WO2012059234A1

WO2012059234A1 - Use of silica having specific particle size distribution and/or pore distribution and of 3-acryloxy-propyltriethoxysilane in an isoprene elastomer composition

Info

Publication number: WO2012059234A1
Application number: PCT/EP2011/005554
Authority: WO
Inventors: Laurent Guy
Original assignee: Rhodia Operations; Dow Corning Corporation
Priority date: 2010-11-03
Filing date: 2011-11-03
Publication date: 2012-05-10
Also published as: FR2966831A1; FR2966831B1

Abstract

The invention relates to the combined use, in an elastomer composition including an isoprene elastomer, of highly structured silica as an inorganic reinforcing filler, and of 3-acryloxy-propyltriethoxysilane as an agent for binding the inorganic filler and elastomer together, wherein said silica has a CTAB specific surface area of between 40 and 525 m²/g, a BET specific surface area of between 45 and 550 m²/g, an object size distribution width Ld ((d84 - d16)/d50) of at least 0.91, and a pore volume distribution such that the ratio of V_{(d5 - d50)}/V_{(d5 - d100)} is at least 0.66. The invention also relates to the resulting elastomer compositions, and to the articles manufactured from said compositions.

Description

USE OF A PARTICULAR POROUS GRANULOMETRIC DISTRIBUTION SILICA AND / OR POROUS DISTRIBUTION AND 3-ACRYLOXY-PROPYLTRIETHOXYSILANE IN AN ISOPRENE (S) ELASTOMERIC COMPOSITION

The invention relates to the joint use, in elastomer compositions (s) comprising an isoprene elastomer, such as natural rubber, of a particular reinforcing inorganic filler and a particular inorganic filler - elastomer coupling agent.

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

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

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

It is known to those skilled in the art that it is generally necessary to employ in the elastomer compositions containing such reinforcing fillers a coupling agent, also called a binding agent, whose function is, in particular, to providing the connection between the surface of the inorganic filler particles (for example a precipitated silica) and the elastomer (s), while facilitating the dispersion of this inorganic filler within the elastomeric matrix.

The term "inorganic filler-elastomer coupling agent" is understood to mean an agent capable of establishing a sufficient chemical and / or physical connection between the inorganic filler and the elastomer.

Such a coupling agent, at least bifunctional, has for example as simplified general formula "N-V-M", in which:

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

M represents a functional group ("M" function) capable of binding physically and / or chemically to the elastomer, in particular via a suitable atom or group of atoms (for example an atom of sulfur);

- V represents a group (divalent / hydrocarbon) for connecting "N" and "M".

The coupling agents should not be confused with simple inorganic filler agents which, in a known manner, may have the "N" function active with respect to the inorganic filler but lack the "M" function. active with respect to the elastomer.

Coupling agents, in particular (silica-elastomer), have been described in numerous documents of the state of the art, the best known being (poly) sulphide silanes, in particular (poly) sulphurized alkoxysilanes. Among these (poly) sulphurized silanes, mention may be made especially of tetrasulphide of triethoxysilylpropyl (abbreviated TESPT), which is generally still considered today as a product providing, for vulcanisais comprising an inorganic filler as a reinforcing filler, such as silica, a very good or even the best compromise in term safety to the grid, ease of implementation and strengthening power.

The combined use of precipitated silica, in particular highly dispersible silica and a silane (or organosilic compound functionalized) polysulfide in a modified elastomer composition (s) allowed the development of the "green tire" for passenger vehicles (Light vehicles). This combination achieved a wear resistance performance comparable to that of carbon black-reinforced elastomer blends, while significantly improving rolling resistance (resulting in lower fuel consumption). fuel), and grip on wet ground.

It would therefore be interesting to also be able to use an inorganic filler such as silica in tires for trucks, tires which are obtained from compositions based on isoprene elastomer (s), mainly natural rubber.

However, the same polysulfide silica / silane combination applied to an isoprene elastomer, such as natural rubber, did not provide a sufficient level of reinforcement compared to what is obtained when carbon black is used as a filler. recessed reinforcement leading to poor wear resistance.

The object of the present invention is to propose in particular the combination for elastomer compositions comprising a diene elastomer, such as natural rubber, with a particular coupling agent with a particular reinforcing inorganic filler, this combination consisting of as an alternative to the use of known coupling agents with known reinforcing inorganic fillers, this combination furthermore providing, to said elastomer compositions (s), a compromise of satisfactory properties, in particular with regard to their rheological properties and / or or dynamic, especially hysteretic. Advantageously, it allows an improvement of the wear resistance. In addition, the elastomer compositions obtained preferentially exhibit good adhesion to both the reinforcing inorganic filler employed and the substrates to which they are subsequently applied. The invention relates in its first object to the use in an elastomer composition (s), comprising at least one isoprene elastomer:

a silica, as reinforcing inorganic filler, said silica having:

. a CTAB specific surface area of between 40 and 525 m ² / g, in particular between 80 and 290 m ² / g, and

. a BET specific surface area of between 45 and 550 m ² / g, in particular between 90 and 320 m ² / g,

with

3-acryloxypropyltriethoxysilane (or γ-acryloxypropyltriethoxysilane), as an inorganic filler-elastomer coupling agent,

said silica having additional characteristics according to different variants of the invention.

The silica used in the invention, rather of the precipitated silica type, is highly structured and has a specific particle size distribution and / or a particular porous distribution.

Unless otherwise stated in this specification, the definitions and methods for measuring the different parameters of the silica used according to the invention are those given in application WO 03/016215.

According to a first variant of the invention, the silica employed has: a width Ld ((d84 - d16) / d50) of object size distribution measured by XDC granulometry after ultrasound deagglomeration of at least 0.91, in particular at least 0.94, for example d 'at least 1, 04, and

. a porous volume distribution as a function of pore size such that the ratio V ₍ d 5, d 50) V (d 5 - dioo) is at least 0.66, for example at least 0.68.

In this first variant, the silica used may optionally have a ratio V _(d 5 - _d 50) _(d 5 - dioo) of at least 0.71, in particular of at least 0.73, for example at least 0 74.

