Radio frequency communication module with an electronic unit encased in an elastomeric material

Description

Technical field of the invention

[0001] The present invention relates to a radiofrequency communication module, or finished product capable of being inserted into the structure of a rubber article, in particular a pneumatic tire, comprising a radiofrequency transponder embedded in an elastomeric material. Prior art

[0002] It is common to integrate an electronic device into a tire, such as a passive radio frequency identification transponder. This type of transponder is generally referred to by the English acronym RFID. Such an electronic device can store data, for example, relating to the tire.

[0003] To improve the quality of data transmission stored in the electronic device, it is first coated in an elastomeric material. The dielectric properties have a direct influence on the signal transmission between the electronic device and the reading system and we are looking for a material that allows us to obtain a good compromise between the permittivity of the said material and the characteristics of the electronic device, such as for example the impedance of the RFID chip or the antenna length.

[0004] Much work has been done to propose formulations of elastomeric materials suitable for the encapsulation of electronic devices. Document US 2009 / 0015415 teaches a composition comprising natural rubber, from 5 to 55 phr of silica and less than 30 phr of carbon black. Document WO 2016 / 105929 teaches a composition comprising natural rubber and at least 35 phr of a coarse black, the specific surface area of ​​which is less than 30 m 2 < / g.

[0005] WO 2016 / 105937, WO 2016 / 105938 and WO 2017 / 083251 teach the addition of a filler other than carbon black or silica, namely crosslinked rubber particles, a non-reinforcing filler or a nano-sized inorganic material, in order to improve the permittivity of the compositions.

[0006] Documents EP 3711974, WO 2018 / 104622, WO 2019 / 170998 and EP 1028007 are also part of the state of the art. The electronic device may be coated in an elastomeric material to form an assembly constituting a radiofrequency communication module and stored before its incorporation into a tire, or any other elastomeric article. This makes it possible to protect it and facilitate its incorporation.

[0007] These modules are often small in size, on the order of a few tens of millimeters. However, at these scales, difficulties can be observed in ensuring the geometric stability of the strips of elastomeric material intended to coat the electronic device, and in particular a shrinkage effect after extrusion of the strips.

[0008] It is therefore important to formulate a composition such that the radiofrequency communication module obtained has good geometric stability until its incorporation into a rubber article, the module having to have, once the article is cured or crosslinked, a rigidity similar to the adjacent compositions so as not to disturb the performance of the rubber article, while ensuring good operation of the device with a low dielectric constant.

[0009] Continuing its research, the applicant discovered that a radiofrequency communication module comprising a specific elastomeric material exhibited excellent geometric stability, particularly during the manufacture of the elastomeric material elements intended to coat the device, while reconciling the sometimes contradictory properties of rigidity similar to adjacent compositions and low permittivity of the elastomeric material. Detailed description of the invention

[0010] The invention, described in more detail below, relates to a radiofrequency communication module (2) comprising an electronic device (1) coated in elastomeric material (3a, 3b), the elastomeric material comprising: from 40 to 55 pce of a butadiene elastomer chosen from polybutadienes, and from 45 to 60 pce of an isoprene elastomer chosen from natural rubber and synthetic polyisoprenes, and does not include any other elastomer; from 6 to 20 pce of carbon black having a BET specific surface area ranging from 70 to 99 m 2 < / g; from 25 to 35 pce of inorganic filler. Definitions

[0011] The carbon-containing compounds mentioned in the description may be of fossil or bio-sourced origin. In the latter case, they may be partially or totally derived from biomass or obtained from renewable raw materials derived from biomass. This includes polymers, plasticizers, fillers, etc. Elastomeric material

[0012] The electronic device of the radiofrequency communication module according to the invention is coated in an elastomeric material. Elastomer

[0013] The elastomeric material in which the electronic device is embedded is based on 10 to 60 pce of at least one butadiene elastomer. Thus, the elastomeric material may contain one or more butadiene elastomers or a mixture of one or more butadiene elastomers with one or more other elastomers, for example diene elastomers other than butadiene elastomers.

