ZEOLITH / ELASTOMER COMPOSITE MATERIAL

Abstract

ZEOLITH / ELASTOMER COMPOSITE MATERIAL The present invention relates to a composite material comprising a) at least one elastomer, and b) an amount equal to or greater than 30% by weight, relative to the total weight of said composite material, of type 3A zeolite, the cationic sites of which are occupied by the potassium cation, the sodium cation, at least one cation of an alkaline earth metal from group IIA of the periodic table, and the hydronium cation. The invention also relates to the use of said composite material as an adsorbent material, for the manufacture of masterbatches, for packaging, and for the manufacture of double glazing. Fig.: none

Description

Title of the invention: ZEOLITH / ELASTOMER COMPOSITE MATERIAL

[0001] The present invention relates to the field of composite materials and in particular to elastomeric materials in which zeolite crystals are incorporated, in particular 3A zeolite crystals, said materials being useful in various applications where adsorption of water is sought, and particularly in drying applications.

[0002] The present invention thus relates to composite materials obtained by incorporating zeolite crystals, in particular zeolite 3A, into an elastomeric matrix, more specifically a thermoplastic elastomeric matrix.

[0003] Zeolite crystals are usually incorporated using high-power mixers, such as Brabender-type mixers, laminar flow mixers, twin-screw mixers, extruders, calenders, and others. However, the high viscosity that develops during the mixing of zeolite crystals with the polymer matrix often makes incorporation difficult. This results, among other things, in the need to restrict the incorporation rate of zeolite crystals, whereas maximum incorporation of zeolite crystals into the polymer matrix is ​​desired in order to best ensure the desired adsorption functions, such as a desiccant function.

[0004] Furthermore, for reasons of efficiency of the elastomer / zeolite composite material in certain applications, it may sometimes be necessary to restrict adsorption to specific molecules, such as water in drying applications, avoiding as much as possible any co-adsorption of very small molecules, for example nitrogen, oxygen, or argon. Indeed, these molecules could alter the mechanical properties, visual perception, or tactile perception of the composite material, due to their possible uncontrolled desorption during the manufacture or use of said composite material.

[0005] Several works already propose solutions for incorporating zeolite crystals into polymer matrices, and among these, for example, are those described in document EP2690136 Al, where a thermoplastic elastomer composition comprises a zeolite, a thermoplastic polymer, and an elastomer partially vulcanized with a phenolic resin. The zeolite introduced into the phenolic resin before vulcanization eliminates the yellow coloration that traditionally results from the activation of the phenolic resin crosslinking by tin chloride. The zeolite content in the final composition can reach 47%, but much lower contents are preferred.

[0006] Application WO2011150237 A1 describes an article molded from two fluid silicone precursors into which a sorbent material has been previously introduced. The mixture is sufficiently fluid to be injection molded. The viscosity is then increased by cross-linking the mixture, causing the article to solidify. The final mixture consists of cross-linked silicone (45% to 95%) and a sorbent material (5% to 55%), which may be, in particular, calcium oxide or a zeolite. This gives the article moisture protection properties, for example, against the explosive charge of an airbag. There is no particular selection of the nature of the sorbent material; only 13X zeolite is mentioned in the examples. However, this type of zeolite has significant porosity, which can be detrimental to certain applications, particularly due to the potential desorption of gaseous molecules.

[0007] Document EPI323468 discloses an adsorbent material comprising 45% to 80% by weight of a porous functional solid, for example a zeolite, incorporated into a polymer matrix, which comprises a thermoplastic polymer having a second porosity in addition to the first porosity of the porous functional solid. This document does not deal with elastomeric polymer composite materials.

[0008] A process for preparing a zeolite A usable in two-component polyurethane resin formulations is also known from document FR2819247, said zeolite A having sodium, potassium, calcium or magnesium and hydronium exchange rates of 10% to 69%, 28% to 55%, 2% to 45% and 1% to 20%, respectively. The zeolite is introduced in small proportions into 2K PU mixtures.

