WO2012140259A1

WO2012140259A1 - Rubber composition comprising a thiophene derivative

Info

Publication number: WO2012140259A1
Application number: PCT/EP2012/056913
Authority: WO
Inventors: Anne Veyland; Nicolas Seeboth; Mikhail Mikhailovitch KRAYUSHKHIN
Original assignee: Compagnie Generale Des Etablissements Michelin; Michelin Recherche Et Technique S.A.
Priority date: 2011-04-14
Filing date: 2012-04-16
Publication date: 2012-10-18
Also published as: CN103608190A; FR2974100B1; FR2974100A1; CN103608190B

Abstract

The invention relates to the use of one or more thiophene compounds having formula (I) as a vulcanisation accelerator in a composition containing one or more diene elastomers, one or more reinforcing fillers and a vulcanisation system. The invention also relates to a rubber composition for the production of tyres, comprising one or more specific thiophene compounds, as well as specific thiophene derivatives.

Description

Rubber composition comprising a thiophene derivative

The present invention relates to the use as a vulcanization accelerator in a composition of a particular thiophene compound, as well as to a rubber composition that can be used in particular for the manufacture of tires or semi-finished products for tires such as belts. tread, said composition being based on a diene elastomer, a reinforcing filler and a vulcanization system comprising a particular thiophene compound.

The vulcanization of diene elastomers by sulfur is widely used in the rubber industry, in particular that of the tire. In order to vulcanize the diene elastomers, a relatively complex vulcanization system comprising, in addition to sulfur, a primary vulcanization accelerator, such as sulphonamides with a benzothiazole nucleus, as well as various secondary accelerators or vulcanization activators, in particular zinc such as zinc oxide (ZnO) alone or used with fatty acids.

Benzothiazole ring sulfenamides used as primary accelerators for vulcanization are, for example, N-cyclohexyl-2-benzothiazyl sulphenamide (abbreviated as "CBS"), N, N-dicyclohexyl-2-benzothiazyl sulphenamide (abbreviated "DCBS"), N-tert-butyl-2-benzothiazyl sulfenamide (abbreviated as "TBBS") and mixtures of these compounds.

As a primary accelerator of vulcanization, 2- (1,3-benzothiazol-2-ylthio) -1,3-benzothiazole (abbreviated as "METS") is also known.

The rubber compositions must have sufficient crosslinking while maintaining an acceptable compromise between the different rheometric properties.

In response to this problem, the Applicant has discovered a novel rubber composition comprising a thiophene compound as a vulcanization accelerator. This new composition of Rubber provides a vulcanized composition using accelerators alternative to known accelerators, ideally with a compromise of rheometric properties similar to that obtained with rubber compositions containing vulcanization accelerators conventionally used.

The object of the invention is therefore to use, as a vulcanization accelerator in a composition based on one or more diene elastomers, one or more reinforcing fillers and a vulcanization system, one or more thiophene compounds. chosen from the following compounds of formula (I) and (II):

in which

R, R 1 and R ₂ represent, independently of one another, a hydrogen atom, a halogen atom, a thiol, hydroxyl or amino group, or a C ₁ -C 25 hydrocarbon-based group chosen from linear alkyl groups, branched or cyclic, saturated or unsaturated aralkyl groups, alkylaryl groups and aryl groups, and optionally interrupted by one or more heteroatoms and / or optionally substituted with one or more halogen atoms and / or optionally substituted by one or more functions thiol, hydroxyl, amino; R and R] or Ry and R ₂ may together form an aromatic ring or not,

-A represents a group selected from

a hydrogen atom,

- a group

* 12

in which R ₁₂ represents:

alkyl, C] -C ₂₅ linear or branched, optionally interrupted by one or more heteroatoms, optionally substituted with one or more cyclic alkyl C3 ₁ 0 aryl or C ₆ -C _12, or

- a cyclic alkyl C3-C10, optionally interrupted by one or more heteroatoms, optionally substituted by one or more linear alkyl groups, branched or cyclic C ₂ -C 5 or aryls C ₆ -C ₂ optionally interrupted by a or more heteroatoms;

- a gr

in which

R _c is identical to R, Ri _c is identical to R _ls R _2c is identical to

R ₂ ,

x denotes integer greater than or equal to 1, preferably less than or equal to 10, more preferably less than or equal to 8 and most preferably less than or equal to 6;

- a group

in which

R ₃ , R 4 and R 5 independently represent a hydrocarbon group d-Cis, optionally interrupted by one or more heteroatoms,

y is an integer greater than or equal to 1, preferably less than or equal to 10, more preferably less than or equal to 8 and most preferably less than or equal to 6;

- a group

in which

R ₆ denotes a hydrocarbon group in

optionally interrupted by one or more heteroatoms;

- a gro

in which

R ₇ denotes a C ₁ -C 18 hydrocarbon group, optionally interrupted by one or more heteroatoms;

in which Y represents a C 1 -C 18 hydrocarbon-based chain, optionally interrupted or substituted by one or more heteroatoms,

Rg denotes a C1-C18 hydrocarbon group, optionally interrupted by one or more heteroatoms; a group

) R ₉

in which

X represents a C ₁ -C ₁₈ hydrocarbon-based chain, optionally interrupted or substituted with one or more heteroatoms,

R1 and R10 denote a C1-C18 hydrocarbon group, optionally interrupted by one or more heteroatoms; a gr

in which

R 1 1 denotes a hydrogen atom, a C 1 -C 18 hydrocarbon group, optionally interrupted by one or more heteroatoms;

M ^{n +} represents a metallic or non-metallic cation,

n represents an integer varying between 1 and 4.

In the foregoing and the following formulas, the arrow (H) denotes the point of attachment of the groups A and A _has on the sulfur atom, respectively of the formulas (I), (Ib) and (F). The invention also relates to a method for preparing a composition as defined above for the manufacture of tires comprising the following steps:

- Incorporating into a diene elastomer, during a first step, the reinforcing fillers or by thermomechanically kneading the whole, in one or more times, to reach a maximum temperature of between 1 10 ° C and 190 ° C ;

- Then incorporate, during a second step, the crosslinking system and knead the whole to a maximum temperature below 1 10 ° C.

Preferably, the invention relates to the process as defined above, wherein between the thermomechanical mixing and the incorporation of the crosslinking system, the whole is cooled to a temperature of less than or equal to 100 ° C. Preferably in this case, the last step is performed on a second mixer.

Another subject of the invention is the use of a composition as defined above for the manufacture of a finished article or of a semi-finished product intended for a motor vehicle ground connection system, such as a tire, internal safety support for tire, wheel, rubber spring, elastomeric joint, other suspension and anti-vibration element. In particular, the composition according to the invention can be used for the manufacture of semi-finished rubber products intended for tires, such as treads, crown reinforcing plies, sidewalls, reinforcing plies. carcases, beads, guards, underlays, rubber blocks and other internal gums, including decoupling erasers, intended to provide the connection or interface between the aforementioned zones of the tires.

The invention further relates to a finished article or semifinished product for a ground connection system of a motor vehicle, in particular tires and semi-finished products for tires, in particular treads, comprising a composition as defined previously. The tires according to the invention are particularly intended for passenger vehicles, two-wheelers, as for industrial vehicles chosen from vans, "heavy goods vehicles" - ie metros, buses, road transport vehicles (trucks, tractors, trailers ), off-the-road vehicles, agricultural or civil engineering machinery, aircraft, other transport or handling vehicles.

The invention also relates to a rubber composition for the manufacture of tires, based on one or more diene elastomers, one or more reinforcing fillers and a vulcanization system, said vulcanization system comprising one or more thiophene compounds chosen from the compounds of formula (Ib) below:

in which

Rb, R ib and R ₂ b independently of one another, a hydrogen atom, a halogen atom, thiol, hydroxyl, amino or a hydrocarbon group of C 1 - C25 chosen from linear alkyl groups , branched or cyclic, saturated or unsaturated aralkyl groups, alkylaryl groups and aryl groups, and optionally interrupted by one or more heteroatoms and / or optionally substituted with one or more halogen atoms and / or optionally substituted with one or more thiol, hydroxyl, amino functions; R¾ and R b or R ₂ b and Rib may together form an aromatic or unsaturated ring,

-Ab represents a group selected from

- a group

wherein R ₂ b represents:

a C1-C25 linear or branched, optionally interrupted by one or more heteroatoms, optionally substituted with one or more cyclic alkyl C3 0 or aryls C ₆ -C _2, or

a C ₃ -C ₁₀ cyclic alkyl group, optionally interrupted by one or more heteroatoms, optionally substituted by one or more linear, branched or cyclic C 1 -C ₂₅ or C ₆ -C ₁₂ aryl groups, optionally interrupted by a or more heteroatoms; grou

in which

R ₃ b, R ₄ b and R ₅ b independently represent a C ₁ -C 18 hydrocarbon group, optionally interrupted by one or more heteroatoms,

y _b is an integer greater than or equal to 1, preferably less than or equal to 10, more preferably less than or equal to 8 and most preferably less than or equal to 6;

in which R ₆ b denotes a C ₁ -C ₁₈ hydrocarbon group, optionally interrupted by one or more heteroatoms;

- a group

in which

R _7b denotes a C 1 -C ₈ hydrocarbon group, optionally interrupted by one or more heteroatoms;

- a group

O

in which

Y _b represents a C 1 -C 4 hydrocarbon-based chain optionally interrupted or substituted by one or more heteroatoms;

R _8b denotes a hydrocarbon group-C _18, optionally interrupted by one or more heteroatoms;

- a group

- X _b -fj'-OR _i o _b

o

in which

b represents a hydrocarbon chain-C _18, optionally interrupted or substituted by one or more heteroatoms;

R _9b and Rio _b denote a C ₁ -C ₈ hydrocarbon group, optionally interrupted by one or more heteroatoms; - a group

in which

Ri ib denotes a hydrogen atom, a Ci-Ci g hydrocarbon group, optionally interrupted by one or more heteroatoms.

