EP1297055A1 - Rubber composition for tyre comprising a multifunctional polyorganosiloxane as coupling agent - Google Patents

Abstract

The invention concerns a sulphur crosslinkable elastomer composition, for use in the manufacture of tyres, comprising at least: i) an isoprene elastomer, in particular natural rubber; ii) a reinforcing inorganic filler, in particular silica; and iii) as coupling agent (white filler/isoprene elastomer), a multifunctional polyorganosiloxane (POS) comprising, grafted on its silicone atoms, part at least of a hydroxyl or hydrolysable function, at least a group bearing at least an activated double ethylene bond. Said POS is in particular a POS with imide, acid or ester function, whereof the double ethylene bond is activated by at least an adjacent carbonyl group (>C=O). The invention also concerns a tyre or semi-finished product, in particular a running tread for tyre comprising said inventive composition.

Description

 RUBBER COMPOSITION FOR TIRE COMPRISING A MULTIFUNCTIONAL POLYORGANOSILOXANE AS A COUPLING AGENT

The present invention relates to diene rubber compositions reinforced with a white or inorganic filler, intended in particular for the manufacture of tires or semi-finished products for tires, in particular the treads of these tires.

Since fuel economy and the need to protect the environment have become a priority, it is desirable to produce elastomers with good mechanical properties and as little hysteresis as possible so that they can be used in the form of rubber compositions. usable for the manufacture of various semi-finished products used in the constitution of tires such as for example underlays, calendering or sidewall gums or treads and to obtain tires with improved properties, in particular having resistance to reduced turnover.

To achieve such an objective, many solutions have been proposed, first of all essentially concentrated on the use of elastomers modified by means of agents such as coupling agents, star-forming or functionalization agents, with carbon black. as reinforcing filler in order to obtain a good interaction between the modified elastomer and carbon black. It is indeed known, in general, that in order to obtain the optimal reinforcement properties imparted by a filler, it is necessary that the latter is present in the elastomeric matrix in a final form which is both as finely divided as possible and distributed as homogeneously as possible. However, such conditions can only be achieved insofar as the filler has a very good ability, on the one hand to be incorporated into the matrix during mixing with the elastomer and to disaggregate, on the other hand to disperse homogeneously in the elastomer.

In a completely known manner, carbon black exhibits such aptitudes, which is generally not the case for inorganic fillers. For reasons of reciprocal affinities, the particles of inorganic charge have an annoying tendency, in the elastomeric matrix, to agglomerate between them. These interactions have the harmful consequence of limiting the dispersion of the filler and therefore the reinforcing properties to a level substantially lower than that which would theoretically be possible to achieve if all the bonds (inorganic filler / elastomer) capable of being created. during the mixing operation, were actually obtained; on the other hand, these interactions tend to increase the consistency in the raw state of the rubber compositions and therefore to make their implementation ("processability") more difficult than in the presence of carbon black.

The interest in rubber compositions reinforced with an inorganic filler was however strongly revived with the publication of patent application EP 501227 which discloses a diene rubber composition vulcanizable with sulfur, reinforced with a particular precipitated silica (SiO ₂ ) of the highly dispersible type, which makes it possible to manufacture a tire or a tread having a markedly improved rolling resistance, without affecting the other properties in particular those of adhesion, endurance and resistance to wear.

EP 810258 discloses a diene rubber composition reinforced with another particular inorganic filler, in this case a specific alumina (Al O ₃ ) with high dispersibility, which also makes it possible to obtain tires or strips bearing having such an excellent compromise of conflicting properties.

The use of these specific highly dispersible silicas or aluminas, as a majority or not reinforcing filler, has certainly reduced the difficulties of processing the rubber compositions containing them, but this processing nevertheless remains more difficult than for rubber compositions conventionally loaded with carbon black.

In particular, it is necessary to use a coupling agent, also called a bonding agent, which has the function of ensuring the connection between the surface of the particles of inorganic filler and the elastomer, while facilitating the dispersion of this filler inorganic within the elastomeric matrix.

By "coupling" agent (inorganic filler / elastomer) is understood in known manner an agent capable of establishing a sufficient connection, of chemical and / or physical nature, between the inorganic filler and the diene elastomer; such a coupling agent, at least bifunctional, has for example as simplified general formula "Y-G-X", in which:

Y represents a functional group (“Y” function) which is capable of physically and / or chemically binding to the inorganic charge, such a bond being able to be established, for example, between a silicon atom of the coupling agent and surface hydroxyl groups (OH) of the inorganic filler (for example surface silanols when it is silica);

- X represents a functional group ("X" function) capable of physically and / or chemically bonding to the diene elastomer, for example by means of a sulfur atom; - G represents a divalent group making it possible to connect Y and X.

Coupling agents should in particular not be confused with simple inorganic charge covering agents which in known manner may comprise the active Y function with respect to the inorganic charge but are devoid of the active X function with respect to - screw of the diene elastomer.

Coupling agents, in particular (silica / diene elastomer), have been described in a large number of documents, the best known being bifunctional alkoxysilanes.

Thus, it has been proposed in patent application FR-A-2 094 859 to use a mercaptosilane coupling agent for the manufacture of tire treads. He was quickly demonstrated and it is now well known that mercaptosilanes, and in particular γ-mercaptopropyltrimethoxysilane or γ-mercaptopropyltriethoxysilane, are capable of providing excellent silica / elastomer coupling properties, but that the industrial use of these coupling agents is not possible due to the high reactivity of the -SH functions leading very quickly, during the preparation of the rubber composition in an internal mixer, to premature vulcanizations also called "scorching""), to very high Mooney plasticities, finally to rubber compositions which are almost impossible to work and to use industrially. To illustrate this impossibility of using industrially such coupling agents and the rubber compositions containing them, mention may be made of documents FR-A-2 206 330, US-A-4 002 594.

To overcome this drawback, it has been proposed to replace these mercaptosilane coupling agents with polysulphurized alkoxysilanes, in particular bis-alkoxyl (Cι-C) silylpropyl polysulphides as described in numerous patents or patent applications (see for example FR-A-2 206 330, US-A-3 842 111, US-A-3 873 489, US-A-3 978 103, US-A-3 997 581).

These polysulphurized alkoxysilanes are generally considered today as products providing, for vulcanized products loaded with silica, the best compromise in terms of safety in roasting, ease of implementation and reinforcing power. Among these polysulphides, mention should be made of bis 3-triethoxysilylpropyl tetrasulphide (abbreviated as TESPT) which is the coupling agent (inorganic filler / diene elastomer) known to be the most effective, and therefore the most used today, in rubber compositions for tires, in particular those intended to constitute treads for these tires; it is sold, for example, under the name "Si69" by the company Degussa. However, this product has the known disadvantage that it is very expensive and must be used most often in a relatively large amount (see for example patents US-A-5,652,310, US-A- 5,684,171, US-A- 5,684,172).

However, unexpectedly, the Applicant has discovered during its research that specific coupling agents can exhibit coupling performance superior to that of polysulphurized alkoxysilanes, in particular to that of TESPT, in rubber compositions for tires based on isoprene elastomer (natural rubber, synthetic polyisoprenes or isoprene copolymers). These specific coupling agents which, moreover, do not pose the aforementioned problems of premature roasting specific to mercaptosilanes, are particular polyfunctional polyorganosiloxanes, carrying an activated ethylenic double bond.

Consequently, a first subject of the invention relates to an elastomeric composition, crosslinkable with sulfur and usable for the manufacture of tires, comprising an isoprene elastomer, an inorganic filler as reinforcing filler, a coupling agent (inorganic filler / isoprene elastomer ), characterized in that this coupling agent is a multifunctional polyorganosiloxane (abbreviated as "POS") comprising, grafted onto its silicon atoms, on the one hand at least one hydroxyl or hydrolyzable function (radical or "Y" function), on the other hand at least one group carrying at least one activated ethylenic double bond (radical or "X" function).

Another subject of the invention is the use of a rubber composition in accordance with the invention for the manufacture of tires or for the manufacture of semi-finished products intended for such tires, these semi-finished products being chosen in particular in the group formed by the treads, the sub-layers intended for example to be placed under these treads, the crown plies, the sides, the carcass plies, the heels, the protectors, the air chambers or the gums waterproof interior for tubeless tires.

The subject of the invention is also these tires and these semi-finished products themselves, when they comprise a rubber composition in accordance with the invention.

The invention relates in particular to tire treads, these treads being able to be used during the manufacture of new tires or for retreading used tires; thanks to the compositions of the invention, these treads have both a low rolling resistance and a high resistance to wear.

The invention also relates to a process for the preparation of a composition in accordance with the invention, this process being characterized in that at least one isoprene elastomer is incorporated, at least one inorganic filler as reinforcing filler and a multifunctional POS as described above, and in that thermomechanically kneading the whole, in one or more stages, until reaching a maximum temperature between 110 ° C and 190 ° C.

The invention also relates to the use as coupling agent (inorganic filler / isoprene elastomer), in a rubber composition comprising an isoprene elastomer and reinforced with an inorganic filler, of such a POS carrying on the one hand, a hydroxyl or hydrolyzable function, on the other hand, an activated ethylenic double bond.

The invention finally relates to a process for coupling an inorganic filler and an isoprene elastomer, in an elastomeric composition vulcanizable with sulfur and usable for the manufacture of tires, this process being characterized in that one incorporates at least one isoprene elastomer , at least one inorganic filler as reinforcing filler and a multifunctional POS as described above, and in that thermomechanically kneading the whole, in one or more stages, until reaching a maximum temperature of between 110 ° C. and 190 ° C.

The invention as well as its advantages will be easily understood in the light of the description and of the exemplary embodiments which follow, as well as of the figures relating to these examples which represent curves of variation of modulus as a function of the elongation for different compositions of diene rubber, whether or not in accordance with the invention. I. MEASUREMENTS AND TESTS USED

The rubber compositions are characterized before and after curing, as indicated below.

1-1. Mooney plasticity

An oscillating consistometer is used as described in the French standard NF T 43-005 (1991). The Mooney plasticity measurement is made according to the following principle: the composition in the raw state (i.e., before baking) is molded in a cylindrical enclosure heated to 100 ° C. After one minute of preheating, the rotor turns within the test tube at 2 revolutions / minute and the torque useful for maintaining this movement is measured after 4 minutes of rotation. The Mooney plasticity (MS 1 + 4) is expressed in "Mooney unit" (MU, with 1 MU = 0.83 Newton.meter).

1-2. Toasting time

The measurements are carried out at 130 ° C, in accordance with French standard NF T 43-005 (1991). The evolution of the consistometric index as a function of time makes it possible to determine the toasting time of the rubber compositions, assessed in accordance with the aforementioned standard by parameter T5 (in the case of a large rotor), expressed in minutes, and defined as being the time necessary to obtain an increase in the consistometric index (expressed in MU) of 5 units above the minimum value measured for this index.

1-3. Tensile tests

These tests make it possible to determine the elasticity stresses and the breaking properties. Unless otherwise indicated, they are carried out in accordance with French standard NF T 46-002 of September 1988. The second secant modules (or apparent stresses, or apparent stresses, in MPa) are measured at 10% (ie after an accommodation cycle) at 10% elongation (noted M10), 100% elongation (Ml 00) and 300% elongation (M300). The stresses at break (in MPa) and the elongations at break (in%) are also measured. All these tensile measurements are carried out under normal temperature and hygrometry conditions according to French standard NF T 40-101 (December 1979).

A processing of the traction records also makes it possible to plot the module curve as a function of the elongation (see attached figures), the module used here being the true secant module measured in first elongation, calculated by reducing to the real section of the 'test tube and not in the initial section as previously for the nominal modules.

1-4. Dynamic properties

The dynamic properties ΔG * and tan (δ) _ma χ are measured on a viscoanalyzer (Metravib VA4000), according to standard ASTM D 5992-96. The response of a sample of vulcanized composition is recorded (cylindrical specimen 4 mm thick and 400 mm ² of section), subjected to a sinusoidal alternating single shear stress, at the frequency of 10 Hz, under normal temperature conditions (23 ° C) according to standard ASTM D 1349-99. A sweep is carried out in amplitude of deformation of 0, 1 to 50%) (outward cycle), then from 50% o to 1% (return cycle). The exploited results are the complex dynamic shear modulus (G *) and the loss factor tan δ. For the return cycle, the maximum value of tan δ observed (tan (δ) _max ) is indicated, as well as the difference in complex modulus (ΔG *) between the values at 0.15 and 50% of deformation (Payne effect).

IT CONDITIONS FOR CARRYING OUT THE INVENTION

The rubber compositions according to the invention are based on at least each of the following constituents: (i) one (at least one) isoprene elastomer (component A defined below), (ii) one (at least one) filler inorganic as reinforcing filler (component B defined below), and (iii) a specific (at least one) POS (component C defined below) as coupling agent (inorganic filler / isoprene elastomer).

