Synthesis process for a composite material capable of storing and releasing thermal energy

Abstract

Method for synthesizing a composite material capable of storing and releasing thermal energy. The invention relates to a method for synthesizing a composite material comprising an inorganic matrix and an active ingredient, the active ingredient being a phase-change material, characterized in that the method comprises at least one step of assembling the active ingredient into the matrix by mechanosynthesis. The present invention relates to the field of composite materials and their manufacture. More particularly, it relates to methods for synthesizing composite materials. The invention will find more specific application for composite materials intended to regulate energy inputs and losses, particularly in the fields of building construction, textiles, packaging, electronics, transportation, and renewable energy. Figure for the abstract: Fig. 1

Description

Title of the invention: Process for synthesizing a composite material capable of storing and releasing thermal energy. Technical field

[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 a more specific application for composite materials intended to store thermal energy and to regulate 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, including the fact that they allow the properties of their constituent components to be combined.

[0003] In the literature and at the industrial level, phase change materials (PCMs) are used for their ability to store and release latent heat during their phase transition, particularly from solid to liquid. When introduced undiluted into conventional materials, they exhibit morphological changes during the phase change, which lead to leakage, corrosion, and a reduction in the stability of the thermal response. They are therefore 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] There is therefore a need to propose a process which makes it possible to offer reliable composite materials and whose manufacture is simplified.

[0006] 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

[0007] 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.

[0008] 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.

[0009] The composite material obtained has high energy value and comprises on the one hand an inorganic matrix and on the other hand one or more actives confined in this matrix.

[0010] 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.

[0011] The manufacturing process is environmentally friendly.

[0012] Advantageously, the process, and more particularly the assembly step, does not require the use of a solvent. The absence of a solvent simplifies the process and makes it more environmentally friendly. The process is advantageously carried out without producing any waste. The process according to the invention is energy-efficient.

[0013] Another aspect relates to a composite material obtained by the present process characterized in that, at the end of the assembly step, the composite material is in the solid state, the active ingredient being confined in the inorganic matrix.

[0014] Another aspect concerns a material which includes the composite material, the material being for example plaster, cement, mortar, concrete or even wood, paper, plastics, textile. BRIEF DESCRIPTION OF THE FIGURES

[0015] 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:

[0016] [Fig.1] Fig.1 represents a schematic diagram of the assembly step comprising high-energy grinding.

[0017] [Fig.2] Fig.2 represents a thermal response during loading and discharge of a plate according to example 1.

[0018] [Fig.3] Fig.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).

[0019] [Fig.4] Fig.4 represents an infrared spectrum of the carbonyl groups (VC0) of : (1) capric acid named CA, (2) myristic acid MA, (3) the CAMA mixture obtained in the Eco-PCM-CAMA70 composite material powder obtained in example 2.

[0020] [Fig. 5] Figure 5 represents the thermal response of a composite material the Eco-PCM CAMA 70 obtained in example 2 in the form of a platelet.

[0021] [Fig. 6] Fig. 6 represents the thermal response of the Eco-PCM composite material. CAMA 70 obtained in example 2 in the form of a plate at 4°C heated to 40°C (1) or exposed to the sun in April (2).

[0022] [Fig.7] Fig.7 represents the thermal response of the Eco-PCM mortar in the example 3 composed of 90% powder of an Eco-PCM-SA70 composite material obtained in example 1 and 10% mortar.

[0023] [Fig. 8A] Figures 8A and 8B compare respectively the thermal responses of mortar tiles (2) and additive-free sepiolite tiles (3) were compared 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 related to the charging and discharging time of the composite material integrated into the mortar.

[0024] [Fig.8B]

[0025] [Fig.9] Fig.9 represents the comparison of the thermal response of a cardboard 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 (2). The applied temperature is 100°C for charge A, and 20°C for discharge B.

[0026] [Fig. 10] Fig. 10 represents the thermal response during charging and discharging of SepSA70 composite material plates (1) and SepSA70 composite material plates with 2% carbon nanoparticles (2) obtained in example7.

[0027] The drawings are given by way of example and are not limiting of 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

[0028] Before proceeding with a detailed review of embodiments of the invention, optional features that may be used in combination or alternatively are listed below:

[0029] According to one example, the mechanosynthesis assembly step is carried out at a temperature lower than the phase change temperature of the active ingredient.

[0030] According to one example, the mechanosynthesis assembly step is carried out in a high-energy mill.

