CA2310131A1 - Rubber composition for tyres, reinforced with a carbon black coated with an aluminous layer - Google Patents

Abstract

The invention concerns a sulphur-vulcanisable rubber composition, capable of being used for making tyres, comprising at least a diene elastomer, a reinforcing filler and a coupling agent ensuring the bond between the reinforcing filler and the elastomer. The invention is characterised in that said reinforcing filler consists wholly or partly of a modified carbon black having the following characteristics: (i) it is coated at least partly with an aluminium oxide and/or hydroxide layer; (ii) its specific BET surface ranges between 30 and 400 m?2¿/g; (iii) its average particle size (in volume), marked d¿w?, ranges between 20 and 400 nm; (iv) its deagglomeration rate, marked .alpha., measured by the so-called ultrasound-deagglomeration test, at 10 % of the power of an ultrasound probe of 600 watts, is greater than 1.10?-3¿ µm?-1¿/s.

Description

WO 99128380 PCT / EP98 / o7679 _1 RUBBER COMPOSITION FOR TIRES, REINFORCED WITH CARBON BLACK COATED WITH AN ALUMINOUS LAYER
The present invention relates to diene rubber compositions usable pow the manufacture of tires or semi-finished pow tires, in particular of treads of these tires, as well as reinforcing loads likely to reinforcing such rubber compositions.
o In order to reduce fuel consumption and the nuisances emitted by vehicles to motew, significant efforts have been made by the designers of afm tires to obtain tires which at the same time have very low resistance to bearing, one improved grip on both dry and sw wet or snowy soil and a very good resistance to fuswe.
Many solutions have thus been proposed to lower the resistance to rolling and improve (grip of tires, but these are generally reflected by one very large lapse in resistance to wear. He is well known especially that the incorporation of conventional white fillers such as for example the silica (Si02), alumina (Ah03), (titanium oxide (Ti02), chalk, talc, clays such as bentonite or ie kaolin for example, in rubber compositions used pow la manufacture of tires and in particular treads, certainly results in a lowering the rolling resistance and improved grip on wet surfaces, snowy or icy, but also by an unacceptable decline in resistance to the uswe linked to the fact that these conventional white fillers have no reinforcing capacity sufficient vis-à-vis screws such rubber compositions; we generally qualify these white charges, pow this reason, non reinforcing loads also called inert loads.
An effective solution to this problem has been described in the patent application EP-3o which discloses a particular reinforced diene rubber composition silica highly dispersible precipitate. This composition makes it possible to manufacture a pneumatic having a markedly improved rolling resistance, without affecting the other properties, in particularly those of grip, endurance and especially resistance to fuswe.
Since the publication of this application EP-A-0 501 227, the interest for compositions reinforced with silica has been largely revived. However, silicas are so generally more difficult to disperse than carbon blacks. Else share the compositions loaded with silica, compared to those loaded with black carbon, present in known manner (disadvantage of having on the one hand a setting work (ie a 4o aptitude for transformation or "processability" to (raw state plus difficult on the other hand a very high electrical resistance.
Compositions having both hysteresis and improved grip, but still an easy implementation at (raw state, a high level of strengthening, and therefore of resistance to fuswe, as well as a high electrical conductivity were therefore absolutely desirable for tire manufacturers.

WO 99/28380. PCT / EP98 / 07679

-2-The Applicant discovered during its research a new composition which, thanks to a particular reinforcing filler, unexpectedly makes it possible to respond to these different conflicting requirements.
Consequently, a first object of the invention relates to a composition of rubber vulcanizable with sulfur, usable for the manufacture of tires, comprising at least a diene elastomer, a reinforcing filler and a coupling agent liaising between the reinforcing filler and (elastomer, this composition being characterized in that t0 said reinforcing filler is made up in whole or in part of a black of so-called "modified" carbon having the following characteristics:
- (i) it is coated at least in part with an oxide and / or hydroxide layer aluminum;
- (ü) its BET specific surface is between 30 and 400 m = / g;
- (iii) its mean particle size (by mass), denoted dW, is included between 20 and 400 nm;
- (iv) its disagglomeration speed, noted a, measured in the so-called test disaggregation ultrasound, at 10% power of a 600 watt ultrasonic probe, is better than 1.10'3 ~ mvls.
The compositions of the invention, thanks to this modified black and to its combination specific of characteristics, in particular its particular surface properties, possesses not only improved hysteresis and adhesion properties, but also a electrical conductivity high.
Rubber compositions comprising as reinforcing filler carbon blacks with a modified surface, covered with a siliceous layer, have certainly been described in requests of recent patents (see for example EP-A-0 711 805, EP-A-0 799 854, EP-A-0 799 867, W096 / 037547); these new compositions and their potential for application in tires are still poorly understood by tire manufacturers. Compared to these compositions loaded with carbon covered in a siliceous layer, compositions by (invention have at least the significant advantage that the aluminous layer of area deposited on the surface of their reinforcing filler, made of oxides and / or aluminum hydroxides which in known manner are more stable and chemically more reactive than oxides of silicon, will therefore be more adherent to black particles and more reactive that cannot (be a siliceous layer. In addition, compared to compositions loaded with even silica made of highly dispersible silica, the compositions of (invention the advantage of have an implementation at (raw state which is facilitated.
Patent application WO97 / 42256 describes compositions for rubber diene which can incorporate, as reinforcing filler, blacks of carbon treated directly in the carbon black synthesis reactor by various metal compounds in particular in the form of oxides, hydroxides or carbides of different metals (e.g. aluminum, zinc, magnesium, calcium, titanium, vanadium, cobalt, nickel, .zirconium, tin, antimony, chromium, neodymium, lead, tellurium, barium, cesium, iron, molybdenum). The blacks thus treated at very high temperature in the reactor of synthesis

