Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K5/00—Heat-transfer, heat-exchange or heat-storage materials, e.g. refrigerants; Materials for the production of heat or cold by chemical reactions other than by combustion
  • C09K5/08—Materials not undergoing a change of physical state when used
  • C09K5/14—Solid materials, e.g. powdery or granular
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
  • B29C43/22—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of indefinite length
  • B29C43/24—Calendering
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/01—Use of inorganic substances as compounding ingredients characterized by their specific function
  • C08K3/013—Fillers, pigments or reinforcing additives
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/02—Elements
  • C08K3/04—Carbon
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2009/00—Use of rubber derived from conjugated dienes, as moulding material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2507/00—Use of elements other than metals as filler
  • B29K2507/04—Carbon
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
  • B29L2007/00—Flat articles, e.g. films or sheets
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C1/00—Tyres characterised by the chemical composition or the physical arrangement or mixture of the composition
  • B60C1/0016—Compositions of the tread
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/34—Silicon-containing compounds
  • C08K3/36—Silica
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/01—Hydrocarbons

Definitions

• the invention relates to a tire rubber composition based on at least one diene elastomer, a filler comprising carbon black and an inorganic filler and a crosslinking system, having an improved thermal conductivity.
• the publication EP 1 767 570 proposes various "more conventional" carbon blacks, carbon blacks derived from acetylene and silica in treads associated with high levels of plasticizers (of the order 100 parts per hundred parts by weight of elastomer, phr).
• the subject of the invention is therefore a rubber composition based on at least one diene elastomer, a filler comprising carbon black and an inorganic filler, and a crosslinking system, characterized in that the inorganic filler content is greater than or equal to 5 parts by weight per hundred parts by weight of elastomer, pce, and - - represents at most 50% by mass fraction of the total charge of the composition, and that the carbon black comprises at least one carbon black derived from acetylene, with a level greater than 3 phr, the amount of black of carbon derived from acetylene representing more than 50%) of the carbon black present in the composition by mass fraction, and in that the composition comprises a plasticizing and / or plasticizing oil with a total content of plasticizing oil and resin plasticizer less than 30 phr.
• the amount of carbon black derived from acetylene accounts for more than 50% of the total charge present in the mass fraction composition.
• the inorganic filler content represents more than 30% by mass fraction of the total charge of the composition, and even more preferentially more than 40% by mass fraction of the total charge of the composition. the composition.
• the inorganic filler e composition comprises silica, and even more preferably a precipitation silica.
• the diene elastomer of the composition is chosen from the group consisting of polybutadienes, synthetic polyisoprenes, natural rubber, butadiene copolymers, isoprene copolymers and blends. of these elastomers.
• the invention also relates to a finished or semi-finished article, a tread, a tire and a semi-finished product comprising a composition as described above.
• the invention also relates to a process for preparing a rubber composition based on at least one diene elastomer, a filler comprising carbon black and an inorganic filler, and a crosslinking system, in which the inorganic filler content is greater than or equal to 5 parts by weight per hundred parts by weight of elastomer, phr, and represents at most 50% by mass fraction of the total charge of the composition, and wherein the carbon black comprises at least one carbon black derived from acetylene, with a level greater than 3 phr, the amount of carbon black derived from acetylene representing more than 50%> of the carbon black present in the composition by mass fraction, and wherein the composition comprises a plasticizer and / or plasticizing resin with a total content of plasticizing oil and plasticizing resin of less than 30 phr, and which comprises the following steps:
• the rubber compositions are characterized, before and after firing, as indicated below.
• the Mooney plasticity measurement is carried out according to the following principle: the raw composition (i.e., before firing) is molded in a cylindrical chamber heated to 100 ° C. After one minute of preheating, the rotor rotates within the test tube at 2 revolutions / minute and the useful torque is measured to maintain this movement after 4 minutes of rotation.
• the indices of tearability are measured at 100 ° C.
