WO2019106292A1 - Rubber composition, the crosslinking system of which comprises a blend of peroxides and an acrylate derivative - Google Patents

Abstract

The invention relates to a rubber composition providing an improved compromise between stiffness and hysteresis, said composition being based on at least one diene elastomer, a specific acrylate derivative, and two peroxides, of which the temperatures required to reach their half-life at the end of one hour differ by at least 10 °C. Also disclosed is a tire comprising the composition.

Description

 RUBBER COMPOSITION HAVING THE CROSSLINKING SYSTEM INCLUDING PEROXIDE CUTTING AND ACRYLATE DERIVATIVE

The invention relates to rubber compositions comprising an acrylate derivative and a peroxide, intended in particular for the manufacture of tires or semi-finished products for tires.

Such compositions are described in certain documents of the state of the art, for objects which are not tires or do not enter into their composition. For example, US 2003/0065076 discloses military tank track compositions comprising an elastomer, a reinforcing filler, zinc diacrylate or zinc dimethacrylate, and a peroxide; with the effect of improving the resistance to abrasion. Similarly, US 2005/0084638 discloses coating mix compositions of an air sleeve for suspensions, also comprising an elastomer, a reinforcing filler, zinc diacrylate and a peroxide.

More recently, in the specific field of tires and more particularly of their inner layers, the documents WO 2016/139285 and WO 2016/102480 propose compositions comprising acrylate derivatives, a peroxide and a low level of reinforcing filler to improve both rolling resistance and aging resistance in thermal and thermo-oxidative conditions.

Continuing its research, the Applicant has surprisingly discovered that the use of a particular blend of peroxides in such compositions makes it possible, unexpectedly, to further improve the rolling resistance, while maintaining a satisfactory rigidity, or even improving the expected rigidity of these compositions. The Applicant has further found that the compositions according to the invention can improve the kinetics of cooking, which is particularly advantageous from an industrial point of view.

Thus, the subject of the present invention is in particular a composition based on at least:

 a diene elastomer,

 a first peroxide whose temperature required to reach its half-life after one hour is denoted Tl, said slow peroxide,

 a second peroxide whose temperature necessary to reach its half-life after one hour is noted T2, said fast peroxide,

 an acrylate derivative of formula (I):

[X] _P A (i)

in which : o [X] p corresponds to a radical of formula (II):

 in which,

^■ R, R ₂ and R ₃ independently represent a hydrogen atom or a hydrocarbon group-C ₈ selected from the group consisting of linear alkyl groups, branched or cyclic, alkylaryl groups, aryl groups and aralkyl, and optionally interrupted by one or more heteroatoms, R ₂ and R ₃ may together form a non-aromatic ring,

^■ (*) represents the point of attachment of the radical of formula (II) A, where A represents an atom belonging to the group consisting of alkaline earth metals or transition metals, a carbon atom, a hydrocarbon group C 1 -C ₃₀ optionally interrupted and / or substituted with one or more heteroatoms, or a group comprising from 2 to 30 monomer units, the monomeric units being chosen from the group consisting of epoxide, ester, ether, amine, acrylic monomer units, siloxanes and urethanes,

 o A comprising p valences free, p having a value ranging from 1 to 20, o being understood that the 1 to 20 radicals X are identical or different, preferably:

A represents an atom belonging to the group consisting of alkaline earth metals or transition metals, a carbon atom or a C ₁ -C ₈ hydrocarbon group,

o A comprising p free valences, p having a value ranging from 2 to 4, o being understood that the 2 to 4 radicals X are identical or different, composition in which the temperature T1 is greater than T2 and the difference between T1 and T2 is at least 10 ° C, and wherein the ratio of the so-called slow peroxide level to the so-called fast peroxide level is in a range from 10/90 to 70/30. The subject of the invention is also a finished or semi-finished rubber article comprising this rubber composition and a tire comprising this rubber composition or this semi-finished rubber article.

The invention as well as its advantages will be readily understood in the light of the description and the following exemplary embodiments.

I- DEFINITIONS

 By the expression "part by weight per hundred parts by weight of elastomer" (or phr) is meant for the purposes of the present invention, the part, by mass per hundred parts by weight of elastomer or rubber.

In the present, unless expressly indicated otherwise, all the percentages (%) indicated are percentages (%) by mass.

On the other hand, any range of values designated by the expression "between a and b" represents the range of values from more than a to less than b (i.e. terminals a and b excluded) while any range of values designated by the term "from a to b" means the range from a to b (i.e., including the strict limits a and b). In the present invention, when a range of values is designated by the expression "from a to b", the interval represented by the expression "between a and b" is also designated and preferentially.

As used herein, "composition based on" is understood to mean a composition comprising the mixture and / or the reaction product of the various constituents used, some of these basic constituents being capable of or intended to react between they, at least in part, during the various phases of manufacture of the composition, in particular during its crosslinking or vulcanization. By way of example, a composition based on an elastomeric and sulfur matrix comprises the elastomeric matrix and the sulfur before firing, whereas after firing the sulfur is no longer detectable because the latter has reacted with the elastomeric matrix in forming sulfur bridges (polysulfides, disulfides, mono-sulphide).

When reference is made to a "majority" compound, in the sense of the present invention, it is understood that this compound is predominant among the compounds of the same type in the composition, that is to say that it is the one which represents the largest amount by mass among the compounds of the same type, for example more than 50%, 60%, 70%, 80%, 90% or even 100% by weight relative to the total weight of the type of compound. Thus, for example, a majority reinforcing filler is the reinforcing filler representing the largest mass relative to the total weight of the reinforcing fillers in the composition. the Conversely, a "minor" compound is a compound that does not represent the largest mass fraction among compounds of the same type, for example less than 50%, 40%, 30%, 20%, 10% or less.

In the context of the invention, the carbonaceous products mentioned in the description may be of fossil origin or biobased. In the latter case, they can be, partially or totally, derived from biomass or obtained from renewable raw materials derived from biomass. These include polymers, plasticizers, fillers, etc.

II- DESCRIPTION OF THE INVENTION

 11-1 Diene Elastomer

 The rubber compositions of the tire of the invention may contain a single diene elastomer or a mixture of several diene elastomers.

By elastomer (or "rubber", the two terms being considered synonymous) of the "diene" type, it will be recalled here that it is to be understood in known manner that one or more elastomers derived from at least a part (ie, a homopolymer or copolymer) of diene monomers (monomers bearing two carbon-carbon double bonds, conjugated or otherwise).

The diene elastomers can be classified into two categories: "essentially unsaturated" or "essentially saturated". The term "essentially unsaturated" is generally understood to mean a diene elastomer derived at least in part from conjugated diene monomers, having a level of units or units of diene origin (conjugated dienes) which is greater than 15% (mol%); Thus, diene elastomers such as butyl rubbers or copolymers of dienes and alpha-olefins of the EPDM type do not fall within the above definition and may in particular be described as "essentially saturated" diene elastomers ( low or very low diene origin, always less than 15%). In the category of "essentially unsaturated" diene elastomers, the term "highly unsaturated" diene elastomer is particularly understood to mean a diene elastomer having a content of units of diene origin (conjugated dienes) which is greater than 50%.

These definitions being given, the term "diene elastomer" can be understood more particularly to mean the rubber compositions of the tire according to the invention: a) any homopolymer obtained by polymerization of a conjugated diene monomer having from 4 to 12 carbon atoms ; b) any copolymer obtained by copolymerization of one or more conjugated dienes with each other or with one or more vinyl aromatic compounds having from 8 to 20 carbon atoms;

 c) a ternary copolymer obtained by copolymerization of ethylene, an α-olefin having 3 to 6 carbon atoms with a non-conjugated diene monomer having from 6 to 12 carbon atoms, for example elastomers obtained from ethylene, propylene with a non-conjugated diene monomer of the aforementioned type such as in particular 1,4-hexadiene, ethylidene norbornene, dicyclopentadiene;

 d) a copolymer of isobutene and isoprene (butyl rubber), as well as the halogenated versions, in particular chlorinated or brominated, of this type of copolymer.

Although it applies to any type of diene elastomer, the person skilled in the tire art will understand that the present invention is preferably implemented with essentially unsaturated diene elastomers, in particular of the type (a) or (b). ) above.

As conjugated dienes 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-di (C ₁ -C ₅ alkyl) -1,3-butadienes, such as for example 2,3-dimethyl-1,3-butadiene, 2,3-diethyl-1,3-butadiene, 2-methyl-3-ethyl-1,3-butadiene, 2-methyl-3-isopropyl-1 3-butadiene, aryl-1,3-butadiene, 1,3-pentadiene, 2,4-hexadiene. Suitable vinylaromatic compounds are, for example, styrene, ortho-, meta-, para-methylstyrene, the "vinyl-toluene" commercial mixture, para-tertiarybutylstyrene, methoxystyrenes, chlorostyrenes, vinylmesitylene, divinylbenzene, vinylnaphthalene.

