Composites based on charcoal and polymer binders

Abstract

The subject of the present invention is a composite material comprising charcoal powder dispersed in a polymer matrix, the polymer comprising polyfurfuryl alcohol (PFA). The invention also relates to shaped objects comprising this composite material, their use and methods of manufacture.

Description

[Technical Field]

[0001] The present invention relates to a composite material comprising charcoal powder dispersed in a polymer matrix, the polymer comprising polyfurfuryl alcohol (PFA). The present invention also relates to shaped articles comprising the composite material, their uses and methods for their manufacture. [Background technology]

[0002] Currently, various approaches to controlling atmospheric carbon dioxide content are being proposed and investigated. One of the most relevant approaches is reducing atmospheric carbon dioxide content through carbon (carbon dioxide) sequestration and storage. For such an approach, it is important to provide functional materials that are valuable and highly acceptable to users, and are suitable for the efficient storage of large amounts of carbon. Building materials are particularly relevant in this regard, since the building and construction sector is responsible for a large portion of the world's total carbon dioxide emissions. Furthermore, building materials are used in large quantities and have the potential to store large amounts of carbon over long periods of time. The quantitative effect of CO2 storage can be calculated as the global warming potential (GWP).

[0003] Charcoal (biochar) is produced by thermal degradation (pyrolysis) of biomass in an oxygen-controlled atmosphere. Charcoal is widely used in agriculture to reduce drainage and increase soil fertility and crop yields. Because charcoal is based on carbon from the atmosphere, it may be an interesting material for carbon sequestration and storage. Compared to other carbon-storing organic matter, such as carbohydrates, charcoal exhibits high recalcitrance, which prevents the stored carbon from re-entering the atmosphere after decomposition. Growing data demonstrates that charcoal may remain stable for hundreds or even thousands of years under normal environmental conditions.

[0004] However, to date, the use of biochar for permanent carbon storage in functional materials has been limited due to various drawbacks of charcoal-based materials. For example, composite materials containing biochar as a filler have been proposed in the art. However, such composite materials are often insufficient for construction applications due to undesirable properties such as low thermal and chemical resilience and high water absorption. Furthermore, such composite materials typically require polymer binders for stability, and polymer binders have a poor environmental footprint.

[0005] German Patent Application No. 3004466A1 describes a method for producing porous casting cores from carbon and a binder. However, the product is merely an intermediate product for combustion in a casting mold. Given the high porosity (over 80%) and binder content (less than 1%), a stable binder matrix cannot be formed and the mechanical stability is low. Furthermore, it is proposed to use carbon of fossil origin, such as coke or mineral coal. This method and composite are neither intended nor suitable for carbon storage in a stable functional material.

[0006] WO 2017 / 089500 A2 relates to the production of composite materials containing carbon and a binder. In the production process, a porous green body is prepared by firing a mixture of carbon and a first binder. This fired green body forms a porous carbonaceous matrix. The porous green body is then impregnated with a second binder resin. The carbon is derived from fossil sources, such as coke or coal. Furthermore, impregnating a preformed carbonaceous green body with a liquid binder has various drawbacks. Because it is generally difficult to uniformly impregnate the fired green body with the binder, the product may contain voids and domains with no or little binder. To penetrate the micropores and achieve uniform distribution, the binder must have a low viscosity, resulting in only partial filling of the pores after solvent removal. Furthermore, shrinkage of fired products is a known problem, making it difficult to obtain fired green bodies with precise and uniform shapes. The process is also inflexible, as the carbon to binder resin ratio and product shape cannot be easily adjusted. The environmental footprint of the product is poor due to the fossil raw materials and intermediate firing step at high temperatures. Overall, the method and composite are not intended or suitable for carbon sequestration in stable functional materials.

[0007] WO 2021 / 115636 A1 relates to combinations of filler materials and binders. Essentially, it proposes combining every conceivable filler with every conceivable binder. This disclosure is extremely broad and merely speculative, without any practical examples or even relevant theoretical examples. Such a non-enabling disclosure fails to provide relevant guidance to those skilled in the art. The many unrelated components and speculative applications are merely an invitation to undertake a research program.

