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
  • 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
• • 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
• • 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
  • C08K5/00—Use of organic ingredients
  • C08K5/0008—Organic ingredients according to more than one of the "one dot" groups of C08K5/01 - C08K5/59
  • C08K5/005—Stabilisers against oxidation, heat, light, ozone
• • 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
  • C08K5/0091—Complexes with metal-heteroatom-bonds

Definitions

• the field of the present invention is that of rubber compositions that can be used in particular for the manufacture of semi-finished articles or products made of rubber such as, for example, pneumatic tires.
• the present invention is more particularly related to antidegradant systems and agents for protecting these rubber compositions against aging due to oxidation.
• antioxidants including derivatives of p-phenylenediamine (“PPD” or “PPDA”) such as for example N-isopropyl -N'-phenyl-p-phenylenediamine (“I-PPD”) or N, 3-dimethylbutyl-N'-phenyl-p-phenylenediamine (“6- PPD”), quinoline derivatives ("TMQ”), both excellent antioxidants and antiozonants (see, for example, patent applications WO 2004/033548, WO 2005/063510, WO 2005/133666).
• PPD p-phenylenediamine
• I-PPD N-isopropyl -N'-phenyl-p-phenylenediamine
• 6- PPD N, 3-dimethylbutyl-N'-phenyl-p-phenylenediamine
• TMQ quinoline derivatives
• antioxidants are today used systematically in diene rubber compositions, in particular in tire compositions, in order to combat
• antioxidants concentration in the rubber compositions naturally decreases over time due to their very chemical function, that they also have a strong natural propensity to migrate from more concentrated areas to less areas. concentrated in antioxidant, so much so that the man of the The business is made to use relatively large quantities of product, which is relatively expensive and otherwise detrimental to the appearance of finished products due to the high tackiness of a large number of antioxidants, especially p-phenylenediamine.
• a first object of the invention relates to a rubber composition, usable in particular for the manufacture of a tire, comprising at least one diene elastomer, a reinforcing filler, a crosslinking system, between 0.2 and 10 phr. an antioxidant and between 0.2 and 10 phr of chromium (III) acetylacetonate.
• the longevity of rubber vulcanizates can thus be improved, in particular that of pneumatic tires which can be subjected in known manner to particularly severe driving conditions, in particular in a humid and corrosive atmosphere.
• the present invention also relates to the use of a composition according to the invention for the manufacture of articles or semi-finished products made of rubber, particularly pneumatic tires, in particular those intended for equipping tourism-type motor vehicles, SUVs. ⁇ "Sport Utility Vehicles"), two wheels (including bicycles, motorcycles), aircraft, such as industrial vehicles chosen from light trucks, "heavy vehicles” - that is to say, subway, bus, road transport equipment (trucks tractors, trailers), off-the-road vehicles such as agricultural or civil engineering -, other transport or handling vehicles.
• the invention also relates per se to any article or semi-finished product of rubber, in particular a tire, comprising a composition according to the invention.
• the invention also relates to the use of a composition according to the invention for the manufacture of a metal / rubber composite comprising a rubber composition and at least one metal reinforcement capable of adhering to said rubber composition.
• the invention also relates to a metal / rubber composite comprising a diene rubber composition according to the invention and at least one metal reinforcement capable of adhering to said rubber composition.
• the rubber compositions according to the invention are characterized, before and after cooking, as indicated below.
• the Mooney plasticity measurement is carried out according to the following principle: the composition in the uncured state (ie, before firing) is molded in a cylindrical chamber heated to 100 ° C. After one minute of preheating, the rotor rotates within the test piece at 2 rpm and the useful torque is measured to maintain this movement after 4 minutes of rotation.
• the measurements are carried out at 130 ° C. in accordance with the French standard NF T 43-005 (1991).
• the evolution of the consistometric 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.
