Revaluation of wind turbine blade waste in the footwear industry

Abstract

The present invention relates to the composite material obtained by incorporating micronised material from wind turbine blade waste of different grain sizes as a filler on elastomeric substrates, using different technologies for incorporation purposes depending on the base substrate used and the resulting improvement of the physical-mechanical properties of the final composite material, method for obtaining same and use thereof as a footwear sole material.

Description

[0001] DESCRIPTION

[0002] Recycling of wind turbine blade waste in the footwear industry

[0003] The present invention relates to the composite material obtained by incorporating micronized material from wind turbine blade waste of different granulometry as a filler on elastomeric substrates, using different technologies for incorporation depending on the base substrate used and its improvement of the physical-mechanical properties of the final composite material, its production process and its use as a material for footwear soles.

[0004] BACKGROUND OF THE INVENTION

[0005] The growing use of renewable energy and the operation of numerous wind farms (wind, photovoltaic, etc.) highlight the need to address how materials are treated at the end of their useful life. Specifically, the decommissioning or repowering of wind farms has raised the need to address waste.

[0006] The European wind industry association WindEurope forecasts that approximately 25,000 tons of blades will become obsolete annually in the EU between now and 2025, the date of the first peak. Germany and Spain will be the countries with the highest number of components retired, as they are the first to implement this technology, followed by Denmark. Italy, France, and Portugal will begin doing so by the end of the decade, so the association predicts that this figure will double to 52,000 tons by 2030.

[0007] Among the materials used in wind farms, composite materials pose the greatest recycling challenges due to the nature of their components (usually thermosetting resins and continuous glass fibers).

[0008] Blades are made up of different areas with different material compositions. The design and typology of blades vary from supplier to supplier, as well as due to adaptations and improvements made over time. Once the root area containing the metal inserts is eliminated, the blades are primarily divided into two types of material combinations: fiberglass laminates (spar caps) and sandwich panels with a foam core made of various materials, including PVC, PET, or balsa wood (shear webs and shell panels).

[0009] There are different strategies to recycle the materials present in wind turbine blades [Daniel Martinez-Marquez et al., State-of-the-art review of product stewardship strategies for large composite wind turbine blades, Resources, Conservation & Recycling Advances, Volume 15, (2022) 200109, 444],

[0010] On the other hand, footwear is the generic name for any garment that covers and protects the foot, and sometimes also the leg. Footwear's purpose is to protect the foot from uneven terrain and inclement weather. Therefore, it is a vitally important garment for people's daily lives. Today, there are a wide variety of types of footwear, and depending on the type, it will be composed of different parts.

[0011] The sole of a shoe is one of the most important parts of the shoe, as it comes into direct contact with the ground and, therefore, plays a key role in providing traction, cushioning, and protection. This is why it is the most durable part of the shoe. Soles come in different shapes depending on the shoe, providing different characteristics for each. Different types of materials are used in the manufacture of soles, each with its own characteristics and advantages. In addition to the base material, they are also mixed with filler, either padding and / or reinforcement.The manufacturing process for each sole will be defined by the base material used: if the base material is rubber, the method will involve intensive mixing, usually in a Banbury mixer, followed by calendering and vulcanization in a mold to obtain the sole; if the base material is TR, TPU, or PVC, the method will be extensive, followed by extrusion and injection molding to obtain the sole.

[0012] The loads used as fillers have no other function than to make the polymer in question cheaper; they do not offer improvements in the physical-mechanical properties of the materials, although they may affect other properties such as processability, antimicrobial capacity, temperature resistance, improved fire behavior, etc. Examples: - Calcium carbonate (CaCO3)

[0013] - Titanium dioxide (T¡02)

[0014] - Sulfates (Barium, Calcium)

[0015] The fillers used as reinforcement, apart from providing some of the properties discussed in the case of fillers, also affect the physical-mechanical properties of the materials.