The copolymers may contain between 99% and 20% by weight of diene units and between 1% and 80% by weight of vinylaromatic units. The elastomers may have any microstructure which is a function of the polymerization conditions used, in particular the presence or absence of a modifying and / or randomizing agent and the amounts of modifying and / or randomizing agent used. The elastomers can be for example block, statistical, sequenced, microsequenced, and be prepared in dispersion or in solution; they may be coupled and / or starred or functionalized with a coupling agent and / or starring or functionalization. For coupling with carbon black, there may be mentioned, for example, functional groups comprising a C-Sn bond or amine functional groups such as aminobenzophenone for example; for coupling to a reinforcing inorganic filler such as silica, mention may be made, for example, of silanol or polysiloxane functional groups having a silanol end (as described, for example, in FR 2,740,778, US 6,013,718 and WO 2008/141702), groups alkoxysilane (as described for example in FR 2 765 882 or US Pat. No. 5,977,238), carboxylic groups (as described for example in WO 01/92402 or US Pat. No. 6,815,473, WO 2004/096865 or US 2006/0089445) or else polyether groups (as described for example in EP 1 127 909, US 6,503,973, WO 2009/000750 and WO 2009/000752). As other examples of functionalized elastomers, mention may also be made of elastomers (such as SBR, BR, NR or IR) of the epoxidized type.

In summary, the diene elastomer of the composition is preferably chosen from the group of highly unsaturated diene elastomers consisting of polybutadienes (abbreviated "BR"), synthetic polyisoprenes (IR), natural rubber (NR), copolymers butadiene, isoprene copolymers and mixtures of these elastomers. Such copolymers are more preferably selected from the group consisting of butadiene-styrene copolymers (SBR), isoprene-butadiene copolymers (BIR), isoprene-styrene copolymers (SIR), isoprene-copolymers butadiene-styrene (SBIR), butadiene-acrylonitrile copolymers (NBR), butadiene-styrene-acrylonitrile copolymers (NSBR) or a mixture of two or more of these compounds.

Advantageously, the diene elastomer comprises predominantly at least one isoprene elastomer. By "isoprene elastomer" is meant in known manner a homopolymer or copolymer of isoprene, in other words an isoprene elastomer chosen from the group comprising or consisting of natural rubber (NR), which can be plasticized or peptized, the synthetic polyisoprenes (IR), the various isoprene copolymers and the mixtures of these elastomers. Among the isoprene copolymers, mention will in particular be made of copolymers of isobutene-isoprene (butyl rubber IIR), isoprene-styrene (SIR), isoprene-butadiene (BIR) or isoprene-butadiene-styrene ( SBIR).

The isoprene elastomer is preferably selected from the group consisting of natural rubber, synthetic polyisoprenes and mixtures thereof. Among these synthetic polyisoprenes, polyisoprenes having a level (mol%) of 1,4-cis bonds greater than 90%, more preferably still greater than 98%, are preferably used. More preferably, the diene elastomer is natural rubber.

Preferably, the level of diene elastomer, preferably of isoprene elastomer, preferably natural rubber, is 50 to 100 phr, more preferably 60 to 100 phr, more preferably 70 to 100 phr, more preferentially 80 to 100 phr and very preferably 90 to 100 phr. In particular, the level of diene elastomer, preferably of elastomer isoprene, more preferably natural rubber, is very preferably 100 phr.

Whether it contains a single diene elastomer or a mixture of several diene elastomers, the rubber composition according to the invention may also contain, in a minority manner, any type of synthetic elastomer other than diene, or even with polymers other than elastomers, by example of thermoplastic polymers. Preferably, the rubber composition according to the invention contains no synthetic elastomer other than diene or polymer other than elastomers or contains less than 10 phr, preferably less than 5 phr.

11-2 Crosslinking system

 11-2-1 Peroxide

 According to the invention, the rubber composition comprises two peroxides. The peroxides used in the composition according to the invention may all be peroxides known to those skilled in the art.

For the purposes of the invention, it is necessary that the composition is at the base of at least a first peroxide whose temperature required to reach its half-life after one hour is denoted Tl, said slow peroxide, and a second peroxide whose temperature required to reach its half-life after one hour is noted T2, said fast peroxide, the temperature T1 being greater than T2 and the difference between T1 and T2 being at least 10 ° C. In other words, the composition according to the invention is based on at least two peroxides, the temperatures necessary to reach their half-life after one hour have at least a difference of 10 ° C.

In addition, the ratio of the so-called slow peroxide level to the so-called rapid peroxide content in the composition according to the invention should advantageously be in a range from 10/90 to 70/30 to present an optimized rigidity - hysteresis.

The half-life time of a peroxide is defined as the time required for the decomposition of one-half of the initial amount of peroxide at a given temperature. Decomposition is a first order reaction and is characteristic of a given temperature. For convenience, in order to compare the stability of the peroxides in dilute solution, they are listed according to the temperature for which they have half-life times of 10 hours or 1 hour. Generally, the half-life time is determined by differential scanning calorimetry coupled with microcalorimeter thermal activity monitoring (DSC-TAM) of a dilute peroxide solution, (eg, dicumyl peroxide) in a solvent. (for example monochlorobenzene). Those skilled in the art can easily determine the temperature to reach the half-life after one hour of a peroxide. For example, he may use the protocol described in Rajesh Babu, R. et al. "Advances in Elastomers I: Blends and Interpenetrating Netwroks - Chapter: Compounding and Vulcanization", Ed .: Visakh, PM et al. (2013).

Whatever the method used, it is important for the purposes of the invention that the difference between the temperature necessary to reach the half-life after one hour of the so-called slow peroxide (Tl) and the temperature necessary to reach the half-life after one hour of the so-called rapid peroxide (T2), ie at least 10 ° C.

Advantageously, the difference between T1 and T2 is at least 15 ° C, preferably at least 20 ° C.

More specifically, preferably, the difference between T1 and T2 is in the range of 10 to 125 ° C, preferably 15 to 45 ° C, more preferably 20 to 25 ° C.

According to the invention, the so-called slow and said rapid peroxides are preferably organic peroxides, which are well known to those skilled in the art.

Advantageously, the organic peroxides are chosen from the group comprising or consisting of dicumyl peroxide; tert-butyl hydroperoxide; tert-amyl hydroperoxide; cumyl hydroperoxide; 1,1,3,3-tetramethylbutyl hydroperoxide; isopropylcumyl hydroperoxide; 2,5-bis (tert-butylperoxy) -2,5-dimethyl-3-hexyne; 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxonane; di-tert-butyl peroxide; 2,5-bis (tert-butylperoxy) -2,5-dimethylhexane; Di (tert-butylperoxyisopropyl) benzene; tert-butylcumyl peroxide; di-tert-amyl peroxide; 4,4-di (tert-butylperoxy) butyl valerate; tert-butyl peroxybenzoate; 2,2-bis (tert-butylperoxy) butane; tert-amyl peroxybenzoate; tert-butyl peroxyacetate; tert-butylperoxy- (2-ethylhexyl) carbonate; tert-butylperoxy isopropyl carbonate; tert-butyl peroxy-3,5,5-trimethylhexanoate; 1,1-bis (tert-butylperoxy) cyclohexane; tert-amyl peroxyacetate; tert-amyl peroxy- (2-ethylhexyl) carbonate; 1,1-bis (tert-butylperoxy) -3,5,5-trimethylcyclohexane; 1,1-bis (tert-amylperoxy) cyclohexane; tert-butyl peroxy-maleate; 1,4-azodi (hexahydrobenzonitrile); tert-butyl peroxyisobutyrate; tert-butyl peroxydiethylacetate; tert-butyl peroxy-2-ethylhexanoate; benzoyl peroxide; tert-amyl peroxy-2-ethylhexanoate; bis (4-methylbenzoyl) peroxide; 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate; the ammonium peroxydisulfate; 2,5-dimethyl-2,5-di- (2-ethylhexanoyl peroxy) hexane; 2,2'-Azodi (2-methylbutyronitrile); 2,2'-Azodi (isobutyronitrile); decanoyl peroxide; dodecanoyl peroxide; bis (3,5,5-trimethylhexanoyl) peroxide; tert-amyl peroxypivalate; tert-butyl peroxyneoheptanoate; 1,1,3,3-tetramethylbutyl peroxypivalate; tert-butyl peroxypivalate; cetyl peroxydicarbonate; dimyristyl peroxydicarbonate; bis (2-ethylhexyl) peroxydicarbonate; bis (4-tert-butylcyclohexyl) peroxydicarbonate; diisopropyl peroxydicarbonate; tert-butyl peroxyneodecanoate; di-sec-butyl peroxydicarbonate; tert-amyl peroxyneodecanoate; cumylperoxyneoheptanoate; bis (3-methoxybutyl) peroxydicarbonate; 1,1,3,3-tetramethylbutyl peroxynodecanoate; cumyl peroxyneodecanoate; diisobutyryl peroxide; and their mixtures.

