METHOD FOR THE SYNTHESIS OF A COMPOSITE MATERIAL THAT CAN STORE AND RELEASE THERMAL ENERGY

Description

TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to the field of composite materials and their manufacture. More particularly, it relates to the processes for synthesizing composite materials. The invention will find more specific application in composite materials intended for storing thermal energy and regulating energy inputs and losses, particularly in the fields of building construction, textiles, packaging, electronics, transportation, and renewable energy. STATE OF THE ART

[0002] Composite materials are interesting for several reasons, particularly because they allow the properties of their constituent components to be combined.

[0003] In literature and industry, phase change materials (PCMs) are used for their ability to store and release latent heat during their phase transitions, particularly from solid to liquid. When introduced undiluted into conventional materials, they exhibit morphological changes during the phase change, leading to leakage, corrosion, and reduced thermal response stability. Therefore, they are often encapsulated using macro-, micro-, or nano-encapsulation.

[0004] However, macro-encapsulation is not very adaptable and does not guarantee the absence of leakage. The manufacturing processes used for micro-encapsulation, nano-encapsulation, and dispersion in "support" phases are complex, lengthy, and expensive, as they require the use of solvents, additives, vacuum and / or heating techniques, and this over several stages.

[0005] We are also familiar with document WO2017 / 198933, which describes a phase change material for thermal energy storage and its manufacturing process. The PCM used is of the solid-solid type, and the manufacturing process involves compounds in the liquid state reacting above the phase change temperature.

[0006] Therefore, there is a need to propose a process that allows for the production of reliable composite materials with simplified manufacturing.

[0007] The other objects, features, and advantages of the present invention will become apparent from an examination of the following description and accompanying drawings. It is understood that other advantages may be incorporated. SUMMARY OF THE INVENTION

[0008] To achieve this objective, according to one embodiment, a process for synthesizing a composite material comprising an inorganic matrix and an active ingredient is provided, the active ingredient being a phase-change material characterized in that the process includes at least one step of assembling the active ingredient into the matrix by mechanosynthesis.

[0009] The synthesis process according to the invention allows the active ingredient to be confined in different porosities created at the level of the organization of the inorganic matrix.

[0010] The resulting composite material has high energy value and comprises on the one hand an inorganic matrix and on the other hand one or more active ingredients confined within this matrix.

[0011] Advantageously, mechanosynthesis, or mechanotransformation, allows solid particles to be flattened, welded, fractured, and re-welded. The mechanosynthesis according to the invention allows the inorganic matrix and the active ingredient to interlock to form the composite, primarily through impact and friction phenomena. Preferably, the mixture of the inorganic matrix and the active ingredient is a powder mixture.

[0012] The manufacturing process is environmentally friendly.

[0013] The process, and more specifically the assembly step, does not require the use of a solvent. The absence of solvents simplifies the process and makes it more environmentally friendly. The process can, in some cases, be carried out without producing any waste. The process according to the invention is energy-efficient.

[0014] Another aspect concerns a composite material obtained by the present process characterized in that, at the end of the assembly step, the composite material is in a solid state, the active ingredient being confined in the inorganic matrix.

[0015] Another aspect concerns a material including the composite material, the material being for example plaster, cement, mortar, concrete or even wood, paper, plastics, textile. BRIEF DESCRIPTION OF THE FIGURES

[0016] The aims, objects, features and advantages of the invention will become clearer from the detailed description of an embodiment thereof, which is illustrated by the following accompanying drawings in which: There figure 1 This represents a schematic diagram of the assembly stage, including high-energy grinding. figure 2represents a thermal response during the charging and discharging of a wafer according to example 1. The figure 3 represents the comparison of the thermal response of a composite material in the form of a plate (1) obtained in Example 1 with the response of a plate based on sepiolite (2) or a mortar (3). figure 4 represents an infrared spectrum of the carbonyl groups (VC0) of: (1) capric acid, denoted CA, (2) myristic acid, MA, (3) the CAMA mixture obtained in the Eco-PCM-CAMA70 composite material powder obtained in Example 2. figure 5 represents the thermal response of a composite material, the Eco-PCM CAMA 70 obtained in example 2 in the form of a plate. figure 6 represents the thermal response of the Eco-PCM CAMA 70 composite material obtained in example 2 as a plate at 4°C heated to 40°C (1) or exposed to the sun in April (2). The figure 7represents the thermal response of the Eco-PCM mortar in example 3, composed of 90% Eco-PCM-SA70 composite material powder obtained in example 1 and 10% mortar. Figures 8A And 8B They compare the thermal responses of mortar tiles (2) and sepiolite tiles without additives (3) to the response of a mortar tile filled with Eco-PCM composite material (1). The shape of the curves and the heating times highlight a thermal insulation effect linked to the charging and discharging time of the composite material integrated into the mortar. figure 9 This represents a comparison of the thermal response of a cardboard box according to example 4, containing 60% of an Eco-PCM-SA70 composite material (1) obtained in example 1, with the response of a molded paperboard box (2). The applied temperature is 100°C for load A and 20°C for discharge B. Figure 10represents the thermal response in charge and discharge of SepSA70 composite material plates (1) and SepSA70 composite material plates with 2% carbon nanoparticles (2) obtained in example7.

