BR112019023028B1 - RUBBER COMPOSITION COMPRISING AT LEAST ONE SILICA AS INORGANIC REINFORCEMENT FILLER, PROCESS FOR PREPARING THE SAME, SEMI-FINISHED ARTICLE AND TIRE COMPRISING THE SAME - Google Patents

Abstract

The invention relates to a rubber composition produced from at least one elastomer, an inorganic reinforcing material, a coupling agent for coupling the elastomer to the inorganic reinforcing material and a crosslinking system; said reinforcing inorganic filler comprising at least one S silica having: - a specific surface area of CTAB SCTAB within a range of 40 to 300 m/g; - a difference between the specific surface area of BET SBET and the specific surface area of CTAB SCTAB greater than or equal to 35 m2/g; - a WAl aluminum content in the range of 0.5 to 7.0% by weight, relative to the weight of the S silica; - an aggregate size distribution amplitude Ld, measured by centrifugal sedimentation, greater than or equal to 1.5; and - a d50 average aggregate diameter, measured by centrifugal sedimentation, so that, for a given CTAB SCTAB specific surface area value and a given WAL aluminum content, a quantity A is defined by the following equation (I): A = [d50] + 0.782 x [SCTAB] - 8.524X [WAL] (I) where: [d50] is the numerical value of d50 expressed in nm; [SCTAB] is the numerical value of (...).

Description

[001] The invention relates to the field of rubber compositions reinforced by an inorganic filler, especially intended for the manufacture of tires or semi-finished products for tires, in particular for treads of these tires.

[002] Rubber compositions determine the road performance of a tire to a large extent. Initially, carbon black was used in rubber compositions as a reinforcing filler, with the aim of limiting tire wear.

[003] However, since fuel economy and the need to protect the environment have become a priority, it has become necessary to produce tires that have reduced rolling resistance without adversely affecting their wear resistance.

[004] Furthermore, it is known in the field of tires that one performance property is often improved at the expense of another. This is the case for rolling resistance and wear resistance, as these performance properties are contradictory.

[005] Tire manufacturers therefore seek a compromise between these two performance properties.

[006] This was especially made possible by virtue of the use, in the treads of these tires, of innovative rubber compositions reinforced with inorganic fillers, in particular specific silicas of the highly dispersible type, which are capable of rivaling, from the point of view reinforcement, with a conventional tire grade carbon black, while giving these compositions a lower hysteresis, which is synonymous with a lower rolling resistance of the tires that comprise them.

[007] Treads containing, as a filler, such highly dispersible silicas (called "HD" or "HDS" for "highly dispersible" or "highly dispersible silica"), used in low rolling resistance tires, sometimes called " green tires" in reference to the energy savings provided to the user ("green tire concept"), have been widely described. Especially reference will be made to Patent Applications EP0501227, EP0692492, EP0692493, EP0735088, EP0767206, EP0786493, EP0881252, WO99/02590, WO99/02601, WO99/02602, WO99/06480, WO00/05300 and WO00/05301. These prior art documents teach the use of HD type silicas having a specific surface area between 100 and 250 m 2 /g.

[008] Among these HD silicas, use is preferably made of silicas with a high specific surface area. High specific surface area generally means surface areas of at least 130 m2/g, or even greater than or equal to 150 m2/g. The benefit of using a silica with a high specific surface area mainly lies in the possibility of increasing the number of bonds between the silica and the elastomer and therefore increasing the level of reinforcement of the same. That is why it seems advantageous to use silicas with a high specific surface area in rubber compositions for tire treads, in order to especially improve the wear resistance of these treads. As an example of silica that has a specific surface area of approximately 160 m2/g, mention may be made of Zeosil® 1165MP silica marketed by Solvay, the reference in the field of “green tires”.

[009] However, it is known that the increase in the specific surface area of a silica is done to the detriment of the hysteresis properties of the rubber compositions, which deteriorates the rolling resistance.

[0010] It still remains beneficial for tire manufacturers to continue to improve the rolling resistance/wear resistance performance trade-off, especially by specifically modifying the morphology of a silica.

[0011] To this end, the applicant has described, in his patent application WO 03/016387, a family of highly dispersible silicas which have a specific surface area greater than that of silicas known to date. These silicas provide the compositions containing them with a significant improvement in wear resistance, without degrading the other properties of these compositions, and especially the rolling resistance.

[0012] In the pursuit of his researches, the applicant discovered, surprisingly, that a silica having a specific morphology, used as an inorganic reinforcing filler in a rubber composition, makes it possible to obtain an excellent compromise of rolling resistance/wear resistance . This compromise is greater than that provided by existing silicas with a high specific surface area, which are commonly used in “green tire” treads.

[0013] Consequently, a first object of the invention relates to a rubber composition based on at least one elastomer, an inorganic reinforcing filler, an agent for coupling the elastomer to the inorganic reinforcing filler and a crosslinking system; said reinforcing inorganic filler comprising at least one S silica having: - a specific surface area of CTAB SCTAB within a range extending from 40 to 300 m2/g; - a difference between the specific surface area of BET SBET and the specific surface area of CTAB SCTAB greater than or equal to 35 m2/g; - a WAl aluminum content within a range extending from 0.5 to 7.0% by weight relative to the weight of silica S; - a breadth of aggregate size distribution Ld, measured by centrifugal sedimentation, greater than or equal to 1.5; and - an average aggregate diameter d50, measured by centrifugal sedimentation, so that, for a given CTAB SCTAB specific surface area value and a given WAl aluminum content, a magnitude A is defined by the following equation (I): A = [d50] + 0.782 x [SCTAB] - 8.524 x [WA1] (i) where: [d50] is the numerical value of d50, expressed in nm; [SCTAB] is the numerical value of SCTAB, expressed in m2/g; [WAl] is the numerical value of WAl, expressed in % by weight in relation to the weight of silica S; and said magnitude A satisfies the relation (II): A > 253 (II).

[0014] Another object of the present invention relates to a process for preparing a rubber composition as defined above, said process comprising the following steps: - at least one elastomer, at least one reinforcing inorganic filler and at least one agent for coupling the elastomer to the reinforcing inorganic charge are brought into contact; said reinforcing inorganic filler comprising at least one silica S having: - a specific surface area of CTAB SCTAB within a range extending from 40 to 300 m2/g; - a difference between the specific surface area of BET SBET and the specific surface area of CTAB SCTAB greater than or equal to 35 m2/g; - a WAl aluminum content within a range extending from 0.5 to 7.0% by weight relative to the weight of silica S; - a breadth of aggregate size distribution Ld, measured by centrifugal sedimentation, greater than or equal to 1.5; and - an average aggregate diameter d50, measured by centrifugal sedimentation, so that, for a given CTAB SCTAB specific surface area value and a given WAl aluminum content, a magnitude A is defined by the following equation (I): A = [d50] + 0.782 x [SCTAB] - 8.524 x [WA1] (i) where: [d50] is the numerical value of d50, expressed in nm; [SCTAB] is the numerical value of SCTAB, expressed in m2/g; [WAl] is the numerical value of WAl, expressed in % by weight in relation to the weight of silica S; and said magnitude A satisfies the relation (II): A > 253 (II); • everything is thermomechanically kneaded, once or several times, until a maximum temperature between 110 °C and 190 °C is reached; • the mix from the previous step is cooled to a temperature below 100 °C, • a crosslinking system is incorporated into the cooled mix from the previous step, • the mix comprising the crosslinking system is kneaded to a maximum temperature below 110° W.

[0015] Another object of the invention relates to a semi-finished article, especially for a tyre, comprising at least one composition as defined above or capable of being obtained according to the process described above. Preferably, such semi-finished article is a tread, especially for a tyre.

[0016] Another object of the present invention is a tire comprising at least one composition as defined above or capable of being obtained according to the process described above.

[0017] Another object of the present invention is a tire comprising at least one semi-finished article as defined above. DETAILED DESCRIPTION OF THE INVENTION I.1 MEASUREMENTS AND TESTS USED □ Characterization of silicas

[0018] The silicas are characterized as indicated below. • CTAB Specific Surface Area Measurement (SCTAB) • Measuring principle

[0019] CTAB specific surface area (SCTAB) values were determined according to an internal procedure derived from the NF ISO 5794-1 standard, appendix G of June 2010. The process is based on the adsorption of CTAB (bromide of N-hexadecyl-N,N,N-trimethylammonium) to the "outer" surface of the silica.

[0020] The CTAB is left to adsorb to the silica in aqueous suspension, with magnetic stirring. After separation of the liquid phase using a centrifuge, excess non-adsorbed CTAB is filtered off with sodium bis(2-ethylhexyl) sulfosuccinate salt (referred to as "OT" in the rest of the description) using of a titrator, and the titration point is given by the maximum turbidity of the solution and determined by a phototrode. • Used device - Precision scale with precision of 1/10 of a mg, Mettler Toledo AS205; - Magnetic stirrer capable of rotating at a speed of 1,100 rpm; - Seven pH meters of the easy type, Mettler Toledo, equipped with a pH electrode type InLab Expert Pro, Mettler Toledo; - Automatic titration equipment type T70, Mettler Toledo, equipped with a DP5 phototrode set to 555 nm; - Stopwatch, whose unit of work is the second; - Titration cylinder, 125 ml plastic cylinder, Mettler Toledo; - Sampling cylinders of 50 and 500 ml; - Centrifuge capable of rotating at a speed of 8,000 rpm; - Mortar and pestle; - Centrifuge tubes with a capacity of 50 ml, suitable for the centrifuge, with screw cap; - 1 liter class A volumetric flasks; - Teflon-coated magnetic stirring bars; - Class A+ precision graduated pipettes of 10 ml and 20 ml, with two marks; - Class A precision burette of 50 ml; - Tall borosilicate glass weighing flask, fitted with a lid, with a capacity of 40 ml, eg 0 35, H 70 mm; - Low format weighing flask, 50 mm in diameter, with cover lid; - Natural ventilation oven, Memmert UM100; - desiccator; - 150 μm sieve and sieve holder. • Reagents

[0021] All reagents must be of recognized analytical quality. The water used must be demineralized water. - Sodium carbonate (Na2CO3), with a purity greater than 99%; - Sodium bicarbonate (NaHCO3) with a purity greater than 99%; - Hexadecyltrimethylammonium bromide (CTAB; C19H42BrN) with a purity greater than 99%;- Sodium bis(2-ethylhexyl)sulfosuccinate (OT; C20H37O7SNa) with a purity greater than 99%; - Demineralized water • Preparation of solutions o Preparation of pH 9.54 buffer solution c(HCO3'/CO32-) = 0.054 mol/l

[0022] In a 1 liter volumetric flask containing 500 ml of demineralized water, the following are added: 4.5470 ± 0.003 g of sodium carbonate (Na2CO3); 9.3585 ± 0.003 g of sodium bicarbonate (NaHCO3).

[0023] After dissolving the solids, the volumetric flask is filled to the graduation mark with demineralized water and homogenization is performed with magnetic stirring for 10 minutes at 250 rpm.

[0024] The pH of the solution is checked with the pH meter; the same should be 9.54 ± 0.1. o Hexadecyltrimethylammonium bromide (CTAB) solution, c(CTAB) = 0.015 mol/l

[0025] 5.50 ± 0.005 g of CTAB are dissolved in a 1 liter volumetric flask containing 350 ml of the buffer solution and approximately 500 ml of demineralized water. Demineralized water is added up to the graduation mark.

[0026] Homogenization is performed with magnetic stirring for approximately 10 hours at a speed of 250 rpm.

[0027] The pH of the solution is checked with the pH meter; the same must be 9.6 ± 0.1.

[0028] At no time should the temperature of this solution drop below 22 °C, the temperature of recrystallization.

[0029] The solution can be used for 24 hours after its preparation. The expiry date of this solution is 15 days. o Sodium bis(2-ethylhexyl) sulfosuccinate (OT) solution, c(OT) = 0.00389 mol/l

[0030] In a 1-liter volumetric flask containing 500 ml of demineralized water, the following are dissolved:

[0031] 1.730 ± 0.005 g of OT; Demineralized water is added up to the graduation mark and stirring is carried out with a magnetic stirrer for 10 h at 250 rpm.

[0032] This solution should be used 12 days after its preparation. The expiry date of this solution is 2 months. Once opened, the solid reagent should be stored in a desiccator. • Test conditions

[0033] The test must be performed at a temperature of 24 °C ± 2 °C.

[0034] It is recommended that the reagents and apparatus be brought to the equilibrium temperature of the room.

[0035] The CTAB solution must not be stored at a temperature below 22 °C. This causes slow recrystallization.

[0036] Before any analysis, the reagents are homogenized under magnetic stirring for 15 minutes at 250 rpm.

[0037] Before any analysis, the burette circuits must be purged and the absence of air bubbles in the circuits must be verified.

[0038] Before any analysis, the phototrode is washed with ethanol, then with demineralized water and then conditioned for 30 minutes in a beaker containing 50 ml of demineralized water.

[0039] The potential of the demineralized water on the phototrode must be 1,000 ± 5 mV, which corresponds to 100% transmission. • Determination of the blank test

[0040] The blank test makes it possible to determine the amount of OT required for the titration of 10 ml of CTAB solution.

[0041] 10.0 ml of CTAB solution are withdrawn and decanted into a beaker for titration. 50 ml of demineralized water is added using the sampling cylinder.

[0042] The test is performed with the following parameters: Endpoint value: 200 mV; Maximum rate: 10 ml/min Minimum rate: 10 μl/min.

[0043] Two tests are performed.

[0044] The volumes in ml of OT solution determined during the two blank tests are called V 2 and V 3.

• Adsorção do CTAB pela sílica.[0045] The average volume V4 is calculated as follows:

• Adsorption of CTAB by silica.

[0046] The silica sample is reduced to powder using a pestle and mortar and then passed through the 150 μm sieve.

[0047] 0.35 ± 0.005 g of the silica sieved sample are weighed, and this test sample weight is called P1.

[0048] The test sample is introduced carefully into a weighing bottle and a magnetic stirring bar is introduced into the weighing bottle.

[0049] 30.0 ml of the CTAB solution are then introduced and placed under magnetic stirring at 1,100 rpm for 40 minutes. • Silica separation

[0050] Immediately after adsorbing the silica, the entire suspension is decanted into a centrifuge tube.

[0051] The silica is separated from the suspension by centrifugation at 8,000 rpm for 30 minutes. • CTAB test after adsorption

[0052] Using a pipette, 10.0 ml of the supernatant CTAB solution is withdrawn directly from the centrifuge tube, taking care not to drag any silica.

[0053] Decantation is carried out in a titration beaker and 50 ml of demineralized water are added using the sampling cylinder. The test is performed with the following parameters: Endpoint value: 250 mV; • Maximum rate: 10 ml/min • Minimum rate: 5 μl/min.

[0054] The consumed OT volume is noted V1. • Moisture content of silica

[0055] The moisture content (% H2O) for each silica sample is determined by the weight loss of the sample after being placed in an oven at 105 °C for 2 hours. For this purpose, the weight of a weighing bottle and a cover cap are weighed on the precision balance, this weight m0 is noted; then exactly 2 g of the silica sample to be tested is quickly weighed. The cap is placed on the bottle once the silica has been weighed, and the m1 weight of the weighing bottle, cap and sample assembly is noted. The lid is then removed and the weighing flask containing silica is placed in a naturally ventilated oven set at 105 ± 5 °C for 2 hours, the oven being preheated to the prescribed temperature.

[0056] The weighing and sample bottle assembly is removed from the oven, the cap is replaced on the bottle and the assembly is placed in the desiccator to cool until it returns to room temperature. The assembly is heavy and the m2 weight is noted.

m0: peso da garrafa de pesagem e da tampa; em gramas; m1: peso do conjunto de garrafa de pesagem, tampa e amostra de sílica, antes de ser colocado no forno; em gramas; m2: peso do conjunto de garrafa de pesagem, tampa e amostra de sílica, após remoção do forno; em gramas. • Expressão dos resultados[0057] The moisture content, expressed as a percentage by weight, is then obtained according to the following formula:

m0: weight of weighing bottle and lid; in grams; m1: weight of the weighing bottle, lid and silica sample assembly, before being placed in the furnace; in grams; m2: weight of the weighing bottle, lid and silica sample set, after removal from the oven; in grams. • Expression of results

em que: 0,165 g = peso de CTAB contido em 30,0 ml de solução; V4 em ml = volume médio de solução de OT derramado para o teste em branco; V1 em ml = volume de solução de OT derramado para o ensaio de teste;P1 em g = peso da amostra de teste bruta; % H2O = teor de umidade de sílica. • Medição da área de superfície específica de BET (SBET)[0058] The CTAB adsorption index is given by the following relationship: CTAB adsorption index (m2/g) =

where: 0.165 g = weight of CTAB contained in 30.0 ml of solution; V4 in ml = average volume of OT solution spilled for the blank test; V1 in ml = volume of OT solution poured for the test run; P1 in g = weight of the raw test sample; % H2O = moisture content of silica. • Measurement of BET Specific Surface Area (SBET)

[0059] 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, Feb. 1938) and, more specifically, according to a method derived from NF ISO 5794-1, Appendix E, June 2010 [multipoint volumetric method (5 points) - gas: nitrogen - vacuum degassing: one hour at 160 ° C - relative pressure w/po range: 0.05 to 0.2]. • Measurement of aluminum content (WAl)

[0060] The Al content (also called WAl) is the aluminum content, that is, the metallic chemical element. The same is determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES). • Apparatus - Precision scale, with 0.1 mg scale, - Funnels, - 100 ml class A volumetric flasks, - 250 ml class A volumetric flasks, - Platinum dishes, - Calibrated micropipette with variable volume of 0.1 to 1 ml (for example: Eppendorf), - Calibrated micropipette with variable volume from 0.5 to 5 ml (for example: Eppendorf), - Syringe filters made of cellulose acetate, with a pore diameter of 0, 45 μm, - 20 ml sample holders, - ICP spectrometer (eg Jobin Yvon, Activa M model), - sand bath. • Reagents - Ultrapure water - Concentrated hydrochloric acid (for example: VWR reference: 20252.290) d=1.18 HCl % = 37 - Concentrated sulfuric acid (for example: VWR reference: 1.00731.1000) d=1.84 H2SO4 % = 95 to 97 - Concentrated hydrofluoric acid (for example: VWR reference: 20307.290) d=1.13 HF % = 40 - Standard aluminum solution of 1 g/l (VWR reference: 1.19770.0500)

operation procedure

[0061] Preparation of the silica sample to be tested: - Accurately weigh approximately 100 mg of silica to be tested in a platinum dish; - Add a few milliliters of demineralized water and 3 drops of concentrated sulfuric acid; - Add 10 ml of concentrated hydrofluoric acid; - Evaporate to dryness in a sand bath; - Add additional 10 ml of hydrofluoric acid, evaporate to dryness; - Repeat this operation a third time; - Let the plate cool down; - Collect the sample again in 10 ml of concentrated hydrochloric acid for several minutes; - After the acid has cooled down, decant the sample into a 200 ml flask containing demineralized water and add demineralized water up to the graduation mark.