[0031] According to one example, the mechanosynthesis assembly step is carried out without solvent.

[0032] According to one example, the mechanosynthesis assembly step is carried out in the presence of grinding balls.

[0033] According to one example, the grinding balls have a diameter between 1 mm and 100 mm.

[0034] According to one example, the grinding balls represent 1 / 5 to 6 times the total weight of the matrix and the active ingredient.

[0035] According to one example, the assembly step by mechano synthesis lasts from 15 seconds to 1 hour.

[0036] According to one example, the asset represents from 1 to 90% by weight of the total weight of matrix and asset.

[0037] According to one example, the matrix is ​​chosen from: - a clay from the family of clay minerals of type TO, TOT or TOT+O which occur 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 from diatomites, microsilicas, nanosilicas, or - carbon in the form of graphite, nano fiber or fullerene, and metal oxides.

[0038] 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 mixture.

[0039] According to one example, the asset is a solid-liquid MCP.

[0040] According to one example, the composite material obtained at the end of the assembly step is in the form of micrometric powder.

[0041] 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.

[0042] According to one example, the process includes 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 is in the form of micrometric powder.

[0043] According to one example, the process includes a subsequent step of humidifying 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 humidification step is in the form of an aqueous mixture.

[0044] According to one example, the humidification step is carried out by adding a quantity of water between 0.5 and 50 times the weight of the composite material to be humidified.

[0045] 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.

[0046] According to 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.

[0047] According to one example, the process includes a subsequent step of dispersing by mechanical agitation the composite material obtained at the end of the assembly step or the grinding step comprising the addition of an aqueous suspension to said composite material with mechanical agitation, the composite material obtained at the end of the dispersion step by mechanical agitation is in the form of an aqueous suspension.

[0048] 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, comprising the addition of an aqueous suspension to said composite material with ultrasonic agitation; the composite material obtained at the end of the ultrasonic dispersion step is in gel form.

[0049] According to one example, a quantity of composite material powder from 1 to 10% is added to water or an aqueous solution.

[0050] 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 process for manufacturing plaster, cement, mortar, concrete or even paper, plastics, wood compounds.

[0051] 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.

[0052] The active ingredient is advantageously bio-based. The active ingredient is advantageously capable of storing and releasing thermal energy. Preferably, the active ingredient is a phase-change material, advantageously alternating between a solid and a liquid form around a phase transition temperature.

[0053] As a preferred example, the active ingredient is chosen from paraffins or paraffinic derivatives, preferably saturated fatty acids, preferably saturated fatty alcohols, fatty acid esters, polyethylene glycols.

[0054] The composite material comprises at least one active ingredient; in one possibility, the composite material comprises several active ingredients selected from the list above. The active ingredients are then a mixture. In the remainder of this description, reference is made to "an active ingredient" or "the active ingredient" for the sake of simplicity and without limitation.

[0055] The asset advantageously has a phase change temperature ranging from -20°C to 300°C.

[0056] The active ingredient is advantageously in solid form, preferably in powder form.

[0057] The inorganic matrix is ​​advantageously geosourced. The main role of the inorganic matrix is ​​to support the asset.

[0058] 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 occur 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 from diatomites, microsilicas, nanosilicas, or - carbon compounds known as 1D, 2D or 3D such as carbon nanotubes, graphene or expanded carbon, graphite, nanofiber or fullerene, or - metal oxides, or - semiconductors.

[0059] The inorganic matrix is ​​advantageously 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.

[0060] It is specified that in the context of the present invention, the term composite material is an assembly of at least two non-miscible components, but exhibiting a high capacity for containment.

[0061] The composite material obtained by the process according to the invention is, at the end of the assembly step, in the form of a powder preferably of micrometric size.

[0062] According to one possibility, the composite material is integrated into other traditional materials such as plaster, cement, mortar, concrete or even wood, paper, plastics.

[0063] The composite material obtained by the process according to the invention and the traditional materials incorporating said composite material have the advantage of regulating energy inputs and losses in various fields such as building, textiles, packaging, electronics or even renewable energies.

[0064] The composite material is capable of storing and releasing thermal energy.

[0065] The composite material obtained by the process according to the invention is of high value energy.

[0066] The composite material advantageously has an operating temperature range of -20°C to 300°C.

[0067] Advantageously, the composite material does not change volume during the phase change and thus advantageously retains dimensional stability.

[0068] The synthesis process according to the invention includes a step of assembling the inorganic matrix and at least one active ingredient.

