WO2017085109A1 - Process for preparing a stabilized natural rubber - Google Patents

Process for preparing a stabilized natural rubber Download PDF

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Publication number
WO2017085109A1
WO2017085109A1 PCT/EP2016/077832 EP2016077832W WO2017085109A1 WO 2017085109 A1 WO2017085109 A1 WO 2017085109A1 EP 2016077832 W EP2016077832 W EP 2016077832W WO 2017085109 A1 WO2017085109 A1 WO 2017085109A1
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WO
WIPO (PCT)
Prior art keywords
natural rubber
hydroxylamine
mmol
rubber
acid salts
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Application number
PCT/EP2016/077832
Other languages
French (fr)
Inventor
Jérôme DUSSILLOLS
Jean-Luc MERCERON
Original Assignee
Compagnie Generale Des Etablissements Michelin
Michelin Recherche Et Technique S.A.
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Publication date
Application filed by Compagnie Generale Des Etablissements Michelin, Michelin Recherche Et Technique S.A. filed Critical Compagnie Generale Des Etablissements Michelin
Publication of WO2017085109A1 publication Critical patent/WO2017085109A1/en

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Classifications

    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08CTREATMENT OR CHEMICAL MODIFICATION OF RUBBERS
    • C08C3/00Treatment of coagulated rubber
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29BPREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
    • B29B13/00Conditioning or physical treatment of the material to be shaped
    • B29B13/02Conditioning or physical treatment of the material to be shaped by heating
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29BPREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
    • B29B13/00Conditioning or physical treatment of the material to be shaped
    • B29B13/06Conditioning or physical treatment of the material to be shaped by drying
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29BPREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
    • B29B13/00Conditioning or physical treatment of the material to be shaped
    • B29B13/10Conditioning or physical treatment of the material to be shaped by grinding, e.g. by triturating; by sieving; by filtering
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29BPREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
    • B29B15/00Pretreatment of the material to be shaped, not covered by groups B29B7/00 - B29B13/00
    • B29B15/02Pretreatment of the material to be shaped, not covered by groups B29B7/00 - B29B13/00 of crude rubber, gutta-percha, or similar substances
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60CVEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C1/00Tyres characterised by the chemical composition or the physical arrangement or mixture of the composition
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08KUse of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00Use of organic ingredients
    • C08K5/0008Organic ingredients according to more than one of the "one dot" groups of C08K5/01 - C08K5/59
    • C08K5/005Stabilisers against oxidation, heat, light, ozone
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08LCOMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L7/00Compositions of natural rubber
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29KINDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2007/00Use of natural rubber as moulding material

Definitions

  • the invention relates to a process for the preparation of a treated natural rubber by means of the addition of a stabilizing agent and the homogenization of the resulting assembly by means of a device which provides mechanical work at elevated temperature.
  • the stabilization of the natural rubber can also be carried out in the latex phase by injection of the stabilizers into the latex.
  • the latex phase treatment has the disadvantage of losing stabilizer in the coagulation water which is released into the environment.
  • GB 1373630 discloses the stabilization of natural rubber by adding hydroxylamine sulfate to natural rubber in the solid state and then reacting at a temperature above 100 ° C in a mixing machine.
  • solutions of hydroxylamine sulfate can corrode machines such as mixing machines or storage tanks of the solution.
  • natural rubber can be treated by a process comprising a step of adding to the natural rubber predominantly in the form of a natural bottom-cup rubber of one or more agents selected from dimedone and particular hydroxylamine - derived compounds in a specific amount, and a mechanical working step of the assembly at a temperature of at least 100 ° C, such a process allowing energy gain, productivity and investment cost. compared to the usual plastification processes, while avoiding corrosion phenomena in installations.
  • the object of the invention is therefore a process for treating a natural rubber, comprising the following steps:
  • the stabilizing agent (s) being dimedone or being chosen from the weak acid salts of compounds of formula XNH 2 and the strong acid salts of compounds of formula XNH 2 neutralized with a strong base, where X is a group selected from hydroxy and C 1 -C 4 hydroxyalkyl groups, and said stabilizing agent (s) being respectively present in an amount ranging from 2.4 mmoles to 24 mmoles equivalent to dimedone or equivalent of XNH 2 per kilogram of natural rubber and then
  • natural rubber of the bottom of the cup is meant the part of natural rubber which, after bleeding from the tree and recoated in a cup, has coagulated in solid form in this cup, and then underwent a cleaning, homogenization and drying.
  • Natural latex rubber means the natural rubber which, after bleeding from the tree, has flowed into the cup, has been reco lted in liquid form and artificially coagulated, then has undergone cleaning, homogenisation and drying.
  • the cleaning, homogenization and drying work generally comprises one or more steps of reducing the size of the pieces of natural rubber, for example by means of a hammer mill, one or more washing steps in a water tray for removing impurities and contaminants, one or more crepe steps, one or more crumbling steps, and one or more drying steps. Then the natural rubber is compressed to be put in the form of bread or ball.
  • the natural rubber is a natural cup bottom rubber. This means that natural rubber does not contain natural latex rubber.
  • the natural rubber used in the process according to the invention is chosen from the natural rubbers derived from the rubber tree Brasiliensis.
  • the stabilizing agent (s) may be chosen from the weak acid salts of compounds of formula XNH 2 .
  • the weak acid salts of compounds of formula XNH 2 mention may be made of the weak acid salts of hydroxylamine, for example hydroxylamine acetate and hydroxylamine oxalate.
  • the stabilizing agent (s) may also be chosen from the strong acid salts of compounds of formula XNH 2 as defined above, neutralized with a strong base.
  • the strong acid salts of compounds of formula XNH 2 mention may be made of the strong acid salts of hydroxylamine, for example hydroxylamine sulfate.
  • the stabilizing agent (s) are hydroxylamine strong acid salts, neutralized with a strong base, the content of hydroxylamine strong acid salt (s) ranging from 2.4 mmol to 24 mmol equivalents of hydroxylamine per kilogram of natural rubber, the content of strong base ranging from 0.1 to 2 moles, preferably 1 to 2 moles, per mole of strong acid salt of hydroxylamine.
  • the stabilizing agent (s) are weak acid salts of hydroxylamine, and are present in a content ranging from 2.4 mmol to 24 mmol equivalent of hydroxylamine, preferably from 6 mmol to 24 mmol. mmol equivalent of hydroxylamine, more preferably from 8 mmol to 18 mmol equivalent of hydroxylamine, per kilogram of natural rubber.
  • the stabilizing agent is dimedone and is present in a content ranging from 2.4 mmol to 24 mmol equivalent of dimedone, preferably from 6 mmol to 24 mmol equivalent of dimedone, per kilogram of natural rubber. .
  • the stabilizing agent (s) are strong acid salts of compounds XNH 2 as defined above, neutralized with a strong base
  • the strong base may be chosen from sodium hydroxide (sodium hydroxide), potassium hydroxide, preferably soda.
  • Strong acid salt neutralized with a strong base means contacting the strong acid salt with the strong base. It is this mixture that is added as a stabilizer in the process.
  • the addition of the stabilizing agent (s) to the natural rubber can be done by spraying the natural rubber with the desired amount of stabilizing agent, generally in aqueous solution, or by soaking the natural rubber in a solution of agent (s) stabilizer (s).
  • the addition of the stabilizing agent (s) to the natural rubber is done by watering.
  • the method according to the invention comprises a mechanical working step at a temperature of at least 100 ° C. natural rubber to which has been added and the stabilizing agent (s).
  • the mechanical work is carried out at a temperature of at least 110 ° C.
  • the mechanical work is preferably carried out by means of one or more shredding and homogenizing devices.
  • a shredding and homogenizing device is generally called "prebreaker”.
  • Such a device has an energy consumption of the order of 50 kW / ton of natural rubber, whereas a plasticizing process consumes around 140 kW / ton.
  • the mechanical work is performed by means of two shredding and homogenization devices arranged in series.
  • the use of two such devices is particularly advantageous to ensure that the natural rubber is maintained at a temperature of at least 100 ° C for a sufficient time which allows the stabilizing agent to react.
  • the mechanical work carried out by means of two devices also makes it possible to achieve a homogeneous distribution of the additive in the natural rubber, this distribution being able to be controlled by an assay according to the method described in the publication J.nat.Rubb .Res, 3 (1), 1-6.
  • the mechanical working stage advantageously has a duration varying from 25 seconds to 3 minutes.
  • the shredding and homogenizing device (s) usually each comprise a feed and shredding zone and a homogenization zone connected to each other, and a shaft passing through said zones, said shaft being provided with rotary knives.
  • the feeding zone generally comprises an upper part and a lower part, said upper part being able to feed said lower part, said lower part comprising the first part of said shaft.
  • the walls of the feed zone have first fixed knives. Such first fixed knives prevent the assembly of natural rubber - stabilizing agent from rising in the upper part of the feed zone once it has reached the lower part of the feed zone.
  • the homogenization zone generally comprises the second part of said shaft and a sleeve inserting said second part of the shaft, said sleeve being provided with second fixed blades.
  • the shaft housed in the lower part of the feed zone and in the homogenization zone is preferably horizontal.
  • the speed of the shaft advantageously varies from 20 to 100 rpm, preferably from 20 to 60 rpm.
  • the chipping and homogenizing device or devices usually each have a die plate at the end of the homogenization zone, said die plate having orifices.
  • holes may be in the form of round holes or oblong holes or triangular holes.
  • these orifices have a variable opening.
  • the variation of the opening of the orifices makes it possible to increase or decrease the mechanical work provided to the natural rubber or to vary the flow rate in the device.
  • the temperature in the shredding and homogenization zone can be adjusted by varying the mechanical work, using the following means, alone or in combination: number of fixed knives, number of rotary knives, length of shredding zone and homogenization, closure of the die plate, flow of natural rubber, heating of the body of the shredding device and homogenization.
  • the mechanical working step may be followed by a cutting step of the treated natural rubber.
  • the cutting step can be performed by means of a cutting device positioned at the output of the device conferring the work mechanical, in particular or the shredding and homogenization device or devices.
  • Another object of the invention is a treated natural rubber which can be obtained by the process obj and of the invention.
  • Another object of the invention is a reinforced rubber composition based on at least one reinforcing filler and an elastomeric matrix comprising at least one natural rubber treated according to the invention.
  • composition-based is meant a composition comprising the mixture and / or the reaction product of the various constituents used, some of these basic constituents being capable of or intended to react with one another, less in part, during the various phases of manufacture of the composition, in particular during its crosslinking or vulcanization.
  • the reinforced rubber composition according to the invention may be in the crosslinked state or in the uncrosslinked state, that is to say crosslinkable.
  • the elastomer matrix present in the composition according to the invention may also, in addition to the natural rubber treated according to the invention, comprise at least one other diene elastomer.
  • the mass fraction of the natural rubber treated according to the invention in the elastomer matrix is predominant and preferably greater than or equal to 10% by weight of the total mass of the matrix. more preferably still greater than or equal to 50% by weight of the total mass of the matrix, even more preferably greater than or equal to 70%.
  • the mass fraction of the natural rubber treated according to the invention in the elastomer matrix is preferably less than or equal to 85% by weight of the total mass of the matrix.
  • the majority mass fraction according to the invention is the highest mass fraction of the blend.
  • diene elastomer it should be understood according to the invention any synthetic elastomer derived at least in part from monomers dienes. More particularly, by diene elastomer, we mean everything homopolymer obtained by polymerization of a conjugated diene monomer having 4 to 12 carbon atoms, or any copolymer obtained by copolymerization of one or more conjugated dienes with each other or with one or more vinylaromatic compounds having from 8 to 20 carbon atoms. In the case of copolymers, these contain from 20% to 99% by weight of diene units, and from 1 to 80% by weight of vinylaromatic units.
  • the diene elastomer constituting a part of the elastomer matrix of the composition according to the invention is preferably chosen from the group of highly unsaturated diene elastomers consisting of polybutadienes (BR), synthetic polyisoprenes (IR) and natural rubber (NR). ) different from the natural rubber treated according to the invention, butadiene copolymers, isoprene copolymers and mixtures of these elastomers.
  • BR polybutadienes
  • IR synthetic polyisoprenes
  • NR natural rubber
  • Such copolymers are more preferably selected from the group consisting of butadiene-styrene copolymers (SBR), isoprene-butadiene copolymers (BIR), isoprene-styrene copolymers (SIR) and isoprene-copolymers.
  • SBR butadiene-styrene copolymers
  • BIR isoprene-butadiene copolymers
  • SIR isoprene-styrene copolymers
  • SBIR butadiene-styrene
  • the elastomeric matrix consists solely of the natural rubber treated according to the invention.
  • the rubber composition of the invention comprises, in addition to at least one elastomeric matrix as described above, at least one reinforcing filler.
  • reinforcing filler known for its ability to reinforce a rubber composition that can be used for manufacturing tire treads, for example carbon black, a reinforcing inorganic filler such as silica with which it is associated with known manner a coupling agent, or a mixture of these two types of load.
  • Suitable carbon blacks are all carbon blacks, used individually or in the form of mixtures, especially those black type HAF, ISAF, SAF conventionally used in the treads of tires (so-called pneumatic grade black). Among the latter, mention will be made more particularly of reinforcing carbon blacks of the 100, 200 or 300 series (ASTM grades), for example blacks NI 15, N 134, N 234, N 326, N 30 O, N 339, N 347, N 375.
  • the carbon blacks could for example be already incorporated into the isoprene elastomer in the form of a masterbatch (see for example WO 97/36724 or WO 99/16600).