[0009] Previous work has highlighted the need to have composite materials incorporating a significant zeolite content, but also the inherent difficulty in manufacturing such composite materials, particularly due to the often excessively high viscosity during the mixing of components.

[0010] Consequently, there remains a need to reduce the difficulty of incorporating high proportions of zeolite into a polymer matrix, and in particular an elastomer, specifically a need to decrease the viscosity during the preparation of the polymer matrix / zeolite mixture. It would therefore be advantageous to have composite materials comprising adsorbent materials that are easier to manufacture, and thus to have adsorbent composite materials that are easy to prepare, and in particular, efficient and readily available desiccant composite materials.

[0011] It has now been discovered that the present invention makes it possible to achieve, in whole or at least in part, the aforementioned objectives through the incorporation of a zeolite by particular in an elastomeric polymer matrix. Other objectives will appear in the following description of the present invention.

[0012] Thus, and according to a first object, the present invention relates to a composite material comprising: a) at least one elastomer, and b) an amount equal to or greater than 30% by weight, relative to the total weight of said composite material, of type 3A zeolite, the cationic sites of which are occupied by the potassium cation, the sodium cation, at least one cation of an alkaline earth metal from column IIA of the periodic table and the hydronium cation.

[0013] The zeolite used in the composite material of the present invention is, as previously stated, a type 3A zeolite. The 3A zeolite has a Si / Al atomic ratio between 0.90 and 1.10, preferably between 0.95 and 1.05.

[0014] This zeolite 3A has so-called "cationic" sites, these sites being occupied by cations intended to ensure the electrical neutrality of said zeolite 3A. The cationic sites are occupied by the potassium cation, generally and preferably from 35% to 70%, the sodium cation, generally and preferably from 2% to 62%, at least one alkaline earth cation, chosen from magnesium, calcium, strontium, and barium, generally and preferably from 2% to 30%, and the hydronium cation, generally and preferably from 1% to 5%, inclusive, the percentages being expressed in moles of cation, relative to the total number of moles of exchangeable sites, as indicated below. It should be understood that the sum of the percentages of each of the cations listed above reaches 100%, to ensure the electrical neutrality of the zeolite as just stated.

[0015] It has been discovered in a completely surprising way that the crystals of this specific 3A zeolite can be easily incorporated in high proportions, for example greater than or equal to 30% by weight, relative to the total weight of the composite material, into an elastomeric matrix, and in particular into a thermoplastic elastomeric matrix.

[0016] Thus, the present invention proposes a composite material comprising zeolite 3A crystals. This zeolite 3A is advantageously and most often an adsorbent zeolite, that is to say, it has been activated, as indicated later in the description. The incorporation of this zeolite 3A is improved to facilitate its incorporation in a high proportion into a polymer matrix and / or, at iso-productivity (this parameter depending essentially on the viscosity of the mixture in the molten state), to increase the proportion of zeolite incorporated into an elastomeric matrix, preferably into a thermoplastic elastomeric matrix, and more particularly into natural rubber (NR), synthetic rubber, halogenated polymers and copolymers, polysulfone rubbers, polysiloxanes, as well as mixtures of two or more of them, in any proportion.

[0017] The 3A zeolite defined above, intended for use in the composite material of the invention, facilitates mixing with the elastomeric matrix, in particular by allowing for a reduction in viscosity or the incorporation of a greater quantity of zeolite into said elastomeric matrix. This directly results in a reduction in the preparation time of the composite material, and therefore improved productivity, but also the possibility of increasing the proportion of zeolite in the composite material and consequently further improving the adsorption properties at iso-mass mixing.

[0018] It has also been observed that, due to the zeolite 3A included in the composite material of the invention, the latter exhibits a zero or negligible capacity for adsorption of argon, nitrogen, oxygen, and rare gases.