As indicated in WO 03/016215: the width Ld of object size distribution, measured by XDC granulometry, after ultrasound disagglomeration (in water), corresponds to the ratio (d84-d16) / d50 in which dn is the size for which one is % of particles (in mass) smaller than this size (the distribution width Ld is therefore calculated on the cumulative particle size curve, taken in its entirety);

- (d5 - d50) represents the pore volume constituted by the pores of diameters between d5 and d50, and V (d5 - di oo) represents the pore volume constituted by the pores of diameters between d5 and d100, dn being here the pore diameter for which n% of the total surface area of all pores is provided by pores larger than this diameter (the total pore area (S ₀ ) can be determined from the mercury intrusion curve) .

According to a second variant of the invention, the silica employed has a porous distribution width Idp greater than 0.70, for example greater than 0.80, or even greater than 0.85.

As indicated in the application WO 03/016215, the porous distribution width Idp is obtained from the porous pore volume distribution curve (ml / g) as a function of the pore diameter (nm): the coordinates of the point S corresponding to the main population, namely the values of the diameter (nm) Xs and the pore volume (ml / g) Y _s ; we draw a line of equation Y = Y _s / 2; this line intersects the porous distribution curve at two points A and B having abscissa (nm) respectively X _A and XB on either side of Xs; the porous distribution width Idp is equal to the ratio (XA - XB) / Xs

Preferably, according to this variant of the invention, said silica also has a width Ld ((d84-d16) / d50) of object size distribution measured by XDC granulometry after ultrasound disagglomeration of at least 0, 91, in particular at least 0.94, for example at least 1.0.

According to a third variant of the invention, the silica employed has. a width The d ((d84-d16) / d50) of object size distribution less than 500 nm, measured by XDC particle size after ultrasound deagglomeration, of at least 0.95 and . a porous volume distribution as a function of pore size such that the ratio V _(d 5 - ci50) / (d5 - ciioo) is at least 0.71, in particular at least 0.73, for example at least 0.74, or even at least 0.78.

As indicated in the application WO 03/016215, the width D of the object size distribution of less than 500 nm, measured by XDC granulometry, after ultrasonic deagglomeration (in water), corresponds to the ratio (d84 d16) / d50 where dn is the size for which one% of particles (in mass), with respect to particles smaller than 500 nm, are smaller than this size (the distribution width d is therefore calculated on the cumulative particle size curve, truncated above 500 nm).

According to a fourth variant of the invention, the silica employed has: a width The d ((d84-d16) / d50) of an object size distribution of less than 500 nm, measured by XDC granulometry after ultrasound disagglomeration, of at least 0.90, in particular from minus 0.92, and

. a pore volume distribution as a function of the size of the pores such that the ratio V _(d5 _d5 o.) / V _(d5 - DIØØ) is at least 0.74, especially at least 0.78, in particular at least 0.80, or at least 0.78. In the silica used according to the invention (i.e., according to one of the four variants of the invention), the volume contributed by the larger pores is usually the largest part of the structure.

It may have both an object size distribution width Ld of at least 1.04 and an object size distribution width d (less than 500 nm) of at least 0.95.

The object-size distribution width Ld of the silica employed in the invention may in certain cases be at least 1, 10, in particular at least 1, 20, for example at least 1, 30 . The first variant and the second variant described above are the preferred variants of the invention. Preferably, the silica used according to the invention, in particular in the case of the first and second variants, has a CTAB specific surface area of between 170 and 270 m ² / g.

In a very preferred manner, especially in the case of the first and second variants, its CTAB specific surface area is between 180 and 240 m ² / g, in particular between 190 and 210 m ² / g.

Likewise, preferably, the silica used according to the invention, in particular in the case of the first and second variants, has a BET specific surface area of between 180 and 290 m ² / g.

In a very preferred manner, especially in the case of the first and second variants, its BET specific surface area is between 190 and 260 m ² / g, in particular between 200 and 240 m ² / g, for example between 210 and 230 m ² / g. boy Wut.

The silica employed according to the present invention may have some microporosity; thus, this silica may be such that (BET surface - CTAB surface) ≥ 5 m ² / g. In general, this microporosity is not too important; this silica is generally such that (BET surface - CTAB surface) <40 m ² / g, in particular (BET surface - CTAB surface) <30 m ² / g.

The CTAB specific surface area is the external surface, which can be determined according to the NF T 45007 method (November 1987). The BET surface area can be measured according to the method of BRUNAUER - EMMETT - TELLER described in "The Journal of the American Chemical Society", vol. 60, page 309 (1938) and corresponding to standard NF T 45007 (November 1987).

In general, the silica employed according to the invention has an aluminum content of less than 0.5% by weight, in particular less than 0.35% by weight, for example less than 0.2% by weight.

The amount of aluminum can be measured by any suitable method, for example by ICP-AES ("Inductively Coupled Plasma - Atomic Emission Spectroscopy") after dissolution in water in the presence of hydrofluoric acid.

In general, the silica implemented according to the invention has a particular surface chemistry, such as it has a ratio (Sears number x 1000) / (BET specific surface) less than 60, preferably less than 55, for example less than 50.

The silica used according to the invention generally has a high object size and therefore atypical, which may be such that the mode of its particle size distribution measured by XDC granulometry after deagglomeration with ultrasound (in water) meets the condition : XDC mode (nm) ≥ (5320 / specific surface area (m ² / g)) + 8, even if: XDC mode (nm) ≥ (5320 / CTAB specific surface area (m ² / g)) + 10. L The dispersibility (and disagglomeration) of the silica used according to the invention can be assessed by means of the following test, by a granulometric measurement (by laser diffraction) carried out on a suspension of silica previously deagglomerated by ultraviolet. sonification (breaking objects from 0.1 to a few tens of microns). Ultrasonic deagglomeration is carried out using a VIBRACELL BIOBLOCK (750 W) sonicator equipped with a 19 mm diameter probe. The particle size measurement is carried out by laser diffraction on a SYMPATEC granulomer, using the Fraunhofer theory.