• the force to be exerted to obtain the fracture (FRD, in Mpa) is determined and the breaking strain (DRD, in%) is measured on a specimen of dimensions 10 ⁇ 10 5 ⁇ 2.5 mm notched at the center of its length on a depth of 5 mm, to cause the rupture of the specimen.
• the Energy can be determined to cause the rupture (Rupture Energy) of the specimen which is the product of the FRD and DRD.
• tan ( ⁇ ) max The dynamic properties tan ( ⁇ ) max is measured on a viscoanalyzer (Metravib VA4000) according to ASTM D 5992-96.
• 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, in the examples the measurements are carried out at 60 ° C.
• a strain amplitude sweep of 0.1% to 45%> (forward cycle) followed by 45%> to 0.1% (return cycle) is performed.
• the result exploited is the loss factor tan (ô).
• tan ( ⁇ ) max the maximum value of tan ( ⁇ ) observed, denoted tan ( ⁇ ) max , - -
• the thermal conductivity is measured at 25 ° C by the guarded hot plate (PCG) method. Measurement protocol:
• the samples are in the form of a 15mm cube with a thickness of about 2.5mm.
• the exchangers are at 20 and 30 ° C for a measurement at 25 ° C.
• the heat flux density in the sample is given by:
• 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). Diene elastomer
• elastomer or “diene” rubber should be understood in known manner an elastomer derived at least in part (i.e., a homopolymer or a copolymer) of monomers dienes (monomers bearing two carbon-carbon double bonds, conjugated or not).
• 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%). ;
• diene elastomers such as butyl rubbers or copolymers of dienes and alpha-olefins of the EPDM type do not fall within the above definition and may in particular be described as "substantially saturated” diene elastomers ( low or very low diene origin, always less than 15%>).
• 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%.
• iene elastomer can be understood more particularly to be used in the compositions according to the invention:
• diene elastomer 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.
• 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.
• 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-hexa
• Suitable vinylaromatic compounds are, for example, styrene, ortho-, meta-, para-methylstyrene, the "vinyl-toluene" commercial mixture, para-tert-butylstyrene, methoxystyrenes, chlorostyrenes, vinylmesitylene, divinylbenzene, viny lnaphthalene.
• the copolymers may contain between 99% and 20% by weight of diene units and between 1% and 80% by weight of vinylaromatic units.
• the elastomers may have any microstructure which is a function of the polymerization conditions used, in particular the presence or absence of a modifying and / or randomizing agent and the amounts of modifying and / or randomizing agent used.
• the elastomers can be for example block, statistical, sequenced, microsequenced, and be prepared in dispersion or in solution; they may be coupled and / or starred or functionalized with a coupling agent and / or starring or functionalization.
• 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 polyether groups (as described for example in EP 1 127 909 or US 6,503,973, WO 2009/000750 and WO 2009/000752).
• elastomers such as SBR, BR, NR or IR of the epoxidized type.
• 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 of greater than 80%, are suitable.
• Tg glass transition temperature
• butadiene-styrene-isoprene copolymers are especially suitable those having a styrene content of between 5% and 50% by weight and more particularly 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 of between 5% and 70% and a content (mol%) in trans units -1,4 of the isoprene part of between 10% and 50%, and more generally any butadiene copolymer isyrene-isoprene having a Tg between -5 ° C and -70 ° C
• the diene elastomer (s) of the composition according to the invention are preferably chosen from the group of highly unsaturated diene elastomers consisting of polybutadienes (abbreviated as "BR"), synthetic polyisoprenes (IR) and natural rubber (NR), butadiene copolymers, isoprene copolymers and mixtures of these elastomers.
• BR polybutadienes
• IR synthetic polyisoprenes
• NR natural rubber
• butadiene 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.
• SBIR butadiene-styrene
• the diene elastomer is predominantly (ie, for more than 50 phr) an SBR, whether it is an emulsion-prepared SBR ("ESBR") or an SBR prepared in solution (“SSBR”), or a blend (mixture) SBR / BR, SBR / NR (or SBR / IR), BR / NR (or BR / IR), or SBR / BR / NR (or SBR / BR / IR).
