WO2024141689A1

WO2024141689A1 - Composite material comprising material from wind turbine blades for the production of profiles by pultrusion

Info

Publication number: WO2024141689A1
Application number: PCT/ES2023/070768
Authority: WO
Inventors: Marcos ROS MARTIN; Pedro Miguel Basail Izcue; María Luz REYES GARCIA; María Asunción PADRÓS RAZQUIN; Eva MARTÍNEZ BARRIGÜETE; Stefano Primi; Mónica SÁNCHEZ HERNÁNDEZ; Araceli GÁLVEZ MORENO; Susana QUILES DÍAZ; Enrique NAVARRO LERA; Alfredo GARCÍA FARRE
Original assignee: Acciona Construccion, S.A.; Acciona Generación Renovable, S.A.
Priority date: 2022-12-28
Filing date: 2023-12-20
Publication date: 2024-07-04
Also published as: ES2977135A1

Abstract

The present invention relates to a novel pultruded composite material comprising material from wind turbine blades, as well as the method of producing said material, which is based on a mechanical micronising treatment, and the use of same in the manufacture of structural profiles made of pultrusion fibre-reinforced polymers (frp), and more specifically in the structure of the followers of a photovoltaic plant.

Description

DESCRIPTION

COMPOSITE MATERIAL COMPRISING MATERIAL FROM WIND TURBINE BLADES FOR THE PRODUCTION OF PROFILES BY PULTRUSION

The present invention refers to a new composite material that comprises material from wind turbine blades, its production process based on a micronized mechanical treatment and its use for the manufacture of structural profiles of pultrusion fiber-reinforced polymers (prf), and more specifically in the structure of the followers of a photovoltaic plant.

BACKGROUND OF THE INVENTION

The growing use of renewable energy and the exploitation of numerous parks (wind, photovoltaic, etc.) highlights the need to address how to treat materials at the end of their useful life. Specifically, the dismantling or repowering (or repowering in English) of wind farms has raised awareness of the need to provide a solution to waste.

The forecast of the European employers' association WindEurope is that in the EU about 25,000 tons of blades will become obsolete annually between now and 2025, the date of the first peak. Germany and Spain will be the countries with the highest number of components removed as they are the first to install this technology, followed by Denmark. Italy, France and Portugal will begin to do so at the end of the decade, so the employers' association predicts that the amount will double to 52,000 tons in 2030.

Among the materials used in wind farms, it is the composite material that represents the biggest problem for recycling, due to the nature of its components (normally thermostable resins and continuous glass fibers).

The blades are made up of different areas with different material compositions. The design and typology of the blades varies from one supplier to another, as well as due to the adaptations and improvements made over time. Once the root area where the metal inserts are located is discarded, it would mainly be divided into two types of material combinations: fiberglass laminates (spar caps) and sandwich panels with a foam core made of different materials that can include PVC. , PET or balsa wood (shear Webs and Shell Panels). 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] among them there is the use of fiberglass as a filler additive in cement to reduce loading costs as well as due to low operational and energy costs and not using dangerous materials, once that the reinforced polymer that is part of the blade is separated and crushed. However, currently said powder material faces two problems for its reuse as a filler, firstly, it is not commercially viable due to the low cost of virgin fillers, such as calcium carbonate or silica. And secondly, the level of filler incorporation is quite limited (less than 10% by weight with respect to the polymer matrix) due to the following reasons: deterioration of mechanical properties and increase in processing problems with higher contents (due to the higher viscosity of the compound) [Géraldine Oliveux, Luke O. Dandy, and Gary A. Leeke. "Current status of recycling of fiber reinforced polymers: Review of technologies, reuse and resulting properties" Progress in Materials Science, vol. 72, 2015.]

DESCRIPTION OF THE INVENTION

The inventors have developed a method to incorporate between 10% and 100% by weight with respect to the polymer matrix of a recycled load from a wind turbine blade, as one of the components of the material used to manufacture a pultruded profile, as a filler material in powder state after grinding since there is an improvement in terms of the aging behavior of the composite material compared to the equivalent galvanized steel material used in equivalent profiles; At the same time, the recycled material from the wind turbine blade that replaces part of the resin, avoiding the use of quarry material, reduces the carbon footprint of the whole. Furthermore, once the material is used to obtain a structural profile through pultrusion, said profile improves the behavior of an equivalent metallic or steel profile, in terms of their weight because it is lighter.