-3-actually consist of two-phase hybrid aggregates or particles, formed by a mixture intimate carbon black and metallic compound, the metallic compound being located so much inside that near the surface of the aggregates; it is specified in particular that the content of metal atom can reach 50% or even 99% of the mass of f aggregate final (% in mass). It is clear that such hybrid charges, if they were released by a any means of their metal compound fraction, for example by a treatment chemical, would have neither the morphology nor your properties of a black of carbon conventional, but those of carbonaceous residues with high porosity. In this, the carbon blacks treaties described in W097 / 42256 should not be confused with blacks of carbon t0 only coated with a layer of metallic compound which, after elimination of such coating, would find their original structure.
Nothing is said further in W097 / 42256 on a rubber composition according to (invention, loaded with a modified carbon black having the characteristics specific of BET surface. particle size dW and deagglomeration speed a mentioned above.
The subject of the invention is also (use of a composition of rubber conforms to (invention for the manufacture of rubber articles, in particular of tires or semi-finished rubber products for these tires, these articles being semi-finished 2o chosen in particular from the group consisting of treads, underlayers intended for example to be placed under these treads, the plies summit, the sidewalls, carcass plies, heels, protectors, inner tubes or the gums waterproof interior for tubeless tires. The invention relates more particularly (use of such a rubber composition for the manufacture of flanks or bands of rolling. due to its good hysteretic properties.
The subject of the invention is also these tires and these articles in rubber themselves when they comprise a rubber composition in accordance with (invention.
The composition in accordance with (invention is particularly suitable for making tapes rolling of tires intended to equip passenger vehicles, van, two-wheelers and heavy goods vehicles, aircraft, civil engineering, agricultural, or handling, these treads that can be used in the manufacture of new tires or for retreading used tires.
The invention and its advantages will be easily understood in the light of the description and examples of embodiments which follow, as well as FIGS. 1 to 3 relating to these examples that represent:
- a device diagram capable of measuring the disaggregation speed at ultrasound (a) a filler in the form of agglomerates (fig. 1);
- evolution curves of the size of the agglomerates during a Bonus to (help of the device of FIG. 1, for loads conforming or not to (invention, curves from from which the disaggregation rates a are determined (fig. 2 and fig.
3}.

-4-I. MEASUREMENTS AND TESTS USED
The reinforcing fillers used are characterized as indicated below.
1o The BET specific surface is determined in a known manner, according to the Brunauer's method-Emmet-Teller described in "The Journal of the American Chemical Society" Vol.
60, page 309, February 1938 and corresponding to standard AFNOR-NF-T45-007 (November 1987).
h size m take y; ~, particles dW ~
The average particle size (in mass), denoted dw, is measured so classic after dispersion ;, by ultrasonic deagglomeration, of the charge to be analyzed in a solution aqueous with 15% ethanol and 0.05% of an ionic nbn surfactant (% by volume).
2o The "particle" tenure used in this application must be understood in his sense usual generic of aggregate, not that of elementary particle possible form part of this aggregate (by aggregate, we must understand in a way known a whole non-breaking of elementary particles, produced during the synthesis of charge).
The determination takes place using a standard centrifugal photosedimentometer "DCP"("Disk Centrifuge Photosedimentometer "sold by Brookhaven Instruments).
A suspension of 10 mg of carbon black is previously carried out in 40 m1 of a 15% ethanol and 0.05% aqueous solution of a nonionic surfactant (% in volume), per action for 10 minutes at 60% power (i.e. 60% of the maximum position of the "tip amplitude ") of a 600 watt ultrasonic probe (Vibracell 1/2 Sonicator thumb marketed by the company Bioblock). During sonication, a gradient composed of 15 ml of water (0.05% of a nonionic surfactant) and 1 ml of ethanol is injected into the sediment disc rotates at 8000 rpm to form a "step gradient".
Then 0.3 ml of the carbon black suspension is injected at the surface gradient; after sedimentation for 120 min, the mass distribution of the sizes of particle and size mass average dw (dW = E (n; d; s) IE (n; d °) with n; number of objects of the size class d;) are calculated by the sedimentometer software.
The disaggregation speed noted a is measured in the test called "test of disaggregation in ultrasound ", at 10% power of a 600 watt probe. This test allows measure in continuous (evolution of the size of the agglomerates of particles during a Bonus, according to indications below.

-5-The assembly used consists of a laser granulometer (type "Mastersizer"
S ", marketed by Malvern Instruments - He-Ne laser source emitting in the red, length wave 632.8 nm) and its preparer ("Maivern Small Semple Unit MSX1"), between which summer a continuous flow treatment cell (Bioblock M72410) inserted a probe ultrasonic (1/2 inch Vibracell sonicator of 600 watts marketed by the Society Bioblock).
A small amount (15 mg) of filler to be analyzed is introduced into the preparer with 160 ml of an aqueous solution containing 20% by mass of ethanol, the speed of traffic being 1o fixed at its maximum. At least three consecutive measurements are performed to determine according to the known Fraunhofer calculation method (Malvern calculation matrix 3 ~ $ D} the average initial diameter (by volume) of the agglomerates, denoted by "[0].
sonification is then established at a power of 10% (ie 10% of the maximum position of the "tip amplitude ") and we follow for about 8 minutes (evolution of the mean diameter in volume from "[t] to time function "t" at a rate of approximately every 10 seconds. After a period induction about 3 minutes, it is observed that (inverse of the volume average diameter l / d "[t] varies linearly with time "t" (stable deagglomeration regime). Speed of disaggregation a is calculated by linear regression of the curve evolution of l / d "[t] in as a function of time "t", in the area of stable deagglomeration regime. She is expressed in ~ mt / s.
By way of example and reference, the ultrasonic deagglomeration test above, applied to a control silica well known to those skilled in the art for its very high dispersibility (silica marketed by Rhône-Poulenc under the reference Zeosil 1165MP), leads to a deagglomeration speed, denoted ao, of approximately 1.5 × 10 −3 ~ mi / s.
Figure 1 shows schematically an example of mounting the measuring device usable for carrying out this ultrasound deagglomeration test. These measures consists of a circuit closed 1 in which a flow 2 of agglomerates of particles can circulate suspension in a liquid 3. This device essentially comprises a sample preparer 10, a laser granulometer 20 and a treatment cell 30. A pressurization atmospheric (I3, 33), at the level of the sample preparer 10 and the cell treatment 30 itself, allows the continuous elimination of air bubbles that form during the Bonus (ie the action of the ultrasound probe).
Sample preparer 10 ("Maivern Smail Semple Unit MSXI") is intended to receive (load sample to be tested (as is or already suspended in the liquid 3) and (send through circuit 1 at a set speed (potentiometer 17}, under the shape of a stream 2 of liquid suspension. This preparer 10 simply consists of a tank of reception which 4o contains, and through which circulates, the suspension to be analyzed. It is fitted with a motor agitation 15, at adjustable speed, in order to avoid sedimentation of the agglomerates of particles of the suspension; a centrifugal mirai-pump 16 is intended for provide traffic suspension 2 in circuit 1; entry 11 of preparer 10 is linked to free pair via a opening 13 intended to receive the load sample to be tested and / or liquid 3 used for suspension.

