FR2958294A1 - Use, in an elastomer composition including isoprene elastomer, of precipitated silica containing aluminum, as reinforcing inorganic filler, and 3 - acryloyloxy - propyltriethoxysilane - Google Patents

Abstract

Use, in an elastomer composition including at least one isoprene elastomer, of a precipitated silica containing aluminum, as reinforcing inorganic filler, and 3-acryloyloxy-propyltriethoxysilane, as an inorganic filler-elastomer coupling agent, is claimed, where the aluminum content of the precipitated silica is greater than 0.5 wt.%, is claimed. An independent claim is included for the elastomer composition comprising: at least one isoprene elastomer; at least one inorganic reinforcing filler; and inorganic filler-elastomer coupling agent.

Description

USE OF A PRECIPITATED SILICA CONTAINING ALUMINUM AND 3-ACRYLOXY-PROPYLTRIETHOXYSILANE IN AN ISOPRENEIC ELASTOMER (S) COMPOSITION The invention relates to the joint use in compositions. elastomer (s) comprising an isoprene elastomer, such as natural rubber, of a particular reinforcing inorganic filler and a particular inorganic filler - elastomer coupling agent.

It also relates to the corresponding elastomer compositions and articles, in particular tires, comprising such compositions.

It is known that the elastomeric articles are generally subjected to various constraints, for example such as a temperature variation, a significant frequency stress variation in dynamic regime, a significant static stress and / or fatigue in significant bending in dynamic mode. Such articles are, for example, tires, shoe soles, floor coverings, conveyor belts, power transmission belts, hoses, seals, especially appliance seals, role of engine vibration extractors either with metal reinforcements or with a hydraulic fluid inside the elastomer, cable sheaths, cables, ropeway rollers.

It was then proposed to use in particular elastomer compositions (s) reinforced with specific inorganic fillers described as "reinforcing", preferably having a high dispersibility. These fillers, in particular white fillers such as precipitated silicas, are capable of competing with or even exceeding at least from the point of view reinforcing the conventionally used carbon black, and also offer these compositions a generally lower hysteresis, which is synonymous in particular a decrease in the internal heating of the elastomeric articles (s) during their use.

It is known to those skilled in the art that it is generally necessary to employ in the elastomer compositions containing such reinforcing fillers a coupling agent, also called a binding agent, whose function is, in particular, to providing the connection between the surface of the inorganic filler particles (for example a precipitated silica) and the elastomer (s), while facilitating the dispersion of this inorganic filler within the elastomeric matrix. The term "inorganic filler-elastomer coupling agent" is understood to mean an agent capable of establishing a sufficient chemical and / or physical connection between the inorganic filler and the elastomer. Such a coupling agent, at least bifunctional, has for example as simplified general formula "NVM", in which: - N represents a functional group ("N" function) capable of binding physically and / or chemically to the inorganic filler, such a bond can be established, for example, between a silicon atom of the coupling agent and the hydroxyl groups (OH) of the surface of the inorganic filler (for example surface silanols when it is silica ); M represents a functional group ("M" function) capable of binding physically and / or chemically to the elastomer, in particular via a suitable atom or group of atoms (for example an atom of sulfur); V represents a (divalent / hydrocarbon) group for linking "N" and

The coupling agents should not be confused with simple inorganic filler agents which, in a known manner, may have the "N" function active with respect to the inorganic filler but lack the "M" function. active with respect to the elastomer. Coupling agents, in particular (silica-elastomer), have been described in numerous documents of the state of the art, the best known being (poly) sulphide silanes, in particular (poly) sulphidized alkoxysilanes. Among these (poly) sulfurized silanes, mention may especially be made of bisistroxysilylpropyl tetrasulfide (abbreviated to TESPT), which is generally still considered today as a product providing, for vulcanizates comprising an inorganic filler as a reinforcing filler, such as silica, a very good, or even the best, compromised in terms of safety roasting, ease of implementation and strengthening power. The combined use of precipitated silica, in particular highly dispersible silica and a silane (or organosilic compound functionalized) polysulfide in a modified elastomer composition (s) allowed the development of the "green tire" for passenger vehicles (Light vehicles). This combination achieved a wear resistance performance comparable to that of carbon black-reinforced elastomer blends, while significantly improving rolling resistance (resulting in lower fuel consumption). fuel), and grip on wet ground. It would therefore be interesting to also be able to use an inorganic filler such as silica in tires for trucks, tires which are obtained from compositions based on isoprene elastomer (s), mainly natural rubber. However, the same polysulfurized silica / silane combination applied to an isoprene elastomer such as natural rubber did not make it possible to obtain a level of reinforcement (which can be illustrated by a constrained curve with uniaxial tensile elongation) sufficient with respect to which is obtained when carbon black is used as a filler, this backing resulting in poor wear resistance.

The object of the present invention is to propose in particular the combination for elastomer compositions comprising a diene elastomer, such as natural rubber, with a particular coupling agent with a particular reinforcing inorganic filler, this combination consisting of as an alternative to the use of known coupling agents with known reinforcing inorganic fillers, this combination furthermore providing, to said elastomer compositions (s), a compromise of very satisfactory properties, in particular with regard to their rheological properties, mechanical and / or dynamic, especially hysteretic. Advantageously, it allows an improvement of the hysteresis / reinforcement compromise. In addition, the elastomer compositions obtained preferably have very good adhesion to both the reinforcing inorganic filler used and the substrates to which they are subsequently applied.

The invention relates in its first object to the use in an elastomer composition (s), comprising at least one isoprene elastomer: - a precipitated silica containing aluminum, as reinforcing inorganic filler, the aluminum content of said precipitated silica being greater than 0.5% by weight, with 3-acryloxypropyltriethoxysilane (or y-acryloxypropyltriethoxysilane), as the inorganic filler-elastomer coupling agent.

Said precipitated silica used generally has an aluminum content of at most 7.0% by weight, preferably at most 5.0% by weight, in particular at most 3.5% by weight, for example at most 3.0% by weight. Preferably, its aluminum content is between 0.75 and 4.0% by weight, more preferably between 0.8 and 3.5% by weight, in particular between 0.9 and 3.2%. by weight, especially between 0.9 and 2.5% by weight or between 1.0 and 3.1% by weight. It is for example between 1.0 and 3.0% by weight, or even between 1.0 and 2.0% by weight. The amount of aluminum can be measured by any suitable method, for example by ICP-AES (Inductively Coupled Plasma - Atomic Emission Spectroscopy) after dissolution in water in the presence of hydrofluoric acid. Aluminum is, in general, substantially at the surface of the precipitated silica. Although aluminum may be present both in tetrahedral, octahedral and pentahedral form, particularly in tetrahedral and octahedral form, in the precipitated silica used in the invention, it is preferably substantially tetrahedral form (more than 50%, in particular at least 90%, especially at least 95% by number, aluminum species are then in tetrahedral form); the links are then rather essentially of the SiOAI type.

Said precipitated silica containing aluminum used in the invention is advantageously highly dispersible, that is to say that in particular it has an ability to deagglomerate and to disperse in a very important polymeric matrix, in particular observable by electron or optical microscopy, on thin sections.

Preferably, the precipitated silica used according to the invention has a CTAB specific surface area of between 70 and 240 m 2 / g. This may be between 70 and 100 m 2 / g, for example between 75 and 10 95 m 2 / g. However, very preferably, its CTAB surface area is between 100 and 240 m 2 / g, in particular between 140 and 200 m 2 / g. Likewise, preferably, the precipitated silica used according to the invention has a BET specific surface area of between 70 and 240 m 2 / g. This may be between 70 and 100 m 2 / g, for example between 75 and 95 m 2 / g. However, very preferably, its BET surface area is between 100 and 240 m 2 / g, in particular between 140 and 200 m 2 / g. The CTAB specific surface area is the external surface, which can be determined according to the method NF T 45007 (November 1987). The BET surface area can be measured according to the method of BRUNAUER - EMMETT - TELLER described in "The Journal of the American Chemical Society", vol. 60, page 309 (1938) and corresponding to standard NF T 45007 (November 1987).

The dispersibility (and disagglomeration) ability of the precipitated silica implemented according to the invention can be assessed by means of the following test, by a granulometric measurement (by laser diffraction) carried out on a silica suspension previously deagglomerated. by ultra-sonification (breaking objects from 0.1 to a few tens of microns). Ultrasound deagglomeration is carried out using a VIBRACELL BIOBLOCK (750 W) sonifier equipped with a 19 mm diameter probe. The particle size measurement is carried out by laser diffraction on a SYMPATEC granulomer, using the Fraunhofer theory.

In a pillbox (height: 6 cm and diameter: 4 cm), 2 grams of silica are weighed and the mixture is made up to 50 grams by addition of deionized water: a 4% aqueous suspension of silica is thus obtained which is homogenized during 2 minutes by magnetic stirring. The deagglomeration is then carried out under ultrasound as follows: the probe being immersed, over a length of 4 cm, it is put into action for 5 minutes and 30 seconds at 80% of its nominal power (amplitude). then the granulometric measurement by introducing into the vat of the granulometer a volume V (expressed in ml) of the homogenized suspension necessary to obtain an optical density of about 20. The value of the median diameter 050 that is obtained according to this test is even lower than the silica has a high deagglomeration ability. A deagglomeration factor FD is given by the equation: FD = 10 × V / optical density of the suspension measured by the granulometer 15 (this optical density is of the order of 20). This deagglomeration factor FD is indicative of the level of particles smaller than 0.1 μm which are not detected by the granulometer. This factor is all the higher as the silica has a high deagglomeration ability. In general, the aluminum-containing precipitated silica used according to the invention has a median diameter 50 50, after deagglomeration with ultrasound, less than 5 μm, in particular less than 4 μm, for example less than 3 μm. . It usually has an ultrafast deagglomeration factor 25 FD greater than 4.5 ml, in particular greater than 5.5 ml, for example greater than 10 ml.

