WO2018104662A1

WO2018104662A1 - Rubber composition comprising a diene elastomer, a polyacrylate derivative and a specific thermoplastic elastomer

Info

Publication number: WO2018104662A1
Application number: PCT/FR2017/053415
Authority: WO
Inventors: Didier Vasseur; Scott WOLFS
Original assignee: Compagnie Generale Des Etablissements Michelin
Priority date: 2016-12-07
Filing date: 2017-12-06
Publication date: 2018-06-14
Also published as: FR3059669A1

Abstract

The present invention relates to a high-modulus rubber composition based on at least one polymer matrix comprising: from 20 to 55 parts by weight per hundred parts by weight of polymer matrix, phm, of at least one diene elastomer; from 35 to 75 phm of a polyalkyl (meth)acrylate polymer having a Vicat softening point measured according to the standard ISO 306: 2013 B50 above 60°C; and from 5 to 35 phm of a thermoplastic elastomer comprising at least one elastomer block and one thermoplastic block, the thermoplastic block comprising a polyalkyl (meth)acrylate polymer.

Description

RUBBER COMPOSITION COMPRISING DIENIC ELASTOMER, POLYACRYLATE DERIVATIVE AND SPECIFIC THERMOPLASTIC ELASTOMER

The invention relates to compositions comprising a mixture of diene elastomer and a thermoplastic having a high rigidity.

The rigidity, in particular that of the crown portion of the tire, contributes to the drifting thrust of the tire. To obtain high rigidities, it has been proposed to introduce into the composition large amounts of filler. However this solution impacts the rolling resistance but also the endurance of the tire due to a strong heating. In addition, the solutions of the prior art do not allow, or difficult to achieve high levels of rigidity (Young's modulus at 23 ° C).

There is therefore a real need to further increase the rigidity of tire compositions, preferably without penalizing the other properties of the tire. The Applicant has found that the addition of a specific thermoplastic elastomer in a composition comprising a diene elastomer and a specific thermoplastic makes it possible to reach a high Young's modulus. These compositions advantageously have an excellent compromise between rigidity, hysteresis and elongation rupture. These compositions also have the advantage of being able to be manufactured by conventional mixing means such as a rotor mixer, without having to resort to processes that complicate the manufacturing process or that use high temperatures, particularly by extrusion, which can lead to degradation of the diene elastomer.

Thus, a first subject of the invention is a rubber composition based on a polymeric matrix comprising:

from 20 to 55 parts by weight per hundred parts by weight of polymeric matrix, pcm, of at least one diene elastomer,

from 35 to 75 μcm of a polyalkyl (meth) acrylate polymer having a Vicat softening point measured according to ISO 306: 2013 B50 greater than 60 ° C., and from 5 to 35 μcm of a thermoplastic elastomer comprising at least an elastomeric block and a thermoplastic block, the thermoplastic block comprising a polyalkyl (meth) acrylate polymer.

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

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

For the purposes of the present patent application, the term "pcm" means part by weight per hundred parts of polymeric matrix, any type of polymer combined, in particular thermoplastic elastomers and thermoplastic polymers combined.

By the expression "part by weight per hundred parts by weight of elastomer" (or phr), is meant for the purposes of the present invention, the part, by weight per hundred parts by weight of elastomer, thermoplastic and non-thermoplastic confused. For the purposes of the present invention, thermoplastic elastomers are part of the elastomers. In the present, unless expressly indicated otherwise, all the percentages (%) indicated are percentages (%) by mass.

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

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

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

By "polyalkyl (meth) acrylate polymer" is meant an alkyl methacrylate polymer (also called alkyl polymethacrylate) and / or an alkyl acrylate polymer (also known as alkyl polyacrylate).

Unless otherwise indicated, the glass transition temperature is measured by means of a differential scanning calorimeter according to ASTM D3418 (1999). In the context of the invention, the carbonaceous products mentioned in the description may be of fossil origin or biobased. In the latter case, they can be, partially or totally, derived from biomass or obtained from renewable raw materials derived from biomass. These include polymers, plasticizers, fillers, etc.