WO 99128380 PCTItrP98 / 07679

-6-To the preparer 10 is connected a laser granulometer 20 ("Mastersizer S") of which the function is continuously measure, at regular time intervals, the average size "d ~" of agglomerates, as flow 2 passes, thanks to a measuring cell 23 at which are coupled the automatic recording and calculation means of the particle size analyzer 20. On call here briefly that laser granulometers use, in a known manner, the principle of diffraction of light by solid objects suspended in a medium whose index of refraction is different from that of solid. According to the theory of Fraunhofer, there is a relation between the size of (object and the angle of diffraction of light (more (object is small and to plus The diffraction angle will be high). In practice, it is enough to measure the amount of light diflâractée for difl'érent angles of diffraction to be able to determine the size distribution (in volume) of the sample, d "corresponding to the average of this distribution (d ~, = E (n;
d; 4) IF {n; d; 3) with n; number of objects of size class d;).
ts Interposed between the preparer 10 and the laser granulometer 20 is finally a cell treatment 30 equipped with an ultrasonic probe 35 (converter 34 and head probe 36) intended continuously breaking up the agglomerates of particles as flow 2 passes.
It is preferred that the processing cell 30 is disposed between the outlet 22 of the particle size analyzer 20 2o and (inlet 11 of the preparer 10, so that, in operation, stream 2 of particles leaving the preparer 10 first passes through the laser granulometer 20 before coming in in processing cell 30. This arrangement has two major advantages for measurements on the one hand, the air bubbles due to the faction of the ultrasonic probe are eliminated when crossing the preparer 10 (which is in the open air), that is to say before entering the particle size analyzer 20; they 2s therefore do not disturb the laser diffraction measurement; on the other hand, the homogeneity of the suspension is improved by prior passage through the preparer 10.
The processing cell 30 is preferably arranged in such a way that the stream 2 of particles entering it, through an entrance 31, first passes in front of the head 36 of the probe 3o ultrasound 35; this unconventional arrangement (flow 2 enters by the bottom 31 of the cell, and not from above 32) has the following advantages: on the one hand, the whole suspension flow 2 is forced to pass in front of the end 36 of the ultrasound probe 35, most active in terms of disaggregation; on the other hand, this provision allows a first degassing after enhancement in the body of the treatment cell 30 itself even the surface 35 of the suspension 2 then being in contact with the atmosphere by means of a pipe 33 low diameter.
Flow 2 is preferably thermostatically controlled by means of a cooling 40 arranged, at cell 30, in a double envelope surrounding the probe 35, the 4o temperature being controlled for example by a temperature probe 14 diving into the liquid 3 at the level of the preparer 10. The arrangement of the different elements of the device measurement is optimized so as to limit the volume as much as possible circulating, that is to say the length of connecting pipes (e.g. flexible pipes).

-7-The rubber compositions are characterized, before and after curing, as shown below after.
An oscillating consistometer is used as described in standard AFNOR-NF-(November 1980). The Mooney plasticity measurement is done according to the principle next: the 1o composition (raw state is molded in a cylindrical enclosure heated to 100 ° C. After one minute of preheating, the rotor turns within (test tube at 2 rpm and we measure the useful torque to maintain this movement after 4 minutes of rotation. The plasticity Mooney (ML 1 + 4) is expressed in "Mooney units" (MU).
~ l tensile tests:
These tests make it possible to determine the elasticity stresses and the breaking properties. They are carried out, unless otherwise indicated, in accordance with standard AFNOR-NF-September 1988.
We measure in second elongation (ie after an accommodation cycle) Ies secant modules to 10% elongation (M10), 100% elongation (M100) and 300% elongation (M300), calculated by reducing to the real section of the test piece. All of these traction measurements are performed under normal temperature and humidity conditions according to Standard AFNOR-NF-T40-i01 (December 1979).
Hysteretic losses (PH) are measured by rebound at 60 ° C in the 6th shock, and expressed in % according to the following relation:
PH (%) = 100 [(WO -W ~) / Wp], with Wo: energy supplied; W1: energy returned.
The dynamic properties, denoted OG 'and tan (8) m ~, measured as a function of the deformation, are performed at 10 Hertz with a peak-peak deformation ranging from 0.15% to 50%. Non-linearity aG 'is the difference in shear modulus between 0.15% and 50%
deformation, expressed in MPa. The hysteresis is expressed by the measurement of tan (8) m ~ which corresponds to 4o maximum tan (8).