  • reinforcing inorganic filler is meant by the present application, by definition, any inorganic or inorganic filler whatever its color and its origin (natural or synthetic), capable of reinforcing on its own, without any other means than an agent intermediate coupling, a rubber composition for the manufacture of tires; such a filler is generally characterized, in known manner, by the presence of hydroxyl groups (-OH) on its surface.
  • a filler is generally characterized, in known manner, by the presence of hydroxyl groups (-OH) on its surface.
  • Suitable reinforcing inorganic fillers are mineral fillers of the siliceous type, in particular of silica (SiO 2), or of the aluminous type, in particular alumina (Al 2 O 3).
  • the silica used may be any 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 m2 / g.
  • Reinforcing fillers of another nature, in particular carbon black are also suitable as reinforcing fillers, provided that these reinforcing fillers are covered with a siliceous layer, or else comprise on their surface functional sites, in particular hydroxyl sites, requiring the use of a coupling agent to establish the bond between the filler and the elastomer.
  • carbon blacks for tires as described for example in the patent documents WO 96/37547 and WO 99/28380.
  • the physical state in which the reinforcing inorganic filler is present is indifferent whether in the form of powder, microbeads, granules, beads or any other suitable densified form.
  • the term "reinforcing inorganic filler” also refers to mixtures of different reinforcing fillers, in particular highly dispersible siliceous fillers as described above.
  • the content of total reinforcing filler is between 10 and 200 phr, more preferably between 30 and 150 phr, and even more preferentially between 70 and 130 phr. , the optimum being in a known manner different according to the particular applications concerned.
  • the reinforcing filler is predominantly other than carbon black, that is to say it comprises more than 50% by weight of the total weight of the filler, of one or more fillers other than carbon black, especially a reinforcing inorganic filler such as silica, or it consists exclusively of such a filler.
  • carbon black when carbon black is also present, it may be used at a level of less than 20 phr, more preferably less than 10 phr (for example between 0.5 and 20 phr, in particular from 1 to 10 phr).
  • a reinforcing filler comprising predominantly carbon black and optionally silica or other inorganic filler is used.
  • the rubber composition according to the invention further comprises, in a conventional manner, an agent capable of effectively provide this link.
  • organosilanes may be used as coupling agents, especially polysulfurized alkoxysilanes or mercaptosilanes, or at least bifunctional polyorganosiloxanes.
  • the level of coupling agent is advantageously less than 20 phr, it being understood that it is generally desirable to use as little as possible. Its rate is preferably between 0.5 and 12 phr.
  • the presence of the coupling agent depends on that of the reinforcing inorganic filler. Its rate is easily adjusted by the skilled person according to the rate of this charge; it is typically of the order of 0.5% to 15% by weight relative to the amount of reinforcing inorganic filler other than carbon black.
  • the rubber composition according to the invention may also contain, in addition to the coupling agents, coupling activators, charge-recovery agents or, more generally, processing aid agents which can be used in known manner, thanks to an improvement of the dispersion of the filler in the rubber matrix and a lowering of the viscosity of the composition, to improve its ability to use in the green state, these agents being for example the hydrolysable silanes such as alkylalkoxysilanes, polyols, polyethers, primary, secondary or tertiary amines, hydroxylated or hydrolyzable polyorganosiloxanes.
  • these agents being for example the hydrolysable silanes such as alkylalkoxysilanes, polyols, polyethers, primary, secondary or tertiary amines, hydroxylated or hydrolyzable polyorganosiloxanes.
  • the rubber compositions in accordance with the invention may also contain reinforcing organic fillers which may replace all or part of the carbon blacks or other reinforcing inorganic fillers described above.
  • reinforcing organic fillers include functionalized polyvinyl organic fillers as described in applications WO-A-2006/069792, WO-A-2006/069793, WO-A-2008/003434 and WO-A 2008/003435.
  • the rubber composition according to the invention may also comprise all or part of the usual additives usually used.
  • elastomer compositions for the manufacture of tires such as, for example, pigments, non-reinforcing fillers, protective agents such as anti-ozone waxes, chemical antiozonants, anti-oxidants, anti-fatigue agents, plasticizing agents, reinforcing or plasticizing resins, acceptors (for example novo lacquer phenolic resin) or methylene donors (for example HMT or H3M) as described, for example, in application WO 02/1 0269, a crosslinking system based on either sulfur, or sulfur and / or peroxide donors and / or bismaleimides, vulcanization accelerators, vulcanization activators.
  • protective agents such as anti-ozone waxes, chemical antiozonants, anti-oxidants, anti-fatigue agents, plasticizing agents, reinforcing or plasticizing resins, acceptors (for example novo lacquer phenolic resin) or methylene donors
  • composition is 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 1 10 ° C and 190 ° C, preferably between 130 ° C and 1 80 ° C, followed by a second mechanical working phase (so-called “productive” phase) to a lower temperature, typically less than 1 10 ° C, for example between 40 ° C and 100 ° 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 1 10 ° C and 190 ° C, preferably between 130 ° C and 1 80 ° C
  • a second mechanical working phase “productive” phase
  • finishing phase finishing phase during which is incorporated the crosslinking system.
  • the process for preparing a composition according to the invention generally comprises:
  • the invention also relates to a semi-finished article of rubber for a tire, comprising a composition of rubber according to the invention, crosslinkable or crosslinked, or consisting of such a composition.
  • the final composition thus obtained may then be calendered, for example in the form of a sheet, a plate or extruded, for example to form a rubber profile usable as a semi-finished rubber product for the tire.
  • the invention is therefore obj and a tire comprising a semi-finished article according to the invention, in particular a tread.
  • FIG. 1 represents a shredding and shredding device. homogenization.
  • the natural rubber to which the stabilizing agent (s) has been added is introduced into a shredder and homogenizer 1.
  • the shredding and homogenizing device 1 comprises a feed and shredding zone 2 and a homogenization zone 3 interconnected, and a shaft 4 passing through said zones, said shaft being provided with rotary knives 5.
  • the feeding and shredding zone 2 comprises an upper part 2a and a lower part 2b.
  • the upper part 2a is an elevated and open part to allow the introduction of natural rubber and stabilizing agents.
  • This upper part 2a is generally square in shape, the length of the sides of which is equal to the diameter formed by the rotary knives 5 of the shaft 4.
  • the walls 6 of this upper part 2a are generally vertical, but can also be inclined to favor the wholesale blo cs of natural rubber. Preferably, the walls 6 are vertical to prevent the natural rubber from remaining on the inclined supply walls.
  • the lower part 2b comprises the first part of the shaft 4.
  • the lower part has a cylindrical bottom in which the shaft 4 is housed.
  • the walls 6 of the upper part 2a may be provided with first fixed knives (not shown) to prevent the natural rubber from rising in the upper part 2a of the feed zone 2.
  • the homogenization zone 3 is in the continuity of the feed and shredding zone 2 and is connected to it. This zone makes it possible to knead and homogenize the natural rubber.
  • This homogenizing zone 3 comprises a sheath 7 inserting the second part of the shaft 4.
  • the sheath 7 is provided with second fixed knives 8.
  • the second fixed knives 8 promote the homogenization and the mechanical work of the natural rubber. These second fixed knives 8 can be positioned on the lower and / or upper part of the sheath. These second fixed knives are removable.
  • the number of second fixed knives 8 may depend on the desired mechanical work. The more the number of second fixed knives is important, the more the mechanical work increases.
  • the rotary knives 5 of the shaft 4 pass on each side of the second fixed knives of the sheath 7.
  • the length of the homogenization zone 3 is variable. It is a function of the desired homogenization time and mechanical work. This length is fixed during the construction of the device.
  • the shredder and homogenizer 1 comprises at the end of the homogenization zone 3 a die plate 9.
  • the die plate 9 has orifices which may be in the form of round holes or oblong holes.
  • the variable opening of the orifices makes it possible to increase or decrease the mechanical work of rubber natural. Reducing the opening of the holes in the die plate 9 also makes it possible to reduce the flow rate in the device 1.
  • the shaft 4 of the device 1 is preferably horizontal. It is supported on both sides of the device 1.
  • a cutting device (not shown) is positioned at the outlet of the die plate 9 to cut the natural rubber into pieces.
  • This cutting device can be fixed on the shaft 4 of the device 1 and rotate at the same speed as the shaft 4.
  • This cutting device is then installed on the shaft 4 leaving the device but may not rotate at the same speed as the shaft 4.
  • This cutting device is driven by an independent motor and can cut smaller pieces than when the cutting system is attached to the shaft of the device as it rotates faster.
  • Examples 1 and 2 which follow are intended to evaluate the corrosiveness of certain stabilizing agents used in the treatment of natural rubber.
  • the tests were conducted at 90 ° C in bottle with a piece of steel.
  • the bottles are placed in an oil bath which keeps the bottle at a temperature of 90 ° C.
  • a metal plate type E24-2NE France AFNOR standard
  • Solutions whose compositions are given in the following table.
  • additional water is made to compensate for the evaporation of the water in order to maintain the concentration of the initial solution. Every 24 hours, the metal plate is weighed to study corrosion.
  • Example 3 The purpose of Example 3 is to evaluate the hysteresis properties of the rubber compositions containing the natural rubbers treated or not treated according to the process according to the invention, as well as to evaluate the effect of the storage of the natural rubbers on their composition. Mooney viscosity.
  • a first series of tests is carried out to compare the corrosion caused by hydroxylamine sulphate and hydroxylamine sulphate neutralized by a strong base, sodium hydroxide.
  • compositions of the solutions tested are given in Table 1.
  • ml, m2, m3, m4 mass of the plate during the measurement, respectively at 24h, 48h, 72h and 96h.
  • Table 2 represents the evolution of the weight of iron weight / initial iron mass as a function of time (in hours) for bottles 1 (curve C1), 2 (curve C2). , 3 (curve C3) and 4 (curve C4).
  • a first series of tests is carried out to compare the corrosion caused by hydroxylamine sulphate and by weak acids of hydroxylamine or dimedone.
  • m l, m2, m3, m4 mass of the plate during the measurement, respectively at 24h, 48h, 72h and 96h.
  • compositions B, C, D, E are examples of rubber compositions comprising a natural rubber treated according to the invention.
  • composition A an untreated natural rubber. according to the invention (composition A), as well as to evaluate the effect of the storage of treated natural rubbers on its Mooney viscosity 1 - Manufacture of rubber compositions:
  • compositions B, C, D and E the natural rubber is pretreated by means of a stabilizing agent by means of two shredding and homogenization devices arranged in series, namely two "prebreakers" connected in series. treated natural rubber comes out of the second prebreaker at 1 10 ° C.
  • the necessary basic constituents are introduced successively into a conventional internal mixer (treated natural rubber). according to the invention or not, reinforcing fillers, other additives), with the exception of the crosslinking system.
  • Thermomechanical work (non-productive phase) is then carried out in one step, which lasts a total of about 3 to 5 min, until a maximum temperature of "fall” of 165 ° C is reached. The mixture thus obtained is recovered and cooled.
  • the final composition thus obtained is then calendered in the form of a sheet or a plate for a characterization in the laboratory.
  • the rubber compositions are characterized after curing as indicated below.
  • Dynamic properties are measured on a viscoanalyzer (Metravib VA4000) according to ASTM D 5992-96.
  • a sample of vulcanized composition (cylindrical specimen 4 mm in thickness and 400 mm 2 in section), subjected to a sinusoidal solicitation in simulated shear alternately, at a frequency of 10 Hz, at a temperature of 60 ° C, to a strain amplitude sweep of 0, 1% to 50%> (forward cycle), then 50%> to 1%) (return cycle): for the forward cycle, the maximum value of the factor is recorded of loss, noted tan (ô) max.
  • tan ( ⁇ ) max (according to a "deformation" sweep at a given temperature) is representative of hysteresis and rolling resistance (plus tan ( ⁇ ) max is low, lower is the hysteresis and therefore the rolling resistance)
  • compositions B, C, D and E have an equivalent hysteresis property compared to that of the reference composition A implementing an NR. with SHA which is very favorable for obtaining a tire with reduced rolling resistance when the composition according to the invention is used as tread.
  • the Mooney viscosities of the natural rubbers treated according to the process according to the invention evolve after storage of the natural rubbers in a manner substantially comparable to that of a natural rubber stabilized with hydroxylamine sulphate, that is to say much less than that of unstabilized natural rubber.
  • the treatment of natural rubber with neutralized hydroxylamine sulfate with a strong base such as sodium hydroxide effectively stabilizes its Mooney viscosity.
  • the natural rubber treatment method according to the invention makes it possible to produce a stabilized natural rubber which gives the rubber compositions hysteresis properties comparable to those conferred by a natural rubber stabilized with hydroxylamine, without the disadvantages of corrosion encountered during stabilization with hydroxylamine sulfate.

Abstract

The invention relates to a process for treating a natural rubber, comprising the following steps: - adding one or more stabilizers to the natural rubber, said natural rubber consisting of at least 80% by weight of natural rubber from cup lump and 0 to 20% by weight of natural rubber from latex, relative to the total weight of natural rubber, said stabilizer(s) being chosen from dimedone or being chosen from weak acid salts of compounds of formula XNH2 and strong acid salts of compounds of formula XNH2 neutralized with a strong base, where X is a group chosen from hydroxyl and hydroxyl (C1-C4 alkyl) groups, and said stabilizer(s) being present respectively in an amount varying from 2.4 mmol to 24 mmol equivalent of dimedone or equivalent of XNH2 per kilogram of natural rubber, then - subjecting the natural rubber to which the stabilizer(s) has (have) been added to mechanical working at a temperature of at least 100°C.

Description

Procédé de préparation d'un caoutchouc naturel stabilisé  Process for preparing stabilized natural rubber
L 'invention se rapporte à un procédé de préparation d 'un caoutchouc naturel traité au moyen de l ' addition d'un agent stabilisant et de l' homogénéisation de l ' ensemble en résultant par un dispositif fournissant un travail mécanique à température élevée. The invention relates to a process for the preparation of a treated natural rubber by means of the addition of a stabilizing agent and the homogenization of the resulting assembly by means of a device which provides mechanical work at elevated temperature.