[0016] - Spherical silica (S¡02): Material with the same composition as fiberglass, but differing in geometry. In these spheres, particle size is prioritized; the smaller the particle size, the greater the reinforcement it generates in the material. (Up to 30-40% can be added.)

[0017] - Clays (kaolins, bentonites): Aluminum silicates of various types (primarily used in PVC systems; the smaller the particle size, the greater the reinforcement). They improve abrasion and tear resistance. Their effect depends on the chemical modification to which they are subjected.

[0018] - Carbon black: mainly used in tire manufacturing (40-50%).

[0019] - Cellulosic natural fibers: Cellulosic fibers such as flax, jute, hemp, or coconut are used as reinforcement. They must be treated to improve their adhesion to the plastic matrix. Due to their fibrillar geometry (length much greater than diameter), they improve the rigidity of materials, increasing their tensile strength while decreasing their flexibility.

[0020] - Natural protein fibers: such as wool and silk. Their main components, keratin and fibroin, respectively, are protein chains with a very large length-to-diameter ratio. They are less commonly used than cellulosic fibers, but there are studies showing that using these materials as reinforcements increases tensile strength by up to 100% compared to the unsaturated material.

[0021] However, to date, there is no affinity between the particles and the plastic material when using chopped fiberglass as a filler in thermoplastic materials, so surface functionalization is always required to generate such affinity and to use fiberglass as a filler material directly.

[0022] DESCRIPTION OF THE INVENTION In a first aspect, the present invention relates to a composite material for shoe soles characterized in that it comprises:

[0023] • a particulate additive material, wherein said material comprises at least 70% by weight of glass fiber relative to the total additive material and up to 30% by weight of epoxy resin relative to the additive material, where the additive material has an average particle diameter of between 10 and 40 pm, measured by scanning electron microscopy (SEM);

[0024] • a matrix comprising or consisting of an elastomer; where the additive material is homogeneously dispersed throughout the elastomer matrix, and where the weight ratio of the additive material to the elastomer is between 0.5% and 25%.

[0025] The advantages of this composite material are that it not only meets the requirements for particle size (<40 µm), but also offers a fairly homogeneous particle size distribution, with a graph that presents a fairly Gaussian shape centered at a size of 20 µm. It demonstrates good compatibility with wind turbine blade waste particles, improving some of its mechanical properties, such as strength, without compromising its elongation. Another advantage of this material is its surface irregularity in various aspects such as its geometry and chemistry. An irregular surface geometry results in a higher surface-to-volume / specific surface area ratio, which always favors surface reactions.

[0026] On the other hand, the peculiarity of this material in terms of its surface chemistry lies in the fact that a large part of the particles that make up the waste have polymeric components adhered to them. This improves the compatibility between the particles and the polymer, making surface functionalization of the waste unnecessary to ensure good compatibility between the phases.

[0027] On the other hand, the presence of a variable percentage of resin makes the additive lighter compared to a reinforcement composed solely of chopped fiberglass.

[0028] Resin is less dense than fiber, so the higher the percentage of resin in the total waste, the more this fact will be increased.

[0029] Additionally, a high percentage of elastomer relative to the total additive material has two positive effects on the reinforcement behavior compared to the use of chopped fibers.

[0030] - The first of these is the improvement in the compatibility of the waste with the polymer matrix, without the need to superficially treat the fiber.

[0031] - The second is the reduction in weight compared to traditional chopped fiberglass, since the density of the polymer is lower than that of the fibers.

[0032] In a preferred embodiment the additive material comprises fiberglass between 70% and 80% by weight.

[0033] In another preferred embodiment, the additive material comprises epoxy resin between 20% and 30% by weight.

[0034] In another preferred embodiment, the elastomer is selected from thermoplastic polyurethane (TPU), thermoplastic rubber (TR) and vulcanized rubber.

