Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
  • C08G77/04—Polysiloxanes
  • C08G77/38—Polysiloxanes modified by chemical after-treatment
  • C08G77/382—Polysiloxanes modified by chemical after-treatment containing atoms other than carbon, hydrogen, oxygen or silicon
  • C08G77/392—Polysiloxanes modified by chemical after-treatment containing atoms other than carbon, hydrogen, oxygen or silicon containing sulfur
• • 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
• • 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
  • C08K5/54—Silicon-containing compounds
  • C08K5/548—Silicon-containing compounds containing sulfur
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L21/00—Compositions of unspecified rubbers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L83/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon only; Compositions of derivatives of such polymers
  • C08L83/04—Polysiloxanes

Definitions

• the present invention relates to diene elastomer compositions reinforced with an inorganic filler, intended in particular for the manufacture of tires or semi-finished products for tires, in particular the treads of these tires.
• POS polyorganosiloxane type
• a coupling agent also called a bonding agent, which has the function of ensuring the connection or bonding between the surface of the particles of inorganic filler and the elastomer, while facilitating the dispersion of this morganic load within the elastomeric matrix.
• Coupling agents in particular (silica / diene elastomer), have been described in a very large number of documents, the best known being bifunctional alkoxysilanes. It was first proposed (see for example application FR-A-2 094 859) to use mercaptosilane coupling agents for the manufacture of tire treads. It was quickly revealed and it is now well known that mercaptosilanes are capable of providing excellent coupling properties but that the industrial use of these coupling agents is not possible due to the high reactivity of the -SH functions leading very rapidly, during the preparation of the rubber composition in an internal mixer, to premature vulcanizations also called "scorching", to very high Mooney plasticities, finally to rubber compositions almost impossible to work and implement industrially.
• TESPT bis- (trialkoxylsilylpropyl) polysulphides, very particularly bis 3-triethoxysilylpropyl tetrasulphide (abbreviated to "TESPT”), of formula [(C 2 H 5 ⁇ ) 3 Si (CH 2 ) 3 S 2 ] 2 , sold in particular by the company Degussa under the name "Si69".
• This TESPT polysulphurized alkoxysilane is today the benchmark coupling agent, for those skilled in the art, in tires loaded with low rolling resistance silica, sometimes qualified as “Green Tires” for the energy savings offered (or “energy-saving Green Tires”), offering an excellent industrial compromise in terms of safety in roasting, hysteresis and reinforcing power.
• compositions based on a reinforcing morganic filler such as silica and TESPT, however, have the known drawback of exhibiting very significantly slowed down vulcanization kinetics, as a general factor of two to three, compared with compositions loaded with black. of carbon.
• This MESPT coupling agent in addition to the fact that it makes it possible to very significantly reduce the cooking times of the rubber compositions comprising it, is also advantageous from the point of view of the environment because of a number of functions. reduced ethoxy (only one ethoxy function instead of three, per silicon atom) and consequently a lesser release of ethanol during the processing of the rubber compositions. Thanks to the use of this coupling agent, the problem of VOCs ("Volatile Organic Compounds”) is certainly greatly reduced, but it is not completely resolved.
• VOCs Volatile Organic Compounds
• the Applicants have discovered during their research that a specific coupling agent, of another nature than an alkoxysilane, not only makes it possible, as for the MESPT above, to reduce the cooking times very significantly. , at a level equivalent to that observed on compositions loaded with carbon black, but still to completely solve the problem of emission of VOCs (ethanol) mentioned above.
• a first subject of the invention relates to an elastomeric composition which can be used for the manufacture of tires, based on at least (i) a diene elastomer, (ii) an inorganic filler as a reinforcing filler, (iii) a coupling agent (inorganic filler / diene elastomer), characterized in that this coupling agent is a linear ⁇ , ⁇ -dihydroxy-polyorganosiloxane oligomer comprising from 2 to 15 silicon atoms, and, along its chain, at least one silicon atom carrying a sulfur functional group (function denoted "F"), of formula (I):
• group G represents SH or an episulphide radical and R 1 represents a divalent linking group.
• a subject of the invention is also the use of a rubber composition in accordance with the invention for the manufacture of tires or for the manufacture of semi-finished products intended for such tires, these semi-finished products being chosen in particular in the group formed by the treads, the sub-layers intended for example to be placed under these treads, the crown plies, the sides, the carcass plies, the heels, the protectors, the air chambers or the gums waterproof interior for tubeless tires.
• the subject of the invention is also these tires and these semi-finished products themselves, when they comprise a rubber composition in accordance with the invention.
• the invention relates in particular to tire treads, these treads being able to be used during the manufacture of new tires or for retreading used tires; thanks to the compositions of the invention, these treads have both a low rolling resistance and a high resistance to wear.