• SBR emulsion-prepared SBR
• SSBR SBR prepared in solution
• an SBR elastomer 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% by weight, is used in particular. at 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.
• the diene elastomer is predominantly (for more than 50 phr) an isoprene elastomer.
• the compositions of the invention are intended to constitute, in tires, the rubber matrices of certain treads (for example for industrial vehicles), . . crown reinforcement plies (for example working plies, protective plies or hooping plies), carcass reinforcement plies, sidewalls, beads, protectors, underlayments, rubber blocks and other internal rubbers providing the interface between the aforementioned zones of the tires.
• isoprene elastomer in known manner a homopolymer or copolymer of isoprene, in other words a diene elastomer chosen from the group consisting of natural rubber (NR), synthetic polyisoprenes (IR), different isoprene copolymers and mixtures of these elastomers.
• NR natural rubber
• IR synthetic polyisoprenes
• 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).
• This isoprene elastomer is preferably natural rubber or synthetic cis-1,4 polyisoprene; of these synthetic polyisoprenes, polyisoprenes having a content (mol%) of cis-1,4 bonds greater than 90%, more preferably still greater than 98%, are preferably used.
• the composition according to the invention may contain less than an essentially saturated diene elastomer, in particular at least one EPDM copolymer or a butyl rubber (optionally chlorinated or brominated), that these copolymers are used alone or in admixture with highly unsaturated diene elastomers as mentioned above, in particular NR or IR, BR or SBR.
• the rubber composition comprises a blend of one (or more) diene elastomers called "high Tg” having a Tg between -70 ° C and 0 ° C and d one (or more) diene elastomers known as "low Tg” between -110 ° 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 (mol%) content of cis-1,4 linkages of preferably greater than 95%>), BIR, SIR, SBIR, 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%.
• 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. - -
• the diene elastomer of the composition according to the invention comprises a blend of a BR (as low elastomer Tg) having a rate (mol%) of cis chains -1.4 greater than 90%, with one or more S-SBR or E-SBR (as elastomer (s) high Tg).
• composition according to the invention may contain a single diene elastomer or a mixture of several diene elastomers, the diene elastomer or elastomers which may be used in combination with any type of synthetic elastomer other than diene, or even with polymers other than elastomers, for example thermoplastic polymers.
• compositions according to the invention comprise, as a reinforcing filler known for its ability to reinforce a rubber composition that can be used for the manufacture of tires, at least carbon black and an inorganic filler, the carbon black comprises at least one carbon black derived from acetylene.
• a reinforcing filler known for its ability to reinforce a rubber composition that can be used for manufacturing tires
• an organic filler such as carbon black
• a reinforcing inorganic filler such as silica
• a blend of these two types of filler including a cut of carbon black and silica.
• carbon blacks apart from carbon blacks derived from acetylene all carbon blacks, especially blacks of the HAF, ISAF, SAF type conventionally used in tires (so-called pneumatic grade blacks) are suitable.
• the reinforcing carbon blacks of the 100, 200 or 300 series for example blacks NI 15, N134, N234, N326, N330, N339, N347, N375, or else, according to the targeted applications, the blacks of higher series (for example N400, N660, N683, N772).
• the carbon blacks could for example already be incorporated into the isoprene elastomer in the form of a masterbatch (see for example WO 97/36724 or WO 99/16600).
• Acetylene-derived carbon blacks are carbon blacks made from acetylene as a starting material.
• the acetylene blacks used may consist of any acetylene black known to those skilled in the art, in particular acetylene blacks having a BET surface area and a CTAB surface area greater than 40 m 2 / g, as well as a structure COAN greater than 80 ml / 100g.
• acetylene carbon blacks marketed by Chevron Chemical Company
• carbon blacks derived from acetylene marketed by the company Denki Kagaku Kogyo such as the "Denka Black”
• carbon blacks derived from acetylene marketed by SN2A such as "Y70”.