Advantageously, the rubber composition according to the present invention does not comprise a mixture of dicumyl peroxide and 1,3 and 1,4-isopropylcumyl cumyl peroxide.

Those skilled in the art will easily select the so-called slow peroxide and the so-called rapid peroxide from the known peroxides according to their needs using the respective temperatures necessary to reach their half-life after one hour.

By way of example, various peroxides and their respective temperatures necessary to reach the half-life after one hour (T) are presented: cumyl hydroperoxide (T = 166 ° C.), dicumyl peroxide (T = 135 ° C. C), 4,4-di (tert-butylperoxy) butyl valerate (T = 125 ° C), 1,1-bis (tert-butylperoxy) -3,5,5-trimethylcyclohexane (T = 110 ° C), tert-butyl peroxyneodecanoate (T = 64 ° C).

It is well understood that a given peroxide can be called peroxide said fast relative to a peroxide, or called peroxide said slow compared to another. For example, dicumyl peroxide can be described as "fast" peroxide compared to cumyl hydroperoxide, or referred to as "slow" peroxide compared to 1,1-bis (tert-butylperoxy) -3,5,5- trimethylcyclohexane.

It is preferable that the so-called slow peroxide level in the composition according to the invention is in a range from 0.5 to 4 phr, preferably from 1 to 3 phr. The so-called rapid peroxide level in the composition according to the invention may also be in a range from 0.5 to 4 phr, preferably from 1 to 3 phr. Preferably, the total level of peroxides in the composition according to the invention may be in a range from 1 to 8 phr, preferably from 2.5 to 6 phr. Advantageously, the ratio of the so-called slow peroxide level to the so-called fast peroxide level is in a range from 15/85 to 65/35, preferably from 20/80 to 60/40, more preferably from / 75 to 55/35.

11-2-2 Acrylate Derivative

 According to the invention, the rubber composition comprises at least one acrylate derivative of formula (I):

 [X] p A

 (I)

 in which,

 o [X] p corresponds to a radical of formula (II):

 in which,

^■ R, R ₂ and R ₃ independently represent a hydrogen atom or a hydrocarbon group-C ₈ selected from the group consisting of linear alkyl groups, branched or cyclic, alkylaryl groups, aryl groups and aralkyl, and optionally interrupted by one or more heteroatoms, R ₂ and R ₃ may together form a non-aromatic ring,

^■ (*) represents the point of attachment of the radical of formula (II) A, where A represents an atom belonging to the group consisting of alkaline earth metals or transition metals, a carbon atom or a hydrocarbon group Ci-C ₈ ,

 o A comprising p free valences, p having a value ranging from 2 to 4, it being understood that the 2 to 4 radicals X are identical or different.

According to the invention, the bond between X and A may be an ionic bond or a covalent bond. Those skilled in the art understand that when A represents an atom belonging to the group consisting of alkaline earth metals or transition metals, especially Zn or Mg, the bond between X and A is an ionic bond. By moreover, when A represents a carbon atom or a C 1 -C ₃₀ hydrocarbon group, it is well within the art to understand that the bond between X and A is a covalent bond.

By cyclic alkyl group is meant an alkyl group comprising one or more rings.

By group or hydrocarbon chain (e) interrupted by one or more heteroatoms is meant a group or chain comprising one or more heteroatoms, each heteroatom being between two carbon atoms of said group or said chain, or between an atom carbon of said group or said chain and another heteroatom of said group or said chain or between two other hetero atoms of said group or said chain.

By group or hydrocarbon chain (e) substituted with one or more heteroatoms is meant a group or chain comprising one or more heteroatoms, each heteroatom being linked to the hydrocarbon group or chain by a covalent bond without interrupting the hydrocarbon group or chain (e).

By "monomer unit" is meant the reacted form of at least one monomer in the acrylate derivative of formula (I).

When A comprises a cyclic hydrocarbon group, it may be a nonaromatic or aromatic cyclic hydrocarbon group.

The heteroatom (s) of the radicals R 1, R ₂ , R ₃ and A may be, independently of one another, oxygen, sulfur, nitrogen, phosphorus or silicon atoms, preferably oxygen atoms. or nitrogen.

Whatever the nature of the radical A, R 1, R ₂ and R ₃ may independently of each other be a hydrogen atom, a methyl group or an ethyl group.

Advantageously, R 1 may represent a methyl group and R ₂ and R ₃ may each represent a hydrogen atom. Alternatively, R _1; R ₂ and R ₃ may each represent a hydrogen atom. The number of valence p depends on the nature of the radical A. According to the invention, p may be from 1 to 20, for example it may be 1, alternatively it may be from 2 to 6, preferably from 2 to 4.

According to a first embodiment of the invention, whatever the groups R 1, R ₂ and R _{3 are} :

A represents an atom belonging to the group consisting of alkaline earth metals or transition metals, a carbon atom or a hydrocarbon group C ₁ -C ₁₃ , preferably C ₁ -C ₈ ,

 o A comprising p free valences, p having a value ranging from 2 to 4,

 it being understood that the 2 to 4 radicals X of the acrylate derivative of formula (I) are identical or different, preferably identical.

According to the invention, when A represents an atom belonging to the group consisting of alkaline earth metals or transition metals, it may be for example an atom selected from the group consisting of Zn and Mg.

When A represents a hydrocarbon group Ci-C _8, preferably Ci-C _8, it may be for example a hydrocarbon group of C ₁ -C ₇ alkyl, preferably Ci-C _6, preferably C ₁ -C ₅ .

For example, the C ₁ -C ₁₃ hydrocarbon group is chosen from the group consisting of the following radicals:

For example, the C ₁ -C ₈ hydrocarbon group is chosen from the group consisting of the following radicals:

dans lesquels, (*) représente le point d'attachement de A au radical de formule (II).

in which, (*) represents the point of attachment of A to the radical of formula (II).

Thus, according to the invention, the acrylate derivative of formula (I) can be chosen from zinc dimethacrylate (ZDMA), magnesium dimethacrylate (MgDMA), zinc diacrylate (ZMA), magnesium diacrylate ( MgMA), trimethylopropane trimethylacrylate (TMPTMA), trimethylolpropane triacrylate (TMPTA) and mixtures thereof. Preferably, the acrylate derivative of formula (I) is ZDMA, MgDMA, or a mixture thereof.

By way of example, diacrylate derivatives such as zinc diacrylate (ZDA) "DYMALINK 633" from CRAY VALLEY, zinc dimethacrylate (ZDMA) "DYMALINK 634" from CRAY VALLEY are commercially available. or trimethylolpropane trimethacrylate (TMPTMA) "SR351" from Sartomer.

According to a second embodiment of the invention, irrespective of the groups R 1, R ₂ and R ₃ , A may be a C 1 -C ₃₀ hydrocarbon-based group chosen from alkyl, linear, branched or cyclic groups, and optionally interrupted. and / or substituted with one or more heteroatoms. Preferably, A represents a linear alkyl group or branched C ₃ -C ₃₀ , optionally interrupted and / or substituted with one or more oxygen or nitrogen atoms, preferably oxygen. More preferably, A represents a linear or branched alkyl, C ₅ -C ₂ o, preferably C ₆ -C _6, optionally interrupted and / or substituted by one or more oxygen or nitrogen, preferably 'oxygen. According to this embodiment, A is advantageously not interrupted and / or substituted by one or more heteroatoms. Alternatively, according to this embodiment A is interrupted and / or substituted by one or more heteroatoms, preferably one or more oxygen or nitrogen atoms, preferably oxygen.

