THERMOPLASTIC TYPE COMPOSITE MATERIAL WITH A THERMOREPARABLE AND THERMODEFORMABLE CROSSBODY

Abstract

THERMOPLASTIC CROSS-CUT COMPOSITE MATERIAL, THERMOREPARANT AND THERMODEFORMABLE. The present invention relates to a composite material comprising hybrid particles (1) incorporated in a thermoplastic polymer matrix, said hybrid particles (1) being formed of inorganic particles functionalized by at least one molecule (2) bearing at least one ionic function involved in at least one ion pair and / or at least one electrostatic function involved in at least one electronegative group capable of being involved in at least one hydrogen bond, said at least one molecule (2) being an organosilane, and at least one counterion and / or at least one hydrogen bond donor / acceptor (3) bearing at least one C=C double bond, the quantity of ion pairs and / or electronegative groups capable of being involved in at least one hydrogen bond on the surface of the inorganic particles being between 0,5 and 20 mol% relative to the quantity of precursors of inorganic particles. (Figure to be published with the abbreviation: Figure 1),

Description

Title of the invention: THERMOPLASTIC CROSS-CUT COMPOSITE MATERIAL, THERMOREPARING AND THERMODEFORMABLE technical field

[0001] The present invention relates to the field of dynamic crosslinking of thermoplastic materials, particularly polyolefins, using functionalized fillers. The invention also relates to a method for manufacturing this type of material. Previous technique

[0002] Currently, the covalent crosslinking of thermoplastic polyolefins is mainly carried out on polyethylenes, then called PER: Crosslinked Polyethylenes or PEX (“crosslinked polyethylene” in English). It is obtained by three known methods: using peroxide (PER-a), silane (PER-b) or ionizing radiation (PER-c).

[0003] To this first family of polyolefins, we should add the family of resins marketed under the name Surlyn®. These are copolymers of ethylene and methacrylic acid known for their ability to be ionically crosslinked. They are ionomers, whose ionic repeating units are carboxylate groups partially neutralized by metal salts, generally zinc (Zn2+). This copolymer is widely used in cosmetic packaging due to its transparency, but also in food packaging because it offers good sealing and is not harmful to health. The advantage of ionic crosslinking lies in the reversibility of the ionic bonds when heated. As a result, the ionomers can be reshaped and are therefore theoretically recyclable, unlike covalently crosslinked polymers.

[0004] Finally, another type of polymer emerged in the 2010s, involving cross-linking of macromolecular chains by reversible organic covalent bonds. These bonds are dynamic because they are involved in chemical exchange or breaking / reforming reactions, triggered by an external stimulus such as a temperature increase or light or radical irradiation. Polymers based on this type of bond are called vitrimers. They have mechanical properties similar to thermosets while retaining the intrinsic processability of thermoplastics and thus their ability to be reshaped multiple times and recycled.

[0005] It should be noted that the various existing materials mentioned above can be divided into two categories according to their type of crosslinking: crosslinking with irreversible covalent bonds for PER and dynamic crosslinking for Surlyn, vitrimers, and the nanocomposite ionomer. The first type of crosslinking is universal in that it can be applied to any type of polyolefin, but the crosslinking is irreversible, which prevents the recycling of these materials. The second type has the advantage of reversible crosslinking, but it is specific to a given copolymer, which may or may not be a polyolefin. The pendant groups of the copolymer can form reversible bonds only with certain crosslinking agents, which prevents their applicability to all types of polyolefins.

[0006] US patent document 11,370,896 B2 discloses an ionomer, namely a polyurethane matrix nanocomposite. The nanocomposite consists of silica nanoparticles functionalized with a sulfonate-type anionic group, which dynamically binds / crosslinks to a PU / PLA copolymer bearing pendant imidazolium cationic groups. This material is used in film form and has demonstrated thermo-stimulated shape memory and repair capabilities, as well as an increase in its elongation at break and Young's modulus.

[0007] Given the rapidly growing market for thermoplastics, particularly polyolefins, there is therefore a need to improve both their mechanical and recyclability properties. Description of the invention

[0008] The invention aims to provide a composite made up of functionalized inorganic and / or hybrid particles, incorporated into a thermoplastic type polymer matrix.

[0009] To this end, the invention relates to a composite material comprising hybrid particles incorporated in a thermoplastic polymer matrix, said hybrid particles being formed of inorganic particles functionalized by at least one molecule bearing at least one ionic function involved in at least one ion pair and / or at least one electrostatic function involved in at least one electronegative group capable of being involved in at least one hydrogen bond, said at least one molecule being an organosilane, and at least one counterion and / or at least one hydrogen bond donor / acceptor bearing at least one C=C double bond, the quantity of ion pairs and / or electronegative groups capable of being involved in at least one hydrogen bond on the surface of the inorganic particles being between 0.5 and 20% mol relative to the quantity of precursors of the inorganic particles.

[0010] Thus, the resulting hybrid composite material, based on a thermoplastic polymer matrix, exhibits greater ductility for thermoplastic matrices and equivalent ductility for elastomers. Furthermore, it displays shape memory and repair properties above its melting temperature Tf with little or no loss of dimensional stability. By "little," we mean a loss of less than 25%. Typically, with thermoplastic materials, a 100% loss is observed above the material's melting temperature. Surface defects such as scratches or more drastic damage can be repaired by locally increasing the temperature.

[0011] By "hybrid particle" is meant a particle consisting of an inorganic core and a surface comprising organic molecules.