[0017] The drawings are given as examples and are not limiting to the invention. They constitute schematic representations of principle intended to facilitate understanding of the invention and are not necessarily to scale with practical applications. DETAILED DESCRIPTION OF THE INVENTION

[0018] Before beginning a detailed review of embodiments of the invention, optional features that may be used in combination or alternatively are stated below: According to one example, the mechanosynthesis assembly step is carried out at a temperature lower than the phase change temperature of the active ingredient.

[0019] As an example, the mechanosynthesis assembly stage is carried out in a high-energy mill. This mill allows the solid particles to be flattened, welded, fractured and / or re-welded to produce the composite material.

[0020] According to one example, the mechanosynthesis assembly step is carried out without solvents.

[0021] According to one example, the mechanosynthesis assembly step is carried out in the presence of grinding balls.

[0022] For example, grinding media have a diameter between 1 mm and 100 mm. In another example, the grinding media represent 1 / 5 to 6 times, preferably 1 / 5 to 10 times, the total weight of the matrix and active ingredient.

[0023] According to one example, the mechanosynthesis assembly stage lasts from 15 seconds to 10 hours, preferably 1 hour.

[0024] According to one example, the asset represents from 1 to 90% by weight of the total matrix and asset weight.

[0025] In one example, the matrix is ​​chosen from: a clay from the family of clay minerals of type TO, TOT or TOT+O which are in platelet, tubular or fibrous form, for example kaolinites, bentonites, perlites, vermiculites, montmorillonites, halloysites, sepiolites, palygorskites, or mineral oxides or hydroxides, for example micronized calcium carbonate derivatives, marble powders, silica derivatives of diatomites, microsilicas, nanosilicas, or carbon in the form of graphite, nano fiber or fullerene, and metallic oxides.

[0026] According to one example, the active ingredient is chosen from paraffins, saturated fatty acids, saturated fatty alcohols, fatty acid esters, polyethylene glycols, alone or in mixtures.

[0027] In one example, the asset is a solid-liquid MCP.

[0028] According to one example, the composite material obtained at the end of the assembly stage is in the form of micrometric powder.

[0029] According to one example, the process includes a subsequent step of re-aggregating the composite material obtained at the end of the assembly step; the composite material obtained at the end of the re-aggregation step is in the form of beads, granules or blocks.

[0030] In one example, the process includes a subsequent step of grinding the composite material obtained after the reaggregation step; the composite material obtained after the grinding step is in the form of micrometric powder. This grinding step is not necessarily carried out with a high-energy mill.

[0031] According to one example, the process includes a subsequent step of moistening the composite material obtained at the end of the assembly step or the reaggregation step, or the grinding step, including the addition of a quantity of water to said composite material; the composite material obtained at the end of the moistening step is in the form of an aqueous mixture.

[0032] According to one example, the humidification step is carried out by adding an amount of water between 0.5 and 50 times the weight of the composite material to be humidified.

[0033] According to one example, the process includes a subsequent step of drying the composite material obtained at the end of the humidification step; the composite material obtained at the end of the drying step is in the form of plates.

[0034] Depending on one possibility, the drying step is carried out at room temperature or at a temperature lower than the phase change temperature of the active ingredient or at a temperature higher than the phase change temperature of the active ingredient.

[0035] According to one example, the process includes a subsequent step of mechanically agitating the dispersion of the composite material obtained at the end of the assembly or grinding step, including the addition of an aqueous system to said composite material with mechanical agitation; the composite material obtained at the end of the mechanically agitated dispersion step is in the form of an aqueous suspension.

[0036] According to one example, the process includes a subsequent ultrasonic dispersion step of the composite material obtained at the end of the assembly or grinding step, including the addition of an aqueous system to said composite material with ultrasonic agitation; the composite material obtained at the end of the ultrasonic dispersion step is in gel form.

[0037] As an example, a quantity of 1 to 10% composite material powder is added to water or an aqueous solution, more specifically the aqueous system.

[0038] According to one example, the process includes a step of incorporating the composite material obtained at the end of the assembly step or the reaggregation step or the grinding step or the humidification step or the dispersion step in a manufacturing process for plaster, cement, mortar, concrete or even paper, plastics, wood compounds and their applications.

[0039] The process according to the invention allows the production of a composite material. The composite material comprises, on the one hand, an inorganic matrix and, on the other hand, at least one active ingredient.

[0040] The active ingredient is, in some cases, bio-based. It is advantageously suited to storing and releasing thermal energy. The active ingredient is a phase-change material, alternately adopting a solid and a liquid form around a phase transition temperature. Preferably, the active ingredient is organic. Organic is defined as originating from an organic chemical substance, while the matrix is ​​considered inorganic because it originates from a mineral chemical substance. Preferred examples include paraffin families or paraffinic derivatives, preferably saturated fatty acids, preferably saturated fatty alcohols, fatty acid esters, and polyethylene glycols.