• the composition in accordance with the invention is particularly suitable for the manufacture of tires or tire treads intended for equipping passenger vehicles, vans, 4x4 vehicles (with 4-wheel drive), two wheels, "Heavy vehicles” (i.e. metro, bus, road transport equipment (trucks, tractors, trailers), off-road vehicles), airplanes, civil engineering, agricultural, or handling equipment, treads conforming to the invention can be used during the manufacture of new tires or for retreading used tires.
• Reduced cooking times are particularly advantageous for treads intended for retreading, whether it is "cold” retreading (use of a precooked tread) or conventional "hot” retreading (use of 'a raw tread).
• a reduced cooking time in addition to reducing production costs, limits the overcooking (or postcooking) imposed on the rest of the casing (carcass) of the used tire (already vulcanized); thanks to the invention, with identical baking time, the treads can also be baked at a lower temperature, which is another means of preserving the carcass from the problem of overcooking mentioned above.
• the invention also relates to a process for obtaining a rubber composition with improved vulcanization kinetics, usable for the manufacture of tires, in which at least one diene elastomer is incorporated, at least one reinforcing inorganic filler and one coupling agent ensuring the connection between the reinforcing inorganic filler and the elastomer, this method being characterized in that said coupling agent consists of a POS oligomer as above, and in that the whole is thermomechanically kneaded, by one or more steps, until reaching a maximum temperature between 110 ° C and 190 ° C.
• the invention also relates to the use as coupling agent (inorganic charge / diene elastomer), in a rubber composition comprising a diene elastomer and reinforced with an inorganic charge, of such a POS oligomer.
• coupling agent inorganic charge / diene elastomer
• the rubber compositions are characterized before and after curing, as indicated below. 1-1. rheometry:
• T 0 is the induction time, that is to say the time necessary for the start of the vulcanization reaction
• T ⁇ (for example T 99 ) is the time necessary to reach a conversion of%, that is to say% (for example 99%) of the difference between the minimum and maximum couples.
• T 9 -T 0 is therefore practically the measurement of the cooking time from the minimum torque.
• a processing of the traction records also makes it possible to trace the module curve as a function of the elongation (see attached figure), the module used here being the true secant module measured in first elongation, calculated by reducing to the real section of the 'test tube and not in the initial section as previously for the nominal modules.
• the dynamic properties ⁇ G * and tan max ( ⁇ ) are measured on a viscoanalyzer (Metravib VA4000), according to standard ASTM D 5992-96.
• the response of a sample of vulcanized composition is recorded (cylindrical specimen 4 mm thick and 400 mm 2 in section), subjected to a sinusoidal stress in alternating single shear, at the frequency of 10 Hz, under normal conditions of temperature (23 ° C) according to standard ASTM D 1349-99.
• a deformation amplitude sweep is carried out from 0.1 to 50% (outward cycle), then from 50%> to 1% (return cycle).
• the exploited results are the complex dynamic shear modulus (G *) and the loss factor tan ⁇ .
• the rubber compositions according to the invention are based on at least each of the following constituents: (i) one (at least one) diene elastomer, (ii) one (at least one) inorganic filler as reinforcing filler, and (iii) one (at least one) specific POS oligomer, as defined below, as coupling agent (inorganic filler / diene elastomer).
• composition based on
• a composition comprising the mixture and / or the in situ reaction product of the various constituents used, some of these base constituents being capable of, or intended to react between them, at least in part, during the various phases of manufacturing the composition, in particular during its vulcanization.
• iene elastomer or rubber in known manner an elastomer derived at least in part (i.e. a homopolymer or a copolymer) from diene monomers (monomers carrying two carbon-carbon double bonds, conjugated or not).
• diene elastomer a diene elastomer derived at least in part from conjugated diene monomers, having a rate 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 of the EPDM type do not enter into the preceding definition and can be qualified in particular as "essentially saturated diene elastomers". "(rate of motifs of diene origin low or very low, always less than 15%).
• the expression “highly unsaturated” diene elastomer is understood in particular to mean a diene elastomer having a content of units of diene origin (conjugated dienes) which is greater than 50%.
• 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-di (C 1 -C 5 alkyl) -1,3-butadienes are suitable.
• Suitable vinyl-aromatic compounds are, for example, styrene, ortho-, meta-, para-methylstyrene, the commercial "vinyl-toluene" mixture, para-tertiobutylstyrene, methoxystyrenes, chlorostyrenes, vinyl mesitylene, divinylbenzene. , vinylnaphthalene.
• the copolymers can 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 quantities of modifying and / or randomizing agent used.
• the elastomers can for example be block, statistical, sequence, microsequenced, and be prepared in dispersion or in solution; they can be coupled and / or star or functionalized with a coupling and / or star-forming or functionalizing agent.