II-DETAILED DESCRIPTION OF THE INVENTION II-1 Polymeric Matrix

The polymeric matrix of the composition according to the invention comprises at least one diene elastomer, at least one polyalkyl (meth) acrylate having a Vicat softening point measured according to ISO 306: 2013 B50 greater than 60 ° C. and a thermoplastic elastomer comprising at least less an elastomeric block and a thermoplastic block, the thermoplastic block comprising a polyalkyl (meth) acrylate polymer.

The person skilled in the art understands that the total content of the at least one diene elastomer of the polyalkyl (meth) acrylate polymer having a Vicat softening point measured according to ISO 306: 2013 B50 greater than 60 ° C. and from thermoplastic elastomer comprising at least one elastomeric block and a thermoplastic block, the thermoplastic block comprising a polyalkyl (meth) acrylate polymer, in the composition according to the invention is 100 cfm.

The diene elastomer The polymeric matrix of the compositions according to the invention contains from 20 to 55 cc of at least one diene elastomer. It may contain a single diene elastomer or a mixture of several diene elastomers.

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

The diene elastomers can be classified into two categories: "essentially unsaturated" or "essentially saturated". The term "essentially unsaturated" is generally understood to mean a diene elastomer derived at least in part from conjugated diene monomers, having a proportion 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 be especially described as "substantially 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: a) any homopolymer obtained by polymerization of a conjugated diene monomer having from 4 to 12 carbon atoms;

b) any copolymer obtained by copolymerization of one or more conjugated dienes with each other or with one or more vinyl aromatic compounds having from 8 to 20 carbon atoms;

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

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

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

As conjugated dienes 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-di (C ₁ -C ₅ alkyl) -1,3-butadienes, such as, for example, 2,3-dimethyl-1,3-butadiene, 2,3-diethyl-1,3-butadiene, 2-methyl-3-ethyl-1,3-butadiene, 2-methyl-3-isopropyl-1 3-butadiene, aryl-1,3-butadiene, 1,3-pentadiene, 2,4-hexadiene. Suitable vinylaromatic compounds are, for example, styrene, ortho-, meta-, para-methylstyrene, the "vinyl-toluene" commercial mixture, para-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 the amounts of modifying and / or randomizing agent used. The elastomers may be, for example, random, sequenced or microsequential, and may be prepared in dispersion or in solution; they may be coupled and / or starred or functionalized with a coupling agent and / or starring or functionalization. For coupling with carbon black, there may be mentioned, for example, functional groups comprising a C-Sn bond or amine functional groups such as aminobenzophenone for example; for coupling to a reinforcing inorganic filler such as silica, there may be mentioned, for example, silanol or polysiloxane functional groups having a silanol end (as described, for example, in F 2 740 778, US Pat. No. 6,013,718 and WO 2008/141702), alkoxysilane groups (as described for example in FR 2,765,882 or US 5,977,238), carboxylic groups (as described for example in WO 01/92402 or US 6,815,473, WO 2004/096865 or US 2006/0089445) or else polyether groups (as described for example in EP 1 127 909, US 6,503,973, WO 2009/000750 and WO 2009/000752). As other examples of functionalized elastomers, mention may also be made of elastomers (such as SBR, BR, NR or IR) of the epoxidized type. These functionalized elastomers may be used in a blend with each other or with unfunctionalized elastomers. For example, a functionalized silanol or polysiloxane elastomer having a silanol end, in admixture with a coupled and / or stanned tin elastomer (described in WO 11/042507), may be used, the latter representing a rate of from 5 to 50 %, for example from 25 to 50%.

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%) of cis-1,4 greater than 80%, polyisoprenes, copolymers of butadiene-styrene and in particular those having a Tg (glass transition temperature (Tg, measured according to ASTM D3418) 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%) in -1,2 bonds of the butadiene part of between 4% and 75%, a content ( mol%) in 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 ° C. to 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 -5 ° C and -60 ° 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. isoprene content 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 (% molar) 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 isoprene part of between 5% and 70% and a content (mol%) in trans units of -1.4 of the isoprenic part of between 10% and 50%, and more generally any butadiene-styrene-isoprene copolymer having a Tg between -20 ° C and -70 ° C.