[0062] Preparing the blank: - In a platinum dish, add a few milliliters of demineralized water and 3 drops of concentrated sulfuric acid; - Add 10 ml of concentrated hydrofluoric acid; - Evaporate to dryness in a sand bath; - Add additional 10 ml of hydrofluoric acid, evaporate to dryness; - Repeat this operation a third time; - Let the plate cool down; - Collect the sample again in 10 ml of concentrated hydrochloric acid for several minutes; - After the acid has cooled down, decant the sample into a 200 ml flask containing demineralized water and add demineralized water up to the graduation mark.

CALIBRATION STRIPE PREPARATION:

St = Padrão PREPARAÇÃO DO CONTROLE DE VALIDAÇÃO[0063] The calibration range is composed of 5 standards prepared in 100 ml bottles of a commercial aluminum solution of 1000 mg/l, according to table I below: TABLE I

St = Standard VALIDATION CONTROL PREPARATION

ENSAIO ICP-AES:[0064] The validation control is prepared in the same way as the St 2 standard of the calibration range, using a 1,000 mg/l aluminum solution in a 100 ml flask, according to Table II below .

ICP-AES TEST:

[0065] Analyze the solutions obtained by the ICP-AES (see instrument parameters). LINES USED:

SEQUÊNCIA DE ANÁLISE: 1- Calibração; 2- Controle de validação; 3- Branco; 4- Amostras.[0066] Jobin Yvon Activates ICP-AES

ANALYSIS SEQUENCE: 1- Calibration; 2- Validation control; 3- White; 4- Samples.

• Resultados[0067] The parameters of the Jobin Yvon Activa ICP-AES instrument are shown in Table III below:

• Results

com: C: concentração em mg/l de alumínio na amostra; Cb: concentração em mg/l de alumínio no branco; V: volume do balão volumétrico em l (nesse caso 0,200 l); PE: amostra de teste em mg de amostra; • Medição dos parâmetros d16, d50, d84 e Ld[0068] The aluminum content (WAl) of the tested silica is given by the following relationship (IV):

with: C: concentration in mg/l of aluminum in the sample; Cb: concentration in mg/l of aluminum in the blank; V: volumetric flask volume in l (in this case 0.200 l); PE: test sample in mg of sample; • Measurement of parameters d16, d50, d84 and Ld

[0069] The d16, d50, d84 and Ld values are measured using a centrifugal photosedimentometer type CPS DC24000 UHR, sold by CPS Instruments. This player is equipped with the operating software provided with the player (operating software version 11g).

[0070] For the purposes of measurements, the following equipment and products are also used: - Ultrasound system: Sonics Vibracell VCF1500 1,500-watt generator, equipped with a Sonics Vibracell CV154 converter, with a Sonics Vibracell amplifier BHN15GD (x1.5) and one Sonics Vibracell 207-10 19mm probe, with interchangeable 19mm Sonics Vibracell 630-0407 Tip probe; - 0.1 mg precision analytical balance (eg Mettler Toledo XP504 model); - Syringes: 1.0 ml and 2.0 ml with 0.81 mm diameter needles; - Tall 50 ml glass beaker (SCHOTT DURAN: 38 mm in diameter, 70 mm in height); magnetic stirrer with 2 cm stirrer bar; - Crystallizer-type ice bath container; - Chemicals: deionized water; 96% ethanol; 99% sucrose (CAS no57-50-1); dodecane; all provided by Sigma; PVC calibration standard provided by CPS Instrument, Inc. The maximum peak of the calibration standard used must be located between 200 and 600 nm, for example 239nm. • Instrument presetting and configuration

cps = centipoise[0071] For measurements, the parameters according to table IV are inserted in the instrument software. Data related to the PVC calibration standard is provided by the supplier of said standard. TABLE IV:

cps = centipoise

[0072] The following parameters for treatment options are defined in accordance with Table V below:

[0073] All other options in the software are set to default by the instrument manufacturer. • Sedimentation gradient preparation

[0074] The centrifuge disk is set to rotate at 24,000 rpm for 30 min. The sucrose solution density gradient is prepared as follows: An aqueous solution containing 24% sucrose by weight is prepared in a 50 ml beaker. An aqueous solution containing 8% sucrose by weight is prepared in a second 50 ml beaker. Once these two solutions are homogenized separately, samples are collected from each of these solutions using a 2 ml syringe, and these samples are injected into the rotating disc in the following order: - Sample 10 1.8 ml of the 8% solution.

[0075] Before each injection into the disc, the 2 solutions are homogenized in the syringe, by suctioning approximately 0.2 ml of air followed by brief manual agitation for a few seconds, making sure not to lose any liquid.

[0076] These injections, whose total volume is 18 ml, are intended to create a density gradient that is useful to eliminate certain instabilities that may appear during the injection of the sample to be measured. To protect this gradient from evaporation, 1 ml of dodecane is added to the rotating disk via a 2 ml syringe. The disk is then allowed to rotate at 24,000 rpm for 60 minutes before any first measurements are taken (rpm = revolutions per minute). • Preparation of the silica sample to be analyzed

[0077] 3.2 g of silica are weighed into a 50 ml tall glass beaker (SCHOTT DURAN: diameter 38 mm, height 70 mm) and 40 ml of deionized water are added. The suspension is placed under magnetic stirring with a 2 cm magnetic stirrer bar at 300 rpm (rpm = revolutions per minute) for at least 20 seconds, then the magnetic stirrer bar is removed and the beaker is placed in a crystallizer. filled with an ice bath. The ultrasound probe is then immersed in the beaker, with the end of the probe located 1 cm below the air-liquid interface. It is advisable to ensure that the interchangeable tip that transmits the ultrasound waves to the suspension has an acceptable state of wear before starting the generator. As is known to those skilled in the art, an acceptable state of wear is usually considered a surface state which does not have any visually perceptible roughness. As a reference for an unacceptable wear state, use can be made, for example, of the right-hand image in Figure 3, page 14, published in “Preparation of Nanoparticle Dispersions from Powdered Material Using Ultrasonic Disruption, version 1.1, [J. S. Taurozzi, V. A. Hackley, M. R. Wiesner], National Institute of Standards and Technology Special Publication 1200 to 1202, June 2012” (CODEN NSPUE, publication available using the digital identifier dx.doi.org/10.6028/NIST.SP .1200-2). The probe's generator is set to 60% of its maximum power and the silica suspension is subjected to ultrasound waves for 8 min. At the end of the ultrasound treatment, the suspension is again placed under magnetic stirring. The sample is taken under agitation. • Analysis

[0078] Before each injection of the sample to be measured, 100 μl of the suspension, containing the standard PVC particles provided by CPS Instruments, whose characteristics were previously registered in the software, are injected into the disk. It is advisable to start the measurement in the software simultaneously with this first injection and wait for confirmation from the instrument before being able to inject 100 μl of the silica suspension subjected to ultrasound in advance, ensuring once again that the measurement is started simultaneously with the injection. These injections are performed using 1 ml syringes.

[0079] At the end of the measurement, which is reached after the time required for all smaller diameter particles (set in the software to 0.02 μm) to settle, the software provides the relative proportions in weight for each measured diameter class. This curve obtained in this way is called the aggregate size distribution.

[0080] The integration of the aggregate size distribution as a function of the diameter makes it possible to obtain what is called a "cumulative" distribution; that is, the total weight of aggregates between the minimum measured diameter and a diameter of interest. • Results

[0081] The values of d50, d16, d84 and Ld result from the cumulative distributions and are calculated as follows, based on a linear scale: - d50 is the diameter below and above which 50% of the aggregate population is found, by weight. d50 is referenced as the mean diameter of the silica aggregates. The same is expressed in nm. - d84 is the diameter below which 84% of the aggregate population is found by weight. The same is expressed in nm. - d16 is the diameter below which 16% of the aggregate population is found by weight. The same is expressed in nm. - Ld: represents the amplitude of the aggregate size distribution. It is calculated according to the equation Ld = (d84-d16)/d50. Ld is a dimensionless number. - Characterization of rubber compositions

[0082] The rubber compositions are characterized, after curing, as indicated below.• Dynamic properties

[0083] The dynamic property tan(δ) is measured in a viscosity analyzer (Metravib VA4000) according to ASTM Standard D 5992 - 96. Measurement at a temperature of 23 °C:

[0084] The response of a sample of reticulated composition (cylindrical specimen with a thickness of 4 mm and a cross section of 400 mm2), subjected to a simple alternating sinusoidal shear stress, at a frequency of 10 Hz, at 23 ° C, per ASTM Standard D 5992-96, is engraved. A peak-to-peak strain amplitude sweep is performed from 0.1% to 100% (output cycle) and then from 100% to 0.1% (return cycle). The result made use of the loss factor (tan(δ)). For the return cycle, the maximum observed value of tan(δ) is indicated (maximum tan(δ) at 23 °C).

[0085] The results are indicated in base 100, with the arbitrary value of 100 being assigned to the control in order to then calculate and compare tan(δ)max at 23 °C of the different samples tested. The base 100 value for the sample to be tested is calculated according to the operation: (tan(δ)max value at 23 °C of the sample to be tested / tan(δ)max value at 23 °C of the control ) x 100 Thus, a result of less than 100 indicates a reduction in hysteresis (hence an improvement in hysteresis properties), which corresponds to an improvement in rolling resistance performance. • Abrasion resistance

[0086] Abrasion resistance is measured according to the NF ISO 4649 standard of November 2010, which consists of determining the volume loss of a sample after a displacement of 40 linear meters on standardized abrasive paper.

[0087] More particularly, the volume loss by abrasion is determined according to the indications of the NF ISO 4649 standard of November 2010 (method B), using an abrasion tester in which the cylindrical specimen is subjected to the action of an abrasive screen of P60 grain fixed to the surface of a rotating drum under a contact pressure of 5 N (N = Newton) and along a path of 40 m. A sample weight loss is measured and the volume loss is calculated according to the density (p) of the material that constitutes the specimen. The density (p) of the material that constitutes the specimen is conventionally obtained based on the weight fractions of each constituent of the material and their respective densities (p)

[0088] The results are indicated in base 100, and the arbitrary value of 100 is assigned to the control, in order to calculate and compare the volume loss of the substance of the different samples tested. The value in base 100 for the sample to be tested is calculated according to the operation: (volume loss value of substance to be tested/volume loss value of control substance) x 100 Therefore, a result lower than 100 indicates a decrease in volume loss and therefore an improvement in abrasion resistance, which corresponds to an improvement in wear resistance performance. On the other hand, a result greater than 100 indicates an increase in volume loss and therefore a decrease in abrasion resistance, which corresponds to a decrease in wear resistance performance. • Characterization of the other constituents of the composition • Glass transition temperature Tg

[0089] The glass transition temperature Tg is measured in a way known by DSC (Differential Scanning Calorimetry) according to ASTM D3418, 1999. • Microstructure of polymers

[0090] Near-infrared (NIR) spectroscopy is used to quantitatively determine the weight content of styrene in the elastomer and its microstructure (relative distribution of 1,2-vinyl-, trans-1,4- and cis-1 units ,4-butadiene). The principle of the method is based on the generalized Beer-Lambert law for a multicomponent system. Since the method is indirect, it involves a multivariate calibration [Vilmin, F., Dussap, C. and Coste, N., Applied Spectroscopy, 2006, 60, 619 to 29] performed using standard elastomers that have a composition determined by 13C NMR. The styrene content and microstructure are then calculated from the NIR spectrum of an elastomer film with a thickness of approximately 730 μm. The spectrum is acquired in transmission mode between 4000 and 6200 cm-1 with a resolution of 2 cm-1 using a Bruker Tensor 37 Fourier transform near-infrared spectrometer equipped with an InGaAs detector cooled by the Peltier effect.

I.2 MODALITY OF THE INVENTION

[0091] The rubber compositions specially intended for the manufacture of tires or semi-finished products for tires according to the invention are based on at least one elastomer, an inorganic reinforcing filler, an agent for coupling the elastomer to the inorganic filler of reinforcement and a reticulation system; said reinforcing inorganic filler comprising at least one silica S having: - a specific surface area of CTAB SCTAB within a range extending from 40 to 300 m2/g; - a difference between the specific surface area of BET SBET and the specific surface area of CTAB SCTAB greater than or equal to 35 m2/g; - a WAl aluminum content within a range extending from 0.5 to 7.0% by weight relative to the weight of silica S; - a breadth of aggregate size distribution Ld, measured by centrifugal sedimentation, greater than or equal to 1.5; and - an average aggregate diameter d50, measured by centrifugal sedimentation, so that, for a given CTAB SCTAB specific surface area value and a given WAl aluminum content, a magnitude A is defined by the following equation (I):

[0092] where: [d50] is the numerical value of d50, expressed in nm; [SCTAB] is the numerical value of SCTAB, expressed in m2/g; [WAl] is the numerical value of WAl, expressed in % by weight in relation to the weight of silica S; It is

[0093] said magnitude A satisfies the relation (II): A > 253 (II).

[0094] The expression composition "based on" should be understood as meaning a composition comprising the mixture and/or the reaction product of the various constituents used, some of which basic constituents are capable of reacting or intended to react with each other, at least in part, during the various stages of manufacture of the composition, in particular during cross-linking or vulcanization thereof.

[0095] "Silica aggregate" is intended to mean, for the purposes of the present invention, in a known manner, a set of indivisible primary particles (that is, which cannot be cut, divided, separated) produced during the synthesis of silica . A silica aggregate represents the smallest dispersible unit in a mixture.

[0096] In the present description, unless expressly stated otherwise, all percentages (%) shown are percentages by weight.

[0097] Furthermore, any range of values denoted by the expression "between a and b" represents the range of values that extends from more than “a” to less than “b” (i.e. limits a and b excluded), whereas any range of values denoted by the expression "from a to b" means the range of values extending from "a" to "b" (ie, including the strict limits a and b).

[0098] The abbreviation "phr" (per hundred parts of rubber) means parts by weight per hundred parts by weight of elastomers (of the total elastomers, if several elastomers are present) or rubber present in the rubber composition.

[0099] In the remainder of this application, the terms "silica" and "precipitated silica" are synonymous.

[00100] To avoid any ambiguity, the "x" symbol used in equations, especially in equation (I), represents the multiplication sign. Thus, the expression "a x b" means "a" multiplied by "b".

[00101] Within the context of the invention, the carbon-based products mentioned in the description may be of fossil or biological origin. In the latter case, they can result partially or completely from biomass or be obtained from renewable starting materials resulting from biomass. Polymers, plasticizers, fillers, etc. are especially related. □ Elastomer

[00102] The rubber compositions according to the invention comprise at least one elastomer, that is, an elastomer or a mixture of several elastomers. Elastomers are polymers well known to those skilled in the art.

[00103] Preferably, the elastomer is a diene elastomer.

[00104] More preferably, the elastomer is a synthetic diene elastomer.

[00105] It is recalled here that the elastomer (or "rubber", the two terms being considered synonymous) of the "diene" type must be understood, in a known way, as meaning one (one or more is understood) elastomer that results at least least in part (ie, a homopolymer or a copolymer) of the diene monomer (or monomers) (ie, monomer (or monomers) containing two conjugated or non-conjugated carbon-carbon double bonds).

[00106] Diene elastomers can be classified into two categories: "essentially unsaturated" or "essentially saturated". "Essentially unsaturated" is generally intended to mean a diene elastomer that results, at least in part, from conjugated diene monomers that have a molar content of diene parent units (conjugated dienes) that is greater than 15% (% in mol); therefore, diene elastomers such as butyl rubbers or copolymers of dienes and α-olefins of the EPDM type, do not fit the above definition and may be designated especially "essentially saturated" diene elastomers (low or very low molar content, always less than to 15 % (mol %) of diene source units). In the category of "essentially unsaturated diene elastomers", "highly unsaturated" diene elastomer means in particular a diene elastomer which has a molar content of diene source units (conjugated dienes) greater than 50% (mol %).

[00107] Given these definitions, "diene elastomer capable of being used in the rubber compositions according to the invention" is more particularly intended to mean: (a) any homopolymer obtained by polymerization of a conjugated diene monomer with 4 to 12 carbon atoms; (b) any copolymer obtained by copolymerizing one or more dienes conjugated with each other or with one or more vinylaromatic compounds having from 8 to 20 carbon atoms;(c) a ternary copolymer obtained by copolymerizing ethylene and an α-olefin having 3 to 6 carbon atoms with a non-conjugated diene monomer having 6 to 12 carbon atoms such as, for example, those elastomers obtained from ethylene and propylene with a non-conjugated diene monomer of the above-mentioned type such as, especially 1,4-hexadiene, ethylidene norbornene or dicyclopentadiene; (d) a copolymer of isobutene and isoprene (butyl rubber) and also halogenated versions, in particular chlorinated or brominated versions, of this type of copolymer.

