WO2017103518A1

WO2017103518A1 - Method for producing a masterbatch comprising a diene elastomer, an organic reinforcing filler and an antioxidant

Info

Publication number: WO2017103518A1
Application number: PCT/FR2016/053488
Authority: WO
Inventors: Charbel KANAAN
Original assignee: Compagnie Generale Des Etablissements Michelin; Michelin Recherche Et Technique S.A.
Priority date: 2015-12-16
Filing date: 2016-12-16
Publication date: 2017-06-22
Also published as: CN108602962B; FR3045621B1; CN108602962A; FR3045621A1

Abstract

The invention relates to a method for producing a masterbatch comprising a diene elastomer, an organic reinforcing filler and an antioxidant, the dispersion of the reinforcing filler in the elastomer matrix having a Z score greater than or equal to 80, and said diene elastomer comprising at least natural rubber. The method comprises the following successive steps: a) introducing a coagulum into at least one continuous mixer, in order to obtain a dried mass, said coagulum comprising the diene elastomer and the organic reinforcing filler dispersed in the dried mass with a Z score greater than or equal to 80; b) conveying the mass leaving the continuous mixer into a mill in order to obtain a ribbon; c) introducing the ribbon from the mill and an antioxidant into a continuous mixer such as to obtain a masterbatch; d) after step c) recovering the masterbatch having a moisture content below 1 wt.-%. The method is characterised in that all of the antioxidant present in the masterbatch obtained at the end of step d) is introduced during step c).

Description

Process for the preparation of a masterbatch, comprising a diene elastomer, a reinforcing organic filler and an antioxidant

The present invention aims to improve the industrial efficiency of the master batch preparation processes comprising a diene elastomer and a reinforcing organic filler finely dispersed in the elastomeric matrix.

The term "master mix" (commonly referred to by its English name as "masterbatch") means an elastomer-based composite in which a filler and possibly other additives have been introduced. In the context of the present invention, the elastomer comprises natural rubber.

According to the invention, the masterbatch is particularly used for the manufacture of reinforced diene rubber compositions for the manufacture of tires or semi-finished products for tires, in particular treads of these tires.

In order to obtain the optimum reinforcement and hysteresis properties conferred by a load in a tire tread and thus a high wear resistance and a low rolling resistance, it is known that it is generally desirable that this filler is present in the elastomeric matrix in a final form which is at once as finely divided as possible and distributed in the most homogeneous manner possible. However, such conditions can be achieved only to the extent that this charge has a very good ability, on the one hand to incorporate into the matrix during mixing with the elastomer and to deagglomerate, on the other hand to to disperse homogeneously in this matrix.

There are different methods for obtaining a masterbatch of diene elastomer and reinforcing filler. In particular, one type of solution consists in improving the dispersibility of the filler in the elastomeric matrix by mixing the elastomer and the "liquid" phase filler. To do this, an elastomer in the form of latex has been used in the form of elastomer particles dispersed in water, and an aqueous dispersion of the filler, that is to say a dispersed filler. in water, commonly called "slurry". Certain processes in particular, such as those described in document US Pat. No. 6,048,923, make it possible to obtain a masterbatch of elastomer and filler having a very good dispersion of the filler in the elastomeric matrix, very improved with respect to the dispersion of the filler in the elastomeric matrix obtainable during the solid phase mixing of elastomer and reinforcing filler. This method consists in particular of incorporating a continuous flow of a first fluid constituted by an elastomer latex into the mixing zone of a coagulation reactor, to incorporate a second continuous flow of a second fluid consisting of an aqueous dispersion of pressurized charging in the mixing zone to form a mixture with the elastomer latex; the mixing of these two fluids being sufficiently energetic to allow the elastomer latex to be coagulated almost completely with the filler before the exit orifice of the coagulation reactor and then to dry the coagulum obtained.

The coagulum is usually dried to produce a masterbatch by a continuous process comprising the following successive steps:

Spinning (in English de-watering), most often in an extruder. The wrung product is usually called "pellet" to designate the coagulum granules. The level of volatiles, essentially water, is usually from 10% to 20% by weight.

Drying, mixing and plasticizing (in English "masticate") in a continuous mixer, most often a Banbury mixer or a mixer Unimix Continuous Mixer marketed by Farrel Corporation (this mixer is also referred to by the abbreviation "FCM"). During this step the mixture is masticated and heated. It is during this stage that the various optional additives are added, and in particular the antioxidant which is an additive considered to be necessary. The product recovered at the outlet is usually called "chunk" to designate the recovered mass. This mass is usually at a temperature ranging from 140 ° C. to 200 ° C. The level of volatiles, essentially water, is usually from 1% to 3% by weight In the presence of natural rubber in the elastomeric matrix, this mass has a very high Mooney viscosity (thus for higher carbon black levels at 65 phr, the Mooney viscosity is above the measurement capabilities of the devices, ie greater than 200 UM, we can speak of "overtoque") and is therefore very difficult to work at a rate compatible with a production at the industrial scale. Thus, in practice, for black levels greater than 65 phr, at the output of the mixer part of the mass is sent to the cylinder tools, the rest is usually discarded. The remainder may represent a significant amount, for example may correspond to half of the production leaving the mixer. Laminating by passing a portion of the mass recovered at the outlet of the continuous mixer in roll tools (Mill oll English). These cylinder tools are in contact with the ambient air. At the outlet of the roll tools, the strip (strip) usually has a temperature ranging from 110 ° C. to 160 ° C. and a volatile matter content of less than 1% by weight.

End of line can include granulation steps, compacting in the form of balls, ...

Possibly storage. Thus, current processes are not economical because of a significant loss

(eg, about half) of the production between the continuous mixing and plasticizing steps due to the Mooney excess viscosity of the product when the elastomeric matrix comprises natural rubber.

A photo of a production of a masterbatch when it passes over the cylinder tools, at a flow rate of 375 kg / h, is given in FIG. 1. It can be seen that the sheet is strongly cracked and that the ribbon which is obtained is is not homogeneous with rips on the edges and difficult to work (it is observed that the ribbon tends to twist).

Surprisingly, it has been found that it is possible to increase the flow rate of the plasticizing step, which may be identical to the flow rate of the dewatering and mixing steps. In other words, it was found that it was possible to send all of the mass leaving the continuous mixer to (x) tool (s) cylinder.

In a fortuitous and unexpected manner, the inventors have indeed found that when the totality of the antioxidant agent present in the masterbatch obtained at the end of the process is introduced no longer into the continuous mixer but after the cylinder tools then it is possible to to increase the flow rate of the plasticizing step, which may be identical to the flow rate of the spinning and mixing steps. Thus, the entire mass leaving the continuous mixer can be plasticized during production.