[0035] In a more preferred embodiment, the vulcanized rubber is selected from styrene-butadiene rubber and nitrile-butadiene vulcanized rubber. It is observed that the micronized wind turbine blade waste material (size < 40 µm) acts as reinforcement with the two rubber materials of different natures (SBR and Nitrile) and different levels of additives (0, 5, 10, and 25%). Regarding the tensile characterization results (elongation / rupture), the elastic modulus of the materials increases in the same way as the degree of additives. The other elastic properties increase similarly or are not significantly negatively affected. Therefore, based on these results, it is believed that the rubber material could accept greater additives without losing properties. The maximum bending stress results obtained support the thesis that the micronized material acts as a reinforcing load on the different rubber materials.

[0036] In another preferred embodiment, if the elastomer is TR, the weight ratio of the additive material to the elastomer is between 2.5% and 5%. Within this range, the physical and mechanical properties are maintained; however, above 5%, although compatibility with the additive material persists, the properties decrease slightly, both in strength and ductility, that is, their elongation and rigidity decrease.

[0037] In another preferred embodiment, if the elastomer is vulcanized rubber, the weight ratio of the additive material to the elastomer is between 0.5% and 25%. More preferably, it is between 0.5% and 5%.

[0038] Another aspect of the invention is a method for obtaining a composite material for a shoe sole, characterized in that it comprises the following steps: a) separating the unsuitable materials from the composite material of a wind turbine blade and micronizing and grinding, preferably by milling, the separated composite material to an average particle diameter size of between 10 pm and 40 pm, where the composite material comprises 70% by weight of fiberglass and up to 30% epoxy resin; b) mixing between 0.5% and 25% by weight of the material obtained in step (a) with an elastomer material selected from TPU, TR, rubber, PVC, EVAs, polycarbonates, polyolefins and polyamides, by means of a mixing technique selected from extrusion, industrial mixer and calendering; c) mechanically forming the composite material from the mixture obtained in step (b), where: if the elastomer is selected from TPU, TR, PVC, EVAs, polycarbonates, polyolefins and polyamides, the mixture obtained in (b) is extruded and subsequently injected into a mold; or if the elastomer is rubber, the mixture obtained in (b) is vulcanized, preferably in a hot plate press at a temperature between 100 °C and 200 °C, and a pressure between 6 bar and 10 bar.

[0039] In the present invention, “separating the unsuitable materials from the composite material of a wind turbine blade” means discarding the root area where the metal inserts are located, where it is divided into two types of material combinations: fiberglass laminates (spar caps) and sandwich panels with a foam core of different materials that may include PVC, PET or balsa wood (shear Webs and Shell Panels) and from both the spar caps area is selected.

[0040] In another preferred embodiment, the composite material from the wind turbine blade in step (a) comprises a glass and / or carbon fiber and an organic fraction of a polymeric nature, preferably a resin selected from epoxy resin and polyester resin. More preferably, it is epoxy resin.

[0041] In another more preferred embodiment of the method, the glass and / or carbon fiber is selected from continuous glass, continuous carbon fiber, unidirectional reinforcements or multidirectional composite fabrics or any combination of the above.

[0042] In another preferred embodiment of the process, the polyolefin elastomeric material is selected from Polyethylene (PE), polypropylene (PP), low-density PE, high-density PE, polystyrene (PS), polybutene.

[0043] In another preferred embodiment of the process, the polyamide elastomeric material is Nylon.

[0044] In another preferred embodiment of the process, the elastomeric material is selected from TPU, TR and Rubber.

[0045] In another preferred embodiment of the process, if the elastomeric material is selected from TPU, TR, the mixing in step (b) is selected from extrusion and calendering, preferably extrusion. In a more preferred embodiment, the shaping in step (c) is carried out by injecting the composite material obtained in step (b) at a temperature of between 160 °C and 200 °C into a mold with the desired shape and morphology.

