Classifications

• • 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
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J3/00—Processes of treating or compounding macromolecular substances
  • C08J3/20—Compounding polymers with additives, e.g. colouring
  • C08J3/205—Compounding polymers with additives, e.g. colouring in the presence of a continuous liquid phase
  • C08J3/2053—Compounding polymers with additives, e.g. colouring in the presence of a continuous liquid phase the additives only being premixed with a liquid phase
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J3/00—Processes of treating or compounding macromolecular substances
  • C08J3/20—Compounding polymers with additives, e.g. colouring
  • C08J3/205—Compounding polymers with additives, e.g. colouring in the presence of a continuous liquid phase
  • C08J3/21—Compounding polymers with additives, e.g. colouring in the presence of a continuous liquid phase the polymer being premixed with a liquid phase
  • C08J3/215—Compounding polymers with additives, e.g. colouring in the presence of a continuous liquid phase the polymer being premixed with a liquid phase at least one additive being also premixed with a liquid phase
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J3/00—Processes of treating or compounding macromolecular substances
  • C08J3/20—Compounding polymers with additives, e.g. colouring
  • C08J3/22—Compounding polymers with additives, e.g. colouring using masterbatch techniques
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J3/00—Processes of treating or compounding macromolecular substances
  • C08J3/20—Compounding polymers with additives, e.g. colouring
  • C08J3/22—Compounding polymers with additives, e.g. colouring using masterbatch techniques
  • C08J3/226—Compounding polymers with additives, e.g. colouring using masterbatch techniques using a polymer as a carrier
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/02—Elements
  • C08K3/08—Metals
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/34—Silicon-containing compounds
  • C08K3/36—Silica
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L21/00—Compositions of unspecified rubbers
  • C08L21/02—Latex
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2307/00—Characterised by the use of natural rubber
  • C08J2307/02—Latex
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2321/00—Characterised by the use of unspecified rubbers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2407/00—Characterised by the use of natural rubber
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2407/00—Characterised by the use of natural rubber
  • C08J2407/02—Latex
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2409/00—Characterised by the use of homopolymers or copolymers of conjugated diene hydrocarbons
  • C08J2409/10—Latex
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2415/00—Characterised by the use of rubber derivatives
  • C08J2415/02—Rubber derivatives containing halogen
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2421/00—Characterised by the use of unspecified rubbers
  • C08J2421/02—Latex
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
  • Y02T10/00—Road transport of goods or passengers
  • Y02T10/80—Technologies aiming to reduce greenhouse gasses emissions common to all road transportation technologies
  • Y02T10/86—Optimisation of rolling resistance, e.g. weight reduction 

Definitions

• the invention relates to the preparation of a masterbatch of diene elastomer and silica comprising at least one silica, a calcium salt and a diene elastomer latex, in particular a natural rubber latex.
• masterbatch refers to an elastomer-based composite in which a filler and possibly other additives have been introduced.
• the present invention relates in particular to the use of such a masterbatch for the manufacture of inorganic filler-reinforced diene rubber compositions for the manufacture of tires or semi-finished products for tires, in particular treads of these tires.
• these inorganic filler particles have an unfortunate tendency in the elastomeric matrix to agglomerate with each other. These interactions have the detrimental consequence of limiting the dispersion of the charge and therefore the reinforcing properties to a level substantially lower than that which it would be theoretically possible to achieve if all the bonds (inorganic filler / elastomer) that can be created during the mixing operation, were actually obtained; these interactions tend on the other hand to increase the consistency in the green state of the rubber compositions and thus to make their implementation ("processability") more difficult than in the presence of carbon black.
• HD type silicas having a BET surface area of between 100 and 250 m 2 / g.
• a high surface area silica HD referring in the field of "Green Tires” is in particular the silica "Zeosil 1165 MP" (BET surface equal to about 160 m 2 / g) marketed by Rhodia.
• the use of this silica "Zeosil 1165 MP" makes it possible to obtain good compromises in terms of tire performance, in particular satisfactory wear resistance and rolling resistance.
• the advantage of using a high surface area silica resides mainly in the possibility of increasing the number of bonds of the silica with the elastomer and therefore of increasing the level of reinforcement thereof.