The DOP oil uptake of the precipitated silica containing aluminum used according to the invention may be less than 300 ml / 100 g, for example between 200 and 295 ml / 100 g. DOP oil uptake can be determined according to ISO 787/5 by using dioctylphthalate.

One of the parameters of the silica used in the invention may reside in the distribution, or distribution, of its pore volume, and in particular in the distribution of the pore volume which is generated by pores with diameters less than or equal to 400 A. This latter volume corresponds to the useful pore volume of the charges used in the reinforcement of the elastomers. In general, the analysis of the porograms shows that this silica preferably has a porous distribution such that the pore volume generated by the pores whose diameter is between 175 and 275 A (V2) represents less than 50% of the pore volume generated by pore diameters less than or equal to 400 A (V1). 10. The pore volumes and pore diameters are measured by mercury porosimetry (Hg), using a MICROMERITICS Autopore 9520 porosimeter, and are calculated by the WASHBURN relationship with a theta contact angle of 130 ° and a gamma surface tension equal to 484 Dynes / cm.

The pH of the precipitated silica used according to the invention is generally between 6.3 and 7.6. The pH is measured according to the following method deriving from the ISO 787/9 standard (pH of a suspension at 5% in water): Apparatus: 20 - calibrated pH meter (reading accuracy to 1 / 100th) - glass electrode combined - 200 mL beaker - 100 mL test specimen - 0.01 gram precision balance. Procedure: 5 grams of silica are weighed to the nearest 0.01 gram in the 200 mL beaker. 95 mL of water measured from the graduated cylinder is then added to the silica powder. The suspension thus obtained is stirred vigorously (magnetic stirring) for 10 minutes. The pH measurement is then carried out.

The physical state in which the precipitated silica to be used according to the invention is present may be arbitrary, that is to say that it may be, for example, in the form of microbeads (substantially spherical beads), powder or granules. It may thus be in the form of substantially spherical beads of average size of at least 80 μm, preferably at least 150 μm, in particular between 150 and 270 μm; this average size is determined according to standard NF X 11507 (December 1970) by dry sieving and determination of the diameter corresponding to a cumulative refusal of 50%. It may be in the form of a powder of average size of at least 3 μm, in particular at least 10 μm, preferably at least 15 μm.

It may be in the form of granules (generally of substantially parallelepiped shape) of size of at least 1 mm, for example between 1 and 10 mm, especially along the axis of their greater length.

According to one particular nonlimiting variant, the precipitated silica, having an aluminum content greater than 0.5% by weight, used according to the invention may have: a CTAB specific surface area of between 140 and 200 m 2 / g, BET specific surface area between 140 and 200 m2 / g, - optionally, a DOP oil intake of less than 300 ml / 100g, - a median diameter of 050, after ultrasound deagglomeration, less than 3 μm, and - a factor of deagglomeration with ultrasound FD greater than 10 ml. According to another particular nonlimiting variant, the precipitated silica having an aluminum content greater than 0.5% by weight, used according to the invention may have: a CTAB specific surface area of between 140 and 200 m 2 / g, optionally, a DOP oil intake of less than 300 ml / 100 g, - a porous distribution such that the pore volume constituted by the pores whose diameter is between 175 and 275 A (V2) represents less than 50% of the pore volume constituted by pores with diameters less than or equal to 400 A (V1), and - a median diameter 050, after deagglomeration with ultrasound, lower than 5pm.

The precipitated silica implemented in the context of the invention may be prepared for example by a process as described in patent applications EP-A-0762992, EP-A-0762993, EP-A-0983966, EP-A -1355856.

Preferably, the precipitated silica employed in the invention can be obtained by a preparation process comprising the precipitation reaction between a silicate and an acidifying agent whereby a suspension of precipitated silica is obtained, followed by separation and drying. of this suspension, in which: - the precipitation reaction is carried out in the following manner: (i) an initial stock having a silicate and an electrolyte is formed, the concentration of silicate (expressed as SiO 2) in said bottom of the tank initial concentration being less than 100 g / L and the concentration of electrolyte in said initial base stock being less than 17 g / L, (ii) the acidifying agent is added to said stock foot until a value is obtained. the pH of the reaction medium is at least 7, (iii) the acidifying agent and a silicate are added simultaneously to the reaction medium, - a suspension having a solids content of not more than 24% is dried. n weight, said process comprising one of the following three operations (a), (b) or (c): (a) after step (iii), at least one aluminum compound A is added to the reaction medium, and , then or simultaneously, a basic agent, (b) after step (iii) or in place of step (iii), a silicate and at least one aluminum compound A are added simultaneously to the reaction medium. (c) step (iii) is carried out by simultaneously adding to the reaction medium acidifying agent, a silicate and at least one compound B of aluminum. It should be noted, in general, that this preparation process is a precipitation silica synthesis process, that is to say that it is made to act, under particular conditions, an acidifying agent with a silicate. The choice of acidifying agent and silicate is in a manner well known per se.

The acidifying agent used is a strong mineral acid such as sulfuric acid, nitric acid or hydrochloric acid, or an organic acid such as acetic acid, formic acid or carbonic acid. The acidifying agent may be diluted or concentrated; its normality can be between 0.4 and 36 N, for example between 0.6 and 1.5 N. In particular, in the case where the acidifying agent is sulfuric acid, its concentration can be between 40.degree. and 180 g / l, for example between 60 and 130 g / l. It is also possible to use, as silicate, any common form of silicates such as metasilicates, disilicates and advantageously an alkali metal silicate, especially sodium or potassium silicate. The silicate may have a concentration (expressed as SiO2) of between 40 and 330 g / l, for example between 60 and 300 g / l. In general, sulfuric acid is used as the acidifying agent, and sodium silicate as the silicate. In the case where sodium silicate is used, it generally has an SiO 2 / Na 2 O weight ratio of between 2.5 and 4, for example between 3.1 and 3.8. The reaction of the silicate with the acidifying agent is in a specific manner according to the following steps. Firstly, a stock is formed which comprises silicate and an electrolyte (step (i)). The amount of silicate present in the initial stock is advantageously only a part of the total amount of silicate involved in the reaction. The term electrolyte is here understood in its normal acceptation, that is to say that it signifies any ionic or molecular substance which, when in solution, decomposes or dissociates to form ions or particles. loaded. As the electrolyte, mention may be made of a salt of the group of alkali and alkaline earth metal salts, in particular the salt of the starting silicate metal and of the acidifying agent, for example sodium chloride in the case of the reaction of sodium silicate with hydrochloric acid or, preferably, sodium sulphate in the case of the reaction of a sodium silicate with sulfuric acid.

The concentration of electrolyte in the initial stock is (greater than 0 g / L and) less than 17 g / l, for example less than 14 g / l. The silicate concentration (expressed as SiO2) in the initial stock is (greater than 0 g / L and) less than 100 g / L; preferably, this concentration is less than 90 g / l, especially less than 85 g / l. The second step consists in adding the acidifying agent to the stock base composition described above (step (ii)). This addition, which causes a correlative drop in the pH of the reaction medium, is carried out until a pH value of at least 7, generally between 7 and 8 is reached. Once the desired value of pH, there is then a simultaneous addition (step (iii)) of acidifying agent and silicate. This simultaneous addition is generally carried out in such a way that the pH value of the reaction medium is constantly equal (within +/- 0.1) to that reached at the end of step (ii). This preparation process comprises one of the three operations (a), (b) or (c) mentioned above, that is to say: (a) after step (iii), at least one reaction medium is added to A compound A of aluminum and then or simultaneously a basic agent, the separation, implemented in the process, preferably comprising a filtration and a disintegration of the cake resulting from this filtration, said disintegration then preferably being carried out. in the presence of at least one aluminum compound B, (b) after step (iii) or in place of step (iii), a silicate and at least one compound are simultaneously added to the reaction medium; In aluminum, the separation, carried out in the process, preferably comprises a filtration and a disintegration of the cake resulting from this filtration, the disintegration then being preferably carried out in the presence of at least one compound B of the invention. aluminum, or (c) in step (iii), is added to the medium r simultaneous action of the acidifying agent, a silicate and at least one compound B of aluminum, the separation, implemented in the process, preferably comprising a filtration and a disintegration of the cake resulting from this filtration, the disintegration being then optionally carried out in the presence of at least one compound B of aluminum.

In a first variant of this preparation process (that is to say when it comprises the operation (a)), it is advantageous, after carrying out the precipitation according to steps (i), (ii) and (iii) described above, the following steps (iv) is added to the reaction medium (that is to say to the suspension or reaction mixture obtained) at least one aluminum compound A, (v) is added to the medium reaction a basic agent, preferably until a pH value of the reaction medium of between 6.5 and 10, in particular between 7.2 and 8.6, and then (vi) is added to the reaction medium the acidifying agent, preferably until a pH value of the reaction medium of between 3 and 5, in particular between 3.4 and 4.5. Step (v) may be performed simultaneously or, preferably, after step (iv).

After the simultaneous addition of step (iii), the reaction medium may be cured, this curing may for example last from 1 to 60 minutes, in particular from 3 to 30 minutes. In this first variant, it may be desirable, between step (iii) and step (iv), and in particular before said optional maturing, to add to the reaction medium an additional amount of acidifying agent. This addition is generally carried out until a pH value of the reaction medium of between 3 and 6.5, in particular between 4 and 6, is obtained. The acidifying agent used during this addition is generally identical to that used. during steps (ii), (iii) and (vi) of the first variant of the method.