In a first aspect, the present invention refers to a composite material of pultruded profiles characterized in that it comprises

• a polymer matrix in a weight percentage of between 25% and 40% with regarding the total composite material;

• a reinforcing material in a percentage by weight of between 75% and 60% with respect to the total composite material;

• a filler material that comprises a crushed compound from wind turbine blades with a grain size between 2 pm and 500 pm, formed by glass and/or carbon fiber and an organic fraction of a polymeric nature, where the percentage of filler material is between 10% and 100% by weight with respect to the polymeric matrix of the pultruded profile; and where the reinforcing material is embedded in the polymeric matrix; the filler material is dispersed throughout the volume of the polymer matrix homogeneously; and where the polymer matrix is a cross-linked polymer.

In a preferred embodiment, the polymeric matrix is a resin with a viscosity of between 100 cps and 4000 cps. Viscosity measurement is performed using a parallel plate rheometer (AR200EX, TA Instruments) operating in rotational mode. It works in inthermal flow mode using 25 mm diameter plates and carrying out the test at a temperature of 23 °C, atmospheric pressure and a rotation speed of 1 rad/s. In a more preferred embodiment, the selected resin is a thermostable resin. . In an even more preferred embodiment, the polymeric matrix is a modified polyester resin. In an even more preferred embodiment, the modified polyester resin is a prepolymer dissolved in methyl methaclate and styrene. Said resin is a resin with the lowest possible viscosity of the commercial ones, which helps to be able to add the greatest amount of filler material and which after adding that filler continues with a low viscosity for use in pultrusion.

In another preferred embodiment the reinforcing material is a glass fiber.

In the present invention, “fiberglass” is understood as any material that includes all formats and compositions of glass fibers composed of: loose or joint filaments, continuous or discontinuous, in thread or woven format in any format forming fabrics or woven and/or nonwoven. Said filaments are composed of a formulation preferably with Silicon oxide combined with any other material in any proportion, and spun by any method to obtain a filament.

In the present invention, “carbon fiber” is understood as any material formed by grouped filaments of carbon in any combination formed by threads, woven and/or non-woven

In a more preferred embodiment the reinforcement material is glass fiber and/or carbon selected from continuous fiberglass, continuous carbon fiber, unidirectional reinforcements or multidirectional composite fabrics or any combination of the above. In a more preferred embodiment, the reinforcing material is a combination of all of the above.

In another preferred embodiment, between 51% and 95% of the filler material has a particle size distribution between 10 pm and 40 pm. Due to the characteristics of the material to be crushed, achieving this granulometry is complex due to its mixed composition. All particle size analyzes of the present invention have been carried out using laser diffraction technology, being able to cover a measurement range between 10 nm and 4 mm and based on the ISO 13320 standard “Particle size analysis - Laser diffraction methods”.

In another preferred embodiment, the fiberglass from the wind turbine blade for the loading material is a “fiberglass” according to the previous definition.

In another preferred embodiment, the amount of organic fraction of a polymeric nature from the wind turbine blade for the loading material is a resin selected from epoxy resin and polyester resin. More preferably it is epoxy resin.

In another preferred embodiment, the percentage of filler material is between 10% and 80% by weight with respect to the polymer matrix of the pultruded profile.

In another preferred embodiment, if between 51% and 95% of the filler material has a particle size between 10 pm and 40 pm, the percentage of additive filler material is between 29% and 31% by weight on the matrix. polymeric. With this particle size distribution, when more than 31% is incorporated, the viscosity greatly increases and prevents processing.

Another aspect of the invention is a procedure for obtaining the pultruded composite material described above, characterized in that it comprises the following steps: a) separate the debris from the composite material of a wind turbine blade and micronize and grind the separated composite material to a smaller size of between 2 pm and 500 pm; b) prepare the polymeric matrix and; c) add the mixture obtained in a) to the mixture obtained in b) and mix between 200 and 1000 rpm, preferably 400 rpm for 10-20 min, preferably 15 min, until a uniform mixture is formed, and add the cross-linking initiation catalysts. between 0.5% and 2% by weight with respect to the total mixture and the dispersant up to 5% by weight with respect to the total mixture; d) heating a pultrusion mold between a temperature of 60°C and 150°C; e) put the mixture obtained in c) in a bath and impregnate a reinforcing material in said mixture continuously, passing it through the heated pultrusion mold of step (d); and f) curing the material obtained from the mold of step (d).

In the present invention, it is understood by “separating the improper composite material of a wind turbine blade” to discard the root area where the metal inserts are, where it is divided into two types of material combinations: fiberglass laminates (spar caps) and sandwich panels with a foam core made of different materials that can include PVC, PET or balsa wood (shear Webs and Shell Panels) and from both the spar caps area is selected.

In a preferred embodiment of the procedure the grinding size of step (a) is between 10 pm and 60 pm. More preferably from 10 pm and 40 pm.

