CA2339106A1 - Composite materials on the basis of renewable resources - Google Patents

Abstract

The invention relates to composite materials on the basis of renewable resources, using reinforcing materials on the basis of natural fibres. Duro- plastics on the basis of oleochemically cross-linkable systems are described as matrix material. These contain as principal ingredients derivatives of oleochemical fatty substances, such as epoxidized fatty substances, fatty substances modified by carboxylic acid or carboxylic anhydride as well as (meth)acrylate-modified fatty substances and fatty substances containing ami no groups. Synthetic comonomers and/or coreactants can possibly be added to sai d oleochemical duro-plastics. Using all conventional manufacturing technology, the above composites can be used to produce components for vehicle manufacture, aircraft manufacture, the building industry, window constructio n, the furniture industry, the electronics industry, sports equipment, toys, machines and apparatuses, the packaging industry, agriculture or security technology.

Description

Composite Materials on the Basis of Renewable Resources This invention relates to a composite material based on natural fibers and a matrix material, to a process for its production and to the use of such composite materials.
Fiber composites consist at least of fibers and a matrix material.
The function of the fibers is to strengthen the material. More particularly, the fibers absorb tensile forces acting on the material while the matrix fills voids between the fibers and coats the fibers. The matrix thus transmits the shear forces acting on the composite material. In addition, the matrix protects the coated fibers from outside influences such as, for example, the penetration of water or moisture, oxidative or photo-oxidative influences.
Known fiber composites include, for example, glass-fiber-, metal-fiber- or carbon-fiber-reinforced plastics. By virtue of their high strength, durability and reproducibility, composites such as these have hitherto been successfully used in many fields. However, in view of the need for sustainable development, products based on biomass and/or agricultural products as renewable raw materials have also been increasingly in demand for composite materials. In contrast to petrochemical and fossil raw materials, renewable raw materials are never exhausted and, through the cultivation of new plants, can be regenerated at any time by photosynthesis.
Plastics reinforced by natural fibers are known per se. Their advantages over glass-fiber-reinforced plastics in regard to raw material base, ecobalance, safety at work, weight and thermal disposal have already been described, cf, for example Kohler, R.; Wedler, M.; Kessler, R.:
"Nutzen wir das Potential der Naturfasern?" in: Gulzower Fachgesprache "Naturfaserverstarkte Kunststoffe" (Ed. Fachagentur Nachwachsende Rohstoffe, Gulzow 1995), pages 95-100, and "Leitfaden Nachwachsende Rohstoffe, Anbau, Verarbeitung, Produkte", 1 st Edition, Heidelberg: Muller, 1998, more particularly Chapter 8. The matrixes used may be divided into thermoplastic and thermoset systems.
Systems with thermoplastic matrixes based on renewable raw materials are known. Thus, EP-A-687 711 describes a fibre composite of biodegradable fibers and a matrix of biodegradable material. Cellulose acetate, lignin, starch and starch derivatives are proposed as suitable thermoplastic materials for the matrix. Products such as these have been found to be unsatisfactory in regard to processability, mechanical properties in important applications and price.
DE-A-196 47 671 describes a fiber composite with a fibrous material for reinforcement and a matrix material based on shellac. The matrix material may contain a crosslinking agent. The main disadvantage of this thermoset matrix material is the very limited availability of shellac.
Other thermoset systems available at the present time are mainly polymer systems of which the raw materials are very largely petrochemical in origin (polyurethanes, epoxy resins, polyesters, etc.). In the field of polyurethanes, some proposals have been put forward with a view to developing native-based raw materials. For example, EP-A-634 433 proposes reaction products of a polyester obtainable by self-condensation of ricinoleic acid with an aromatic polyisocyanate as binders for the production of composite materials.
In addition, DE-A-41 19 295 proposes an ecofriendly composite material of natural fibers and plastics of the polyurethane-polyester and/or polyurethane-polyamide type which contain hydroxyfunctional natural fatty acids of unchanged length or derivatives thereof.
In "Angewandte makromolekulare Chemie" 249 (1997), pages 79 to 92, R. Mulhaupt, D. Hoffmann, S. Lawson and H. Warth describe flexible, semiflexible and rigid polyester networks based on maleinized oils of vegetable oils, such as soybean, rapeseed and linseed oil, as anhydride-functional hardeners with epoxy resins based on bisphenol A/diglycidyl ether or epoxidized vegetable oils. They also describe unsaturated polyester resins based on malefic anhydride, epoxidized vegetable oils and styrene which may optionally be reinforced with natural short fibers, such as flax or hemp. The processability of such resins by existing processing machines is not discussed.
The problem addressed by the present invention was to provide composite materials where both the reinforcing material and the matrix material would largely be based on renewable raw materials. In addition, these composite materials would be processable without difficulty by existing processing machines.
The solution to the problem stated above can be found in the claims and consists essentially in the use of natural fibers as the reinforcing material and of a matrix material consisting essentially of binder systems based on oleochemical thermosets. Accordingly, the present invention relates to composite materials based on natural fibers and a matrix material, the matrix material being largely based on oleochemical thermosets.
The present invention also relates to a process for the production of structural components of the thermosets according to the invention and natural fibers.
The present invention also relates to the use of the composite materials according to the invention for the production of structural components for vehicle manufacture, i.e. for the manufacture of cars, railway vehicles and aircraft and for the production of bodywork parts and interior trim. The composite materials according to the invention may also be used in the construction industry as insulating materials, sandwich elements and the like, in window manufacture for making window frames, door frames and doors, in the furniture industry for the production of panels, furniture parts and furniture, in the electronics/energy industry for the production of computers, domestic appliances, housings, blades for fans or wind energy installations. In the leisure industry and in the field of sports, sports equipment, boats, gliders and toys can be made from the composite materials according to the invention; in machine construction, they may be used for the manufacture of gearwheels or gear components;
