WO2014016344A1 - Rubber composition comprising a lignin-based resin - Google Patents

Abstract

The invention relates to a rubber composition containing at least one diene elastomer, a reinforcing filler, a cross-linking system, a lignin-based resin and a hardener, with the hardener being selected from among polyamines, polyaldimines, polyketimines or mixtures thereof. The invention also relates to semi-finished tyre products and tyres comprising said composition.

Description

 - -

RUBBER COMPOSITION COMPRISING A LIGNIN-BASED RESIN

The present invention relates to rubber compositions intended in particular for the manufacture of tires or semi-finished products for tires, in particular rubber compositions having a high rigidity.

 It is known to use in certain tire parts, rubber compositions having high rigidity at low tire deformations (see WO 02/10269). Resistance to small deformations is one of the properties that must present a tire to respond to the stresses to which it is subjected.

This stiffening can be obtained by increasing the rate of reinforcing filler or by incorporating certain reinforcing resins into the rubber compositions constituting the parts of the tire.

 However, in a known manner, increasing the stiffness of a rubber composition by increasing the loading rate can penalize the hysteresis properties and therefore the rolling resistance of the tires. However, we always try to lower the rolling resistance of tires to reduce fuel consumption for economic and environmental purposes.

[005] Conventionally, this increase in stiffness is obtained by incorporating reinforcing resins based on an acceptor / methylene donor system. The terms "methylene acceptor" and "methylene donor" are well known to those skilled in the art and widely used to designate compounds capable of reacting together to generate by condensation a three-dimensional reinforcing resin which is superimposed, interpenetrated with the reinforcing filler / elastomer network on the one hand, with the elastomer / sulfur network on the other hand (if the crosslinking agent is sulfur). The methylene acceptor previously described is associated with a hardening agent capable of crosslinking or hardening, also commonly called "methylene donor". The crosslinking of the resin is then caused during the firing of the rubber matrix, by formation of methylenic bridges (-CH ₂ -) between the carbons at the ortho and / or para positions of the phenolic rings of the resin and the methylene donor. and thus creating a three-dimensional resin network.

The methylene donors conventionally used in tire rubber compositions are hexamethylenetetramine (abbreviated to HMT), or hexamethoxymethylmelamine (abbreviated to HMMM or H3M), or hexaethoxymethylmelamine. - -

[007] However, it is desirable to find alternatives to conventional reinforcing resins, in particular allowing an improvement in road behavior, without penalizing the rolling resistance of the tires. Unexpectedly, the Applicants have discovered during their research that the usual reinforcing resins can advantageously be replaced by a resin based on a lignin and a suitable hardener. The use of such a lignin not only makes it possible to obtain rubber compositions having a hysteresis similar to conventional rubber compositions which comprise HMT or H3M methylene donors, but surprisingly to improve the low-deformation rigidity, therefore the road behavior of the tires. In addition, lignin is a natural material which is economically and ecologically very advantageous compared to the resins used up to now in tires.

 Accordingly, a first subject of the invention relates to a rubber composition based on at least one diene elastomer, a reinforcing filler, a crosslinking system, a resin based on lignin and a hardener being understood. the hardener is chosen from polyamines, polyketimines, polyaldimines or mixtures thereof.

 [009] Preferably, the invention relates to a composition as defined above in which the elastomer is chosen from the group consisting of natural rubber, synthetic polyisoprenes, polybutadienes, butadiene copolymers, copolymers of isoprene and mixtures of these elastomers.

 [0010] Preferably also, the invention relates to a composition as defined above in which the level of lignin is in a range from 1 to 35 phr. More preferably, the level of lignin is from 3 to 30 phr, preferably from 5 to 25 phr.

Preferably, the invention relates to a composition as defined above wherein the hardener is a polyamine. Preferably, the hardener is a polyamine compound of general formula (I):

in which A represents a hydrocarbon group comprising at least 2 carbon atoms (preferably from 2 to 18), optionally interrupted by hetero atoms and optionally substituted.

Alternatively and preferably also, the invention relates to a composition as defined above wherein the hardener is a polyaldimine. Preferably, the hardener is a poly-aldimine compound of general formula (II): - -

in which :

R 1, -2, R ₃ and R ₄ independently represent identical or different groups chosen from alkyl groups having from 1 to 20 carbon atoms, cycloalkyl having from 5 to 24 carbon atoms, aryl having from 6 to 30 carbon atoms or aralkyls having 7 to 25 carbon atoms; groups which may possibly be interrupted by heteroatoms and / or substituted,

 A represents a hydrocarbon group comprising at least 2 carbon atoms (preferably from 2 to 18), optionally interrupted by hetero atoms and optionally substituted.

 Alternatively and preferably also, the invention relates to a composition as defined above wherein the hardener is a polyketimine. Preferably, the hardener is a polyketimine compound of general formula (IV):

 R

R ₄

 (IV)

in which :

R 1, R 2, R ₃ and R ₄ independently represent identical or different groups chosen from alkyl groups having from 1 to 20 carbon atoms, cycloalkyls having from 5 to 24 carbon atoms, aryls having from 6 to 30 carbon atoms or aralkyls having 7 to 25 carbon atoms; groups which may possibly be interrupted by heteroatoms and / or substituted,

 A represents a hydrocarbon group comprising at least 2 carbon atoms (preferably from 2 to 18), optionally interrupted by hetero atoms and optionally substituted.

 Preferably, the invention relates to a composition as defined above in which the rate of hardener is in a range from 0.2 to 20 phr. Preferably, the level of hardener is from 0.3 to 10 phr, preferably from 0.5 to 8 phr.

[0015] Preferably, the invention relates to a composition as defined above in which the reinforcing filler comprises carbon black and / or silica.

Preferably, the invention relates to a tire comprising a rubber composition as defined above. - -

[0017] Also, the invention relates to a finished or semi-finished rubber article comprising a rubber composition as defined above.

Alternatively and preferentially also, the invention relates to a method for preparing a rubber composition as defined above, comprising the following steps:

 - Incorporating into a diene elastomer, during a first step (called "nonproductive"), a reinforcing filler, a lignin-based resin and a hardener, thermomechanically kneading the whole until reaching a maximum temperature included between 110 ° C and 190 ° C;

- cool all at a temperature below 100 ° C;

 - Then incorporate, in a second step (called "productive"), a crosslinking system;

 - mix everything up to a maximum temperature below 1 10 ° C.

 Alternatively and preferentially also, the invention relates to a process for preparing a rubber composition as defined above, comprising the following steps:

 - Incorporating into a diene elastomer, during a first step (called "non-productive"), a reinforcing filler, thermomechanically kneading the whole until reaching a maximum temperature between 1 10 ° C and 190 ° C;

- cool all at a temperature below 100 ° C;

 - Then incorporate, during a second step (called "productive"), a crosslinking system, a lignin-based resin and a hardener;

 - mix everything up to a maximum temperature below 1 10 ° C.

 Alternatively and preferentially also, the invention relates to a process for preparing a rubber composition as defined above, comprising the following steps:

 - Incorporating into a diene elastomer, during a first step (so-called "non-productive"), a reinforcing filler, a resin based on lignin, thermomechanically kneading the whole until a maximum temperature of between 10 ° C and 10 ° C is reached. ° C and 190 ° C;

 - cool all at a temperature below 100 ° C;

 - Then incorporate, in a second step (called "productive"), a crosslinking system, a hardener;

 - mix everything up to a maximum temperature below 1 10 ° C.

The invention also relates to tires comprising a rubber composition according to the invention. - -

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

 The tires according to the invention are particularly intended for passenger vehicles such as two-wheeled vehicles (motorcycle, bicycle), industrial vehicles chosen from pickup trucks, "heavy vehicles" - ie, subway, bus, transport vehicles road transport (trucks, tractors, trailers), off-the-road vehicles, agricultural or civil engineering machinery, aircraft, other transport or handling vehicles.