In another preferred embodiment, the polymeric matrix of step (b) is a resin with a viscosity of between 100 cps and 4000 cps. In a more preferred embodiment the selected resin is a thermosetting resin. In an even more preferred embodiment, the polymer matrix is a modified polyester resin. In an even more preferred embodiment, the modified polyester resin is a prepolymer dissolved in methalate and styrene.

In another preferred embodiment the reinforcing material of step (d) is glass and/or carbon fiber. In a more preferred embodiment it is selected from continuous fiberglass, continuous carbon fiber, unidirectional reinforcements or composite fabrics. multidirectional or any combination of the above. In a more preferred embodiment, the reinforcing material is a combination of all of the above.

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 it is a resin selected from epoxy resin and polyester resin. More preferably it is epoxy resin.

In another more preferred embodiment, 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.

In another preferred embodiment, to prepare the polymer matrix of step (b), the components of a modified polyester resin are mixed. In another more preferred embodiment, preparing the polymer matrix of step (b) is carried out by mixing prepolymer dissolved in methylmethacrylate and styrene.

In another preferred embodiment, the mixing of step (c) is through a mechanical process.

A third aspect of the present invention is a profile or load-bearing element characterized in that it comprises the pultruded composite material described above.

In a preferred embodiment, the pultruded composite profile replaces the steel profiles that form the structure of the followers of a photovoltaic plant. In another more preferred embodiment the follower is a horizontal axis. In another even more preferred embodiment, the profile has dimensions between 250x250x25 mm ³ and 100x100x10 mm ³ , and can be used with any combination of fiberglass and/or carbon fiber.

Throughout the description and claims the word "comprises" and its meanings are not intended to exclude other technical characteristics, additives, components or steps. For those skilled in the art, other objects, advantages and features of the invention will emerge partly from the description and partly from the practice of the invention. The following examples and figures are provided by way of illustration, and are not intended that are limiting of the present invention.

BRIEF DESCRIPTION OF THE FIGURES

Fig. 1. Schematic representation of the different elements that make up the reinforcement zone.

Fig. 2. Size distribution curve once micronized.

Fig. 3. Scheme of a pultrusion line.

EXAMPLES

Next, the invention will be illustrated through tests carried out by the inventors, which demonstrate the effectiveness of the product of the invention.

Example 1

Once the improper parts have been separated and the structural part (Fig. 1) of the “spar caps” area has been selected, the micronizing/grinding process is carried out. This grinding of this piece has been carried out in two ways: one way with means of laboratory and another avenue of large-scale professional grinders.

A preferred particle size of the material is achieved between 40 and 10 pm so that it does not affect the viscosity of the resin, where an excessive increase in it prevents pultrusion processing.

The compendium of results obtained allows us to conclude that the viscosity of the mixture depends on both the composition of the load and its granulometry. In terms of filler composition, it has been shown that the use of fillers with lower organic fraction content generates less viscous mixtures, which will allow the incorporation of higher percentages of filler in the mixture while maintaining its processability. Regarding the granulometry of the load used, the need to use loads with wide granulometric profiles has been demonstrated, with sizes between 2 pm and 500 pm, where more than 80% of the load has a size less than 75 pm and whose granulometry may be centered between 10 and 40 pm (Fig. 2). On the other hand, it has been proven that the resin curing process depends on the amount of filler incorporated into the mixture and its granulometry. In general, a shift in curing towards higher temperatures has been observed as we increase the filler content incorporated into the mixture. This displacement to higher temperatures could hinder the correct curing of the piece during the pultrusion process, this being one of the factors that motivate the preparation of pultruded profiles. with 30% load. Therefore, the mixture is prepared by combining the polymer matrix with the rest of the components by electromechanical means. The mixture is composed of a modified polyester resin from manufacturer IN EOS. To do this, mix in the proportions within the range marked by the manufacturer around 95-99% of component A (Modar™ NX 801 P resin, 0.5-3% of the PB peroxide and 0.5-2 % BCC peroxide, which correspond to a degree of fluidity and density suitable for incorporating powder from other materials as a “filler”. Then a load with the micronized/powdered reinforcement material, the shovel powder, of 30 will be added. % load with respect to the total of the material obtained previously, this is incorporated little by little while the mixture is beaten with electromechanical means for its uniform mixing.

On the other hand, changes have been observed in the radical curing processes depending on the granulometry, where the use of finer granulometries generates the appearance of a new radical curing process at temperatures close to 130°C, which in the case of Incorporating filler contents equal to or greater than 50% becomes the predominant curing process.