According to this second embodiment, the acrylate derivative of formula (I) may be chosen from the group consisting of lauryl (meth) acrylate, stearyl (meth) acrylate, polycaprolactone (meth) acrylate, isophoryl methoxy acrylate, tert-butylcyclohexyl (meth) acrylate, 4-acetoxyphenethyl (meth) acrylate, 4-acryloylmorpholine, butyl (meth) acrylate, tert-butyl (meth) acrylate, 2- benzyl propyl (meth) acrylate, the (meth) acrylate of

[[(butylamino) carbonyl] oxy] ethyl, 2-carboxyethyl (meth) acrylate, oligo-2-carboxyethyl (meth) acrylate, 2- (diethylamino) ethyl (meth) acrylate, (meth) ) di (ethylene glycol) ethyl ether acrylate, 2- (dimethylamino) ethyl (meth) acrylate, 3- (dimethylamino) propyl (meth) acrylate, dicyclopentenyl ethylene glycol (meth) acrylate, meth) acrylate ethylene glycol methyl ether, ethylene glycol phenyl ether (meth) acrylate, 2-ethylhexyl (meth) acrylate, hexyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate , 2-hydroxy-3-phenethylpropyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, hydroxypropyl (meth) acrylate, isobornyl (meth) acrylate, (meth) acrylate, isobutyl, isodecyl (meth) acrylate, isooctyl (meth) acrylate, octadecyl (meth) acrylate, poly (ethylene glycol) methyl ether (meth) acrylate, poly (meth) acrylate (propylene glycol), N-Propyl (meth) acrylamide, tetrahydrofurfuryl (meth) acrylate, 2-tetrahydropyranyl (meth) acrylate, 3,5,5-trimethylhexyl (meth) acrylate, 10-undecenyl (meth) acrylate ethoxylated nonyl phenol (meth) acrylate, propoxylated nonyl phenol (meth) acrylate, phenoxyethyl (meth) acrylate, ethoxylated nonylphenol mono (meth) acrylate, propoxylated nonylphenol mono (meth) acrylate, (meth) acrylate, 2 - [(butylamino) carbonyl] oxy] ethyl (meth) acrylate, 2- (2-ethoxyethoxy) ethyl (meth) acrylate, (meth) acrylate octyl decyl, isodecyl (meth) acrylate, propoxylated neopentyl glycol monomethyl ether (meth) acrylate, tricyclodecane methanol (meth) acrylate and mixtures thereof.

By way of example of an acrylate derivative of formula (I) available commercially and corresponding to this embodiment, mention may be made, for example, of those of the company SIGMA- ALDRICH: lauryl acrylate (LA); those of the company RAHN AG under the names GENOMER, 1120 or under the name MIRAMER M140; those of IGM RESINS under the name PHOTOMER 4135 or 4211; or those of the company under the name SARTOMER SR217, SR335 or SR531.

According to a third embodiment of the invention, whatever the groups R 1, R ₂ and R _{3 are} :

o A represents a linear, branched or cyclic C ₄ -C ₃₀ hydrocarbon group interrupted and / or substituted by one or more heteroatoms, o A comprising p free valences, p having a value ranging from 2 to 6,

 it being understood that the 2 to 6 radicals X of the acrylate derivative of formula (I) are identical or different, preferably identical.

According to this third embodiment, the heteroatom (s) of A may advantageously be chosen from the group consisting of oxygen, sulfur, nitrogen, silicon and phosphorus atoms and their combinations. Preferably, the heteroatom (s) of A are selected from the group consisting of oxygen and sulfur atoms. More preferably, the heteroatom (s) of A are oxygen atoms.

In other words, according to this third embodiment, A advantageously represents a linear, branched or cyclic C ₄ -C ₃₀ hydrocarbon group interrupted and / or substituted by one or more heteroatoms chosen from oxygen atoms, sulfur, nitrogen, silicon, phosphorus and combinations thereof, preferably selected from the group consisting of oxygen and sulfur atoms. More preferably, A preferably represents a linear, branched or cyclic C ₄ -C ₃₀ hydrocarbon-based group, preferably linear or branched, interrupted and / or substituted with one or more oxygen and / or sulfur atoms, preferably interrupted and / or substituted by one or more oxygen atoms.

Preferably, according to this third embodiment, A represents a linear, branched or cyclic, preferably linear or branched C ₄ -C ₃₀ hydrocarbon-based group, interrupted by one or more oxygen and / or sulfur atoms, of preferably interrupted by one or more oxygen atoms. More preferably, A represents a linear or branched C ₄ -C ₃₀ hydrocarbon-based group interrupted by one or more oxygen atoms.

According to this third embodiment, when A represents a C ₄ -C ₃₀ hydrocarbon group, it may be for example a hydrocarbon group C ₅ -C ₂₀ , preferably C ₆ -C ₆ . According to the invention, according to this third embodiment, the multifunctional acrylate derivative of formula (I) is preferably selected from the group consisting of dipentaerythriol penta (meth) acrylate, dipentaerythriol hexa (meth) acylate, diethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, ethoxylated hexanediol di (meth) acrylate, propoxylated hexanediol di (meth) acrylate, trimethylpropane tri (meth) acrylate ethoxylated, propoxylated trimethylpropane tri (meth) acrylate, ethoxylated pentaerythritol tetra (meth) acrylate, propoxylated pentaerythritol tetra (meth) acrylate, ethoxylated bisphenol A di (meth) acrylate, di (meth) acrylate, propoxylated bisphenol A, ethoxylated hexanediol glycol di (meth) acrylate, propoxylated hexanediol glycol di (meth) acrylate, ethoxylated neopentyl glycol di (meth) acrylate, propoxylated neopentyl glycol di (meth) acrylate, tri (meth) acrylate ethoxylated glycerol, propoxylated glycerol tri (meth) acrylate, ethoxylated trimethylolpropane tri (meth) acrylate, propoxylated trimethylolpropane tri (meth) acrylate, ester diol di (meth) acrylate, tri (meth) acrylate tri (2-hydroxyethyl) isocyanurate, hydroxypivalyl hydroxypivalate bis [6- (acryloyloxy) hexanoate] and mixtures thereof.

By way of example of a polyfunctional acrylate derivative of formula (I) corresponding to this third embodiment, mention may be made of those of the company SARTOMER under the name SR264 (polyethylene glycol (300) diacrylate), SR454 (trimethylolpropane triacrylate) ethoxylated (3)); those of MIWON SPECIALTY CHEMICAL under the name MIRAMER M340, M410, M500, M600 or M231; or those of IGM RESINS under the name PHOTOMER 4050, 4226, or 4600, and also those of SIGMA-ALDRICH: diethylene glycol diacrylate, dipropylene glycol diacrylate, dipentaerythriol pentaacrylate (DPPA), dipentaerythriol hexaacylate (DPHA).

According to a fourth embodiment of the invention, whatever the groups R 1, R ₂ and R _{3 are} :

 A represents a group comprising from 2 to 30 monomer units, the monomer units being chosen from the group consisting of epoxide, ester, ether, amine, acrylic, siloxane and urethane monomer units.

 o A comprising free valences, p having a value ranging from 1 to 20,

 it being understood that the 1 to 20 X radicals of the acrylate derivative of formula (I) are identical or different, preferably identical.

Particularly advantageously, according to this fourth embodiment, the monomer units represent more than 50 mol% of A, preferably more than 60 mol% of A. The monomer units can also represent 100 mol% of A. Moreover, the monomer units of A are advantageously identical, within the acrylate derivative of formulas (I).

Advantageously, according to this fourth embodiment, A represents a group which is linear. However, A may have branches, preferably when the monomeric units are urethane monomer units.

According to this fourth embodiment, A may advantageously represent a group comprising from 2 to 16, preferably from 3 to 10 monomer units, the monomeric units being chosen from the group consisting of epoxide, ester, ether, amine and acrylic monomer units. , siloxanes and urethanes.

Advantageously, according to this fourth embodiment, A comprises p free valences, p having a value ranging from 2 to 20, preferably from 2 to 15, preferably from 2 to 10, preferably from 2 to 8, preferably from 2 to 6. In other words, the acrylate derivative preferably comprises from 2 to 20, preferably from 2 to 15, preferably from 2 to 10, preferably from 2 to 8, preferably from 2 to 6. radicals X.

According to this fourth embodiment, the molecular weight of the acrylate derivative of formula (I) is advantageously in a range from 250 to 15,000 g / mol, preferably from 500 to 10,000 g / mol, more preferably from 800 to 8000 g / mol.

When the monomer units of A are epoxide monomeric units, the acrylate derivative of formula (I) is advantageously an "epoxy (meth) acrylate". A description of such compounds can be found in the book: Radiation Curing: Coatings and Printing inks, Technical Basics, Applications and Trouble Shooting, ISBN 3-86630-907-4, Publisher: Vincentz Network GmbH & Co eKG, Hanover, Authors: P.GIockner, TJung, S.Struck, K.Studer, 2008, p.60-62. These compounds may be epoxy derivatives of bisphenol, epoxy novolac, fatty acids or epoxidized oils (eg epoxidized soybean oil, epoxidized castor oil, etc.), or any other oligomer or polymer which has epoxy functions which are functionalized with (meth) acrylic acid in order to obtain the abovementioned (meth) acrylic epoxides, which can and can be modified or not.