• compositions according to the invention may also contain organic fillers other than carbon blacks.
• organic fillers other than carbon blacks.
• inorganic filler is to be understood in the present application, by definition, any inorganic or mineral filler (regardless of its color and origin (natural or synthetic), also called “white” charge, “clear” charge or “ non-black “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 for the manufacture of tires, in particular Other terms capable of replacing, in its reinforcing function, a conventional carbon black of pneumatic grade
• Such a filler is generally characterized, in known manner, by the presence of functional groups, in particular hydroxyl (-OH) on its surface, requiring for use as a reinforcing filler the use of an agent or coupling system for providing a stable chemical bond between the isoprene elastomer and said filler.
• Such an inorganic filler can thus be used with a coupling agent to enable the strengthening of the rubber composition in which it is included. It can also be used with a coating agent (which does not provide a bond between the filler and the elastomeric matrix) in addition to a coupling agent or not (in this case the inorganic filler does not play a reinforcing role ).
• inorganic filler presents itself is indifferent, whether in the form of powder, microbeads, granules, beads or any other suitable densified form.
• inorganic filler is also understood to mean mixtures of different inorganic fillers, in particular highly dispersible siliceous and / or aluminous fillers as described below.
• Suitable inorganic fillers include mineral fillers of the siliceous type, in particular of silica (SiO 2), or of the aluminous type, in particular alumina (Al 2 O 3).
• the silica used may be any silica known to those skilled in the art, especially 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.
• HDS highly dispersible precipitated silicas
• the 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.
• inorganic fillers whose average size (in mass) is between 20 and 300 nm, more preferably between 20 and 150 nm, are particularly suitable for the present invention.
• This average size is measured conventionally after dispersion, by deagglomeration with ultrasound, of the load to be analyzed in water or an aqueous solution containing a surfactant.
• an inorganic filler such as silica
• the measurement is carried out using an XDC X-ray centrifugal sedimentometer ("X-rays Disk Centrifuge"), marketed by Brookhaven Instruments, according to the following procedure. .
• an at least bifunctional coupling agent is used in known manner to ensure a sufficient chemical and / or physical connection between the inorganic filler ( surface of its particles) and the diene elastomer, in particular organosilanes or bifunctional polyorganosiloxanes.
• polysulfide silanes called “symmetrical” or “asymmetrical” silanes 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).
• polysulphide silanes known as "symmetrical" silanes having the following general formula (III) are suitable in the following non-limiting definition: . _
• 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 alkylene
• C 1 -C 10 especially C 1 -C 4, in particular propylene
• R2 R2 in which:
• R.1 radicals substituted or unsubstituted, identical or different, represent an alkyl group Ci-Cis cycloalkyl, C5-C18 aryl or C 6 -Ci8 (preferably alkyl, Ci-C 6 , cyclohexyl or phenyl, especially C1-C4 alkyl groups, more particularly methyl and / or ethyl).
• polysulphurized silanes By way of examples of polysulphurized silanes, mention may be made more particularly of bis (C 1 -C 4 alkoxy) -alkyl (C 1 -C 4 ) -silylalkyl (C 1 -C 4 ) polysulfides (especially disulfides, trisulphides or tetrasulfides). such as polysulfides of bis (3-trimethoxysilylpropyl) or bis (3-triethoxysilylpropyl).
• TESPT bis (3-triethoxysilylpropyl) tetrasulfide
• TESPD bis (3-triethoxysilylpropyl) tetrasulfide
• TESPD bis (3-triethoxysilylpropyl) tetrasulfide
• TESPD bis (3-triethoxysilylpropyl) tetrasulfide
• TESPD bis (3-triethoxysilylpropyl) tetrasulfide
• TESPD bis (3-triethoxysilylpropyl) tetrasulfide
• TESPD bis (triethoxysilylpropyl) tetrasulfide
• polysulfides especially disulfides, trisulphides or in the patent application WO 02/083782 (or US 2004/132880).