Of course, by the expression composition "based on" is meant a composition comprising the mixture and / or the in situ reaction product of the various constituents used, some of these base constituents being capable of, or intended to react between them, at least in part, during the various stages of manufacturing the composition, in particular during its vulcanization.

II- 1. Isoprene elastomer (component A)

By “diene” elastomer (or rubber) is understood in known manner an elastomer derived at least in part (ie, a homopolymer or a copolymer) from diene monomers, that is to say from monomers carrying two carbon double bonds- carbon, conjugated or not. By "essentially unsaturated" diene elastomer is meant here a diene elastomer derived at least in part from conjugated diene monomers, having a proportion of units or units of diene origin (conjugated dienes) which is greater than 15% (% by moles) . In the category of “essentially unsaturated” diene elastomers, the expression “highly unsaturated” diene elastomer is understood in particular to mean a diene elastomer having a rate of units of diene origin (conjugated dienes) which is greater than 50%.

These general definitions being given, in the present application is meant by "isoprene elastomer", in known manner, a homopolymer or a copolymer of isoprene, in other words a diene elastomer chosen from the group consisting of natural rubber (NR ), synthetic polyisoprenes (IR), the various isoprene copolymers and mixtures of these elastomers. Among the isoprene copolymers, mention will be made in particular of isobutene-isoprene (butyl rubber - IIR), isoprene-styrene (SIR), isoprene-butadiene (BIR) or isoprene-butadiene-styrene copolymers (SBIR).

This isoprene elastomer is preferably natural rubber or a synthetic polyisoprene of the cis-1,4 type. Among these synthetic polyisoprenes, are preferably used polyisoprenes having a rate (molar%) of cis-1,4 bonds greater than 90%, more preferably still greater than 98%.

When blended with the above isoprene elastomer, the compositions of the invention may contain diene elastomers other than isoprene, in a minority (ie, for less than 50% by weight) or in the majority (ie, for more than 50% by weight), depending on the intended applications. They could also include non-diene elastomers, or even polymers other than elastomers, for example thermoplastic polymers.

By way of such diene elastomers other than isoprene, mention will be made in particular of any highly unsaturated diene elastomer chosen in particular from the group consisting of polybutadienes (BR), butadiene copolymers, in particular styrene-butadiene copolymers (SBR), and mixtures of these different elastomers.

If such diene elastomers other than isoprene are used, the person skilled in the art of the tire will readily understand that coupling agents other than the multifunctional POS described here (POS with activated double bond), in particular polysulphurized alkoxysilanes, may then be advantageously used to couple these complementary diene elastomers.

The improvement in coupling provided by the invention is particularly notable on rubber compositions whose elastomer base is mainly (ie, more than 50%> by weight) made of polyisoprene, ie, natural rubber or synthetic polyisoprene .

The composition according to the invention is particularly intended for a tread for a tire, whether it is a new or used tire (retreading), in particular for a tire intended for industrial or commercial vehicles such as "Weight - heavy "- ie, metro, bus, road transport equipment (trucks, tractors, trailers), off-road vehicles.

In such a case, the best known embodiment of the invention consists in using as isoprene elastomer only polyisoprene, more preferably natural rubber. It is for such conditions that the best performance in terms of rolling resistance and wear resistance has been observed.

However, a person skilled in the art of tires will understand that various cuts between isoprene elastomers, in particular natural rubber, and other diene elastomers, in particular SBR and / or BR, are also possible in rubber compositions in accordance with the invention which can be used by example for various parts of the tire other than its tread, for example for sidewalls or protectors of tires for passenger vehicles, vans or HGVs, whether these cuts are minority or majority in isoprene elastomer. II-2. Reinforcing filler (component B)

The white or inorganic filler used as reinforcing filler can constitute all or only part of the total reinforcing filler, in the latter case associated for example with carbon black.

Preferably, in the rubber compositions according to the invention, the reinforcing inorganic filler constitutes the majority, i.e. more than 50% by weight of the total reinforcing filler, more preferably more than 80%> by weight of this total reinforcing filler.

In the present application, the term "reinforcing inorganic filler" is understood, in a known manner, an inorganic or mineral filler, whatever its color and its origin (natural or synthetic), also called "white" filler or sometimes "clear" filler "in contrast to carbon black, this inorganic filler being capable of reinforcing on its own, without other means than an intermediate coupling agent, a rubber composition intended for the manufacture of tires, in other words capable of replacing, in its reinforcing function, a conventional charge of pneumatic grade carbon black.

The reinforcing inorganic filler is in particular an inorganic filler of the silica (SiO ₂ ) or alumina (Al ₂ O ₃ ) type, or a mixture of these two fillers.

The silica used can be any reinforcing silica known to those skilled in the art, in particular any precipitated or pyrogenic silica having a BET surface as well as a CTAB specific surface, both less than 450 m ² / g, preferably from 30 to 400 m ² / g. Highly dispersible precipitated silicas (called "HD") are preferred, in particular when the invention is implemented for the manufacture of tires having a low rolling resistance; the term “highly dispersible silica” is understood to mean, in known manner, any silica having a significant ability to disaggregate and to disperse in an elastomeric matrix, observable in known manner by electron or optical microscopy, on fine sections.

As non-limiting examples of such preferred highly dispersible silicas, mention may be made of Perkasil KS 430 silica from Akzo, BV3380 silica from Degussa, Zeosil 1165 MP and 1115 MP silica from Rhodia, Hi-Silica 2000 from the company PPG, the silicas Zeopol 8741 or 8745 from the company Huber, treated precipitated silicas such as for example the silicas "doped" with aluminum described in application EP 735 088.

The reinforcing alumina preferably used is a highly dispersible alumina having a BET surface area ranging from 30 to 400 m ² / g, more preferably between 60 and 250 m ² / g, an average particle size at most equal to 500 nm, more preferably at most equal to 200 nm, as described in the above-mentioned application EP 810 258. As nonlimiting examples of such reinforcing aluminas, mention may be made in particular of "Baikalox""A125","CR125","D65CR" aluminas from the company Baikowski. The physical state under which the reinforcing inorganic filler is present is immaterial, whether in the form of powder, microbeads, granules, or even beads.

Of course, the term reinforcing inorganic filler is also understood to mean mixtures of different reinforcing inorganic fillers, in particular of highly dispersible silicas and / or aluminas as described above.

When the rubber compositions of the invention are used as tire treads, the reinforcing inorganic filler used, in particular if it is silica, preferably has a BET surface area of between 60 and 250 m ² / g , more preferably between 80 and 200 m ² / g.

The reinforcing inorganic filler can also be used in cutting (mixing) with carbon black. As carbon blacks, all carbon blacks are suitable, in particular blacks of the HAF, ISAF, SAF type, conventionally used in tires and particularly in tire treads. By way of nonlimiting examples of such blacks, mention may be made of blacks NI 15, N134, N234, N339, N347, N375.

The quantity of carbon black present in the total reinforcing filler can vary within wide limits, this quantity of carbon black being preferably less than the quantity of inorganic reinforcing filler present in the rubber composition.

In the compositions in accordance with the invention, in combination with the reinforcing inorganic filler, it is preferable to use a carbon black in small proportion, at a preferential rate of between 2 and 20 phr, more preferably within a range of 5 to 15 phr. (parts by weight per hundred parts of elastomer). In the indicated intervals, the coloring properties (black pigmentation agent) and anti-UV properties of the carbon blacks are benefited, without, however, penalizing the typical performance provided by the reinforcing inorganic charge, namely low hysteresis (reduced rolling resistance) and high grip on both wet and snowy or icy surfaces.

Preferably, the rate of total reinforcing filler (reinforcing inorganic filler plus carbon black if applicable) is between 10 and 200 phr, more preferably between 20 and 150 phr, the optimum being different according to the targeted applications; in fact, the level of reinforcement expected on a bicycle tire, for example, is in known manner significantly lower than that required on a tire capable of traveling at high speed in a sustained manner, for example a motorcycle tire, a tire for a passenger vehicle or for a utility vehicle such as Truck.

For tire treads capable of running at high speed, the quantity of reinforcing inorganic filler, in particular if it is silica, is preferably between 30 and 120 phr, more preferably between 40 and 100 phr .

It will be understood that when the only diene elastomer present in the composition according to the invention is an isoprene elastomer, the abbreviation "pce" can then be replaced by "pci" (parts by weight per hundred parts of isoprene elastomer). In the present description, the BET specific surface is determined in a known manner, according to the Brunauer-Emmett-Teller method described in "The Journal of the American Chemical Society" Vol. 60, page 309, February 1938 and corresponding to the French standard NF T 45-007 (November 1987); the CTAB specific surface is the external surface determined according to the same standard NF T 45-007.

Finally, a person skilled in the art will understand that, as an equivalent charge of the reinforcing inorganic filler described in this paragraph, a reinforcing filler of the organic type could be used, in particular a carbon black for tires, covered at least in part with 'An inorganic layer requiring the use of a coupling agent to ensure the bond with the elastomer.

II-3. Coupling agent (component C)

In known manner, as already explained above, a coupling agent (inorganic filler / diene elastomer) is a compound carrying at least two functions, denoted here "Y" and "X", allowing it to be able to be grafted, on the one hand on the reinforcing inorganic filler by means of the function Y, on the other hand on the diene elastomer by means of the function X.

The coupling agent (component C) used in the rubber compositions in accordance with the invention is an at least bifunctional POS comprising, per molecule, grafted onto its silicon atoms, on the one hand at least one hydroxyl or hydrolyzable function (ci -a radical or "Y" function) allowing it to be grafted onto the reinforcing inorganic charge, on the other hand, and this is the essential characteristic of this POS for the intended application, at least one group carrying at least at least one activated ethylenic double bond (hereinafter radical or "X" function) allowing it to be grafted onto the isoprene elastomer.

These functions or radicals X and Y are described in detail below before developing the possible preferential structures for component C.

The radical X is the group carrying the activated carbon-carbon double bond intended to be grafted onto the isoprene elastomer during the vulcanization step, by forming a covalent bond with the latter.

It will be recalled that, in known manner, an "activated" bond is a bond made more capable of reacting (in this case, here, with the isoprene elastomer).

The ethylenic double bond (> C = C <) of the radical X is preferably activated by the presence of an adjacent electron-attracting group, that is to say attached to one of the two carbon atoms of the ethylenic double bond . It is recalled that, by definition, an "electron-attracting" group is a radical or functional group capable of attracting electrons to itself more than a hydrogen atom would if it occupied the same place in the molecule considered. This electro-attracting or "activating" group is preferably chosen from the radicals carrying at least one of the bonds C = O, C = C, C≡C, OH, OR (R alkyl) or OAr (Ar aryl), or at least one sulfur and / or nitrogen atom, or at least one halogen.

Mention will more preferably be made of an activating group chosen from acyl radicals (-COR), carbonyls (> C = O), carboxyl (-COOH), carboxy-esters (-COOR), carbamylins (-CO-NH2; -CO-NH -R; -CO-NR ₂ ), alkoxy (-OR), aryloxy (-OAr), hydroxy (-OH), alkenyls (-CH = CHR), alkynyls (-C = CR), naphthyl (CιoH ₇ -) , phenyl (C ₆ H ₅ -), the radicals carrying at least one sulfur (S) and / or nitrogen (N) atom, or at least one halogen.

By way of particular examples of such an activating group, there may be mentioned in particular, in addition to those already mentioned, the acetyl, propionyl, benzoyl, toluyl, formyl, methoxycarbonyl, ethoxycarbonyl, methylcarbamyl, ethylcarbamyl, benzylcarbamyl, phenylcarbamyl, dimethylcarbamyl radicals , dibenzylcarbamyle, diphenylcarbamyle, methoxy, ethoxy, phenoxy, benzyloxy, vinyl, isopropenyl, isobutenyl, ethynyl, xylyl, tolyl, methylthio, ethylthio, benzylthio, phenylthio, thiocarbonyl, thiuram, thiuramid, amino , cyanato, isocyanato, isothiocyanato, hydroxyamino, acetamido, benzamido, nitroso, nitro, azo, hydrazo, hydrazino, azido, ureido, radicals carrying at least one chlorine or bromine atom.

Even more preferably, the electro-attractor group is chosen from carbonyls, carboxyls, carboxyesters, radicals carrying sulfur and / or nitrogen with a carbonyl root. A POS is particularly used, the ethylenic double bond of which is activated by an adjacent radical carrying at least one bond (C = O).

