Rubber composition comprising masterbatch

Abstract

To provide a rubber composition based on a filler comprising at least one diene elastomer, at least carbon black and an inorganic filler, particularly silica, in which the filler is very well dispersed in the elastomer matrix.SOLUTION: The invention relates to a rubber composition based on: at least one diene elastomer; a filler comprising at least carbon black and an inorganic filler with an inorganic filler content less than or equal to 50 pts.wt. per hundred parts of elastomer (phr); and a crosslinking system.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a rubber composition based on at least one diene elastomer, at least carbon black, and a filler containing an inorganic filler, in particular silica, which provides a very good dispersion of the filler in the elastomer matrix. More particularly, the present invention relates to a process for preparing such a composition based on at least one masterbatch containing a diene elastomer and carbon black, which masterbatch itself provides a very good dispersion of the carbon black in the elastomer matrix.

[0002]

[0002] The term "masterbatch" is understood to mean an elastomer-based composite into which fillers and possibly other additives have been incorporated.

[0003] The invention particularly relates to the use of such masterbatches for the preparation of diene rubber compositions reinforced with a blend of organic and inorganic fillers for the purpose of producing tires or semi-finished products for tires, in particular the treads of these tires. [Background technology]

[0004]

[0004] In order to obtain optimal reinforcing and hysteresis properties imparted to a tire tread by a filler, and thus high abrasion resistance and low rolling resistance, it is generally known that it is desirable for the filler to be present in a final form that is as finely divided as possible and as uniformly distributed as possible in the elastomer matrix. However, such a state can only be achieved if the filler has a very good ability, on the one hand, to be incorporated into the matrix and deagglomerate during mixing with the elastomer, and, on the other hand, to disperse uniformly throughout this matrix.

[0005] This has become possible thanks in particular to the use of novel rubber compositions at least partially reinforced with inorganic fillers, particularly silica, which can rival conventional tire-grade carbon black from the standpoint of reinforcing.

[0006] However, due to their mutual affinity, these inorganic filler particles have an undesirable tendency to agglomerate with one another in the elastomer matrix. These interactions have the deleterious effect of limiting the dispersion of the filler, and hence the reinforcing properties, to a level substantially lower than would theoretically be possible if all the (inorganic filler / elastomer) bonds that could be created during the compounding operation were actually obtained. These interactions also tend to increase the viscosity of the rubber composition in the uncured state, thus making even highly dispersible silica more difficult to process than when carbon black is present.

[0007] There are various methods for obtaining masterbatches of diene elastomers and reinforcing fillers. In particular, one solution consists of compounding the elastomer and filler in the "liquid" phase to improve the dispersion of the filler in the elastomer matrix. To do so, the process involves the preparation of an elastomer in the form of a latex, which is in the form of elastomer particles dispersed in water, and an aqueous dispersion of the filler, i.e., the filler dispersed in water, commonly referred to as a "slurry." In particular, certain processes, such as those described in U.S. Pat. No. 6,048,923, make it possible to obtain masterbatches of elastomers and fillers with a very good dispersion of the filler in the elastomer matrix, which is greatly improved compared to the dispersion of the filler in the elastomer matrix that can be obtained during solid-phase compounding of the elastomer and reinforcing filler. This process comprises, inter alia, introducing into the compounding zone of a coagulation reactor a continuous flow of a first fluid consisting of an elastomer latex, and introducing into the compounding zone under pressure a second continuous flow of a second fluid consisting of an aqueous dispersion of a filler to form a mixture with the elastomer latex, the compounding of these two fluids being sufficiently energetic to allow almost complete coagulation of the elastomer latex together with the filler prior to the exit of the coagulation reactor, and then drying the coagulate obtained.

[0008] This process is particularly suitable for producing masterbatches with very good dispersion starting from natural rubber latex and carbon black. Indeed, the application of this process is particularly advantageous due to the ability of natural rubber latex and carbon black to undergo spontaneous coagulation. However, such a process is limited by the carbon black content present in the masterbatch. An approach to control the total filler content of rubber compositions containing carbon black masterbatches without affecting processability is desirable. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] U.S. Patent No. 6,048,923 [Patent Document 2] U.S. Patent No. 6,936,669 [Patent Document 3] U.S. Patent No. 7,981,966 [Patent Document 4] U.S. Patent No. 8,217,103 [Patent Document 5] U.S. Patent No. 8,569,409 [Patent Document 6] U.S. Patent No. 5,064,901 [Patent Document 7] International Publication No. 03 / 16837 [Patent Document 8] U.S. Patent No. 6,608,125 [Patent Document 9] U.S. Patent Application Publication No. 2006 / 0041063 [Patent Document 10] U.S. Patent Application Publication No. 2003 / 0130535 [Patent Document 11] WO 02 / 10269 [Non-patent literature]

[0010] [Non-Patent Document 1] S. Otto et al., Kautschuk Gummi Kunststoffe, 58th edition, NR 7-8 / 2005 [Non-patent document 2] KF Gaseley, A.D. T. Gordon and T.D. Pendle, Chapter 3, "Latex concentrates: properties and composition," in "Natural Rubber Science and Technology," A.D. Roberts, Oxford University Press, 1988 [Non-patent document 3] Journal of Polymer Science of 1950, Vol. V, No. 2, pp. 201-206 [Non-patent document 4] Journal of Polymer Science of 1951, Vol. VI, No. 1, pp. 73-81 [Non-patent document 5] 1 / 2 Industrial and Engineering Chemistry, 1948, Vol. 40, No. 5, pp. 932-937, E. J. Vandenberg, G. E. Hulse, Hercules Powder Company, Wilmington, Del.+ [Non-patent document 6] 1 / 2 Industrial and Engineering Chemistry, 1954, Vol. 46, No. 5, pp. 1065-1073, JR Miller, H.E. Diem, B.F. Goodrich Chemical Co., Akron, Ohio+ [Non-Patent Document 7] The Vanderbilt Rubber Handbook, 13th edition, 1990, pp. 417 and 418 [Non-patent document 8] The Vanderbilt Rubber Handbook (1978), pp. 344-346 Summary of the Invention

[0011] Contrary to the effects of adding carbon black in solid form and contrary to the knowledge of those skilled in the art of the difficulties in dispersing and processing silica in an elastomer matrix, the incorporation of silica into diene elastomer and carbon black masterbatches having very good dispersion of the carbon black in the diene elastomer matrix, in particular masterbatches prepared according to the process described above, makes it possible to obtain new masterbatches having improved hysteresis while retaining very good dispersion of all fillers in the elastomer matrix after the introduction of the silica in solid form.

[0012]

[0010] One subject of the present invention is therefore a rubber composition based on at least one diene elastomer, a filler comprising at least carbon black and an inorganic filler with an inorganic filler content of not more than 50 parts by weight per 100 parts of elastomer (phr), and further a crosslinking system, characterized in that the dispersion of the filler in the elastomer matrix has a Z value of 60 or more, more preferably 80 or more.

[0013] Preferably, the composition is obtained from a first masterbatch comprising at least a diene elastomer and carbon black, the first masterbatch having a dispersion of carbon black in an elastomer matrix having a Z value of 60 or greater, more preferably 90, and even more preferably the first masterbatch is obtained by liquid phase compounding starting from an aqueous dispersion of diene elastomer latex and carbon black.

[0014] According to one advantageous embodiment, such a first masterbatch is obtained according to the following process steps: feeding a continuous flow of diene elastomer latex into 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 containing a filler under pressure into the mixing zone of the coagulation reactor to form a coagulated mixture, and drying the coagulate obtained above in order to recover the first masterbatch.