[0014] The butadiene elastomer of the elastomeric material is preferably chosen from the group consisting of polybutadienes (abbreviated "BR"), butadiene copolymers, and mixtures thereof. Such butadiene copolymers are more preferably chosen from the group consisting of butadiene-styrene (SBR) copolymers and mixtures thereof. Preferably, the butadiene elastomer is chosen from the group consisting of polybutadienes and mixtures thereof. Preferably, the butadiene elastomer is non-syndiotactic.

[0015] The elastomeric material also preferably comprises an isoprene elastomer.

[0016] By "isoprene elastomer" is meant a homopolymer or a copolymer of isoprene, in other words a diene elastomer chosen from the group consisting of natural rubber (NR) which can be plasticized or peptized, synthetic polyisoprenes (IR), the various isoprene copolymers, in particular isoprene-styrene copolymers (SIR), isoprene-butadiene copolymers (BIR) or isoprene-butadiene-styrene copolymers (SBIR), and mixtures of these elastomers.

[0017] Preferably, the isoprene elastomer is chosen from the group consisting of synthetic polyisoprenes, natural rubber, isoprene copolymers and mixtures thereof, preferably from the group consisting of natural rubber, polyisoprenes comprising a cis 1,4 linkage mass percentage of at least 90%, more preferably at least 98%, relative to the mass of the isoprene elastomer and mixtures thereof. Preferably, the isoprene elastomer is natural rubber.

[0018] The elastomeric material comprises 40 to 55 parts of a butadien elastomer selected from polybutadienes, and 45 to 60 parts of an isoprene elastomer selected from natural rubber and synthetic polyisoprenes, and does not comprise any other elastomer.

[0019] The electrically insulating elastomeric material preferably includes an adhesion promoter for bonding it to the electronic device. This promoter can be a cobalt or nickel salt, for example, cobalt naphthenate at a concentration of less than 3 parts per cubic centimeter (ppc) and with a suitable sulfur content, on the order of 5 to 7 ppc. The electrically insulating elastomeric material preferably has a dielectric constant measured between 800 MHz and 1 GHz of less than 6.5.

[0020] The elastomeric material preferably comprises a vulcanization system comprising sulfur and a vulcanization accelerator. Charge

[0021] The elastomeric material in which the electronic device is embedded comprises at least 6 to 20 pce of carbon black having a BET specific surface area ranging from 70 to 99 m 2 < / g and 20 to 40 pce of inorganic filler.

[0022] Suitable carbon blacks are carbon blacks conventionally used in tires (so-called tire-grade blacks). These carbon blacks can be used in their isolated form, as commercially available, or in any other form, for example as a carrier for some of the rubber additives used. The carbon blacks could, for example, already be incorporated into an isoprene elastomer in the form of a masterbatch (see, for example, applications WO 97 / 36724 or WO 99 / 16600).

[0023] Carbon blacks are characterized by various properties, including BET specific surface area and Compressed Oil Absorption Number (COAN). The COAN of carbon blacks is measured according to ASTM D3493-16.

[0024] The specific surface area BET of carbon blacks is measured according to standard D6556-10 (multipoint method (minimum 5 points) - gas: nitrogen - relative pressure range P / P0: 0.1 to 0.3).

[0025] Examples of carbon blacks useful for the needs of the invention are the 300 series blacks such as N330, N347.

[0026] The carbon black content in the elastomeric material is preferably within a range of values ​​from 8 to 15 parts per cent.

[0027] The elastomeric material preferably does not comprise carbon black with a BET surface area of ​​less than 70 m 2 < / g or comprises less than 10 pce, preferably less than 5 pce, preferably less than 2 pce, preferably less than 1 pce.

