Rubber composition

Abstract

A rubber composition which surprisingly provides an improved balance between hysteresis properties and processability, said rubber composition being based on at least one elastomer matrix, a reinforcing filler in a total amount of less than 50 phr, and a particulate rubber, the reinforcing filler includes at least one carbon black and at least one silica, and the total amount of carbon black in phr is less than the total amount of silica.

Description

Technical Field

[0001] The field of the present invention is that of rubber compositions, in particular rubber compositions for rubber products, more particularly rubber compositions for rubber products that come into contact with the ambient air, still more particularly rubber compositions for tires, footwear, rubber conveyor belts or tracks, in particular rubber compositions for tires, more particularly rubber compositions for tire sidewalls. Background Art

[0002] Generally speaking, the performance quality of rubber products such as tires requires a variety of excellent properties. However, it is well known that these properties have conflicting relationships, such as the relationship between hysteresis and processability.

[0003] Patent document WO2006 / 052035 discloses a rubber composition composed of novel vinyl-cis-polybutadiene for sidewalls, which exhibits low matrix expansion and excellent extrusion processability and can improve low fuel consumption.

[0004] A continuing goal for rubber product manufacturers is to improve the balance between hysteresis performance qualities and processability. Summary of the Invention

[0005] During the course of their research, the inventors discovered that a specific rubber composition intended in particular for use in rubber products, more particularly for tires, articles of footwear, conveyor belts or rubber tracks, and even more particularly for tire sidewalls, enables an improved and unexpected balance between hysteresis performance qualities and processability.

[0006] The expression "based on" or "composition based on" is understood to mean that the composition comprises a mixture of the various essential components used, in situ reaction products or both, some of which are capable of, are intended to react at least partially during the various stages of manufacture of the composition or during subsequent vulcanization, modification of the initially prepared composition, or are intended to react at least partially and are intended to react at least partially with each other. Thus, the composition used in the present invention may differ in the non-crosslinked state and in the crosslinked (vulcanized) state.

[0007] The term "phr" means parts by weight per hundred parts of elastomer and, with respect to the preparation of the composition before curing, that is to say in the case of the presence of crumb rubber, means parts by weight per hundred parts of "new" elastomer, thus excluding from the base number 100 the elastomer contained in the crumb rubber.

[0008] In this specification, unless otherwise expressly mentioned, all percentages (%) shown are percentages by weight (wt %).

[0009] In a given composition, the expression "elastomeric matrix" is understood to mean all the elastomers present in the rubber composition.

[0010] In this specification, unless expressly stated otherwise, each TgDSC (glass transition temperature) is measured in a known manner by DSC (differential scanning calorimetry) according to standard ASTM D3418-08.

[0011] Any numerical interval expressed by the expression "between a and b" means a numerical range greater than "a" and less than "b" (i.e., excluding the limits a and b), while any numerical interval expressed by the expression "a to b" means a numerical range extending from "a" to "b" (i.e., including the strict limits a and b).

[0012] When referring to a "primary" compound, within the meaning of the present invention, this means that among the compounds of the same type in the composition, the compound is the primary one, that is, it is the compound that accounts for the largest amount by weight of the compounds of the same type, preferably greater than 50% by weight, and more preferably greater than 75% by weight. Thus, for example, relative to the total weight of polymers in the composition, the primary polymer is the polymer that accounts for the largest weight. Similarly, a "primary" filler is the filler that accounts for the largest weight of the fillers in the composition. For example, in a system containing only one polymer, the polymer is the primary one within the meaning of the present invention, and in a system containing two polymers, the primary polymer accounts for more than half of the weight of the polymers. Conversely, a "minor" compound is a compound that does not account for the largest weight fraction of the compounds of the same type.

[0013] Within the meaning of the present invention, when referring to a "primary" unit (or monomer) within the same compound (or polymer), it is meant that among the units (or monomers) forming the compound (or polymer), the unit (or monomer) is the primary one, that is, it is the unit (or monomer) that accounts for the largest weight fraction of the units (or monomers) forming the compound (or polymer). Thus, for example, a resin composed primarily of units derived from C5 monomers is a resin in which C5 units account for the largest amount by weight of all the units comprising the resin. In other words, the "primary" monomer (or collection of "primary" monomers) is the monomer (or collection of monomers) that accounts for the largest weight fraction of the polymer. Conversely, a "minor" monomer is a monomer that does not account for the largest mole fraction in the polymer.

[0014] The compounds mentioned in this specification may be of fossil or biobased origin. In the case of biobased compounds, they may be partially or fully derived from biomass, or obtained from renewable starting materials derived from biomass. This particularly relates to polymers, plasticizers, fillers, and the like.

[0015] A first aspect of the present invention is a rubber composition based at least on an elastomeric matrix, a reinforcing filler and granular rubber, the total amount of the reinforcing filler being less than 50 phr, the reinforcing filler comprising at least one carbon black and at least one silica, the total amount of carbon black being less than the total amount of silica.