in waste management, they may be used for the manufacture of garbage containers. In plant manufacture, vessels, pumps and tube elements can be made from the composite materials according to the invention; in the packaging industry, the materials according to the invention may be used for the production of bottles, containers, moldings and technical packaging.
Finally, the composite materials according to the invention may be used in agriculture for the production of containers, feed silos, plant pots and, in safety field, for the production of safety helmets.
It is known that thermosets are plastics which are formed from oligomers - optionally with monomers or polymers added - by irreversible and close crosslinking via covalent bonds. "Thermosets" in the context of the invention are understood to be both the raw materials before crosslinking (i.e. the reactive resins) and the cured reaction products.
Oleochemical derivatives or fatty compounds in the context of the present invention are natural, more particularly vegetable or animal, oils and more particularly derivatives and secondary products thereof obtained by chemical reaction. The oils mentioned occur in nature in the form of natural mixtures of different fatty acid glycerol esters, for example in palm oil, palm kernel oil, palm stearin, olive oil, rapeseed oil, coriander oil, sunflower oil, cottonseed oil, peanut oil, hemp oil, linseed oil, lard oil, fish oil, train oil, lard or bovine tallow. Besides the saturated acids, the fatty acid component of the natural triglycerides mentioned above are in particular the mono- or polyunsaturated acids palmitoleic acid, oleic acid, elaidic acid, petroselic acid, erucic acid, ricinoleic acid, hydroxy-methoxystearic acid, 12-hydroxystearic acid, linoleic acid, linolenic acid and gadoleic acid. Other crosslinkable functional groups, such as hydroxyl, mercapto, carboxyl, amino, anhydride or epoxide groups, or even olefinic double bonds may be introduced into these triglycerides by methods known per se.
Examples of preferred starting materials are the natural fats and oils of rape, sunflowers, soya, flax, hemp, castor oil, coconuts, oil palms, oil palm kernels and olives.
Other suitable starting materials are the dimer and trimer fatty acids obtainable by the polymerization or oligomerization of fatty acids by radical polymerization or thermal treatment and secondary products thereof.
The following classes of compounds are particularly suitable for the production of oleochemical thermosets:
~ epoxidized fats and oils ~ OH-functionalized fats and oils which either already contain native hydroxyl groups, such as castor oil for example, or have been produced by ring opening of epoxidized fats and oils or by ring opening of maleinized oils and fats with polyols ~ anhydride-functionalized fats and oils, more particularly maleinates ~ aminic fatty compounds ~ (meth)acrylate-functional fatty compounds, preferably produced by esterification of (meth)acrylic acid with hydroxyfunctionalized fats and oils or by ring opening of epoxidized fats with olefinically unsaturated carboxylic acids, such as (meth)acrylic acid, crotonic acid, itaconic acid, malefic acid and mixtures thereof ~ reaction products of OH-functional fats and oils with carboxylic anhydrides.
The most important representatives of the epoxidized fats and oils are epoxidized soybean oil, epoxidized rapeseed oil and epoxidized sunflower oil.
These epoxidized triglycerides may be converted into the corresponding hydroxyfunctional compounds by nucleophilic ring opening.
Nucleophiles are understood to be alcohols such as, for example, water, methanol, ethanol, ethylene glycol, glycerol and trimethylol propane;
amines such as, for example, ethanolamine, diethanolamine, triethanolamine, ethylenediamine, dipropylenetriamine or hexamethylene-diamine; or carboxylic acids, such as acetic acid, dimer fatty acid, malefic acid, phthalic acid, terephthalic acid or a mixture of mono- and/or difunctional fatty acids containing 6 to 30 carbon atoms.
Anhydride-modified fatty acids ring-opened with nucleophiles and derivatives thereof may also be used with advantage. Anhydride-modified fatty acids and derivatives thereof may also be obtained, for example, by ene-addition or Diels-Alder addition of unsaturated anhydrides, such as malefic anhydride, onto isolated and/or conjugated double bonds. The addition may also be a radical addition; additions of saturated anhydrides onto saturated and unsaturated fatty compounds are also possible.
If epoxidized or anhydride-modified fatty compounds are reacted with aminofunctional nucleophiles in such a way that the derivatives obtained contain primary or secondary amino groups, these products may also be referred as "amine-modified fats". Compounds such as these may also be processed to oleochemical thermosets.
Fatty compounds containing carboxylic acid or carboxylic anhydride groups suitable for curing with epoxides may be obtained by the esterification of carboxylic anhydrides with hydroxyfunctional fatty compounds. Examples of suitable carboxylic anhydrides are malefic anhydride, succinic anhydride, itaconic anhydride, phthalic anhydride, 4 cyclohexane-1,2-dicarboxylic anhydride, naphthalene-1,8-dicarboxylic anhydride, adipic anhydride and mixtures thereof. The hydroxyfunctional fatty compounds may be hydroxyl-containing or hydroxylated triglycerides, diglycerides, dimer diols or mixtures thereof which may also have been hydrogenated.
In addition, the polyaminoamides known per se based on dimer and/or trimer acids with low molecular weight polyamines may be used as aminic fatty compounds.
The esterification products of hydroxyfunctional fatty compounds with olefinically unsaturated carboxylic acids or the ring opening products of epoxidized fatty compounds with the olefinically unsaturated carboxylic acids from the group consisting of acrylic acid, methacrylic acid, crotonic acid, itaconic acid, malefic acid, fumaric acid and mixtures thereof may additionally contain other comonomers. These additional comonomers may on the one hand be the above-mentioned olefinically unsaturated carboxylic acids in excess although they may also be their esters of C~-so alcohols, preferably C~o_22 alcohols, and allyl esters or vinyl esters, such as vinyl acetate, vinyl propionate, vinyl laurate or vinyl versatate, or even styrene, divinyl benzene or mixtures thereof.
The matrix material to be used in accordance with the invention may be formulated as a one-component system. The (meth)acrylic acid derivatives of the fatty compounds are particularly suitable for this purpose.
These thermoset systems may be formulated as a one-component system by addition of known radical polymerization initiators. Synthetic olefinically unsaturated comonomers may also be added.
In the case of two-component systems, the two reactants are only mixed just before the reaction. For example, triglycerides containing carboxyl groups or carboxylic anhydride groups may be reacted with epoxidized fats and oils. Synthetic epoxides may optionally be added in varying amounts.
The triglycerides containing carboxylic acid or carboxylic anhydride groups may be similarly cured with fatty amines.