-g-II. CONDITIONS FOR CARRYING OUT THE INVENTION
In addition to the usual additives or those likely to be used in a composition of rubber vulcanizable with sulfur and usable for the manufacture of tires, the seion compositions (invention comprising at least as basic constituents a diene elastomer, a reinforcing filler and a coupling agent between the charge reinforcing and the elastomer, said reinforcing filler being made up of all or part of a modified carbon black as described in detail below.
By "diene" elastomer or rubber is understood in known manner a elastomer from less in part (ie a homopolymer or a copolymer) of diene monomers (monomers carriers of two carbon-carbon double bonds, conjugated or not).
Generally, the term diene elastomer is understood here to mean "essentially unsaturated "a diene elastomer derived at least in part from conjugated diene monomers, having a rate of units or units of diene origin (conjugated dienes) which is greater than 15%
(% in moles).
Thus, for example, diene elastomers such as butyl rubbers or copolymers of dienes and alpha-olefins of the EPDM type do not enter the definition previous and can be qualified in particular as diene elastomers "essentially saturated "(rate of motifs of diene origin low or very low, always less than 15%).
In the category of "essentially unsaturated" diene elastomers, hear in particular by "highly unsaturated" diene elastomer an elastomer diene having a rate of motifs of diene origin (conjugated dienes) which is greater than 50%.
These definitions being given, we mean in particular by elastomer diene likely to be used in the compositions in accordance with the invention:
(a) - any homopolymer obtained by polymerization of a conjugated diene monomer having from 4 to 12 carbon atoms;
(b) - any copolymer obtained by copolymerization of one or more dienes conjugates with each other or with one or more vinyl aromatic compounds having from 8 to 20 atoms of carbon;
(c) - any ternary copolymer obtained by copolymerization of ethylene, of an a-olefin 4o having 3 to 6 carbon atoms with a non-conjugated diene monomer having 6 to 12 carbon atoms, such as elastomers obtained from ethylene, propylene with an unconjugated diene monomer of the aforementioned type such as especially 1,4-hexadiene, ethylidene norbornene, dicyclopentadiene;
(d) - any copolymer of isobutene and isoprene (butyl rubber), as well as the halogenated, in particular chlorinated or brominated, versions of this type of copolymer.

Although it applies to any type of diene elastomer, those skilled in the art tire will understand that the present invention is first implemented with elastomers essentially unsaturated diene, in particular of the type (a) or (b) above above.
By way of conjugated dienes, in particular 1,3-butadiene, 2-1,3-methyl-butadiene, 2,3-di (C1-CS 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, aryl-1,3-butadiene, 1,3-pentadiene, 2,4-hexadiene.
o As vinyl-aromatic compounds suitable, for example, styrene, fortho-, meta-, para-methylstyrene, the commercial "vinyl-toluene" mixture, para-tertiobutylstyrene, the methoxystyrenes, chlorostyrenes, vinyl mesitylene, divinylbenzene, vinylnaphthalene.
The copolymers can contain between 99% and 20% by weight of units diene and from 1% to 80% by weight of vinyl aromatic units. Elastomers can have any microstructure which is a function of the polymerization conditions used, in particular the presence or not of a modifying and / or randomizing agent and quantities of modifying agent and / or randomizing employed. The elastomers can for example be block, statistical, sequenced, 2 micro-sequenced, be prepared in dispersion or in solution.
Preferably polybutadienes and in particular those having a content of -1.2 units between 4% and 80% or those with cis-1.4 content greater than 80%, polyisoprenes, butadiene-styrene copolymers and in particular those having a styrene content between S% and 50% by weight and more particularly between 20% and 40%, a bond content -1.2 of the butadiene part of between 4%
and 65%, one content of trans-1,4 bonds of between 20% and 80%, the copolymers of butadiene-isoprene and in particular those having an isoprene content of between 5% and 90% by weight and a glass transition temperature (Tg) between -40 ° C and -80 ° C, isoprene copolymers-3o styrene and in particular those having a styrene content of between 5% and 50% by weight and a Tg of between -25 ° C and -50 ° C.
In the case of butadiene-styrene-isoprene copolymers are suitable especially those having a styrene content of between 5% and 50% by weight and more particularly between 10% and 40%, an isoprene content between 15% and 60% in weight and more particularly between 20% and 50%, a butadiene content of between 5% and 50% in weight and more particularly between 20% and 40%, a content of units -1.2 of the butadiene part between 4% and 85%, a content of trans units -1.4 Of the game butadiene between 6% and 80%, a content of -1.2 units plus -3.4 the part 4o isoprene between 5% and 70% and a content of trans units -1.4 of the part isoprene between 10% and 50%, and more generally any copolymer butadiene-stytene-isoprene having a Tg of between -20 ° C and -70 ° C.
Of course, (elastomer can be coupled and / or starred to yet functionalized with an agent coupling and / or star or functionalization. The elastomer can also be of natural rubber or a natural rubber blend with everything elastomer, especially diene, synthetic.
Particularly preferably, (diene elastomer of the conform composition to (invention is chosen from the group of diene elastomers strongly unsaturated constituted by polybutadienes, polyisoprenes or natural rubber, copolymers of butadiene-styrene, butadiene-isoprene copolymers, copolymers isoprene-styrene, butadiene-styrene-isoprene copolymers, or a mixture of two or more of these compounds.
When the composition according to (invention is intended for a strip of bearing for pneumatic, (diene elastomer is preferably a copolymer of butadiene-styrene prepared in solution having a styrene content of between 20% and 30% in weight, one content of vinyl bonds in the butadiene part of between 15% and 65%, one grade t5 in trans-1,4 bonds between ZO% and 75% and a temperature of glass transition between -20 ° C and -55 ° C, this butadiene copolymer-styrene possibly being used in mixture with a polybutadiene preferably have more than 90%
of connections cis-1,4.
The composition according to the invention is reinforced, at least in part, with a carbon black with modified surface, called "modified carbon black" or "modified black", having the following features:
- (i) it is coated at least in part with an oxide and / or hydroxide layer aluminum;
- (ü) its BET specific surface is between 30 and 400 m2 / g;
- (iii) its average particle size (in mass), noted dW, is included between 20 and 400 nm;
- (iv) its disagglomeration speed, noted a, measured in the so-called test disaggregation ultrasound, at 10% power of a 600 watt ultrasonic probe, is better than 1.10-3 pm-1 / s.
By aluminum oxide and / or hydroxide is meant any aluminum compound responding to impurities and water of hydration, to the general formula (I) below (a and b real numbers):
(I) A1 (OH) a O b, with: 0 5 a _ <3 and b = (3-a} / 2.
4o Such a formula includes pure aluminum oxides or aluminas A1203 (a = 0), the tri-aluminum hydroxides Al (OH) 3 (a = 3), the intermediate oxide-hydroxides (0 <a <3), thus as their possible hydrated forms, or a mixture of tri-hydroxides etlou oxide-aluminum hydroxides. This formula is given to the nearest impurities being heard that aluminum oxides and / or hydroxides present on the surface of carbon black amended may contain a certain proportion of impurities linked to the process implemented work for the load manufacturing.