Ripening of the reaction medium is usually carried out between step (v) and step (vi), for example for 2 to 60 minutes, in particular for 5 to 45 minutes. Similarly, a ripening of the reaction medium is most often carried out after step (vi), for example for 2 to 60 minutes, in particular for 5 to 30 minutes. The basic agent used in step (v) may be an ammonia solution or, preferably, a solution of sodium hydroxide (or sodium hydroxide).

In a second variant of said method (that is to say when it comprises operation (b)), after steps (i), (ii) and (iii) described above, or in place of of step (iii) described above, a step (iv) which consists in adding to the reaction medium simultaneously a silicate and at least one compound A of aluminum. Only in the case where the compound A of aluminum is sufficiently acidic (for example this may be the case when this compound A is an aluminum sulphate), it is indeed possible (but not obligatory) to substitute the step (iii) by step (iv), which in fact means that step (iii) and step (iv) then form only one step, the compound A of aluminum then playing the role of acidifying agent. The simultaneous addition of step (iv) is generally carried out in such a way that the pH value of the reaction medium is constantly equal (to within + -0.1) to that reached at the end of the step ( iii) or step (ii).

It is possible, after the simultaneous addition of step (iv), to ripen the reaction medium, which curing may for example last from 2 to 60 minutes, in particular from 5 to 30 minutes. In this second variant, it may be desirable, after step (iv), and in particular after this optional ripening, to add to the reaction medium an additional quantity of acidifying agent. This addition is generally carried out until a pH value of the reaction medium of between 3 and 6.5, in particular between 4 and 6, is obtained. The acidifying agent used during this addition is generally identical to that used. during step (ii) of the second variant of the method.

Ripening of the reaction medium is usually carried out after this addition of acidifying agent, for example for 1 to 60 minutes, in particular for 3 to 30 minutes. The aluminum compound A used in the preparation process (particularly in the first two variants mentioned) is generally an organic or inorganic salt of aluminum. As examples of organic salt, mention may be made in particular of carboxylic or polycarboxylic acid salts, such as the salts of acetic, citric, tartaric or oxalic acid.

As examples of inorganic salt, mention may in particular be made of halides and oxyhalides (such as chlorides, oxychlorides), nitrates, phosphates, sulphates and oxysulphates. In practice, compound A of aluminum may be used in the form of a solution, generally aqueous. Aluminum compound A is preferably used as aluminum compound A. In a third variant of this preparation method (that is to say when it comprises the operation (c)), it is advantageous to carry out, after carrying out the steps (i) and (ii) described above, a step (iii) which consists in adding to the reaction medium simultaneously with the acidifying agent, a silicate and at least one compound B of aluminum. This simultaneous addition is generally carried out in such a way that the pH value of the reaction medium is constantly equal (within +/- 0.1) to that reached at the end of step (ii). In this third variant, it may be desirable, after step (iii), to add to the reaction medium an additional amount of acidifying agent. This addition is generally done until a pH value of the reaction medium of between 3 and 6.9, in particular between 4 and 6.6, is obtained.

The acidifying agent used during this addition is generally identical to that used in steps (ii) and (iii). Ripening of the reaction medium is usually carried out after this addition of acidifying agent, for example for 1 to 60 minutes, in particular for 3 to 30 minutes.

The compound B of the aluminum employed in the third variant is, in general, an alkali metal aluminate, in particular potassium or, preferably, sodium. The temperature of the reaction medium is generally between 70 and 98 ° C.

According to one variant, the reaction is carried out at a constant temperature of between 75 and 96 ° C. According to another (preferred) variant, the end-of-reaction temperature is higher than the reaction start temperature: thus, the temperature at the start of the reaction is preferably maintained between 70 and 96 ° C., and then the temperature is raised. in a few minutes, preferably to a value between 80 and 98 ° C, the value at which it is maintained until the end of the reaction; the operations (a) or (b) are thus usually performed at this constant temperature value. At the end of the steps which have just been described, a silica slurry is obtained which is then separated (liquid-solid separation). In general, this separation comprises a filtration (followed by a washing if necessary) and a disintegration, said disintegration can be then (preferably in the case of the first two variants mentioned, possibly in the case of the third variant) carried out in the presence at least one aluminum compound B and, optionally, in the presence of an acidifying agent as described above (in the latter case, the compound B of the aluminum and the acidifying agent are advantageously added simultaneously ).

The disintegration operation, which can be carried out mechanically, for example by passing the filter cake in a colloidal or ball mill, notably makes it possible to lower the viscosity of the suspension to be dried (in particular to be atomized) subsequently. The aluminum compound B is usually different from the aluminum compound A mentioned above and generally consists of an alkali metal aluminate, especially potassium or, preferably, sodium aluminate. The amounts of aluminum compounds A and B used in this preparation process are such that the precipitated silica obtained has more than 0.5% by weight of aluminum, and in particular a preferred amount of aluminum as mentioned above. high. The separation carried out in this process usually comprises filtration (with washing if necessary) carried out using any suitable method, for example by means of a belt filter, a vacuum filter or, preferably, a filter. a filter press.

The precipitated silica suspension thus recovered (filter cake) is then dried.

In this preparation process, this suspension must present immediately before drying a dry matter content of at most 24% by weight, preferably at most 22% by weight. This drying can be done by any means known per se.

Preferably, the drying is done by atomization. For this purpose, any suitable type of atomizer may be used, such as a turbine, nozzle, liquid pressure or two-fluid atomizer. In general, when the filtration is carried out using a filter press, a nozzle atomizer is used, and when the filtration is carried out using a vacuum filter, a turbine atomizer is used. . When the drying is carried out using a nozzle atomizer, the precipitated silica that can then be obtained is usually in the form of substantially spherical beads. At the end of this drying, it may optionally proceed to a grinding step on the recovered product; the precipitated silica that can then be obtained is generally in the form of a powder. When the drying is carried out using a turbine atomizer, the precipitated silica that may then be obtained may be in the form of a powder.

Finally, the dried product (in particular by a turbine atomizer) or milled as indicated above may optionally be subjected to an agglomeration step, which consists, for example, of a direct compression, a wet-path granulation (that is, with the use of a binder such as water, silica suspension, etc.), extrusion or, preferably, dry compaction.

When the latter technique is used, it may be advisable, before compacting, to deaerate (operation also called pre-densification or degassing) the powdery products so as to eliminate the air included in these products. ci and ensure a more regular compaction. The precipitated silica which can then be obtained by this agglomeration step is generally in the form of granules.

The 3-acryloxypropyltriethoxysilane (or γ-acryloxypropyltriethoxysilane) used in the invention as an inorganic filler-elastomer coupling agent can be prepared by a process as described in US-A-3179612, starting from US Pat. allyl acrylate and triethoxysilane.

The aluminum-containing precipitated silica used according to the present invention as the reinforcing inorganic filler and the 3-acryloxypropyltriethoxysilane used according to the present invention as the reinforcing inorganic filler-elastomer coupling agent may be mixed together prior to their use. A first variant is that the 3-acryloxypropyltriethoxysilane is not grafted onto said precipitated silica; a second variant consists in that the 3-acryloxypropyltriethoxysilane is grafted onto said precipitated silica which will thus be "precoupled" before mixing with the elastomer composition (s).

It is possible to use all or part of the 3-acryloxypropyltriethoxysilane used according to the invention as a coupling agent in supported form (the setting is carried out prior to its use) on a solid compatible with its chemical structure. this solid support may for example be carbon black or, preferably, precipitated silica containing aluminum used according to the present invention.

The elastomer compositions in which 3-acryloxypropyltriethoxysilane is used according to the invention may contain at least one precipitated silica covering agent used as a reinforcing filler. This covering agent is capable, in known manner, of improving the processing power of the elastomer compositions in the green state. Such a coating agent may consist, for example, of an alkylalkoxysilane (in particular an alkyltriethoxysilane), a polyol, a polyether (in particular a polyethylene glycol), a polyetheramine, a primary, secondary or tertiary amine (in particular a trialkanolamine), a α, β-dihydroxylated polydimethylsiloxane or an α, β-diamine polydimethylsiloxane. This coating agent may optionally be mixed with said precipitated silica and 3-acryloxypropyltriethoxysilane prior to their use.

The elastomer compositions in which the 3-acryloxypropyltriethoxysilane and the precipitated silica described above are used according to the invention may optionally comprise at least one other inorganic filler-elastomer coupling agent, in particular a sulphurised silane. or polysulfide. Examples of such a coupling agent are: bis-triethoxysilylpropyl disulfide (abbreviated TESPD) of formula: (C2HSO) 3Si - (CH2) 3 -S2- (CH2) 3 -Si (OC2H5) 3 bis-triethoxysilylpropyl tetrasulfide (abbreviated to TESPT) of formula: (C2HSO) 3Si- (CH2) 3 -S4- (CH2) 3 -Si (OC2H5) 3 - bis-monohydroxydimethylsilylpropyl tetrasulfide of formula: (HO) (CH3) 2Si- (CH2) 3 -S4- (CH2) 3-Si (CH3) 2 (OH) - bis-monoethoxydimethylsilylpropyl disulfide (abbreviated as MESPD) of formula: (C2HSO) (CH3) 2Si- (CH2) ) 3-S2- (CH2) 3-Si (CH3) 2 (OC2H5) - bis-monoethoxydimethylsilylpropyl tetrasulfide (abbreviated as MESPT) of formula: (C2H5O) (CH3) 2Si- (CH2) 3 -S4- (CH2) ) 3-Si (CH3) 2 (OC2H5) - bis-monoethoxydimethylsilylisopropyl tetrasulfide (abbreviated to MESiPrT) of formula: (C2HSO) (CH3) 2Si-CH2-CH- (CH3) -S4 = (CH3) -CH- CH2-Si (CH3) 2 (OC2H5) However, preferably, said elastomer compositions (s) do not contain any other inorganic filler-elastomer coupling agent. 3-acryloxypropyltriethoxysilane.