[0028] The elastomeric material preferably does not comprise carbon black with a BET surface area greater than 99 m 2 < / g or comprises less than 10 pce, preferably less than 5 pce, preferably less than 2 pce, preferably less than 1 pce.

[0029] The elastomeric material also includes 25 to 35 pce of inorganic filler.

[0030] The physical state in which the inorganic filler is present is indifferent, whether in the form of powder, microbeads, granules, balls or any other suitable densified form.

[0031] The inorganic filler is preferably chosen from the group consisting of mineral fillers of the siliceous type, in particular silica (SiO2), of the aluminous type, in particular alumina (Al2O3), chalk, clay, bentonite, talc, kaolin, glass microbeads, glass flakes and mixtures thereof, preferably from silica, chalk, clay, bentonite, talc, kaolin and mixtures thereof, preferentially from silica, chalk, kaolin and mixtures thereof. Very preferably, the inorganic filler is silica.

[0032] The silica used may be any reinforcing silica known to those skilled in the art, in particular any precipitated or pyrogenic silica having a BET surface area and a CTAB specific surface area both less than 450 m2 / g, preferably from 30 to 400 m2 / g. Examples of highly dispersible precipitated silicas (called "HDS") include Ultrasil 7000 and Ultrasil 7005 silicas from Degussa, Zeosil 1165MP, 1135MP and 1115MP silicas from Rhodia, Hi-Sil EZ150G silica from PPG, Zeopol 8715, 8745 and 8755 silicas from Huber, and high specific surface area silicas as described in application WO 03 / 16837.

[0033] In this presentation, the BET specific surface area of ​​silica is determined by gas adsorption using the Brunauer-Emmett-Teller method described in "The Journal of the American Chemical Society" (Vol. 60, page 309, February 1938), and more precisely according to a method adapted from the NF ISO 5794-1 standard, annex E of June 2010 [multipoint volumetric method (5 points) - gas: nitrogen - vacuum degassing: one hour at 160°C - relative pressure range p / po: 0.05 to 0.17].

[0034] The CTAB specific surface area of ​​silica is determined according to the French standard NF T 45-007 of November 1987 (method B).

[0035] In the preferred case where the inorganic filler comprises silica, the latter preferably has a BET surface area of ​​between 45 and 400 m2 / g, more preferably between 60 and 300 m2 / g.

[0036] To couple the reinforcing inorganic filler to the elastomer, one can optionally use in a known manner a coupling agent (or bonding agent) at least bifunctional intended to ensure a sufficient connection, of a chemical and / or physical nature, between the inorganic filler (surface of its particles) and the elastomer, in particular organosilanes, or bifunctional polyorganosiloxanes.

[0037] In particular, polysulfurized silanes, called "symmetrical" or "asymmetrical" depending on their particular structure, can be used, as described for example in applications WO03 / 002648 (or US 2005 / 016651) and WO03 / 002649 (or US 2005 / 016650).

[0038] Examples of polysulfurized silanes include bis-(alkoxyl(C1-C4)-alkyl(C1-C4)silyl-alkyl(C1-C4)) polysulfides (especially disulfides, trisulfides or tetrasulfides), such as bis(3-trimethoxysilylpropyl) or bis(3-triethoxysilylpropyl) polysulfides. Among these compounds, bis(3-triethoxysilylpropyl) tetrasulfide, abbreviated to TESPT, of formula [(C 2 H 5 O) 3 Si(CH 2 ) 3 S 2 ] 2 or bis-(triethoxysilylpropyl) disulfide, abbreviated to TESPD, of formula [(C 2 H 5 O) 3 Si(CH 2 ) 3 S] 2 . Mention will also be made, as preferred examples, of polysulfides (in particular disulfides, trisulfides or tetrasulfides) of bis-(monoalkoxyl(C1-C4)-dialkyl(C1-C4)silylpropyl), more particularly bis-monoethoxydimethylsilylpropyl tetrasulfide as described in patent application US 2004 / 132880.