It is generally known that to obtain the reinforcing properties optimal conferred by a charge, it should in particular that the latter be present in the rubbery matrix in a final form which is both the most finely divided possible and distributed as homogeneously as possible. Now, such conditions cannot be carried out only insofar as the load has a very good aptitude, on the one hand to incorporate into the matrix when mixing with the elastomer and other share in disaggregate in order to disperse homogeneously in (elastomer.
to The intrinsic dispersibility of a charge can be assessed with (using the test says of ultrasonic deagglomeration described in chapter I above, by measuring his speed of disaggregation a.
It was found that for a speed a greater than 1.10-3 pm-tls, the black modified presents a ~ 5 good dispersibility, that is to say that few micron agglomerates are observed by reflection in light microscopy on a section of rubber composition prepared according to the rules of wax.
For an even better dispersion of the modified black in the matrix of diene rubber, 2o and therefore for optimal reinforcement, it is preferred that the speed of disaggregation has either greater than 1.5 10-3 µm-1 / s. This is particularly advantageous in particular when (invention is implemented for the manufacture of treads exhibiting low rolling resistance.
25 For a BET surface area of less than 30 m2 / g, the compositions have certainly a setting easier work and reduced hysteresis, but there is a decline in properties of breakage and wear resistance in tires; for BET surfaces greater than 400 m = / g, the implementation in the raw state becomes more difficult (Mooney plasticity higher) and the charge dispersion is degraded. For sizes dW too high, greater than 30 400 nm, the particles behave like defects which localize the constraints and are harmful to wear; dW sizes too small, less than 20 nm, on the other hand penalize the implementation at (raw state and the dispersion of the charge during of this setting artwork.
35 For all the reasons explained above, the BET surface area is preference included in a range from 50 to 300 ms / g and the particle size dW is preference included in a range from 30 to 200 nm.
Modified carbon black, thanks to its aluminous surface layer, presents furthermore a 4o high surface reactivity, ie a high rate of reactive functions of surface (Al-OH), vis-with respect to the coupling agent, which is particularly favorable to mechanical properties rubber compositions of the invention, that is to say the function of enhancement filled by the load.
45 Preferably, the level of aluminum (of (element Al) present on the surface of the carbon black modified is greater than 0.25%, more preferably greater than 0.5%, even more WO 99IZ8380 PCT / EP981o7679 preferably adjusted in a range between 0.5% and 5% (% by mass black modified, determined by chemical analysis).
Below the minimums indicated, (effect of lowering fhysteresis can be insufficient, depending on the nature of the compositions used, in particular that of (elastomer, while beyond of the maximum recommended rate, there is generally no longer any improvement in fhysteresis then that one is exposed to the risk of leading on the one hand to a dispersibility too low modified black, known drawback of white charges compared to carbon black, on the other hand to a decrease in adhesion of the aluminous layer to the surface of the black carbon. A rate o greater than 5% would also require larger quantities of precursor product (aluminum alkoxide) or even longer impregnation times during manufacturing what which is economically less attractive.
For an optimization of (adhesion of the aluminous layer to the surface of the black as well as the ~ 5 dispersibility of the filler in the rubber composition, in especially when this composition is intended for a low tire tread resistance to bearing, it is preferred that the aluminum content be adjusted between 0.5% and 3%.
The black modified above can be used alone or combined with another charge reinforcing, by 2o example with a reinforcing silica; in such a case, we use preferably precipitated silica highly dispersible, especially when the invention is used for the manufacture tires with low rolling resistance. As examples no limiting of such preferential highly dispersible silicas, it is possible to quote silica Perlcasil KS 430 from Akzo, silica BV3380 from Degussa, silica Zeosil 1165MP
25 and 1115MP from RhBne-Poulenc, Hi-Sil 2000 silica from the company PPG, silicas Zeopol 8741 or 8745 from the Huber Company.
Modified black, alone or possibly associated with silica, can also be used in cutting, ie in admixture, with conventional carbon black.
Preferably, in the compositions according to (invention, the modified black constitutes the majority, ie more than SO% by weight, of the total reinforcing filler; he can advantageously constitute the entire reinforcing filler.
Preferably, the rate of total reinforcing filler in the compositions by (invention, is included in a field ranging from 20 to 300 pce, more preferably 30 at 150 phr, the optimum being different depending on the intended applications: from known manner, the level of reinforcement expected on a bicycle tire; for example is significantly lower to that required on a passenger vehicle or vehicle tire utility such as 4th heavyweight.
The modified carbon black can be obtained according to the following process:
a) - we start with a pneumatic grade carbon black;