[0015]

[0013] According to one preferred embodiment, the diene elastomer of the composition is selected from the group consisting of polybutadiene, natural rubber, synthetic polyisoprene, butadiene copolymers, isoprene copolymers and blends of these elastomers, more preferably the diene elastomer is natural rubber.

[0016] According to another preferred embodiment, the inorganic filler of the composition is silica or chemically treated silica.

[0017] Another subject of the present invention is a method for preparing a composition comprising at least one diene elastomer and a filler comprising at least one carbon black and an inorganic filler with an inorganic filler content of not more than 50 parts by weight per 100 parts of elastomer, and also a crosslinking system, comprising the following steps: preparing a first masterbatch of diene elastomer and carbon black, comprising: feeding a continuous stream of diene elastomer latex to a mixing zone of a coagulation reactor defining an elongated coagulation zone extending between the mixing zone and an outlet; and feeding a continuous stream of a fluid containing a filler, including carbon black, under pressure to the mixing zone of the coagulation reactor to form a coagulated mixture; drying the coagulum obtained above to recover a first masterbatch; Incorporating the inorganic filler and the other constituents of the composition, except the crosslinking system, into the first masterbatch obtained above by thermomechanical mixing everything in a mixer until a maximum temperature of 130°C to 200°C is reached, to produce a non-productive compound; cooling the combined mixture to a temperature below 100°C before incorporating the crosslinking system; Subsequently, the process comprises incorporating a crosslinking system and an additional diene elastomer, which may be the same as or different from the at least one diene elastomer, into the non-productive compound and compounding everything to a maximum temperature of less than 120° C. In other words, the additional elastomer is added to the production route according to one embodiment.

[0018] Advantageously, the additional diene elastomer is incorporated into the compound in an amount to reduce the carbon black in the masterbatch to a predetermined level in the rubber composition.

[0019] The present invention also provides a method for preparing a composition comprising at least one diene elastomer, a filler comprising at least one carbon black and an inorganic filler having an inorganic filler content of not more than 50 parts by weight per 100 parts of elastomer, and a crosslinking system, comprising the steps of: preparing a first masterbatch of diene elastomer and carbon black, the step comprising: feeding a continuous stream of diene elastomer latex to a mixing zone of a coagulation reactor defining an elongated coagulation zone extending between the mixing zone and an outlet; and feeding a continuous stream of a fluid containing a filler, including carbon black, under pressure to the mixing zone of the coagulation reactor to form a coagulated mixture; drying the coagulum obtained above to recover a first masterbatch; Incorporating the inorganic filler and the other constituents of the composition, except the crosslinking system, into the first masterbatch obtained above by thermomechanically kneading everything in a mixer until a maximum temperature of 130°C to 200°C is reached, to produce a first non-productive compound; cooling the first non-productive compound to a temperature below 100°C; incorporating at least one additional component of the composition into the first non-productive compound to produce at least a second non-productive compound; cooling the combined mixture to a temperature below 100°C, followed by incorporating all or part of the crosslinking system into at least a second non-productive compound and compounding everything to a maximum temperature below 120°C.

[0020] In one embodiment, the additional component is an additional diene elastomer, which can be the same as or different from the at least one diene elastomer. In another embodiment, the additional component is part of a crosslinking system. In another embodiment, the additional component is not part of a crosslinking system or an additional elastomer, but rather is an additive such as an antiozonant, wax, oil, etc.

[0021] The present invention also provides a method for preparing a composition comprising at least one diene elastomer, a filler comprising at least one carbon black and an inorganic filler having an inorganic filler content of not more than 50 parts by weight per 100 parts of elastomer, and a crosslinking system, comprising the steps of: preparing a first masterbatch of diene elastomer and carbon black, the step comprising: feeding a continuous stream of diene elastomer latex to a mixing zone of a coagulation reactor defining an elongated coagulation zone extending between the mixing zone and an outlet; and feeding a continuous stream of a fluid containing a filler, including carbon black, under pressure to the mixing zone of the coagulation reactor to form a coagulated mixture; drying the coagulum obtained above to recover a first masterbatch; Incorporating the inorganic filler and other constituents of the composition, part of the crosslinking system, into the first masterbatch obtained above by thermomechanically kneading everything in a mixer until a maximum temperature of 130°C to 200°C is reached, thereby producing a non-productive compound; cooling the combined mixture to a temperature below 100°C, followed by incorporating the remainder of the crosslinking system into the non-productive compound and compounding the whole to a maximum temperature below 120°C.

[0022] According to one preferred embodiment of the method, the diene elastomer is natural rubber and the inorganic filler is silica or silica-coated carbon black.

[0023]

[0021] According to one embodiment of the method, the content of carbon black in the masterbatch is 1-100 phr, and the content of inorganic filler is 25-50 phr.

[0024] In one embodiment, the composition may be incorporated into a carcass, a portion of a belt structure, and / or a tread. For example, as part of a carcass, the component may be an apex, a wire coat, a ply coat, a squeegee compound, a gum strip, a chafer, a reinforcing sidewall insert, or an exposed sidewall. As part of a tread section, the component may be a tread base or a tread cap. The composition may also be an innerliner.

[0025] A final subject of the present invention is a finished or nearly finished article, a tire tread, a tire component or a semi-finished product comprising the composition described above or the masterbatch described above. DETAILED DESCRIPTION OF THE INVENTION

[0026] The present invention relates to a composition based on a masterbatch of diene elastomer and reinforcing filler, comprising at least one diene elastomer and a filler comprising at least carbon black and an inorganic filler with an inorganic filler content of not more than 50 parts by weight per 100 parts of elastomer, the composition having a dispersion of the filler in the elastomer matrix with a Z value of at least 60, more preferably at least 80, and even more preferably at least 90. As is known, the dispersion of the filler in the elastomer matrix can be expressed by the Z value, measured after crosslinking according to the method described in Kautschuk Gummi Kunststoffe by S. Otto et al., 58th edition, NR 7-8 / 2005, in accordance with ISO standard 11345.

[0027]

[0025] The Z value is calculated based on the percentage of surface area where the filler is not dispersed ("% Undispersed Surface Area") as measured by a "disperGRADER+" instrument equipped with "disperDATA" operating software and operating process by Dynisco, according to the formula: Z = 100 - (% Undispersed Surface Area) / 0.35.

[0028] The percentage of undispersed surface area is itself measured by a camera observing the surface area of ​​the sample under light incident at 30°. The light spots relate to fillers and lumps, while the dark spots relate to the rubber matrix; digital processing converts the image into a black and white image, allowing the determination of the percentage of undispersed surface area as described in the above-mentioned document by S. Otto.

[0029]

[0027] According to one embodiment of the present invention, the composition is obtained by adding an inorganic filler to a first masterbatch comprising at least a diene elastomer and carbon black, and having a dispersion of carbon black in an elastomer matrix having a Z value of 60 or more, more preferably 90 or more.

[0030]

[0028] In this description, unless expressly indicated otherwise, all percentages (%) given are by weight. Also, any range of values ​​given by the expression "between a and b" denotes a range of values ​​greater than a and less than b (i.e., excluding the boundaries a and b), whereas any range of values ​​given by the expression "a to b" means a range of values ​​from a to b (i.e., including the precise boundaries a and b).

[0031] I. Diene elastomers As a matter of convention, the interchangeable terms "elastomer" and "rubber" are used interchangeably herein.

[0032]

[0030] In practice, various conjugated diene-based elastomers may be used in the rubber composition, such as, for example, polymers and copolymers of at least one of isoprene and 1,3-butadiene, and polymers and copolymers of styrene copolymerized with at least one of isoprene and 1,3-butadiene, and mixtures thereof.