• Another type of solution has been envisaged which consists in improving the dispersibility of the filler in the elastomeric matrix by mixing the elastomer and the "liquid" phase filler.
• an elastomer in the form of latex has been used in the form of elastomer particles dispersed in water, and aqueous dispersion of the filler, that is to say a silica dispersed in water, commonly called “slurry" of silica.
• silica aggregates are typically hydrophilic in nature and have affinity to water, so silica aggregates have more affinity with water than with the elastomer particles themselves.
• US Pat. No. 5,763,388 proposes the incorporation of silica into the rubber latex by treating the silica with a coupling agent, mixing the silica thus treated in the presence of conventional coagulation agents.
• the patent EP1321488 also proposes to put in contact an aqueous dispersion with negatively charged silica and a diene elastomer latex, with an emulsion containing a polysulfide coupling agent, in the presence of a coagulation agent such as a polyamine .
• the EPI patent 323775 also proposes bringing into contact an aqueous dispersion containing an inorganic filler such as a silica with an elastomer latex in the presence of a coagulation agent which may be constituted according to the list envisaged in this document by sodium or potassium chlorides, salts, acids ... More preferentially, this method describes an additional step allowing the formation in situ of the inorganic filler during mixing between the aqueous dispersion comprising a precursor capable of forming the inorganic filler, with the latex before adding a coagulation agent.
• a coagulation agent which may be constituted according to the list envisaged in this document by sodium or potassium chlorides, salts, acids ... More preferentially, this method describes an additional step allowing the formation in situ of the inorganic filler during mixing between the aqueous dispersion comprising a precursor capable of forming the inorganic filler, with the latex before adding a coagulation agent.
• the Applicants have surprisingly discovered a simplified method for obtaining a silica-elastomer masterbatch prepared in the "liquid" phase using a specific salt in a small predetermined quantity, without the need for the addition of other additives or agents. coagulation.
• This method makes it possible in particular to achieve a very good rate of return (greater than 80% by mass respecting the charge rate previously introduced and with good dispersion of the charge in the elastomeric matrix).
• the method for preparing a masterbatch of diene elastomer and silica comprises the following successive stages:
• the molar ratio of calcium cations defined as the number of moles of calcium cations of the calcium salt per unit area of silica (expressed in mol / m 2 ), is between 1.19 * 10 -6 and 2.81 * 10 ⁇ 6 mol / m 2 .
• the diene elastomer latex is a natural rubber latex, and in particular a concentrated latex of natural rubber.
• the silica is a precipitated silica.
• the amount of silica during the contacting of two dispersions is between 20 phr and 150 phr, parts per hundred parts by weight of elastomer, preferably between 30 phr and 100 phr, preferentially between 30 phr and 90 phr and even more preferably 30 phr and 70 phr.
• the calcium salt is preferentially chosen from calcium sulphates, calcium halides, calcium carbonates, calcium phosphates, calcium hydroxides, calcium oxalates and nitrates. calcium and more preferably the calcium salt is a calcium chloride.
• the invention also relates to a masterbatch of diene elastomer and silica, prepared according to the method which comprises the following successive stages:
• the subject of the invention is also a rubber composition based on at least one masterbatch as mentioned above, as well as a finished or semi-finished article, a tire tread or a tire or product. semi-finished product comprising at least one such rubber composition.
• the molar ratio of calcium cations is defined as the number of moles of calcium cations of the calcium salt per unit area of silica (expressed in mol / m 2 ), the unit of silica surface being defined as the silica mass considered multiplied by the BET specific surface area.
• a mass ml of metal salt having a molar mass M1 and a number N of metal atoms per molecule of salt, added to a mass m2 of silica (regardless of whether or not the silica is already dispersed in a solution aqueous) having a specific surface area measured by BET S2 (in m 2 / g), the molar level of metal cations expressed in mol / m 2 is equal to: [(ml / ml) * N] / (m2 * S2).
• the BET surface area is determined according to the method of BRUNAUER - EMMET - TELLER described in "The Journal of the American Chemical Society", Vol. 60, page 309, February 1938 and corresponding to standard NF T 45007.