[0041] The composite material comprises at least one active ingredient; alternatively, the composite material may comprise several active ingredients selected from the list above. The active ingredients are then a mixture. In the remainder of this description, references to "an active ingredient" and "the active ingredient" are used for ease of description of the invention, but are not intended to be limiting.

[0042] The asset preferentially exhibits a phase change temperature ranging from -20°C to 300°C.

[0043] The active ingredient in the present process is in solid form, preferably in powder form.

[0044] The inorganic matrix is, in one case, geo-sourced. Its main role is to support the asset.

[0045] As a preferred example, the inorganic matrix is ​​chosen from: a clay from the family of clay minerals of type TO, TOT or TOT+O which are in platelet, tubular or fibrous form, for example kaolinites, bentonites, perlites, vermiculites, montmorillonites, halloysites, sepiolites, palygorskites, or mineral oxides or hydroxides, for example micronized calcium carbonate derivatives, marble powders, silica derivatives of diatomites, microsilicas, nanosilicas, or so-called 1D, 2D or 3D carbon compounds such as carbon nanotubes, graphene or expanded carbons, graphite, nano fiber or fullerene, or metallic oxides, or semiconductors.

[0046] The inorganic matrix is ​​preferably in solid form, preferably fractionated, preferably in powder form, for example with a particle size of at least millimeters, preferably with a maximum particle size of 50 mm. For example, the inorganic matrix can be pre-ground to obtain a powder of micrometer size.

[0047] It is specified that within the framework of the present invention, the term composite material is an assembly of at least two immiscible components, but having a capacity to contain the active ingredient in such a way that it crystallizes under the phase transition without releasing it above the phase transition.

[0048] The composite material obtained by the process according to the invention is, at the end of the assembly stage, in the form of a powder preferably of micrometric size.

[0049] In one possibility, the composite material is integrated into other traditional materials such as plaster, cement, mortar, concrete, or even wood, paper, and plastics. The composite material obtained by the process according to the invention, and the traditional materials incorporating said composite material, offer the advantage of regulating energy inputs and losses in various fields such as construction, textiles, packaging, electronics, and renewable energy.

[0050] The composite material is capable of storing and releasing thermal energy.

[0051] The composite material obtained by the process according to the invention has a high energy value. Advantageously, the composite material has an operating temperature range of -20°C to 300°C.

[0052] Advantageously, the composite material does not change volume during the phase change and thus advantageously retains dimensional stability.

[0053] The synthesis process according to the invention includes a step of assembling the inorganic matrix and at least one active ingredient.

[0054] The assembly step is carried out according to the invention by mechanosynthesis or mechanotransformation. The inorganic matrix and the active ingredient are mixed. They form a mixture to obtain the composite material at the end of the assembly step.

[0055] Mechanosynthesis refers to a step consisting of mixing, or even grinding together, at least two components until a composite material is formed.

[0056] According to a preferred embodiment, the amount of asset added for the assembly step is between 1 and 90% of the total weight of the matrix and the asset, preferably between 30 and 70%.

[0057] The assembly step is carried out without the addition of solvent. The assembly step is preferably carried out with solid components. A solvent is defined as a compound in a liquid state, preferably in which the active ingredient and / or the matrix are solubilized.

[0058] In one scenario, the assembly step involves adding a dispersion aid. More specifically, the assembly step involves adding water. The added water acts as a dispersion aid, as the active ingredient and matrix are insoluble in water. The added water is not a solvent.

[0059] According to one possibility of the invention, the assembly step is carried out by a high-energy crusher.

[0060] During the assembly stage, the active ingredient and the inorganic matrix undergo mechanical transformations such as flattening, welding, fracturing, and / or re-welding of their particles. The assembly stage also involves impact and friction phenomena.

[0061] Impacts and friction promote size reduction and the disintegration of particles, agglomerates, and granules based on crystallized organic molecules, thus maximizing contact surfaces while generating new surfaces and creating defects, as illustrated in figure 1 The alternating plastic deformation, fracture, and bonding process leads to the production of an organic / inorganic composite material capable of storing and releasing heat. figure 1 The beads 1, the active ingredient 2, and the inorganic matrix 3 are placed in a bowl 4. figure 1illustrates the impacts and frictions that ensure the integration and containment of asset 2 in matrix 3.

[0062] The process according to the invention is advantageously configured to ensure control over the retention of the active ingredient in the various interstices and cavities formed by the organizational network of the inorganic matrix. This control of the active ingredient's retention is advantageously achieved by adjusting, on the one hand, the temperature during the phase transition of the active ingredient, and on the other hand, the mechanical energy supplied during the formation of the composite. The power applied to the mixing process is advantageously managed so as to promote physical interactions and prevent chemical reactions that could disrupt the organization of the crystalline network of the organic molecules.

[0063] Advantageously, confining the active ingredient within the inorganic matrix increases its fire stability.

[0064] Advantageously, this process makes it possible to manufacture recyclable composite materials using a bio-based active ingredient and a geo-based inorganic matrix.

