Classifications

• • 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
  • C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
  • C08K3/20—Oxides; Hydroxides
  • C08K3/22—Oxides; Hydroxides of metals
• • 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
  • C08K5/00—Use of organic ingredients
  • C08K5/04—Oxygen-containing compounds
  • C08K5/09—Carboxylic acids; Metal salts thereof; Anhydrides thereof
  • C08K5/098—Metal salts of carboxylic acids

Definitions

• the present invention relates to diene rubber compositions useful in particular for the manufacture of tires or semi-finished products for tires such as treads.
• vulcanization of diene elastomers by sulfur is widely used in the rubber industry, particularly in the tire industry.
• a relatively complex vulcanization system comprising, in addition to sulfur, various vulcanization accelerators as well as one or more vulcanization activators, in particular zinc derivatives such as zinc oxide (ZnO) is used. ) alone or used with fatty acids.
• Tire manufacturers are looking for solutions to greatly reduce or, if possible, eliminate zinc or its derivatives rubber formulations, because of the known environmental impact of these compounds, especially vis-à-vis water and aquatic organisms (R50 classification according to European Directive 67/548 / EC of 9 December 1996).
• a first object of the invention relates to a rubber composition, usable especially for the manufacture of tires, said rubber composition is based on at least one diene elastomer, containing less than 2 phr of zinc, meaning parts per cent of elastomer, and based on at least:
• a sulfur-based crosslinking system a zinc carboxylate of formula: (RCOO) 2 Zn in which R represents a hydrocarbon-based group chosen from alkyls, linear or branched, cyclic or otherwise, having from 1 to 16 carbon atoms; aryls, aralkyls or alkaryls having from 1 to 16 carbon atoms.
• R represents a hydrocarbon-based group chosen from alkyls, linear or branched, cyclic or otherwise, having from 1 to 16 carbon atoms; aryls, aralkyls or alkaryls having from 1 to 16 carbon atoms.
• the patent application KR-10-2004-0105992 describes the use of zinc carboxylate of formula (RCOO) 2 Zn where R represents a benzene or CH 3 (CH 2 ) 2 2 group used as a vulcanization activator.
• the subject of the invention is particularly the use of a rubber composition according to the invention for the manufacture of tires or semi-finished rubber products intended for these tires, these semi-finished products being, in particular, chosen from the group constituted by the treads, the sub-layers intended for example to be placed under these treads, the crown plies, the sidewalls, the carcass plies, the heels, the protectors, the tubes and the inner tires. waterproof for tire without chamber.
• the invention relates to a rubber composition in which the level of zinc is between 0.2 and 1.5 phr, and even more preferably between 0.2 and 1 phr.
• R represents a hydrocarbon group having from 1 to 11 carbon atoms
• the zinc carboxylate is zinc 2-ethyl hexanoate, zinc laurate or zinc acetate.
• the diene elastomer comprises more than 40 phr of isoprene elastomer.
• the reinforcing filler comprises carbon black in a content greater than 10 phr, preferably the reinforcing filler mainly comprises carbon black.
• the reinforcing filler comprises a blend of carbon black and an inorganic filler, in particular the inorganic filler comprises silica and more particularly the reinforcing filler. comprises silica and carbon black, the amount of silica being less than or equal to (by weight) the amount of carbon black.
• the rate of all the primary, secondary accelerators and vulcanization activators of the vulcanization system is between 0.5 and 10 phr, and more preferably between 0.5 and 5 phr.
• the invention also relates to the process for the preparation of a rubber composition based on at least one diene elastomer, containing less than 2 phr of zinc, characterized in that it is incorporated by kneading with the diene elastomer, at least a reinforcing filler, and a sulfur-based crosslinking system comprising a zinc carboxylate of formula (RCOO) 2 Zn, wherein:
• R represents a hydrocarbon group chosen from alkyls, linear or branched, cyclic or non-cyclic having from 1 to 16 carbon atoms, aryls, aralkyls or alkaryls having from 1 to 16 carbon atoms;
• composition according to the invention is particularly suitable for the manufacture of treads of tires intended to equip vehicles "heavy vehicles” (that is to say, metro, bus, road transport equipment (trucks, tractors, trailers), off-the-road vehicles), aircraft, civil engineering, agrarian, or handling equipment.
• vehicles "heavy vehicles” that is to say, metro, bus, road transport equipment (trucks, tractors, trailers), off-the-road vehicles), aircraft, civil engineering, agrarian, or handling equipment.