The subject of the invention is thus a process for preparing a masterbatch comprising a diene elastomer, a reinforcing organic filler and an antioxidant and having a dispersion of the reinforcing filler in the elastomeric matrix having a Z score greater than or equal to 80, the diene elastomer comprises at least natural rubber, the method comprises the following successive steps: a) introducing, to obtain a dried mass, a coagulum in at least one continuous mixer, said coagulum comprises said diene elastomer and said organic reinforcing filler dispersed with a Z score greater than or equal to 80 in the dried mass;

b) passing the mass leaving the continuous mixer in a cylinder tool to obtain a ribbon; then

c) Introduce the ribbon at the outlet of the cylinder tool and an antioxidant into a continuous mixer so as to obtain a masterbatch;

d) recovering from step c) said masterbatch having a moisture content of less than 1% by weight

characterized in that all of the antioxidant present in the masterbatch obtained at the end of step d) is introduced in step c).

Advantageously, the entire mass leaving the continuous mixer of step a) is sent to the cylinder tool of step b).

The masterbatch advantageously has a dispersion of the reinforcing filler in the elastomeric matrix having a Z score greater than or equal to 90.

Prior to step a) the coagulum is advantageously obtained by mixing in the liquid phase from a latex of the diene elastomer and an aqueous dispersion of the organic reinforcing filler. In particular, it is obtained according to the following steps:

Feeding a continuous stream of the latex of the diene elastomer to a mixing zone of a coagulation reactor defining an elongated coagulation zone extending between the mixing zone and an outlet,

Feeding a continuous flow of a fluid comprising a reinforcing organic load under pressure into the mixing zone of a coagulation reactor to form a coagulated mixture,

- Spin the coagulum obtained previously to recover the wrung coagulum of step a).

In step a) the continuous mixer is advantageously FCM. At the outlet of the continuous mixer of step a), the mass advantageously has a volatile matter content of less than 5% by weight. At the exit of step b) the ribbon advantageously has a volatile matter content of less than 1% by weight. The organic filler is advantageously a carbon black. The carbon black content is advantageously between 40 and 90 phr, preferably between 45 and 80 phr.

The diene elastomer is advantageously a natural rubber.

The antioxidant is advantageously an N-alkyl-N'-phenyl-paraphenyldiamine corresponding to formula (I):

(I)

wherein ¹ represents a linear or branched alkyl group having 1 to 12 carbon atoms or a cycloalkyl group having 5 to 8 carbon atoms. The invention also relates to a method for preparing a rubber composition comprising the following steps:

(A) Preparation of a masterbatch comprising a diene elastomer, a reinforcing organic filler and an antioxidant by the process according to the invention;

(B) High temperature thermomechanical mixing of the masterbatch obtained following step (A) with the other constituents of the rubber composition, except for the vulcanization system;

(C) mechanical work at a temperature below the temperature of step (B) of the product from step (B) and incorporation of the vulcanization system.

I- MEASUREMENTS AND TESTS

The rubber compositions are characterized, before and after firing, as indicated below.

Mooney Plasticity

An oscillating consistometer is used as described in the French standard NF T 43-005 (1991). The Mooney plasticity measurement is carried out according to the following principle: the composition in the green state (Le., Before baking) is molded in a cylindrical chamber heated to 115 ° C. After 5 minutes of preheating, the rotor (of small size) rotates within the specimen at 0.04 revolutions / minute and the useful torque is measured to maintain this movement after 10 minutes of rotation. The Mooney plasticity (MS 5 + 10) is expressed in "Mooney unit" (UM, with 1 UM = 0.83 Newton meter). When the viscosity is too high, the rotor can not rotate and can not measure torque.

Dispersion

In a known manner, the charge dispersion in an elastomeric matrix can be represented by the note Z, which is measured, after crosslinking, according to the method described by S. Otto and Al in Kautschuk Gummi Kunststoffe, 58 Jahrgang, NR 7- 8/2005, in accordance with ISO 11345.

The calculation of the Z score is based on the percentage of area in which the charge is not dispersed ("% undispersed area"), as measured by the "disperGRADER +" apparatus supplied with its operating mode and software. 'disperDATA' exploitation by Dynisco according to the equation:

Z = 100 - (% undispersed area) /0.35

The percentage of undispersed surface is measured by a camera observing the surface of the sample under 30 ° incident light. The bright spots are associated with filler and agglomerates, while the dark spots are associated with the rubber matrix; digital processing transforms the image into a black and white image, and allows the determination of the percentage of undispersed surface, as described by S. Oto in the aforementioned document.

The higher the Z score, the better the dispersion of the charge in the elastomeric matrix (a Z score of 100 corresponding to a perfect dispersion and a Z score of 0 to a mediocre dispersion). It will be considered that a Z score greater than or equal to 80 corresponds to a surface having a very good dispersion of the filler in the elastomeric matrix. Traction tests

These tensile tests make it possible to determine the elastic stress and the properties at break. Unless otherwise indicated, they are carried out in accordance with the French standard NF T 46-002 of September 1988. A second elongation (Le., After a cycle of accommodation at the extension rate provided for the measurement itself) is measured. nominal secant modulus (or apparent stress, in MPa) at 100% elongation (denoted MA100). The tensile measurements for determining the secant accommodating modules are carried out at a temperature of 23 ° C +/- 2 ° C, and under normal humidity conditions (50 +/- 5% relative humidity). tearability

The indices of tearability are measured at 100 ° C. In particular, the force to be exerted to obtain the fracture (FD, in Mpa) is determined on a specimen of dimensions 10 x 105 x 2.5 mm notched at the center of its length to a depth of 5 mm, to cause the rupture of the specimen.

Dynamic Properties

The dynamic properties and in particular tan (5) max, representative of the hysteresis, are measured on a viscoanalyzer (Metravib VA4000), according to the ASTM D 5992-96 standard. 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, is recorded under normal conditions. temperature (23 ° C) according to ASTM D 1349-99. A strain amplitude sweep is carried out from 0.1% to 100% peak-to-peak (forward cycle), then from 100% to 0.1% peak-to-peak (return cycle). The results exploited are the complex dynamic shear modulus (G *) and the loss factor tan (5). For the return cycle, the maximum value of tan (5) observed, denoted tan (5) max, is indicated.

Fatigue MFTR: Test "MFTRA":

The fatigue strength, expressed in number of cycles or in relative units (ur), is measured in a known manner on a non-notched specimen subjected to repeated low frequency tractions up to an elongation of 20%, at the same time. using a Monsanto device ("MFTR" type), until rupture of the test piece, according to the French standard NF T46-021.

