WO2018202979A1

WO2018202979A1 - Rubber composition comprising a polyfunctional acrylate incorporated from a masterbatch

Info

Publication number: WO2018202979A1
Application number: PCT/FR2018/051035
Authority: WO
Inventors: Didier Vasseur; Delphine VILCOT; Guillaume PIBRE
Original assignee: Compagnie Generale Des Etablissements Michelin
Priority date: 2017-05-04
Filing date: 2018-04-25
Publication date: 2018-11-08
Also published as: EP3619050A1; FR3065959A1

Abstract

The present invention relates to rubber compositions comprising at least: a diene elastomer, a peroxide, and a masterbatch comprising an elastomer and a specific polyfunctional acrylate. The invention also relates to a method for obtaining such compositions and to finished or semi-finished rubber articles comprising said compositions.

Description

RUBBER COMPOSITION BASED ON POLYFUNCTIONAL ACRYLATE INCORPORATED FROM A MASTER MIXTURE

The invention relates to rubber compositions comprising a polyfunctional acrylate, preferably a zinc diacrylate derivative, and a peroxide, especially 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 document WO 2016/139285 proposes compositions comprising a derivative of zinc diacrylate, a peroxide and a low level of reinforcing filler to improve both the resistance rolling and resistance to aging in thermal and thermo-oxidative conditions. Continuing its research, the Applicant has surprisingly discovered that the use of a polyfunctional acrylate incorporated in a diene elastomeric matrix in the form of a masterbatch, in combination with a peroxide, makes it possible to improve the rigidity of the compositions for pneumatic tires without penalizing cohesion.

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

a diene elastomer,

a peroxide, a masterbatch comprising an elastomer and a polyfunctional acrylate of formula (I)

[X] _P A (i)

in which :

A represents an atom belonging to the group consisting of alkaline earth metals or transition metals, a carbon atom or a linear, branched or cyclic C ₁ -C ₃ hydrocarbon group,

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

it being understood that the 2 to 4 radicals X are identical or different;

the polyfunctional acrylate being advantageously a derivative of zinc diacrylate in the form of a zinc salt of formula (III)

in which R 1, R ₂ and R ₃ represent, independently of one another, a hydrogen atom or a C 1 -C 7 hydrocarbon-based group chosen from linear, branched or cyclic alkyl groups, aralkyl groups, alkylaryl groups and aryl groups; and optionally interrupted by one or more heteroatoms, R ₂ and R ₃ may together form a non-aromatic ring.

This object is also referred to herein as "composition according to the invention" for reasons of simplification of writing.

The present invention furthermore relates to a process for obtaining a rubber composition based on at least one diene elastomer, a peroxide, and a masterbatch comprising an elastomer and a polyfunctional acrylate of formula (I).

[X] _P A m

in which :

A represents an atom belonging to the group consisting of alkaline earth metals or transition metals, a carbon atom or a linear, branched or cyclic C1-C13 hydrocarbon group,

in which,

^■ R-ι, 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,

it being understood that the 2 to 4 radicals X are identical or different;

(III) wherein R 1, R ₂ and R ₃ independently of one another are a hydrogen atom or a C ₇ hydrocarbon group selected from linear, branched or cyclic alkyl groups, aralkyl groups, alkylaryl groups and aryl groups, and optionally interrupted by one or more heteroatoms, R ₂ and R ₃ may together form a non-aromatic ring,

said method comprising the following steps:

(a) contacting and mixing the polyfunctional acrylate of formula (I), preferably the zinc diacrylate derivative, and the elastomer, to form a masterbatch,

(b) contacting and mixing, concomitantly or sequentially, the masterbatch obtained in step (a), a diene elastomer and a peroxide.

This object is also referred to herein as the "method according to the invention of the reasons for simplification of writing. The present invention also relates to:

a rubber composition obtainable by the process according to the invention,

a finished or semi-finished rubber article comprising a composition according to the invention or a rubber composition obtainable by the process according to the invention, and

a tire comprising a composition according to the invention, a rubber composition obtainable by the process according to the invention, or a semi-finished rubber article according to the invention.

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. For the purposes of the present invention, the elastomer mass includes the mass of the diene elastomer and the mass of the elastomer of the masterbatch defined below.

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 matrix and sulfur comprises the elastomeric matrix and the sulfur before cooking, whereas after cooking the sulfur is no longer detectable because it has reacted with the elastomeric matrix forming sulfur bridges (polysulfides, disulfides, mono-sulfide).

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. In contrast, a "minor" compound is a compound that does not represent the largest mass fraction among compounds of the same type.

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

II-A Composition according to the invention

II-A-1 Diene Elastomer

The composition according to 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).

These 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% (mole%); 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%. Given these definitions, the term "diene elastomer" can be understood more particularly to be used in the compositions 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 oolefin 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 hexadiene-1,4, 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, are particularly suitable. 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, raryl-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, chlorostoises, 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 or US Pat. No. 6,013,718 and WO 2008/141702), alkoxysilane groups (as described for example in FR 2,765,882 or US 5,977,238), carboxylic groups (as described for example in WO 01/92402 or US 6,815,473, WO 2004/096865 or US 2006/0089445). ) or else polyether groups (as described for example in EP 1 127 909 or 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 according to the invention can be chosen, for example, from the group of highly unsaturated diene elastomers, preferably from the group comprising or consisting of polybutadienes (abbreviated as "BR"), synthetic polyisoprenes (IR), natural rubber (NR), butadiene copolymers, 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 of butadiene styrene (SBIR), butadiene-acrylonitrile copolymers (NBR), butadiene-styrene-acrylonitrile copolymers (NSBR) or a mixture of two or more of these compounds. According to a particular preferential embodiment, 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 cis 1,4 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 isoprene elastomer, more preferably of 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.

II-A-2 Masterbatch

The composition according to the invention further comprises a masterbatch comprising an elastomer and a polyfunctional acrylate, preferably a zinc diacrylate derivative.

The concept of "masterbatch" (commonly referred to by its English name "masterbatch") is well known to those skilled in the art. It is an elastomer-based composite in which one or more additives, for example a filler, have been introduced or, in the context of the present invention, a polyfunctional acrylate, preferably a zinc diacrylate derivative. The Applicant has found, surprisingly, that the incorporation of polyfunctional acrylate, preferably of zinc diacrylate derivative, in the form of a masterbatch makes it possible to increase the modulus of the composition with respect to the incorporation of the same polyfunctional acrylate, preferably of the same derivative of zinc diacrylate, directly in the composition, in powder form in particular. II-A-2-a Polyfunctional Acrylate

The masterbatch of the composition according to the invention comprises a polyfunctional acrylate of formula (I)

[X] _P A (i)

in which :

in which,

^■ ^(*) represents the point of attachment of the radical of formula (II) A,

it being understood that the 2 to 4 radicals X are identical or different;

in which R 1, R ₂ and R ₃ independently represent a hydrogen atom or a C ₁ -C ₇ hydrocarbon-based group chosen from linear, branched or cyclic alkyl groups, aralkyl groups, alkylaryl groups and aryl groups, and optionally interrupted by one or more heteroatoms, R ₂ and R ₃ may together form a non-aromatic ring.