• the invention also relates to these ground connection systems of motor vehicles, these tires and semi-finished rubber products themselves, including treads, when they comprise a rubber composition according to the invention.
• the invention particularly relates to the use of such treads for the manufacture of new tires or the retreading of used tires.
• the invention also relates to these ground connection systems of motor vehicles, tires and treads both in the green state (i.e., before firing) and in the fired state (i.e., after crosslinking or vulcanization).
• compositions of the invention are based on: (i) at least one diene elastomer, (ii) at least one reinforcing filler, and a sulfur-based vulcanization system comprising at least (iii) a zinc carboxylate of formula (RCOO) 2 Zn.
• composition based on is meant in the present application a composition comprising the mixture and / or the reaction product of the various constituents used, some of these basic constituents (for example the coupling agent and the inorganic filler) being capable of, or intended to react with each other, at least in part, during the different phases of manufacture of the compositions, in particular during their vulcanization (firing).
• these basic constituents for example the coupling agent and the inorganic filler
• elastomer or rubber (both terms being synonymous) of the "diene” type, is generally meant an elastomer derived at least in part (ie a homopolymer or a copolymer) from monomers dienes (monomers carrying two carbon-carbon double bonds , conjugated or not).
• diene elastomers in known manner, can be classified into two categories: those said to be “essentially unsaturated” and those termed “essentially saturated”.
• essentially unsaturated diene elastomer is meant 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%); for example, diene elastomers such as butyl rubbers or copolymers of dienes and alpha-olefins of the EPDM type do not fall within this definition and may instead be described as essentially 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, one 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.
• 1,3-butadiene, 2-methyl-1,3-butadiene and 2,3-di-(C 1 -C 5) -l-3-butadienes are especially suitable.
• Suitable vinyl aromatic compounds are, for example, styrene, ortho-, meta-, para-methylstyrene, the "vinyl-toluene" commercial mixture, para-tertiarybutylstyrene, methoxystyrenes, chlorostyrenes, vinylmesitylene and divinylbenzene. vinyl naphthalene.
• the copolymers may contain between 99% and 20% by weight of diene units and between 1% and 80% by weight of vinyl aromatic 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, sequence, microsequential, and be prepared in dispersion or in solution; they can be coupled and / or star or functionalized with a coupling agent and / or starring or functionalization.
• Polybutadienes and in particular those having a 1,2-unit content of between 4% and 80%, or those having a cis-1,4 content of greater than 80%, polyisoprenes and copolymers of butadiene- styrene and in particular those having a styrene content of between 5% and 50% by weight and more particularly between 20% and 40%, a 1,2-butadiene content of the butadiene part.
• Tg glass transition temperature
• butadiene-styrene-isoprene copolymers 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%, are especially suitable.
• the diene elastomer of the composition according to the invention is chosen from the group of diene elastomers (highly unsaturated) consisting of polybutadienes (BR), synthetic polyisoprenes (IR), rubber natural (NR), butadiene copolymers, isoprene copolymers and mixtures of these elastomers.
• diene elastomers highly unsaturated consisting of polybutadienes (BR), synthetic polyisoprenes (IR), rubber natural (NR), butadiene copolymers, isoprene copolymers and mixtures of these elastomers.
• Such copolymers are more preferably selected from the group consisting of butadiene-styrene copolymers (SBR), isoprene-butadiene copolymers (BIR), isoprene-styrene copolymers (SIR), isoprene-copolymers of butadiene-styrene (SBIR) and mixtures of such copolymers.
• SBR butadiene-styrene copolymers
• BIR isoprene-butadiene copolymers
• SIR isoprene-styrene copolymers
• SBIR isoprene-copolymers of butadiene-styrene
• the diene elastomer is preferably an isoprene elastomer, ie a homopolymer or a isoprene copolymer, in other words a diene elastomer selected from the group consisting of natural rubber (NR), synthetic polyisoprenes (IR), different isoprene copolymers or a mixture of these elastomers.
• NR natural rubber
• IR synthetic polyisoprenes
• isoprene copolymers examples include copolymers of isobutene-isoprene (butyl rubber - HR), 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 diene elastomer may also consist, in whole or in part, of another highly unsaturated elastomer such as, for example, an SBR elastomer.
• the diene elastomer it is advantageous for the diene elastomer to contain at least 40 phr of isoprene elastomer.