[00108] Although this applies to any type of elastomer, especially diene elastomer, persons skilled in the art will understand that the present invention is preferably employed with essentially unsaturated diene elastomers, in particular of type (a) or (b) above .

[00109] In the case of copolymers (b), the latter may contain from 20% to 99% by weight of diene units and from 1% to 80% by weight of vinylaromatic units.

[00110] As conjugated dienes, the following are especially suitable: 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-di(C 1-C 5 alkyl)-1,3-butadienes such as , for example, 2,3-dimethyl-1,3-butadiene, 2,3-diethyl-1,3-butadiene, 2-methyl-3-ethyl-1,3-butadiene, 2-methyl-3-isopropyl- 1,3-butadiene, an aryl-1,3-butadiene, 1,3-pentadiene or 2,4-hexadiene.

[00111] The following, for example, are suitable as vinylaromatic compounds: styrene, ortho-, meta- or para-methylstyrene, the commercial mixture "vinyltoluene", para-(tert-butyl)styrene, methoxystyrenes, chlorostyrenes, vinylmesitylene, divinylbenzene or vinylnaphthalene.

[00112] Preferably, the diene elastomer (or elastomers) of the composition according to the invention can preferably be selected from the group of diene elastomers consisting of polybutadienes (abbreviated as BRs), synthetic polyisoprenes (abbreviated as IRs), natural rubber (abbreviated as NR), butadiene copolymers, isoprene copolymers and mixtures of these elastomers. Such copolymers are most preferably selected from the group consisting of butadiene/styrene copolymers (abbreviated as SBRs), whether the latter prepared by emulsion polymerization (ESBR) or solution polymerization (SSBR), isoprene/butadiene copolymers (abbreviated as BIRs ), isoprene/styrene copolymers (abbreviated as SIRs) and isoprene/butadiene/styrene copolymers (abbreviated as SBIRs). Preferably, the diene elastomer is selected from the group consisting of polybutadienes (BRs), butadiene/styrene copolymers (SBRs), isoprene/butadiene copolymers (BIRs), isoprene/styrene copolymers (SIRs), isoprene/styrene copolymers (SIRs), isoprene/butadiene/styrene copolymers (SBIR) and blends of these copolymers.

[00113] Among the diene elastomers, the following are suitable: polybutadienes and, in particular, those that have a content (% in mol) of 1,2- units between 4% and 80% or those that have a content (% in mol) of cis-1,4- units greater than 80%, polyisoprenes, butadiene/styrene copolymers, and in particular those having Tg (glass transition temperature Tg, measured according to ASTM D3418, 1999) from between 0 °C and -70 °C and more particularly between -10 °C and -60 °C, a styrene content between 5% and 60% by weight and more particularly between 20% and 50% by weight, a content (% in mol) of 1,2- bonds in the butadiene part of between 4% and 75% and a content (% in mol) of trans-1,4- bonds between 10% and 80%, copolymers of butadiene/isoprene and especially those having an isoprene content between 5% and 90% by weight and Tg ranging from -40 °C to -80 °C or isoprene/styrene copolymers and especially those having a of styrene between 5% and 50% by weight and a Tg between -5 °C and -50 °C. In the case of butadiene/styrene/isoprene copolymers, those having a styrene content between 5% and 50% by weight and, more particularly, between 10% and 40%, an isoprene content between 15% and 60% by weight and, more particularly, between 20% and 50%, a butadiene content between 5% and 50% by weight and, more particularly, between 20% and 40%, a content (% in mol) of 1.2 units of the part butadiene of between 4% and 85%, a content (mol %) of trans-1,4- units of the butadiene part of between 6% and 80%, a content (mol %) of 1,2- plus 3,4 units - of the isoprene part between 5% and 70% and a content (% in mol) of trans-1,4- units of the isoprene part between 10% and 50% and, more generally, any butadiene/styrene/isoprene copolymer that have a Tg between -5 °C and -70 °C are especially suitable.

[00114] According to a specific embodiment, the diene elastomer is predominantly (for more than 50 phr) an SBR, whether this is an SBR prepared in emulsion ("ESBR") or an SBR prepared in solution ("SSBR") or a mix (blend) of SBR/BR, SBR/NR (or SBR/IR), BR/NR (or BR/IR) or even SBR/BR/NR (or SBR/BR/IR). In the case of an SBR elastomer (ESBR or SSBR), use is especially made of an SBR having a moderate styrene content, for example between 20% and 35% by weight, or a high styrene content, for example 35 % to 45% by weight, a content (% in mol) of vinyl bonds in the butadiene part of between 15% and 70%, a content (% in mol) of trans-1,4- bonds of between 15% and 75% and a Tg between -10°C and -55°C; such SBR may advantageously be used as a mixture with a BR which preferably has more than 90% (mol %) of cis-1,4- bonds.

[00115] According to another specific embodiment of the invention, the diene elastomer of the composition according to the invention comprises a mixture (blend) of a BR (as a low Tg elastomer) with a content (% in mol) of cis bonds -1,4- greater than 90% with one or more S-SBRs or E-SBRs (as high Tg elastomer (or elastomers)).

[00116] Elastomers can have any microstructure, which depends on the polymerization conditions used, especially the presence or absence of a modification and/or randomization agent and the amounts of modification and/or randomization agent used. These elastomers can, for example, be block, random, sequential or microsequential elastomers and be prepared in dispersion or in solution; they can be star-coupled and/or branched or otherwise functionalized with a coupling agent and/or star-branched or functionalized.

[00117] Preferably, the elastomer is a functionalized diene elastomer.

[00118] Preferably, the functionalized diene elastomer is a functionalized butadiene/styrene copolymer.

[00119] "Functionalized diene elastomer" means a synthetic diene elastomer comprising at least one chemical group comprising one or more heteroatoms such as, for example, a sulfur atom S, a nitrogen atom N, an oxygen atom O, a Si silicon atom or an Sn tin atom. Within the context of the present description, this chemical group is also called a "function". The two terms are used interchangeably.

[00120] This chemical group can be located at the end of the chain, ie at one end of the main linear elastomer chain. Then it will be said that the diene elastomer is functionalized "at the end of the chain". It is generally an elastomer obtained by reacting a living elastomer with a functionalizing agent, i.e. any molecule that is at least monofunctional, the function being any type of chemical group known to persons skilled in the art to react with one end of the live chain.

[00121] This chemical group can be located in the main linear elastomer chain. Then it will be said that the diene elastomer is coupled or otherwise functionalized "in the middle of the chain", as opposed to the position "at the end of the chain", even though the group is not located precisely in the middle of the elastomer chain. It is usually an elastomer obtained by reacting two chains of the living elastomer with a coupling agent, i.e. any at least difunctional molecule, the function being any type of chemical group known by persons skilled in the art to react with a end of the live chain.

[00122] This group can be central, to which n elastomer chains (n> ) are linked, forming a branched star structure of the elastomer. Then it will be said that the diene elastomer is star-branched. It is generally an elastomer obtained by reacting n chains of the living elastomer with a star branching agent, i.e. any polyfunctional molecule, the function being any type of chemical group known by persons skilled in the art to react with a end of the live chain.

[00123] Those skilled in the art will understand that a functionalization reaction with an agent comprising more than one function that is reactive with respect to the living elastomer results in a mixture of functionalized entities at the end of the chain and in the middle of the chain, which constitute the linear chains of the functionalized diene elastomer and also, if appropriate, star-branched entities. Depending on operating conditions, primarily the molar ratio of functionalizing agent to live chains, certain entities are predominant in the mixture.

[00124] Preferably, the functionalized diene elastomer comprises at least one polar function comprising at least one oxygen atom.

[00125] Preferably, the polar function may be selected from the group consisting of silanol, alkoxysilanes, alkoxysilanes containing an amino group, epoxide, ethers, esters, carboxylic acids and hydroxyl. The polar function especially improves the interaction between the reinforcing inorganic filler and the elastomer. Such functionalized elastomers are known per se and are described especially in the following documents: FR2740778, US6013718, WO2008/141702, FR2765882, WO01/92402, WO2004/09686, EP1127909, US6503973, WO2009/000750 and WO 2009 /000752.

[00126] The functionalized diene elastomer is preferably a diene elastomer comprising a polar function which is a silanol.

[00127] Preferably, the silanol is located at the end of the chain or in the middle of the chain of the main chain of the functionalized diene elastomer. More preferably, the silanol is located at the backbone end of the functionalized diene elastomer.

[00128] Preferably, the functionalized diene elastomer is a diene elastomer (especially an SBR) in which the silanol function is located at the end of the chain. This functionalized diene elastomer comprises, at one end of its main chain, a silanol function or a polysiloxane group having a silanol end of the formula - (SiR1R2-O-)mH where m represents an integer with a value that if it ranges from 3 to 8, preferably 3, R1 and R2, which are the same or different, represent an alkyl radical having 1 to 10 carbon atoms, preferably an alkyl radical having 1 to 4 carbon atoms.

[00129] This type of elastomer can be obtained according to the processes described in EP0778311 and, more particularly, according to the process that consists, after an anionic polymerization step, in functionalizing the living elastomer with a functionalizing agent of the cyclic polysiloxane type, provided that the reaction medium does not allow polymerization of the cyclopolysiloxane. As cyclic polysiloxanes, mention may be made of those corresponding to formula (V):

[00130] where m represents an integer with a value ranging from 3 to 8, preferably 3, and R1 and R2, which are identical or different, represent an alkyl radical with 1 to 10 carbon atoms, preferably an alkyl radical which has 1 to 4 carbon atoms. Among these compounds mention may be made of hexamethylcyclotrisiloxane.

[00131] More preferably, the functionalized diene elastomer is a diene elastomer (especially an SBR) comprising, at one end of the main chain thereof, a silanol function or a polysiloxane group having a silanol end of formula -( SiR1R2-O-)mH where m represents an integer with a value equal to 3, preferably 3, R1 and R2, which are identical or different, represent an alkyl radical having 1 to 4 carbon atoms.

[00132] Preferably, the functionalized diene elastomer (especially the SBRs) comprises a polar function that is an alkoxysilane that contains, or does not contain, another function (or that contains another chemical group, where these expressions are synonymous).

[00133] Preferably, this functionalized diene elastomer comprises, within its main chain, at least one alkoxysilane group linked to the elastomer chain by the silicon atom and which, optionally, contains at least one other function.

[00134] According to some variants, the alkoxysilane group (carrying or not carrying another function) is located at one end of the main chain of the elastomer (chain end).

[00135] According to other variants, the alkoxysilane group (carrier or not of another function) is located in the main chain of elastomers (middle of the chain). The silicon atom of this function links the two main chain branches of the diene elastomer.

[00136] The alkoxysilane group (which does or does not contain another function) comprises a C1-C10 alkoxy radical, optionally partially or totally hydrolyzed to give hydroxyl, or even a C1-C8 alkoxy radical, preferably C1-C4, and is more preferably methoxy and ethoxy.

[00137] The other function is preferably supported by silicon of the alkoxysilane group, directly or through a spacer group, defined as a radical or atom based on an aliphatic C1-C18 hydrocarbon, linear or branched, divalent, cyclic or non-cyclic, saturated or unsaturated or a divalent aromatic C6-C18 hydrocarbon-based radical.

[00138] The other function is preferably a function comprising at least one heteroatom chosen from N, S, O or P. Mention may be made, by way of example, among these functions, of primary, secondary or tertiary, cyclic or non-cyclic, isocyanates, imines, cyanos, thiols, carboxylates, epoxides or primary, secondary or tertiary phosphines.

[00139] Mention can thus be made, as a secondary or tertiary amine function, of amines substituted by C1-C10 alkyl radicals, preferably C1C4, more preferably a methyl or ethyl radical, or else cyclic amines that form a heterocycle containing a nitrogen atom and at least one carbon atom, preferably from 2 to 6 carbon atoms. For example, the methylamino-, dimethylamino-ethylamino-, diethylamino-, propylamino-, dipropylamino-, butylamino-, dibutylamino-, pentylamino-, dipentylamino-, hexylamino-, dihexylamino- or hexamethylenamino- groups, preferably the diethylamino- groups and dimethylamino- are suitable.

[00140] Mention may be made, as an imine function, of ketimines. For example, (1,3-dimethylbutylidene)amino-, (ethylidene)mino-, (1-methylpropylidene)amino-, (4-N,N-dimethylaminobenzylidene)amino-, (cyclohexylidene)amino-, di -hydroimidazole and imidazole are suitable.

[00141] Thus, mention may be made, as a carboxylate function, of acrylates or methacrylates. This function is preferably a methacrylate.

[00142] Mention may be made, as an epoxide function, of the epoxy or glycidyloxy groups.

[00143] Mention may be made, as a secondary or tertiary phosphine function, of phosphines substituted by C1-C10 alkyl radicals, preferably C1-C4, more preferably a methyl or ethyl radical, or else diphenylphosphine. For example, methylphosphino-, dimethylphosphino-ethylphosphino-, diethylphosphino-, ethylmethylphosphino- and diphenylphosphino- groups are suitable.

[00144] Preferably, the other function is preferably a tertiary amine, more preferably a diethylamino- or dimethylamino- group.

[00145] Preferably, the functionalized diene elastomer (especially an SBR) may comprise a polar function which is an alkoxysilane that does or does not contain an amino group.

[00146] Preferably, the alkoxysilane group that contains, or does not contain, an amino group is located at the chain end or in the middle of the chain of the main chain of the functionalized diene elastomer. More preferably, the alkoxysilane group containing, or not containing, the amino group is located mid-chain of the backbone of the functionalized diene elastomer.

[00147] Preferably, the amino group is a tertiary amine.

[00148] Preferably, the alkoxysilane group can be represented by formula (VI):

[00149] in which: • *— represents binding to an elastomer chain; • the radical R represents a C 1 -C 10 alkyl radical, or even a substituted or unsubstituted C1-C8 alkyl radical, preferably a C1-C4, more preferably methyl and ethyl; • in the alkoxyl radical (or radicals) of the formula -OR', which is optionally partially or totally hydrolyzed to give hydroxyl, R' represents a C1-C10, or even C1-C8, preferably a C1-C4, substituted alkyl radical or unsubstituted, more preferably methyl and ethyl; • X represents a group that includes the other role; • a is 1 or 2, b is 1 or 2, and c is 0 or 1, with the proviso that a+b+c = 3.

[00150] More preferably, the functionalized diene elastomer is a diene elastomer (especially an SBR) comprising, within the main chain thereof, at least one alkoxysilane group of formula (VI), wherein: • *— represents the bonding to an elastomer chain; • radical R represents a substituted or unsubstituted C1-C4 alkyl radical, more preferably methyl and ethyl; • in the alkoxy radical (or radicals) of the formula -OR', which optionally is partially or totally hydrolyzed to give hydroxyl, R' represents a substituted or unsubstituted C1-C4 alkyl radical, more preferably methyl and ethyl; • X represents a group that includes the other role; preferably a tertiary amine; • a is 1 or 2, b is 1 or 2, and c is 0 or 1, with the proviso that a+b+c = 3.

[00151] This type of elastomer is obtained mainly by the functionalization of a living elastomer resulting from an anionic polymerization. It should be specified that it is known to those skilled in the art that, when an elastomer is modified by reaction of a functionalizing agent with the living elastomer resulting from an anionic polymerization step, a mixture of modified entities of that elastomer is obtained, whose composition depends on the conditions of the modification reaction and especially on the ratio of reactive sites of the functionalizing agent to the number of chains of living elastomers. This mixture comprises entities that are chain-end functionalized, coupled, star-branched, and/or non-functionalized.

[00152] According to a particularly preferred variant, the modified diene elastomer comprises, as the predominant entity, the diene elastomer functionalized in the middle of the chain by an alkoxysilane group linked to the two branches of the diene elastomer by means of the silicon atom. Even more particularly, the diene elastomer functionalized in the middle of the chain by an alkoxysilane group represents 70% by weight of the modified diene elastomer.

[00153] These functionalized elastomers can be used as a blend (blend) with each other or with non-functionalized elastomers.

[00154] The rubber compositions according to the invention may contain only one diene elastomer, functionalized or not, or a mixture of several diene elastomers, functionalized or not, it being possible for the diene elastomer (or elastomers) to be used in combination with any type of synthetic elastomer other than a diene elastomer or even with polymers other than elastomers, eg thermoplastic polymers. - Reinforcement inorganic filler

[00155] The term "inorganic reinforcing filler" should be understood here as meaning, in a known manner, any inorganic or mineral filler, regardless of its color and origin (natural or synthetic), also known as "white filler", " light filler" or else "non-black filler", in contrast to carbon black, as this inorganic material is capable of reinforcing, by itself, without other means than an intermediate coupling agent, a rubber composition specially intended for the manufacture of semi-finished products for tires or tyres, in other words capable of replacing, in its reinforcing role, a conventional tire carbon black for rubber compositions, intended especially for the manufacture of semi-finished products for tires or tires. This charge is generally characterized by the presence of functional groups, especially hydroxyl (OH) functional groups on its surface, which require, in this regard, the use of a coupling agent or system intended to provide a stable chemical bond between the elastomer and said load.

[00156] The inorganic wear-reinforcing filler in the rubber compositions according to the invention comprises at least one silica S that has: - a specific surface area of CTAB SCTAB within a range extending from 40 to 300 m2/ g; - a difference between the specific surface area of BET SBET and the specific surface area of CTAB SCTAB greater than or equal to 35 m2/g; - a WAl aluminum content within a range extending from 0.5 to 7.0% by weight relative to the weight of silica S; - a breadth of aggregate size distribution Ld, measured by centrifugal sedimentation, greater than or equal to 1.5; e- an average aggregate diameter d50, measured by centrifugal sedimentation, so that, for a given CTAB SCTAB specific surface area value and a given WAl aluminum content, a magnitude A is defined by the following equation (I):

[00157] where: [d50] is the numerical value of d50, expressed in nm; [SCTAB] is the numerical value of SCTAB, expressed in m2/g; [WAl] is the numerical value of WAl, expressed in % by weight in relation to the weight of silica S; It is

[00158] said magnitude A satisfies the relation (II): A > 253 (II).