The triglycerides containing carboxylic acid or carboxylic anhydride groups may also be esterified with hydroxyfunctional fatty compounds.
Esterification catalysts known per se may have to be added for this purpose.
Epoxidized triglycerides, optionally with synthetic epoxides added, may also be cured with fatty amides, optionally in the presence of low molecular weight synthetic polyamines.
Another way of modifying the matrix material of the oleochemical thermosets according to the invention is to produce polymer blends with thermoplastic polymers such as, for example, polyethylene, polypropylene and copolymers thereof, polystyrene and styrene copolymers or even thermoplastic materials of natural origin such as, for example, thermoplastic starch, polyesters of hydroxycarboxylic acids (Biopol), cellulose acetate.
Other auxiliaries known per se, including flameproofing agents, pigments, UV absorbers and organic and/or inorganic fillers, may also be added to the composite materials. Suitable inorganic fillers are natural and synthetic silicas (Aerosil types, including hydrophobicized forms, Amosil types, zeolites, such as Sasil and Flavith D (odor absorbers made by Degussa), silicate-containing hollow microbeads (Fillite made by Omya) and natural silicates, such as bentonites, montmorillonites, talcum, kaolinite and wollastonite. Suitable pigments are, for example, calcium carbonate, calcium sulfate, barium sulfate, titanium dioxide and carbon black. Various types of carbon black (furnace blacks, gas blacks, for example Printex 60 of Degussa) color the structural component black, even in low concentrations, and protect it against UV radiation. The auxiliaries are used in concentrations of 0.1 to 5% by weight. Organic fillers are, for example, starch and starch derivatives, wheat proteins, cellulose powder and chitin/chitosan powder.
Although the oleochemical thermosets mentioned above may also be processed with synthetic fibers, such as glass fibers, carbon fibers, metal fibers and the like to form fibre composites, natural fibers are preferably used in accordance with the invention. These natural fibers may be used in the form of short fibers, yarns, rovings or preferably sheet-form textiles in the form of nonwovens, needle-punched nonwovens, random laid nonwovens, woven fabrics, laid fabrics or knitted fabrics based on flax, hemp, straw, wood wool, sisal, jute, coconut, ramie, bamboo, bast, cellulose, cotton or wool fibers, animal hair or fibers based on chitin/chitosan and combinations thereof.
The fiber composites according to the invention may be processed to mouldings by any of the known methods. One feature common to all these known methods for the production of mouldings is that the starting materials, fiber and matrix, are combined to form a moulding composition which cures on, in or between solid moulds to form a composite material.
The fiber starting material is introduced into an uncured matrix of the thermoset and, by compression, is completely wetted and coated with this still low-viscosity thermoset resin. Accordingly, the nature of the fibrous material to be introduced critically determines the production method to be used. For example, no reinforcing material in the form of a woven fabric may be used in an extrusion process. By contrast, short fibers are eminently suitable for extrusion processes or transfer molding applications of matrix/fiber mixtures. The latter technique is preferably used in the case of one-component systems. The matrix material is also determined by the production process, for example by the viscosity of the thermoset mixture before curing.
The choice of a suitable matrix material is determined by the type of fibers, by the fiber intermediate and not least by the setting rate and the surface area. The impregnation of the fibers and the hardening cycle of the matrix determine both the quality of the composite and the joining of the layers to one another, more particularly the interlaminar strength.