[0033] Representative of such conjugated diene-based elastomers are, for example, at least one of cis-1,4-polyisoprene (natural and synthetic), cis-1,4-polybutadiene, styrene / butadiene copolymers (prepared aqueous emulsion polymers and prepared organic solvent solution polymers), intermediate vinyl polybutadienes having a vinyl-1,2-content ranging from about 10 to about 90 percent, isoprene / butadiene copolymers, and styrene / isoprene / butadiene terpolymers.

[0034] Cis-1,4-polyisoprene and cis-1,4-polyisoprene natural rubber are well known to those having skill in the rubber art.

[0035] Representative synthetic polymers are the homopolymerization products of butadiene and its homologs and derivatives, such as methylbutadiene, dimethylbutadiene, and pentadiene, as well as copolymers such as those formed from butadiene or its homologs or derivatives with other unsaturated monomers. The latter include acetylene, e.g., vinyl acetylene; olefins, e.g., isobutylene, which copolymerizes with isoprene to form butyl rubber; vinyl compounds, e.g., acrylic acid, acrylonitrile, which polymerizes with butadiene to form NBR, methacrylic acid, and styrene, which polymerizes with butadiene to form SBR; and vinyl esters and various unsaturated aldehydes, ketones, and ethers, e.g., acrolein, methyl isopropenyl ketone, and vinyl ethyl ether.

[0036] Specific examples of synthetic rubbers include neoprene (polychloroprene), polybutadiene (including cis-1,4-polybutadiene), polyisoprene (including cis-1,4-polyisoprene), butyl rubber, halobutyl rubber, such as chlorobutyl or bromobutyl rubber, styrene / isoprene / butadiene rubber, copolymers of 1,3-butadiene or isoprene with monomers such as styrene, acrylonitrile, and methyl methacrylate, and ethylene / propylene terpolymers, also known as ethylene / propylene / diene monomer (EPDM), particularly ethylene / propylene / dicyclopentadiene terpolymers. Further examples of rubbers that can be used include alkoxy-silyl end-functionalized solution-polymerized polymers (SBR, PBR, IBR, and SIBR), silicon-coupled polymers, and tin-coupled star-branched polymers.

[0037]

[0035] For practical purposes, the preferred rubbers or elastomers are polyisoprene (natural or synthetic), polybutadiene and SBR.

[0038] In one embodiment, one elastomer is SBR, more preferably solution-polymerized SBR (SSBR), which can be conveniently prepared, for example, by organolithium catalysis in the presence of an organic hydrocarbon solvent.

[0039] In one embodiment, at least one elastomer is functionalized to react with the silica filler. Representative functionalized elastomers include, for example: (A) Amine functional groups reactive with hydroxyl groups on the precipitated silica; (B) siloxy functional groups, including end-chain siloxy groups reactive with hydroxyl groups on the precipitated silica; (C) a combination of amine and siloxy functional groups reactive with hydroxyl groups on said precipitated silica; (D) a combination of thiol and siloxy (e.g., ethoxysilane) functional groups reactive with the hydroxyl groups on the precipitated silica; (E) a combination of imine and siloxy functional groups reactive with the hydroxyl groups on the precipitated silica; (F) Hydroxyl functional groups reactive with precipitated silica It is a styrene / butadiene elastomer containing one or more functional groups including

[0040]

[0038] With regard to functionalized elastomers, representative of amine-functionalized SBR elastomers are, for example, the in-chain functionalized SBR elastomers described in U.S. Patent No. 6,936,669, the disclosure of which is incorporated herein in its entirety.

[0041]

[0039] Representative of the combination of amino-siloxy-functionalized SBR elastomers in which one or more amino-siloxy groups are linked to the elastomer are, for example, JSR's HPR355 (trademark) and the amino-siloxy-functionalized SBR elastomers described in U.S. Pat. No. 7,981,966, the disclosure of which is incorporated herein in its entirety.

[0042] Representative styrene / butadiene elastomers end-functionalized with silane-sulfide groups are described, for example, in US Pat. Nos. 8,217,103 and 8,569,409, the disclosures of which are incorporated herein in their entireties.

[0043]

[0041] Tin-coupled elastomers prepared by organic solvent polymerization may also be used, such as, for example, tin-coupled organic solution polymerization prepared styrene / butadiene copolymers, isoprene / butadiene copolymers, styrene / isoprene copolymers, polybutadiene, and styrene / isoprene / butadiene terpolymers (including the functionalized styrene / butadiene elastomers described above).

[0044] Tin-coupled copolymers of styrene / butadiene can be prepared, for example, by introducing a tin-coupling agent during the copolymerization reaction of styrene / 1,3-butadiene monomers in an organic solvent solution, usually at or near the end of the polymerization reaction. Such coupling of styrene / butadiene copolymers is well known to those skilled in the art.

[0045]

[0043] In practice, it is usually preferred that at least 50 percent, and more typically in the range of about 60 to about 85 percent, of the Sn (tin) bonds in the tin-coupled elastomer be attached to butadiene units of the styrene / butadiene copolymer to produce Sn-dienyl bonds, such as butadienyl bonds.

[0046] The creation of the tin-dienyl bond can be accomplished in several ways, such as by varying the styrene and / or butadiene reactivity ratio for the copolymerization by, for example, the sequential addition of butadiene to the copolymerization system or by the use of a modifier. Whether used in a batch or continuous copolymerization system, such techniques are believed to be well known to those skilled in such art.

[0047] Various tin compounds, especially organotin compounds, can be used for coupling elastomers. Representative of such compounds are, for example, alkyltin trichlorides, dialkyltin dichlorides, which result in tin-coupled styrene / butadiene copolymer elastomer variants, but trialkyltin monochlorides may also be used, which will simply produce tin-terminated copolymers.

[0048] Examples of tin-modified or coupled styrene / butadiene copolymer elastomers may be found, for example, in US Pat. No. 5,064,901, the disclosure of which is incorporated herein in its entirety without intending to be limiting.

[0049] Emulsion polymerization prepared styrene / butadiene / acrylonitrile copolymer rubbers containing from about 2 to about 40 weight percent bound acrylonitrile in the copolymer are also contemplated as diene-based rubbers for use in this invention.

[0050] By emulsion polymerization prepared E-SBR, it is meant that styrene and 1,3-butadiene are copolymerized as an aqueous emulsion. Such techniques are well known to those skilled in the art. The bound styrene content can vary, for example, from about 5 to about 50 percent. In one embodiment, the E-SBR may also contain acrylonitrile to form a terpolymer rubber, as an E-SBAR, in an amount of, for example, from about 2 to about 30 weight percent bound acrylonitrile in the terpolymer.

[0051] It is further contemplated that in certain embodiments the rubber elastomer may be a butyl-type rubber, particularly copolymers of isobutylene with minor amounts of diene hydrocarbons such as isoprene, and halogenated butyl rubbers.

[0052] These diene elastomers can be divided into two categories: "essentially unsaturated" or "essentially saturated." In general, the expression "essentially unsaturated" is understood to mean diene elastomers which originate at least in part from conjugated diene monomers having a content of units of diene origin (conjugated dienes) of more than 15% (mol %); therefore, diene elastomers such as butyl rubber or diene / α-olefin copolymers of the EPDM type do not fall within the preceding definition and can in particular be described as "essentially saturated" diene elastomers (low or very low content of units of diene origin, always less than 15%). Within the "essentially unsaturated" diene elastomer category, the expression "highly unsaturated" diene elastomers is understood to mean in particular diene elastomers having a content of units of diene origin (conjugated dienes) of more than 50%.