The use according to the invention may optionally be carried out in the presence of a free radical initiator (for example from 0.02 to 5%, in particular from 0.05 to 0.5%, by weight relative to the amount in question. weight of elastomer (s)), that is to say of a compound (especially organic compound) susceptible, in particular following energetic activation, to generate free radicals in situ, in its surrounding environment, in this case in the elastomer (s). The initiator of free radicals is here an initiator of the type with thermal initiation, that is to say that the energy supply, for the creation of free radicals, is in thermal form. Its decomposition temperature should generally be below 180 ° C, in particular below 160 ° C. It is for example chosen from the group consisting of organic peroxides, organic hydroperoxides, azido compounds, bis (azo) compounds, peracids, peresters or a mixture of at least two of these compounds. It is in particular an organic peroxide, for example benzoyl peroxide, acetyl peroxide, lauryl peroxide, peroxide of 1,1 bis (t-butyl) -3,3,5-trimethylcyclohexane, peroxide optionally being placed on a solid support, such as calcium carbonate. However, preferably, the invention is implemented in the absence of any free radical initiator.

The elastomer composition (s) employed in the invention may advantageously not comprise other elastomers than the isoprene elastomer (s) it contains. It may optionally (non-preferred variant) comprise at least one elastomer other than isoprene. In particular, it may optionally comprise at least one isoprene elastomer (for example natural rubber) and at least one diene elastomer other than isoprene, the amount of isoprene elastomer (s) relative to the total amount of isoprene elastomer. elastomer (s) then being preferably greater than 50% (generally less than 99.5%, and for example between 70 and 99%) by weight.

The elastomer composition (s) used according to the invention generally comprises at least one isoprene elastomer (natural or synthetic) chosen from: (1) synthetic polyisoprenes obtained by homopolymerization of isoprene or 2-methylbutadiene -1.3; (2) synthetic polyisoprenes obtained by copolymerizing isoprene with one or more ethylenically unsaturated monomers selected from: (2.1) conjugated diene monomers, other than isoprene, having from 4 to 22 carbon atoms, such as for example 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-chlorobutadiene-1,3 (or chloroprene), 1-phenylbutadiene-1,3, pentadiene-1, 3, 2,4-hexadiene; (2.2) aromatic vinyl monomers having 8 to 20 carbon atoms, such as, for example, styrene, ortho-, meta- or paramethylstyrene, the commercial "vinyl-toluene" mixture, paratertiobutylstyrene, methoxystyrenes, chlorostyrenes vinylmesitylene, divinylbenzene, vinylnaphthalene; (2.3) vinyl nitrile monomers having 3 to 12 carbon atoms, such as, for example, acrylonitrile, methacrylonitrile; (2.4) acrylic ester monomers derived from acrylic acid or methacrylic acid with alkanols having from 1 to 12 carbon atoms, such as, for example, methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, methacrylate, isobutyl; (2.5) a mixture of at least two of the aforementioned monomers (2.1) to (2.4); the copolymeric polyisoprenes containing between 20 and 99% by weight of isoprenic units and between 80 and 1% by weight of diene units, aromatic vinyls, vinyl nitriles and / or acrylic esters, and consisting, for example, in poly (isoprene-butadiene) ), poly (isoprene-styrene) and poly (isoprene-butadiene-styrene); (3) natural rubber; (4) copolymers obtained by copolymerization of isobutene and isoprene, as well as the halogenated, in particular chlorinated or brominated, versions of these copolymers; (5) a mixture of at least two of the aforementioned elastomers (1) to (4); (6) a mixture containing more than 50% (preferably less than 99.5%, and for example 70-99%) by weight of the aforementioned elastomer (1) or (3) and less than 50% (preferably more than 0.5%, and for example between 1 and 30% by weight of one or more diene elastomers other than isoprenic.

By diene elastomer other than isoprene, is meant in a manner known per se including: homopolymers obtained by polymerization of one of the conjugated diene monomers defined above in (2.1), such as polybutadiene and polychloroprene; copolymers obtained by copolymerization of at least two of the abovementioned conjugated dienes (2.1) with one another or by copolymerization of one or more of the abovementioned conjugated dienes (2.1) with one or more unsaturated monomers mentioned above (2.2), (2.3) and / or or (2.4), such as poly (butadiene-styrene) and poly (butadiene-acrylonitrile); ternary copolymers obtained by copolymerization of ethylene, of an α-olefin having from 3 to 6 carbon atoms with a non-conjugated diene monomer having from 6 to 12 carbon atoms, for example elastomers obtained from ethylene propylene with a non-conjugated diene monomer of the aforementioned type such as in particular 1,4-hexadiene, héthylidénenorbornène, dicyclopentadiène (EPDM elastomer). Preferably, the elastomer composition (s) comprises at least one isoprene elastomer chosen from: (1) homopolymeric synthetic polyisoprenes; (2) the synthetic polyisoprenes copolymers consisting of poly (isoprene-butadiene), poly (isoprene-styrene) and poly (isoprene-butadiene-styrene); (3) natural rubber; (4) butyl rubber; (5) a mixture of at least two of the aforementioned elastomers (1) to (4); (6) a mixture containing more than 50% (preferably less than 99.5%, and for example 70-99%) by weight of the aforementioned elastomer (1) or (3) and less than 50% (preferably more than 0.5%, and for example from 1 to 30% by weight of non-isoprene diene elastomer consisting of polybutadiene, polychloroprene, polybutadiene-styrene, polybutadiene-acrylonitrile or a terpolymer (ethylene - propylene - nonconjugated monomeric diene). More preferentially, the elastomer composition (s) comprises at least one isoprene elastomer chosen from: (1) homopolymeric synthetic polyisoprenes; (3) natural rubber; (5) a mixture of the aforementioned elastomers (1) and (3); (6) a mixture containing more than 50% (preferably less than 99.5%, and for example 70-99%) by weight of the aforementioned elastomer (1) or (3) and less than 50% (preferably more than 0.5%, for example from 1 to 30% by weight of diene elastomer other than isoprene, consisting of polybutadiene or polybutadiene-styrene. According to a very preferred variant of the invention, the elastomer composition (s) comprises as isoprene elastomer at least natural rubber, or even only natural rubber. According to an even more preferred variant, the elastomer composition (s) comprises as elastomer (s) only natural rubber.

In general, the elastomer composition (s) used according to the invention further comprises all or part of the other constituents and auxiliary additives usually employed in the field of elastomeric compositions. Thus, generally, it comprises at least one compound selected from vulcanizing agents (e.g., sulfur or a sulfur donor compound (such as a thiuram derivative)), vulcanization accelerators (e.g., a guanidine derivative or a thiazole derivative), vulcanization activators (for example stearic acid, zinc stearate and zinc oxide, which may optionally be introduced in a fractional manner during the preparation of the composition), black of carbon, protective agents (especially antioxidants and / or antiozonants, such as for example N-phenyl-N '- (1,3-dimethyl-butyl) -p-phenylenediamine), antireversions (such as for example hexamethylene-1,6-bis (thiosulfate), 1,3-bis (citraconimidomethyl) benzene), plasticizers.

The combined use according to the invention of the aluminum-containing precipitated silica described in the preceding discussion and of 3-acryloxypropyltriethoxysilane can be carried out more particularly in shoe soles, floor coverings, barriers to gas, flame retardant materials, ropeway rollers, appliance joints, liquid or gas line joints, braking system joints, hoses, ducts (especially cable ducts) ), cables, engine mounts, conveyor belts, transmission belts or, preferably, tires (particularly tire treads), advantageously in tires for heavy goods vehicles, in particular for trucks.

The elastomer composition (s) obtained according to the use according to the invention contains an effective amount of 3-acryloxypropyltriethoxysilane. More particularly, the elastomer compositions resulting from the invention may comprise (parts by weight), per 100 parts of isoprene elastomer (s): at 200 parts, in particular 20 to 150 parts, especially 30 to 110 parts. 10 parts, for example 30 to 75 parts, of precipitated silica containing aluminum as described above and used as reinforcing inorganic filler; 1 to 20 parts, in particular 2 to 20 parts, especially 2 to 12 parts, for example 2 to 10 parts, of 3-acryloxypropyltriethoxysilane used as reinforcing inorganic filler-elastomer coupling agent.

Preferably, the amount of 3-acryloxypropyltriethoxysilane used, chosen especially in the abovementioned ranges, is determined so that it generally represents 1 to 20%, in particular 2 to 15%, for example 4 to 12%, by weight relative to the amount used of the precipitated silica containing aluminum as described above.

In general, the total amounts of coupling agents + optional coating agent are identical to those mentioned above when using, in addition to the coupling agent (3-acryloxypropyltriethoxysilane) used according to the invention. another coupling agent (especially sulphide or polysulfide) and / or a covering agent.

The second subject of the present invention is the elastomer compositions (s) described above, and therefore comprising: at least one isoprene elastomer, at least one reinforcing inorganic filler, at least one inorganic filler-elastomer coupling agent; , characterized in that said reinforcing inorganic filler and said inorganic filler - elastomer coupling agent are as defined above according to the first subject of the invention, that is to say that said reinforcing inorganic filler is precipitated silica containing aluminum as described in the above discussion and said inorganic filler-elastomer coupling agent is 3-acryloxypropyltriethoxysilane. All that has been previously described in the context of the use according to the first subject of the invention applies to these elastomer compositions (s).

The elastomer compositions according to the invention may be prepared according to any conventional two-phase procedure. A first phase (called non-productive) is a thermomechanical work phase at high temperature. It is followed by a second mechanical working phase (so-called productive) at temperatures generally below 110 ° C. in which the vulcanization system is introduced.