[0012] In addition, the invention presented herein has the following advantages: - Obtaining a composite material with increased dimensional stability at high temperatures, and thus higher mechanical properties at high temperatures. At low temperatures, mechanical properties, such as the Young's modulus of the thermoplastic polymer or elastomer, are only slightly impacted; for example, this impact is less than or equal to 20%, which is an advantage compared to the insertion of other types of crosslinking agents that more significantly degrade mechanical properties. By "low temperature," we mean a temperature above ambient temperature, up to the melting point of semi-crystalline thermoplastics or the glass transition temperature of amorphous thermoplastics. - An increase in the durability of the composite material thanks to its self-repairing properties. - Maintaining the recyclability of the composite material despite the dynamic crosslinking of the composite material without significant loss, thus allowing its subsequent reuse and therefore improving the circularity of thermoplastics. - Compliance with current and future legislation, particularly European legislation on the recyclability of plastic materials and their reuse, for example in the automotive industry.

[0013] These hybrid particles are used as reversible / dynamic crosslinking points, giving thermostimulated repair and shape memory properties to thermoplastic polymer matrix composite materials. Thus, the composite material is a dynamically crosslinked material.

[0014] By definition, ion pairs contain a stoichiometric quantity of anions and cations. Said anions are preferably sulfonates, carboxylates (such as maleates, fumarates, itaconates, and fatty acids), acetates, bromates, and chlorates. Said cations are preferably ammoniums, pyridiniums, imidazoliums, hydroniums, and guanadiniums.

[0015] The molecule, bearing at least one ionic function involved in at least one ion pair and / or at least one electrostatic function involved in at least one electronegative group capable of being involved in at least one hydrogen bond, is an organosilane. By way of example, the organosilane is very preferably a molecule of the formula Si(OR)3X, with R being preferably chosen from among the methoxy, ethoxy, propoxy, butoxy groups, and X being a group bearing an anion, preferably of the sulfonate, carboxylate type, such as maleates, fumarates, itaconates and fatty acids, acetates, bromates, and chlorates, or a cation, preferably of the ammonium, pyridinium, imidazolium, hydronium, and guanadinium types.

[0016] Alternatively, the organosilane may be a molecule of formula Si(OR)2X2, with R preferably being selected from the methoxy, ethoxy, propoxy, butoxy groups, and X being a group bearing an anion, preferably of the sulfonate, carboxylate type, such as maleates, fumarates, itaconates and fatty acids, acetates, bromates, and chlorates, or a cation, preferably of the ammonium, pyridinium, imidazolium, hydronium, and guanadinium type.

[0017] According to another alternative, organosilane is a molecule of formula Si(OR)X3, with R being preferably chosen from the methoxy, ethoxy, propoxy, butoxy groups, and X being a group bearing an anion, preferably of the sulfonate, carboxylate type, such as maleates, fumarates, itaconates and fatty acids, acetates, bromates, and chlorates, or a cation, preferably of the ammonium, pyridinium, imidazolium, hydronium, and guanadinium type.

[0018] According to one embodiment, said molecule carries only a single ionic function involved in at least one pair of ions.

[0019] According to another embodiment, said molecule carries only a single electrostatic function involved in at least one electronegative group capable of being involved in at least one hydrogen bond.

[0020] According to another embodiment, said molecule carries an ionic function and an electrostatic function involved in at least one electronegative group capable of being involved in at least one hydrogen bond.

[0021] According to another embodiment, said molecule carries at least two ionic functions.

[0022] According to another embodiment, said molecule carries at least two electrostatic functions involved in at least two electronegative groups capable of being involved in at least two hydrogen bonds.

[0023] According to another embodiment, said molecule carries at least two ionic functions and one electrostatic function involved in at least one electronegative group capable of being involved in at least one hydrogen bond.

[0024] According to another embodiment, said molecule carries an ionic function and at least two electrostatic functions involved in at least two electronegative groups capable of being involved in at least two hydrogen bonds.

[0025] According to another embodiment, said molecule carries at least two ionic functions and at least two electrostatic functions involved in at least two electronegative groups capable of being involved in at least two hydrogen bonds.

[0026] By way of examples of organosilane, the most preferred are dimethyloctadecyl(3-trimethoxysilyl)propyl ammonium chloride, trimethyl(3-trimethoxysilyl)propyl ammonium chloride, n,n-didecyl-n-methyl-n-(3-trimethoxysilyl)propyl ammonium chloride, 4-(trimethoxysilylethyl)benzyltrimethyl chloride, 3-aminopropyltriethoxysilane, 4-aminobutyltriethoxysilane, 2-(2-pyridylethyl)trimethoxysilane, 2-(4-pyridylethyl)triethoxysilane, 3-(trihydroxysilyl)-1-propanesulfonic acid, 3-(guanidinyl)propyltrimethoxysilane, the disodium salt of carboxyethylsilanetriol, 3-(trihydroxysilyl)-l-propanesulfonic acid and 3-(trihydroxysilyl)propyl methylphosphonate sodium salt.

[0027] The counterion and / or hydrogen bond donor / acceptor carries at least one C=C double bond advantageously involved in the polymer crosslinking reaction by radical grafting carried out using a peroxide-type compound. In this way, the polymer and the particles are connected by one or more ionic and / or electrostatic bonds. The C=C double bond may originate from an alkene, such as (meth)acrylate, styrenic, and vinyl groups.

[0028] The counterion and / or hydrogen bond donor / acceptor may be selected from the group consisting of a compound bearing a sulfonate group, such as potassium 3-sulfopropyl methacrylate or sodium 4-vinylbenzenesulfonate, a compound bearing an ammonium group, such as catecholammonium corynein, (3-carboxypropyl)trimethylammonium chloride, or N,N,N-trimethyl-3-[(2-methyl-l-oxo-2-propen-l-yl)oxy]-l-propanaminium, a compound bearing a carboxylate group, such as maleic acid, methacrylic acid, or acrylic acid, a compound bearing an amine group, such as ethyl 2-(dimethylamino)methacrylate, 3-buten-l-amine, N-vinylformamide, or 4-vinylaniline, and a group bearing a pyridine group, such as 2-vinylpyridine.