In a pillbox (height: 6 cm and diameter: 4 cm), 2 grams of silica are weighed and the mixture is made up to 50 grams by addition of deionized water: a 4% aqueous suspension of silica is thus obtained which is homogenized during 2 minutes by magnetic stirring. The deagglomeration is then carried out under ultrasound as follows: the probe being immersed over a length of 4 cm, it is put into action for 5 minutes and 30 seconds at 80% of its nominal power (amplitude). The granulometric measurement is then carried out by introducing into the vat of the granulometer a volume V (expressed in ml) of the homogenized suspension necessary to obtain an optical density of approximately 20.

The value of the median diameter 0 ₅ o obtained according to this test is even lower than the silica has a high ability to deagglomerate.

A disaggregation factor F _D is given by the equation:

F _D = 10 x V / optical density of the suspension measured by the granulometer (this optical density is about 20). This disaggregation factor F _D is indicative of the level of particles smaller than 0.1 μm which are not detected by the particle size analyzer. This factor is all the higher as the silica has a high deagglomeration ability.

In general, the silica used according to the invention has a median diameter δ ₅₀ , after deagglomeration with ultrasound, lower than 8.5 μm; it may be less than 6.0 μm, for example less than 5.5 μm.

It may have an ultrasonic deagglomeration factor F _D greater than 3.5 ml, in particular greater than 4.5 ml, for example greater than 9 ml.

The silica used in the invention preferably has a satisfactory dispersibility (dispersibility) in the polymers.

The pH of the silica used according to the invention is generally between 6.0 and 7.5.

The pH is measured according to the following method deriving from the ISO 787/9 standard (pH of a suspension at 5% in water):

Apparatus:

- calibrated pH meter (reading accuracy at 1 / 100th)

- combined glass electrode

- 200 mL beaker

- 100 mL test tube

- precision balance to 0.01 gram.

Operating mode:

5 grams of silica are weighed to the nearest 0.01 gram in the beaker of

200 mL. 95 mL of water measured from the graduated cylinder is then added to the silica powder. The suspension thus obtained is stirred vigorously (magnetic stirring) for 10 minutes. The pH measurement is then performed.

The physical state in which the silica to be used according to the invention is present may be arbitrary, that is to say that it may be, for example, powder, granules or microbeads (substantially spherical beads). It can thus be in the form of a powder of average size of at least 3 μm, in particular at least 10 μm, preferably at least 15 μm. This is for example between 15 and 60 pm.

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

It may, preferably, be in the form of substantially spherical beads of average size of at least 80 μm, in particular at least 100 μm, for example at least 150 μm; it is generally at most 300 μm, in particular between 100 and 270 μm, for example between 150 and 270 μm; this average size is determined according to standard NF X 11507 (December 1970) by dry sieving and determination of the diameter corresponding to a cumulative refusal of 50%.

The silica used in the context of the invention may be prepared for example by a method as described in WO 03/016215.

Preferably, the silica employed in the invention can be obtained by a preparation process comprising the reaction of a silicate with an acidifying agent whereby a suspension of silica is obtained, and then the separation and drying of this suspension , in which among others the reaction of the silicate with the acidifying agent is carried out according to the following successive steps:

(i) forming an aqueous base stock having a pH of between 2 and 5, preferably between 2.5 and 5,

(ii) at the same time, said silicate and acidifying agent are added to said base stock, such that the pH of the reaction medium is maintained between 2 and 5, preferably between 2.5 and 5,

(iii) stopping the addition of the acidifying agent while continuing the addition of silicate in the reaction medium until a pH value of the reaction medium of between 7 and 10, preferably between 7 and 10 is obtained; , 5 and 9.5,

(iv) simultaneously adding silicate and acidifying agent to the reaction medium, such that the pH of the reaction medium is maintained between 7 and 10, preferably between 7.5 and 9.5, (v) stopping the addition of the silicate while continuing the addition of the acidifying agent in the reaction medium until a pH value of the reaction medium of less than 6.

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

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

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

The elastomer compositions in which 3-acryloxypropyltriethoxysilane is used according to the invention can contain at least one silica-covering agent used as a reinforcing filler. This covering agent is capable, in a known manner, of improving the processability of the elastomer compositions in the green state.

Such a coating agent may consist for example of an alkylalkoxysilane (in particular an alkyltriethoxysilane), a polyol, a polyether (especially a polyethylene glycol), a polyetheramine, a primary amine, secondary or tertiary (in particular a trialkanolamine), an α, ω-dihydroxylated polydimethylsiloxane or an α, ω-diamine polydimethylsiloxane.

This coating agent may optionally be mixed with said precipitated silica and 3-acryloxypropyltriethoxysilane prior to their use.

The elastomer compositions in which the 3-acryloxypropyltriethoxysilane and the silica described above are used according to the invention may optionally comprise at least one other inorganic filler-elastomer coupling agent, in particular a sulphurized silane or polysulfide.

Examples of such a coupling agent are:

bis-triethoxysilylpropyl disulphide (abbreviated TESPD) of formula:

(C2H ₅ O) 3Si- (CH 2) 3 -S 2 - (CH 2) 3 -Si (OC 2 H 5) 3

bis-triethoxysilylpropyl tetrasulfide (abbreviated TESPT) of formula:

(C 2 H ₅ O) 3 Si- (CH2) 3-S4- (CH2) 3-Si (OC2H5) 3

bis-monohydroxydimethylsilylpropyl tetrasulfide of formula:

(HO) (CH ₃ ) 2Si- (CH 2) 3 -S 4 - (CH ₂ ) 3 -Si (CH ₃ ) ₂ (OH)

bis-monoethoxydimethylsilylpropyl disulfide (abbreviated as MESPD) of formula:

(C 2 H ₅ O) (CH3) 2Si- (CH2) 3-S2- (CH2) 3-Si (CH3) 2 (OC2H5)

bis-monoethoxydimethylsilylpropyl tetrasulfide (abbreviated as MESPT) of formula:

(C 2 H ₅ O) (CH3) 2Si- (CH2) 3-S4- _(CH2) 3-Si (CH3) 2 (OC2H5)

bis-monoethoxydimethylsilylisopropyl tetrasulfide (abbreviated to MESiPrT) of formula:

(C2H5O) (CH3) 2 Si-CH2-CH- (CH3) -S4- (CH3) -CH-CH2-Si (CH3) 2 (OC ₂ H5)

However, preferably, said elastomer compositions (s) do not contain any other inorganic filler-elastomer coupling agent other than 3-acryloxypropyltriethoxysilane.