[0016] The specific composition of the rubber enables an improved and unexpected balance between hysteresis performance qualities and processability.

[0017] Unless expressly stated otherwise, each aspect, embodiment, example and alternative below (including each preferred range, material, or both) may be applied to any of the other aspects, embodiments, examples, and alternatives of the present invention.

[0018] The rubber composition according to the invention is based on an elastomeric matrix.

[0019] By convention, the terms "elastomer" and "rubber" are interchangeable and used without distinction in the context.

[0020] An elastomer of the “diene” type (or more generally “rubber”, the two terms being considered synonymous) is understood in a known manner to mean an elastomer (or elastomers) resulting at least in part (i.e. as a homopolymer or copolymer) from diene monomers (monomers carrying two conjugated or non-conjugated carbon-carbon double bonds).

[0021] These diene elastomers can be divided into two categories: “essentially unsaturated” or “essentially saturated”. Generally, the expression “essentially unsaturated” is understood to mean a diene elastomer derived at least partly from conjugated diene monomers and having a content of units of diene origin (conjugated dienes) greater than 15% (mol %); thus, diene elastomers such as butyl rubber or EPDM-type diene / α-olefin copolymers do not meet the aforementioned definition but 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 category of “essentially unsaturated” diene elastomers, “highly unsaturated” diene elastomers are particularly understood to mean a diene elastomer having a content of units of diene origin (conjugated dienes) greater than 50%.

[0022] Although the present invention is applicable to any type of diene elastomer, it preferably uses essentially unsaturated diene elastomers.

[0023] Taking these definitions into account, the expression “diene elastomer capable of being used in the composition according to the invention” is understood in particular to mean:

[0024] - (a) any homopolymer obtained by polymerization of conjugated diene monomers preferably having 4 to 12 carbon atoms;

[0025] (b) Any copolymer obtained by copolymerizing one or more conjugated dienes with one another or with one or more vinyl aromatic compounds preferably having from 8 to 20 carbon atoms.

[0026] The following compounds are particularly suitable as conjugated dienes: 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-di(C1-C5-alkyl)-1,3-butadiene (e.g. 2,3-dimethyl-1,3-butadiene, 2,3-diethyl-1,3-butadiene, 2-methyl-3-ethyl-1,3-butadiene or 2-methyl-3-isopropyl-1,3-butadiene), aryl-1,3-butadiene, 1,3-pentadiene or 2,4-hexadiene. For example, the following vinylaromatic compounds are suitable: styrene, o-methylstyrene, m-methylstyrene or p-methylstyrene, the commercial "vinyltoluene" mixture, p-(tert-butyl)styrene, methoxystyrene, chlorostyrene, vinylmesitylene, divinylbenzene or vinylnaphthalene.

[0027] The second aspect of the present invention is the rubber composition according to the first aspect, wherein the elastomeric matrix comprises at least one elastomer selected from the group consisting of isoprene elastomer and butadiene elastomer.

[0028] The third aspect of the present invention is the rubber composition according to the first or second aspect, wherein the elastomeric matrix comprises at least one isoprene elastomer, and preferably, the total amount of the isoprene elastomer is greater than 30 phr and less than 70 phr.

[0029] “Isoprene elastomers” are understood to mean all elastomers consisting essentially of isoprene monomers.

[0030] According to a preferred embodiment of the second aspect or the third aspect, the isoprene elastomer is selected from the group consisting of isoprene polymers, isoprene copolymers, and corresponding combinations.

[0031] According to a more preferred embodiment of the above preferred embodiment, the isoprene copolymer is selected from the group consisting of butadiene-isoprene copolymer (BIR), styrene-isoprene copolymer (SIR), styrene-butadiene-isoprene copolymer (SBIR) and corresponding combinations.

[0032] According to an even more preferred embodiment of the above more preferred embodiment, the isoprene content of the butadiene-isoprene copolymer (BIR) is greater than 50 wt% and less than 90 wt% relative to 100 wt% of the butadiene-isoprene copolymer (BIR).

[0033] According to an even more preferred embodiment of the above more preferred embodiments, the butadiene-isoprene copolymer (BIR) has a TgDSC of -80°C to -40°C.

[0034] According to an even more preferred embodiment of the above more preferred embodiment, the styrene content of the styrene-isoprene copolymer (SIR) is greater than 5 wt% and less than 50 wt% relative to 100 wt% of the styrene-isoprene copolymer (SIR).

[0035] According to an even more preferred embodiment of the above more preferred embodiments, the styrene-isoprene copolymer (SIR) has a TgDSC greater than -50°C and less than -25°C.

[0036] According to an even more preferred embodiment of the above more preferred embodiments, the isoprene content of the styrene-butadiene-isoprene copolymer (SBIR) is greater than the styrene and butadiene contents.

[0037] According to an even more preferred embodiment of the above more preferred embodiment, the isoprene content of the styrene-butadiene-isoprene copolymer (SBIR) is greater than 50 wt% and less than 60 wt% relative to 100 wt% of the styrene-butadiene-isoprene copolymer (SBIR).