The function Y is a hydroxyl function or a hydrolysable function attached to a silicon atom of the POS, in particular an alkoxyl function (OR ¹ ) in which R ¹ is a monovalent hydrocarbon group, linear or branched, preferably comprising from 1 to 15 atoms of carbon.

In other words, functions Y particularly chosen from the so-called "hydroxysilyl" (≡Si-OH) or "alkoxysilyl" (≡Si-OR ¹ ) functions are particularly suitable; the radical R ¹ having 1 to 15 carbon atoms is more preferably selected from alkyl, alkoxyalkyl, cycloalkyl and aryl groups, especially among alkyls Cι-C _6, the alkoxyalkyl C ₂ -C _6, cycloalkyl C ₅ -C ₈ and phenyl.

Multifunctional POSs which can be used in the compositions of the invention are in particular POSs consisting of siloxyl units, identical or different, of formula (I) which follows:

(I) R ² _has Yb c Si O _{(4. A. B. C)} / 2

in which :

- a, b and c are each integers or fractional from 0 to 3; the radicals R ² , identical or different if there are more than one, represent a monovalent hydrocarbon radical; - The radicals Y, identical or different if there are more than one, represent a hydroxyl or hydrolyzable group as defined above, capable of binding to the reinforcing inorganic filler;

the radicals X, identical or different if there are more than one, represent the group carrying the activated ethylenic double bond as defined above, capable of binding to the isoprene elastomer,

with the reservation that:

- 0 <(a + b + c) <3;

- at least one radical X and at least one radical Y are present in the polysiloxane molecule.

The simplified notation used in formula (I) above is well known to those skilled in the art in the field of polyorganosiloxanes; it includes the various specific formulas possible for the siloxyl units, whatever their functionalization rate, their position on the polysiloxane chain (along the chain or at the end (s) of the chain) or the nature of the POS (for example linear, trendy or cyclic).

This POS of formula (I) is therefore a copolymer, statistical, block or block, branched, linear or cyclic, comprising at least the two functions Y and X above defined on the polysiloxane chain, whether along the chain or chain end (s).

In formula (I) above, it will be understood that the radicals R ² may be identical or different within the same siloxyl unit (when several of them are present on this same unit), or identical or different from one siloxyl motif to another. The same is true for the radicals Y and X.

The radicals R ² are preferably chosen from alkyl, linear or branched, Cj-Cg and cycloalkyls C5-Cg, in particular from methyl, ethyl, n-propyl, isopropyl, n-butyl, n-pentyl, cyclohexyl and / or among aryls, in particular phenyl. More preferably, the radicals R ² are methyl radicals.

The radicals Y are preferably selected from the group consisting of hydroxyl (OH) and C _j-C₆ alkoxyl, especially methoxy, ethoxy, propoxy or isopropoxy, or a mixture of these hydroxyl or alkoxyl. More preferably, the radicals Y are chosen from hydroxyl, methoxyl, ethoxyl and mixtures of these radicals.

As preferred examples of radicals X, mention will be made of those of formulas (X / a), (X / b) or (X / c) below:

(X / b)

(X / c)

in which:

- Bj is O, NH, N-alkyl, N-aryl in particular N-phenyl, S, CH ₂ , CH-alkyl or CH-aryl in particular CH-phenyl;

- B ₂ is N, CH, C-alkyl or C-aryl, in particular C-phenyl;

- the radicals R ', R "and R'", identical or different from each other, represent hydrogen, a Cι-C ₆ alkyl, substituted or unsubstituted, a cyano radical, a halogen or a C ₆ aryl - C _JO , substituted or unsubstituted, in particular a phenyl, R "and / or R '" (ie, any one of these radicals or both) which may additionally represent a monovalent COOH group or a derivative group of ester type or amide;

- the divalent group A is intended to ensure the bond with the polysiloxane chain.

It is noted that the "ball joints" Bj and B ₂ have the role of ensuring the connection between the group A and the activated double bond. What all three structures have in common is the presence of an ethylenic double bond (> C = C <) activated by at least one adjacent carbonyl group (> C = O). The group A, substituted or unsubstituted, is preferably a hydrocarbon radical, saturated or unsaturated, comprising from 1 to 18 carbon atoms, said group A possibly being interrupted by at least one heteroatom (such as for example O or N) or at least one divalent group comprising at least one heteroatom (such as for example O or N); are especially suitable alkylene groups Cι-Cι ₈ or arylene groups C ₆ -C _{] 2} , more particularly alkylene Ci -Ci ₀ , especially C ₂ -C, in particular propylene. As preferred examples of such structures, particular mention will be made of those of formulas (II) which follow:

formulas in which:

- the symbol V represents a divalent radical -O- or -NR ⁶ -;

- the symbol W represents a monovalent group COOR ⁷ or a monovalent group CONR ⁸ R ⁹ ;

- R ³ is a divalent alkylene radical, linear or branched, comprising from 1 to 15 carbon atoms whose free valence is carried by a carbon atom and is linked to a silicon atom, said radical R ³ being able to be interrupted within of the alkylene chain by at at least one heteroatom (such as O or N) or at least one divalent group comprising at least one heteroatom (such as O or N);

- the symbols R ⁴ and R ⁵ , identical or different, each represent a hydrogen atom, a halogen atom, a cyano radical or an alkyl radical, linear or branched, having from 1 to 6 carbon atoms, R ⁵ can also represent a monovalent group COOR ⁷ ;

- the symbols R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ , identical or different, each represent a hydrogen atom, an alkyl radical, linear or branched, having from 1 to 6 carbon atoms or a phenyl radical , the symbols R and R being able, in addition, to form together and with the nitrogen atom, to which they are linked, a single saturated ring having from 3 to 8 carbon atoms in the ring.

When R is interrupted at the sem of the alkylene chain by at least one heteroatom, the heteroatom is present in the form of a divalent residue preferably chosen from -O-, -CO-, -CO-O-, -COO-cyclohexylene (optionally substituted by an OH radical) -, -O-alkylene (linear or branched at C2-C ₆ , optionally substituted by an OH or COOH radical) -, -O- CO-alkylene (linear or branched at C ₂ -C ₆ , optionally substituted by an OH or COOH radical) -, -CO-NH, -O-CO-NH-, and -NH-alkylene (linear or branched C ₂ -C ₆ ) -CO-NH-; R ^{3 also} represents an aromatic radical chosen from -phenylene (ortho, meta or para) - alkylene (linear or branched in C ₂ -C ₆ ) -, -phenylene (ortho, meta or para) -O-alkylene (linear or branched in C ₂ -C ₆ ) - -alkylene (linear or branched in C ₂ -C ₆ ) -phenylene (ortho, meta or para) -alkylene (linear or branched in Cι-C ₆ ) -, and -alkylene (linear or branched in C ₂ -C ₆ ) -phenylene (ortho, meta or para) -O-alkylene (linear or branched in C] -C ₆ ) -.

R ⁴ and R ⁵ are preferably chosen from hydrogen, chlorine, methyl, ethyl, n-propyl, n-butyl, R ⁵ possibly also representing a COOR ⁷ group where the radical R ⁷ is chosen from hydrogen, methyl, ethyl, n-propyl, n-butyl.

R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are preferably chosen from hydrogen and methyl, ethyl, n-propyl, n-butyl radicals, the symbols R ⁸ and R ^{9 being} able, in addition, to form together and with the nitrogen atom a pyrrolidinyl or piperidyl ring.

A point common to the five structures above is the presence of an ethylenic double bond (> C = C <) activated by at least one adjacent carbonyl group (> C = O).

In these formulas (III to II / 5), the following characteristics are more preferably verified:

- R ³ represents an alkylene radical chosen from - (CH ₂ ) 2-; - (CH ₂ ) ₃ -; - (CH ₂ ) ₄ -; -CH ₂ -CH (CH ₃ ) -; - (CH ₂ ) ₂ -CH (CH ₃ ) -CH ₂ -; - (CH ₂ ) ₃ -O- (CH ₂ ) ₃ -; - (CH ₂ ) ₃ -O-CH ₂ -CH (CH ₃ ) - CH ₂ -; - (CH ₂ ) ₃ -O-CH ₂ CH (OH) -CH ₂ -; more particularly R ³ is chosen from - (CH ₂ ) ₂ - or - (CH ₂ ) ₃ -;

- R ⁴ and R ⁵ are chosen from a hydrogen atom, chlorine or the methyl, ethyl, n-propyl, n-butyl radicals, more particularly hydrogen or methyl, R ⁵ can also represent a COOR group ⁷ where R ⁷ represents hydrogen or methyl; - R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are chosen from hydrogen and methyl, R ⁸ and R ^{9 being} able, in addition, to form together and with the atom N a piperidyl ring. Even more preferably, the POSs of the compositions of the invention verify at least one of the following characteristics:

- c is equal to 0 or 1;

- the rate of R ⁿ SiO _{3/2 units} (units noted "T" in silicone chemistry) - where R ¹¹ is chosen from the radicals corresponding to the definitions of R ² , Y and X - this rate being expressed by the number , per molecule, of these units per 100 silicon atoms, is less than or equal to 30%, preferably less than or equal to 20%; - the rate of Y functions, expressed by the number, per molecule, of Y functions per 100 silicon atoms, is at least 0.8%>, and preferably lies in the range from 1 to 100 %;

the rate of X functions, expressed by the number, per molecule, of X functions per 100 silicon atoms, is at least 0.4%, and preferably lies in the range from 0.8 to 100%.

Given the values that the symbols a, b and c can take and the above details relating to the radical R ¹¹ , it will be understood that the multifunctional POSs of formula (I) may in particular have either a linear structure or a cyclic structure, or a mixture of these structures, these structures possibly also having a certain molar amount of ramifications ("T" units).

Given the meanings given above with respect to the radicals X, it should also be understood that a multifunctional POS conforming to formula (I) can be carrier in particular:

- in addition to function (s) maleimide (III), isomeimide (II / 4) and acrylamide (II / 5);

- of maléamic acid and / or fumaramic acid function (s), when, in formulas (II / 2) and / or (II / 3), the symbol N = -ΝR ⁶ - and the symbol W = COOR ⁷ where R ⁷ = H; - of maleic ester and / or fumaric ester function (s), when, in formulas (II / 2) and / or (II / 3), the symbol N = -O- and the symbol W = COOR ⁷ where R ⁷ is different from H;

- of maleramic ester and / or fumaramic ester function (s), when, in formulas (II / 2) and / or (II / 3), either the symbol N = ΝR ⁶ - and the symbol W = COOR ⁷ where R ⁷ is different from H, ie the symbol V = -O- and the symbol W = COΝR ⁸ R ⁹ ; - of function (s) friend of maleic and / or fumaric amide, when, in formulas (II / 2) and / or (II / 3), the symbol V = -NR ⁶ - and the symbol W = CONR ⁸ R ⁹ .

As preferred examples of POS of formula (II) corresponding to the above definitions, there will be mentioned in particular essentially linear POS and corresponding to the following average formula (III):

(III) in which

- the symbols R, R, X and Y are as defined above;

- the symbols R ^1! are chosen from R ² , X and Y; - the symbols T ¹ are chosen from the patterns HO _1/2 and R ^! Oι ₂ ;

the symbols T, which are identical or different from the symbols T, are chosen from the units HO1 / 2, R ^l O and the unit (R ² ) ₃ SiOι ₂ ;

- the symbols m, n, p, q, r, s and t each represent whole or fractional numbers which meet the following cumulative conditions:. m and t are different from zero and their sum is equal to 2 + s;

. n, p, q and r are in the range of 0 to 100;

. s is in the range from 0 to 75;

. when n = 0, p is different from zero and when p = 0, n is different from zero;

. the sum (n + p + q + r + s + t) - giving the total number of silicon atoms - lies in the range from 2 to 250;

. the ratio 100 s / (n + p + q + r + s + t) - giving the rate of "T" units - is at most equal to 30, preferably at most equal to 20;

. the ratio 100 (m + p + r + s [when R ¹¹ = Y] + t) / (n + p + q + r + s + t) - giving the rate of functions Y (provided by the patterns represented by the symbols T, T and Y) - is equal to or greater than 1, preferably in a range from 4 to 100;

. the ratio 100 (n + p + s [when R ¹¹ ≈ X]) / (n + p + q + r + s + t) - giving the rate of functions X - is equal to or greater than 1, preferably included in a domain from 2 to 100.