[0019] Indeed, zeolite 3A, as defined above, imparts drying properties to the composite material of the invention through its water molecule adsorption properties, without co-adsorbing, or only in very small quantities, small molecules potentially present in the atmosphere that could come into contact with the composite material, for example, nitrogen, but also oxygen or argon. Without being bound by theory, this absence or near absence of co-adsorption is primarily due to a relatively high potassium (K+) cation exchange rate, typically greater than or equal to 35%, as indicated later in the description.

[0020] Thus, and in a preferred embodiment, the composite material of the present invention comprises a 3A zeolite whose cationic sites are occupied: - by the potassium cation, in an amount between 35% and 70%, preferably between 38% and 68%, preferably still between 40% and 65%, and advantageously between 45% and 60% inclusive, - by an alkaline earth cation, in an amount between 2% and 30%, preferably between 3% and 25%, preferably still between 5% and 20%, inclusive, - by the sodium cation, in an amount between 2% and 62% inclusive, and - by the hydronium cation, in an amount between 1% and 5% inclusive.

[0021] As previously stated, the alkaline earth cation is selected from the magnesium cation, the calcium cation, the strontium cation, and the barium cation. According to a particularly preferred aspect of the present invention, the alkaline earth cation is selected from the calcium cation (Ca2+) and the magnesium cation (Mg2+), as well as mixtures thereof in any proportion.

[0022] In one embodiment of the invention, when the alkaline earth cation chosen is calcium, a calcium exchange rate is preferred, i.e. the cationic sites are occupied by the calcium cation in a range between 5% and 30%, preferably between 5% and 20%, preferably still between 5% and 15%, limits included.

[0023] According to another embodiment, when the alkaline earth cation chosen is magnesium, a magnesium exchange rate of between 2% and 15% is preferred, preferably between 4% and 10%.

[0024] It must be understood that all the exchangeable sites of zeolite 3A are occupied by the cations indicated above, the sum of the percentages being equal to 100%, as indicated above.

[0025] According to a preferred embodiment of the present invention, the composite material comprises 3A zeolite crystals whose average number diameter, calculated from counting on SEM images as indicated below, is between 0.1 pm and 4.0 pm, preferably between 0.2 pm and 3.5 pm, preferably still between 0.3 pm and 3.0 pm, inclusive.

[0026] Crystals with an average diameter in number lower or greater than the limits indicated above may, however, be used within the scope of the present invention. It has been observed, however, that an average diameter in number within the limits indicated above promotes incorporation into the elastomeric matrix, both in terms of incorporation time and the quantity of zeolite incorporated.

[0027] As previously stated, the zeolite content in the elastomer matrix of the composite material of the present invention is greater than or equal to 30% by weight relative to the total weight of the composite material. A composite material according to the present invention is preferred in which the zeolite content is between 30% and 90%, preferably between 40% and 85%, even better between 45% and 80%, and even more preferably between 50% and 80%, inclusive, relative to the total weight of said composite material.

[0028] The composite material of the present invention, in addition to the elastomeric matrix and the 3A zeolite, may also comprise a quantity, generally a minor one and advantageously less than or equal to 20%, preferably less than or equal to 10%, and better still less than or equal to 5%, by weight, relative to the total weight of zeolite(s), of one or more other zeolites selected from other LTA-type zeolites, such as 4A and 5A zeolites, from Faujasites (FAU of type LSX, MSX, X, Y) with a Si / Al molar ratio between 1 and 100, from EMT-type zeolites, from MFI-type zeolites with a Si / Al ratio between 5 and 500, from GIS-type zeolites (for example, P zeolite), from zeolites of type SOD (such as sodalite), among MOR type zeolites, among HEU type zeolites and among BEA type zeolites.

[0029] The zeolite present in the composite material of the present invention is well known to those skilled in the art and easily prepared from a type 3A, 4A or 5A zeolite, by carrying out the desired cation exchanges, as indicated above previously, or from known operating methods, such as that available for example in document FR2819247, adapted to the exchange rates respectively referred to previously.

