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    • 专利摘要:
    The invention relates to a method of treating a natural rubber, comprising the steps of: adding to the natural rubber one or more stabilizing agents, said natural rubber consisting of at least 80% by weight of natural rubber of the bottom of the cup and from 0 to 20% by weight of natural latex rubber, relative to 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 strong acid salts of compounds of formula XNH2 neutralized with a strong base, wherein X is a group selected from hydroxyl and hydroxyC1-4alkyl groups, and the said stabilizing agent (s) being respectively present in an amount varying from 2.4 mmoles to 24 mmol equivalent of dimedone or XNH2 equivalent per kilogram of natural rubber, then - subject the natural rubber to which the stabilizer agent (s) has been added ts to mechanical work at a temperature of at least 100 ° C.
    公开号:FR3043678A1
    申请号:FR1561037
    申请日:2015-11-17
    公开日:2017-05-19
    发明作者:Jerome Dussillols；Jean-Luc Merceron
    申请人:Michelin Recherche et Technique SA Switzerland ；Compagnie Generale des Etablissements Michelin SCA；Michelin Recherche et Technique SA France；
    IPC主号:
    专利说明:

    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 homogenisation of the resulting assembly by means of a device providing high temperature mechanical work.
    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.
    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.
    But this plastification process has a significant energy cost, of the order of 140 kW / t, and requires significant investment.
    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.
    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 that is released into the environment.
    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.
    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 hydroxylamine solutions. It is also possible to find stabilizer in the effluents.
    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.
    GB 1373630 describes the stabilization of natural rubber by addition of a hydroxylamine sulfate on natural rubber in the solid state, then reaction at a temperature above 100 ° C in a mixing machine.
    However, hydroxylamine sulfate solutions can corrode machines such as mixing machines or storage tanks of the solution.
    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 thus 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.
    The Applicants have surprisingly discovered 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 melt of one or more agents selected from dimedone and specific 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 usual plasticization processes, while avoiding corrosion phenomena in installations. The subject of the invention is therefore a method for treating a natural rubber, comprising the following steps: adding to the natural rubber one or more stabilizing agents, said natural rubber consisting of at least 80% by weight of natural rubber of cup and from 0 to 20% by weight of natural rubber of latex, relative to the total weight of natural rubber, the said stabilizing agent (s) being dimedone or being chosen from the weak acid salts of compounds of formula XNH2 and the strong acid salts of compounds of formula XNH2 neutralized with a strong base, wherein X is a group selected from hydroxyl and hydroxyC1-4alkyl groups, and the said stabilizing agent (s) being respectively present in an amount varying from 2.4 mmoles to 24 mmol equivalent of dimedone or equivalent of XNH2 per kilogram of natural rubber, and then subject the natural rubber to which the stabilizing agent (s) has been added mechanical work at a temperature of at least 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 collected in a cup, coagulated in solid form in this cup, then underwent a cleaning, homogenization and drying.
    "Natural latex rubber" means natural rubber which, after bleeding from the tree, has flowed into the cup, has been collected in liquid form and artificially coagulated, and 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 tank 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.
    In a preferred embodiment, the natural rubber is a natural cup bottom rubber. This means that natural rubber does not contain natural latex rubber.
    Preferably, the natural rubber used in the process according to the invention is chosen from natural rubbers derived from Hevea Brasiliensis.
    As explained above, the stabilizing agent (s) may be chosen from the weak acid salts of compounds of formula XNH 2. As 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. 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.
    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.
    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. .
    When the stabilizing agent (s) are strong acid salts of compounds XNH2 as defined above, neutralized with a strong base, the strong base may be chosen from sodium hydroxide (sodium hydroxide), potassium hydroxide, preferably sodium hydroxide.
    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). Preferably, the addition of the stabilizing agent (s) to the natural rubber is done by watering.
    After the step of adding to the natural rubber one or more stabilizing agents, the process according to the invention comprises a mechanical working step at a temperature of at least 100 ° C. of the natural rubber to which has been added and the stabilizing agents.
    Preferably, the mechanical work is performed at a temperature of at least 110 ° C.
