adhesion or reduced

Impart flammability.

For better connectivity with plastics, in particular

Thermoplastic plastics includes the agent one

Adhesion promoters. This may comprise a carboxylated polypropylene, wherein for the carboxylation in particular maleic anhydride

is advantageous if a later connection of natural fibers

Polypropylene is provided. The bonding agent improves the

Adherence of the plastic molecules of the polypropylene to the

Natural fibers, resulting in a fiber-reinforced plastic material with improved mechanical properties. In which

preferred method is the finishing with the adhesion promoter in the aqueous phase. The primer may be provided dissolved or suspended in the water. In this way, the

Adhesive incorporated in the fibers or attached to these. Equipping with the primer can be as easy as a dyeing process.

It is advantageous in the method according to the invention, when the natural fibers provided in the wet state before the first

Dry open with the addition of water and then equipped with the primer. In this way, a good absorption of the adhesion promoter in the natural fibers is achieved. A On the other hand, drying before the equipment would lead to a keratinization of the natural fibers. This would not only the

impaired mechanical properties of natural fibers, but also complicates the recording with the adhesion promoter.

The natural fibers have a content of adhesion promoter of 0.5 wt.% To 5 wt.%, Advantageously, the content of

Adhesion promoters between 1% by weight and 3.5% by weight, with a content of adhesion promoter of from 1.25% by weight to 2.5% by weight being particularly preferred.

In step 6, the natural fibers are dried. In which

According to the invention, this is the first drying of the

Natural fibers, which were always kept moist until that time. The drying is carried out in terms of the drying temperature and the drying time in such a way that the

Natural fibers are not damaged and a cornification

is largely prevented. Furthermore, the drying is carried out in such a way that a sufficient amount of residual moisture is contained in the natural fibers, so that no keratinization of natural fibers takes place even after completion of the drying. In this context, a content of dry matter after completion of the drying of 88 to 92

Wt.%, Not more than 95 wt.% Particularly advantageous. In other words, these values correspond to a residual moisture content of 5% by weight or from 8 to 12% by weight. Thus, the natural fibers retain their

Suppleness, which has a positive effect on the mechanical stability in the subsequent use of natural fibers, for example as

Fiber reinforcement in a plastic material. The drying is preferably carried out in a multi-stage process with pre- and final drying. A particularly advantageous

Drying process involves two-stage drying. In a first stage, the predrying is carried out a drying in a belt dryer. An advantageous drying of the first stage takes place at hot air temperatures of 60 to 80 ° C and a

Residence time of 25 to 35 minutes. The temperature is chosen so that a hornification of natural fibers is largely prevented. Furthermore, excessive local drying of the air stream facing natural fibers is prevented. In a second stage, the final drying, the natural fibers are dried in a stream of air, wherein the natural fibers are exposed directly to a heated air flow and carried with it. For this purpose, an air-layer dryer is preferably used in which the natural fibers and the air flow in the DC through the

Air dryer are performed. The air temperature of the heated air stream is preferably between 75 ° C and 1 10 ° C and the residence time of the natural fibers is 0.5 to 3 s.

In step 7, the natural fibers are mixed with granules of a plastic, wherein the granules are distributed in the pores of the natural fiber matrix due to the large bulkiness.

In step 8, the natural fibers provided with the granules are fed to an agglomeration device, here an extruder. In the extruder, those provided with the granules

Natural fibers compressed and heated by friction. In this case, the rest of the moisture contained in the natural fibers escapes and escapes from the extruder as steam. By heating the natural fibers and the removal of the residual amounts of water is an activation of the bonding agent is received by the direct contact with both the natural fibers and the plastic a particularly strong bond with both substances, so that the Natural fibers are particularly firmly integrated into the plastic.

Furthermore, due to the friction, the plastic at least partially melts, so that the natural fibers pass through the in the extruder

arranged snail evenly in the molten

Plastic be distributed and then firmly with this

are connected.

Subsequently, the mixture of natural fibers and plastic is pressed through a sieve on which a cutting blade strikes along. In this way, pellets of a fiber-reinforced form

Plastic material.