[00159] Preferably, the inorganic load reinforcing use in the rubber compositions according to the invention comprises at least one S silica capable of being obtained by a preparation process, said process comprising the following steps: having a starting solution with a pH within a range extending from 2.00 to 5.00; adding to said initial solution, simultaneously, a silicate and an acid, so that the pH of the reaction medium is maintained in a range extending from 2.00 to 5.00; stopping the addition of the acid, while continuing the addition of the silicate to the reaction medium until a pH value for said reaction medium within a range extending from 7.00 to 10.00 is obtained; adding to the reaction medium, simultaneously, at least an aluminum compound, a silicate and an acid, so that the pH of the reaction medium is maintained in a range that extends from 7.00 to 10.00; stopping the addition of the silicate and said at least one aluminum compound, while continuing the addition of the acid to the reaction medium until a pH value for the reaction medium of less than 6.0 is obtained, and obtaining a silica suspension S precipitated; - said silica S, especially having an average aggregate diameter d50, measured by centrifugal sedimentation, so that, for a given value of the specific surface area of CTAB SCTAB and a given WAl aluminum content, a magnitude A is defined by the following equation (I):

[00160] where: [d50] is the measured numerical value of d50, expressed in nm; [SCTAB] is the numerical value of SCTAB, expressed in m2/g; [WAl] is the numerical value of WAl, expressed in % by weight in relation to the weight of silica S; It is

[00161] said magnitude A satisfies the relation (II): A > 253 (II).

[00162] For the sake of brevity in the remainder of the present application, silicas having the characteristics defined above (including the preferred modes of said characteristics, as defined below) and also silicas obtained, or capable of being obtained, by the defined process above (including preferred modes of said process, as defined below) are termed "Silica (or silicas)".

[00163] The specific surface area of CTAB SCTAB is the external specific surface area, as determined by measuring the amount of N-hexadecyl-N,N,N-trimethylammonium bromide adsorbed on the silica surface at a given pH; which measurement is described above.

[00164] The CTAB SCTAB specific surface area of silica S is greater than or equal to 40 m2/g, more preferably greater than or equal to 60 m2/g. Preferably, the SCTAB can be greater than or equal to 70 m2/g. Even more preferably, the SCTAB can be greater than or equal to 110 m2/g, greater than or equal to 120 m2/g, or even greater than or equal to 130 m2/g.

[00165] The SCTAB of silica S is less than or equal to 300 m 2 /g, preferably less than or equal to 280 m 2 /g, even more preferably less than or equal to 270 m 2 /g.

[00166] Preferably, the SCTAB of silica S, which has proven to be advantageous for the compositions according to the invention, may be within a range extending from 70 to 300 m2/g, from 80 to 300 m2/g, from 110 at 300 m2/g, from 120 to 300 m2/g; 130 to 280 m2/g.

[00167] The difference between the specific surface areas of BET and CTAB (denoted in the remainder of the description as SBET and SCTAB) is generally considered to be representative of the microporosity of a silica, insofar as it constitutes a measure of the pores of the silica. which are accessible to nitrogen molecules, but not to larger molecules such as N-hexadecyl-N,N,N-trimethylammonium bromide.

[00168] Silica S has an SBET-SCTAB difference greater than or equal to 35 m2/g. Preferably, the SBET-SCTAB of silica S is greater than or equal to 40 m2/g, more preferably greater than or equal to 45 m2/g, most preferably greater than or equal to 50 m2/g, even more preferably greater than or equal to 55 m2 /g and even greater than or equal to 60 m2/g. SBET-SCTAB difference values are not limited. In general, the S-silica SBET-SCTAB difference may be less than or equal to 150 m2/g, preferably less than or equal to 100 m2/g. The SBET-SCTAB especially does not exceed 300 m2/g.

[00169] Preferably, the SBET-SCTAB difference is within a range extending from 50 to 300 m2/g, more preferably from 55 to 150 m2/g.

[00170] The specific surface area of BET SBET of silica S is not particularly limited, but it is at least 35 m2/g greater than the specific surface area value of CTAB SCTAB. The SBET of silica S is preferably greater than or equal to 80 m2/g, preferably greater than or equal to 100 m2/g, preferably greater than or equal to 140 m2/g, preferably greater than or equal to 160 m2/g, preferably greater than or equal to to 170 m2/g, more preferably greater than or equal to 180 m2/g. Preferably, the SBET is less than or equal to 450 m2/g, more preferably less than or equal to 400 m2/g.

[00171] Silica S may have the following preferred combinations of specific surface areas: a SCTAB within a range extending from 70 to 300 m2/g and an SBET within a range extending from 110 to 450 m2/g ; a SCTAB within a range extending from 110 to 300 m2/g and an SBET within a range extending from 160 to 450 m2/g; a SCTAB within a range extending from 110 to 300 m2/g and an SBET within a range extending from 180 to 450 m2/g; a SCTAB within a range extending from 120 to 300 m2/g and an SBET within a range extending from 200 to 450 m2/g.

[00172] Silica S comprises aluminum. The aluminum content (WAl) of the S silica is within a range extending from 0.5 to 7.0% by weight, preferably from 0.5 to 5.0% by weight. Throughout this document, WAl aluminum content is defined as the Al content by weight relative to the weight of silica S. WAl is determined (measured) by inductively coupled plasma atomic emission spectroscopy (ICP-AES) as described above.

[00173] WAl is preferably greater than or equal to 0.8% by weight and preferably greater than or equal to 1.0% by weight. More preferably, the WAl can be within a range extending from 0.8 to 3.5% by weight, and even from 1.0 to 3.0% by weight.

[00174] It should be recognized that S silica may contain elements other than aluminum; non-limiting examples of other elements are especially Mg, Ca or Zn.

[00175] It has been observed that compared to a precipitated silica having the same SCTAB, S silica has a superior aggregate size distribution and provides rubber compositions containing it with an improved compromise of wear resistance performance properties. bearing/wear resistance.

[00176] Silica S has a breadth of aggregate size distribution Ld, measured by centrifugal sedimentation, greater than or equal to 1.5, preferably greater than or equal to 1.6. Preferably, the breadth of the aggregate size distribution Ld, as measured by centrifugal sedimentation, may be less than or equal to 4, for example less than or equal to 3.5.

[00177] Preferably, the amplitude of the aggregate size distribution Ld of the S silica, measured by centrifugal sedimentation, is within a range extending from 1.5 to 3.5, preferably from 1.5 to 3.2. Even more preferably, the amplitude of the S-silica Ld aggregate size distribution, as measured by centrifugal sedimentation, is within a range extending from 1.5 to 3.0, preferably from 1.5 to 2.5.

[00178] S silicas have a high mean aggregate diameter d50, measured by centrifugal sedimentation, for a given SCTAB value. It is known that the size of the silica aggregates and the surface area of the silica are inversely proportional to each other: the size of the aggregates decreases when the specific surface area, especially the SCTAB, increases.

[00179] In particular, it was observed that the silicas used in the rubber compositions according to the invention have an average aggregate diameter d50, measured by centrifugal sedimentation, which is significantly larger than the prior art silicas containing aluminum, to given SCTAB specific surface area value and for a given WAl aluminum content. This axiom is expressed by the magnitude A, which satisfies the following relation (II): A > 253 (II); where A is a unitless number and is defined by equation (I): A = [d50] + 0.782 x [SCTAB] - 8.524 x [WA1] (i)

[00180] where: [d50] is the numerical value of d50, expressed in nm; [SCTAB] is the numerical value of SCTAB, expressed in m2/g; [WAl] is the numerical value of WAl, expressed in % by weight in relation to the weight of S silica.

[00181] In equation (I), [d50] is unitless. For example, if the measured value of d50, as measured by centrifugal sedimentation, is 16 nm, then the numerical value of d50 is 16 and therefore [d50] = 16.

[00182] In equation (I), [SCTAB] is unitless. For example, if the measured value of SCTAB is 200 m2/g, the numerical value of SCTAB is 200 and therefore [S CTAB] = 200.

[00183] In equation (I), [WAl] is unitless. For example, if the measured value of WAl is 1.3% by weight of the weight of silica S, then the numerical value of WAl is 1.3 and therefore [WAl] = 1.3.

[00184] The magnitude A is a unitless number that, for silica S, is greater than or equal to 253.

[00185] Preferably, the magnitude A is less than or equal to 300. The preferred values for the magnitude A can be: A > 253, A > 255, A > 258, A > 259, A > 260.

[00186] Preferably, the ratio (II) may be 253 < A < 298 (IIa).

[00187] Preferably, the ratio (II) may be 255 < A < 297 (IIb).

[00188] Preferably, the ratio (II) may be 255 < A < 288 (IIc).

[00189] Preferably, the ratio (II) may be 258 < A < 285 (IId).

[00190] Preferably, the ratio (II) may be 259 < A < 285 (IIe).

[00191] Preferably, the ratio (II) can be 259 < A < 300 (IIf).

[00192] Preferably, when the SCTAB is within the range extending from 40 to 300 m2/g, the silica S has an average aggregate diameter d50, measured by centrifugal sedimentation, greater than or equal to 30 nm.

[00193] Preferably, when WAl is within the range extending from 0.8 to 3.0% by weight and the CTAB surface area is within the range extending from 70 to 280 m2/g, the values Typical d50 average aggregate diameters are generally greater than or equal to 65 nm, even greater than or equal to 70 nm, and even greater than or equal to 80 nm.

[00194] Preferably, d50 of silica S is less than or equal to 320 nm, more preferably it is less than or equal to 300 nm.

[00195] In an advantageous embodiment, the reinforcing inorganic filler comprises a silica S having: - a SCTAB within the range extending from 40 to 300 m2/g; - an SBET-SCTAB difference greater than or equal to 35 m2/g; - an aluminum content (WAl) within the range extending from 0.5 to 5.0% by weight; - a breadth of aggregate size distribution Ld, measured by centrifugal sedimentation, greater than or equal to 1.5; and - an average aggregate diameter d50, measured by centrifugal sedimentation, so that, for a given CTAB SCTAB specific surface area value and a given WAl aluminum content, a magnitude A is defined by the following equation (I):

[00196] where: [d50] is the numerical value of d50, expressed in nm; [SCTAB] is the numerical value of SCTAB, expressed in m2/g; [WAl] is the numerical value of WAl, expressed in % by weight in relation to the weight of silica S; It is

[00197] said magnitude A satisfies the relation (II):

[00198] In another advantageous embodiment, the reinforcing inorganic filler comprises a silica S that has: - a SCTAB within the range extending from 70 to 300 m2/g; - an SBET-SCTAB difference greater than or equal to 50 m2/g; - an aluminum content (WAl) within the range extending from 0.5 to 5.0% by weight; - a breadth of the Ld aggregate size distribution, measured by centrifugal sedimentation, within the range extending from 1.5 to 3.5; and - an average aggregate diameter d50, measured by centrifugal sedimentation, so that, for a given CTAB SCTAB specific surface area value and a given WAl aluminum content, a magnitude A is defined by the following equation (I):

[00199] where: - d50] is the numerical value of d50, expressed in nm; - SCTAB] is the numerical value of SCTAB, expressed in m2/g; [WAl] is the numerical value of WAl, expressed in % by weight in relation to the weight of silica S; It is

[00200] said magnitude A satisfies the relation (II):

[00201] In another advantageous embodiment, the reinforcing inorganic filler comprises a silica S that has: - a SCTAB within the range extending from 110 to 300 m2/g; - an SBET-SCTAB difference greater than or equal to 50 m2/g; - an aluminum content (WAl) within the range extending from 0.8 to 5.0% by weight; - a breadth of the Ld aggregate size distribution, measured by centrifugal sedimentation, within the range extending from 1.5 to 3.5; and - an average aggregate diameter d50, measured by centrifugal sedimentation, so that, for a given CTAB SCTAB specific surface area value and a given WAl aluminum content, a magnitude A is defined by the following equation (I): A = [d50] + 0.782 x [SCTAB] - 8.524 x [WA1] (i)

[00202] where: [d50] is the numerical value of d50, expressed in nm; - SCTAB] is the numerical value of SCTAB, expressed in m2/g; [WAl] is the numerical value of WAl, expressed in % by weight in relation to the weight of silica S; It is

[00203] said magnitude A satisfies the relation (II): 259 < A < 300 (Ilf).

[00204] In an additional advantageous embodiment, the reinforcing inorganic filler comprises a silica S that has: - a SCTAB within a range extending from 110 to 300 m2/g; - an SBET-SCTAB difference greater than or equal to 50 m2/g; - an aluminum content (WAl) within a range extending from 0.8 to 3.0% by weight; - a breadth of the Ld aggregate size distribution, measured by centrifugal sedimentation, within a range extending from 1.5 to 2.5; and - an average aggregate diameter d50, measured by centrifugal sedimentation, so that, for a given CTAB SCTAB specific surface area value and a given WAl aluminum content, a magnitude A is defined by the following equation (I): A = [d50] + 0.782 x [SCTAB] - 8.524 x [WA1] (i)

[00205] where: [d50] is the numerical value of d50, expressed in nm; - SCTAB] is the numerical value of SCTAB, expressed in m2/g; [WAl] is the numerical value of WAl, expressed in % by weight in relation to the weight of silica S; It is

[00206] said magnitude A satisfies the relation (II): 259 < A < 300 (IIf).

[00207] In an additional advantageous embodiment, the reinforcing inorganic filler comprises a silica S that has: - a SCTAB within the range extending from 110 to 300 m2/g; - an SBET within a range extending from 180 m2/g to 450 m2/g; - an SBET-SCTAB greater than or equal to 50 m 2/g; - an aluminum content (WAl) within the range extending from 0.8 to 3.0% by weight; - a breadth of the Ld aggregate size distribution, measured by centrifugal sedimentation, within a range extending from 1.5 to 2.5; and - an average aggregate diameter d50, measured by centrifugal sedimentation, so that, for a given CTAB SCTAB specific surface area value and a given WAl aluminum content, a magnitude A is defined by the following equation (I): A = [d50] + 0.782 x [SCTAB] - 8.524 x [WA1] (i)

[00208] where: [d50] is the numerical value of d50, expressed in nm; [SCTAB] is the numerical value of SCTAB, expressed in m2/g; [WAl] is the numerical value of WAl, expressed in % by weight in relation to the weight of silica S; It is

[00209] said magnitude A satisfies the relation (II): A > 253 (II).

[00210] These S silicas are preferably obtained, or capable of being obtained, by a process for preparing precipitated silica as described below, which includes all preferred modes and variants of said process. Silica S is a precipitated silica.

[00211] The process for preparing precipitated silica S comprises the following steps:

[00212] have available an initial solution with a pH within a range extending from 2.00 to 5.00;

[00213] add to said initial solution, simultaneously, a silicate and an acid, so that the pH of the reaction medium is maintained in a range that extends from 2.00 to 5.00;

[00214] stop adding the acid, while continuing to add the silicate to the reaction medium until a pH value is obtained for said reaction medium within a range extending from 7.00 to 10.00;

[00215] add to the reaction medium, simultaneously, at least one aluminum compound, a silicate and an acid, so that the pH of the reaction medium is maintained in a range that extends from 7.00 to 10.00;

[00216] stop adding the silicate and said at least one aluminum compound, while continuing to add the acid to the reaction medium until a pH value for the reaction medium less than 6.0 is obtained, and obtain a suspension of precipitated S silica.

[00217] In the present description, the term "silicate" is used to denote one or more silicates that may be added during said process. The silicate may be selected from the group consisting of alkali metal silicates.

[00218] Preferably, the silicate is selected from the group consisting of sodium silicate and potassium silicate. The silicate may be in any known form, such as metasilicate or disilicate.

[00219] In the case where sodium silicate is used, the latter generally has a SiO2/Na2O weight ratio within a range extending from 2.0 to 4.0, in particular from 2.4 to 3, 9, for example from 3.1 to 3.8.

[00220] The silicate may have a concentration (expressed as % by weight relative to SiO2) within a range extending from 3.9% to 25.0% by weight, for example from 5.6% to 23, 0% by weight, in particular from 5.6% to 20.7%.

[00221] In the present description, the term "acid" is used to denote one or more acids that may be added during said process. The process can be carried out with any type of acid known to those skilled in the art. As the acid, generally an inorganic acid such as sulfuric acid, nitric acid or hydrochloric acid, or an organic acid such as acetic acid, formic acid or carbonic acid is used. Preferably, the acid is selected from the group consisting of sulfuric acid, nitric acid or hydrochloric acid; more preferably, the acid is sulfuric acid.

[00222] The acid added precisely to the reaction medium can be in diluted or concentrated form. The same acid can be used at different stages of the process, in identical or different concentrations at different stages. Preferably, the acid is sulfuric acid.

[00223] In a preferred embodiment of the process, for all process steps, the acid is sulfuric acid and the silicate is sodium silicate. Preferably, the same sodium silicate having the same concentration (expressed as % by weight relative to SiO2) is used in all process steps.

[00224] In step (i) of the process, an initial solution with a pH within a range extending from 2.00 to 5.00 is made available and introduced into the reactor. The starting solution is an aqueous solution. The term "aqueous" indicates that the solvent is water.

[00225] Preferably, the initial solution has a pH within a range extending from 2.50 to 5.00, in particular from 3.00 to 4.50; for example, from 3.50 to 4.50.

[00226] The initial solution can be obtained by adding acid to water in order to obtain a pH value of the initial aqueous solution within a range extending from 2.50 to 5.00, in particular from 3.00 to 4.50; for example, from 3.50 to 4.50.