    The mechanical work is preferably carried out by means of one or more shredding and homogenization devices. Such a device is generally called "prebreaker".
    Such a device has an energy consumption of the order of 50 kW / tonne of natural rubber, whereas a plasticizing process consumes around 140 kW / ton.
    According to a particularly preferred embodiment, 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 ranging from 25 seconds to 3 minutes.
    The shredding and homogenization device or devices usually comprise each a feed and shredding zone and a homogenization zone interconnected, and a shaft passing through said zones, said shaft being provided with rotary knives.
    The feed zone generally comprises an upper part and a lower part, said upper part being able to supply 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 set of natural rubber - stabilizing agent goes up in the upper part of the feeding zone once it has reached the lower part of the feeding 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.
    These holes may be in the form of round holes or oblong holes or triangular holes.
    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.
    The temperature in the shredding and homogenizing 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 can be followed by a cutting step of the treated natural rubber. The cutting step may be performed by means of a cutting device positioned at the output of the device conferring the mechanical work, in particular or of the shredding and homogenizing device or devices.
    Another subject of the invention is a treated natural rubber that can be obtained by the method that is the subject 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.
    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.
    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.
    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.
    By diene elastomer, it should be understood according to the invention any synthetic elastomer derived at least in part from monomers dienes. More particularly, diene elastomer is any 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 one another 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. 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.
    More preferably, the elastomeric matrix consists solely of 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.
    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.
    Suitable carbon blacks are all carbon blacks, used individually or in the form of mixtures, in particular blacks of the HAF, ISAF, SAF type conventionally used in tire treads (so-called pneumatic grade blacks). Among the latter, there will be mentioned more particularly the reinforcing carbon blacks of the series 100, 200 or 300 (ASTM grades), such as, for example, the blacks N115, N134, N234, N326, N330, N339, N347 and N375. The carbon blacks could for example already be incorporated into the isoprene elastomer in the form of a masterbatch (see for example WO 97/36724 or WO 99/16600).
    As reinforcing inorganic filler, is meant by the present application, by definition, any inorganic or mineral filler regardless of its color and its origin (natural or synthetic), capable of reinforcing on its own, without 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.
    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. By way of example, mention may be made, for example, of carbon blacks for tires as described for example in 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. Of course, the term "reinforcing inorganic filler" also refers to mixtures of different reinforcing fillers, in particular highly dispersible siliceous fillers as described above.
    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 preferably between 70 and 130 phr, the optimum being in a known manner different according to the particular applications concerned.
    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.
    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).
    According to another variant of the invention, a reinforcing filler comprising predominantly carbon black and optionally silica or other inorganic filler is used.
    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 the silica is present in the composition as a reinforcing filler, it is possible to use as coupling agents organosilanes, especially polysulfurized alkoxysilanes or mercaptosilanes, or at least bifunctional polyorganosiloxanes.
    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.
    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 implement in the green state, these agents being, for example, hydrolysable silanes such as alkylalkoxysilanes, polyols, polyethers, primary, secondary or tertiary amines, hydroxylated or hydrolysable 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. 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.
    The rubber composition according to the invention may also comprise all or part of the usual additives usually used in elastomer compositions intended for the manufacture of tires, for example pigments, non-reinforcing fillers, protective agents such as waxes anti-ozone, chemical antiozonants, anti-oxidants, anti-fatigue agents, plasticizers, reinforcing or plasticizing resins, acceptors (for example phenolic novolac resin) or methylene donors (for example HMT or H3M) as described for example in the application WO 02/10269, a crosslinking system based on either sulfur, or sulfur and / or peroxide donors and / or bismaleimides, vulcanization accelerators, vulcanization activators.
    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 110 ° C and 190 ° C, preferably between 130 ° C and 180 ° C, followed by a second phase of mechanical work (so-called "productive" phase) to a lower temperature, typically less than 110 ° C, for example between 40 ° C and 100 ° C, finishing phase during which is incorporated the crosslinking system.