II. BRIEF DESCRIPTION OF THE FIGURES

Figure 1 is a photograph of a masterbatch, not according to the invention, during its passage over the cylinder tools.

Figure 2 is a photograph of a masterbatch, according to the invention, during its passage over the cylinder tools.

III. DETAILED DESCRIPTION OF THE INVENTION

In the present description, unless expressly indicated otherwise, all the percentages (%) indicated are% by weight. On the other hand, any range of values designated by the expression "between a and b" represents the range of values from more than a to less than b (i.e. terminals a and b excluded) while any range of values designated by the expression "from a to b" signifies the range of values from a to b (that is to say, including the strict limits a and b).

"Phr" means "parts by weight per hundred parts of elastomer". III-1) Process for preparing a masterbatch

The process according to the invention comprises the following successive stages:

a) Introducing, to obtain a dried mass, a coagulum in at least one continuous mixer said coagulum comprises said diene elastomer and said organic reinforcing filler dispersed with a Z score greater than or equal to 80;

c) Introduce the ribbon at the outlet of the cylinder tool and an antioxidant into a continuous mixer;

characterized in that all of the antioxidant present in the masterbatch obtained at the end of step d) is introduced in step c). The method according to the invention allows that during step b) the entire mass leaving the continuous mixer is sent to said cylinder tool. Thus, compared to the methods of the prior art, significant savings are possible.

The flow rates of steps a) and b) are advantageously greater than 500 kg / h, more preferably greater than 600 kg / h, for example ranging from 600 kg / h to 1300 kg / h. Since the process is a continuous process and all of the mass leaving the continuous mixer is sent to the cylinder tool of step b), the flow rates of steps a) and b) are advantageously identical. For the purposes of the present invention, the term "identical flow rates" means flow rates that do not exceed 10% losses.

In step a), the coagulum advantageously has a dispersion of the reinforcing filler in the elastomeric matrix having a Z score greater than or equal to 90. The masterbatch obtained at the end of the process retains this very good dispersion. This step a) allows drying, mixing with any additives introduced into the mixer, and plastification to obtain a master batch in the form of a dried mass. The additives that may be added do not include an antioxidant.

Prior to step a) the coagulum is advantageously obtained by mixing in the liquid phase from a latex of the diene elastomer and an aqueous dispersion of the organic reinforcing filler.

In particular, the coagulum is obtained according to the following steps:

Feeding a continuous stream of the latex of the diene elastomer to a mixing zone of a coagulation reactor defining an elongated coagulation zone extending between the mixing zone and an outlet, feeding a continuous flow of a fluid comprising a reinforcing organic filler under pressure in the mixing zone of a coagulation reactor to form a coagulated mixture,

The coagulum introduced during step a) is advantageously in the form of granules.

The coagulum introduced during step a) has advantageously been drained to a volatile content ranging from 8% to 20% by weight, usually about 15% by weight. Volatiles are essentially water.

The coagulum is advantageously introduced during step a) at a rate greater than

500 kg / h, more preferably greater than 600 kg / h, still more preferably from 600 kg / h to 1300 kg / h.

In step a) the continuous mixer is advantageously FCM. Conventionally, at the outlet of the continuous mixer of step a), or of the last continuous mixer when several mixers are used, the mass is at a temperature of between 140 ° C. and 200 ° C.

At the output of the continuous mixer of step a), or of the last continuous mixer when several mixers are used, the mass advantageously has a volatile matter content of less than 5% by weight.

Often, when the level of organic reinforcing filler is 65 phr or more, at the outlet of the continuous mixer of step a), or of the last continuous mixer when several mixers are used, the mass has a Mooney viscosity greater than 200. MU. That is, the mass has such a high Mooney viscosity that it can not be measured. Step b) allows plastification of the dried mass obtained following step a). At the outlet of the roll tools, a masterbatch is obtained in the form of a ribbon.

The flow rate of step b) is advantageously greater than 500 kg / h, more preferably greater than 600 kg / h, still more advantageously ranging from 600 kg / h to 1300 kg / h.

In step b), the entire output mass of the continuous mixer of step a), or the last continuous mixer when more than one mixer is used, is sent to the one or more cylinder tools.

Following the plasticization, we recover a ribbon.

This ribbon, at the outlet of step b), is advantageously at a temperature of between 110 ° C. and 160 ° C.

This tape, at the end of step b), advantageously has a volatile matter content of less than 1% by weight, generally from 0.3% to 0.5% by weight.

Following these steps, the ribbon, at the output of the cylinder tool, is introduced into a continuous mixer. Any type of continuous mixer can be used, the extruders being for example well adapted. It is during this stage only that the totality of the antioxidant agent present in the masterbatch obtained at the end of the process will be added.

Other additives can be added. They are preferentially added during step a) but they can also be added during step c). By way of example of these other additives, there may be mentioned, for example, fillers (which may be identical to or different from the charges already present in the coagulum, as an example of filler, mention may be made of zinc oxide), Other diene elastomers which are as defined below, other masterbatch or a masterbatch supplement provided that they do not contain an antioxidant when added in step a) , plasticizers, processing aids (eg stearic acid, liquid polymers, oil, hydrocarbon waxes), resins, flame retardants, extender oils, lubricants, stabilizers ( such as hydroxylamine sulfate), and mixtures thereof.

A photograph of a production of a masterbatch according to the invention during its passage over the rollers of the cylinder tool, at a flow rate of 700 kg / h, is given in FIG. torn and that the ribbon obtained is homogeneous (no tear on the edges) and easy to work (absence of tendrils). By the method according to the invention it is possible to lower the Mooney viscosity of the mixture without degrading its properties. This makes it possible to significantly improve the processability of the mixture on the rollers of the cylinder tool and thus to increase the flow rate on this tool (s) with a cylinder.

111-2) Diene elastomer

Usually, the terms "elastomer" and "rubber", which are interchangeable, are used interchangeably in the text.

By elastomer or "diene" rubber, should be understood in known manner an elastomer derived at least in part (Le., A homopolymer or a copolymer) of monomers dienes (monomers bearing two carbon-carbon double bonds, conjugated or not).

These diene elastomers can be classified into two categories: "essentially unsaturated" or "essentially saturated". The term "essentially unsaturated" is generally understood to mean a diene elastomer derived at least in part from conjugated diene monomers, having a level of units or units of diene origin (conjugated dienes) which is greater than 15% (mol%); for example, diene elastomers such as butyl rubbers or copolymers of dienes and alpha-olefins of the EPDM type do not fall within the above definition and may be especially described as "substantially saturated" diene elastomers ( low or very low diene origin, always less than 15%). In the category of "essentially unsaturated" diene elastomers, the term "highly unsaturated" diene elastomer is particularly understood to mean a diene elastomer having a content of units of diene origin (conjugated dienes) which is greater than 50%.