The use according to the invention may optionally be carried out in the presence of a free radical initiator (for example from 0.02 to 5%, in particular from 0.05 to 0.5%, by weight relative to the amount in question. elastomer weight (s)), i.e. a compound (in particular an organic compound) capable, in particular following energetic activation, of generating free radicals in situ in its surrounding environment, in this case in the elastomer (s). The initiator of free radicals is here an initiator of the type with thermal initiation, that is to say that the energy supply, for the creation of free radicals, is in thermal form. Its decomposition temperature should generally be below 180 ° C, in particular below 160 ° C.

It is for example chosen from the group consisting of organic peroxides, organic hydroperoxides, azido compounds, bis (azo) compounds, peracids, peresters or a mixture of at least two of these compounds. It is in particular an organic peroxide, for example benzoyl peroxide, acetyl peroxide, lauryl peroxide, peroxide of 1, 1 bis (t-butyl) -3,3,5-trimethylcyclohexane, peroxide optionally being placed on a solid support, such as calcium carbonate.

However, preferably, the invention is implemented in the absence of any free radical initiator.

The elastomer composition (s) employed in the invention may advantageously not comprise other elastomers than the isoprene elastomer (s) it contains.

It may optionally (non-preferred variant) comprise at least one elastomer other than isoprene. In particular, it may optionally comprise at least one isoprene elastomer (for example natural rubber) and at least one diene elastomer other than isoprene, the amount of isoprene elastomer (s) relative to the total amount of elastomer (s) then being preferably greater than 50% (generally less than 99.5%, and for example between 70 and 99%) by weight.

The elastomer composition (s) used according to the invention generally comprises at least one isoprene elastomer (natural or synthetic) chosen from:

(1) synthetic polyisoprenes obtained by homopolymerization of isoprene or 2-methyl-1,3-butadiene; (2) synthetic polyisoprenes obtained by copolymerization of isoprene with one or more ethylenically unsaturated monomers chosen from:

(2.1) conjugated diene monomers, other than isoprene, having from 4 to 22 carbon atoms, such as, for example, butadiene-1,3, 2,3-dimethyl-1,3-butadiene, 2-chloro butadiene-1,3 (or chloroprene), 1-phenyl-1,3-butadiene, 1,3-pentadiene, 2,4-hexadiene;

(2.2) aromatic vinyl monomers having 8 to 20 carbon atoms, such as, for example, styrene, ortho-, meta- or paramethylstyrene, the commercial "vinyl-toluene" mixture, paratertiobutylstyrene, methoxystyrenes, chlorostyrenes vinylmesitylene, divinylbenzene, vinylnaphthalene;

(2.3) vinyl nitrile monomers having 3 to 12 carbon atoms, such as, for example, acrylonitrile, methacrylonitrile;

(2.4) acrylic ester monomers derived from acrylic acid or methacrylic acid with alkanols having from 1 to 12 carbon atoms, such as, for example, methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, methacrylate, isobutyl;

(2.5) a mixture of at least two of the aforementioned monomers (2.1) to (2.4); the copolymeric polyisoprenes containing between 20 and 99% by weight of isoprenic units and between 80 and 1% by weight of diene units, aromatic vinyls, vinyl nitriles and / or acrylic esters, and consisting, for example, in poly (isoprene-butadiene) ), poly (isoprene-styrene) and poly (isoprene-butadiene-styrene);

(3) natural rubber;

(4) copolymers obtained by copolymerization of isobutene and isoprene, as well as the halogenated versions, in particular chlorinated or brominated, of these copolymers;

(5) a mixture of at least two of the aforementioned elastomers (1) to (4);

(6) a mixture containing more than 50% (preferably less than 99.5%, and for example 70-99%) by weight of the aforementioned elastomer (1) or (3) and less than 50% (preferably more than 0.5%, and for example between 1 and 30%) by weight of one or more diene elastomers other than isoprenic.

By diene elastomer other than isoprene, is meant in a manner known per se including: homopolymers obtained by polymerization of one of the conjugated diene monomers defined above in (2.1), such as polybutadiene and polychloroprene; copolymers obtained by copolymerization of at least two of the abovementioned conjugated dienes (2.1) with one another or by copolymerization of one or more of the abovementioned conjugated dienes (2.1) with one or more unsaturated monomers mentioned above (2.2), (2.3) and / or or (2.4), such as poly (butadiene-styrene) and poly (butadiene-acrylonitrile); ternary copolymers obtained by copolymerization of ethylene, of an α-olefin having from 3 to 6 carbon atoms with a non-conjugated diene monomer containing from 6 to 12 carbon atoms, for example elastomers obtained from ethylene propylene with a non-conjugated diene monomer of the aforementioned type, such as in particular hexadiene-1,4, ethylidene norbornene, dicyclopentadiene (elastomer EPDM).

Preferably, the elastomer composition (s) comprises at least one isoprene elastomer chosen from:

(1) homopolymeric synthetic polyisoprenes;

(2) the synthetic polyisoprenes copolymers consisting of poly (isoprene-butadiene), poly (isoprene-styrene) and poly (isoprene-butadiene-styrene);

(3) natural rubber;

(4) butyl rubber;

(5) a mixture of at least two of the aforementioned elastomers (1) to (4);

(6) a mixture containing more than 50% (preferably less than 99.5%, and for example 70-99%) by weight of the aforementioned elastomer (1) or (3) and less than 50% (preferably more than 0.5%, and for example from 1 to 30% by weight of non-isoprene diene elastomer consisting of polybutadiene, polychloroprene, polybutadiene-styrene, polybutadiene-acrylonitrile or a terpolymer (ethylene - propylene - nonconjugated monomeric diene). More preferentially, the elastomer composition (s) comprises at least one isoprene elastomer chosen from: (1) homopolymeric synthetic polyisoprenes; (3) natural rubber; (5) a mixture of the aforementioned elastomers (1) and (3); (6) a mixture containing more than 50% (preferably less than 99.5%, and for example 70-99%) by weight of the aforementioned elastomer (1) or (3) and less than 50% (preferably more than 0.5%, for example from 1 to 30% by weight of diene elastomer other than isoprene, consisting of polybutadiene or polybutadiene-styrene.