[0053] In summary, the synthetic diene elastomer or elastomers according to the present invention are preferably selected from the group of highly unsaturated diene elastomers formed with polybutadiene (abbreviated as "BR"), synthetic polyisoprene (IR), butadiene copolymers, isoprene copolymers, and blends of these elastomers. Such copolymers are more preferably selected from the group consisting of butadiene / styrene copolymers (SBR), isoprene / butadiene copolymers (BM), isoprene / styrene copolymers (SIR), and isoprene / butadiene / styrene copolymers (SBIR).

[0054] As defined above, the liquid-phase compounding process is preferably used to obtain masterbatches based on diene elastomers and carbon black, which have a very good dispersion of the carbon black in the elastomer. Thus, in particular for the production of the first masterbatch of diene elastomers and carbon black, a diene elastomer latex is used in particular, which is a specific form of elastomer in the form of elastomer particles dispersed in water.

[0055] The present invention therefore preferably relates to a latex of a diene elastomer, the diene elastomer being as defined above.

[0056] More particularly, with regard to natural rubber (NR), which is particularly suitable for the present invention, this natural rubber exists in various forms as explained in detail by KF Gaseley, A.D.T.Gordon and T.D.P. Endle in Chapter 3, "Latex concentrates: properties and composition," of "Natural Rubber Science and Technology," A.D. Roberts, Oxford University Press—1988.

[0057]

[0055] In particular, several forms of natural rubber latex are commercially available: natural rubber latex designated as "field latex", natural rubber latex designated as "concentrated natural rubber latex", epoxidized latex (ENR), deproteinized latex or vulcanized latex. Natural rubber field latex is latex to which ammonia has been added to prevent premature coagulation, while concentrated natural rubber latex corresponds to field latex that has undergone a treatment corresponding to washing and subsequent further concentration. Various categories of concentrated natural rubber latex are listed in particular according to ASTM standard D 1076-06. Among these concentrated natural rubber latexes, a distinction is made in particular between the quality designated as "HA" (high ammonia) and the quality designated as "LA"; in the present invention, concentrated natural rubber latex of the HA quality is advantageously utilized.

[0058] The NR latex may be previously physically or chemically modified (centrifugation, enzyme treatment, chemical denaturants, etc.).

[0059] The latex may be used directly or may be first diluted with water to facilitate its processing.

[0060]

[0058] Thus, as a synthetic elastomer latex, the latex may consist in particular of a synthetic diene elastomer already available in the form of an emulsion (for example, a butadiene / styrene copolymer SBR prepared in emulsion), or of a synthetic diene elastomer initially in solution (for example, an SBR prepared in solution) which is emulsified in a mixture of organic solvent and water, generally with the aid of a surfactant.

[0061] SBR latexes, especially emulsion-prepared SBRs ("ESBRs") or solution-prepared SBRs ("SSBRs"), and more particularly emulsion-prepared SBRs, are particularly suitable for the present invention.

[0062]

[0060] There are two main types of process for the copolymerization of styrene and butadiene in emulsion, one of which, the hot process (carried out at temperatures close to 50°C), is suitable for the preparation of highly branched SBR, while the other, the cold process (carried out at temperatures which may range from 15°C to 40°C), makes it possible to obtain a more linear SBR.

[0063] For a detailed description of the effectiveness of some emulsifiers that can be used in the hot process (as a factor of the emulsifier content), reference can be made, for example, to two articles by C.W. Carr, I.M. Kolthoff, E.J. Meehan, University of Minnesota, Minneapolis, Minn., in the Journal of Polymer Science of 1950, Vol. V, No. 2, pp. 201-206, and of 1951, Vol. VI, No. 1, pp. 73-81.

[0064]

[0062] For comparative examples of the implementation of the cold process, reference may be made, for example, to the article 1 / 2 Industrial and Engineering Chemistry, 1948, Vol. 40, No. 5, pp. 932-937, EJ Vandenberg, GE Hulse, Hercules Powder Company, Wilmington, Del. + and the article 1 / 2 Industrial and Engineering Chemistry, 1954, Vol. 46, No. 5, pp. 1065-1073, J.R. Miller, H.E. Diem, B.F. Goodrich Chemical Co., Akron, Ohio +.

[0065] In the case of SBR elastomers (ESBR or SSBR), in particular SBR having an average styrene content, for example 20% to 35% by weight, or a high styrene content, for example 35% to 45%, a vinyl bond content in the butadiene moiety of 10% to 70%, a trans-1,4-bond content (mol%) of 15% to 75% and a Tg of -10°C to -55°C is used; such SBR can advantageously be used as a blend with BR having preferably more than 90% (mol%) of cis-1,4-bonds.

[0066] It is noted that it is possible to consider using one or more natural rubber latexes as a blend, one or more synthetic rubber latexes as a blend, or a blend of one or more natural rubber latexes with one or more synthetic rubber latexes.

[0067] II. Fillers

[0065] All carbon blacks customarily used in tires are suitable as carbon blacks, in particular blacks of the HAF, ISAF or SAF type ("tire grade" blacks). Among the latter, mention may be made more particularly of reinforcing carbon blacks of the 100, 200 or 300 series (ASTM grades), such as, for example, N110, N121, N134, N220, N231, N234, N242, N293, N299, S315, N326, N330, M332, N339, N343, N347, N351, N358 or N375 blacks, or blacks of the higher numerical series (for example, N400, N539, N550, N582, N630, N642, N650, N683, N754, N762, N765, N774, N787, N907, N908, N990 and N991), depending on the targeted application.

[0068] Mass balance or ISCC carbon blacks, such as carbon blacks derived at least in part from non-traditional feedstocks such as tall oil, methane, or waste tire oil, are also suitable. The ASTM-D6866 method is used to determine radiocarbon ( 14The ratio of the amount of biomass carbon (C) to that of a modern reference standard is determined. This ratio is reported as a percentage with the units "pMC" (percent modern carbon). If the material being analyzed is a mixture of modern radiocarbon and fossil carbon (the fossil carbon being derived from petroleum, coal, or natural gas sources), the resulting pMC value directly correlates to the amount of biomass material present in the sample. The result provided by ASTM D6866 is the amount of biocomponent "present" in the material, not the amount of biomaterial "used" in the manufacturing process. In one embodiment, the carbon black has a modern carbon content greater than one percent (1%) as defined by ASTM D6866. The carbon black is produced from a bio-based feedstock prior to its addition to the masterbatch and / or rubber composition. In one embodiment, the carbon black is at least partially derived from a bio-based feedstock, and in a preferred embodiment, is completely devoid of fossil carbon.

[0069] Also suitable as carbon blacks are carbon blacks that have been partially or completely coated with silica by post-treatment or modified in situ with silica, such as, but not limited to, fillers sold by Cabot Corporation under the names Ecoblack™ "CRX 2000" or "CRX4000."

[0070] Various combinations of carbon blacks (of different particle sizes and / or other properties, e.g., conventional petroleum-derived carbon blacks and bio-derived carbon blacks) can also be used in the disclosed rubber compositions. Representative examples of rubber-reinforcing carbon blacks are found, for example and without limitation, in The Vanderbilt Rubber Handbook, 13th Edition, 1990, pages 417 and 418, along with their ASTM designations. Such rubber-reinforcing carbon blacks can have, for example, iodine absorptions ranging from 9 to 240 g / kg and DBP values ​​from 34 to 150 cc / 100 g.