• T ⁇ (for example T 95 ) is the time required to reach a conversion of ⁇ %, that is to say ⁇ % (for example 95 %) of the difference between the minimum and maximum couples.
• 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).
• the composition of the invention is a rubber-based composition (ie, comprising the mixture or the reaction product) of at least one diene elastomer, a reinforcing filler, a crosslinking system, between 0.2 and 10 phr of water. an antioxidant; it furthermore has the novel and essential characteristic of having between 0.2 and 10 phr of an acetylacetonate of alkaline or alkaline-earth metal.
• iene elastomer or indistinctly rubber is meant in known manner 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 can be classified in known manner into two categories: those known as “essentially unsaturated” and those known as “essentially saturated”.
• the term “diene elastomer” is used herein to mean a diene elastomer derived at least in part from conjugated diene monomers having a level of units or units of diene origin (conjugated dienes) which is greater than 15% (%). in moles).
• diene elastomers such as butyl rubbers or copolymers of dienes and alpha-olefins EPDM type do not fall within the above definition and may be particularly described as “substantially saturated diene elastomers" "(low or very low diene origin, always less than 15%).
• substantially saturated diene elastomers low or very low diene origin, always less than 15%.
• 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 more particularly be understood as being capable of being used in the compositions in accordance with the invention:
• diene elastomer any type of diene elastomer, one skilled in the art of the tire will understand that the present invention is first used with essentially unsaturated diene elastomers, in particular of the type (a) or ( b) above.
• the diene elastomer is selected from the group consisting of polybutadienes (BR), natural rubber (NR), synthetic polyisoprenes (IR), butadiene copolymers, isoprene copolymers, and mixtures of these elastomers.
• Such copolymers are more preferably chosen from the group consisting of butadiene-styrene copolymers (SBR), the latter being prepared by emulsion polymerization (ESBR) as in solution (SSBR), the isoprene-butadiene copolymers (BIR ), isoprene-styrene copolymers (SIR) and isoprene-butadiene-styrene copolymers (SBIR).
• SBR butadiene-styrene copolymers
• ESBR emulsion polymerization
• SBIR isoprene-butadiene copolymers
• SIR isoprene-styrene copolymers
• SBIR isoprene-butadiene-styrene copolymers
• 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.
• a coupling agent for example, there may be mentioned for example functional groups comprising a C-Sn bond or amino functional groups such as benzophenone for example;
• a reinforcing inorganic filler such as silica mention may be made, for example, of silanol or polysiloxane functional groups having a silanol end (as described, for example, in US Pat. No.
• alkoxysilane groups as described, for example, in US 5,977,238), carboxylic groups (as described, for example, in US 6,815,473 or US 2006/0089445) or polyether groups (as described for example in US 6,503,973).
• elastomers such as SBR, BR, NR or IR of the epoxidized type.
• 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%) of trans-1,4 bonds of between 10% and 80%, butadiene-isoprene copolymers and especially those having an isoprene content of between 5% and 90% by weight and a Tg of -40 ° C. to -80 ° C., the isoprene-styrene copolymers and in particular those having a styrene content of between 5% and 50% by weight and a Tg between -25 ° C and -
• butadiene-styrene-isoprene copolymers 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 isoprenic part of between 10% and 50%, and more generally any butadiene-based copolymer.
• styrene-isoprene having a Tg of between -20 ° C. and
• the majority diene elastomer by weight is 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 to 35% by weight, is used in particular. 45%, a vinyl 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 majority diene elastomer by weight is an isoprene elastomer.
• the compositions of the invention are intended to constitute, in pneumatic tires, the rubber matrices of certain treads (for example for industrial vehicles), crown reinforcement plies (for example). example of working plies, protective plies or hooping plies), carcass reinforcement plies, sidewalls, beads, protectors, underlayments, rubber blocks and other internal gums providing the interface between the aforesaid areas of the tires.