[0008] Roudsari et al., "A statistical approach to develop biocomposites from epoxy resin, poly(furfuryl alcohol), poly(propylene carbonate), and biochar," 2017, J. Appl. Pol. Sci., 134, 38, 45307, discloses composites based on epoxy resin and poly(propylene carbonate) (PPC), containing relatively small amounts of biochar and poly(furfuryl alcohol), prepared using triethylenetetramine as a curing agent. The authors conclude that to obtain good mechanical properties, PPC should be added to the epoxy / PFA matrix, but the amount of biochar should be reduced to 5% or even less (p. 2017, right column). Such composites and their manufacture are relatively complex and expensive. Furthermore, the inclusion of amine additives in such composites is undesirable. Another drawback is the relatively high environmental footprint of the composites.

[0009] Chinese Patent No. 101293644B relates to a metal foam part having an inner surface coated with porous carbon, which is suitable as a catalyst. It is obtained by immersing the porous metal part in a dispersion of precursor compounds, followed by a calcination process to convert the carbonaceous precursor into a carbon material. The precursor solution contains a thermosetting resin and a carbon material, such as activated carbon or carbon nanotubes. This document does not relate to a composite material made from a polymer matrix in which a carbon material is dispersed.

[0010] EP 4032955 A1 relates to fiber-reinforced composites obtained from a radically curable mixture containing a curable thermosetting resin, a curing agent, and a filler. Preferably, the thermosetting resin is an unsaturated polyester resin, and the curing agent is typically a peroxy compound. The composition and manufacturing method are relatively complex and expensive, while having a relatively high environmental footprint.

[0011] In view of the shortcomings of the prior art, there is a continuing need for improved and efficient methods and products for efficient and permanent carbon storage. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] German Patent Application Publication No. 3004466A1 [Patent Document 2] International Publication No. 2017 / 089500A2 Brochure [Patent Document 3] International Publication No. 2021 / 115636A1 Brochure [Patent Document 4] Chinese Patent No. 101293644B [Patent Document 5] European Patent Application Publication No. 4032955A1 [Non-patent literature]

[0013] [Non-Patent Document 1] Roudsari et al., “A statistical approach to develop biocomposites from epoxy resin, poly(furfuryl alcohol), poly(propylene carbonate), and biochar”, 2017, J.Appl.Pol.Sci., 134, 38, 45307. Summary of the Invention [Problem to be solved by the invention]

[0014] The problem underlying the present invention is to provide new materials, uses and methods that overcome the problems outlined above. Specifically, the problem is to provide improved materials that have a favorable environmental footprint and global warming potential (GWP). A specific problem is to provide materials that have a negative carbon dioxide balance and can be used as carbon sinks to store carbon sequestered from the atmosphere.

[0015] Providing such new materials, e.g., building materials, that are suitable for long-term storage in large quantities is a particular challenge.

[0016] It is a further object of the present invention to provide such a material that has high stability, including thermal, mechanical and chemical stability, so that the carbon storage effect can be achieved over a long period of time. The material should remain stable at high temperatures and preferably be flame retardant or fire resistant.

[0017] A further object of the present invention is to provide such materials that are readily obtainable from conventional raw materials by relatively simple methods. These materials should be available at low cost and suitable for mass production, since only then can relevant amounts of carbon sequestration and significant environmental impact be achieved. In contrast, the present invention does not provide niche products that can only be obtained from rare materials or by complex methods. [Means for solving the problem]

[0018] Surprisingly, it has been found that the problems underlying the present invention are overcome by the composite materials, shapes, uses and methods set forth in the claims. Further embodiments of the present invention are outlined throughout the specification.

[0019] The subject of the present invention is a composite material comprising charcoal powder dispersed in a polymer matrix, the polymer comprising polyfurfuryl alcohol (PFA), the composite material comprising 25 to 90% by weight of charcoal and 10 to 75% by weight of polyfurfuryl alcohol.

[0020] Polyfurfuryl alcohol (furan resin, CAS 25212-86-6) is a polymer typically obtained by polycondensation of furfuryl alcohol in the presence of a weak acid. The primary product of such a polycondensation reaction is a linear polymer. However, it is known in the art that some alternative linkages may be formed during polycondensation. PFA is a liquid polymer at room temperature. Preferably, furfuryl alcohol and PFA are biobased, meaning they are derived from biomass. In the art, the building block furfuryl alcohol is typically produced industrially by hydrogenation of furfural, which can be produced from waste biomass such as corn cobs or sugarcane. PFA from biomass building blocks has a superior environmental footprint.

[0021] Charcoal is a lightweight black carbon material produced from organic materials, primarily wood or other plant materials, in the presence of small amounts of oxygen in a process called pyrolysis. The resulting charcoal can be ground or crushed into a fine powder.