The invention, taken in its second subject, relates to elastomer compositions (s) both in the raw state (that is to say before cooking) and in the cooked state (that is to say, before cooking). - say after crosslinking or vulcanization).

The elastomer compositions according to the invention can be used to manufacture finished or semi-finished articles comprising said compositions. The present invention thus has for third object articles comprising at least one elastomer composition (s) as defined above, these articles consisting of shoe soles, floor coverings, gas barriers, materials and the like. flame retardants, ropeway rollers, appliance gaskets, liquid or gas line joints, braking system joints, hoses, ducts (especially cable ducts), cables , engine supports, conveyor belts, transmission belts, or, preferably, tires (especially tire treads), advantageously tires for heavy goods vehicles, in particular for trucks. Finally, the fourth subject of the invention is the compositions (or kits) comprising at least one reinforcing inorganic filler for elastomer and at least one inorganic filler-elastomer coupling agent, characterized in that said reinforcing inorganic filler and said coupling agent inorganic filler - elastomer are as defined above according to the first subject of the invention, that is to say that said reinforcing inorganic filler is precipitated silica containing aluminum as described in the above discussion and said inorganic filler-elastomer coupling agent is 3-acryloxypropyltriethoxysilane. All that has been mentioned previously in the context of the use according to the first subject of the invention or in the context of the second or third subject of the invention applies to these compositions (or kits) and their uses. . In particular, these compositions may further comprise at least one covering agent for said precipitated silica used as a reinforcing filler. Similarly, these compositions find a particularly advantageous application in elastomer compositions (s) comprising at least one isoprene elastomer, especially in those comprising (for example as sole elastomer) natural rubber. A preferred application lies in their use in tires (especially tire treads), advantageously in tires for heavy goods vehicles, in particular for trucks.

The following examples illustrate the invention without, however, limiting its scope.

EXAMPLES

EXAMPLE 1 (comparative)

In a stainless steel reactor equipped with a propeller stirring system and external electric heating, are introduced: - 29.335 kg of water - 509 g of Na 2 SO 4 - 17.3 kg of aqueous sodium silicate, having a weight ratio SiO2 / Na2O equal to 3.47 and a density at 20 ° C equal to 1.230. The silicate concentration (expressed as SiO2) in the initial stock is then 76.5 g / l.

The mixture is then heated to a temperature of 83 ° C while maintaining stirring. 17470 g of dilute sulfuric acid of density at 20 ° C. equal to 1.050 are then introduced in order to obtain in the reaction medium a pH value (measured at its temperature) equal to 8. The temperature of the reaction is 83 ° C. ° C during the first 20 minutes; it is then increased from 83 to 92 ° C. in approximately 30 minutes, which corresponds to the end of the acidification. 4120 g of aqueous sodium silicate of the type described above and 4830 g of sulfuric acid, also of the type described above, are then introduced together into the reaction medium, this simultaneous introduction of acid and silicate being carried out in a manner such that the pH of the reaction medium, during the period of introduction, is constantly equal to 8.0 ± 0.1. After introduction of all of this silicate, dilute acid is continued for 7 minutes to bring the pH of the reaction medium to a value of 5.2. After this introduction of acid, the reaction mixture obtained is stirred for 5 minutes.

The total reaction time is 85 minutes. A slurry or suspension of precipitated silica is thus obtained which is then filtered and washed by means of a plane filter. The cake obtained is then fluidized by mechanical and chemical action (simultaneous addition of sulfuric acid and a quantity of sodium aluminate corresponding to a weight ratio AI / SiO 2 of 0.3%). After this disintegration operation, the resulting slurry, with a pH equal to 6.5 and a loss on ignition equal to 85.5% (thus a solids content of 14.5% by weight), is spray-dried.

The characteristics of the silica obtained Al in powder form are then as follows: CTAB specific surface area 163 m2 / g - BET specific surface area 164 m2 / g - aluminum content by weight 0.26% - V2N1 ratio 51% - pH 6, Al silica is subjected to the disagglomeration test as defined previously in the description.

After deagglomeration with ultrasound, it has a median diameter (050) of 2.9 .mu.m.

EXAMPLE 2 In a stainless steel reactor equipped with a propeller stirring system and external electric heating, the following are introduced: 29.335 kg of water 509 g of Na 2 SO 4 17.3 kg of aqueous sodium silicate , having a weight ratio of SiO 2 / Na 2 O equal to 3.47 and a density at 20 ° C. of 1.230. The silicate concentration (expressed as SiO2) in the initial stock is then 76.5 g / l. The mixture is then heated to a temperature of 83 ° C while maintaining stirring. 18050 g of dilute sulfuric acid having a density at 20 ° C. of 1.050 is then introduced in order to obtain a pH value (measured at its temperature) of 8 in the reaction medium. The temperature of the reaction is 83 ° C for the first 20 minutes; it is then increased from 83 to 92 ° C. in approximately 30 minutes, which corresponds to the end of the acidification. 1850 g of aqueous sodium silicate of the type described above and 2230 g of sulfuric acid, also of the type described above, are then introduced together into the reaction medium, this simultaneous introduction of acid and silicate being carried out such that the pH of the reaction medium, during the period of introduction, is constantly equal to 8.0 ± 0.1. This step is followed by a simultaneous addition of 4520 g of an aluminum sulphate solution with a density of 20 ° C equal to 1.056 and of 2260 g of aqueous sodium silicate of the type described above so that the pH of the reaction medium, during the period of introduction, is constantly equal to 8.0 ± 0.1. After this joint addition, sulfuric acid of the type described above is introduced into the reaction medium for 5 minutes in order to bring the pH of the reaction medium to a value of 5.2. After this introduction of acid, the reaction mixture obtained is stirred for 5 minutes. The total reaction time is 85 minutes.

A slurry or suspension of precipitated silica is thus obtained which is then filtered and washed by means of a plane filter. The cake obtained is then fluidized by mechanical and chemical action (simultaneous addition of sulfuric acid and a quantity of sodium aluminate corresponding to a weight ratio AI / SiO 2 of 0.3%). After this disintegration operation, the resulting slurry, with a pH equal to 6.5 and a loss on ignition equal to 86.0% (thus a solids content of 14.0% by weight), is spray-dried. The characteristics of the silica obtained P1 in powder form are then as follows: The silica P1 is subjected to the deagglomeration test as defined previously in the description. After deagglomeration with ultrasound, it has a median diameter (o 0) of 2.5 μm. EXAMPLE 3

In a stainless steel reactor equipped with a propeller stirring system and external electric heating, are introduced: - 29.335 kg of water 30 - 509 g of Na 2 SO 4 - 17.3 kg of aqueous sodium silicate, having a weight ratio SiO2 / Na2O equal to 3.44 and a density at 20 ° C equal to 1.232. - CTAB specific surface area 161 m2 / g - BET specific surface area 161 m2 / g - aluminum content by weight 1.2% - V2 / V1 ratio 45% -PH 7.4 The silicate concentration (expressed as SiO2) in the foot of initial tank is then 76.5 g / L. The mixture is then heated to a temperature of 83 ° C while maintaining stirring. 17180 g of dilute sulfuric acid of density at 20 ° C. equal to 1.050 are then introduced in order to obtain in the reaction medium a pH value (measured at its temperature) equal to 8. The temperature of the reaction is 83 ° C. ° C during the first 20 minutes; it is then increased from 83 to 92 ° C. in approximately 30 minutes, which corresponds to the end of the acidification. 4100 g of aqueous sodium silicate of the type described above and 7540 g of an aluminum sulphate solution having a density of 20 ° C. of 1.056 are then added together in the reaction medium, this simultaneous introduction of aluminum sulphate. (acid) and silicate being carried out in such a way that the pH of the reaction medium, during the period of introduction, is constantly equal to 8.0 ± 0.1. After this joint addition, sulfuric acid of the type described above is introduced into the reaction medium for 5 minutes in order to bring the pH of the reaction medium to a value of 5.2. After this introduction of acid, the reaction mixture obtained is stirred for 5 minutes. The total reaction time is 85 minutes.

A slurry or suspension of precipitated silica is thus obtained which is then filtered and washed by means of a plane filter. The cake obtained is then fluidized by mechanical and chemical action (simultaneous addition of sulfuric acid and a quantity of sodium aluminate corresponding to a weight ratio AI / SiO 2 of 0.3%). After this disintegration operation, the resulting slurry, with a pH equal to 6.5 and a loss on ignition equal to 85.0% (thus a solids content of 15.0% by weight), is spray-dried. CTAB specific surface area 158 m2 / g BET specific surface area 178 m2 / g 1.5% aluminum weight ratio V2N1 ratio 47% The characteristics of the silica obtained P2 in the form of a powder are then as follows: Silica P2 is subjected to the disagglomeration test as defined above in the description. After deagglomeration with ultrasound, it has a median diameter (050) of 2.9 .mu.m.

EXAMPLE 4

In a stainless steel reactor equipped with a propeller stirring system and external electric heating, the following are introduced: - 29.35 kg of water - 509 g of Na 2 SO 4 - 17.2 kg of aqueous sodium silicate having a SiO 2 / Na 2 O weight ratio of 3.44 and a density at 20 ° C of 1.230.