• the weight losses of a mixing sample subjected to a rise in temperature are monitored. The latter is done in 2 steps: 1 / Heating from 25 to 550 ° C under an inert atmosphere (N 2 ) to evaporate the volatile materials and carry out the pyrolysis of the organic materials. Volatility resulting products causes a corresponding weight loss in a 1st step (300 ° C) and then the volatiles organics originally present in the mixture. 21 Continuation of heating up to 750 ° C under oxidizing atmosphere (Air or 0 2 ) to achieve the combustion of black (and / or charcoal). The resulting volatility of the products results in a weight loss corresponding to the initial amount of black (and / or charcoal material). The products that remain after these treatments constitute ashes. It is generally inorganic materials such as ZnO, silica ... c) - Measures c) -l- Preparation of samples
• the quantity of product analyzed must be weighed to 0.0 lmg and between 20 and 30 mg.
• 2nd segment dynamics of 550 to 750 ° C at 10 ° C / min, in air (or 02) (40 ml / min)
• the blank curve is made following the procedure described in the TGA User's Manual.
• the TGA takes into account, in order to determine the losses, the mass of the sample P2 which it calculates at the effective start of the measurement from the weight of the crucible, which is essential for the calculation of the residue; P2 is calculated by the TGA taking into account the mass P3 (Crucible + sample) at time T0 - PO.
• volatile matter rate then calculated by the apparatus is erroneous since a part of MV, volatile matter (PI - P2) evaporated during the wait between the preparation and the actual start of the measurement.
• Tx load (pcmo) [(D) / (B + C)] * 100
• B represents the percentage of organic matter (range 250-550 ° C)
• C the percentage of intermediate losses (between 550 and 750 ° C)
• D the percentage of residue (above 750 ° C).
• the coagulation yield corresponds to the ratio of the recovered dry mass (from which the mass of residual volatiles after drying as defined in the ATG measurement protocol has been removed in the preceding paragraphs) on the target mass. initially, multiplied by one hundred.
• the method for preparing a masterbatch of diene elastomer and silica according to the invention comprises the following successive stages:
• the molar ratio of calcium cations defined as the number of moles of calcium cations of the calcium salt per unit area of silica (expressed in mol / m 2 ), is between 1.19 * 10 -6 and 2.81 * 10 ⁇ 6 mol / m 2 .
• any silica S1O2 known to those skilled in the art, especially any precipitation silica or pyrogenation having a BET surface and a specific surface CTAB both less than 450 m 2 / g, preferably from 30 to 400 m 2 / g.
• HDS highly specific silicas
• the silicas Ultrasil 7000 and Ultrasil 7005 from the company Degussa
• the silicas Zeosil 1165MP, 1135MP and 1115MP from the company Rhodia from the company Rhodia
• the silica Hi-Sil EZ150G from PPG from the Zeopol 8715, 8745 and 8755 silicas from Huber
• the high surface area silicas as described in WO 03/16837.
• the silica is then dispersed in water, preferably so as to obtain a dispersion whose viscosity is sufficient to be easily "manipulable".
• the mass concentration of silica in the dispersion is between 0.1 and 30%.
• an aqueous dispersion of silica with a silica content in water of 4% by weight can be produced.
• the dispersion is sheared by sonification in order to make it possible to obtain stability of the aggregates in the water, which makes it possible to improve the dispersion of the silica in the masterbatch subsequently produced.
• This sonication can notably be carried out using a Vibracell generator manufactured by SONICS and Materials Inc. of 1500 Watts with a piezoelectric converter with PZT crystal (reference 75010), a booster for the probe and a 19mm diameter titanium alloy probe. (for a height of 127mm).
• a Vibracell generator manufactured by SONICS and Materials Inc. of 1500 Watts with a piezoelectric converter with PZT crystal (reference 75010), a booster for the probe and a 19mm diameter titanium alloy probe. (for a height of 127mm).
• the calcium salt is then added and the mixture is stirred with a spatula.