[0046] In another preferred embodiment of the process, if the selected elastomeric material is rubber, the mixing in step (b) is carried out using an industrial mixer, preferably a Banbury type mixer. In a more preferred embodiment, the shaping in step (c) is carried out by calendering the composite material obtained in step (b) and subsequent thermoforming and vulcanization, preferably in a hot plate press at a temperature between 100 °C and 200 °C, and a pressure between 6 bar and 10 bar in a mold with a thickness of between 3 and 7 mm with the desired shape and morphology in the presence of sulfur in an amount of between 1% and 2.2% by weight with respect to the total mixture of composite material obtained in (b) if the elastomer is rubber.

[0047] A third aspect of the invention is a shoe comprising a sole characterized in that the sole comprises the composite material described above. Preferably, the shoe is a sneaker.

[0048] A fourth aspect of the present invention is the use of the composite material described above as a footwear sole, preferably where the footwear is a sneaker.

[0049] Throughout the description and claims, the word "comprise" and its variants are not intended to exclude other technical features, additives, components, or steps. For those skilled in the art, other objects, advantages, and features of the invention will be apparent in part from the description and in part from the practice of the invention. The following examples and figures are provided for illustrative purposes only and are not intended to limit the scope of the present invention.

[0050] BRIEF DESCRIPTION OF THE FIGURES

[0051] Fig. 1. TGA result of wind turbine blade material.

[0052] Fig. 2. Infrared spectrum of the wind turbine blade resin.

[0053] Fig. 3. Material obtained after the milling process in SEM

[0054] Fig. 4. Particle size distribution of the sample resulting from the milling process

[0055] Fig. 5. Morphologically characterized by optical microscopy of the composite material comprising TPU and TR elastomer.

[0056] Fig. 6. Morphologically characterized by optical microscopy of the composite material comprising SBR and NBR vulcanized rubber elastomer.

[0057] Fig. 7. Maximum stress results for the composite material comprising TPU and TR elastomer

[0058] Fig. 8. Maximum stress results for the composite material comprising rubber elastomer.

[0059] Fig. 9. Flexural test results for the composite material comprising TPU and TR elastomer

[0060] Fig. 10. Flexural test results for the composite material comprising rubber elastomer.

[0061] Fig. 11. Thermogravimetric analysis for the composite material comprising TPU and TR elastomer

[0062] EXAMPLES

[0063] The invention will then be illustrated by tests carried out by the inventors, which demonstrate the effectiveness of the product of the invention.

[0064] Example 1. Characterization of wind turbine blade material

[0065] Composition of wind turbine blade material

[0066] The calcination results of the sample indicate that the resin content is approximately 26% of the total mass of the composite, with fiber accounting for the remaining 74%.

[0067] These results are consistent with those observed after subjecting the sample to thermogravimetric analysis (see Figure 1). The degradation curve obtained indicates that the decomposition of the polymer matrix occurs in two main stages. The first consists of two successive weight losses of 4% and 14%, with maximum degradation temperatures of 369°C and 440°C, respectively. In the second stage, a weight loss of 5.7% is observed, with a maximum degradation temperature of 543°C. This decomposition process is consistent with the decomposition profiles published in the literature for epoxy resins.

[0068] At the end of heating at 950 °C, a solid residue of 76% by weight is obtained, which corresponds to the glass fiber content, the polymer content being equal to 24% by weight, a result that agrees with the calcination analysis.

[0069] On the other hand, the resin was also subjected to analysis by IR spectroscopy (see Figure 2), the results confirm that it is an epoxy type resin, specifically an epoxy resin based on diglycidyl ether of bisphenol A (DGEBA). The characteristic bands of DGEBA are observed: i) at 1505.8 cm-i and 1457.4 cm-i, signals associated with the stretching vibrations of the C=C double bonds of the aromatic ring, i) 1293 cm-i, rocking and twisting vibrations of the CH2 groups, iii) 1181 cm-i, bending vibration of the C-H bonds of the aromatic ring, iv) 1028.7 cm-i, symmetric stretching of the ether group and v) 831 cm-i, twisting of the C-H bonds of the aromatic ring.