[0030] A non-limiting example of the preparation of zeolite 3A useful in the context of the present invention includes the following steps: 1 / Bringing the following aqueous solutions or suspensions into contact: I have an aqueous suspension of zeolite 3A (a-1), 4A (a-2) or 5A (a-3), bj an aqueous solution of alkaline earth metal salt(s) (b-1), or potassium salt(s) (b-3) or solutions of alkaline earth metal salt(s) and potassium (b-2), It is an acid solution, according to one of the following methods: either simultaneously ai, bj and c, either ai and bj then c, let ai and c then bj, let bj and c then ai, Given that i and j are identical, and that when i equals 1, then j can also equal 2, and when i equals 3, then j can also equal 2, 2 / then filtration and washing of the resulting solid, 3 / then drying and activation, preferably under non-degrading gas sweep, of the solid from 2 / .

[0031] When the solutions and the suspension are brought into contact simultaneously [(ai) and (bj) and (c)], the mixing is generally carried out for a period of less than 1 hour at a temperature generally between 15°C and 80°C.

[0032] In the case where the zeolite suspension (ai) and the acid solution (c) are first mixed, the mixing is generally carried out for a few minutes, preferably under stirring, before the introduction of the aqueous saline solution (bj), the reaction mixture then being stirred for a period generally less than 1 hour at a temperature generally between 15°C and 80°C.

[0033] In the case where the salt(s) solution (bj) and the acid solution (c) are first mixed, the mixing is generally carried out for a few minutes, preferably under stirring, before the introduction of the zeolite suspension (ai), the reaction mixture then being stirred for a period generally less than 1 hour at a temperature generally between 15°C and 80°C.

[0034] Following the synthesis steps described above, solid crystals are obtained, suspended in an aqueous solution. The crystals are filtered and then washed with water. If the zeolite suspension (ai) and the salt solution(s) (bj) are initially mixed, the mixing is generally carried out for a period generally less than 1 hour, preferably with stirring, and at a temperature generally between 15°C and 80°C, and suspended crystals are obtained, said crystals being washed with water before being introduced into the acidic solution (c). Finally, the product is filtered and then washed with a mixture of the acidic solution and the wash water.

[0035] The concentrations and compositions of the salt and acid solutions are adjusted without particular difficulty so that the final zeolite conforms to the formula indicated above.

[0036] The proportions of the different cations present in the structure of the zeolites are measured conventionally by X-ray fluorescence, as indicated below, the accuracy of the measurements being on the order of 1%. The exchanged zeolite is then activated, according to techniques well known to those skilled in the art, and for example by subjecting the zeolite to be activated to a heat treatment generally comprising first a drying step, generally between 60°C and 110°C for a duration most often ranging from about half an hour to about 2 hours, followed by an activation step at a temperature generally between 300°C and 600°C, preferably between 350°C and 500°C.Preferably, the activation step is carried out under gas purging with a non-degrading gas (such as air, nitrogen, and others), which allows for the rapid removal of water present in the zeolite and prevents its hydrothermal degradation while limiting the negative effects due to an excessively high activation temperature.

[0037] The zeolite used in the context of the present invention is a dehydrated zeolite, that is to say, one desorbed of its water by heat treatment or having a very low residual water content. Typically, and according to a preferred embodiment of the present invention, the zeolite used for the preparation of the composite material according to the invention has a loss on ignition (LOI) of less than 3%, preferably less than 2%.

[0038] Exchange rates are determined from X-ray fluorescence analyses, and the size of zeolite crystals is determined by counting on scanning electron microscopy images according to the characterization techniques described later in this description.

[0039] Furthermore, the composite material of the present invention may also comprise one or more additives well known to those skilled in the art, for example, and without limitation, one or more additives selected from crosslinking agents, such as organic peroxides, colorants, pigments, antibacterial agents, anti-fog agents, blowing agents, dispersants, lubricants, flame retardants, fillers, in particular those that are inert with respect to adsorption, and other agents. bonding and compatibilizing agents of the functional polyolefin type.