• polybutadienes are suitable and in particular those having a content of -1,2 units (between 4% and 80%) or those having a cis-1,4 content greater than 80%, polyisoprenes, butadiene copolymers -styrene and in particular those having a styrene content of between 5% and 50%> by weight and more particularly between 20%) and 40%, a content of -1,2 bonds in the butadiene part of between 4%> and 65%>, a content of trans-1,4 bonds of between 20% and 80% > , butadiene-isoprene copolymers and in particular those having an isoprene content of between 5% and 90% by weight and a transition temperature vitreous (Tg, measured according to standard ASTM D3418-82) from -40 ° C to -80 ° C, isoprene-styrene copolymers and in particular those having a styrene content of between 5% and 50% by weight
• butadiene-styrene-isoprene copolymers are particularly 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 of units - 1.2 of the butadiene part between 4% and 85%, a content of trans units -1.4 of the part butadiene between 6% and 80%), a content of -1.2 units plus -3.4 of the isoprene part between 5%> and 70% and a content of trans units -1.4 of the isoprene part included between 10%> and 50%), and more generally any butadiene-styrene-isoprene copolymer having a Tg of between -20 ° C. and -70 ° C.
• the diene elastomer of the composition in accordance with the invention is chosen from the group of highly unsaturated diene elastomers constituted by polybutadienes (BR), polyisoprenes (IR), natural rubber (NR) , butadiene copolymers, isoprene copolymers and mixtures of these elastomers.
• BR polybutadienes
• IR polyisoprenes
• NR natural rubber
• butadiene copolymers butadiene copolymers
• isoprene copolymers and mixtures of these elastomers.
• Such copolymers are more preferably chosen from the group consisting of butadiene-styrene copolymers (SBR), isoprene-butadiene copolymers (BIR), isoprene-styrene copolymers (SIR) and isoprene copolymers- butadiene-styrene (SBIR).
• SBR butadiene-styrene copolymers
• BIR isoprene-butadiene copolymers
• SIR isoprene-styrene copolymers
• SBIR isoprene copolymers- butadiene-styrene
• composition according to the invention is particularly intended for a tread for a tire, whether it is a new or used tire (in the case of retreading).
• the diene elastomer is for example an SBR, whether it is an SBR prepared in emulsion ("ESBR") or an SBR prepared in solution (“SSBR "), or a cut (mix) SBR / BR, SBR NR (or SBR / IR), or even BR / NR (or BR / IR).
• SBR elastomer use is in particular of an SBR having a styrene content of between 20% and 30%> by weight, a content of vinyl bonds in the butadiene part of between 15% and 65%, a content of trans-1,4 bonds between 15%) and 75% and a Tg between -20 ° C and -55 ° C.
• Such an SBR copolymer, preferably prepared in solution (SSBR) is optionally used in admixture with a polybutadiene (BR) preferably having more than 90%> of cis-1,4 bonds.
• the diene elastomer is in particular an isoprene elastomer;
• Isoprene elastomer means in a known manner an isoprene homopolymer or copolymer, 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.
• isoprene copolymers examples include isobutene-isoprene (butyl rubber - IIR), isoprene-styrene (SIR), isoprene-butadiene (BIR) or isoprene-butadiene-styrene copolymers (SBIR).
• This isoprene elastomer is preferably natural rubber or a synthetic cis-1,4 polyisoprene; among these synthetic polyisoprenes, polyisoprenes are preferably used having a rate (mol%) of cis-1,4 bonds greater than 90%>, more preferably still greater than 98%.
• the diene elastomer may also consist, in whole or in part, of another highly unsaturated elastomer such as, for example, an SBR elastomer.
• the composition according to the invention may contain at least one essentially saturated diene elastomer, in particular at least one EPDM copolymer, which this copolymer is for example used or not in admixture with one or more of the highly unsaturated diene elastomers mentioned above.
• the compositions of the invention may contain a single diene elastomer or a mixture of several diene elastomers, the diene elastomer or elastomers being able to be used in combination with any type of synthetic elastomer other than diene, or even with polymers other than elastomers, for example thermoplastic polymers.
• the white or inorganic filler used as reinforcing filler can constitute all or only part of the total reinforcing filler, in the latter case associated for example with carbon black.
• the reinforcing inorganic filler constitutes the majority, that is to say more than 50% by weight of the total reinforcing filler, more preferably more than 80% by weight of this total reinforcing load.
• the term "reinforcing morganic filler” means, in a known manner, an inorganic or mineral filler, whatever its color and its origin (natural or synthetic), also called “white” filler or sometimes “clear” filler "In contrast to carbon black, this inorganic filler being capable of reinforcing on its own, without other means than an intermediate coupling agent, a rubber composition intended for the manufacture of tires, in other words capable of replacing, in its reinforcing function, a conventional charge of pneumatic grade carbon black.