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

More preferably, the diene elastomer comprises predominantly at least one polyisoprene. In other words, the diene elastomer comprises more than 50% by weight of polyisoprene relative to the diene elastomer mass. Preferably, the diene elastomer comprises from 60 to 100%, preferably from 70 to 100%, or more, by weight of polyisoprene relative to the diene elastomer mass. By "polyisoprene" 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 (N) which can be plasticized or peptized, synthetic polyisoprenes (IR), the various isoprene copolymers and the mixtures of these elastomers. Among the isoprene copolymers, mention will in particular be made of copolymers of isobutene-isoprene (butyl rubber IIR), isoprene-styrene (SIR), isoprene-butadiene (BIR) or isoprene-butadiene-styrene ( SBIR).

The polyisoprene is preferably selected from the group consisting of natural rubber, synthetic polyisoprenes and mixtures thereof. Preferably, the polyisoprene has a mass ratio of cis 1,4 units of at least 90%, more preferably at least 98% relative to the weight of the polyisoprene.

More preferably, the polyisoprene is natural rubber, a synthetic polyisoprene or a mixture thereof. More preferably, the polyisoprene is natural rubber. Thus, according to the invention, the diene elastomer preferably comprises predominantly natural rubber. Preferably, the level of diene elastomer in the composition according to the invention is in a range from 22 to 50 mcms, more preferably from 23 to 40 mcms.

1-b Polyalkyl (meth) acrylate polymer

The rubber composition according to the invention is based on 35 to 75 sccm of at least one (that is to say one or more) polyalkyl (meth) acrylate polymer having a Vicat softening point measured according to the ISO standard. 306: 2013 B50 greater than 60 ° C.

The Applicant has found that below a Vicat softening point of 60 ° C measured according to ISO 306: 2013 B50, the polyalkyl (meth) acrylate polymer may no longer be sufficiently rigid. For these reasons, the polyalkyl (meth) acrylate polymer preferably has a Vicat softening point measured according to ISO 306: 2013 B50 in a range from 60 ° C to 110 ° C, preferably from 65 ° C to 105 ° C. ° C, preferably 70 to 100 ° C, more preferably 75 to 95 ° C.

The level of the polyalkyl (meth) acrylate polymer is preferably in a range from 45 to 70 phr, preferably from 50 to 65 cfm. The polyalkyl (meth) acrylate polymer may advantageously be a polymethylmethacrylate (also called polymethylmethacrylate or PMMA). This polymethylmethacrylate polymer is advantageously a polymer consisting of more than 80%, preferably more than 90%, more preferably more than 95%, for example 100% of methyl methacrylate monomer.

The polyalkyl (meth) acrylate polymer may be prepared in a manner known to those skilled in the art by radical polymerization of alkyl acrylate monomer (and / or methacrylate), and is also commercially available. For example, polymethyl methacrylate is available from Asahi Kasei under the trade name "Delpet SR 6500" with a Vicat softening point of 78 ° C. llc Thermoplastic elastomer

The rubber composition according to the invention is based on 5 to 35 sccm of at least one thermoplastic elastomer comprising at least one elastomer block and a thermoplastic block, the thermoplastic block comprising a polyalkyl (meth) acrylate polymer (denoted by "the thermoplastic elastomer "for reasons of simplification).

Preferably, the level of thermoplastic elastomer in the composition according to the invention is in a range from 5 to 30 cm 2, preferably from 6 to 20 cm 3, preferably from 7 to 15 cm 3, more preferably from 8 to 30 cm 3. 10 cfm.

Advantageously, the mass ratio of the thermoplastic elastomer to the sum of the diene elastomer and the polyalkyl (meth) acrylate polymer is in a range from 0.05 to 0.35; preferably from 0.05 to 0.25; more preferably 0.05 to 0.15.

The thermoplastic elastomer preferably has a weight average molecular weight (Mw) of 40,000 to 190,000 g / mol.

The elastomeric block of the thermoplastic elastomer is advantageously a diene elastomer as defined above. It is preferably a polybutadiene or a copolymer of styrene such as SB, for example. The elastomeric block preferably has a weight average molecular weight (Mw) of 5,000 to 65,000 g / mol.