The silicate concentration (expressed as SiO2) in the initial stock is then 76.5 g / l. The mixture is then heated to a temperature of 83 ° C while maintaining stirring. It then introduces 16900 g of dilute sulfuric acid density at 20 ° C equal to 1.050 to obtain in the reaction medium a pH value (measured at its temperature) equal to 8. The temperature of the reaction is 83 ° C during the first 20 minutes; it is then increased from 83 to 92 ° C. in approximately 30 minutes, which corresponds to the end of the acidification. 4100 g of aqueous sodium silicate of the type described above are then introduced together into the reaction medium, 2150 g of dilute sodium aluminate with a density at 20 ° C. of 1,237 and 6,000 g of sulfuric acid of the type described above. before, this simultaneous introduction of acid, of silicate and of sodium aluminate being carried out in such a way that the pH of the reaction medium, during the period of introduction, is constantly equal to 8.0 ± 0.1. After this joint addition, sulfuric acid of the type described above is introduced into the reaction medium for 3.5 minutes so as to bring the pH of the reaction medium to a value equal to 6.5. After this introduction of acid, the reaction mixture obtained is stirred for 5 minutes.

The total reaction time is 87 minutes. A slurry or suspension of precipitated silica is thus obtained which is then filtered and washed by means of a plane filter. The cake obtained is then fluidified by mechanical action. After this disintegration operation, the resulting slurry, with a loss on ignition equal to 84.5% (thus a solids content of 15.5% by weight), is spray-dried. The characteristics of the silica obtained P3 in powder form are then as follows. The silica P3 is subjected to the deagglomeration test as defined previously in the description. After deagglomeration with ultrasound, it has a median diameter (050) of 2.9 Nm. EXAMPLE 5

This example illustrates the use and behavior of the precipitated silica containing aluminum prepared in Example 3 with 3-acryloxypropyltriethoxysilane in an elastomeric composition. In an internal Haake-type mixer, elastomeric compositions are prepared whose constitution, expressed in part by weight per 100 parts of elastomers (phr), is given in Table I below. CTAB surface area 135 m 2 / g - BET specific surface area 160 m 2 / g - aluminum content by weight 2.7% - V2N1 ratio 40% - pH 6.7 Table 1: Formulations used for mixtures Compositions Control 1 Reference 1 Composition 1 NR (1) 100 100 100 Silica 1 (2) 50 50 - Silica 2 (3) - - 50 Coupling agent 1 (4) 4.0 - - Coupling agent 2 (5) - 5.7 5, 7 ZnO 3.0 3.0 3.0 Stearic acid 2.5 2.5 2.5 Antioxidant 1 (6) 1.5 1.5 1.5 Antioxidant 2 (7) 1.0 1.0 1.0 Carbon black (N330) 3.0 3.0 3.0 CBS (8) 1.5 1.5 1.5 TBzTD (9) 0.2 0.2 0.2 DPG (10) 0.5 0, 5 0.5 Sulfur 1.5 1.8 1.8 (1) SMR 5 L natural rubber (supplied by Safic-Alcan) (2) Silica Al (Example 1) (3) Silica P2 (Example 3) ( 4) TESPT (Z-6940 from Dow Corning) (5) 3-acryloxypropyltriethoxysilane (6) N-1,3-dimethylbutyl-N-phenyl-para-phenylenediamine (Santoflex 6-PPD from Flexsys) ( 7) 2,2,4-trimethyl-1H-quinoline (Permanax TQ from Flexsys) (8) N-cyclohexyl-2-benzot hiazyl-sulfenamide (Rhenogran CBS-80 from RheinChemie) (9) Tetrabenzylthiuram disulfide (Rhenogran TBzTD-70 from RheinChemie) (10) Diphenylguanidine (Rhenogran DPG-80 from RheinChemie) Process for the preparation of elastomeric compositions

The process for preparing the compositions is conducted in two successive preparation phases. A first phase consists in a thermomechanical work phase at high temperature. It is followed by a second phase of mechanical work at temperatures below 110 oc; this phase allows the introduction of the vulcanization system. The first phase is carried out in a Haake type internal mixer (capacity of 300 mL). The fill factor is 0.75. The initial temperature and the speed of the rotors are fixed each time so as to reach mixing drop temperatures of about 140-160 ° C. The first phase is decomposed here in two passes. It allows to incorporate, in a first pass, the elastomer (natural rubber), then the reinforcing inorganic filler consisting of silica (fractional introduction) with the coupling agent and stearic acid; the duration of this pass is between 4 and 10 minutes. After cooling the mixture (temperature below 100 ° C.), a second pass makes it possible to incorporate the zinc oxide and the protective / antioxidant agents (6-PPD in particular); the duration of this pass is between 2 and 5 minutes. After cooling the mixture (temperature below 100 ° C), the second phase allows the introduction of the vulcanization system (sulfur and accelerators, such as CBS). It is carried out on a roll mill, preheated to 50 ° C. The duration of this phase is between 2 and 6 minutes.

Each final mixture is then calendered in the form of plates 2-3 mm thick. On these so-called raw mixtures obtained, an evaluation of their rheological properties makes it possible to optimize the duration and the vulcanization temperature. Then, the mechanical and dynamic properties of the optimum vulcanized mixtures are measured.

Rheological properties - Viscosity of raw mixtures

The Mooney consistency is measured on the compositions in the uncured state at 100 ° C. by means of a MV 2000 rheometer according to the NF ISO 289 standard.

The value of the torque read after 4 minutes after preheating for 1 minute (Mooney Large (1 + 4) at 100 ° C) is shown in Table II.

Table II Compositions Control 1 Reference 1 Composition 1 ML (1 + 4) - 100 ° C. 62 76 71 It can be seen that the composition resulting from the invention (composition 1) has a satisfactory viscosity at flood, and especially lower than that of the reference composition (reference 1) containing the same coupling agent but associated with a precipitated silica having an aluminum content that does not conform to that required by the invention. - Rheometry of the compositions

The measurements are performed on the compositions in the green state. The results relating to the rheology test, which is conducted at 150 ° C. by means of a Monsanto ODR rheometer according to the standard NF ISO 3417, are given in Table III. According to this test, the test composition is placed in the test chamber. controlled test at a temperature of 150 ° C for 30 minutes, and the resistive torque opposed by the composition is measured at a low amplitude oscillation (3 °) of a biconical rotor included in the test chamber, the composition completely filling the chamber in question. From the curve of variation of the torque as a function of time, one determines: the minimum torque (Cmin), which reflects the viscosity of the composition at the temperature considered; - the maximum torque (Cmax); - the delta torque (AC = Cmax - Cmin); The time T98 necessary to obtain a state of vulcanization corresponding to 98% of the complete vulcanization (this time is taken as optimum vulcanization); the roasting time TS2 corresponding to the time required to have a rise of 2 points above the minimum torque at the temperature in question (150 ° C.) and reflecting the time during which it is possible to use the raw mixtures with this temperature without initiation of vulcanization (the mixture cures from TS2). The results obtained are shown in Table III.

Table III Compositions Control 1 Reference 1 Composition 1 Cmin (dNm) 12.8 13.5 13.0 Cmax (dNm) 83.5 81.4 76.5 Delta couple (dNm) 70.7 67 , 9 63.5 TS2 (min) 5.55 6.65 6.85 T98 (min) 10.0 10.3 9.98 It is found that the composition resulting from the invention (composition 1) has a very satisfactory set rheological properties, and in particular with respect to the reference composition (reference 1) containing the same coupling agent but associated with a precipitated silica having an aluminum content not in accordance with that required by the invention. In particular, it has values of minimum and maximum couples lower than those of the reference composition (reference 1), and neighboring (Cmin) or even lower (Cmax) than those of the control composition (control 1), which translated a greater ease of use of the mixture prepared. And especially the composition 1 resulting from the invention (composition 1) has a good vulcanization kinetics (TS2, T98), especially with respect to the reference composition (reference 1) and even compared to the control composition (control 1) , without penalizing the viscosity of the raw mixture (illustrated in particular by the minimum torque).

Mechanical properties of vulcanizates

The measurements are carried out on the optimally vulcanized compositions (T98) for a temperature of 150 ° C.

The uniaxial tensile tests are carried out in accordance with the NF ISO 37 standard with type H2 specimens at a speed of 500 mm / min on an INSTRON 5564 device. The x% modules correspond to the stress measured at x% deformation. in tensile and are expressed, as the breaking strength in MPa. It is possible to determine a reinforcement index (I.R.) which is equal to the ratio between the 300% deformation modulus and the 100% deformation modulus. The measured properties are collated in Table IV.

Table IV Compositions Control 1 Reference 1 Composition 1 Module 10% (Mpa) 0.73 0.72 0.67 Module 100% (Mpa) 3.70 3.80 3.53 Module 300% (Mpa) 16.1 20, 19.4 Breaking strength (Mpa) 27.3 28.1 28.4 IR 4.35 5.47 5.50 It is found that the composition resulting from the invention (composition 1) has a very good compromise of mechanical properties. at least comparable to, or better than, that obtained with the reference composition (reference 1) or even the control composition (control 1).

Dynamic properties of vulcanizates

Dynamic properties are measured on a viscoanalyzer (Metravib VA3000) according to ASTM D5992. The loss factor (tan b) and complex dynamic compression (E *) values are recorded on vulcanized samples (cylindrical specimen of section 95 mm 2 and height 14 mm). The sample is initially subjected to a predeformation of 10%, then to a sinusoidal deformation in alternating compression of +/- 2%. The measurements are carried out at 60 ° C. and at a frequency of 10 Hz. The results, presented in Table V, are the complex compressive modulus (E * -60 ° C.-10 Hz) and the loss factor (tan 6). - 60 ° C - 10 Hz). The values of the loss factor (tan b) and elastic modulus amplitude in dynamic shear (AG ') are recorded on vulcanized samples (parallelepipedal specimen of section 8 mm 2 and height 7 mm). The sample is subjected to an alternating double shear sinusoidal deformation at a temperature of 40 ° C. and at a frequency of 10 Hz. The amplitude-deformation sweep processes are carried out in a round-trip cycle, ranging from 0.degree. 1 to 50% then return 50 to 0.1%. The results, presented in Table IV, are derived from the amplitude sweep of the return strains and relate to the maximum value of the loss factor (tan b max return - 40 ° C - 10 Hz) as well as the amplitude of the elastic modulus ( AG '- 40 ° C - 10 Hz) between the values at 0.1% and 50% deformation (Payne effect).