According to a very preferred variant of the invention, the elastomer composition (s) comprises as isoprene elastomer at least natural rubber, or even only natural rubber.

According to an even more preferred variant, the elastomer composition (s) comprises as elastomer (s) only natural rubber. In general, the elastomer composition (s) used according to the invention also comprises all or part of the other constituents and auxiliary additives usually employed in the field of elastomeric compositions.

Thus, generally, it comprises at least one compound chosen from vulcanizing agents (for example sulfur or a sulfur-donor compound (such as a thiuram derivative)), vulcanization accelerators (for example a guanidine derivative or a thiazole derivative), vulcanization activators (for example, stearic acid, zinc stearate and zinc oxide, which may optionally be introduced in a fractional manner during the preparation of the composition), carbon, protective agents (especially antioxidants and / or antiozonants, such as for example N-phenyl-N '- (1,3-dimethylbutyl) -p-phenylenediamine), antireversions (such as for example hexamethylene-1,6-bis (thiosulfate), 1,3-bis (citraconimidomethyl) benzene), plasticizers. The joint use according to the invention of the silica described in the previous discussion and 3-acryloxypropyltriethoxysilane can be done more particularly in shoe soles, floor coverings, gas barriers, flame retardant materials, rollers of cable cars, the appliance seals, liquid or gas line seals, brake system seals, hoses, ducts (especially cable ducts), cables, motor mounts, conveyor, transmission belts or, preferably, tires (especially tire treads), advantageously in tires for heavy goods vehicles, in particular for trucks.

The elastomer composition (s) obtained according to the use according to the invention contains an effective amount of 3-acryloxypropyltriethoxysilane.

More particularly, the elastomer compositions resulting from the invention may comprise (parts by weight), per 100 parts of isoprene elastomer (s):

10 to 200 parts, in particular 20 to 150 parts, especially 30 to 1 part, for example 30 to 75 parts, of silica as described above and used as reinforcing inorganic filler;

1 to 20 parts, in particular 2 to 20 parts, especially 2 to 12 parts, for example 2 to 10 parts, of 3-acryloxypropyltriethoxysilane used as reinforcing inorganic filler-elastomer coupling agent.

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

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

The present invention has the second object the elastomer compositions (s) described above, and thus comprising:

at least one isoprene elastomer, at least one reinforcing inorganic filler,

at least one inorganic filler - elastomer coupling agent,

characterized in that said reinforcing inorganic filler and said inorganic filler-elastomer coupling agent are as defined above according to the first subject of the invention, that is to say that said reinforcing inorganic filler is silica as described in the above disclosure and said inorganic filler-elastomer coupling agent is 3-acryloxypropyltriethoxysilane.

All that has been previously described in the context of the use according to the first subject of the invention applies to these elastomer compositions (s).

In particular, these compositions may further comprise at least one covering agent for said silica used as a reinforcing filler.

The elastomer compositions according to the invention may be prepared according to any conventional two-phase procedure. A first phase (called non-productive) is a thermomechanical work phase at high temperature. It is followed by a second phase of mechanical work (called productive) at temperatures generally below 110 ° C in which the vulcanization system is introduced. The invention, taken in its second object, relates to elastomer compositions (s) both in the raw state (that is to say before cooking) and in the cooked state (that is to say, before cooking). say after crosslinking or vulcanization).

The elastomer compositions according to the invention can be used to manufacture finished or semi-finished articles comprising said compositions.

The present invention thus has for third object articles comprising at least one elastomer composition (s) as defined above, in particular comprising (for example as sole elastomer) natural rubber, these articles consisting of shoe soles , floor coverings, gas barriers, fire-retardant materials, ropeway rollers, appliance joints, liquid or gas line joints, brake system seals, (flexible) hoses, sheaths (including cable sheaths), cables, motor mounts, conveyor belts, transmission belts, or, preferably, tires (especially tire treads), advantageously tires for heavy goods vehicles, in particular for trucks.

The following example illustrates the invention without limiting its scope. EXAMPLE This example illustrates the use and behavior of a precipitated silica S, as recommended by the invention, and 3-acryloxypropyltriethoxysilane in an elastomeric composition.

1- The precipitated silica S has the following characteristics:

CTAB surface area 204 m ² / g

- BET specific surface 212 m ² / g

- width Ld (XDC)> 0.91

- V (d5 - d50 / V (d5 - d100)> 0.66

- porous distribution width Idp> 0.70

- aluminum content by weight <0,5%

2- In an internal mixer of the Haake type, elastomeric compositions are prepared whose constitution, expressed in part by weight per 100 parts of elastomers (phr), is shown in Table I below.

Table I: Formulations used for blends

(1) Natural rubber SMR 5 - CV60 (supplied by Safic-Alcan)

(2) Silica S

(3) TESPT (Z-6940 from Dow Corning Company)

(4) 3-acryloxypropyltriethoxysilane

(5) N-1,3-dimethylbutyl-N-phenyl-para-phenylenediamine (Santoflex

6-PPD from Flexsys)

(6) 2,2,4-trimethyl-1H-quinoline (Permanax TQ from Flexsys)

(7) N-cyclohexyl-2-benzothiazyl sulfenamide (Rhenogran CBS-80 from

RheinChemie company)

(8) Diphenylguanidine (Rhenogran DPG-80 from RheinChemie)

Process for the preparation of elastomeric compositions

The process for preparing the compositions is conducted in two successive preparation phases. A first phase consists in a thermomechanical work phase at high temperature. It is followed by a second phase of mechanical work at temperatures below 110 ° C; this phase allows the introduction of the vulcanization system. The first phase is carried out in a Haake-type internal mixer (300 ml capacity). The fill factor is 0.75. The initial temperature and the speed of the rotors are fixed each time so as to reach mixing temperatures of the vicinity of 150-170 ° C.