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

I. Tests

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

 1.1. Dynamic Properties

These tests make it possible to determine the elasticity stresses. Unless otherwise indicated, they are carried out in accordance with the French standard NF T 46-002 of September 1988. The secant modulus is measured in second elongation (ie after an accommodation cycle at the extension rate provided for the measurement itself). nominal (or apparent stresses, in MPa) at 10% elongation (denoted MA10). Elongations at break (% AR) are also measured. 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).

The dynamic properties G ^* (10%) and tan (δ) max at 40 ° C are measured on a viscoanalyzer (Metravib VA4000), according to the ASTM D 5992-96 standard. The response of a sample of vulcanized composition (cylindrical specimen 4 mm in thickness and 400 mm ² in section), subjected to a sinusoidal stress in alternating simple shear, at the frequency of 10 Hz, is recorded under normal conditions. temperature (23 ° C) according to ASTM D 1349-99, or as the case may be at a different temperature. A strain amplitude sweep of 0.1 to 50% (forward cycle) and then 50% to 1% (return cycle) are performed. The results exploited are the complex dynamic shear modulus G ^* and the loss factor tan (δ). For the return cycle, the maximum value of tan (δ) observed, denoted tan (δ) max, as well as the complex dynamic shear modulus G ^* (10%) at 10% deformation, at 40 ° C are indicated. - -

It is recalled that, in a manner well known to those skilled in the art, the value of tan (δ) max at 40 ° C is representative of the hysteresis of the material and hence the rolling resistance: plus tan (ô) max at 40 ° C is low, the lower the rolling resistance is reduced.

II. Conditions of realization of the invention

 The rubber composition according to the invention is based on at least one diene elastomer, a reinforcing filler, a crosslinking system, a lignin-based resin and a hardener, it being understood that the hardener is chosen from polyamines, polyketimines, polyaldimines or mixtures thereof.

By the term "composition based" 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 between they, at least in part, during the various phases of manufacture of the composition, in particular during its crosslinking or vulcanization.

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

11.1. Diene elastomer

 The rubber composition according to the invention comprises a diene elastomer.

 By elastomer or "diene" rubber, must be understood in a known way (one means one or more) elastomer derived at least in part (ie, a homopolymer or a copolymer) of monomers dienes (monomers carrying two double bonds carbon-carbon, 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 type EPDM - - do not fall within the above definition and may in particular be described as "essentially saturated" diene elastomers (low or very low diene origin, always less than 15%). In the category of "essentially unsaturated" diene elastomers, the term "highly unsaturated" diene elastomer is particularly understood to mean a diene elastomer having a content of units of diene origin (conjugated dienes) which is greater than 50%.

 These definitions being given, the term diene elastomer may be understood more particularly to be used in the compositions according to the invention:

 any homopolymer obtained by polymerization of a conjugated diene monomer having from 4 to 12 carbon atoms;

 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;

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

 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 art of the tire will understand that the present invention is preferably implemented with essentially unsaturated diene elastomers, in particular of the type (a) or (b) above.

 By way of conjugated dienes 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-di (C 1 -C 5) -alkyl-1,3-butadienes, such as for example 2,3-dimethyl-1,3-butadiene, 2,3-diethyl-1,3-butadiene, 2-methyl-3-ethyl-1,3-butadiene, 2-methyl-3-isopropyl 1,3-butadiene, aryl-1,3-butadiene, 1,3-pentadiene, 2,4-hexadiene. Suitable vinyl aromatic compounds are, for example, styrene, ortho-, meta-, para-methylstyrene, the "vinyl-toluene" commercial mixture, para-tert-butylstyrene, 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 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 amino functional groups such as benzophenone 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), alkoxysilane groups (such as 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 groups polyethers (as described for example in EP 1 127 909 or US Pat. No. 6,503,973). 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 between 4% and 80% or those having a content (mol%) in cis-1, 4 greater than 80%, polyisoprenes, butadiene-styrene copolymers and in particular those having a Tg (glass transition temperature (Tg, measured according to ASTM D3418) between 0 ° C. and -70 ° C. and more particularly between -10 ° C. and -60 ° C. ° 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 (mol%) of trans-1,4 bonds of between 10% and 80%, butadiene-isoprene copolymers 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 between - 25 ° C and - 50 ° C. In the case of butadiene-styrene-isoprene copolymers are especially suitable those having a styrene content of between 5% and 50% by weight and more particularly of between 10% and 40%, 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 of between 6% and 80%, a content (mol%) in units -1, 2 plus -3 , 4 of the isoprenic part between 5% and 70% and a content (mol%) in trans units -1, 4 of the part isoprene of between 10% and 50%, and more generally any butadiene-styrene-isoprene copolymer having a Tg of between -20 ° C. and -70 ° C.

 In summary, the diene elastomer of the composition according to the invention is preferably selected from the group of highly unsaturated diene elastomers 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 isoprene-copolymers. butadiene-styrene (SBIR).

 According to one particular embodiment, the diene elastomer is predominantly (ie, for more than 50 phr) an SBR, whether it is an emulsion-prepared SBR ("ESBR") or a prepared SBR. 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 an average styrene content, for example between 20% and 35% by weight, or a high styrene content, for example 35 to 35% by weight, is used in particular. 45%, a vinyl ring content of the butadiene part of between 15% and 70%, a content (mol%) of trans-1,4 bonds of between 15% and 75% and a Tg of between -10 ° C. and - 55 ° C; such an SBR can be advantageously used in admixture with a BR preferably having more than 90% (mol%) of cis-1,4 bonds.

 By "isoprene 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) 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 be made in particular of isobutene-isoprene (butyl rubber-NR), isoprene-styrene (SIR), isoprene-butadiene (BIR) or isoprene-butadiene-styrene copolymers. (SBIR). This isoprene elastomer is preferably natural rubber or a synthetic cis-1,4 polyisoprene; of 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.

According to another preferred embodiment of the invention, the rubber composition comprises a blend of one (or more) diene elastomers said "high Tg" having a Tg between - 70 ° C and 0 ° C and a (one or more) diene elastomers called "low Tg" 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 cis-1,4 preferably greater than 95%), BIRs, SIRs, SBIRs, and mixtures of these elastomers. The low Tg elastomer 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 Tg 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 comprises a blend of a BR (as a low elastomer Tg) having a molar ratio (mol%) of cis-1, 4 chains higher than 90%, with one or more S-SBR or E-SBR (as elastomer (s) high Tg).

 The compositions of the invention may contain a single diene elastomer or a mixture of several diene elastomers, or the diene elastomers may be used in combination with any type of synthetic elastomer other than diene, or with polymers other than elastomers, for example thermoplastic polymers.

II.2. Reinforcing charge

 It is possible to use 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 blend of these two types of filler, including a carbon black and silica blend.

As carbon blacks are suitable for all black carbon, including black type HAF, ISAF, SAF conventionally used in tires (so-called pneumatic grade black). Among these, mention will be made more particularly of reinforcing carbon blacks of the 100, 200 or 300 series (ASTM grades), such as, for example, N 1 15 blacks, - -

N134, N234, N326, N330, N339, N347, N375, or, depending on the intended applications, black higher series (eg N660, N683, N772). The carbon blacks could for example already be incorporated into an 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 functionalized polyvinyl organic fillers such as described in applications WO-A-2006/069792, WO-A-2006/069793, WO-A-1, 2008/003434 and WO-A-2008/003435.

 By "reinforcing inorganic filler" must be understood in the present application, by definition, any inorganic or mineral filler (whatever its color and its natural or synthetic origin), also called "white" charge, charge " clear "or" non-black filler "charge as opposed to carbon black, capable of reinforcing on its own, with no other means than an intermediate coupling agent, a rubber composition for the manufacture of pneumatic, in other words able to replace, in its reinforcing function, a conventional carbon black pneumatic grade; such a filler is generally characterized, in known manner, by the presence of hydroxyl groups (-OH) on its surface.