• the reinforcing inorganic filler is an inorganic filler of the silica (SiO 2 ) or alumina (Al 2 O 3 ) type, or a mixture of these two fillers.
• the silica used can be any reinforcing silica known to those skilled in the art, in particular any precipitated or pyrogenic silica having a BET surface as well as a CTAB specific surface, both less than 450 m 2 / g, preferably from 30 to 400 m 2 / g.
• Highly dispersible precipitated silicas (called "HDS") are preferred, in particular when the invention is implemented for the manufacture of tires having a low rolling resistance; the term “highly dispersible silica” is understood to mean, in known manner, any silica having a significant ability to disaggregate and to disperse in an elastomeric matrix, observable in known manner by electron or optical microscopy, on fine sections.
• Nonlimiting examples of such preferential highly dispersible silicas mention may be made of Perkasil KS 430 silica from the company A zo, the BV3380 silica from the company Degussa, the Zeosil 1165 MP and 1115 MP silicas from the company Rliodia, the silica Hi- Sil 2000 from the company PPG, the Zeopol 8741 or 8745 silicas from the Huber company, treated precipitated silicas such as for example the silicas "doped" with aluminum described in application EP-A-0 735 088.
• the reinforcing alumina preferably used is a highly dispersible alumina having a BET surface area ranging from 30 to 400 m 2 / g, more preferably between 60 and 250 m 2 / g, a average particle size at most equal to 500 nm, more preferably at most equal to 200 nm, as described in the above-mentioned application EP-A-0 810 258.
• BET surface area ranging from 30 to 400 m 2 / g, more preferably between 60 and 250 m 2 / g, a average particle size at most equal to 500 nm, more preferably at most equal to 200 nm, as described in the above-mentioned application EP-A-0 810 258.
• Such reinforcing aluminas mention may be made in particular of "Baikalox""A125",”CR125”,”D65CR” aluminas from the company Baikowski.
• reinforcing inorganic filler is also understood to mean mixtures of various reinforcing inorganic fillers, in particular of highly dispersible silicas and / or aluminas as described above.
• the reinforcing inorganic filler used in particular if it is silica, preferably has a BET surface area of between 60 and 250 m 2 / g , more preferably between 80 and 200 m 2 / g.
• the reinforcing inorganic filler can also be used in cutting (mixing) with carbon black.
• carbon blacks all carbon blacks are suitable, in particular blacks of the HAF, ISAF, SAF type, conventionally used in tires and particularly in tire treads.
• the quantity of carbon black present in the total reinforcing filler can vary within wide limits, this quantity of carbon black being preferably less than the quantity of inorganic reinforcing filler present in the rubber composition.
• compositions in accordance with the invention in particular in the treads incorporating such compositions, it is preferred to use, in small proportion, a carbon black in association with the reinforcing inorganic filler, at a preferential rate of between 2 and 20 phr (parts by weight per hundred parts of elastomer), more preferably comprised within a range of 5 to 15 phr.
• a carbon black in association with the reinforcing inorganic filler, at a preferential rate of between 2 and 20 phr (parts by weight per hundred parts of elastomer), more preferably comprised within a range of 5 to 15 phr.
• the rate of total reinforcing filler is between 10 and 200 phr, more preferably between 20 and 150 phr, the optimum being different depending on the intended applications; in fact, the level of reinforcement expected on a bicycle tire, for example, is in known manner significantly lower than that required on a tire capable of traveling at high speed in a sustained manner, for example a motorcycle tire, a tire for a passenger vehicle or for a utility vehicle such as Truck.
• the quantity of reinforcing inorganic filler is preferably between 30 and 140 phr, more preferably within a range of 50 to 120 pce.
• the BET specific surface is determined in a known manner by gas adsorption using the Brunauer-Emmett-Teller method described in "The Journal of the American Chemical Society” Vol. 60, page 309, February 1938, more precisely according to French standard NF ISO 9277 of December 1996 [multi-point volumetric method (5 points) - gas: nitrogen - degassing: hour at 160 ° C - relative pressure range p / in: 0.05 at 0.17].
• the CTAB specific surface is the external surface determined according to French standard NF T 45-007 of November 1987 (method B).
• a reinforcing organic filler could be used, in particular a carbon black, covered at least in part with an inorganic layer. , for example silica, requiring the use of a coupling agent to establish the connection with the elastomer.