[0039] As coupling agent other than polysulfurized alkoxysilane, mention may in particular be made of bifunctional POS (polyorganosiloxanes) or hydroxysilane polysulfides as described in patent applications WO 02 / 30939 and WO 02 / 31041, or silanes or POS bearing azo-dicarbonyl functional groups, as described for example in patent applications WO 2006 / 125532, WO 2006 / 125533, WO 2006 / 125534.

[0040] In elastomeric materials according to the invention, the coupling agent content is preferably between 4 and 12 parts per liter, more preferably between 4 and 8 parts per liter. In another arrangement, the elastomeric materials according to the invention do not include a coupling agent. Crosslinking system

[0041] The elastomeric material preferably comprises a vulcanization system comprising sulfur and a vulcanization accelerator.

[0042] Since the crosslinking system is sulfur-based, it is referred to as a vulcanization system. The sulfur can be provided in any form, including molecular sulfur or a sulfur-donating agent. At least one vulcanization accelerator is also present, and, optionally, various known vulcanization activators such as zinc oxide, stearic acid or equivalent compounds such as stearic acid salts and transition metal salts, guanidine derivatives (especially diphenylguanidine), or known vulcanization retarders can also be used.

[0043] Sulfur is used at a preferential rate of between 0.1 and 10 parts per million, preferably between 1 and 5 parts per million. The vulcanization accelerator is used at a preferential rate in the range of 1 to 10 parts per million, preferably from 1 to 5 parts per million.

[0044] Any compound capable of acting as an accelerator for the vulcanization of diene elastomers in the presence of sulfur may be used as an accelerator, in particular accelerators of the thiazole type and their derivatives, accelerators of the sulfenamide, thiuram, dithiocarbamate, dithiophosphate, thiourea and xanthate types. Examples of such accelerators include, but are not limited to, the following compounds: 2-mercaptobenzothiazyl disulfide (abbreviated as "MBTS"), N-cyclohexyl-2-benzothiazyl sulfenamide ("CBS"), N,N-dicyclohexyl-2-benzothiazyl sulfenamide ("DCBS"), N-tert-butyl-2-benzothiazyl sulfenamide ("TBBS"), N-tert-butyl-2-benzothiazyl sulfenimide ("TBSI"), tetrabenzylthiuram disulfide ("TBZTD"), zinc dibenzyldithiocarbamate ("ZBEC") and mixtures of these compounds. Various additives

[0045] The elastomeric material may also include all or part of the usual additives normally used in elastomer compositions for the manufacture of rubber articles, in particular pneumatic bandages, such as plasticizers or extending oils, whether aromatic or non-aromatic, pigments, protective agents such as anti-ozone waxes, chemical anti-ozonants, antioxidants, anti-fatigue agents, reinforcing resins such as bismaleimides, acceptors (e.g. novolac phenolic resin) or methylene donors (e.g. HMT or H3M).

[0046] The elastomeric material may also comprise an adhesion promoter such as a cobalt salt, intended to improve the adhesion between the metal surface of the electronic device and the elastomeric material. When comprising cobalt salt, the elastomeric material preferably comprises at most 5 phr of cobalt salt.

[0047] The elastomeric material of the invention may also comprise an alkaline earth, alkali or lanthanide metal salt.

[0048] The salt of an alkaline earth, alkali or lanthanide metal may advantageously be an acetylacetonate of an alkaline earth, alkali or lanthanide metal.

[0049] Preferably, the alkaline earth, alkali, or lanthanide metal of the salt is chosen from the group consisting of lithium, sodium, potassium, calcium, magnesium, lanthanum, cerium, praseodymium, neodymium, samarium, erbium, and mixtures thereof. Even more preferably, the salt of an alkaline earth, alkali, or lanthanide metal is a magnesium or neodymium salt. In other words, the salt of an alkaline earth, alkali, or lanthanide metal is advantageously a magnesium or neodymium acetylacetonate, preferably a magnesium acetylacetonate.