• POS polyorganosiloxanes
• 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 amines , secondary or tertiary (for example trialkanol-amines), hydroxylated or hydrolysable POS, for example ⁇ , ⁇ -dihydroxy-polyorganosiloxanes (in particular ⁇ , ⁇ -dihydroxy-polydimethylsiloxanes), fatty acids such as for example stearic.
• hydrolysable silanes such as alkylalkoxysilanes (especially alkyltriethoxysilanes), polyols, polyethers (for example polyethylene glycols), primary amines , secondary or tertiary (for example trialkanol-amines), hydroxylated or hydrolysable POS, for example ⁇ ,
• the content of coupling agent is preferably between 0.1 and 12% by weight of the inorganic filler for a CTAB surface of 160 m 2 / g, more preferably between 4 and 10% by mass.
• inorganic filler for a CTAB surface area of 160m 2 / g; and / or the content of covering agent is preferably between 0.1 and 20% by weight of the inorganic filler for a CTAB surface of 160 m 2 / g, more preferably between 5 and 20% by mass of the inorganic filler for a surface of CTAB of 160m 2 / g.
• the coupling agent content can be adjusted to the specific surface level of the filler.
• the level of inorganic filler present in the compositions in accordance with the invention is greater than or equal to 5 parts by weight per hundred parts by weight of elastomer, phr, and represents at most 50% by mass fraction of the total charge of the composition, and that the carbon black content derived from acetylene is greater than 3 phr, the amount of carbon black derived from acetylene accounting for more than 50%> of the carbon black present in the composition by mass fraction.
• the amount of carbon black derived from acetylene represents more than 50% of the total charge present in the mass fraction composition.
• the amount of carbon black derived from acetylene accounts for more than 90% of the carbon black present in the composition. - - mass fraction, and even more preferably it represents 100% of the carbon black present in the composition.
• the total charge rate varies from 20 to 150 phr, preferably from 30 to 90 phr, and even more preferably from 30 to 70 phr.
• the carbon black content derived from acetylene is preferably greater than or equal to 10 phr.
• the level of inorganic filler is preferably greater than or equal to 8 phr.
• the black carbon content derived from acetylene varies from 10 to 40 phr and the inorganic filler content varies from 8 to 30 phr, and even more preferentially the inorganic filler content varies from 12 to 30 phr.
• the inorganic filler content represents at most 30% of the total mass fraction load and more preferably the inorganic filler content represents more than 40% by mass fraction of the total filler of the composition. .
• compositions in accordance with the invention may comprise a plasticizing oil and / or a plasticizing resin.
• plasticizing oil or plasticizing resin is meant an oil or a resin whose usual function is to facilitate the implementation, by a lowering of the Mooney plasticity.
• these plasticizing oils are defined as being at room temperature (23 ° C) liquids (that is to say, as a reminder, substances having the ability to take over the shape of their containing), which are, in contrast to resins or rubbers that are inherently solid.
• the extender oil is chosen from the group consisting of polyolefinic oils (that is to say from the polymerization of olefins, monoolefins or diolefins), paraffinic oils, naphthenic oils (low or high viscosity), aromatic oils, mineral oils, and mixtures of these oils.
• plasticizing resin is reserved in the present application, by definition, to a compound which is solid on the one hand at room temperature (23 ° C.) (as opposed to to a liquid plasticizer such as an oil), on the other hand compatible (that is to say miscible with the rate used, typically greater than 5 phr) with the rubber composition for which it is intended, so as to act as a true diluting agent.
• Hydrocarbon resins are polymers well known to those skilled in the art, miscible by nature in diene (s) elastomer compositions (s) when they are further qualified as “plasticizers". They have been described, for example, in the book “Hydrocarbon Resins” by R. Mildenberg, M. Zander and G. Collin (New York, VCH, 1997, ISBN 3-527-28617-9), chapter 5 of which is devoted their applications, in particular pneumatic rubber (5.5 “Rubber Tires and Mechanical Goods”). They may be aliphatic, aromatic or aliphatic / aromatic type that is to say based on aliphatic and / or aromatic monomers. They may be natural or synthetic, whether based on petroleum or not (if so, also known as petroleum resins). They are preferably exclusively hydrocarbon-based, that is to say they contain only carbon and hydrogen atoms.