[0069] The assembly step is carried out according to the invention by mechanosynthesis or mechano-transformation. 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.

[0070] Mechanosynthesis is understood to mean a step consisting of mixing, or even grinding together, at least two components until a composite material is formed.

[0071] 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%.

[0072] The assembly step is advantageously carried out without the addition of solvent. The assembly step is advantageously carried out with solid components.

[0073] According to one possibility of the invention, the assembly step is carried out by a high-energy crusher.

[0074] During the assembly step, the active ingredient and the inorganic matrix undergo mechanical transformations such as the flattening, welding, fracturing, and / or re-welding of the particles of these elements. The assembly step involves, in particular, impact and friction phenomena.

[0075] Impacts and friction promote size reduction and the disintegration of particles, agglomerates, and granules based on crystallized organic molecules, thereby maximizing contact surfaces while generating new surfaces and creating defects, as illustrated in [Fig. 1]. The alternating plastic deformation, fracture, and bonding leads to the fabrication of an organic / inorganic composite material capable of storing and releasing heat. In [Fig. 1], the beads 1, the active ingredient 2, and the inorganic matrix 3 are placed in a bowl 4. [Fig. 1] illustrates the impacts and friction that ensure the integration of the active ingredient 2 into the matrix 3.

[0076] 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 retention of the active ingredient 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 mixture is advantageously managed so as to promote physical interactions and prevent chemical reactions that could disrupt the organization of the crystalline network of organic molecules.

[0077] Advantageously, confining the active ingredient in the inorganic matrix increases its fire stability.

[0078] Advantageously, the use of a bio-based active ingredient and a geo-based inorganic matrix in said process makes it possible to manufacture recyclable composite materials.

[0079] Advantageously, the process makes it possible to obtain a composite material which does not release the active ingredient during its phase change.

[0080] According to one example, the mill is a high energy mill of the planetary, vibrational or agitator ball mill type.

[0081] According to one possibility, in the case of planetary mills, the assembly step is carried out by mixing the active ingredient and the inorganic matrix in a mixing bowl. The mixing bowl is, for example, a bowl made of steel, PTFE, agate, tungsten carbide, silicon nitride, zirconium oxide, or sintered aluminum oxide.

[0082] According to one possibility, the assembly step, 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.

[0083] By way of example, the grinding balls have a diameter between 0.1 cm and 10 cm, preferably between 0.1 cm and 5 cm. The balls can have various shapes such as spherical or cylindrical. For example, cylindrical grinding balls have a diameter between 0.2 and 1 cm and a height between 1 and 5 cm.

[0084] According to a preferred embodiment, the grinding balls are added in a ratio of between 1 / 5 and 6 times the total weight of the organic matrix and the active ingredient.

[0085] Advantageously, the assembly step 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.

[0086] The mechanosynthesis mechanism typically results in heating of the components. Preferably, the assembly step is carried out at a temperature lower than the phase change temperature of the active ingredient. It is therefore 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.

[0087] According to one possibility, the assembly step is configured to be carried out below the phase change temperature of the active ingredient. For example, pauses are made during the assembly step, either by stopping or slowing down the grinding or by regulating linked either as soon as the temperature reaches a ceiling temperature and as long as the temperature has not reached a threshold temperature.

[0088] According to another possibility, the temperature control module includes a cooling system configured to cool and maintain the temperature during the assembly step below the phase change temperature of the asset.

[0089] According to one possibility, the assembly step can be carried out at least partially at a temperature higher than the phase change temperature of the active ingredient, however the assembly step is carried out by mechanosynthesis and allows the composite material to be obtained.

[0090] The composite material obtained comprises the active material confined in cavities induced by the organizational networks of the inorganic matrix.

[0091] According to one embodiment, the duration of the assembly step is between 15 seconds and 10 hours, preferably a maximum of 1 hour.

[0092] The parameters of the assembly stage such as for example the design of the mill, the mass of powder, the ball / powder ratio, the speed and time of grinding as well as the working temperature contribute to obtaining an effective composite material.

[0093] According to one embodiment, the process includes a subsequent step of re-aggregating the composite material obtained after the assembly step. Re-aggregation of the composite material obtained after the assembly step is advantageously 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, carried out by a mill, possibly a high-energy or conventional one.

[0094] According to 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.