Production technologies suitable for use in accordance with the invention include, for example, pultrusion, production by the winding technique, the pressing technique and the vacuum technique, differential pressure-resin transfer molding (DP-RTM), resin transfer molding (RTM), the prepreg technique.
The invention is illustrated by the following Examples. Unless otherwise indicated, quantities relating to compositions are all % by weight.
Examples Example 1: production of the ring opening product 260 g of Edenol D81 (epoxidized soybean oil, Henkel, epoxide content 6.63%), 155.3 g of acrylic acid and 1.66 g of 2,5-di-tert.butyl hydroquinone are weighed into a 500 ml four-necked flask equipped with a reflux condenser and heated with stirring to 120°C while air is passed through at a rate of 15 I/h. The reaction begins exothermically which is reflected in an increase in temperature to 140°C. The mixture is left to react for a total of 6 hours counting from the moment the temperature of 120°C is reached. The excess acrylic acid is then distilled off at 120°C/100 mbar while air (15 I/h) is passed through (ca. 2 h).
A yellow viscous product is obtained; it has an epoxy content of <
0.2%, an acid value of < 50 and a viscosity of ca. 45,000 mPas at 20°C.
The polymerization inhibitor 2,5-di-tert.butyl hydroquinone may be replaced, for example, by a-tocopherol.
Example 2: mixture of the reactive resin (monomer mixture) 97% of the adduct of epoxidized soybean oil and acrylic acid according to Example 1 (contains 4.1 % of free acrylic acid) + 3% of free acrylic acid + 2% of tert.butyl per-(3,3,5-trimethyl hexanoate) This mixture is placed in a drying cabinet for 10 to at most 30 mins.