Among these diene elastomers, there are also natural rubber and synthetic elastomers.

By synthetic diene elastomers which can be used in accordance with the invention, the term diene elastomer is more particularly understood to mean:

(a) - any homopolymer obtained by polymerization of a conjugated diene monomer having from 4 to 12 carbon atoms;

(b) - any copolymer obtained by copolymerization of one or more conjugated dienes with each other or with one or more vinyl aromatic compounds having from 8 to 20 carbon atoms; (c) - a ternary copolymer obtained by copolymerizing ethylene, an α-olefin having 3 to 6 carbon atoms with a non-conjugated diene monomer having from 6 to 12 carbon atoms, carbon, such as elastomers obtained from ethylene, propylene with a non-conjugated diene monomer of the aforementioned type such as in particular 1,4-hexadiene, ethylidene norbornene, dicyclopentadiene;

(d) - a copolymer of isobutene and isoprene (butyl rubber), as well as the halogenated versions, in particular chlorinated or brominated, of this type of copolymer.

As conjugated dienes 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-di (C ₁ -C ₅ alkyl) -1,3-butadienes, such as for example 2,3-dimethyl-1,3-butadiene, 2,3-diethyl-1,3-butadiene, 2-methyl-3-ethyl-1,3-butadiene, 2-methyl-3-isopropyl-1 3-butadiene, aryl-1,3-butadiene, 1,3-pentadiene, 2,4-hexadiene. Examples of suitable vinylaromatic compounds are styrene, ortho-, meta-, para-methylstyrene, the "vinyl-toluene" commercial mixture, paratertiobutylstyrene, methoxystyrenes, chlorostyrenes, vinylmesitylene, divinylbenzene and vinylnaphthalene. The copolymers may contain between 99% and 20% by weight of diene units and between 1% and 80% by weight of vinylaromatic units. The elastomers may have any microstructure which is a function of the polymerization conditions used, in particular the presence or absence of a modifying and / or randomizing agent and the amounts of modifying and / or randomizing agent used. The elastomers can be for example block, statistical, sequenced, microsequenced, and be prepared in dispersion or in solution; they may be coupled and / or starred or functionalized with a coupling agent and / or starring or functionalization. For coupling with carbon black, there may be mentioned, for example, functional groups comprising a C-Sn bond or amine functional groups such as aminobenzophenone for example; for coupling to an inorganic filler such as silica, there may be mentioned, for example, silanol or polysiloxane functional groups having a silanol end (as described, for example, in F 2 740 778 or US Pat. No. 6,013,718, and WO 2008/141702), alkoxysilane groups (as described for example in FR 2,765,882 or US 5,977,238), carboxylic groups (as described for example in WO 01/92402 or US 6,815,473, WO 2004/096865 or US 2006/0089445). ) or else polyether groups (as described for example in EP 1 127 909 or US 6,503,973, WO 2009/000750 and WO 2009/000752). As other examples of functionalized elastomers, mention may also be made of elastomers (such as SBR, BR, NR or IR) of the epoxidized type.

Suitable polybutadienes and in particular those having a content (mol%) in units -1.2 of between 4% and 80% or those having a content (mol%) of cis-1,4 greater than 80%, polyisoprenes, butadiene-styrene copolymers and in particular those having a Tg (glass transition temperature (Tg, measured according to ASTM D3418) between 0 ° C. and -70 ° C. and more particularly between -10 ° C. and -60 ° C., a styrene content of between 5% and 60% by weight; weight and more particularly between 20% and 50%, a content (mol%) in -1,2 bonds of the butadiene part of between 4% and 75%, a content (mol%) in trans-1,4 bonds between 10% and 80%, butadiene-isoprene copolymers and especially those having an isoprene content of between 5% and 90% by weight and a Tg of -40 ° C to -80 ° C, the isoprene-styrene copolymers and in particular those having a styrene content of between 5% and 50% by weight and a Tg of between -5 ° C. and -50 ° C. In the case of butadiene-styrene-isoprene copolymers, those having a styrene content between 5% and 50% by weight and more particularly between 10% and 40%, an isoprene content of between 15% and 60% by weight and more particularly between 20% and 50%, a butadiene content of between 5% and 50% by weight and more particularly between 20% and 40%, a content (mol%) in -1,2 units of the part butadiene content between 4% and 85%, a content (mol%) in trans-1,4 units of the butadiene part of between 6% and 80%, a content (mol%) in units -1,2 plus -3, 4 of the isoprenic portion of between 5% and 70% and a content (mol%) in trans units -1,4 of the isoprenic portion of between 10% and 50%, and more generally any butadiene-styrene-isoprene copolymer having a Tg between -5 ° C and -70 ° C.

In summary, the synthetic diene elastomer (s) according to the invention are preferably chosen from the group of highly unsaturated diene elastomers consisting of polybutadienes (abbreviated as "B"), synthetic polyisoprenes (IR), butadiene copolymers, copolymers of isoprene 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).

As has been mentioned above, the liquid phase mixing processes are preferably used to obtain masterbatches based on diene elastomer and reinforcing organic filler having a very good dispersion of the organic reinforcing filler in the elastomer. Thus, in particular, for producing the masterbatch of diene elastomer and of reinforcing organic filler, a diene elastomer latex will be used more particularly, the elastomer latex being a particular form of elastomer which is in the form of diene elastomers. elastomer scattered in the water. The invention therefore preferably relates to diene elastomer latices, the diene elastomers being those defined above.

More particularly, for the natural rubber (NR) which composes all or part of the elastomer according to the invention, this natural rubber exists in various forms as detailed in Chapter 3 "Latex concentrates: properties and composition", K.F. Gaseley, A.D.T. Gordon and TD Pendle in "Natural Rubber Science and Technology", AD Roberts, Oxford University Press - 1988. In particular several forms of natural rubber latex are marketed: so-called "field latex" natural rubber latexes , the so-called "natural concentrated rubber rubber latex", the epoxy latex ("ENR"), the deproteinized latex or the prevulcanized latex. Field natural rubber latex is a latex in which ammonia has been added to prevent premature coagulation and the concentrated natural rubber latex is a field latex which has been treated to a wash followed by a new concentration. The different categories of concentrated natural rubber latex are listed in particular according to ASTM D 1076-06. Among these concentrated natural rubber latexes, there are in particular concentrated natural rubber latexes of quality called "HA" (high ammonia) and quality called "LA"; Advantageously used for the invention concentrated natural rubber latex HA grade. The NR latex can be modified beforehand physically or chemically (centrifugation, enzymatic treatment, chemical modification, etc.). The latex can be used directly or be diluted beforehand in water to facilitate its implementation.