[0029] For the sake of clarity in the specific context of the invention, it should be specified that a hydrogen bond is an electrostatic interaction between two polar groups which occurs when a hydrogen atom (H) covalently bonded to a strongly electronegative atom such as nitrogen (N) or oxygen (O) is subjected to the electrostatic field of another strongly electronegative atom located nearby.

[0030] The number of ion pairs and / or electronegative groups that can be involved in at least one hydrogen bond on the surface of the inorganic particles is adjusted to obtain optimal properties according to the chemical nature of the ionic functions. The quantity of ion pairs on the surface is between 0.5 and 20 mol% relative to the quantity of inorganic particle precursors, and preferably between 1 and 10 mol%.

[0031] The particles used before functionalization, called inorganic particles, preferably have a sphericity coefficient greater than or equal to 0.75, preferably greater than or equal to 0.9. The inorganic particles are very preferentially spherical.

[0032] In the context of this invention, it is understood that the sphericity coefficient of a particle represents the ratio of the particle's smallest diameter to its largest diameter. For a perfect sphere, this ratio is equal to 1.

[0033] Said inorganic particles are preferably individualized.

[0034] By "individualized" we mean a set of particles in which the particles are not aggregated, that is to say that each particle in the set is not linked to other particles by strong chemical bonds, such as covalent bonds.

[0035] Preferably, the inorganic particles are individualized and / or spherical.

[0036] The inorganic particles are preferably made up of a three-dimensional silica (SiO2) network, the diameter of which is between 0.1 and 100 µm.

[0037] The inorganic particles preferably have a diameter between 0.3 and 40 µm, and even more preferably between 1 and 10 µm.

[0038] The precursors of the inorganic particles are metallo-organic precursors, preferably silica precursors. The precursors of the inorganic silica particles are, for example, silicon chlorides, such as silicon tetrachloride, or silicon alkoxides such as tetraethoxysilane, tetramethoxysilane, or tetra-n-propoxysilane.

[0039] The thermoplastic polymer matrix incorporating the hybrid particles of the composite material is a polyolefin.

[0040] Preferably, said polyolefin is selected from the group consisting of polyethylene, polypropylene, rubber, ethylene / vinyl acetate copolymers (EVA), and POE-type thermoplastic elastomers such as poly(ethylene- octene) PEC8 or poly(ethene-butene) PEC4, EPDM elastomers, styrenic block thermoplastic elastomers such as SBS (polystyrene-β-polybutadiene-β-polystyrene), SIS (polystyrene-β-polyisoprene-β-polystyrene) or SEBS (polystyrene-β-poly(ethylene-butylene)-β-polystyrene), NBR (nitrile-butadiene rubber) elastomers, SBR (styrene-butadiene rubber) elastomers or SIR (styrene-isoprene rubber) elastomers, or mixtures thereof

[0041] According to a preferred embodiment, the inorganic particles forming the hybrid particles of the composite material are between 0.5 and 10% by mass of said composite material, preferably between 3 and 8%, and more preferably about 5%.

[0042] By "approximately x%", this corresponds here to a value of x% plus or minus 0.5%.

[0043] The precursors of the inorganic particles are metallo-organic precursors, preferably silica precursors. The precursors of the inorganic silica particles are, for example, silicon chlorides, such as silicon tetrachloride, or silicon alkoxides such as tetraethoxysilane, tetramethoxysilane, or tetra-n-propoxysilane.

[0044] Said inorganic particles are synthesized by inorganic polymerization of precursors, in particular silica, following hydrolysis and condensation reactions, carried out by aerosol.

[0045] Surprisingly, this aerosol process allows the synthesis and functionalization of hybrid particles in a concomitant manner.

[0046] The invention also relates to a method for manufacturing a composite material comprising hybrid particles incorporated into a thermoplastic polymer matrix of the invention, comprising the following steps: a. synthesis of hybrid particles, said hybrid particles being formed from inorganic particles functionalized by at least one molecule bearing at least one ionic function involved in at least one ion pair and / or at least one electrostatic function involved in at least one electronegative group capable of being involved in at least one hydrogen bond, said at least one molecule being an organosilane, and at least one counterion and / or at least one hydrogen bond donor / acceptor bearing at least one C=C double bond, the quantity of ion pairs and / or electronegative groups capable of being involved in at least one hydrogen bond on the surface of the inorganic particles being between 0.5 and 20 mol% relative to the quantity of precursors of the inorganic particles, said particles having a diameter between 0.1 and 100 µm; and b. reactive extrusion of an assembly comprising said hybrid particles, a peroxide-type compound and a thermoplastic polymer matrix, in in which the proportion of hybrid particles is between 0.5 and 10% by mass of the composite material, at a temperature between 50°C and 250°C, for obtaining said thermoplastic polymer matrix composite material.

[0047] According to a preferred embodiment, the proportion of hybrid particles is between 3 and 8% by mass of the composite material, and more preferably about 5%.

[0048] By "about x %", this here means a value of x % plus or minus 0.5%.

[0049] Generally speaking, the principle of the method of the invention consists in coming The goal is to reversibly crosslink a thermoplastic polymer matrix, preferably polyolefin, by melting with functionalized micrometric hybrid particles. These particles have at least two molecules on their surface. The first carries a negatively charged functional group. The second carries a positively charged functional group, forming a more or less strong ionic and / or electrostatic bond. This molecule also carries a C=C double bond, enabling the radical grafting of the particles to the thermoplastic polymer. Alternatively, the first molecule may carry a negative functional group and the second a positive one, the latter also exhibiting a C=C double bond. The ionic and / or electrostatic bond at the organic polymer / inorganic particle interface provides the reversible / dynamic character, giving these composite compounds new properties, as described above.