[0040] Thus, the composite material of the present invention comprises an elastomeric matrix in which a 3A zeolite is incorporated. According to one embodiment, the elastomeric matrix can be a thermoplastic elastomeric matrix, and more specifically can be generally chosen from natural rubbers, synthetic rubbers, halogenated polymers and copolymers, polysulfonated rubbers, polysiloxanes, as well as mixtures of two or more of them, in any proportion.

[0041] The elastomeric matrix comprises one or more elastomers selected from polysiloxanes (known as "silicones"), natural rubber (NR), polybutadienes (BR), polynitriles (NBR), hydrogenated or partially hydrogenated polynitriles (HNBR), styrene-isoprene-butadiene rubber (SIBR), polyisobutylenes and polyisobutenes (PIB), isobutylene-isoprene elastomeric copolymers (IIR, known as "butyl rubbers"), halogenated or non-halogenated, polychloroprenes (CR), EPDM rubbers ("Ethylene Propylene Diene Monomer"), chlorinated polyethylenes (CM), polysulfonated rubbers (CSM), polyisoprenes (IR), as well as mixtures of two or more of them, in any proportion.

[0042] The elastomeric matrix of the composite material of the present invention may optionally comprise other polymers than those listed above, and for example and without limitation, one or more polymers selected from polyethylenes, polypropylenes, ethylene propylene rubbers (EPM), ethylene-butylene, hexylene or octylene copolymers, acrylic polymers (such as alkyl poly(meth)acrylates), poly(vinyl chloride), ethylene-vinyl acetate copolymers, poly(vinyl acetate), polyamides, polyesters, chlorinated polyethylenes, polyurethanes, polystyrenes, silicone polymers, styrene-ethylene-butylene-styrene (SEBS) block copolymers, epoxy resins, as well as mixtures of two or more of them, in any proportions.

[0043] Preferably the elastomeric matrix of the composite material of the present invention is chosen from polysiloxanes and synthetic rubbers, preferably again from polysiloxanes, alone or in mixtures with one or more of the polymers listed above.

[0044] The elastomeric matrix of the composite material of the present invention, whether it comprises one or more of the elastomers listed above, can be subjected a posteriori, i.e. after incorporation of the zeolite, to a physicochemical treatment, such as crosslinking or vulcanization (“curing” in English), or any other treatment desired for the intended use.

[0045] The preparation of the composite material according to the present invention can be carried out by simply mixing the zeolite and the elastomer matrix, according to techniques well known to those skilled in the art for incorporating mineral fillers into polymer materials. Thus the mixing can be carried out for example, and without limitation, in an extruder, in a laminar mixer or a calender, in a twin-screw mixer, in a Brabender type mixer, with rotating blades of various shapes adapted to each type of matrix, or in Banbury type devices, in which two spiral rotors rotate in opposite directions at a variable rotational speed.

[0046] As previously mentioned, it is possible at this stage to add one or more additives. The incorporation temperature is adjusted according to the type of elastomer polymer, and can generally be between 20°C and 400°C.

[0047] The composite material of the invention can be shaped into the desired form for end use, for example by molding, extrusion, extrusion-molding, rolling, and others.

[0048] Thanks to the intrinsic properties of the 3A zeolite described above, its incorporation into the elastomeric matrix is ​​greatly facilitated. A substantial reduction in the viscosity of the mixture has been observed, and / or a greater quantity of zeolite can be incorporated into the elastomeric matrix, due to the improved rheological behavior resulting from the lower viscosity. This means that the zeolite incorporation process requires substantially less energy and / or is faster. This allows for a reduction in the preparation time of the composite material according to the invention, making its industrialization much more cost-effective (improved productivity) and / or by enabling an increase in the proportion of zeolite in said composite material, thereby increasing the adsorption properties of said composite material at iso-mass.