 The physical state under which the reinforcing inorganic filler 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.

As reinforcing inorganic fillers are particularly suitable mineral fillers of the siliceous type, in particular of silica (SiO ₂ ), or of the aluminous type, in particular of alumina (Al ₂ 0 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 / boy Wut. As highly dispersible precipitated silicas (referred to as "HDS"), mention may be made, for example, of the silicas Ultrasil 7000 and Ultrasil 7005 from the company Degussa, the silicas Zeosil 1 165MP, 1 135MP and 1 1 15MP from the company Rhodia, the silica Hi -Sil EZ150G from the PPG company, the Zeopol 8715, 8745 and 8755 silicas of the Huber Company, the high surface area silicas as described in the application WO 03/16837. - -

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 total reinforcing filler content (carbon black and / or reinforcing inorganic filler such as silica) is between 20 and 200 phr, more preferably between 30 and 150 phr, the optimum being in a known manner. different depending on the particular applications targeted: the level of reinforcement expected on a bicycle tire, for example, is of course less than that required on a tire capable of driving at high speed in a sustained manner, for example a motorcycle tire, a tire for a vehicle for tourism or for commercial vehicles such as Trucks.

 According to a preferred embodiment of the invention, a reinforcing filler comprising between 30 and 150 phr is used, more preferably between 50 and 120 phr of inorganic filler, particularly 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).

 To couple the reinforcing inorganic filler to the diene elastomer, is used in known manner a coupling agent (or bonding agent) at least bifunctional for ensuring a sufficient connection, chemical and / or physical, between the inorganic filler (surface of its particles) and the diene elastomer, in particular organosilanes or bifunctional polyorganosiloxanes.

 In particular, polysulfide silanes, called "symmetrical" or "asymmetrical" according to their particular structure, are used, as described for example in the applications WO03 / 002648 (or US 2005/016651) and WO03 / 002649 (or US 2005 / 016650).

 In particular, the following definition is not limiting, so-called "symmetrical" polysulfide silanes corresponding to the following general formula (I):

 (I) Z - A - Sx - A - Z, wherein:

 x is an integer of 2 to 8 (preferably 2 to 5);

 - A is a divalent hydrocarbon radical (preferably C 1 -C 18 alkylene groups or C 6 -C 12 arylene groups, more particularly C 1 -C 10 alkylenes, especially C 1 -C 4 alkylenes, in particular propylene);

Z is one of the following formulas: - -

R1 R1 R2

 -Si-R1; - Si- R2; - Si- R2,

 In which:

 the radicals R1, which may be substituted or unsubstituted, which are identical to or different from one another, represent a C1-C18 alkyl, C5-C18 cycloalkyl or C6-C18 aryl group (preferably C1-C6 alkyl, cyclohexyl or phenyl groups, especially C1-C4 alkyl groups, more particularly methyl and / or ethyl).

 the radicals R2, substituted or unsubstituted, identical or different from each other, represent a C 1 -C 18 alkoxyl or C 5 -C 18 cycloalkoxyl group (preferably a group chosen from C 1 -C 8 alkoxyls and C 5 -C 8 cycloalkoxyls, more preferentially still another group chosen from C 1 -C 4 alkoxyls, in particular methoxyl and ethoxyl).

 In the case of a mixture of polysulfurized alkoxysilanes corresponding to formula (I) above, especially commercially available mixtures, the average value of "x" is a fractional number preferably between 2 and 5 more preferably close to 4. However, the invention can also be advantageously used for example with disulfide alkoxysilanes (x = 2).

 By way of examples of polysulphurized silanes, mention may be made more particularly of polysulfides (in particular disulfides, trisulphides or tetrasulfides) of bis (C 1 -C 4 alkoxyl) -alkyl (C 1 -C 4) alkyl-silyl (C 1 -C 4) )), such as, for example, bis (3-trimethoxysilylpropyl) or bis (3-triethoxysilylpropyl) polysulfides. Among these compounds, bis (3-triethoxysilylpropyl) tetrasulfide, abbreviated TESPT, of formula [(C2H50) 3Si (CH2) 3S2] 2 or bis (triethoxysilylpropyl) disulfide, abbreviated as TESPD, is especially used. formula [(C2H50) 3Si (CH2) 3S] 2. Mention may also be made, by way of preferred examples, of polysulfides (in particular disulfides, trisulphides or tetrasulfides) of bis- (monoalkoxyl (C1 -C4) -dialkyl (C1 -C4) silylpropyl), more particularly bis-monoethoxydimethylsilylpropyl tetrasulfide as described in the patent application WO 02/083782 (or US 2004/132880).

As a coupling agent other than polysulfurized alkoxysilane, there may be mentioned in particular bifunctional POS (polyorganosiloxanes) or hydroxysilane polysulfides (R2 = OH in formula I above) as described in the patent applications. WO 02/30939 (or US 6,774,255) and WO 02/31041 (or US 2004/051210), or alternatively silanes or POS bearing azo-dicarbonyl functional groups, as described for example in patent applications WO 2006/125532, WO 2006/125533, WO 2006/125534.

 In the rubber compositions according to the invention, the content of coupling agent is preferably between 4 and 12 phr, more preferably between 4 and 8 phr.

 Those skilled in the art will understand that as an equivalent load of the reinforcing inorganic filler described in this paragraph, could be used a reinforcing filler of another nature, especially organic, since this reinforcing filler would be covered an 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.

11 -3 - Lignine

The composition according to the invention comprises a resin based on a lignin and a hardener.

 Lignin is one of the essential components of plant walls, with cellulose, hemicelluloses and pectins. Its main functions are to provide rigidity, and impermeability to water. All plants produce lignin. Its content is lower in annuals than in perennials, and is highest in trees. Quantitatively, the lignin content is 3 to 5% in the leaves, 5 to 20% in the herbaceous stems, 15 to 35% in the woody stems (C. Lapierre, Session of the Academy of Agriculture, February 17, 2010 , listed in Wikipedia). Since lignin is a very abundant biopolymer on Earth, it is interesting to use it in rubber compositions for both economic and environmental reasons.

Lignin is a natural polymer that ensures the rigidity of the plant by binding the cell wall fibers to each other. Composed of substituted phenylpropanoic units and linked together by various types of CC and CO bonds, lignin is a polymer of relatively complex structure and very dependent on the botanical origin and the extraction method undergone (D Fengel G. Wegener Wood, Chemistry, Ultrastructure, Reactions, Walter de Gruyter and Co., Berlin, 1983, 66 - 181). Lignin has a wide variety of functional groups, such as cinnamic double bonds, hydroxyl groups (phenolic and alcoholic), methoxyls, carbonyls and carboxyls, on its alkylaromatic backbone. - -

The 3 base units from which lignin is synthesized by the plant are coumaryl alcohol, coniferyl alcohol and sinapyl alcohol. Also referred to as p-hydroxyphenyl, guaiacyl and syringyl units. In ortho phenol groups, methoxy groups can be found. Depending on the origin of the plant and the species, the different patterns are more or less present (Nimez 1974, Adler 1980, Sjostrom 1981, Chen 1991, Ede and Kilpelaeinen 1995, Karhunen et al., 1995, 1996). Ralph, 1999).

 Thus, there are several varieties of lignins according to their plant origin and according to their extraction process. Several extraction processes are known to those skilled in the art and in particular the Kraft process.

The Kraft process was developed in 1870 in Germany, it is based on the use of sodium hydroxide and sodium sulphide. It was very developed in the 30's and is the most used process in the paper industry today. This process is described, for example, by Ciullo P.A. in "Papermaking, in Industrial Minerals and their uses - A Handbook of Formulation, 1996; pp. 166-169 ".