[0050] The mixing and / or dispersion of the assembly comprising the hybrid functionalized particles, the thermoplastic polymer matrix, preferably polyolefin, and a peroxide-type compound, as well as the grafting of said particles onto said polymer matrix, are carried out by reactive extrusion using, for example, a mixing device such as an internal mixer, a single-screw extruder, a twin-screw extruder, or a satellite extruder, and preferably a twin-screw extruder. The hybrid particles and the peroxide-type compound can be added to the feed zone (the hopper) or to a zone of the extruder where the polymer is already in a molten state. The hybrid particles are dispersed homogeneously within the thermoplastic polymer matrix. The ionic and / or electrostatic crosslinking of the hybrid particles occurs partly during the extrusion phase.The grafting of hybrid particles can be carried out in infrastructures similar to those already in operation for the grafting of silanes in PER-b. The present invention has the advantage of enabling the dynamic crosslinking of thermoplastics during the reactive extrusion step, which does not require the implementation of an additional device.

[0051] Step a) of synthesis can advantageously be carried out by the following aerosol process, comprising the following steps: 1. Nebulization, in a reactor, of a first hydroalcoholic or aqueous solution containing one or more precursors of inorganic particles, preferably silica, with a mass concentration between 0.1 and 20%, and of a second alcoholic or hydroalcoholic solution comprising at least one molecule bearing at least one ionic function involved in at least one ion pair and / or at least one electrostatic function involved in at least one electronegative group capable of being involved in at least one hydrogen bond, said at least one molecule being an organosilane, and at least one counterion and / or at least one hydrogen bond donor / acceptor bearing at least one C=C double bond, the quantity of ion pairs and / or electronegative groups capable of being involved in at least one hydrogen bond being calculated with respect to the molar quantity of said precursors of inorganic particles varying between 0.5 and 20%mol,to obtain a mist of droplets from the first and second solutions; 2. Heating said fog to a temperature between 50°C and 100°C for a predetermined duration for the formation of inorganic particles and the evaporation of the solvent; 3. Heating of said particles obtained during step 2) to a condensation temperature for the transformation of said precursors into the inorganic part of said hybrid particles; 4. Recovery of said hybrid particles.

[0052] The predetermined duration of step 2) is preferably less than or equal to 10 s, and even more preferably less than or equal to 5 s.

[0053] By "condensing temperature" is meant a temperature between 50 and 250 °C, preferably between 100 and 200 °C, and even more preferably about 150 °C.

[0054] The process of the invention is a continuous process requiring a limited number of preparation steps. It allows for the simple production of non-aggregated, functionalized hybrid particles in a single step, without waste generation, as the by-products can be recycled and / or reused. This process makes it easy to vary the surface state of the hybrid particles by changing the chemical nature and quantity of the molecules present. Thus, unlike molecular crosslinking agents, the hybrid particles of the present invention can be adapted to vary the bond exchange dynamics while providing also several other properties due to the nature of the compounds used (anti-UV, magnetism, coloring, etc.).

[0055] Inorganic particles are synthesized and functionalized in a single step and by aerosol to form hybrid particles according to the invention. This synthesis process involves a first step of atomizing solutions into droplets which are heated to be transformed into individual solid particles.

[0056] According to one embodiment, the first solution is an aqueous or hydroalcoholic solution, with a pH between 2 and 4. Preferably, the first solution is an aqueous solution.

[0057] The second solution is advantageously an aqueous, pure alcoholic or hydroalcoholic solution, this second solution being methanol, ethanol or propanol when it contains an alcohol, without being limited to these examples of alcohol.

[0058] According to one embodiment, in the case of use of silica, the silica precursors are silicon chlorides, such as silicon tetrachloride, or silicon alkoxides, such as tetraethoxysilane, tetramethoxysilane, or tetra-n-propoxysilane.

[0059] According to one embodiment, the precursors of inorganic (non-functionalized) particles are those mentioned above.

[0060] The quantity of ion pairs and / or electronegative groups that can be involved in at least one hydrogen bond of step a) is preferably between 0.5 and 10%mol, and even more preferably between 0.8% and 3%mol relative to the quantity of inorganic particle precursors.

[0061] The other compounds or groups, such as ion pairs, the counter-ion, molecules, organosilanes, etc.; involved in the process are as defined above.

[0062] According to an alternative embodiment to step 1), the first and second solutions form a single solution of inorganic precursors and ion pairs and / or electronegative groups capable of being involved in at least one hydrogen bond. This single solution contains, in this case, just enough alcohol to allow the dissolution of the ion pairs and / or electronegative groups capable of being involved in at least one hydrogen bond.

[0063] According to one embodiment, in the case of the two separate solutions (first and second solutions), they are nebulized simultaneously and meet at the outlet of a nebulization nozzle of an atomizing device. In this case, the solution containing the inorganic precursor is nebulized into the center of the solution containing the molecule bearing at least the ion pair and / or at least the electronegative group capable of being involved in at least one hydrogen bond.

[0064] The process can advantageously be implemented by means of a commercially available aerosol atomization device, such as a Büchi-B290 reactor or atomizer. Such an atomizer comprises the following main elements: a solution(s) aspiration device via a peristaltic pump, a compressed gas inlet, a heating module, an atomization nozzle, a drying cylinder and a recovery container.

[0065] The atomizing nozzle may be of various conventional arrangements, of the double, triple or more nozzle type, for the synthesis of hybrid particles formed from inorganic particles having a coefficient of sphericity greater than or equal to 0.75 and / or an average diameter between 0.1 and 100 sqm.

