Zeolite / Elastomer Composites

Abstract

The present invention relates to a composite material comprising: a) at least one elastomer; and b) a type 3A zeolite in an amount of 30 wt. % or more, based on the total weight of the composite material, the type 3A zeolite having cationic sites occupied by potassium cations, sodium cations, at least one alkaline earth metal cation from group IIA of the periodic table, and hydronium ions. The invention also relates to the use of said composite material as an adsorbent material for the preparation of masterbatches, for packaging and for the manufacture of insulating glazing.

Description

[Technical field]

[0001] The present invention relates to the field of composite materials, and in particular to elastomeric materials incorporating zeolite crystals, particularly 3A zeolite crystals, which are useful in a variety of applications where water adsorption is desired, more particularly drying applications.

[0002] The present invention therefore relates to a composite material obtained by incorporating crystals of a zeolite, in particular a 3A zeolite, into an elastomeric matrix, more particularly a thermoplastic elastomeric matrix. [Background technology]

[0003] Zeolite crystals are typically incorporated using high-power mixers, such as Brabender mixers, laminar mixers, twin-screw mixers, extruders, and even calendars. However, the high viscosity that arises during mixing of the zeolite crystals with the polymer matrix often makes incorporation difficult. This, among other things, results in the need to limit the level of incorporation of the zeolite crystals, although it is desirable to achieve maximum incorporation of the zeolite crystals in the polymer matrix in order to best ensure the desired adsorption properties, such as desiccant properties.

[0004] Also, for the effectiveness of elastomer / zeolite composites in certain applications, it may be necessary to limit the adsorption of certain molecules, such as water in dry applications, while avoiding as far as possible the potential co-adsorption of very small molecules, such as nitrogen, oxygen and argon, which may alter the mechanical properties, visual or tactile perception of the composite as a result of untimely desorption that may occur during the manufacture or use of said composite.

[0005] Various works have already proposed solutions that make it possible to incorporate zeolite crystals into a polymer matrix, including, for example, that described in document EP 2 690 136 A1, in which a thermoplastic elastomer composition comprises a zeolite, a thermoplastic polymer and an elastomer partially cured with a phenolic resin. The zeolite introduced into the phenolic resin before curing makes it possible to eliminate the yellow coloration usually due to the activation of crosslinks on the phenolic resin by stannous chloride. The zeolite content in the final composition can be as high as 47%, but much lower contents are preferred.

[0006] Application WO2011150237A1 describes an article molded from two silicone fluid precursors, into which a sorbent material has previously been introduced. This mixture is sufficiently fluid to be poured. The viscosity is then increased by crosslinking the mixture so that the article solidifies. The final mixture consists of crosslinked silicone (45% to 95%) and a sorbent material (5% to 55%), which may in particular be calcium oxide or a zeolite, which gives the article protective properties against moisture, for example in the explosive filling of airbags. The nature of the sorbent is not particularly selected, only zeolite 13X is mentioned in the examples. However, this type of zeolite has a considerable porosity, which may be detrimental in certain applications, in particular due to the possibility of desorption of gas molecules.

[0007] The document EP1323468 discloses an adsorbent material comprising 45% by weight to 80% by weight of a porous functional solid, e.g. a zeolite, incorporated in a polymer matrix comprising a thermoplastic polymer having a second porosity in addition to the first porosity of the porous functional solid. This document does not deal with composite materials comprising elastomeric polymers.

[0008] Also known from document FR 2 819 247 is a method for preparing zeolites A which can be used in two-component polyurethane resin formulations, said zeolites A having degrees of exchange of sodium, potassium, calcium or magnesium and hydronium ions of 10% to 69%, 28% to 55%, 2% to 45% and 1% to 20%, respectively, the zeolites being introduced in small proportions into the 2K PU mixture.

[0009] Prior studies highlight not only the need for access to composite materials incorporating significant zeolite content, but also the difficulties inherent in producing such composite materials, particularly as a result of viscosities during mixing of the components that are often excessively high. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] European Patent Application Publication No. 2690136 [Patent Document 2] International Publication No. 2011 / 150237 [Patent Document 3] European Patent Application Publication No. 1323468 [Patent Document 4] French Patent No. 2819247 Summary of the Invention [Problem to be solved by the invention]

[0011] Thus, there remains a need to reduce the difficulty of incorporating high percentages of zeolites into polymer matrices, especially elastomers, and in particular to reduce the viscosity during preparation of the polymer matrix / zeolite mixture.It would therefore be advantageous to have access to composites containing adsorbent materials, their easier manufacture, and therefore adsorbent and easy to prepare composites, especially effective and readily available desiccant composites. [Means for solving the problem]

[0012] It has now been found that the present invention makes it possible to achieve the above-mentioned objectives in whole or at least in part by incorporating specific zeolites in an elastomeric polymer matrix. Further objectives will become more apparent in the light of the invention below.