[0065] Advantageously, the process makes it possible to obtain a composite material that does not release the active ingredient during its phase change.

[0066] As an example, the crusher is a high-energy crusher of the planetary, vibrational or agitator ball type.

[0067] In one scenario, for planetary mills, the assembly step is carried out by mixing the active ingredient and the inorganic matrix in a mixing bowl. The mixing bowl can be made of materials such as steel, PTFE, agate, tungsten carbide, silicon nitride, zirconium oxide, or sintered aluminum oxide.

[0068] In one scenario, the assembly stage, particularly with a planetary mill, uses grinding balls or cylinders. For example, the grinding balls are made of stainless steel, aluminum oxide, or zirconium oxide.

[0069] For example, grinding media have a diameter between 0.1 cm and 10 cm, preferably between 0.1 cm and 5 cm. The media can have various shapes, such as spherical or cylindrical. For example, cylindrical grinding media have a diameter between 0.2 and 1 cm and a height between 1 and 5 cm.

[0070] According to a preferred embodiment, the grinding balls are added in a ratio of between 1 / 5 and 6, or even 1 / 5 to 10 times the total weight of the organic matrix and the active ingredient.

[0071] Advantageously, the assembly stage allows for intimate mixing of the materials used, through shocks involving, in particular, fracturing, deformation, which can be plastic, and the bonding of particles in order to promote dispersion and intimate mixing, while maintaining a crystalline organization of the organic molecules.

[0072] The mechanosynthesis process typically results in heating of the components. The assembly step is performed at a temperature lower than the phase change temperature of the active ingredient. Therefore, it is preferable to have a temperature control module during the assembly step. Advantageously, it is the temperature of the mixture comprising the inorganic matrix and the active ingredient that is controlled.

[0073] In one scenario, the assembly step is configured to be performed below the phase change temperature of the asset. For example, pauses are implemented during the assembly step, by stopping or slowing down the grinding process either regularly or as soon as the temperature reaches a ceiling temperature and until the temperature reaches a threshold temperature.

[0074] According to another possibility, the temperature control module includes a cooling system configured to cool and maintain the temperature during the assembly stage below the phase change temperature of the asset.

[0075] The resulting composite material comprises the active material confined within cavities induced by the organizational networks of the inorganic matrix.

[0076] According to one embodiment, the duration of the assembly step is between 15 seconds and 10 hours, preferably a maximum of 1 hour.

[0077] Assembly stage parameters such as mill design, powder mass, ball / powder ratio, grinding speed and time, and working temperature all contribute to obtaining an effective composite material.

[0078] In one embodiment, the process includes a subsequent step of re-aggregating the composite material obtained after the assembly step. This re-aggregation of the composite material obtained after the assembly step is preferably carried out at a temperature above the phase change temperature and leads to the production of beads, granules, or blocks. The re-aggregation step is, for example, performed by a mill, possibly a high-energy or conventional one.

[0079] In one embodiment, the process includes a subsequent step of grinding the composite material obtained after the reaggregation step. Grinding the composite material obtained after the reaggregation step leads to obtaining a composite material in the form of a preferably millimeter-sized powder. This subsequent grinding step is carried out, for example, with a high-energy mill or, preferably, a standard mill. Preferably, this subsequent grinding step is carried out at a temperature below the phase change temperature of the active ingredient. This makes it possible to obtain the composite in the form of a millimeter-sized powder. This embodiment is advantageously used when the phase change temperature of the active ingredient is close to ambient temperature and the mill is not temperature-controlled.

[0080] In one embodiment, the process includes a subsequent step of moistening the composite material obtained after the assembly, reaggregation, or grinding step. This moistening step involves adding a quantity of water to the composite material. The composite material obtained after the moistening step is in the form of an aqueous mixture. Preferably, the quantity of water added is between 1 / 2 and 50 times the weight of the composite material to be moistened. In one alternative embodiment, the subsequent moistening step includes a grinding phase, preferably a high-energy grinding phase, or a mixing phase, for example, manual or mechanical, depending on the desired grain size. The composite material obtained after the grinding phase of the moistening step is in the form of a paste or a cream.

[0081] In one embodiment, the process includes a subsequent step of drying the composite material obtained after the humidification step. Drying is carried out either at ambient temperature, at a temperature below the phase transition, or at a temperature above the phase transition. At this stage, since the composite material is already formed and the active ingredient is already confined within the inorganic matrix, the drying temperature is unlikely to damage the composite material. If the active ingredient changes shape by transitioning to a liquid state, because it is confined within the matrix, there is no leakage or risk of loss. The composite material obtained after the drying step is, for example, in the form of sheets that may or may not be compressible.