[0022] The composite material is characterized by a polymer matrix containing PFA. In a preferred embodiment, the polymer matrix consists of PFA. This means that the matrix does not contain another matrix-forming polymer, although the presence of functional additives is not excluded. In a preferred embodiment, the polymer matrix is ​​cured and / or crosslinked. PFA essentially has the properties of a thermosetting polymer. When heated for a sufficient period of time, PFA crosslinks and hardens. This means that a reaction occurs in which different polymer chains are covalently bonded. Overall, a three-dimensional polymer matrix is ​​formed. The addition of an additional crosslinking agent is not required, but a crosslinking agent can be added if desired.

[0023] The charcoal powder is dispersed throughout a continuous polymer matrix. Thus, the particles or particle agglomerates are embedded in the polymer matrix. Depending on the ratio of charcoal powder filler to PFA binder and the degree of mixing, the charcoal particles or charcoal particle agglomerates may contact each other. In terms of the polymer matrix and dispersed particles, this structure is fundamentally different from materials in the art formed by impregnating a fired green body with a liquid binder.

[0024] The use of charcoal in such composites is highly advantageous for environmental reasons, since 1 kg of charcoal contains approximately 680-820 grams of carbon, which is equivalent to approximately 2.5-3 kg of carbon dioxide. Thus, if the charcoal is permanently stored in the composite, the atmosphere can be permanently depleted of an equivalent amount of carbon dioxide. This can have relevant environmental impacts when charcoal-based materials are used in large quantities, for example, in construction applications.

[0025] Therefore, the present combination of PFA and charcoal from organic sources provides a highly advantageous environmental footprint, enabling the sequestration and permanent storage of large amounts of carbon from the atmosphere. The composite material comprises 25-90% by weight of charcoal and 10-75% by weight of PFA. Preferably, the composite material comprises 30-85% by weight of charcoal and 15-70% by weight of PFA, more preferably 40-80% by weight of charcoal and 20-60% by weight of PFA. It is particularly preferred that the proportion of charcoal in the composite be at least 30%, at least 50%, or at least 70% by weight. In these embodiments, it is advantageous that PFA can impart high stability to the composite. Furthermore, the environmental footprint is particularly favorable when the charcoal content is relatively high. The composite material preferably consists of charcoal and PFA (as a polymer binder), which can provide a particularly favorable environmental footprint.

[0026] In a preferred embodiment, the charcoal powder has an average particle size (particle size) of 10 μm to 10 mm, preferably 50 μm to 5 mm, more preferably 100 μm to 1 mm. In a preferred embodiment, the charcoal particles have a particle size in the range of 10 μm to 10 mm, preferably 50 μm to 5 mm, more preferably 100 μm to 1 mm. Preferably, the particle size is determined by the method according to DIN ISO 2591-1:1988. It has been found that fine powders having such particle sizes are suitable for providing composite materials with high uniformity and strength.

[0027] In a preferred embodiment, the composite material is not porous. In a preferred embodiment, the composite material is dense and / or does not contain voids. If the composition including the PFA binder and charcoal powder is molded and compressed before solidification, a non-porous and / or dense material can be obtained. A non-porous material is particularly advantageous for storing the maximum amount of carbon. Furthermore, the stability and barrier properties of a dense material can be particularly high.

[0028] In another embodiment, the composite material is porous. For example, the composite material may contain 1 to 70% by volume, or 2 to 25% by volume, voids, e.g., pores. This may be advantageous in applications where lightweight and / or permeability to fluids, such as air or water, is desired. Non-porous materials can be obtained by conventional means, for example, by adding a propellant during the manufacturing process.

[0029] In a preferred embodiment, the composite material comprises at least one additional filler or reinforcing agent, such as fiber. If additional fillers or reinforcing agents are added, they are preferably also based on organic materials and have a good environmental footprint. Additional fillers can be added to modify properties, for example, by including color pigments or conductive particles. Reinforcing agents, such as fibers, especially glass or carbon fibers, can be added to increase mechanical stability. Preferably, the amount of filler and / or reinforcing agent is up to 20%, preferably up to 10%, for example in the range of 1-20% or 2-10% (w / w).

[0030] The composite material may contain at least one additive that is not a structural polymer, a filler, or a reinforcing agent. For example, the additive can be selected from plasticizers, coupling agents, colorants, processing aids, flame retardants, heat stabilizers, and compatibilizers. For example, the processing aid can improve workability in solution or the molding procedure, or can impart desired properties to the composite material, such as color, strength, etc. Preferably, the amount of additive is up to 5% or up to 2%, for example, in the range of 0.01-5% or 0.1-2% (w / w).