[0013] Thus, according to a first subject, the invention relates to a composite material comprising: a) at least one elastomer, and b) a type 3A zeolite in an amount of 30% by weight or more based on the total weight of the composite material, the cationic sites being occupied by potassium cations, sodium cations, at least one alkaline earth metal cation from group IIA of the periodic table, and hydronium ions; The present invention relates to a composite material comprising: DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] As described above, the zeolite used in the composite material of the present invention is type 3A zeolite, which has a Si / Al atomic ratio of 0.90 to 1.10, preferably 0.95 to 1.05.

[0015] The 3A zeolite has sites referred to as "cation sites" which are occupied by cations intended to ensure the electrical neutrality of the 3A zeolite. The cationic sites are generally occupied by potassium cations, preferably in the range of 35% to 70% inclusive, generally by sodium cations, preferably in the range of 2% to 62% inclusive, generally by at least one alkaline earth metal cation selected from magnesium, calcium, strontium and barium, preferably in the range of 2% to 30% inclusive, and generally by hydronium ions, preferably in the range of 1% to 5% inclusive, the percentages being expressed as the number of moles of cations relative to the total number of moles of exchangeable sites, as shown below. As previously mentioned, it should be understood that the sum of the percentages of each of the above listed cations adds up to 100% to ensure the electrical neutrality of the zeolite.

[0016] It was a complete surprise to discover that this 3A zeolite crystallite in particular can be readily incorporated into an elastomeric matrix, in particular a thermoplastic elastomeric matrix, in high proportions, e.g., 30 wt. % or more, relative to the total weight of the composite.

[0017] The present invention therefore proposes a composite material comprising crystals of 3A zeolite, which is advantageously and most frequently an adsorbent zeolite, i.e. activated as further described herein. The incorporation of this 3A zeolite has been improved in order to facilitate its incorporation in high proportions into polymer matrices and / or to increase the proportion of zeolite incorporated in elastomer matrices, preferably thermoplastic elastomer matrices, more particularly natural rubber (NR), synthetic rubber, halogenated polymers and copolymers, polysulfonated rubber, polysiloxanes and mixtures of two or more thereof in any proportion, for the same productivity (this parameter essentially depends on the viscosity of the mixture when melted).

[0018] The 3A zeolites defined above and intended for use in the composite material of the invention facilitate their mixing with an elastomeric matrix, in particular as a result of allowing a reduction in the viscosity or by incorporating a higher amount of zeolite in said elastomeric matrix, which is directly reflected in a reduction in the preparation time of the composite material and therefore in an increase in productivity, but also in the possibility of increasing the proportion of zeolite in the composite material and thus further improving its adsorption properties for the same mass of mixture.

[0019] It was also observed that due to the 3A zeolite present in the composite material of the invention, the latter has little or no adsorption capacity for argon, nitrogen, oxygen or noble gases.

[0020] In particular, the 3A zeolite defined above confers desiccant properties to the composite material of the invention due to its ability to adsorb water molecules without, or with only very small amounts of, co-adsorption of small molecules that may be present in the atmosphere that may come into contact with the composite material, such as nitrogen, but also oxygen or argon. Without wishing to be bound by any particular theory, it is believed that this absence or virtual absence of co-adsorption is due mainly to the adsorption of potassium cations (K + ) resulting from a relatively high degree of exchange, typically 35% or more as further indicated herein.

[0021] Thus, in a preferred embodiment, the composite material of the present invention comprises a 3A zeolite in which the cationic sites are occupied by: potassium cations in an amount between 35% and 70% (inclusive), preferably between 38% and 68% (inclusive), more preferably between 40% and 65% (inclusive) and advantageously between 45% and 60% (inclusive); - alkaline earth metal cations in an amount between 2% and 30% (inclusive), preferably between 3% and 25% (inclusive), more preferably between 5% and 20% (inclusive), - sodium cations in an amount between 2% and 62% inclusive; - Hydronium cation in an amount between 1% and 5% (inclusive).