When the monomer units of A are monomeric ester units, the acrylate derivative of formula (I) is advantageously a "(meth) acrylate ester". A description of such compounds can be found Radiation Curing: Coatings and Printing inks, Technical Basics, Applications and Trouble Shooting, ISBN 3-86630-907-4, Publisher: Vincentz Network GmbH & Co. KG, Hanover, Authors: P.GIockner, TJung, S.Struck, K.Studer, 2008, p.65. These compounds are characterized by the presence of ester-C (O) -O- units in their structure and the presence of two or more (meth) acrylate functional groups. They may contain alkyl or aryl elements. These molecules are most often prepared by esterification with acrylic acid of hydroxyl functional groups borne by polyester polyols or their derivatives. Another route is the reaction of carboxylic groups carried by polyesters with hydroxyalkyl acrylates.

When the monomer units of A are ether monomer units, the acrylate derivative of formula (I) is advantageously a "(meth) acrylate ether". A description of such compounds can be found Radiation Curing: Coatings and Printing inks, Technical Basics, Applications and Trouble Shooting, ISBN 3-86630-907-4, Publisher: Vincentz Network GmbH & Co. KG, Hanover, Authors: P.GIockner, Tjung, S.Struck, K.Studer, 2008, p.65-67. These compounds are characterized by the presence of ether-C-O- units in their structure. They may for example result from the polymerization of ethylene oxide or of propylene oxide which are polymerized with, for example, for a base molecule, molecules containing one, two or more hydroxyl functional groups, such as, for example, trimethylolpropane. . These ether (meth) acrylates can be modified by amine functions at the end of most of the time of a Michael reaction between (meth) acrylate functions and a primary or secondary amine.

When the monomer units of A are amine monomer units, the acrylate derivative of formula (I) is advantageously an "amine (meth) acrylate". A description of such compounds can be found Radiation Curing: Coatings and Radiation Curing: Coatings and Printing inks, Technical Basics, Applications and Trouble Shooting, ISBN 3-86630-907-4, Publisher: Vincentz Network GmbH & Co eKG, Hanover, Authors P.GIockner, TJung, S.Struck, K.Studer, 2008, p.66. These compounds may be oligomers containing a repeat unit amine function with one, two or more acrylic functional groups, or alternatively oligomers based on ester, ether, acrylic, silicone, urethane-type repeating units having acrylic functions. grafted and some of which have been modified by compounds having amine functions. An example of preparation of such compounds can be found in documents WO2000044734, FR3022544 or WO2008000696.

When the monomer units of A are monomeric acrylate units, the acrylate derivative of formula (I) is advantageously a "(meth) acrylate acrylate". A description of such compounds can be found Radiation Curing: Coatings and Printing inks, Technical Basics, Applications and Trouble Shooting, ISBN 3-86630-907-4, Publisher: Vincentz Network GmbH & Co. KG, Hanover, Authors: P.GIockner, Tjung, S.Struck, K.Studer, 2008, p.67. These compounds are characterized in that they are obtained by polymerization of acrylic monomers in order to obtain oligomers, polymers or copolymers which will subsequently be grafted in order to relate to their structure one, two or more functions (meth ) acrylic. The structures in question may be linear, branched, or star-shaped and therefore contain a repeating unit of the type - CH2-C (R) (C (O) -O-R ') - with R being a hygrogen or an alkyl or an aryl and R' a group which is the support or not of the function (meth) acrylic). An example of preparation of such compounds can be found in WO201293465.

When the monomer units of A are siloxane monomer units, the acrylate derivative of formula (I) is advantageously a "(meth) acrylate silicone". A description of such compounds can be found Radiation Curing: Coatings and Printing inks, Technical Basics, Applications and Trouble Shooting, ISBN 3-86630-907-4, Publisher: Vincentz Network GmbH & Co. KG, Hanover, Authors: P.GIockner, TJung, S.Struck, K.Studer, 2008, p.67-68. These compounds are characterized by the presence of siloxane units -Si (R) 2-0- in their structure and the presence of one, two or more (meth) acrylate functions (R may be an alkyl or an aryl). Several ways of obtaining are described in the literature, in particular with the documents CA2288384 and EP1595909.

When the monomer units of A are urethane monomer units, the acrylate derivative of formula (I) is advantageously a "(meth) acrylate urethane". A description of such compounds can be found Radiation Curing: Coatings and Printing inks, Technical Basics, Applications and Trouble Shooting, ISBN 3-86630-907-4, Publisher: Vincentz Network GmbH & Co. KG, Hanover, Authors: P.GIockner, TJung, S.Struck, K.Studer, 2008, p.62-64. These compounds are characterized by the presence of urethane -N (H) -C (O) -O- unit in their structure and the presence of one, two or more (meth) acrylate functions. A simple preparation route consists of the reaction of a molecule containing two or more isocyanate functions with hydroxylalkylacrylate molecules. Molecules of more sophisticated constitution can be obtained for example by reaction of polyols which can themselves be composed of alkyl, aryl, ester, ether, be linear, branched or starred, and diisocyanate molecules in the presence of hydroxyalkylacrylates.

Many acrylate derivatives of formula (I) are commercially available in this fourth embodiment. By way of example, when the monomer units of A of the acrylate derivative of formula (I) are epoxide monomeric units, mention may be made of those of SARTOMER under the name CN109 or CN186, or one of those of the company RAHN AG under the name GENORMER 2253 or 2281, or those of MIWON under the name MIRAMER PE210, or PE310, or those of the company IGM RESINS under the name PHOTOMER 3015, 3620 or 3660. When the monomeric units of A of the derivative of acrylate of formula (I) are ester monomer units, mention may be made of those of SARTOMER under the name CN203, CN291, or CH2562, or those of RAHN AG under the name GENOMER 3485, 3611, or those of MIWON under the name MIRAMER PS3010, PS4500, or P261; or those of the company IGM RESINS under the name PHOTOMER 5432 or 5450. When the monomer units of A of the acrylate derivative of formula (I) are monomers ether units, mention may be made of those of the company SARTOMER under the name tripropylene diacrylate glycol (SR306), trietylene glycol diacrylate (SR272), dipropylene glycol diacrylate (SR508), or one of those of RAHN AG under the name GENORMER 3364, 3480 or 3457, or those of the company IGM RESINS under the name PHOTOMER 5662 or 5010. When the monomer units of A of the acrylate derivative of formula (I) are monomeric amine units, mention may be made of one of those of the company RAHN AG under the name GENOMER 5271, 5275, 5695, or a those of the company SARTOMER under the name CN890, or one of those of MIWON under the name MIRAMER AS1000, LR3600 or A102. When the monomer units of A of the acrylate derivative of formula (I) are acrylic monomer units, mention may be made of one of those of the company SARTOMER under the name CN820, or one of those of the company MIWON under the name MIRAMER SC9060 , SC9211, S5242. When the monomer units of A of the acrylate derivative of formula (I) are siloxane monomer units, mention may be made of one of those of the company SARTOMER under the name CN9800, or one of those of the company ELKEM SILICONES under the name SILCOLEASE UV POLY110, UV ADD150, UV RCA 170, or one of those of the company EVONIK under the name TEGO RC902, RC711, RC722, RC922, or one of those of the company SHIN ETSU under the name X-22-164, X- 22-2445, X-22-174. When the monomer units of A of the acrylate derivative of formula (I) are urethane monomer units, mention may be made of those of SARTOMER under the name CN965 or CN9002, or one of those of the company MIWON under the name MIRAMER PU2100 , PU2560 or PU256NT, or one of those of IGM RESINS under the name PHOTOMER 6010, 6019 or 6720.

Whatever the embodiment of the invention, the level of acrylate derivative in the composition may range from 1 to 40 phr, preferably from 2 to 30 phr, more preferably from 5 to 25 phr. pc.

In a particularly advantageous manner, whatever the embodiment of the invention, preferably according to the first embodiment described above, the ratio of the peroxide level to the level of acrylate derivative is in a range from from 0.02 to 8, preferably from 0.05 to 5, more preferably from 0.08 to 1.2.

11-2-3 Sulfur

Furthermore, the rubber composition according to the invention is advantageously sulfur-free as a vulcanizing agent, or contain less than 0.3 phr, preferably less than 0.2, more preferably less than 0.1. pc. More preferably, the rubber composition according to the invention does not include sulfur. Sulfur may be molecular sulfur or come from a sulfur donor agent, such as alkyl phenol disulfides (APDS).