• the calcium salt can advantageously be added to the aqueous silica dispersion before the sonification step, in particular to improve the solubilization of the salt in the aqueous dispersion produced. II-2) Calcium salt
• Calcium salts chosen from calcium sulphates, calcium halides and in particular chlorides, bromides, fluorides and iodides, calcium carbonates, calcium phosphates, calcium hydroxides and oxalates are particularly suitable.
• calcium and calcium nitrates and more preferably still the calcium salt chosen is a calcium chloride. It is clear that it is possible to envisage using a blend of the various calcium salts mentioned above.
• the elastomer latex is a particular form of elastomer which is in the form of elastomer particles dispersed in water.
• the invention relates to diene elastomer latices, the diene elastomers being defined as follows:
• elastomer or “diene” rubber should be understood in known manner an elastomer derived at least in part (i.e., a homopolymer or a copolymer) of monomers dienes (monomers bearing two carbon-carbon double bonds, conjugated or not).
• diene elastomers can be classified into two categories: “essentially unsaturated” or “essentially saturated”.
• the term “essentially unsaturated” is generally understood to mean a diene elastomer derived at least in part from conjugated diene monomers, having a level of units or units of diene origin (conjugated dienes) which is greater than 15% (mol%);
• diene elastomers such as butyl rubbers or copolymers of dienes and alpha-olefins of the EPDM type do not fall within the above definition and may in particular be described as "substantially saturated” diene elastomers ( low or very low diene origin, always less than 15%).
• the term “highly unsaturated” diene elastomer is particularly understood to mean a diene elastomer having a content of units of diene origin (conjugated dienes) which is greater than 50%.
• the latex can be used directly or be previously diluted in water to facilitate its implementation.
• diene elastomer By synthetic diene elastomers which can be used in accordance with the invention, the term diene elastomer is more particularly understood to mean:
• conjugated dienes 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-di (C 1 -C 5) alkyl-1,3-butadienes, such as for example 2 3-dimethyl-1,3-butadiene, 2,3-diethyl-1,3-butadiene, 2-methyl-3-ethyl-1,3-butadiene, 2-methyl-3-isopropyl-1,3-butadiene, aryl-1,3-butadiene, 1,3-pentadiene, 2,4-hexadiene.
• alkyl-1,3-butadienes such as for example 2 3-dimethyl-1,3-butadiene, 2,3-diethyl-1,3-butadiene, 2-methyl-3-ethyl-1,3-butadiene, 2-methyl-3-isopropyl-1,3-butadiene, aryl-1,3-butadiene, 1,3-pentadiene, 2,4-he
• Suitable vinylaromatic compounds are, for example, styrene, ortho-, meta-, para-methylstyrene, the "vinyl-toluene" commercial mixture, para-tertiarybutylstyrene, methoxystyrenes, chlorostyrenes, vinylmesitylene, divinylbenzene, vinylnaphthalene.
• the copolymers may contain between 99% and 20% by weight of diene units and between 80% and 80% by weight of vinylaromatic units.
• the elastomers may have any microstructure which is a function of the polymerization conditions used, in particular the presence or absence of a modifying and / or randomizing agent and the amounts of modifying and / or randomizing agent used.
• the elastomers can be for example block, statistical, sequenced, microsequenced, and be prepared in dispersion or in solution; they may be coupled and / or starred or functionalized with a coupling agent and / or starring or functionalization.
• alkoxysilane groups as described for example in FR 2,765,882 or US 5,977,238), carboxylic groups (as described for example in WO 01/92402 or US 6,815,473, WO 2004/096865 or US 2006 / 0089445) or polyether groups (as described for example in EP 1 127 909 or US 6,503,973, WO 2009/000750 and WO 2009/000752).
• elastomers such as SBR, BR, NR or IR of the epoxidized type.
• Suitable polybutadienes and in particular those having a content (mol%) in units -1.2 between 4%> and 80%> or those having a content (%> molar) in cis-1,4 greater than 80%> polyisoprenes, butadiene-styrene copolymers and in particular those having a Tg (glass transition temperature (Tg, measured according to ASTM D3418) between 0 ° C. and -70 ° C. and more particularly between -10 ° C.