[0095] According to one embodiment, the process includes a subsequent step of moistening the composite material obtained at the end of the assembly step, the reaggregation step, or the grinding step. This moistening step including the addition of a quantity of water to the composite material. The composite material obtained after the humidification 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 humidified. Optionally, the subsequent humidification step includes a grinding phase, preferably high-energy grinding, 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 humidification step is in the form of a paste or a cream.

[0096] According to one embodiment, the process includes a subsequent step of drying the composite material obtained after the humidification step. The 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, since it is confined within the matrix, there is no leakage or risk of losing the active ingredient. The composite material obtained after the drying step is, for example, in the form of sheets that may or may not be compressible.

[0097] According to 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 carried out, for example, 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 aqueous suspensions of hydrophilic resins.The composite material obtained after the mechanical agitation dispersion step is in the form of an aqueous suspension advantageously exhibiting 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 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 aqueous suspensions of hydrophilic resins. 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.

[0098] According to 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 the addition or subsequent to it. The ultrasonication is a cavitation. Preferably, the quantity of composite material added to the aqueous system is between 1% and 10%, preferably between 1% and 5%, of the total weight of the aqueous suspension obtained. The aqueous system is an aqueous suspension, for example, water, an aqueous suspension of cellulose-based fibers, an aqueous suspension of wood chips, or aqueous suspensions 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.

[0099] The process according to any of the above-described embodiments makes it possible to obtain 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.

[0100] 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 process for manufacturing plaster, cement, mortar, concrete or even paper, plastics, wood compounds.

[0101] This step makes it possible to increase the inertia and energy density of materials by adding composite material.

[0102] According to one possibility, the composite material is used in passive or active thermal storage devices.

[0103] Example 1

[0104] Method for manufacturing a composite material that is active around 70°C

[0105] 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 the cylinders to the powder (matrix + active ingredient) is 1:1. The time of the step The assembly, i.e., 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 resulting composite material, with 70% active ingredients, called Eco-PCM-SA70, is in powder form.

[0106] According to one possibility, a humidification step is carried out on the resulting composite material. 30 ml of water are poured into the bowl containing the Eco-PCM-SA70 in powder form and the grinding cylinders. The mixture is ground for 90 seconds, regardless of temperature. A homogeneous paste is obtained. A shaping step is performed to produce a 1 cm thick wafer from this paste. After a drying step at room temperature, a solid wafer is obtained that can be handled, sawn, and retains its shape above the phase transition.

[0107] The thermal response of this wafer was measured as a function of time ([Fig.2]). The wafer weighs 9.762 g, its surface area is 15.75 cm2, and its thickness is 1 cm.

[0108] 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, 100°C. The time / temperature evolution is measured until the temperature plateau is reached, the Eco-PCM-SA70 charges.

[0109] In a second step, the surface of the wafer is left in contact with ambient air, i.e., 20°C, and the temperature-time evolution is measured. The Eco-PCM-SA70 discharges. The higher the temperature at the surface, the faster the charging rate.

[0110] 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) ([Fig.3]). The temperature was 140°C for loading and 20°C for unloading.

[0111] The time to reach 80°C is 149 s for mortar, 362 s for fibrous clay, and 981 s for Eco-PCM-SA70.

[0112] During cooling the time to reach 50°C is for the mortar 361 s, the fibrous clay 399 s, the Eco-PCM 2477 s.

[0113] On [Fig.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.

[0114] 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.

[0115] Example 2

[0116] Process for manufacturing an active composite material around 24°C, Eco-PCM-CAMA70 — Use of a eutectic manufactured in the same manufacturing step as the Eco-PCM

[0117] 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, and the mass ratio of cylinders to powder (matrix + active ingredient) is 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 designated Eco-PCM-CAMA70, is in powder form.

[0118] It is noted that the experimental conditions used made it possible to produce 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 4 is, in fact, an infrared spectrum of the carbonyl groups (VCO) of: (1) capric acid, designated CA, (2) myristic acid, MA, and (3) the CAMA mixture obtained in the Eco-PCM-CAMA70 powder. An infrared spectrum (not shown) of the CH groups of the hydrogenated chain (VCH) of: (1) capric acid, designated CA, (2) myristic acid, MA, and (3) the CAMA mixture obtained in the Eco-PCM-CAMA70 powder was also obtained. The infrared bands of the chain and functional groups are clearly offset, which implies the presence of the homogeneous eutectic mixture.The shift of the VCH band towards higher wavenumbers corresponds to a less compact crystalline form, which explains the melting temperature of the mixture at 24°C instead of 31°C for capric acid and 54.4°C for myristic acid.