[0066] According to one embodiment, the process may advantageously include a stirring step for a duration of 10 min to 48 h, before the nebulization of step 1) in order to hydrolyze the precursors of inorganic particles with three-dimensional network.

[0067] Preferably, the stirring step time is between 10 and 24h for a solution at pH 2, or between 30 min and 2h for a solution at pH 3.

[0068] The process may include, before the nebulization step 1) and after the stirring step, a conventional step of aspirating the solution(s) defined above towards an atomization nozzle of an atomizer by means of a compressed gas heated by a heating module.

[0069] Said aspiration step is typically carried out by a peristaltic pump, a syringe pump or any other element fulfilling this function.

[0070] According to an embodiment A, the inorganic particles are functionalized, by aerosol co-condensation of organosilane groups and silica precursors, with an organosilane group bearing a quaternary ammonium function. The quaternary ammonium can be linked to a carbon chain, this carbon chain being from 1 to 18 carbons, preferably from 10 to 18 carbons. The counterion in this case is a sulfonate, a carboxylate, an acetate, a bromate, or a chlorate carried by a molecule that also has a C=C double bond, such as potassium 3-sulfopropyl methacrylate or sodium 4-vinylbenzenesulfonate in the case of a sulfonate. This double bond can originate from an alkene such as styrene, (meth)acrylate, or vinyl groups. Alternatively, the organosilane group can bear a sulfonate function and the counter-ion can be a quaternary ammonium linked by a C=C double bond.Preferably, the organosilane group is dimethyloctadecyl (3-trimethoxysilyl)propyl ammonium chloride bearing a quaternary ammonium and a long carbon chain, and the counterion is potassium 3-sulfopropyl methacrylate, bearing a sulfonate anion and a methacrylate function: .

[0071] [Chem.l]

[0072] Similarly, the ion pair can be made between N,N,N-trimethyl-3-[(2-methyl-l-oxo-2-propen-l-yl)oxy]-l-propanaminium and 3-(trihydroxysilyl)-l-propanesulfonic acid:

[0073] [Chem.2]

[0074] According to another embodiment B, the inorganic particles can be functionalized by an organosilane group bearing a primary amine function in its acidic form (NH3+) and whose counter-ion bears a carboxylate function and a C=C double bond, for example, maleic acid in its maleate form. Similarly, the ionic groups can be reversed. It is possible to have an organosilane group bearing a carboxylate function and its counter-ion being an amine also bearing a C=C double bond. Preferably, the organosilane group is 3-aminopropyltriethoxysilane and the counter-ion is maleic acid:

[0075] [Chem.3] och3 h H3CO-Si^^ och3 h' H ü h 0 n ' N L “O H 9CH3 ^^^ShOCH3 och3

[0076] According to an embodiment C, the surface of the inorganic particles may include one or more hydrogen bonds. In these cases, the organosilane group, covalently bonded to the particle, bears a pyridine functional group. The nitrogen of the pyridine functional group is then involved in a hydrogen bond with the hydrogen of a carboxyl group. The carboxyl group is borne by a molecule that also has a C=C double bond. The organosilane group may bear the carboxyl group, and the molecule bearing the C=C double bond may also contain a pyridine. Preferably, the organosilane group is 2-(2-pyridylethyl)trimethoxysilane, and the molecule bearing both the carboxylic acid and the C=C double bond is maleic acid.

[0077] [Chem.4]

[0078] Alternatively, before step b), the process of the invention may include a step of mixing said assembly, then a step of introducing said mixture into an extrusion device for reactive extrusion.

[0079] The peroxide-type compound can conventionally be dicumyl peroxide.

[0080] Alternatively, the peroxide could be chosen from dilauroyl peroxide, di(3,5,5-trimethylhexanoyl) peroxide, di(2-ethylhexyl)peroxydicarbonate, di-tert-amyl peroxide, tert-butyl peroxy-3,5,5-trimethylhexanoate, 3-hydroperoxy-1,1-dimethylbutyl peroxyneodecanoate, 00-tert-butyl-0-2-isopropy monoperoxycarbonate, bis[1-(tert-butylperoxy)-1-methylethyl]benzene, 1,1-Bis(tert-butylperoxy)cyclohexane, tert-butylperoxy 2-ethylhexyl carbonate or tert-butyl peroxybenzoate. According to one embodiment of step b), reactive extrusion can be carried out using an internal mixer, with the two blades rotating at 30–100 rpm, preferably 40–60 rpm. The mixture can be introduced in two stages, spaced 1–10 minutes apart. The blade speed is increased to 60–100 rpm.After approximately 15-25 minutes, the composite material is extracted.

[0081] According to one embodiment, the process of the invention may include a step c) of shaping by compression, after step b), by a device of A conventional press is used to advantageously complete the crosslinking process and / or increase the crosslinking yield under the action of pressure and heat. The pressure can typically be 150-200 bar and the temperature can range from 100°C to 200°C, depending on the nature of the composite material.

[0082] The various definitions and data for the composite material and the preferred embodiments defined for the composite material apply to the process of the invention.

[0083] The other compounds or groups, such as ion pairs, the counter-ion, molecules, organosilanes etc., involved in the process are defined above.

[0084] According to one embodiment, the proportion of peroxide-type compound is less than 1% by mass of the composite material, preferably between 0.4 and 0.5%.

[0085] The present invention also relates to a motor vehicle comprising at least one element, said element being obtained from a composite material according to the invention.