• Tg glass transition temperature
• styrene content of between 5% and 60% by weight and more particularly between 20% and 50%, a content (%> molar) in -1,2 bonds of the butadiene part between 4% and 75%, a content (mol%) of trans-1,4 bonds of between 10% and 80%, butadiene-isoprene copolymers and in particular those having an isoprene content of between 5% and 90%.
• the isoprene-styrene copolymers and especially those having a styrene content of between 5% and 50% by weight and a e Tg between -5 ° C and -50 ° C.
• 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 -1,2 units of the butadiene part of between 4% and 85%, a content (mol%) in trans units -1,4 of the butadiene part included between 6% and 80%, a content (mol%) in units -1,2 plus -3,4 of the isoprenic part of between 5% and 70% and a content (mol%) in trans units -1,4 of the isoprene part of between 10% and 50%), and more generally any butadiene-styrene-isoprene copolymer having a Tg of between -5 ° C and -70 °
• the synthetic diene elastomer (s) according to the invention are preferably chosen from the group of highly unsaturated diene elastomers consisting of polybutadienes (abbreviated as "BR"), synthetic polyisoprenes (IR), butadiene copolymers, copolymers of isoprene and mixtures of these elastomers.
• BR polybutadienes
• IR synthetic polyisoprenes
• IR butadiene copolymers
• copolymers of isoprene and mixtures of these elastomers are more preferably selected from the group consisting of butadiene-styrene copolymers (SBR), isoprene-butadiene copolymers (BIR), isoprene-styrene copolymers (SIR) and isoprene-copolymers.
• SBR butadiene-styrene copolymers
• BIR isoprene-but
• the latex can in particular consist of a synthetic diene elastomer already available in the form of an emulsion (for example a copolymer of butadiene and styrene, SBR, prepared in emulsion), or a diene elastomer.
• synthetic solution initially for example a SBR prepared in solution
• a surfactant for example a surfactant which is emulsified in a mixture of organic solvent and water, generally by means of a surfactant.
• SBR latex in particular an emulsion-prepared SBR (“ESBR”) or an SBR prepared in solution (“SSBR”), and more particularly an SBR prepared in emulsion.
• ESBR 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 ring content of the butadiene part of between 15% and 70%, a content (mol%) of trans-1,4 bonds of between 15% and 75% and a Tg of between -10 ° C. and - 55 ° C; such an SBR can be advantageously used in admixture with a BR preferably having more than 90% (mol%) of cis-1,4 bonds.
• one or more natural rubber latexes may be used in the form of a blend, one or more synthetic rubber latexes in a blend or a blend of one or more natural rubber latexes with one or more synthetic rubber latexes.
• Both dispersions are contacted in the presence of a calcium salt.
• the salt is added to the aqueous dispersion of silica as has been previously explained, that is to say during the formation of the aqueous dispersion of silica or after its formation.
• the calcium salt when the aqueous dispersion of silica and the elastomer latex are brought into contact. In the latter case, it is advantageous to introduce the salt in the form of a saline solution.
• any type of apparatus allowing an "effective" mixing of two products in the liquid phase can also be used, so it will be possible to use a static mixer such as static mixers marketed by Noritake Co., Limited, TAH in the US, KOFLO with USA, or TOKUSHU KIKA KOGYO Co., Ltd. or a high shear mixer such as mixers marketed by TOKUSHU KIKA KOGYO Co., Ltd., or by PUC in Germany, by CAVITRON in Germany or by SILVERSON in the UK. It is clear that the more efficient the mixing step, the better the dispersion and homogeneity of the silica-diene elastomer masterbatch.
• a coagulum of elastomer and silica is formed either as a single solid element in the solution, or in the form of several separate solid elements.
• the calcium cation molar rate defined as the number of moles of calcium cations of the calcium salt per unit area of silica (expressed in mol / m 2 ), must be between 1, 19 * 10 ⁇ 6 and 2,81 * 10 ⁇ 6 mol / m 2 .
• the volumes of the two dispersions to be contacted and in particular the silica dispersion volume depends on the silica target for the master batch to be achieved, taking into account the respective concentrations of the dispersions. So the volume will be adapted accordingly.