    The process for preparing a composition according to the invention generally comprises: (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) the production, at a temperature below said maximum temperature of said first time, of a second time mechanical work in which is incorporated said crosslinking system. The invention also relates to a semi-finished rubber tire article, comprising a rubber composition according to the invention, crosslinkable or crosslinked, or consisting of such a composition.
    The final composition thus obtained can then be calendered, for example in the form of a sheet, a plate or extruded, for example to form a rubber profile usable as a semi-finished rubber product for the tire. The subject of the invention is therefore a tire comprising a semi-finished article according to the invention, in particular a tread. 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 shows 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 part and open 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 feeding large blocks of natural rubber. Preferably, the walls 6 are vertical to prevent the natural rubber from being stuck on feeding walls that would be inclined.
    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. Due to the gravity, the natural rubber blocks are still in contact with the rotary knives 5 of the shaft 4, and are therefore easily caught to be shredded.
    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 continuity with the feeding and shredding zone 2 and is connected to it. This zone makes it possible to knead and homogenize the natural rubber.
    This homogenization zone 3 comprises a sleeve 7 inserting the second part of the shaft 4. The sleeve 7 is provided with second fixed knives 8. The second fixed knives 8 promote the homogenization and 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 the natural rubber. The reduction in the opening of the holes of 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.
    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. 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.
    Examples
    Examples 1 and 2 which follow are intended to evaluate the corrosiveness of certain stabilizers 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. 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. 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.
    Example 1
    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.
    The compositions of the solutions tested are given in Table 1.
    Table 1
    SHA: hydroxylamine sulfate
    The results are given in Table 2.
    Table 2
    mO: initial mass of the plate ml, m2, m3, m4: mass of the plate during the measurement, respectively at 24h, 48h, 72h and 96h.
    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).
    The results show that from a quantity of 1.6 g of strong base in the hydroxylamine sulfate solution, the corrosion is less important.
    Example 2
    A first series of tests is carried out to compare the corrosion caused by hydroxylamine sulphate and by weak acids of hydroxylamine or dimedone.
    The compositions of the solutions tested are given in Table 3.
    Table 3
    The results are given in Table 4. Table 4
    mO: initial mass of the plate ml, m2, m3, m4: mass of the plate during the measurement, respectively at 24h, 48h, 72h and 96h.
    The results of Table 4 are also illustrated in FIG. 3, which represents 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 C8) and 9 (curve C9).
    The results show that with hydroxylamine oxalate, hydroxylamine acetate or dimedone, corrosion is less important than with hydroxylamine sulfate.
    Example 3 The object 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 a non-natural rubber. treated 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:
    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 110 ° C.
    The necessary basic constituents (natural rubber treated according to the invention or not, reinforcing fillers, other additives), with the exception of the crosslinking system, are successively introduced into a conventional internal mixer. 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.
    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 (CBS). The whole is then mixed (productive phase) for a few minutes (about ten minutes).
    The final composition thus obtained is then calendered in the form of a sheet or a plate for a characterization in the laboratory. 2- Measurements and tests:
    Moonev viscosity:
    An oscillating consistometer is used as described in the French standard NF 43-005 (1991). 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 one minute of preheating, the rotor rotates within the test tube at 2 revolutions / minute and the useful torque is measured to maintain this movement after 4 minutes of rotation. Mooney viscosity (ML1 + 4) is expressed in "Mooney unit" (UM, with lUM = 0.83N.m).
    Dynamic properties:
    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. The response of a sample of vulcanized composition (cylindrical specimen 4 mm in thickness and 400 mm 2 in section), subjected to a sinusoidal stress in alternating simple shear, at the frequency of 10 Hz, at the temperature of 60 °, is recorded. C, at a strain amplitude sweep from 0.1% to 50% (forward cycle), then from 50% to 1% (return cycle): for the forward cycle, the maximum value of the loss factor is recorded, tan (O) max.
    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 (ô) max is low, lower is the hysteresis and therefore the rolling resistance) 3 - Results
    The compositions and their properties are reported in the tables below.
    The amounts of hydroxylamine sulfate, sodium hydroxide, hydroxylamine acetate and hydroxylamine oxylate were introduced prior to the preparation of the composition, as explained above.