[00227] Alternatively, the starting solution may contain a silicate. Therefore, it can also be obtained by adding acid to a mixture of water and silicate, in order to obtain a pH within a range extending from 2.00 to 5.00, in particular from 3.00 to 4 ,50; for example, from 3.50 to 4.50.

[00228] The initial solution can also be prepared by adding acid to a solution containing previously formed silica particles at a pH lower than 7.00, in order to obtain a pH value within a range that extends from 2 .00 to 5.00, preferably from 2.50 to 5.00, in particular from 3.00 to 4.50, for example from 3.50 to 4.50.

[00229] The initial solution of step (i) may or may not comprise an electrolyte. Preferably, the initial aqueous solution of step (i) comprises an electrolyte which does not contain aluminum.

[00230] The term "electrolyte" is understood herein in its generally accepted meaning, namely that it means any ionic or molecular substance which, when in solution, breaks down or dissociates to form ions or charged particles. The term "electrolyte" is used in the present description to indicate one or more electrolytes that may be present. Mention may be made, as the use electrolyte in the initial aqueous solution, of salts selected from the group consisting of alkali metal salts and alkaline earth metal salts. Preferably, the electrolyte used in the starting aqueous solution is a metal salt of the starting silicate and the acid that are used in the process. Notable examples of such salts are especially sodium chloride in the case of the reaction of a sodium silicate with hydrochloric acid or sodium sulfate in the case of the reaction of a sodium silicate with sulfuric acid. Preferably, the electrolyte is sodium sulfate.

[00231] Preferably, when sodium sulfate is used as the electrolyte in step (i), its concentration in the initial aqueous solution is within a range extending from 8 to 40 g/l, in particular from 10 to 35 g/l l, for example, from 13 to 30 g/l.

[00232] Step (ii) of the process comprises the simultaneous addition of an acid and a silicate to the initial solution. The amounts of acid and silicate added during step (ii) are regulated so that the pH of the reaction medium is maintained in a range extending from 2.00 to 5.00, more preferably it is maintained in a range that extends from 2.00 to 5.00. extends from 2.50 to 5.00, in particular held from 3.00 to 5.00, for example held in a range extending from 3.20 to 4.80.

[00233] This simultaneous addition in step (ii) is advantageously carried out so that the pH value of the reaction medium is constantly equal to the pH reached at the end of step (i), ± 0.20 pH unit.

[00234] Preferably, step (ii) consists of the simultaneous addition of acid and silicate to the initial solution, as described in detail below.

[00235] In one embodiment of the process, an intermediate step (ii') can be performed between step (i) and step (ii), in which a silicate and an acid are added to the initial solution, so that the pH of the reaction medium is maintained within a range extending from 2.00 to 9.50. The addition of silicate and acid can be simultaneous throughout or only part of step (ii'). Step (ii') is typically extended for 1 to 10 minutes, preferably 2 to 8 minutes, before step (ii) is started.

[00236] Then, in step (iii), the addition of the acid is stopped while continuing the addition of the silicate to the reaction medium. Acid addition is stopped when the pH of the reaction medium is within a range extending from 7.00 to 10.00, preferably from 7.50 to 9.50.

[00237] At the end of step (iii), that is, after stopping the addition of silicate, it may be advantageous to carry out a maturation step of the reaction medium. This maturation step of the reaction medium is preferably carried out at the pH obtained at the end of step (iii). The maturation step can be carried out under agitation of the reaction medium. The maturation step is preferably carried out under stirring of the reaction medium for a period of 2 to 45 minutes, in particular 5 to 25 minutes. Preferably, the maturing step does not comprise any addition of acid or silicate.

[00238] After step (iii) and the optional maturation step, the simultaneous addition of at least one aluminum compound, an acid and a silicate is carried out, so that the pH of the reaction medium is maintained in a range that extends from 7.00 to 10.00, preferably from 7.50 to 9.50.

[00239] This simultaneous addition of at least one aluminum compound, an acid and a silicate (step (iv)) is preferably carried out so that the pH value of the reaction medium is constantly equal to the pH reached at the end of the previous step , step (iii), ± 0.20 pH unit.

[00240] It should be noted that said process may comprise additional steps. For example, between step (iii) and step (iv), on the one hand, and between the optional maturation step after step (iii) and step (iv), on the other hand, an acid can be added to the medium of reaction. After this addition of acid, the pH of the reaction medium must remain within a range extending from 7.00 to 9.50, preferably from 7.50 to 9.50.

[00241] In step (v), the addition of the silicate and said at least one aluminum compound is stopped, while the addition of acid to the reaction medium continues, so as to obtain a pH value in the reaction medium of less than 6.00, preferably within a range extending from 3.00 to 5.50, in particular from 3.00 to 5.00. A precipitated silica suspension is obtained in the reactor.

[00242] At the end of step (v) and consequently after stopping the addition of acid to the reaction medium, a maturation step can advantageously be carried out. This maturation step of the reaction medium is preferably carried out at the pH obtained at the end of step (iv). The maturation step can be carried out under agitation of the reaction medium. The maturation step is preferably carried out under stirring of the reaction medium for a period of 2 to 45 minutes, in particular 5 to 25 minutes. Preferably, the maturing step does not comprise any addition of acid or silicate.

[00243] At least one aluminum compound is added precisely to the reaction medium during step (iv), that is, during the simultaneous addition of an acid and a silicate to the reaction medium at a pH within a range that extends from 7.00 to 10.00. Said at least one aluminum compound can be added precisely to the reaction medium throughout the entire duration of step (iv), i.e. at the same time as the acid and silicate addition. As a variant, it can be added precisely during only part of step (iv), for example only after the first simultaneous addition of acid and silicate.

[00244] The expression "at least one aluminum compound" is used to denote one or more aluminum compounds that may be added during said process.

[00245] Any known aluminum compound can be useful in said process, as long as it is soluble in water. Notable examples of suitable aluminum compounds may be, without limitation, aluminum chlorides, sulfates or nitrites or alkali metal aluminates. Preferably, the aluminum compound is selected from the group consisting of alkali metal aluminates. Preferably, the aluminum compound is selected from the group consisting of potassium aluminate and sodium aluminate. Even more preferably, the aluminum compound is sodium aluminate.

[00246] The reactor in which the entire reaction of the silicate with the acid is carried out is usually equipped with a suitable stirring apparatus and a suitable heating apparatus.

[00247] The entire reaction of the silicate with the acid (steps (i) to (v)) is generally carried out at a temperature within a range extending from 40 to 97 °C, in particular from 60 to 95 °C , preferably 80 to 95°C, more preferably 85 to 95°C.

[00248] According to a variant of the invention, the entire reaction of the silicate with the acid is carried out at a constant temperature, preferably within a range extending from 40 to 97 °C, in particular from 80 to 95 °C, more preferably from 85 to 95°C.

[00249] According to another variant of the invention, the final reaction temperature is higher than the initial reaction temperature: thus, the temperature is maintained at the beginning of the reaction (for example, throughout steps (i) to ( iii)), preferably within a range extending from 40 to 85 °C, then the temperature is increased, preferably to a value within a range extending from 80 to 95 °C, preferably from 85 to 95 °C , value at which it is maintained (for example, throughout steps (iv) and (v)) until the end of the reaction.

[00250] It was found that the succession of these specific steps, in particular the presence of a first simultaneous addition of acid and silicate at a pH within a range extending from 2.00 to 5.00 and the simultaneous addition of a compound of aluminum, acid and silicate at a pH within a range extending from 7.00 to 10.00 constitutes important conditions for obtaining a precipitated silica with the claimed characteristics and, in particular, aggregate size distribution high and average aggregate diameter d50. The different process parameters such as, for example, the temperature, the pH of the reaction medium, the amount of electrolyte in step (i) and the amount of aluminum compound can be modified to obtain precipitated silicas that have the required values of CTAB SCTAB specific surface area, BET SBET specific surface area and WAl aluminum content.

[00251] At the end of the steps just described, a silica paste is obtained, which is then separated (liquid-solid separation). Preferably, the process for preparing the silica also comprises a step (vi) in which said suspension is filtered and the precipitated silica is dried.

[00252] The separation carried out in said preparation process usually comprises filtration followed by washing, if necessary. Filtration is carried out according to any known method, for example by means of a filter press, belt filter, vacuum filter or rotary filter, preferably by means of a filter press. At the end of this step, a filter cake is obtained.

[00253] The filter cake is then subjected to a disintegration operation. The term "disintegration" in the present case is intended to denote a process in which a solid, namely the filter cake, is converted into a fluid. After the disintegration step (also called fluidization or liquefaction operation), the filter cake is in a fluid-like fluid form and the precipitated silica is in suspension again.

[00254] In a variant, the disintegration step may comprise a mechanical treatment that causes a reduction in the particle size of the suspended silica. Said mechanical treatment can be carried out by passing the filter cake through a high shear mixer, such as a colloidal type mill or a ball mill. In another variant, the disintegration step may comprise a chemical treatment. The filter cake is then subjected to chemical action by adding, for example, an acid or an aluminum compound, different or identical to that used in step (iv) of the process. The aluminum compound used in the disintegration step is preferably identical to that used in step (iv) of the process and is, for example, sodium aluminate or potassium aluminate, even more preferably sodium aluminate. In yet another variant, the disintegration step can comprise a mechanical treatment and a chemical treatment.

[00255] When an aluminum compound is added to the filter cake during the disintegration operation, the amount is generally such that the weight ratio between the aluminum compound and the amount of silica, expressed as SiO2, present in the filter cake is within a range extending from 0.10% to 0.75%, preferably from 0.10% to 0.50% by weight, more preferably from 0.20% to 0.45% by weight.

[00256] Regardless of the stage at which an aluminum compound is added, the accumulated amount of said aluminum compound added precisely to the reaction medium and during the chemical disintegration step is such that the aluminum content in the precipitated silica S is within a range extending from 0.5 to 7.0% by weight relative to the weight of the silica, preferably from 0.8 to 3.5% by weight, and even from 1.0 to 3.0% by weight relative to the weight of silica. The content of aluminum compound added during the chemical disintegration step can be adapted to obtain the desired aluminum content in the precipitated silica S by means known to those skilled in the art.

[00257] Preferably, the S precipitated silica suspension that is obtained after the disintegration step is then dried.

[00258] This drying can be carried out by any means known per se.

[00259] Preferably, drying is carried out by spray drying. For this purpose, any suitable type of atomizer can be used, especially a rotary, nozzle, liquid pressure or two-fluid atomizer. Generally, when filtration is performed using a filter press, a nozzle atomizer is used, and when filtration is performed using a vacuum filter, a rotary atomizer is used.

[00260] When drying is carried out using a nozzle atomizer, the S silica able to be obtained is usually in the form of substantially spherical granules. At the end of this type of drying, a milling or micronization step of the recovered product can be performed. The silica S which is then able to be obtained is generally in the form of a powder.

[00261] When drying is carried out using a rotary atomizer, the silica S which is then able to be obtained may be in the form of a powder.

[00262] Finally, the product dried (especially by a rotary atomizer) or milled or micronized as indicated above can optionally be subjected to an agglomeration step, which consists, for example, of direct compression, wet granulation (i.e. with the use of a binder such as water, silica suspension, etc.), extrusion or, preferably, dry compaction. The silica S capable of then being obtained by this agglomeration step is generally in the form of granules.

[00263] Preferably, the S silica can optionally be combined with at least one additional silica in the rubber compositions according to the invention. In other words, the reinforcing inorganic filler also comprises an additional silica other than S-silica.

[00264] In this case, the content of each of these silicas can be within a range that extends from 1 to 99% by weight in relation to the total weight of the inorganic reinforcement filler. Preferably, it is advantageous that the silica S represents at least 50% by weight of the total weight of the inorganic reinforcing filler, more preferably at least 80% by weight of the total weight of the inorganic reinforcing filler. The total weight of the inorganic reinforcing filler corresponds to the sum of the weight of silica S and the weight of additional silica.

[00265] “Additional silica” means any other silica other than S silicas, that is, with characteristics different from S silicas, especially with a magnitude A that does not satisfy the relation (II). As additional silicas, mention may be made of precipitated or fumed silicas other than S silicas. What are called highly dispersible silicas ("HDSs") can especially be used such as, for example, Evonik's Ultrasil 7000GR silicas, Evonik's silicas Solvay's Zeosil® 1165 MP and Solvay's Zeosil® 1115 MP, Solvay's Zeosil® Premium 200MP silica, PPG's Hi-Sil EZ150G silica, Huber's Zeopol 8715, 8745 or 8755 silicas or silicas as described in Applications WO03/ 016215 and WO03/016387.

[00266] In another embodiment, the inorganic reinforcing filler may be a mixture of S silica and another inorganic reinforcing filler selected from the group consisting of aluminum oxides, aluminum hydroxides, aluminosilicates, titanium oxides, silicon nitrides or carbides , all of reinforcement type. Such reinforcing inorganic fillers are, for example, described in WO99/28376, WO00/73372, WO02/053634, WO2004/003067, WO2004/056915.

[00267] As aluminum oxide, use can especially be made of a reinforcing and highly dispersible alumina having a BET surface area ranging from 30 to 400 m2/g, more preferably between 60 and 250 m2/g, and an average aggregate size at most equal to 500 nm, more preferably at most equal to 200 nm. Special mention may be made, as non-limiting examples of such reinforcing aluminas, to Baikalox A125 or CR125 (Baikowski), APA-100RDX alumina (Condea), Aluminoxid C alumina (Degussa) or AKP-G015 alumina (Sumitomo Chemicals) and those described in Application EP0810258.

[00268] As equivalent to an inorganic filler of additional reinforcement, those skilled in the art will understand that they can use especially an organic type reinforcer, especially a carbon black as described below, at least partially covered with an inorganic layer, especially a layer of silica. Such carbon blacks are described, for example, in WO2013/190063.

[00269] Preferably, the silica S represents 100% by weight of the total weight of the reinforcing inorganic filler.

[00270] The amount of reinforcing inorganic filler in the rubber composition of the invention depends on the use of this composition. In fact, the expected level of reinforcement for a bicycle tire, for example, is, as is known, significantly lower than that required for a tire capable of running at high speeds in a sustained manner, for example, a motorcycle tire, a tire for a passenger vehicle or a tire for a utility vehicle such as a heavy vehicle. Those skilled in the art know how to adapt the amount of reinforcing inorganic filler depending on the use of the composition of the invention.

[00271] Preferably, the amount of reinforcing inorganic filler in the composition may be within a range preferably extending from 10 to 200 phr, even more preferably within a range extending from 30 to 150 phr. - Agent for coupling the elastomer to the reinforcing inorganic filler

[00272] The rubber compositions according to the invention comprise at least one agent for coupling the elastomer to the reinforcing inorganic filler.

[00273] To couple the reinforcing inorganic filler to the diene elastomer, use is made, in a well-known manner, of an at least bifunctional coupling agent (or bonding agent) intended to provide a satisfactory connection, chemical in nature and/or or physical, between the inorganic load (surface of its aggregates) and the diene elastomer. The coupling agent has, for example, the simplified general formula "Y-T-X", in which: - Y represents a functional group ("Y function") that is capable of physically and/or chemically binding to the inorganic charge, it being possible that this bond is established, for example, between a silicon atom of the coupling agent and the surface hydroxyl groups (OH) of the inorganic filler; - X represents a functional group ("X" function) that is able to physically and/or chemically bind to the elastomer, for example, by means of a sulfur atom; - T represents a group that makes it possible to connect Y and X.

[00274] This connection can be established, for example, through covalent, hydrogen, ionic and/or electrostatic bonds between the Y function and the reinforcing inorganic load and between the Z function and the elastomer.

[00275] Coupling agents should not, in particular, be confused with simple agents to cover the load in question which, in a known way, can comprise the Y function, active in relation to the load, but without the X function, active with respect to the elastomer.

[00276] Such coupling agents have been described in a very large number of documents and are well known to persons skilled in the art. In fact, any coupling agent capable of effectively providing bonding or coupling between an inorganic reinforcing filler and the elastomer can be used.

[00277] Preferably, the agent for coupling the elastomer to the reinforcing inorganic filler is an organosilane compound.

[00278] Preferably, the organosilane compound is selected from the group consisting of organosilane polysulfides (symmetric or asymmetric), polyorganosiloxanes, mercaptosilanes, masked mercaptosilanes, mercaptosilane dimers, masked mercaptosilane dimers, silane dimers having a mercaptosilane unit , mercaptosilane oligomers, masked mercaptosilane oligomers and silane oligomers having at least one mercaptosilane unit and at least one masked mercaptosilane, preferably organosilane polysulphides.

[00279] These agents for coupling the elastomer to the reinforcing inorganic filler, in particular, have been described in a large number of documents, the best known being the bifunctional alkoxysilanes such as alkoxysilane sulfides. Use is made, in particular, of alkoxysilane sulfides, called "symmetrical" or "asymmetrical", depending on their specific structure, as described, for example, in Patent Applications or Patents US-A-3 842 111, US-A - 3 873 489, US-A-3 978 103, US-A-3 997 581, US-A-4 002 594, US-A-4 072 701, US-A-4 129 585 or in later documents A -5 580 919, US-A-5 583 245, US-A-5 650 457, US-A-5 663 358, US-A-5 663 395, US-A-5 663 396, US-A-5 674 932, US-A-5 675 014, US-A-5 684 171, US-A-5 684 172, US-A-5 696 197, US-A-5 708 053, US-A-5 892 085 and WO 02/083782.

[00280] More preferably, the organosilane compound is selected from organosilane polysulfides (symmetrical or asymmetrical), also called silane polysulfides.

[00281] More particularly, use can be made of silane polysulphides, called "symmetrical" or "asymmetrical", depending on their specific structure, as described, for example, in WO 03/002648 (or US 2005/016651) and WO 03/002649 (or US 2005/016650).