• the target silica content for the masterbatch is between 20 and 150 phr (parts by weight per hundred parts of elastomer), preferably between 30 and 100 phr and more preferably between 30 and 90 phr, more preferably between 30 and 90 phr. and 70 pce.
• the solids recovered are filtered or centrifuged. Indeed, the filtering operation that can be performed using a sieve or filter cloth, may be unsuitable when the coagulum is in the form of many small and solid elements. In such a case, an additional centrifugation operation is preferably carried out.
• the coagulum obtained is dried, for example in an oven.
• the dry coagulum obtained may advantageously be homogenized in order to ensure the representativity of the sample for measuring the degree of charge, for example by performing a light mechanical work on a cylinder tool.
• the masterbatches thus produced may be used in rubber compositions, in particular for tires.
• the rubber compositions for tires based on the masterbatches according to the invention may also comprise, in known manner, a coupling agent and a vulcanization system.
• coupling agent is understood to mean, in known manner, an agent capable of establishing a sufficient bond, of a chemical and / or physical nature, between the inorganic filler and the diene elastomer; such a coupling agent, at least bifunctional, has for example as simplified general formula "Y-Z-X", in which:
• Y represents a functional group ("Y" function) which is capable of binding physically and / or chemically to the inorganic filler, such a bond being able to be established, for example, between a silicon atom of the coupling agent and the surface hydroxyl (OH) groups of the inorganic filler (for example surface silanols in the case of 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;
• Z represents a divalent group making it possible to connect 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.
• TESPT bis 3-triethoxysilylpropyl tetrasulfide
• pigments whether these are aromatic or non-aromatic, 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, a crosslinking system based on either sulfur or sulfur donors and / or peroxide and / or bismaleimides, vulcanization accelerators.
• 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, a crosslinking system based on either sulfur or sulfur donors and / or peroxide and / or bismaleimides, vulcanization accelerators.
• these compositions comprise, as preferential non-aromatic or very weakly aromatic plasticizing agent, at least one compound chosen from the group consisting of naphthenic, paraffinic, MES, TDAE, ester (especially trioleate) oils.
• glycerol the hydrocarbon plasticizing resins having a high Tg preferably greater than 30 ° C, and mixtures of such compounds.
• compositions may also contain, in addition to the coupling agents, coupling activators, covering agents (comprising, for example, the only Y function) of the reinforcing inorganic filler or, more generally, processing aid agents capable of in a known manner, thanks to an improvement of the dispersion of the inorganic filler in the rubber matrix and to a lowering of the viscosity of the compositions, to improve their ability to use in the green state, these agents being for example hydrolysable silanes such as alkylalkoxysilanes (especially alkyltriethoxysilanes), polyols, polyethers (for example polyethylene glycols), primary, secondary or tertiary amines (for example trialkanol amines), hydroxylated or hydrolyzable POSs, for example ⁇ , ⁇ -dihydroxy-polyorganosiloxanes (in particular ⁇ , ⁇ -dihydroxy-polydimethylsiloxanes), fatty acids such as, for
• the rubber compositions of the invention are made in suitable mixers, using two successive preparation phases according to one procedure.
• a first phase of work or thermomechanical mixing (sometimes called “non-productive” phase) at high temperature, up to a maximum temperature between 130 ° C and 200 ° C preferably between 145 ° C. and 185 ° C.
• a second mechanical working phase (sometimes referred to as a "productive" phase) at a lower temperature, typically below 120 ° C., for example between 60 ° C. and 100 ° C. ° C, finishing phase during which is incorporated the crosslinking system or vulcanization.
• all the basic constituents of the compositions of the invention are intimately incorporated, by kneading, with the diene elastomer during the first so-called non-productive phase, that is, that is to say that is introduced into the mixer and that is kneaded thermomechanically, in one or more steps, at least these various basic constituents until the maximum temperature between 130 ° C and 200 ° C, preferably between 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 an external mixer such as a roller mixer; the whole is then mixed (productive phase) for a few minutes, for example between 2 and 15 min.