[0070] Morphological characterization of the blade milling material

[0071] The material generated during the milling process can be seen in Figure 3. At first glance, it appears quite homogeneous and has a relatively small particle size, so it was subjected to the corresponding morphological characterization. In the SEM images obtained, it can be seen that the vast majority of the particles present in the sample have a fairly uniform size distribution. Two size distribution patterns are observed: the first of approximately 10 microns and a second of approximately 20 microns, the latter being much more abundant. These values ​​are in line with expectations, as well as with the specifications required to proceed with the extrusion tests of the fiber-polymer hybrid. The particle size distribution was evaluated twice using different samples to validate the result.The particle size curve obtained for the five measurements is shown below. It shows two particle size families (6 microns and 20 microns), with an average particle size of 19 microns (Figure 4). Based on the results obtained from the material characterization and the good size distribution observed, it is considered the optimal material for use as a filler in elastomeric matrices.

[0072] Example 2. Incorporation of wind turbine blade material into TPU and TR elastomeric matrices

[0073] A twin-screw extruder was used to incorporate the blade waste material into the TR and TPU thermoplastics. A rotational speed of 25 rpm was established, and a temperature profile was set according to the technical specifications for each material. The temperatures refer to the different zones of the extruder, from the feed zone to the nozzle: TPU: 170°C, 175°C, 180°C, and 185°C.

[0074] TR: 160°C, 165°C, 170°C and 175°C.

[0075] The different materials added with the shovel waste at the concentrations indicated in the test matrix were transferred to the injection molding machine, where they were injected into molds in the shape of the test pieces for subsequent characterization.

[0076] The increase in color in the test specimens is consistent with the increase in residue concentration in the different matrices. The exceptions are the TR2.5 and TR5 test specimens, as they were made with a different batch of milling powder and the polymer composition may be slightly different.

[0077] The materials were morphologically characterized using optical microscopy to observe the distribution of the blade milled material particles in the polymer matrix (see Figure 5), where a homogeneous distribution of particles was observed throughout the polymer matrix. The number of particles observed also increases with the level of additive.

[0078] Example 3. Incorporation of wind turbine blade material into rubber elastomeric matrices

[0079] Two rubber materials were selected, the first based on a copolymerization of styrene and butadiene (SBR) and the second on butadiene and acrylonitrile (NBR).

[0080] The incorporation of the wind turbine blade milling material into the rubber matrices was carried out using a Banbury type mixer, a mixing speed of 110 rpm was established for 6 minutes: • 2 minutes of chewing and melting of the rubber

[0081] • 3 minutes of mixing with the blade milling material and process aid additives

[0082] • 1 minute of mixing with the vulcanization system.

[0083] NBR material:

[0084] SBR material:

[0085] The material obtained in the Banbury mixer is subsequently calendered to further improve the homogenization of all the components, obtaining perfectly homogeneous sheets of additive material.

[0086] The rubber material then undergoes a thermoforming process, which, in the presence of sulfur, triggers the vulcanization reaction. The material is vulcanized in a hot-platen press at 150°C and 8 bars of pressure, in a 4 mm thick mold measuring 100 x 100 mm.

[0087] Taking as a reference the unadditive rubber materials (NBR and SBR for each series of samples), an increasing darkening and opacity of the sample can be observed as the amount of blade waste material in its composition increases.

[0088] The materials were morphologically characterized using optical microscopy to observe the distribution of the blade milled material particles in the polymer matrix (see Figure 6), where a homogeneous distribution of particles was observed throughout the polymer matrix. The number of particles observed also increases with the level of additive.