The invention finally relates to a thiophene of the following formula:

(Γ)

in which

R _a , Ria and R _2a represent, independently of one another, a hydrogen atom, a halogen atom, a thiol, hydroxyl or amino group, or a C 25 -C 25 hydrocarbon-based group chosen from linear, branched alkyl groups; or cyclic, saturated or unsaturated aralkyl groups, alkylaryl groups and aryl groups, and optionally interrupted by one or more heteroatoms and / or optionally substituted with one or more halogen atoms and / or optionally substituted with one or more thiol functions , hydroxyl, amino, R _a and Ri _a or Ri _a and R _2a may together form an aromatic ring or not,

-A _a represents

- a G

he

wherein R _12a represents;

alkyl, Ci-Cio linear or branched, optionally interrupted by one or more heteroatoms, optionally substituted with one or more cyclic alkyl groups, C3-C ₁₀ aryl or C ₆ -C _2, or

- a cyclic alkyl C3-C10, optionally interrupted by one or more heteroatoms, optionally substituted by one or more linear alkyl groups, branched or cyclic C 1 -C 25 aryl or C ₆ -C ₂ optionally interrupted by one or more heteroatoms,

it being understood that R _a and R _la , and R _la and R _2a can not form a ring combination, and

R _a and R _2a do not simultaneously represent, respectively, a chlorine atom and an acetyl group;

- a group

in which R _3a , R _4a and R _5a independently represent a C 1 -C 18 hydrocarbon group, optionally interrupted by one or more heteroatoms,

y _a is an integer greater than or equal to 1, preferably less than or equal to 10, more preferably less than or equal to 8 and most preferably less than or equal to 6; group

in which R _7a denotes a d-Cig hydrocarbon group, optionally interrupted by one or more heteroatoms, at the provided that R _2a denotes a C 1 -C 18 hydrocarbon group which does not contain a heteroatom,

- a

in which

X _a is a C 1 -C 4 hydrocarbon chain, optionally interrupted or substituted by one or more heteroatoms, but which can not carry another phosphonate group,

R9a and Rioa independently represent a C1-C15 hydrocarbon group, optionally interrupted by one or more heteroatoms.

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

I. Measurements and tests used

The rubber compositions, in which the thiophene vulcanization accelerators are tested, are characterized, before and after firing, as indicated below.

rheometry

The measurements are carried out at 150 ° C. with an oscillating chamber rheometer according to DIN 53529 - Part 3 (June 1983). The evolution of the rheometric torque, ACouple (in dN.m), as a function of time describes the evolution of the stiffening of the composition as a result of the vulcanization reaction. Measurements are processed according to DIN 53529 - Part 2 (March 1 983) (with the exception of the conversion rate constant): T ₀ is the induction time, ie the time required at the beginning of the vulcanization reaction; T _a (by example T99) is the time required to reach a conversion of a%, that is to say ct% (for example 99%) of the difference between the minimum and maximum couples.

The conversion rate constant denoted by K (expressed in min ^-1 ), of order 1, calculated between 30% and 80% of conversion, which makes it possible to evaluate the kinetics of vulcanization, is also measured. measuring the slope of the rise in torque on the cooking rheogram at 150 ° C. II, Implementation conditions of the invention

As explained above, the composition comprising the vulcanization accelerators used according to the invention and the composition according to the invention are based on one or more diematic elastomers, one or more reinforcing fillers and a vulcanization system.

By the term "composition based on" is meant 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 with one another, at least partly, during the various phases of manufacture of the composition, in particular during its vulcanization.

In the present description, unless expressly indicated otherwise, all percentages (%) are% by weight. 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 that any range of values designated by the expression "from a to b" means the range of values from a to b (that is, including the strict limits a and b). II- 1. Diene elastomer

By elastomer or "diene" rubber, must be understood in known manner an elastomer derived at least in part (i.e., a homopolymer or a copolymer) of monomers dienes (monomers bearing two carbon-carbon double bonds, conjugated or not ).

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% (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 referred to 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 be used in the compositions according to the invention or comprising the vulcanization accelerators used 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, such as, 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, those 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- 3-butadiene, aryl-1,3-butadiene, 1,3-pentadiene, 2,4-hexadiene. Examples of suitable vinylaromatic compounds are 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 may be for example block, statistical, sequence, microsequential, and be prepared in dispersion, in emulsion 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 link C-Sn 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 or WO 2008/141702), alkoxysilane groups (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 6,815,473, WO 2004/096865 or US 2006/0089445). ) or polyether groups (as described for example in EP 1 127 909, US 6,503,973 WO 2009/000750 or 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.

Suitable polybutadienes and in particular those having a content (mol%) in units-1,2 of between 4% and 80% or those having a content (mol%) in cis-1,4 of greater than 80%, polyisoprenes, copolymers of butadiene-styrene and in particular those having a Tg (glass transition temperature (Tg, measured according to ASTM D341 8) of between 0 ° C. and -70 ° C. and more particularly between -10 ° C. and -60 ° C. , a styrene content of between 5% and 60% by weight and more particularly between 20% and 50%, a content (mol%) of -1,2 bonds of the butadiene part of between 4% and 75%, a content of (mol%) in trans-1,4 bonds between 10% and 80%, copolymers of butadiene-isoprene and in particular those having an isoprene content of between 5% and 90% by weight and a Tg of -40 ° At -80 ° C., the isoprene-styrene copolymers and in particular those having a styrene content of between 5% and 50% by weight and a Tg co between 5 ° C. and -50 ° C. In the case of butadiene-styrene-isoprene copolymers, those having a styrene content of between 5% and 50% by weight and more particularly between 10% and 40% are especially suitable. an isoprene content of between 15% and 60% by weight and more particularly between 20% and 50%, a butadiene content of between 5% and 50% by weight and more particularly between 20% and 40%, a content (mol%) in units - 1, 2 of the butadiene part of between 4% and 85%, a content (mol%) in trans - 1,4 units of the butadiene part included between 6% and 80%, a content (mol%) in units - 1, 2 plus -3, 4 of the isoprene part of between 5% and 70% and a content (mol%) in trans - 1, 4 units of the isoprenic portion of between 10% and 50%, and more generally any butadiene-styrene-isoprene copolymer having a Tg between -5 ° C and -70 ° C.

In summary, the diene elastomer of the composition according to the invention or comprising vulcani zation accelerators used according to ^the invention are preferably selected from the group of highly unsaturated diene el astomères 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) and copolymers of soprene-butadiene-styrene (SBIR).

According to a method of realization, the diene elastomer is natural rubber.

According to another particular embodiment, the diene elastomer is predominantly (Le., For more than 50 phr) an SBR, whether it is an emulsion prepared SBR ("ESBR") or an SBR prepared in solution ("SSBR"), or a blend (mixture) SBR / BR, SBR / NR (or SBR / IR), BR / NR (or BR / IR), or SBR / BR / NR (or SBR / BR / IR). In the case of an SBR elastomer (ESBR or SSBR), an SBR having a mean styrene content, for example between 20% and 35% by weight, or a high styrene content, for example 35% by weight, is used in particular. at 45%, a vinyl content of the butadiene part of between 15% and 70%, a content (mol%) of 1,4-trans-1,4 bonds of between 15% and 75% and a Tg of between -1 0 ° C and - 55 ° C; such an SBR can be advantageously used in mixture with a BR preferably having more than 90% (mol%) of cis-1,4 bonds.

According to another particular embodiment, the diene elastomer is predominantly (for more than 50 phr) an isoprene elastomer. This is particularly the case when the compositions of the invention are intended to constitute, in tires, the rubber matrices of certain treads (for example for industrial vehicles), crown reinforcing plies (for example work webs, protective webs or hoop webs), carcass reinforcement plies, flanks, beads, protectors, underlayments, rubber blocks and other internal gums providing the interface between aforementioned areas of the tires.