[0071]

[0069] The expression "inorganic filler" here should be understood to mean, as is known, any inorganic or mineral filler, whatever its color and its origin (natural or synthetic), which, in contrast to carbon black, is also called a "white filler," "transparent filler," or even "non-black filler," which is capable of reinforcing rubber compositions for tire treads by itself, without any other means than intermediate coupling agents, and in other words of replacing conventional tire-grade carbon black in its reinforcing role for tire treads. Such fillers are generally characterized by the presence of functional groups, in particular hydroxyl (-OH) groups, on their surface, and their use as reinforcing fillers requires the use of coupling agents or systems intended to provide a stable chemical bond between the isoprene elastomer and the filler.

[0072]

[0070] Thus, such inorganic fillers may be used in conjunction with a coupling agent to enable reinforcement of the rubber composition in which they are included, or may be used in conjunction with a coating agent in addition to the coupling agent (which does not provide a bond between the filler and the elastomeric matrix), or may not be used at all (in which case the inorganic filler does not play a reinforcing role).

[0073] The physical state in which the inorganic filler is present is not important, whether in the form of powder, microbeads, granules, spheres or any other suitable compressed form. Of course, the expression "inorganic filler" refers in particular to silica, such as conventional, precipitated, treated and / or highly dispersible silica, and very high surface area HDS (BET nitrogen surface area >250 m), as described below. 2 / g) of silicon and / or aluminum fillers.

[0074] Mineral fillers of the silicon type, in particular silica (SiO2), or of the aluminum type, in particular alumina (Al2O3), are particularly suitable as inorganic fillers. The silicas used may be any silica known to those skilled in the art, in particular any of the 450 ml silicas.2 / g or less, preferably 30 to 400m 2 The filler may be precipitated or pyrogenic silica having a BET surface area and a CTAB specific surface area in the range of 1 / g. Highly dispersible precipitated silica ("HDS") includes, for example, Evonik's Ultrasil 7000 and Ultrasil 7005 silicas, Rhodia's Zeosil 1165 MP, 1135 MP, 1115, and 1200 MP silicas, PPG's Hi-Sil EZ150G silica, Huber's Zeopol 8715, 8745, and 8755 silicas, or the high specific surface area silicas described in WO 03 / 16837. Other possible fillers include Solvay's Premium SW, Zeosil 115, 125, and 200 MP.

[0075]

[0073] When the composition of the present invention is intended for a tire tread having low rolling resistance, the inorganic filler used, especially silica, is preferably 45 to 400 ml 2 / g, more preferably 60 to 300m 2 / g BET surface area.

[0076]

[0074] Inorganic fillers having an average particle size (by weight) of preferably 20 to 300 nm, more preferably 20 to 150 nm, are particularly suitable for the present invention. This average particle size is conventionally measured after dispersion by ultrasonic deagglomeration of the filler to be analyzed in water or in an aqueous solution containing a surfactant. In the case of inorganic fillers such as silica, the measurement is carried out using an X-ray detection centrifugal sedimentometer of the "XDC" ("X-ray Disc Centrifuge") type sold by Brookhaven Instruments, according to the following procedure: A suspension of 3.2 g of the inorganic filler sample to be analyzed in 40 ml of water is produced by the action of a 1500 W ultrasonic probe (a 1.905 cm (3 / 4 inch) Vibracell ultrasonicator sold by Bioblock) at 60% power (60% of the highest position on the "power control" setting) for 8 minutes. After sonication, 15 ml of the suspension is introduced into a rotating disk at a speed varying from 3000 to 6000 rpm (the speed is adapted as a function of the filler's average particle size: the smaller the particle size, the faster the speed). After 120 minutes of sedimentation, the particle size and the weight distribution (dw) of the average particle size (weight) are calculated using the "XDC" sedimentation velocimeter software [dw = Σ(ni di5) / Σ(ni di4), where ni is the number of particle size classes or objects of diameter di].

[0077] Preferably, the total filler (carbon black and inorganic filler, e.g., silica) content is between 1 and 200 phr, more preferably between 30 and 150 phr, even more preferably between 30 and 100 phr, the optimum depending on the particular application targeted, as is known: for example, the level of reinforcement expected for a bicycle tire will naturally be lower than that required for a tire capable of sustained high speed travel, e.g., a motorcycle tire, or a tire for a special purpose vehicle such as a passenger car or heavy vehicle.

[0078]

[0076] According to one preferred embodiment of the present invention, the carbon black content in the masterbatch and / or rubber composition varies from 1 to 100 phr, preferably from 30 to 80 phr, the inorganic filler content, in particular silica, varies from 5 to 50 phr, more particularly the total filler content including carbon black varies from 35 to 70 phr, the inorganic filler content, in particular silica, varies from 5 to 35 phr, and even more particularly the total filler content including carbon black varies from 35 to 65 phr and the inorganic filler content, in particular silica, varies from 1 to 30 phr.

[0079] III. Masterbatch - Rubber Composition Advantageously, the masterbatches and compositions so produced can be used in tire applications.

[0080]

[0078] The rubber compositions for tires based on the masterbatch according to the invention and inorganic fillers may also contain coupling agents and / or coating agents and vulcanization systems in a known manner.

[0081] In one embodiment, the rubber composition may include a silane coupling agent. In one embodiment, the rubber composition may include a silane coupling agent corresponding to the reinforcing filler, which is silica.

[0082] The silane coupling agent can be any suitable silane coupling agent, such as a bis(ω-trialkoxyalkylsilyl) polysulfide, an ω-mercaptoalkyl-trialkoxysilane, or a combination thereof. In one example, the bis-(ω-trialkoxysilylalkyl) polysulfide has an average of about 2 to about 4 connecting sulfur atoms in its polysulfide bridge. In another example, the bis-(ω-trialkoxysilylalkyl) polysulfide has an average of about 2 to about 2.6 connecting sulfur atoms in its polysulfide bridge. In yet another example, the bis-(ω-trialkoxysilylalkyl) polysulfide has an average of about 3.3 to about 3.8 connecting sulfur atoms in its polysulfide bridge. The alkyl group of the silylalkyl portion of the bis-(ω-trialkoxysilylalkyl) polysulfide can be a saturated C2-C6 alkyl group, such as a propyl group. Additionally, at least one of the alkyl groups of the trialkoxy moiety of the bis-(ω-trialkoxysilylalkyl) polysulfide can be an ethyl group, and the remaining alkyl groups of the trialkoxy moiety can independently be saturated C-C alkyl groups. 18 In another example, at least two of the alkyl groups in the trialkoxy moiety of the bis-(ω-trialkoxysilylalkyl) polysulfide are ethyl groups, and the remaining alkyl groups in the trialkoxy moiety are independently saturated C-C alkyl groups. 18In one example, the bis-(ω-trialkoxysilylalkyl) polysulfide coupling agent is bis-3-(triethoxysilylpropyl)tetrasulfide ("TESPD"). In another example, the bis-(ω-trialkoxysilylalkyl) polysulfide coupling agent is bis-3-(triethoxysilylpropyl)tetrasulfide ("TESPT"). The ω-mercaptoalkyltrialkoxysilane may have its mercapto moiety blocked, which may be blocked by pre-reaction with hydroxyl groups (e.g., silanol groups) contained in the precipitated silica aggregates before being unblocked at elevated temperatures. In one example, the blocked ω-mercaptoalkyltrialkoxysilane is NXT or NXT-LoV, available from GE Silicones of Tarrytown, NY.

[0083] sulfur curative It will be preferred that the rubber composition used in the tire component further contain a conventional sulfur-containing organosilicon compound. Examples of suitable sulfur-containing organosilicon compounds are those of the formula: Z-Alk-S n -Alk-Z I [Wherein Z is [ka] (In the formula, R 6 is an alkyl group of 1 to 4 carbon atoms, cyclohexyl, or phenyl; R 7 is an alkoxy of 1 to 8 carbon atoms or a cycloalkoxy of 5 to 8 carbon atoms) wherein Alk is a divalent hydrocarbon of 1 to 18 carbon atoms and n is an integer from 2 to 8. It is of the type.