[0038] According to a preferred embodiment of the second aspect or the third aspect, the isoprene elastomer is selected from natural rubber, synthetic polyisoprene and corresponding combinations; preferably, the isoprene elastomer consists of natural rubber.

[0039] According to a more preferred embodiment of the preferred embodiment, the synthetic polyisoprene is a synthetic polyisoprene having a cis-1,4-linkage content (mol %) of preferably greater than 90%, more preferably greater than 95%, and even more preferably greater than 98%.

[0040] The fourth aspect of the present invention is the rubber composition according to any one of the first to third aspects, wherein the elastomeric matrix comprises at least one butadiene elastomer, and preferably, the total amount of the butadiene elastomer is greater than 30 phr and less than 70 phr.

[0041] “Butadiene elastomers” are understood to mean all elastomers consisting essentially of butadiene monomers.

[0042] According to a preferred embodiment of the second aspect or the fourth aspect, the butadiene elastomer is selected from butadiene polymers, butadiene copolymers and corresponding combinations, preferably selected from polybutadiene (BR), styrene-butadiene copolymer (SBR) and corresponding combinations.

[0043] According to a more preferred embodiment, the butadiene elastomer is selected from polybutadiene (BR) and corresponding combinations.

[0044] According to an even more preferred embodiment of the above more preferred embodiments, the polybutadiene has a 1,2-unit content (mol %) of greater than 4% and less than 80%.

[0045] According to an even more preferred embodiment of the above more preferred embodiments, the polybutadiene has a cis-1,4-content (mol %) greater than 80%.

[0046] According to a more preferred embodiment of the preferred embodiment, the butadiene copolymer is selected from the group consisting of styrene-butadiene copolymer (SBR), butadiene-isoprene copolymer (BIR), styrene-butadiene-isoprene copolymer (SBIR) and corresponding combinations.

[0047] According to an even more preferred embodiment of the above more preferred embodiments, the butadiene copolymer is selected from styrene-butadiene copolymer (SBR) and corresponding combinations.

[0048] According to a specific embodiment of the above-mentioned even more preferred embodiment, the glass transition temperature TgDSC of the styrene-butadiene copolymer (SBR) is greater than -100°C and less than 0°C, preferably greater than -90°C and less than 0°C, more preferably greater than -80°C and less than 0°C, still more preferably greater than -70°C and less than 0°C, in particular greater than -60°C and less than -10°C.

[0049] According to a specific embodiment of the above-mentioned even more preferred embodiment, the styrene content of the styrene-butadiene copolymer (SBR) is greater than 5% by weight and less than 60% by weight, more particularly greater than 20% by weight and less than 50% by weight, relative to 100% by weight of the styrene-butadiene copolymer (SBR).

[0050] According to a specific embodiment of the above-mentioned even more preferred embodiment, the styrene-butadiene copolymer (SBR) has a 1,2-linkage content (mol %) of the butadiene portion of greater than 4% and less than 75% and a trans-1,4-linkage content (mol %) greater than 10% and less than 80%.

[0051] According to an even more preferred embodiment of the above more preferred embodiments, the butadiene copolymer is selected from butadiene-isoprene copolymers (BIR) and corresponding combinations.

[0052] According to particularly preferred embodiments of the above even more preferred embodiments, the isoprene content of the butadiene-isoprene copolymer (BIR) is greater than 5% by weight and less than 50% by weight relative to 100% by weight of the butadiene-isoprene copolymer (BIR).

[0053] According to a particular embodiment of the above even more preferred embodiment, the butadiene-isoprene copolymer (BIR) has a TgDSC in the range of -80°C to -40°C.

[0054] According to an even more preferred embodiment of the above more preferred embodiment, the butadiene copolymer is selected from styrene-butadiene-isoprene copolymer (SBIR) and corresponding combinations thereof. The butadiene content of the styrene-butadiene-isoprene copolymer (SBIR) is greater than the styrene and isoprene contents.

[0055] The fifth aspect of the present invention is a rubber composition according to any one of the first to fourth aspects, wherein the elastomeric matrix comprises at least one isoprene elastomer and at least one butadiene elastomer, preferably, the total amount of the isoprene elastomer is greater than 30 phr and less than 70 phr, and the total amount of the butadiene elastomer is greater than 30 phr and less than 70 phr.

[0056] According to a preferred embodiment of the third aspect or the fifth aspect, the total amount of isoprene elastomer is less than or equal to 65 phr, preferably less than 65 phr, more preferably less than or equal to 60 phr, still more preferably less than 60 phr, in particular less than or equal to 55 phr, more in particular less than 55 phr.

[0057] According to a preferred embodiment of the third aspect or the fifth aspect, the total amount of isoprene elastomer is greater than or equal to 35 phr, preferably greater than 35 phr, more preferably greater than or equal to 40 phr, still more preferably greater than 40 phr, in particular greater than or equal to 45 phr, more in particular greater than 45 phr.