at 200°C and cured. The polymer shows no adhesion to Teflon plates and only very slight adhesion to Sitka plates. Commercially available release agents may be used to prevent adhesion to other surfaces.
Depending on the required processing temperature, the peroxide may be replaced by a faster decomposing type. This does not affect the mechanical properties.
The resin may be processed without difficulty in existing processing machines (presses, extruders, impregnating rollers).
Example 3: composite materials In order further to improve the mechanical properties, fibers are incorporated in and cured with the resin. The fibers are present in the form of a random fiber nonwoven with a weight of 200 to 2,000 g/m2.
The following mechanical properties are achieved with the resin of Example 2 and 37% of flax fibers:
tensile strength aZ, Br: 43 N/mm2 E modulus EZ: 7207 N/mm2 Elongation sZ, B~: 0.9%
Example 4: synthesis of the adduct of castor oil lhvdroaenated) and malefic anh dr~(addition onto OH Group) 300 g of Loxiol G15 (supplier Henkel, hydrogenated castor oil, saponification number 179) are weighed into a 500 ml three-necked spherical flask and melted at 80°C. The fat is dried in vacuo (20 mbar) for 1 hour. 62.05 g of malefic anhydride are then added, after which the contents of the flask are heated to 150°C and blanketed with nitrogen.
Reaction time 3 h. Two phases are initially formed but gradually disappear.
Slight exothermy was observed. After 3 h, vacuum (20 mbar) is reapplied to remove unreacted malefic anhydride.
Analysis:

free malefic anhydride 1.4%
free castor oil 28%
castor oil fatty acid 2.9%
other fatty acids 1.2%
glycerol 0.9%
Product viscous, brown cloudy Example 5: synthesis of the adduct of hydroxyl-containing linseed oil and malefic anhydride Hydroxylated linseed oil 28.6 g of Edenol B 316 (linseed oil epoxide, Henkel) are stirred with 171.4 g of water in a laboratory autoclave (volume 300 ml), purged three times with nitrogen and reacted for 3 h at 220°C. The reaction mixture was then concentrated by evaporation at 90°C/20 mbar in a rotary evaporator.
Residual epoxide content: 0.05%.
Preparation of adduct 78.6 g of the hydroxylated linseed oil were reacted with 69.8 g of malefic anhydride as described in Example 1.
Example 6: curing of anhydride adducts with epoxides Reaction product from Example 4 (49.4%) was stirred with Edenol B
316 (linseed oil epoxide) (50.6%), applied to a flax nonwoven (35% of the composite as a whole) and crosslinked for 10 mins. at 200°C/30 bar applied pressure.
Tensile test to DIN 53455 tensile strength 16.4 Mpa elongation at max. 0.88%
Example 7 As in Example 6, the reaction product of Example 5 (37%) was stirred with Edenol B 316 (63.0%), applied to a flax nonwoven (35% of the composite as a whole) and crosslinked for 10 mins. at 200°C/30 bar applied pressure.
Tensile test to DIN 53455 tensile strength 40.7 Mpa elongation at max. 2%
Examales 8 to 16 Mixtures of reactive resins (monomer mixtures) of the ring opening product of Example 1, comonomers and 2% tert.butyl per-(3,3,5-trimethylhexanoate) were prepared as in Example 2. Test specimens for tensile strength tests to DIN 53455 were prepared from these mixtures.
As can be seen from the tensile strength, tear strength and elongation values, these cured reactive resins have excellent mechanical properties. The production of composite materials in accordance with Examples 6 and 7 also led to composites with excellent strength properties.
Example 17 As in Example 1, 2% of tert.butyl per-(3,3,5-trimethylhexanoate) was added to an acrylate-modified epoxidized linseed oil (Photomer 3082, Henkel) and the mixture was cured to form test specimens for a tensile strength test to DIN 53 455. The following strength values were measured:
tensile strength 4.843 MPa elongation at max. 2.8%
tear strength 4.58 MPa elongation at break 2.64%
Example 18 66 kg of linseed stand oil and 23.1 kg of malefic anhydride (MA) were heated with stirring under nitrogen to 200°C and kept at that temperature for 7 hours. Nitrogen was passed over throughout the reaction time. A
red-brown, clear viscous malefic anhydride adduct was formed.
In a cure test, 558 g of this malefic anhydride adduct were mixed with 27.9 g of polyethylene glycol 300 and the resulting mixture was cured in an aluminium dish for 16 hours at 80°C. A thoroughly cured film was obtained.
Example 19 An MA adduct was prepared as in Example 1 from 66 kg of soybean oil and 23.1 kg of MA. 121.1 g of dibenzoyl peroxide were added to 599 g of this MA adduct, followed by heating for 12 hours to 100°C. A brown, solid slightly brittle film was formed.
Example 20 Reaction of fatty maleinates with fatty epoxides 14.6 g of epoxidized linseed oil and 0.2 g of N-methyl imidazole were added to and mixed with 35.5 g of the linseed oil/MA adduct of Example 18, followed by heating for 3.5 hours at 80°C in an aluminium dish. A light brown, hard, slightly brittle moulding was obtained.
Example 21 A linseed oil/MA adduct in a ratio by weight of 10:5.5 was prepared as in Example 20. 14.6 g of epoxidized linseed oil were added to 29.5 g of this MA adduct, followed by curing for 5 hours at 80°C. An orange-colored, very hard and only very slightly brittle molding was obtained.
Example 22 A soybean oil fatty acid/MA adduct (ratio by weight 10:3.5) was prepared. 13.9 g of epoxidized linseed oil and 0.2 g of N-methylimidazole were added to 30 g of this adduct, followed by curing for 1 hour at 150°C.

A yellow, slightly cloudy, flexible and elastic molding was obtained.
Example 23 Reaction of fatty maleinates with bisphenol A diglycidyl ether (example of the combination of a fat with a synthetic epoxide) 27.8 g of bisphenol A diglycidyl ether and 0.2 g of N-methyl imidazole were added to 30.0 g of a linseed oil fatty acid/MA adduct (ratio by weight 10:6.67), followed by heating for 1 hour to 150°C. A dark brown, hard, clear molding was obtained.
Example 24 Production of fatty amines:
763.6 g of epoxystearic acid methyl ester and 1731.8 g of dipropylenetriamine were heated together in a three-necked flask. The methanol formed was distilled off to 200°C via a water separator (100 ml).
The mixture was then stirred for 5 hours at 200°C, a yellow clear liquid being formed. The excess amine was distilled off in a high vacuum (0.08 mbar) up to a bottom temperature of 200°C. A yellow-orange, viscous clear substance (fatty amine A) was obtained.
841.4 g of ethylenediamine were similarly introduced into a three-necked flask and 855.1 g of epoxidized soybean oil were added dropwise over a period of 1 hour at 100 to 130°C. After reaction for another 5 hours at 125 to 130°C, the excess amine was distilled off in vacuo at 150°C. A
light brown pasty substance (fatty amine B) was obtained.
10.0 g of fatty amine A were mixed with 17.1 g of linseed oil/MA
adduct (10:11.1 ) and the resulting mixture was cured at 150°C in an aluminium beaker. A solid molding was immediately formed.
25.0 g of fatty amine B were similarly mixed with a soybean oil/MA
adduct (10:3.5) in an aluminium beaker. Polymerization occurred immediately and a solid molding was formed.