[0084] Specific examples of sulfur-containing organosilicon compounds which can be used in accordance with the present invention include 3,3'-bis(trimethoxysilylpropyl) disulfide, 3,3'-bis(triethoxysilylpropyl) disulfide, 3,3'-bis(triethoxysilylpropyl) tetrasulfide, 3,3'-bis(triethoxysilylpropyl) octasulfide, 3,3'-bis(trimethoxysilylpropyl) tetrasulfide, 2,2'-bis(triethoxysilylpropyl) tetrasulfide, 3,3'-bis(trimethoxysilylpropyl)tetrasulfide, 3,3'-bis(triethoxysilylpropyl)trisulfide, 3,3'-bis(tributoxysilylpropyl)disulfide, 3,3'-bis(trimethoxysilylpropyl)hexasulfide, 3,3'-bis(trimethoxysilylpropyl)octasulfide, 3,3'-bis(trioctoxysilylpropyl)tetrasulfide, 3,3'-bis(tri 2,2'-bis(tri-2"-ethylhexoxysilylpropyl) disulfide, 3,3'-bis(triisooctoxysilylpropyl) tetrasulfide, 3,3'-bis(tri-t-butoxysilylpropyl) disulfide, 2,2'-bis(methoxydiethoxysilylethyl) tetrasulfide, 2,2'-bis(trippropoxysilylethyl) pentasulfide, 3,3'-bis(tricyclonexoxysilyl silylpropyl) tetrasulfide, 3,3'-bis(tricyclopentoxysilylpropyl) trisulfide, 2,2'-bis(tri-2"-methylcyclohexoxysilylethyl) tetrasulfide, bis(trimethoxysilylmethyl) tetrasulfide, 3-methoxyethoxypropoxysilyl 3'-diethoxybutoxy-silylpropyl tetrasulfide, 2,2'-bis(dimethylmethoxysilylethyl) disulfide, 2,2'-bis(dimethylsec.butoxysilylethyl) trisulfide, 3,3'-bis(methylbutylethoxysilylpropyl) tetrasulfide, 3,3'-bis(di-t-butylmethoxysilylpropyl) tetrasulfide, 2,2'-bis(phenylmethylmethoxysilylethyl) trisulfide, 3,3'-bis(diphenylisopropoxysilylpropyl) tetrasulfide, 3,3'-bis(diphenylcyclohexoxysilylpropyl) disulfide, 3,3'-bis(dimethylethylmercaptomethyl) 2,2'-bis(methyldimethoxysilylethyl) trisulfide, 2,2'-bis(methylethoxypropoxysilylethyl) tetrasulfide, 3,3'-bis(diethylmethoxysilylpropyl) tetrasulfide, 3,3'-bis(ethyldi-sec-butoxysilylpropyl) disulfide, 3,3'-bis(propyldiethoxysilylpropyl) disulfide, 3,3'-bis(butyldimethoxysilylpropyl) trisulfide tetrasulfide, 3,3'-bis(phenyldimethoxysilylpropyl)tetrasulfide, 3-phenylethoxybutoxysilyl 3'-trimethoxysilylpropyl tetrasulfide, 4,4'-bis(trimethoxysilylbutyl)tetrasulfide, 6,6'-bis(triethoxysilylhexyl)tetrasulfide, 12,12'-bis(triisopropoxysilyldodecyl)disulfide, 18,18'-bis(trimethoxysilyloctadecyl)tetrasulfide, 18,18 Examples of such tetrasulfides include 4,4'-bis(tripropoxysilyloctadecenyl)tetrasulfide, 4,4'-bis(trimethoxysilylbuten-2-yl)tetrasulfide, 4,4'-bis(trimethoxysilylcyclohexylene)tetrasulfide, 5,5'-bis(dimethoxymethylsilylpentyl)trisulfide, 3,3'-bis(trimethoxysilyl-2-methylpropyl)tetrasulfide, and 3,3'-bis(dimethoxyphenylsilyl-2-methylpropyl)disulfide.

[0085] The preferred sulfur-containing organosilicon compounds are 3,3'-bis(trimethoxy or triethoxysilylpropyl) sulfides. The most preferred compounds are 3,3'-bis(triethoxysilylpropyl) disulfide and 3,3'-bis(triethoxysilylpropyl) tetrasulfide. Thus, with respect to Formula I, preferably, Z is [ka] (In the formula, R 7 is an alkoxy of 2 to 4 carbon atoms, with 2 carbon atoms being particularly preferred; alk is a divalent hydrocarbon of 2 to 4 carbon atoms, with 3 carbon atoms being particularly preferred; n is an integer of 2 to 5, with 2 and 4 being particularly preferred. is.

[0086] In another embodiment, suitable sulfur-containing organosilicon compounds include those disclosed in U.S. Patent No. 6,608,125. In one embodiment, the sulfur-containing organosilicon compound is 3-(octanoylthio)-1-propyltriethoxysilane, CH3(CH2)6C(=O)-S-CH2CH2CH2Si(OCH2CH3)3, commercially available as NXT™ from Momentive Performance Materials.

[0087]

[0085] In another embodiment, suitable sulfur-containing organosilicon compounds include those disclosed in U.S. Patent Application Publication No. 2006 / 0041063, the disclosure of which is incorporated herein by reference in its entirety. In one embodiment, the sulfur-containing organosilicon compound includes the reaction product of a diol-based hydrocarbon (e.g., 2-methyl-1,3-propanediol) with S-[3-(triethoxysilyl)propyl]thiooctanoate. In one embodiment, the sulfur-containing organosilicon compound is Momentive Performance Materials' NXT-Z™.

[0088] In another embodiment, suitable sulfur-containing organosilicon compounds include those disclosed in U.S. Patent Application Publication No. 2003 / 0130535, which is incorporated herein by reference in its entirety. In one embodiment, the sulfur-containing organosilicon compound is Degussa's Si-363.

[0089] The amount of the sulfur-containing organosilicon compound of Formula I in a rubber composition will vary depending on the level of other additives used. The amount of the compound of Formula I ranges from 0.5 to 20 phr. Preferably, the amount ranges from 1 to 10 phr.

[0090] According to some embodiments of the rubber composition of the present invention, the coupling agent content is preferably 160 ml 2 0.1% to 12% by weight of inorganic filler per CTAB surface area of ​​ / g, more preferably 160m 2 / g CTAB surface area is 4% to 10% by weight of inorganic filler; and / or the content of coating agent is preferably 160m 2 0.1% to 20% by weight of inorganic filler per CTAB surface area per g, more preferably 160 m 2 The coupling agent content is 5% to 20% by weight of the inorganic filler for a specific surface area of ​​CTAB / g. The content of the coupling agent can be adjusted based on the specific surface area of ​​the filler.

[0091] As will be appreciated by those skilled in the art, fillers of other nature, particularly organic, may be used as fillers equivalent to the inorganic fillers described herein, provided that the filler is coated with an inorganic layer such as silica or contains functional sites, particularly hydroxyls, on its surface that require the use of a coupling agent to form a link between the filler and the elastomer.

[0092] IV. Mixed

[0090] These rubber compositions according to the invention may also contain all or some of the standard additives customarily used in elastomeric compositions for the manufacture of tires, and in particular treads, such as plasticizers or extending oils which may be aromatic or non-aromatic, pigments, protectants such as antiozone waxes, chemical antiozonants, antioxidants, antifatigue agents, reinforcing resins, such as methylene acceptors (e.g. phenol-novolak resins) or methylene donors (e.g. HMT or H3M), as described in WO 02 / 10269, sulfur or sulfur donors, and / or crosslinking systems based on peroxides and / or bismaleimides, and vulcanization accelerators.