By "soprene elastomer" is meant in known manner a homopolymer or copolymer of isoprene, in other words a diene elastomer selected from the group consisting of natural rubber (NR), polyisoprene synthesis (1R) , the various isoprene copolymers and the mixtures of these elastomers. Among the isoprene copolymers, mention will be made in particular of isobutene-isoprene (butyl rubber-TIR), isoprene-styrene (S-IR), isoprene-butadiene (BIR) or isoprene-butadiene-copolymers. styrene (SBIR). This isoprene elastomer is preferably natural rubber or a synthetic cis-1,4 polyisoprene; of these synthetic polyisoprenes, polyisoprenes having a content (mol%) of cis-1,4 bonds greater than 90% are preferred, more preferably! still more than 98%.

According to another particular embodiment, particularly when it is intended for a tire sidewall, a tubeless tire sealing inner liner (or other impervious element air), the composition according to the invention or comprising the Vulcanization accelerators used according to the invention may contain at least one substantially saturated diene elastomer, in particular at least one EPDM copolymer or a butyl rubber (optionally chlorinated or brominated), which these copolymers are used alone or in mixture with highly unsaturated diene elastomers as mentioned above, especially NR or TR, BR or SBR.

According to another preferred embodiment of the invention, the rubber composition comprises a blend of one (or more) diene elastomers called "high Tg" having a Tg between -70 ° C and 0 ° C and d one (or more) diene elastomers, called "low Tg", of between -1 10 ° C and -80 ° C, more preferably between -105 ° C and -90 ° C. The high Tg elastomer is preferably selected from the group consisting of S-SBR, E-SBR, natural rubber, synthetic polyisoprenes (having a molar ratio (% molar) of C 1 -C 4 preferably greater than 95%), B IR, SIR, SBIR, and mixtures of these elastomers. The low-level eletomer Tg preferably comprises butadiene units at a level (mol%) of at least 70%; it consists preferably of a polybutadiene (BR) having a content (mol%) of cis-1,4 chains greater than 90%.

According to another particular embodiment of the invention, the rubber composition comprises, for example, from 30 to 100 phr, in particular from 50 to 100 phr, of a high Tg elastomer in a blend with 0 to 70 phr, in particular from 0 to 50 phr, of a low T elastomer; according to another example, it comprises for all 100 pce one or more SBR prepared (s) in solution.

According to another particular embodiment of the invention, the diene elastomer of the composition according to the invention or comprising the vulcanization accelerators used according to the invention comprises a cutting of a BR (as low elastomer Tg). having a content (mol%) of cis-1,4 chains higher than 90%, with one or more S-SBR or E-SBR (as elastomer (s) high Tg).

The composition according to the invention or comprising the vulcanization accelerators used according to the invention may contain a single diene elastomer or a mixture of several diene elastomers, the diene elastomer (s) possibly being used in combination with any type of synthetic elastomer other than diene, or even with polymers other than elastomers, for example thermoplastic polymers. II-2. Reinforcing charge

Any type of reinforcing filler known for its ability to reinforce a rubber composition that can be used for manufacturing tires, for example an organic filler such as carbon black, a reinforcing inorganic filler such as silica, or a cutting of these two types of filler, including a cut of carbon black and silica.

Suitable carbon blacks are all carbon blacks, especially blacks of the HAF, ISAF, SAF type conventionally used in tires (so-called pneumatic grade blacks). Among the latter, mention will be made more particularly of reinforcing carbon blacks of the 100, 200 or 300 series (ASTM grades), for example blacks NI 15, N 34, N 234, N 326, N 30 O, N 339, N 347, N 370, or else , depending on the intended applications, blacks of higher series (for example N660, N683, N772). The carbon blacks could for example already be incorporated into the isoprene elastomer in the form of a masterbatch (see for example WO 97/36724 or WO 99/16600).

As examples of organic fillers other than carbon blacks, mention may be made of the organic functionalized polyvinyl aromatic fillers as described in applications WO-A-2006/069792 and WO-A-2006/069793.

By "reinforcing inorganic filler" is meant in the present application, by definition, any inorganic or mineral filler (whatever its color and origin (natural or synthetic), also called "white" filler, area "even""non-blackfiller" 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 tires, in other words capable of replacing, in its reinforcing function, 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.

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 below.

Suitable reinforcing inorganic fillers are in particular mineral fillers of the siliceous type, in particular silica (SiO ₂ ), or of the alumincusc type, in particular alumina (Al ₂ O ₃ ). 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. As highly dispersible precipitated silicas (so-called "HDS"), there may be mentioned, for example, the silicas Ultrasil 7000 and Ultrasil 7005 from the company Degussa, the silicas Zeosil 1 165MP, 1 1 35MP and 1 1 1 5MP from the company Rhodia, the Hi-Sil EZ 1 50G silica from PPG, Zeopol 871 5, 8745 and 8755 silicas from Huber, high surface area silicas as described in WO 03/16837.

When the composition according to the invention or comprising the vulcanization accelerators used according to the invention is intended for tire treads with a low rolling resistance, the reinforcing inorganic filler used, in particular if it is silica, preferably has a BET surface area of between 45 and 400 m ² / g, more preferably between 60 and 300 m ² / g.

Preferably, the content of total reinforcing filler (carbon black and / or reinforcing inorganic filler such as silica) is between 20 and 200 phr, more preferably between 30 and 200 phr. 1 50 phr, the optimum being in a known manner different according to the particular applications concerned: the level of reinforcement expected on a bicycle tire, for example, is of course lower than that required on a tire capable of running at high speed in a sustained manner for example a motorcycle tire, a tire for a passenger vehicle or for a commercial vehicle such as a heavy truck.

According to one embodiment of the invention, a reinforcing filler comprising between 30 and 1 50 phr is used, more preferably between 50 and 120 phr of inorganic filler, particularly of silica, and optionally carbon black; the carbon black, when present, is preferably used at a level of less than 20 phr, more preferably less than 10 phr (for example between 0.1 and 10 phr).

According to another embodiment, the reinforcing filler is carbon black.

In order to couple the reinforcing inorganic filler to the diene elastomer, an at least bifunctional coupling agent (or bonding agent) is used in 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 bifunctional polyorganosiloxanes.

In particular, polysulphide silanes, called "symmetrical" or "asymmetrical" depending on their particular structure, are used, as described for example in the applications WO03 / 002648 (or US 2005/01 6651) and WO03 / 002649 (or US 2005/01 6650 ).

In particular, polysulphide silanes known as "symmetrical" silanes having the following general formula (111) are suitable, without the following definition being limiting:

(III) Z - D - S _p - D - Z, in the aq

p is an integer of 2 to 8 (preferably 2 to 5); D is a divalent hydrocarbon radical (preferably C ₁ -C 18 alkylene groups or C ₆ -C ₁₀ arylene groups, more particularly C ₁ -C ₄ alkylenes, especially C ₁ -C ₄ alkylenes, in particular propylene);

Z is one of the following formulas:

in which:

the radicals R2, substituted or unsubstituted, which are identical to or different from one another, represent a C1-C18 alkyl, C8-C6 cycloalkyl or C6-C18 aryl group (preferably C ₁ -C ₆ alkyl groups); -C ₆ , cyclohexyl or phenyl, especially C ₁ -C ₄ alkyl groups, more particularly methyl and / or ethyl).

the radicals R ₂₂ , which are substituted or unsubstituted, which are identical to or different from one another, represent a C 1 -C ₁₈ alkoxyl or C ₈ -C ₈ cycloalkoxyl group (preferably a group chosen from C 1 -C ₈ alkoxyls and cycloalkoxyls containing C 8 -C 8, more preferably still a group selected from C 1 -C ₄ alkoxyls, in particular methoxyl and ethoxyl).

In the case of a mixture of polysulfurized alkoxysilanes corresponding to formula (III) above, in particular common commercially available mixtures, the average value of "p" is a fractional number preferably of between 2 and 5, more preferably close to 4, But the invention can also be advantageously implemented for example with disulfide alkoxysilanes (p = 2).

By way of examples of polysulphide silanes, mention may be made more particularly of the polysulfides (in particular disulfides, trisulphides or tetrasulfides) of bis (C 1 -C ₄ alkoxy) -alkyl (C 1 -C ₄ ) silyl-alkyl (C 1 - C ₄ )), such as polysulfides of bis (3-trimethoxysilylpropyl) or bis (3-triethoxysilylpropyl). Among these compounds, bis (3-triethoxysilylpropyl) tetrasulfide, abbreviated to TESPT, of formula [(C ₂ H 3 O) 3 Si (CH ₂ ) 3 S 2] 2 or bis (triethoxysilylpropyl) disulfide, is especially used, abbreviated to TESPD, of formula [(C ₂ H ₅ O) 3Si (CH 2) 3 S] 2. Preferred polysulfides (especially disulfides, trisulphides or tetrasulfides) of bis (monoalkoxyl (C 1) are also preferred; - C4) -DialkyI (C] - C4) silylpropyl), more particularly the bis-monoethoxydimethylsilylpropyl tetrasulfide as described in the patent application WO 02/083782 (or US 2004/1 32880).