• compositions in accordance with the invention may thus comprise one or more plasticizing oils and / or one or more plasticizing resins inasmuch as the total content of plasticizer (s) and plasticizer (s) resin (s) used is less than or equal to 30 phr, preferably it varies from 0 to 5 phr. Even more preferentially, the composition is devoid of plasticizing oil and plasticizing resin.
• plasticizer (s) and plasticizer (s) resin (s) used is less than or equal to 30 phr, preferably it varies from 0 to 5 phr. Even more preferentially, the composition is devoid of plasticizing oil and plasticizing resin.
• the rubber compositions in accordance with the invention may also comprise all or part of the usual additives normally used in elastomer compositions intended for the manufacture of tires or semi-finished products for tires, for example other plasticizers (other than the plasticizer system of the invention), preferably non-aromatic or very weakly aromatic, for example naphthenic oils, paraffinic oils, MES or TDAE oils, esters (in particular trioleates) of glycerol including natural esters such as vegetable oils of rapeseed or sunflower, pigments, protective agents such as anti-ozonants, anti-oxidants, anti-fatigue agents, a crosslinking system based on either sulfur or sulfur and / or peroxide donors and or bismaleimides, vulcanization accelerators, vulcanization activators, anti-reversion agents.
• plasticizers other than the plasticizer system of the invention
• non-aromatic or very weakly aromatic for example naphthenic oils, paraffinic oils, MES or TDAE oils
• compositions may also contain, in addition to the coupling agents, coupling activators, inorganic charge-covering agents or, more generally, processing aids that can be used in a known manner, thanks to an improvement in the dispersion. of the charge in the rubber matrix and a lowering of the viscosity of the compositions, to improve their processability in the green state, these agents being, for example, hydrolysable silanes such as alkylalkoxysilanes, polyols, polyethers, primary, secondary or tertiary amines, hydroxylated or hydrolysable polyorganosiloxanes.
• hydrolysable silanes such as alkylalkoxysilanes, polyols, polyethers, primary, secondary or tertiary amines, hydroxylated or hydrolysable polyorganosiloxanes.
• compositions are manufactured in suitable mixers, using two successive preparation phases well known to those skilled in the art: a first phase of work or thermomechanical mixing at high temperature, up to a maximum temperature of between 110 ° C. and 190 ° C. ° C, preferably between 130 ° C and 180 ° C, followed by a second mechanical working phase to a lower temperature, typically below 110 ° C, for example between 40 ° C and 100 ° C, phase in which the crosslinking system is incorporated.
• the method according to the invention for preparing a rubber composition for an inner tire liner comprises the following steps:
• the first phase is carried out in a single thermomechanical step in the course of which, in a suitable mixer such as a conventional internal mixer, all the necessary basic constituents (elastomer, filler and coupling agent if necessary and graphite), then in a second step, for example after one to two minutes of mixing, the other additives, optional additional coating or processing agents, with the exception of the crosslinking system.
• a suitable mixer such as a conventional internal mixer
• the other additives, optional additional coating or processing agents with the exception of the crosslinking system.
• the crosslinking system After cooling the mixture thus obtained, it is then incorporated in an external mixer such as a roll mill, maintained at low temperature (for example between 40 ° C and 100 ° C), the crosslinking system.
• the whole is then mixed for a few minutes, for example between 2 and 15 min.
• the crosslinking system is preferably a vulcanization system, that is to say a system based on sulfur (or a sulfur-donor agent) and a primary vulcanization accelerator.
• a vulcanization system that is to say a system based on sulfur (or a sulfur-donor agent) and a primary vulcanization accelerator.
• various known secondary accelerators or vulcanization activators such as zinc oxide, stearic acid or equivalent compounds, guanidine derivatives (in particular diphenylguanidine).