Il est connu que le caoutchouc naturel a tendance à durcir, et donc à perdre en plasticité, lors de son transport et de son stockage. Cette perte de plasticité se traduit par une augmentation de sa viscosité Mooney. Cette tendance à durcir est due au fait que les protéines du caoutchouc naturel réagissent notamment avec les fonctions carbonyles, et en particulier les fonctions aldéhydes, des chaînes polyisoprène pour former une macrostructure plus importante.  It is known that natural rubber has a tendency to harden, and therefore to lose plasticity during transport and storage. This loss of plasticity results in an increase in its Mooney viscosity. This tendency to harden is due to the fact that the proteins of the natural rubber react in particular with the carbonyl functions, and in particular the aldehyde functions, polyisoprene chains to form a larger macrostructure.
II est connu de compenser ce durcissement du caoutchouc naturel, en abaissant la viscosité du caoutchouc naturel notamment par une plastification de ce caoutchouc naturel au moyen d'un travail mécanique dans un mélangeur interne.  It is known to compensate for this hardening of the natural rubber, by lowering the viscosity of the natural rubber in particular by plasticizing this natural rubber by means of mechanical work in an internal mixer.
Mais ce procédé de plastification présente un coût énergétique important, de l ' ordre de 140 kW/t, et nécessite des investissements importants.  But this plastification process has a significant energy cost, of the order of 140 kW / t, and requires significant investments.
Il est également connu de stabiliser le caoutchouc naturel sec avec des stabilisants, en particulier des composés hydroxylamines ou hydrazides, au moyen de machines de mélange fournissant un travail mécanique et à une température supérieure à 100° C .  It is also known to stabilize dry natural rubber with stabilizers, especially hydroxylamine or hydrazide compounds, by means of mixing machines providing mechanical work and at a temperature above 100 ° C.
La stabilisation du caoutchouc naturel peut également être effectuée en phase latex, par inj ection des stabilisants dans le latex. Le traitement en phase latex présente cependant l 'inconvénient de perdre du stabilisant dans les eaux de coagulation qui sont rejetées dans l ' environnement.  The stabilization of the natural rubber can also be carried out in the latex phase by injection of the stabilizers into the latex. However, the latex phase treatment has the disadvantage of losing stabilizer in the coagulation water which is released into the environment.
Il est également connu de traiter des crêpes ou des granulés de caoutchouc naturel humides par arrosage ou trempage avec des stabilisants. Ces crêpes ou granulés sont ensuite passés dans des extrudeuses et/ou mis directement dans les séchoirs. It is also known to treat pancakes or wet natural rubber granules by watering or dipping with stabilizers. These pancakes or granules are then passed through extruders and / or put directly in the dryers.
Cependant, le traitement des crêpes ou des granulés de caoutchouc naturel humides par arrosage ou trempage avec des stabilisants présente l 'inconvénient de perdre de l ' eau et donc du produit lors du passage dans les crêpeuses ou dans les séchoirs . De plus, pour l ' arrosage, il est nécessaire de manipuler une grande quantité de stabilisant, par exemple de solutions d' hydroxylamines. I l est également possible de retrouver du stabilisant dans les effluents .  However, the treatment of crepes or wet natural rubber granules by watering or soaking with stabilizers has the disadvantage of losing water and therefore the product during passage in the crepe or in the dryers. In addition, for watering, it is necessary to handle a large amount of stabilizer, for example solutions of hydroxylamines. It is also possible to find stabilizer in the effluents.
II est enfin connu de traiter le caoutchouc naturel sec avec des stabilisants. Le caoutchouc naturel et le stabilisant sont mélangés dans des machines fournissant un travail mécanique et de la température, pour disperser et faire réagir le stabilisant avec le caoutchouc naturel. On peut citer le document EP 0 950 485 qui décrit un procédé de séchage du caoutchouc naturel de latex comprenant une étape d' ajout d'un stabilisant, tel que la dimédone, des composés hydrazides ou du sulfate d' hydroxylamine. Ce document mentionne simplement un mélangeur ou une extrudeuse.  It is finally known to treat dry natural rubber with stabilizers. The natural rubber and the stabilizer are mixed in machinery providing mechanical work and temperature, to disperse and react the stabilizer with the natural rubber. There may be mentioned EP 0 950 485 which describes a method for drying natural latex rubber comprising a step of adding a stabilizer, such as dimedone, hydrazide compounds or hydroxylamine sulfate. This document simply mentions a mixer or an extruder.
Le document GB 1373630 décrit la stabilisation du caoutchouc naturel par ajout d'un sulfate d' hydroxylamine sur du caoutchouc naturel à l' état so lide, puis réaction à température supérieure à 1 00°C dans une machine de mélangeage.  GB 1373630 discloses the stabilization of natural rubber by adding hydroxylamine sulfate to natural rubber in the solid state and then reacting at a temperature above 100 ° C in a mixing machine.
Cependant, les so lutions de sulfate d' hydroxylamine peuvent corroder les machines telles que les machines de mélangeage ou les réservoirs de stockage de la solution.  However, solutions of hydroxylamine sulfate can corrode machines such as mixing machines or storage tanks of the solution.
Il existe donc un besoin de disposer d'un procédé de traitement du caoutchouc naturel pendant la phase d'usinage qui présente un gain énergétique par rapport aux procédés de stabilisation usuels avec des hydroxylamines, et qui présente un gain énergétique, de productivité et de coût d' investissement par rapport au procédé de plastification habituel. Ce procédé doit permettre d' éviter les phénomènes de corrosion dans les installations. De plus ce procédé ne doit pas rejeter de sulfate d' hydroxylamine dans les effluents liquides. De plus, les propriétés des compositions comprenant du caoutchouc naturel ainsi traité doivent être comparables à celles des compositions comprenant du caoutchouc naturel plastifié. En particulier, la résistance au roulement, la viscosité Mooney et la rigidité d'une composition contenant un tel caoutchouc naturel doit être comparable à celle obtenue pour une composition contenant un caoutchouc naturel plastifié. There is therefore a need for a process for treating natural rubber during the machining phase, which has an energy gain compared to conventional stabilization processes with hydroxylamines, and which has an energy, productivity and cost saving. investment compared to the usual plasticization process. This process must make it possible to avoid corrosion phenomena in the installations. In addition, this process must not reject hydroxylamine sulphate in the liquid effluents. In addition, the properties of the compositions comprising natural rubber and treated must be comparable to those of the compositions comprising plasticized natural rubber. In particular, the rolling resistance, the Mooney viscosity and the rigidity of a composition containing such a natural rubber must be comparable to that obtained for a composition containing a plasticized natural rubber.
Les demanderesses ont découvert de façon surprenante que le caoutchouc naturel pouvait être traité au moyen d'un procédé comprenant une étape d' addition au caoutchouc naturel majoritairement sous forme de caoutchouc naturel de fond de tasse d'un ou plusieurs agents choisis parmi la dimédone et des composés dérivés d' hydroxylamine particuliers en une quantité spécifique, , et une étape de travail mécanique de l ' ensemble à une température d ' au moins 100 °C, un tel procédé permettant un gain énergétique, de productivité et de coût d' investissement par rapport aux procédés de plastification habituels , tout en permettant d' éviter les phénomènes de corrosion dans les installations.  The Applicants have surprisingly found that natural rubber can be treated by a process comprising a step of adding to the natural rubber predominantly in the form of a natural bottom-cup rubber of one or more agents selected from dimedone and particular hydroxylamine - derived compounds in a specific amount, and a mechanical working step of the assembly at a temperature of at least 100 ° C, such a process allowing energy gain, productivity and investment cost. compared to the usual plastification processes, while avoiding corrosion phenomena in installations.
L 'invention a donc pour obj et un procédé de traitement d 'un caoutchouc naturel, comprenant les étapes suivantes :  The object of the invention is therefore a process for treating a natural rubber, comprising the following steps:
- ajouter au caoutchouc naturel un ou plusieurs agents stabilisants, ledit caoutchouc naturel étant constitué d' au moins 80% en poids de caoutchouc naturel de fond de tasse et de 0 à 20% en poids de caoutchouc naturel de latex, par rapport au poids total de caoutchouc naturel, le ou lesdits agents stabilisants étant la dimédone ou étant choisis parmi les sels d' acide faible de composés de formule XNH2 et les sels d' acide fort de composés de formule XNH2 neutralisés avec une base forte, où X est un groupe choisi parmi les groupes hydroxyle et hydroxyalkyle en C 1 -C 4 , et le ou lesdits agents stabilisants étant présents respectivement en une quantité variant de 2,4 mmo les à 24 mmo les équivalent de dimédone ou équivalent de XNH2 par kilogramme de caoutchouc naturel, puis adding to the natural rubber one or more stabilizing agents, said natural rubber consisting of at least 80% by weight of natural bottom mastic and 0 to 20% by weight of natural latex rubber, based on the total weight of natural rubber, the stabilizing agent (s) being dimedone or being chosen from the weak acid salts of compounds of formula XNH 2 and the strong acid salts of compounds of formula XNH 2 neutralized with a strong base, where X is a group selected from hydroxy and C 1 -C 4 hydroxyalkyl groups, and said stabilizing agent (s) being respectively present in an amount ranging from 2.4 mmoles to 24 mmoles equivalent to dimedone or equivalent of XNH 2 per kilogram of natural rubber and then
soumettre le caoutchouc naturel auquel a été ajouté le ou les agents stabilisants à un travail mécanique à une température d' au moins 100 ° C . Par caoutchouc naturel de fond de tasse, on entend la partie de caoutchouc naturel qui, après saignée de l ' arbre et réco lte dans une tasse, a coagulé sous forme so lide dans cette tasse, puis a subi un travail de nettoyage, d' homogénéisation et de séchage. subjecting the natural rubber to which the stabilizing agent (s) has been added to mechanical work at a temperature of not less than 100 ° C. By natural rubber of the bottom of the cup, is meant the part of natural rubber which, after bleeding from the tree and recoated in a cup, has coagulated in solid form in this cup, and then underwent a cleaning, homogenization and drying.
Par caoutchouc naturel de latex, on entend le caoutchouc naturel qui, après saignée de l' arbre, s ' est écoulé dans la tasse, a été réco lté sous forme liquide et coagulé artificiellement, puis a subi un travail de nettoyage, d' homogénéisation et de séchage.  "Natural latex rubber" means the natural rubber which, after bleeding from the tree, has flowed into the cup, has been reco lted in liquid form and artificially coagulated, then has undergone cleaning, homogenisation and drying.
Le travail de nettoyage, d ' homogénéisation et de séchage comprend généralement une ou plusieurs étapes de réduction de la taille des morceaux de caoutchouc naturel, par exemple au moyen d'un broyeur à marteaux, une ou plusieurs étapes de lavage dans un bac à eau pour éliminer les impuretés et les contaminants, une ou plusieurs étapes de crêpage, une ou plusieurs étapes de mise en miettes et une ou plusieurs étapes de séchage. Puis le caoutchouc naturel est comprimé pour être mis sous forme de pain ou de balle.  The cleaning, homogenization and drying work generally comprises one or more steps of reducing the size of the pieces of natural rubber, for example by means of a hammer mill, one or more washing steps in a water tray for removing impurities and contaminants, one or more crepe steps, one or more crumbling steps, and one or more drying steps. Then the natural rubber is compressed to be put in the form of bread or ball.
Selon un mode de réalisation préféré, le caoutchouc naturel est un caoutchouc naturel de fond de tasse. Cela signifie que le caoutchouc naturel ne contient pas de caoutchouc naturel de latex.  In a preferred embodiment, the natural rubber is a natural cup bottom rubber. This means that natural rubber does not contain natural latex rubber.
De préférence, le caoutchouc naturel utilisé dans le procédé selon l' invention est choisi parmi les caoutchoucs naturels issus de l ' hévéa Brasiliensis.  Preferably, the natural rubber used in the process according to the invention is chosen from the natural rubbers derived from the rubber tree Brasiliensis.
Comme expliqué précédemment, le ou les agents stabilisants peuvent être choisis parmi les sels d' acide faible de composés de formule XNH2. A titre de sels d' acide faible de composés de formule XNH2, on peut citer les sels d' acide faible de l 'hydroxylamine, par l ' exemple l ' acétate d' hydroxylamine et l 'oxalate d 'hydroxylamine. As explained above, the stabilizing agent (s) may be chosen from the weak acid salts of compounds of formula XNH 2 . As the weak acid salts of compounds of formula XNH 2 , mention may be made of the weak acid salts of hydroxylamine, for example hydroxylamine acetate and hydroxylamine oxalate.
Le ou les agents stabilisants peuvent également être choisis parmi les sels d' acide fort de composés de formule XNH2 telle que définie précédemment, neutralisés avec une base forte. A titre de sels d' acide fort de composés de formule XNH2, on peut citer les sels d' acide fort de l ' hydroxylamine, par exemple le sulfate d' hydroxylamine. Selon un premier mode de réalisation, le ou les agents stabilisants sont des sels d'acide fort d'hydroxylamine, neutralisés avec une base forte, la teneur en sel(s) d'acide fort d'hydroxylamine variant de 2,4 mmoles à 24 mmoles équivalent d'hydroxylamine par kilogramme de caoutchouc naturel, la teneur en base forte variant de 0,1 à 2 moles, de préférence de 1 à 2 moles, par moles de sel d'acide fort d'hydroxylamine. The stabilizing agent (s) may also be chosen from the strong acid salts of compounds of formula XNH 2 as defined above, neutralized with a strong base. As the strong acid salts of compounds of formula XNH 2 , mention may be made of the strong acid salts of hydroxylamine, for example hydroxylamine sulfate. According to a first embodiment, the stabilizing agent (s) are hydroxylamine strong acid salts, neutralized with a strong base, the content of hydroxylamine strong acid salt (s) ranging from 2.4 mmol to 24 mmol equivalents of hydroxylamine per kilogram of natural rubber, the content of strong base ranging from 0.1 to 2 moles, preferably 1 to 2 moles, per mole of strong acid salt of hydroxylamine.