[0086] The present invention therefore aims to combine the advantages of the two previous types of crosslinking in a single material. Indeed, it allows for the universal and reversible crosslinking of thermoplastics, particularly all polyolefin families, thereby promoting their recyclability and improving their mechanical properties, thermal resistance, and service temperature. Furthermore, the present invention aims to improve the high-temperature mechanical properties of thermoplastics, extend their lifespan, increase the repairability index of the automotive parts concerned, and thus reduce the amount of waste produced by the automotive industry.

[0087] In addition, the invention makes it easier to comply with European directives requiring the recovery of 95% of the components of end-of-life motor vehicles (Directive 2000 / 53 / EC).

[0088] Surprisingly, the composite material according to the present invention has a dimensional stability greater than or equal to 75%, after the melting temperature Tf of polyolefin polymer matrices.

[0089] In a totally unexpected manner, the composite material according to the present invention has a value of the storage modulus at the rubbery tray, after the melting temperature of polyolefin polymer matrices, different from 0.

[0090] These two criteria demonstrate the self-repairing nature of the composite material of the invention.

[0091] The invention has been illustrated and described in detail in the drawings and the preceding description. This description is to be considered illustrative and given by way of example and not as limiting the invention to this single description. Numerous embodiments are possible. Brief description of the drawings

[0092] [Fig.1] is a schematic representation of the composite material according to an embodiment of the invention;

[0093] [Fig.2] represents an example of an atomization device (atomizer) for the production of hybrid particles incorporated in a thermoplastic polymer matrix.

[0094] [Fig.3] shows the different dimensional stabilities of an example of hybrid material of the invention. Detailed description Example 1

[0095] Fig. 1 represents an example of a composite material according to the invention.

[0096] The composite material comprises micrometric spherical hybrid particles Functionalized silica (SiO2) particles (illustrated on the left side of [Fig. 1]) have two molecules on their surface. The first, 2, carries a negatively charged functional group. The second, 3, carries a positively charged functional group, forming a more or less strong ionic and / or electrostatic bond. This molecule also carries a C=C double bond, which allows for radical grafting (illustrated by the dashed arrow) of the particles to a polyolefin polymer matrix with dicumyl peroxide (DCP). Alternatively, the first molecule can carry a negative functional group and the second a positive one, the latter also possessing a C=C double bond. This results in a dynamically crosslinked hybrid composite material (referring to the right side of [Fig. 1]). Example 2:

[0097] An example of an atomization device 4 is given in [Fig.2], intended for the production of hybrid particles.

[0098] It comprises the following main elements: a solution(s) aspiration device via a peristaltic pump 6, a compressed gas inlet 8 (inlet temperature), a gas outlet 9, a heating module 10, an atomizing nozzle 12, a drying cylinder 14, a recovery container 16, a cyclone device 18, and a temperature probe 20 (outlet temperature).

[0099] A process for manufacturing hybrid particles includes steps of drawing the precursor and ion-pair solution(s) by the peristaltic pump 6 to the atomizing nozzle 12 via a compressed gas heated by the heating module 10 (areas E and F of [Fig. 2]). A step of atomizing the precursor and ion-pair solution(s) into droplets is shown in area G, followed by a step of drying the droplets in the drying cylinder 14, as shown in area H. After this drying step, a step of recovering the functionalized particles 1 (zone I), the flow out of zone H being directed towards the cyclone device 18, the gases being evacuated by the gas evacuation 9 upstream of said cyclone device 18, and the functionalized particles 1 are collected.

[0100] Steps 1), 2), and 3) of the process correspond to zones G and H of the device (nebulization-drying). Step 4) corresponds to zone I (particle recovery). Example 3:

[0101] In the case of embodiment A, the process for manufacturing hybrid particles is implemented as follows.

[0102] The synthesis of the hybrid particles is carried out by aerosol injection. For this purpose, the ion pair is prepared by mixing anion and cation in stoichiometric quantities in methanol. A second aqueous solution, acidified to pH 2, is prepared containing tetraethoxysilane (TEOS) to achieve a silica concentration of 1 wt%. This solution is stirred for 8 hours to hydrolyze the TEOS. The ion pair is then added to this TEOS solution. Between 0.5 mol% and 20 mol% of the ion pair is added relative to the amount of TEOS. This mixture is nebulized in a Büchi-B290 atomizing reactor. This reactor is heated to 150°C at the inlet, which corresponds to an outlet temperature of approximately 90°C. The nebulized solution flow rate is 1.5 mL / min, and the airflow for nebulization is 740 L / h. Finally, the airflow for particle collection is set at 27 m³ / h.

[0103] In the case of embodiment B, the process for manufacturing hybrid particles is implemented as follows.

[0104] The hybrid particles are synthesized by aerosol but according to two different protocols: either by nebulizing a solution at pH=3 containing the TEOS and the ion pair, or by nebulizing two solutions, one containing the TEOS and the other the ion pair. In both cases, the ion pair is prepared by mixing anion and cation in stoichiometric quantities in methanol.

[0105] Then, in the first case, an acidified aqueous solution at pH 3 is prepared, containing tetraethoxysilane (TEOS) to achieve a silica concentration of 1% by mass. This solution is stirred for 45 min - 1 h to hydrolyze the TEOS. The ion pair is then added to this TEOS solution. Between 0.5 mol% and 10 mol% of ion pairs are added relative to the amount of TEOS. This mixture is nebulized in a Büchi-B290 atomizing reactor. This reactor is heated to 150°C at the inlet, which corresponds to an outlet temperature of approximately 90°C for an ion pair concentration below 5 mol%; otherwise, the reactor is heated to 50°C, resulting in an outlet temperature of approximately 35°C. The flow rate of the nebulized solution is 1.5 mL / min, the airflow enabling nebulization corresponds to a flow rate of 740 L / h. Finally, the airflow for recovering particles is set at 27 m3 / h.