• a coating agent When a coating agent is used, its incorporation can be carried out entirely during the non-productive phase, together with the inorganic filler, or in full during the productive phase, together with the vulcanization system, or still split over the two successive phases. It should be noted that it is possible to introduce all or part of the coating agent in a supported form (the setting is carried out beforehand) on a solid compatible with the chemical structures corresponding to this compound. For example, when splitting between the two successive phases above, it can be It is advantageous to introduce the second part of the coating agent onto the external mixer after being placed on a support in order to facilitate its incorporation and dispersion.
• 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 preferential rate of between 0.5 and 10 phr, more preferably between 0.5 and 5.0 phr.
• accelerator primary or secondary
• any compound capable of acting as an accelerator of vulcanization of diene elastomers in the presence of sulfur in particular thiazole-type accelerators and their derivatives, accelerators of thiuram type, zinc dithiocarbamates.
• accelerators are for example selected from the group consisting of 2-mercaptobenzothiazyl disulfide (abbreviated "MBTS”), tetrabenzylthiuram disulfide (“TBZTD”), N-cyclohexyl-2-benzothiazyl sulfenamide (“CBS”), N, N dicyclohexyl-2-benzothiazyl sulphenamide (“DCBS”), N-tert-butyl-2-benzothiazyl sulphenamide (“TBBS”), N-tert-butyl-2-benzothiazyl sulphenimide (“TBSI”), zinc dibenzyldithiocarbamate (“ ZBEC ”) and mixtures of these compounds.
• MBTS 2-mercaptobenzothiazyl disulfide
• TBZTD tetrabenzylthiuram disulfide
• CBS N-cyclohexyl-2-benzothiazyl sulfen
• 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.
• Vibracell ultrasound generator manufactured by SONICS and Materials Inc of 1500 Watts (ref: VC1500, 20kHz), with a piezoelectric converter with PZT crystal (reference CV154), a booster for the probe (ref BHN15GD, amplitude increased by 50%) and a standard non-threaded probe (not "high gain”) in 19mm diameter titanium alloy (for a height of 127mm)
• silica 160MP precipitation silica (ZEOSIL 1165MP), manufactured by Rhodia, BET specific surface area measured at 160 m 2 / g, with an actual density of 2.14 g / cm 3 , with a level of "surface" silanol functions (measured by Me (OH)) graftation of 7.4 OH / nm 2 and a “total" silanols functional level (measured by AT G) of 12 OH / nm 2
• ZEOSIL 1165MP 160MP precipitation silica
• the quantity of calcium chloride which is introduced into the aqueous suspension of silica is weighed (brought into contact for at least 10 minutes).
• the slurry of [silica + water + salt] is sonified at 60% of the maximum power of the generator. ultrasound, for 8 minutes, the beaker 100mL being maintained at a fixed temperature by being immersed in an ice bath.
• the dispersion thus obtained just sonifée is then maintained with magnetic stirring (500tr / min) until contacting.
• the latex is weighed and its concentration is adjusted (dilution by addition of ultrapure water).
• the coagulum formed or the solids formed are centrifuged, including in cases where the visual appearance of the coagulum made it possible to envisage an operation filtering.
• the centrifugation is carried out, after transfer into a 250mL nalgene flask, using a Sigma 4K15 scoop centrifuge at 8000 rpm for 10 minutes.
• the coagulum in the form of a pellet
• the ATG loading rate and the coagulation yield are then measured on the master batch thus produced.
• the calcium salt used in this example being a calcium chloride (Ca (Cl 2 ), 2H 2 O as specified in section III-1.
• tests El, E2 and E3 are distinguished from each other as follows: for El, the molar ratio of calcium cations is 1.12 * 10 -6 (corresponding to a hydrated calcium chloride mass of 0.097 g for a master batch of 10.5 g, at 50 parts by weight per hundred parts of elastomer)
• the molar ratio of calcium cations is 1.56 * 10 -6 (corresponding to a mass of hydrated calcium chloride of 0.130 g)
• the molar ratio of calcium cations is 2.31 * 10 -6 (corresponding to a mass of hydrated calcium chloride of 0.195 g)
• the molar ratio of calcium cations is 3.12 * 10 -6 (corresponding to a hydrated calcium chloride mass of 0.259 g).

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