[0050] The level of the alkali-earth, alkali or lanthanide metal salt may be, for example, in a range of 0.1 to 5 pc, preferably 0.5 to 4 pc and more preferably 0.5 to 2 pc.

[0051] The elastomeric material of the invention may further comprise a cobalt salt. For example, the cobalt salt may be chosen from the group consisting of abietates, acetylacetonates, tallates, naphthenates, resinates and mixtures thereof. The cobalt salt content may advantageously be within a range from 0.5 to 3 phr, preferably from 0.5 to 2 phr, preferably from 0.5 to 1.2 phr. Electronic device

[0052] The radiofrequency communication module according to the invention may comprise any type of electronic device. In particular, the electronic device is preferably a passive radiofrequency identification transponder, often identified by the English acronym RFID (Radio-Frequency IDentification) and subsequently referred to as “radiofrequency transponder”.

[0053] The term "radio frequency transponder" here refers to a transponder whose interrogation is performed externally and passively. The interrogation phases therefore require no energy from the transponder itself. The primary function of the radio frequency transponder is to identify the rubber item into which it is integrated, such as an inflatable tube.

[0054] Radio frequency transponders usually include an electronic chip and a radiating antenna capable of communicating with a radio frequency reader.

[0055] In particular, the radio frequency transponder's communication frequency is located in the UHF (Ultra High Frequency) band, between 300 MHz and 3 GHz. This provides an advantageous compromise between a small radiating antenna, easily integrated into an elastomeric material intended for a tire or rubber item, and a long transponder reading range, far from the tire or rubber item. Advantageously, the radio frequency transponder communicates in the narrow frequency band between 860 MHz and 960 MHz, and more specifically on the very narrow bands of 860 MHz to 870 MHz and 915 MHz to 925 MHz. Indeed, at these frequencies, the conventional elastomeric compounds of a tire have a significant influence on the propagation of radio waves.Furthermore, these frequencies—defined by standards—require a reduction in the length of the radiating antenna, which has the advantage of facilitating the integration of the radio frequency transponder, embedded in a rubber patch, within the pneumatic tire. The radio frequency communication module also complies with ISO 29160, 20912, and 18000-63 standards.

[0056] According to a first embodiment, the radiating antenna comprises two helical antenna sections and the electronic chip is galvanically connected to the two helical antenna sections.

[0057] According to another embodiment, the radio frequency transponder further comprises a primary antenna electrically connected to the electronic chip, in which the primary antenna is inductively coupled to the radiating antenna, and in which the radiating antenna is a dipole antenna made of a single-strand helical spring.

[0058] This second embodiment has the advantage of mechanically separating the radiating antenna from the electronic components of the transponder and thus eliminating the weak point of conventional transponders, namely the area where the antenna sections are attached to the electronic chip support. Process for coating an electronic device

[0059] The radio frequency communication module can be manufactured by a process that includes the following steps: Prepare two layers of elastomeric material as described herein, Sandwich the electronic device between the two layers, If necessary bake the module.

[0060] Alternatively, the module can be manufactured by depositing the electronic device on a portion of a layer, the layer is then folded over itself to cover the electronic device which is thus sandwiched along its entire length or part of its length.

[0061] The layers can be produced by calendering. During the baking of the module, the elastomeric material is crosslinked.

[0062] The communication module according to the invention, by virtue of its properties, can be integrated into any type of rubber article, such as, for example, balloons, conveyor belts, and inflatable articles. In particular, the communication module according to the invention is especially suitable for integration into the structure of a pneumatic tire. Pneumatic tire

[0063] The invention also relates to a pneumatic tire comprising a top, two ridges and two sidewalls, a carcass ply anchored in said two ridges, comprising a radio frequency communication module according to the invention.