Selon un deuxième mode de réalisation, le ou les agents stabilisants sont des sels d'acide faible d'hydroxylamine, et sont présents à une teneur variant de 2,4 mmoles à 24 mmoles équivalent d'hydroxylamine, de préférence de 6 mmoles à 24 mmoles équivalent d'hydroxylamine, de préférence encore de 8 mmoles à 18 mmoles équivalent d'hydroxylamine, par kilogramme de caoutchouc naturel.  According to a second embodiment, the stabilizing agent (s) are weak acid salts of hydroxylamine, and are present in a content ranging from 2.4 mmol to 24 mmol equivalent of hydroxylamine, preferably from 6 mmol to 24 mmol. mmol equivalent of hydroxylamine, more preferably from 8 mmol to 18 mmol equivalent of hydroxylamine, per kilogram of natural rubber.
Selon un troisième mode de réalisation, l'agent stabilisant est la dimédone et est présent à une teneur variant de 2,4 mmoles à 24 mmoles équivalent de dimédone, de préférence de 6 mmoles à 24 mmoles équivalent de dimédone, par kilogramme de caoutchouc naturel.  According to a third embodiment, the stabilizing agent is dimedone and is present in a content ranging from 2.4 mmol to 24 mmol equivalent of dimedone, preferably from 6 mmol to 24 mmol equivalent of dimedone, per kilogram of natural rubber. .
Lorsque le ou les agents stabilisants sont des sels d'acide fort de composés XNH2 tels que définis précédemment, neutralisés avec une base forte, la base forte peut être choisie parmi la soude (hydroxyde de sodium), l'hydroxyde de potassium, de préférence la soude. When the stabilizing agent (s) are strong acid salts of compounds XNH 2 as defined above, neutralized with a strong base, the strong base may be chosen from sodium hydroxide (sodium hydroxide), potassium hydroxide, preferably soda.
Par sel d'acide fort neutralisé avec une base forte, on entend la mise en contact du sel d'acide fort avec la base forte. C'est ce mélange qui est ajouté en tant que stabilisant dans le procédé.  Strong acid salt neutralized with a strong base means contacting the strong acid salt with the strong base. It is this mixture that is added as a stabilizer in the process.
L'ajout du ou des agents stabilisants au caoutchouc naturel peut se faire par arrosage du caoutchouc naturel avec la quantité souhaitée d'agent stabilisant, en général en solution aqueuse, ou bien par trempage du caoutchouc naturel dans une solution d'agent(s) stabilisant(s). De préférence, l'ajout du ou des agents stabilisants au caoutchouc naturel se fait par arrosage.  The addition of the stabilizing agent (s) to the natural rubber can be done by spraying the natural rubber with the desired amount of stabilizing agent, generally in aqueous solution, or by soaking the natural rubber in a solution of agent (s) stabilizer (s). Preferably, the addition of the stabilizing agent (s) to the natural rubber is done by watering.
Après l'étape d'addition au caoutchouc naturel d'un ou plusieurs agents stabilisants, le procédé selon l'invention comprend une étape de travail mécanique à une température d'au moins 100 °C du caoutchouc naturel auquel a été ajouté et le ou les agents stabilisants. After the step of adding to the natural rubber one or more stabilizing agents, the method according to the invention comprises a mechanical working step at a temperature of at least 100 ° C. natural rubber to which has been added and the stabilizing agent (s).
De préférence, le travail mécanique est effectué à une température d' au moins 1 1 0°C .  Preferably, the mechanical work is carried out at a temperature of at least 110 ° C.
Le travail mécanique est de préférence effectué au moyen d 'un ou plusieurs dispositifs de déchiquetage et d' homogénéisation. Un tel dispositif est généralement appelé « prebreaker ».  The mechanical work is preferably carried out by means of one or more shredding and homogenizing devices. Such a device is generally called "prebreaker".
Un tel dispositif a une consommation énergétique de l ' ordre 50 kW/tonne de caoutchouc naturel, alors qu 'un procédé de plastification consomme de l ' ordre de 140 kW/tonne.  Such a device has an energy consumption of the order of 50 kW / ton of natural rubber, whereas a plasticizing process consumes around 140 kW / ton.
Selon un mode de réalisation particulièrement préféré, le travail mécanique est réalisé au moyen de deux dispositifs de déchiquetage et d ' homogénéisation disposés en série.  According to a particularly preferred embodiment, the mechanical work is performed by means of two shredding and homogenization devices arranged in series.
L 'utilisation de deux tels dispositifs est particulièrement avantageuse pour s ' assurer que le caoutchouc naturel soit maintenu à une température d' au moins 100° C pendant un temps suffisant qui permette à l ' agent stabilisant de réagir.  The use of two such devices is particularly advantageous to ensure that the natural rubber is maintained at a temperature of at least 100 ° C for a sufficient time which allows the stabilizing agent to react.
Le travail mécanique réalisé au moyen de deux dispositifs permet également d' atteindre une répartition homogène de l ' additif dans le caoutchouc naturel, cette répartition pouvant être contrôlée par un dosage selon la méthode décrite dans la publication J.nat.Rubb .Res, 3 ( 1 ), 1 -6.  The mechanical work carried out by means of two devices also makes it possible to achieve a homogeneous distribution of the additive in the natural rubber, this distribution being able to be controlled by an assay according to the method described in the publication J.nat.Rubb .Res, 3 (1), 1-6.
L ' étape de travail mécanique présente avantageusement une durée variant de 25 secondes à 3 minutes .  The mechanical working stage advantageously has a duration varying from 25 seconds to 3 minutes.
Le ou les dispositifs de déchiquetage et d'homogénéisation comprennent habituellement chacun une zone d' alimentation et de déchiquetage et une zone d ' homogénéisation reliées entre elles, et un arbre traversant lesdites zones, ledit arbre étant muni de couteaux rotatifs .  The shredding and homogenizing device (s) usually each comprise a feed and shredding zone and a homogenization zone connected to each other, and a shaft passing through said zones, said shaft being provided with rotary knives.
La zone d' alimentation comprend généralement une partie supérieure et une partie inférieure, ladite partie supérieure étant apte à alimenter ladite partie inférieure, ladite partie inférieure comprenant la première partie dudit arbre. Selon un mode de réalisation particulier, les parois de la zone d' alimentation présentent des premiers couteaux fixes . De tels premiers couteaux fixes permettent d ' éviter que l ' ensemble caoutchouc naturel - agent stabilisant ne remonte dans la partie supérieure de la zone d' alimentation une fois qu' il a atteint la partie inférieure de la zone d' alimentation. The feeding zone generally comprises an upper part and a lower part, said upper part being able to feed said lower part, said lower part comprising the first part of said shaft. According to a particular embodiment, the walls of the feed zone have first fixed knives. Such first fixed knives prevent the assembly of natural rubber - stabilizing agent from rising in the upper part of the feed zone once it has reached the lower part of the feed zone.
La zone d ' homogénéisation comprend généralement la seconde partie dudit arbre et un fourreau insérant ladite seconde partie de l ' arbre, ledit fourreau étant muni de seconds couteaux fixes.  The homogenization zone generally comprises the second part of said shaft and a sleeve inserting said second part of the shaft, said sleeve being provided with second fixed blades.
L ' arbre logé dans la partie inférieure de la zone d' alimentation et dans la zone d ' homogénéisation est de préférence horizontal.  The shaft housed in the lower part of the feed zone and in the homogenization zone is preferably horizontal.
La vitesse de l ' arbre varie avantageusement de 20 à 1 00 tours/min, de préférence de 20 à 60 tours/min.  The speed of the shaft advantageously varies from 20 to 100 rpm, preferably from 20 to 60 rpm.
Le ou les dispositifs de déchiquetage et d'homogénéisation présentent habituellement chacun une plaque filière en bout de la zone d'homogénéisation, ladite plaque filière présentant des orifices .  The chipping and homogenizing device or devices usually each have a die plate at the end of the homogenization zone, said die plate having orifices.
Ces orifices peuvent être sous forme de trous ronds ou de trous oblongs ou de trous triangulaires .  These holes may be in the form of round holes or oblong holes or triangular holes.
Avantageusement, ces orifices présentent une ouverture variable. La variation de l ' ouverture des orifices permet d' augmenter ou de diminuer le travail mécanique fourni au caoutchouc naturel ou de faire varier le débit dans le dispositif.  Advantageously, these orifices have a variable opening. The variation of the opening of the orifices makes it possible to increase or decrease the mechanical work provided to the natural rubber or to vary the flow rate in the device.
La température dans la zone de déchiquetage et d'homogénéisation peut être réglée en faisant varier le travail mécanique, en utilisant les moyens suivants, seuls ou en combinaison : nombre de couteaux fixes, nombre de couteaux rotatifs, longueur de la zone de déchiquetage et d'homogénéisation, fermeture de la plaque filière, débit de caoutchouc naturel, chauffage du corps du dispositif de déchiquetage et d' homogénéisation.  The temperature in the shredding and homogenization zone can be adjusted by varying the mechanical work, using the following means, alone or in combination: number of fixed knives, number of rotary knives, length of shredding zone and homogenization, closure of the die plate, flow of natural rubber, heating of the body of the shredding device and homogenization.
L ' étape de travail mécanique peut être suivie d'une étape de coupe du caoutchouc naturel traité .  The mechanical working step may be followed by a cutting step of the treated natural rubber.
L ' étape de coupe peut être effectuée au moyen d'un dispositif de coupe positionné en sortie du dispositif conférant le travail mécanique, en particulier ou du ou des dispositifs de déchiquetage et d'homogénéisation. The cutting step can be performed by means of a cutting device positioned at the output of the device conferring the work mechanical, in particular or the shredding and homogenization device or devices.
Un autre obj et de l' invention est un caoutchouc naturel traité susceptible d' être obtenu par le procédé obj et de l ' invention.  Another object of the invention is a treated natural rubber which can be obtained by the process obj and of the invention.
Un autre obj et de l'invention est une composition de caoutchouc renforcée à base d'au moins une charge renforçante et d'une matrice élastomère comprenant au moins un caoutchouc naturel traité selon l ' invention.  Another object of the invention is a reinforced rubber composition based on at least one reinforcing filler and an elastomeric matrix comprising at least one natural rubber treated according to the invention.
Par l'expression composition "à base de" , il faut entendre une composition comportant le mélange et/ou le produit de réaction des différents constituants utilisés, certains de ces constituants de base étant susceptibles de, ou destinés à, réagir entre eux, au moins en partie, lors des différentes phases de fabrication de la composition, en particulier au cours de sa réticulation ou vulcanisation.  By the term "composition-based" is meant a composition comprising the mixture and / or the reaction product of the various constituents used, some of these basic constituents being capable of or intended to react with one another, less in part, during the various phases of manufacture of the composition, in particular during its crosslinking or vulcanization.
La composition de caoutchouc renforcée selon l'invention peut se présenter à l'état réticulé ou à l'état non réticulé, autrement dit réticulable.  The reinforced rubber composition according to the invention may be in the crosslinked state or in the uncrosslinked state, that is to say crosslinkable.
La matrice élastomère présente dans la composition selon l' invention peut également, outre le caoutchouc naturel traité selon l' invention, comprendre au moins un autre élastomère diénique.  The elastomer matrix present in the composition according to the invention may also, in addition to the natural rubber treated according to the invention, comprise at least one other diene elastomer.
Dans le cas d'un coupage avec au moins un autre élastomère diénique, la fraction massique du caoutchouc naturel traité selon l'invention dans la matrice élastomère est majoritaire et de préférence supérieure ou égale à 10% en masse de la masse totale de la matrice, encore plus préférentiellement supérieure ou égale 50% en masse de la masse totale de la matrice, encore plus préférentiellement supérieure ou égale 70% . La fraction massique du caoutchouc naturel traité selon l'invention dans la matrice élastomère est de préférence inférieure ou égale à 85 % en masse de la masse totale de la matrice. On appelle fraction massique majoritaire selon l'invention la fraction massique la plus élevée du coupage.  In the case of a blend with at least one other diene elastomer, the mass fraction of the natural rubber treated according to the invention in the elastomer matrix is predominant and preferably greater than or equal to 10% by weight of the total mass of the matrix. more preferably still greater than or equal to 50% by weight of the total mass of the matrix, even more preferably greater than or equal to 70%. The mass fraction of the natural rubber treated according to the invention in the elastomer matrix is preferably less than or equal to 85% by weight of the total mass of the matrix. The majority mass fraction according to the invention is the highest mass fraction of the blend.
Par élastomère diénique, doit être compris selon l'invention tout élastomère synthétique issu au moins en partie de monomères diènes. Plus particulièrement, par élastomère diénique, on entend tout homopolymère obtenu par polymérisation d'un monomère diène conjugué ayant 4 à 12 atomes de carbone, ou tout copolymère obtenu par copolymérisation d'un ou plusieurs diènes conjugués entre eux ou avec un ou plusieurs composés vinylaromatiques ayant de 8 à 20 atomes de carbone. Dans le cas de copolymères, ceux-ci contiennent de 20 % à 99 % en masse d'unités diéniques, et de 1 à 80 % en masse d'unités vinylaromatiques. By diene elastomer, it should be understood according to the invention any synthetic elastomer derived at least in part from monomers dienes. More particularly, by diene elastomer, we mean everything homopolymer obtained by polymerization of a conjugated diene monomer having 4 to 12 carbon atoms, or any copolymer obtained by copolymerization of one or more conjugated dienes with each other or with one or more vinylaromatic compounds having from 8 to 20 carbon atoms. In the case of copolymers, these contain from 20% to 99% by weight of diene units, and from 1 to 80% by weight of vinylaromatic units.