A chemical structure of lignin can be represented as below (Wikipedia article):

The lignin used in the composition according to the invention may be a lignin as obtained after extraction. It can also be used after being functionalized by chemical modification. For example, several modifications of the extracted lignin have been - - described: oxyakylation, epoxidation, phenolation, carboxylation, methylolation, sulfonation, acrylation, phosphorylation. For example, the lignin may be epoxidized, for example by the action of a peracid or by the action of epichlorohydrin. An example of hydroxyalkylated and then epoxidized lignin can be represented by the structure below:

According to a preferred embodiment of the invention, the amount of lignin is preferably in a range from 1 to 35 phr; below the minimum indicated, the technical effect is insufficient, while beyond the maximum indicated, one faces the risk of very high stiffening and increased hysteresis. Preferably, the level of lignin is from 3 to 30 phr, and even more preferably from 5 to 25 phr.

In order to form a reinforcing resin, it is possible to associate with the lignin a hardener selected from the hardeners described below. - -

11.4. Curing

 The resin described above is associated with a hardening agent capable of crosslinking or curing. According to the invention, and associated with a lignin as resin, this curing agent can be of several chemical natures: it can be a polyamine, a polyaldimine, a polyketimine or a mixture of the latter. .

 The crosslinking of the resin is caused during the baking of the rubber matrix, by formation of covalent bonds between the resin and the amine and / or imine functions of the hardener.

 The amount of hardener is preferably in a range from 0.2 to 20 phr; below the minimum indicated, the technical effect has been found to be insufficient, while beyond the maximum indicated, one is exposed to the risk of penalization of the implementation in the green state of the compositions. Preferably, the level of hardener is from 0.3 to 10 phr and even more preferably from 0.5 to 8 phr.

 11.4.1. Polyamine hardener

 The compositions of the invention use a hardener which may be a primary polyamine. In this case it can be any chemical compound having at least two primary amino functions. These compounds are easily identified by those skilled in the art.

The polyamines include in particular a polyamine compound of general formula (I),

in which A represents a hydrocarbon group comprising at least 2 carbon atoms (preferably from 2 to 18), optionally interrupted by hetero atoms and optionally substituted.

 By group or chain interrupted (e) by one or more heteroatoms is meant (throughout the present application) a group or chain comprising one or more heteroatoms, each heteroatom being between two carbon atoms of said group or of 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.

Furthermore, A may also be substituted by one or more primary amine functions (NH ₂ ) and / or by one or more radicals such as alkyl, cycloalkyl, - - cycloalkylalkyl, aralkyl, themselves substituted by one or more primary amino functions (NH ₂ ).

 The polyamine compounds include, in particular, aliphatic polyamines such as ethylenediamine, diethylenetriamine, and triethylenetetramine, in particular 1,8-diaminooctane, alicyclic polyamines such as 1,3 bis (aminomethyl) cyclohexane, and polyamines. aliphatic compounds comprising an aromatic ring such as m-xylylenediamine, p-xylylenediamine, and aromatic polyamines such as m-phenylenediamine, 2,2-bis (4-aminophenyl) propane, diaminodiphenylmethane, diaminodiphenylsulfone, 2,2-bis ( 4-aminophenyl) -p-diisopropylbenzene, especially 3,3'-diaminobenzidine.

 According to a preferred embodiment of the invention, the polyamine curative is chosen from p-xylylenediamine, 1,3-bis (aminomethyl) cyclohexane, 1,8-diaminooctane and 3,3'-diaminobenzidine. .

 II.4.2. Polyaldimine hardener

 The compositions of the invention use a hardener which may be a polyaldimine. In this case it may be any chemical compound having at least two aldimine functions. These compounds are easily identified by those skilled in the art.

The polyaldimines include in particular a poly-aldimine compound of general formula (II),

in which :

R 1 and R ₂ independently represent identical or different groups chosen from alkyl groups having from 1 to 20 carbon atoms, cycloalkyls having from 5 to 24 carbon atoms, aryls having from 6 to 30 carbon atoms or aralkyls having from 7 to 25 carbon atoms; groups which may possibly be interrupted by heteroatoms and / or substituted,

 - A represents a hydrocarbon group having at least 2 carbon atoms (preferably 2 to 18), optionally interrupted by hetero atoms and optionally substituted.

Preferably R 1 and R ₂ independently represent identical or different groups chosen from alkyl groups having from 1 to 12 carbon atoms, cycloalkyls having from 5 to 8 carbon atoms, aryls having from 6 to 24 carbon atoms. carbon or aralkyls having 7 to 13 carbon atoms; groups that can be substituted. More preferably, R 1 and R ₂ each represent an aryl radical having from 6 to 24 carbon atoms, and even more preferably, an optionally substituted phenyl radical.

Also preferably, A represents a hydrocarbon group having 2 to 18 carbon atoms, optionally interrupted by hetero atoms and optionally substituted. More preferably, A represents an alkylene or cycloalkylene group containing from 2 to 18 carbon atoms, optionally interrupted by hetero atoms and optionally substituted; or an aralkylene containing from 8 to 18 carbon atoms, optionally interrupted by hetero atoms and optionally substituted, it being understood that in the alkylene or aralkylene carbon chains optionally interrupted by heteroatoms and optionally substituted, there may be double or triple bonds between carbon atoms. In a very preferential manner, A represents an alkylene group comprising from 2 to 12 carbon atoms, more preferably from 2 to 8 carbon atoms (in particular 6 carbon atoms), this radical being optionally substituted.

As indicated in the preceding paragraphs, the groups R 1, R ₂ and A may optionally be interrupted by heteroatoms, such as S, O or N, preferably N or O. For the purposes of the present invention, it is necessary to heteroatom-interrupted group means a group which comprises between its end atoms (which are carbon atoms, as defined by the definitions of the hydrocarbon groups in question), one or more heteroatoms as previously proposed. Preferably, the groups R 1, R ₂ and A are not interrupted by heteroatoms.

As indicated in the preceding paragraphs, the groups R 1, R ₂ and A may be substituted. The radicals substituting these groups may be common radicals known to those skilled in the art such as alkyl (preferably methyl, tert-butyl or isopropyl), cycloalkyl (preferably cyclohexyl), cycloalkylalkyl, aryl, aralkyl, hydroxyl, alkoxy, amino , carboxy, or carbonyl.

Furthermore, A may also be substituted by one or more aldimine entities of formula (III) and / or by one or more radicals such as alkyl, cycloalkyl, cycloalkylalkyl or aralkyl, themselves substituted by one or more aldimine entities. of formula (III): - -

in which R ₃ is independently defined as R 1 and R ₂ above, the arrow representing the point of attachment of the radical or radicals of formula (III) with the atom carrying them.

Thus, the compounds of formula (II), comprise at least two aldimine entities, and may contain more, for example, three or four depending on the nature of the substituent groups of the group A.

 According to a preferred embodiment, the compounds of formula (II) comprise two aldimine entities, that is to say that the group A is not substituted with radicals comprising one or more aldimine entities of formula ( III) as defined above.

 According to another preferred embodiment, the compounds of formula (II) comprise more than two aldimine entities, that is to say that the group A is substituted with a radical comprising one or more aldimine entities of formula (III) as defined above.