It will be appreciated that one or more natural rubber latices may be used in cutting, or a blend of one or more natural rubber latices with one or more synthetic rubber latices.

Thus, using synthetic elastomer latex, the latex can in particular consist of a synthetic diene elastomer already available in the form of an emulsion (for example a copolymer of butadiene and styrene, SBR, prepared in emulsion), or a diene elastomer. synthetic solution initially (for example a SBR prepared in solution) which is emulsified in a mixture of organic solvent and water, generally by means of a surfactant.

Particularly suitable for the invention is an SBR latex, in particular an emulsion-prepared SBR ("ESBR") or an SBR prepared in solution ("SSBR"), and more particularly an SBR prepared in emulsion. There are two main types of emulsion copolymerization processes styrene and butadiene, one of them, or hot process (implemented at a temperature close to 50 ° C), being adapted for the preparation of highly branched SB while the other, or method of cold (implemented at a temperature ranging from 15 ° C to 40 ° C), makes it possible to obtain more linear SBRs. For a detailed description of the effectiveness of several emulsifiers that can be used in said hot process (as a function of the levels of said emulsifiers), reference may be made, for example, to the two articles by CW Carr, 1. M. Kolthoff, EJ Meehan, University of Minesota, Minneapolis, Minesota, which appeared in Journal of Polymer Science, 1950, Vol. V, No. 2, pp. 201-206, and 1951, Vol. VI, No. 1, pp. 73-81. With regard to comparative examples of implementation of said cold process, reference may be made, for example, to the article ½ Industrial and Engineering Chemistry, 1948, Vol. 5 40, No. 5, pp. 932-937, EJ Vandenberg, GE Hulse, Hercules Powder Company, Wilmington, Delaware + and Article ½ Industrial and Engineering Chemistry, 1954, Vol. 46, No. 5, pp. 1065-1073, JR Miller, HE Diem, BF Goodrich Chemical Co., Akron, Ohio.

In the case of an SBR elastomer (ESBR or SSBR), an SBR having an average styrene content, for example between 20% and 35% by weight, or a high styrene content, for example 35 to 35% by weight, is used in particular. 45%, a vinyl ring content of the butadiene part of between 15% and 70%, a content (mol%) of trans-1,4 bonds of between 15% and 75% and a Tg of between -10 ° C. and - 55 ° C; such an SBR can be advantageously used in admixture with a BR preferably having more than 90% (mol%) of cis-1,4 bonds.

11-3) Reinforcing filler

The reinforcing filler comprises a reinforcing organic filler. As reinforcing organic filler all carbon blacks are suitable. Carbon blacks are suitable for all carbon blacks, in particular blacks of the HAF, ISAF, SAF type conventionally used in tires (so-called pneumatic grade blacks). Among these, the reinforcing carbon blacks of the 100, 200 or 300 series (ASTM grades), for example the N115, N134, N234, N326, N330, N339, N347 or N375 blacks, or even targeted applications, blacks of higher series (eg N400, N660, N683, N772, N990). As carbon black, carbon blacks partially or completely covered with silica by a post-treatment, or carbon blacks modified in situ by silica such as, without limitation, the fillers, are also suitable. marketed by Cabot Corporation under the name EcoblackTM "CRX 2000" or "CRX4000".

It will be possible to envisage using the reinforcing organic filler alone or in blending with a reinforcing inorganic filler.

By "inorganic filler" is meant here, in a known manner, any inorganic or mineral filler whatever its color and origin (natural or synthetic), also called "white" filler, "clear" filler or filler. "non-black"("non-blackfiller") as opposed to carbon black, this inorganic filler being able to reinforce on its own, with no other means than a possible intermediary coupling agent, a rubber composition intended for the manufacturing a tire tread, in other words able to replace, in its reinforcing function, a conventional tire grade carbon black for tread. Such a filler is generally characterized by the presence of functional groups, in particular hydroxyl (-OH), at its surface, which may need to be used as a reinforcing filler for the use of an agent or coupling system intended to ensure a connection. chemical stable between the isoprene elastomer and said charge. Such an inorganic filler can therefore be used alone or with a coupling agent to allow the reinforcement of the rubber composition in which it is included. The physical state in which the inorganic filler is present is indifferent whether in the form of powder, microbeads, granules, beads or any other suitable densified form. Of course, inorganic filler is also understood to mean mixtures of different inorganic fillers, in particular highly dispersible siliceous and / or aluminous fillers as described below. Suitable inorganic fillers are, in particular, mineral fillers of the siliceous type, in particular silica (SiO ₂ ), or aluminous type, in particular alumina (Al ₂ O ₃ ). The silica used may be any silica known to those skilled in the art, especially 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. /boy Wut. As highly dispersible precipitated silicas (referred to as "HDS"), mention may be made, for example, of the Ultrasil 7000 and Ultrasil 7005 silicas from Evonik, the Zeosil 1165MP, 1135MP and 1115MP silicas from Rhodia, the Hi-Sil EZ150G silica from the PPG company, the Zeopol 8715, 8745 and 8755 silicas of the Huber Company, the high surface area silicas as described in the application WO 03/016387. In order to couple the reinforcing inorganic filler to the diene elastomer, an at least bifunctional coupling agent (or bonding agent) is used in known manner to ensure a sufficient chemical and / or physical connection between the inorganic filler ( surface of its particles) and the diene elastomer, in particular organosilanes or bifunctional polyorganosiloxanes. In particular, polysulfide silanes, called "symmetrical" or "asymmetrical" silanes according to their particular structure, are used, as described for example in the applications WO03 / 002648 (or US 2005/016651) and WO03 / 002649 (or US 2005/016650). Preferably, the total charge rate (carbon black and, if appropriate, inorganic filler such as silica) is between 40 and 200 phr, more preferably between 40 and 150 phr and even more preferably between 40 and 100 phr. optimum being known in different ways according to the particular applications concerned: the level of reinforcement expected on a bicycle tire, for example, is of course less than that required on a tire capable of driving at high speed in a sustained manner, for example a motorcycle tire , a tire for passenger vehicle or commercial vehicle such as Heavy weight. According to one embodiment of the invention, the reinforcing filler is carbon black. Carbon black is advantageously used, the content of which varies from 40 to 90 phr, advantageously from 45 to 80 phr.

Advantageously, the masterbatch does not comprise a coupling agent, even in the presence of an inorganic reinforcing filler.

Advantageously, the masterbatches and the compositions thus produced may be used in tire applications. The tire rubber compositions based on the masterbatch and the inorganic filler mixture according to the invention may also comprise, in known manner, a covering agent and, where appropriate, a coupling agent.