11-3 Reinforcing filler

The diene elastomer, the peroxides and the acrylate derivative are sufficient on their own for the invention to be carried out. Nevertheless, the rubber composition according to the invention may comprise a reinforcing filler known for its ability to reinforce a rubber composition.

A reinforcing filler typically consists of particles whose average size (in mass) is less than one micrometer, generally less than 500 nm, most often between 20 and 200 nm, in particular and more preferably between 20 and 150 nm.

Preferably, the composition contains no reinforcing filler or contains less than 150 phr, preferably less than 100 phr. In other words, the rubber composition according to the invention may optionally comprise from 0 to less than 150 phr, preferably from 0 to less than 100 phr of reinforcing filler. When the composition according to the invention comprises a reinforcing filler, the level of reinforcing filler in the composition according to the invention is preferably in a range from 10 to 90 phr, preferably from 20 to 80 phr, more preferably from 30 to 80 phr. at 75 pce.

The reinforcing filler may comprise carbon black, a reinforcing inorganic filler or mixtures thereof.

The reinforcing filler, when present in the composition according to the invention, is advantageously mainly composed of carbon black. The reinforcing filler may comprise, for example, from 50 to 100% by weight of carbon black, preferably from 55 to 90% by weight, preferably from 60 to 80% by weight. Particularly advantageously, the reinforcing filler comprises exclusively carbon black. The reinforcing filler may also further comprise a reinforcing inorganic filler. Preferably, the reinforcing inorganic filler is silica.

When the composition according to the invention comprises carbon black (predominantly or exclusively, as a reinforcing filler), the level of carbon black in the composition according to the invention is preferably in a range from 10 to 90 preferably from 20 to 80 phr, more preferably from 30 to 75 phr. The blacks that can be used in the context of the present invention may be all black conventionally used in tires or their treads (so-called pneumatic grade blacks). Among the latter, there will be mentioned more particularly the reinforcing carbon blacks of the series 100, 200, 300, or the series blacks 500, 600 or 700 (ASTM grades), such as, for example, the blacks N115, N134, N234, N326, N330. , N339, N347, N375, N550, N683, N772). These carbon blacks can be used in the isolated state, as commercially available, or in any other form, for example as a carrier for some of the rubber additives used. The carbon blacks could for example already be incorporated into the diene elastomer, in particular isoprene in the form of a masterbatch (see for example applications WO 97/36724 or WO 99/16600). The BET surface area of the carbon blacks is measured according to the D6556-10 standard [multipoint method (at least 5 points) - gas: nitrogen - relative pressure range R / R0: 0.1 to 0.3].

"Reinforcing inorganic filler" means any inorganic or mineral filler, irrespective of its color and origin (natural or synthetic), also called "white" filler, "clear" filler or even "non-black" filler. as opposed to carbon black, capable of reinforcing on its own, with no other means than an intermediate coupling agent, a rubber composition intended for the manufacture of pneumatic tires, in other words able to replace, in its function of reinforcement, a conventional carbon black of pneumatic grade; such a filler is generally characterized, in known manner, by the presence of hydroxyl groups (-OH) on its surface. In other words, without a coupling agent, the inorganic filler does not make it possible to reinforce or not sufficiently the composition and is therefore not included in the definition of "reinforcing inorganic filler".

Suitable reinforcing inorganic fillers are in particular mineral fillers of the siliceous type, preferentially silica (SiO ₂ ). The silica used may be any reinforcing silica known to those skilled in the art, in particular any precipitated or fumed silica having a BET surface and a CTAB specific surface both less than 450 m ² / g, preferably from 30 to 400 m ² / g, especially between 60 and 300 m ² / g. As highly dispersible precipitated silicas (called "HDS"), mention may be made, for example, of the "Ultrasil" 7000 and "Ultrasil" 7005 silicas of the Degussa company, the "Zeosil" 1165MP, 1135MP and 1115MP silicas of the Rhodia company. "Hi-Sil" silica EZ150G from the company PPG, the "Zeopol" silicas 8715, 8745 and 8755 from the Huber Company, the high surface area silicas as described in the application WO 03/016387.

In the present description, with regard to silica, the BET surface area is determined in a known manner by gas adsorption using the method of Brunauer-Emmett-Teller described in "The Journal of the American Chemical Society" Flight . 60, page 309, February 1938, specifically according to the French standard NF ISO 9277 of December 1996 (multipoint volumetric method (5 points) - gas: nitrogen - degassing: time at 160 ° C - relative pressure range p / po: 0.05 at 0.17). The CTAB specific surface is the external surface determined according to the French standard NF T 45-007 of November 1987 (method B).

Reinforcing inorganic fillers are also suitable for mineral fillers of the aluminous type, in particular alumina (Al ₂ O ₃ ) or aluminum (oxide) hydroxides, or reinforcing titanium oxides, for example described in US Pat. No. 6,610,261 and US Pat. US 6,747,087.

The physical state in which the reinforcing inorganic filler is present is indifferent whether in the form of powder, microbeads, granules, beads or any other suitable densified form. Of course, the term "reinforcing inorganic filler" also refers to mixtures of different reinforcing inorganic fillers, in particular highly dispersible siliceous and / or aluminous fillers as described above.

Those skilled in the art will understand that, as the equivalent filler of the reinforcing inorganic filler described in this paragraph, it would be possible to use a reinforcing filler of another nature, in particular an organic filler, since this reinforcing filler would be covered with a filler. inorganic layer such as silica, or would comprise on its surface functional sites, especially hydroxyl, requiring the use of a coupling agent to establish the bond between the filler and the elastomer. In order to couple the reinforcing inorganic filler to the diene elastomer, an at least bifunctional coupling agent (or bonding agent) is used in a well-known manner to ensure a sufficient chemical and / or physical connection between the inorganic filler (surface of its particles) and the diene elastomer. In particular, organosilanes or at least bifunctional polyorganosiloxanes are used.

Those skilled in the art can find examples of coupling agent in the following documents: WO 02/083782, WO 02/30939, WO 02/31041, WO 2007/061550, WO 2006/125532, WO 2006/125533, WO 2006/125534, US 6,849,754, WO 99/09036, WO 2006/023815, WO 2007/098080, WO 2010/072685 and WO 2008/055986.

The content of coupling agent is advantageously less than 10 phr, it being understood that it is generally desirable to use as little as possible. Typically when a reinforcing inorganic filler is present, the level of coupling agent is from 0.5% to 15% by weight based on the amount of inorganic filler. Its level is preferably in a range from 0.5 to 7.5 phr. This rate is easily adjusted by those skilled in the art according to the level of inorganic filler used in the composition.

The rubber composition according to the invention may also contain, in addition to the coupling agents, coupling activators, inorganic charge-covering agents or, more generally, processing aid agents which can be used in known manner, thanks to to improve the dispersion of the filler in the rubber matrix and to lower the viscosity of the compositions, to improve their ability to use in the green state, these agents being, for example, hydrolysable silanes such as alkylalkoxysilanes (especially alkyltriethoxysilanes), polyols, polyethers (for example polyethylene glycols), trialkanolamines, hydroxylated or hydrolysable POSs, for example α,--dihydroxy-polyorganosiloxanes (especially α,--dihydroxy-polydimethylsiloxanes); ), fatty acids such as stearic acid.

11-4 Miscellaneous additives

 The rubber compositions according to the invention may also comprise all or part of the usual additives, known to those skilled in the art and usually used in tire rubber compositions, in particular treads or internal layers of rubber. pneumatics, such as, for example, plasticizers (plasticizing oils and / or plasticizing resins), fillers other than those mentioned above, pigments, protective agents such as anti-ozone waxes, chemical anti-ozonants, anti-oxidants, anti-oxidants, -fatigue, reinforcing resins (as described for example in the application WO 02/10269).