 More preferentially, these poly-aldimine compounds are chosen from the following compounds:

 N, N'-bis [phenylmethylene] ethane-1,2-diamine

 N, N'-bis [phenylmethylene] hexane-1,6-diamine,

N, N'-bis [phenylmethylene] octane-1,8-diamine,

 N, N'-bis [phenylmethylene] cyclohexane-1,4-diamine,

 N, N'-bis [phenylmethylene] cyclohexane-1,2-diamine,

 N, N'-bis [phenylmethylene] -3- [9- (3-aminopropyl) -1,5,7,1-tetraoxaspiro [5.5] undec-3-yl] propan-1-amine

N, N'-bis [4-methoxyphenylmethylene] -3- [9- (3-aminopropyl) -1,5,7,1-tetraoxaspiro [5.5] undec-3-yl] propan-1-amine

 N, N, N-Tris (2 - {[phenylmethylene] amino} ethyl) amine,

 N, N'-bis [(4-diethylaminophenyl) methylene] hexane-1,6-diamine,

N, N'-bis [mesitylmethylene] hexane-1,6-diamine, - -

N, N'-bis [(4-methylphenyl) methylene] hexane-1,6-diamine,

 N, N'-bis [(4-diethylaminophenyl) methylene] octane-1,8-diamine,

 N, N'-bis [mesitylmethylene] octane-1,8-diamine,

 N, N'-bis [(4-methylphenyl) methylene] octane-1,8-diamine,

N, N'-bis [(4-methoxyphenyl) methylene] hexane-1,6-diamine,

 N, N'-bis [(2-diethylaminophenyl) methylene] hexane-1,6-diamine,

 N, N'-bis [(2-methoxyphenyl) methylene] hexane-1,6-diamine,

 N, N'-bis [(2,4,6-triisopropylphenyl) methylene] hexane-1,6-diamine,

 N, N'-bis [(2,4,6-tri-tert-butylphenyl) methylene] hexane-1,6-diamine,

N, N'-bis [(2,4,6-tricyclohexylphenyl) methylene] hexane-1,6-diamine,

 N, N'-bis [(2,6-diisopropyl-4-methylphenyl) methylene] hexane-1,6-diamine,

 N, N'-bis [(2,6-di-tert-butyl-4-methylphenyl) methylene] hexane-1,6-diamine,

 N, N'-bis [(2,6-dicyclohexyl-4-methylphenyl) methylene] hexane-1,6-diamine.

 As poly-aldimine compounds are preferably used di-aldimine compounds, tri-aldimines and tetra-aldimines. These compounds and their method of preparation are described in the state of the art essentially to improve the abrasion resistance of rubber compositions intended for the manufacture of tires for vehicles, and patent application JP2006063206A1 may be cited in this respect. above, or for the preparation of resins according to the method described in US Patent 3,668,183.

The poly-aldimine compounds may for example be synthesized by condensing an amine on an aldehyde. This mode of preparation of aldimines is described in "Advanced Organic Chemistry, Part B: Reactions and Synthesis" by FA Carey and RJ Sundberg, 4th Edition, p 31-33, as well as in "Advanced Organic Chemistry, Reactions, Mechanisms, and Structure "by J. March, 5th Edition, pp.1185-1187 and in the references cited by these works.

 For example, if we consider the di-aldimines, those of general formula (II) may in particular be prepared by the condensation of a diamine and one or two aldehydes, simultaneously or successively, depending on the molecule is symmetrical or non-symmetrical.

The same type of synthesis is applicable to the synthesis of poly-aldimines, using the appropriate starting reagents, for example triamines for tri-aldimines. - - of general formula (II), tetramines for tetra-aldimines of general formula (II), etc.

 As regards the compounds of general formula (II), the amines used for the synthesis of these products are compounds comprising at least two amino functions. As such, these compounds can be diamines or polyamines such as triamines, tetramines, etc.

 By way of example of diamines useful for the synthesis of di-aldimines for the invention, mention may be made, for example, of ethylenediamine, 1,2-propylenediamine, 3,3'-dimethyl-4,4'- diamino-dicyclohexylmethane, 4,4'-diaminodicyclohexylmethane, isophore diamine, neopentane diamine, (2,2-dimethyl-propane-1,3-diamine), 1,8-octamethylenediamine, 1,3-diaminopropane, 1,6-hexamethylenediamine, 1,2-diaminocyclohexane, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, and preferably 1,8-octamethylenediamine, 1,6-hexamethylenediamine, 1,2-diaminocyclohexane, 1,4-diaminocyclohexane, 3- [9- ( 3-aminopropyl) -1,5,7,1 1 -tetraoxaspiro [5.5] undec-3-yl] propan-1-amine.

 For example, 4,7,10-trioxatridecane-1,3-diamine, 4,9-dioxadodecane-1,2-diamine, N-3-amine- (3- (2-aminoethylamino)) may also be mentioned. propylamine), diethylenetriamine, dipropylene triamine, N, N-Bis- (3-aminopropyl) methylamine, N-4-amine- (N, N'-bis (3-aminopropyl) -ethylenediamine), 2,4-diamino- 6-methyl-1,3,5-triazine, 2,4-diamino-6-phenyl-s-triazine, melamine, triethylenetetramine, tetraethylenepentamine, 2,2 ', 2 "-nitrilotriethylamine, 3,6-dioxaoctane-1, 8-diamine, N, N, N-tris (2-aminoethyl) amine, bis (3-aminopropyl) tetramethyldisiloxane, 2- (2-aminoethoxy) ethanamine, 3- {2- [2- (3-aminopropoxy) ethoxy] ethoxy} propan-1-amino, 3- [4- (3-aminopropoxy) phenoxy] propan-1-amino, 3- {2- (3-aminopropoxy) -1 - [(3-aminopropoxy) methyl] ethoxy} propan -1-Amino, 2 - ({2 - [(2-aminophenyl) thio] ethyl} thio) aniline, 2 - [(3 - {[(2-aminophenyl) thio] methyl} -2,4,6-trimethylbenzyl thio] aniline, 2 - ({4 - [(2-aminophenyl) thio] but-2-enyl} thio) aniline, and preferentially N, N-bis ( 2-aminoethyl) ethane-1,2-diamine.

 By way of example of triamines and tetramines useful for the synthesis of tri-aldimines and tetra-aldimines for the invention, mention may be made of tris (2-aminoethyl) amine, N, N-bis (2- aminoethyl) -N- {2 - [(2-aminoethyl) amino] ethyl} amine, N, N-bis (2-aminoethyl) butane-1,4-diamine, N, N-bis (2-aminoethyl) -N - {2- [bis (2-aminoethyl) amino] ethyl} amine, 2-

(aminomethyl) hexane-1,6-diamine, 2,2-bis (aminomethyl) hexane-1,6-diamine, 2,5-bis (aminomethyl) hexane-1,6-diamine, 3,5-diaminocyclohexylamine, 1 [3,5-bis (aminomethyl) phenyl] methanamine. - -

As an example of aldehydes useful for the synthesis of tri-aldimines and tetra-aldimines for the invention, there may be mentioned benzaldehyde, 4-methoxybenzaldehyde, 4- (diethylamino) benzaldehyde, 4-methylbenzaldehyde, 2 methoxybenzaldehyde, 2,4-dimethoxybenzaldehyde, 2,4-dimethylbenzaldehyde, 2,4,6-trimethylbenzaldehyde, 2,6-diisopropyl-4-methylbenzaldehyde, 2,4,6-triisopropylbenzaldehyde, 2,6-di-tert-butyl 4-methylbenzaldehyde, 2,4,6-tri-tert-butylbenzaldehyde, 1-naphthaldehyde, 2,6-dicyclohexyl-4-methylbenzaldehyde, 2,4,6-tricyclohexyl-4-methylbenzaldehyde, 1-naphthaldehyde, 2-naphthaldehyde 1,1'-biphenyl-2-carbaldehyde, 1H-indole-5-carbaldehyde, 5-methylthiophene-2-carbaldehyde, 3,5-dimethyl-1H-pyrrole-2-carbaldehyde, 1-ethyl-1H pyrrole-2-carbaldehyde, 1H-indole-3-carbaldehyde, quinoline-4-carbaldehyde.