1-4) Antioxidant agent

One or more antioxidant agents may be used as the antioxidant.

The antioxidant may be amine, phenol, imidazole, carbamate metal salt, para-phenylene diamine (s) and / or dihydrotrimethylquinoline (s), polymerized quinine, wax or any other antioxidant usually used in elastomer formulations. . As a specific example, there may be mentioned: N- (l, 3-dimethylbutyl) -N'-phenyl-p-phenylenediamine (6-PPD, marketed for example under the trademarks ^® ANTIGEN 6C by Sumitomo Chemical Co., Ltd. . NOCLAC ^® 6C by Ouchi Shinko Chemical Industrial Co., Ltd.), the product "Ozonon" 6C available from Seiko Chemical Co., Ltd., the l, 2-dihydro-2,2,4-trimethyl quinoline polymerized (TMQ , sold for example under the trademark Agerite Resin D, by RT Vanderbilt), butylated hydroxytoluene (BHT), and butylhydroxyanisole (BHA).

The antioxidant agent is advantageously an N-alkyl-N'-phenyl-paraphenyldiamine corresponding to formula (I):

wherein R ¹ represents a linear or branched alkyl group having 1 to 12 carbon atoms or a cycloalkyl group having 5 to 8 carbon atoms.

Preferably, R ¹ represents an alkyl having from 2 to 8 carbon atoms, preferably chosen from the group consisting of ethyl, propyl (ln, n-propyl, iso-propyl), butyl (l, n-butyl, dry -butyl and tert-butyl), pentyl, hexyl, heptyl and octyl, or a cycloalkyl group having 5 to 8 carbon atoms (cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl), more preferably a cyclohexyl group.

More preferably, compounds whose R ¹ groups are branched, of formulas (I -bis) below:

(1-bis)

in which R ⁴ , R ⁵ , which are identical to or different from each other, each represent an alkyl group whose number of carbon atoms is in accordance with the preferred definitions given above for R ¹ .

As more preferred examples of branched radicals R ¹ , mention will be made in particular of isopropyl, 1,3-dimethylbutyl and 1,4-dimethylpentyl.

The compounds of formula (I-bis) above are well known to those skilled in the art. They have been used for a very long time as anti-aging rubber compositions for tires, especially in the belts of such tires, and belong to the family of paraphenylenediamine derivatives ("PPD") such as for example

N-isopropyl-N'-phenyl-para-phenylenediamine ("1-PPD")

or N-1,3-dimethylbutyl-N'-phenyl-para-phenylenediamine ("6-PPD")

both excellent antioxidants and antiozonants (see eg WO 2004/033548, WO 2005/063510).

The antioxidants are usually introduced in an amount ranging from 0.5 phr to 5 phr.

11-5) Other additives

These rubber compositions in accordance with the invention may also comprise all or part of the usual additives normally used in elastomer compositions intended for the manufacture of tires, in particular treads, for example plasticizers or lubricating oils. extension, whether aromatic or non-aromatic, pigments, protective agents such as antiozone waxes, chemical antiozonants, anti-fatigue agents, reinforcing resins, acceptors (for example phenolic novolac resin) or methylene donors (for example HMT or H3M) as described for example in the application WO 02/10269, a crosslinking system based on either sulfur or sulfur and / or peroxide and / or bismaleimide donors , vulcanization accelerators.

Preferably, these compositions comprise, as preferred non-aromatic or very weakly aromatic plasticizing agent, at least one compound selected from the group consisting of naphthenic, paraffinic, MES, TDAE oils, esters (especially trioleate) oils. glycerol, the hydrocarbon plasticizing resins having a high Tg preferably greater than 30 ° C, and mixtures of such compounds. It will be noted that it is also conceivable to produce the masterbatches according to the invention by incorporating, especially before the drying phase of the production of the masterbatch in the liquid phase, additives as described above, oil, antioxidant, coupling agent , debt collector ...

111-6) Manufacture of rubber compositions:

The invention also relates to a method for preparing a rubber composition comprising the following steps:

A) Preparation of a masterbatch comprising a diene elastomer, a reinforcing organic filler and an antioxidant by the process according to the invention;

B) thermomechanical mixing at high temperature of the masterbatch obtained following step A) with the other constituents of the rubber composition, with the exception of the vulcanization system;

C) Mechanical work at a temperature below the temperature of step B) of the product from step B) and incorporation of the vulcanization system.

The rubber compositions of the invention are manufactured in suitable mixers, using two successive preparation phases (steps B) and C) according to a general procedure well known to those skilled in the art: a first phase of work or mixing thermomechanical system (sometimes referred to as a "non-productive" phase) at a high temperature, up to a maximum temperature of between 130 ° C and 200 ° C, preferably between 145 ° C and 185 ° C, followed by a second mechanical working phase (sometimes called a "productive" phase) at a lower temperature, typically less than 120 ° C, for example between 60 ° C and 100 ° C, finishing phase during which the crosslinking system is incorporated; vulcanization.

According to one embodiment of the invention, all the basic constituents of the compositions of the invention, with the exception of the vulcanization system, are intimately incorporated, by kneading, during the first so-called non-productive phase, that is to say that is introduced into the mixer and which is kneaded thermomechanically, in one or more steps, at least these various basic constituents until the maximum temperature between 130 ° C and 200 ° C, preferably between 145 ° C and 185 ° C.

According to a preferred embodiment of the invention, the basic constituents of the compositions of the invention, with the exception of the vulcanization system, are incorporated in the diene elastomer and the reinforcing filler which have been previously prepared in the form of a first masterbatch.

This first masterbatch is made in "liquid" phase. For this purpose, the diene elastomer in the form of latex, which is in the form of elastomer particles dispersed in water, and an aqueous dispersion of carbon black, that is to say a load dispersed in water, commonly called "slurry". More preferably still, the process steps described in document US Pat. No. 6,048,923, which consists in particular in incorporating a continuous flow of a first fluid constituted by the elastomer latex into the mixing zone of a coagulation reactor, will be followed. incorporating a second continuous stream of a second fluid consisting of the aqueous dispersion of carbon black under pressure in the mixing zone to form a mixture with the elastomer latex; the mixing of these two fluids being sufficiently energetic to allow the elastomer latex to be coagulated almost completely with the carbon black before the exit orifice of the coagulation reactor and then to dry the coagulum obtained according to the process of the invention.

According to another preferred embodiment of the invention, an inorganic filler and a second elastomer are incorporated in the first masterbatch also in the form of a second masterbatch which has been previously prepared. This second masterbatch can be prepared in particular in solid form by thermomechanical mixing of the second elastomer and the inorganic filler; it can also be prepared by any other method and in particular it can also be prepared in the liquid phase.