    The mass quantities of hydroxylamine sulfate, hydroxylamine acetate, hydroxylamine oxalate and dimedone are such that the molar amounts of hydroxylamine or dimedone equivalent are equal for each composition.
    Table 5
    (1) natural rubber at 80% by weight of bottom natural rubber cup and 20% by weight of natural latex rubber (2) hydroxylamine sulfate (3) NaOH: soda (4) HAC: acetic acid acetate hydroxylamine (5) HOX: Oxalic acid hydroxylamine oxalate (6) DIM: Dimedone (7) Carbon black N220 (*) 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
    All stabilizers were added at the same molar rate.
    Dynamic properties:
    Table 6
    The properties in the vulcanized state 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 to obtain a tire with a reduced rolling resistance when the composition according to the invention is used as a 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 sulfate, that is to say from much less than that of unstabilized natural rubber. In particular, it is noted that the treatment of natural rubber with hydroxylamine sulfate neutralized with a strong base such as soda, can effectively stabilize 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 having the disadvantages of corrosion encountered during stabilization with hydroxylamine sulfate.
    权利要求:
    Claims (22)
    [1" id="c-fr-0001]
    A method of treating a natural rubber, comprising the steps of: adding to the natural rubber one or more stabilizing agents, said natural rubber consisting of at least 80% by weight of cup bottom natural rubber and 0 to 20% by weight of natural rubber of latex, relative to the total weight of natural rubber, the said stabilizing agent or agents being chosen from dimedone or being chosen from the weak acid salts of compounds of formula XNH 2 and the acid salts strong of compounds of formula XNH2 neutralized with a strong base, where X is a group selected from hydroxy and hydroxyalkyl groups C1-C4, and the said stabilizing agent (s) being respectively present in an amount ranging from 2.4 mmol to 24 mmol equivalent of dimedone or equivalent of XNH2 per kilogram of natural rubber, and then subject the natural rubber to which the stabilizing agent (s) has been added to a work mechanical at a temperature of at least 100 ° C.
    [2" id="c-fr-0002]
    2. Method according to claim 1, characterized in that the natural rubber is a natural rubber cup bottom.
    [3" id="c-fr-0003]
    3. Method according to claim 1 or 2 characterized in that the natural rubber is selected from the natural rubber from Hevea Brasiliensis.
    [4" id="c-fr-0004]
    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 hydroxylamine oxalate.
    [5" id="c-fr-0005]
    5. Process according to any one of Claims 1 to 3, characterized in that the strong acid salts of compounds of formula XNH 2 are chosen from hydroxylamine strong acid salts, preferably hydroxylamine sulphate.
    [6" id="c-fr-0006]
    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" id="c-fr-0007]
    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" id="c-fr-0008]
    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" id="c-fr-0009]
    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" id="c-fr-0010]
    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" id="c-fr-0011]
    11. Method according to any one of the preceding claims characterized in that the mechanical work is performed by means of one or more chipping and homogenization devices (1).
    [12" id="c-fr-0012]
    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" id="c-fr-0013]
    13. The method of claim 11 or 12 characterized in that the or shredding devices and homogenization each comprise a feed zone and shredding (2) and a homogenization zone (3) connected together, and a shaft (4) passing through said zones, said shaft being provided with rotary knives (5).
    [14" id="c-fr-0014]
    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" id="c-fr-0015]
    15. Method according to claim 14, characterized in that the homogenization 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" id="c-fr-0016]
    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" id="c-fr-0017]
    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.
    [18" id="c-fr-0018]
    18. Method according to any one of the preceding claims, characterized in that the mechanical working step is followed by a cutting step of the treated natural rubber.
    [19" id="c-fr-0019]
    19. Treated natural rubber obtainable by the process as defined in any one of the preceding claims.
    [20" id="c-fr-0020]
    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" id="c-fr-0021]
    21. Semi-finished rubber article for a tire, characterized in that it comprises a crosslinkable or crosslinked rubber composition according to claim 20.