• coupling agent inorganic filler / elastomer
• organic filler / elastomer an agent capable of establishing a sufficient bond, of chemical and / or physical nature, between the inorganic filler and the diene elastomer ;
• a coupling agent at least bifunctional, has for example as a very simplified general formula "Y-A-F", in which:
• Y represents a functional group ("Y" function) capable of physically and / or chemically binding to the inorganic charge, such a bond being able to be established for example between a silicon atom of the coupling agent and the hydroxyl groups on the surface inorganic filler (for example surface silanols when it is silica);
• F represents a functional group ("F" function) capable of binding physically and / or chemically to the diene elastomer, for example via a sulfur atom; - A represents a divalent group making it possible to connect Y and F.
• Coupling agents should in particular not be confused with simple agents for recovering the inorganic charge which, in known manner, may comprise the "Y" function active with respect to the inorganic charge but are devoid of the function "F” activates with respect to the diene elastomer.
• the coupling agent used in the compositions of the invention is a linear ⁇ , ⁇ - dihydroxy-polyorganosiloxane oligomer comprising from 2 to 15 silicon atoms, and, along its chain, at least one silicon atom carrying a pendant functional sulfur group (function "F"), having the formula (I): - R 1 - G
• G represents SH or an episulfide radical (or epithio) and R 1 represents a divalent linking group.
• ⁇ ⁇ -dihydroxy-polyorganosiloxane
• POS POS of which the majority (that is to say more than 50 mol%) of the silicon atoms of the ends (positions called " ⁇ , ⁇ ") of the polysiloxane chain carry a hydroxyl function (OH).
• this POS oligomer verifies at least one, preferably the following two characteristics:
• OH hydroxyl
• the group R 1 linking G and the silicon atom carrying the function F is preferably chosen from alkylene groups, linear or branched, comprising from 1 to 20 carbon atoms, these groups being able to be interrupted by hydrocarbon groups of a other nature, for example by cycloalkylene or arylene groups.
• R 1 is chosen from the following groups:
• alkylene- (poly) cycloalkylene-alkylene groups denoted r 2 of which the alkylene parts, linear or branched, have 1 to 20 carbon atoms, and the cyclic part comprises from 5 to
• alkylene-phenylene-alkylene groups denoted r 3 in which the alkylene parts, linear or branched, have from 1 to 20 carbon atoms;
• r ! , r 2 and r 3 comprise at least one heteroatom, for example an oxygen atom.
• POS oligomers which can be used in the compositions of the invention are for example POSs of average formula (II) which follows: R ⁇ 1
• R ' mainly represent hydrogen, a minority of them (that is to say less than 50%, preferably less than 40% in moles, more preferably still less than 20%) which can, depending on the specific conditions of synthesis of the oligomer, represent a Ci -C 15 alkyl, preferably C ⁇ -C in 6;
• R which are identical or different, each represent a monovalent hydrocarbon group chosen from linear or branched alkyls having from 1 to 6 carbon atoms;
• - (x + y + z) representing the total number of silicon atoms is in a range from 2 to 15, preferably from 2 to 10, more preferably still from 2 to 7;
• - x is equal to or different from zero, preferably different from zero;
• R may be identical or different within the same siloxyl unit (when several of them are present on this same unit), or identical or different from one siloxyl motif to another.
• R are preferably chosen from methyl, ethyl, propyl and butyl; more preferably, R is methyl.
• R 3 is chosen from the groups r 1 and r 2 defined above, or
• n is an integer ranging from 4 to 7
• R 3 is chosen from alkylene r 1 .
• the group G (thiol or episulphide) of the function F is carried by a carbon of aliphatic or cycloaliphatic nature, with the possibility that an adjacent carbon of aliphatic or cycloaliphatic nature is substituted by OH or by SH.
• - n is an integer ranging from 1 to 12, preferably equal to 1, 2 or 3 (for formulas (3), (4), (5), (9), (10) and (11));
• R 4 , R 5 and R 6 identical or different, represent H or a monovalent hydrocarbon radical, preferably chosen from linear or branched alkyls having from 1 to 6 carbon atoms, more preferably from methyl, ethyl, propyl and butyl .
• radicals of the r 1 , r 2 or r 3 type comprising one or more double bonds located in the alkylene part and / or, if it is r 2 or r 3 , in the ring;
• These pF groups can be converted into F groups by an appropriate sulfurization reaction.
• the reaction can be more or less complete, so that z can be different from zero.
• This sulfurization reaction can in particular be carried out in the presence of H 2 S when the pF group is of the (D1) unsaturation or (D2) epoxide type or when it is a group episulphide "assimilated pF".
• the sulfurization employs an appropriate sulfurization agent such as H 2 S, Na 2 S 4 , NaSH, thiourea.
• the preferential groups F previously mentioned can be obtained by sulfurization of the preferential precursor groups (pF) which follow:
• the episulfide groups are potentially precursors (called in the present application "assimilated pF") for other groups F, during a sulfurization reaction.
• group (13) is a precursor of group (8)
• the group (12) is a precursor of the group (7).