Table V Compositions Control 1 Reference 1 Composition 1 E * - 60 ° C - 10 Hz (MPa) 6.24 6.33 5.81 Tang b - 60 ° C - 10 Hz 0.056 0.047 0.054 AG '- 60 ° C - 10 Hz (MPa) 1.76 1.03 0.71 Tang b max back-0.100 0.074 0.067 60 ° C-10 Hz The composition resulting from the invention (composition 1) has very good dynamic properties (hysteretic properties at 60 ° C. C), in particular with respect to the reference composition (reference 1) and also with respect to the control composition (control 1). It can be seen from the results of Tables II to v that the composition resulting from the invention (composition 1) has a very good compromise of properties.

EXAMPLE 6

This example illustrates the use and behavior of the aluminum-containing precipitated silica prepared in Example 2 with 3-acryloxypropyltriethoxysilane in an elastomeric composition. In an internal Haake-type mixer, elastomeric compositions are prepared whose constitution, expressed in part by weight per 100 parts of elastomers (phr), is given in Table VI below.

Table VI: Formulations used for mixtures Compositions Control 2 Reference 2 Composition 2 NR (1) 100 100 100 Silica 1 (2) - 50 - Silica 2 (3) 50 - 50 Coupling agent 1 (4) 4.0 - - Coupling agent 2 (5) - 5.7 5.7 ZnO 3.0 3.0 3.0 Stearic acid 2.5 2.5 2.5 Antioxidant 1 (6) 1.5 1.5 1.5 Antioxidant 2 (7) 1.0 1.0 1.0 Carbon black (N330) 3.0 3.0 3.0 CBS (8) 1.5 1.5 1.5 TBzTD (9) 0.2 0 , 2 0.2 DPG (10) 1.5 1.5 1.5 Sulfur 0.5 0.5 0.5 (1) Natural rubber SMR - CV60 (supplied by Safic-Alcan) (2) Silica Al (Example 1) (3) Silica P1 (Example 2) (4) TESPT (Z-6940 from Dow Corning Company) (5) 3-acryloxypropyltriethoxysilane (6) N-1,3-dimethylbutyl-N-phenyl -para-phenylenediamine (Santoflex 6-PPD from Flexsys) (7) 2,2,4-trimethyl-1H-quinoline (Permanax TQ from Flexsys) (8) N-cyclohexyl-2-benzothiazyl-sulfenamide ( Rhenogran CBS-80 from RheinChemie) (9) Tetrabenzylthiuram disulfide (Rhenogran TBzTD-70 RheinChemie) (10) Diphenylguanidine (Rhenogran DPG-80 from RheinChemie)

Process for the Preparation of the Elastomeric Compositions The process for the preparation of the compositions is carried out in two successive preparation phases. A first phase consists in a thermomechanical work phase at high temperature. It is followed by a second phase of mechanical work at temperatures below 110 ° C; this phase allows the introduction of the vulcanization system.

The first phase is carried out in a Haake type internal mixer (capacity of 300 mL). The fill factor is 0.75. The initial temperature and the speed of the rotors are fixed each time so as to reach mixing drop temperatures of about 140-160 ° C. The first phase is decomposed here in two passes.

It allows to incorporate, in a first pass, the elastomer (natural rubber), then the reinforcing inorganic filler consisting of silica (fractional introduction) with the coupling agent and stearic acid; the duration of this pass is between 4 and 10 minutes. After cooling the mixture (temperature below 100 ° C.), a second pass makes it possible to incorporate the zinc oxide and the protective / antioxidant agents (6-PPD in particular); the duration of this pass is between 2 and 5 minutes.

After cooling the mixture (temperature below 100 ° C), the second phase allows the introduction of the vulcanization system (sulfur and accelerators, such as CBS). It is carried out on a roll mill, preheated to 50 ° C. The duration of this phase is between 2 and 6 minutes.

Each final mixture is then calendered in the form of plates 2-3 mm thick. On these so-called raw mixtures obtained, an evaluation of their rheological properties makes it possible to optimize the duration and the vulcanization temperature. Then, the mechanical and dynamic properties of the optimum vulcanized mixtures are measured.

Rheological properties

Viscosity of the raw mixtures The Mooney consistency is measured as in Example 5. The value of the torque read after 4 minutes after preheating for one minute (Mooney Large (1 + 4) at 100 ° C.) is indicated in FIG. Table VII.

Table VII Compositions Control 2 Reference 2 Composition 2 ML (1 + 4) - 100 ° C. 56 53 50 It is found that the composition resulting from the invention (composition 2) has a very satisfactory flood viscosity, which is lower than that of the reference composition (reference 2) containing the same coupling agent but associated with a precipitated silica having an aluminum content which is not in accordance with that required by the invention, or that of the control composition (control 2) containing the same precipitated silica but associated with another coupling agent. 30 - Rheometry of the compositions

The measurements are carried out as in Example 5. The results obtained are shown in Table VIII. Table VIII Compositions Control 2 Reference 2 Composition 2 Cmin (dNm) 13.0 11.2 10.8 Cmax (dNm) 70.1 75.9 72.8 Delta torque (dNm) 57.1 64 , 622 TS2 (min) 5.68 7.10 7.77 It is found that the composition resulting from the invention (composition 1) has a very satisfactory set of rheological properties, and especially with respect to the composition of the composition. reference (reference 2) containing the same coupling agent but associated with a precipitated silica having an aluminum content not in accordance with that required by the invention. In particular, it has lower minimum and maximum torque values than those of the reference composition (reference 2), or even lower (Cmin) than those of the control composition (control 2), which reflects a great facility implementation of the prepared mixture. The composition 1 resulting from the invention (composition 2) has a good vulcanization kinetics (TS2), especially with respect to the reference composition (reference 2) and with respect to the control composition (control 2), and this without penalize the viscosity of the raw mixture (illustrated in particular by the minimum torque).

Mechanical properties of vulcanizates

The measurements are carried out as in Example 5. The measured properties are collated in Table IX. 415 Table IX Compositions Control 2 Reference 2 Composition 2 Module 10% (Mpa) 0.58 0.64 0.56 Module 100% (Mpa) 2.83 3.18 2.55 Module 300% (Mpa) 13.7 18 , 7 15.3 Breaking strength (Mpa) 28.7 28.8 29.3 IR 4.85 5.88 5.99 It is found that the composition resulting from the invention (composition 2) has a very good compromise of properties mechanical, at least comparable to, or better than, that obtained with the reference composition (reference 2) or the control composition (control 2).

Dynamic properties of vulcanizates

The dynamic properties are measured as in Example 5. The results are shown in Table X.

Table X Compositions Control 2 Reference 2 Composition 2 E * - 60 ° C - 10 Hz (MPa) 5.76 5.38 5.06 Tang b - 60 ° C - 10 Hz 0.077 0.054 0.054 The composition resulting from the invention ( composition 2) has very good dynamic properties (hysteretic properties at 60 ° C.), especially with respect to the reference composition (reference 2) and to the control composition (control 2).

It can be seen from the results of Tables VII to X that the composition resulting from the invention (Composition 2) has a very good compromise of properties. 15

Claims (41)