• the diene elastomer is preferably an SBR copolymer, in particular an SBR prepared in solution, preferably used in admixture with a polybutadiene; more preferably, the SBR has a styrene content of between 20% and 30% by weight, a vinyl content of the butadiene part of between 15% and 65%, a trans-1,4 content of between 15% and 75% and a Tg between -20 ° C and -55 ° C, and the polybutadiene has more than 90% cis-1,4 bonds.
• compositions of the treads of 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 other polymers.
• elastomers for example thermoplastic polymers.
• carbon black in a proportion of greater than 10 phr.
• the amount of carbon black may advantageously be greater than 30 phr, especially when it constitutes the only reinforcing filler or the majority reinforcing filler.
• the carbon black can of course be used in cutting with reinforcing fillers and in particular inorganic fillers.
• inorganic fillers comprise silica, preferentially the latter in a pneumatic application intended for heavy vehicles will remain in a proportion less than or equal to the amount of carbon black.
• carbon blacks are suitable for all carbon blacks, in particular blacks of the HAF, ISAF, SAF type conventionally used in tires and particularly in tire treads.
• blacks NIl 5, Nl 34, N234, N330, N339, N347, N375 may be mentioned.
• a precipitated silica is preferably used.
• highly dispersible in particular when the invention is implemented for the manufacture of tires having a low rolling resistance; as non-limiting examples of such preferential highly dispersible silicas, mention may be made of the silicas Ultrasil 7000 and Ultrasil 7005 from the company Degussa, the silicas Zeosil 1 165MP, 1 135MP and II 15MP from the company Rhodia, the silica Hi-SiI EZ1 50G from the PPG company, the Zeopol 8715, 8745 and 8755 silicas of the Huber Company, treated precipitated silicas such as, for example, the "aluminum doped" silicas described in the above-mentioned application EP-A-0735088.
• the reinforcing alumina (Al 2 O 3) preferably used is a highly dispersible alumina having a BET surface area ranging from 30 to 400 m 2 / g, more preferably from 60 to 250 m 2 / g, an average particle size of at most 500 nm. more preferably at most equal to 200 nm.
• Such reinforcing aluminas mention may in particular be made of "Baikalox A 125" or "CR125” (Baikowski company), "APA-100RDX” (Condea), "Aluminoxid C” (Degussa) or “AKP-GO” aluminas. "(Sumitomo Chemicals).
• inorganic filler suitable for use in the rubber compositions of the invention, mention may also be made of aluminum (oxide) hydroxides, aluminosilicates, titanium oxides, carbides or nitrides of silicon, all of the reinforcing type as described in WO 99/28376 (or US 6,610,261), WO 00/73372 (or US 6,747,087), WO 02/053634 (or US2004-0030017), WO 2004/003067, WO 2004 / 056915.
• coupling agent is understood, in known manner, an agent capable of establishing a sufficient bond, chemical and / or physical, between the inorganic filler and the diene elastomer; such a coupling agent, at least bifunctional, has for example as simplified general formula "Y-A-X", in which:
• Y represents a functional group ("Y" function) which is capable of physically and chemically bonding to the inorganic filler, such a bond can be established, for example, between a silicon atom of the coupling and the surface hydroxyl (OH) groups of the inorganic filler (for example surface silanols when it is silica);
• X represents a functional group ("X" function) capable of binding physically and / or chemically to the diene elastomer, for example via a sulfur atom;
• A represents a divalent group for connecting Y and X.
• Coupling agents in particular silica / diene elastomer have been described in a very large number of documents, the best known being bifunctional organosilanes bearing alkoxyl functions (that is to say, by definition, "alkoxysilanes") to as functions "Y” and, as functions "X", functions capable of reacting with the diene elastomer such as for example polysulfide functions.
• reinforcing filler ie, reinforcing inorganic filler plus carbon black, if appropriate
• inert fillers such as clay particles, bentonite, talc, chalk, kaolin, usable for example in sidewalls or tire treads colored.
• 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, for example plasticizers or extension oils, which these are of aromatic or non-aromatic nature, pigments, protective agents such as anti-ozone waxes, chemical antiozonants, anti-oxidants, anti-fatigue agents, reinforcing resins, acceptors (for example phenolic novolac resin) or methylene donors (for example HMT or H3M) as described for example in the application WO 02/10269 (or US2003-0212185).
• plasticizers or extension oils which these are of aromatic or non-aromatic nature, pigments, protective agents such as anti-ozone waxes, chemical antiozonants, anti-oxidants, anti-fatigue agents, reinforcing resins, acceptors (for example phenolic novolac resin) or methylene donors (for example HMT or H3M) as described for example in the application WO 02/10269 (or US
• plasticizers or extension oils generally remaining in amounts of less than or equal to 30 phr.