• isoprene elastomer in known manner a homopolymer or a 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 examples include isobutene-isoprene copolymers (butyl rubber-HR), isoprene-styrene copolymers (SIR), isoprene-butadiene copolymers (BIR) or isoprene-butadiene-styrene copolymers. (SBIR).
• This isoprene elastomer is preferably natural rubber or a synthetic cis-1,4 polyisoprene; of these synthetic polyisoprenes, polyisoprenes having a content (mol%) of cis-1,4 bonds greater than 90%, more preferably still greater than 98%, are preferably used.
• the composition complies with the invention may contain at least one essentially saturated diene elastomer, in particular at least one EPDM copolymer or a butyl rubber (optionally chlorinated or brominated), that these copolymers may be used alone or as a mixture with highly unsaturated diene elastomers as mentioned previously, especially 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 0 C and 0 0 C and d one (one or more) diene elastomers called "at low Tg” between -110 ° C. and -80 ° C., more preferably between -105 ° C. and -90 ° C.
• the high-Tg elastomer is preferably chosen in the group consisting of S-SBR, E-SBR, natural rubber, synthetic polyisoprenes (having a content (% molar) of cis-1,4 chains preferably greater than 95%), BIR, SIRs, SBIRs, and mixtures of these elastomers.
• the low Tg elastomer preferably comprises butadiene units at a level (mol%) of at least 70%; it consists preferably of a polybutadiene (BR) having a content (mol%) of cis-1,4 chains greater than 90%.
• the rubber composition of the invention may contain one or more diene elastomers, the latter or they may also be used in combination with any type of synthetic elastomer other than diene, or even with polymers other than elastomers, for example thermoplastic polymers.
• composition of the invention comprises any type of so-called reinforcing filler known for its ability to reinforce a rubber composition that can be used for the manufacture of tires, for example an organic filler such as carbon black, a reinforcing inorganic filler such as silica to which is associated in a known manner a coupling agent, or a mixture of these two types of filler.
• an organic filler such as carbon black
• a reinforcing inorganic filler such as silica to which is associated in a known manner a coupling agent, or a mixture of these two types of filler.
• Such a reinforcing filler typically consists of nanoparticles 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.
• the content of total reinforcing filler is between 30 and 150 phr.
• the total reinforcing filler content is more preferably within a range of 40 to 120 phr.
• an external rubber composition of the tire of the invention from 40 to 150 phr, in particular from 50 to 120 phr of carbon black, silica, or a mixture of silica and carbon black.
• Carbon blacks are suitable for all carbon blacks, in particular blacks of the HAF, ISAF, SAF type conventionally used in tires or their treads (so-called pneumatic grade blacks).
• carbon blacks of the 100, 200, 300, 600 or 700 series for example blacks Nl 15, N134, N234, N326, N330, N339, N347, N375, are particularly suitable.
• 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).
• organic fillers other than carbon blacks
• functionalized polyvinyl organic fillers as described in applications WO-A-2006/069792 and WO-A-2006/069793, WO-A-2008/003434. and WO-A-2008/003435.
• "Reinforcing inorganic filler” means any inorganic or mineral filler, irrespective of its color and origin (natural or synthetic), also called “white” filler or sometimes "clear” filler as opposed to carbon black.
• a rubber composition intended for the manufacture of tires in other words able to replace, in its reinforcing function, a conventional carbon black pneumatic grade; such a filler is generally characterized, in known manner, by the presence of hydroxyl groups (-OH) on its surface.
• 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, especially between 60 and 300 m 2 / g.
• HDS highly dispersible precipitated silicas
• the Ultrasil 7000 and Ultrasil 7005 silicas from Degussa mention may be made of, for example, the Ultrasil 7000 and Ultrasil 7005 silicas from Degussa, the Zeosil 1165MP, 1135MP and 1115MP silicas from Rhodia, the Hi-SiI silica EZ150G from the PPG company, the Zeopol 8715, 8745 and 8755 silicas of the Huber Company.