 II.4.3. Polyketimine hardener

 The compositions of the invention use a hardener which may be a polyketimine. In this case it can be any chemical compound having at least two ketine functions. These compounds are easily identified by those skilled in the art.

 The polyketimines include in particular and preferably the polyketimine compounds of general formula (IV),

in which :

R 1, R ₂ , R ₃ and R ₄ independently represent identical or different groups chosen from alkyl groups having from 1 to 20 carbon atoms, cycloalkyls having from 5 to 24 carbon atoms, aryls having from 6 to 30 carbon atoms; or aralkyls having 7 to 25 carbon atoms; groups which may possibly be interrupted by heteroatoms and / or substituted,

 - A represents a hydrocarbon group having at least 2 carbon atoms (preferably 2 to 18), optionally interrupted by hetero atoms and optionally substituted.

Preferably, R ₁ , R ₂ , R ₃ and R ₄ independently represent identical or different groups chosen from alkyl groups having from 1 to 12 carbon atoms, cycloalkyls having from 5 to 8 carbon atoms, aryls having from 1 to 12 carbon atoms, and 6 to 24 carbon atoms or aralkyls having 7 to 13 carbon atoms; groups that can be substituted. More preferably, R-1, R ₂ , R ₃ and R ₄ - - each represent an aryl radical having from 6 to 24 carbon atoms, and more preferably still, an optionally substituted phenyl radical.

 Also preferably, A represents a hydrocarbon group having 2 to 18 carbon atoms, optionally interrupted by hetero atoms and optionally substituted. More preferably, A represents an alkylene or cycloalkylene group containing from 2 to 18 carbon atoms, optionally interrupted by hetero atoms and optionally substituted; or an aralkylene containing from 8 to 18 carbon atoms, optionally interrupted by hetero atoms and optionally substituted, it being understood that in the alkylene or aralkylene carbon chains optionally interrupted by heteroatoms and optionally substituted, there may be double or triple bonds between carbon atoms. In a very preferential manner, A represents an alkylene group comprising from 2 to 12 carbon atoms, more preferably from 2 to 8 carbon atoms (in particular 6 carbon atoms), this radical being optionally substituted.

As indicated in the preceding paragraphs, the groups R 1, R ₂ , R ₃ , R ₄ and A may be optionally interrupted by heteroatoms, such as S, O or N, preferably N or O. In the meaning of According to the present invention, heteroatom-interrupted group means a group which comprises between its end atoms (which are carbon atoms, as defined by the definitions of the hydrocarbon groups in question), one or more heteroatoms such as previously proposed. Preferably, the groups R 1, R ₂ , R 3, R ₄ and A are not interrupted by heteroatoms.

As indicated in the preceding paragraphs, the groups R 1, R ₂ , R ₃ , R ₄ and A may be substituted. The radicals substituting these groups may be common radicals known to those skilled in the art such as alkyl (preferably methyl, tert-butyl or isopropyl), cycloalkyl (preferably cyclohexyl), cycloalkylalkyl, aryl, aralkyl, hydroxyl, alkoxy, amino , carboxy, or carbonyl.

Furthermore, A may also be substituted with one or more ketimine moieties of formula (V) and / or with one or more radicals such as alkyl, cycloalkyl, cycloalkylalkyl or aralkyl, which are themselves substituted by one or more ketimine moieties. of formula (V):

(V) in which R ₅ and R ₆ are independently defined as R 1, R ₂ , R 3 and R ₄ above, the arrow representing the point of attachment of the radical or radicals of formula (V) with the atom that carries them.

 Thus, the compounds of formula (IV), comprise at least two ketines, and may contain more, for example, three or four depending on the nature of the substituent groups of the group A.

 According to a preferred embodiment, the compounds of formula (IV) comprise two kétimine entities, that is to say that the group A is not substituted by radicals comprising one or more kétimine entities of formula ( V) as defined above.

 According to another preferred embodiment, the compounds of formula (IV) comprise more than two kétimine entities, that is to say that the group A is substituted with a radical comprising one or more kétimine entities of formula (V) as defined above.

More preferentially, these poly-ketimine compounds are chosen from the following compounds:

 - B, Ν'-bis (4-methylpentan-2-ylidene) hexane-1,6-diamine,

 N, N'-bis (2,6-dimethylheptan-4-ylidene) hexane-1,6-diamine,

 N, N'-bis (2,4-dimethylpentan-3-ylidene) hexane-1,6-diamine,

- B, Ν'-bis (4-methylpentan-2-ylidene) octane-1,8-diamine,

 N, N'-bis (2,6-dimethylheptan-4-ylidene) octane-1,8-diamine,

 N, N'-bis (2,4-dimethylpentan-3-ylidene) octane-1,8-diamine,

 N, N'-dicyclopentylidenehexane-1,6-diamine,

 N, N'-dicyclopentylideneoctane-1,8-diamine,

N, N'-dicyclohexylidenehexane-1,6-diamine,

 N, N'-dicyclohexylideneoctane-1,8-diamine,

 N, N'-bis (4-methylpentan-2-ylidene) cyclohexane-1,4-diamine,

 N, N'-bis (4-methylpentan-2-ylidene) cyclohexane-1,2-diamine,

 N, N'-bis (2,6-dimethylheptan-4-ylidene) cyclohexane-1,4-diamine,

N, N'-bis (2,6-dimethylheptan-4-ylidene) cyclohexane-1,2-diamine,

 N, N'-dicyclohexylidenecyclohexane-1,4-diamine,

 N, N'-dicyclohexylidenecyclohexane-1,2-diamine,

N- (4-methylpentan-2-ylidene) -, N ', N'-bis ((4-methylpentan-2-ylideneamino) ethyl) ethane-1,2-diamine, - -

- N- _{(2-6-dimethylheptan-4-ylidene!) ^-N,!} N'-bis (2- (2,6-dimethylheptan-4-ylideneamino) ethyl) ethane-1,2-diamine.

 As poly-ketimine compounds are preferably used di-ketimines, tri-ketimines and tetra-ketimines compounds. Poly-ketimine compounds can for example be synthesized by condensing an amine on a ketone. This method of preparation of ketimines is described in "Advanced Organic Chemistry, Part B: Reactions and Synthesis" by FA Carey and RJ Sundberg, 4th Edition, pp. 31-33, as well as in "Advanced Organic Chemistry, Reactions, Mechanisms, and Structure". By J. March, 5th Edition, pp.1185-1187 and in the references cited by these works.

For example, if we consider di-ketimines, those of general formula (IV) may in particular be prepared by the condensation of a diamine and one or two ketones, simultaneously or successively, depending on the molecule is symmetrical or non-symmetrical.

 The same type of reaction is applicable to the synthesis of poly-ketimines, using the appropriate starting reagents, for example triamines for tri-ketimines of general formula (IV), tetramines for tetra-ketimines of formula General (IV), etc.

 Regarding the compounds of general formula (IV), the polyamines used for the synthesis of these products are the same as those described above for the synthesis of poly-aldimines.

 As examples of ketones useful for the synthesis of polyketimines for the invention, mention may be made of pentan-3-one, 2,2,6,6-tetramethylcyclohexanone, 2,2,4,4-tetramethyl-3-pentanone 4-methylpentan-2-one, 2,4-dimethylpentan-3-one, 2,6-dimethylheptan-4-one, cyclohexanone, acetone, 2,6-dimethylcyclohexanone, 2,2,4,4-tetramethylpentan-3 -one, (1, 1 ', 3', 1 ") ter (cyclohexan) -2'-one, dicyclohexylmethanone, dicyclopentylmethanone, cyclopentanone, bicyclo [3.3.1] nonan-9-one, dicyclopropylmethanone, 2,6-di -tert-butyl-cyclohexanone, 2,6-dimethylcyclohexanone, 2,4-dimethyl-3-pentanone and preferentially 4-methylpentan-2-one, 2,4-dimethylpentan-3-one, 2,6-dimethylheptan-4- one, cyclohexanone, cyclopentanone.