[0064] In a preferred embodiment, the axis of the radiating antenna of the radio frequency communication module is oriented such that nearby metallic elements do not interfere with the propagation plane of the electromagnetic wave, whether transmitted to or from the transponder. In the case of a metallic array, the angle between the axis of the radiating antenna and the axis of the cables must be between 70° and 130°.

[0065] Thus, in a preferred embodiment, a tire comprises a metallic sheet including metallic reinforcements substantially parallel to each other, embedded in a rubber composition, wherein the radio frequency communication module includes a radiating antenna, the angle between the axis of the radiating antenna and the axis of the metallic reinforcements being between 70° and 130°.

[0066] According to one embodiment, the radiofrequency communication module can be fixed to a sidewall of the tire. This avoids placing it in the immediate vicinity of the centering bead or the middle of the tire sidewall, but rather above or below this centering bead.

[0067] According to another embodiment, the radio frequency communication module can be fixed to the surface of the inner layer of the tire.

[0068] According to yet another embodiment, the radio frequency communication module is integrated into the tire during its manufacture.

[0069] The implementation of such a radio frequency communication module can take place at any time during the life of the tire, from its manufacture to its retreading.

[0070] The tire equipped with a radiofrequency communication module may be a tire intended to equip passenger motor vehicles, SUVs ("Sport Utility Vehicles"), two-wheelers (in particular motorcycles), airplanes, as well as industrial vehicles chosen from vans, "Heavy Goods Vehicles", i.e. metro, buses, road transport vehicles (trucks, tractors, trailers), off-road vehicles such as agricultural or civil engineering vehicles, and other transport or handling vehicles. Description of figures

[0071] [ Fig 1 ] There figure 1has a radiating antenna 10 consisting of a steel wire 12 which has been plastically deformed in order to form a helical spring having an axis of revolution 11. This steel wire is coated with a conduction layer of copper, aluminum, silver, gold, copper, tin, zinc or brass covered if necessary with a chemical insulation layer for example of brass, zinc, nickel or tin to protect the elastomeric material from the material of the conduction layer.

[0072] The electromagnetic conduction of such an antenna is mainly carried out by a skin effect, that is to say it is mainly ensured in the outer layers of the antenna. This skin thickness is in particular a function of the radiation frequency and the conductivity of the material constituting the conduction layer. For example, for a UHF frequency (for example 915 MHz), the skin thickness is of the order of 2.1 µm for silver, 2.2 µm for copper, 4.4 µm for brass.

[0073] Steel wire can be coated with these layers and then shaped; alternatively, it can also be shaped and then coated.

[0074] The helical spring is first defined by a winding diameter of the coated wire and a helix pitch. Thus, the inner diameter 13 and outer diameter 15 of the helical spring are precisely determined by taking into account the diameter of the wire. The length of the spring 17 corresponds here to half the wavelength of the transmission signal of the radiofrequency transponder 1 in a rubber mass. Thus, a median plane 19 can be defined for the helical spring perpendicular to the axis of revolution 11 separating the radiating antenna into two equal parts. This plane is in the middle of the central zone 16 of the radiating antenna, this central zone 16 corresponds to approximately 25% of the total length of the antenna and preferably 15%.

[0075] [ Fig 2 ] There figure 2presents a radiofrequency transponder 1 in a configuration where the electronic part 20 is located inside a radiating antenna 10. The geometric shape of the electronic part 10 is circumscribed in a cylinder whose diameter is less than or equal to the internal diameter 13 of the helical spring. The threading of the electronic part 20 into the radiating antenna 10 is thus facilitated.

[0076] [ Fig 3 ] There figure 3 shows in axial section a tire comprising in its structure a radiofrequency communication module placed according to the two modes previously described.

[0077] There figure 3 indicates the axial X, circumferential C and radial Z directions.