L'élastomère diénique constituant une partie de la matrice élastomère de la composition selon l'invention est choisi préférentiellement dans le groupe des élastomères diéniques fortement insaturés constitué par les polybutadiènes (BR), les polyisoprènes (IR) de synthèse, le caoutchouc naturel (NR) différent du caoutchouc naturel traité selon l' invention, les copolymères de butadiène, les copolymères d'isoprène et les mélanges de ces élastomères. De tels copolymères sont plus préférentiellement choisis dans le groupe constitué par les copolymères de butadiène-styrène (SBR), les copolymères d' isoprène-butadiène (BIR), les copolymères d'isoprène- styrène (SIR) et les copolymères d' isoprène-butadiène-styrène (SBIR) . On peut également envisager un coupage avec tout élastomère synthétique autre que diénique, voire avec tout polymère autre qu'élastomère, par exemple un polymère thermoplastique.  The diene elastomer constituting a part of the elastomer matrix of the composition according to the invention is preferably chosen from the group of highly unsaturated diene elastomers consisting of polybutadienes (BR), synthetic polyisoprenes (IR) and natural rubber (NR). ) different from the natural rubber treated according to the invention, butadiene copolymers, isoprene copolymers and mixtures of these elastomers. Such copolymers are more preferably selected from the group consisting of butadiene-styrene copolymers (SBR), isoprene-butadiene copolymers (BIR), isoprene-styrene copolymers (SIR) and isoprene-copolymers. butadiene-styrene (SBIR). It is also possible to cut with any synthetic elastomer other than diene, or with any other polymer other than elastomer, for example a thermoplastic polymer.
Plus préférentiellement, la matrice élastomère est uniquement constituée du caoutchouc naturel traité selon l ' invention.  More preferably, the elastomeric matrix consists solely of the natural rubber treated according to the invention.
La composition de caoutchouc de l'invention comprend, outre au moins une matrice élastomère telle que décrit ci-dessus, au moins une charge renforçante.  The rubber composition of the invention comprises, in addition to at least one elastomeric matrix as described above, at least one reinforcing filler.
On peut utiliser tout type de charge renforçante connue pour ses capacités à renforcer une composition de caoutchouc utilisable pour la fabrication de bandes de roulement de pneumatiques, par exemple du noir de carbone, une charge inorganique renforçante telle que de la silice à laquelle est associé de manière connue un agent de couplage, ou encore un mélange de ces deux types de charge.  It is possible to use any type of reinforcing filler known for its ability to reinforce a rubber composition that can be used for manufacturing tire treads, for example carbon black, a reinforcing inorganic filler such as silica with which it is associated with known manner a coupling agent, or a mixture of these two types of load.
Comme noirs de carbone conviennent tous les noirs de carbone, utilisés individuellement ou sous forme de mélanges, notamment les noirs du type HAF, ISAF, SAF conventionnellement utilisés dans les bandes de roulement des pneumatiques (noirs dits de grade pneumatique) . Parmi ces derniers, on citera plus particulièrement les noirs de carbone renforçants des séries 100, 200 ou 300 (grades ASTM), comme par exemple les noirs N I 15 , N 134 , N234, N326, N330, N339, N347, N375. Les noirs de carbone pourraient être par exemp le déj à incorporés à l'élastomère isoprénique sous la forme d'un masterbatch (voir par exemple demandes WO 97/36724 ou WO 99/ 16600) . Suitable carbon blacks are all carbon blacks, used individually or in the form of mixtures, especially those black type HAF, ISAF, SAF conventionally used in the treads of tires (so-called pneumatic grade black). Among the latter, mention will be made more particularly of reinforcing carbon blacks of the 100, 200 or 300 series (ASTM grades), for example blacks NI 15, N 134, N 234, N 326, N 30 O, N 339, N 347, N 375. The carbon blacks could for example be already incorporated into the isoprene elastomer in the form of a masterbatch (see for example WO 97/36724 or WO 99/16600).
Comme charge inorganique renforçante, doit être entendu dans la présente demande, par définition, toute charge inorganique ou minérale quelles que soient sa couleur et son origine (naturelle ou de synthèse), capable de renforcer à elle seule, sans autre moyen qu' un agent de couplage intermédiaire, une composition de caoutchouc destinée à la fabrication de pneumatiques; une telle charge se caractérise généralement, de manière connue, par la présence de groupes hydroxyle (-OH) à sa surface.  As reinforcing inorganic filler, is meant by the present application, by definition, any inorganic or inorganic filler whatever its color and its origin (natural or synthetic), capable of reinforcing on its own, without any other means than an agent intermediate coupling, a rubber composition for the manufacture of tires; such a filler is generally characterized, in known manner, by the presence of hydroxyl groups (-OH) on its surface.
Comme charges inorganiques renforçantes conviennent notamment des charges minérales du type siliceux, en particulier de la silice (S1O2) , ou du type alumineuse, en particulier de l'alumine (AI2O3) . La silice utilisée peut être toute silice renforçante connue de l'homme du métier, notamment toute silice précipitée ou pyrogénée présentant une surface BET ainsi qu'une surface spécifique CTAB toutes deux inférieures à 450 m2/g, de préférence de 30 à 400 m2/g, notamment entre 60 et 300 m2/g. On citera également les charges minérales du type alumineux, en particulier de l'alumine (AI2O3) ou des (oxyde)hydroxydes d'aluminium, ou encore des oxydes de titane renforçants, par exemp le décrits dans US 6 610 261 et US 6 747 087. Comme charges renforçantes conviennent également des charges renforçantes d'une autre nature, notamment du noir de carbone, dès lors que ces charges renforçantes seraient recouvertes d'une couche siliceuse, ou bien comporteraient à leur surface des sites fonctionnels, notamment hydroxyles, nécessitant l'utilisation d'un agent de couplage pour établir la liaison entre la charge et l'élastomère. A titre d'exemple, on peut citer par exemp le des noirs de carbone pour pneumatiques tels que décrits par exemp le dans les documents brevet WO 96/37547, WO 99/28380. Suitable reinforcing inorganic fillers are mineral fillers of the siliceous type, in particular of silica (SiO 2), or of the aluminous type, in particular alumina (Al 2 O 3). The silica used may be any 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 m2 / g. Mention may also be made of mineral fillers of the aluminous type, in particular alumina (Al 2 O 3) or aluminum (oxide) hydroxides, or reinforcing titanium oxides, for example described in US 6,610,261 and US 6,747. 087. Reinforcing fillers of another nature, in particular carbon black, are also suitable as reinforcing fillers, provided that these reinforcing fillers are covered with a siliceous layer, or else comprise on their surface functional sites, in particular hydroxyl sites, requiring the use of a coupling agent to establish the bond between the filler and the elastomer. As for example, there may be mentioned, for example, carbon blacks for tires as described for example in the patent documents WO 96/37547 and WO 99/28380.
L'état physique sous lequel se présente la charge inorganique renforçante est indifférent, que ce soit sous forme de poudre, de microperles, de granulés, de billes ou toute autre forme densifiée appropriée. Bien entendu, on entend également par charge inorganique renforçante des mélanges de différentes charges renforçantes, en particulier de charges siliceuses hautement dispersibles telles que décrites précédemment.  The physical state in which the reinforcing inorganic filler is present is indifferent whether in the form of powder, microbeads, granules, beads or any other suitable densified form. Of course, the term "reinforcing inorganic filler" also refers to mixtures of different reinforcing fillers, in particular highly dispersible siliceous fillers as described above.
De manière préférentielle, le taux de charge renforçante totale (noir de carbone et/ou autre charge renforçante telle que silice) est compris entre 10 et 200 pce, plus préférentiellement entre 30 et 1 50 pce, et encore plus préférentiellement entre 70 et 130 pce, l'optimum étant de manière connue différent selon les applications particulières visées.  Preferably, the content of total reinforcing filler (carbon black and / or other reinforcing filler such as silica) is between 10 and 200 phr, more preferably between 30 and 150 phr, and even more preferentially between 70 and 130 phr. , the optimum being in a known manner different according to the particular applications concerned.
Selon une variante de l'invention, la charge renforçante est majoritairement autre que du noir de carbone, c'est-à-dire qu'elle comprend plus de 50% en poids du poids total de la charge, d'une ou de plusieurs charges autres que du noir de carbone, notamment une charge inorganique renforçante telle que la silice, voire elle est exclusivement constituée d'une telle charge.  According to a variant of the invention, the reinforcing filler is predominantly other than carbon black, that is to say it comprises more than 50% by weight of the total weight of the filler, of one or more fillers other than carbon black, especially a reinforcing inorganic filler such as silica, or it consists exclusively of such a filler.
Selon cette variante, lorsque du noir de carbone est également présent, il peut être utilisé à un taux inférieur à 20 pce, plus préférentiellement inférieur à 10 pce (par exemple entre 0,5 et 20 pce, notamment de 1 à 10 pce) .  According to this variant, when carbon black is also present, it may be used at a level of less than 20 phr, more preferably less than 10 phr (for example between 0.5 and 20 phr, in particular from 1 to 10 phr).
Selon une autre variante de l'invention, on utilise une charge renforçante comportant majoritairement du noir de carbone, et optionnellement de la silice ou une autre charge inorganique.  According to another variant of the invention, a reinforcing filler comprising predominantly carbon black and optionally silica or other inorganic filler is used.
Lorsque la charge renforçante comprend une charge nécessitant l'utilisation d'un agent de couplage pour établir la liaison entre la charge et l'élastomère, la composition de caoutchouc selon l 'invention comprend en outre, de manière classique, un agent susceptible d'assurer efficacement cette liaison. Lorsque la silice est présente dans la composition à titre de charge renforçante, on peut utiliser comme agents de couplage des organosilanes, notamment des alkoxysilanes polysulfurés ou des mercaptosilanes, ou encore des polyorganosiloxanes au moins bifonctionnels. When the reinforcing filler comprises a filler requiring the use of a coupling agent to establish the bond between the filler and the elastomer, the rubber composition according to the invention further comprises, in a conventional manner, an agent capable of effectively provide this link. When silica is present in as the reinforcing filler, organosilanes may be used as coupling agents, especially polysulfurized alkoxysilanes or mercaptosilanes, or at least bifunctional polyorganosiloxanes.
Dans la composition selon l' invention, le taux d' agent de couplage est avantageusement inférieur à 20 pce, étant entendu qu' il est en général souhaitable d' en utiliser le moins possible. Son taux est préférentiellement compris entre 0,5 et 12 pce. La présence de l'agent de couplage dépend de celle de la charge inorganique renforçante. Son taux est aisément ajusté par l'homme du métier selon le taux de cette charge; il est typiquement de l'ordre de 0,5 % à 15 % en poids par rapport à la quantité de charge inorganique renforçante autre que du noir de carbone.  In the composition according to the invention, the level of coupling agent is advantageously less than 20 phr, it being understood that it is generally desirable to use as little as possible. Its rate is preferably between 0.5 and 12 phr. The presence of the coupling agent depends on that of the reinforcing inorganic filler. Its rate is easily adjusted by the skilled person according to the rate of this charge; it is typically of the order of 0.5% to 15% by weight relative to the amount of reinforcing inorganic filler other than carbon black.
La composition de caoutchouc selon l'invention peut également contenir, en complément des agents de couplage, des activateurs de couplage, des agents de recouvrement des charges ou plus généralement des agents d'aide à la mise en œuvre susceptibles de manière connue, grâce à une amélioration de la dispersion de la charge dans la matrice de caoutchouc et à un abaissement de la viscosité de la composition, d'améliorer sa faculté de mise en œuvre à l'état cru, ces agents étant par exemp le des silanes hydro lysables tels que des alkylalkoxysilanes, des polyo ls, des polyéthers, des aminés primaires , secondaires ou tertiaires, des polyorganosiloxanes hydroxylés ou hydro lysables.  The rubber composition according to the invention may also contain, in addition to the coupling agents, coupling activators, charge-recovery agents or, more generally, processing aid agents which can be used in known manner, thanks to an improvement of the dispersion of the filler in the rubber matrix and a lowering of the viscosity of the composition, to improve its ability to use in the green state, these agents being for example the hydrolysable silanes such as alkylalkoxysilanes, polyols, polyethers, primary, secondary or tertiary amines, hydroxylated or hydrolyzable polyorganosiloxanes.
Les compositions de caoutchouc conformes à l'invention peuvent également contenir, des charges organiques renforçantes qui peuvent remplacer tout ou partie des noirs de carbone ou des autres charges inorganiques renforçantes décrites plus haut. Comme exemples de charges organiques renforçantes, on peut citer les charges organiques de polyvinyle fonctionnalisé telles que décrites dans les demandes WO-A-2006/069792, WO-A-2006/069793 , WO-A- 2008/003434 et WO-A-2008/003435.  The rubber compositions in accordance with the invention may also contain reinforcing organic fillers which may replace all or part of the carbon blacks or other reinforcing inorganic fillers described above. Examples of reinforcing organic fillers that may be mentioned include functionalized polyvinyl organic fillers as described in applications WO-A-2006/069792, WO-A-2006/069793, WO-A-2008/003434 and WO-A 2008/003435.