The thermoplastic block is advantageously a polyalkyl (meth) polymer as defined above. Advantageously, the thermoplastic block is a polymer chosen from the group consisting of polymethylmethacrylates, polyethylmethacrylates, polypropylmethacrylates, polybutylmethacrylates, polyisobutylmethacrylates, polymethylacrylates, polyethylacrylates and mixtures of these polyalkyl (meth) acrylate derivatives. More preferably, the thermoplastic block is a polymethylmethacrylate. The thermoplastic block preferably has a weight average molecular weight (Mw) of 35,000 to 70,000 g / mol. The thermoplastic elastomer may, for example, have the following composition: the elastomer block represents from 33% to 75% of the mass of the thermoplastic elastomer, the thermoplastic block represents from 25% to 67% of the mass of the elastomer thermoplastic.

The thermoplastic block of the thermoplastic elastomer may also comprise a polymer other than the polyalkyl (meth) acrylate polymer of the thermoplastic block of the thermoplastic elastomer.

Advantageously, the thermoplastic elastomer may have the following composition: the elastomer block represents from 20% to 60% of the mass of the thermoplastic elastomer, the polyalkyl (meth) acrylate polymer represents from 21% to 42% of the mass thermoplastic elastomer, the polymer other than the polyalkyl (meth) acrylate polymer of the thermoplastic block of the thermoplastic elastomer represents from 13% to 52% of the mass of the thermoplastic elastomer.

Advantageously, the polymer other than the polyalkyl (meth) acrylate polymer of the thermoplastic block of the thermoplastic elastomer is a polymer of a vinylaromatic compound. This polymer of a vinylaromatic compound may be, for example, either a homopolymer obtained by polymerization of at least one vinylaromatic monomer, or a copolymer obtained by copolymerization of one or more of these vinylaromatic monomers with one another or with one or more other monomers. As vinylaromatic monomers are especially suitable styrene, ortho-, meta, para-methylstyrene, the commercial mixture "vinyltoluene", para-tertiarybutylstyrene, methoxystyrenes, vinylmesitylene, divinylbenzene, vinylnaphthalene, etc. Preferably the monomer is styrene. Thus, according to a preferred aspect of the invention, the other thermoplastic block is a polystyrene. The other thermoplastic block preferably has a weight average molecular weight (Mw) of 14,000 to 55,000 g / mol. Advantageously, when the thermoplastic elastomer is a triblock, it is a polystyrene / polybutadiene / polyethylmethacrylate copolymer or a polystyrene / polybutadiene / polymethylmethacrylate copolymer. It can also be a mixture of these copolymers. More preferably, the thermoplastic elastomer is a polystyrene / polybutadiene / polymethyl methacrylate copolymer. Such products are commercially available. These include for example the product sold under the name Nanostrengh ^® by Arkema with different grades referenced A012, GVlOO or E21.

Reinforcing Charge The composition of the tire according to the invention may advantageously comprise a reinforcing filler known for its ability to reinforce a rubber composition that can be used for the manufacture of tires.

The reinforcing filler may comprise carbon black, an organic filler other than carbon black, an inorganic filler or a mixture of at least two of these filler. Preferably, the reinforcing filler comprises a carbon black, a reinforcing inorganic filler (preferably silica) or a mixture thereof. More preferably still, the reinforcing filler predominantly comprises carbon black, more preferably it mainly comprises carbon black and, in the minor case, an inorganic filler (preferably silica). Particularly advantageously, the reinforcing filler comprises from 50 to 100% by weight of carbon black, preferably from 55 to 90% by weight, preferably from 60 to 80% by weight.

Such a reinforcing filler typically consists of particles whose average size (in mass) is less than one micrometer, generally less than 500 nm, most often between 20 and 200 nm, in particular and more preferably between 20 and 150 nm. According to the invention, the level of reinforcing filler, preferably the reinforcing filler predominantly comprising carbon black, can be in a range from 0 to 140 mcms, preferably from 5 to 60 mcms, preferably from 10 to 30 moles. cfm.

Advantageously, the weight ratio of the reinforcing filler to the sum of the diene elastomer and the polyalkyl (meth) acrylate polymer is in a range from 0.05 to 0.40; preferably from 0.10 to 0.30; preferably from 0.10 to 0.20.