[0058] According to a preferred embodiment of the fourth or fifth aspect, the total amount of butadiene elastomer is less than or equal to 65 phr, preferably less than 65 phr, more preferably less than or equal to 60 phr, even more preferably less than 60 phr, in particular less than or equal to 55 phr, more in particular less than 55 phr.

[0059] According to a preferred embodiment of the fourth aspect or the fifth aspect, the total amount of butadiene elastomer is greater than or equal to 35 phr, preferably greater than 35 phr, more preferably greater than or equal to 40 phr, still more preferably greater than 40 phr, in particular greater than or equal to 45 phr, more in particular greater than 45 phr.

[0060] According to a preferred embodiment of the invention, the elastomeric matrix in the rubber composition according to the invention consists of an isoprene elastomer and a butadiene elastomer.

[0061] According to another preferred embodiment of the invention, the elastomeric matrix in the rubber composition according to the invention comprises another elastomer or an elastomer other than the isoprene elastomer and the butadiene elastomer.

[0062] Thus, any elastomer known to those skilled in the art (which is not defined above as an isoprene elastomer or a butadiene elastomer) may be used.

[0063] The rubber composition according to the invention is based on reinforcing fillers, and the total amount of reinforcing fillers is less than 50 phr, preferably less than or equal to 45 phr, more preferably less than 45 phr, still more preferably less than or equal to 40 phr, in particular less than 40 phr.

[0064] The sixth aspect of the present invention is a rubber composition according to any one of the first to fifth aspects, wherein the total amount of reinforcing filler is greater than 5 phr, preferably greater than or equal to 10 phr, more preferably greater than 10 phr, and even more preferably greater than or equal to 15 phr, especially greater than 15 phr, more especially greater than or equal to 20 phr, even more especially greater than 20 phr, advantageously greater than or equal to 25 phr, more advantageously greater than 25 phr, even more advantageously greater than or equal to 30 phr, especially greater than 30 phr, more especially greater than or equal to 35 phr, and even more especially greater than 35 phr.

[0065] Any type of reinforcing filler known to be capable of reinforcing a rubber composition that can be used to manufacture rubber products may be used, such as organic reinforcing fillers (e.g., at least one carbon black) or inorganic reinforcing fillers (e.g., silica (SiO2), aluminum oxide (Al2O3), or combinations thereof) combined in a known manner with at least one coupling agent.

[0066] The reinforcing filler of the rubber composition according to the invention comprises at least one carbon black.

[0067] The seventh aspect of the present invention is a rubber composition according to any one of aspects 1 to 6, wherein the total amount of carbon black in the reinforcing filler is greater than 0 phr, preferably greater than or equal to 1 phr, more preferably greater than 1 phr, and even more preferably greater than or equal to 2 phr, especially greater than 2 phr, and more especially greater than or equal to 3 phr, and the total amount of carbon black in the reinforcing filler is less than 20 phr, preferably less than or equal to 15 phr, more preferably less than 15 phr, even more preferably less than or equal to 10 phr, especially less than 10 phr, more especially less than or equal to 5 phr, and even more especially less than 5 phr.

[0068] The weight fraction of carbon black can be measured by thermogravimetric analysis (TGA) on a model TGA / DSC1 instrument from Mettler Toledo according to standard NFT-46-07. About 20 g of sample can be introduced into the thermal analyzer and then subjected to a thermal program (thermolyzable stage) from 25° C. to 600° C. under an inert atmosphere, and then subjected to a thermal program (oxidizable stage) from 400° C. to 750° C. under an oxidizing atmosphere. The weight of the sample can be measured continuously throughout the thermal program. The content of organic matter can correspond to the weight loss relative to the initial weight of the sample measured during the pyrolyzable stage. The amount of carbon black can correspond to the weight loss relative to the initial weight of the sample measured during the oxidizable stage.

[0069] Suitable carbon blacks are all carbon blacks, in particular blacks of the SAF, ISAF, HAF, FEF, GPF, HMF, SRF and SRF types customary in tires (“tire-quality” carbon blacks), for example reinforcing carbon blacks of the ASTM grades 100, 200 or 300 series (for example N115, N134, N234, N326, N330, N339, N347 or N375 carbon blacks), or higher carbon blacks of the ASTM grades 500, 600, 700, 800 or 900 series (for example N550, N660, N683, N772, N774, N880, N990, N991 carbon blacks).

[0070] According to a preferred embodiment of the present invention, the BET specific surface area of ​​the carbon black (according to standard ASTM D6556-10) is greater than 80 m 2 / g (for example, at 80m 2 / g and 160m 2 / g), preferably greater than 90m 2 / g (for example, at 90m 2 / g and 150m 2 / g), more preferably greater than 100m 2 / g (for example, at 100m 2 / g and 140m 2 / g), and more preferably greater than 110 m 2 / g (for example, at 110m 2 / g and 130m 2 / g).