[0119] 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 cm1 (2) myristic acid - MA: VCO at 1699 cm1 (3) CAMA mixture - Eco-PCM-CAMA70 powder: VCO at 1711cm 1 (1) capric acid - CA: VCH at 2918 cm1 (2) myristic acid - MA: VCH at 2916 cm1 (3) CAMA mixture - Eco-PCM-CAMA70 powder: VCH at 2928 cm1

[0120] According to one possibility, a humidification step is carried out on the resulting composite material. 30 ml of water and 20 g of Eco-PCM-CAMA70 powder are poured into the bowl containing the grinding cylinders, and the mixture is ground for 90 seconds, regardless of temperature. A homogeneous paste is obtained. A shaping step is then performed to produce a 1 cm thick plate from this paste. After a drying step At room temperature, a solid plate is obtained which can be handled, sawn, and whose composition is identical to that of the powder.

[0121] The thermal response of this Eco-PCM-CAMA70 wafer was measured as a function of time ([Fig. 5]). The wafer, 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 by 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. [Fig. 6] demonstrates the efficiency of the wafer cooled to 4°C when one of its surfaces is exposed to sunlight.

[0122] Example 3

[0123] Eco-PCM-SA70 composite material-filled mortar

[0124] 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 incorporated and the mixture is kneaded (spun) with a trowel. The resulting paste is molded and dried at room temperature.

[0125] 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 1h30 at 100°C.

[0126] The thermal response ([Fig. 7]) 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 temperature plateau was reached, at which point the plate became charged. Subsequently, the surface of the plate was left in contact with ambient air at 20°C, and the time / temperature relationship was measured again, observing the discharge stage.

[0127] The heat storage and release time is very clearly visible in the 50-70°C zone ([Fig.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.

[0128] Figures 8A and 8B compare the thermal responses of mortar tiles (2) and sepiolite tiles without additives (3) respectively 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 related to the charging and discharging time of the Eco-PCM incorporated into the mortar.

[0129] Example 4

[0130] Cardboard filled with Eco-PCM-SA70 composite material

[0131] Cardboard from shipping boxes 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 for 10 minutes at power level 4). The aim is to obtain a good dispersion of cellulose fibers. After dispersion in water using a Turrax for 5 minutes at power level P4, the Eco-PCM-SA70 composite material powder, as prepared in Example 1, is then added. The percentage of Eco-PCM-SA70 powder in the cardboard varies from 5% to 80%, more commonly 60%.

[0132] The mixture is blended with Turrax (10 min, Power 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 take place below or above the phase transition. Eco-PCM-based cardboards, containing up to 80% Eco-PCM (i.e., 56% active), are thus produced.

[0133] Figure 9 compares the thermal response of the board made with Eco-PCM-SA70 powder (1) to the thermal response of a molded board (2) of the same thickness. The external temperature applied to the outer surface of the board 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 and 308 s for the reference board and the Eco-PCM board, respectively. 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.

[0134] Example 5

[0135] Polyethylene filled with Eco-PCM-PARA50 composite material

[0136] An Eco-PCM in powder form is produced according to the process of Example 1, the matrix of which is made of sepiolite and the active ingredient is made of paraffin, the active ingredient representing 50% by weight of the total weight of the matrix + active ingredient. A composite material in powder form is obtained and named Eco-PCM-PARA50.

[0137] The composite material obtained Eco-PCM-PARA50 is introduced into high-density polyethylene (PE RIGIDEX) heated to its melting point of 160°C, the whole is then cooled.

[0138] Polyethylene sheets and particles filled with 50% and 73% Eco-PCM-PARA50 were thus manufactured. Differential scanning calorimetry (DSC) analyses of the stored (positive sign) and then released (negative sign) latent energy were performed on these PE sheets filled with 73% Eco-PCM-PARA50, i.e., 36.5% paraffin, during cycles of

[0139]

[0140]

[0141]

[0142]

[0143]

[0144]

[0145]

[0146]

[0147]

[0148]

[0149]