• Vulcanization or crosslinking system Vulcanization or crosslinking system
• compositions also comprise a crosslinking system based on either sulfur, or sulfur and / or peroxide and / or bisphenolamide donors, vulcanization accelerators, vulcanization activators.
• a crosslinking system based on either sulfur, or sulfur and / or peroxide and / or bisphenolamide donors, vulcanization accelerators, vulcanization activators.
• a activator or an accelerator is based on zinc, the sum of zinc elements included in total in the composition must comply with a total zinc content of less than 2 phr, according to the invention.
• the vulcanization system itself is preferably based on sulfur and a primary vulcanization accelerator, in particular a sulfenamide type accelerator, as chosen from the group consisting of 2-mercaptobenzothiazyl disulfide (abbreviated "MBTS").
• a primary vulcanization accelerator in particular a sulfenamide type accelerator, as chosen from the group consisting of 2-mercaptobenzothiazyl disulfide (abbreviated "MBTS").
• MBTS 2-mercaptobenzothiazyl disulfide
• CBS N-cyclohexyl-2-benzothiazyl sulphenamide
• DCBS N-dicyclohexyl-2-benzothiazyl sulphenamide
• TBBS N-tert-butyl-2-benzothiazyl sulphenamide
• TBSI N-tert-butyl-2-benzothiazyl sulfenimide
• 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.
• the set of primary, secondary accelerators and vulcanization activators is used at a preferential rate of between 0.5 and 10 phr, more preferably between 0.5 and 5.0 phr, in particular when the invention applies to a tire tread.
• compositions according to the invention may comprise zinc oxides in a very small amount to limit the amount of zinc present in the composition, preferably in amounts of less than 0.5 phr. And advantageously the composition is free of zinc oxide which is replaced by a zinc carboxylate.
• the zinc carboxylates according to the invention are zinc carboxylates of formula (RCOO) 2 Zn, in which R represents a hydrocarbon group chosen from linear or branched, cyclic or non-cyclic alkyls having from 1 to 16 carbon atoms, aryls, aralkyls or alkaryls having 1 to 16 carbon atoms.
• R represents a hydrocarbon group chosen from linear or branched, cyclic or non-cyclic alkyls having from 1 to 16 carbon atoms, aryls, aralkyls or alkaryls having 1 to 16 carbon atoms.
• They are preferably used so that they constitute the only zinc supply in the composition or, failing this, the main zinc supply, so that the total amount of zinc in the composition is between 0.2 and 1.5. and more preferably between 0.2 and 1 phr.
• the corresponding carboxylates whose radical R has between 1 and 11 carbon atoms such as zinc acetate, corresponding to R with 1 carbon atom, zinc 2-hexyl hexanoate, R 7 carbon atoms , zinc laurate, R. has 1 1 carbon atoms.
• the invention also relates to a process for preparing a rubber composition based on diene elastomer, containing less than 2 phr of zinc, characterized in that at least one diene elastomer is incorporated by mixing with at least one diene elastomer. reinforcing filler, and at least one sulfur-based crosslinking system comprising a zinc carboxylate of formula (RCOO) 2 Zn, wherein:
• R represents a hydrocarbon group chosen from alkyls, linear or branched, cyclic or non-cyclic having from 1 to 16 carbon atoms, aryls, aralkyls or alkaryls having from 1 to 16 carbon atoms;
• the rubber compositions according to the invention are manufactured in appropriate mixers, using two successive preparation phases according to a general procedure well known to those skilled in the art: a first thermomechanical working or mixing phase (sometimes referred to as a "no" phase). -productive ”) at high temperature, up to a maximum temperature of between 130 ° C and 200 ° C, preferably between 145 ° C and 185 ° C, followed by a second phase of mechanical work (sometimes called phase" Producer ”) at a lower temperature, typically below 120 ° C., for example between 60 ° C. and 100 ° C., a finishing phase during which the crosslinking or vulcanization system is incorporated.
• a first thermomechanical working or mixing phase (sometimes referred to as a "no" phase).