[0093]

[0091] In a possible embodiment, these compositions may contain, as preferred non-aromatic or very weakly aromatic plasticizers, at least one compound selected from the group consisting of naphthenic oils, paraffinic oils, MES oils, TDAE oils, glycerol esters (especially trioleates), hydrocarbon-based plasticizing resins exhibiting a high Tg, preferably above 30°C, and mixtures of such compounds.

[0094] It should be noted that it is also possible to foresee producing masterbatches according to the present invention by incorporating additives such as oils, antioxidants, coupling agents, coating agents, etc., as described above, especially before the drying stage of the production of the masterbatch in the liquid phase.

[0095] V. Production of Rubber Compositions and Masterbatches The rubber compositions of the present invention are prepared in a suitable mixer using two successive preparation stages according to general procedures well known to those skilled in the art: a first stage (sometimes referred to as the "non-productive" stage) of thermomechanical operation or kneading at elevated temperatures, to a maximum temperature of 130°C to 200°C, preferably 145°C to 185°C, in at least one pass, followed by a second stage (sometimes referred to as the "productive" stage) of mechanical operation at lower temperatures, typically below 120°C, e.g., 60°C to 100°C, during which a crosslinking or vulcanization system is incorporated during the finishing stage. It is contemplated that embodiments may include one or more non-productive stages or passes.

[0096] According to one embodiment of the present invention, all the basic constituents of the composition of the invention, with the exception of the vulcanization / crosslinking system, in particular the masterbatch comprising the carbon black and the inorganic filler, and, where appropriate, the coupling agent, are intimately incorporated into the diene elastomer by kneading during the so-called non-productive first stage, i.e., at least these various basic constituents are introduced into a mixer and kneaded thermomechanically in one or more steps until a maximum temperature of between 130° C. and 200° C., preferably between 145° C. and 185° C., is reached.

[0097] According to another embodiment of the invention, all the basic constituents of the composition of the invention, including at least one component of the crosslinking / vulcanization system, in particular the masterbatch comprising carbon black and inorganic filler, and, where appropriate, coupling agent, are intimately incorporated into the diene elastomer by kneading during the so-called non-productive first stage, i.e. at least these various basic constituents are introduced into a mixer and kneaded thermomechanically in one or more steps until a maximum temperature of 130° C. to 200° C., preferably 145° C. to 185° C., is reached.

[0098] According to another embodiment of the present invention, at least one of the basic components of the composition of the present invention, optionally including at least one component of the crosslinking / vulcanization system, in particular a masterbatch comprising carbon black and inorganic filler, and, if appropriate, a coupling agent, is intimately incorporated into the diene elastomer by kneading during a so-called non-productive first stage. That is, at least one basic component is introduced into a mixer and kneaded thermomechanically in one or more steps until a maximum temperature of 130°C to 200°C, preferably 145°C to 185°C, is reached, producing a first non-productive compound or composition. At least a second basic component of the rubber composition of the present invention is incorporated into the first non-productive compound during another non-productive stage (or second non-productive stage) by any method or kneading known to those skilled in the art. At least the second base constituent is introduced into the mixer and is thermomechanically mixed in one or more steps at a maximum temperature of 130°C to 200°C until a second non-productive compound is produced.

[0099] According to one preferred embodiment of the invention, the inorganic filler is incorporated into a diene elastomer and carbon black which have been previously prepared in the form of a first masterbatch.

[0100] Preferably, this first masterbatch is produced in the "liquid" phase. To do so, the process involves a diene elastomer in the form of a latex in the form of elastomer particles dispersed in water, and an aqueous dispersion of carbon black, a filler dispersed in water, commonly referred to as a "slurry." Even more preferably, the process steps described in U.S. Pat. No. 6,048,923 are carried out, which process in particular comprises introducing into the blending zone of a coagulation reactor a continuous stream of a first fluid consisting of an elastomer latex, and introducing into the blending zone under pressure a second continuous stream of a second fluid consisting of an aqueous dispersion of carbon black to form a mixture with the elastomer latex, wherein the blending of these two fluids is sufficiently energetic to allow almost complete coagulation of the elastomer latex together with the carbon black prior to the exit of the coagulation reactor, and then drying the resulting coagulum.

[0101]

[0099] It should be noted in particular that the incorporation of the inorganic filler can not only be carried out simultaneously with the introduction of the other constituents (especially the diene elastomer alone or in the form of a first masterbatch) into the mixer, but that this incorporation can advantageously be delayed by a period of several tens of seconds to several minutes.

[0102]

[0100] By way of example, the (non-productive) first stage is carried out in a single thermomechanical step, during which at least one base component (if appropriate in the form of a masterbatch as defined above), optional supplemental coating agents or processing aids, and various other additives, including, optionally, components of the vulcanization system, are introduced into a suitable mixer, such as a standard internal mixer. The total duration of mixing in this non-productive stage is preferably 1 to 15 minutes. After cooling of the mixture thus obtained during the final non-productive stage, the remaining activated components of the vulcanization system are then incorporated at low temperature, typically in an internal mixer; everything is then mixed for several minutes, for example, 2 to 15 minutes (productive stage). In one embodiment, an additional diene elastomer can also be incorporated into the final non-productive compound during the productive stage, which includes a step of mixing everything up to a maximum temperature of less than 120°C. In one embodiment, this additional diene elastomer can be the same as or different from the at least one diene elastomer. In a preferred embodiment, the additional diene elastomer is used to dilute the amount of filler contained in the original masterbatch. Thus, the additional diene elastomer is incorporated into the compound in an amount that reduces the carbon black in the masterbatch to a predetermined level in the rubber composition. As will be readily understood by those skilled in the art, the rubber composition may be compounded by methods generally known in the rubber compounding art, for example, by mixing various sulfur-vulcanizable component rubbers with various commonly used additive materials, such as sulfur donors, curing aids, e.g., activators and inhibitors and processing additives, fillers, pigments, fatty acids, zinc oxide, waxes, antioxidants and antiozonants, and peptizers. The crosslinking system is preferably a vulcanization system, i.e., a system based on sulfur (or sulfur donors) and a primary vulcanization accelerator. Representative examples of sulfur donors include elemental sulfur (free sulfur), amine disulfides, polymeric polysulfides, and sulfur olefin adducts. Preferably, the sulfur vulcanizing agent is elemental sulfur. The sulfur vulcanizing agent may be used in an amount ranging from 0.01 to 12 phr, especially from 1 to 10 phr.To this basic vulcanization system are added various known secondary vulcanization accelerators or vulcanization activators, such as zinc oxide, stearic acid or equivalent compounds, or guanidine derivatives (especially diphenylguanidine), which are incorporated during the non-productive first stage and / or the productive stage described below. As known to those skilled in the art, depending on the intended use of the sulfur-vulcanizable and sulfur-vulcanized materials (rubbers), the additives mentioned above are selected and generally used in conventional amounts.

[0103]

[0101] Typical amounts of antioxidants include about 1 to about 5 phr. Typical antioxidants can be, for example, diphenyl-p-phenylenediamine and others, such as those disclosed in The Vanderbilt Rubber Handbook (1978), pages 344-346. Typical amounts of fatty acids, if used, which can include stearic acid, include about 0.1 to about 5 phr. Typical amounts of waxes include about 1 to about 5 phr. Microcrystalline waxes are often used. Typical amounts of peptizers include about 0.1 to about 1 phr. Typical peptizers can be, for example, pentachlorothiophenol and dibenzamidodiphenyl disulfide.