As coupling agent other than polysulfurized alkoxysilane, there may be mentioned in particular bifunctional POS (polyorganosiloxanes) or hydroxysilane polysulfides (R ₂₂ = OH in formula III above) as described in patent applications. WO 02/30939 (or US Pat. No. 6,774,255) and WO 02/31041 (or US 2004/05 1 21 0), or else silanes or POS bearing azodicarbonyl functional groups, as described, for example, in the patent applications WO 2006/125532, WO 2006/1 25533, WO 2006/125534.

In the rubber compositions according to the invention or comprising the vulcanization accelerators used according to the invention, the content of coupling agent is preferably between 4 and 12 phr, more preferably between 3 and 8 phr.

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. II.3 Vulcanization system

The vulcanization system itself is 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 productive 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).

Sulfur is used at a preferential level of between 0.5 and 10 phr, more preferably between 0.5 and 5 phr, in particular between 0.5 and 3 phr, when the composition of the invention is intended, according to a method. of the invention to constitute a tire tread.

The primary vulcanization accelerator must allow crosslinking of the rubber compositions in commercially acceptable times, while maintaining a minimum safety period ("toasting time") during which the compositions can be shaped without the risk of premature vulcanization. ("Roasting").

AT. Use of thiophene compounds as a vulcanization accelerator

According to the invention, one or more thiophene compounds chosen from the following compounds of formula (I) and (II) are used as primary vulcanization accelerator:

in which

R 1, R 1 and R ₂ represent, independently of one another, a hydrogen atom, a halogen atom, a thiol, hydroxyl or amino group, or a C 1 -C ₂₅ hydrocarbon-based group chosen from linear, branched alkyl groups; or cyclic, saturated or unsaturated aralkyl groups, alkylaryl groups and aryl groups, and optionally interrupted by one or more heteroatoms and / or optionally substituted with one or more halogen atoms and / or optionally substituted with one or more thiol functions hydroxyl, amino; R and R j where R 1 and R ₂ may together form an aromatic ring or not,

-A represents a group selected from

a hydrogen atom,

in which R] ₂ represents:

a group C ₁ -C ₂ _5> linear or branched, optionally interrupted ar one or more heteroatoms, optionally substituted by one or more C 3 -C 10 cyclic alkyl or C ₆ -C ₁₂ aryl groups, or

- a cyclic alkyl C 3 -C ₁ 0, optionally interrupted by one or more heteroatoms, optionally substituted by one or more linear alkyl groups, branched or cyclic C 1 -C25 aryl or C ₆ -C i 2, optionally interrupted by one or more heteroatoms;

- a group

in which

R _c is identical to R, Ri _c is identical to Rj, R _2c is identical to

R ₂ ,

x denotes an integer greater than or equal to 1, preferably less than or equal to 1 0, more preferably less than or equal to 8 and most preferably less than or equal to 6;

- a group

R ₅ in which

R 3, R ₄ and R 5 independently represent a hydrocarbon group Cj-C is optionally interrupted by one or more heteroatoms,

y is an integer greater than or equal to 1, preferably less than or equal to 10, more preferably less than or equal to 8 and most preferably less than or equal to 6; - a group

in which

R ₆ denotes a C 1 -C ₁₈ hydrocarbon group, optionally interrupted by one or more heteroatoms;

- a gro

in which

R ₇ denotes a hydrocarbon group-Cis, optionally interrupted by one or more heteroatoms;

- a group

in which

Y represents a C1-C18 hydrocarbon chain, optionally interrupted or substituted by one or more heteroatoms,

Rg denotes a C1-C18 hydrocarbon group, optionally interrupted by one or more heteroatoms;

- a group

in which X represents a C 1 -C 4 hydrocarbon-based chain, optionally interrupted or substituted with one or more heteroatoms,

R 9 and R 11 denote a C 1 -C 18 hydrocarbon group, optionally interrupted by one or more heteroatoms;

- a gr

in which

Rn denotes a hydrogen atom, a C 1 -C 18 hydrocarbon group, optionally interrupted by one or more heteroatoms;

M ^{n +} represents a metallic or non-metallic cation, n represents an integer varying between 1 and 4.

The compounds of formula (I) or (II) may advantageously replace all or part of the accelerator compounds conventionally used.

By cyclic alkyl group is meant an alkyl group consisting of 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.

According to a first embodiment, R, R 1 and R ₂ independently represent a hydrogen atom or a methyl group.

According to a second embodiment, R, _t and R ₂ each represent a hydrogen atom. According to a third embodiment, R represents a methyl and R 1 and R ₂ each represent a hydrogen atom.

The groups R ₃ to R _{1 2} may be chosen independently from linear, branched or cyclic alkyl groups, aryl groups, aralkyl groups and alkylaryl groups, subject to any conditions previously explained for each of these groups.

The group R ₂ may represent cyclohexyl or terbutyl. Groups X and Y may be independently selected from linear, branched or cyclic alkylene groups, arylene groups and alkylarylene groups.

The cation M " ^T may be a metal cation selected from Zn ²⁺ , Cu ²⁺ , Na ⁺ , Li ⁺ and K ⁺ .

The cation M ^{n +} may be a non-metallic cation such as an ammonium ion, for example the NMe ₄ ⁺ , H ₄ ⁺ or H ₃ NMe ^- ion.

According to a particular embodiment, the groups R ₃ , R ₄ and R ₅ represent a methyl group.

According to a particular embodiment, the group R _$ represents a C i -C ₄₅ pl us preferably alkyl C ₃ -C and very preferably, methyl or ethyl.

According to one particular embodiment, the group R ₇ represents a C 1 -C 4 alkyl, more preferentially a C 1 -C ₃ alkyl and very preferably a methyl group or an ethyl group, or R ₇ represents an aralkyl group. as for example a benzyl group.

According to a particular embodiment, Y represents a C 1 -C 4 alkylene, more preferably a C 1 -C ₃ alkylene and very preferably a propylene group or an ethylene group and R ₈ represents a C 1 -C 4 alkyl group. , more preferably a C 1 -C 3 alkyl and very preferably a methyl group or an ethyl group.

According to a particular embodiment, X represents a C 1 -C 4 alkylene, more preferentially a C 1 -C 3 alkylenene and very preferably, a methylene group or an ethylene group and R and R 10 independently represent a C 1 -C ₄ alkyl, more preferably a C ₁ -C ₃ alkyl and very preferably a methyl group or an ethyl group.

According to a particular embodiment, the Ru group represents a hydrogen atom.

According to a particular embodiment, the R12 group represents a cycloalkyl group, C ₅ or C <s, or a linear alkyl group or branched C ^ -This. Preferentially, the group R | ₂ represents a cyclohexyl or a terbutyl e and more preferably, the group R 12 represents a cyclohexyl.

As a compound of formula (I) in particular, mention may be made of the following compounds:

The compound (s) of formula (I) and / or (II) generally represent from 0.1 to 7 phr, preferably from 0.5 to 7 phr, more preferably from 0.5 to 5 phr.

B. Rubber composition

According to the invention, the vulcanization system of the composition according to the invention comprises, as a primary vulcanization accelerator, one or more thiophene compounds chosen from the compounds of formula (Ib) below;

in which

R _b , Ri _b and R _Σb represent, independently of each other, a hydrogen atom, a halogen atom, a thiol, hydroxyl or amino group, or a C ₁ -C 25 hydrocarbon-based group chosen from among the groups linear, branched or cyclic alkyls, saturated or unsaturated aralkyl groups, alkylaryl groups and aryl groups, and optionally interrupted by one or more heteroatoms and / or optionally substituted by one or more halogen atoms and / or optionally substituted by a or several thiol, hydroxyl, amino functions; R _¾ and R i _b or R ib and R _2b may together form an aromatic cycle or not,

-A _b represents a group selected from

- a group

in which Ri _2b represents;

a linear or branched C 1 -C 25 alkyl group optionally interrupted by one or more heteroatoms, optionally substituted by one or more C 3 -C 10 cyclic alkyl groups or C ₆ -C ₁₂ aryl groups, or

a C3-C10 cyclic alkyl group, optionally interrupted by one or more heteroatoms, optionally substituted by one or more linear, branched or cyclic alkyl groups in

C ₁ -C ₂ 5 or C ₆ -C aryls _{! 2} , optionally interrupted by one or more heteroatoms; - a gro

in which

yb is an integer greater than or equal to 1, preferably less than or equal to 10, more preferably less than or equal to 8 and most preferably less than or equal to 6; a. grou

in which

R _6b denotes a C 1 -C ₈ hydrocarbon-based group, optionally interrupted by one or more heteroatoms;

- a gr

in which

R ₇ b denotes a C ₁ -C 18 hydrocarbon group, optionally interrupted by one or more heteroatoms;

in which

Y represents a hydrocarbon chain in C 1 -C 18, optionally interrupted or substituted by one or more heteroatoms;

R¾b denotes a C1-C18 hydrocarbon group, optionally interrupted by one or more heteroatoms;

- a group

in which

X represents a C1-C12 hydrocarbon chain, optionally interrupted or substituted by one or more heteroatoms;

R _9b and Rjob denote a C1-C18 hydrocarbon group, optionally interrupted by one or more heteroatoms;

- a G

in which

Riib denotes a hydrogen atom, a C1-C18 hydrocarbon group, optionally interrupted by one or more heteroatoms.