The pellets thus produced can be processed with conventional equipment for plastics processing, in particular, the pellets in conventional injection molding and extrusion equipment

are processed. To produce a plastic article from fiber-reinforced plastic, the pellets are fed to an injection molding or extrusion plant and molded into articles there. By the means of equipping the natural fiber becomes one

functional natural fiber equipped, which has special technical properties depending on the requirements and purpose. To reduce the flammability of natural fibers in insulating materials or a fiber-reinforced plastic article, the agent may comprise a flame retardant, in particular based on boron. To enhance the stability of the natural fibers, particularly colored natural fibers, to UV radiation, the means for equipping may comprise a light stabilizer. A dye allows the coloring of natural fibers, the dye

adheres particularly well to the natural fibers according to the invention and thereby results in a continuous coloration of natural fibers. Other objects, features, advantages and applications of the present invention will become apparent from the following

Description of embodiments with reference to the drawing.

All described and / or illustrated features alone or in any combination form the subject matter of the invention, regardless of the summary in individual

Claims or their dependency.

The figure schematically illustrates a method for the provision and processing of natural fibers.

The methods described are plant parts which are not woody and therefore contain only small amounts or no lignin. Also advantageous are plant parts that are not horny to a small extent or not at all. Cornification is usually triggered by drying in plant fibers. It is therefore proposed to use those parts of plants which have not been dried. Freshly cut grass or siled grass are particularly suitable for the process according to the invention. In this way a biomass

provided, whose dry matter content is between 25 and 40 wt.%. Dry matter content refers to the content of dry substance that remains when all water is removed. A content of dry matter of 25 to 40% by weight therefore corresponds to a water content of between 75 and 60% by weight. The silage has the advantage that the only available at certain seasons grass throughout the year without

Quality loss can be processed. Another suitable substance is rye green sliced, although other renewable fiber-containing raw materials available depending on the region can also be used. In step 2, a suspension containing the biomass is prepared by adding water. For this purpose, the biomass is added to a mixing tank, water is added and brought into suspension by means of an agitator arranged in the mixing tank with water. In this step, a first purification of the biomass, wherein adhering to the biomass impurities and unwanted impurities are dissolved in the water. In step 3, the natural fibers are extracted from the biomass. For leaching, a macerator is used, which separates the macerator-supplied suspended biomass into individual components and due to the generated friction opens the cells filled with cell liquid and leaves the cell juice. For this purpose, a macerator on a rotating cutting blade, which strikes non-contact on a counter knife designed as a sieve. The result of the maceration is a suspension in which the in the

Biomass contained natural fibers are isolated and the biomass contained in the liquid components in the aqueous

Suspension go into solution.

The isolated natural fibers consist essentially of alpha-cellulose and hemi-cellulose, the natural fibers containing 25% by weight of alpha-cellulose and 15% by weight of hemi-cellulose.

In step 4, a separation of the liquid from the

Suspension. For this purpose, the suspension is fed to a screw press. In the screw press, a separation of the

Water containing the components dissolved in the water such as cell water, carbohydrates, proteins and impurities from the natural fibers contained in the biomass. The above-described steps 2) to 4) are repeated twice. In each case, purified water is used to prepare the suspension, which means that water is provided without the previously dissolved constituents. By repeating steps 2 to 4, which are also referred to as purification process, results in a particularly high purity of natural fibers. In the

the last time, ie second repetition of steps 2) to 4), a means for equipping the natural fibers is added to the purified water. This agent is then dissolved in the aqueous suspension and is deposited on the natural fibers in the wet phase.

The purity of natural fibers is determined by a dyeing test

demonstrated. For this purpose, first 0.5 g of direct dye is dissolved in water at a temperature of 40 ° C. Then the solution 2 g Glauber's salt (NaSO *) is added and the solution is heated to 60 ° C. Subsequently, natural fibers are added, which are taken after the first drying and have a content of dry matter of 60 to 65 wt.%. The resulting mixture is heated with stirring to 70 ° C and stirring for 30 min. kept at 70 ° C. Then the natural fibers are pressed with a hand press, rinsed several times with water and dried in air. The analysis of the natural fibers is done by means of a microscope.