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 C1-C13, it can be for example a hydrocarbon group C1-C1 _0, preferably -C _8, preferably C 1 -C 5.

When A represents a cyclic hydrocarbon group, it may be a nonaromatic or aromatic cyclic hydrocarbon group, preferably non-aromatic.

For example, the C1-C13 hydrocarbon group is chosen from the consti group.

wherein m is an integer from 1 to 13, preferably from 6 to 10, and ( ^* ) represents the point of attachment of A to the radical of formula (II).

The number of valence p depends on the nature of the radical A. According to the invention, p can 2, 3 or 4. For example, p can be 2 or 3, for example 2.

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. On the other hand, when A represents a carbon atom or a C1-C13 hydrocarbon group, the person skilled in the art clearly understands 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. The heteroatom (s) may be a nitrogen, sulfur or oxygen atom.

Preferentially in formulas (I) and (III) above, R 1, R ₂ and R ₃ independently represent a hydrogen atom, a methyl group or an ethyl group. More preferably, R ₂ and R ₃ each represent a hydrogen atom and according to a very preferred alternative, R 1 represents a methyl group. Alternatively, R 1, R ₂ and R ₃ may each represent a hydrogen atom.

Advantageously, the polyfunctional acrylate is chosen from the group consisting of zinc dimethacrylate, magnesium dimethacrylate, zinc diacrylate, magnesium diacrylate, trimethylopropane trimethylacrylate, trimethylolpropane triacrylate, 1,6-hexanbediol diacrylate, and the like. methyl-1,5-pentanediol diacrylate, 1,10-decanediol diacrylate, tricyclodecanedimethanol diacrylate, pentaerythritol tetraacrylate, ethlyene glycol dimethacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, 1, 10-decanediol dimethacrylate, 1,3-butylene glycol dimethacrylate, tricyclodecanedimethanol dimethacrylate and mixtures thereof, preferably in the group consisting of zinc dimethacrylate, magnesium dimethacrylate, zinc diacrylate, magnesium diacrylate and mixtures thereof.

By way of example, there are commercially available zinc diacrylate derivatives such as zinc diacrylate (ZDA) "Dymalink 633" from Cray Valley or zinc dimethacrylate (ZDMA) "Dymalink 634" from the company Cray Valley, as well as other polyfunctional acrylates such as those of the company SARTOMER: trimethylolpropane trimethacrylate (TMPTMA) "SR351", 1,6-hexanbediol diacrylate (HDDA) "SR238", 3-methyl-1,5 -pentanediol diacrylate (MPDA) "SR341", 1, 10-decanediol diacrylate (DDDA) "SR595", tricyclodecanedimethanol diacrylate (TCDDMDA) "SR833", pentaerythritol tetraacrylate (PETTA) "SR295", trimethylolpropane triacrylate (TMPTA) "SR351", ethlyene glycol dimethacrylate (EGDMA) "SR206", 1,4-butanediol dimethacrylate (BDDMA) "SR214", 1,6-hexanediol dimethacrylate (HDDMA) "SR239", 1,10-decanediol dimethacrylate (DDDMA) "SR261", 1,3-butylene glycol dimethacrylate e (BGDMA) "SR297", tricyclodecanedimethanol dimethacrylate (TCDDMDMA) "SR834".

The masterbatch of the composition according to the invention advantageously comprises from 55 to 85% by weight of the polyfunctional acrylate of formula (I), preferably the zinc diacrylate derivative. More preferably, it comprises from 60 to 80% by weight, preferably from 65 to 80% by weight.

Regardless of the amount of polyfunctional acrylate of formula (I), preferably a zinc diacrylate derivative in the masterbatch, the amount of polyfunctional acrylate of formula (I), preferably of zinc diacrylate derivative, in the composition according to the invention is preferably in a range from 5 to 40 phr, preferably from 5 to 35 phr, preferably from 5 to 30 phr, preferably from 10 to 25 phr. Beyond a rate of 40 phr, the properties of the composition may degrade while below a level of 5 phr, the effect of the polyfunctional acrylate is less noticeable on stiffening and reinforcement.

Those skilled in the art can adapt the amount of polyfunctional acrylate of formula (I) in the masterbatch and the amount of masterbatch to be incorporated in the composition according to the invention to obtain the desired amount of polyfunctional acrylate of formula (l) in the composition according to the invention. II-A-2-b Elastomer of masterbatch

The masterbatch of the composition according to the invention comprises an elastomer. This elastomer may be chosen from the group comprising or consisting of diene elastomers, thermoplastic elastomers and mixtures of these elastomers.

The elastomer of the masterbatch may be of the same nature or of a different nature from the diene elastomer of the composition according to the invention.

For example, the elastomer of the masterbatch may be a diene elastomer as defined above. It can also act of a thermoplastic elastomer as defined in WO 201 1/0861 19, WO 2012/152686 or WO 2016/202645 for example.

By way of example, the elastomer of the masterbatch may be chosen from the group comprising or consisting of polybutadienes, synthetic polyisoprenes, natural rubber, butadiene-styrene copolymers, isoprene copolymers, copolymers ethylene-propylene, ethylene-propylene-diene copolymers, styrene-butadiene-methacrylate terpolymers and mixtures of these elastomers.

Particularly advantageously, the elastomer of the masterbatch mainly comprises, preferably exclusively, a polar elastomer. The polar elastomer may thus be chosen from the group comprising or consisting of a polar diene elastomer, a polar thermoplastic elastomer or a mixture thereof.

The Applicant has in fact unexpectedly realized that the incorporation of polyfunctional acrylate of formula (I) in the form of a masterbatch comprising a polar elastomer makes it possible to further increase the modulus of the composition by in relation to the incorporation of the same polyfunctional acrylate of formula (I) in the form of a masterbatch comprising a non-polar elastomer. For the purposes of the present invention, the term "polar elastomer" is understood to mean a diene or thermoplastic elastomer having a net dipole resulting from opposite charges (that is to say having negative partial and positive partial charges) from polar bonds. arranged asymmetrically. The polar bonds in the polar elastomer may be, for example, bonds between carbon atoms and other atoms having a relatively high electronegativity, such as O, N, F and Cl.

Advantageously, the polar elastomer is chosen from the group consisting of or consisting of epoxidized natural rubbers (ENR), synthetic epoxidized rubber, styrene-butadiene-methyl methacrylate copolymers (SBM), non-hydrogenated nitrile rubbers (NBR). , hydrogenated nitrile rubbers (HNBR), copolymers of ethylene and vinyl acetate (EVA), polylactic acid (PLA), polyhydroxyalkanoates (PHA), polyhydroxybutyrates (PHB), polyhydroxyvalerate (PHV), polyhydroxybutyrate-co-hydroxyvalerate (PHBV), polycaprolactone (PCL), polybutylene succinate (PBS), polyethylene succinate (PES), polybutylene-co-isosorbide terephthalate (PBIT), polyamide-polyether copolymers (PEBAX) and mixtures of these polar elastomers. Particularly advantageously, the polar elastomer is selected from the group comprising or consisting of epoxidized natural rubbers, styrene-butadiene-methyl methacrylate copolymers and mixtures of these polar elastomers.

The masterbatch of the composition according to the invention advantageously comprises from 15 to 45% by weight of elastomer. More preferably, it comprises from 20 to 40% by weight, preferably from 20 to 35% by weight.