The compounds of formula (Ib) may advantageously replace all or part of the accelerator compounds conventionally used.

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

By hydrocarbon group or 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 a carbon atom 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.

According to a first embodiment, R _b , R _lb and R _2b independently represent a hydrogen atom or a methyl group.

According to a second embodiment, R _b , R _lb and R _2¾ each represent a hydrogen atom.

According to a third embodiment, R _b represents methyl and R b and R ₂ b each represents a hydrogen atom.

The groups R _3b to R _{) 2b} may be chosen independently from linear, branched or cyclic alkyl groups, aryl groups, aralkyl groups and alkylaryl groups, subject to any conditions previously explained for each of these groups.

The group R _2b may represent cyclohexyl or terbutyl. Groups X _b and Y may be independently selected from linear, branched or cyclic alkylene groups, arylene groups and alkylarylene groups.

As a compound of formula (ib) in particular, mention may be made of the compounds (B) to (H) mentioned above.

The compound (s) of formula (Ib) generally represent from 0.1 to 7 phr, preferably from 0.5 to 7 phr, more preferably from 0.5 to 5 phr.

The vulcanization system of the composition according to the invention may also comprise one or more additional primary accelerators, in particular the thiuram family compounds, the zinc dithiocarbamate derivatives, the suifenamides, the guanidines or the thiophosphates. H-4. Various additives

The rubber composition according to the invention or comprising the vulcanization accelerators used according to the invention may also comprise all or part of the usual additives normally used in elastomer compositions intended for the manufacture of tires, in particular treads, such as, for example, plasticizers or extension oils, whether these are of aromatic or non-aromatic nature, pigments, protective agents such as anti-ozone waxes (such as Ozone wax C32 ST), antiozonants chemical, anti-oxidants (such as 6-paraphenylenediamine), anti-fatigue agents, reinforcing resins, acceptors (for example phenolic novolac resin) or methylene donors (for example HMT or H3 M) as described by US Pat. example in the application WO 02/10269.

Preferably, the composition according to the invention or comprising the vulcanization accelerators used according to the invention comprises, as preferential non-aromatic or very weakly aromatic plasticizing agent, at least one compound chosen from the group consisting of naphthenic oils, paraffinic, MES oils, TDÀE oils, esters (in particular trioleates) of glycerol, hydrocarbon plasticizing resins having a high Tg preferably greater than 30 ° C, and mixtures of such compounds.

The composition according to the invention or comprising the vulcanization accelerators used according to the invention may also contain, in addition to the coupling agents, activators for coupling the reinforcing inorganic filler or, more generally, agents for assisting the implementation. in a known manner, by improving the dispersion of the inorganic filler in the rubber matrix and by lowering the viscosity of the compositions, to improve their ability to use in the green state, these agents being examples of hydrolysable silanes such as alkylalkoxysilanes (especially alkyltriethoxysilanes), polyols, polyethers (for example polyethylene glycols), primary, secondary or tertiary amines (for example trialkanol amines), hydroxylated or hydrolysable POSs, for example α, ω-dihydroxy-polyorganosiloxanes (in particular α, ω-dihydroxy-polydimethylsiloxanes), fatty acids such as, for example stearic acid.

II-5. Manufacture of rubber compositions

The rubber composition according to the invention or comprising the vulcanization accelerators used according to the invention is manufactured in appropriate mixers, generally using two successive preparation phases according to a general procedure well known to those skilled in the art: a first phase working or thermomechanical mixing (sometimes referred to as a "non-productive" phase) at a high temperature, up to a maximum temperature of between 1 ° to 100 ° C. and preferably between 1 ° and 5 ° C. 50 ° C and more preferential! still between 1 1 5 ° C and 1 40 ° C, followed by a second phase of mechanical work (sometimes called "productive" phase) at a lower temperature, typically below 1 10 ° C, for example between 40 ° C and 100 ° C, finishing phase during which can be incorporated the crosslinking system or vulcanization.

According to a preferred embodiment of the invention, all the basic constituents of the composition of the invention or comprising the vulcanization accelerators used according to the invention, with the exception of the vulcanization system, namely the one or more fillers. the coupling agent, if appropriate, are intimately incorporated, by kneading, with the diene elastomer or the diene elastomers during the so-called non-productive first phase, that is to say that the the mixture is introduced into the mixer and thermomechanically kneaded, in one or more steps, at least these various basic constituents until the maximum temperature between 1 1 0 ° C and 1 90 ° C, preferably between 1 1 5 ° C and 1 50 ° C. The two phases can be carried out consecutively on the same mixer or be separated by a cooling step at a temperature below 100 ° C., the last step then being carried out on a second mixer.

By way of example, the first (non-productive) phase is carried out in a single thermomechanical step during which all the necessary constituents, the possible setting agents, are introduced into a suitable mixer such as a conventional internal mixer. Complementary applications and other miscellaneous additives, with the exception of the vulcanization system. The total mixing time in this non-productive phase is preferably between 1 and 15 minutes. After cooling the mixture thus obtained during the first non-productive phase, the vulcanization system is then incorporated at low temperature, generally in an external mixer such as a roller mixer; the whole is then mixed (productive phase) for a few minutes, for example between 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 rubber profile that can be used, for example, as a tread. tire for passenger vehicle,

II-6. Particular Thiophene Compounds The subject of the invention is also a thiophene of the following formula (Γ):

in which

R _a, R _a and R 2a independently of one another, a hydrogen atom, a halogen atom, thiol, hydroxyl, amino or a hydrocarbon group of C ₁ -C25 chosen from linear alkyl groups, branched or cyclic, saturated or unsaturated aralkyl groups, alkylaryl groups and aryl groups, and optionally interrupted by one or more heteroatoms and / or optionally substituted with one or more halogen atoms and / or optionally substituted by one or more functions thiol, hydroxyl, amino, R _a and R or Ri _a and R _2a may together form an aromatic ring or not,

-A _a represents

in which R] _2a represents:

a linear or branched C 1 -C ₆ alkyl group optionally interrupted by one or more heteroatoms, optionally substituted by one or more C ₃ -C ₁₀ cyclic alkyl groups or C ₆ -C ₁₂ aryl groups, or

- a cyclic alkyl C ₃ -C ₁₀ alkyl, optionally interrupted by one or more heteroatoms, optionally substituted by one or more linear alkyl groups, branched or cyclic C1-C25 aryl or C6-C _12, optionally interrupted by one or several heteroatoms,

with the proviso that R _a and R, and Ri _a and R _2a can not form a ring combination, and

- a group

wherein R _3a, R _4a and Rs independently represent _a hydrocarbon group-Ci _8, optionally interrupted by one or more heteroatoms,

y _a is an integer greater than or equal to 1, preferably less than or equal to 10, more preferably less than or equal to 8 and most preferably less than or equal to 6; a gr

in which R _7a denotes a C 1 -C ₁₈ hydrocarbon group, optionally interrupted by one or more heteroatoms, with the proviso that R _2a denotes a C 1 -C ₁₈ hydrocarbon group containing no heteroatom:

- a group

GOLD*,

in which

_X is a hydrocarbon chain in C) _{-C) 8,} optionally interrupted or substituted by one or more hetero atoms, but which can not carry another phosphonate group,

R9a and RIOA independently represent a hydrocarbon group-Ci _8, optionally interrupted by one or more heteroatoms.

According to a first embodiment, R _a, R _a and R _2a independently represent a hydrogen atom or a methyl group. According to a second embodiment, R _a , Ri "and R _2a each represent a hydrogen atom.

According to a third embodiment, R ₈ represents a methyl and R _la and R _2a each represent a hydrogen atom.

The groups R _3a to R _5a, R _7a> R _9a to R i and R _{_0a) 2a} are independently selected from linear, branched or cyclic, aryl groups, aralkyl groups and alkylaryl groups.

The group R i _2a may represent cyclohexyl or terbutyl. The group _X is independently selected f the linear alkylene, branched or cyclic arylene groups and alkylarylene groups.

As a compound of formula (Γ) particular, there may be mentioned compounds (B), (D), (E) and (G) cited above.

II- 7. Preparation of accelerators of general formula II), (11). LL) and (F) Those skilled in the art can prepare the thiophene compounds of the general formula (1) when the group A represents a hydrogen atom, in which case the thiophenes are substituted by a thiol. This thiol may be salified by techniques known to those skilled in the art to obtain the thiolate compounds of formula (II).

From thiols or thiolates described above and depending on the nature of the group A, A _b or A _a , the skilled person can obtain the compounds of general formula (I) or (Γ) as indicated below:

- When radical A represents a group

as defined above, the compound can be prepared by an oxidative coupling.