The blacks that can be used in the context of the present invention may be all black conventionally used in tires or their treads (so-called pneumatic grade blacks). Among these, the reinforcing carbon blacks of the 100, 200, 300 series, or the 500, 600 or 700 series blacks (ASTM grades), for example the blacks NI 15, N134, N234, N326, are especially suitable. N330, N339, N347, N375, N550, N683, N772). These carbon blacks can be used in the isolated state, as commercially available, or in any other form, for example as a carrier for some of the rubber additives used. The carbon blacks could for example already be incorporated into the diene elastomer, in particular isoprene in the form of a masterbatch (see for example applications WO 97/36724 or WO 99/16600). The BET surface area of the carbon blacks is measured according to the D6556-10 standard [multipoint method (at least 5 points) - gas: nitrogen - relative pressure range Ρ / Ρ0: 0.1 to 0.3].

As examples of organic fillers other than carbon blacks, mention may be made of functionalized polyvinyl organic fillers as described in applications WO 2006/069792, WO 2006/069793, WO 2008/003434 and WO 2008/003435.

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

Suitable reinforcing inorganic fillers are in particular mineral fillers of the siliceous type, preferentially silica (SiO ₂ ). The silica used may be any reinforcing silica known to those skilled in the art, in particular any precipitated or fumed silica having a BET surface and a CTAB specific surface both less than 450 m ² / g, preferably from 30 to 400 m ² / g, in particular between 60 and 300 m ² / g-A of highly dispersible precipitated silicas (called "HDS"), there may be mentioned for example the silicas "Ultrasil" 7000 and "Ultrasil" 7005 from the company Degussa, silicas "Zeosil" 1165MP, 1135MP and 1115MP from the company hodia, the silica "Hi-Sil" EZ150G from the company PPG, the "Zeopol" silicas 8715, 8745 and 8755 from the company Huber, the silicas with high specific surface area as described in WO 03/016387. In the present description, with regard to silica, the BET surface area is determined in a known manner by gas adsorption using the method of Brunauer-Emmett-Teller described in "The Journal of the American Chemical Society" Flight . 60, page 309, February 1938, specifically according to the French standard NF ISO 9277 of December 1996 (multipoint volumetric method (5 points) - gas: nitrogen - degassing: time at 160 ° C - relative pressure range p / po: 0.05 at 0.17). The CTAB specific surface is the external surface determined according to the French standard NF T 45-007 of November 1987 (method B).

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

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

Those skilled in the art will understand that, as the equivalent filler of the reinforcing inorganic filler described in this paragraph, it would be possible to use a reinforcing filler of another nature, in particular an organic filler, since this reinforcing filler would be covered with a filler. inorganic layer such as silica, or would comprise on its surface functional sites, especially hydroxyl, requiring the use of a coupling agent to establish the bond between the filler and the elastomer.

In order to couple the reinforcing inorganic filler to the diene elastomer, an at least bifunctional coupling agent (or bonding agent) is used in a well-known manner to ensure a sufficient chemical and / or physical connection between the inorganic filler (surface of its particles) and the diene elastomer. In particular, organosilanes or at least bifunctional polyorganosiloxanes are used.

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

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

The rubber composition in accordance with the invention may also contain, in addition to the coupling agents, coupling activators, inorganic charge-covering agents or, more generally, processing aid agents which can be used in a known manner, thanks to an improvement of the dispersion of the load in the rubber matrix and to 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 (especially alkyltriethoxysilanes), polyols, polyethers (for example polyethylene glycols), primary, secondary or tertiary amines (for example trialkanolamines), hydroxylated or hydrolysable POSs, for example α, ω-dihydroxy-polyorganosiloxanes (in particular α, ω-dihydroxy-polydimethylsiloxanes), fatty acids as for example stearic acid.

11-3 Miscellaneous additives The rubber compositions in accordance with the invention may also comprise all or part of the usual additives normally used in tire elastomer compositions, for example pigments, protective agents such as antiozone waxes, chemical ozonants, anti-oxidants, plasticizers, anti-fatigue agents, reinforcing resins, a crosslinking system based on either sulfur, or sulfur and / or peroxide and / or bismaleimide donors, accelerators, vulcanization, vulcanization activators.

The rubber composition according to the invention may advantageously be devoid of plasticizer or contain less than 5 phr, preferably less than 2 phr, more preferably less than 1 phr. This plasticizer may be a solid hydrocarbon resin (or plasticizing resin), an extender oil (or plasticizing oil), or a mixture of both.