[0022] As indicated above, the alkaline earth metal cation is selected from magnesium, calcium, strontium and barium cations. According to a very particularly preferred embodiment of the invention, the alkaline earth metal cation is a calcium cation (Ca 2+ ) and magnesium cation (Mg 2+ ) and mixtures thereof in any proportion.

[0023] In one embodiment of the present invention where the selected alkaline earth metal cation is calcium, it is preferred that the degree of calcium exchange, i.e., cationic sites are occupied by calcium cations, in the range of 5% to 30% (inclusive), preferably 5% to 20% (inclusive), more preferably 5% to 15% (inclusive).

[0024] According to another embodiment in which the selected alkaline earth metal cation is magnesium, a degree of magnesium exchange between 2% and 15%, preferably between 4% and 10%, is preferred.

[0025] It is understood that all exchangeable sites in the 3A zeolite are occupied by the cations shown above, and as shown above, the sum of the percentages equals 100%.

[0026] According to a preferred embodiment of the present invention, the composite material comprises 3A zeolite crystals whose number average diameter, calculated by counting in SEM images as shown below, is between 0.1 μm and 4.0 μm (inclusive), preferably between 0.2 μm and 3.5 μm (inclusive), more preferably between 0.3 μm and 3.0 μm (inclusive).

[0027] However, crystals with a number average diameter below or above the above limits can be used in the context of the present invention, but it has been observed that number average diameters between the above limits are favorable for incorporation into an elastomeric matrix, both in terms of incorporation time and amount of incorporated zeolite.

[0028] As indicated above, the zeolite content in the elastomer matrix of the composite material of the invention is 30% by weight or more relative to the total weight of the composite material. Preferred are composite materials according to the invention in which the zeolite content is between 30% and 90% (inclusive), preferably between 40% and 85% (inclusive), better still between 45% and 80% (inclusive), even more preferably between 50% and 80% (inclusive) relative to the total weight of said composite material.

[0029] The composite material of the invention may also comprise, in addition to the elastomeric matrix and the 3A zeolite, one or more other zeolites chosen, generally in small amounts, advantageously less than or equal to 20% by weight, preferably less than or equal to 10% by weight and even better less than or equal to 5% by weight, relative to the total weight of the zeolite, from other zeolites of LTA type, such as 4A and 5A zeolites, from faujasites (FAU of type LSX, MSX, X or Y) with a Si / Al molar ratio between 1 and 100, from EMT type zeolites, from MFI type zeolites with a Si / Al molar ratio between 5 and 500, from GIS type zeolites (for example zeolite P), from SOD type zeolites (for example sodalite), from MOR type zeolites, from HEU type zeolites and from BEA type zeolites.

[0030] The zeolites present in the composite material of the invention are well known to those skilled in the art and can be easily prepared by starting from a type 3A, 4A or 5A zeolite and carrying out the desired cation exchange as indicated above, or alternatively from known procedures, such as those provided in document FR 2 819 247, each adapted to the degree of exchange mentioned above.

[0031] A non-limiting example of the preparation of a 3A zeolite that is useful in the context of the present invention involves the following steps. 1 / Aqueous solutions or suspensions of: ai an aqueous suspension of 3A(a-1), 4A(a-2) or 5A(a-3) zeolite; bj An aqueous solution of an alkaline earth metal salt (b-1) or a potassium salt (b-3) or an alkaline earth metal salt and a potassium salt (b-2); c) Acid solution according to one of the following methods: At the same time, AI, BJ and C, or ai and bj, then c, or ai and c, then bj, or bj and c, then ai, where i and j are the same, it is understood that when i is equal to 1, j can also be equal to 2, and when i is equal to 3, j can also be equal to 2; 2 / then a step of filtering and washing the solid obtained, 3 / Then comes the drying and activation step of the solid obtained from 2 / , preferably while flushing with a non-decomposing gas.

[0032] When the solution and suspension are contacted simultaneously [(ai) and (bj) and (c)], mixing is typically carried out at a temperature between 15° C. and 80° C. for a period of less than 1 hour.

[0033] When the suspension of zeolite (ai) and the acid solution (c) are first mixed, mixing is usually carried out for a few minutes, preferably with stirring, before being introduced into the aqueous salt solution (bj), and the reaction mixture is then stirred, usually at a temperature between 15°C and 80°C, for a period generally less than one hour.