11-5 Preparation of rubber compositions

The rubber composition according to the invention can be manufactured in suitable mixers, using two successive preparation phases well known to those skilled in the art:

a first phase of work or thermomechanical mixing (so-called "nonproductive" phase), which can be conducted in a single thermomechanical step during which is introduced into a suitable mixer such as a conventional internal mixer (for example of the type 'Banbury'), all the necessary constituents, in particular the elastomeric matrix, the acrylate derivative, the optional fillers, the possible other various additives, with the exception of the peroxide. Incorporation of the filler into the elastomer, when present, can be performed in one or more times by thermomechanically kneading. In the case where the filler, in particular the carbon black, is already incorporated in whole or in part into the elastomer in the form of a masterbatch, as described for example in the applications WO 97/36724 or WO 99 / 16600 is the masterbatch that is directly kneaded and if necessary is incorporated other elastomers or fillers present in the composition which are not in the form of masterbatch, as well as any other various additives other than the crosslinking system. The non-productive phase is carried out at a high temperature, up to a maximum temperature of between 110 ° C. and 200 ° C., preferably between 130 ° C. and 185 ° C., for a period generally of between 2 and 10 minutes. second phase of mechanical work (so-called "productive" phase), which is performed in an external mixer such as a roll mill, after cooling the mixture obtained during the first non-productive phase to a lower temperature, typically below 120 ° C, for example between 40 ° C and 100 ° C. The peroxides are then incorporated and the whole is then mixed for a few minutes, for example between 2 and 15 min.

The final composition thus obtained is then calendered, for example in the form of a sheet or a plate, in particular for a characterization in the laboratory, or else extruded in the form of a semifinished (or profiled) of rubber usable by example as a tire tread or as an inner tire layer.

The cooking can be carried out, in a manner known to those skilled in the art, at a temperature generally between 130 ° C. and 200 ° C., under pressure, for a sufficient time which may vary, for example, between 5 and 90 min, depending in particular the firing temperature, the crosslinking system adopted, the kinetics of crosslinking of the composition in question or the size of the tire.

11-6 Finished or semi-finished and pneumatic rubber article

The present invention also relates to a finished or semi-finished rubber article comprising a composition according to the invention.

It also relates to a tire comprising a composition according to the invention or a semi-finished rubber article according to the invention.

The invention particularly relates to tires intended to equip motor vehicles of the tourism type, SUV ("Sport Utility Vehicles"), or two wheels (in particular motorcycles), or planes, or industrial vehicles chosen from light trucks, "Poids- "heavy" - that is, metros, buses, road transport vehicles (trucks, tractors, trailers), off-the-road vehicles such as agricultural or civil engineering machinery, and others.

The composition defined in the present description is particularly well suited to the tread and the inner tire layers. Thus, in the tire according to the present invention the composition may be present in the tread of the tire or in at least one inner layer of the tire. According to the invention, the inner layer may be chosen from the group consisting of carcass plies, crown plies, bead-knuckles, toe feet, decoupling layers, edging gums, tamping gums, the sub-ply tread layer and combinations of these inner layers. Preferably, the inner layer is selected from the group consisting of carcass plies, crown plies, bead fences, toe feet, decoupling layers and combinations of these inner layers.

The invention relates to tires and semi-finished products for tires previously described, the rubber articles, both in the raw state (that is to say, before cooking) and in the cooked state (this is that is, after crosslinking or vulcanization).

III- BRIEF DESCRIPTIONS OF FIGURES

 Fig. 1 is a graph showing tan (δ) max values at 60 ° C (ordinate) as a function of the nature and concentration of peroxides (abscissa).

 Figure 2 is a graph showing the values of G * (10%) at 60 ° C expressed in MPa (ordinate) depending on the nature and concentration of peroxides (abscissa).

 Figure 3 is a graph showing the durations for which 90% crosslinking is obtained after starting the baking at 140 ° C expressed in minutes (ordinate) depending on the nature and concentration of peroxides (abscissa).

In all these figures, "DICUP" means 100% dicumyl peroxide; "Lup 231" means 100% 1,1-bis (tert-butylperoxy) -3,5,5-trimethylcyclohexane; the ratios 80/20, 60/40, 50/50, 40/60, 20/80 are the respective ratios of DICUP / Lup 231 for which measurements have been made.

IV- EXAMPLES

 IV-1 Measurements and tests used

The dynamic properties G * (10%) and tan (δ) max at 60 ° C are measured on a viscoanalyzer (Metravib VA4000) according to ASTM D 5992-96. The response of a reticulated composition sample (cylindrical specimen 4 mm in thickness and 400 mm ² in section), subjected to a sinusoidal stress in alternating simple shear, at the frequency of 10 Hz, is recorded under the defined conditions of temperature for example at 60 ° C according to ASTM D 1349-99, or as the case may be at a different temperature. A strain amplitude sweep of 0.1 to 50% (forward cycle) and then 50% to 0.1% (return cycle) are performed. The results exploited are the complex dynamic shear modulus G * and the loss factor tan (δ). For the return cycle, the maximum value of tan (δ) observed, denoted tan (δ) max, as well as the complex dynamic shear modulus G * (10%) at 10% deformation, at 60 ° C are indicated.

It will be recalled that, in a manner well known to those skilled in the art, the value of tan (δ) max at 60 ° C. is representative of the hysteresis of the material and therefore of the rolling resistance: plus the value tan (δ) max at 60 ° C is low, the lower the rolling resistance is reduced and therefore improved. Furthermore, the value of G * (10%) at 60 ° C is representative of the rigidity: the higher the value of G * (10%) at 60 ° C, the greater the stiffness is important.

Rheometry:

 The measurements are carried out at a given temperature (for example 140 ° C.) with an oscillating chamber rheometer according to DIN 53529 - Part 3 (June 1983). The evolution of the rheometric torque, ACouple, as a function of time describes the evolution of the stiffening of the composition as a result of the vulcanization reaction. The measurements are processed according to DIN 53529 - Part 2 (March 1983): T0 is the induction time (expressed in min), that is to say the time required for the beginning of the crosslinking reaction; ta (for example t90) is the time necessary to reach a conversion of a% (for example 90%), that is to say a% (for example 90%) of the difference between the minimum and maximum couples. The lower the value of ta, the faster the composition will cross-link, that is to say that the cooking will have been quick.

IV-2 Preparation of compositions

In the following examples, the rubber compositions were made as described in point 11.5 above. In particular, the "non-productive" phase was carried out in a 0.4 liter mixer for 3.5 minutes, for an average pallet speed of 50 revolutions per minute until reaching a maximum temperature of 160 ° C. The "productive" phase was performed in a cylinder tool at 23 ° C for 5 minutes.

IV-3 Tests of rubber compositions

The dynamic properties and the rheology of different rubber compositions comprising a peroxide (s) crosslinking system were measured. The compositions tested (in phr) and the results obtained are shown in Table 1 below. The peroxides tested, alone or in blends, are dicumyl peroxide and 1,1-bis (tert-butylperoxy) -3,5,5-trimethylcyclohexane, the temperatures necessary to reach their half-life after one hour are 135 ° C and 110 ° C, respectively. Compositions C, D, E and F are in accordance with the invention. Compositions A and G are control compositions comprising only one peroxide. Composition B is a control composition comprising two peroxides, but at levels such that the ratio of slow and fast peroxide levels is not in accordance with the invention. Table 1

 (1) Natural rubber

 (2) Carbon black N326 (designation according to ASTM D-1765)

 (3) Zinc oxide (industrial grade - Umicore company)

 (4) Zinc dimethacrylate ("Dimalink 634" from Cray Valley Corporation)

 (5) Dicumyl peroxide ("Dicup DCP" from Arkema)

 (6) 1,1-bis (tert-butylperoxy) -3,5,5-trimethylcyclohexane ("Luperox 231" from Arkema)

The results obtained are shown in the graphs of FIGS. 1, 2 and 3. These results show, surprisingly, that the hysteresis of the compositions comprising a cutting of Dicup / Lup 213 peroxides ranging from 20/80 to 60/40 is significantly lower than the expected hysteresis (in dashed line) by the weighted average of these two peroxides (Fig. 1). Moreover, the rigidity of the compositions comprising a blend of Dicup / Lup 213 peroxides ranging from 20/80 to 50/50 is greater than the expected stiffness (in dashed line) by the weighted average of these two peroxides (FIG 2). Finally, the cooking speed of the compositions comprising a cutting of Dicup / Lup 213 peroxides ranging from 20/80 to 60/40 is greater than the expected cooking rate (in dashed line) by the weighted average of these two peroxides (Fig. 3).

The hysteresis and rigidity of compositions according to the invention (H, D, I and J) have also been measured at different concentrations of peroxides for compositions whose slow peroxide / fast peroxide ratio is 50/50. The compositions tested (in phr) and the results obtained are shown in Table 2 below.

Table 2

 (1) to (6) see Table 1

Increasing the levels of the two peroxides at the 50/50 ratio makes it possible to increase rigidity while maintaining a reduced hysteresis, ie an improved rolling resistance.