[0031] In a preferred embodiment, the composite material comprises: (A) 25 to 90%, preferably 30 to 85%, of charcoal; (B) 10 to 75%, preferably 15 to 70% PFA; (C) optionally up to 20% fillers and / or reinforcing agents; (D) optionally up to 5% additives; where all percentages are by weight, the sum of components (A)-(D) is 100%, and additive (D) is not a filler and / or reinforcing agent. Fillers and additives are preferably selected as outlined above.

[0032] The subject of the present invention is also a shaped object comprising the composite material of the present invention. As used herein, a shaped object is a separate solid part or body (object) of a defined three-dimensional structure. The shaped object may consist of or comprise the composite material described above. The shaped object can be used, for example, in construction, furniture, or transportation applications. In a preferred embodiment, the shaped object is a panel, an insulating board, a building block, or a device. The device is a functional object such as a tube, a box, a pot, or a piece of furniture. The use of the composite material described above for preparing such shaped objects is highly advantageous, since shaped objects can be obtained easily, reliably, and in large quantities by molding.

[0033] In a preferred embodiment, the shaped object is a building material, i.e., a material used in construction. In a preferred embodiment, the building material is a wall panel, an insulating board, a building component, or a block for assembling building components such as walls. For furniture applications, the shaped object is preferably a panel or a structural component. It is highly advantageous that such building materials or furniture components can be conveniently, uniformly, and in large numbers obtained by molding the composite material.

[0034] A panel is a flat object for covering building or furniture components, such as walls, floors, or furniture surfaces. The use of the composite material as a panel is particularly advantageous due to the high stability of the composite material. Because the composite material is mechanically, thermally, and chemically stable, the panel can shield the substrate to which it is attached. Furthermore, the high thermal stability can protect the substrate from heat or fire.

[0035] In a preferred embodiment, the panel has a thickness of 0.05 to 5 m. 2, a thickness of 2 to 50 mm, and a length preferably at least 10 times greater than the thickness. More preferably, the panel has a length of 0.2 to 2 m 2 1 mm, a thickness of 2 to 10 mm, and a length preferably at least 10 times greater than the thickness. Panels having such dimensions are advantageous because they can be conveniently manufactured using conventional molding equipment and procedures and can be widely used in construction or furniture applications.

[0036] In a preferred embodiment, the composite material or shaped object is an insulating material. This is advantageous because the composite material has a high heat capacity. For example, the heat capacity of a composite made of 70% by weight charcoal and 30% by weight PFA is about 2050 J / kgK, which is comparable to the traditional insulating material extruded polystyrene (XPS).

[0037] The composite materials and shaped articles have significant advantages over those obtained by impregnating preformed porous green bodies of filler with a binder solution: uniform impregnation of preformed green bodies is much more complex and difficult to achieve, and shaping of porous green bodies is much more complicated than simply molding and curing an object into a desired shape.

[0038] The shaped object may be a composite of the composite material of the present invention and an additional material, for example, in the form of a laminate of two, three, or more layers. In a preferred embodiment, the composite material or shaped object includes a coating layer (coating). Typically, the coating is a functional coating that imparts desired properties to the substrate. For example, the coating may impart desired optical properties, such as color or gloss, to the substrate, or may provide protection against moisture, UV radiation, chemical or mechanical damage, or weathering (climate), or may include a texture. Applying a color coating may be particularly desirable, since charcoal imparts a dark color to the composite material. The coating can be applied by conventional means, such as liquid coating procedures using resins, impregnation, electron scattering (Trespa process), physical or chemical vapor deposition, lamination, etc. The coating may cover the shaped object completely or partially, for example, on only one side. For example, a panel may include a functional coating only on the outer surface.

[0039] The subject of the present invention is also the use of the composite material or shaped article as a flame retardant and / or fire barrier. The composite material has high thermal stability and is therefore found to be suitable for fire protection or as a fire barrier. Fire barrier materials provide a physical barrier against the passage of fluids, flames, or sparks at very high temperatures, thereby preventing the spread of flames. The low weight loss of the composite material even at very high temperatures indicates that the material may be suitable for such use. This is particularly advantageous for panels, which can shield the substrate on which such panels are mounted from the environment.

[0040] The shaped objects and / or composites can be used to protect against UV radiation. The inclusion of biochar in a PFA matrix can significantly improve the UV resistance of building materials, etc., thereby reducing the need for UV stabilizing compounds during manufacturing and reducing degradation during use, which also leads to improved recyclability.