La composition de caoutchouc selon l'invention peut comporter également tout ou partie des additifs usuels habituellement utilisés dans les compositions d'élastomères destinées à la fabrication de pneumatiques, comme par exemple des pigments, des charges non renforçantes, des agents de protection tels que cires anti-ozone, anti- ozonants chimiques, anti-oxydants, des agents anti-fatigue, des agents plastifiants, des résines renforçantes ou plastifiantes, des accepteurs (par exemp le résine phéno lique novo laque) ou des donneurs de méthylène (par exemp le HMT ou H3M) tels que décrits par exemple dans la demande WO 02/ 1 0269, un système de réticulation à base soit de soufre, soit de donneurs de soufre et/ou de peroxyde et/ou de bismaléimides, des accélérateurs de vulcanisation, des activateurs de vulcanisation. The rubber composition according to the invention may also comprise all or part of the usual additives usually used. in elastomer compositions for the manufacture of tires, such as, for example, pigments, non-reinforcing fillers, protective agents such as anti-ozone waxes, chemical antiozonants, anti-oxidants, anti-fatigue agents, plasticizing agents, reinforcing or plasticizing resins, acceptors (for example novo lacquer phenolic resin) or methylene donors (for example HMT or H3M) as described, for example, in application WO 02/1 0269, a crosslinking system based on either sulfur, or sulfur and / or peroxide donors and / or bismaleimides, vulcanization accelerators, vulcanization activators.
La composition est fabriquée dans des mélangeurs appropriés , en utilisant deux phases de préparation successives bien connues de l'homme du métier : une première phase de travail ou malaxage thermomécanique (phase dite "non-productive") à haute température, jusqu'à une température maximale comprise entre 1 10° C et 190°C, de préférence entre 130°C et 1 80° C, suivie d'une seconde phase de travail mécanique (phase dite "productive") jusqu'à une plus basse température, typiquement inférieure à 1 10°C, par exemple entre 40° C et 100°C, phase de finition au cours de laquelle est incorporé le système de réticulation.  The composition is 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 1 10 ° C and 190 ° C, preferably between 130 ° C and 1 80 ° C, followed by a second mechanical working phase (so-called "productive" phase) to a lower temperature, typically less than 1 10 ° C, for example between 40 ° C and 100 ° C, finishing phase during which is incorporated the crosslinking system.
Le procédé de préparation d'une composition selon l' invention, comprend généralement :  The process for preparing a composition according to the invention generally comprises:
(i) la réalisation, à une température maximale comprise entre 130 °C et 200 °C , d'un premier temps de travail thermo-mécanique des constituants de la composition comprenant le caoutchouc naturel traité selon l' invention et une charge renforçante, à l ' exception d'un système de réticulation, puis  (I) the production, at a maximum temperature of between 130 ° C. and 200 ° C., of a first thermomechanical working time of the constituents of the composition comprising the natural rubber treated according to the invention and a reinforcing filler, with the exception of a crosslinking system, then
(ii) la réalisation, à une température inférieure à ladite température maximale dudit premier temps, d'un second temps de travail mécanique au cours duquel est incorporé ledit système de réticulation.  (ii) the production, at a temperature below said maximum temperature of said first time, of a second mechanical working time during which said crosslinking system is incorporated.
L'invention a également pour obj et un article semi-fini en caoutchouc pour pneumatique, comprenant une composition de caoutchouc selon l' invention, réticulable ou réticulée, ou constitué d'une telle composition. The invention also relates to a semi-finished article of rubber for a tire, comprising a composition of rubber according to the invention, crosslinkable or crosslinked, or consisting of such a composition.
La composition finale ainsi obtenue peut ensuite être calandrée, par exemp le sous la forme d'une feuille, d'une plaque ou encore extrudée, par exemple pour former un profilé de caoutchouc utilisable comme produit semi-fini en caoutchouc destiné au pneumatique.  The final composition thus obtained may then be calendered, for example in the form of a sheet, a plate or extruded, for example to form a rubber profile usable as a semi-finished rubber product for the tire.
L'invention a donc pour obj et un pneumatique comportant un article semi-fini selon l' invention, en particulier une bande de roulement.  The invention is therefore obj and a tire comprising a semi-finished article according to the invention, in particular a tread.
D ' autres buts, caractéristiques et avantages de la présente invention apparaîtront encore plus clairement à la lecture de la description suivante, donnée uniquement à titre d' exemple non limitatif, et faite en référence à la figure 1 qui représente un dispositif de déchiquetage et d' homogénéisation.  Other objects, features and advantages of the present invention will emerge even more clearly on reading the following description, given solely by way of nonlimiting example, and with reference to FIG. 1 which represents a shredding and shredding device. homogenization.
Le caoutchouc naturel auquel a été ajouté le ou les agents stabilisants est introduit dans un dispositif de déchiquetage et d'homogénéisation 1 .  The natural rubber to which the stabilizing agent (s) has been added is introduced into a shredder and homogenizer 1.
Le dispositif de déchiquetage et d' homogénéisation 1 comprend une zone d' alimentation et de déchiquetage 2 et une zone de d'homogénéisation 3 reliées entre elles, et un arbre 4 traversant lesdites zones, ledit arbre étant muni de couteaux rotatifs 5.  The shredding and homogenizing device 1 comprises a feed and shredding zone 2 and a homogenization zone 3 interconnected, and a shaft 4 passing through said zones, said shaft being provided with rotary knives 5.
La zone d' alimentation et de déchiquetage 2 comprend une partie supérieure 2a et une partie inférieure 2b .  The feeding and shredding zone 2 comprises an upper part 2a and a lower part 2b.
La partie supérieure 2a est une partie surélevée et ouverte pour permettre l ' introduction du caoutchouc naturel et des agents stabilisants. Cette partie supérieure 2a est généralement de forme carrée dont la longueur des côtés est égale au diamètre formé par les couteaux rotatifs 5 de l ' arbre 4. Les parois 6 de cette partie supérieure 2a sont généralement verticales, mais peuvent également être inclinées pour favoriser l ' alimentation de gros blo cs de caoutchouc naturel. De préférence, les parois 6 sont verticales pour éviter que le caoutchouc naturel ne reste co llé sur des parois d' alimentation qui seraient inclinées. La partie inférieure 2b comprend la première partie de l ' arbre 4. La partie inférieure présente un fond cylindrique dans lequel l ' arbre 4 vient se loger. The upper part 2a is an elevated and open part to allow the introduction of natural rubber and stabilizing agents. This upper part 2a is generally square in shape, the length of the sides of which is equal to the diameter formed by the rotary knives 5 of the shaft 4. The walls 6 of this upper part 2a are generally vertical, but can also be inclined to favor the wholesale blo cs of natural rubber. Preferably, the walls 6 are vertical to prevent the natural rubber from remaining on the inclined supply walls. The lower part 2b comprises the first part of the shaft 4. The lower part has a cylindrical bottom in which the shaft 4 is housed.
A cause de la gravité, les blo cs de caoutchouc naturel sont toujours en contact avec les couteaux rotatifs 5 de l ' arbre 4, et sont donc facilement attrapés pour être déchiquetés.  Due to gravity, the natural rubber blocks are always in contact with the rotary knives 5 of the shaft 4, and are therefore easily caught to be shredded.
Les parois 6 de la partie supérieure 2a peuvent être munies de premiers couteaux fixes (non représentés) pour éviter que le caoutchouc naturel ne remonte dans la partie supérieure 2a de la zone d' alimentation 2.  The walls 6 of the upper part 2a may be provided with first fixed knives (not shown) to prevent the natural rubber from rising in the upper part 2a of the feed zone 2.
La zone d ' homogénéisation 3 est dans la continuité de la zone d' alimentation et de déchiquetage 2 et est reliée à elle. Cette zone permet de malaxer et d' homogénéiser le caoutchouc naturel.  The homogenization zone 3 is in the continuity of the feed and shredding zone 2 and is connected to it. This zone makes it possible to knead and homogenize the natural rubber.
Cette zone d ' homogénéisation 3 comprend un fourreau 7 insérant la seconde partie de l ' arbre 4. Le fourreau 7 est muni de seconds couteaux fixes 8. Les seconds couteaux fixes 8 favorisent l' homo généisation et le travail mécanique du caoutchouc naturel. Ces seconds couteaux fixes 8 peuvent être positionnés sur la partie inférieure et/ou supérieure du fourreau. Ces seconds couteaux fixes sont amovibles. Le nombre de seconds couteaux fixes 8 peut dépendre du travail mécanique souhaité. Plus le nombre de seconds couteaux fixes est important, plus le travail mécanique augmente. Les couteaux rotatifs 5 de l ' arbre 4 passent de chaque côté des seconds couteaux fixes du fourreau 7.  This homogenizing zone 3 comprises a sheath 7 inserting the second part of the shaft 4. The sheath 7 is provided with second fixed knives 8. The second fixed knives 8 promote the homogenization and the mechanical work of the natural rubber. These second fixed knives 8 can be positioned on the lower and / or upper part of the sheath. These second fixed knives are removable. The number of second fixed knives 8 may depend on the desired mechanical work. The more the number of second fixed knives is important, the more the mechanical work increases. The rotary knives 5 of the shaft 4 pass on each side of the second fixed knives of the sheath 7.
La longueur de la zone d ' homogénéisation 3 est variable. Elle est fonction du temps d'homogénéisation et du travail mécanique souhaités . Cette longueur est fixée lors de la construction du dispositif.  The length of the homogenization zone 3 is variable. It is a function of the desired homogenization time and mechanical work. This length is fixed during the construction of the device.
Le dispositif de déchiquetage et d' homogénéisation 1 comprend en bout de la zone d' homogénéisation 3 une plaque filière 9. La plaque filière 9 présente des orifices qui peuvent être sous la forme de trous ronds ou de trous oblongs . L ' ouverture variable des orifices permet d' augmenter ou de diminuer le travail mécanique du caoutchouc naturel. La réduction de l'ouverture des trous de la plaque filière 9 permet également de diminuer le débit dans le dispositif 1. The shredder and homogenizer 1 comprises at the end of the homogenization zone 3 a die plate 9. The die plate 9 has orifices which may be in the form of round holes or oblong holes. The variable opening of the orifices makes it possible to increase or decrease the mechanical work of rubber natural. Reducing the opening of the holes in the die plate 9 also makes it possible to reduce the flow rate in the device 1.
L'arbre 4 du dispositif 1 est préférentiellement horizontal. Il est soutenu de part et d'autre du dispositif 1.  The shaft 4 of the device 1 is preferably horizontal. It is supported on both sides of the device 1.
Un dispositif de coupe (non représenté) est positionné en sortie de la plaque filière 9 pour couper le caoutchouc naturel en morceaux.  A cutting device (not shown) is positioned at the outlet of the die plate 9 to cut the natural rubber into pieces.
Ce dispositif de coupe peut être fixé sur l'arbre 4 du dispositif 1 et tourner à la même vitesse que l'arbre 4.  This cutting device can be fixed on the shaft 4 of the device 1 and rotate at the same speed as the shaft 4.
Il est possible d'avoir un dispositif de coupe indépendant de l'arbre 4 du dispositif. Ce dispositif de coupe est alors installé sur l'arbre 4 sortant du dispositif mais peut ne pas tourner à la même vitesse que l'arbre 4. Ce dispositif de coupe est entraîné par un moteur indépendant et permet de couper des morceaux plus petits que lorsque le système de coupe est fixé à l'arbre du dispositif car il tourne plus vite.  It is possible to have a cutting device independent of the shaft 4 of the device. This cutting device is then installed on the shaft 4 leaving the device but may not rotate at the same speed as the shaft 4. This cutting device is driven by an independent motor and can cut smaller pieces than when the cutting system is attached to the shaft of the device as it rotates faster.
L'invention ainsi que ses avantages seront aisément compris à la lumière de la description et des exemples de réalisation qui suivent, ainsi que de la figure 2 relative à l'exemple 1 qui représente l'évolution de la masse d'une plaque d'acier en fonction du temps, et de la figure 3 relative à l'exemple 2 qui représente l'évolution de la masse d'une plaque d'acier en fonction du temps.  The invention as well as its advantages will be readily understood in the light of the description and the following exemplary embodiments, as well as of FIG. 2 relating to example 1 which represents the evolution of the mass of a plate of steel as a function of time, and of FIG. 3 relating to example 2 which represents the evolution of the mass of a steel plate as a function of time.
Exemples Les exemples 1 et 2 qui suivent ont pour objet d'évaluer le caractère corrosif de certains agents stabilisants utilisés dans le traitement du caoutchouc naturel. Examples Examples 1 and 2 which follow are intended to evaluate the corrosiveness of certain stabilizing agents used in the treatment of natural rubber.
Les essais ont été menés à 90°C en bouteille avec une pièce en acier. Les bouteilles sont placées dans un bain d'huile qui permet de maintenir la bouteille à la température de 90°C. Dans une bouteille, une plaque de métal type E24-2NE (norme France AFNOR) est plongée dans des solutions dont les compositions sont données dans le tableau suivant. Au cours du test, des appoints d'eau sont réalisés pour compenser l'évaporation de l'eau afin de conserver la concentration de la solution initiale. Toutes les 24 heures, la plaque de métal est pesée pour étudier la corrosion. The tests were conducted at 90 ° C in bottle with a piece of steel. The bottles are placed in an oil bath which keeps the bottle at a temperature of 90 ° C. In a bottle, a metal plate type E24-2NE (France AFNOR standard) is immersed in solutions whose compositions are given in the following table. During the test, additional water is made to compensate for the evaporation of the water in order to maintain the concentration of the initial solution. Every 24 hours, the metal plate is weighed to study corrosion.