To a solution of the precursor thiol is added an organic or inorganic oxidizing agent (for example diisopropylazodicarboxylate or ammonium persulfate, or alternatively iodine or a solution of sodium hypochlorite). For example, this type of procedure is described in the following documents:

with NaOCl by Math.es in US2,196,607 (1940),

- with (NH) ₂ S ₂ O _g in Stewart, Mafhes, J. of Org. Chem., 1949, vol. 14, p. 1 1 1 1 - 1 1 17.

By this reaction, the derivatives in which x = 1 are obtained. To obtain compounds in which x is greater than 1, sulfur atoms can be inserted into the existing sulfur-sulfur bond, for example by reaction with triphenylthiosulfenyl chloride. in dichlorometh in the presence of acetic acid, as proposed for example in Tetrahedron Letters, Volume 41, Issue 37, September 2000, Pages 7169-7172.

When the radical A, A _¾ or A _a represents a group

as defined above, the synthesis route may be similar to that described for the above compounds.

For example, Birch describes the oxidative coupling of methyl mercaptan with tert-butyl mcrcaptan in the presence of potassium hexacyanoferrate III (Birch et al., Journal of the Institute of Petroleum, 1953, 39, pp. 206-210).

It is also possible to follow another procedure consisting in carrying out a redistribution reaction of a symmetrical disulfide in the presence of an alkyl mercaptan as described, for example, by Brzezinska, Ewa; Tcrnay, Andrew L., Jr. in the article Disulfides Syntheses Using 2,2'-Dithiobis (benzothiazole), Journal of Organic Chemistry (1994), 59, 8239-8244. This method consists in making a reaction in chloroform between a symmetrical disulfurc and a mercaptan such as tert-butyl mercaptan, which leads to a redistribution.

By this reaction, derivatives are obtained in which y, y _b or y _a = 1. For those compounds wherein Y, Y _b _or y is greater than 1, can be inserted sulfur atoms dan s binding sulfur - existing sulfur, for example by reaction with chloride triphénylthiosulfényl in dichloromethane in the presence of acetic acid, as proposed for example in Tetrahedron Letters, Volume 41, Issue 37, September 2000, pages 71 69-71 72.

- When the radical A or Ab represents a group

as defined above, this compound may be prepared according to a thioesterification reaction between the thiol or its corresponding thiolate with a carboxylic acid or its derivatives (acid chloride, anhydride) bearing the radical D or R ₆ -

For example, Jan Larsen and Christine Lenoir in Organic Syntheses, Coll. Flight. 9, p. 72 (1998) describe a thioesterification reaction between a thiol and an acid chloride in the presence of triethylamine to trap the hydrochloric acid formed, the reaction being carried out in dichloromethane at 0 to 10 ° C.

as defined above, this compound may be prepared by elimination addition reaction between the thiol and a chloroformate carrying the radical R ₇ , R _7b or R _a which may itself be commercially available or prepared by reaction between a alcohol and phosgene or a derivative thereof. An organic or inorganic base can be added to trap the hydrochloric acid formed.

This approach is described by Taylor, Roger in the Journal of the Chemical Society, Perkin Transactions 2: Physical Organic Chemistry (1972-1999), 1983, p. 291-296. The authors react ethyl mercaptan with methyl chloroformate in the presence of pyridine.

Instead of using the thiol, it is possible to use the corresponding thiolate. This approach is described by Suzuki, Shigenori; Hisamichi, Kanehiko; Endo, Katsuya in Heterocycles, 1993, vol. 35, # 2 p. 895-900. The authors react sodium methylthiolate with methyl chloroformate to obtain the thiocarbonate derivative.

Another synthetic route is to react the thiol or its thiolate with phosgene (Chen, HW et al., Journal of the American Chemical Society, 1978, vol 100, pp. 2370-2375) or a derivative thereof such as triphosgene (WO2008 / 038175) optionally in the presence of an inorganic or organic base such as a tertiary amine, for example to form the chlorothioformate intermediate. This intermediate can then react with an alcohol in the presence of an organic base such as a tertiary amine to form the thiocarbonate compound. This approach is for example described in Organic Syntheses, Coll. Vol.5, p.166 (1973); Vol.44, p.20 (1964). - When radical A or A _¾ represents a group

as defined above, this compound may be prepared by nucleophilic substitution between the thiol or its thiolate and an ester substituted with a halogenated group and bearing the radicals Y and R _s or Yb and Rgb such as, for example, bromoethylacetate or 4-bromo methylbutyrate . For example, the reaction between 3-mercapto-5,6-diphenyl-1,2,4-triazine and ethyl 3-bromo-propionate in ethyl acetate in the presence of triethylamine to trap acid hydrobromic formed is described by Bhalla, M .; Srivastava, VK; Bhalla, TN; Shanker, K. in Bollettino Chimico Farmaceutico (1995), 134 (1), 9-15.

- When the radical A, At, or A _d represents a group

as defined above, this compound can be prepared by nucleophilic substitution between the thiol or thiolate and a halogenated derivative of a phosphonate or phosphonic acid bearing the radicals X, R and R or Xb, and R½ inbo or _X , R _a and Rioa, and more particularly with a bromo or chloro alkyl phosphonate.

This reaction is described, for example, for the reaction between diethyl (2-bromoethyl) phosphonate and sodium ethanethiolate in an ether (Mikolajczyk, Mari, Costisella, Burkhard, Grzejszczak, Slawomir, Tetrahedron, 1983, vol. 39, # 7 pp. 1189-1193).

- When the radic

as defined above, this compound may be prepared by nucleophilic substitution between the thiol or its thiolate and an allyl halide carrying the Ru or Ru _b radical and for example between the thiol and allyl bromide.

For example, the reaction between a triazine thiol and an allyl halide in the presence of potassium hydroxide in alcohol is described in patent BE 503980 of the Belgian Society of Nitrogen and Chemical Marly (1951). - When the radical A, A _¾ or A _a represents a group

as defined above, this compound may be prepared by reaction between the thiol and a basic composition which may be an aqueous solution of an organic or inorganic base, for example an aqueous solution of sodium hydroxide, and then by reaction with an amine primary of formula R ₁₂ NH ₂ (respectively R _2b R _2a or H ₂ NH ₂₎ or 12 (respectively R ₂ R b or _12a) is as defined above. The oxidizing coupling is then carried out in the presence of an oxidizing compound which may be, for example, a halogenated compound such as dichlorine, dibromine, diiodine, hypohalogenous acids or their alkaline salts such as, for example, sodium hypochlorite.

As an example of a compound of formula (I), it is possible to note the mercaptothiophene of formula (1) below:

marketed for example by the company Aldri ch.

The mercaptothiophene of formula (2) below is also a known compound.

Its synthesis is described in the document: Synthesis and some transformations of sulfides of thiophene series. VIII. The mechanism of formation of 2-mercapto-5-ethyl-3-thenylideneimine, Goldfarb, Ya. L. Kalik, MA; Kirmalova, ML, Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya (1964), (9), 1675-8 1. Thiophene bisulfides are also known compounds. For example, the following bis (2-thién ructure:

is marketed by Aldrich.

The synthesis of 2,2'-dithio-bis-5-methyl-thiophene (4) with the following structure:

is also described in the following document: Synthesis and some transformations of sulfides of thiophene series. VIII. The mechanism of formation of 2-mercapto-5-ethyl-3-enylideneimine, Goldfarb, Ya. L. Kalik, M.A .; Kirmalova, M.L., Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya (1964), (9), 1675-8 1. By way of example for formula (II), mention may be made of potassium, sodium, lithium, zinc and cobalt salts.

Cobalt salt (5)

is for example described in the document: Copper, cobalt and platinum complexes with dithiothiophene-based ligands, Belo, Dulce; Figueira, auro J .; Mendonca, Joana; Santos, Isabel C; Almeida, Manuel; Henriques, Rui T .; Duarte, Maria Teresa; Rovira, Concepcio; Vcciana, Jaume, European Journal of Inorganic Chemistry (2005), (16), 3337-3345. Potassium salt (6)

is for example described in the document: Preparation of cep hem derivatives as antibacterials, Tawada, Hiroyuki; Okonogi, Kenji (1997), JP 09100283.

Lithium salt (7)

is for example described in the document: 2-Thiophenethiol, Jones, Edward; Moodie, Lain M. Organic Syntheses (1970), 50.

Zinc salt

is for example described in the document: Synthesi s and transformations of thiophene-series sulfides. XXI. Effect of sodium in liquid ammonia on the methyl ester of 2-ethylthito-5-ethyl-3-thiophenecarboxylic acid, Goldfarb, Ya. L. Kalik, M. A .; Kirmalova, M. Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya (1 969), (1 0), 2260-5

III. Example

Sulfenamide 3 was prepared according to the scheme below. Deprotonation of 2-methylthiophene with n-butyllithium followed by reaction with sulfur makes it possible to generate the intermediate thiolate which is directly oxidized to give the disulfide 2. This disulfide 2 is then converted into sulfenamide by reaction with cyclohexylamine in an oxidizing medium according to a general procedure described by FA Davis, AJ Fricdman, EW Kluger, E. B. Skibo, ER Fretz, AP Milicia, WC Lc astcrs, J. Org. Chem. 1,977,42,967-972.