[0078] This tire 30 has a crown 32 reinforced by a crown reinforcement or belt 36, two sidewalls 33 and two bead 34, each of these bead 34 being reinforced with a bead 35. The crown reinforcement 36 is radially surmounted externally by a rubber tread 39. A carcass reinforcement 37 is wound around the two bead 35 in each bead 34, the reverse 38 of this reinforcement 37 being, for example, disposed towards the outside of the tire 30.The carcass reinforcement 37 is, in a manner known per se, made up of at least one ply reinforced by so-called “radial” cables, for example textile cables here, that is to say that these cables are arranged practically parallel to each other and extend from one bead to the other so as to form an angle of between 80° and 90° with the median circumferential plane (as well as the median plane (plane perpendicular to the axis of rotation of the tire which is located midway between the two beads 4 and passes through the middle of the crown reinforcement 36). A layer of waterproof inner rubber 40 (in English “inner liner”) extends from one bead to the other radially internally relative to the carcass reinforcement 37.

[0079] This tire 30 comprises, by way of illustration, a communication module 2 placed at the interface between the rubber mixture constituting the sidewall 33 and the carcass ply 37. The position illustrated is radially external to the end of the turn-up 38 of the carcass ply 37, under the middle of the sidewall 33. This position is excellent for radiofrequency communication between the transponder and an external reader and the very good robustness of the radiofrequency transponder of the communication module allows it to withstand without damage the high mechanical stresses linked to rolling.

[0080] The tire 30 also includes a communication module in its pre-vulcanized configuration, fixed to the inner rubber 40 of the tire by means of a layer of conventional cold-vulcanizing bonding rubber, such as Gray gum supplied by Tech International. This communication module was fixed after the tire was manufactured, for example, in preparation for retreading operations on the tire tread.

[0081] [ Fig 4 ] There figure 4 represents an electronic device (1) coated in two layers of an elastomeric material (3a, 3b), the assembly constituting a radiofrequency communication module (2). Examples Preparation of rubber compositions

[0082] The following tests are conducted as follows: the diene elastomer (epoxy-coated or not), the reinforcing filler, and the various other ingredients, with the exception of the vulcanization system, are successively introduced into an internal mixer (final filling rate: approximately 70% by volume), whose initial tank temperature is approximately 60°C. A thermomechanical process (non-productive phase) is then carried out in a single step, lasting approximately 3 to 4 minutes in total, until a maximum "drop" temperature of 165°C is reached.

[0083] The mixture thus obtained is collected, cooled, and then sulfur and an accelerator (sulfenamide) are incorporated on a mixer (homo-finisher) at 30 °C, mixing everything (productive phase) for an appropriate time (for example between 5 and 12 min).

[0084] The compositions thus obtained are then calendered in the form of plates (thickness of 2 to 3 mm) or thin sheets of rubber.

[0085] An electronic device is sandwiched between two layers of identical composition, as shown in figure 4 in order to obtain a radio frequency communication module.

[0086] This module has a length between 3 and 8 cm and a width between 0.5 and 3 cm. Permittivity

[0087] The relative permittivity of each composition is measured. The results are expressed on a basis of 100, with 100 corresponding to the composition with the most unfavorable permittivity for use as a coating gum for an electronic device, in this case composition C4. The lower the value, the more favorable the relative permittivity is for the use of the evaluated gum as a coating gum for an electronic device. Withdrawal

[0088] Shrinkage is assessed by measuring the length L0 of the module obtained immediately after calendering the rubber compound into a sheet and cutting the rubber sheet to the desired dimensions, then measuring the length L1 of the module after a stabilization time of between 1 and 48 hours, the precise stabilization time corresponding to the time after which the module length no longer changes. Shrinkage is calculated as (L0 - L1) / L0.

[0089] A value of 100 is assigned to the composition with the greatest shrinkage. A value less than 100 corresponds to less shrinkage.