Preferably, the extender oil (of which the composition according to the invention is devoid or contains less than 5 phr, preferably less than 2 phr, more preferably less than 1 phr) is chosen from the group consisting of naphthenic oils (low or high viscosity, especially hydrogenated), paraffinic oils, MES (Medium Extracted Solvates) oils, Treated Distillate Aromatic Extracts (TDAE) oils, mineral oils, vegetable oils, ethers plasticizers, ester plasticizers, phosphate plasticizers, sulphonate plasticizers and mixtures of these compounds.

Preferably, the thermoplastic hydrocarbon resin (of which the composition according to the invention is free or contains less than 5 phr, preferably less than 2 phr, more preferably less than 1 phr) is chosen from the group consisting of naphthenic oils. (Low or high viscosity, especially hydrogenated or not) is selected from the group consisting of aliphatic resins, or aromatic or aliphatic / aromatic type that is to say based on aliphatic and / or aromatic monomers. These resins can be natural or synthetic, whether based on petroleum or not (if so, also known as petroleum resins). The rubber composition according to the invention may also be devoid of a crosslinking system or contain less than 0.5 phr, preferably less than 0.3 phr, more preferably less than 0.1 phr. The crosslinking system may be a molecular sulfur crosslinking system (or equivalently the molecular sulfur donor agents). 11-4 Tires

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

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

It is possible to define three types of zones within the tire: · The radially outer zone and in contact with the ambient air, this zone consisting essentially of the tread and the external sidewall of the tire. An outer flank is an elastomeric layer disposed outside the carcass reinforcement with respect to the internal cavity of the tire, between the crown and the bead so as to completely or partially cover the region of the carcass reinforcement. extending from the top to the bead.

• The radially inner zone and in contact with the inflation gas, this zone being generally constituted by the inflation-gas-tight layer, sometimes called inner waterproof layer or inner liner.

• The inner area of the tire, that is to say the area between the outer and inner zones. This zone includes layers or plies which are here called internal layers of the tire. These are, for example, carcass plies, tread sub-layers, tire belt plies or any other layer that is not in contact with the ambient air or the inflation gas of the tire.

The composition defined in the present description is particularly well suited to the inner layers.

Also, in the tire according to the present invention the composition according to the invention may be present in at least one layer chosen from an inner layer. According to the invention, the inner layer may be chosen from the group consisting of carcass plies, crown plies, bead-knuckles, toe feet, decoupling layers, edge gums, underlayer rolling and combinations of these inner layers. Preferably, the inner layer is selected from the group consisting of carcass plies, crown plies, bead fences, toe feet, decoupling layers and combinations of these inner layers.

The invention relates to tires and semi-finished products for tires previously described, rubber articles, both in the raw state (that is to say, before cooking) and in the cooked state (that is to say, before cooking). after crosslinking or vulcanization). 11-5 Preparation of rubber compositions

The compositions used in the treads of the invention may be manufactured in appropriate mixers, using two successive preparation phases well known to those skilled in the art: a high temperature thermomechanical working or kneading phase, up to at a maximum temperature of between 110 ° C and 190 ° C, preferably between 130 ° C and 180 ° C.

The process for preparing such compositions comprises, for example, a stage of incorporation into a diene elastomer, during a first stage (called "non-productive" stage), at least one reinforcing filler, a polyalkyl (meth) acrylate conforming polymer. to the present invention and a thermoplastic elastomer according to the present invention, thermomechanically kneading the whole (for example in one or more times), until a maximum temperature of between 110 ° C and 190 ° C. is reached.

The first kneading step is generally carried out by incorporating the reinforcing filler to the elastomer in one or more times by thermomechanically kneading. In the case where the reinforcing filler, in particular carbon black, is already incorporated wholly or partly into the elastomer in the form of a masterbatch as described for example in the applications WO 97/36724 or WO 99 / 16600, the masterbatch is directly kneaded and if necessary is incorporated other elastomers or reinforcing fillers present in the composition that are not in the form of masterbatch, as well as additives other than the crosslinking system.

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 the manufacture of a pneumatic.