• z is different from 0, the two types of groups, e.g. (13) and (8), respectively 12) and (7) are present on the molecule.
• the particularly preferred oligomers of formula (II) are those in which all of the groups R are methyl groups.
• POS oligomers having the following average formula (IV):
• POS oligomers previously described can be prepared by methods involving in particular:
• the hydrolysis and condensation product is then subjected to sulphurization with H 2 S, eg according to WO-A-9902580 when the pF group is of type (Dl ) unsaturated, according to US-A-4,163,832 when the pF group is an episulphide assimilated group and according to US-A-4,281,202 when the pF group is of (D2) epoxy type.
• the sulfurization can be carried out according to the technique described in EP-A-997 489 in the presence of Na 2 S 4 or NaSH, or of FR-A-2 055 229 and FR-A-1 356 552 in the presence of thiourea and NH or sodium alcoholate; one can also operate as described in US-A-5,107,009 in the presence of NaSH, or in FR-A-2,294,171 in the presence of H 2 S and NH
• pF being of type (Dl) or (D3)
• X being a halogen atom, preferably Cl, operating optionally in the presence of halosilanes of formula (IX):
• POS oligomers described above have been found to be sufficiently effective on their own for coupling a diene elastomer and a reinforcing inorganic filler such as silica. Without this being limiting, they may advantageously constitute the sole coupling agent present in the rubber compositions of the invention.
• the POS oligomer content is preferably greater than 0.5 pci, more preferably greater than 1 pci and less than 15 pci. Below the minima indicated, the effect is likely to be insufficient, while beyond the maximum rate indicated, there is generally no longer any improvement in the coupling, while the costs of the composition increase. For these reasons, this POS oligomer content is more preferably between 2 and 10 pci.
• POS oligomers described above could be grafted beforehand on the reinforcing inorganic fillers, in particular on silica, via their Y function, the fillers thus precoupled can then be linked to the elastomer through their free type F function.
• the rubber compositions in accordance with the invention also comprise all or part of the additives usually used in diene rubber compositions intended for the manufacture of tires, such as for example plasticizers, extension oils, protective agents.
• additives usually used in diene rubber compositions intended for the manufacture of tires such as for example plasticizers, extension oils, protective agents.
• protective agents such as anti-ozone waxes, anti-ozone chemicals, anti-oxidants, anti-fatigue agents, adhesion promoters, coupling activators as described for example in the aforementioned applications WO00 / 05300 and WO00 / 05301, resins reinforcing agents as described in WO02 / 10269, a crosslinking system based either on sulfur or on sulfur and / or peroxide and / or bismaleimide donors, vulcanization accelerators, vulcanization activators, etc.
• a reinforcing inorganic filler can also be associated, if necessary, with a conventional white filler that is not very reinforcing or not, for example particles of clays, bentonite, talc, chalk, kaolin.
• the rubber compositions in accordance with the invention may also contain, in addition to the POS oligomers described above, agents for covering the reinforcing inorganic filler, comprising for example the only function Y, or more generally agents for assisting in setting implemented in known manner, thanks to an improvement in the dispersion of the inorganic filler in the rubber matrix and to a lowering of the viscosity of the compositions, of improving their ability to be used in the raw state, these agents being chosen from the preferred group consisting of hydrolyzable silanes such as alkylalkoxysilanes (in particular alkyltriethoxysilanes), polyols, polyethers (for example polyethylene glycols), primary, secondary or tertiary amines (for example trialcan
• ra a value sufficient to give the oil a dynamic viscosity at 25 ° C of between 5 and 1000 mPa.s, preferably between 10 and 200 mPa.s; and the organic radicals R 9 , because of their availability in industrial products, are generally methyl, ethyl, propyl and / or phenyl radicals, preferably at least 80% by number of these radicals R 9 being methyl radicals.
• polyalkylene glycols As preferred examples of polyalkylene glycols, mention will be made in particular of those of formula:
• radicals R 10 identical or different from each other, each represent an alkylene radical, linear or branched, having from 1 to 4 carbon atoms.
• hydrolyzable silanes By way of preferred examples of hydrolyzable silanes, mention will be made in particular of those of formula: (R n ) t Si (E) 4-t
• the symbols R 11 each represent a linear or branched C ⁇ -C 8 alkyl (such as for example methyl, ethyl, propyls, butyls), a Cs-C 8 cycloalkyl (such as for example cyclohexyl), a C 6 -C ⁇ aryl or aralkyl having a C 6 -C ⁇ 2 aryl part and a C] -C alkyl part (such as, for example, phenyl, xylyl, benzyl, phenylethyl);
• the symbols E are hydrolyzable groups and each represent a C 1 -C 10 alkoxy group (such as, for example, methoxy, ethoxy, octyloxy), a C 6 -C 1 aryloxy group (such as, for example, phenyloxy), a C 1 -C C alkoxy group 13 (such as, for example, acetoxy), a
• an inorganic charge recovery agent in particular an ⁇ , ⁇ - dihydroxy-POS, it is preferably used at a rate of 0.1 to 10 parts by weight, more preferably from 0.5 to 5 parts, per 100 parts of reinforcing inorganic filler, the total amount of POS oligomer and of covering agent advantageously representing less than 10%, more preferably less than 8% by weight relative to the quantity of reinforcing inorganic filler.