II.5. Crosslinking system

The crosslinking system may be a vulcanization system, it is preferably based on sulfur or sulfur donors and primary vulcanization accelerator (preferably 0.5 to 10.0 pce primary accelerator). To this vulcanization system are optionally added, various secondary accelerators and / or known vulcanization activators such as zinc oxide (preferentially for 0.5 to 10.0 phr), stearic acid, guanidine derivatives (in particular diphenylguanidine), or other (preferentially for 0.5 to 5.0 phr each). ). Sulfur is used at a preferential rate of between 0.5 and 10 phr, more preferably between 0.5 and 5.0 phr, for example between 0.5 and 3.0 phr, when the invention is applied to a strip. of tire rolling.

 As accelerator (primary or secondary) can be used any compound capable of acting as an accelerator for vulcanization of diene elastomers in the presence of sulfur, in particular thiazole type accelerators and their derivatives, accelerators of the thiuram type, dithiocarbamates of zinc. 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 sulfenamide (abbreviated "DCBS"), N-tert-butyl-2-benzothiazyl sulfenamide (abbreviated "TBBS"), N-tert-butyl-2-benzothiazyl sulfenimide (abbreviated "TBSI"), zinc dibenzyldithiocarbamate (in abbreviated "ZBEC") and mixtures of these compounds. Preferably, a primary accelerator of the sulfenamide type is used.

 [00121] Preferably, the composition of the invention is devoid of guanidine derivative or contains less than 0.5 phr. Preferably, the composition is either totally devoid of such compounds, or it contains less than 0.45 phr, preferably less than 0.4 phr, more preferably less than 0.3 phr, preferably less than 0, 2 phr and very preferably less than 0.1 phr. The term "guanidine derivative" is understood to mean the organic compounds bearing as their main function a guanidine function, such as those known in tire compositions, in particular as vulcanization accelerators, for example diphenylguanidine (DPG) or diorthotolylguanidine (DOTG).

 According to a preferred embodiment, in the tire according to the invention, the composition of the invention may be devoid of zinc or contains less than 0.5 phr, preferably less than 0.3 phr, more preferably less than 0. , 2 phr and very preferably less than 0.1 phr.

He .6. Various additives

The rubber compositions of the treads according to the invention also comprise all or part of the usual additives usually used in elastomer compositions for the production of treads, - As for example pigments, protective agents such as anti-ozone waxes, anti-ozonants chemical, anti-oxidants, anti-fatigue agents, reinforcing resins other than those mentioned above or plasticizers ,. Preferably this plasticizer is a solid hydrocarbon resin (or plasticizing resin), an extender oil (or plasticizing oil), or a mixture of both.

 These compositions may also contain, in addition to the coupling agents, coupling activators, inorganic charge-covering agents or, more generally, processing aid agents that may be used in a known manner, by means of an improvement. of the dispersion of the filler in the rubber matrix and a lowering of the viscosity of the compositions, to improve their ability to implement in the green state, these agents being, for example, hydrolysable silanes such as alkylalkoxysilanes, polyols, polyethers, primary, secondary or tertiary amines, hydroxylated or hydrolyzable polyorganosiloxanes.

II.7. Preparation of rubber compositions

 The compositions used in the treads of the invention can be manufactured in appropriate mixers, using two successive preparation phases well known to those skilled in the art: a first phase of work or thermomechanical mixing (phase so-called "non-productive") at a high temperature, up to a maximum temperature of between 1 10 ° C and 190 ° C, preferably between 130 ° C and 180 ° C, followed by a second phase of mechanical work (phase so-called "productive") to a lower temperature, typically below 1 10 ° C, for example between 40 ° C and 100 ° C, finishing phase during which the crosslinking system is incorporated.

 The process for preparing such compositions comprises for example the following steps:

 - Incorporating into a diene elastomer, during a first step (called "non-productive"), a reinforcing filler, thermomechanically kneading the whole (for example in one or more times), until a maximum temperature is reached between 110 ° C and 190 ° C;

 - cool all at a temperature below 100 ° C;

 - Then incorporate, in a second step (called "productive"), a crosslinking system;

- mix everything up to a maximum temperature below 1 10 ° C. - -

The lignin-based resin and the hardener may be incorporated either during the non-productive phase or during the productive phase. Preferably, the lignin-based resin is incorporated during the non-productive phase and the hardener during the productive phase.

For example, the nonproductive phase is conducted in a single thermomechanical step during which is introduced, in a suitable mixer such as a conventional internal mixer, in a first step all the basic constituents necessary (a diene elastomer, reinforcing filler and the like), then in a second step, for example after one to two minutes of mixing, the other additives, any optional load-collecting or processing agents, with the exception of crosslinking system. The total mixing time in this non-productive phase is preferably between 1 and 15 minutes. During this phase, may optionally be added the lignin-based resin and the hardener, or only the lignin. If lignin and hardener are not added during this phase, they should be added during the next phase below so that the lignin and hardener required for the purposes of the invention are present in the composition. completed.

 After cooling the mixture thus obtained, is then incorporated in an external mixer such as a cylinder mixer, maintained at low temperature (for example between 40 ° C and 100 ° C), the crosslinking system. The whole is then mixed (productive phase) for a few minutes, for example between 2 and 15 min. During this phase, the lignin and hardener may be added, or only the hardener if the lignin has been added during the non-productive phase.

 The final composition thus obtained can then be calendered, for example in the form of a sheet, a plate especially for a characterization in the laboratory, or extruded, for example to form a rubber profile used for manufacturing of a tire.

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

11 - Pneumatic of the invention

The rubber composition according to the invention can be used in different parts of the tire, particularly in the crown, the bead area, the - - sidewall area and the tread (especially in the underlayer of the tread).

 According to a preferred embodiment of the invention, the rubber composition described above can be used in the tire as a rigid elastomeric layer in at least a portion of the tire.

 By elastomer "layer" is meant any three-dimensional element, in rubber composition (or "elastomer", both being considered synonymous), of any shape and thickness, in particular sheet, strip, or other element of any straight section, for example rectangular or triangular.

First of all, the elastomer layer may be used as a tread sub-layer disposed in the crown of the tire, on the one hand between the tread, Le., The portion intended to come into contact with the tread. road during taxiing, and secondly the belt reinforcing said vertex. The thickness of this elastomeric layer is preferably in a range from 0.5 to 10 mm, especially in a range of 1 to 5 mm.

 According to another preferred embodiment of the invention, the rubber composition according to the invention may be used to form an elastomeric layer, disposed in the region of the region of the bead of the tire, radially between the carcass ply, the bead and the overturning of the carcass ply.

Another preferred embodiment of the invention may be the use of the composition according to the invention to form an elastomeric layer disposed in the area of the tire sidewall.

 Alternatively, the composition of the invention may advantageously be used in the tread of the tire.

III. EXAMPLES OF CARRYING OUT THE INVENTION

III.1. Preparation of epoxidized lignin B

The epoxidized lignin B was synthesized from kraft lignin: 10 g of kraft lignin ("lignin alkali" marketed by Aldrich) were suspended in 30 ml of DMSO. Thereafter, 40 g of epichlorohydrin, 30 g of sodium hydroxide and 0.3 g of antimony trifluoride are added. The mixture is stirred for 1 hour at 70 ° C. and then for 6 hours at 90 ° C. The epoxidized lignin is recovered by precipitation using a phosphate buffer solution of pH 7. It is - Washed with distilled water and dried under vacuum at room temperature (ie between 17 ° C and 25 ° C).