b) - the starting carbon black is impregnated with a colloidal suspension formed by hydrolysis of a solution of aluminum alkoxide in an alcoholic solvent;
c) - the alcoholic solvent is removed by evaporation;
d) - the thus impregnated black is then heat treated so as to transform layer aluminous present on its surface in an adherent layer of oxide and / or hydroxide aluminum.
All carbon blacks are suitable as starting carbon black reinforcing conventionally used in tires, particularly in tapes 1o bearing of these tires, in particular blacks of the HAF type ("High Abrasion Furnace "), ISAF (" Intermediate Super Abrasion Furnace "), SAF (" Super Abrasion Furnace ").
Among these, we will more particularly mention carbon blacks reinforcing series 100, 200 or 300 (ASTM grades).
Preferably, these starting carbon blacks have the characteristics following:
- a BET surface area between 20 and 200 m ~ / g, more preferably between 50 and 170 m = / g;
- an average size (by mass) of particles dW of between 20 and 400 nm, more 2o preferably between 30 and 200 nm.
By way of nonlimiting examples of such preferential starting blacks, we will quote black N115, N134, N234, N339, N347, N375.
By colloidal suspension is meant in known manner a phase suspension solid in a liquid whose size of solid objects is less than one micrometer.
For the formation of the colloidal impregnation suspension, dissolved with stirring and temperature falkoxide aluminum in the selected alcohol, for example methanol, ethanol, (iso) propanol, different isomers of butanol, then hydrolyzed by adding water.
Alkoxide 3o of aluminum used is preferably an aluminum alkoxide comprising 1 to 6 atoms of carbon, for example a methoxide, an ethoxide, an (iso) propoxide or the butoxides aluminum, or a mixture of two or more of these compounds.
The impregnation step can be carried out at room temperature (20 ° C) or at a higher temperature, for example between 30 ° C and 65 ° C depending on the nature of alcohol or alcohols used, of course below the boiling point of the suspension, being understood that the chosen temperature may be close to this temperature of boiling. The duration impregnation is chosen to be long enough, from a few minutes to a few hours depending cases, in order to create sufficient physico-chemical interactions between the black surface of carbon and the aluminum compound.
Preferably, the colloidal impregnation suspension contains acid nitric used at both as a catalyst for hydrolysis of the alkoxide solution and as that peptizing agent for the colloidal suspension. After reaction, the nitric acid will be eliminated by washing with water 4s of impregnated black. Elimination of the alcoholic solvent, after impregnation carbon black, can be carried out by any suitable means, for example by evacuation under empty under agitation.
The heat treatment step is preferably carried out under inert gas, for example under argon, the treatment temperature preferably being between 100 ° C and 900 ° C, more preferably between 150 ° C and 850 ° C. Generally, the higher this temperature of treatment, the higher the formula (I) defined above "moves"
hydroxide worms (oxide (decrease in a and increase in b); one-time treatment temperature of 800 850 ° C, for example, will lead to an essentially aluminous layer made of alumina (A1203).
It is well known in the art that it is necessary to use, to a silica reinforcing, a coupling agent (silica-elastomer), also called liaison, who has for the function of ensuring the connection between the white filler and the elastomer, while facilitating the dispersion of this white charge within the elastomeric matrix.
Modified black, due to its aluminous surface layer, requires also employment 2o of such a coupling agent to fully ensure its charge function strengthening in the rubber composition according to (invention.
By "coupling" agent (filler / elastomer), more precisely means a suitable agent establish a sufficient connection; chemical and / or physical, between the charge considered and the elastomer, while facilitating the dispersion of this charge within the matrix elastomeric; such a coupling agent, at least bifunctional, has by example like simplified general formula "YTX", in which:
Y represents a functional group ("Y" function) which is capable of binding physically and / or chemically to the white charge, such a bond possibly to be established, for example, between a silicon atom of the coupling agent and the groups surface hydroxyl (OH) of the filler (for example surface silanols when he is silica);
- X represents a functional group (function "X") capable of binding physically and / or chemically to (elastomer, for example by (intermediate of a sulfur atom;
- T represents a hydrocarbon group making it possible to link Y and X.
Coupling agents should in particular not be confused with simple agents of 4o recovery of the load considered which, in known manner, includes the function Y
active vis-à-vis the load but are devoid of function X active vis-à-vis opposite (elastomer.
Such coupling agents, of variable effectiveness, have been described in a very large number of documents; see for example 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 or more recent patents US-A-5 580 919, US-A-5 583 245, US-A-5 663 396, US-A-5 684 171, US-A-5 684 172, US-A-5 696 197, which describe in detail ~ such known compounds.
Any known coupling agent can in fact be used to ensure effectively, within diene rubber compositions which can be used for the manufacture of tires, the bond or coupling between silica and diene elastomer, such as organosilanes, in particular of polysulphurized alkoxysilanes such as polysulphides, in particular the tetrasulfides, bis (trialkoxyl (Ct-C4rsilylpropyl), in particular bis (3-trimethoxysilylpropyl) or bis (3-triethoxysilylpropyl). We use in particular Ie t0 bis (3-triethoxysilylpropyl) tetrasulfide, abbreviated TESPT, of formula [(C2H50) 3Si (CH2) 3S2] 2, marketed for example by the company Degussa under the denomination Si69.
Those skilled in the art will be able to adjust the content of coupling agent in the compositions by t5 the invention, depending on the intended application, the nature of the polymer implemented; and some quantity of modified black used, supplemented if necessary by any charge reinforcing white used as an additional charge.
In order to take into account the differences in specific surface and density charges 20 reinforcing materials capable of being used, as well as molar masses agents of coupling, it is preferable to determine the optimal level of coupling agent, for black modified, in moles per square meter of modified black, calculated from the ratio weight [agent of modified black coupling], of the BET surface of the modified black and of the mass agent molar coupling (denoted M below), according to the following relationship:
(moles / m ~ modified black) _ (coupling agent / modified black] (1 BET) (l / tl ~
Of course, an equivalent relation will be applied for example to the silica if it is used as additional reinforcing white filler, to determine also the 3rd optimal rate of additional coupling agent for this silica, in moles per square meter of this white charge.
Preferably, the (total) amount of coupling agent used in the compositions according to the invention is between 10-7 and 10-5 moles per square meter from [black from modified carbon plus, if necessary, an associated reinforcing white filler].
More preferably again, the amount of coupling agent is between 5.10 - ~ and 5.10 -6 moles per square meter of [modified carbon black plus where appropriate white charge reinforcing associated].
Of course, the compositions in accordance with the invention contain, in addition to the compounds already described, all or part of the constituents usually used in the compositions by diene rubber intended for the manufacture of tires, such as by example of plasticizers, pigments, antioxidants, antiozonants, a system of crosslinking at WO 9912838ü PCT / EP98 / 07679 based either on sulfur or on sulfur and / or peroxide donors and / or bismaleimides, vulcanization accelerators, extension oils, etc.
The compositions in accordance with the invention could also contain, in additional dcs coupling agents described above, collection agents for white charge, such as for example alkylalkoxysilanes, polyols, amines. These compositions conform to (invention can be used alone or in combination with any other rubber composition suitable for the manufacture of tires.
to The rubber compositions are prepared by using the diene polymers according to well known techniques, for example by work thermomechanical in one or two stages in an internal paddle mixer, followed by mixing on mixer external.
According to a conventional one-step process, for example, a internal mixer usual all the components necessary for (except the system of vulcanization. The result 2o of this first mixing step is then taken up on a mixer external, usually a cylinder mixer, and then we add the system of vulcanization. A
second step can be added to the internal mixer, basically in order to make undergo the mixture with additional heat treatment.