[0106] In the second case, an aqueous solution A, acidified to pH 2, is prepared containing tetraethoxysilane (TEOS) to achieve a silica concentration of 1% by mass. This solution is stirred for 8 hours to hydrolyze the TEOS. The ion pair is added to a solution B composed of 75% by volume of absolute ethanol and 25% by volume of distilled water. The amount of ion pair is calculated to correspond to a molar concentration between 1% and 6% relative to the amount of TEOS in solution A. Both solutions are nebulized in a Büchi-B290 atomizing reactor using a nozzle consisting of three nested concentric channels. Solution A is nebulized into the central channel at a flow rate of 1.5 mL / min. Solution B is nebulized into the channel surrounding the central channel at a flow rate of 0.75 mL / min. Finally, the external channel allows air circulation at a flow rate of 740 L / h. The reactor is heated to 150°C.The airflow for collecting the particles is set at 27 m3 / h.

[0107] In the case of embodiment C, the process for manufacturing hybrid particles is implemented as follows.

[0108] The hybrid particles are synthesized by aerosol, by nebulizing two solutions, one containing TEOS and the other the molecules interacting by hydrogen bonding. The parameters of this process are equivalent to the second case described previously for embodiment B. Example 4, Examples 4.1-4.11

[0109] Thermal repairs for examples of hybrid composite materials

[0110] Prerequisite for heat repair:

[0111] E'Tf + 30°C > 0 MPa E' corresponds to the value of the preservation modulus of the rubber plate after a temperature of 30°C above the melting temperature Tf, measured by DMTA (Dynamic Mechanical Thermal Analysis). This value reflects the crosslinking density of a hybrid composite material. It is a key criterion for determining the nature of the phenomenon. If the material is not crosslinked, then it will repair itself due to its thermoplastic nature and not due to the dynamics of the bonds. It thus allows us to understand the impact of the crosslinking density on the repair efficiency.

[0112] SD >75% SD corresponds to the dimensional stability of an example of a hybrid composite material. This criterion makes it possible to estimate the material's ability to be repaired while retaining its original shape, which is important for pressureless surface repair. It is a qualitative and visual criterion that reflects the difference in shape of a sample before and after heat treatment at 30 °C above the melting temperature for 1 hour 30 minutes in an oven. When If the material retains its shape, then SD is 100%. If it begins to contract, SD varies between 75% and 50%. Finally, if the sample has sunk, degraded (it browns), or contracted completely, then SD is 0%.

[0113] Fig. 3 presents the examples used as a reference.

[0114] Table 1 presents the criteria and results of thermal repair of examples of hybrid materials (Examples 4.1-4.11), in which

[0115] Chemical nature of the organic molecules forming the ion pair (PI)

[0116] a: organosilane

[0117] [3: Counter ion and / or hydrogen bond donor / acceptor, bearing a double C=C bond

[0118] al: NC 18+ = dimethyloctadecyl[3-(trimethoxysilyl)propyl] ammonium chloride

[0119] a2: NC+ = trimethyl(3-trimethoxylilyl)-propyl ammonium chloride

[0120] a3: APTES = 3-Aminopropyltriethoxysilane

[0121] a4: If Pyridyne = 2-(2-Pyridylethyl)trimethoxysilane,

[0122] SO3- = potassium 3-sulfopropyl methacrylate

[0123] styrS03- = sodium 4-vinylbenzenesulfonate

[0124] Maleic acid Chemical nature of the polymer

[0125] HDPE: high-density polyethylene

[0126] LDPE: low-density polyethylene

[0127] PEC8: POE elastomer of poly(ethylene octene)

[0128] EVA: ethylene / vinyl acetate copolymer Experimental results

[0129] qElh 30: Repair efficiency of Young's modulus after lh30 heat treatment

[0130] q erupture ih 30: repair efficiency from elongation to break after lh30 of heat treatment

[0131] SD and E' are defined in example 4.

[0132] The repair efficiencies of Young's modulus qE and elongation at break PLupture after a heat treatment of lh30 were determined using tensile tests. In order to validate a repair efficiency, it was estimated that one of the parameters of Young's modulus qE or elongation at break qerapture had to be greater than or equal to 80%. To eliminate the influence of forming conditions, the mechanical properties of the damaged specimens are compared to the mechanical properties of specimens from the undamaged portion of the same plate, which will therefore have undergone the same thermal and mechanical stresses. The repair efficiency for a given property is calculated using the following equation: h (%) = Prepared x 100 ^reference with Krepaired: a specific property of the repaired material Reference ■ the same property for an undamaged sample of the same material

[0133] Surprisingly, the composite material according to the present invention has a dimensional stability greater than or equal to 75%, after the melting temperature of polyolefin polymer matrix.

[0134] In a totally unexpected manner, the composite material according to the present invention has a value of the storage modulus at the rubbery tray, after the melting temperature of the polyolefins, different from 0. Example 5:

[0135] 5 g of hybrid particles and 450 mg of dicumyl peroxide are added in 100 g of polyolefin is introduced into an internal mixer heated to 160°C, with two blades rotating at 50 rpm. The mixture is introduced in two stages, 5 minutes apart. The blade speed is increased to 100 rpm after 10 minutes, and after 18 minutes the molten polymer is extracted. It is then pressed at 200 bar for 1 hour and 30 minutes.

[0136] These polyolefins, once hybridized, exhibit reversible crosslinking in the sense that thermostimulated self-healing properties are observed. After complete rupture and repair under pressure, the hybrid composite materials repair themselves after 1h30 with a repair efficiency greater than or equal to 80%.