L'exemple 3 a pour objet d'évaluer les propriétés d'hystérèse des compositions de caoutchouc contenant les caoutchoucs naturels traités ou non selon le procédé conforme à l'invention, ainsi que d'évaluer l'effet du stockage des caoutchoucs naturels sur leur viscosité Mooney. The purpose of Example 3 is to evaluate the hysteresis properties of the rubber compositions containing the natural rubbers treated or not treated according to the process according to the invention, as well as to evaluate the effect of the storage of the natural rubbers on their composition. Mooney viscosity.
Exemple 1 Example 1
Une première série d'essais est réalisée pour comparer la corrosion occasionnée par le sulfate d'hydroxylamine et par le sulfate d'hydroxylamine neutralisé par une base forte, la soude. A first series of tests is carried out to compare the corrosion caused by hydroxylamine sulphate and hydroxylamine sulphate neutralized by a strong base, sodium hydroxide.
Les compositions des solutions testées sont données dans le tableau 1.  The compositions of the solutions tested are given in Table 1.
Tableau 1 Table 1
Figure imgf000018_0001
Figure imgf000018_0001
SHA : sulfate d'hydroxylamine  SHA: hydroxylamine sulfate
Les résultats sont donnés dans le tableau 2. Tableau 2 The results are given in Table 2. Table 2
Figure imgf000019_0001
Figure imgf000019_0001
mO : masse initiale de la plaque  mO: initial mass of the plate
ml, m2, m3, m4 : masse de la plaque lors de la mesure, respectivement à 24h, 48h, 72h et 96h.  ml, m2, m3, m4: mass of the plate during the measurement, respectively at 24h, 48h, 72h and 96h.
Les résultats du tableau 2 sont également illustrés sur la figure 2 qui représente l'évolution du rapport masse de fer pesée/masse de fer initiale en fonction du temps (en heure) pour les bouteilles 1 (courbe Cl), 2 (courbe C2), 3 (courbe C3) et 4 (courbe C4). The results in Table 2 are also illustrated in FIG. 2, which represents the evolution of the weight of iron weight / initial iron mass as a function of time (in hours) for bottles 1 (curve C1), 2 (curve C2). , 3 (curve C3) and 4 (curve C4).
Les résultats montrent qu'à partir d'une quantité de 1,6g de base forte dans la solution de sulfate d'hydroxylamine, la corrosion est moins importante. The results show that from a quantity of 1.6 g of strong base in the hydroxylamine sulfate solution, the corrosion is less important.
Exemple 2 Example 2
Une première série d'essais est réalisée pour comparer la corrosion occasionnée par le sulfate d'hydroxylamine et par des acides faibles d'hydroxylamine ou la dimédone. A first series of tests is carried out to compare the corrosion caused by hydroxylamine sulphate and by weak acids of hydroxylamine or dimedone.
Les compositions des solutions testées sont données dans le tableau 3. Tableau 3 The compositions of the solutions tested are given in Table 3. Table 3
Figure imgf000020_0001
Figure imgf000020_0001
Les résultats sont donnés dans le tableau 4. The results are given in Table 4.
Tableau 4 Table 4
Bouteilles Rapport des masses pesées Bottles Report weighed masses
Additif mO/mO ml/mO m2/m0 m3/m0 m4/m0 Additive mO / mO ml / mO m2 / m0 m3 / m0 m4 / m0
No.
5 Sulfate 1 0,795 0,774 0,756 0,736 d'hydroxyla  5 Sulfate 1 0.795 0.774 0.756 0.736 of hydroxyla
-mine  -mine
6 Oxalate 1 0,881 0,876 0,872 0,870 d'hydroxyla  6 Oxalate 1 0.881 0.876 0.872 0.870 hydroxyla
-mine  -mine
7 Acétate 1 0,966 0,946 0,942 0,935 d'hydroxyla  7 Acetate 1 0,966 0,946 0,942 0,935 hydroxyla
-mine  -mine
8 Dimédone 1 0,995 0,989 0,985 0,981 8 Dimedone 1 0.995 0.989 0.985 0.981
9 Témoin 1 0,999 0,999 0,999 0,999 9 Witness 1 0.999 0.999 0.999 0.999
Temps (h) 0 24 48 72 96 m0 : masse initiale de la plaque Time (h) 0 24 48 72 96 m0: initial mass of the plate
m l , m2, m3 , m4 : masse de la plaque lors de la mesure, respectivement à 24h, 48h, 72h et 96h.  m l, m2, m3, m4: mass of the plate during the measurement, respectively at 24h, 48h, 72h and 96h.
Les résultats du tableau 4 sont également illustrés sur la figure 3 , qui représente l ' évo lution du rapport masse de fer pesée/masse de fer initiale en fonction du temps (en heure) pour les bouteilles 5 (courbe C5), 6 (courbe C6), 7 (courbe C7), 8 (courbe C 8) et 9 (courbe C9) . The results of Table 4 are also illustrated in Figure 3, which shows the evolution of the weight of iron weight / initial iron mass as a function of time (in hours) for bottles 5 (curve C5), 6 (curve C6), 7 (curve C7), 8 (curve C 8) and 9 (curve C9).
Les résultats montrent qu' avec de l'oxalate d' hydroxylamine, de l ' acétate d' hydroxylamine ou de la dimédone, la corrosion est moins importante qu' avec le sulfate d' hydroxylamine.  The results show that with hydroxylamine oxalate, hydroxylamine acetate or dimedone, corrosion is less important than with hydroxylamine sulfate.
Exemple 3 Example 3
L 'obj et de cet exemple est de comparer les propriétés de compositions de caoutchouc comprenant un caoutchouc naturel traité selon l' invention (compositions B, C, D, E) avec les propriétés d' une composition de caoutchouc comprenant un caoutchouc naturel non traité selon l' invention (composition A), ainsi que d ' évaluer l ' effet du stockage des caoutchoucs naturels traités sur sa viscosité Mooney 1 -Fabrication des compositions de caoutchouc : The purpose of this example is to compare the properties of rubber compositions comprising a natural rubber treated according to the invention (compositions B, C, D, E) with the properties of a rubber composition comprising an untreated natural rubber. according to the invention (composition A), as well as to evaluate the effect of the storage of treated natural rubbers on its Mooney viscosity 1 - Manufacture of rubber compositions:
Pour les compositions B, C, D et E, le caoutchouc naturel est préalablement traité au moyen d'un agent stabilisant au moyen de deux dispositifs de déchiquetage et d'homogénéisation disposés en série, à savoir deux « prebreakers » montés en série, Le caoutchouc naturel traité sort du deuxième prebreaker à 1 10°C . For compositions B, C, D and E, the natural rubber is pretreated by means of a stabilizing agent by means of two shredding and homogenization devices arranged in series, namely two "prebreakers" connected in series. treated natural rubber comes out of the second prebreaker at 1 10 ° C.
On introduit successivement, dans un mélangeur interne usuel, tous les constituants de base nécessaires (Caoutchouc naturel traité selon l' invention ou non, charges renforçantes, autres additifs), à l'exception du système de réticulation. On conduit alors un travail thermomécanique (phase non-productive) en une étape, qui dure au total environ 3 à 5 min, jusqu'à atteindre une température maximale de « tombée » de 165 °C . On récupère le mélange ainsi obtenu et on le refroidit. The necessary basic constituents are introduced successively into a conventional internal mixer (treated natural rubber). according to the invention or not, reinforcing fillers, other additives), with the exception of the crosslinking system. Thermomechanical work (non-productive phase) is then carried out in one step, which lasts a total of about 3 to 5 min, until a maximum temperature of "fall" of 165 ° C is reached. The mixture thus obtained is recovered and cooled.
Après refroidissement du mélange ainsi obtenu, on incorpore alors dans un mélangeur externe (homo-finisseur) maintenu à basse température, le système de réticulation composé du soufre et du sulfénamide (CB S). L'ensemble est alors mélangé (phase productive) pendant quelques minutes (une dizaine de minutes environ) .  After cooling the mixture thus obtained, is then incorporated in an external mixer (homo-finisher) maintained at low temperature, the crosslinking system composed of sulfur and sulfenamide (CB S). The whole is then mixed (productive phase) for a few minutes (about ten minutes).
La composition finale ainsi obtenue est ensuite calandrée sous la forme d'une feuille ou d'une plaque pour une caractérisation au laboratoire.  The final composition thus obtained is then calendered in the form of a sheet or a plate for a characterization in the laboratory.
2- Mesures et tests : 2- Measurements and tests:
Viscosité Mooney : Mooney Viscosity:
On utilise un consistomètre oscillant tel que décrit dans la norme française NF 43 -005 ( 199 1 ) . La mesure de viscosité Mooney se fait selon le principe suivant : la composition à l ' état cru (i. e. , avant cuisson) est moulée dans une enceinte cylindrique chauffée à 100°C . Après une minute de préchauffage, le rotor tourne au sein de l ' éprouvette à 2 tours/minute et on mesure le couple utile pour entretenir ce mouvement après 4 minutes de rotation. La viscosité Mooney (ML 1 +4) est exprimée en « unité Mooney » (UM, avec l UM=0.83N.m) .  An oscillating consistometer is used as described in the French standard NF 43 -005 (199 1). The Mooney viscosity measurement is carried out according to the following principle: the composition in the green state (i.e., before firing) is molded in a cylindrical chamber heated to 100 ° C. After a minute of preheating, the rotor rotates within the specimen at 2 revolutions / minute and the useful torque is measured to maintain this movement after 4 minutes of rotation. Mooney viscosity (ML 1 +4) is expressed in "Mooney unit" (UM, with UM = 0.83N.m).
Propriétés dynamiques : Dynamic properties:
Les compositions de caoutchouc sont caractérisées après cuisson comme indiqué ci-après .  The rubber compositions are characterized after curing as indicated below.
Les propriétés dynamiques sont mesurées sur un viscoanalyseur (Metravib VA4000), selon la norme ASTM D 5992-96. On enregistre la réponse d'un échantillon de composition vulcanisée (éprouvette cylindrique de 4 mm d ' épaisseur et de 400 mm2 de section), soumis à une so llicitation sinusoïdale en cisaillement simp le alterné, à la fréquence de 10Hz, à la température de 60°C, à un balayage en amplitude de déformation de 0, 1 % à 50%> (cycle aller), puis de 50%> à 1 %) (cycle retour) : pour le cycle aller, on enregistre la valeur maximale du facteur de perte, notée tan(ô)max. Dynamic properties are measured on a viscoanalyzer (Metravib VA4000) according to ASTM D 5992-96. We record the response of a sample of vulcanized composition (cylindrical specimen 4 mm in thickness and 400 mm 2 in section), subjected to a sinusoidal solicitation in simulated shear alternately, at a frequency of 10 Hz, at a temperature of 60 ° C, to a strain amplitude sweep of 0, 1% to 50%> (forward cycle), then 50%> to 1%) (return cycle): for the forward cycle, the maximum value of the factor is recorded of loss, noted tan (ô) max.
On rappelle que, de manière bien connue de l'homme du métier, la valeur de tan(ô)max (selon un balayage "en déformation" , à température donnée) est représentative de l'hystérèse et de la résistance au roulement (plus tan(ô)max est faible, plus basse est l'hystérèse et donc la résistance au roulement) It will be recalled that, in a manner well known to those skilled in the art, the value of tan (δ) max (according to a "deformation" sweep at a given temperature) is representative of hysteresis and rolling resistance (plus tan (δ) max is low, lower is the hysteresis and therefore the rolling resistance)
3 - Résultats 3 - Results
Les compositions et leurs propriétés sont reportées dans les tableaux ci-dessous. The compositions and their properties are reported in the tables below.
Les quantités de sulfate d' hydroxylamine, de soude, d' acétate d' hydroxylamine et d' oxylate d' hydroxylamine ont été introduites préalablement à la préparation de la composition, comme expliqué précédemment. The amounts of hydroxylamine sulfate, sodium hydroxide, hydroxylamine acetate and hydroxylamine oxylate were introduced prior to the preparation of the composition, as explained above.