Dyes used are Columbia real black BV 150% of CBW Chemie GmbH Wolfen, Solaminlichtgelb 5G 167% of CBW Chemie GmbH Wolfen, Solaminlichtscharlach FB 200% of CBW Chemie GmbH Wolfen, DyStar Remazol Yellow RR Gran of DyStar Colors Distribution GmbH Frankfurt / Main, DyStar Levafix Brilliant Red CA of DyStar Colors Distribution GmbH Frankfurt am Main and DyStar Remazol Red CA Gran of DyStar Colors Distribution GmbH Frankfurt am Main. The examined with the microscope natural fibers are characterized by an almost continuous coloring, there are only minor defects. Starting from the by the Microscope visible surface of a natural fiber is the

Area fraction of the defects of a natural fiber at most 5%.

The means for equipping contains a bonding agent based on a carboxylated with maleic anhydride polypropylene for better connectability to thermoplastics. In order to reduce the flammability of natural fibers, the composition further contains a flame retardant based on boron

Use of natural fibers provided in UV-exposed areas, the agent may be additionally provided with a light stabilizer and a dye allows the continuous coloring of natural fibers.

In step 5, the natural fibers are dried. In which

According to the invention, this is the first drying of the

Natural fibers, which were always kept moist until that time. To avoid cornification, the drying is carried out in such a way that the natural fibers after drying have a content of dry matter of 88 to 92 wt.%, At most 95 wt.% Have.

The drying takes place in a two-stage process. In a first stage, drying takes place in a belt dryer

Warm air temperatures of 60 to 80 ° C and a residence time of the natural fibers in the belt dryer from 25 to 35 min. So that

Nevertheless, natural fibers have a uniform residual moisture, the belt dryer is designed so that only a portion of the dried natural fibers is removed, while the remaining part of the

Belt dryer for a repeated drying is fed again. For this purpose, the part of the natural fibers is returned, which was turned away during the drying of the air flow and thus has the highest residual moisture. Accordingly, only the part of Natural fibers taken, which has a uniformly low residual moisture. The drying parameters during the drying in the first stage are adjusted so that the natural fibers after the first drying a residual moisture content of 20 to 40 wt.%, At most 50 wt.% Have.

In a second stage, the natural fibers are placed in a stream of heated air and passed in co-current with the heated air, the natural fibers releasing moisture to the co-current air. For this drying is a

Air-layer dryer used. In this dryer, the

Natural fibers entrained in the air flow and dried in a short time. The air temperature of the heated air stream is preferably between 75 ° C and 110 ° C and the residence time of the natural fibers in the device is preferably between 0.5 s and 3 s done. For this purpose, the air flow is accelerated by means of a blower to a speed of 1 m / s to 6 m / s.

The drying parameters during the drying in the second stage are adjusted so that the natural fibers have a content of dry matter of 88 to 92 wt.%, At most 95 wt.% After the second drying. After drying, the natural fibers are separated from the air, this can be done for example by a cyclone.

The natural fibers removed after the second drying have a bulk of 31 kg / m ³ . The bulkiness can be quantified by a bulk density, or by determining the bulk density. To determine the bulkiness of natural fibers are blown into an open-topped, dimensionally stable container with the dimensions of 1 m ^x 1 mx 0.25 in or manually filled and smoothed off at the top of the container, then the Weight of natural fibers filled in the container weighed. From the mass and the volume (0.25 m ³ ) the bulkiness is calculated. In this case, individual results and an average of three experiments must be stated. A bulkiness of natural fibers according to the invention is between 30 kg / m ³ and 50 kg / m ³ , preferably between 35 and 60 kg / m ³ .

The natural fibers produced by the method described above are then packaged and sent for further use.

For use as an insulating material, the natural fibers can either be formed into insulation boards or be introduced directly as blowing insulation into a building.

For use as a fiber reinforcement for a plastic material, the natural fibers are mixed with granules of a plastic, the granules being distributed in the pores of the natural fiber matrix due to the large bulkiness. Subsequently, provided with the granules natural fibers of a device for

Agglomeration, fed here to an extruder. In the extruder, the natural fibers provided with the granules are compressed and heated. In this case, the rest of the moisture contained in the natural fibers escapes and escapes from the extruder as steam. By heating the natural fibers and the removal of the residual amounts of water is an activation of the bonding agent of the direct contact with both the natural fibers and with the

Plastic enters into a firm bond with both substances, so that the natural fibers are firmly integrated into the plastic. Furthermore, the plastic melts, whereby the natural fibers are uniformly melted in the melt by the screw arranged in the extruder