The person skilled in the art knows how to adapt the amount of elastomer in the masterbatch and the amount of masterbatch to be incorporated in the composition according to the invention to obtain the desired amount of polyfunctional acrylate of formula (I) in the composition. according to the invention.

II-A-3 Peroxide

The composition according to the invention also comprises a peroxide, which may be any peroxide known to those skilled in the art. Among the peroxides, well known to those skilled in the art, it is preferable to use in the context of the present invention an organic peroxide.

By "organic peroxide" is meant an organic compound, that is to say containing carbon, having a group -O-O- (two oxygen atoms linked by a single covalent bond). During the crosslinking process, the organic peroxide decomposes at its unstable 0-0 bond in free radicals. These free radicals allow the creation of crosslinking bonds

The organic peroxide is preferably selected from the group consisting of or consisting of dialkyl peroxides, monoperoxycarbonates, diacyl peroxides, peroxyketals or peroxyesters.

Preferably, the dialkyl peroxides are selected from the group consisting of or consisting of dicumyl peroxide, di-t-butyl peroxide, t-butylcumyl peroxide, 2,5-dimethyl-2,5-di -butylperoxy) hexane, 2,5-dimethyl-2,5-di (t-amylperoxy) -hexane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3, 2,5-dimethyl-2,5-di (t-butylperoxy) -hexane dimethyl-2,5-di (t-amylperoxy) hexyne-3, n, (x'-di - [(t-butyl-peroxy) isopropyl] benzene, cc, (x'-di - [(t- amylperoxy) isopropyl] benzene, di-t-amyl peroxide, 1,3,5-tri - [(t-butylperoxy) isopropyl] benzene, 1,3-dimethyl-3- (t-butylperoxy) butanol, and 1,3-dimethyl-3- (t-amylperoxy) butanol.

A mixture of dicumyl peroxide and 1,3 and 1,4-isopropylcumyl cumyl peroxide (sold for example by Arkema under the trade name Luperox® DC60) is also of interest.

Certain monoperoxycarbonates such as O-tert-butyl-O- (2-ethylhexyl) monoperoxycarbonate, O-tert-butyl-O-isopropyl monoperoxycarbonate and OO-tert-amyl-O-2-ethyl hexyl monoperoxycarbonate may also be used.

Of the diacyl peroxides, the preferred peroxide is benzoyl peroxide.

Of the peroxyketals, the preferred peroxides are selected from the group consisting of or consisting of 1,1-di- (t-butylperoxy) -3,3,5-trimethylcyclohexane, 4,4-di- (t-butylperoxy) valerate n-butyl, ethyl 3,3-di- (t-butylperoxy) butyrate, 2,2-di- (t-amylperoxy) -propane, 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxynonane (or cyclic methyl ethyl ketone peroxide), the 3,3,5,7,7-pentamethyl-1,2,4-trioxepane, 4,4-bis (t-amylperoxy) n-butyl valerate, 3,3-di (t-amylperoxy) butyrate ethyl, 1,1-di (t-butylperoxy) cyclohexane, 1,1-di (t-amylperoxy) cyclohexane and mixtures thereof. Preferably, the peroxyesters are selected from the group consisting of tert-butylperoxybenzoate, tert-butylperoxy-2-ethylhexanoate and tert-butylperoxy-3,5,5-trimethylhexanoate.

In summary, the organic peroxide is particularly preferably selected from the group consisting of dicumyl peroxide, aryl or diaryl peroxides, diacetyl peroxide, benzoyl peroxide, dibenzoyl peroxide, peroxide. ditertbutyl, tertbutylcumyl peroxide, 2,5-bis (tertbutylperoxy) -2,5-dimethylhexane, n-butyl-4,4'-di (tert-butylperoxy) valerate, 00- (t-butyl) -O- (2-ethylhexyl) monoperoxycarbonate, tert-butyl peroxyisopropylcarbonate, tert-butyl peroxybenzoate, tert-butyl peroxy-3,5,5-trimethylhexanoate, 1,3 (4) -bis (tert-butylperoxyisopropyl) benzene and mixtures thereof, more preferably in the group consisting of dicumyl peroxide, n-butyl-4,4'-di (tert-butylperoxy) -valerate, OO- (t-butyl) O- ( 2-ethylhexyl) monoperoxycarbonate, tert-butyl peroxyisopropylcarbonate, tert-butyl peroxybenzoate, tert-butyl peroxy-3,5,5-trimethylhexanoate, 1,3 (4 ) bis (tert-butylperoxyisopropyl) benzene and mixtures thereof.

There are various packaged products commercially known under their trademarks; we can mention: -the "Dicup" from Hercules Powder Co., the "Perkadox Y12" from Noury van der Lande, the "Peroximon F40" from Montecatini Edison SpA, the "Trigonox" from Noury van der Lande, the "Varox" of the company RTVanderbilt Co., or the "Luperko", the company Wallace & Tiernan, Inc. Preferably, the amount of peroxide to be used in the composition according to the invention, for the needs of the invention is less than or equal to 3 phr. Preferably, the amount of peroxide in the composition according to the invention is in a range from 0.1 to 3 phr. Indeed, below an amount of 0.1 phr, the effect of the peroxide is not noticeable whereas beyond 3 phr, the properties of elongation rupture and therefore resistance of the composition are decreased . More preferably, the amount of peroxide in the composition is in a range from 0.2 to 2.5 phr, preferably from 0.25 to 1.8 phr.

Whatever the amounts of polyfunctional acrylate of formula (I), preferably of zinc diacrylate derivative, and of peroxide in the composition according to the invention, it is preferable that the ratio of the peroxide content to the level of polyfunctional acrylate of formula (I), preferably of zinc diacrylate derivative, in the composition according to the invention is less than or equal to 0.09. Preferably, the ratio of the peroxide content to the level of polyfunctional acrylate of formula (I), preferably of zinc diacrylate derivative, in the composition according to the invention is between 0.01 and 0.09; preferably between 0.03 and 0.09 and more preferably between 0.05 and 0.08.

II-A-4 Reinforcing filler

The diene elastomer, the masterbatch comprising the elastomer and the polyfunctional acrylate of formula (I), preferably the zinc diacrylate derivative, and the peroxide, are sufficient on their own for the invention to be carried out. Nevertheless, the composition of the tire 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 80 phr, preferably less than 65 phr. 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 5 to 60 phr, preferably from 10 to 50 phr.

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. In a particularly advantageous manner, 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. 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 these, the reinforcing carbon blacks of the series 100, 200, 300, or the series blacks 500, 600 or 700 (ASTM grades), for example the blacks N15, N134, N234, N326, will be mentioned more particularly. 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 Ρ / Ρ0: 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, especially any precipitated or fumed silica having a BET surface and a specific surface area CTAB both less than 450 m ² / g, preferably 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 Degussa, the "Zeosil" silicas 1 165MP, 1 135MP and 1 1 15MP of the Rhodia company, the "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, more precisely according to the French standard NF ISO 9277 of December 1996 (multipoint volumetric method (5 points) - gas: nitrogen - degassing: 1 hour at 160 ° C. - relative pressure range p / po: 0.05 to 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 level 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 (in particular alkyltriethoxysilanes), polyols, polyethers (for example polyethylene glycols), primary, secondary or tertiary amines (for example trialkanol amines), hydroxylated or hydrolyzable POSs, for example α, ω-dihydroxy- polyorganosiloxanes (especially α, ω-dihydroxy-polydimethylsiloxanes), fatty acids such as stearic acid.