[0089] Example 4. Mechanical characterization

[0090] The physical and mechanical properties of the materials obtained have been thoroughly studied. The influence of the additive percentage on the parameters most influential in the mechanical properties of elastomeric footwear sole materials has been studied:

[0091] • Tensile Strength and Modulus, ac / ASTM D3039

[0092] • Flexural Strength and Modulus, ac / ASTM D790

[0093] • Elongation at break, ac / ASTM D3039

[0094] Tensile Strength and Modulus + Rupture, ac / ASTM D3039

[0095] The tests were carried out in compliance with the specifications of ASTM D3039, including aspects related to the size and shape of the specimens. The stroke speed was kept constant at 15 mm min-1. The load cell used was 5 kN.

[0096] Results of TR and TPU test tubes

[0097] *In this test the test piece did not break, the elongation reached the maximum of the equipment, in this case 1,500%.

[0098] Regarding the maximum stress results (see Figure 7), for the TPU we observe that the material added with 10% of wind turbine blade waste material does not present significant changes with respect to the unadditive sample (the samples do not really break, so probably at higher stresses some difference could be seen), while in the TR material, at the lowest levels of additivation (2.5 and 5% (m / m)), the properties are maintained, but when the concentration of waste within the thermoplastic material increases, a decrease occurs. On the other hand, when the materials are added with 25% of material, in both cases a significant decrease is observed in both the maximum elongation and the breaking stress.

[0099] Regarding the modulus of elasticity (Young's modulus), i.e., the stiffness of the material, one would expect the addition of the residue to increase the stiffness of the composites, as can be seen in the case of the TPU material. However, in the TR material, the opposite phenomenon is observed: as the amount of residue increases in the composites, their stiffness decreases (Young's modulus decreases). This behavior may be due to the low compatibility between the polymer and the residue, which may cause the incorporated particles to not adhere well to the matrix, leaving them free in the form of powder, which can cause a slipping or plasticizing effect.

[0100] Results of rubber test tubes

[0101] Regarding the elongation / fracture results (see Figure 8), it can be observed that the additive material acts as reinforcement, and that its resistant properties are enhanced (higher Young's modulus and maximum stress) without significantly affecting the ductile properties. Based on the observations, it is believed that the material can be added with a larger amount of wind turbine blade waste, since the properties do not experience the characteristic drop in these properties observed when this type of matrix is ​​added in excess.

[0102] Flexural Strength and Modulus, ac / ASTM D790

[0103] The flexural tests were carried out in compliance with the specifications of the corresponding standard, ASTM D790, including aspects relating to the size and shape of the specimens. The constant speed was 10 mm min-1, the distance between supports was 60 mm, and the load cell used was 5 kN for the TR and TPU specimens and 1 kN for the rubber specimens.

[0104] Results of TR and TPU test tubes

[0105] The flexural results (see Figure 9) corroborate the results obtained in the tensile / fracture test. In the case of TPU, the normal behavior in this type of case follows, i.e., stiffness increases with the amount of fiberglass, while with TR the effect is the opposite, the material becomes less rigid.

[0106] Results of rubber test tubes

[0107] The results of the bending test (see figure 10) have a very high associated uncertainty due to the high flexibility of the materials developed, since at such low values ​​of forces obtained (< 1 N), the error associated with the measurement is comparable to the value obtained.

[0108] Regarding the maximum tension obtained for each additive-coated rubber material, the results confirm the reinforcing role that the micronized blade material load provides to the rubber material, as this increases as the level of additives in the material increases.

[0109] Thermogravimetric analysis

[0110] The results obtained by thermogravimetry (see Figure 11) allow to certify the correct additive content of the materials, since the quantity of material observed at high temperatures (> 500°C) quantitatively coincides with the additive content (~ 20 % for materials with 25 % additive content, ~ 7 - 8 % for materials with 10 % additive content and practically 0 for thermoplastic materials without additives). Small deviations may be due to contaminants and / or small instrumental error.