[0090] It is observed that the communication module according to the invention has both very low shrinkage and a permittivity which is particularly favorable to the use of the gum as a coating gum for an electronic device intended to be integrated into a rubber article. [Painting] C1 C2 C3 C4 NR (1) 50 100 50 50 BR (2) 50 0 50 50 Black N330 9 9 3 30 Silica SIL165G (3) 30 30 30 30 Additives (4) 7,5 7,5 7,5 7,5 Vulcanization system (5) 4,5 4,5 4,5 4,5 Of which insoluble sulfur 2 2 2 2 Results Relative permittivity @915 MHz 40 40 20 100 Withdrawal 20 100 50 40 (1) Natural rubber (2) Non-functional polybutadiene “Buna CB24” marketed by Lanxess (3) “165G” silica marketed by Solvay (4) Additives include zinc oxide (industrial grade, Umicore company), stearic acid (“Pristerene 4931” from Uniqema company), N-1,3-dimethylbutyl-N-phenylparaphenylenediamine (“Santoflex 6-PPD” from Flexsys company) and 2,2,4-Trimethyl-1,2-Dihydroquinoline (TMQ) polymer (5) The vulcanization system comprises insoluble sulfur, the accelerator (N,N-dicyclohexylbenzothiazole-2-sulfenamide from Flexsys) and the retarder (N-cyclohexylthiophthalimide marketed under the name “Vulkalent G” by Lanxess) for vulcanization.

Claims

1. Radiofrequency communication module (2) comprising an electronic device (1) coated in elastomeric material (3a, 3b), the elastomeric material comprising: - from 40 to 55 phr of a butadiene elastomer selected from the polybutadienes, and from 45 to 60 pce of an isoprene elastomer, selected from natural rubber and synthetic polyisoprenes, and does not comprise other elastomers ; - from 6 to 20 phr of carbon black exhibiting a BET specific surface ranging from 70 to 99 m2 / g; - from 25 to 35 phr of inorganic filler.

2. Radiofrequency communication module according to the preceding claim, comprising from 8 to 15 phr of carbon black exhibiting a BET specific surface ranging from 70 to 99 m2 / g.

3. Radiofrequency communication module according to any one of the preceding claims, in which the inorganic filler is selected from the group consisting of inorganic fillers of the siliceous type, in particular silica, of the aluminous type, in particular alumina, chalk, clay, bentonite, talc, kaolin, glass microbeads, glass flakes and their mixtures, preferably from silica, chalk, clay, bentonite, talc, kaolin and their mixtures, preferentially from silica, chalk, kaolin and their mixtures.

4. Radiofrequency communication module according to the preceding claim, in which the inorganic filler is silica.

5. Radiofrequency communication module according to any one of the preceding claims, in which the elastomeric material comprises a vulcanization system comprising sulfur and a vulcanization accelerator.

6. Radiofrequency communication module according to any one of the preceding claims, comprising from 0 to 5 phr of an adhesion promoter, preferentially cobalt salt.

7. Radiofrequency communication module according to any one of the preceding claims, in which the elastomeric material is an electrical insulator, preferably with a dielectric constant, measured between 800 MHz and 1 GHz, of less than 6.5.

8. Radiofrequency communication module according to any one of the preceding claims, in which the electronic device is a radiofrequency transponder.

9. Radiofrequency communication module according to the preceding claim, in which the communication frequency of the radiofrequency transponder lies in the UHF band of between 300 MHz and 3 GHz, preferentially in the narrow frequency band of between 860 MHz and 960 MHz and very preferentially over very narrow bands from 860 MHz to 870 MHz and 915 MHz to 925 MHz.

10. Tyre comprising a radiofrequency communication module according to any one of the preceding claims.

11. Tyre according to the preceding claim, comprising a metal ply comprising metal reinforcements which are substantially parallel to one another and which are embedded in a rubber composition, in which tyre the radiofrequency communication module comprises a radiating antenna, the angle between the axis of the radiating antenna and the axis of the metal reinforcements being between 70° and 130°.