[00282] Preferably, in particular, without the definition below being limiting, silane polysulphides corresponding to the following general formula (VII) are suitable:

[00283] in which: - x is an integer from 2 to 8 (preferably from 2 to 5); - the symbols A, which are identical or different, represent a divalent hydrocarbon-based radical (preferably a C1-C18 alkylene group or a C6-C12 arylene group, more particularly a C1C10 alkylene group, especially C1-C4, in particular propylene ); - the Z symbols, which are identical or different, correspond to one of the three formulas (VIII) below:

[00284] in which: • the radicals Ra, which are substituted or unsubstituted and identical or different from each other, represent a C1-C18 alkyl group, C, C5-C18 cycloalkyl group or C6-C18 aryl group (preferably C1 alkyl groups -C6, cyclohexyl or phenyl, especially C1-C4 alkyl groups, more particularly methyl and/or ethyl). • the radicals Rb, which are substituted or unsubstituted and identical or different from one another, represent a C1-C18 alkoxy group or C5-C18 cycloalkoxy group or group (preferably a group selected from C1-C8 alkoxyls and C5-C8 cycloalkoxyls , even more preferably a group selected from C1-C4 alkoxys, in particular methoxy and ethoxy).

[00285] In the case of a mixture of alkoxysilane polysulfides corresponding to formula (VII) above, especially commercially available normal mixtures, the average value of the indices "x" is a fractional number, preferably between 2 and 5, more preferably approximately 4. However, the invention can also advantageously be carried out, for example, with alkoxysilane disulfides (x = 2).

[00286] Mention will be made, more particularly, as examples of silane polysulphides, to bis-((C1-C4)alkoxyl(C1-C4)alkylsilyl(C1-C4)alkyl) polysulphides (in particular, the disulfides, trisulfides or tetrasulfides), such as, for example, bis(3-trimethoxysilylpropyl) or bis(3-triethoxysilylpropyl) polysulfides. Use is made, in particular, among these compounds, of bis-(3-triethoxysilylpropyl) tetrasulfide, abbreviated as TESPT, of formula [(C2H5O)3Si(CH2)3S2]2 or bis(trethoxysilylpropyl) disulfide, abbreviated as TESPD , with the formula [(C2H5O)3Si(CH2)3S]2. Mention will also be made, as preferred examples, of bis-(monoalkoxyl(C1-C4)-dialkyl(C1-C4)silylpropyl) polysulphides (especially disulfides, trisulphides or tetrasulphides), more particularly bis-monoethoxydimethylsilylpropyl tetrasulphide, as described in WO 02/083782 (or US 7 217 751) mentioned above.

[00287] In particular, as examples of coupling agents, in addition to an alkoxysilane polysulfide, bifunctional POSs (polyorganosiloxanes) or even hydroxysilane polysulfides (Rb = OH in formula VII above) can be used, as described, for example, in WO 02/30939 (or US 6 774 255), WO 02/31041 (or US 2004/051210) and WO2007/061550, or even silanes or POSs containing azodicarbonyl functional groups, as described, for example , in WO 2006/125532, WO 2006/125533 and WO 2006/125534.

[00288] As examples of other silane sulphides, mention will be made, for example, of silanes containing at least one thiol function (-SH) (called mercaptosilanes) and/or at least one masked thiol function, dimers or oligomers of these silanes, such as described, for example, in Patents or Patent Applications US6849754, WO99/09036, WO2006/023815, WO2007/098080, WO2007/98120, EP1994038, EP2079793, WO2010/072685 and WO2008/055986.

[00289] The content of the agent for coupling the elastomer to the reinforcing inorganic filler is easily adjusted by persons skilled in the art, depending on the content of the reinforcing inorganic filler used in the composition.

[00290] More particularly, the coupling agent content is advantageously less than 20 phr, it being understood that generally it is desirable to use as little of it as possible. Typically, the coupling agent content represents from 0.5% to 15% by weight relative to the weight of the reinforcing inorganic filler. Its content is preferably between 0.5 and 12 phr, more preferably within a range extending from 3 to 10 phr. □ Coverage agents:

[00291] The rubber compositions according to the invention may also contain coupling activators when a coupling agent is used, agents for covering the inorganic filler or, more generally, processing aids capable, in a known manner, due to a improvement in filler dispersion in the rubber matrix and a reduction in the viscosity of the compositions, from improving their processability in the uncured state. Such covering agents are well known (see, for example, WO 2006/125533, WO 2007/017060 and WO 2007/003408); mention will be made, for example, of hydroxysilanes or hydrolyzable silanes, such as hydroxysilanes (see, for example, WO 2009/062733), alkylalkoxysilanes, especially alkylethoxyethylsilanes such as, for example, 1-octyltriethoxysilane, polyols (for example diols or triols ), polyethers (e.g. polyethylene glycols), primary, secondary or tertiary amines (e.g. trialkanolamines), hydroxylated or hydrolysable polyorganosiloxanes (e.g. dihydroxypolyorganosilanes (especially -dihydroxypolyorganosilanes) (especially -dihydroxypolyodimethylsiloxanes) (see , eg EP 0 784 072), and fatty acids such as eg stearic acid.□ Reinforcing organic fillers

[00292] The rubber compositions according to the invention may also comprise at least one reinforcing organic filler such as, for example, carbon black or a polymer-type reinforcing filler. Preferably, the reinforcing organic filler is carbon black.

[00293] All carbon blacks, especially HAF, ISAF or SAF type blacks, conventionally used in tires (“tyre grade blacks”) are suitable as carbon blacks. More specifically, mention will be made, among the latter, of reinforcement carbon blacks of the 100, 200 or 300 series (ASTM categories), such as, for example, blacks N115, N134, N234, N326, N330, N339, N347 either N375 or else, depending on the intended applications, the blacks of higher series (eg N660, N683 or N772). The carbon blacks can, for example, already be incorporated into an elastomer, especially an isoprene elastomer, in the form of a masterbatch (see, for example, WO 97/36724 or WO 99/16600).

[00294] Mention may be made, as examples of polymeric organic fillers, to functionalized polyvinyl organic fillers, as described in WO 2006/069792, WO 2006/069793, WO 2008/003434 and WO 2008/003435.

[00295] When an organic filler is combined with the inorganic filler filler, the organic filler is used in a low proportion, that is, the inorganic filler filler remains as the predominant filler.

[00296] Preferably, the weight fraction of the reinforcing organic filler is less than 50% in relation to the total weight of the reinforcing load (total weight of the reinforcing load = weight of the inorganic reinforcing load + weight of the reinforcing organic load ), preferably less than or equal to 20% in relation to the total weight of the reinforcing load.

[00297] More particularly, the content of the reinforcing organic filler, especially the carbon black content, is within a range extending from 2 to 20 phr, more preferably within a range extending from 5 to 15 phr . □ Other additives

[00298] The rubber compositions according to the invention may optionally also comprise all or a portion of the usual additives commonly used in elastomer compositions intended for the manufacture of tires or semi-finished articles for tires, such as, for example, pigments, protection such as anti-ozone waxes, chemical anti-ozonants or antioxidants, anti-fatigue agents, cross-linking agents other than those mentioned above, reinforcing resins or plasticizing agents, methylene acceptors (e.g. novolak phenolic resin) or methylene donors (e.g. HMT or H3M), as described, for example, in WO 02/10269. Preferably, when the rubber composition of the invention comprises a plasticizer, it is selected from the group consisting of solid hydrocarbon-based resins (or plasticizer resins), extender oils (plasticizer oils) or a mixture of oils and plasticizer resins. □ Reticulation system

[00299] The rubber compositions according to the invention comprise a chemical crosslinking system. Any type of crosslinking system known to those skilled in the art for rubber compositions can be used.

[00300] The crosslinking system is preferably a vulcanization system, that is, a system based on sulfur (or on a sulfur donor agent) and on a primary vulcanization accelerator. Various known secondary vulcanization accelerators or vulcanization activators, such as zinc oxide, stearic acid or equivalent compounds or guanidine derivatives (in particular, diphenylguanidine), can be added to this basic vulcanization system, being incorporated during the first stage not productive and/or during the productive phase, as described later.

[00301] When sulfur is used, it is used with a preferred content between 0.5 and 12 phr, in particular between 1 and 10 phr. The primary vulcanization accelerator is used with a preferred content between 0.5 and 10 phr, more preferably between 0.5 and 5.0 phr.

[00302] The vulcanization system of the composition according to the invention may also comprise one or more additional accelerators, for example compounds from the thiuram family, zinc dithiocarbamate derivatives, sulfenamides, guanidines or thiophosphates. In particular, any compound capable of acting as an accelerator for the vulcanization of diene elastomers in the presence of sulfur can be used, especially accelerators of the thiazole type and also their derivatives, accelerators of the thiurams type and zinc dithiocarbamates. Such accelerators are, for example, selected from the group consisting of 2-mercaptobenzothiazole disulfide (abbreviated as MBTS), tetrabenzylthiuram disulfide (TBZTD), N-cyclohexyl-2-benzothiazolesulfenamide (CBS), N,N-dicyclohexyl-2- benzothiazide (DCBS), N-(tert-butyl)-2-benzothiazolesulfenamide (TBBS), N-(tert-butyl)-2-benzothiazolesulfenimide (TBS), zinc dibenzyldithiocarbamate (ZBEC) and mixtures of these compounds. Preferably, a sulfenamide-type primary accelerator is used. □ Process for preparing the compositions according to the invention

[00303] The rubber compositions of the invention, intended especially for the manufacture of tires or semi-finished products for tires, can be produced by any process well known to people skilled in the art.

[00304] For example, these rubber compositions according to the invention can be produced in appropriate mixers, using two successive preparation stages, according to a general procedure well known to people skilled in the art: a first stage of thermomechanical working or kneading (sometimes called a "non-productive" phase) at high temperature, up to a maximum temperature (denoted Tmax) between 130 °C and 200 °C, preferably between 145 °C and 185 °C, followed by a second mechanical working phase (sometimes called a “productive” phase) at lower temperature, typically below 120 °C, for example between 60 °C and 100 °C, finishing phase during which the crosslinking or vulcanizing system is incorporated; such steps have been described, for example, in EP-A-0501227, EP-A-0735088 and EP-A-0810258.

[00305] For example, in a process to prepare the compositions of the invention, silica S, combined or not combined with another inorganic reinforcing filler, such as an additional silica, for example, or with a carbon black and the agent for coupling the elastomer to said reinforcing inorganic load, are incorporated by kneading into the elastomer or elastomers during the first "non-productive" phase, i.e., at least these ingredients are introduced into the mixer and thermomechanically kneaded, in one or several stages. Then, after, for example, one to two minutes of kneading, optional additional covering agents or processing aids and other various additives, with the exception of the crosslinking or vulcanizing system, are added to the internal mixer. This mixture is thermomechanically kneaded until the maximum temperature Tmax mentioned above is reached. It is possible to envisage one or more additional steps in order to prepare master batches of reinforcing elastomers/inorganic fillers intended to be introduced during the first "non-productive" phase. Masterbatches of elastomer/inorganic reinforcing fillers comprising at least one S silica can be obtained by bulk blending or liquid blending from an elastomer latex and an aqueous dispersion of said inorganic reinforcing filler.

[00306] The mixture is then cooled and the crosslinking system (preferably the vulcanization system) is then incorporated at low temperature (typically less than 100 °C), usually in an external mixer, such as an open mill; the blended mixture is then blended for a few minutes, for example between 5 and 15 min. This second phase is the "productive" phase.

[00307] The process for preparing a rubber composition according to the invention preferably comprises the following steps: □ at least one elastomer, at least one reinforcing inorganic filler and at least one agent for coupling the elastomer to the inorganic filler of reinforcement are brought into contact; said reinforcing inorganic filler comprising at least one silica S having: - a specific surface area of CTAB SCTAB within a range extending from 40 to 300 m2/g; - a difference between the specific surface area of BET SBET and the specific surface area of CTAB SCTAB greater than or equal to 35 m2/g; - a WAl aluminum content within a range extending from 0.5 to 7.0% by weight relative to the weight of silica S; - a breadth of aggregate size distribution Ld, measured by centrifugal sedimentation, greater than or equal to 1.5; and - an average aggregate diameter d50, measured by centrifugal sedimentation, so that, for a given CTAB SCTAB specific surface area value and a given WAl aluminum content, a magnitude A is defined by the following equation (I):

[00308] where: [d50] is the numerical value of d50, expressed in nm; [SCTAB] is the numerical value of SCTAB, expressed in m2/g; [WAl] is the numerical value of WAl, expressed in % by weight in relation to the weight of silica S; It is

• tudo é amassado termomecanicamente, uma ou diversas vezes, até que uma temperatura máxima entre 110 °C e 190 °C seja alcançada; • a mistura da etapa anterior é resfriada para uma temperatura abaixo de 100 °C, • um sistema de reticulação é incorporado à mistura resfriada da etapa anterior, • a mistura que compreende o sistema de reticulação é amassada até uma temperatura máxima abaixo de 110 °C.[00309] said magnitude A satisfies the relation (II):

• everything is thermomechanically kneaded, once or several times, until a maximum temperature between 110 °C and 190 °C is reached; • the mixture from the previous step is cooled to a temperature below 100 °C, • a crosslinking system is incorporated into the cooled mixture from the previous step, • the mixture comprising the crosslinking system is kneaded to a maximum temperature below 110 ° W.

[00310] The final composition obtained in this way is subsequently calendered, for example, in the form of a sheet or plate, especially for laboratory characterization, or else extruded, in order to form, for example, a profiled rubber element used in the manufacture of semi-finished products especially for tires. These products can then be used for the manufacture of tires, according to techniques known to people skilled in the art, with the advantage of the invention, namely a good compromise of rolling resistance/wear resistance.

[00311] Preferably, the process for preparing a rubber composition according to the invention also comprises a step in which the kneaded mixture comprising the crosslinking system is cured.

[00312] This curing (or vulcanizing) step is carried out according to methods well known to persons skilled in the art. It is especially carried out in known manner at a temperature generally between 130 °C and 200 °C, under pressure of several hundred bar, for a sufficient time that can be within a range extending, for example, between 5 and 90 min, depending especially on the curing temperature, the reticulation system adopted, the vulcanization kinetics of the composition in question or the size of the tire. • Semi-finished articles and tires

[00313] Another object of the present invention relates to a semi-finished article, especially for a tire, comprising at least one composition, according to the invention and as defined above. The semi-finished articles of the present invention advantageously have an improved rolling resistance/abrasion resistance compromise. The rubber composition of the semi-finished product can be in the uncured state (before crosslinking) or in the cured state (after crosslinking).

[00314] The semi-finished article can be any article used for the manufacture of finished rubber articles and, for example, a tire.

[00315] Preferably, the semi-finished article for a tire can be selected from lower layers, bonding rubbers between rubbers of different natures or calendering rubbers for metal or textile reinforcements, sidewall rubbers or treads. More preferably, the semi-finished article is a tire tread.

[00316] The semi-finished articles are obtained by methods well known to persons skilled in the art. The preferred modes of S silicas, elastomers and coupling agents mentioned for the compositions according to the invention also apply to this semi-finished article.

[00317] Another object of the present invention relates to a tire comprising at least one rubber composition according to the invention and as described above or comprising at least one semi-finished article as described above. The tires of the present invention advantageously have an improved rolling resistance/abrasion resistance compromise.

[00318] The tires of the invention may be specially intended to equip motor vehicles of the type of passenger vehicle, SUV ("Sport utility vehicles"), two-wheeled vehicle (especially motorcycle) or aircraft, and industrial vehicles chosen from vans, heavy vehicles, i.e. underground trains, buses, heavy road transport vehicles (trucks, tractors, trailers) or off-road vehicles such as heavy agricultural or construction site vehicles and other transport or handling vehicles.

[00319] The tires of the invention are obtained by methods well known to people skilled in the art. The preferred modes of S silicas, elastomers and coupling agents mentioned for the compositions according to the invention also apply to this tire.

II - EXAMPLES

[00320] The following examples illustrate the invention without, however, limiting it. II.1 PREPARATION OF INORGANIC REINFORCEMENT LOADS

[00321] The silicas used in the compositions to be tested are the following: • Silica SC1

[00322] SC1 silica is a silica marketed by Solvay under the reference Zeosil® 1165MP. It is obtained especially according to the process described in Application EP0520862-A1. Its characteristics are shown in table VI. • Silica SC2

[00323] SC2 silica is a silica marketed by Solvay under the reference Zeosil® Premium 200MP. It is obtained especially according to the process described in Application WO03/016215-A1, pages 1 to 15. Its characteristics are shown in table VI. • Silica SC3

[00324] SC3 silica was obtained according to the protocol described on page 18, lines 15 to 32 of Application WO03/106339-A1 (example 2). Its characteristics are shown in table VI. • Silica S1

[00325] 16.7 liters of purified water and 210 g of Na2SO4 (solid) are introduced into a 25 l stainless steel reactor. The solution obtained in this way is stirred and heated to reach a temperature of 92 °C. The whole process is carried out at this temperature, with stirring, in order to maintain a homogeneous reaction medium. Sulfuric acid at a concentration of 7.7% by weight is introduced in order to reach a pH equal to 3.90.

[00326] A sodium silicate solution (with a weight ratio of SiO2/Na2O = 3.45 and a concentration of SiO2 = 19.4% by weight) is introduced into the reactor at a flow rate of 115 g/min for 45 seconds. The same sodium silicate solution is used throughout the entire process. Then, a sodium silicate solution at a flow rate of 115 g/min and a sulfuric acid solution with a concentration equal to 7.7% by weight, at a flow rate of 140 g/min, are simultaneously introduced into the reactor by 14 minutes. The flow rate of the sulfuric acid solution is regulated in order to maintain the pH of the reaction medium equal to 4.50. At the end of this step, a sodium silicate solution at a flow rate of 115 g/min and a 96% by weight sulfuric acid solution (referred to in the rest of the description as 96% sulfuric acid) are introduced simultaneously for a period of 10 min. The flow rate of this 96% sulfuric acid solution is regulated to maintain a pH of 4.50.