• compositions are produced in suitable mixers, using two successive preparation phases well known to those skilled in the art: a first working or thermo-mechanical kneading phase (sometimes called a "non-productive" phase) at high temperature, up to a maximum temperature (noted T max ) of between 110 ° C and 190 ° C, preferably between 130 ° C and 180 ° C, followed by a second phase of mechanical work (sometimes referred to as the "productive" phase) at a lower temperature, typically less than 110 ° C, for example between 60 ° C and 100 ° C, finishing phase during which the crosslinking or vulcanization system is incorporated; such phases have been described for example in the aforementioned documents EP 501227, EP 735088, WO00 / 05300, WO00 / 05301 or WO02 / 083782.
• the manufacturing method according to the invention is characterized in that at least the reinforcing inorganic filler and the POS oligomer are incorporated by kneading with the diene elastomer during the first so-called non-productive phase, that is to say -to say that one introduces into the mixer and that one thermomechanically kneads, in one or more steps, at least these different basic constituents until reaching a maximum temperature between 110 ° C and 190 ° C, preferably between 130 ° C and 180 ° C.
• the first (non-productive) phase is carried out in a single thermomechanical step during which all the necessary basic constituents are introduced into a suitable mixer such as a conventional internal mixer. (diene elastomer, reinforcing inorganic filler and coupling agent), then in a second step, for example after one to two minutes of kneading, any additional covering or processing agents and other various additives, with the exception of vulcanization system; when the apparent density of the reinforcing inorganic filler is weak (general case of silicas), it may be advantageous to split its introduction into two or more parts.
• a suitable mixer such as a conventional internal mixer.
• thermomechanical working step can be added to this internal mixer, after the mixture has fallen and intermediate cooling (cooling temperature preferably less than 100 ° C.), in order to subject the compositions to a complementary thermomechanical treatment, in particular to improve still the dispersion, in the elastomeric matrix, of the reinforcing inorganic filler and of its coupling agent.
• the total duration of the kneading, in this non-productive phase is preferably between 2 and 10 minutes.
• the vulcanization system is then incorporated at low temperature, generally in an external mixer such as a cylinder mixer; the whole is then mixed (productive phase) for a few minutes, for example between 5 and 15 minutes.
• the final composition thus obtained is then calendered, for example in the form of a sheet, a plate or even extradited, for example to form a rubber profile used for the manufacture of semi-finished products such as treads, crown reinforcement plies, sidewalls, carcass reinforcement plies, heels, protectors, air chambers or waterproof inner liners for tubeless tires.
• Vulcanization (or baking) is carried out in a known manner at a temperature generally between 130 ° C and 200 ° C, preferably under pressure, for a sufficient time which can vary for example between 5 and 90 min depending in particular on the temperature curing, the vulcanization system adopted, the vulcanization kinetics of the composition considered or of the size of the tire.
• the vulcanization system proper is preferably based on sulfur and a primary vulcanization accelerator, in particular an accelerator of the sulfenamide type.
• a primary vulcanization accelerator in particular an accelerator of the sulfenamide type.
• various known secondary accelerators or vulcanization activators such as zinc oxide, stearic acid, guanidine derivatives (especially diphenylguanidine), etc.
• Sulfur is used at a preferential rate of between 0.5 and 10 phr, more preferably of between 0.5 and 5.0 phr, for example between 0.5 and 3.0 phr when the invention is applied to a strip. tire bearing.
• the primary vulcanization accelerator 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.
• the invention relates to the rubber compositions previously described both in the so-called “raw” state (ie, before curing) and in the so-called “cooked” or vulcanized state (ie, after crosslinking or vulcanization).
• the compositions according to the invention can be used alone or as a blend (ie, as a mixture) with any other rubber composition which can be used for the manufacture of tires.
• This step was carried out without catalysis and by direct hydrolysis of the mixture of silanes, using the following reagents:
• Me 2 SiOEt 157.9 g (or 1066.9 mmol); demineralized water: 947.33 g (i.e. 52.6 moles; 22.13 eq. / silanes).
• the ethanol formed during the reaction is removed by azeotropic entrainment with cyclohexane.