III. EXAMPLES OF EMBODIMENT OF THE INVENTION
The synthesis is carried out in accordance with the indications given in paragraph II-Chapter 2 II above, according to the specific conditions which follow.
At first, 8.0 g of aluminum isopropoxide (A1 (OCH (CH3) 2) 3 at 98%
sold by the company Sigma) are dissolved in 200 ml of anhydrous ethanol by agitation magnetic at S00 rpm at a temperature of 60 ° C; after a hour, add 42.4 g demineralized water and maintained (stirring at 60 ° C; two hours later add 10 ml 4o concentrated nitric acid (53%) and the temperature is gradually lowered temperature up room temperature, thus leaving (stirring for 12 hours.
so a colloidal suspension by hydrolysis of the alcoholic isopropoxide solution aluminum.

40 g of carbon black N234 are placed in the flask of an evaporator rotary (Rotavapor R-124 from Btichi sold by the company Bioblock). Bath temperature is set to 50 ° C and the speed of rotation at 80 rpm (time "t" = 0). After 55 min of agitation (either t = 55 min), add a third of the impregnation solution, another third to t = 85 min, and finally the last third at t = 115 min. This maintains (agitation for approximately three hours and then we vacuum (t = Sh) to remove excess alcoholic solvent; after 30 minutes the temperature of the bath is fixed at 60 ° C. and agitation is thus continued under vacuum up to t = 7h, for a to complete evacuation of the solvent. The carbon black thus impregnated is then removed from the ball, placed in a vacuum oven (200 mm Hg) and dried at 100 ° C for a night. Black thus treated is then extracted by skin for 48 hours in Soxhlet, then dried again in the same conditions.
y, ~, tra_itement t_hermiy ~ e;
The carbon black is then placed in a tubular oven (Carbolite type marketed by the company Osi), under argon flow (200 ml / min), then subjected cycle next thermal: 30 min at 200 ° C, then 1 hour at 800 ° C; the ramps up temperature are set at 10 ° C / min.
The characteristics of the carbon black thus obtained are summarized in the Table 1. We note that the particle size dw is not significantly changed by compared to the black of on the other hand, but that its BET surface area is however greatly increased, by more 50%. The rate of aluminum is high, around 1.5%, a result well correlated with the rate of ash measure.
On the other hand. the deagglomeration speed a is significantly higher than the lower limit fixed of 1.10-3 wm-1 / s (i.e. 2I3 of ao). A speed of 3.1.10-3 pm-i / s must to be considered here as particularly high, since about 100% higher than the speed ao 3o recorded on a highly dispersible control silica (Zeosil 1165MP).
Figures 2 and 3 show the evolution curves [l / d "(t) = f (t)] of the size of agglomerates, recorded in the ultrasonic disagglomeration test, respectively for the modified black and for this highly dispersible control silica (Zeosil 1165MP), the speed has determined being the slope of the line [1 / d "(t) = f (t)].
We can see in these figures 2 and 3 that the first points recorded ("t"
varying from 0 to 30 s approximately) correspond to the measurement of the initial diameter of "[0], followed (after putting into action of the ultrasonic probe) from a gradual passage (here, "t" from 30 s to 3 min approximately) to a stable diet 4o of disagglomeration during which the inverse of "d""varies well linearly with time "t"
(data recording is stopped here after about 8 minutes.
deducted by a linear regression elementary calculation, supported by the calculator of the granulometer, the deagglomeration speed a in the steady-state zone of disaggregation.
as the starting carbon black N234, meanwhile, has the same disaggregation with ultrasound, a speed particularly high (17.10- '~ m-1 / s - no depicted on figures), which was of course expected given the very high known dispersibility of carbon blacks for tires, in general.
The compositions tested below are prepared in a known manner in mixers laboratory, as follows: we introduce (diene elastomer in a mixer internal 75% filled and the temperature is around 70 ° C, then after an appropriate time of mixing, for example of (order of 1 minute, we add all the others ingredients, including including the load and if applicable (associated coupling agent, except of the system vulcanization. We then conduct a thermomechanical work with a duration of 5.5 minutes approximately, with an average speed of the pallets of 70 rpm, up to get a drop temperature of about 140 ° C. We recover the mixture as well got then we add the vulcanization system on an external mixer (homo-finisher) at 30 ° C. The vulcanization is carried out at 150 ° C (40 min).

We compare below 2 diene rubber compositions intended for the manufacture of tires or tire treads. The SBR elastomer {copolymer of styrene-butadiene) is prepared in solution and comprises 25% of styrene, 58%
of patterns polybutadiene 1-2 and 23% of polybutadiene units 1-4 trans.
These 2 compositions are identical except for the following differences:
- composition No 1 (witness): conventional reinforcing filler constituted by a black carbon type N234;
3o - composition No2 (in accordance with (invention): reinforcing filler constituted exclusively with modified carbon black N234, to which is associated (agent of Si69 {TESP'I ~ coupling.
The coupling agent Si69 was introduced at a rate corresponding to a surface cover 35 of about 9.6.10 -mol / ms of modified carbon black.
Tables 2 and 3 successively give the formulation of the different compositions (table 2 - rate of the various products expressed in pce), their properties before and after baking at 150 ° C for 40 minutes (Table 3).
The study of these different results leads to the following observations:
- the Mooney plasticity value appears lower on the composition in accordance with (invention only on the control composition, in any case revealing result of a very good ability to process raw the composition of (invention;