Regardless of the amounts of polyfunctional acrylate of formula (I), preferably of zinc diacrylate derivative, and of filler in the composition according to the invention, and whatever the nature of the reinforcing filler, it is advantageous for the invention that the ratio of the filler content to the level of the polyfunctional acrylate of formula (I), preferably the zinc diacrylate derivative, in the composition according to the invention is preferably less than or equal to 4. Preferably, the ratio of the degree of charge to the level of polyfunctional acrylate of formula (I), preferably of zinc diacrylate derivative, in the composition according to the invention is preferably The invention is in a range from 0.15 to 3, preferably from 1.5 to 3.

II-A-5 vulcanization system

The composition of the tire according to the invention does not require a vulcanization system, which is one of its advantages since it simplifies the formula and the preparation of the composition. If however a vulcanization system is present in the composition, it is preferably in small amounts. The vulcanization system itself is usually based on sulfur (or a sulfur-donor agent) and a primary vulcanization accelerator. To this basic vulcanization system are added, incorporated during the first non-productive phase and / or during the production phase as described later, various known secondary accelerators or vulcanization activators such as zinc oxide. stearic acid or equivalent compounds, guanidine derivatives (in particular diphenylguanidine).

Molecular sulfur (or equivalently the molecular sulfur donor agents), when it is used, is at a preferential rate of less than 0.5 phr,

Thus, very preferably, the composition does not contain molecular sulfur or sulfur-donor agent as vulcanizing agent or contains less than 0.5 phr, preferably less than 0.3 phr, preferably still less than 0.1 phr. More preferably, the composition of the tire according to the invention does not contain molecular sulfur or sulfur-donor agent as vulcanizing agent.

The vulcanization system of the composition according to the invention may also comprise one or more additional accelerators, for example the compounds of the thiuram family, the zinc dithiocarbamate derivatives, the sulfenamides, the guanidines or thiophosphates. In particular, any compound capable of acting as a vulcanization accelerator for diene elastomers in the presence of sulfur, in particular thiazole type accelerators and their derivatives, thiuram type accelerators, zinc dithiocarbamates, may be used in particular. These accelerators are more preferably selected from the group consisting of 2-mercaptobenzothiazyl disulfide (abbreviated "MBTS"), N-cyclohexyl-2-benzothiazyl sulfenamide (abbreviated "CBS"), N, N-dicyclohexyl-2-benzothiazyl sulphenamide (abbreviated "DCBS"), N-tert-butyl-2-benzothiazyl sulphenamide (abbreviated "TBBS"), N-tert-butyl-2-benzothiazyl sulphenimide (abbreviated "TBSI"), zinc dibenzyldithiocarbamate (in abbreviated "ZBEC") and mixtures of these compounds. Preferably, a primary accelerator of the sulfenamide type is used.

If an accelerator is used, it is at rates such as those practiced by those skilled in the art of vulcanized tire compositions. Nevertheless, the composition of the tire according to the invention is preferably devoid of any vulcanization accelerator.

II-A-6 Other possible additives

The composition according to the invention may optionally comprise all or part of the usual additives usually used in tire elastomer compositions, such as, for example, pigments, protective agents such as anti-ozone waxes, chemical antiozonants, chemical agents and the like. plasticizers (such as a solid hydrocarbon resin (or plasticizing resin), an extender oil (or plasticizing oil), or a mixture of both), anti-fatigue agents, reinforcing resins, acceptors (for example resin phenolic novolak) or methylene donors (eg HMT or H3M).

In particular, the composition according to the invention may also advantageously comprise a metal oxide. The metal oxide may be selected from the group consisting of or consisting of the oxides of Group II, IV, V, VI, VII and VII metals, and mixtures thereof. Preferably, the metal oxide is selected from the group comprising or consisting of oxides of zinc, magnesium, cobalt, nickel and mixtures thereof. More preferably, the metal oxide is a zinc oxide. The level of metal oxide in the composition of the tire according to the invention is advantageously greater than 5 phr. Preferably, this rate is included in a area ranging from 5 to 20 phr, preferably from 7 to 15 phr. As an example of commercially available metal oxides, mention may be made of industrial grade zinc or magnesium oxides from Umicore.

The compositions according to the invention may be prepared for example by any method according to the invention described below.

II-B Process according to the invention and rubber composition obtainable by this process

The present invention also relates to a process for obtaining a rubber composition based on at least one diene elastomer, a peroxide, and a masterbatch comprising an elastomer and a polyfunctional acrylate of formula (I)

[X] _P A (i)

in which :

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, groups aryls and aralkyls, 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) to A,

it being understood that the 2 to 4 radicals X are identical or different;

in which R 1, R ₂ and R ₃ represent independently of each other a hydrogen atom or a C ₇ hydrocarbon group selected from linear, branched or cyclic alkyl groups, aralkyl groups, alkylaryl groups and aryl groups, and optionally interrupted by one or more heteroatoms, R ₂ and R ₃ may together form a non-aromatic ring,

said method comprising the following steps:

II-B-1 Step (a) Preparation of the masterbatch

Step (a) comprises steps of contacting and mixing the polyfunctional acrylate of formula (I), preferably the zinc diacrylate derivative, and the elastomer. Preferably, step (a) comprises a step of incorporating the polyfunctional acrylate of formula (I), preferably zinc diacrylate derivative, into the elastomer of the masterbatch. Step (a) may be carried out in any suitable mixer well known to those skilled in the art, as described for example in WO 97/36724 or WO 99/16600. It may for example be carried out at a temperature ranging from 60 ° C to 200 ° C, preferably at a maximum falling temperature of between 130 ° C and 200 ° C, preferably 130 ° C to 165 ° C. Step (a) may be carried out, for example, for a period of from 2 to 7 minutes, preferably from 3 to 6 minutes. Particularly advantageously, the zinc diacrylate derivative is brought into contact with the elastomer fractionally, that is to say in several times, preferably in 2 to 5 times. For example, the elastomer of the masterbatch can be introduced into a mixer, and a fraction of the polyfunctional acrylate of formula (I), preferably zinc diacrylate derivative, for example a third, can be introduced into the mixer 1 minute after the introduction of the elastomer, then another fraction, for example a third, 1 to 2 minutes later, and a final fraction, for example a third, 1 to 2 minutes later. ll-B-1-a Polyfunctional Acrylate