[0034] If the salt solution (bj) and the acid solution (c) are mixed first, they are usually mixed for a few minutes, preferably with stirring, before the suspension of zeolite (ai) is introduced, and the reaction mixture is then usually stirred at a temperature between 15°C and 80°C for a period generally less than 1 hour.

[0035] At the end of the aforementioned synthesis steps, solid crystals are obtained suspended in the aqueous solution. The crystals are filtered off and then washed with water. When the zeolite suspension (ai) and the salt solution (bj) are first mixed, the mixing is usually carried out for a time of less than 1 hour, preferably with stirring, at a temperature usually between 15°C and 80°C, to obtain crystals in the form of a suspension, which are then washed with water before being introduced into the acid solution (c). Finally, the product is filtered off and then washed with a mixture of the acid solution and washing water.

[0036] The concentrations and compositions of the salt and acid solutions are adjusted without any particular difficulty so that the final zeolite corresponds to the formula given above.

[0037] The proportion of different cations present in the structure of the zeolite is measured in a conventional manner by X-ray fluorescence, as will be further shown below, with a measurement accuracy of the order of 1%. After having undergone exchange, the zeolite is then activated according to techniques well known to those skilled in the art, for example by subjecting the zeolite to be activated to a heat treatment, which generally includes a drying step, usually at 60°C to 110°C, for a period usually ranging from about half an hour to about two hours, followed by an activation step, generally at a temperature of 300°C to 600°C, preferably 350°C to 500°C. Preferably, the activation step is carried out while flushing with a non-decomposing gas (for example air, nitrogen, etc.), which allows the rapid removal of the water present in the zeolite and avoids its hydrothermal decomposition, while limiting the adverse effects of too high an activation temperature.

[0038] The zeolites used in the context of the present invention are dehydrated zeolites, i.e. those which have had their water desorbed by thermal treatment or have a very low residual water content. Typically, according to a preferred embodiment of the present invention, the zeolites used for the preparation of the composite material according to the present invention have a loss on ignition (LOI) of less than 3%, preferably less than 2%.

[0039] The degree of exchange is determined by X-ray fluorescence analysis and the size of the zeolite crystals is determined by counting in scanning electron microscope images according to the characterization techniques further described herein.

[0040] In addition, the composite material of the present invention may also comprise one or more additives well known to those skilled in the art, such as, but not limited to, one or more additives selected from crosslinking agents, e.g., organic peroxides, colorants, pigments, antibacterial agents, antifogging agents, swelling agents, dispersants, lubricants, flame retardants, fillers, especially those inert to adsorption, binders and compatibilizers of the functional polyolefin type.

[0041] The composite material of the present invention therefore comprises an elastomeric matrix in which 3A zeolite is incorporated. According to one embodiment, the elastomeric matrix can be a thermoplastic elastomeric matrix, and more particularly may be generally selected from natural rubbers, synthetic rubbers, halogenated polymers and copolymers, polysulfonated rubbers, polysiloxanes, and mixtures of two or more of these in any proportion.

[0042] The elastomeric matrix comprises one or more elastomers selected from polysiloxanes (referred to as "silicones"), natural rubber (NR), polybutadiene (BR), polynitrile (NBR), hydrogenated or partially hydrogenated polynitrile (HNBR), styrene-isoprene-butadiene rubber (SIBR), polyisobutylene and polyisobutene (PIB), isobutylene-isoprene elastomeric copolymers (IIR, referred to as "butyl rubber") (which may be halogenated or non-halogenated), polychloroprene (CR), EPDM (ethylene propylene diene monomer) rubber, chlorinated polyethylene (CM), polysulfonated rubber (CSM), polyisoprene (IR), and mixtures of two or more of these in any proportion.

[0043] The elastomeric matrix of the composites of the present invention may optionally comprise one or more polymers other than those listed above, such as, but not limited to, one or more polymers selected from polyethylene, polypropylene, ethylene-propylene rubber (EPM), ethylene-butylene, hexylene or octylene copolymers, acrylic polymers (such as polyalkyl(meth)acrylates), polyvinyl chloride, ethylene-vinyl acetate copolymers, polyvinyl acetate, polyamides, polyesters, chlorinated polyethylene, polyurethanes, polystyrene, silicone polymers, styrene-ethylene-butylene-styrene (SEBS) block copolymers, epoxy resins, and mixtures of two or more of these in any proportion.