[0071] According to a preferred embodiment of the present invention, the carbon black has a compression oil absorption value (COAN: Compression Oil Absorption Number) (according to standard ASTM D3493-16) greater than 90 ml / 100 g (for example, between 90 ml / 100 g and 120 ml / 100 g), preferably greater than 95 ml / 100 g (for example, between 95 ml / 100 g and 115 ml / 100 g), more preferably greater than 100 ml / 100 g (for example, between 100 ml / 100 g and 110 ml / 100 g).

[0072] The reinforcing filler of the rubber composition according to the invention comprises at least one silica.

[0073] The eighth aspect of the present invention is a rubber composition according to any one of aspects 1 to 7, wherein the total amount of silica in the reinforcing filler is greater than 20 phr, preferably greater than or equal to 25 phr, more preferably greater than 25 phr, and even more preferably greater than or equal to 30 phr, in particular greater than 30 phr, and the total amount of silica in the reinforcing filler is less than 50 phr, preferably less than or equal to 45 phr, more preferably less than 45 phr, even more preferably less than or equal to 40 phr, in particular less than 40 phr, more particularly less than or equal to 35 phr, and even more particularly less than 35 phr.

[0074] According to a preferred embodiment of the present invention, the silicon dioxide is any reinforced silicon dioxide, in particular, the BET specific surface area and the CTAB specific surface area are less than 450 m 2 / g, preferably 20m 2 / g to 400m 2 / g, more preferably 50m 2 / g to 350m 2 / g, and more preferably 100m 2 / g to 300m 2 / g, especially at 150m 2 / g and 250m 2 / g of any precipitated silica or fumed silica. The BET specific surface area can be measured according to a known method (i.e., by gas adsorption according to the Brunauer-Emmett-Teller method described in the Journal of the American Chemical Society (Volume 60, page 309, February 1938)), more specifically according to the French standard NF ISO 9277 of December 1996 (multipoint (5-point) volumetric method; gas: nitrogen, degassing: 1 hour at 160°C, relative pressure p / p0 range: 0.05 to 0.17). The CTAB specific surface area can be determined according to the French standard NF T 45-007 of November 1987 (Method B).

[0075] According to a preferred embodiment of the invention, the silica is formed from particles having a weight average size of less than 1000 nm, preferably less than 500 nm, more preferably less than 200 nm, still more preferably between 20 nm and 200 nm. The weight average size can be measured in a known manner after dispersion of the filler to be analyzed by ultrasonic deagglomeration in water (or an aqueous solution containing a surfactant), for example by means of a centrifugal sedimentometer of the XDC (X-ray Disc Centrifuge) type with X-ray detection sold by Brookhaven Instruments according to the following steps: 3.2 g of the inorganic filler sample to be analyzed is suspended in 40 ml of water by means of a 1500 W ultrasonic probe (Vibracell ¾ inch sonicator sold by Bioblock) at 60% power (60% of the maximum position of the "output control") for 8 minutes; after ultrasonic treatment, 15 ml of the suspension are introduced into a rotating disk; after sedimentation for 120 minutes, the weight distribution of the particle sizes and the weight average size dw of the particles are calculated by the software of the XDC sedimentometer.

[0076] The total amount of carbon black (in phr) in the reinforcing filler of the rubber composition according to the invention is less than the total amount of silica.

[0077] According to a preferred embodiment of the present invention, the total amount of carbon black in the reinforcing filler of the rubber composition according to the present invention is less than 90% by weight, preferably less than 80% by weight, more preferably less than 70% by weight, still more preferably less than 60% by weight, in particular less than 50% by weight, more in particular less than 40% by weight, still more in particular less than 30% by weight, advantageously less than 20% by weight, and more advantageously less than 10% by weight, relative to 100% by weight of reinforcing filler.

[0078] According to a preferred embodiment of the invention, the rubber composition according to the invention is based on a silane-type coupling agent.

[0079] Silane-type coupling agents are intended to provide sufficient chemical bonding, sufficient physical bonding, or both, between the silica and the elastomeric matrix.

[0080] Silane-type coupling agents (which, by definition, are at least bifunctional) have the simplified general formula "YAX" where:

[0081] -Y represents a functional group capable of physically bonding to silica, chemically bonding to silica, or both physically and chemically bonding to silica, such as establishing such a bond between a silicon atom of a silane-type coupling agent and a surface silanol group of silica;

[0082] - X represents a functional group ("X" functional group) capable of physically bonding to the elastomeric matrix, chemically bonding to the elastomeric matrix, or physically and chemically bonding to the elastomeric matrix, for example, through a sulfur atom;

[0083] -A represents a divalent group capable of linking Y and X.

[0084] Difunctional organosilanes or polyorganosiloxanes are generally used, and are usually referred to as "symmetrical" or "asymmetrical" silane polysulfides depending on their specific structure, as described in numerous patent documents (see, for example, WO 03 / 002648, WO 03 / 002649 or WO 2004 / 033548).