As components C which are more preferably used, mention will be made of those comprising oligomers and polymers noted POS / 1 which are essentially linear and which correspond to formula (III) above and in which (we will then speak, abbreviated, in this case, of POS / 1 polymers of imide type):

- the X functions, identical or different, are chosen from the radicals of formulas

(IIIll), (II / 2), (II / 3) and their mixtures, with the conditions according to which:

. at least one of the functions X corresponds to the formula (11/1);

. R ⁵ is different from a COOR ⁷ group;

. in formulas (II / 2) and (II / 3), the symbol V = -NR ⁶ - where R ⁶ = H, R ⁵ is different from a group COOR ⁷ and the symbol W = COOR ⁷ where R ⁷ = H;

. at least one of the functions X corresponds to the formula (11/1);

. when, where appropriate, there is a mixture of function (s) X of formula (11/1) with functions X of formulas (II / 2) and / or (II / 3), the molar fraction of functions X of formulas (II / 2) and / or (II / 3) in the set of functions X is on average equal to or less than 12%> by mole and, preferably equal to or less than 5%> by mole; the symbols m, n, p, q, r, s and t meet the following cumulative conditions: m + t = 2 + s; n is in the range from 0 to 50; p is in the range from 0 to 20; when n = 0, p is at least equal to 1 and when p = 0, n is at least equal to 1; q is in the range from 0 to 48; r is in the range from 0 to 10; • s is in the range from 0 to 1; the sum (n + p + q + r + s + t) - giving the total number of silicon atoms - lies in the range from 2 to 50; the ratio 100 s / (n + p + q + r + s + t) - giving the rate of patterns "T" - is less than or equal to 10; . the ratio 100 (m + p + r + s [when R ⁿ = Y] + t) / (n + p + q + r + s + t) - giving the rate of functions Y (provided by the patterns represented by the symbols T, T and Y) - is in a range from 4 to 100, preferably from 10 to 100; The ratio 100 (n + p + s [when R ⁿ = X]) / (n + p + q + r + s + t) - giving the rate of functions X - is included in a domain from 10 to 100, preferably from 20 to 100.

As other components C more preferably used, mention will also be made of those comprising oligomers and polymers marked POS / 2 which are essentially linear and which correspond to formula (III) and in which (we will then speak, abbreviated, in this case, of POS polymers / 2 of acid or ester type):

the symbols T ² , identical or different from the symbols T ¹ , are chosen from the pattern HO1 2 and the pattern R'OIΛ;

- the functions X, identical or different, are chosen from the radicals of formulas (II / 2), (II / 3) and their mixtures, where on the one hand the symbol V = -NR ⁶ -, R ⁵ is different d 'a COOR ⁷ group and either R ⁷ is H (POS / 2 of acid type) or R ⁷ is different from H (POS / 2 of ester type);

- the symbols m, n, p, q, r, s and t meet the cumulative conditions set out above for POS / 1 of the imide type.

Also included in the scope of the invention are cyclic POSs having the following average formula (III ′):

(III ') in which: - the symbols n ', p', q 'and r' each represent whole or fractional numbers which meet the following cumulative conditions:

• n ', p' and q 'are in the range from 0 to 9; . when n '= 0, p' is at least equal to 1; • when p - 0, n 'and r' are each at least equal to 1;

• r 'is in the range from 0 to 2;

• the sum (n '+ p' + q '+ r ¹ ) is in the range from 3 to 10;

. the ratio 100 (p '+ r ¹ ) / (n' + p '+ q' + r ¹ ) - giving the rate of functions Y - is included in a domain from 4 to 100; "The ratio 100 (n '+ p ¹ ) / (n' + p '+ q' + r ') - giving the rate of functions X - is included in a domain from 10 to 100,

these cyclic multifunctional POSs can be used in admixture with the essentially linear POSs of formula (III) above.

The multifunctionalized POSs carrying the X functions of formula (II), those of formula (III) or (III ¹ ) above can be prepared according to a synthetic route involving in particular:

- A hydrolysis and condensation reaction of a dihalosilane or a dialkoxysilane carrying an X function, optionally in the presence of a dihalosilane or a dialkoxysilane;

- A condensation reaction between an organosilane carrying a function X and at least two functions Y, and a linear POS α, ω-dihydroxylated;

a redistribution and equilibration reaction between an organosilane carrying an X function and at least two Y and / or halo functions, and an organocyclosiloxane which may optionally carry one or more Y functions in the chain;

- A coupling reaction between an organosilane carrying an X function and at least two Y functions, and a polysilazane;

- a coupling reaction between a precursor POS, linear or cyclic, carrying at least one Y function and functional with at least one motif attached to a silicon atom in particular of the -alkylene type (linear or branched C ₂ -C ₆ ) -OH, -alkylene (linear or branched C ₂ -C ₆ ) -NR ⁶ H or -alkylene (linear or branched C ₂ -C ₆ ) -COOH, and a reactive compound capable of reacting with (or ) above-mentioned motif (s) to give rise to the desired function X; an esterification reaction of a POS, linear or cyclic, carrying at least one Y function and at least one X function of formula (II / 2) or (II / 3) where the symbol W represents a COOH group.

More precisely, these POSs can be prepared by a process which consists for example:

• (a) hydrolyzing in an aqueous medium an organosilane of formula:

R ²

CI— Si-Ci (IV) IX where the symbols R ² and X have the definitions given above, possibly operating in the presence of an organosilane of formula:

Such a process is well suited for preparing multifunctional POSs of formula (III) where the symbols T and T both represent the pattern HOι _{/ 2} and where on the one hand p = r = s = 0 and on the other hand q is either equal to zero [when the silane (IV) is hydrolyzed in the absence of the silane (V)], or a number different from zero [when the silane (IV) is hydrolyzed in the presence of the silane (V) )]. With regard to the practical way of implementing this process, reference will be made to the content of FR-A-2,514,013 for more details;

(B) to condense, optionally in the presence of a catalyst based for example on a tin carboxylate, an organosilane of formula:

(R ¹ O) _d - Si- (R ² ) 3-d (VI)

X

in which the symbols R ¹ , R ² and X are as defined above and d is a number chosen from 2 or 3, with a POS of formula:

in which the symbol R ² is as defined above and e is an integer or fractional number ranging from 2 to 50. Such a method is well suited for preparing multifunctional POSs of formula (III) where the symbols T ¹ and T ² represent a mixture of HO _1/2 patterns with R patterns ^! Oι 2 and where the symbols p, r and s can be different from zero when d = 3, while, whatever the value of d, q is different from zero. With regard to the practical manner of implementing this method, one can refer for more details to the contents of US-A-3,755,351;

(C) to carry out a redistribution and equilibration reaction, in the presence of an appropriate catalyst and of water, between on the one hand an organosilane of formula:

(Z) _f - Si ^~ (R ² ) _3.f (VIII) X in which the symbol R ² and X are as defined above, the symbol Z is chosen from hydroxyl radicals, R ^ and halo (such as for example chlorine) and f is an integer chosen from 2 or 3, and d on the other hand an organocyclosiloxane of formula:

in which the symbols R are as defined above and g is an integer ranging from 3 to 8, and optionally a dihydroxy POS of formula (VII). Such a process is well suited for preparing POSs of formula (III) where the symbols T and T represent the units HO _1/2 and the symbol q is different from zero.

The coupling agents or components C which are preferably used in the context of the invention are POS / 1 of the imide type.

A first advantageous procedure for preparing such POSs in formula (III) in which the symbol q is equal to zero consists in carrying out the following steps (dl) and (d2):

(dl) we react:

- an organosilane of formula (VI) where the symbol X represents the function of formula (II / 2) where V = -NR ⁶ with R ⁶ = H, R ⁵ is different from a group COOR ⁷ and W = COOR ⁷ with R ⁷ =

H, that is to say an organosilane of formula:

with a disilazane of formula

(R ² ) ₃ Si— NH Si (R ² ) ₃ (XI)

formula in which the symbols R ¹ , R ² , R ³ , R ⁴ and R ⁵ are as defined above and d is an integer chosen from 2 or 3,

this reaction being carried out in the presence of a catalyst, supported or not supported on an inorganic material (such as for example a siliceous material), based on at least one Lewis acid, operating at atmospheric pressure and at a temperature in the range from room temperature (23 ° C) to 150 ° C, and preferably from 60 ° C to 120 ° C;

• (d2) the reaction medium obtained is stabilized by treatment of the latter with at least one halosilane of formula (R ² ) ₃ Si-halogeno where the halo residue is preferably chosen from a chlorine or bromine atom, in operating in the presence of at least one non-nucleophilic and non-reactive organic base with respect to the imide function formed in situ during step (dl).

The disilazane is used in an amount at least equal to 0.5 mole per 1 mole of starting organosilane and preferably ranging from 1 to 5 moles per 1 mole of organosilane.

The preferred Lewis acid is ZnCl ₂ and / or ZnBr ₂ and / or ZnI ₂ . It is used in an amount at least equal to 0.5 mole per 1 mole of organosilane and, preferably, ranging from 1 to 2 moles per 1 mole of organosilane.

The reaction is carried out in a heterogeneous medium, preferably in the presence of a solvent or of a mixture of solvents common to the organosilicon reagents. The preferred solvents are of the aprotic polar type such as for example chlorobenzene, toluene, xylene, hexane, octane, decane. The most preferred solvents are toluene and xylene.

This method (d) can be implemented by following any operating method known per se. A procedure which is very suitable is as follows: firstly, the reactor is supplied with Lewis acid, then a solution of the organosilane is gradually poured into all or part of the solvent (s); in a second step, the reaction mixture is brought to the chosen temperature, then the disilazane is poured which can optionally be used in the form of a solution in part of the solvent (s); then in a third step, the reaction mixture obtained is treated with at least one halosilane in the presence of one or more organic base (s) with a view to its stabilization; and finally in a fourth step, the stabilized reaction medium is filtered to remove the Lewis acid and the salt formed in situ during stabilization, then it is subjected to devolatilization under reduced pressure to remove the solvent (s) ( s).

Regarding the stabilization step (d2), the halosilane (s) is (are) used in an amount at least equal to 0.5 mole per 1 mole of starting organosilane and, from preferably ranging from 0.5 to 1.5 moles per 1 mole of organosilane. As regards the organic bases, those which are preferred are in particular tertiary aliphatic amines (such as for example N-methylmorpholine, triethylamine, triisopropylamine) and hindered cyclic amines (such as for example 2,2,6-tetraalkyl , 6 piperidines). The organic base (s) is (are) used in an amount at least equal to 0.5 mole per 1 mole of starting organosilane and preferably ranging from 0.5 to 1 , 5 moles per 1 mole of organosilane.

A second operating mode - hereinafter process (e) - advantageous for preparing such POSs in formula (III) of which the symbol q is different from zero consists in carrying out the only step (dl) defined above, but in which the disilazane of formula (XI) has been replaced by a cyclic polysilazane of formula:

in which the symbols R are as defined above and h is an integer ranging from 3 to 8.

This second method can be implemented using the operating mode which is suitable, presented above with regard to the implementation of the method (d), and based on the realization of only the first time, second time and fourth time of which we talked about above. Note, however, that the polysilazane is used in an amount at least equal to 0.5 / h mole for 1 mole of starting organosilane and preferably ranging from 1 / h to 5 / h moles for 1 mole of organosilane ( h being the number of silazane units in the polysilazane of formula (XII)).

Carrying out methods (d) and (e), like that of methods (f), (g) and (h) which are presented later in this memo, leads to the production of a coupling agent or component. C which can be in the form of a multifunctional POS in the pure state or in the form of a mixture of a multifunctional POS with a variable amount by weight (generally much less than 50% in the mixture) of other (or others) compound (s) which can (can) consist for example in:

- (i) a small amount of the unreacted starting organosilane of formula (X); and or

- (ii) a small amount of the organosilane of formula:

formed by direct cyclization of the corresponding amount of the starting organosilane of formula (X); and or

(iii) a small amount of the cyclic monofunctional POS of formula:

in which :

- the symbols R ² are as defined above;

- the symbols X are as defined above for POS / 1 of the imide type;

- the symbols n "and q" are whole or fractional numbers satisfying the following cumulative conditions:

n "and q" are each in the range of 1 to 9; the sum n "+ q" is in the range from 3 to 10,

said cyclic monofunctional POS being derived from a modification of the silicone skeleton of the desired multifunctional POS.

Other POSs which can preferably be used in the context of the invention are POS / 2 of the acid type or of the ester type.

An advantageous procedure - hereinafter process (f) - which can be used to prepare POS / 2 of the acid type consists in carrying out a coupling reaction between:

- on the one hand, an essentially linear amino POS having the same formula (III) given above with regard to the definition of POS / 2, but in which the symbol X is now an amino function of formula -R ³ - NR ⁶ H (R ³ and R ⁶ defined above); said amino POS is represented for short, in the following, by the simplified formula:

Si-R ³ -NR ⁶ H (XV)

- and on the other hand maleic anhydride or one of its derivatives of formula:

in which the symbols R ⁴ and R ⁵ are as defined above for formula (II).