It will be noted in particular that in the case of the incorporation of a second elastomer and / or an inorganic filler, this or these incorporations can be carried out simultaneously with the introduction into the mixer of the other constituents (in particular the first diene elastomer or first masterbatch) but also advantageously that this or these incorporations can be shifted in time from a few tens of seconds to a few minutes.

Note that in the case of an addition of an inorganic filler and a second elastomer, they may be introduced separately or in the form of a second master batch containing the second elastomer and the inorganic filler. In the case of the introduction of the second elastomer alone and the inorganic filler alone, shifted in time from a few tens of seconds to a few minutes, the inorganic filler can be introduced before, after or simultaneously with the second elastomer.

By way of example, the first (non-productive) phase is carried out in a single thermomechanical step during which all the necessary constituents (in the form where appropriate) are introduced into a suitable mixer such as a conventional internal mixer. of masterbatches as specified above), any additional coating or processing agents and other miscellaneous additives, with the exception of the vulcanization system. The total mixing time in this non-productive phase is preferably between 1 and 15 minutes. After cooling the mixture thus obtained during the first non-productive phase, the vulcanization system is then incorporated at low temperature, generally in an external mixer such as a roller mixer; the whole is then mixed (productive phase) for a few minutes, for example between 2 and 15 min.

The crosslinking system is preferably a vulcanization system, that is to say a system based on sulfur (or a sulfur-donor agent) and a primary vulcanization accelerator. To this basic vulcanization system are added, incorporated during the first non-productive phase and / or during the production phase as described later, various known secondary accelerators or vulcanization activators such as zinc oxide. stearic acid or equivalent compounds, guanidine derivatives (in particular diphenylguanidine).

Sulfur is used at a preferential rate of between 0.5 and 12 phr, in particular between 1 and 10 phr. The primary vulcanization accelerator is used at a preferred level of between 0.5 and 10 phr, more preferably between 0.5 and 5.0 phr.

As accelerator (primary or secondary) can be used any compound capable of acting as an accelerator of vulcanization of diene elastomers in the presence of sulfur, in particular thiazole-type accelerators and their derivatives, accelerators of thiuram type, zinc dithiocarbamates. These accelerators are for example selected from the group consisting of 2-mercaptobenzothiazyl disulfide (abbreviated "MBTS"), tetrabenzylthiuram disulfide ("TBZTD"), N-cyclohexyl-2-benzothiazyl sulfenamide ("CBS"), N, N dicyclohexyl-2-benzothiazyl sulphenamide ("DCBS"), N-tert-butyl-2-benzothiazyl sulphenamide ("TBBS"), N-tert-butyl-2-benzothiazyl sulphenimide ("TBSI"), zinc dibenzyldithiocarbamate (" ZBEC ") and mixtures of these compounds. The final composition thus obtained is then calendered, for example in the form of a sheet or a plate, in particular for a characterization in the laboratory, or else extruded in the form of a rubber profile that can be used, for example, as a tread. tires for passenger cars, trucks etc.

It will be noted that such a composition may advantageously constitute the entire tread. But the invention also applies to cases where these rubber compositions form only part of a composite tread consisting for example of two radially superimposed layers of different formulations (so-called "cap-base" structure), both intended to come into contact with the road during the running of the tire, during the life of the latter. The part based on compositions in accordance with the invention may then constitute the radially outer layer of the tread intended to come into contact with the ground from the beginning of the rolling of the new tire, or on the contrary its radially inner layer intended to contact the soil later.

IV EXAMPLES OF CARRYING OUT THE INVENTION

The Mooney plasticity is expressed in "Mooney unit" (UM, with 1 UM = 0.83 Newton meter). Example 1

IV.l Preparation of masterbatch of natural rubber and carbon black

The coagulum of natural rubber (100 phr) and carbon black (72 phr) having a very good note of dispersion of the charge in the elastomeric matrix are made in the liquid phase according to the process described in U.S. Patent No. 6,048,923.

They are then dried according to the following methods:

Ml master mix (not according to the invention):

At the outlet of the wringer, pellets at a rate of 700 kg / h dry product and loaded with 15% volatile matter (mainly water) are sent to the FCM. The 6-PPD is injected at the entrance of the FCM at a rate of 1.2 phr.

At the outlet of the FCM, the mixture called chunk leaves at 165 ° C and a volatile matter content of between 1 and 3%. The Mooney viscosity measured for this composite (MS) is> 200 and is therefore not measurable by the machine (overtorque).

Just at the end of the FCM, only half of the production (350kg / h) is sent to the cylinder tool (oll Mill), the other half is thrown away. At the outlet of the roll mill, the composite has a temperature around 155 ° C, a Mooney viscosity of 150-170 on average and a volatile matter content <1%, generally around 0.4 %. This RM output composite, called strip, is then sent towards the end of the line. Master mix M2 (according to the invention):

At the exit of the wringer, pellets at a rate of 750kg / h dry product and loaded with 15% volatile (essentially water) are sent to the FCM. With this recipe, there is no injection of 6-PPD at the FCM.

At the end of the FCM, the entire production (750kg / h) is sent to the Roll Mill tool.

At the outlet of the roll mill, the composite has a temperature around 155 ° C, a Mooney viscosity of between 125 and 145 and a volatile content <1%, generally around 0.4%.

This composite called strip is then sent to the prebreaker where it is mixed with 1.2 pce of 6-PPD. At the exit of prebreaker the composite is sent towards the end of line.

IV-2 Preparation of rubber compositions

The different compositions were made from the master batch Ml or M2.

The following tests are carried out in the following manner: the master mixture M1 or M2 is introduced into an internal mixer, filled to 70% and whose initial tank temperature is about 60.degree. Thermomechanical work (non-productive phase) is then carried out in one step (total mixing time equal to about 5 minutes), until a maximum temperature of "fall" of about 165 ° C. is reached.

The resulting mixture is recovered, cooled and the vulcanization system is added.

(sulfur and sulfenamide accelerator) on an external mixer at 70 ° C, mixing the whole

(productive phase) for about 5 to 6 min.

The compositions thus obtained are then calendered either in the form of plates (thickness of 2 to 3 mm) or thin sheets of rubber for the measurement of their physical or mechanical properties, or in the form of profiles that can be used directly, after cutting and / or or assembly to the desired dimensions, for example as semi-finished products for tires, in particular as treads of tires. IV-3 Mechanical properties

This example is intended to demonstrate that the properties of a rubber composition obtained with a masterbatch according to the invention has the same mechanical properties as a masterbatch obtained by a conventional method.

The composition C1, not in accordance with the invention, is prepared from a master batch M1 according to the method detailed in section IV-2.

The composition C2 according to the invention is prepared from a master batch M2 according to the method detailed in section IV-2.