[00327] The introduction of 96% sulfuric acid is stopped while the addition of said sodium silicate solution is continued with a flow rate of 93 g/min until the reaction medium reaches a pH of 8.00.

[00328] A sodium silicate solution at a flow rate of 181 g/min and a 96% sulfuric acid solution are then simultaneously introduced into the reaction medium for a period of 3 min. The flow rate of the 96% sulfuric acid solution is regulated so that the pH of the reaction medium is maintained at a value of 8.00.

[00329] Then, are added simultaneously and for 15 minutes: a solution of sodium silicate at a flow rate of 181 g/min, a solution of sodium aluminate (% by weight of Al: 11.6% -% by weight of Na2O: 19.9%) at a flow rate of 10 g/min and a 96% sulfuric acid solution. The flow rate of the 96% sulfuric acid solution is regulated so that the pH of the reaction medium is maintained at a value of 8.00.

[00330] At the end of this simultaneous addition, the reaction medium is brought to a pH = 4.80 with 96% sulfuric acid. The reaction mixture is aged for 5 minutes. A suspension of precipitated silica is thus obtained.

[00331] The reaction medium is filtered and washed in a filter press. The cake obtained is mechanically disintegrated. The resulting suspension is spray-dried to obtain precipitated silica SI. The characteristics of precipitated silica S1 are indicated in table VI. • Silica S2

[00332] 1,129 l of water and 29.7 kg of Na2SO4 (solid) are introduced into a stainless steel reactor of 2,500 l. The solution obtained in this way is stirred and heated to reach a temperature of 92 °C. The whole process is carried out at this temperature, with stirring, in order to maintain a homogeneous reaction medium. Sulfuric acid at 96% by weight (referred to in the rest of the description as sulfuric acid at 96%) is introduced into the reactor so as to reach a pH equal to 3.90. A sodium silicate solution (with a SiO2/Na2O weight ratio = 3.46 and a SiO2 concentration = 19.4% by weight) is introduced into the reactor at a flow rate of 1353 l/h for 61 seconds. The same sodium silicate solution is used throughout the entire process.

[00333] Then, a sodium silicate solution at a flow rate of 445 l/h, water at a flow rate of 575 l/h and a 96% sulfuric acid solution are introduced simultaneously into the reactor for 15 minutes. The flow rate of the 96% sulfuric acid solution is regulated to maintain the pH of the reaction medium at 3.90. At the end of this step, a sodium silicate solution at a flow rate of 445 l/h and a 96% sulfuric acid solution are introduced simultaneously for a period of 9 min. The flow rate of this 96% sulfuric acid solution is regulated so as to maintain a pH equal to 3.90. The introduction of the 96% sulfuric acid is stopped while the addition of said sodium silicate solution is continued with a flow rate of 582 l/h until the reaction medium reaches a pH of 8.00.

[00334] A sodium silicate solution at a flow rate of 703 l/h and a 96% sulfuric acid solution are then simultaneously introduced into the reaction medium for a period of 3 min. The flow rate of the 96% sulfuric acid solution is regulated so that the pH of the reaction medium is maintained at a value of 8.00.

[00335] Then, are added simultaneously and for 15 minutes: a solution of sodium silicate at a flow rate of 703 l/h, a solution of sodium aluminate (% by weight of Al: 11.6% -% by weight of Na2O: 19.4%) at a flow rate of 47.6 kg/h and a 96% sulfuric acid solution. The flow rate of the 96% sulfuric acid solution is regulated so that the pH of the reaction medium is maintained at a value of 8.00.

[00336] At the end of this simultaneous addition, the reaction medium is brought to a pH = 4.50 with 96% sulfuric acid. Water is then introduced to lower the temperature to a value of 85 °C and the reaction mixture is aged for 5 minutes. A suspension of precipitated silica is thus obtained.

[00337] The reaction medium is filtered and washed in a filter press. The cake obtained is mechanically disintegrated. The resulting suspension is spray dried to obtain precipitated silica S2. The characteristics of precipitated silica S2 are indicated in table VI. • Silica S3

[00338] 16.7 liters of purified water and 260 g of Na2SO4 (solid) are introduced into a 25 l stainless steel reactor. The solution obtained in this way is stirred and heated to reach a temperature of 92 °C. The whole process is carried out at this temperature, with stirring, in order to maintain a homogeneous reaction medium. Sulfuric acid at a concentration of 7.7% by weight is introduced in order to reach a pH equal to 3.90. A sodium silicate solution (with a SiO2/Na2O weight ratio = 3.4 and a SiO2 concentration = 19.4% by weight) is introduced into the reactor at a flow rate of 114 g/min for 45 seconds. The same sodium silicate solution is used throughout the entire process.

[00339] Then, a sodium silicate solution at a flow rate of 114 g/min and a sulfuric acid solution with a concentration equal to 7.7% by weight, at a flow rate of 137 g/min, are introduced simultaneously in the reactor for 14 minutes. The flow rate of the sulfuric acid solution is regulated in order to maintain the pH of the reaction medium equal to 4.53. At the end of this step, a sodium silicate solution at a flow rate of 114 g/min and a 96% by weight sulfuric acid solution (referred to in the rest of the description as 96% sulfuric acid) are introduced simultaneously for a period of 10 min. The flow rate of this 96% sulfuric acid solution is regulated to maintain a pH of 4.53.

[00340] The introduction of 96% sulfuric acid is stopped while the addition of said sodium silicate solution is continued with a flow rate of 114 g/min until the reaction medium reaches a pH of 8.00.

[00341] A sodium silicate solution at a flow rate of 181 g/min and a 96% sulfuric acid solution are then simultaneously introduced into the reaction medium for a period of 3 min. The flow rate of the 96% sulfuric acid solution is regulated so that the pH of the reaction medium is maintained at a value of 8.00.

[00342] Then, are added simultaneously and for 15 minutes: a solution of sodium silicate at a flow rate of 181 g/min, a solution of sodium aluminate (% by weight of Al: 11.6% -% by weight of Na2O: 19.9%) at a flow rate of 10 g/min and a 96% sulfuric acid solution. The flow rate of the 96% sulfuric acid solution is regulated so that the pH of the reaction medium is maintained at a value of 8.00.

[00343] At the end of this simultaneous addition, the reaction medium is brought to a pH = 4.80 with 96% sulfuric acid. The reaction mixture is aged for 5 minutes. A suspension of precipitated silica is thus obtained.

[00344] The reaction medium is filtered and washed in a filter press. The cake obtained is mechanically disintegrated. The resulting suspension is spray dried to obtain precipitated silica S3. The characteristics of precipitated silica S3 are indicated in table VI. • Silica S4

[00345] 16.7 liters of purified water and 260 g of Na2SO4 (solid) are introduced into a 25 l stainless steel reactor. The solution obtained in this way is stirred and heated to reach a temperature of 92 °C. The whole process is carried out at this temperature, with stirring, in order to maintain a homogeneous reaction medium. Sulfuric acid at a concentration of 7.7% by weight is introduced in order to reach a pH equal to 3.90. A sodium silicate solution (with a SiO2/Na2O weight ratio = 3.4 and a SiO2 concentration = 19.3% by weight) is introduced into the reactor at a flow rate of 114 g/min for 45 seconds. The same sodium silicate solution is used throughout the entire process. Then, a sodium silicate solution at a flow rate of 114 g/min and a sulfuric acid solution with a concentration equal to 7.7% by weight, at a flow rate of 142 g/min, are simultaneously introduced into the reactor by 14 minutes. The flow rate of the sulfuric acid solution is regulated in order to maintain the pH of the reaction medium equal to 3.74. At the end of this step, a sodium silicate solution at a flow rate of 115 g/min and a 96% by weight sulfuric acid solution (referred to in the rest of the description as 96% sulfuric acid) are introduced simultaneously for a period of 10 min. The flow rate of this 96% sulfuric acid solution is regulated to maintain a pH of 3.74.

[00346] The introduction of 96% sulfuric acid is stopped while the addition of said sodium silicate solution is continued with a flow rate of 114 g/min until the reaction medium reaches a pH of 8.00.

[00347] A sodium silicate solution at a flow rate of 182 g/min and a 96% sulfuric acid solution are then simultaneously introduced into the reaction medium for a period of 3 min. The flow rate of the 96% sulfuric acid solution is regulated so that the pH of the reaction medium is maintained at a value of 8.00.

[00348] Then, are added simultaneously and for 15 minutes: a solution of sodium silicate at a flow rate of 182 g/min, a solution of sodium aluminate (% by weight of Al: 11.6%.-

[00349] % by weight of Na2O: 19.9%) at a flow rate of 10 g/min and a 96% sulfuric acid solution. The flow rate of the 96% sulfuric acid solution is regulated so that the pH of the reaction medium is maintained at a value of 8.00.

[00350] At the end of this simultaneous addition, the reaction medium is brought to a pH = 4.80 with 96% sulfuric acid. The reaction mixture is aged for 5 minutes. A suspension of precipitated silica is thus obtained.

11.2 PREPARAÇÃO DAS COMPOSIÇÕES DE BORRACHA A SEREM TESTADAS[00351] The reaction medium is filtered and washed in a filter press. The cake obtained is mechanically disintegrated. The resulting suspension is spray dried to obtain precipitated silica S4. The characteristics of precipitated silica S4 are indicated in table VI. TABLE VI: CHARACTERISTICS OF USED SILICAS

11.2 PREPARATION OF RUBBER COMPOSITIONS TO BE TESTED

[00352] The rubber compositions to be tested are prepared as follows: the diene elastomer (or the mixture of diene elastomers, when appropriate), then the inorganic reinforcing filler (silica to be tested), the agent for coupling the elastomer to the inorganic reinforcing filler and then, after kneading for one to two minutes, the various other ingredients, with the exception of sulfur and the primary sulfenamide accelerator, are introduced into an internal mixer that is 70% filled and which has an initial vessel temperature of approximately 60 °C. Thermomechanical work is then carried out (non-productive phase) in one or two stages (total kneading duration equal to approximately 5 to 7 min, people versed in the technique know how to adapt this total duration depending on the elastomer matrix of the composition), until a maximum "drop" temperature of approximately 160 to 165 °C is reached. The mixture obtained in this way is recovered and cooled, then the sulfur and sulfenamide accelerator are added in an external mixer (homofinisher) at 30 °C, everything being mixed (productive phase) for 3 to 4 minutes.

[00353] The compositions are then formed for measurements of their physical or mechanical properties (for example, in the form of 4 mm specimens, etc.) and, where appropriate, are cured (or vulcanized) for measurements of properties healed. 11.3 TEST A

[00354] The purpose of this test is to demonstrate the improved performance properties of a rubber composition according to the invention, based on an innovative silica, compared to a rubber composition used conventionally and marketed in "green tires".

[00355] For this purpose, four rubber compositions are compared, intended especially for the manufacture of tire treads: - the control compositions T1 and T2 contain SC1 silica, - the compositions according to the invention C1 and C2 contain the S1 silica.

[00356] The T1 and T2 control compositions are representative of the rubber compositions used in commercial “green tires”, which are known to have a good compromise of rolling resistance/wear resistance performance properties.

[00357] The control composition T2 and the composition according to the invention C2 respectively differ from the control composition T1 and the composition according to the invention C1 by the nature of the elastomer and the filler content. The elastomer matrix of compositions T1 and C1 comprises a functionalized diene elastomer and that of compositions T2 and C2 comprises a non-functionalized diene elastomer.

[00358] Table VII presents the formulation of the different compositions, with the contents expressed in phr (parts by weight per hundred parts by weight of elastomers).

[00359] The optimal content of diphenylguanidine (DPG) is adapted depending on the specific BET surface area of the silica to be tested.

[00360] In fact, the greater the BET specific surface area of a silica, the more it is necessary to use a high DPG content in order to cover the silica surface and promote its dispersion. Those skilled in the art know how to adapt these contents depending on the nature of the silica used. The formulations can be compared.

[00361] Each T1 and C1 composition has a density (p) equal to 1.23.

(1) Elastômero: Copolímero de estireno/butadieno SBR, que tem uma função de amina-alcoxissilano terciária no meio da cadeia e tem uma temperatura de transição vítrea, medida de acordo com a norma D3418 de 1999, igual a -48 °C. Sua microestrutura, determinada pelo método NIR, é a seguinte: o teor em peso de unidades 1,4-trans é de 45,1%, o de unidades 1,4-cis é de 30,5% e o de unidades 1,2 é de 24,4% (cada um desses três teores se refere às unidades de butadieno). O teor em peso de unidades de estireno é de 27%;(2) Elastômero: Copolímero de estireno/butadieno não funcionalizado SBR em solução, com temperatura de transição vítrea medida de acordo com a norma D3418 de 1999 igual a -48 °C. Sua microestrutura, determinada pelo método NIR, é a seguinte: o teor em peso de unidades 1,4-trans é de 50%, o de unidades 1,4-cis é de 26% e o de unidades 1,2 é de 24% (cada um desses três teores se refere às unidades de butadieno). O teor em peso de unidades de estireno é de 26,5%; (3) negro de fumo grau N234 comercializado por Cabot Corporation; (4) Agente de acoplamento: Bis[3-(trietoxissilil)propil] Tetrassulfureto de silano (TESPT) comercializado por Evonik sob a referência Si69; (5) DPG: difenilguanidina, comercializada por Flexsys sob a referência Perkacit; (6) Resina: Fração C5/C9 comercializada por Exxon com a referência ECR-373; (7) Plastificante: Óleo de girassol que compreende 85% em peso de ácido oléico, comercializado por Novance sob a referência Lubrirob Tod 1880; (8) Antioxidante: N-(1,3-dimetilbutil)-N-fenil-para-fenilenodiamina comercializado por Flexsys sob a referência Santoflex 6-PPD; (9) Acelerador: N-ciclo-hexil-2-benzotiazolesulfenamida comercializado por Flexsys sob a referência Santocure CBS.[00362] Each T2 and C2 composition has a density (p) equal to 1.18. TABLE VII

(1) Elastomer: SBR styrene/butadiene copolymer, which has an amine-tertiary alkoxysilane function in the middle of the chain and has a glass transition temperature, measured in accordance with D3418 of 1999, equal to -48 °C. Its microstructure, determined by the NIR method, is as follows: the content by weight of 1,4-trans units is 45.1%, that of 1,4-cis units is 30.5% and that of 1, 2 is 24.4% (each of these three contents refers to butadiene units). The content by weight of styrene units is 27%;(2) Elastomer: SBR non-functionalized styrene/butadiene copolymer in solution, with a glass transition temperature measured in accordance with D3418 of 1999 equal to -48 °C. Its microstructure, determined by the NIR method, is as follows: the content by weight of 1,4-trans units is 50%, that of 1,4-cis units is 26% and that of 1,2 units is 24 % (each of these three levels refers to butadiene units). The content by weight of styrene units is 26.5%; (3) carbon black grade N234 available from Cabot Corporation; (4) Coupling agent: Bis[3-(triethoxysilyl)propyl] Silane tetrasulfide (TESPT) sold by Evonik under the reference Si69; (5) DPG: diphenylguanidine, available from Flexsys under the trade name Perkacit; (6) Resin: C5/C9 fraction marketed by Exxon under the reference ECR-373; (7) Plasticizer: Sunflower oil comprising 85% by weight of oleic acid, marketed by Novance under the reference Lubrirob Tod 1880; (8) Antioxidant: N-(1,3-dimethylbutyl)-N-phenyl-para-phenylenediamine sold by Flexsys under the reference Santoflex 6-PPD; (9) Accelerator: N-cyclohexyl-2-benzothiazolesulfenamide sold by Flexsys under the trade name Santocure CBS.

[00363] The properties measured after curing at 150 °C for 45 min are described in Table VIII.

[00364] Quite surprisingly, the composition according to the invention C1 simultaneously exhibits significantly reduced hysteresis and abrasion properties compared to the control composition T1.

[00365] This clear improvement in hysteresis and abrasion properties is also observed in another elastomer matrix. In fact, composition C2 according to the invention also exhibits much lower hysteresis and abrasion properties than control composition T2.

[00366] In conclusion, these results show that the innovative silica used in the compositions according to the invention makes it possible to obtain rubber compositions with a clear improvement in the compromise of the performance properties of rolling resistance/wear resistance compared to silica used in the rubber compositions for "Green Tires". II.4 TEST B

[00367] The purpose of this test is to demonstrate the improved performance properties of a rubber composition according to the invention, based on an innovative silica, compared to a rubber composition comprising a prior art silica, WO03/016215 -TO 1.

[00368] For this purpose, four rubber compositions are compared, intended especially for the manufacture of tire treads: - the control compositions T3 and T4 contain silica SC2, - the compositions according to the invention C3 and C4 contain the S2 silica.

[00369] The control composition T4 and the composition according to the invention C4 differ respectively from the control composition T3 and the composition according to the invention C3 by the nature of the elastomer and the filler content. The elastomer matrix of compositions T3 and C3 comprises a functionalized diene elastomer and that of compositions T4 and C4 comprises a non-functionalized diene elastomer.

[00370] Table IX presents the formulation of the different compositions, with the contents expressed in phr (parts by weight per hundred parts by weight of elastomers).

[00371] The optimal content of diphenylguanidine (DPG) is tailored depending on the specific BET surface area of the silica to be tested.

[00372] In fact, the greater the BET specific surface area of a silica, the more it is necessary to use a high DPG content in order to cover the silica surface and promote its dispersion. Those skilled in the art know how to adapt these contents depending on the nature of the silica used. The formulations can be compared.

[00373] Each T3 and C3 composition has a density (p) equal to 1.23.