    [22" id="c-fr-0022]
    22. A tire characterized in that it comprises a semi-finished article as defined in claim 21.
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    同族专利:
    公开号 | 公开日
    WO2017085109A1|2017-05-26|
    FR3043678B1|2018-01-05|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    US20040106724A1|2000-11-07|2004-06-03|Hirotoshi Toratani|Natural rubber produced from latex and composition comprising the same|
    EP2671913A1|2011-02-03|2013-12-11|Bridgestone Corporation|Natural rubber, rubber composition using the same, and tire|CN111295296A|2017-11-23|2020-06-16|米其林集团总公司|Natural rubber|
    WO2021224568A1|2020-05-05|2021-11-11|Compagnie Generale Des Etablissements Michelin|Method for preparing stabilized natural rubber|GB1373630A|1970-01-31|1974-11-13|Malaysia Rubber Res Inst|Stabilisation of natural rubber|
    DE69635185T2|1995-05-22|2006-07-06|Cabot Corp., Boston|RUBBER COMPOSITIONS CONTAINING SILICONE-MODIFIED ROOT|
    EP1537908B1|1997-09-30|2012-04-04|Cabot Corporation|Elastomer composite blends and methods for producing them|
    JP4234200B2|1996-04-01|2009-03-04|キャボットコーポレイション|Novel elastomer composite and method for producing the same|
    WO1999028380A1|1997-11-28|1999-06-10|Compagnie Generale Des Etablissements Michelin - Michelin & Cie|Rubber composition for tyres, reinforced with a carbon black coated with an aluminous layer|
    CN1330961C|1997-11-28|2007-08-08|米什兰集团总公司|Reinforcing aluminium filler and rubber composition containing same|
    JP4111584B2|1998-04-13|2008-07-02|株式会社ブリヂストン|Manufacturing method of natural rubber|
    CA2338162A1|1999-05-28|2000-12-07|Emmanuel Custodero|Diene elastomer and reinforcing titanium oxide based rubber composition for a pneumatic tyre|
    JP5357371B2|2000-07-31|2013-12-04|コンパニーゼネラールデエタブリッスマンミシュラン|Tire tread|
    FR2880349B1|2004-12-31|2009-03-06|Michelin Soc Tech|FUNCTIONALIZED POLYVINYLAROMATIC NANOPARTICLES|
    FR2880354B1|2004-12-31|2007-03-02|Michelin Soc Tech|ELASTOMERIC COMPOSITION REINFORCED WITH A FUNCTIONALIZED POLYVINYLAROMATIC LOAD|
    FR2903411B1|2006-07-06|2012-11-02|Soc Tech Michelin|NANOPARTICLES OF FUNCTIONALIZED VINYL POLYMER|
    FR2903416B1|2006-07-06|2008-09-05|Michelin Soc Tech|ELASTOMERIC COMPOSITION REINFORCED WITH A FUNCTIONALIZED NON-AROMATIC VINYL POLYMER|CN111372951A|2017-11-23|2020-07-03|米其林集团总公司|Process for treating natural rubber|
    CN111386286A|2017-11-23|2020-07-07|米其林集团总公司|Process for treating natural rubber|
    FR3088230B3|2018-11-09|2020-12-04|Michelin & Cie|PROCESS FOR TREATING A NATURAL RUBBER|
    FR3104156B1|2019-12-04|2021-11-12|Michelin & Cie|process for preparing a natural rubber|
    法律状态:
    2016-11-18| PLFP| Fee payment|Year of fee payment: 2 |
    2017-05-19| PLSC| Search report ready|Effective date: 20170519 |
    2017-11-21| PLFP| Fee payment|Year of fee payment: 3 |
    优先权:
    申请号 | 申请日 | 专利标题
    FR1561037A|FR3043678B1|2015-11-17|2015-11-17|PROCESS FOR PREPARING STABILIZED NATURAL RUBBER|
    FR1561037|2015-11-17|FR1561037A| FR3043678B1|2015-11-17|2015-11-17|PROCESS FOR PREPARING STABILIZED NATURAL RUBBER|
    PCT/EP2016/077832| WO2017085109A1|2015-11-17|2016-11-16|Process for preparing a stabilized natural rubber|
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