The polyfunctional acrylate of formula (I), preferably the zinc diacrylate derivative, may be as defined above for the composition according to the invention. In particular, in the polyfunctional acrylate of formula (I), preferably in the zinc diacrylate derivative, R ₁ , R ₂ and R ₃ preferably represent, independently, a hydrogen atom or a methyl group. More preferably, R ₂ and R ₃ each represent a hydrogen atom. More preferably, R 1 represents a methyl group. Even more advantageously, R ₂ and R ₃ each represent a hydrogen atom, and R 1 represents a methyl group. On the other hand, A may represent an atom belonging to the group consisting of alkaline earth metals or transition metals, preferably an atom selected from the group consisting of Zn and Mg. Alternatively, in the polyfunctional acrylate of formula (I), A may represent a hydrocarbon group C1-C13, preferably a hydrocarbon group C1-C10, preferably -C _8, preferably C 1 -C 5. For example, the hydrocarbon group in Ci C ₃ may be selected from the group consisting of the following radicals:

wherein m is an integer from 1 to 13, preferably from 6 to 10, and ( ^* ) represents the point of attachment of A to the radical of formula (II). Moreover, in the polyfunctional acrylate of formula (I), the number of valence p depends on the nature of the radical A. According to the invention, p may be 2, 3 or 4. For example, p may be 2 or 3 for example 2. Advantageously, the polyfunctional acrylate is selected from the group consisting of zinc dimethacrylate, magnesium dimethacrylate, zinc diacrylate, magnesium diacrylate, trimethylopropane trimethylacrylate, trimethylolpropane triacrylate, 1,6-hexanbediol diacrylate, 3-methyl-1, 5-pentanediol diacrylate, 1, 10-decanediol diacrylate, tricyclodecanedimethanol diacrylate, pentaerythritol tetraacrylate, ^the ethlyene giycoi dimethacrylate, 1, 4-butanediol dimethacrylate, 1, 6- hexanediol dimethacrylate, 1,10-decanediol dimethacrylate, 1,3-butylene glycol dimethacrylate, tricyclodecanedimethanol dimethacrylate and mixtures thereof, preferably in the group consisting of zinc dimethacrylate, magnesium acrylate, zinc diacrylate, magnesium diacrylate and mixtures thereof.

The masterbatch of the process according to the invention advantageously comprises from 55 to 85% by weight of the polyfunctional acrylate of formula (I), preferably from zinc diacrylate. More preferably, it comprises from 60 to 80% by weight, preferably from 65 to 80% by weight.

Regardless of the amount of polyfunctional acrylate of formula (I), preferably a zinc diacrylate derivative, in the masterbatch, the amount of polyfunctional acrylate of formula (I), preferably of zinc diacrylate derivative, in the composition obtainable by the process according to the invention is preferably in a range from 5 to 40 phr, preferably from 5 to 35 phr, preferably from 5 to 30 phr, preferably from 10 to 25 phr. pc. ll-B-1-b Elastomer of masterbatch

The elastomer of the masterbatch may be as defined above for the composition according to the invention. In particular, the elastomer of the masterbatch may be chosen from the group comprising or consisting of diene elastomers, thermoplastic elastomers and mixtures of these elastomers. For example, the elastomer of the masterbatch may be a diene elastomer as defined above. It can also act of a thermoplastic elastomer as defined in WO 201 1/0861 19, WO 2012/152686 or WO 2016/202645 for example. By way of example, the elastomer of the masterbatch may be chosen from the group comprising or consisting of polybutadienes, synthetic polyisoprenes, natural rubber, butadiene-styrene copolymers, isoprene copolymers, copolymers ethylene-propylene, ethylene-propylene-diene copolymers, styrene-butadiene-methacrylate terpolymers and mixtures of these elastomers.

Particularly advantageously, the elastomer of the masterbatch mainly comprises, preferably exclusively, a polar elastomer. The polar elastomer may thus be chosen from the group comprising or consisting of a polar diene elastomer, a polar thermoplastic elastomer or a mixture thereof. Advantageously, the polar elastomer is chosen from the group comprising or consisting of epoxidized natural rubbers (ENR), synthetic epoxidized rubber, styrene-butadiene-methyl methacrylate copolymers (SBM), non-hydrogenated nitrile rubbers (NBR). hydrogenated nitrile rubbers (HNBR), copolymers of ethylene and vinyl (EVA), polylactic acid (PLA), polyhydroxyalkanoates (PHA), polyhydroxybutyrates (PHB), polyhydroxyvalerate (PHV), polyhydroxybutyrate-co-hydroxyvalerate (PHBV), polycaprolactone (PCL), polybutylene succinate (PBS), polyethylene succinate (PES), polybutylene-co-isosorbide terephthalate (PBIT), polyamide-polyether copolymers (PEBAX) and mixtures of these polar elastomers. Particularly advantageously, the polar elastomer is selected from the group comprising or consisting of epoxidized natural rubbers, styrene-butadiene-methyl methacrylate copolymers and mixtures of these polar elastomers.

The masterbatch of the process according to the invention advantageously comprises from 15 to 45% by weight of elastomer. More preferably, it comprises from 20 to 40% by weight, preferably from 20 to 35% by weight. II-B-2 Step (b) Preparation of the rubber composition

Step (b) comprises steps of contacting and mixing, concomitantly or sequentially, the masterbatch obtained in step (a), the diene elastomer and the peroxide. Preferably, step (b) comprises the steps of concomitantly or successively incorporating the masterbatch obtained in step (a) and the peroxide into the diene elastomer.

Step (b) can be carried out in any suitable mixer well known to those skilled in the art. This step can be carried out using two successive preparation phases according to a general procedure well known to those skilled in the art: a first phase of work or thermomechanical mixing (sometimes referred to as a "non-productive" phase) at high temperature, up to a maximum temperature of between 110 ° C. and 190 ° C., preferably between 130 ° C. and 180 ° C., followed by a second mechanical working phase (sometimes referred to as a "productive" phase) at a lower temperature , typically below 1 10 ° C, for example between 60 ° C and 100 ° C, finishing phase during which is incorporated the crosslinking system. Such phases have been described for example in the applications EP 0 501 227 A, EP 0 735 088 A, EP 0 810 258 A, WO 2000/05300 or WO 2000/05301.

The first (non-productive) phase is preferably carried out in several thermomechanical steps. During a first step we introduce, in a suitable mixer such as a conventional internal mixer, the diene elastomer, the masterbatch obtained in step (a), optionally one or more reinforcing filler (s) different from the polymeric reinforcing filler, optionally plasticizers (and optionally the coupling agents and / or other ingredients with the exception of the crosslinking system), at a temperature between 20 ° C and 100 ° C and preferably between 25 ° C and 100 ° C. After a few minutes, preferably from 0.5 to 2 min and a rise in temperature to 90 ° C to 100 ° C, the other ingredients (ie, those that remain if all were not put initially) are added at once or in portions, with the exception of the crosslinking system during mixing ranging from 20 seconds to a few minutes. The total mixing time, in this non-productive phase, is preferably between 2 and 10 minutes at a temperature of less than or equal to 180 ° C, and preferably less than or equal to 170 ° C. After cooling the mixture thus obtained, then incorporating the crosslinking system, namely peroxide, at low temperature (typically below 100 ° C), generally in an external mixer such as a roll mill; the whole is then mixed (productive phase) for a few minutes, for example between 5 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 extruded, to form for example a rubber profile used for the manufacture of semi-finished products. finished in order to obtain products such as an inner layer of tire. These products can then be used for the manufacture of tires, according to the techniques known to those skilled in the art.