(1) Elastômero: Copolímero de estireno/butadieno SBR, que tem uma função de amina-alcoxissilano no meio da cadeia e tem uma temperatura de transição vítrea, medida de acordo com a norma D3418 de 1999, igual a -48 °C. Sua microestrutura, determinada pelo método NIR, é a seguinte: o teor em peso de unidades 1,4-trans é de 45,1%, o de unidades 1,4-cis é de 30,5% e o de unidades 1,2 é de 24,4% (cada um desses três teores se refere às unidades de butadieno). O teor em peso de unidades de estireno é de 27%; (2) Elastômero: Copolímero de estireno/butadieno não funcionalizado SBR em solução, com temperatura de transição vítrea medida de acordo com a norma D3418 de 1999 igual a -48 °C. Sua microestrutura, determinada pelo método NIR, é a seguinte: o teor em peso de unidades 1,4-trans é de 50%, o de unidades 1,4-cis é de 26% e o de unidades 1,2 é de 24% (cada um desses três teores se refere às unidades de butadieno). O teor em peso de unidades de estireno é de 26,5%; (3) negro de fumo grau N234 comercializado por Cabot Corporation; (4) Agente de acoplamento: Bis[3-(trietoxissilil)propil] Tetrassulfureto de silano (TESPT) comercializado por Evonik sob a referência Si69; (5) DPG: difenilguanidina, comercializada por Flexsys sob a referência Perkacit; (6) Resina: Fração C5/C9 comercializada por Exxon com a referência ECR-373; (7) Plastificante: Óleo de girassol que compreende 85% em peso de ácido oléico, comercializado por Novance sob a referência Lubrirob Tod 1880; (8) Antioxidante: N-(1,3-dimetilbutil)-N-fenil-para-fenilenodiamina comercializado por Flexsys sob a referência Santoflex 6-PPD; (9) Acelerador: N-ciclo-hexil-2-benzotiazolesulfenamida comercializado por Flexsys sob a referência Santocure CBS. As propriedades medidas após a cura a 150 °C por 45 min são mostradas na tabela X.

[00374] Each T4 and C4 composition has a density (p) equal to 1.18. TABLE IX

(1) Elastomer: SBR styrene/butadiene copolymer, which has an amine-alkoxysilane function in the middle of the chain and has a glass transition temperature, measured according to D3418 of 1999, equal to -48 °C. Its microstructure, determined by the NIR method, is as follows: the content by weight of 1,4-trans units is 45.1%, that of 1,4-cis units is 30.5% and that of 1, 2 is 24.4% (each of these three contents refers to butadiene units). The content by weight of styrene units is 27%; (2) Elastomer: SBR non-functionalized styrene/butadiene copolymer in solution, with a glass transition temperature measured in accordance with D3418 of 1999 equal to -48 °C. Its microstructure, determined by the NIR method, is as follows: the content by weight of 1,4-trans units is 50%, that of 1,4-cis units is 26% and that of 1,2 units is 24 % (each of these three levels refers to butadiene units). The content by weight of styrene units is 26.5%; (3) carbon black grade N234 available from Cabot Corporation; (4) Coupling agent: Bis[3-(triethoxysilyl)propyl] Silane tetrasulfide (TESPT) sold by Evonik under the reference Si69; (5) DPG: diphenylguanidine, available from Flexsys under the trade name Perkacit; (6) Resin: C5/C9 fraction marketed by Exxon under the reference ECR-373; (7) Plasticizer: Sunflower oil comprising 85% by weight of oleic acid, marketed by Novance under the reference Lubrirob Tod 1880; (8) Antioxidant: N-(1,3-dimethylbutyl)-N-phenyl-para-phenylenediamine sold by Flexsys under the reference Santoflex 6-PPD; (9) Accelerator: N-cyclohexyl-2-benzothiazolesulfenamide sold by Flexsys under the trade name Santocure CBS. The measured properties after curing at 150 °C for 45 min are shown in table X.

[00375] Quite surprisingly, the composition according to the invention C3 simultaneously exhibits significantly reduced hysteresis and abrasion properties compared to the control composition T3.

[00376] This clear improvement in hysteresis and abrasion properties is also observed in another elastomer matrix. In fact, composition C4 according to the invention also exhibits much lower hysteresis and abrasion properties than control composition T4.

[00377] In conclusion, these results show that the innovative silica used in the compositions according to the invention makes it possible to obtain rubber compositions with a clear improvement in the compromise of the performance properties of rolling resistance/wear resistance compared to silica used in prior art rubber compositions. II.5 TEST C

[00378] The purpose of this test is to demonstrate the improved performance properties of a rubber composition according to the invention, based on an innovative silica, compared to a rubber composition comprising a prior art silica, WO03/106339 -TO 1.

[00379] For this purpose, two rubber compositions are compared, intended for the manufacture of tire treads: - the control composition T5 contains silica SC3, - the composition according to the invention C5 contains silica S1.

[00380] Table XI presents the formulation of the different compositions, with the contents expressed in phr (parts by weight per hundred parts by weight of elastomers).

[00381] The content of agent for coupling the elastomer to the reinforcing inorganic filler and the content of diphenylguanidine (DPG) are adapted respectively to the specific surface area of CTAB and BET of the silica to be tested. In fact, the greater the SCTAB specific surface area of a silica, the greater the number of potential binding sites between the reinforcing inorganic filler and the elastomer and, therefore, the greater the amount of said coupling agent required to promote bonds between the reinforcing inorganic filler and the elastomer. reinforcing inorganic filler and the elastomer. Furthermore, the greater the BET specific surface area of a silica, the more it is necessary to use a high DPG content in order to cover the silica surface and promote silica dispersion. Those skilled in the art know how to adapt these contents depending on the nature of the silica used. The formulations can be compared.

(1) Elastômero: Copolímero de estireno/butadieno SBR, que tem uma função de amina-alcoxissilano no meio da cadeia e tem uma temperatura de transição vítrea, medida de acordo com a norma D3418 de 1999, igual a -48 °C. Sua microestrutura, determinada pelo método NIR, é a seguinte: o teor em peso de unidades 1,4-trans é de 45,1%, o de unidades 1,4-cis é de 30,5% e o de unidades 1,2 é de 24,4% (cada um desses três teores se refere às unidades de butadieno). O teor em peso de unidades de estireno é de 27%; (2) negro de fumo grau N234 comercializado por Cabot Corporation; (3) Agente de acoplamento: Bis[3-(trietoxissilil)propil] Tetrassulfureto de silano (TESPT) comercializado por Evonik sob a referência Si69; (4) DPG: difenilguanidina, comercializada por Flexsys sob a referência Perkacit; (5) Resina: Fração C5/C9 comercializada por Exxon com a referência ECR-373; (6) Plastificante: Óleo de girassol que compreende 85% em peso de ácido oléico, comercializado por Novance sob a referência Lubrirob Tod 1880; (7) Antioxidante: N-(1,3-dimetilbutil)-N-fenil-para-fenilenodiamina comercializado por Flexsys sob a referência Santoflex 6-PPD; (8) Acelerador: N-ciclo-hexil-2-benzotiazolesulfenamida comercializado por Flexsys sob a referência Santocure CBS.[00382] Each composition T5, C5 has a density (p) equal to 1.23.

(1) Elastomer: SBR styrene/butadiene copolymer, which has an amine-alkoxysilane function in the middle of the chain and has a glass transition temperature, measured according to D3418 of 1999, equal to -48 °C. Its microstructure, determined by the NIR method, is as follows: the content by weight of 1,4-trans units is 45.1%, that of 1,4-cis units is 30.5% and that of 1, 2 is 24.4% (each of these three contents refers to butadiene units). The content by weight of styrene units is 27%; (2) carbon black grade N234 available from Cabot Corporation; (3) Coupling agent: Bis[3-(triethoxysilyl)propyl] Silane tetrasulfide (TESPT) sold by Evonik under the reference Si69; (4) DPG: diphenylguanidine, sold by Flexsys under the trade name Perkacit; (5) Resin: C5/C9 fraction marketed by Exxon under the reference ECR-373; (6) Plasticizer: Sunflower oil comprising 85% by weight of oleic acid, marketed by Novance under the reference Lubrirob Tod 1880; (7) Antioxidant: N-(1,3-dimethylbutyl)-N-phenyl-para-phenylenediamine sold by Flexsys under the reference Santoflex 6-PPD; (8) Accelerator: N-cyclohexyl-2-benzothiazolesulfenamide sold by Flexsys under the trade name Santocure CBS.

[00383] The properties measured after curing at 150 °C for 45 min are described in Table XII.

[00384] Quite surprisingly, the composition according to the invention C5 simultaneously exhibits significantly reduced hysteresis and abrasion properties compared to the control composition T5.

[00385] An improvement in the compromise of performance properties of rolling resistance/wear resistance is therefore observed with the composition according to the invention C5 comprising the innovative silica S1 as reinforcing inorganic filler, compared to the composition of T5 control. II.6 TEST D

[00386] The purpose of this test is to demonstrate the improved performance properties of rubber compositions according to the invention, based on innovative silicas, compared to a rubber composition used conventionally and marketed in "green tires".

[00387] For this purpose, two rubber compositions are compared, intended for the manufacture of tire treads: - the control composition T1 contains silica SC1, - the compositions according to the invention C6, C7 and C8 are modalities different from the invention.

[00388] Table XIII presents the formulation of the different compositions, with the contents expressed in phr (parts by weight per hundred parts by weight of elastomers).

[00389] The content of agent for coupling the elastomer to the reinforcing inorganic filler and the content of diphenylguanidine (DPG) are adapted respectively to the specific surface area of CTAB and BET of the silica to be tested. In fact, the greater the SCTAB specific surface area of a silica, the greater the number of potential binding sites between the reinforcing inorganic filler and the elastomer and, therefore, the greater the amount of said coupling agent required to promote bonds between the reinforcing inorganic filler and the elastomer. reinforcing inorganic filler and the elastomer. Furthermore, the greater the BET specific surface area of a silica, the more it is necessary to use a high DPG content in order to cover the silica surface and promote silica dispersion. Those skilled in the art know how to adapt these contents depending on the nature of the silica used. The formulations can be compared.

(1) Elastômero: Copolímero de estireno/butadieno SBR, que tem uma função de amina-alcoxissilano no meio da cadeia e tem uma temperatura de transição vítrea, medida de acordo com a norma D3418 de 1999, igual a -48 °C. Sua microestrutura, determinada pelo método NIR, é a seguinte: o teor em peso de unidades 1,4-trans é de 45,1%, o de unidades 1,4-cis é de 30,5% e o de unidades 1,2 é de 24,4% (cada um desses três teores se refere às unidades de butadieno). O teor em peso de unidades de estireno é de 27%; (3) negro de fumo grau N234 comercializado por Cabot Corporation; (4) Agente de acoplamento: Bis[3-(trietoxissilil)propil] Tetrassulfureto de silano (TESPT) comercializado por Evonik sob a referência Si69; (5) DPG: difenilguanidina, comercializada por Flexsys sob a referência Perkacit; (6) Resina: Fração C5/C9 comercializada por Exxon com a referência ECR-373; (7) Plastificante: Óleo de girassol que compreende 85% em peso de ácido oléico, comercializado por Novance sob a referência Lubrirob Tod 1880; (8) Antioxidante: N-(1,3-dimetilbutil)-N-fenil-para-fenilenodiamina comercializado por Flexsys sob a referência Santoflex 6-PPD; (9) Acelerador: N-ciclo-hexil-2-benzotiazolesulfenamida comercializado por Flexsys sob a referência Santocure CBS.[00390] Each composition T1, C6, C7 and C8 has a density (p) equal to 1.23.

(1) Elastomer: SBR styrene/butadiene copolymer, which has an amine-alkoxysilane function in the middle of the chain and has a glass transition temperature, measured according to D3418 of 1999, equal to -48 °C. Its microstructure, determined by the NIR method, is as follows: the content by weight of 1,4-trans units is 45.1%, that of 1,4-cis units is 30.5% and that of 1, 2 is 24.4% (each of these three contents refers to butadiene units). The content by weight of styrene units is 27%; (3) carbon black grade N234 available from Cabot Corporation; (4) Coupling agent: Bis[3-(triethoxysilyl)propyl] Silane tetrasulfide (TESPT) sold by Evonik under the reference Si69; (5) DPG: diphenylguanidine, available from Flexsys under the trade name Perkacit; (6) Resin: C5/C9 fraction marketed by Exxon under the reference ECR-373; (7) Plasticizer: Sunflower oil comprising 85% by weight of oleic acid, marketed by Novance under the reference Lubrirob Tod 1880; (8) Antioxidant: N-(1,3-dimethylbutyl)-N-phenyl-para-phenylenediamine sold by Flexsys under the reference Santoflex 6-PPD; (9) Accelerator: N-cyclohexyl-2-benzothiazolesulfenamide sold by Flexsys under the trade name Santocure CBS.

[00391] The properties measured after curing at 150 °C for 45 min are described in Table XIV.

[00392] Compared with the control composition T1, the compositions of the invention C6, C7 and C8 comprising innovative silicas with different morphology, all exhibit decreased abrasion, synonymous with good wear resistance.

[00393] The compositions according to the invention C6 and C7 also have very good hysteresis properties compared to the control composition T1.

[00394] The composition C8 has a hysteresis slightly higher than that of the control composition T1. However, this slight deterioration remains acceptable for use in tires and the gain in abrasion from this composition is significant.

Claims (15)

1. Rubber composition characterized by being based on at least one elastomer, an inorganic reinforcing load, an agent for coupling the elastomer to the inorganic reinforcing load and a reticulation system; said reinforcing inorganic filler comprising at least one silica S having: - a specific surface area of CTAB SCTAB within a range extending from 40 to 300 m2/g; - a difference between the specific surface area of BET SBET and the specific surface area of CTAB SCTAB greater than or equal to 35 m2/g; - a WAl aluminum content within a range extending from 0.5 to 7.0% by weight relative to the weight of silica S; - a breadth of aggregate size distribution Ld, measured by centrifugal sedimentation, greater than or equal to 1.5; and - an average aggregate diameter d50, measured by centrifugal sedimentation, so that, for a given CTAB SCTAB specific surface area value and a given WAl aluminum content, a magnitude A is defined by the following equation (I):

where: [d50] is the numerical value of d50, expressed in nm; [SCTAB] is the numerical value of SCTAB, expressed in m2/g; [WAl] is the numerical value of WAl, expressed in % by weight in relation to the weight of silica S; and said magnitude A satisfies the relation (II):

2. Rubber composition, according to claim 1, characterized by the fact that the ratio (II) is:

3. Rubber composition, according to claim 1 or 2, characterized in that the WAI aluminum content of the silica S is within a range extending from 0.5 to 5.0%, more preferably from 0 .8 to 3.5%, even more preferably from 1.0% to 3.0% by weight relative to the weight of the S silica. 4. Rubber composition according to any one of claims 1 to 3, characterized in that the amplitude of the aggregate size distribution Ld, measured by centrifugal sedimentation, of silica S is within a range that extends from 1 .5 to 3.5. 5. Rubber composition according to any one of claims 1 to 4, characterized in that the difference between the specific surface area of BET (SBET) and the specific surface area of CTAB (SCTAB) of silica S is greater than or equal to 40 m2/g, preferably greater than or equal to 45 m2/g, more preferably greater than or equal to 50 m2/g, even more preferably greater than or equal to 55 m2/g. 6. Rubber composition according to any one of claims 1 to 5, characterized in that the specific surface area of CTAB SCTAB of silica S is within a range extending from 110 to 300 m2/g. 7. Rubber composition according to any one of claims 1 to 6, characterized in that the silica S has a specific surface area of BET SBET greater than or equal to 160 m2/g, preferably greater than or equal to 170 m2 /g, more preferably greater than or equal to 180 m2/g. 8. Rubber composition according to any one of claims 1 to 7, characterized in that the reinforcing inorganic filler also comprises an additional silica other than S silica. 9. Rubber composition according to any one of claims 1 to 8, characterized by the fact that the content of inorganic reinforcing filler is within a range extending from 10 to 200 phr, preferably from 30 to 150 phr. 10. Rubber composition according to any one of claims 1 to 9, characterized in that it also comprises an organic reinforcing filler, preferably carbon black. 11. Composition according to any one of claims 1 to 10, characterized in that the elastomer is a diene elastomer. 12. Process for preparing a rubber composition, of the type defined in any one of claims 1 to 10, characterized in that it comprises the following steps: • at least one elastomer, at least one inorganic reinforcing filler and at least one agent to couple the elastomer to the reinforcing inorganic load they are placed in contact; said reinforcing inorganic filler comprising at least one S silica having: • a specific surface area of CTAB SCTAB within a range extending from 40 to 300 m2/g; • a difference between the specific surface area of BET SBET and the specific surface area of CTAB SCTAB greater than or equal to 35 m2/g; • a WAl aluminum content within a range extending from 0.5 to 7.0% by weight in relation to the weight of S silica; • a breadth of aggregate size distribution Ld, measured by centrifugal sedimentation, greater than or equal to 1.5; and • an average aggregate diameter d50, measured by centrifugal sedimentation, so that, for a given CTAB SCTAB specific surface area value and a given WAl aluminum content, an A magnitude is defined by the following equation (I):

where: [d50] is the numerical value of d50, expressed in nm; [SCTAB] is the numerical value of SCTAB, expressed in m2/g; [WAl] is the numerical value of WAl, expressed in % by weight in relation to the weight of silica S; and said magnitude A satisfies the relation (II):

• everything is thermomechanically kneaded, once or several times, until a maximum temperature between 110 °C and 190 °C is reached; • the mixture from the previous step is cooled to a temperature below 100 °C, • a reticulation system is incorporated into the cooled mixture from the previous step, • the mixture comprising the reticulation system is kneaded to a maximum temperature below 110 °C. 13. Semi-finished article characterized by the fact that it comprises at least one composition, of the type defined in any one of claims 1 to 10, or capable of being obtained by the process, of the type defined in claim 12. 14. Semi-finished article, according to claim 13, characterized in that it is a tire tread. 15. Tire characterized in that it comprises at least one composition, of the type defined in any one of claims 1 to 10, or that it comprises at least one semi-finished article of the type defined in claim 13 or 14.