The N-butyl lithium (22.9 ml of a 2.5M solution in hexane, 57.3 mmol) is added under argon to a stirred solution at -20 ° C of 2-methylthiophene 1 (5.0 ml). mmol) in anhydrous diethyl ether (30 ml). The temperature increases to - 12 ° C. The reaction medium is allowed to return to ambient temperature and then stirred for 30 min. The suspension obtained is again cooled to -10 ° C. and the sulfur (1.66 g, 52 mmol) is added little by little. The reaction mixture is stirred at room temperature for 1.5 h and then at reflux for 10 min. The solution obtained is poured into an aqueous solution of 1% NaOH (200 mL) and washed with diethyl ether (2 times 30 mL). The iodine (6.61 g, 52 mmol) ground in a mortar is added to the alkaline solution and the suspension is stirred for 12 hours. The solution is extracted with diethyl ether (3 times 50 ml) and the combined organic phases are washed with water then dried over MgSO 4 and evaporated. The solid residue obtained after cooling is recrystallized from petroleum ether. Disulfide 2 (3.4 g, 13 mmol, 50%) is obtained as yellow crystals.

Fusion point. 40-42 ° C (lit. 38.5-39.5 in article Ya, L. Goldfarb, M.A., Kalik, ML Kirmalova, Jzv.Akad.Nauk SSSR, Ser.Kimi 1967, 1675-1681.]) .

1 H NMR (300 MHz, CDCl 3, δ): 2.56 (s, 6H, 2 CH ₃ ), 6.70-6.75 (m, 2H, 2 ^thioph CH), 7.02 (d, J = 3.3 Hz, 2H, 2 CH ^{, hioph} ).

Mass, m / z (%): 258 (39, M ⁺ ), 129 (100, ½M ⁺ ).

The disulfide 2 (1.3 g, 5.0 mmol) is added to a solution of AgNO ₃ (0.87 g, 5.1 mmol) with stirring in absolute methanol (40 mL). The resulting suspension is stirred for 10 minutes, then cyclohexylamine (2.9 mL, 25 mmol) is added, and the reaction mixture is stirred at room temperature overnight. The silver thiolate precipitate is filtered and washed with methanol (20 mL). The combined solution is evaporated and then water is added (100 mL). The product is extracted with diethyl ether (3 * 30 ml), the extract is washed with water (4 * 100 ml), dried over MgSO ₄ , evaporated and dried under vacuum to give 0.96 g (84 ml). %) sulfenamide 3 as a yellow liquid. ¹ H NMR (300 MHz, CDCl 3, δ): 1.05-1.30 (m, 6H, 3 CH ₂ ), 1.67-1.78 (m, 2H, CH ₂ ), 1.87-1. 99 (m, 2H, C¾), 2.49 (s, 3H, CH ₃ ), 2.60-2.73 (m, 1H, CH), 2.79 (brs, 1H, NH) ), 6.66-6.69 (m, 1H, CH ^lhioph ), 7.01 (d, J = ^3.3 Hz, H, CH ^thioph ). Mass, m / z (%): 227 (74, M ⁺ ), 145 (57), 129 (100). Obtained,%: C, 58.06; H, 7.82; N, 7.09; S, 28, 1 4. C _n Hi ₇ NS ₂ . Calculated,% C, 58.10; H, 7.54; N, 6.16; S, 28.20.

The purpose of this example is to compare the properties of a rubber composition comprising carbon black as a predominant reinforcing filler, usable for the manufacture of a tire tread, comprising 2- [(cyclohexylamino) thio] -5 methyl-thiophene according to the invention as a primary vulcanization accelerator (composition 2) with the properties of a rubber composition comprising N-cyclohexyl-2-benzothiazyl sulfenamide (CBS) (composition 1).

The formulations of the compositions are given in Table 1 below. The amounts are expressed in parts per 100 parts by weight of elastomer (phr).

The rubber composition 2 comprising [(2 - [(cyclohexylamino) thio] -5-methyl-thiophene is identical to the comparative composition 1, it being understood that the CBS is replaced by an isomolar amount of [(2 - [(cyclohexylamino) tbio] -5 methylthiophene.

Table 1

(1) polybutadiene with 0.7% of 1-2; 1.7% trans 1 -4; 98% cis 1 -4 (Tg = -105 ° C) (mol%) (2) butadiene-styrene copolymer SSBR (SBR prepared in solution) with 25% styrene, 59% polybutadiene 1 -2 and 20% trans-polybutadiene 1-4 (Tg = -24 ° C)

(mol%); rate expressed as dry SBR (extended SBR with 9% by weight of MES oil, ie a total of SSBR + oil equal to 76 phr)

(3) carbon black

(4) "Zeosil 1 165MP" silica of the Rhodia company, "HDS" type (BET and CTAB: approximately 160 m2 / g);

(5) Antioxidant agent 6-para-phenylenediamine

(6) Antiozonant agent

(7) Aliphatic resin (C5 pure) "Hikorez A-100" sold by the company OLON

(8) coupling agent

(9) Diphenylguanidine (Perkacit DPG from Flexsys) * CBS (Santocure CBS from Flexsys)

The rheometric properties at 150 ° C are given in Table 2 below.

Table 2

The rheometric properties obtained for the composition 2 according to the invention show that [(2 - [(cyclohexylamino) thio] -5 methyl-thiophene can be used as accelerator of vulcanization in rubber compositions comprising one or more reinforcing fillers.

Claims

1. Use as a vulcanization accelerator in a composition based on one or more dielectric elastomers, one or more reinforcing fillers and a vulcanization system, of one or more thiophene compounds chosen from the compounds of formula (I) and (II)

in which

R, R 1 and R ₂ represent, independently of one another, a hydrogen atom, a halogen atom, a thiol, hydroxyl or amino group, or a C 1 -C 25 hydrocarbon-based group chosen from linear alkyl groups; branched or cyclic, saturated or unsaturated aralkyl groups, alkylaryl groups and aryl groups, and optionally interrupted by one or more heteroatoms and / or optionally substituted by one or more halogen atoms and / or optionally substituted by a or more than one thiol, hydroxyl, amino function; R and R [or R ₁ and R ₂ may together form an aromatic ring or not,

-A represents a group selected from a hydrogen atom,

in which R ₁₂ represents:

a linear or branched C ₁ -C 25 alkyl group optionally interrupted by one or more heteroatoms, optionally substituted by one or more C ₃ -C ₁₀ cyclic alkyl groups or C ₆ -C ₁₂ aryl groups, or

- a cyclic alkyl C ₃ -C ₁ 0, optionally interrupted by one or more heteroatoms, optionally substituted by one or more linear alkyl groups, branched or cyclic C _i -C25 aryl or C ₆ -C ₂ optionally interrupted by one or more heteroatoms;

- a gr

in which

R _c is identical to R, R _lc is identical to Ri, R _2c is identical to R ₂

x denotes an integer greater than or equal to 1, preferentially less than or equal to 10, more preferably less than or equal to 8 and very preferably less than or equal to 6; - n group

in which

R-3, R.4 and R ₅ independently represent a C1-C18 hydrocarbon group, optionally interrupted by one or more heteroatoms,

y is an integer greater than or equal to 1, preferably less than or equal to 10, more preferably less than or equal to 8 and most preferably less than or equal to 6; a group

in which

R ₆ denotes a Ci-Cia hydrocarbon group, optionally nterromputed by one or more heteroatoms; a gro

in which

R ₇ denotes a C 1 -C 5 hydrocarbon group, optionally nterromputed by one or more heteroatoms;

-

in which

Y represents a C 1 -C 15 hydrocarbon-based chain, optionally interrupted or substituted with one or more heteroatoms;

Rg denotes a hydrocarbon group Cj -C _{] S} , optionally interrupted by one or more heteroatoms; a

in which

X represents a hydrocarbon chain Ci-Ci g, optionally interrupted or substituted by one or more heteroatoms;

R _{9 and} R ₁₀ denote a C ₁ -C 18 hydrocarbon group, optionally interrupted by one or more heteroatoms;

- a gr

in which

R 1 denotes a hydrogen atom, a C 1 -C 4 hydrocarbon-based group, optionally interrupted by one or more heteroatoms _;

2. Use according to claim 1, characterized in that the groups R, R and R ₂ independently represent a hydrogen atom or a methyl group.

3. Use according to claim 2, characterized in that the groups R, R 1 and R ₂ each represent a hydrogen atom.

4. Use according to claim 2, characterized in that the R group represents a methyl group and R j and R ₂ each represent a hydrogen atom.

5. Use according to any one of the preceding claims, characterized in that group A is the group

wherein R _{1 2} is as defined in claim 1.

6. Use according to any one of the preceding claims, characterized in that the groups R to R ₁₂ are independently selected from linear, branched or cyclic alkyl groups, aryl groups, aralkyl groups and alkylaryl groups.