The first phase is decomposed here in two passes.

It allows to incorporate, in a first pass, the elastomer (natural rubber), then the reinforcing inorganic filler consisting of silica (fractional introduction) with the coupling agent and stearic acid; the duration of this pass is between 4 and 10 minutes.

After cooling the mixture (temperature below 100 ° C.), a second pass makes it possible to incorporate the zinc oxide and the protective / antioxidant agents (6-PPD in particular); the duration of this pass is between 2 and 5 minutes.

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

Each final mixture is then calendered in the form of plates 2-3 mm thick.

On these so-called raw mixtures obtained, an evaluation of their rheological properties makes it possible to optimize the duration and the vulcanization temperature.

Then, the mechanical and dynamic properties of the optimum vulcanized mixtures are measured. Rheological properties

- Viscosity of raw mixtures

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

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

The measurements are performed on the compositions in the green state. The results relating to the rheology test, which is conducted at 150 ° C. using a Monsanto ODR rheometer according to the NF ISO 3417 standard, are shown in Table III.

According to this test, the composition to be tested is placed in the controlled test chamber at a temperature of 150 ° C. for 30 minutes, and the resistive torque opposed by the composition is measured at a low amplitude oscillation (3 °). a biconical rotor included in the test chamber, the composition completely filling the chamber in question.

From the curve of variation of the torque as a function of time, we determine:

the minimum torque (Cmin), which reflects the viscosity of the composition at the temperature considered;

- the maximum torque (Cmax);

- the delta-torque (ΔΟ = Cmax - Cmin);

the roasting time TS2 corresponding to the time required to have a rise of 2 points above the minimum torque at the temperature in question (150 ° C.) and reflecting the time during which it is possible to use the raw mixtures with this temperature without initiation of vulcanization (the mixture cures from TS2).

The results obtained are shown in Table II.

Table II

It is found that the composition resulting from the invention (composition I) has a satisfactory set of rheological properties. In particular, while having an acceptable flood viscosity, it has lower minimum and maximum torque values than those of the control composition, which reflects greater ease of use of the mixture prepared.

And the composition resulting from the invention (composition I) has a good vulcanization kinetics (TS2), and without penalizing the viscosity of the raw mixture (illustrated in particular by the minimum torque).

Mechanical properties of vulcanizates

The measurements are carried out on the compositions vulcanized at the optimum (that is to say at a state of vulcanization corresponding to 98% of the complete vulcanization) for a temperature of 150 ° C.

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

The measurement of loss of mass by abrasion is carried out according to the indications of standard NF ISO 4649, using a Zwick abraser where the cylindrical specimen is subjected to the action of an abrasive cloth of grains P60 and fixed on the surface of a drum rotating under a contact pressure of 10 N and a stroke of 40 m. The measured value is a volume of loss of substance (in mm ³ ) after wear by abrasion; the lower it is, the better the resistance to abrasion.

The measured properties are collated in Table III. Table III

It is found that the composition resulting from the invention (composition I) has a good compromise of mechanical properties compared to what is obtained with the control composition.

The composition I thus has relatively low 10% and 100% modules and a relatively high 300% modulus, hence a higher reinforcement index.

In addition, the composition I has a lower abrasion loss, that is to say a better resistance to abrasion, hence a gain in wear resistance, which is important in pneumatic application, in particular for heavy goods vehicles.

Dynamic properties of vulcanizates

Dynamic properties are measured on a viscoanalyzer (Metravib VA3000) according to ASTM D5992.

In a first series of measurements, the values of loss factor (tan δ) and complex modulus in dynamic compression (E *) are recorded on vulcanized samples (cylindrical specimen of section 95 mm ² and height 14 mm). The sample is initially subjected to a predeformation of 10%. then to a sinusoidal deformation in alternating compression of +/- 2%. The measurements are carried out at 60 ° C. and at a frequency of 10 Hz.

The results, presented in Table IV, are thus the complex modulus in compression (E * - 60 ° C - 10 Hz) and the loss factor (tan δ - 60 ° C - 10 Hz).

In a second series of measurements, the values of the loss factor (tan δ) and elastic modulus in dynamic shear (G ¹ ) are recorded on vulcanized samples (parallelepipedal test specimen with section 8 mm ² and height 7 mm). The sample is subjected to an alternating double shear sinusoidal deformation at a temperature of 40 ° C. and at a frequency of 10 Hz. The amplitude-deformation sweep processes are carried out in a round-trip cycle, ranging from 0.degree. 1 to 50% then return 50 to 0.1%.

The results, presented in Table IV, are derived from the amplitude sweep of the return strains and relate to the maximum value of the loss factor (tan δ max return - 40 ° C - 10 Hz) as well as the amplitude of the elastic modulus ( AG ^* - 40 ° C - 10 Hz) between the values at 0.1% and 50% deformation (Payne effect).

Table IV

The composition resulting from the invention (composition I) has good dynamic properties (hysteretic properties at 60 ° C.), especially with respect to the control composition.

It can be seen from the results of Tables II to IV that the composition resulting from the invention (Composition I) has a good compromise of properties.