[0041] Another advantage is that biochar as a pyrolysis product can also introduce less heat load into the composite than traditional products such as kraft paper.

[0042] In principle, the composite material can be obtained by various methods in which charcoal powder, PFA and liquid are mixed, solidified and dried. However, it is highly preferred to produce the composite material by molding. This is particularly advantageous because the liquid composition from charcoal powder and PFA can be molded and consolidated in a simple and efficient process, which allows obtaining a homogeneous and highly stable composite.

[0043] According to the present invention, it has been discovered that the molding process can also be highly advantageous for moisture control. The initial mixture contains a solvent, and as the PFA binder hardens in a condensation reaction, additional water is released. Charcoal has a porous structure and can absorb moisture into its interior. Without being bound by theory, it is believed that charcoal powder can adsorb moisture and / or solvent, particularly the water formed in the condensation reaction, thereby assisting the condensation reaction by shifting the reaction equilibrium toward further hardening. From the product characteristics, it can be concluded that such water uptake into the charcoal interior does not adversely affect the stability of the final product. In contrast, the high stability suggests improved overall stability, as a tightly hardened, high-density product can be obtained. This unique advantage is only observed when the adsorbent charcoal filler is combined with a PFA resin capable of further condensation.

[0044] The subject of the present invention is a method for producing a composite material or a shaped object according to the invention, comprising the steps of: (a) preparing a composition comprising charcoal powder, at least one compound selected from polyfurfuryl alcohol (PFA) and furfuryl alcohol, and at least one solvent; (b) placing the composition in a mold; (c) subjecting the mold to heat and pressure; (d) removing the molded part from the mold; It is also a method including the above.

[0045] The process steps (a) to (d) are carried out in sequential order. Preferably, the PFA is produced prior to step (a) by polymerization from furfuryl alcohol in a polycondensation reaction, typically in the presence of a weak acid, such as maleic anhydride. The polycondensation can be assisted by heating, for example, at temperatures between 80°C and 150°C. The PFA resin can be obtained in the form of a liquid polymer. Preferably, the initial moisture content of the biochar is less than 5%, typically between 1 and 5%, more preferably about 3%. The initial moisture content of the biochar is controlled by drying.

[0046] The composition in step (a) can be prepared by mixing charcoal powder, PFA, and solvent in any given order. Preferably, a mixture of PFA and solvent is prepared first. The desired viscosity can be controlled by the amount of solvent. The PFA / solvent mixture is then combined with charcoal powder. After thorough mixing, the homogeneous composition can be inserted into a mold (molding form).

[0047] Preferably, the ratio of PFA to solvent in the PFA / solvent mixture and / or composition is 50-90% PFA to 10-50% solvent (w / w), preferably 60-85% PFA to 15-40% solvent (w / w), preferably about 70-30% (w / w). In a preferred embodiment, the solvent is an aliphatic alcohol, preferably ethanol. Surprisingly, it has been found that a mixture of PFA and an aliphatic alcohol, preferably ethanol, can aid in intimate impregnation of the charcoal, possibly by reducing the PFA viscosity. This allows the ethanol to improve the stability of the composite material. Preferably, the mixture is essentially water-free, e.g., containing less than 10% water, or less than 5% water, or less than 2% water. It has been found that workability and product properties can be advantageous when using an essentially water-free mixture of PFA and ethanol. Alternatively, the solvent can be another organic solvent, such as methanol or propanol.

[0048] In an alternative embodiment, furfuryl alcohol is used in place of PFA in step (a). Proceeding accordingly, PFA is formed from furfuryl alcohol in an in situ process when heat and pressure are applied in step (c). This embodiment also provides a composite of the present invention comprising charcoal powder dispersed in a PFA matrix.

[0049] In the subsequent step (c), the mold, and thus the composition within the mold, is subjected to heat and pressure. Preferably, the mold in step (c) is subjected to a temperature of 80°C to 250°C, typically 100°C to 200°C, and a pressure of preferably 2 bar to 50 bar, more preferably 5 bar to 20 bar. The heat has the effect of at least partially curing the PFA and at least partially drying the composition. The solvent can be removed into the environment and / or adsorbed by charcoal. The pressure has the effect of more efficiently removing the solvent, resulting in a non-porous, dense (dense) product.