• -productive ) at high temperature, up to a maximum temperature of between 130 ° C and 200 ° C, preferably between 145 ° C and 185 ° C
• a second phase of mechanical work sometimes called phase” Producer
• a finishing phase
• all the basic constituents of the compositions of the invention with the exception of the vulcanization system, namely carbon black, a possible other reinforcing filler, a possible coupling agent. are intimately incorporated, by kneading, with the diene elastomer during the so-called non-productive first phase, that is to say that it is introduced into the mixer and kneaded thermomechanically, one or more steps, at least these different basic constituents until reaching the maximum temperature between 130 ° C and 200 ° C, preferably between 145 ° C and 185 ° C.
• the first (non-productive) phase is carried out in a single thermomechanical step during which all the necessary constituents, the possible coating agents, are introduced into a suitable mixer such as a conventional internal mixer. or other complementary additives and other additives, with the exception of the vulcanization system.
• the total mixing time in this non-productive phase is preferably between 1 and 15 minutes.
• the vulcanization system is then incorporated at low temperature, generally in a mixer. external such as a roll mill; the whole is then mixed (productive phase) for a few minutes, for example between 2 and 15 min.
• the vulcanization system itself is preferably based on sulfur and a primary accelerator, preferably of sulfenamide type as previously detailed in the vulcanization system.
• various known secondary accelerators or vulcanization activators including one or more zinc carboxylates of formula (RCOO 2 Zn according to the invention, or even other zinc derivatives insofar as the latter remain in the minority and lower than the amounts specified in the section on the vulcanization system, and optionally fatty acids such as stearic acid, guanidine derivatives (in particular diphenylguanidine), etc.
• the final composition thus obtained is then calendered, for example in the form of a sheet or a plate, in particular for a characterization in the laboratory, or else extruded in the form of a rubber profile that can be used, for example, as a tread. tire for passenger vehicle.
• the vulcanization (or cooking) is carried out in a known manner at a temperature generally of between 130 ° 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.
• R represents a hydrocarbon group chosen from alkyls, linear or branched, cyclic or non-cyclic having from 1 to 16 carbon atoms, aryls, aralkyls or alkaryls having from 1 to 16 carbon atoms, comprises the following steps: the diene elastomer, in a mixer, the reinforcing filler and the zinc carboxylate of formula (RCOO) 2 Zn by thermomechanically kneading the whole, in one or more times, until a maximum temperature of between 130 ° C. and 200 ° C.
• more than 80% by weight and preferably more than 90% of the zinc present in the composition is derived from the zinc carboxylate of formula (RCOO) 2 Zn and even more preferably 100% of the zinc of the composition is derived from said zinc carboxylate.
• the rubber compositions are characterized, before and after firing, as indicated below.
• the measurements are carried out at 130 ° C., in accordance with the French standard NF T 43-005.
• the evolution of the consistency index as a function of time makes it possible to determine the toasting time of the rubber compositions, evaluated according to the above-mentioned standard by the parameter T5 (case of a large rotor), expressed in minutes, and defined as being the time required to obtain an increase in the consistometric index (expressed in MU) of 5 units above the minimum value measured for this index.
• the measurements are carried out at 150 ° C. with an oscillating chamber rheometer according to DIN 53529 - Part 3 (June 1983).
• the evolution of the rheometric torque, ⁇ Couple, as a function of time describes the evolution of the stiffening of the composition as a result of the vulcanization reaction.
• the measurements are processed according to DIN 53529 - Part 2 (March 1983): T 0 is the induction time, that is to say the time required for the beginning of the vulcanization reaction; T ⁇ (for example T 99 ) is the time necessary to wing a convection of cc%, that is to say oc% (for example 99%) of the difference between the minimum and maximum couples.
• T 0 is the induction time, that is to say the time required for the beginning of the vulcanization reaction;
• T ⁇ (for example T 99 ) is the time necessary to wing a convection of cc%, that is to say oc% (for example
• the breaking stresses (in MPa) and the elongations at break (in%) are also measured. All these tensile measurements are carried out at a temperature of 100 ° C. ⁇ 2 ° C., and under normal humidity conditions (50 ⁇ 5% relative humidity), according to the French standard NF T 40-101 (December 1979). ).
• the dynamic properties ⁇ G * and tan ( ⁇ ) max 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 is performed from 0.1% to 45% (forward cycle) and then from 45% to 0.1% (return cycle).
• compositions presented in the following tests are prepared in the following manner: an internal mixer, filled to 70% and whose initial tank temperature is approximately 60 ° C., is successively introduced into the reinforcing filler ( carbon black, others optionally optional fillers and optionally coupling agent), the diene elastomer as well as the various other ingredients including the secondary vulcanization accelerator with the exception of the rest of the vulcanization system.