Claims

CLAIMS 1- Use in a composition of elastomer(s), comprising at least one isoprene elastomer: - of a silica, as a reinforcing inorganic filler, said silica having: . a CTAB specific surface area of between 40 and 525 m2/g, in particular between 80 and 290 m2/g,. a BET specific surface area of between 45 and 550 m2/g, in particular between 90 and 320 m2/g,. a width Ld ((d84 - d16)/d50) of object size distribution measured by XDC particle size after ultrasonic deagglomeration of at least 0.91, and. a distribution of the pore volume such that the ratio V(d5 - d50) (d5 - dioo) is at least 0.66, with - 3-acryloxy-propyltriethoxysilane, as inorganic filler - elastomer coupling agent. 2- Use in a composition of elastomer(s), comprising at least one isoprene elastomer: - of a silica, as a reinforcing inorganic filler, said silica having: . a CTAB specific surface area of between 40 and 525 m2/g, in particular between 80 and 290 m2/g,. a BET specific surface area of between 45 and 550 m2/g, in particular between 90 and 320 m2/g, and - a porous distribution width Idp greater than 0.70, with - 3-acryloxy-propyltriethoxysilane, as coupling agent inorganic filler - elastomer. 3- Use according to claim 2, characterized in that said silica has a width Ld ((d84 - d16)/d50) of object size distribution measured by XDC particle size after ultrasonic deagglomeration of at least 0, 91. 4- Use in a composition of elastomer(s), comprising at least one isoprene elastomer: - of a silica, as a reinforcing inorganic filler, said silica having: . a CTAB specific surface area of between 40 and 525 m2/g, in particular between 80 and 290 m2/g,. a BET specific surface area of between 45 and 550 m2/g, in particular between 90 and 320 m2/g,. a width L'd ((d84 - d16)/d50) of object size distribution less than 500 nm, measured by XDC particle size after ultrasonic deagglomeration, of at least 0.95 and . a distribution of the pore volume such that the ratio V(d5 - d50) (d5 - dioo) is at least 0.71, with - 3-acryloxy-propyltriethoxysilane, as inorganic filler - elastomer coupling agent. 5- Use in a composition of elastomer(s), comprising at least one isoprene elastomer: - of a silica, as a reinforcing inorganic filler, said silica having: . a CTAB specific surface area of between 40 and 525 m2/g, in particular between 80 and 290 m2/g,. a BET specific surface area of between 45 and 550 m2/g, in particular between 90 and 320 m2/g,. a width L'd ((d84 - d16)/d50) of object size distribution less than 500 nm, measured by XDC particle size after ultrasonic deagglomeration, of at least 0.90, and. a distribution of the pore volume such that the ratio V(d5. d5o V(d5 - dioo) is at least 0.74, with - 3-acryloxy-propyltriethoxysilane, as inorganic filler - elastomer coupling agent. 6- Use according to one of claims 1 to 5, in particular according to one of claims 1 to 3, characterized in that said silica has a CTAB specific surface area of between 170 and 270 m2/g, in particular between 180 and 240 m2/ g, in particular between 190 and 210 m2/g. 7- Use according to one of claims 1 to 6, characterized in that said silica has a BET specific surface area of between 180 and 290 m2/g, in particular between 190 and 260 m2/g, in particular between 200 and 240 m2/g. 8- Use according to one of claims 1 to 7, characterized in that said silica has an aluminum content of less than 0.5% by weight, preferably less at 0.35% by weight, in particular less than 0.2% by weight. 9- Use according to one of claims 1 to 8, characterized in that said silica is in the form of substantially spherical beads, preferably of average size of at least 80 Mm. 10- Use according to one of claims 1 to 9, characterized in that said silica is obtained by a process comprising the reaction of a silicate with an acidifying agent, whereby one obtains a suspension of silica, then the separation and drying of this suspension, in which the reaction of the silicate with the acidifying agent is carried out according to the following successive stages: (i) an aqueous base is formed having a pH between 2 and 5, preferably between 2.5 and 5, (ii) silicate and the acidifying agent are added to said stock, simultaneously, in such a way that the pH of the reaction medium is maintained between 2 and 5, preferably between 2.5 and 5, (iii) the addition of the acidifying agent is stopped while continuing the addition of silicate into the reaction medium until a pH value of the reaction medium is obtained between 7 and 10, preferably between 7.5 and 9.5, (iv) silicate and the acidifying agent are added to the reaction medium, simultaneously, in such a way that the pH of the reaction medium is maintained between 7 and 10, preferably between 7.5 and 9.5, (v) the addition of the silicate is stopped while continuing the addition of the acidifying agent into the reaction medium until a pH value is obtained of the reaction medium less than 6. 1 1- Use according to one of claims 1 to 10, characterized in that the quantity used of 3-acryloxy-propyltriethoxysilane represents from 1 to 20%, in particular from 2 to 15%, per relative to the quantity used of said silica. 12- Use according to one of claims 1 to 11, characterized in that said silica and 3-acryloxy-propyltriethoxysilane are mixed beforehand. 13- Use according to one of claims 1 to 12, characterized in that said composition of elastomer(s) further comprises at least one covering agent for said silica, optionally previously mixed with said silica and 3-acryloxy- propyltriethoxysilane. 14- Use according to one of claims 1 to 13, characterized in that said elastomer(s) composition does not comprise another inorganic filler - elastomer coupling agent. 15- Use according to one of claims 1 to 14, in the absence of free radical initiator. 16- Use according to one of claims 1 to 15, characterized in that said composition of elastomer(s) does not comprise any elastomers other than said isoprene elastomer(s). 17- Use according to one of claims 1 to 15, characterized in that said composition of elastomer(s) comprises at least one isoprene elastomer and at least one diene elastomer other than isoprene, the quantity of elastomer(s) isoprene(s) relative to the total quantity of elastomer(s) being preferably greater than 50% by weight. 18- Use according to one of claims 1 to 17, characterized in that said composition of elastomer(s) comprises at least one isoprene elastomer chosen from: (1) synthetic polyisoprenes obtained by homopolymerization of isoprene or methyl -2 butadiene-1,3; (2) synthetic polyisoprenes obtained by copolymerization of isoprene with one or more ethylenically unsaturated monomers chosen from: (2.1) conjugated diene monomers, other than isoprene, having 4 to 22 carbon atoms; (2.2) vinyl aromatic monomers having 8 to 20 carbon atoms; (2.3) vinyl nitrile monomers having 3 to 12 carbon atoms; (2.4) acrylic ester monomers derived from acrylic acid or methacrylic acid with alkanols having 1 to 12 carbon atoms; (2.5) a mixture of at least two of the aforementioned monomers (2.1) to (2.4); copolymer polyisoprenes containing between 20 and 99% by weight of isoprene units and between 80 and 1% by weight of diene units, aromatic vinyls, vinyl nitriles and/or acrylic esters; (3) natural rubber; (4) copolymers obtained by copolymerization of isobutene and isoprene, as well as halogenated versions of these copolymers; (5) a mixture of at least two of the aforementioned elastomers (1) to (4); (6) a mixture containing more than 50% by weight of the aforementioned elastomer (1) or (3) and less than 50% by weight of one or more diene elastomers other than isoprene. 19- Use according to claim 18, characterized in that said composition of elastomer(s) comprises at least one isoprene elastomer chosen from: (1) homopolymeric synthetic polyisoprenes; (2) synthetic polyisoprene copolymers consisting of poly(isoprene-butadiene), pply(isoprene-styrene) and poly(isoprene-butadiene-styrene); (3) natural rubber; (4) butyl rubber; (5) a mixture of at least two of the aforementioned elastomers (1) to (4); (6) a mixture containing more than 50% by weight of the aforementioned elastomer (1) or (3) and less than 50% by weight of diene elastomer other than isoprene consisting of polybutadiene, polychloroprene, poly(butadiene -styrene), poly(butadiene-acrylonitrile) or a terpolymer. 20- Use according to one of claims 1 to 19, characterized in that said composition of elastomer(s) comprises as isoprene elastomer at least natural rubber, preferably said composition of elastomer(s) comprising title of elastomer(s) only natural rubber. 21- Use according to one of claims 1 to 20, characterized in that said composition of elastomer(s) further comprises at least one compound chosen from vulcanization agents, vulcanization accelerators, vulcanization activators, carbon black, protective agents, plasticizing agents. 22- Use according to one of claims 1 to 21 in shoe soles, floor coverings, gas barriers, flame retardant materials, cable car rollers, household appliance joints, liquid pipe joints or gas, brake system seals, pipes, ducts, cables, engine mounts, conveyor belts, transmission belts or, preferably, tires. 23- Use according to one of claims 1 to 22 in a tire for heavy goods vehicles, in particular for trucks. 24- Composition of elastomer(s) comprising: - at least one isoprene elastomer, - at least one reinforcing inorganic filler, - at least one inorganic filler - elastomer coupling agent, characterized in that said inorganic filler - elastomer coupling agent is 3-acryloxy-propyltriethoxysilane, said reinforcing inorganic filler and said inorganic filler - elastomer coupling agent being as defined in one of claims 1 to 10. 25- Composition according to claim 24, characterized in that the quantity of 3-acryloxy-propyltriethoxysilane represents from 1 to 20%, in particular from 2 to 15%, relative to the quantity of said silica. 26- Composition according to one of claims 24 and 25, characterized in that said silica and 3-acryloxy-propyltriethoxysilane are previously mixed together. 27- Composition according to one of claims 24 to 26, characterized in that said composition further comprises at least one covering agent for said silica, optionally previously mixed with said silica and 3-acryloxy-propyltriethoxysilane. 28- Composition according to one of claims 24 to 27, characterized in that said composition does not comprise another inorganic filler - elastomer coupling agent. 29- Composition according to one of claims 24 to 28, characterized in that said composition does not comprise a free radical initiator. 30- Composition according to one of claims 24 to 29, characterized in that said composition does not comprise any elastomers other than said isoprene elastomer(s). 31- Composition according to one of claims 24 to 29, characterized in that said composition comprises at least one isoprene elastomer and at least one diene elastomer other than isoprene, the quantity of isoprene elastomer(s) relative to to the total quantity of elastomer(s) being preferably greater than 50% by weight. 32- Composition according to one of claims 24 to 31, characterized in that said composition comprises at least one isoprene elastomer chosen from: (1) synthetic polyisoprenes obtained by homopolymerization of isoprene or 2-methyl-1-butadiene, 3; (2) synthetic polyisoprenes obtained by copolymerization of isoprene with one or more ethylenically unsaturated monomers chosen from: (2.1) conjugated diene monomers, other than isoprene, having 4 to 22 carbon atoms; (2.2) vinyl aromatic monomers having 8 to 20 carbon atoms; (2.3) vinyl nitrile monomers having 3 to 12 carbon atoms; (2.4) acrylic ester monomers derived from acrylic acid or methacrylic acid with alkanols having 1 to 12 carbon atoms; (2.5) a mixture of at least two of the aforementioned monomers (2.1) to (2.4); copolymer polyisoprenes containing between 20 and 99% by weight of isoprene units and between 80 and 1% by weight of diene units, aromatic vinyls, vinyl nitriles and/or acrylic esters; (3) natural rubber; (4) copolymers obtained by copolymerization of isobutene and isoprene, as well as halogenated versions of these copolymers; (5) a mixture of at least two of the aforementioned elastomers (1) to (4); (6) a mixture containing more than 50% by weight of the aforementioned elastomer (1) or (3) and less than 50% by weight of one or more diene elastomers other than isoprene. 33- Composition according to claim 32, characterized in that said composition comprises at least one isoprene elastomer chosen from:

(1) homopolymer synthetic polyisoprenes;

(2) synthetic polyisoprene copolymers consisting of poly(isoprene-butadiene), poly(isoprene-styrene) and poly(isoprene-butadiene-styrene);

(3) natural rubber;

(4) butyl rubber;

(5) a mixture of at least two of the aforementioned elastomers (1) to (4);

(6) a mixture containing more than 50% by weight of the aforementioned elastomer (1) or (3) and less than 50% by weight of diene elastomer other than isoprene consisting of polybutadiene, polychloroprene, poly(butadiene -styrene), poly(butadiene-acrylonitrile) or a terpolymer.

34- Composition according to one of claims 24 to 33, characterized in that said composition comprises, as isoprene elastomer, at least natural rubber, preferably said composition of elastomer(s) comprising, as elastomer(s), ) only natural rubber.

35- Composition according to one of claims 24 to 34, characterized in that said composition further comprises at least one compound chosen from vulcanization agents, vulcanization accelerators, vulcanization activators, carbon black, agents protectors, anti-reversion agents, plasticizing agents. 36- Article comprising at least one composition according to one of claims 24 to 35, this article consisting of a shoe sole, a floor covering, a gas barrier, a flame retardant material, a cable car roller, a gasket household appliances, a joint of liquid or gas pipes, a brake system seal, a pipe, a sheath, a cable, an engine support, a conveyor belt, a transmission belt or, preferably, a tire. 37- Tire according to claim 36 for heavy goods vehicles, in particular for trucks.