[0137] The thermal conditions under pressure for this self-repair are:

[0138] - at 80°C for PEC8 and EVA matrix hybrids;

[0139] - at 120°C for LDPE matrix hybrids;

[0140] - at 150°C for HDPE matrix hybrids.

[0141] Advantageously, the composite material according to the present invention is used to manufacture one or more elements of said motor vehicle, in particular interior or exterior plastic parts, for example, the dashboard, the doors, decorative trim, etc.

[0142] [Tables 1] Reaction parameters Repair Reaction results Chemical nature PI and particles Particle size Chemical nature polymer Repair temperature E' at Tf + 30°C SD pEif-iSo U Rupture 1 f(30 a PN (%molSi) Mean diameter (pm) CC) in kPa in % in % in % Free 4.1 al P1 4.9 2.8 HDPE 150°C 64123 100% 119% 100% Free 4.2 al 6.6 2.2 HDPE 150*0 229133 100% 101% 100% Free 4.3 a2 P1 3.5 3 HDPE 150°C 40124 100% 94% 396% Free 4.4 a3 03 3 2.5 HDPE 150*C 150136 75% 97% 117% Free 4.5 a3 |33 4.5 1.7 HDPE 150X 198148 75% 84% 106% Free 4.6 a3 ^3 6.1 4.3 HDPE 150*0 133136 75% 185% 18% Free 4.7 a3 P3 3.2 1.6 HDPE 150aC 158136 100% 85% 89% Free 4.8 a4 P3 4.4 3.5 HDPE 150*C 107140 75% 111% 280% Free 4.9 al 6.6 2.2 LDPE 120*0 5719 100% 73% 100% Exempt 4.10 al 6.6 2.2 PEC8 808C 310110 100% 100% 94% Exempt 4.11 al 6 6 2.2 EVA 65°C 504136 100% 118% 66%

Claims

Demands

1. Composite material comprising hybrid particles (1) incorporated in a thermoplastic polymer matrix, said hybrid particles (1) being formed of inorganic particles functionalized by at least one molecule (2) bearing at least one ionic function involved in at least one ion pair and / or at least one electrostatic function involved in at least one electronegative group capable of being involved in at least one hydrogen bond, said at least one molecule (2) being an organosilane, and at least one counterion and / or at least one hydrogen bond donor / acceptor (3) bearing at least one C=C double bond, the amount of ion pairs and / or electronegative groups capable of being involved in at least one hydrogen bond on the surface of the inorganic particles being between 0.5 and 20 mol% relative to the amount of precursors of the inorganic particles.

2. A composite material according to claim 1, wherein the thermoplastic polymer matrix is ​​a polyolefin, preferably selected from the group consisting of polyethylene, polypropylene, rubber, ethylene / vinyl acetate (EVA) copolymers, POE-type thermoplastic elastomers such as poly(ethylene-octene) PEC8 or poly(ethene-butene) PEC4, EPDM elastomers, styrenic block thermoplastic elastomers such as SBS (polystyrene-β-polybutadiene-β-polystyrene), SIS (polystyrene-β-polyisoprene-β-polystyrene) or SEBS (polystyrene-β-poly(ethylene-butylene)-β-polystyrene), NBR (nitrile-butadiene rubber) elastomers, SBR (styrene-butadiene rubber) elastomers, or SIR elastomers (styrene-isoprene rubber), or a mixture thereof.

3. Hybrid particles (1) according to claim 1, wherein the inorganic particles have a coefficient of sphericity greater than or equal to 0.75, preferably greater than or equal to 0.9, or are spherical.

4. A composite material according to any one of claims 1 to 3, wherein the inorganic particles consist of a three-dimensional silica (SiO2) network, the average diameter of which is between 0.1 and 100 pm, preferably between 0.3 and 40 pm, even more preferably between 1 and 10 pm.

5. Composite material according to any one of the preceding claims, wherein the inorganic particles are between 0.5 and 10% by mass of the composite material, preferably between 3 and 8%, and more preferably about 5%.

6. Composite material according to any one of claims 2 to 5, wherein the composite material has dimensional stability greater than or equal to 75%, after the melting temperature of polyolefin polymer matrices.

7. Composite material according to any one of claims 2 to 6, wherein the composite material has a rubber-plated conservation modulus value, after the melting temperature of polyolefin polymer matrices, different from 0.

8. A method for manufacturing a composite material comprising hybrid particles (1), as defined according to any one of claims 1 to 7, incorporated into a thermoplastic polymer matrix, comprising the following steps of: a. synthesis of hybrid particles (1), said hybrid particles (1) being formed of inorganic particles functionalized by at least one molecule (2) bearing at least one ionic function involved in at least one ion pair and / or at least one electrostatic function involved in at least one electronegative group capable of being involved in at least one hydrogen bond, said at least one molecule (2) being an organosilane, and at least one counterion and / or at least one hydrogen bond donor / acceptor (3) bearing at least one C=C double bond, the quantity of ion pairs and / or electronegative groups capable of being involved in at least one hydrogen bond on the surface of the inorganic particles being between 0.5 and 20 mol% relative to the quantity of precursors of the inorganic particles, said particles having a diameter between 0.1 and 100 µm; and b. reactive extrusion of an assembly comprising said hybrid particles (1), a peroxide-type compound and a thermoplastic polymer matrix, wherein the proportion of hybrid particles (1) is between 0.5 and 10% by mass of the composite material, at a temperature between 50°C and 250°C, for obtaining said thermoplastic polymer matrix composite material.

9. A method according to claim 8, wherein the proportion of peroxide-type compound is less than 1% by mass of the composite material, preferably between 0.4 and 0.5%.

10. Motor vehicle comprising at least one composite material according to any one of claims 1 to 7, or as obtained according to the process of any one of claims 8 to 9.

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