the composition in accordance with (invention has modulus values, in particular of modules M100 and M300 indicators in a known way of the quality of reinforcement, which are at least equal if not greater than those obtained on the control composition;
to - The composition according to (the invention also has properties very advantageous hysteretics, compared to those offered by the black of carbon conventional, with a very significant reduction in rebound losses (PI-1], of non linearity OG 'and tan (8) ~~.
In summary, the compositions of the invention unexpectedly exhibit properties hysteresis significantly improved, without their setting properties work at (vintage state and after cooking are affected.
t5 These results suggest both good resistance ability to wear and a particularly low rolling resistance for treads of tires, while guaranteeing conductivity for these treads electric satisfactory, sufficient to dissipate charges, for example electrostatic which can forming by friction, in particular when rolling tires.
It is believed that the specific process for preparing the modified black (cold impregnation followed by heat treatment) allows to deposit, on the surface of particles or aggregates of carbon black, a fine, stable, strongly adherent aluminous layer and distributed from relatively homogeneous (average particle size little changed but strong increase in the surface BE'I ~.
Such a coating quality of its reinforcing filler could explain performances unexpected results of the rubber composition according to the invention, improved upon times compared to compositions reinforced with conventional carbon black (reduction in fhysteresis) and by 3o compared to compositions reinforced with precipitated silica even highly dispersible (increased dispersibility; high electrical conductivity).
The compositions of the invention thus offer an interesting alternative to (use of conventional compositions loaded with carbon blacks or silicas highly dispersible, or even carbon blacks coated with a siliceous layer.

_ Zp Table 1 N234 N234 modified Ash 825C / air 0.06 3.24 (%) Rate A1 (%) 0.03 1.49 Densit He (glml) 1.9926 2.0329 BET area (m2 / g) 117 193 dW nm) 65 68 a (~ rri 'Is) 0.0174 0.0031 Table 2 Composition number1 2 SBR {1) 100 100 N234 modified - 50 Si69 - S

Zn0 3 3 Staric acid 1.5 1.5 Antioxidant (2) 1 1 DPG (3) 0.5 0.5 Sulfur 1.5 1.5 _ CBS (4) 2 2 (1) Styrene butadiene copolymer (2) N-1,3 dimethylbutyt N-phenylparAphenylenediamine (3) DiphEnylguanidine (4) N-cyclohexyl-2-benzothiarylsulfenamide Table 3 Composition number1 Z

Plasticit (UM) 106 101 M 10 (MPa) 6.41 6.27 M100 (MPa) 5.32 5.68 M300 (MPa) 14.09 14.25 PH (%) 31.6 28.1 OG * (MPa) 4.81 3.20 ~ (s) m ~ I .345 0.291

Claims (17)

1. Sulfur vulcanizable rubber composition usable for the manufacture of tires, comprising at least one diene elastomer, a filler reinforcing and a coupling agent providing the bond between the reinforcing filler and the elastomer, characterized in that said reinforcing filler consists wholly or partly of a black carbon says "modified" having the following characteristics:
- (i) it is coated at least in part with an oxide and/or hydroxide layer aluminum;
- (ii) its BET specific surface is between 30 and 400 m2/g;
- (iii) its average size (in mass) of particles, denoted dw, is included between 20 and 400nm;
- (iv) its disagglomeration rate, denoted .alpha., measured in the so-called deagglomeration ultrasound, at 10% power of a 600 watt ultrasound probe, is better than 1.10 -3 µm-1/s. 2. Composition according to claim 1, characterized in that the rate of deagglomeration .alpha. is greater than 1.5.10 -3 µm-1/s. 3. Composition according to claims 1 or 2, characterized in that the rate aluminum surface area of the modified carbon black is greater than 0.25% (% by mass). 4. Composition according to claim 3, characterized in that the rate of aluminum surface area of the modified carbon black is between 0.5% and 5%. 5. Composition according to any one of claims 1 to 4, characterized in that the modified carbon black constitutes more than 50% by weight of the filler totally reinforcing. 6. Composition according to claim 5, characterized in that the black of modified carbon represents all of the reinforcing filler. 7. Composition according to any of claims 1 to 6, characterized in it comprises, in addition to the modified carbon black, silica as a filler reinforcing white. 8. Composition according to any one of claims 1 to 7, characterized in that the total reinforcing filler is present at a rate of 20 to 300 phr (parts in weight percent elastomer parts). 9. Composition according to any one of claims 1 to 8, characterized in that the amount of coupling agent is between 10 -7 and 10 -5 mol per meter black square modified carbon and, where appropriate, an associated reinforcing white filler. 10. Composition according to claim 9, characterized in that the amount agent coupling is between 5.10 -7 and 5.10 -6 mole per meter buried with black modified carbon and, where appropriate, an associated reinforcing white filler. 11. Composition according to any one of claims 1 to 10, characterized in that the diene elastomer is selected from the group consisting of polybutadienes, polyisoprenes or natural rubber, butadiene-styrene copolymers, the butadiene-isoprene copolymers, isoprene-styrene copolymers, copolymers of butadiene-styrene-isoprene, or a mixture of two or more of these compounds. 12. Composition according to claim 11, characterized in that the elastomer dienic is a butadiene-styrene copolymer prepared in solution having a content of styrene included between 20% and 30% by weight, a content of vinyl bonds of the part butadiene between 15% and 65%, a content of trans-1,4 bonds between 20%
and 75% and a glass transition temperature between -20°C and -55°C, this copolymer of butadiene-styrene optionally being used as a mixture with a polybutadiene have preferably more than 90% sis-1,4 bonds. 13. Use of a rubber composition according to any from claims 1 to 12 for the manufacture of rubber articles. 14. Use of a rubber composition according to any from claims 1 to 12, for the manufacture of tires or semi-finished products finished in rubber intended for such tires, these semi-finished products being chosen in the group made up of the treads, the underlays of treads rolling, the crown plies, sides, carcass plies, heels, protectors, the air chambers or sealed inner rubbers for tubeless tyres. 15. Rubber article comprising a composition according to any from claims 1 to 12. 16. A tire comprising a composition according to any one of claims 1 to 12: 17. Tire tread based on a composition according to one any of claims 1 to 12.