[0044] Preferably, the elastomeric matrix of the composite material of the present invention is selected from polysiloxanes and synthetic rubbers, more preferably from polysiloxanes, alone or in a mixture with one or more of the polymers listed above.

[0045] The elastomeric matrix of the composite material of the invention, whether or not it contains one or more of the elastomers listed above, can be subjected to post-treatments, i.e. after the incorporation of the zeolite, such as physicochemical treatments, such as crosslinking or curing, or any other desired treatment for the intended application.

[0046] The preparation of the composite material of the invention can be carried out by simply mixing the zeolite with the elastomeric matrix, according to techniques known to those skilled in the art for incorporating mineral fillers into polymeric materials. Mixing can thus be carried out, for example and without limitation, in an extruder, in a laminar mixer or calendar, in a twin screw mixer, in a Brabender type mixer with rotating blades, in various forms suitable for each type of matrix, or in a Banbury type device with two spiral rotors rotating in opposite directions at variable rotation speeds.

[0047] As indicated above, at this stage it is possible to add one or more additives. The incorporation temperature is adjusted depending on the type of elastomeric polymer and can very generally be between 20 ° C and 400 ° C.

[0048] The composite materials of the present invention can be formed into the desired shape for the end use, for example, by molding, extrusion, extrusion, rolling, etc.

[0049] The aforementioned unique properties of 3A zeolite greatly facilitate its incorporation into elastomer matrices. The improved rheological behavior resulting from the lower viscosity has led to the observation of a substantial reduction in the viscosity of the mixture and / or the incorporation of a larger amount of zeolite into the elastomer matrix, and thus the possibility of a substantially less energy intensive and / or more rapid operation for the incorporation of zeolite. This allows a reduction in the preparation time of the composite material according to the invention, making its industrial production more profitable (improving productivity) and / or resulting in the possibility of increasing the proportion of zeolite in said composite material, and thus enhancing the adsorption properties of said composite material for the same mass.

[0050] The composite material of the present invention finds very advantageous application as an adsorbent composite, in particular as a desiccant composite which can be used in particular for the manufacture of masterbatches, in packaging, in the manufacture of insulating glazing, for use in the pharmaceutical, medical, food processing, electronic, automotive and construction sectors, to name a few.

[0051] The following examples serve to illustrate the purpose of the present invention and are provided as a guide only, without intending to limit the various embodiments of the invention in any way.

[0052] In the following examples, the physical properties of the zeolites were evaluated by methods known to those skilled in the art, the main ones of which are repeated below.

[0053] <Characterization Technology> The physical properties of zeolites are evaluated by methods known to those skilled in the art, the main ones being repeated below.

[0054] <Zeolite crystal particle size> The number-average diameter of zeolite crystals is evaluated by observation with a scanning electron microscope (SEM). To evaluate the size of the zeolite crystals in the sample, a set of images is taken at a magnification of at least 5000. The diameter of at least 200 crystals is then measured using dedicated software, for example the Smile View software published by LoGraMi. The accuracy is on the order of 3%.

[0055] <Chemical analysis of zeolites, determination of Si / Al molar ratio and exchange degree> The elemental chemical analysis of the zeolite powder according to the invention can be carried out according to various analytical techniques known to the person skilled in the art, including the technique of chemical analysis by X-ray fluorescence as described in the standard NF EN ISO 12677:2011 in a wavelength dispersive spectrometer (WDXRF), for example a Tiger S8 instrument from Bruker.

[0056] X-ray fluorescence is a non-destructive spectral technique that utilizes the photoluminescence of atoms in the X-ray range to establish the elemental composition of a sample. Excitation of the atoms, typically by an X-ray beam or electron bombardment, produces specific radiation after the atoms return to their ground state. After calibration for each oxide, measurement uncertainties of less than 0.4% by weight are traditionally obtained.

[0057] Examples of other analytical methods include atomic absorption spectrometry (AAS) and inductively coupled plasma atomic emission spectrometry (ICP-AES), as described in standards NF EN ISO 21587-3 or NF EN ISO 21079-3, on instruments such as the Perkin Elmer 4300DV.