[0104] Accelerators are used to control the time and / or temperature required for vulcanization and to improve the properties of the vulcanizate. In one embodiment, a single accelerator system may be used, i.e., a primary accelerator. The primary accelerator may be used in a total amount ranging from about 0.1 to about 10 phr, more preferably from 0.5 to 5.0 phr. In another embodiment, a combination of primary and secondary accelerators may be used to activate and improve the properties of the vulcanizate, with the secondary accelerator being used in a smaller amount. These accelerator combinations may produce a synergistic effect on the final properties, which may be expected to be somewhat better than those produced by the use of either accelerator alone. Additionally, delayed-action accelerators may be used that are not affected by normal processing temperatures but produce satisfactory cures at normal vulcanization temperatures. Vulcanization retarders may also be used. Suitable types of accelerators that may be used in the present invention are amines, disulfides, guanidines, thioureas, thiazoles, thiurams, sulfenamides, dithiocarbamates, and xanthates. Preferably, the primary accelerator is a sulfenamide. If a second accelerator is used, the secondary accelerator is preferably a guanidine, dithiocarbamate, or thiuram compound.

[0105]

[0103] The final composition thus obtained is then calendered, for example in the form of sheets or slabs, or extruded in the form of rubber profiled elements which can be used, for example, as tire treads for passenger cars, heavy vehicles, etc.

[0106] Variations in the present invention are possible in light of the description thereof provided herein. While certain representative embodiments and details have been shown for the purpose of illustrating the invention, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the scope of the invention. It is therefore to be understood that changes can be made in the particular embodiments described that are within the full intended scope of the invention as defined by the appended claims.

Claims

1. 1. A method for preparing a rubber composition based on at least one diene elastomer, a filler comprising at least carbon black and an inorganic filler with an inorganic filler content of not more than 50 parts by weight per 100 parts of elastomer, and further a crosslinking system, comprising: Preparing a first masterbatch of diene elastomer and carbon black, feeding a continuous stream of diene elastomer latex into a mixing zone of a coagulation reactor defining an elongated coagulation zone extending between the mixing zone and an outlet; feeding a continuous stream of fluid containing a filler, including carbon black, under pressure into a mixing zone of a coagulation reactor to form a coagulation mixture; The coagulated product obtained above is dried to recover the first masterbatch. and Incorporating the inorganic filler and the other constituents of the composition, except the crosslinking system, into the first masterbatch obtained above by thermomechanically kneading everything in a mixer until a maximum temperature of 130°C to 200°C is reached, to produce a non-productive compound; Cooling the combined mixture to a temperature below 100°C before incorporating the crosslinking system; Subsequently, the crosslinking system and the additional diene elastomer are incorporated into the non-productive compound and all are mixed to a maximum temperature of less than 120°C, the additional diene elastomer being the same as or different from the at least one diene elastomer. A method comprising:

2. 10. The method of claim 1, wherein additional diene elastomer is incorporated into the non-productive compound in an amount to reduce the carbon black in the masterbatch to a predetermined level in the rubber composition.

3. 1. A method for preparing a rubber composition based on at least one diene elastomer, a filler comprising at least carbon black and an inorganic filler with an inorganic filler content of not more than 50 parts by weight per 100 parts of elastomer, and further a crosslinking system, comprising: Preparing a first masterbatch of diene elastomer and carbon black, feeding a continuous stream of diene elastomer latex into a mixing zone of a coagulation reactor defining an elongated coagulation zone extending between the mixing zone and an outlet; feeding a continuous stream of fluid containing a filler, including carbon black, under pressure into a mixing zone of a coagulation reactor to form a coagulation mixture; The coagulated product obtained above is dried to recover the first masterbatch. and Incorporating the inorganic filler and the other constituents of the composition, except for the crosslinking system, into the first masterbatch obtained above by thermomechanically kneading everything in a mixer until a maximum temperature of 130°C to 200°C is reached, to produce a first non-productive compound; cooling the first non-productive compound to a temperature below 100°C; incorporating at least one additional component of the composition into the first non-productive compound to produce at least a second non-productive compound; cooling the combined mixture to a temperature below 100°C; Subsequently, all or part of the crosslinking system is incorporated into at least a second non-productive compound and all is mixed to a maximum temperature of less than 120°C. A method comprising:

4. 4. The method of claim 3, wherein the at least one additional component is an additional diene elastomer, the additional diene elastomer being the same as or different from the at least one diene elastomer.

5. 5. The method of claim 4, wherein additional diene elastomer is incorporated into the first non-productive compound in an amount to reduce the carbon black in the masterbatch to a predetermined level in the rubber composition.

6. 4. The method of claim 3, wherein at least one additional component is part of the crosslinking system, the at least one additional component being selected from the group consisting of sulfur, sulfur donors, accelerators, and vulcanization activators.

7. 10. The method of claim 1, wherein the diene elastomer is selected from the group consisting of polybutadiene, natural rubber, synthetic polyisoprene, butadiene copolymers, isoprene copolymers, and blends of these elastomers.

8. 8. The method of claim 7, wherein the diene elastomer is natural rubber.

9. 4. The method of claim 3, wherein the diene elastomer is selected from the group consisting of polybutadiene, natural rubber, synthetic polyisoprene, butadiene copolymers, isoprene copolymers, and blends of these elastomers.

10. 10. The method of claim 9, wherein the diene elastomer is natural rubber.

11. The method of claim 1 , wherein the inorganic filler is silica or silica-coated carbon black.

12. The method of claim 1 , wherein the inorganic filler is silica or silica-coated carbon black.

13. 2. The method according to claim 1, wherein the content of carbon black in the masterbatch is 30 to 80 phr and the content of inorganic filler is 5 to 50 phr.

14. 4. The method according to claim 3, wherein the content of carbon black in the masterbatch is 30 to 80 phr and the content of the inorganic filler is 5 to 50 phr.

15. 2. The method according to claim 1, wherein the content of carbon black in the rubber composition is 30 to 80 phr and the content of inorganic filler is 5 to 50 phr.

16. The method according to claim 3, wherein the content of carbon black in the rubber composition is 30 to 80 phr and the content of inorganic filler is 5 to 50 phr.

17. 1. A method for preparing a rubber composition based on at least one diene elastomer, a filler comprising at least carbon black and an inorganic filler with an inorganic filler content of not more than 50 parts by weight per 100 parts of elastomer, and further a crosslinking system, comprising: Preparing a first masterbatch of diene elastomer and carbon black, feeding a continuous stream of diene elastomer latex into a mixing zone of a coagulation reactor defining an elongated coagulation zone extending between the mixing zone and an outlet; feeding a continuous stream of fluid containing a filler, including carbon black, under pressure into a mixing zone of a coagulation reactor to form a coagulation mixture; The coagulated product obtained above is dried to recover the first masterbatch. and Incorporating the inorganic filler and other constituents of the composition, part of the crosslinking system, into the first masterbatch obtained above by thermomechanically kneading everything in a mixer until a maximum temperature of 130°C to 200°C is reached, to produce a non-productive compound; cooling the combined mixture to a temperature below 100°C; Subsequently, the remainder of the crosslinking system is incorporated into the non-productive compound and everything is mixed to a maximum temperature of less than 120°C. A method comprising:

18. 18. The method of claim 17, wherein the diene elastomer is natural rubber.

19. 18. The method of claim 17, wherein the inorganic filler is silica or silica-coated carbon black.

20. The method according to claim 17, wherein the content of carbon black in the rubber composition is 30 to 80 phr and the content of inorganic filler is 5 to 50 phr.

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