[0050] Step (c) can be completed when the mold has the desired consistency, typically resulting in a solid molded object. The molded object is removed from the mold in step (d). Preferably, the mold is removed after a period of 10 minutes to 8 hours, preferably 20 minutes to 3 hours. In one embodiment, the molded part obtained in step (d) is the composite material described above.

[0051] In a preferred embodiment, after step (d), the molded part is exposed to heat in step (e). Typically, the molded part obtained in step (d) is an intermediate product (green body), which is converted into a composite material by further heating in the subsequent step (e). This allows curing to be completed and / or residual moisture to be removed. Preferably, in step (e), the molded part is heated in an oven, which is typically ventilated at a temperature of preferably 100°C to 250°C, typically 120°C to 220°C, for efficient drying. This allows the green body with residual moisture to be converted into a composite material by additional curing and drying. After heating is completed, the composite material of the present invention can be obtained.

[0052] In a preferred embodiment, the process heat generated in the pyrolysis process in which the char is produced can be used in the heating step to produce the composite material, leading to even greater energy efficiency and further improvement of the environmental footprint of the material.

[0053] Advantageously, the composite material of the present invention can be obtained simply by molding a liquid mixture of charcoal powder and PFA. Therefore, there is no need to prepare a carbonaceous green body as an intermediate and then impregnate the intermediate with a binder. Therefore, the process of the present invention is easier and more convenient than conventional processes, such as those described in WO 2017 / 089500 A2. The molding method of the present invention also provides a novel and advantageous material, since the PFA matrix with dispersed charcoal particles can impart high stability to the composite material. Intimate and uniform contact between both components can be achieved without voids.

[0054] It has been found that, according to the present invention, stable composite materials can be obtained that consist predominantly of biochar and PFA. Preferably, the composite, especially the polymer matrix, does not contain relevant amounts of other components. Preferably, the combined amount of biochar and PFA in the composite is greater than 80% by weight, more preferably greater than 90% or 95% by weight, and preferably the polymer matrix consists of PFA.

[0055] Preferably, the composition for preparing the composite material does not contain additional reactive components for forming a polymer matrix. Preferably, the composition does not contain any additional curable components in the form of polymer resins, monomers, or additives. Preferably, the composition does not contain any additional components containing unsaturated groups, such as vinyl or acrylic groups, epoxy groups, reactive silicon-based groups, such as siloxane or silane groups, thiol, cyanate, or isocyanate groups. Preferably, the composition does not contain any additional thermosetting adhesive. It is also preferred that the composition does not contain any low-molecular-weight additives for curing, such as curing agents, crosslinking agents, or curing catalysts. Preferably, the composition does not contain any curing agents, such as peroxy compounds, active hydrogen-containing compounds, anionic initiators or cationic initiators, molecules capable of providing anions, such as tertiary amines, secondary amines, or metal alkoxides. Preferably, the composite material, particularly the polymer matrix, does not contain polyurethanes, polyesters, polycarboxylates, or polyacrylates. Preferably, the composite material, particularly the polymer matrix, does not contain any organic polymers containing N, Si, S, and / or P, such as amine, thiol, phosphate, or siloxane groups.

[0056] Typically, the polymer matrix is ​​the primary structural component that provides stability to the composite. Therefore, the polymer matrix is ​​not merely a coating or filler of another, different material. The composite does not include a solid body or framework of another, different material, e.g., a solid foam, such as a metal foam, or a porous green body, such as a carbonaceous framework, impregnated with a composition comprising PFA or furfuryl alcohol and biochar. The composite with a polymer matrix is ​​also not an intermediate for further chemical modification, such as a green body for calcination, in which the polymer matrix is ​​decomposed.

[0057] According to the present disclosure, the charcoal may be biochar. Both charcoal and biochar are obtained by pyrolysis of organic materials. While pyrolysis conditions tend to be different, there is no clear distinction between charcoal and biochar. However, charcoal is physically and chemically very different from other carbon products, particularly those of fossil origin, such as bituminous coal or coke, or refined carbon materials, such as carbon black, carbon nanotubes, or carbon fibers. For example, coke is obtained from oil or bituminous coal and has a much higher density, a much lower volatile matter content, and a different chemical composition than biochar. These products are generally more refined, more expensive, and have different properties than charcoal and biochar. In one embodiment, the charcoal and / or biochar has not undergone further chemical modification, such as activated carbon (activated charcoal). The above advantageous properties can be achieved with simple charcoal or biochar, which can be advantageous for cost reasons.