[0049] The composite material of the present invention finds very interesting uses as an adsorbent composite material, and in particular as a desiccant composite material, usable in particular for the manufacture of masterbatches, for packaging, for the manufacture of double glazing, usable in the pharmaceutical, paramedical, agri-food, electronic, automotive, construction fields, to name only the main possible uses.

[0050] The following examples are intended to illustrate the object of the invention, and are provided for guidance purposes only, without however being intended in any way to limit the various embodiments of the present invention.

[0051] In the following examples, the physical properties of the agglomerates are evaluated by methods known to those skilled in the art, the main ones of which are recalled below. Characterization techniques

[0052] The physical properties of zeolites are evaluated by known methods of The expert in the art, whose main characteristics are listed below. Grain size of zeolite crystals

[0053] The number-average diameter of zeolite crystals is estimated by scanning electron microscopy (SEM). To estimate the size of the zeolite crystals in the samples, a series of images are taken at a magnification of at least 5000x. The diameter of at least 200 crystals is then measured using dedicated software, for example, Smile View from LoGraMi. The accuracy is on the order of 3%.

[0054] Chemical analysis of zeolites. Determination of the Si / Al molar ratio and exchange rate

[0055] An elemental chemical analysis of the zeolite powder according to the invention can be carried out using various analytical techniques known to those skilled in the art. Among these techniques, one can mention the chemical analysis technique by X-ray fluorescence as described in standard NF EN ISO 12677:2011 on a wavelength dispersive X-ray fluorescence (WDXRF) spectrometer, for example the Tiger S8 from Bruker.

[0056] X-ray fluorescence is a non-destructive spectral technique that exploits the photoluminescence of atoms in the X-ray range to determine the elemental composition of a sample. Excitation of atoms, generally by an X-ray beam or by bombardment with electrons, generates specific radiation after the atom returns to its ground state. Conventionally, after calibration, a measurement uncertainty of less than 0.4% by weight is obtained for each oxide.

[0057] Other methods of analysis are illustrated for example by the methods by atomic absorption spectrometry (AAS) and atomic emission spectrometry with high-frequency induced plasma (ICP-AES) described in the standards NF EN ISO 21587-3 or NF EN ISO 21079-3 on an apparatus of the type for example Perkin Elmer 4300DV.

[0058] X-ray fluorescence spectroscopy has the advantage of being largely independent of the element's chemical composition, thus providing a precise determination, both quantitative and qualitative. Following calibration, a measurement uncertainty of less than 0.4% by weight is obtained for each oxide, SiO2 and Al2O3, as well as for the various oxides (such as those derived from exchangeable cations, for example, potassium). Therefore, the elemental chemical analyses described above allow verification of both the Si / Al molar ratio of the zeolite used and the exchange rate of monovalent and divalent cations.

[0059] In the description of the present invention, the measurement uncertainty of the Si / Al molar ratio is ± 5%. The measurement of the Si / Al molar ratio of the zeolite present in the composite material can also be measured by Ma- Resonance Spectroscopy Solid-state nuclear genetics (NMR) of silicon.

[0060] The exchange rate by a given cation is calculated by evaluating the ratio between the number of moles of said cation (expressed in moles equivalent, i.e. in number of moles of electrical charges, i.e. 2 times the number of moles of the cation when the cation is divalent) and the number of moles of exchangeable sites which is equal to the number of moles of aluminium present in the framework of the zeolite.

[0061] The respective quantities of each of the cations are evaluated by chemical analysis of the corresponding cations, the quantity of each cation being evaluated by chemical analysis of the corresponding oxides (Na2O, CaO, K2O, MgO, etc.). The quantity of hydronium ion is calculated by subtracting the number of moles of aluminum present in the zeolite's structure from the sum of the number of moles of the other cations present in the zeolite (expressed in moles equivalent). X-ray diffraction

[0062] The identification of zeolites present in the composite of the invention is evaluated by X-ray diffraction analysis, known to those skilled in the art by the acronym XRD, after solvent treatment to dissolve the elastomer matrix, the choice of solvent being made according to the nature of the elastomer. The solid sample collected after dissolution and removal of the solvent is analyzed on a Bruker XRD instrument.