[0058] X-ray fluorescence spectra have the advantage of being almost independent of the chemical combination of elements and provide accurate determinations both quantitatively and qualitatively. After calibration for each oxide SiO2 and Al2O3, and also for different oxides (e.g., those derived from exchangeable cations such as potassium), conventionally, a measurement uncertainty of less than 0.4 wt% is obtained. Therefore, the above-described elemental chemical analysis makes it possible to verify both the Si / Al molar ratio of the zeolite used and the degree of exchange 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 determined by solid-state silicon nuclear magnetic resonance (NMR) spectroscopy.

[0060] The degree of exchange by a given cation is calculated by evaluating the ratio between the number of moles of the cation (expressed in molar equivalents, i.e., the number of moles of charge, or twice the number of moles of the cation if the cation is divalent) and the number of moles of exchangeable sites (which is equal to the number of moles of aluminum present in the zeolite framework).

[0061] The respective amounts of each cation are evaluated by chemical analysis of the corresponding cation, and the respective amounts of the cation are evaluated by chemical analysis of the corresponding oxide (Na2O, CaO, K2O, MgO, etc.). On the other hand, the amount of hydronium ions is calculated by subtracting the number of moles of aluminum present in the zeolite framework from the total number of moles of other cations (expressed in molar equivalents) present in the zeolite.

[0062] <X-ray diffraction> The identification of the zeolite present in the composite material of the present invention is evaluated by X-ray diffraction analysis, known to those skilled in the art by the acronym XRD, after treatment with a solvent to dissolve the elastomer matrix, and the selection of the solvent is made according to the properties of the elastomer. The solid sample collected after dissolution and solvent removal is analyzed with an XRD diffractometer manufactured by Bruker.

[0063] Since each zeolite has a unique diffraction pattern defined by the positions of the diffraction peaks and their relative intensities, this analysis makes it possible to identify the various zeolites present in a sample.

[0064] The collected samples were crushed and then spread by simple mechanical compression and flattened on the sample holder. The conditions for acquiring diffractograms on a Bruker D8 Advance diffractometer were as follows: Cu tube used at 40kV-30mA Solar slit size: 2.5°, irradiation surface width: 16mm, Rotation of the sample device: 10 rpm, Measurement range: 4°<2θ<70°, Increment: 0.015°, Counting time per increment: 0.8 seconds.

[0065] The obtained diffractograms are interpreted using EVA software, which identifies the zeolites using the ICDD PDF-2 database, release 2011. The weight amounts of the zeolitic fractions are determined by XRD and evaluated using TOPAS software from Bruker.

[0066] <Small molecule adsorption test> The purpose of testing for the adsorption of small molecules, such as oxygen, is to verify that 3A zeolites that are useful in the context of the present invention have little or no capacity for adsorption of said small molecules.

[0067] The test is carried out according to the volumetric method, using a commercial gas adsorption apparatus (Tristar 2 from Micromeritics). Approximately 10 g of sample is placed in a glass cell and degassed under reduced pressure at room temperature for at least 15 hours. After degassing, the sample is placed under helium and weighed to determine the mass of the anhydrous sample. The sample is then contacted with a known volume of oxygen at 600 mmHg. This is maintained in the presence of oxygen for 24 hours at 25°C. The oxygen end pressure in the cell is then measured, which allows the amount of oxygen adsorbed by the sample to be calculated by difference. The adsorption is measured at a pressure of 25 Ncm 3 g-1 Less than 20Ncm 3 g -1 Less than 15Ncm 3 g -1 less than, advantageously 12 Ncm 3 g -1 If it is less than this, it is considered low. EXAMPLES

[0068] The various zeolite / elastomer mixtures are prepared according to the following procedure: First, a peroxide type crosslinker (Luperox P from Arkema, 3.8 g or 1.9 phr (parts per 100 rubber)) is added to 200 g (100 phr) of zeolite while stirring. This premix (PM) is then introduced into 200 g (100 phr) of silicone polymer matrix (silicone R401_70S from Wacker Chemie AG) using a Lescuyer double roll mixer.

[0069] The mixer is operated for about 60 minutes at a temperature of 20 ° C. After 25-30 minutes of operation, the unincorporated mass of the premix (i.e. rejected at the bottom of the double roll), called the "rejected mass", is weighed and then reintroduced into the mixture for 30-60 minutes. The results are considered acceptable if the rejected mass is less than 20 grams. The rotation speeds of the rolls (diameter 150 mm) are different, 18 revolutions / min for the rear roll and 24 revolutions / min for the front roll. The gap between the two rolls is about 3 mm. A homogeneous mixture is obtained in the form of a sheet with a length of about 60 cm and a width of about 15 cm and a thickness of 3 mm.