[0058] The composite materials, shaped articles, uses and methods of the present invention solve the problem underlying the present invention: highly stable composite materials are provided, which have a good environmental footprint and can be used as carbon sinks for long-term storage of carbon from the atmosphere, for example in buildings, furniture, etc. The composite materials have unusually high thermal stability, which makes them suitable for flame retardant and flame-retardant applications.

[0059] Another advantage of the composite material and manufacturing method of the present invention is that it can be obtained from conventional materials, charcoal and furfuryl alcohol, which are readily available at relatively low cost. Furthermore, the composite material can be obtained through a simple molding process, making it suitable for mass production, a prerequisite for efficient carbon storage. As outlined above, the molding process is also advantageous due to the moisture control in the binder system.

[0060] Furthermore, the starting materials and the composite are non-toxic, which offers advantages over materials in the art such as phenolic and formaldehyde-based resins. After use, the composite can be recycled or burned in a thermal power plant.

[0061] A particular advantage is that not only is biochar naturally derived, but PFA can also be easily obtained from naturally derived furfuryl alcohol, particularly from waste biomass. Biochar and furfuryl alcohol are simple products, not highly refined, and available in large quantities from natural sources at low cost. Furthermore, it is advantageous that the composite can contain high levels of both materials, up to 100%. Therefore, a very favorable environmental footprint can be achieved.

[0062] Furthermore, the composite, its underlying composition, and manufacturing process are very simple since only two starting materials are required. Therefore, the reaction of the present invention is easy to control and carry out. This is a significant advantage over prior art systems and composites that are based on specific curing reactions, thermosetting systems, and additives, such as epoxy systems and hardeners.

[0063] Overall, the composite materials are advantageous compared to conventional products due to their low toxicity, high stability, and easy fabrication at low cost, providing improved materials for efficient carbon sequestration and mass storage. [Brief explanation of the drawings]

[0064] [Figure 1] 1 shows the results of Example 2 regarding the thermal stability of the composite and comparative samples in the range of 25-800° C. as determined by thermogravimetric analysis (TGA). DETAILED DESCRIPTION OF THE INVENTION

[0065] Illustrative embodiments of the invention and aspects of the invention are illustrated in the drawings.

[0066] Figure 1 shows the results of Example 2 for the thermal stability in the range 25-800°C as determined by thermogravimetric analysis (TGA) of the composite and comparative samples. Results are shown for the inventive composite from PFA and charcoal (continuous line), pure charcoal (dashed line, long segment) and pure PFA (dashed line, short segment). [Example]

[0067] Example 1: Preparation of a composite material of the present invention PFA resin was prepared from furfuryl alcohol (Sigma-Aldrich, USA) by acid-catalyzed polymerization. Furfuryl alcohol was mixed with maleic anhydride (2 wt%) at ambient temperature. The mixture was heated to 100 °C for 45 min under magnetic stirring until a fluid PFA resin was obtained. This PFA resin has a pH of 2.8 (measured at 50 w / w% in water) and a density of 1.4.

[0068] Biochar was produced by pyrolysis of beech-derived lignocellulosic biomass. Biochar with a particle size distribution ranging from 100 μm to 1 mm was produced by impact crushing and then drying at 120 °C for 24 h to obtain biochar with a moisture content of approximately 3%.

[0069] To fabricate the composite, liquid PFA polymer resin was mixed with ethanol (96%) to achieve an ethanol / PFA ratio of 30:70 (w / w). Ethanol reduces the PFA viscosity and improves biochar impregnation. The PFA / ethanol mixture was then mixed with biochar to achieve a PFA:biochar ratio of 70:30 (w / w). This composition was inserted into an aluminum mold and heated at 160°C for 45 minutes while compressing under 10 bar pressure. The mold measured 105 mm in length, 60 mm in width, and 75 mm in thickness. After demolding, the composite was heated in a ventilated oven at 180°C for 2 hours to complete the curing of the PFA and the release of volatiles, such as solvents and water from the PFA polycondensation. A highly stable solid object was obtained.

[0070] In further experiments, composites were prepared from compositions with PFA:biochar ratios of 50:50 and 60:40 (w / w), which also yielded highly stable solid objects.

[0071] Example 2: Thermal stability of composite materials The thermal stability of the composite material of Example 1 was investigated by thermogravimetric analysis (TGA). Sample weights were determined in the temperature range of 25-800 °C with a temperature gradient of 10 °C / min. Comparative samples, namely pure biochar and the corresponding pure PFA product, were also investigated.