[0085] As a reminder, the most widely used are the "symmetrical" silane polysulfides corresponding to the following general formula (I):

[0086] ZAS x -AZ(I), where:

[0087] -x is an integer from 2 to 8 (preferably from 2 to 5);

[0088] -A is a divalent hydrocarbon group, preferably C1-C 18 Alkylene or C6-C 12 Arylene, more particularly C1-C 10 Alkylene, especially C1-C4 alkylene, especially propylene;

[0089] -Z corresponds to one of the following:

[0090] [Chemical Formula 1]

[0091]

[0092] in:

[0093] -R a The groups are substituted or unsubstituted and are the same or different from each other and represent C1-C18 Alkyl, C5-C 18 Cycloalkyl or C6-C 18 aryl (preferably C1-C6 alkyl, cyclohexyl or phenyl, especially C1-C4 alkyl, more especially methyl, ethyl or methyl and ethyl),

[0094] -R b The groups are substituted or unsubstituted and are the same or different from each other and represent C1-C 18 Alkoxy or C5-C 18 Cycloalkoxy groups (preferably groups selected from C1-C8 alkoxy and C5-C8 cycloalkoxy, more preferably groups selected from C1-C4 alkoxy, in particular methoxy and ethoxy) are particularly suitable without being restricted by the above definition.

[0095] In the case of mixtures of alkoxysilane polysulfides corresponding to the above formula (I), in particular commercially available standard mixtures, the average value of the "x" index is preferably a fraction between 2 and 5, more preferably a fraction close to 4. However, the invention can also be advantageously carried out using, for example, alkoxysilane disulfides (x=2).

[0096] As examples of silane polysulfides, mention may be made more particularly of bis((C1-C4)alkoxy(C1-C4)alkylsilyl(C1-C4)alkyl)polysulfides (in particular disulfides, trisulfides or tetrasulfides), such as bis(3-trimethoxysilylpropyl)polysulfide or bis(3-triethoxysilylpropyl)polysulfide. Of these compounds, use is made in particular of bis(3-triethoxysilylpropyl)tetrasulfide (abbreviated to TESPT, chemical formula [(C2H5O)3Si(CH2)3S2]2) or bis(3-triethoxysilylpropyl)disulfide (abbreviated to TESPD, chemical formula [(C2H5O)3Si(CH2)3S]2). As preferred examples, mention will also be made of bis(mono(C1-C4)alkoxydi(C1-C4)alkylsilylpropyl)polysulfides (in particular disulfides, trisulfides or tetrasulfides), more particularly bis(monoethoxydimethylsilylpropyl)tetrasulfide, as described in patent application WO 02 / 083782 (or US 7217751).

[0097] As coupling agents other than alkoxysilane polysulfides, mention may be made in particular of difunctional POS (polyorganosiloxanes) or hydroxysilane polysulfides (Rb═OH in formula (I) above), as described, for example, in patent applications WO 02 / 30939 (or US Pat. No. 6,774,255) and WO 02 / 31041 (or US Pat. No. 2004 / 051210), or silanes or POS carrying an azodicarbonyl function, as described, for example, in patent applications WO 2006 / 125532, WO 2006 / 125533 and WO 2006 / 125534.

[0098] As examples of other silane sulfides, mention may be made of silanes carrying at least one thiol (—SH) function (called mercaptosilanes), at least one blocked thiol function or both, as described, for example, in patents or patent applications US 6849754, WO 99 / 09036, WO 2006 / 023815, WO 2007 / 098080, WO 2008 / 055986 and WO 2010 / 072685.

[0099] Of course, it is also possible to use mixtures of the aforementioned silane-type coupling agents, as described in particular in the aforementioned patent application WO 2006 / 125534.

[0100] According to a more preferred embodiment, the amount of silane-type coupling agent in the rubber composition according to the invention is between 5% and 20% by weight relative to 100% by weight of silica.

[0101] According to a preferred embodiment of the invention, the amount of silane-type coupling agent is between 1 and 10 phr, preferably between 1 and 5 phr.

[0102] The rubber composition according to the invention is based on granular rubber (hereinafter referred to as "crump" for short).

[0103] The ninth aspect of the present invention is a rubber composition according to any one of the first to eighth aspects, wherein the total amount of granular rubber is greater than 0 phr, preferably greater than or equal to 1 phr, more preferably greater than 1 phr, and even more preferably greater than or equal to 2 phr, especially greater than 2 phr, more especially greater than or equal to 3 phr, and even more especially greater than 3 phr, and the total amount of granular rubber is less than 50 phr, preferably less than or equal to 40 phr, more preferably less than 40 phr, even more preferably less than or equal to 30 phr, especially less than 30 phr, more especially less than or equal to 20 phr, even more especially less than 20 phr, advantageously less than or equal to 15 phr, more advantageously less than 15 phr, even more advantageously less than or equal to 10 phr, especially less than 10 phr.