[0082] In one embodiment, the process includes a subsequent dispersion step by mechanical agitation of the composite material obtained after the assembly or grinding step. This dispersion step comprises adding the composite material obtained after the assembly or grinding step to an aqueous system, advantageously with mechanical agitation that may be simultaneous with the addition or subsequent to it. The mechanical agitation is, for example, carried out with a magnetic stirrer, a mixer, or a high-performance dispersion device such as a Turrax®. The aqueous system is an aqueous suspension, for example, water, an aqueous suspension of cellulose-based fibers, an aqueous suspension of wood chips, or an aqueous suspension of hydrophilic resins.The composite material obtained after the mechanical agitation dispersion step is in the form of an aqueous suspension that advantageously exhibits stability for several months. Preferably, the amount of composite material added to the aqueous system is between 5 and 20% of the total weight of the resulting aqueous suspension. In this case, the composite material obtained after this step can be described as a suspension of the active ingredient, for example, paraffin, acid, ester, or fatty alcohol, in water stabilized by an inorganic support formed by the inorganic matrix.

[0083] In one embodiment, the process includes a subsequent ultrasonic dispersion step of the composite material obtained after the assembly or grinding step. This dispersion step comprises adding the composite material obtained after the assembly or grinding step to an aqueous system, advantageously with ultrasonication that may be simultaneous with or subsequent to the addition. The ultrasonication is a cavitation process. Preferably, the amount of composite material added to the aqueous system is between 1% and 10%, preferably between 1% and 5%, of the total weight of the resulting aqueous suspension. The aqueous system is an aqueous suspension, for example, water, an aqueous suspension of cellulose-based fibers, an aqueous suspension of wood chips, or an aqueous suspension of hydrophilic resins.The composite material obtained after the ultrasonic dispersion step is in the form of an aqueous gel-type suspension, advantageously exhibiting stability for several months. In this case, the composite material obtained after this step can be described as a suspension of the active ingredient, for example, paraffin, acid, ester, or fatty alcohol, in water stabilized by an inorganic support formed by the inorganic matrix.

[0084] The process, according to any of the embodiments described above, yields high-energy-potential composite materials, also known as Eco-PCMs, for example, in the form of powders, solids, pastes, creams, or suspensions. These forms of composite material allow for easy incorporation into numerous and varied industrial matrices.

[0085] According to one possibility, the process includes a step of incorporating the composite material obtained at the end of the assembly step or the reaggregation step or the grinding step or the humidification step or the dispersion step into a manufacturing process for plaster, cement, mortar, concrete or even paper, plastics, wood compounds.

[0086] This step increases the inertia and energy density of materials through the addition of composite material.

[0087] According to one possibility, the composite material is used in passive or active thermal storage devices. Example 1 Manufacturing process for an active composite material at around 70°C

[0088] For the assembly step, the inorganic matrix and the active ingredient are placed in powder form in a PTFE grinding bowl. The matrix consists of 6 g of sepiolite, and the active ingredient consists of 14 g of stearic acid (SA). Grinding balls in the form of small steel grinding cylinders are added to the grinding bowl. The grinding cylinders have a diameter of 0.3 cm and a length of 2 cm; the mass ratio of cylinders to powder (matrix + active ingredient) is 1:1. The assembly step, i.e., the grinding of the mixture, takes 90 seconds. The mill used is a high-energy mill, specifically a planetary type. The temperature is maintained below the phase transition temperature by allowing the mixture to rest every 30 seconds. The composite material obtained with 70% active ingredient, called Eco-PCM-SA70, is in powder form.

[0089] Depending on the method, a humification step is performed on the resulting composite material. 30 ml of water is poured into the bowl containing the Eco-PCM-SA70 powder and the grinding cylinders. The mixture is ground for 90 seconds, regardless of temperature. A homogeneous paste is obtained. A shaping step then produces a 1 cm thick wafer from this paste. After drying at room temperature, the resulting wafer is solid and can be handled and sawn, retaining its shape above the phase transition.

[0090] The thermal response of this wafer was measured as a function of time ( Figure 2 The tablet weighs 9.762 g, its surface area is 15.75 cm², and its thickness is 1 cm.

[0091] Initially, one surface of the wafer is placed in direct contact with a heating plate; the measuring sensor is positioned on the opposite surface. The wafer is heated to 140°C, 120°C, and 100°C. The time / temperature evolution is measured until the temperature plateau is reached, at which point the Eco-PCM-SA70 charges.

[0092] In a second step, the surface of the wafer is left in contact with ambient air at 20°C, and the temperature-time relationship is measured. The Eco-PCM-SA70 discharges. The higher the surface temperature, the faster the charging rate.

[0093] The thermal response of the plate obtained (1) was compared to that of plates made from sepiolite alone (2) or from a raw mortar (3) ( Figure 3 ). The temperature is 140°C for charging, and 20°C for discharging.

[0094] The time to reach 80°C is 149 s for mortar, 362 s for fibrous clay, and 981 s for Eco-PCM-SA70.

[0095] During cooling the time to reach 50°C is for mortar 361 s, fibrous clay 399 s, Eco-PCM 2477 s.

[0096] On the Figure 3 We observe that after 750 s (12 min 30s) of heating at 140°C the temperatures are for the mortar 119°C, the fibrous clay 95°C, the Eco-PCM 64°C.