The crosslinking (or baking) is conducted in a known manner 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 on the cooking temperature , the crosslinking system adopted, the kinetics of crosslinking of the composition in question or the size of the tire. II-B-2-a Diene Elastomer

The diene elastomer of the process according to the invention may be as defined above for the composition according to the invention. It may be of the same or different nature of the elastomer of the masterbatch of the process according to the invention. The diene elastomer of the process according to the invention may be chosen, for example, from the group of highly unsaturated diene elastomers, preferably from the group comprising or consisting of polybutadienes, synthetic polyisoprenes, natural rubber, copolymers of butadiene, isoprene copolymers and mixtures of these elastomers. According to a particular preferential embodiment, the diene elastomer comprises predominantly at least one isoprene elastomer, preferably an isoprene elastomer chosen from the group comprising or consisting of natural rubber, which can be plasticized or peptized, synthetic polyisoprenes, different isoprene copolymers and mixtures of these elastomers.

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 isoprene elastomer, more preferably of natural rubber, is very preferably 100 phr.

Whether it contains a single diene elastomer or a mixture of several diene elastomers, the rubber composition obtainable by the process 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, for example thermoplastic polymers. Preferably, the rubber composition obtainable by the process according to the invention does not contain any synthetic elastomer other than diene or polymer other than elastomers or contains less than 10 phr, preferably less than 5 phr. . ll-B-2-b Peroxide

The peroxide used in the process according to the invention may be any peroxide known to those skilled in the art. Among the peroxides, well known to those skilled in the art, it is preferable to use in the context of the present invention an organic peroxide.

Certain monoperoxycarbonates such as 00-tert-butyl-O- (2-ethylhexyl) monoperoxycarbonate, OO-tert-butyl-O-isopropyl monoperoxycarbonate and OO-tert-amyl-O-2-ethyl hexyl monoperoxycarbonate may also be used.

Of the diacyl peroxides, the preferred peroxide is benzoyl peroxide.

Of the peroxyketals, the preferred peroxides are selected from the group consisting of or consisting of 1,1-di- (t-butylperoxy) -3,3,5-trimethylcyclohexane, 4,4-di- (t-butylperoxy) valerate n-butyl, ethyl 3,3-di- (t-butylperoxy) butyrate, 2,2-di- (t-amylperoxy) -propane, 3,6,9-triethyl-3,6, 9-trimethyl-1, 4,7-triperoxynonane (or cyclic methyl ethyl ketone peroxide), 3,3,5,7,7-pentamethyl-1,2,4-trioxepane, 4,4-bis ( t-amylperoxy) n-butyl valerate, ethyl 3,3-di (t-amylperoxy) butyrate, 1,1-di (t-butylperoxy) cyclohexane, 1,1-di (t-amylperoxy) cyclohexane and mixtures thereof. Preferably, the peroxyesters are selected from the group consisting of tert-butylperoxybenzoate, tert-butylperoxy-2-ethylhexanoate and tert-butylperoxy-3,5,5-trimethylhexanoate.

Preferably, the amount of peroxide to be used for the purposes of the invention is less than or equal to 3 phr. Preferably, the amount of peroxide in the composition is in a range from 0.1 to 3 phr. More preferably, the amount of peroxide in the composition is in a range from 0.2 to 2.5 phr, preferably from 0.25 to 1.8 phr.

Regardless of the quantities of polyfunctional acrylate of formula (I), preferably of zinc diacrylate derivative, and of peroxide, it is preferable that the ratio of the peroxide content to the level of polyfunctional acrylate of formula (I) preferably zinc diacrylate derivative in the rubber composition is less than or equal to 0.09. Preferably, the ratio of the peroxide content to the level of polyfunctional acrylate of formula (I), preferably of zinc diacrylate derivative, in the rubber composition is between 0.01 and 0.09; preferably between 0.03 and 0.09 and more preferably between 0.05 and 0.08. ll-B-2-c Reinforcing filler

The method according to the invention may comprise a step of incorporating reinforcing filler but this is not mandatory. Thus, the method according to the invention can not to include reinforcing charge incorporation step. If the process according to the invention comprises a step of incorporating reinforcing filler, the level of reinforcing filler incorporated to obtain the rubber composition is advantageously less than 80 phr, preferably less than 65 phr, preferably included in a range of from 5 to 60 phr, preferably from 10 to 50 phr.

If the process according to the invention comprises a step of incorporation of reinforcing filler, may be as defined above for the composition according to the invention. In particular, the reinforcing filler 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.

Whatever the amounts of polyfunctional acrylate of formula (I), preferably zinc diacrylate derivative, and filler incorporated in the rubber composition, and whatever the nature of the reinforcing filler, it is advantageous for the invention that the ratio of the filler content to the level of the polyfunctional acrylate of formula (I), preferably the zinc diacrylate derivative, in the rubber composition is less than or equal to 4. Preferably, preferably, the ratio of the filler content and the polyfunctional acrylate of formula (I), preferably the level of zinc diacrylate derivative, in the rubber composition is in a range from 0.15 to 3, preferably from 1, 5 to 3.

The step of incorporating reinforcing filler may advantageously comprise or consist of a step of contacting and mixing the diene elastomer and the reinforcing filler. This step may be carried out previously, concomitantly or successively in step (b) of the process according to the invention. In other words, if the process according to the invention comprises a reinforcing filler incorporation step, the reinforcing filler can be incorporated into the diene elastomer independently before, at the same time or after the masterbatch obtained at the same time. step (a) and the peroxide. ll-B-2-d Vulcanization system

The process according to the invention may comprise a step of incorporating molecular sulfur or sulfur donor agent as a vulcanizing agent but this is not mandatory. Advantageously, the process according to the invention does not comprise a step of incorporation of molecular sulfur or of sulfur donor agent as vulcanizing agent. If the process according to the invention comprises a step of incorporating molecular sulfur or sulfur-donor agent as vulcanizing agent, the level of molecular sulfur or of sulfur-donor agent as vulcanizing agent incorporated to obtain the rubber composition is advantageously less than 0.5 phr, preferably less than 0.3 phr, more preferably less than 0.1 phr.

The step of incorporating the vulcanization system may advantageously comprise or consist of a step of contacting and mixing the diene elastomer and the vulcanization system. This step may be carried out previously, concomitantly or successively in step (b) of the process according to the invention. In other words, if the method according to the invention comprises a step of incorporating the vulcanization system, the vulcanization system can be incorporated in the diene elastomer independently before, at the same time or after the masterbatch obtained at step (a) and the peroxide, and optionally the reinforcing filler. Preferably, the vulcanization system is incorporated after step (b) of the method according to the invention. ll-B-2-e Other possible additives

The method according to the invention may comprise a step of incorporating usual additives usually used in tire elastomer compositions, for example pigments, protective agents such as anti-ozone waxes, chemical antiozonants, plasticizing agents (such as a solid hydrocarbon resin (or plasticizing resin), an extender oil (or plasticizing oil), or a mixture of both), anti-fatigue agents, reinforcing resins, acceptors (for example novolac phenolic resin) or methylene donors (eg HMT or H3M).

In particular, the process according to the invention may also advantageously comprise a step of incorporating a metal oxide. The metal oxide can be chosen in the group consisting of or consisting of the oxides of Group II, IV, V, VI, VII and VIII metals, and mixtures thereof. Preferably, the metal oxide is selected from the group comprising or consisting of oxides of zinc, magnesium, cobalt, nickel and mixtures thereof. More preferably, the metal oxide is a zinc oxide. The level of metal oxide incorporated is advantageously greater than 5 phr. Preferably, this level is in a range from 5 to 20 phr, preferably from 7 to 15 phr.