Example 25 46.2 g of a soybean oil/MA adduct (10:3.5) were mixed with 3.4 g of diethylenetriamine in an aluminium beaker. Polymerization occurred immediately and a yellow molding was formed.
Example 26 244.3 g of epoxidized soybean oil were mixed with 287.7 g of dimer fatty acid and 0.2 g of trifluoromethane sulfonic acid and heated for 1 hour at 85°C. A solid flexible molding was formed.
Examples 18 to 26 show that a number of oleochemical reaction products are suitable for use as one- or two-component thermoset matrix polymers which can be excellently processed with corresponding natural fibers to form composite materials.

Claims (8)

1. A fiber composite based on natural fibers and a matrix material, characterized in that the matrix material consists essentially of oleochemical thermosets produced from a) ring opening products of epoxidized fats with short-chain olefinically unsaturated carboxylic acids and optionally other olefinically unsaturated comonomers, with the proviso that the unsaturated carboxylic acids are selected from the group consisting of acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid or mixtures thereof, b) anhydride-modified fatty acids which are produced by ene addition or Diels-Alder addition of unsaturated anhydrides onto isolated and/or conjugated double bonds of the starting fatty acids c) reaction products of hydroxyl-containing fats free from epoxide groups with carboxylic anhydrides, the use of aromatic polyisocyanates as constituents of the matrix materials being excluded.

2. A composite material as claimed in claim 1, characterized in that the other comonomers are selected from the group consisting of unsaturated carboxylic acids from the group of acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid or mixtures thereof, their esters of C1-30 alcohols, preferably C10-22 alcohols, and allyl esters or vinyl esters, such as vinyl acetate, vinyl propionate or vinyl versatate, vinyl laurate or styrene, divinyl benzene or mixtures thereof.

3. Composite materials as claimed in claim 1 or 2, characterized in that the carboxylic anhydrides are selected from the group consisting of maleic anhydride, succinic anhydride, citraconic anhydride, itaconic anhydride, phthalic anhydride, trimellitic anhydride, 4-cyclohexane-1,2-dicarboxylic anhydride and naphthalene-1,8-dicarboxylic anhydride, nadic anhydride and mixtures thereof.

4. Composite materials as claimed in claims 1 to 3, characterized in that hydroxyl-containing or hydroxylated triglycerides, diglycerides, dimer diols or mixtures thereof are used as the fats containing hydroxyl groups.

5. Composite materials as claimed in claims 1 to 4, characterized in that the matrix material is a two-component system, the first component being a fatty derivative containing carboxyl groups or/or carboxylic anhydride groups and the second component being a low molecular weight polyol, a hydroxyl-containing fat, a synthetic polyepoxide and/or an epoxide-containing fat.

6. Composite materials as claimed in claims 1 to 5, characterized in that the matrix material is a two-component system, the first component containing the epoxidized fat and optionally a synthetic polyepoxide and the second component being a synthetic carboxylic anhydride, a synthetic polycarboxylic acid, a synthetic polyamine or an aminic fat.

7. Composite materials as claimed in claims 1 to 6, characterized in that the natural fibers are selected from short fibers, sheet-form textiles in the form of nonwovens, needle-punched nonwovens, random laid nonwovens, woven fabrics, laid fabrics or knitted fabrics based on flax, hemp, straw, wood wool, sisal, jute, coconut, ramie, bamboo, bast, cellulose, cotton or wool fibers, animal hair or fibers based on chitin/chitosan and combinations thereof.

8. The use of the composite materials claimed in claims 1 to 7 for the production of structural components for vehicle and aircraft construction, the building industry, window manufacture, the furniture industry, the electronics industry, sports equipment, toys, machine construction, the packaging industry, agriculture or the safety sector.