[0097] The ability of Eco-PCMs to charge and discharge, as well as their insulating capacity, has thus been clearly demonstrated. The thermal response is proportional to the Active / Substrate ratio. Example 2 Manufacturing process for an active composite material at around 24°C. Eco-PCM-CAMA70: Use of a eutectic manufactured in the same manufacturing step as Eco-PCM.

[0098] For the assembly step, the inorganic matrix and the active ingredient are placed in powder form in a PTFE grinding bowl. The matrix comprises 6 g of sepiolite, and the active ingredient comprises 10.08 g of capric acid (CA) and 3.92 g of myristic acid (MA). Grinding balls in the form of small steel grinding cylinders are added to the grinding bowl. The grinding balls have a diameter of 0.3 cm and a length of 2 cm, with a mass ratio of cylinders to powder (matrix + active ingredient) of 1:1. The assembly step, i.e., the grinding of the mixture, takes eight 15-second cycles with pauses to allow the bowl to return to ambient temperature. The resulting composite material, containing 70% active ingredient and also known as Eco-PCM-CAMA70, is in powder form.

[0099] It is noted that the experimental conditions used allowed for the fabrication of an effective eutectic confined within the sepiolite, in the presence of the support during the Eco-PCM manufacturing step. Indeed, the infrared spectra clearly show the existence of an intimate mixture between CA and MA in the Eco-PCM-CAMA70 powder. figure 4This is indeed an infrared spectrum of the carbonyl groups (VCO) of: (1) capric acid (CA), (2) myristic acid (MA), and (3) the CAMA mixture obtained in Eco-PCM-CAMA70 powder. An infrared spectrum (not shown) of the hydrogenated chain (VCH) CH groups of: (1) capric acid (CA), (2) myristic acid (MA), and (3) the CAMA mixture obtained in Eco-PCM-CAMA70 powder was also obtained. The infrared bands of the chain and functional groups are clearly shifted, which implies the presence of a homogeneous eutectic mixture. The shift of the VCH band towards higher wavenumbers corresponds to a less compact crystalline form, which explains the melting point of the mixture at 24°C instead of 31°C for capric acid and 54.4°C for myristic acid.

[0100] The wavelengths of the carbonyl groups (VCO) and the CH groups of the hydrogenated chain (VCH) are given below for each curve: (1) capric acid - CA : VCO at 1699 cm -1< (2) myristic acid - MA : VCO at 1699 cm -1< (3) CAMA mixture - Eco-PCM-CAMA70 powder : VCO at 1711cm -1< (1) capric acid - CA : VCH at 2918 cm -1< (2) myristic acid - MA : VCH at 2916 cm -1< (3) CAMA mixture - Eco-PCM-CAMA70 powder : VCH at 2928 cm -1<

[0101] Depending on the method, a humification step is performed on the resulting composite material. 30 ml of water and 20 g of Eco-PCM-CAMA70 powder are added to the bowl containing the grinding cylinders, and the mixture is ground for 90 seconds, regardless of temperature. This produces a homogeneous paste. A shaping step then produces a 1 cm thick plate from this paste. After drying at room temperature, the resulting solid plate can be handled and sawn, and has the same composition as the powder.

[0102] The thermal response of this Eco-PCM-CAMA70 wafer was measured as a function of time ( Figure 5The wafer, initially at 4°C, is heated to 40°C during charging and cooled to 4°C during discharging. The active temperature range of the wafer is between 19 and 24°C. The time taken for the wafer, heated to 40°C, to reach 26°C (i.e., to be charged) is 1087 s, and during cooling, it begins discharging at 24°C after 557 s. Figure 6 demonstrates the effectiveness of the wafer cooled to 4°C when one of its surfaces is exposed to the sun. Example 3 Eco-PCM-SA70 Composite Material Filled Mortar

[0103] The Eco-PCM-SA70 powder, as prepared in Example 1, is mixed with a commercial mortar. The percentage of Eco-PCM-SA70 powder in the mortar varies from 10% to 90% by weight. After the dry mixture has been homogenized, water is added and the mixture is kneaded (spun) with a trowel. The resulting paste is molded and dried at room temperature.

[0104] Eco-PCM mortar plates that can incorporate between 7 and 63% active ingredients are manufactured; it is noted that the samples retain their shape at 100°C and that the active molecules are confined, as no grease stains are observed on the blotting paper supporting the samples after 1 hour 30 minutes at 100°C.

[0105] The thermal response ( figure 7 The concentration of this Eco-PCM-loaded mortar was measured over time by applying a fixed ambient temperature of 90°C, 100°C, 120°C, or 140°C. The measuring sensor was positioned on the opposite surface. The time / temperature relationship was measured until the plate reached a temperature plateau, at which point it became charged. Subsequently, the plate surface was exposed to ambient air at 20°C, and the time / temperature relationship was measured again, observing the discharge stage.

[0106] The heat storage and release time is very clearly visible in the 50-70°C zone ( Figure 7). This time varies very clearly with the external temperature applied to the wafer during charging; the time taken to reach 70°C is 550 s, 930 s and 1470 s for the wafer heated to 140°C, 120°C and 100°C respectively; the time to reach 20°C during cooling from these same temperatures varies little, 676 s, 636 s and 500 s.