III- EXAMPLES

lll-l Measurements and tests used Young's modulus at 23 ° C

This is the Young's module (as a reminder, initial module in extension) often noted E as measured according to a method well known to those skilled in the art. Force-elongation curves, measured for example according to ASTM D638-02 for strips of thickness greater than 1 mm, or according to ASTM D882-09 for thin layers whose thickness is at most equal to 1 mm; for example at 5 mm / min with an "Instron-Strain Gauge Extensometer" extensometer at a temperature of 23 ° C., it is possible to deduce the E modulus values, expressed in MPa, and calculated with respect to the initial section of the test specimen tractionnée.

Unless otherwise indicated, the results are expressed in base 100 relative to the control: a value greater than 100 indicates an increase in the Young's modulus at 23 ° C. and consequently that the composition concerned is more rigid. 111-2 Preparation of compositions

The following tests are carried out as follows: an internal mixer (final filling ratio: approximately 70% by volume) is introduced, the initial temperature of which is approximately 60 ° C., the elastomer diene, and the thermoplastic elastomer, as well as the various other ingredients. The mixture is mixed by increasing the temperature to a temperature corresponding to the Vicat point of the polyalkyl (meth) acrylate, and then introducing the polyalkyl (meth) acrylate polymer. One thermomechanical work is then carried out in one step, which lasts in total about 5 to 6 min, until a maximum temperature of "fall" of 165 ° C is reached.

The resulting mixture is recovered and shaped to cool.

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.

11-3 Testing of rubber compositions

The examples presented in Tables 1 to 5 are intended to compare Young's moduli 23 ° C of control compositions (T1 to T9) with compositions C1 to C9 according to the invention.

Table 1

(1) Natural rubber

(2) PMMA grafted natural rubber with 30% PMMA "Megapoly 30" from the company Green HPSP

(3) Styrene-Butadiene-Methylmethacrylate Copolymer (SBM) sold under the name Nanostrengh E21 by the company Arkema

(4) Polymethyl methacrylate "Delpet SR 6500" from Asahi Kasei Point Vicat Pv = 78 ° C. Table 2

(l) to (4) See Table 1

(5) Polymethyl methacrylate "Delpet SR6200" from Asahi Kasei Point Vicat Pv = 94 ° C

Table 3

(1) to (5) See Table 2

(6) ASTM grade N234 (Cabot company)

The results presented in Tables 1 to 3 show that a thermoplastic elastomer comprising at least one elastomer block and a thermoplastic block, the thermoplastic block comprising a polyalkyl (meth) acrylate (SBM) polymer is more effective than a diene elastomer grafted with a polyalkyl (meth) acrylate polymer (PMMA-grafted NR) for increasing the modulus of a composition comprising a diene elastomer and a polyalkyl (meth) acrylate polymer, whatever the levels of diene elastomer and of polyalkyl (meth) acrylate polymer; . Table 4

(l) to (6) See Table 3

These results show that the addition of a reinforcing filler, such as a carbon black, is compatible with the formulations according to the present invention. The addition of reinforcing filler makes it possible to further increase the modulus of the compositions in accordance with the invention. This improved effect was, however, not observed for the control compositions comprising a diene elastomer grafted with a polyalkyl (meth) acrylate polymer instead of the thermoplastic elastomer (SBM).

Table 5

(l) to (6) See Table 3

These results confirm those presented in Tables 1 to 4 above at different levels of diene elastomer, polyalkyl (meth) acrylate and thermoplastic elastomer comprising at least one elastomer block and a thermoplastic block, the thermoplastic block comprising a polymer polyalkyl (meth) acrylate. Furthermore, it has been found that it is not necessary to introduce a high level of thermoplastic elastomer comprising at least one elastomer block and a thermoplastic block, the thermoplastic block comprising a polyalkyl (meth) acrylate polymer to increase the module of the compositions.

Thus, the compositions according to the present invention make it possible to increase the levels of Young's modulus, and this without necessarily having to use a high level of thermoplastic rigid phase. This is an advantage to maintain a good level of adhesion of the composition on the other tire positions thanks to the high rate of diene elastomer. This also advantageously makes it possible to manufacture the compositions according to the invention by conventional mixing means (rotor mixture for example), without having to resort to high temperature extrusion which will have the disadvantage of being liable to degrade. the diene elastomer.

Claims

A rubber composition based on a polymeric matrix comprising:

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

3. A rubber composition according to claim 1 or 2, wherein the diene elastomer comprises predominantly natural rubber.

The rubber composition according to any one of claims 1 to 3, wherein the level of the at least one diene elastomer is within a range of 22 to 50, preferably 23 to 40,.