• Silanes and 636.91 g of water are introduced into a 3-liter flask equipped with a temperature probe and mechanical stirring. 1 liter of cyclohexane is added to the medium, which makes the system biphasic. The reaction medium is stirred and heated at 70 ° C for 3 hours. The temperature of the reaction medium rose to 100 ° C. and the heating was continued for 3 h 30 min.
• the transformation rate of unsaturations is 86%> molar. No sulfides are observed to the accuracy of the 1 H NMR detection.
• a diene elastomer (or mixture of diene elastomers) is introduced into an internal mixer, filled to 70% and whose initial tank temperature is approximately 90 ° C. , if applicable), the reinforcing filler, the coupling agent, then, after one to two minutes of kneading, the various other ingredients with the exception of the vulcanization system.
• Thermomechanical work is then carried out (non-productive phase) in two stages (total mixing time equal to approximately 7 min), until a maximum "fall" temperature of approximately 165 ° C is reached.
• the mixture thus obtained is recovered, cooled, and then the vulcanization system (sulfur and accelerator) is added.
• sulfenamide on an external mixer (homo-finisher) at 30 ° C, mixing everything (productive phase) for 3 to 4 minutes.
• compositions thus obtained are then calendered either in the form of plates (thickness of 2 to 3 mm) or of thin sheets of rubber for the measurement of their physical or mechanical properties, or in the form of profiles which can be used directly, after cutting and / or assembly to the desired dimensions, for example as semi-finished products for tires, in particular as tire treads.
• the diene elastomer is an SBR / BR blend and the reinforcing inorganic filler (HDS silica) is used at a preferential rate comprised within a range of 40 to 120 phr.
• the reinforcing inorganic filler HDS silica
• the purpose of this test is to demonstrate the improved coupling performance (inorganic filler / diene elastomer) provided by the POS oligomer, compared to the conventional TESPT coupling agent.
• compositions are prepared for this based on a SSBR / BR blend reinforced with silica, denoted C-1 and C-2, these two compositions differing essentially in the nature of the coupling agent used:
• composition C-1 conventional TESPT silane
• Composition C-2 POS oligomer of formula (XV).
• the diene elastomer is an elastomer known to a person skilled in the art: SSBR comprising 25%) by mass of styrene, the polybutadiene units present being 58% of the polybutadiene-1,2 units and 23% of the polybutadiene-1 units, 4 trans, said SSBR being used in admixture with a polybutadiene having a high rate of cis 1-4 bonds.
• the two coupling agents are used at an isomolar silicon content, that is to say that whatever the composition is used, the same number of moles of functions Y reactive with respect to silica and of its surface hydroxyl groups.
• the POS oligomer is associated a small amount of covering agent (1 pce) of the inorganic load (aid for implementation); it should be noted that the total quantity (POS coupling agent + POS covering agent) - ie 5 phr - advantageously remains lower than that of the conventional coupling agent TESPT alone (6.4 phr) in the control composition C- 1.
• the level of coupling agent and covering agent, in the composition of the invention C-2 represents less than 10% by weight relative to the amount of reinforcing inorganic filler .
• Tables 1 and 2 give the formulation of the different compositions (Table 1 - rate of the different products expressed in pce) as well as their rheometric properties, and properties after cooking (40 min at 150 ° C); the vulcanization system is made up of sulfur and sulfenamide.
• the appended figure reproduces the module curves (in MPa) as a function of the elongation (in%); these curves are denoted Cl and C2 and correspond respectively to compositions C-1 and C-2.
• the composition according to the invention has the highest values of modulus under strong deformation (MA300) and of MA300 / MA100 ratio, clear indicators for those skilled in the art of better reinforcement provided by the inorganic filler and its POS oligomer coupling agent; - finally, hysteresis properties also improved, as illustrated by tan ( ⁇ ) max and ⁇ G values very significantly reduced, which is an indicator of reduced rolling resistance.
• composition of the invention (curve C2) reveals a higher level of reinforcement (module) whatever the rate of elongation under great deformation (elongations of 100% and more); for such an elongation domain, this behavior demonstrates a high quality of the bond or coupling between the reinforcing inorganic filler and the diene elastomer.
• composition according to the invention comprising the oligomer ⁇ , ⁇ -dihydroxy-mercaptopolyorganosiloxane reveals not only superior reinforcing properties, but also and above all improved cooking properties compared to to those offered by the conventional TESPT coupling agent.
• the invention finds particularly advantageous applications in rubber compositions intended for the manufacture of tire treads, in particular when these treads are intended for tires for passenger vehicles, motorcycles or industrial vehicles of the HGV type.
• silicone oil of type ⁇ , ⁇ -di-OH (“Rhodorsil 48V50” from the company Rhodia);

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• 2003
  • 2003-12-09 EP EP03799473A patent/EP1576044A1/de not_active Withdrawn
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