Les quantités massiques de sulfate d' hydroxylamine, d' acétate d' hydroxylamine, d'oxalate d' hydroxylamine et de dimédone sont telles que les quantités mo laires en équivalent hydroxylamine ou dimédone sont égales pour chaque composition. Tableau 5 The mass quantities of hydroxylamine sulfate, hydroxylamine acetate, hydroxylamine oxalate and dimedone are such that the average amounts of hydroxylamine or dimedone equivalent are equal for each composition. Table 5
Figure imgf000024_0001
Figure imgf000024_0001
(l)caoutchouc naturel à 80% en poids de caoutchouc naturel de fond de tasse et 20%> en poids de caoutchouc naturel de latex  (l) Natural rubber at 80% by weight of bottom natural rubber cup and 20%> by weight of natural latex rubber
(2) sulfate d'hydroxylamine  (2) hydroxylamine sulfate
(3) NaOH : soude  (3) NaOH: sodium hydroxide
(4) HAC : acide acétique acétate d'hydroxylamine  (4) HAC: acetic acid hydroxylamine acetate
(5) HOX : acide oxalique oxalate d'hydroxylamine  (5) HOX: Oxalic acid hydroxylamine oxalate
(6) DIM : Dimédone  (6) DIM: Dimmedone
(7) Noir de carbone N220  (7) Carbon black N220
(*) quantité massique de sulfate d'hydroxylamine par rapport au caoutchouc naturel, en pce ; la quantité molaire de soude est deux fois le nombre de moles de sulfate d'hydroxylamine ; le NaOH est rajouté à la solution de SHA avant d'injecter la solution SHA+NaOH sur le caoutchouc naturel  (*) mass quantity of hydroxylamine sulphate relative to natural rubber, in phr; the molar amount of sodium hydroxide is twice the number of moles of hydroxylamine sulfate; the NaOH is added to the SHA solution before injecting the SHA + NaOH solution onto the natural rubber
Tous les stabilisants ont été ajoutés au même taux molaire. Propriétés dynamiques : All stabilizers were added at the same molar rate. Dynamic properties:
Tableau 6  Table 6
Figure imgf000025_0001
Figure imgf000025_0001
Les propriétés à l ' état vulcanisé des compositions montrent que les compositions conformes à l' invention (compositions B, C, D et E) possèdent une propriété d' hystérèse équivalente par rapport à celle de la composition A de référence mettant en œuvre un NR avec SHA ce qui est très favorable pour obtenir un pneumatique possédant une résistance au roulement réduite lorsque la composition conforme à l' invention est utilisée à titre de bande de roulement. Par ailleurs les viscosités Mooney des caoutchoucs naturels traités selon le procédé conforme à l 'invention évo luent après stockage des caoutchoucs naturels de manière sensiblement comparable à celle d'un caoutchouc naturel stabilisé par le sulfate d' hydroxylamine, c ' est-à-dire de façon bien inférieure à celle d 'un caoutchouc naturel non stabilisé. En particulier, il est noté que le traitement du caoutchouc naturel avec le sulfate d' hydroxylamine neutralisé avec une base forte telle que la soude, permet de stabiliser efficacement sa viscosité Mooney. Le procédé de traitement de caoutchouc naturel conforme à l' invention permet de produire un caoutchouc naturel stabilisé qui confère aux compositions de caoutchouc des propriétés d' hystérèse comparables à celles conférées par un caoutchouc naturel stabilisé avec l 'hydroxylamine, sans avoir les inconvénients de la corrosion rencontrés lors d'une stabilisation avec le sulfate d ' hydroxylamine. The vulcanized state properties of the compositions show that the compositions according to the invention (compositions B, C, D and E) have an equivalent hysteresis property compared to that of the reference composition A implementing an NR. with SHA which is very favorable for obtaining a tire with reduced rolling resistance when the composition according to the invention is used as tread. Furthermore, the Mooney viscosities of the natural rubbers treated according to the process according to the invention evolve after storage of the natural rubbers in a manner substantially comparable to that of a natural rubber stabilized with hydroxylamine sulphate, that is to say much less than that of unstabilized natural rubber. In particular, it is noted that the treatment of natural rubber with neutralized hydroxylamine sulfate with a strong base such as sodium hydroxide, effectively stabilizes its Mooney viscosity. The natural rubber treatment method according to the invention makes it possible to produce a stabilized natural rubber which gives the rubber compositions hysteresis properties comparable to those conferred by a natural rubber stabilized with hydroxylamine, without the disadvantages of corrosion encountered during stabilization with hydroxylamine sulfate.

Claims

REVENDICATIONS
1 . Procédé de traitement d'un caoutchouc naturel, comprenant les étapes suivantes : 1. A method of treating a natural rubber, comprising the steps of:
ajouter au caoutchouc naturel un ou plusieurs agents stabilisants, ledit caoutchouc naturel étant constitué d' au moins 80% en poids de caoutchouc naturel de fond de tasse et de 0 à 20%> en poids de caoutchouc naturel de latex, par rapport au poids total de caoutchouc naturel, le ou lesdits agents stabilisants étant choisis parmi la dimédone ou étant choisis parmi les sels d ' acide faible de composés de formule XNH2 et les sels d' acide fort de composés de formule XNH2 neutralisés avec une base forte, où X est un groupe choisi parmi les groupes hydroxyle et hydroxyalkyle en C 1 -C 4 , et le ou lesdits agents stabilisants étant présents respectivement en une quantité variant de 2,4 mmo les à 24 mmo les équivalent de dimédone ou équivalent de XNH2 par kilogramme de caoutchouc naturel, puis adding to the natural rubber one or more stabilizing agents, said natural rubber consisting of at least 80% by weight of natural bottom mastic and 0 to 20% by weight of natural latex rubber, based on the total weight of natural rubber, the stabilizing agent (s) being (are) chosen from dimedone or being chosen from the weak acid salts of compounds of formula XNH 2 and the strong acid salts of compounds of formula XNH 2 neutralized with a strong base, where X is a group selected from hydroxyl and hydroxyalkyl groups C 1 -C 4, and the said stabilizing agent (s) being respectively present in an amount ranging from 2.4 mmo to 24 mmo the equivalent of dimedone or equivalent of XNH 2 by kilogram of natural rubber, then
soumettre le caoutchouc naturel auquel a été ajouté le ou les agents stabilisants à un travail mécanique à une température d' au moins 100 ° C .  subjecting the natural rubber to which the stabilizing agent (s) has been added to mechanical work at a temperature of not less than 100 ° C.
2. Procédé selon la revendication 1 , caractérisé en ce que le caoutchouc naturel est un caoutchouc naturel de fond de tasse.  2. Method according to claim 1, characterized in that the natural rubber is a natural rubber cup bottom.
3. Procédé selon la revendication 1 ou 2 caractérisé en ce que le caoutchouc naturel est choisi parmi les caoutchoucs naturels issus de l 'hévéa Brasiliensis.  3. Method according to claim 1 or 2 characterized in that the natural rubber is selected from natural rubber from the Hevea Brasiliensis.
4. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que les sels d' acide faible de composés de formule XNH2 sont choisis parmi les sels d' acide faible d' hydroxylamine, de préférence l ' acétate d' hydroxylamine et l 'oxalate d' hydroxy lamine. 4. Process according to any one of the preceding claims, characterized in that the weak acid salts of compounds of formula XNH 2 are chosen from the weak acid salts of hydroxylamine, preferably hydroxylamine acetate and hydroxyamine oxalate.
5. Procédé selon l 'une quelconque des revendications 1 à 3 caractérisé en ce que les sels d' acide fort de composés de formule 5. Process according to any one of Claims 1 to 3, characterized in that the strong acid salts of compounds of formula
XNH2 sont choisis parmi les sels d' acide fort d' hydroxylamine, de préférence le sulfate d' hydroxylamine. XNH 2 are selected from the strong acid salts of hydroxylamine, preferably hydroxylamine sulfate.
6. Procédé selon l'une quelconque des revendications 1 à 3 et 5 caractérisé en ce que le ou les agents stabilisants sont des sels d'acide fort d'hydroxylamine, neutralisés à la base forte, la teneur en sel(s) d'acide fort d'hydroxylamine variant de 2,4 mmoles à 24 mmoles équivalent d'hydroxylamine par kilogramme de caoutchouc naturel, la teneur en base forte variant de 0,1 à 2 moles, de préférence de 1 à 2 moles, par moles de sel d'acide fort d'hydroxylamine. 6. Method according to any one of claims 1 to 3 and 5 characterized in that the stabilizing agent (s) are strong acid salts of hydroxylamine, neutralized with strong base, the salt content (s) of hydroxylamine strong acid ranging from 2.4 mmol to 24 mmol of hydroxylamine per kilogram of natural rubber, the content of strong base ranging from 0.1 to 2 moles, preferably from 1 to 2 moles, per mole of salt; strong acid hydroxylamine.
7. Procédé selon l'une quelconque des revendications 1 à 3 et 5 à 7, caractérisé en ce que la base forte est la soude.  7. Method according to any one of claims 1 to 3 and 5 to 7, characterized in that the strong base is sodium hydroxide.
8. Procédé selon l'une quelconque des revendications 1 à 4 caractérisé en ce que le ou les agents stabilisants sont des sels d'acide faible d'hydroxylamine, et sont présents à une teneur variant de 2,4 mmoles à 24 mmoles équivalent d'hydroxylamine, de préférence de 6 mmoles à 24 mmoles équivalent d'hydroxylamine, de préférence encore de 8 mmoles à 18 mmoles équivalent d'hydroxylamine, par kilogramme de caoutchouc naturel.  8. Method according to any one of claims 1 to 4 characterized in that the stabilizing agent (s) are weak acid salts of hydroxylamine, and are present in a content ranging from 2.4 mmol to 24 mmol equivalent of hydroxylamine, preferably from 6 mmol to 24 mmol equivalent of hydroxylamine, more preferably from 8 mmol to 18 mmol equivalent of hydroxylamine, per kilogram of natural rubber.
9. Procédé selon l'une quelconque des revendications 1 à 3 caractérisé en ce que l'agent de stabilisant est la dimédone et est présent à une teneur variant de 2,4 mmoles à 24 mmoles équivalent de dimédone, de préférence de 6 mmoles à 24 mmoles équivalent de dimédone, par kilogramme de caoutchouc naturel.  9. Method according to any one of claims 1 to 3 characterized in that the stabilizer agent is dimedone and is present in a content ranging from 2.4 mmol to 24 mmol equivalent of dimedone, preferably from 6 mmol to 24 mmol equivalent of dimedone, per kilogram of natural rubber.
10. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que le travail mécanique est effectué à une température d'au moins 110°C.  10. Process according to any one of the preceding claims, characterized in that the mechanical work is carried out at a temperature of at least 110 ° C.
11. Procédé selon l'une quelconque des revendications précédentes caractérisé en ce que le travail mécanique est effectué au moyen d'un ou plusieurs dispositifs de déchiquetage et d'homogénéisation (1).  11. Method according to any one of the preceding claims, characterized in that the mechanical work is performed by means of one or more shredding and homogenization devices (1).
12. Procédé selon la revendication 11, caractérisé en ce que le travail mécanique est réalisé au moyen de deux dispositifs de déchiquetage et d'homogénéisation disposés en série.  12. Method according to claim 11, characterized in that the mechanical work is performed by means of two shredding and homogenization devices arranged in series.
13. Procédé selon la revendication 11 ou 12 caractérisé en ce que le ou les dispositifs de déchiquetage et d'homogénéisation comprennent chacun une zone d'alimentation et de déchiquetage (2) et une zone d ' homogénéisation (3) reliées entre elles, et un arbre (4) traversant lesdites zones, ledit arbre étant muni de couteaux rotatifs (5) . 13. The method of claim 11 or 12 characterized in that the or shredding devices and homogenization each comprise a feeding and shredding zone (2) and a homogenisation zone (3) interconnected, and a shaft (4) passing through said zones, said shaft being provided with rotary knives (5).
14. Procédé selon la revendication 13 , caractérisé en ce que la zone d' alimentation et de déchiquetage (2) comprend une partie supérieure (2a) et une partie inférieure (2b), ladite partie supérieure (2a) étant apte à alimenter ladite partie inférieure (2b), ladite partie inférieure (2b) comprenant la première partie dudit arbre (4) .  14. The method of claim 13, characterized in that the feeding and shredding zone (2) comprises an upper portion (2a) and a lower portion (2b), said upper portion (2a) being adapted to feed said portion. lower part (2b), said lower part (2b) comprising the first part of said shaft (4).
15. Procédé selon la revendication 14, caractérisé en ce que la zone d' homogénéisation (3 ) comprend la seconde partie dudit arbre (4) et un fourreau (7) insérant ladite seconde partie de l ' arbre (4), ledit fourreau (7) étant muni de seconds couteaux fixes (8) .  Method according to claim 14, characterized in that the homogenisation zone (3) comprises the second part of said shaft (4) and a sleeve (7) inserting said second part of the shaft (4), said sleeve ( 7) being provided with second fixed knives (8).
16. Procédé selon l'une quelconque des revendications 13 à 15 , caractérisé en ce que l ' arbre (4) présente une vitesse de rotation variant de 20 à 100 tours/min, de préférence de 20 à 60 tours/min.  16. Method according to any one of claims 13 to 15, characterized in that the shaft (4) has a rotation speed ranging from 20 to 100 revolutions / min, preferably from 20 to 60 rev / min.
17. Procédé selon l'une quelconque des revendications 13 à 16, caractérisé en ce que le ou les dispositifs de déchiquetage et d'homogénéisation présentent chacun une plaque filière (9) en bout de la zone d ' homogénéisation (3), ladite plaque filière (9) présentant des orifices.  17. A method according to any one of claims 13 to 16, characterized in that the or shredding devices and homogenization each have a die plate (9) at the end of the homogenization zone (3), said plate die (9) having orifices.
1 8. Procédé selon l 'une quelconque des revendications précédentes, caractérisé en ce que l ' étape de travail mécanique est suivie d'une étape de coupe du caoutchouc naturel traité .  Process according to one of the preceding claims, characterized in that the mechanical working step is followed by a cutting step of the treated natural rubber.
19. Caoutchouc naturel traité susceptible d' être obtenu par le procédé tel que défini à l 'une quelconque des revendications précédentes .  19. Treated natural rubber obtainable by the process as defined in any one of the preceding claims.
20. Composition de caoutchouc à base d' au moins une charge renforçante et d'une matrice élastomère comprenant au moins un caoutchouc naturel traité tel que défini à la revendication 19.  20. A rubber composition based on at least one reinforcing filler and an elastomeric matrix comprising at least one treated natural rubber as defined in claim 19.
21 . Article semi-fini en caoutchouc pour pneumatique, caractérisé en ce qu' il comprend une composition de caoutchouc réticulable ou réticulée selon la revendication 20.  21. A rubber semi-finished article for a tire, characterized in that it comprises a cross-linkable or cross-linked rubber composition according to claim 20.
22. Pneumatique caractérisé en ce qu' il comporte un article semi-fini tel que défini dans la revendication 21 .  22. A tire characterized in that it comprises a semi-finished article as defined in claim 21.
PCT/EP2016/077832 2015-11-17 2016-11-16 Process for preparing a stabilized natural rubber WO2017085109A1 (en)

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FR3124417A1 (en) 2021-06-29 2022-12-30 Compagnie Generale Des Etablissements Michelin Process for the preparation of a natural rubber
WO2023275450A1 (en) 2021-06-29 2023-01-05 Compagnie Generale Des Etablissements Michelin Method for preparing a natural rubber

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