The rubber composition according to any one of claims 1 to 4, wherein the level of the polyalkyl (meth) acrylate polymer is within a range of from 45 to 70 mcf, preferably from 50 to 65 mcf.

The rubber composition according to any one of claims 1 to 5, wherein the polyalkyl (meth) acrylate polymer has a Vicat softening point measured according to ISO 306: 2013 B50 in a range from 60 ° C to 110 ° C, preferably 65 ° C to 105 ° C.

The rubber composition according to any one of claims 1 to 6, wherein the polyalkyl (meth) acrylate polymer is a polymethylmethacrylate.

The rubber composition according to any one of claims 1 to 7, wherein the mass ratio of the thermoplastic elastomer to the sum of the diene elastomer and the polyalkyl (meth) acrylate polymer is in a range from from 0.05 to 0.35; preferably from 0.05 to 0.25.

The rubber composition according to any of claims 1 to 8, wherein the level of the thermoplastic elastomer comprising at least one elastomeric block and a thermoplastic block is within a range of from 5 to 30, preferably 6 to 20 cm.

The rubber composition according to any one of claims 1 to 9, wherein the elastomeric block is a butadiene or a butadiene-styrene copolymer.

11. A rubber composition according to any one of claims 1 to 10, wherein the thermoplastic block is selected from the group consisting of polymethyl methacrylates, polyethyl methacrylates, polypropyl methacrylates, polybutyl methacrylates, polyisobutyl methacrylates, polymethyl acrylates, polyethyl acrylates and the like. mixtures of these polyalkyl (meth) acrylates.

The rubber composition according to any one of claims 1 to 11, wherein the thermoplastic elastomer has the following composition:

the elastomer block represents from 33% to 75% of the mass of the thermoplastic elastomer,

the thermoplastic block represents from 25% to 67% of the mass of the thermoplastic elastomer.

A rubber composition according to any one of claims 1 to 12, wherein the thermoplastic block of the thermoplastic elastomer also comprises a polymer other than the polyalkyl (meth) acrylate polymer of the thermoplastic block of the thermoplastic elastomer.

The rubber composition of claim 13, wherein the thermoplastic elastomer has the following composition:

the elastomer block represents from 20% to 60% of the mass of the thermoplastic elastomer,

the polyalkyl (meth) acrylate polymer represents from 21% to 42% of the mass of the thermoplastic elastomer,

the polymer other than the polyalkyl (meth) acrylate polymer of the thermoplastic block of the thermoplastic elastomer represents from 13% to 52% of the mass of the thermoplastic elastomer.

The rubber composition according to claim 13 or 14, wherein the polymer different from the polyalkyl (meth) acrylate polymer of the thermoplastic block of the thermoplastic elastomer is a polymer of a vinylaromatic compound.

The rubber composition according to claim 12 to 15, wherein the thermoplastic elastomer is a polystyrene / polybutadiene / polyethylmethacrylate copolymer or a polystyrene / polybutadiene / polymethyl methacrylate copolymer.

The rubber composition according to any one of claims 1 to 16, further comprising from 0 to 140 pcm of reinforcing filler, preferably from 5 to 60 pcm.

18. A rubber composition according to any one of claims 1 to 17, wherein the mass ratio of the reinforcing filler to the sum of the diene elastomer and the polyalkyl (meth) acrylate polymer is in a range from 0, 05 to 0.40; preferably from 0.10 to 0.30.

The rubber composition according to any one of claims 1 to 18, wherein the reinforcing filler is carbon black, silica or a mixture thereof.

20. A rubber composition according to any one of claims 1 to 19, wherein the reinforcing filler comprises predominantly carbon black.

21. Finished or semi-finished rubber article comprising a rubber composition according to any one of claims 1 to 20.

22. A tire comprising a rubber composition according to any one of claims 1 to 20.

The tire of claim 22, wherein the rubber composition according to any one of claims 1 to 20 is present in at least one inner layer.

24. A tire according to claim 23, wherein the inner layer is selected from the group consisting of carcass plies, crown plies, toe feet, decoupling layers, edge rubbers, tread underlayer. and the combinations of these inner layers.