III.2. Preparation of compositions

The following tests are carried out as follows: one introduces into an internal mixer (final filling rate: approximately 70% by volume), the initial vessel temperature of which is approximately 60 ° C., in succession diene elastomer, reinforcing filler and lignin, as well as the various other ingredients with the exception of the vulcanization system and the hardener. Thermomechanical work (non-productive phase) is then carried out in one step, which lasts in total about 3 to 4 min, until a maximum temperature of "fall" of 180 ° C is reached.

 The mixture thus obtained is recovered, cooled and then sulfur is incorporated, a sulfenamide type accelerator and the hardener on a mixer (homo-finisher) at 30 ° C, mixing the whole (productive phase) for a period of time. appropriate (for example between 5 and 12 min).

 The compositions thus obtained are then calendered either in the form of plates (thickness of 2 to 3 mm) or thin sheets of rubber for the measurement of their physical or mechanical properties, or extruded in the form of a profile.

III.3. Testing of rubber compositions

 [00143] This test illustrates rubber compositions used in tire tread underlays. These compositions make it possible to increase the rigidity with respect to a conventional rubber composition (comprising a phenolic resin and HMT as a methylene donor), while maintaining a similar level of hysteresis.

 For this, three rubber compositions were prepared as indicated above, two of which according to the invention (noted below C.2 and C.3) and a non-compliant (control composition noted below C. 1) (see Table 1).

 The control composition C.1 is a conventional composition for those skilled in the art, used to manufacture mixtures for tread underlays of tires; it is based on natural rubber.

The compositions of the invention C.2 and C.3 contain a resin based on lignin and a polyamine hardener to replace the formo-phenolic resin couple / - - hardener (s) HMT contained in the conventional control composition C.1. The lignin used is different for each of the compositions according to the invention. Their formulations (in phr or parts by weight per hundred parts of elastomer), their mechanical properties have been summarized in Tables 1 and 2 below.

 Table 1

(1) Natural rubber;

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

 (3) novolac formophenolic resin ("Peracit 4536K" from Perstorp);

(4) Kraft lignin marketed by Aldrich under the name "lignin, alcaki, pH = 6.5";

(5) Epoxidized Kraft Lignin B;

 (6) Zinc oxide (industrial grade - Umicore company);

 (7) Stearin ("Pristerene 4931" from Uniqema);

 (8) N-1,3-dimethylbutyl-N-phenylparaphenylenediamine Santoflex 6-PPD from Flexsys;

 (9) Hexamethylenetetramine (from Degussa);

 (10) p-xylylenediamine (from Sigma-Aldrich);

(1 1) N-cyclohexyl-benzothiazyl sulphenamide (Santocure CBS from Flexsys). - -

Table 2

It is noted that the replacement of the formo-phenolic resin / hardener (s) HMT couple by a lignin resin and a hardener in the compositions of the invention C.2 to C.3 makes it possible to obtain a complex shear modulus dynamic G ^* (10%) at 40 ° C higher than that of the control composition C.1, representative of an increase in the low-deformation stiffness of the compositions according to the invention, while reconciling a stable value of the loss factor at 40 ° C (denoted tan (δ) max), that is to say a similar hysteresis and which remains acceptable, in particular in certain areas of the tire, particularly in the lower zone and in the underlayer.

 In summary, the results of these tests demonstrate that the use of a lignin resin and a hardener in the compositions of the invention makes it possible to obtain rubber compositions with a low deformation rigidity greater than that of a conventional composition (here control composition), synonymous with an improvement in road behavior, while maintaining an acceptable hysteresis, particularly in certain areas of the tire, particularly in the lower zone and in the underlayer.

Claims

claims

1. A rubber composition based on at least one diene elastomer, a reinforcing filler, a crosslinking system, a lignin-based resin and a hardener, it being understood that the hardener is chosen from polyamines, polyaldimines, polyketimines or mixtures thereof.

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

 3. A rubber composition according to any one of claims 1 to 2, wherein the lignin content is in a range from 1 to 35 phr.

 4. A rubber composition according to claim 3, wherein the level of lignin is 3 to 30 phr, preferably 5 to 25 phr.

 The rubber composition according to any one of claims 1 to 4, wherein the hardener is a polyamine.

 The rubber composition according to claim 5, wherein the hardener is a polyamine compound of the general formula (I):

 H H

Wherein A represents a hydrocarbon group having at least 2 carbon atoms (preferably 2 to 18), optionally interrupted by hetero atoms and optionally substituted.

 The rubber composition according to any one of claims 1 to 4, wherein the hardener is a polyaldimine.

The rubber composition according to claim 7, wherein the hardener is a poly-aldimine compound of the general formula (II):

in which : R 1, R 2, ₃ and R ₄ independently represent identical or different groups chosen from alkyl groups having from 1 to 20 carbon atoms, cycloalkyls having from 5 to 24 carbon atoms, aryls having from 6 to 30 carbon atoms; or aralkyls having 7 to 25 carbon atoms; groups which may possibly be interrupted by heteroatoms and / or substituted,

 A represents a hydrocarbon group comprising at least 2 carbon atoms (preferably from 2 to 18), optionally interrupted by hetero atoms and optionally substituted.

 The rubber composition according to any one of claims 1 to 4, wherein the hardener is a polyketimine.

 The rubber composition of claim 9, wherein the hardener is a polyketimine compound of the general formula (IV):

in which :

R 1, R ₂ , R ₃ and R ₄ independently represent identical or different groups chosen from alkyl groups having from 1 to 20 carbon atoms, cycloalkyls having from 5 to 24 carbon atoms, aryls having from 6 to 30 carbon atoms; or aralkyls having 7 to 25 carbon atoms; groups which may possibly be interrupted by heteroatoms and / or substituted,

A represents a hydrocarbon group comprising at least 2 carbon atoms (preferably from 2 to 18), optionally interrupted by hetero atoms and optionally substituted.

 1 1. A rubber composition according to any one of claims 1 to 10 wherein the level of hardener is within a range of 0.2 to 20 phr.

12. A rubber composition according to claim 11 wherein the level of hardener is 0.3 to 10 phr, preferably 0.5 to 8 phr.

 The rubber composition according to any one of claims 1 to 12, wherein the reinforcing filler comprises carbon black and / or silica.

14. A tire comprising a rubber composition according to any one of claims 1 to 13.

A finished or semi-finished rubber article comprising a rubber composition according to any one of claims 1 to 13.

 16. Process for preparing a rubber composition according to any one of claims 1 to 13, characterized in that it comprises the following steps:

to incorporate in a diene elastomer, during a first step (called "non-productive"), a reinforcing filler, a lignin-based resin and a hardener, by thermomechanically kneading the whole until a maximum temperature between 110 ° C and 190 ° C;

cool the assembly to a temperature below 100 ° C;

then incorporate, during a second step (called "productive"), a crosslinking system;

knead to a maximum temperature below 1 10 ° C.

 17. Process for preparing a rubber composition according to any one of claims 1 to 13, characterized in that it comprises the following steps:

incorporating into a diene elastomer, during a first step (called "non-productive"), a reinforcing filler, thermomechanically kneading the whole until a maximum temperature of between 1 10 ° C and 190 ° C;

cool the assembly to a temperature below 100 ° C;

then incorporate, during a second stage (so-called "productive"), a crosslinking system, a lignin-based resin and a hardener;

knead to a maximum temperature below 1 10 ° C.

 18. Process for preparing a rubber composition according to any one of claims 1 to 13, characterized in that it comprises the following steps:

to incorporate in a diene elastomer, during a first step (so-called "non-productive"), a reinforcing filler, a resin based on lignin, by thermomechanically kneading the whole until reaching a maximum temperature of between 1 10 ° C and 190 ° C;

cool the assembly to a temperature below 100 ° C;

then incorporate, during a second stage (called "productive"), a crosslinking system, a hardener;

knead to a maximum temperature below 1 10 ° C.