7. Use according to any one of claims 1 to 6, characterized in that the group R ₁₂ represents a cyclohexyl or a terbutyl,

8. Use according to any one of the preceding claims, characterized in that the X and Y groups are independently selected from linear, branched or cyclic alkylene groups, arylene groups and alkylarylene groups.

9. Use according to any one of the preceding claims, characterized in that M ^{n +} is a metal cation selected from Zn ²⁺ , Cu ²⁺ , Na ⁺ , Li ⁺ and ⁺ .

10. Use according to any one of claims 1 to 8 characterized in that M "^' is a non-metallic cation.

1 1. Use according to any one of the preceding claims, characterized in that the said thiophene compound (s) represent from 0.1 to 7 phr, preferably from 0.5 to 7 phr, better still from 0.5 to 5 phr (parts by weight). percent of diene elastomer).

12. Use according to any one of the preceding claims, characterized in that the diene elastomer (s) are chosen from the group consisting of polybutadienes, natural rubber, synthetic polyisoprenes, butadiene copolymers and isoprene copolymers. and mixtures of these elastomers.

13. Use according to any one of the preceding claims, characterized in that the reinforcing filler or fillers are selected from silica, carbon black and mixtures thereof, preferably carbon black.

14. Use according to any one of the preceding claims, characterized in that the reinforcing filler (s) are present at a level of between 20 and 200 phr, preferably between 30 and 150 phr.

Process for preparing a composition as defined in any one of the preceding claims for the manufacture of tires, characterized in that it comprises the following steps:

- Incorporating into a diene elastomer, during a first step, the reinforcing fillers or by thermomechanically kneading the whole, in one or more times, to reach a maximum temperature between 1 10 ° C and 1 90 ° VS ;

- Then incorporate, in a second step, a crosslinking system and knead the whole to a maximum temperature below 1 10 ° C.

The method of claim 15, wherein between the thermomechanical mixing and the incorporation of the crosslinking system, the assembly is cooled to a temperature of less than or equal to 100 ° C.

7. Use of a composition as defined in any one of claims 1 to 14 for the manufacture of a finished article or a semi-finished product for a motor vehicle ground connection system.

18. A finished article or semi-finished product for a motor vehicle ground connection system, comprising a composition as defined in any one of claims 1 to 14.

9. A tire comprising a rubber composition as defined in any one of claims 1 to 14.

20. A tread comprising a rubber composition as defined in any one of claims 1 to 14.

21. Rubber composition for the manufacture of tires, based on one or more diene elastomers, or a plurality of reinforcing fillers and a vulcanization system, characterized in that said vulcanization system comprises one or more thiophene compounds chosen from the compounds of formula (Ib) below:

in which

Rb, ib and R ₂ b independently of one another, a hydrogen atom, a halogen atom, thiol, hydroxyl, amino or a hydrocarbon group of C ₁ -C ₂₅ selected from linear alkyl groups , branched or cyclic, saturated or unsaturated aralkyl groups, alkylaryl groups and aryl groups, and optionally interrupted by one or more heteroatoms and / or optionally substituted by one or more halogen atoms and / or optionally substituted by one or more thiol, hydroxyl, amino functions; Rb and Rib or Ri and R _2b may together form an aromatic ring or not,

-A represents a group selected from

- a group

in which Rj ₂ represents:

alkyl C 1 -C25 linear or branched, optionally interrupted by one or more heteroatoms, optionally substituted with one or more cyclic alkyl C 3 -C ₁ 0 aryl or C ₆ -C i _2, or a C ₃ -C ₁₀ cyclic alkyl group, optionally interrupted by one or more heteroatoms, optionally substituted with one or more linear, branched or cyclic C 1 -C 25 alkyl or C ₆ -C 12 aryic groups, optionally interrupted by one or more hetero atoms; a group

in which

R _3b , R _4b and Rs independently represent a C 1 -C ₁₈ hydrocarbon group, optionally interrupted by one or more heteroatoms,

y _b is an integer greater than or equal to 1, prefer! less than or equal to 10, more preferably less than or equal to 8 and most preferably less than or equal to 6;

- a group

in which

R _6b denotes a C 1 -C 18 hydrocarbon-based group, optionally interrupted by one or more heteroatoms; a group

R ^b

in which

R _7b denotes a C 1 -C 18 hydrocarbon group, optionally interrupted by one or more heteroatoms;

in which

Y _b represents a C ₁₈ -C ₁₈ hydrocarbon chain, optionally interrupted or substituted by one or more heteroatoms;

R denotes a hydrocarbon group-Ci _®, optionally interrupted by one or more heteroatoms; a

in which

b represents a C 1 -C 18 hydrocarbon-based chain, optionally interrupted or substituted by one or more heteroatoms;

Rçb and Rb désign denote a C₁-C₁ hydrocar hydrocarbon group, optionally interrupted by one or more heteroatoms;

- a group

in which

R i _b denotes a hydrogen atom, a C 1 -C 18 hydrocarbon group, optionally interrupted by one or more heteroatoms.

22. Composition according to Claim 21, characterized in that the groups R _b , Ri _b and R _2b independently represent a hydrogen atom or a methyl group.

23. Composition according to claim 22, characterized in that the groups ¾, Ri _b and R ₂ each represent a hydrogen atom.

24. Composition according to claim 22, characterized in that the group _¾ represents a methyl group and and ₂ b each represent a hydrogen atom.

25. Composition according to any one of claims 21 to 24, characterized in that Ab is the group

wherein R _12b is as defined in claim 21.

26. Use according to any one of claims 21 to

25, characterized in that the groups R3b to _R12b are independently selected from linear, branched or cyclic alkyl groups, aryl groups, aralkyl groups and alkylaryl groups.

27. Use according to any one of claims 21 to

26, characterized in that the group R ₁₂ b represents a cyclohexyl or a terbutylc.

28. Use according to any one of claims 21 to

27, characterized in that the groups X _b and Y _b are independently selected from linear, branched or cyclic alkylene groups, arylene groups and alkylarylene groups.

29. Thiophene of the following formula (Γ):

in which R _a , Ri a and R _2a represent, independently of each other, a hydrogen atom, a halogen atom, a thiol, hydroxyl or amino group, or a C 1 -C 25 hydrocarbon-based group chosen from linear alkyl groups; , branched or cyclic, saturated or unsaturated aralkyl groups, alkylaryl groups and aryl groups, and optionally interrupted by one or more heteroatoms and / or optionally substituted with one or more halogen atoms and / or optionally substituted with one or more several thiol, hydroxyl, amino, R _a and R _{) a} or R ₈ and R _{2a functions that} can together form an aromatic ring or not,

-A _a represents

- a group

^R 12a in leq el R i _2a represents:

al kyle a group -C-C ₁₆ linear or branched, optionally interrupted by one or more heteroatoms, optionally substituted with one or more cyclic alkyl groups, C3-C 10 aryl or C ₆ -C i _2, or

a cyclic C ₃ -C ₁₀ alkyl group, optionally interrupted by one or more heteroatoms, optionally substituted with one or more linear, branched or cyclic C ₁ -C ₂₅ alkyl or C ₆ -C ₁₂ aryl groups, optionally interrupted by one or more heteroatoms,

it being understood that R _a and R _{) 8} , and R _ia and R _2a can not form a ring combination, and

- a group

wherein R _3a , R _a and R _5a independently represent a C 1 -C 18 hydrocarbon group, optionally interrupted by one or more heteroatoms,

y _a is an integer greater than or equal to 1, preferably less than or equal to 10, more preferably less than or equal to 8 and most preferably less than or equal to 6;

- a group

wherein R _7a denotes a C1-C8 hydrocarbon group, optionally interrupted by one or more heteroatoms, with the proviso that R _2a denotes a C1-C12 hydrocarbon group having no heteroatom; a group

in which

X _a is a C -C hydrocarbon chain, optionally interrupted or substituted by one or more heteroatoms, but which can not carry another phosphonate group,

R _9a and Rioa independently represent a C1-C18 hydrocarbon group, optionally interrupted by one or more heteroatoms,

Thiophene according to claim 29, characterized in that

R _a , Ria and R _2a independently represent a hydrogen atom or a methyl group.

31. Thiophene according to claim 30, characterized in that R _a , R and R _2a each represent a hydrogen atom.

32. Thiophene according to Claim 30, characterized in that each R _a represents methyl and R _a and R _2a each represents a hydrogen atom.

33. Thiophene according to any one of claims 29 to 32, characterized in that Aa is the group

^R 12a wherein R _2a is as defined in claim 29.

34. Thiophene according to any one of claims 29 to

33, characterized in that the groups R _3a to R _5a, R _7a, R _a to R _0a e R _2a are independently selected from linear, branched or cyclic, aryl groups, aralkyl groups and alkylarylcs groups.

35. Thiophene according to any one of claims 29 to

34, characterized in that the group R12a represents a cyclohexyl or a terbutyl.

36. Thiophene according to any one of claims 29 to

35, characterized in that the X _a group is independently selected from linear, branched or cyclic alkylene groups, arylene groups and alkylarylene groups.