Claims

CLAIMS 1. A composite material characterized in that it comprises: a) a particulate additive material, said material comprising at least 70% by weight of glass fiber with respect to the total additive material and up to 30% by weight of epoxy resin with respect to the additive material, where the additive material has an average particle diameter of between 10 and 40 pm, measured by scanning electron microscopy; b) a matrix comprising or consisting of an elastomer; where the additive material is homogeneously dispersed throughout the elastomer matrix, and where the weight ratio of the additive material to the elastomer is between 0.5% and 25%.

2. Composite material according to claim 1, wherein the additive material comprises fiberglass between 70% and 80% by weight.

3. Composite material according to any of claims 1 or 2, wherein the additive material comprises epoxy resin between 20% and 30% by weight.

4. Composite material according to any of claims 1 to 3, wherein the elastomer is selected from thermoplastic polyurethane, thermoplastic rubber and vulcanized rubber.

5. Composite material according to claim 4, wherein the vulcanized rubber is selected from butadiene-styrene rubber and nitrile-butadiene vulcanized rubber.

6. Composite material according to claim 4, wherein if the elastomer is thermoplastic rubber the weight ratio of the additive material to the elastomer is between 2.5% and 5%.

7. Composite material according to any of claims 4 or 5, wherein if the elastomer is vulcanized rubber, the weight ratio of the additive material to the elastomer is between 0.5% and 5%.

8. Method for obtaining a composite material according to claims 1 a 7 characterized in that it comprises the following steps: a) separating the improper ones from the composite material of a wind turbine blade and micronizing and grinding, preferably by milling, the separated composite material to an average particle diameter size of between 10 pm and 40 pm, where the composite material comprises 70% by weight of fiberglass and up to 30% epoxy resin; b) mixing between 0.5% and 25% by weight of the material obtained in step (a) with an elastomeric material selected from TPU, TR, Rubber, PVC, EVAs, polycarbonates, polyolefins and polyamides, by means of a mixing technique selected from extrusion, industrial mixer and calendering; c) mechanically forming the composite material from the mixture obtained in step (b), where: if the elastomer is selected from TPU, TR, PVC, EVAs, polycarbonates, polyolefins and polyamides, the mixture obtained in (b) is extruded and subsequently injected into a mold;or if the elastomer is rubber, the mixture obtained in (b) is vulcanized, preferably in a hot plate press at a temperature between 100 °C and 200 °C, and a pressure between 6 bar and 10 bar; 9. Method according to claim 8, the composite material from the wind turbine blade of step (a) comprises a glass and / or carbon fiber and an organic fraction of a polymeric nature, preferably a resin selected from epoxy resin and polyester resin, preferably epoxy resin.

10. Method according to any of claims 8 or 9, wherein if the elastomeric material is selected from TPU, TR the mixing of step (b) is selected from extrusion and calendering.

11. Method according to claim 10, wherein the shaping of step (c) is carried out by injecting the composite material obtained in step (b) at a temperature between 160 °C and 200 °C into a mold with the desired shape and morphology.

12. Method according to any of claims 8 or 9, wherein if the selected elastomeric material is rubber, the mixing of step (b) is carried out using an industrial mixer, preferably the mixer is a Banbury type mixer.

13. Method according to claim 12, wherein the shaping of step (c) is carried out by calendering the composite material obtained in step (b) and subsequent thermoforming and vulcanization in a hot plate press.

14. Method according to claim 13, wherein the vulcanization is carried out at a temperature between 100 °C and 200 °C, and a pressure between 6 bar and 10 bar in a mold with a thickness of between 3 and 7 mm with the desired shape and morphology in the presence of sulfur in an amount of between 1 and 2.2% by weight with respect to the total mixture of composite material obtained in (b).

15. Footwear comprising a sole characterized in that the sole comprises the composite material according to any of claims 1 to 7.

16. Footwear according to claim 15, wherein the footwear is a sneaker.

17. Use of the composite material according to claims 1 to 7 as a footwear sole.

18. Use according to claim 17 wherein the footwear is a sneaker.