[0063] This analysis makes it possible to identify the different zeolites present in the sample because each of the zeolites has a unique diffractogram defined by the positioning of the diffraction peaks and by their relative intensities.

[0064] The collected sample is ground, then spread and smoothed onto a sample holder by simple mechanical compression. The acquisition conditions for the diffractogram produced on the Bruker D8 ADVANCE instrument are as follows:

[0065] • Cu tube used at 40 kV - 30 mA;

[0066] • size of the Soller slits = 2.5, with a width of the irradiation surface of 16 mm;

[0067] * rotating sample device: 10 rpm 1;

[0068] • measuring range: 4° < 20 < 70°;

[0069] • pitch: 0.015°;

[0070] • counting time per step: 0.8 seconds.

[0071] The interpretation of the diffractogram obtained is carried out with the EVA software with identification of the zeolites using the ICDD PDF-2 database, release 2011. The quantity by weight of the zeolitic fractions is measured by XRD, it is evaluated using the TOPAS software from the Bruker company. Small molecule adsorption test

[0072] The small molecule adsorption test, for example oxygen, aims to verify that The 3A zeolite useful in the context of the present invention has only a very low or zero adsorption capacity of said small molecules.

[0073] The test is performed using a commercial gas adsorption apparatus (Micromeritics Tristar 2) according to a volumetric method. Approximately 10 g of sample are placed in a glass cell and degassed under vacuum at room temperature for at least 15 hours. After degassing, the cell is placed under helium and weighed to determine the mass of the anhydrous sample. The sample is then brought into contact with a known volume of oxygen at 600 mmHg. It is maintained in the presence of oxygen for 24 h at 25°C. The final oxygen pressure in the cell is then recorded, which allows the amount of oxygen adsorbed by the sample to be calculated by difference. Adsorption can be considered weak if it is less than 25 Ncm3g4, preferably less than 20 Ncm3g', preferably even less than 15 Ncm3g', and advantageously less than 12 Ncm3gA Examples:

[0074] Various zeolite / elastomer mixtures are prepared according to the following procedure: a peroxide-type crosslinking agent (Luperox P from Arkema, 3.8 g or 1.9 phr (“parts per hundred of rubber”)) is first added, with stirring, to 200 g (100 phr) of a zeolite. This premix (PM) is then introduced into 200 g (100 phr) of a silicone polymer matrix (Silicone R401_70S from Wacker Chemie AG) using a Lescuyer brand twin-cylinder mixer.

[0075] The mixer is operated for approximately 60 minutes at a temperature of 20°C. After 25 to 30 minutes of operation, the unincorporated premix mass (i.e., the mass rejected at the base of the twin cylinders), referred to as the "refuse mass," is weighed and then reintroduced into the mixture between 30 and 60 minutes. The results are considered acceptable when the refuse mass is less than 20 grams. The rotation speeds of the cylinders (150 mm in diameter) are different: 18 revolutions per minute for the rear cylinder and 24 revolutions per minute for the front cylinder. The gap between the two cylinders is approximately 3 mm. A homogeneous mixture is obtained in the form of a sheet approximately 60 cm long, 15 cm wide, and 3 mm thick.

[0076] Rheological behavior measurements are also performed on the sheets obtained using a plane-plane oscillating matrix rheometer (MDR C type from France Scientifique) at 130°C for 60 minutes, the duration during which the silicone matrix crosslinks. The rheometer is operated according to ISO 6502 and ASTM D5289 standards.

[0077] The composite material sheets prepared with zeolite 3A crystals partially exchanged with calcium as a divalent cation exhibit a lower minimum torque than that obtained with zeolite 3A crystals without a divalent cation, This demonstrates that less energy is required to mix the 3A zeolite crystals containing divalent cations according to the invention with the polymer matrix. Indeed, greater fluidity (lower viscosity) of the mixture is obtained with the 3A zeolite crystals according to the invention, and all the more so when the divalent cation exchange rate is high, as observed with calcium.