• Sulfur is used at a preferential rate of between 0.5 and 12 phr, in particular between 1 and 10 phr.
• the primary vulcanization accelerator is used at a preferred level of between 0.5 and 10 phr, more preferably between 0.5 and 5.0 phr.
• accelerator primary or secondary
• any compound capable of acting as an accelerator of vulcanization of diene elastomers in the presence of sulfur in particular thiazole-type accelerators and their derivatives, accelerators of thiuram type, zinc dithiocarbamates.
• accelerators are for example selected from the group consisting of 2-mercaptobenzothiazyl disulfide (abbreviated "MBTS”), tetrabenzylthiuram disulfide (“TBZTD”), N-cyclohexyl-2-benzothiazyl sulfenamide (“CBS”), N, N dicyclohexyl-2-benzothiazylsulfenamide (“DCBS”), N-tert-butyl-2-benzothiazylsulfenamide (“TBBS”), N-tert-butyl-2-benzothiazylsulfenamide (“TBSI”), zinc dibenzyldithiocarbamate (“ ZBEC ”) and mixtures of these compounds.
• MBTS 2-mercaptobenzothiazyl disulfide
• TBZTD tetrabenzylthiuram disulfide
• CBS N-cyclohexyl-2-benzothiazyl sulfenamide
• the final composition thus obtained is then calendered, for example in the form of a sheet or a plate, in particular for a characterization in the laboratory, or extruded, to form for example a rubber profile used for the manufacture of semi-finished products. finished such as tire treads.
• the vulcanization (or cooking) is conducted in a known manner at a temperature generally between 120 ° C and 200 ° C, for a sufficient time which may vary for example between 5 and 90 min depending in particular on the cooking temperature, the system of vulcanization adopted and the kinetics of vulcanization of the composition under consideration.
• compositions according to the invention may advantageously constitute the tread of tires and in particular tires for civil engineering.
• the latter may also constitute only part of the tire tread in the form of a zebra or drain situated, for example, in the circumferentially central zone of the tire and / or at the shoulders of the tread.
• a zebra or drain situated, for example, in the circumferentially central zone of the tire and / or at the shoulders of the tread.
• the mixture thus obtained is recovered, cooled and the vulcanization system (sulfur and sulfenamide accelerator) is added to an external mixer (homoformer) at 70 ° C., mixing the whole (productive phase) for about 5 to 6 hours. 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.
• the vulcanization (or cooking) is carried out at 120 ° C. for 300 minutes.
• compositions A1 and B1 are defined as follows:
• control composition A1 is a "conventional" tire tire tread composition of civil engineering including a blend of carbon black NI (not derived from acetylene) and silica,
• control composition B1 in which the whole of the carbon black NI 15 has been replaced by a carbon black derived from acetylene.
• composition B0 in accordance with the invention in which the carbon black NI 15 has been replaced by a carbon black derived from acetylene, has, as would be expected, an improved thermal conductivity (the value of ⁇ has increased) but surprisingly, an improved hysteresis (lowering of Tan (6) max) , in comparison with the control composition Al.
• This test aims to show another advantage obtained surprisingly with some of the compositions according to the invention, by comparing two compositions according to the invention having good properties of thermal conductivity and hysteresis.
• compositions B2, identical to the composition B 1 of the test 1, and C2 were prepared according to the method detailed above and have the same basic formulation identical to that given in the test 1.
• compositions B2 and C2 are in accordance with the present invention, they respectively comprise a carbon black fraction derived from acetylene and silica, in levels according to the invention.
• the differences in formulation, in phr, between the two compositions are presented in Table 3 which follows:
• composition C2 according to the invention exhibits, as the composition B2 according to the invention, a good thermal conductivity ( ⁇ value) and a low hysteresis (Tan ( ⁇ ) max) ).
• composition C2 having a silica content higher than that of the composition B2 makes it possible, with respect to the composition B2, a significant improvement in the energy at break even though the total amount of charge is identical. .

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