[0107] THE Figures 8A And 8B They compare the thermal responses of mortar tiles (2) and sepiolite tiles without additives (3) to the response of the mortar tile loaded with Eco-PCM (1). The shape of the curves and the heating times highlight a thermal insulation effect linked to the charging and discharging time of the Eco-PCM incorporated into the mortar. Example 4 Cardboard filled with Eco-PCM-SA70 composite material

[0108] Shipping box cardboard is soaked in water for at least 4 hours. After being wrung out and cut into pieces a few centimeters long, the cardboard is dispersed in water using a blender or a Turrax (10 g in 2 liters of water, 10 min, power setting 4). The goal is to achieve a good dispersion of cellulose fibers. After dispersing in water using the Turrax for 5 min at power setting P4, Eco-PCM-SA70 composite material powder, as prepared in Example 1, is added. The percentage of Eco-PCM-SA70 powder in the cardboard varies from 5% to 80%, most commonly 60%.

[0109] The mixture is then blended with Turrax (10 minutes at power level 4). The resulting suspension is deposited onto a fine mesh and pressed to remove water and retain the paste (mat). The mat is then dried at room temperature or in an oven; drying can occur below or above the phase transition. Eco-PCM-based cardboards, containing up to 80% Eco-PCM (56% active), are thus produced.

[0110] There Figure 9This study compares the thermal response of board manufactured with Eco-PCM-SA70 powder (1) to the thermal response of molded board (2) of the same thickness. The external temperature applied to the board's surface is 100°C for load A and 20°C for discharge B. Heat storage and release are clearly visible in the 50-70°C range. The time to reach 80°C is 227 s for the reference board and 509 s for the Eco-PCM board. During cooling, the time to reach 50°C is 174 s for the reference board and 308 s for the Eco-PCM board. After 400 s of heating to 100°C, the temperature of the Eco-PCM board is 76°C, while it is 86°C for the reference board. Example 5 Eco-PCM-PARA50 composite material-filled polyethylene

[0111] An Eco-PCM in powder form is produced according to the process of Example 1, where the matrix consists of sepiolite and the active ingredient is paraffin, the active ingredient representing 50% by weight of the total weight of the matrix and active ingredient. A composite material in powder form is obtained and named Eco-PCM-PARA50.

[0112] The resulting composite material, Eco-PCM-PARA50, is introduced into high-density polyethylene (PE RIGIDEX) heated to its melting point of 160°C. The assembly is then cooled. Polyethylene sheets and particles filled with 50% and 73% Eco-PCM-PARA50 were thus produced. Differential scanning calorimetry (DSC) analyses of the latent energy stored (positive sign) and then released (negative sign) were performed on these PEs filled with 73% Eco-PCM-PARA50 (i.e., 36.5% paraffin) during heating and cooling cycles. The cycles ranged from -50°C to 100°C, with a temperature change of 10°C / min. These analyses demonstrate the energy storage and release capacities of these polymers. Eco-PCM retained its charge and discharge capabilities after being introduced into PE. Temperature range: -50°C to 100°C Table 1 Heating TpM(°C) HM(J / g) 73% of ECO-PCM-PARA50 58,37 +48,8 50% off ECO-PCM-PARA50 56,94 +26,58 Temperature -100°C to around 50°C Table 2 Cooling TpC(°C) HC(J / g) 73% ECO-PCM-PAR50 49,7 -50,97 50% off ECO-PCM-PARA50 50,42 -31,79 Example 6 Eco-PCM-PARA50 Composite Material Filled Polyvinyl Acetate

[0113] The same Eco-PCM-PARA50 composite material from Example 5 is obtained and mixed with a commercial aqueous polyvinyl acetate (PVAc) emulsion using an Ultra Turrax. The concentration of Eco-PCM-PARA50 in the emulsion is 12.5%. This suspension is dried in a Teflon mold at room temperature.

[0114] The analyses are carried out after demolding. The concentration of Eco-PCM-PARA50 in the solid is then 32.5%.

[0115] Differential scanning calorimetry (DSC) analyses of the stored (positive sign) and released (negative sign) latent energy were performed on PVAc panels loaded with 32.5% Eco-PCM-PARA50 during heating and cooling cycles. In cycles ranging from -50°C to 100°C, the temperature variation was 10°C / min. The Eco-PCM retained its thermal storage and release capacities after its introduction into the PVAc. Temperature range: -50°C to 100°C Table 3 Heating TpM (°C) HM (J / g) 32% of Eco-PCM-PARA50 57,42 +30,6 Temperature -100°C to around 50°C Table 4 Cooling TpC (°C) HC (J / g) 32% Eco-PCM-PARA50 51,58 -28,76 Example 7 Increasing the thermal conductivity of an Eco-PCM-SA70 by adding 2% carbon nanotubes

[0116] An Eco-PCM in powder form is produced according to the process of Example 1, the matrix of which consists of sepiolite and the active ingredient of stearic acid and carbon nanotubes, resulting in a composite material comprising 70% stearic acid and 2% carbon nanotubes. To obtain 50 g of composite material, 35 g of stearic acid, 1 g of carbon nanotubes, and 14 g of sepiolite are mixed.