II-B-3 Rubber composition obtainable by the process according to the invention

The present invention also relates to a rubber composition that can be obtained by a method according to the invention.

The Applicant has in fact surprisingly found that the incorporation of polyfunctional acrylate of formula (I) according to the process according to the invention makes it possible to increase the modulus of the composition compared to a process where the incorporation of the same acrylate polyfunctional of formula (I) is carried out directly in the composition, in particular powder form. ll-C 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 or a composition obtainable by the process according to the invention. It also relates to a tire comprising a composition according to the invention, a composition obtainable by the process 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 inner layers of tire.

Also, in the tire according to the present invention the composition may be present 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, rubber articles, both in the raw state (that is to say, before cooking) and in the cooked state (that is to say, before cooking). after crosslinking or vulcanization).

III- EXAMPLES

111-1 Measurements and tests used

Dynamic properties (after cooking): Tensile test

These tensile tests make it possible to determine the elastic stress and the properties at break. Unless otherwise indicated, they are carried out in accordance with the French standard NF T 46-002 of September 1988. Traction data processing also makes it possible to draw the modulus curve as a function of elongation. The module used here is the nominal secant modulus (or apparent) measured in first elongation, calculated by reducing to the initial section of the specimen. The nominal secant modulus (or apparent stresses, in MPa) is measured at first elongation at 23 ° C. at 10% and 100% elongation respectively denoted M10 and M100.

The rigidity results M 10 and M 100 are presented in "base 100" with respect to the composition Control A. The higher the value, the more rigid the composition. The rupture stress (CR) tests are based on the NF ISO 37 standard of December 2005 on a dumbbell test tube type H2 and are measured at a pulling speed of 500 mm / min. The breaking stress is measured in MPa. The results of CR are presented in "base 100" with respect to the control composition A. The higher the value, the more the composition is cohesive.

All these tensile measurements are carried out under normal conditions of temperature (23 ± 2 ° C.) and hygrometry (50 ± 5% relative humidity), according to the French standard NF T 40-101 (December 1979).

III-2 Preparation of compositions

The masterbatches were prepared in a "Banbury" type internal vane mixer with a working volume of 3.3 liters set to have a tank temperature of 70 ° C, a 75% filling, a rotation pallets of 50 revolutions per minute, for a duration of about 4 minutes to a maximum temperature of 140 ° C. The elastomer of the masterbatch was introduced at t = 0, and the zinc diacrylate derivative introduced gradually after one to three minutes, so that the final amount of the zinc diacrylate derivative in the masterbatch was 75% by weight.

The rubber compositions tested were prepared by introducing the diene elastomer into a "Banbury" type internal mixer with a working volume of 3.3 liters, and then incorporating the zinc diacrylate derivative in the form of a powder (control). ) in the form of a masterbatch (compositions according to the invention) and the reinforcing filler (carbon black), at a temperature of about 90 ° C and a rotation of the pallets of 50 revolutions per minute. After 2 minutes and a rise in temperature to about 110 ° C, the metal oxide (ZnO) was incorporated. The total mixing time was about 4 minutes to reach a maximum temperature of 160 ° C. After cooling the mixture thus obtained to a temperature of 40 ° C, the crosslinking system (peroxide) was incorporated; the whole is then mixed for about 5 minutes.

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. The The crosslinking was then carried out at a temperature of about 160 ° C, under pressure, for 30 minutes.

III-3 Rubber Tests

The examples presented in Table 1 are intended to compare the different properties of compositions according to the invention (C1 to C5) with a control composition T which differs from the compositions according to the present invention in that the zinc diacrylate derivative is incorporated in powder form not in the form of a masterbatch.

Table 1

(1) ASTM N326 grade carbon black (Cabot company)

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

(3) Dicumyl peroxide "Dicup" from the company Hercules

(4) Zymethyl dimethacrylate (ZDMA) "DYMALINK 634" from the company CRAY VALLEY

(5) Masterbatch containing 75% by weight (20 phr) of (4) and 25% by weight (6.6 phr) of EPM containing 65% of ethylene sold under the name Vistalon 706 by the company Exxon Mobil

(6) Masterbatch Containing 75% by weight (20 phr) of (4) and 25% by weight (6.6 phr) of natural rubber

(7) Masterbatch Containing 75% by Weight (20 phr) of (4) and 25% by Weight (6.6 phr) of SBR 23% Styrene Solution

(8) Masterbatch Containing 75% by weight (20 phr) of (4) and 25% by weight (6.6 phr) of epoxidized natural rubber (ENR) at 25% epoxidation

(9) Masterbatch Containing 75% by weight (20 phr) of (4) and 25% by weight (6.6 phr) of copolymer Styrene (13%) - Butadiene (45%) - Methyl methacrylate (42%) ( SBM) marketed under the name Nanostrengh A012 by the company Arkema

These results show that the compositions in accordance with the invention all make it possible to improve the rigidity of the compositions, while maintaining a satisfactory level of cohesion, whatever the nature of the elastomer of the masterbatch. The compositions according to the invention and using a polar elastomer (ENR, SBM in particular) in the masterbatch show particularly remarkable levels of rigidity.

Claims

1. Rubber composition based on at least:

a diene elastomer,

a peroxide,

a masterbatch comprising an elastomer and a polyfunctional acrylate of formula (I)

[X] _P A m

in which :

in which,

^■ ^(*) represents the point of attachment of the radical of formula (II) A, o it being understood that the 2 to 4 radicals X are identical or different.

The rubber composition according to claim 1, wherein the diene elastomer is selected from the group consisting of polybutadienes, synthetic polyisoprenes, natural rubber, butadiene copolymers, isoprene copolymers and mixtures thereof. elastomers.

3. A rubber composition according to claim 1 or 2, wherein the diene elastomer comprises predominantly at least one isoprene elastomer.

The rubber composition of claim 3, wherein the isoprene elastomer is selected from the group consisting of natural rubber, synthetic polyisoprenes and mixtures of these elastomers.

The rubber composition according to any one of claims 1 to 4, wherein A represents an atom selected from the group consisting of Zn and Mg.

6. Composition according to any one of claims 1 to 4, wherein p is 2 or 3, preferably 2.

The rubber composition according to any one of claims 1 to 5, wherein the polyfunctional acrylate of formula (I) is a zinc diacrylate derivative in the form of a zinc salt of formula (III)

in which R 1, R ₂ and R ₃ represent independently of each other a hydrogen atom or a C ₇ hydrocarbon group selected from linear, branched or cyclic alkyl groups, aralkyl groups, alkylaryl groups and aryl groups, and optionally interrupted by one or more heteroatoms, R ₂ and

R ₃ may together form a non-aromatic ring.

The rubber composition according to any one of claims 1 to 4, wherein A represents a C1-C13 hydrocarbon group selected from group

The rubber composition according to any one of claims 1 to 8, wherein R 1, R ₂ and R ₃ independently represent a hydrogen atom or a methyl group.

The rubber composition according to any one of claims 1 to 9, wherein R ₂ and R ₃ each represent a hydrogen atom.