• 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.
• organosilanes or at least bifunctional polyorganosiloxanes are used.
• 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 having the following general formula (I) are not suitable for the following definition:
• x is an integer of 2 to 8 (preferably 2 to 5);
• the symbols A which are identical or different, represent a divalent hydrocarbon group (preferably an alkylene Ci-Ci 8 or an arylene group C O -C I2, more particularly alkylene Ci-Cio, including Ci-C 4 , especially propylene);
• the symbols Z identical or different, correspond to one of the three formulas below: -,
• radicals R 1 substituted or unsubstituted, identical or different, represent an alkyl group Ci-8 cycloalkyl, C5-C18 aryl or C 6 -C 8 (preferably alkyl Ci-C 6, cyclohexyl or phenyl, especially alkyl groups, C1-C4 alkyl, more particularly methyl and / or ethyl).
• the radicals R 2 substituted or unsubstituted, which are identical to or different from one another, represent a C 1 -C 18 alkoxyl or C 5 -C 18 cycloalkoxyl group (preferably a group chosen from C 1 -C 8 alkoxyls and C 5 cycloalkoxyls); -C 8 , more preferably still a group selected from C1-C4 alkoxyls, in particular methoxyl and ethoxyl).
• silane polysulfides are more particularly the bis (mono, trisulfide or tetrasulfide) of bis (alkoxyl (Ci-C4) alkyl (C 1 -C 4) alkyl SiIyI- (Ci-C 4 )), 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 (3-triethoxysilylpropyl) tetrasulfide
• TESPD bis (triethoxysilylpropyl) tetrasulfide
• polysulfides especially disulfides, trisulphides or in the aforementioned patent application WO 02/083782 (or US 7,217,751).
• silanes carrying at least one thiol function (-SH) (called mercaptosilanes) and / or of at least one blocked thiol function, as described for example in patents or patent applications US 6,849,754, WO 99/09036, WO 2006/023815, WO 2007/098080.
• the content of coupling agent is preferably between 2 and 15 phr, more preferably between 3 and 12 phr.
• 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.
• 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.
• These primary accelerators are more preferably selected from the group consisting of 2-mercaptobenzothiazyl disulfide (abbreviated "MBTS”), N-cyclohexyl-2-benzothiazyl sulfenamide (abbreviated "CBS”), N, N-dicyclohexyl-2-benzothiazyl sulphenamide (abbreviated "DCBS”), N-tert-butyl-2-benzothiazyl sulphenamide (abbreviated "TBBS”), N-tert-butyl-2-benzothiazyl sulphenimide (abbreviated "TBSI”) and mixtures of these compounds .
• MBTS 2-mercaptobenzothiazy
• composition of the invention has the characteristic of comprising between 0.2 and 10 phr of an antioxidant, preferably between 0.3 and 6 phr, more preferably between 0.5 and 4 phr of such an antioxidant.
• the antioxidant used in the composition of the invention is any antioxidant capable of delaying, in a known manner, the aging of rubber vulcanizates attributable to the action of oxygen.
• PPD para-phenylenediamine derivatives
• PPDA para-phenylenediamine derivatives
• substituted para-phenylenediamines such as, for example, N, 3-dimethylbutyl-N'-phenyl.
• p-phenylenediamine (more commonly known by the abbreviated term "6-PPD”), N-isopropyl-N'-phenyl-p-phenylenediamine (abbreviated as "I-PPD”), phenylcyclohexyl-p- phenylenediamine, N, N'-di (1,4-dimethylpentyl) -p-phenylenediamine, N, N'-diaryl-p-phenylenediamine (“DTPD”), diaryl-p- phenylenediamine (“DAPD”), 2,4,6-tris (N, 4-dimethylpentyl-p-phenylenediamino) -1,3,5-triazine, and mixtures of such diamines.