[0104] The tenth aspect of the present invention is the rubber composition according to any one of the first to ninth aspects, wherein the total amount of granular rubber calculated on a phr basis is greater than the total amount of carbon black, and the total amount of granular rubber calculated on a phr basis is less than the total amount of silica.

[0105] Crumbs are in the form of granules, optionally converted into rubber sheets. Typically, crumb rubbers originate from the grinding or micronization of vulcanized rubber compositions that have been used for a first application, for example in tires; they are the product of material recycling.

[0106] Crumb rubber can be obtained by reducing worn tires or other rubber to produce granules, from which the reinforcing material (e.g. steel or fibers) and any other contaminants (e.g. dust, glass or stones) have been removed. The work "Rubber Chemistry and Technology" discloses a number of methods for grinding vulcanized or crosslinked rubber to obtain crumb rubber.

[0107] According to a preferred embodiment of the present invention, the crumb rubber is produced from worn tires.

[0108] According to a preferred embodiment of the present invention, the crumb rubber is in the form of microparticles.

[0109] The term "microparticles" is understood to mean particles whose size, ie their diameter (in the case of spherical particles) or their largest dimension (in the case of non-isometric particles), is a few micrometers or tens or hundreds of micrometers.

[0110] An eleventh aspect of the present invention is the rubber composition according to any one of the first to tenth aspects, wherein the crumb rubber does not include any crumb rubber particles retained on a 40-mesh sieve, or the crumb rubber includes crumb rubber particles retained on a 40-mesh sieve, and the total amount of crumb rubber particles retained on the 40-mesh sieve is less than 10% by weight relative to 100% by weight of the crumb rubber. Preferably, the crumb rubber does not include any crumb rubber particles retained on a 60-mesh sieve, or the crumb rubber includes crumb rubber particles retained on a 60-mesh sieve, and the total amount of crumb rubber particles retained on the 60-mesh sieve is less than 10% by weight relative to 100% by weight of the crumb rubber. More preferably, the crumb rubber does not include any crumb rubber particles retained on an 80-mesh sieve, or the crumb rubber includes crumb rubber particles retained on an 80-mesh sieve, and the total amount of crumb rubber particles retained on the 80-mesh sieve is less than 10% relative to 100% by weight of the crumb rubber.

[0111] The total amount of crumb rubber particles retained on the 40-mesh screen is less than 10 wt% relative to 100 wt% of the crumb rubber, which means that more than 90 wt% of the crumb rubber particles can pass through the 40-mesh screen relative to 100 wt% of the crumb rubber.

[0112] The total amount by weight of crumb rubber particles of the crumb rubber of the rubber composition according to the invention can be obtained by the size distribution of the particles of the crumbs determined according to Standard ASTM-D5644-01.

[0113] Alternatively, the size distribution of the particles of the granulate (i.e. the weight distribution of the sizes of the particles of the granulate) can be measured by laser particle size analysis on a Mastersizer 3000 device from Malvern. The measurement can be carried out by liquid route, diluting with alcohol after pretreatment with ultrasound for 1 minute to ensure dispersion of the particles. The measurement can be carried out according to standard ISO-13320-1 and can in particular determine the D10 and D50 (i.e. the average diameter below which 10% and 50% by weight of the total number of particles are present, respectively).

[0114] According to preferred embodiment of the present invention, the granular rubber according to rubber combination of the present invention is carried out mechanical treatment, cryogenic treatment or mechanical treatment and cryogenic treatment, promptly use mechanical grinding process, cryogenic process or two kinds of technology that granular rubber is ground.In these two kinds of technology, use magnetic separator to remove steel component, and use air classifier or other separating equipment separated fiber component.Mechanical grinding process uses various grinding techniques (for example crusher, granulator etc.) so that rubber is mechanically broken into smaller particles.In cryogenic process, will be frozen to extremely low temperature through shredding rubber, be broken into smaller particles then.

[0115] According to a more preferred embodiment of the above preferred embodiment, the crumb rubber is subjected to a low temperature treatment according to the micronization process described in documents US7445170 and US7861958.

[0116] Commercially available crumb rubber is, for example, PolyDyne 40, PolyDyne 80, PolyDyne 140 or PolyDyne 200 from Lehigh Technologies.

[0117] The crumb rubber of the rubber composition according to the present invention may be composed of a composition based on all ingredients generally used in rubber compositions for rubber products.

[0118] According to a preferred embodiment of the invention, the crumb rubber of the rubber composition according to the invention consists of an elastomer-based composition.

[0119] According to a more preferred embodiment of the above preferred embodiment, the crumb rubber comprises more than 30% by weight, preferably more than 35% by weight, more preferably more than 40% by weight of elastomer relative to 100% by weight of crumb rubber, said percentages being determined according to standard ASTM E1131-03.

[0120] According to the above preferred embodiment or a more preferred embodiment of the above more preferred embodiment, the crumb rubber comprises an elastomer comprising, preferably consisting of, a diene elastomer.