Plastic be distributed. After melting, the mixture becomes of natural fibers and plastic pressed through a sieve on which a cutting knife along strips. In this way, pellets of a fiber-reinforced plastic material are formed. As the starting material of the plastic, a thermoplastic material, in particular polypropylene or polyethylene is used, wherein the two aforementioned plastics may also be formed as recycled material. The pellets thus produced can be processed with conventional equipment for plastics processing, in particular, the pellets in conventional injection molding and extrusion equipment

are processed. To produce a plastic article from fiber-reinforced plastic, the pellets are fed to an injection molding or extrusion plant and molded into articles there.

A test piece consisting of a fiber-reinforced plastic containing 50% by weight of the natural fibers according to the invention and 50% by weight of polypropylene achieves the following values:

Density 0.82 g / cm ³

Tensile strength (ISO 527) 32 MPa

Tensile modulus (ISO 527) 4,000 Mpa

Charpy impact strength (ISO 179) 1 1 kJ / m ²

The melt flow index, as the index of the flow behavior of a thermoplastic material, is compared to a pure

Polypropylene reduced by only 20%. This indicates similar good processability of the fiber reinforced plastic compared to a pure plastic. However, the strength values improve significantly over pure polypropylene. Both the tensile modulus and the impact strength of the fiber reinforced Plastics are significantly better than the comparative values of a polypropylene. The values for pure polypropylene as new are: Density 0.9 g / cm ³

Tensile strength (ISO 527) 26 MPa

Tensile modulus (ISO 527) 1,450 Mpa

Charpy impact strength (ISO 179) 5 kJ / m ² Based on the density, the strength values of the fiber-reinforced plastic compared to pure plastic are significantly improved, so that due to the better strength further weight reduction and thus material saving is possible. Thus, for example, the wall thickness of a plastic article can be reduced.

Furthermore, it has surprisingly been found that a test specimen, which consists of ground, ie recycled fiber-reinforced plastic of the type described above, has a tensile strength which is also 32 MPa and thus behaves comparable to a non-processed specimen. Thus it turns out that the fiber-reinforced plastic material according to the invention is particularly suitable for recycling.

Claims

Fiber-reinforced plastic material, comprising biomass-provided natural fibers which are embedded in the plastic material, characterized in that the natural fibers are made from fiber-containing biomass with low lignin content and treated and embedded in the plastic material and connected to these, that the fiber-reinforced plastic material in Compared to the plastic material without natural fibers has a higher tensile modulus. Fiber-reinforced plastic material according to claim 1, characterized in that the tensile modulus according to ISO 527 is at least 3,000 MPa, preferably at least 4,000 MPa. Fiber-reinforced plastic material according to claim 1 or 2, characterized in that the plastic material comprises thermoplastic material. Fiber-reinforced plastic material according to claim 3, characterized in that the plastic material is formed from polypropylene or polyethylene. Fiber-reinforced plastic material according to one of claims 1 to 4, characterized in that the proportion of fibrous biomass in the plastic material is at least 40% by weight, preferably 50% by weight. A plastic article of a fiber reinforced plastics material according to any one of claims 1 to 5. A method of producing a fiber reinforced plastics material, the method comprising the steps of: 1) providing a fiber containing biomass having a dry weight of at most 50% by weight; 2) adding water to Preparing a suspension containing the biomass; 3) extraction of natural fibers from the biomass; 4) separating the liquid from the suspension; 5) at least one repetition of steps 2) to 4), wherein in the last repetition of steps 2) to 4) the suspension contains at least one fiberising agent comprising at least one coupling agent; 6) drying the natural fibers; 7) mixing the natural fibers with a plastic granulate; 8) pelletizing the plastic provided with the natural fibers. Method according to one of claims 1 to 4, characterized in that the means additionally comprise a flame retardant, light stabilizers and / or a dye. A method according to claim 7, characterized in that the adhesion promoter comprises a carboxylated polypropylene. 10. The method according to claim 9, characterized in that maleic anhydride is used for the carboxylation.

1. The method according to any one of claims 7 to 10, characterized in that the fiber-containing biomass grass clippings, rye greens, Marc and / or Bargasse contains.