[0150] Heating and cooling cycles from -50 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 charging and discharging capacities after its introduction into PE. Temperature -50°C to 100°C [Tables 1] Heating TpM(°C) HM(J / g) 73% of ECO-PCM-PARA50 58.37 +48.8 50% of ECO-PCM-PARA50 56.94 +26.58 Temperature -100°C to 50°C [Table 2] Cooling TpC (°C) HC (J / g) 73% of ECO-PCM-PAR50 49.7 -50.97 50% of ECO-PCM-PARA50 50.42 -31.79 Example 6 Eco-PCM-PARA50 Composite Material Filled Polyvinyl Acetate 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. The analyses are carried out after demolding. The concentration of Eco-PCM-PARA50 in the solid is then 32.5%. 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 to 100°C, the temperature change was 10°C / min. The Eco-PCM retained its thermal storage and release capacities after its introduction into the PVAc. Temperature -50°C to 100°C [Tables 3] Heating TpM (°C) HM (J / g) 32% of Eco-PCM-PARA50 57.42 +30.6 Temperature -100°C to around 50°C

[0151] [Tables4] Cooling TpC (°C) HC (J / g) 32% Eco-PCM-PARA50 51.58 -28.76

[0152] Example 7

[0153] Increasing the thermal conductivity of an Eco-PCM-SA70 by adding 2% carbon nanotubes

[0154] An Eco-PCM in powder form is prepared according to the process of Example 1, the matrix of which consists of sepiolite and the active ingredient of stearic acid and carbon nanotubes, so as to obtain 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.

[0155] According to one possibility, a humidification step is carried out on the resulting composite material. 50 ml of water are added to the bowl along with 50 g of Eco-PCM-SA70 NPC2 powder and the grinding rollers. The mixture is ground for 90 seconds, regardless of temperature. A homogeneous paste is obtained. A shaping step is performed to produce 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 whose composition is identical to that of the powder.

[0156] 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 ([Fig. 10]).

[0157] The invention is not limited to the embodiments previously described and extends to all embodiments covered by the invention.

[0158] List of references: 1. Grinding ball 2. Active 3. Inorganic Matrix 4. Bowl

Claims

Demands

1. A process for synthesizing a composite material comprising an inorganic matrix and an active, the active being a phase-change material: characterized in that the process comprises at least one step of assembling the active into the matrix by mechanosynthesis carried out without solvent in a high-energy mill at a temperature below the phase-change temperature of the active, the active being a solid-liquid PCM.

2. A method according to the preceding claim in which the mechanosynthesis assembly step is carried out in the presence of grinding balls.

3. A method according to the preceding claim in which the grinding balls have a diameter between 1 mm and 100 mm.

4. A method according to any one of the two preceding claims wherein the grinding balls represent from 1 / 5 to 6 times the total weight of the matrix and the active ingredient.

5. A method according to any one of the preceding claims wherein the mechanosynthesis assembly step lasts from 15 seconds to 1 hour.

6. A 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 matrix and active ingredient.

7. A method according to any one of the preceding claims wherein the matrix is ​​selected 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 from diatomites, microsilicas, nanosilicas, or - carbon in the form of graphite, nano fiber or fullerene, and metal oxides.

8. A process according to any one of the preceding claims wherein the active ingredient is selected from paraffins, saturated fatty acids, saturated fatty alcohols, fatty acid esters, polyethylene glycols, alone or in mixtures.

9. A 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 a micrometric powder.

10. A process according to any one of the preceding claims comprising 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 being in the form of beads, granules or blocks.

11. A process 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.

12. A process according to any one of the preceding claims comprising a further step of humidifying the composite material obtained at the end of the assembly step or the reaggregation step, or the grinding step comprising adding a quantity of water to said composite material, the composite material obtained at the end of the humidification step being in the form of an aqueous mixture.

13. A method according to the preceding claim wherein the humidification step is carried out by adding a quantity of water between 0.5 and 50 times the weight of the composite material to be humidified.

14. A process according to any one of the two preceding claims comprising 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 being in the form of plates.

15. A process according to any one of the preceding claims comprising a further step of mechanically agitating the dispersion of the composite material obtained at the end of the assembly step or the grinding step comprising adding an aqueous suspension to said composite material with mechanical agitation, the composite material obtained at the end of the mechanically agitated dispersion step being in the form of an aqueous suspension.

16. A method according to any one of the preceding claims comprising a subsequent ultrasonic dispersion step of the composite material obtained at the end of the assembly step or the grinding step including the addition of an aqueous suspension to said composite material with agitation by ultrasonication, the composite material obtained at the end of the ultrasonication dispersion step is in gel form.

17. A method according to the preceding claim in which an amount of composite material powder from 1 to 10% is added to water or an aqueous solution.

18. A process 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 humidification step or the dispersion step into a process for manufacturing plaster, cement, mortar, concrete or even paper, plastics, wood compounds.

Images