• 6-PPD N-isopropyl-N'-phenyl-p-phenylenediamine
• I-PPD N-isopropyl-N'-phenyl-p-
• TMQ quinoline derivatives
• Diphenylamines or substituted triphenylamines may also be mentioned, as described for example in applications WO 2007/121936 and WO 2008/055683, in particular 4,4'-bis (isopropylamino) -triphenylamine, 4,4'-bis (1,3-dimethylbutylamino) triphenylamine, 4,4'-bis (1,4-dimethylpentylamino) triphenylamine.
• antioxidants in particular of the family of 2,2'-methylenebis [4-alkyl (Ci-Cio) -6-alkyl (Ci-Cl 2 ) phenols, as described above. especially in the aforementioned application WO 99/02590.
• the term antioxidant may refer to both a single antioxidant compound or a mixture of several antioxidant compounds.
• the antioxidant is selected from the group consisting of substituted p-phenylenediamines, substituted diphenylamines, substituted triphenylamines, quinoline derivatives, and mixtures of such compounds; more preferably still, the antioxidant is selected from the group consisting of substituted p-phenylenediamines and mixtures of such diamines.
• composition according to the invention contains between 0.2 and 10 phr of chromium (III) acetylacetonate.
• said level of chromium acetylacetonate is preferably between 0.3 and 6 phr, more preferably within a range of 0.5 to 2.5 phr.
• the rubber compositions in accordance with the invention may also comprise all or part of the additives normally used in rubber compositions intended for the manufacture of pneumatic tires, such as, for example, plasticizers or extension oils, which these are of a kind aromatic or non-aromatic, especially very low or non-aromatic oils (eg, paraffinic oils, hydrogenated naphthenic oils, MES or TDAE oils), vegetable oils, plasticizers ethers, ester plasticizers (for example glycerol trioleates), fillers other than those mentioned above, for example lamellar fillers, hydrocarbon plasticizing resins having a high Tg, preferably greater than 30 ° C., as described for example in the applications WO 2005/087859, WO 2006/061064 and WO 2007 / 017060, and mixtures of such compounds, other anti-degradants or anti-aging agents such as For example, antiozonants, accelerators, vulcanization activators or retarders, anti-eversion agents such as for example sodium hexathio
• the rubber compositions of the invention may also contain coupling enhancers when a coupling agent is used, inorganic filler recovery agents when an inorganic filler is used, or more generally, bleaching agents. in a known manner, by improving the dispersion of the filler in the rubber matrix and by lowering the viscosity of the compositions, to improve their ability to implement in the green state.
• hydroxysilanes or hydrolysable silanes such as hydroxysilanes, alkylalkoxysilanes, in particular alkyltriethoxysilanes such as, for example, 1-octyl-tri-ethoxysilane, polyols (for example diols or triols), polyethers (for example polyethylene glycols), primary, secondary or tertiary amines (for example trialkanol amines); hydroxylated or hydrolysable polyorganosiloxanes (for example ⁇ , ⁇ -dihydroxy-poly-organosilanes (in particular ⁇ , ⁇ -dihydroxy-polydimethylsiloxanes).
• the composition of the invention in the case in particular where the composition of the invention is intended to constitute a calendering matrix of a metal reinforcement, the composition comprises, in association with the acetylacetonate compound described above, at at least one cobalt compound at a preferential content of between 0.1 and 10 phr, more preferably between 0.3 and 6 phr, in particular between 0.5 and 4 phr. It has been found that a certain synergy could indeed exist between the two compounds, which also results in an improvement of the adhesive performance under thermal and wet aging conditions.
• This cobalt compound is preferably an organic cobalt compound, chosen more preferentially from the group consisting of abietates, acetates, acetylacetonates, benzoates, butyrates, formates, linoleates, maleates, oleates, propionates, tallates, naphthenates, resinates, stearates, and the like. mixtures (i.e., salts, complexes, or other mixed derivatives) of such compounds, in particular among abietates, acetylacetonates, tallates, naphthenates, resinates and mixtures of such compounds. Acetylacetonates, tallates and cobalt naphthenates are preferred in the majority of cases.