The amino POS of formula (XV) can be prepared, in a manner known per se, by carrying out for example a redistribution and equilibration reaction between on the one hand a POS which results from a hydrolysis of an alkoxysilane carrying a function amine formula:

in which the symbols R, R, d, R ³ and R ⁶ are as defined above with regard to formulas (VI) to (XV), and on the other hand an α, ω-dihydroxylated POS of formula (VII ).

As regards the practical manner of carrying out the coupling reaction between the amino POS (XV) and maleic anhydride (XVI), this is a reaction known in itself, usually carried out at a temperature ranging from room temperature (23 ° C) to 80 ° C by operating in the presence of a solvent or a mixture of solvents. Reference can be made to the content of document US-A-3,701,795 for more details.

Other preferred POSs, POS / 2 of the ester type, can be prepared by esterification of an intermediate maleamic acid POS by carrying out the following steps: (gl) coupling reaction, as explained above with regard to process (f) , between the amino POS (XV) and maleic anhydride (XNI), then (g2) reaction of esterification of the medium comprising POS / 2 of the acid type formed, to lead to the compound comprising POS / 2 of the desired ester type , by applying the following synthesis scheme:

R ⁴ c:: CR ^{^}

≡Si-R-NR— this ^' COOH

POS / 2 acid type

esterification

Ester type POS / 2

With regard to the practical way of implementing step (g2), reference will be made for more details to the contents of the following documents which describe, possibly starting from other reagents, procedures applicable to the conduct of this step: (i) reaction of the ammonium salt of the carboxylic acid with an agent such as the organic sulfate of formula (R ⁷ ) ₂ SO ₄ or the organic iodide of formula R ⁷ I: cf. especially

Can. J. Chem., 65, 1987, pages 2179-2181 and Tetrahedron Letters n ° 9, pages 689-692,

1973; (ii) reaction of the chloride of the carboxylic acid with the alcohol of formula R OH in the presence of an amino base: cf. in particular Heterocycles, 39, 2, 1994, pages 767-778 and J. Org.

Chem., 26, 1961, pages 697-700; (3i) transesterification reaction in the presence of an ester such as the formate of formula H-

COOR ⁷ : cf. including Justus Liebigs Ann. Chem., 640, 1961, pages 142-144 and J.

Chem. Soc, 1950, pages 3375-3377; (4i) methylation reaction with diazomethane which makes it possible to easily prepare the methyl ester: cf. including Justus Liebigs Ann. Chem., 488, 1931, pages 211-227; (5i) direct esterification reaction with alcohol R ⁷ -OH: cf. including Org. Syn. Coll., Vol

1, pages 237 and 451, 1941 and J. Org. Chem., 52, 1987, page 4689.

According to a second method (h), which corresponds to a preferred synthetic route, the POS / 2 of the ester type can be prepared by formation of an amide function by adding the amino POS (XN) to an ester derivative (XIX) obtained from a mono-ester of maleic acid (XVIII), by carrying out the following steps: (hl) alcoholysis of maleic anhydride (XVI) with alcohol R ⁷ -OH, (h2) activation of the carboxylic acid function of the maleic acid mono-ester (XVIII) obtained, using the various activation methods described in the field of peptide synthesis, to lead to the activated ester derivative (XIX), then (h3) addition of the Amino POS (XV) on said activated ester derivative (XIX) to lead to the compound comprising POS / 2 of the desired ester type, by applying the following synthetic scheme:

Amino POS (XV)

where the symbol Ac of the derivative (XIX) represents an activating function. With regard to the practical way of implementing steps (hl) to (h3), 01 will refer for more details to the contents of the following documents which, if necessary, describe from the start of other reagents, procedures applicable to the different conduct process steps considered:

- for step (hl): cf. in particular J. Med. Chem., 1983, 26, pages 174-181;

- for stages (h2) and (h3): cf. John JONES, Amino Acid and Peptide-Synthesis, p∑ 25-41, Oxford University Press, 1994.

In order to allow the addition of the amino function to the carboxylic acid function of the maleic acid ester (XVIII), it is first necessary to activate the carboxylic acid function and this activation can be done in particular. by using the following methods:

(j) activation by reaction with an alkyl chloroformate, according to the scheme:

T-COOH ^{CI "C0" QR} > T-CO-O-CO-OR, + HCI activating function Ac

where T represents the residue -R ⁴ C = CR ⁵ -COOR ⁷ and R represents a linear alkyl radical ay for example 1 to 3 carbon atoms;

(2d) activation by reaction with dicyclohexylcarbodiimide (DCCI) in the presence preferably of N-hydroxysuccinimide (HO-SN), according to the scheme:

activating function Ac

(3d) activation by reaction with a chlorinated compound such as for example thionyl chloride, phosphorus pentachloride, according to the scheme:

PC

T-COOH *. T-CO-CI + POC + HCI

ac

Activation methods (j) and (2j) are especially preferred. To return to the general processes (b) and (c) for preparing multifunctional POSs, they can advantageously be carried out starting, for example, from an organosilane of formula:

in which the symbols R ¹ , R ² , d, R ³ , R ⁶ , R ⁴ , R ⁵ and R ⁷ (different from H) are as defined above (formulas II and VI).

Such organosilanes are products which can be prepared by applying either of the methods (gl) and (g2) described above, in the course of which the amino POS (XV) will be replaced by the amino alkoxysilane. of formula (XVII).

Finally, it will be understood that, in general, the component C can be in the form of a multifunctional POS in the pure state or in the form of a mixture of such a POS with a variable quantity by weight (preferably less than 50% by weight of this mixture) of one or more other compounds which may consist, for example, of:

(i) one and / or the other of the starting reagents from which the multifunctional POSs are prepared, when the conversion rate of said reagents is not complete; and / or (ii) the product (s) resulting from a complete or incomplete modification of the silicone skeleton of the starting reagent (s); and or

(iii) the product (s) resulting from a modification of the silicone skeleton of the desired multifunctional POS, carried out by a condensation reaction, a hydrolysis and condensation reaction and / or a redistribution reaction .

The POSs described above comprising, grafted onto their silicon atoms, hydroxyl or hydrolyzable functions on the one hand and groups carrying an activated ethylenic double bond on the other hand, have been found to be sufficiently effective on their own for the coupling of 'An isoprene elastomer and a reinforcing inorganic filler such as silica. Without this being limiting, they can advantageously constitute the only coupling agent present in the rubber compositions of the invention when the diene elastomer consists exclusively of an isoprene elastomer, in particular natural rubber or synthetic cis-1,4 polyisoprene.

The content of component (C) is preferably greater than 0.5 pci, more preferably greater than 1 pci and less than 15 pci. Below the minima indicated the effect may be insufficient, while beyond the maximum rate indicated, there is generally no longer any improvement in the coupling, while the costs of the composition increase. For these reasons, this content of component C is more preferably between 2 and 10 pci.

A person skilled in the art will know how to adjust this content of component C as a function of the intended application, in particular of the part of the tire for which the rubber composition of the invention is intended, the nature of the isoprene elastomer and the amount of reinforcing inorganic filler used. Of course, in order to reduce the costs of the rubber compositions, it is desirable to use as little as possible, that is to say the amount necessary for sufficient coupling between the isoprene elastomer and the reinforcing inorganic filler. The effectiveness of the activated ethylenic double bond makes it possible, in a large number of cases, to use POS at a preferential rate of between 0.5% and 20% by weight relative to the amount of reinforcing inorganic filler; rates below 15%> are more particularly preferred.

A person skilled in the art will understand that the POSs described above could be grafted beforehand on the reinforcing inorganic fillers, in particular on silica, via their function (s) Y, the reinforcing inorganic fillers thus precoupled then being able to be linked to the isoprene elastomer via their free X function (s) with activated ethylenic double bond.

H-4. Miscellaneous additives

Of course, the rubber compositions in accordance with the invention also comprise all or part of the additives usually used in rubber compositions comprising an isoprene elastomer and intended for the manufacture of tires, such as for example plasticizers, protective agents such as antiozone waxes, chemical antiozonants, antioxidants, anti-fatigue agents, adhesion promoters, a crosslinking system such as those based either on sulfur or on sulfur donors, accelerators and activators of vulcanization, etc. reinforcing inorganic can also be associated, if necessary, with a conventional white filler with little or no reinforcing, for example particles of clays, bentonite, talc, chalk, kaolin, titanium oxides.

The rubber compositions in accordance with the invention may also contain, in addition to the POSs (component C) described above, agents for covering the reinforcing inorganic filler, comprising for example the only function Y, or more generally aid agents. to the use which, in known manner, thanks to an improvement in the dispersion of the inorganic filler in the rubber matrix and to a reduction in the viscosity of the compositions, can improve their ability to be used in the raw state , these agents, used for example at a preferential rate of between 0.5 and 3 phr, being for example alkylalkoxysilanes, in particular alkyltriethoxysilanes, such as for example 1-octyl-triethoxysilane sold by the company Degussa-Hùls under the name Dynasylan Octeo or 1-hexa-decyl-triethoxysilane marketed by the company Degussa-Hûls under the name Si216, polyols, po lyethers (e.g. polyethylene glycols), primary, secondary or tertiary amines (e.g. trialkanol-amines), hydroxylated or hydrolyzable polyorganosiloxanes, for example α, co-dihydroxy-polyorganosiloxanes (in particular α, ω-dihydroxy-polydimethylsiloxanes).

As explained above, the compositions in accordance with the invention may also contain other coupling agents than component C, for example polysulphurized alkoxysilanes, when these compositions contain, in addition to the isoprene elastomer, other diene elastomers, for example of the SBR and / or BR type, the coupling of which with the reinforcing inorganic filler can then be advantageously ensured by conventional coupling agents such as polysulphurized alkoxysilanes.

II-5. Preparation of rubber compositions

The compositions are produced in suitable mixers, using two successive preparation phases well known to those skilled in the art: a first working or thermo-mechanical kneading phase (sometimes called a "non-productive" phase) at high temperature, up to a maximum temperature (noted T _ma χ) of between 110 ° C and 190 ° C, preferably between 130 ° C and 180 ° C, followed by a second phase of mechanical work (sometimes called the "productive" phase ) at a lower temperature, typically less than 110 ° C., for example between 60 ° C. and 100 ° C., finishing phase during which the crosslinking or vulcanization system is incorporated; such phases have been described for example in the aforementioned application EP 501227.

The manufacturing method according to the invention is characterized in that at least component B and component C are incorporated by kneading into component A during the first so-called non-productive phase, that is to say that the 'is introduced into the mixer and kneaded thermomechanically, in one or more steps, at least these different basic constituents until reaching a maximum temperature between 110 ° C and 190 ° C, preferably between 130 ° C and 180 ° C.

For example, the first (non-productive) phase is carried out in a single thermomechanical step during which all the necessary basic constituents, any agents, are introduced into a suitable mixer such as a conventional internal mixer. covering or additional processing and other various additives, with the exception of the vulcanization system. A second thermomechanical working step can be added to this internal mixer, after the mixture has fallen and intermediate cooling (cooling temperature preferably less than 100 ° C.), with the aim of subjecting the compositions to a complementary heat treatment, in particular to improve still the dispersion, in the elastomeric matrix, of the reinforcing inorganic filler and of its coupling agent. The total duration of the kneading, in this non-productive phase, is preferably between 2 and 10 minutes.

After the mixture thus obtained has cooled, the vulcanization system is then incorporated at low temperature, generally in an external mixer such as a roller mixer; the whole is then mixed (productive phase) for a few minutes, for example between 5 and 15 minutes. The final composition thus obtained is then calendered, for example in the form of a sheet, a plate or even a rubber profile usable for the manufacture of semi-finished products such as treads, crown plies, sidewalls, carcass plies, heels, protectors, inner tubes or waterproof inner liners for tubeless tires.

The vulcanization (or baking) is carried out in a known manner at a temperature generally between 130 ° C and 200 ° C, for a sufficient time which can vary for example between 5 and 90 min depending in particular on the baking temperature, the system of vulcanization adopted and of the vulcanization kinetics of the composition considered.

The vulcanization system proper is preferably based on sulfur and a primary vulcanization accelerator, in particular an accelerator of the sulfenamide type. To this basic vulcanization system are added, incorporated during the first non-productive phase and / or during the productive phase, various known secondary accelerators or vulcanization activators such as zinc oxide, stearic acid, derivatives guanidiques (in particular diphenylguanidine), etc. Sulfur is used at a preferential rate of between 0.5 and 10 phr, more preferably of between 0.5 and 5.0 phr, for example between 0.5 and 3.0 phr when the invention is applied to a strip. tire bearing. The primary vulcanization accelerator is used at a preferential rate of between 0.5 and 10 phr, more preferably between 0.5 and 5.0 phr in particular when the invention applies to a tire tread.