The set of compositions has the following basic formulation (in phr):

Table 1

(1) 6-PPD: N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine: antioxidant

(2) ZnO: Zinc Oxide

(3) N-cyclohexyl-2-benzothiazyl sulfenamide ("Santocure CBS" from Flexsys); accelerator

The properties measured after cooking at 130 ° C. for 60 minutes are given in Table 2 below.

Table 2

Cl and C2 products have the same mechanical properties. Example 2

IV.4 Preparation of masterbatch of natural rubber and carbon black

The coagulum of natural rubber (100 phr) and carbon black (50 phr) having a very good note of dispersion of the filler in the elastomeric matrix are made in the liquid phase according to the process described in U.S. Patent No. 6,048,923.

They are then dried according to the following methods:

M3 master mix (not according to the invention):

At the exit of the wringer, pellets at a rate of 1000 kg / h dry product and loaded with 15% volatile matter (essentially water) are sent to the FCM. The 6-PPD is injected at the entrance of the FCM at a rate of 1.2 phr.

At the outlet of the FCM, the mixture called chunk leaves at 160 ° C and a volatile material content of between 1 and 3%. The Mooney viscosity measured for this composite (MS) is between 95 and 115.

At the end of the FCM, the entire production (1000kg / h) is sent to the cylinder tool (oll Mill).

At the outlet of the roll mill, the composite has a temperature around 155 ° C, a Mooney viscosity of 85-95 on average and a volatile content <1%, generally around 0.4 %. This RM output composite, called strip, is then sent towards the end of the line. M4 master mix (according to the invention):

At the exit of the wringer, pellets at a rate of 1000 kg / h dry product and loaded with 15% volatile matter (essentially water) are sent to the FCM. With this recipe, there is no injection of 6-PPD at the FCM.

At the outlet of the FCM, the mixture called chunk leaves at 165 ° C and a volatile matter content of between 1 and 3%. The Mooney viscosity measured for this composite (MS) is between 95 and 115.

At the end of the FCM, the entire production (1000kg / h) is sent to the Roll Mill tool.

At the outlet of the roll mill, the composite has a temperature around 155 ° C., a Mooney viscosity of between 55 and 65 and a volatiles content of <1%, generally around 0.4%. This composite called strip is then sent to the prebreaker where it is mixed with 1 pce of 6-PPD. At the exit of prebreaker the composite is sent towards the end of line. IV-5 Preparation of rubber compositions

The different compositions were made from the masterbatch M3, and M4.

The following tests are carried out in the following manner: the masterbatch M3 or M4 is introduced into an internal mixer, filled to 70% and whose initial tank temperature is approximately 60.degree. Thermomechanical work (non-productive phase) is then carried out in one step (total mixing time equal to about 5 minutes), until a maximum temperature of "fall" of about 165 ° C. is reached.

The mixture thus obtained is recovered, cooled and the vulcanization system (sulfur and sulfenamide accelerator) is added to an external mixer at 70 ° C., mixing the whole (productive phase) for about 5 to 6 minutes.

The compositions thus obtained are then calendered either in the form of plates (thickness of 2 to 3 mm) or thin sheets of rubber for the measurement of their physical or mechanical properties, or in the form of profiles that can be used directly, after cutting and / or or assembly to the desired dimensions, for example as semi-finished products for tires, in particular as treads of tires.

IV-6 Mechanical properties

Composition C3, which is not in accordance with the invention, is prepared from a masterbatch M3 according to the method detailed in section IV-5.

The composition C4 according to the invention is prepared from a master batch M4 according to the method detailed in section IV-5.

The set of compositions has the following basic formulation (in phr):

Table 3 (1) 6-PPD: N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine: antioxidant

(2) ZnO: Zinc Oxide

The properties measured after cooking at 150 ° C. for 40 minutes are given in Table 4 below.

Table 4

Products C3 and C4 have the same mechanical properties.

By the suppression of the injection of the 6-PPD at FCM (Farrel Continuous Mixer) upstream of Roll Mill on:

• Lowers the Mooney viscosity of the composite,

· Increases throughput

and this without degrading the properties of the composite in mixture.

Stopping the injection of 6-PPD at the FCM significantly improves the cohesion of the composite on the Roll Mill, quickly lowering its Mooney viscosity and increasing the production rate (for the example of 72 pce in carbon black the increase in flow is 100%, it is more than 30% for the example of 50 phr carbon black).

Claims

claims

A process for the preparation of a masterbatch, comprising a diene elastomer and a reinforcing organic filler, an antioxidant, and having a dispersion of the reinforcing filler in the elastomeric matrix having a Z-score greater than or equal to 80, the elastomer diene comprises at least natural rubber, the process comprises the following successive steps:

a) introducing, to obtain a dried mass, a coagulum in at least one heated continuous mixer, said coagulum comprises said diene elastomer and said organic reinforcing filler dispersed with a Z score greater than or equal to 80 in the dried mass;

c) Introduce the ribbon at the outlet of the cylinder tool and the antioxidant into a continuous mixer so as to obtain a masterbatch;

2. Method according to claim 1, characterized in that all of the mass leaving the continuous mixer of step a) is sent to the cylinder tool of step b).

Process according to Claim 1 or 2, characterized in that the masterbatch has a dispersion of the reinforcing filler in the elastomeric matrix having a Z-score greater than or equal to 90.

Process according to any one of the preceding claims, characterized in that prior to step a) the coagulum is obtained by mixing in the liquid phase from a latex of the diene elastomer and an aqueous dispersion of the filler. reinforcing organic. Process according to Claim 4, characterized in that the coagulum is obtained according to the following steps:

Method according to any one of the preceding claims, characterized in that during step a) the continuous mixer is an FCM.

Process according to any one of the preceding claims, characterized in that at the outlet of the continuous mixer of step a), the mass has a volatile matter content of less than 5% by weight.

Process according to any one of the preceding claims, characterized in that at the outlet of step b) the ribbon has a volatile matter content of less than 1% by weight.

9. Process according to any one of the preceding claims, characterized in that the reinforcing organic filler is a carbon black.

10. The method of claim 9, characterized in that the carbon black content is between 40 and 90 phr, preferably between 45 and 80 phr.

11. Process according to any one of the preceding claims, characterized in that the diene elastomer is a natural rubber.

12. Process according to any one of the preceding claims, characterized in that the antioxidant agent is an N-alkyl-N'-phenyl-paraphenyldiamine corresponding to formula (I):

(I)

A process for preparing a rubber composition comprising the steps of:

(A) preparing a masterbatch comprising a diene elastomer, a reinforcing organic filler and an antioxidant by the process of any one of the preceding claims;