• Metal reinforcement means any reinforcing element capable of reinforcing the rubber matrix, whether it is entirely metallic or not, of which at least the surface or outer part, intended to come into contact with the rubber, is metal.
• This reinforcement may be in various forms, preferably in the form of a unitary yarn (monofilament), a film (for example a strip or a ribbon) or an assembly of threads, that these threads are twisted together. (For example, in the form of a cable) or substantially parallel to each other (for example in the form of a packet of son, a continuous fiber or a set of short fibers).
• this reinforcement is more preferably in the form of a unitary yarn or an assembly of yarns, for example a cable or a strand manufactured with devices and methods of cabling or stranding known to those skilled in the art, which are not described here for the simplicity of the presentation.
• a reinforcement made of steel in particular carbon pearlitic (or ferritoclastic) steel known in the known manner as "carbon steel", or stainless steel as described, for example, in EP-A patent applications. -648 891 or WO98 / 41682. But it is of course possible to use other steels or other alloys.
• carbon steel When a carbon steel is used, its carbon content is preferably between 0.1% and 1.2%, especially between 0.5% and 1.1% (% by weight of steel); it is more preferably between 0.6% and 1.0%, such a content representing a good compromise between the mechanical properties required for the tire and the feasibility of the son.
• metal reinforcements as well as the cobalt salts that may be used for a preferential use have, for example, been described in more detail in the patent application WO 2005/113666.
• a particular embodiment consists in using a bismaleimide compound.
• This type of compound usable without hardener, has a cooking kinetics well adapted to that of tires, it is likely to activate the kinetics of adhesion and further improve, in the compositions according to the invention, the endurance in wet aging conditions of adhesive interphases.
• R is a substituted or unsubstituted hydrocarbon, aromatic or aliphatic, cyclic or acyclic radical, such radical may include a heteroatom selected from O, N and S; this radical R preferably comprises from 2 to 24 carbon atoms.
• a bismaleimide selected from the group consisting of N, N'-ethylene-bismaleimides, N, N'-hexamethylene-bismaleimides, N, N '- (m-phenylene) -bismaleimides, N, N' - ( p-phenylene) -bismaleimides, N, N '- (p-tolylene) -bismaleimides, N 5 N- (methylenedi-p-phenylene) -bismaleimides, N, N' - (oxydi-p-phenylene) -bismaleimides and mixtures of these compounds.
• Such bismaleimides are well known to those skilled in the art.
• a reinforcing resin or a bismaleimide is used, it is present in the composition of the invention at a preferred level of between 0.1 and 20%, more preferably between 1 and 8% by weight of rubber composition.
• a preferred level of between 0.1 and 20%, more preferably between 1 and 8% by weight of rubber composition For levels above the maximum values indicated, there is a risk of excessive stiffening of the compositions, and thus of embrittlement of the compositions; for rates below the indicated minima, the intended technical effect may be insufficient.
• compositions are manufactured in appropriate mixers, using two successive preparation phases well known to those skilled in the art: a first phase of work or thermomechanical mixing (so-called “non-productive” phase) at high temperature, up to a maximum of maximum temperature between 110 0 C and 190 0 C, preferably between 130 0 C and 180 0 C, followed by a second phase of mechanical work (so-called “productive” phase) to a lower temperature, typically less than 110 0 C, finishing phase during which is incorporated the crosslinking system.
• a first phase of work or thermomechanical mixing at high temperature, up to a maximum of maximum temperature between 110 0 C and 190 0 C, preferably between 130 0 C and 180 0 C
• a second phase of mechanical work so-called “productive” phase
• the nonproductive phase is conducted in a single thermomechanical step of a few minutes (for example between 2 and 10 min) during which is introduced, in a suitable mixer such as a conventional internal mixer, all the necessary basic constituents and other additives, with the exception of the crosslinking or vulcanization 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 30 0 C and 100 0 C), the vulcanization system. The whole is then mixed (productive phase) for a few minutes (for example between 5 and 15 min).