It goes without saying that the invention relates to the rubber compositions described above, both in the so-called "raw" state (ie, before baking) and in the so-called "cooked" or vulcanized state (ie, after crosslinking or vulcanization). .

Of course, the compositions in accordance with the invention can be used alone or as a blend (i.e., as a mixture) with any other rubber composition which can be used for the manufacture of tires.

III. EXAMPLES OF EMBODIMENT OF THE INVENTION

III- 1. Synthesis of POS coupling agents

A) POS "A"

An POS / 1 of imide type is prepared, with the starting organosilane of formula (X), N- [γ-propyl (methyldiethoxy) silane] maleamic acid, according to the following steps.

1.- Preparation of the starting maléamic acid silane:

The operation is carried out in a 2 liter glass reactor, equipped with a stirring system and a dropping funnel. The γ-aminopropylsilane of formula (C ₂ H ₅ O) ₂ CH ₃ Si (CH ₂ ) ₃ NH ₂ (300.3 g, i.e. 1.570 moles) is gradually poured at the temperature of 13-15 ° C. (reaction temperature maintained at this value by means of an ice water bath placed under the reactor) over a solution of maleic anhydride ( 160 g, or 1.633 moles) in toluene as solvent (569.9 g), over a period of 2 hours and 20 minutes. The reaction medium is then left at 23 ° C for 15 hours. At the end of this time, the reaction medium is filtered through a sintered glass of porosity 3 and a solution of the desired maleamic acid silane in toluene is thus recovered, a solution which is used in the form where it is found for the implementation of the following process. This solution contains 0.152 mole of silane maleamic acid per 100 g of solution.

2.- POS synthesis:

It is carried out by implementing the method (e) previously described, according to the following steps:

^{1st stage} : ZnCb (94.6 g, or 0.694 mol) is introduced into a 3-liter glass reactor, equipped with a stirring system and a dropping funnel, and then the solid is heated to 80 ° C for 1 hour 30 minutes under a reduced pressure of 4.10 ² Pa; the reactor is then returned to atmospheric pressure, operating under an argon atmosphere, and 150 cm ³ of toluene are then poured in, then gradually 413.5 g of the malane acid silane solution (181.8 g, or 0.629 mole) into toluene which was obtained previously in point 1;

- 2 times: the ^dropping funnel is loaded with cyclic hexamethyltrisilazane (51.2 g, ie 0.233 mole) and with 200 cm ³ of toluene; the temperature of the reaction medium is 90 ° C., then the cyclic hexamethyltrisilazane is poured in gradually over a period of 50 minutes; at the end of pouring, the orange-colored organic solution obtained is heated to a temperature of 80 ° C. and it is maintained at this temperature for 15 hours;

- 4 ^th time: the reaction mixture is filtered through "filter box", then the toluene is removed after devolatilization under reduced pressure.

A yellow oil is thus obtained which has been subjected to analyzes by proton NMR and by silicon NMR ( ²⁹ Si). The results of these analyzes reveal that the reaction product (POS A) contains approximately:

81.5% by weight of POS / 1 polymer of imide type having the form of an oligomer of average formula:

• 18.5% by weight of the organosilane of formula:

B) POS "B"

An POS / 2 of the ester type is prepared, by implementing the method (h) described above, with the activation method (2d), according to the following steps.

1.- Alcoholysis of maleic anhydride

In a 2 liter tetracol reactor, maleic anhydride is introduced (698.1 g, or 7.12 moles), then it is melted by heating the reactor using an oil bath brought to 70 °. vs. Once all of the anhydride has melted, methanol (221.4 g, or 6.92 moles) is introduced, with stirring, via a dropping funnel. The medium is then left under stirring for 20 hours at 23 ° C, then it is devolatilized by establishing a reduced pressure of 10.10 Pa for 1 hour, and finally it is filtered on filter paper. 786.9 g of monomethyl ester of maleic acid of formula are thus recovered (yield of 86%>):

2.- Preparation of the activated ester derivative according to the activation method (211:

Into a 2 liter glass reactor, equipped with mechanical stirring and a dropping funnel, are introduced: N-hydroxysuccinimide (105.4 g, or 0.916 mole), tetrahydrofuran as solvent (400 cm ³ ) and the monomethyl ester of maleic acid (100.9 g, or 0.776 mole). The reaction medium is stirred, and the pouring of the dicyclohexylcarbodiimide (206.2 g, or 1.001 moles) is carried out gradually, at room temperature (23 ° C), over a period of 10 minutes. The medium becomes heterogeneous due to the precipitation of dicyclohexylurea.

After a reaction period of 110 minutes, the reaction medium is filtered through a "bucher" and the filtrate is concentrated by evaporation at a temperature not exceeding 35 ° C. The residual reaction medium is left at a temperature of 4 ° C for 15 hours, then it is again filtered through a sintered glass containing 10 cm of silica. The second filtrate obtained is completely devolatilized under reduced pressure to remove the remaining solvent and the solid finally obtained is then recrystallized from a CH ₂ CI ₂ / ethylenic ether mixture.

43.3 g (25% yield ”) of the activated ester derivative of formula:

3.- Preparation of the amino POS:

In a 4 liter glass reactor fitted with mechanical stirring and an ascending cooler, γ-aminopropylsilane of formula (C2H ₅ O) ₂ CH ₃ Si (CH ₂ ) ₃ NH ₂ (1700.3 g) is introduced. , i.e. 8.9 moles). The pouring of the water (1442.5 g, or 80.13 moles) is done using a pouring pump having a flow rate of 10 cm ³ / hour. The reaction is exothermic throughout the casting and the temperature is not controlled.

After 3 hours of reaction, a water-ethanol mixture is removed under reduced pressure of 100 Pa, first at 40 ° C, then at 70 ° C to completely remove the ethanol and thus lead to an intermediate amino oil .

350.24 g of the intermediate amino oil obtained at the end of the preceding step, a polydimethylsiloxane oil α, ω, are introduced into another 1 liter reactor, also provided with mechanical stirring and with a condenser. -dihydroxylated (230.92 g) having a viscosity of 50 mPa.s at 25 ° C and titrating 12% by weight of OH, as well as catalyst based on potassium siliconate (0.0416 g). The reaction medium is heated at 90 ° C for 6 hours.

At the end of this time, the reaction medium is left for 15 hours at room temperature (23 ° C), then it is neutralized using 0.0974 g of a mixture based on phosphoric acid and polydimethylsiloxane oligomers , operating at 90 ° C for 1 hour. The reaction medium obtained is filtered through a microporous filter of 0.5 μm.

The amino POS obtained was subjected to proton and silicon NMR analyzes. The results of these analyzes reveal a mixture of linear (74% molar) and cyclic (26% molar) structures having the following average formulas:

The POS thus obtained contains 0.51 amino function per 100 g of product.

4.- Preparation of compound A comprising a POS / 2 polymer of ester type by coupling of the activated ester derivative with the amino POS:

The activated ester derivative as prepared in point 2 above (19.88 g, ie 0.088 mole) is introduced into a tetracol reactor with 100 cm ³ of CH ₂ CI ₂ as solvent. The amine POS as prepared in point 3 above (15.62 g) is dissolved in 100 cm ³ of CH ₂ C1 ₂ , then the solution is introduced into a dropping funnel. The casting is carried out gradually over a period of one hour, on a reaction medium which has been cooled beforehand to 5 ° C. by an ice water bath.

When the casting is complete, the reaction medium is reacted at room temperature (23 ° C) for 15 hours. At the end of this time, the medium is transferred to a separating funnel, then it is washed 4 times in succession with water. The addition of a saturated aqueous NaCl solution is necessary to aid in the separation of the phases. The residual organic phase is recovered, dried over MgSO ₄ , then filtered through filter paper and finally the solvent is removed under reduced pressure and at room temperature (23 ° C).

An oil is thus obtained which has been subjected to analyzes by proton NMR and by silicon NMR ( ²⁹ Si).

The results of these analyzes reveal that the product thus synthesized (POS B) contains approximately: 94% by weight of POS / 2 polymer of ester type of medium formula:

6% by weight of the cyclic monofunctional POS of medium formula

ffl-2. Preparation of rubber compositions

The following tests are carried out as follows: an isoprene elastomer (or mixture of diene elastomers) is introduced into an internal mixer, filled to 70% and whose initial tank temperature is approximately 60 ° C. , if applicable), the reinforcing filler, the coupling agent, then the various other ingredients with the exception of the vulcanization system. Thermomechanical work (non-productive phase) is then carried out in one or two stages (total mixing time equal to approximately 7 min), until a maximum "fall" temperature of approximately 165 ° C is reached. The mixture thus obtained is recovered, it is cooled and then sulfur and sulfenamide are added on an external mixer (homo-finisher) at 30 ° C., mixing the whole (productive phase) for 3 to 4 minutes.

The compositions thus obtained are then calendered either in the form of plates (thickness of 2 to 3 mm) or of thin sheets of rubber for the measurement of their properties. physical or mechanical, either in the form of profiles which can be used directly, after cutting and / or assembling to the desired dimensions, as semi-finished products for tires, in particular as tire treads for trucks.

In the following tests, the isoprene elastomer used is natural rubber and the reinforcing inorganic filler (silica or silica / alumina blend), used at a preferential rate of between 30 and 80 phr, constitutes all or most of the reinforcing filler total, a fraction of this total reinforcing filler which may consist of carbon black.

III-3. Characterization tests

A) Trial 1

The purpose of this test is to demonstrate the improved coupling performance (inorganic filler / isoprene elastomer) in a composition in accordance with the invention, compared to a composition of the prior art using a conventional coupling agent TESPT.

Two rubber compositions based on natural rubber and reinforced with silica are prepared for this, these compositions being intended for treads for truck tires.

These two compositions are identical except for the following differences:

composition No. 1 (control): conventional TESPT coupling agent; composition No. 2 (according to the invention): POS A.

The two coupling agents tested are used at an isomolar rate in X functions, that is to say that whatever the composition tested, the same number of moles of X functions reactive with respect to the polyisoprene.

Relative to the weight of polyisoprene, the level of TESPT and that of POS are in both cases less than 5 pci, this amount representing in both cases less than 10%> by weight relative to the amount of reinforcing inorganic filler.

Tables 1 and 2 give the formulation of the different compositions (Table 1 - rate of the different products expressed in pce or pci), their properties before and after cooking (25 min at 150 ° C); the vulcanization system consists of sulfur and sulfenamide. Figure 1 attached reproduces the module curves (in MPa) as a function of the elongation (in%); these curves are denoted Cl and C2 and correspond respectively to compositions No. 1 and No. 2.

Examination of these different results in Table 2 and in Figure 1 attached leads to the following observations: - the toasting times (T5) are sufficiently long in all cases (more than 20 minutes), offering a significant margin of safety vis-à-vis the problem of toasting;

- the Mooney plasticity values remain low (less than 60 MU) whatever the composition considered, which is an indicator of a very good suitability of the compositions for processing in the raw state;

- after cooking, the composition according to the invention (No. 2) has the highest values of modulus under strong deformation (Ml 00 and M300) and of ratio M300 / M100, clear indicators for those skilled in the art of better reinforcement provided by the inorganic filler and its POS coupling agent; - the hysteresis properties are improved on the composition of the invention, ΔG in particular being divided by two, indicating a significantly reduced rolling resistance;

- It must be deduced from these results that the very sensitive (doubly) increase in Mooney viscosity observed on the composition of the invention is due to the formation, during kneading, of additional bonds between the inorganic filler and the polyisoprene, in d '' other terms of better coupling (inorganic filler / polyisoprene).

The appended FIG. 1 confirms the preceding observations well: the composition of the invention (curve C2) reveals a higher level of reinforcement (module) whatever the elongation rate, in particular with great deformation (elongations of 100%> and more) ; for such an elongation domain, this behavior clearly illustrates a better quality of the bond or coupling between the reinforcing inorganic filler and the isoprene elastomer.

B) Test 2

This test demonstrates the superior coupling performance of a POS with an activated ethylenic double bond, compared with that of an alkoxysilane also comprising an activated ethylenic double bond, namely trimethoxy-silylpropyl methacrylate (abbreviated as TMSPM).

This TMSPM, marketed by the company Hϋls under the name "Dynasylan Memo", has the known formula (see for example documents DE-A-43 19142 or US-A-5,484,848):

Two rubber compositions similar to the preceding compositions 1 and 2, based on natural rubber and reinforced with silica, are prepared for this test, intended for treads for truck tires. These two compositions have an identical formulation, except for the coupling agent used:

- composition No. 3 (witness): TMSPM;

- composition No. 4 (according to the invention): POS B. These two coupling agents are used here at an isomolar rate in X functions. Relative to the weight of polyisoprene, the rate of TESPT and that of POS are in both cases less than 5 pci, that is to say advantageously less than 10 %> by weight relative to the amount of reinforcing inorganic filler.