Next, the pultrusion process is described to obtain the specific profile. Once the mixture is prepared, it is incorporated into the pultrusion process. This consists of different phases, as can be seen in the following image. The different types of glass and carbon fiber are placed at the beginning of the line (1). To carry out the impregnation of the fiber with the matrix, an open bath (2) is used, where the reinforcement is introduced into the impregnation bath where it is mixed with the matrix and the rest of the additives. Once the fiber is impregnated, it passes through a mold where, through the application of temperature, between 60°C and 150°C, the curing of the piece is achieved (3). So that this manufacturing process can work continuously, the profile is extracted from the mold by pulling two presses (4). Finally, the profile is cut to the necessary final dimensions (8-10m length) (5). Below is a table with the mechanical properties of the profile obtained, where A= section of the profile, 1= Moment of inertia, l _T = Moment of Torsion, E= Modulus of elasticity, G= Modulus of Torsion:

Table 1. Mechanical and geometric properties of the profile

Claims

1. A composite material of pultruded profiles characterized in that it comprises

• a polymer matrix in a weight percentage of between 25% and 40% with respect to the total composite material;

• a filler material that comprises a crushed compound from wind turbine blades with a grain size between 2 pm and 500 pm, formed by glass and/or carbon fiber and an organic fraction of a polymeric nature, where the percentage of filler material is between 10% and 100% by weight with respect to the polymer matrix of the pultruded profile; and where the reinforcing material is embedded in the polymer matrix; the filler material is dispersed throughout the volume of the polymer matrix homogeneously; and where the polymer matrix is a cross-linked polymer.

2. Composite material according to claim 1, wherein the polymer matrix is a resin with a viscosity of between 100 cps and 4000 cps.

3. Composite material according to claim 2, wherein the resin is selected from a thermostable resin.

4. Composite material according to claim 3, wherein the polymer matrix is a modified polyester resin.

5. Composite material according to claim 3, wherein the modified polyester resin is dissolved in methylmethacrylate and styrene.

6. Composite material according to any of claims 1 to 4, where the reinforcing material is fiberglass and/or carbon.

7. Composite material according to claim 6, wherein 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.

8. Composite material according to any of claims 1 to 7, where between 51% and 95% of the filler material has a granulometric distribution of a particle size between 10 pm and 40 pm.

9. Composite material according to any of claims 1 to 8, wherein the glass fiber coming from the wind turbine blade for the loading material is a glass and/or carbon fiber selected from continuous fiberglass, carbon fiber continuous, unidirectional reinforcements or multidirectional composite fabrics or any combination of the above.

10. Composite material according to any of claims 1 to 9, wherein the organic fraction from the wind turbine blade for the filler material is epoxy resin.

11. Composite material according to any of claims 1 to 10, where the percentage of filler material is between 10% and 60% by weight with respect to the polymeric matrix of the pultruded profile.

12. Composite material according to claim 11, where if between 51% and 95% of the filler material has a particle size between 10 pm and 40 pm, the percentage of additive filler material is between 29% and 31 % by weight on the polymeric matrix.

13. Procedure for obtaining the pultruded composite material described in any of claims 1 to 12, characterized in that it comprises the following steps: a) separating the improper composite material from a wind turbine blade and micronizing and grinding the separated composite material up to a smaller size of between 2 pm and 500 pm; b) prepare the polymeric matrix and; c) add the mixture obtained in a) to the mixture obtained in b) and mix between 200 and 1000 rpm, preferably 400 rpm for 10-20 min, preferably 15 min, until a uniform mixture is formed, and add the cross-linking initiation catalysts. between 0.5% and 2% by weight with respect to the total mixture and the dispersant up to 5% by weight with respect to the total mixture; d) heating a pultrusion mold between a temperature of 60°C and 150°C; e) put the mixture obtained in c) in a bath and impregnate a material of reinforcement in said mixture continuously by passing it through the heated pultrusion mold of step (d); and f) curing the material obtained from the mold of step (d).

14. Method according to claim 13, wherein the grinding size of step (a) is between 10 pm and 60 pm.

15. Method according to any of claims 9 or 10, step (b) is a resin with a viscosity between 100 cps and 4000 cps.

16. Profile or load element characterized in that it comprises the composite material according to any of claims 1 to 12.

17. Profile according to claim 16, wherein the profile has the structure of the followers of a photovoltaic plant.

18. Profile according to claim 17, where the follower is a horizontal axis.

19. Profile according to claim 18, wherein the profile has dimensions between 250x250x25 mm ³ and 100x100x10 mm ³ , and can be used with any combination of fiberglass and/or carbon fiber.