[0117] Depending on the method, a humification step is performed on the resulting composite material. 50 ml of water is added to the bowl along with 50 g of Eco-PCM-SA70 NPC2 powder and the grinding cylinders. The mixture is ground for 90 seconds, regardless of temperature. A homogeneous paste is obtained. A shaping step then produces a 1 cm thick wafer from this paste. After drying at room temperature, a solid Eco-PCM-SA70-NPC2 wafer is obtained, which can be handled and sawn, and has the same composition as the powder.

[0118] The analyses are performed after demolding. The Eco-PCM-SA70-NPC2 and Eco-PCM-SA70 are placed in contact with a heating plate and insulated, while the temperature of the surface opposite the plate is connected via sensors to a temperature recorder. The Eco-PCM-SA70-NPC2 has a faster thermal response than the Eco-PCM-SA70 during the heating and cooling stages ( Figure 10 ).

[0119] The invention is not limited to the embodiments previously described and extends to all embodiments covered by the invention. List of references:

[0120] 1. Grinding ball 2. Active ingredient 3. Inorganic matrix 4. Bowl

Claims

1. Method for synthesising a composite material comprising an inorganic matrix and an active ingredient, the active ingredient being a phase-change material (PCM): characterised in that the method comprises at least one step of assembling the active ingredient into the matrix by mechanosynthesis carried out without a solvent in a high-energy mill at a temperature lower than the phase change temperature of the active ingredient, the active ingredient being a solid-liquid PCM.

2. Method according to the preceding claim, wherein the assembly step by mechanosynthesis is carried out in the presence of grinding beads having a diameter of between 1 mm and 100 mm.

3. Method according to the preceding claim, wherein the grinding beads represent from 1 / 5 to 10 times the total weight of the matrix and the active ingredient.

4. Method according to any one of the preceding claims, wherein the assembly step by mechanosynthesis lasts from 15 seconds to 10 hours.

5. Method according to any one of the preceding claims, wherein the active ingredient represents from 1 to 90% by weight of the total weight of the matrix and active ingredient.

6. Method according to any one of the preceding claims, wherein the matrix is selected from: - a clay of the family of clay minerals of the TO, TOT or TOT+O type which are in platelet, tubular or fibrous form, for example kaolinites, bentonites, perlites, vermiculites, montmorillonites, halloysites, sepiolites, palygorskites, or - mineral oxides or hydroxides, for example micronised calcium carbonate derivatives, marble powders, silica derivatives of diatomites, microsilica, nanosilica, or - carbon in the form of graphite, nanofibre or fullerene, and metal oxides.

7. Method according to any one of the preceding claims, wherein the active ingredient is selected from the families of paraffins, saturated fatty acids, saturated fatty alcohols, fatty acid esters, polyethylene glycols, alone or in a mixture thereof.

8. Method according to any one of the preceding claims, wherein the composite material obtained at the end of the assembly step is in the form of micrometric powder.

9. Method according to any one of the preceding claims comprising a subsequent step of reaggregating the composite material obtained at the end of the assembly step, the composite material obtained at the end of the reaggregating step being in the form of pellets, granules or cakes.

10. Method according to the preceding claim, comprising a subsequent step of grinding the composite material obtained at the end of the reaggregation step, the composite material obtained at the end of the grinding step being in the form of micrometric powder.

11. Method according to any one of the preceding claims comprising a subsequent step of humidifying the composite material obtained at the end of the assembly step or the reaggregating step or the grinding step, comprising adding an amount of water to said composite material, the composite material obtained at the end of the humidifying step being in the form of an aqueous mixture, the humidifying step being performed by adding an amount of water between 0.5 and 50 times the weight of the composite material to be humidified.

12. Method according to the preceding claim comprising a subsequent step of drying the composite material obtained at the end of the humidifying step, the composite material obtained at the end of the drying step being in the form of plates.

13. Method according to any one of the preceding claims comprising: - a subsequent step of dispersing by mechanical stirring the composite material obtained at the end of the assembly step or the grinding step, comprising adding an aqueous system to said composite material with mechanical stirring, the composite material obtained at the end of the step of dispersing by mechanical stirring being in the form of an aqueous suspension, or - a subsequent step of dispersing by ultrasonication the composite material obtained at the end of the assembly step or the grinding step, comprising the addition of an aqueous system to said composite material with stirring by ultrasonication, the composite material obtained at the end of the step of dispersing by ultrasonication being in the form of a gel.

14. Method according to the preceding claim, wherein an amount from 1 to 10% of composite material powder is added to water or an aqueous system.

15. Method according to any one of the preceding claims comprising a step of incorporating the composite material obtained at the end of the assembly step or the reaggregation step or the grinding step or the humidifying step or the dispersion step into a method for manufacturing plaster, cement, mortar, concrete or even paper, plastics, or wood composites.