Claims

1. Rubber composition based on at least:  a diene elastomer,  a first peroxide whose temperature required to reach its half-life after one hour is denoted Tl, said slow peroxide,  a second peroxide whose temperature necessary to reach its half-life after one hour is noted T2, said fast peroxide,  an acrylate derivative of formula (I): [X] _P A (i)  in which :  o [X] p corresponds to a radical of formula (II):

 in which, ^■ R, R ₂ and R ₃ independently represent a hydrogen atom or a hydrocarbon group-C ₈ selected from the group consisting of linear alkyl groups, branched or cyclic, alkylaryl groups, aryl groups and aralkyl, and optionally interrupted by one or more heteroatoms, R ₂ and R ₃ may together form a non-aromatic ring, ^■ (*) represents the point of attachment of the radical of formula (II) A, where A represents an atom belonging to the group consisting of alkaline earth metals or transition metals, a carbon atom, a hydrocarbon group C 1 -C ₃₀ optionally interrupted and / or substituted with one or more heteroatoms, or a group comprising from 2 to 30 monomer units, the monomeric units being chosen from the group consisting of epoxide, ester, ether, amine, acrylic monomer units, siloxanes and urethanes, o A comprising free valences, p having a value ranging from 1 to 20, o it being understood that the 1 to 20 radicals X are identical or different, composition in which the temperature T1 is greater than T2 and the difference between T1 and T2 is at least 10 ° C, and wherein the ratio of the peroxide level said slow on the so-called fast peroxide level is included in a range from 10/90 to 70/30. The rubber composition according to claim 1, wherein in the acrylate derivative of formula (I): A represents an atom belonging to the group consisting of alkaline earth metals or transition metals, a carbon atom or a C ₁ -C ₈ hydrocarbon group,  o A comprising p free valences, p having a value ranging from 2 to 4, it being understood that the 2 to 4 radicals X are identical or different. A composition according to any one of the preceding claims, wherein the diene elastomer is selected from the group consisting of polybutadienes, synthetic polyisoprenes, natural rubber, butadiene copolymers, isoprene copolymers and blends. of these elastomers, preferably selected from the group consisting of synthetic polyisoprenes, natural rubber and mixtures thereof. 4. A composition according to any one of the preceding claims, wherein the difference between T1 and T2 is at least 15 ° C, preferably at least 20 ° C. 5. Composition according to any one of claims 1 to 3, wherein the difference between T1 and T2 is in a range from 10 to 125 ° C, preferably from 15 to 45 ° C, more preferably from 20 to 25 ° C. 6. Composition according to any one of the preceding claims, wherein the so-called slow and said rapid peroxides are organic peroxides. The composition of any one of the preceding claims, wherein the organic peroxides are selected from the group consisting of dicumyl peroxide; tert-butyl hydro-peroxide; tert-amyl hydroperoxide; cumyl hydroperoxide; 1,1,3,3-tetramethylbutyl hydroperoxide; isopropylcumyl hydroperoxide; 2,5-bis (tert-butylperoxy) -2,5-dimethyl-3-hexyne; 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxonane; di-tert-butyl peroxide; 2,5-bis (tert-butylperoxy) -2,5-dimethylhexane; Di (tert-butylperoxy-isopropyl) benzene; peroxide of tert- butylcumyl; di-tert-amyl peroxide; 4,4-di (tert-butylperoxy) butyl valerate; tert-butyl peroxybenzoate; 2,2-bis (tert-butylperoxy) butane; tert-amyl peroxybenzoate; tert-butyl peroxyacetate; tert-butylperoxy- (2-ethylhexyl) carbonate; tert-butylperoxy isopropyl carbonate; tert-butyl peroxy-3,5,5-trimethylhexanoate; 1,1-bis (tert-butylperoxy) cyclohexane; tert-amyl peroxyacetate; tert-amyl peroxy- (2-ethylhexyl) carbonate; 1,1-bis (tert-butylperoxy) -3,5,5-trimethylcyclohexane; 1,1-bis (tert-amylperoxy) cyclohexane; tert-butyl peroxy-maleate; 1,4-azodi (hexahydrobenzonitrile); tert-butyl peroxyisobutyrate; tert-butyl peroxydiethylacetate; tert-butyl peroxy-2-ethylhexanoate; benzoyl peroxide; tert-amyl peroxy-2-ethylhexanoate; bis (4-methylbenzoyl) peroxide; 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate; ammonium peroxydisulfate; 2,5-dimethyl-2,5-di- (2-ethylhexanoyl peroxy) hexane; 2,2'-Azodi (2-methylbutyronitrile); 2,2'-Azodi (isobutyronitrile); decanoyl peroxide; dodecanoyl peroxide; bis (3,5,5-trimethylhexanoyl) peroxide; tert-amyl peroxypivalate; tert-butyl peroxyneoheptanoate; 1,1,3,3-tetramethylbutyl peroxypivalate; tert-butyl peroxypivalate; cetyl peroxydicarbonate; dimyristyl peroxydicarbonate; bis (2-ethylhexyl) peroxydicarbonate; bis (4-tert-butylcyclohexyl) peroxydicarbonate; diisopropyl peroxydicarbonate; tert-butyl peroxyneodecanoate; di-sec-butyl peroxydicarbonate; tert-amyl peroxyneodecanoate; cumylperoxyneoheptanoate; bis (3-methoxybutyl) peroxydicarbonate; 1,1,3,3-tetramethylbutyl peroxynodecanoate; cumyl peroxyneodecanoate; diisobutyryl peroxide; and their mixtures. 8. Composition according to any one of the preceding claims, wherein the so-called slow peroxide level is in a range from 0.5 to 4 phr, preferably from 1 to 3 phr. 9. Composition according to any one of the preceding claims, wherein the so-called fast peroxide level is in a range from 0.5 to 4 phr, preferably from 1 to 3 phr. 10. Composition according to any one of the preceding claims, wherein the total content of peroxides is in a range from 1 to 8 phr, preferably from 2.5 to 6 phr. 11. Composition according to any one of the preceding claims, wherein the ratio of the peroxide content said to slow on the peroxide rate said fast is in a range from 15/85 to 65/35, preferably from 20/80 to 60/40. 12. Composition according to any one of the preceding claims, in which R 1, R ₂ and R ₃ independently of one another represent a hydrogen atom, a methyl group or an ethyl group. 13. Composition according to any one of the preceding claims, in which R 1 represents a methyl group and R ₂ and R ₃ each represent a hydrogen atom. The composition of any one of claims 1 to 12, wherein R _1; R ₂ and R ₃ each represent a hydrogen atom. 15. A composition according to any one of the preceding claims, wherein p is 2 or 3, preferably 2. 16. A composition according to any one of the preceding claims, wherein A represents an atom selected from the group consisting of Zn and Mg. 17. A composition according to any one of claims 1 to 14, wherein A represents a hydrocarbon group C ₁ -C ₈ selected from the group consisting of the following radicals:

in which, (*) represents the point of attachment of A to the radical of formula (II). A rubber composition according to any one of the preceding claims, wherein the acrylate derivative is selected from the group consisting of zinc dimethacrylate, magnesium dimethacrylate, zinc diacrylate, magnesium diacrylate, trimethyl propane trimethyl acrylate. , trimethylolpropane triacrylate and mixtures thereof. 19. Composition according to any one of the preceding claims, in which the level of acrylate derivative is in a range from 1 to 40 phr, preferably from 2 to 30 phr, more preferably from 5 to 25 phr. 20. Composition according to any one of the preceding claims, in which the ratio of the total content of peroxides to the level of acrylate derivative is in a range from 0.02 to 8, preferably from 0.1 to 1. 2. 21. Composition according to any one of the preceding claims, said composition being sulfur-free as a vulcanizing agent, or containing less than 0.3 phr, preferably less than 0.2 phr. 22. Composition according to any one of the preceding claims, said composition optionally comprising from 0 to 150 phr of reinforcing filler. 23. The composition of claim 22, wherein the reinforcing filler comprises carbon black, an inorganic reinforcing filler or a mixture thereof. 24. Composition according to claim 22 or 23, wherein the reinforcing filler mainly comprises, preferably exclusively, carbon black. 25. The composition of claim 24, wherein the carbon black content is in a range from 10 to 90 phr, preferably from 20 to 80 phr, more preferably from 30 to 75 phr. 26. A finished or semi-finished rubber article comprising a composition according to any one of claims 1 to 25. 27. A tire comprising a composition according to any one of claims 1 to 24 or a semi-finished rubber article according to claim 25. 28. A tire according to claim 27, wherein the composition according to any one of claims 1 to 25 is present in at least the tread of the tire or in at least one inner layer. The tire of claim 28, wherein the inner layer is selected from the group consisting of carcass plies, crown plies, bead fences, toe feet, decoupling layers, edging gums, tamping gums. , tread underlayer and combinations of these inner layers.