[0078] The characteristics of the tested composite material sheets are grouped in the following Table 1 (where TE is the Cation Exchange Rate): - Table 1 - Zeolite TE Na (%) TE K (%) TE Ca (%) TE Mg (%) TE Hydronium (%) Crystal Size 1 2.5 10 7.2 6 3 33 47 19 0 1 2.5 8 6.5 10 4 (comp.) 46 30 23 0 1 2.5 6 5.7 93 5 45 46 0 7 2 2.5 17 6.6 8

Claims

Demands

1. Composite material comprising: a) at least one elastomer, and b) an amount equal to or greater than 30% by weight, relative to the total weight of said composite material, of type 3A zeolite, the cationic sites of which are occupied by the potassium cation, the sodium cation, at least one cation of an alkaline earth metal of column IIA of the periodic table and the hydronium cation, and in which the cationic sites are occupied from 35% to 70% by the potassium cation, from 2% to 62% by the sodium cation, from 2% to 30% by at least one alkaline earth cation, selected from magnesium, calcium, strontium and barium and from 1% to 5% by the hydronium cation, inclusive, the percentages being expressed in moles of cation, relative to the total number of moles of exchangeable sites.

2. Composite material according to claim 1, wherein the alkaline earth cation is selected from the magnesium cation and the calcium cation, as well as mixtures thereof in any proportion.

3. Composite material according to any one of the preceding claims, wherein when the chosen alkaline earth cation is calcium, the cationic sites are occupied by the calcium cation in a range of 5% to 30%, preferably between 5% and 20%, preferably still between 5% and 15%, inclusive.

4. Composite material according to any one of the preceding claims, wherein the 3A zeolite crystals have a number-average diameter, calculated from counting on SEM images, of between 0.1 pm and 4.0 pm, preferably between 0.2 pm and 3.5 pm, preferably still between 0.3 pm and 3.0 pm, inclusive.

5. Composite material according to any one of the preceding claims, wherein the zeolite content is between 30% and 90%, preferably between 40% and 85%, more preferably between 45% and 80%, and even more preferably between 50% and 80%, inclusive, relative to the total weight of said composite material.

6. Composite material according to any one of the preceding claims, further comprising an amount less than or equal to 20%, preferably less than or equal to 10%, and better still less than or equal to 5%, by weight, relative to the total weight of zeolite(s), of one or more other zeolites selected from other LTA-type zeolites, such as zeolites 4A and zeolites 5A, among Faujasites (FAU of type LSX, MSX, X, Y) with a Si / Al molar ratio between 1 and 100, among EMT type zeolites, among MFI type zeolites with a Si / Al ratio between 5 and 500, among GIS type zeolites (e.g., P zeolite), among SOD type zeolites (such as sodalite), among MOR type zeolites, among HEU type zeolites, and among BEA type zeolites.

7. Composite material according to any one of the preceding claims, further comprising one or more additives selected from crosslinking agents, colorants, pigments, antibacterial agents, anti-fog agents, swelling agents, dispersants, lubricants, flame retardants, filler materials, bonding agents and compatibilizing agents of the functional polyolefin type.

8. Composite material according to any one of the preceding claims, wherein the elastomeric polymer selected from polysiloxanes, natural rubber, polybutadienes, polynitriles, hydrogenated or partially hydrogenated polynitriles, styrene-isoprene-butadiene rubber, polyisobutylenes and polyisobutenes, halogenated or non-halogenated isobutylene-isoprene elastomeric copolymers, polychloroprenes, EPDM rubbers, chlorinated polyethylenes, polysulfonated rubbers, polyisoprenes, and mixtures of two or more of them, in any proportions.

9. Use of a composite material according to any one of the preceding claims as an adsorbent composite material, as a desiccant composite material, for the manufacture of masterbatches, for packaging, for the manufacture of double glazing.