• a suitable mixer such as a conventional internal mixer
• an external mixer such as a roll mill
• chromium acetylacetonate is introduced during the non-productive phase, along with the antioxidant.
• the invention also applies to the case where all or only a fraction of this acetylacetonate is introduced during the productive phase.
• the final composition thus obtained can then be calendered, for example in the form of a sheet, a plate or extruded, for example to form a rubber profile used for the manufacture of a composite or a semi product. -fini, such as for example webs, tapes, underlays, other rubber blocks reinforced or not with metal reinforcements, intended to form for example a portion of the structure of a tire.
• the vulcanization (or firing) may then be carried out in a known manner at a temperature generally of between 130 ° C. and 200 ° C., preferably under pressure, for a sufficient time which may vary, for example, between 5 and 90 min, depending in particular on the firing temperature, the vulcanization system adopted and the vulcanization kinetics of the composition under consideration.
• the invention relates to rubber compositions and composites both in the so-called “raw” state (i.e., prior to firing) and in the so-called “fired” or vulcanized state (i.e. after vulcanization).
• the rubber composition of the invention described above can be used for the manufacture of any article or semi-finished product made of rubber, in particular in motor vehicle tires, whether this composition is external or internal with respect to the structure of the tire.
• external or “external” composition (or mixture) is meant here any rubber part of the tire which gives on the outside of the tire, in other words which is contact with air or a gas inflation; by way of preferred examples, mention may be made in particular of the tread, the sidewalls or the sealing layer of the tire.
• an inflation gas which is therefore located inside the tire structure itself; examples that may be mentioned include calender mixtures present in the bead zone, the carcass reinforcement or the crown reinforcement of the tire.
• the rubber composition of the invention is also usable for the manufacture of a metal / rubber composite, whether or not this composite is intended to be incorporated in a tire.
• This composite may be in various forms, for example in the form of a sheet, a strip, strip or a rubber block in which is incorporated the metal reinforcement, or a coating of rubber coating the metal reinforcement, the latter being in direct contact with the rubber composition.
• the final adhesion between the metal and the rubber composition can be obtained at the end of the firing of the finished article comprising the composite; preferably, this cooking is operated under pressure.
• the composites according to the invention are preferably intended for tires, in particular for radial tires to form all or part of the crown reinforcement, of the carcass reinforcement or the reinforcement of the bead zone of such tires.
• FIGURE very schematically represents a radial section of a tire 1 with a radial carcass reinforcement according to the invention, intended for example for a heavy-duty vehicle or a passenger vehicle in this representation.
• This tire 1 comprises a crown 2, two sidewalls 3, two beads 4, a carcass reinforcement 7 extending from one bead to the other.
• the top 2 surmounted by a tread (not shown in this schematic figure, for simplification), is in a manner known per se reinforced by a crown reinforcement 6 constituted for example by at least two superimposed crossed vertex plies (plies so-called "working" top), optionally covered with at least one protective ply or with a zero degree hooping crown ply.
• the carcass reinforcement 7 is wound around the two rods 5 in each bead 4, the upturn 8 of this armature 7 being for example disposed towards the outside of the tire 1 which is shown here mounted on its rim 9.
• the armature of carcass 7 consists of at least one ply reinforced by so-called "radial” cables, that is to say that these cables are arranged substantially parallel to each other and extend from one bead to the other of to form an angle between 80 ° and 90 ° with the median circumferential plane (plane perpendicular to the axis of rotation of the tire which is located halfway between the two beads 4 and passes through the middle of the crown reinforcement 6).
• this tire 1 also comprises, in a known manner, a rubber or elastomer layer 10, commonly known as a rubber or sealing layer, which defines the radially inner face of the tire and which is intended to protect the carcass ply from the diffusion air from the interior space to the tire.