• Thermomechanical work (non-productive phase) is then carried out in one step, which lasts a total of about 3 to 4 minutes, until a maximum temperature of "fall" of 165 ° C. is obtained. The mixture thus obtained is recovered.
• 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 treads.
• a control composition is compared with a composition according to the invention, these two compositions differing only in their vulcanization system.
• compositions, controls and according to the invention are intended for the manufacture of a tread of a tire for a motor vehicle HGV.
• the vulcanization system of the control compositions contains 3 phr of ZnO (ie 2.4 phr of zinc) whereas the vulcanization system of the compositions in accordance with the invention does not contain ZnO or stearic acid but ZEH, 2-ethyl hexanoate zinc, at a rate of 3 phr (ie 0.56 phr of zinc).
• This replacement corresponds to a reduction of 77% by weight of the amount of zinc in the composition.
• the simple increase in sulfur and primary accelerator levels does not make it possible to compensate in terms of rubber properties the sharp decrease in zinc in the composition.
• compositions Tl and Al contain only natural rubber as diene elastomer and only carbon black as a reinforcing filler
• compositions T2 and A2 contain only natural rubber as diene elastomer and black carbon cutting
• the compositions T3 and A2 contain a blend of NR / BR / SBR as the diene elastomer and only carbon black as the reinforcing filler.
• Table 2 gives the properties after baking at 165 ° C. for 15 minutes of the various compositions mentioned above.
• compositions T1 and A1 have not only a number of sulfur bridges that are almost identical but also a distribution of these bridges of identical sulfur, that is to say that these two bridges are identical.
• compositions Tl and Al have vis-à-vis each other the same percentage of bridges of sulfur formed with a single sulfur atom, the same percentage of bridges of sulfur formed with two sulfur atoms and the same percentage sulfur bridges formed with more than two sulfur atoms.
• This identical distribution is synonymous with properties of same crosslinking rubber for both compositions despite the considerable difference in the zinc level between the two.
• compositions T2 and A2 based on natural rubber and which contain silica no decrease in properties is observed from T2 to A2 (the difference in elongation at break is not significant) with A2 according to the invention, hysteretic properties (tan ( ⁇ ) max ) similar to T2 and a crosslinking density (MA100) which is even greater than that of T2.
• the invention functions as well with a reinforcing filler 100% carbon black as with a black carbon / silica blend.
• compositions T3 and A3 based on an NR / BR / SBR blend there is also an overall maintenance of all the properties of the composition A3 according to the invention with respect to the composition T3.
• synthetic rubbers are less dependent on the vulcanization activation system than natural rubber.
• DCBS N, N-dicyclohexyl-2-benzothiazyl sulfenamide
• ZEH zinc 2-ethyl hexanoate (Schill and Seilacher)
• compositions according to the invention that is to say including carboxylates according to the invention, with respect to a control composition comprising ZnO (3 part) as a vulcanization activator. ..
• the control composition is the composition T1 of Example 1, the composition A1 is identical to that of Example 1 according to the invention which includes as vulcanization activator ZEH at the rate of 3 phr (corresponding to a total zinc content in the composition of 0.56 phr).
• compositions B2 and C2 are in accordance with the invention, their formulations are identical to that of Al with the exception of the vulcanization activator whose rate corresponds in each composition to a zinc level of 0.56 phr, and are the following: -
• B2 zinc acetate according to the invention, carboxylate of formula
• compositions A3, B3 and C3 have the same formulation as the composition A1 of Example 1 with the exception of the vulcanization activator:
• compositions A1, B2, C2, A3, B3 and C3 therefore have the same sulfur content of 2 phr and the same level of vulcanization primary accelerator DCBS of 1, 6 phr.
• Table 3 shows an increase in ⁇ Couple for the three compositions Al, B2 and C2 according to the invention compared to the control composition Tl, which means a strong crosslinking for the three compositions Al, B2 and C2.
• compositions A1, B2 and C2 according to the invention.

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• 2007
  • 2007-12-21 JP JP2009543389A patent/JP6000505B2/ja not_active Expired - Fee Related
  • 2007-12-21 CN CN2007800505409A patent/CN101589099B/zh not_active Expired - Fee Related
  • 2007-12-21 EP EP07866253A patent/EP2104704A1/fr not_active Withdrawn
  • 2007-12-21 WO PCT/EP2007/011332 patent/WO2008080582A1/fr not_active Ceased
  • 2007-12-21 US US12/521,774 patent/US8232338B2/en not_active Expired - Fee Related

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