The rubber composition according to any one of claims 1 to 10, wherein R 1 is a methyl group.

The rubber composition according to any one of claims 1 to 4, wherein the polyfunctional acrylate is selected from the group consisting of zinc dimethacrylate, magnesium dimethacrylate, zinc diacrylate, magnesium diacrylate, trimethylopropane trimethylacrylate, trimethylolpropane triacrylate, 1,6-hexanbediol diacrylate, 3-methyl-1,5-pentanediol diacrylate, 1,10- decanediol diacrylate, tricyclodecanedimethanol diacrylate, pentaerythritol tetraacrylate, ethlyene glycol dimethacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,10-decanediol dimethacrylate, 1,3-butylene glycol dimethacrylate, tricyclodecanedimethanol dimethacrylate and mixtures thereof, preferably in the group consisting of zinc dimethacrylate, magnesium dimethacrylate, zinc diacrylate, magnesium diacrylate and mixtures thereof.

13. A rubber composition according to any one of claims 1 to 12, wherein the masterbatch comprises 55 to 85% by weight, preferably 60 to 80% by weight, of polyfunctional acrylate of formula (I) preferably zinc diacrylate derivative.

The rubber composition according to any of claims 1 to 13, wherein the amount of polyfunctional acrylate of formula (I), preferably zinc diacrylate derivative, in the composition is in a range from at 40 parts by weight per hundred parts by weight of elastomer, preferably from 5 to 35 phr.

15. A rubber composition according to any one of claims 1 to 14, wherein the elastomer of the masterbatch is selected from the group consisting of diene elastomers, thermoplastic elastomers and mixtures of these elastomers.

16. A rubber composition according to any one of claims 1 to 15, wherein the elastomer of the masterbatch comprises predominantly a polar elastomer.

The rubber composition according to claim 16, wherein the polar elastomer is selected from the group consisting of epoxidized natural rubbers, epoxidized synthetic rubbers, styrene-butadiene-methyl methacrylate copolymers, non-hydrogenated nitrile rubbers, hydrogenated nitrile rubbers, copolymers of ethylene and vinyl acetate, polylactic acid, polyhydroxyalkanoates, polyhydroxybutyrates, polyhydroxyvalerate, polyhydroxybutyrate-co-hydroxyvalerate, polycaprolactone, polybutylene succinate, polyethylene succinate, polybutylene-co-isosorbide terephthalate, polyamide-polyether copolymers and mixtures thereof. polar elastomers.

Rubber composition according to any one of claims 1 to 17, wherein the masterbatch comprises from 15 to 45% by weight of elastomer, preferably from 20 to 40% by weight.

The rubber composition according to any one of claims 1 to 18, wherein the peroxide is an organic peroxide.

The rubber composition according to claim 19, wherein the organic peroxide is selected from the group consisting of dicumyl peroxide, aryl or diaryl peroxides, diacetyl peroxide, benzoyl peroxide, dibenzoyl peroxide. , ditertbutyl peroxide, tertbutylcumyl peroxide, 2,5-bis (tertbutylperoxy) -2,5-dimethylhexane, n-butyl-4,4'-di (tert-butylperoxy) valerate, 00- (t -butyl) -O- (2-ethylhexyl) monoperoxycarbonate, tert-butyl peroxyisopropylcarbonate, tert-butyl peroxybenzoate, tert-butyl peroxy-3,5,5-trimethylhexanoate, 1,3 (4) -bis (tert -butylperoxyisopropyl) benzene and mixtures thereof, more preferably in the group consisting of dicumyl peroxide, n-butyl-4,4'-di (tert-butylperoxy) -valerate, OO- (t-butyl) 0- (2-ethylhexyl) monoperoxycarbonate, tert-butyl peroxyisopropylcarbonate, tert-butyl peroxybenzoate, tert-butyl peroxy-3,5,5-trimethylhexanoate , 1,3 (4) -bis (tert-butylperoxyisopropyl) benzene and mixtures thereof.

21. A rubber composition according to any one of claims 1 to 20, wherein the amount of peroxide in the composition is less than or equal to 3 phr.

22. A rubber composition according to any one of claims 1 to 21, wherein the amount of peroxide in the composition is in a range from 0.1 to 3 phr, preferably from 0.2 to 2.5 phr .

23. A rubber composition according to any one of claims 1 to 22, wherein the ratio of the peroxide level to the level of polyfunctional acrylate of formula (I), preferably of zinc diacrylate derivative, in the composition is less than or equal to 0.09, preferably between 0.01 and 0.09.

24. A rubber composition according to any one of claims 1 to 23, said composition comprising no reinforcing filler or comprising less than 65 phr.

25. A rubber composition according to claim 24, wherein the level of reinforcing filler is in a range from 5 to 60 phr, preferably from 10 to 50 phr.

26. A rubber composition according to claim 24 or 25, wherein the reinforcing filler predominantly consists of carbon black.

A rubber composition according to any one of claims 24 to 26, wherein the ratio of the filler content to the level of polyfunctional acrylate of formula (I), preferably zinc diacrylate derivative, in the composition is less than or equal to 4, preferably in a range from 0.15 to 3.

28. A rubber composition according to any one of claims 1 to 27, wherein the composition does not contain molecular sulfur or sulfur donor agent as vulcanizer or contains less than 0.5 phr.

29. A rubber composition according to any one of claims 1 to 28, wherein the composition does not contain molecular sulfur or sulfur donor agent as vulcanizer or contains less than 0.3 phr. preferably less than 0.1 phr.

30. Process for obtaining a rubber composition based on at least one diene elastomer, a peroxide, and a masterbatch comprising an elastomer and a polyfunctional acrylate of formula (I)

[X] _P A (i) in which :

in which,

^■ ^(*) represents the point of attachment of the radical of formula (II) A,

o it being understood that the 2 to 4 radicals X are identical or different, said method comprising the following steps:

(a) contacting and mixing the polyfunctional acrylate of formula (I) and the elastomer to form a masterbatch,

31. The method of claim 30, wherein the composition is as defined in any one of claims 1 to 23.

32. The method of claim 30 or 31, not including step of incorporating reinforcing filler.

33. The method of claim 30 or 31, comprising a step of incorporating a reinforcing filler as defined in any one of claims 24 to 27.

34. Process according to any one of claims 30 to 33, not including a step of adding molecular sulfur or sulfur-donor agent as vulcanizing agent.

35. A process according to any of claims 30 to 33, comprising a step of incorporating molecular sulfur or sulfur donor agent as a vulcanizing agent as defined in claim 28 or 29.

36. A rubber composition obtainable by a process defined in any one of claims 30 to 35.

37. A finished or semi-finished rubber article comprising a rubber composition according to any one of claims 1 to 29 or 36.

38. A tire comprising a rubber composition according to any one of claims 1 to 29 or 36, or a semi-finished rubber article according to claim 37.

Tire according to claim 38, wherein the rubber composition according to any one of claims 1 to 29 or 36 is present in at least one inner layer.

40. A tire according to claim 39, wherein the inner layer is selected from the group consisting of carcass plies, crown plies, bead fences, toe feet, decoupling layers, edging, tamping gums, tread underlayer and combinations of these inner layers.