• a rubber or elastomer layer commonly known as a rubber or sealing layer
• it may further comprise an intermediate reinforcing elastomer layer (not shown in the figure) which is located between the carcass ply and the sealing layer.
• the tire according to the invention has the essential feature of comprising in its structure at least one composition according to the invention.
• This composition in the case of a so-called interior composition, may for example be a part of the bead zone 4 comprising the bead wire 5, a cross-crown ply or a ply of protection of the crown reinforcement 6, a ply forming all or part of the carcass reinforcement 7.
• This composition in the case of a so-called external composition, may be present for example in the tread, in the sidewalls 3 or in the sealing layer 10 of the tire. .
• the rubber composition of the invention is advantageously usable as a calendering composition (thus as an internal mixture) in the crown reinforcement 6 of all types of pneumatic tires, for example for vehicles. , vans or heavy vehicles.
• the rubber composition of the invention has, in the vulcanized state (ie, after firing), an ElO modulus which is greater than 4 MPa, more preferably between 6 and 20 MPa, for example between 6 and 15 MPa.
• the rubber composition of the invention has, in the vulcanized state, an ElO modulus which is less than 9 MPa, more preferably between 4 and 9 MPa.
• Ci and C-2 Two rubber compositions (hereinafter Ci and C-2) were prepared, the formulation of which is given in Table 1, the rate of the different products being expressed in phr (parts by weight per cent). parts of total elastomer, here consisting of 100 phr of NR).
• the control composition (CI) essentially comprises, in addition to the elastomer and the reinforcing filler (carbon black), an antioxidant, zinc oxide, stearic acid, sulfur and a sulfenamide accelerator. reinforcing resin (phenolic resin plus methylene donor) and a cobalt salt as adhesion promoter with respect to a metal reinforcement (cobalt naphthenate, Fluka product at 10% by weight of cobalt metal equivalent) .
• These compositions are for example intended to constitute the calendering gum of a crown reinforcement of a tire.
• composition of the invention C-2 is distinguished only by the additional presence of 1.6 phr of chromium (III) acetylacetonate compound.
• the reinforcing filler (carbon black), the elastomer were successively introduced into an internal mixer, the initial vessel temperature of which was approximately 60 ° C. diene (NR), an antioxidant and optionally acetylacetonate, and the various other ingredients with the exception of the vulcanization system; the mixer was thus filled to about 70% (% by volume).
• Thermomechanical work non-productive phase
• the mixture thus obtained was recovered, cooled, and sulfur and a sulfenamide type accelerator were incorporated on an external mixer (homoformer) at 30 ° C., mixing the whole (productive phase) for a few minutes.
• compositions thus obtained are then either calendered in the form of plates (thickness of 2 to 3 mm) for the measurement of their physical or mechanical properties on the one hand, for the conduct of aging tests on the other hand.
• composition C-2 The mechanical properties of these compositions have been reported in the attached Table 2. It is noted that the two compositions have almost equivalent properties, apart from an elongation at break advantageously higher in the presence of chromium acetylacetonate (composition C-2 according to the invention).
• the rubber blocks After baking the compositions (25 min at 150 ° C.), the rubber blocks are placed in an oven at a temperature of 55 ° C., under a relative humidity of 60%, for one to several weeks, in order to compare the kinetics reducing the antioxidant levels of the compositions during this accelerated aging.
• the antioxidant level was measured by a known technique of HPLC (high performance liquid chromatography), firstly in the initial state on unaged samples, that is to say directly at the baking outlet, and secondly after aging from one to six weeks.
• the results obtained are reported in the attached Table 3.
• the level of antioxidant in the compositions is expressed in relative units, with the base 100 being selected for the control composition in the initial state (i.e., after baking out).
• HMT hexamethylenetetramine - Degussa company

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