[0072] The results are shown in Figure 1. We found that biochar-PFA composites with only 30% biochar can offer significant advantages in thermal resilience while dramatically reducing thermal decomposition. The approximately 25% mass loss observed at 750 °C demonstrates the material's high thermal resistance and its superiority over pure PFA (approximately 50% mass loss). A synergistic improvement in the thermal decomposition of the PFA-biochar composite was also observed, as the mass loss of the composite was significantly lower than expected from the combination of the two components alone. The results also demonstrate that essentially no mass loss occurs within the temperature range up to approximately 250 °C. This can be advantageous, as significant changes in properties may be undesirable in practical applications. Within this temperature range, thermal stability is high and comparable to that of pure PFA. By comparison, pure biochar exhibits significant weight loss between 20 °C and 80 °C. Overall, this thermal behavior provides an advantageous combination of high stability in the range up to about 250° C., even with relatively small amounts of biochar added, and relatively high stability and structural integrity at elevated temperatures up to about 800° C. It can be expected that building components from this composite will not disintegrate at high temperatures, making this material suitable for flame retardant or fire barrier applications.

[0073] Example 3: Environmental footprint of composite materials The environmental footprints of panels from the composite material of the present invention and comparison building materials, namely conventional HPL and epoxy-glass fiber composites, were calculated by various standardized methods. HPL (high-pressure laminate) is a common building material made of 60%-70% paper and 30%-40% binder based on a combination of phenol-formaldehyde resin and melamine-formaldehyde resin. Epoxy-glass fiber composites are common in the art as fire-retardant panels for building applications. Calculations were performed for the Cradle-to-Gate (from raw material acquisition at the factory to product delivery), which is an assessment of the partial product life cycle from resource extraction (cradle) to the factory gate, i.e., transportation to the consumer. 1m 2 Calculations were performed for a panel with an area of ​​1000 m and a thickness of 8 mm. The results show that the composite material of the present invention has a very favorable environmental footprint (Table 1). The composite material of the present invention has a significantly better environmental footprint than conventional products. Notably, the CO balance of the composite material of the present invention can be negative. Therefore, the composite material of the present invention can be an effective carbon sink and is suitable for sequestering and storing carbon from the atmosphere.

[0074] [Table 1]

Claims

1. A composite material comprising charcoal powder dispersed in a polymer matrix, the polymer comprising polyfurfuryl alcohol (PFA), the composite comprising 25-90% by weight charcoal and 10-75% by weight polyfurfuryl alcohol.

2. 10. The composite material of claim 1, comprising 25 to 90% by weight of charcoal and 10 to 75% by weight of polyfurfuryl alcohol.

3. 3. The composite material of claim 1 or claim 2, wherein the charcoal powder has an average particle size of 10 μm to 10 mm as determined by DIN ISO 2591-1:1988.

4. 4. The composite material of claim 1, which is non-porous.

5. 5. The composite material according to any one of claims 1 to 4, comprising at least one additional filler and / or reinforcing agent, such as a fiber, and / or at least one additive, such as a plasticizer, a coupling agent, a colorant, a processing aid, a flame retardant, a heat stabilizer, and a compatibilizer.

6. A shaped object comprising the composite material according to any one of claims 1 to 5.

7. 7. The shaped object according to claim 6, which is a panel, an insulating board, a construction component, a building block or a device.

8. 0.05 to 5 m ２ 8. The shaped object according to claim 7, which is a panel having an area of ​​100 mm, a thickness of 2 to 50 mm, and a length at least 10 times greater than the thickness.

9. 9. A composite material or shaped article according to any one of claims 1 to 8, comprising a coating.

10. 10. A composite material or shaped object according to any one of claims 1 to 9, obtained by molding and curing.

11. 11. Use of a composite material and / or shaped article according to any one of claims 1 to 10 as a flame retardant and / or fire barrier.

12. A method for producing a composite material or a shaped object according to any one of claims 1 to 11, comprising the steps of: (a) preparing a composition comprising charcoal powder, at least one compound selected from polyfurfuryl alcohol (PFA) and furfuryl alcohol, and at least one solvent; (b) placing the composition in a mold; (c) subjecting the mold to heat and pressure; (d) removing the molded part from the mold; A method comprising:

13. 13. The method of claim 12, wherein the ratio of PFA to solvent in the composition is 50-90% PFA to 50-10% solvent (w / w).

14. 14. The method of claim 12 or claim 13, wherein the solvent is ethanol.

15. 15. The method of any one of claims 12 to 14, wherein after step (d), the formed part is exposed to heat.

Images