[0070] The measurement of the rheological behavior is likewise carried out using an oscillating matrix plate / plate rheometer (France Scientifique model MDR-C) at 130° C. for 60 minutes, during which the silicone matrix crosslinks. The rheometer is operated according to ISO 6502 and ASTM D5289 standards.

[0071] Composite sheets prepared with 3A zeolite crystals partially exchanged with calcium as the divalent cation have a lower minimum torque than those obtained with 3A zeolite crystals without divalent cations, indicating that a lower amount of energy is required to mix the 3A zeolite crystals of the present invention containing divalent cations with a polymer matrix, since a higher degree of divalent cation exchange with the 3A zeolite crystals of the present invention results in a more fluid mixture (viscosity reduction), as observed with calcium.

[0072] The properties of the composite sheets tested are summarized in Table 1 below (DE is the degree of cation exchange).

[0073] [Table 1]

Claims

1. 1. A composite material comprising: a) at least one elastomer, and b) a type 3A zeolite in an amount of 30 wt.% or more based on the total weight of the composite material, the cationic sites being occupied by potassium cations, sodium cations, at least one alkaline earth metal cation from Group IIA of the periodic table, and hydronium ions; Composite material comprising:

2. 2. The composite material of claim 1, wherein the cationic sites are occupied in the range of 35% to 70% by potassium cations, in the range of 2% to 62% by sodium cations, in the range of 2% to 30% by at least one alkaline earth metal cation selected from magnesium, calcium, strontium and barium, and in the range of 1% to 5% by hydronium cations, where the percentages are expressed as moles of cations relative to the total moles of exchangeable sites.

3. 3. The composite material of claim 1 or claim 2, wherein the alkaline earth metal cations are selected from magnesium and calcium cations and mixtures thereof in any proportion.

4. 4. A composite material according to any one of claims 1 to 3, wherein the selected alkaline earth metal cation is calcium and the cationic sites are occupied in the range of 5% to 30%, preferably 5% to 20%, more preferably 5% to 15% by calcium cations.

5. 5. The composite material according to any one of claims 1 to 4, wherein the number average diameter of the 3A zeolite crystals is between 0.1 μm and 4.0 μm, preferably between 0.2 μm and 3.5 μm, more preferably between 0.3 μm and 3.0 μm, as calculated by counting on a SEM image.

6. 6. A composite material according to any one of claims 1 to 5, wherein the content of zeolite is between 30% and 90%, preferably between 40% and 85%, better still between 45% and 80%, and even more preferably between 50% and 80% relative to the total weight of the composite material.

7. 7. The composite material according to any one of claims 1 to 6, further comprising one or more other zeolites in an amount of at most 20% by weight, preferably at most 10% by weight, more preferably at most 5% by weight, relative to the total weight of the zeolites, selected from other zeolites of LTA type, such as 4A zeolites and 5A zeolites, from faujasites (FAU of type LSX, MSX, X or Y) having a molar Si / Al ratio between 1 and 100, from type EMT zeolites, from type MFI zeolites having a molar Si / Al ratio between 5 and 500, from type GIS zeolites (for example zeolite P), from type SOD zeolites (for example sodalite), from type MOR zeolites, from type HEU zeolites and from type BEA zeolites.

8. 8. The composite material according to any one of claims 1 to 7, further comprising one or more additives selected from crosslinkers, colorants, pigments, antimicrobial agents, anti-fog agents, swelling agents, dispersants, lubricants, flame retardants, fillers, binders and compatibilizers of functional polyolefin type.

9. 9. The composite material of any one of claims 1 to 8, wherein the elastomeric matrix comprises one or more elastomers selected from polysiloxanes, natural rubber, polybutadiene, polynitriles, hydrogenated or partially hydrogenated polynitriles, styrene-isoprene-butadiene rubber, polyisobutylene and polyisobutene, halogenated or non-halogenated isobutylene-isoprene elastomeric copolymers, polychloroprene, EPDM rubber, chlorinated polyethylene, polysulfonated rubber, polyisoprene, and mixtures of two or more thereof in any proportion.

10. Use of the composite material according to any one of claims 1 to 9 as an adsorbent composite, as a desiccant composite, for the production of masterbatches, for packaging and for the production of insulating glazing.

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