Tables 3 and 4 give the formulation of the two compositions (Table 3 - rate of the different products expressed in pce or pci), their properties before and after cooking (25 min at 150 ° C). Figure 2 attached reproduces meanwhile the modulus curves (in MPa) as a function of the elongation (in%>); these curves are denoted C3 and C4 and correspond respectively to compositions No. 3 and No. 4.

The examination of the various results in Table 4 shows that the two compositions have very similar and satisfactory properties with regard to the toasting times, the Mooney plasticities and the hysteresis properties. However, a substantial difference is noted between the two compositions with regard to the values of modulus under high elongation (Ml 00 and M300) and of M300 / M100 ratio, which are higher for the composition of the invention; this is a clear indicator for those skilled in the art of a higher reinforcement offered by the POS compared to the alkoxysilane, although the latter also carries an activated ethylenic double bond.

Figure 2 confirms the previous observations: the composition of the invention (curve C4). shows a significantly higher modulus whatever the elongation rate, in particular with large deformation (elongations of 100%) and more), which confirms a better quality of the bond or coupling between the reinforcing inorganic filler and the polyisoprene.

C) Trial 3

This test illustrates another preferred embodiment of the invention, in which the coupling agent POS with activated ethylenic double bond (component C) is combined with a covering agent for the reinforcing inorganic filler.

This covering agent is an α, ω-dihydroxy-polyorganosiloxane, it is incorporated into the composition according to the invention at the same time as the POS coupling agent (non-productive step), in order to improve the implementation at raw state (lower viscosity) and dispersion of the inorganic filler in the elastomeric matrix.

Two identical compositions are compared for this test, except for the following differences:

composition No. 5 (control): TESPT coupling agent (4 pce); composition No. 6 (invention): POS A (3 pce) + aaggeenntt ddee rreeccoouuvrement (1 pce).

Composition No. 5 is the test control and contains 8% by weight of TESPT relative to the weight of silica. Composition No. 6 is the composition according to the invention and advantageously contains, relative to the weight of silica, less than 8%> of the coupling agent with maleimide function (precisely 6%).

Tables 5 and 6 give the formulation of the different compositions, their properties before and after cooking (150 ° C, 25 minutes). Figure 3 reproduces the module curves (in MPa) as a function of the elongation (in%>); these curves are denoted C5 and C6 and correspond respectively to compositions No. 5 and No. 6. The vulcanization system consists of sulfur and sulfenamide.

The study of the different results demonstrates that composition No. 6 in accordance with the invention, compared with control composition No. 5, exhibits an improved compromise in properties:

- low Mooney plasticity in both cases;

- slightly higher safety at roasting; - after firing, modules with strong deformation (M 100, M300) and a report

M300 / M100 clearly superior, synonymous with better reinforcement and therefore improved coupling between the elastomer and the reinforcing inorganic filler,

- Figure 3 confirming the previous observations: composition No. 6 (curve C6) reveals a level of reinforcement (modulus) much greater with large deformation (elongations of 100% and more), compared to the control composition based on TESPT

(Curve C5).

It is also composition No. 6 which presents the most advantageous compromise with regard to hysteretic properties: lower tan (δ) _max , very noticeable reduction in non-linearity ΔG *.

While making it possible to reduce the level of coupling agent, the association of activated double bond POS with a covering agent thus offers a particularly advantageous compromise of properties to compositions reinforced with an inorganic filler such as silica.

D) Test 4

This test illustrates once again the beneficial effect of the invention in a composition based on natural rubber, comprising as reinforcing inorganic filler a blend (50/50 by volume) of silica and alumina (alumina as described in the above-mentioned application EP 810258).

Two identical compositions are compared with the following differences:

- composition No. 7: TESPT coupling agent (4 pce);

- composition N ° 8: POS A (4 pce).

Tables 7 and 8 give the formulation of the different compositions, their properties before and after cooking. The results demonstrate once again, in an isoprene matrix, the overall superiority of the POS coupling agent (composition No. 8) compared to the conventional coupling agent TESPT (composition No. 7), with in particular:

- slightly higher safety at roasting; - module M300, higher ratio (M300 / M100);

- more advantageous hysteretic properties, as illustrated by a lower tan (δ) _{max value} and a very significant reduction in non-linearity ΔG *. E Trial 5

This test demonstrates that the selected POS coupling agent leads to insufficient coupling performance with respect to a diene elastomer other than isoprene, in any case less than that offered by a conventional polysulphurized alkoxysilane such as TESPT.

For this, two compositions based on SBR elastomer reinforced with silica are prepared; these compositions, both not in accordance with the invention, are identical except for the coupling agent used: TESPT for composition No. 9, POS A with imide function for composition No. 10 (with an isomolar ratio in functions X). Composition No. 9 is a control composition typically used for passenger car tire treads.

Tables 9 and 10 give the formulation of the different compositions and their properties before and after cooking. FIG. 4 reproduces the modulus curves (in MPa) as a function of the elongation (in%), these curves being denoted C9 and CIO and corresponding respectively to compositions No. 9 and No. 10.

The study of the various results in Table 10 demonstrates that composition No. 10 based on POS, compared to control composition No. 9 based on TESPT, has markedly degraded properties, with in particular:

- a toasting time T5 increased very sharply (almost by a factor of four), prohibitively from an industrial point of view; - after firing, modules with strong deformation (Ml 00, M300) and a report

M300 / M100 clearly lower, clear indicators of a reinforcement and therefore of an insufficient coupling between the SBR elastomer and the reinforcing inorganic filler,

- Figure 4 confirming this last observation: composition No. 10 (curve C10) reveals a large deformation (elongations of 100% and more) a level of reinforcement (modulus) much lower, compared to the control composition based on TESPT ( Curve

C9);

- finally, an unfavorable development of hysteresis (tan (δ) _max increased by almost 40%>).

The coupling agent POS with an activated ethylenic double bond, in order to lead to improved performances compared to TESPT, must therefore be associated with an isoprene elastomer and not with any diene elastomer.

In conclusion, the POS coupling agent selected for the compositions in accordance with the invention comprising an isoprene elastomer gives the latter particularly high mechanical properties in the vulcanized state, while offering them very good processing properties. the raw state.

Unpredictably for a person skilled in the art, this multifunctional POS with an activated ethylenic double bond reveals in such compositions a performance clearly superior to that of the polysulphurized alkoxysilane TESPT, however considered to be In general, the best coupling agent (inorganic filler / diene elastomer) in rubber compositions reinforced with an inorganic filler such as silica.

It also unexpectedly demonstrates an efficiency greater than that of other known coupling agents, in this case alkoxysilanes, carrying an activated ethylenic double bond.

The invention finds particularly advantageous applications in rubber compositions which can be used for the manufacture of tire treads having both a low rolling resistance and a high resistance to wear, in particular when these treads are exclusively based on natural rubber or synthetic polyisoprene and are intended for tires for industrial vehicles of the Truck type.

Table 1

(1) natural rubber;

(2) "HD" type silica - "Zeosil 1165MP" from the company Rhodia in the form of microbeads (BET and CTAB: approximately 150-160 m ² / g);

(3) TESPT coupling agent ("Si69" from Degussa);

(4) POS A (imide function);

(5) N-1, 3-dimethylbutyl-N-phenyl-para-phenylenediamine ("Santoflex 6-PPD" from the company Flexsys);

(6) N-cyclohexyl-2-benzothiazyl-sulfenamide ("Santocure CBS" - Flexsys company)

Table 2

Table 3

(1) (2) (5) and (6) same as table 1;

(3) trimethoxysilylpropyl methacrylate ("Dynasylan Memo" from the company Hûls);

(4) POS B (with maleamic ester function);

Table 4

Table 5

(1) to (6) same as table 1;

(7) α, ω-dihydroxy-polymethylsiloxane

(Rhodorsil 48V50 oil from Rhodia).

Table 6

Table 7

(1) to (6) same as table 1;

(7) alumina "Baikalox CR125" from the company Baikowski (in powder form - BET: approximately 105 m ² / g);

(8) N330 carbon black.

Table 8

Table 9

(1) SBR with 57% of 1-2 polybutadiene units; 25% styrene; spread with 37.5% oil; expressed in dry SBR; Tg = -26 ° C; (27) to (6) same as table 1;

(7) diphenylguanidine ("Vulcacit D" from the company BAYER);

(8) mixture of macro- and microcrystalline anti-ozone waxes.

Table 10

Claims

1. Elastomeric composition usable for the manufacture of tires, based on at least (i) an isoprene elastomer (component A), (ii) an inorganic filler as a reinforcing filler (component B), (iii) a coupling (inorganic filler / isoprene elastomer), characterized in that this coupling agent (component C) is a multifunctional polyorganosiloxane (abbreviated "POS") comprising, grafted onto its silicon atoms, on the one hand at least one hydroxyl function or hydrolyzable (radical or "Y" function), on the other hand at least one group carrying at least one activated ethylenic double bond (radical or "X" function).

2. Composition according to claim 1, in which component A is chosen from the group consisting of natural rubber, synthetic polyisoprenes, isoprene copolymers and mixtures of these elastomers.

3. Composition according to claims 1 or 2, wherein the amount of component B is between 10 and 200 phr (parts by weight per hundred parts of elastomer).

4. Composition according to any one of claims 1 to 3, in which the amount of component C is greater than 0.5 pci (parts by weight per cent of isoprene elastomer).

5. Composition according to claim 4, in which the amount of component C is between 2 and 10 pci.

6. Composition according to any one of claims 1 to 5, in which the ethylenic double bond of component C is activated by at least one adjacent electron-attracting group chosen from the radicals carrying at least one of the C≈O bonds, C = C, C≡C, OH, OR (R alkyl), CN or OAr (Ar aryl), or at least one sulfur and / or nitrogen atom, or at least one halogen.

7. Composition according to claim 6, in which the adjacent electron-withdrawing group is chosen from acyl (-COR), carbonyl (> C = O), carboxyl (-COOH), carboxy-esters (-COOR) and carbamyl radicals. (-CO-NH2; -CO-NH-R; -CO-NR ₂ ), alkoxy (-OR), aryloxy (-OAr), hydroxy (-OH), alkenyls (-CH≈CHR), alkynyls (-C = CR), naphthyl (Cι ₀ H ₇ -), phenyl (C ₆ H ₅ -), the radicals carrying at least one sulfur (S) and / or nitrogen (N) atom, or minus a halogen.

8. Composition according to claim 7, in which the adjacent electron-withdrawing group is a carbonyl group (> C = O).

9. Composition according to any one of claims 1 to 8, in which the POS consists of siloxyl units, identical or different, of formula (I) which follows:

R ² _a Y _D X _c Si O (_ _a _ _ _c y ₂ in which :

- a, b and c are each integers or fractional from 0 to 3;

the radicals R ² , identical or different if there are more than one, represent a monovalent hydrocarbon radical;

- the radicals Y, identical or different if they are several, represent the hydroxyl or hydrolyzable function;

the radicals X, identical or different if there are more than one, represent the group carrying at least one activated ethylenic double bond,

with the reservation that:

- 0 <(a + b + c) <3; at least one radical X and at least one radical Y are present in the polysiloxane molecule.

10. Composition according to claim 9, in which the radicals Y are chosen from hydroxyl (OH) or alkoxyl (OR ¹ ) radicals, R ¹ being a monovalent hydrocarbon group, linear or branched, comprising from 1 to 15 carbon atoms.

11. Composition according to claim 10, in which R ¹ is chosen from Cι-C ₆ alkyls, C2-C ₆ alkoxyalkyls, C ₅ -Cg cycloalkyls and the phenyl radical.

12. Composition according to claims 10 or 11, in which the radicals Y are chosen from the group consisting of hydroxyl (OH), C1-C3 alkoxyls (OR ¹ ) and mixtures of these hydroxyls or alkoxyls.

13. Composition according to claim 12, in which the radicals Y are chosen from hydroxyl, methoxyl, ethoxyl and mixtures of these hydroxyls or alkoxyls.

14. A composition according to any one of claims 9 to 13, wherein the R ² radicals are chosen from alkyls C _j C₆ alkyl, cycloalkyls Cs-alkyl, in particular from methyl, ethyl, n-propyl, isopropyl , n-butyl, n-pentyl, cyclohexyl, and aryls, especially phenyl.