CLAIMS1- Use in an elastomer composition (s), comprising at least one isoprene elastomer: a precipitated silica containing aluminum, as reinforcing inorganic filler, the aluminum content of said precipitated silica being greater than 0, 5% by weight, with 3-acryloxypropyltriethoxysilane, as an inorganic filler-elastomer coupling agent. 2- Use according to claim 1, characterized in that said precipitated silica has an aluminum content of at most 7.0% by weight, preferably at most 5.0% by weight, in particular at most 3.5% by weight. 3- Use according to one of claims 1 and 2, characterized in that said precipitated silica has an aluminum content of between 0.75 and 4.0% by weight, preferably between 0.8 and 3.5%, in particular between 0.9 and 3.2% by weight. 4- Use according to one of claims 1 to 3, characterized in that the precipitated silica is highly dispersible. 5- Use according to one of claims 1 to 4, characterized in that said precipitated silica has: - a CTAB specific surface area of between 70 and 240 m2 / g, and - a BET specific surface area of between 70 and 240 m2 / boy Wut. 6. Use according to one of claims 1 to 5, characterized in that said precipitated silica has a median diameter (050), after ultrasound disagglomeration, less than 5 pm, in particular less than 4 pm, for example lower à3pm. 7- Use according to one of claims 1 to 6, characterized in that said precipitated silica has an ultrasonic deagglomeration factor (FD) greater than 4.5 ml, in particular greater than 10 ml. 8- Use according to one of claims 1 to 7, characterized in that said precipitated silica has a DOP oil intake of less than 300 ml / 100g. 9- Use according to one of claims 1 to 8, characterized in that said precipitated silica has a porous distribution such that the pore volume constituted by the pores whose diameter is between 175 and 275 A represents less than 50% of the porous volume constituted by pores with diameters less than or equal to 400 A. 10- Use according to one of claims 1 to 9, characterized in that said precipitated silica is obtained by a process comprising the precipitation reaction between a silicate and an acidifying agent whereby a precipitated silica suspension is obtained, then the separation and drying of this suspension, in which: - the precipitation reaction is carried out in the following manner: (i) an initial stock having a silicate and an electrolyte is formed, the silicate concentration (expressed as SiO2) in said initial base stock being less than 100 g / L and the electrolyte concentration in said initial stock being less than 17 g / L, (ii) the acidifying agent is added to said stock foot up to to obtain a pH value of the reaction medium of at least 7, (iii) the acidifying agent and a silicate are added to the reaction medium simultaneously, - a suspension having a material content of at most 24% by weight, said process comprising one of the following three operations (a), (b) or (c): (a) adding, after step (iii), to the reaction medium at least an aluminum compound and then or simultaneously a basic agent, (b) after step (iii) or in place of step (iii), a silicate and minus one aluminum compound, (c) step (iii) is carried out by simultaneously adding to the reaction medium acidifying agent, a silicate and at least one aluminum compound. 11- Use according to one of claims 1 to 10, characterized in that the amount of 3-acryloxypropyltriethoxysilane used represents from 1 to 20%, in particular from 2 to 15%, relative to the amount of said silica used rushed. 10 12- Use according to one of claims 1 to 11, characterized in that said precipitated silica and 3-acryloxypropyltriethoxysilane are premixed together. 13- Use according to one of claims 1 to 12, characterized in that said elastomer composition (s) further comprises at least one covering agent of said precipitated silica, optionally premixed with said precipitated silica and 3 -acryloxy-propyltriethoxysilane. 14. Use according to one of claims 1 to 13, characterized in that said elastomer composition (s) does not comprise another inorganic filler - elastomer coupling agent. 15- Use according to one of claims 1 to 14, in the absence of free radical initiator. 16- Use according to one of claims 1 to 15, characterized in that said elastomer composition (s) does not include other elastomers that said (s) elastomer (s) isoprene (s). 30 17- Use according to one of claims 1 to 15, characterized in that said elastomer composition (s) comprises at least one isoprene elastomer and at least one diene elastomer other than isoprene, the amount of elastomer (s) Isoprene (s) relative to the total amount of elastomer (s) being preferably greater than 50% by weight. 18- Use according to one of claims 1 to 17, characterized in that said elastomer composition (s) comprises at least one isoprene elastomer chosen from: (1) synthetic polyisoprenes obtained by homopolymerization of isoprene or 2-methyl-1,3-butadiene; (2) synthetic polyisoprenes obtained by copolymerizing isoprene with one or more ethylenically unsaturated monomers selected from: (2.1) conjugated diene monomers, other than isoprene, having from 4 to 22 carbon atoms; (2.2) vinyl aromatic monomers having 8 to 20 carbon atoms; (2.3) vinyl nitrile monomers having from 3 to 12 carbon atoms; (2.4) acrylic ester monomers derived from acrylic acid or methacrylic acid with alkanols having from 1 to 12 carbon atoms; (2.5) a mixture of at least two of the aforementioned monomers (2.1) to (2.4); the copolymeric polyisoprenes containing between 20 and 99% by weight of isoprenic units and between 80 and 1% by weight of diene units, aromatic vinyls, vinyl nitriles and / or acrylic esters; (3) natural rubber; (4) copolymers obtained by copolymerization of isobutene and isoprene, as well as the halogenated versions of these copolymers; (5) a mixture of at least two of the aforementioned elastomers (1) to (4); (6) a mixture containing more than 50% by weight of the aforementioned elastomer (1) or (3) and less than 50% by weight of one or more diene elastomers other than isoprenic. 30 19- Use according to claim 18, characterized in that said elastomer composition (s) comprises at least one isoprene elastomer chosen from: (1) homopolymeric synthetic polyisoprenes; (2) polyisoprenes of synthetic copolymers consisting of poly (isoprene-butadiene), poly (isoprene-styrene) and poly (isoprene-butadiene-styrene); (3) natural rubber; (4) butyl rubber; (5) a mixture of at least two of the aforementioned elastomers (1) to (4); (6) a mixture containing more than 50% by weight of the aforementioned elastomer (1) or (3) and less than 50% by weight of non-isoprene diene elastomer consisting of polybutadiene, polychloroprene, poly (butadiene styrene), poly (butadiene-acrylonitrile) or a terpolymer. 20- Use according to one of claims 1 to 19, characterized in that said elastomer composition (s) comprises as isoprene elastomer at least natural rubber, preferably said elastomer composition (s) comprising at least as elastomer (s) only natural rubber. 21- Use according to one of claims 1 to 20, characterized in that said elastomer composition (s) further comprises at least one compound selected from vulcanizing agents, vulcanization accelerators, vulcanization activators, carbon black, protective agents, plasticizers. 22- Use according to one of claims 1 to 21 in the soles of shoes, floor coverings, gas barriers, flame retardant materials, rollers of cable cars, appliance joints, liquid pipe joints or gas, brake system seals, hoses, ducts, cables, engine mounts, conveyor belts, transmission belts or, preferably, tires. 23. Use according to one of claims 1 to 22 in a tire for heavy goods vehicles, in particular for trucks. 24- Composition of elastomer (s) comprising: - at least one isoprene elastomer, - at least one reinforcing inorganic filler, - at least one inorganic filler - elastomer coupling agent, characterized in that said inorganic filler - elastomer coupling agent is 3-acryloxypropyltriethoxysilane, said reinforcing inorganic filler and said inorganic filler-elastomer coupling agent being as defined in one of claims 1 to 13. 25. Composition according to claim 24, characterized in that the amount of 3-acryloxypropyltriethoxysilane represents from 1 to 20%, in particular from 2 to 15%, relative to the amount of said precipitated silica. 26- Composition according to claim 25, characterized in that said precipitated silica and 3-acryloxypropyltriethoxysilane are premixed together. 27- Composition according to one of claims 25 and 26, characterized in that said composition further comprises at least one covering agent of said precipitated silica, optionally premixed with said precipitated silica and 3-acryloxy-propyltriethoxysilane. 28. Composition according to one of claims 24 to 27, characterized in that said composition does not comprise another inorganic filler-elastomer coupling agent. 29. Composition according to one of Claims 24 to 28, characterized in that the said composition does not comprise a free radical initiator. 30. Composition according to one of claims 24 to 29, characterized in that said composition does not comprise other elastomers than the said isoprene elastomer (s). 31- The composition according to one of claims 24 to 30, characterized in that said composition comprises at least one isoprene elastomer and at least one diene elastomer other than isoprene, the amount of isoprene elastomer (s) relative to the total amount of elastomer (s) being preferably greater than 50% by weight. 32- Composition according to one of claims 24 to 31, characterized in that said composition comprises at least one isoprene elastomer chosen from: (1) synthetic polyisoprenes obtained by homopolymerization of isoprene or 2-methylbutadiene-1, 3; (2) synthetic polyisoprenes obtained by copolymerization of isoprene with one or more ethylenically unsaturated monomers chosen from: (2.1) conjugated diene monomers, other than isoprene, having from 4 to 22 carbon atoms; (2.2) vinyl aromatic monomers having 8 to 20 carbon atoms; (2.3) vinyl nitrile monomers having from 3 to 12 carbon atoms; (2.4) acrylic ester monomers derived from acrylic acid or methacrylic acid with alkanols having from 1 to 12 carbon atoms; (2.5) a mixture of at least two of the aforementioned monomers (2.1) to (2.4); copolymeric polyisoprenes containing between 20 and 99% by weight of isoprenic units and between 80 and 1% by weight of diene units, aromatic vinyls, vinyl nitriles and / or acrylic esters; (3) natural rubber; (4) copolymers obtained by copolymerization of isobutene and isoprene, as well as the halogenated versions of these copolymers; (5) a mixture of at least two of the aforementioned elastomers (1) to (4); (6) a mixture containing more than 50% by weight of the aforementioned elastomer (1) or (3) and less than 50% by weight of one or more diene elastomers other than isoprenic. 33. Composition according to claim 32, characterized in that said composition comprises at least one isoprene elastomer chosen from: (1) homopolymeric synthetic polyisoprenes; (2) the synthetic polyisoprenes copolymers consisting of poly (isoprene-butadiene), poly (isoprene-styrene) and poly (isoprene-butadiene-styrene); (3) natural rubber; (4) butyl rubber; (5) a mixture of at least two of the aforementioned elastomers (1) to (4); (6) a mixture containing more than 50% by weight of the aforementioned elastomer (1) or (3) and less than 50% by weight of non-isoprene diene elastomer consisting of polybutadiene, polychloroprene, poly (butadiene styrene), poly (butadiene-acrylonitrile) or a terpolymer. 34- Composition according to one of claims 24 to 33, characterized in that said composition comprises as isoprene elastomer at least natural rubber, preferably said elastomer composition (s) comprising as elastomer (s) ) only natural rubber. 35- Composition according to one of claims 24 to 34, characterized in that said composition further comprises at least one compound selected from vulcanizing agents, vulcanization accelerators, vulcanization activators, carbon black, the agents protectors, antireversions agents, plasticizers. 36- Article comprising at least one composition according to one of claims 24 to 34, this article consisting of a shoe sole, a floor covering, a gas barrier, a flame retardant material, a cable car, a seal of household appliances, a gasket for liquids or gases, a brake system gasket, a pipe, a jacket, a cable, an engine support, a conveyor belt, a transmission belt or, preferably, a pneumatic tire . 37- A tire according to claim 36 for heavy goods vehicles, in particular for trucks. A composition comprising at least one reinforcing inorganic filler for elastomer and at least one inorganic filler - elastomer coupling agent, characterized in that said inorganic filler - elastomer coupling agent is 3-acryloxypropyltriethoxysilane, said reinforcing inorganic filler and said inorganic filler - elastomer coupling agent being as defined in one of claims 1 to 13. 39. Composition according to claim 38, characterized in that it further comprises at least one covering agent for said reinforcing inorganic filler. 40. Use of the composition according to one of claims 38 and 39 in an elastomer composition (s) comprising at least one isoprene elastomer, in particular natural rubber. 41- Use according to claim 40 in a tire, in particular for trucks, especially for trucks.