15. Composition according to claim 14, in which the radicals R ² are methyl radicals.

16. Composition according to any one of claims 9 to 15, in which the radical X is chosen from those of formulas (X / a), (X / b) or (X / c) below:

(X / b)

in which:

- B, is O, NH, N-alkyl, N-aryl, S, CH ₂ , CH-all yl or CH-aryl;

- B ₂ is N, CH, C-alkyl or C-aryl;

- the radicals R ', R "and R'", identical or different from each other, represent hydrogen, a Cι-C ₆ alkyl, substituted or unsubstituted, a cyano radical, a halogen or a C ₆ aryl - Cιo, substituted or unsubstituted, R "and / or R '" can also represent a monovalent group COOH or a derivative group of ester or amide type;

- the divalent group A is intended to ensure the bond with the polysiloxane chain.

17. Composition according to claim 16, in which the radical X is chosen from those of formulas (II) which follow:

CO - NR— R-

/

(11/5)

R ^{3 %} R 10

in which :

- the symbol V represents a divalent radical -O- or -NR ⁶ -;

- the symbol W represents a monovalent group COOR ⁷ or a monovalent group CONR ⁸ R ⁹ ;

- R ³ is a divalent alkylene radical, linear or branched, comprising from 1 to 15 carbon atoms whose free valence is carried by a carbon atom and is linked to a silicon atom, said radical R ³ being able to be interrupted within the alkylene chain with at least one heteroatom or at least one divalent group comprising at least one heteroatom;

- the symbols R ⁴ and R ⁵ , identical or different, each represent a hydrogen atom, a halogen atom, a cyano radical or an alkyl radical, linear or branched, having from 1 to 6 carbon atoms, R possibly additionally represent a monovalent COOR group;

- the symbols R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ , identical or different, each represent a hydrogen atom, an alkyl radical, linear or branched, having from 1 to 6 carbon atoms or a phenyl radical , the symbols R ⁸ and R ^{9 being} able, in addition, to form together and with the nitrogen atom to which they are linked, a single saturated ring having from 3 to 8 carbon atoms in the ring.

18. Composition according to claim 17, in which:

- R ³ represents an alkylene radical chosen from - (CH ₂ ) ₂ -; - (CH ₂ ) ₃ -; - (CH ₂ ) ₄ -; -CH ₂ -CH (CH ₃ ) -; - (CH ₂ ) ₂ -CH (CH ₃ ) -CH ₂ -; - (CH ₂ ) ₃ -O- (CH ₂ ) 3-; - (CH ₂ ) ₃ -O-CH ₂ -CH (CH ₃ ) - CH ₂ -; - (CH ₂ ) 3-O-CH ₂ CH (OH) -CH2-; - R ⁴ and R ⁵ are chosen from a hydrogen atom, chlorine or methyl ethyl, n-propyl, n-butyl radicals, R possibly also representing a COOR group where R represents hydrogen or methyl;

- R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are chosen from hydrogen and methyl, ethyl, n-propyl, n-butyl radicals, the symbols R and R being able, in addition, to form together and with the nitrogen atom a pyrrolidinyl or piperidyl ring.

19. Composition according to claim 18, in which R ³ is chosen from - (CH ₂ ) ₂ - and - (CH ₂ ) ₃ -; R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are chosen from hydrogen and methyl.

20. Composition according to any one of claims 9 to 19, in which the POS is an essentially linear POS corresponding to the following average formula (III):

(III) in which:

- the symbols R ¹ , R ² , X and Y are as defined above;

- the symbols R are chosen from R, X and Y;

- the symbols T ¹ are chosen from the patterns HOι _{/ 2} and R ^! Oι _{/ 2} ;

- The symbols T ² , identical or different from the symbols T ¹ , are chosen from the units HO1 / 2, R'θι / 2 and the unit (R ² ) ₃ SiO _m ;

- the symbols m, n, p, q, r, s and t each represent whole or fractional numbers which meet the following cumulative conditions:

. m and t are different from zero and their sum is equal to 2 + s;

. n, p, q and r are in the range of 0 to 100;

. s is in the range from 0 to 75;

. when n = 0, p is different from zero and when p = 0, n is different from zero;

. the sum (n + p + q + r + s + t) is in the range from 2 to 250;

. the ratio 100 s / (n + p + q + r + s + t) is at most equal to 30, preferably at most equal to

20; . the ratio 100 (m + p + r + s [when R ¹¹ = Y] + t) / (n + p + q + r + s + t) is equal to or greater than 1, preferably within a domain of 4 100 ; . the ratio 100 (n + p + s [when R ¹¹ = X]) / (n + p + q + r + s + t) is equal to or greater than 1, preferably within a range of 2 to 100.

21. Composition according to any one of claims 1 to 20, in which the amount of component C represents between 0.5%> and 20% by weight relative to the amount of component B.

22. Composition according to claim 21, in which the amount of component C represents less than 15% by weight relative to the amount of component B.

23. Composition according to any one of claims 1 to 22, in which component B is predominantly silica.

24. Composition according to any one of claims 1 to 22, in which component B is mainly alumina.

25. Composition according to any one of claims 1 to 24, in which component B constitutes the whole of the reinforcing filler.

26. Composition according to any one of claims 1 to 24, in which component B is used in admixture with carbon black.

27. Composition according to any one of claims 2 to 26, in which component A is chosen from natural rubber, synthetic cis-1,4 polyisoprenes and mixtures of these elastomers.

28. The composition of claim 27, wherein component A is natural rubber.

29. Composition according to any one of claims 1 to 28, comprising an agent for recovering the inorganic filler.

30. Composition according to claim 29, the covering agent being a hydroxylated polyorganosiloxane.

31. Composition according to claim 30, the covering agent being an α, ω-dihydroxy-polyorganosiloxane.

32. Composition according to any one of claims 1 to 31, characterized in that it is in the vulcanized state.

33. Process for preparing a rubber composition vulcanizable with sulfur and usable for the manufacture of tires, characterized in that there is incorporated into (i) at least one isoprene elastomer, at least: (ii) an inorganic filler as filler reinforcing and (iii), as coupling agent (inorganic filler / isoprene elastomer), a multifunctional polyorganosiloxane comprising, grafted onto its silicon atoms, on the one hand at least one hydroxyl or hydrolyzable function, on the other hand at at least one group carrying at least one activated ethylenic double bond, and in that thermomechanically kneading the whole, in one or more steps, until reaching a maximum temperature of between 110 ° C. and 190 ° C.

34. The method of claim 33, the ethylenic double bond of component C being activated by at least one adjacent electron-withdrawing group chosen from the radicals carrying at least one of the bonds C = O, C = C, C≡C, OH, OR (R alkyl), CN or OAr (Ar aryl), or at least one sulfur and / or nitrogen atom , or at least one halogen.

35. The method of claim 34, the adjacent electron-withdrawing group being a carbonyl group (> C = O).

36. Method according to any one of claims 33 to 35, the POS consisting of siloxyl units, identical or different, of form (I) which follows:

^R2 a ^γ b ^x c ^Si 0 (4-abc) / 2 in which:

a, b and c are each integers or fractional from 0 to 3; - the radicals R, identical or different if there are more than one, represent a monovalent hydrocarbon radical;

- the radicals Y, identical or different if they are several, represent the hydroxyl or hydrolyzable function; the radicals X, which are identical or different if there are more than one, represent the group carrying at least one activated ethylenic double bond,

with the reservation that:

- 0 <(a + b + c) <3; - at least one radical X and at least one radical Y are present in the polysiloxane molecule.

37. The method of claim 36, the radicals R being chosen from methyl, ethyl, n-propyl, isopropyl, n-butyl, n-pentyl, cyclohexyl and phenyl.

38. Process according to claims 36 or 37, the radicals Y being chosen from hydroxyl, methoxyl and ethoxyl.

39. Method according to any one of claims 36 to 38, the radical X being chosen from those of formulas (X / a), (X / b) or (X / c) below:

O

(X / c)

in which:

- Bi is O, NH, N-alkyl, N-aryl, S, CH ₂ , CH-alkyl or CH-aryl;

- B ₂ is N, CH, C-alkyl or C-aryl;

- the radicals R ', R "and R'", identical or different from each other, represent hydrogen, a Cι-C ₆ alkyl, substituted or unsubstituted, a cyano radical, a halogen or a C ₆ aryl - Cιo, substituted or unsubstituted, R "and / or R '" can also represent a monovalent group COOH or a derivative group of ester or amide type;

- the divalent group A is intended to ensure the bond with the polysiloxane chain.

40. Method according to claim 39, the radical X being chosen from those of formulas (II) which follow:

in which :

- the symbol V represents a divalent radical -O- or -NR ⁶ -;

- the symbol W represents a monovalent group COOR ⁷ or a monovalent group CONR ⁸ R ⁹ ;

- R ³ is a divalent alkylene radical, linear or branched, comprising from 1 to 15 carbon atoms whose free valence is carried by a carbon atom and is linked to a silicon atom, said radical R being able to be interrupted within the alkylene chain with at least one heteroatom or at least one divalent group comprising at least one heteroatom;

- the symbols R ⁴ and R ⁵ , identical or different, each represent a hydrogen atom, a halogen atom, a cyano radical or an alkyl radical, linear or branched, having from 1 to 6 carbon atoms, R ⁵ can also represent a monovalent group COOR ⁷ ;

- the symbols R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ , identical or different, each represent a hydrogen atom, an alkyl radical, linear or branched, having from 1 to 6 carbon atoms or a phenyl radical , the symbols R ⁸ and R ^{9 being} able, in addition, to form together and with the nitrogen atom to which they are linked, a single saturated ring having from 3 to 8 carbon atoms in the ring.

41. The method of claim 40, wherein R ³ is chosen from - (CH ₂ ) ₂ - and - (CH ₂ ) ₃ -; R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are chosen from hydrogen and methyl.

42. Method according to any one of claims 33 to 41, in which the POS is an essentially linear POS corresponding to the following average formula (III):

(III) in which :

- the symbols R ¹ , R ² , X and Y are as defined above;

- the symbols R are chosen from R, X and Y; - the symbols T ¹ are chosen from the patterns

- The symbols T, identical or different from the symbols T, are chosen from the units HO1 / 2, R'Rι _/ 2 and the unit (R ² ) ₃ SiO _1/2 ;

- the symbols m, n, p, q, r, s and t each represent whole or fractional numbers which meet the following cumulative conditions: • m and t are different from zero and their sum is equal to 2 + s;

• n, p, q and r are in the range from 0 to 100;

• s is in the range from 0 to 75;

• when n = 0, p is different from zero and when p = 0, n is different from zero;

• the sum (n + p + q + r + s + t) is in the range from 2 to 250; "The ratio 100 s / (n + p + q + r + s + t) is at most equal to 30, preferably at most equal to

20;

• the ratio 100 (m + p + r + s [when R ¹¹ = Y] + t) / (n + p + q + r + s + t) is equal to or greater than 1, preferably included in a domain of 4 to 100;

. the ratio 100 (n + p + s [when R ¹¹ = X]) / (n + p + q + r + s + t) is equal to or greater than 1, preferably within a range of 2 to 100.

43. Use of a rubber composition according to any one of claims 1 to 31, for the manufacture of tires or semi-finished products intended for tires, these semi-finished products being chosen in particular from the group consisting of the treads, the under-layers of these treads, the crown plies, the sidewalls, the carcass plies, the beads, the protectors, the air chambers and the inner rubber compounds for tubeless tires.

44. A tire in the raw state comprising a rubber composition according to any one of claims 1 to 31.

45. A tire in the baked state comprising a rubber composition according to claim 32.

46. Semi-finished product for a tire, comprising a rubber composition according to any one of claims 1 to 31, this product being chosen in particular from the group consisting of treads, the under-layers of these strips. bearing, crown plies, sidewalls, carcass plies, heels, protectors, air chambers and internal rubber compounds for tubeless tires.

47. Semi-finished product according to claim 46, consisting of a tire tread for a heavy vehicle.

48. Use, as coupling agent (inorganic filler / isoprene elastomer), in an elastomeric composition reinforced with an inorganic filler, of a multifunctional polyorganosiloxane comprising, grafted on its silicon atoms, of a at least one hydroxyl or hydrolyzable function, on the other hand at least one group carrying at least one activated ethylenic double bond.

49. Method for coupling an inorganic filler and an isoprene elastomer, in a rubber composition which can be used for the manufacture of tires, characterized in that at least one isoprene elastomer is incorporated, at least one inorganic filler as reinforcing filler and a multifunctional polyorganosiloxane comprising, grafted onto its silicon atoms, on the one hand at least one hydroxyl or hydrolyzable function, on the other hand at least one group carrying at least one activated ethylenic double bond, and in that it is kneaded thermomechanically, in one or more stages, until a maximum temperature of between 110 ° C and 190 ° C is reached.