[0121] According to a particular embodiment of the above-mentioned even more preferred embodiment, the diene elastomer of the crumb rubber is chosen from polybutadienes, polyisoprenes (including natural rubber), butadiene copolymers and isoprene copolymers.

[0122] According to a particular embodiment of the above-mentioned even more preferred embodiment, the molar content of units of diene origin (conjugated dienes) present in the diene elastomer of the crumb rubber is greater than 50%, preferably greater than 50% and less than 70%.

[0123] According to a preferred embodiment of the invention, the crumb rubber of the rubber composition according to the invention consists of a filler-based composition.

[0124] According to a more preferred embodiment of the above preferred embodiment, the above amount of filler in the crumb rubber is greater than 5% by weight and less than 80% by weight, preferably greater than 10% by weight and less than 75% by weight, more preferably greater than 15% by weight and less than 70% by weight of filler relative to 100% by weight of crumb rubber, the percentages being determined according to standard ASTM E1131-03.

[0125] Here, the term "filler" refers to any type of filler, whether reinforcing filler (usually nanoparticles with a weight average size preferably less than 500 nm, in particular greater than 20 nm and less than 200 nm) or non-reinforcing filler or inert filler (usually microparticles with a weight average size preferably greater than 1 μm, for example greater than 2 μm and less than 200 μm). The weight average size of the nanoparticles is measured in a manner known to those skilled in the art (for example, according to section 1.1 of patent application WO 2009 / 083160). The weight average size of the microparticles can be determined by mechanical sieving.

[0126] According to a more preferred embodiment of the above preferred embodiment, the filler of the granulated rubber comprises a reinforcing filler; preferably, the reinforcing filler comprises an organic reinforcing filler, an inorganic reinforcing filler or a combination thereof.

[0127] Any type of reinforcing filler known to be capable of reinforcing a rubber composition that can be used to manufacture rubber products may be used, such as organic reinforcing fillers (e.g., at least one carbon black) or inorganic reinforcing fillers (e.g., silica (SiO2), aluminum oxide (Al2O3), or combinations thereof) combined in a known manner with at least one coupling agent.

[0128] According to an even more preferred embodiment of the above-mentioned more preferred embodiment, the reinforcing filler of the granulated rubber comprises an organic reinforcing filler, preferably at least one carbon black, more preferably representing more than 50% by weight, still more preferably more than 60% by weight, in particular more than 70% by weight, more in particular more than 80% by weight, still more in particular more than 90% by weight, advantageously 100% by weight, relative to 100% by weight of the reinforcing filler.

[0129] According to an even more preferred embodiment of the above-mentioned more preferred embodiment, the reinforcing filler of the crumb rubber comprises an organic reinforcing filler, preferably at least one carbon black, more preferably representing 20 to 40 wt. %, still more preferably 25 to 35 wt. %, relative to 100 wt. % of the crumb rubber.

[0130] The weight fraction of carbon black can be measured by thermogravimetric analysis (TGA) on a model TGA / DSC1 instrument from Mettler Toledo according to standard NF T-46-07. A sample of up to 20 g can be introduced into the thermal analyzer and then subjected to a thermal program from 25° C. to 600° C. under an inert atmosphere (thermolyzable stage) and then to a thermal program from 400° C. to 750° C. under an oxidizing atmosphere (oxidizable stage). The weight of the sample can be measured continuously throughout the thermal program. The content of organic matter can correspond to the weight loss measured during the thermolyzable stage relative to the initial weight of the sample. The amount of carbon black can correspond to the weight loss measured during the oxidizable stage relative to the initial weight of the sample.

[0131] Suitable carbon blacks are all carbon blacks, in particular blacks of the SAF, ISAF, HAF, FEF, GPF, HMF, SRF and SRF types customary in tires (“tire-quality” carbon blacks), for example reinforcing carbon blacks of the ASTM grades 100, 200 or 300 series (for example N115, N134, N234, N326, N330, N339, N347 or N375 carbon blacks), or higher carbon blacks of the ASTM grades 500, 600, 700, 800 or 900 series (for example N550, N660, N683, N772, N774, N880, N990, N991 carbon blacks).

[0132] According to a more preferred embodiment of the above preferred embodiment, the filler of the crumb rubber comprises a non-reinforcing filler, which is preferably chalk, kaolin or a corresponding combination.

[0133] The crumb rubber of the rubber composition according to the invention may be composed of a composition based on conventional additives commonly used in rubber compositions intended for rubber products. Additives may also be present in the crumb rubber in the form of residues or derivatives, since they may have reacted during the production phase of the composition or during the crosslinking phase of the composition producing the crumb rubber.

[0134] The crumb rubber of the rubber composition according to the present invention may be a simply ground / micronized rubber material without any further treatment.

[0135] The twelfth aspect of the present invention is the rubber composition according to any one of the first to eleventh aspects, wherein the crumb rubber has not been subjected to any modification by treatment selected from the group consisting of heat treatment, mechanical treatment, biological treatment, chemical treatment, and respective combinations thereof.

[0136] According to a preferred embodiment of the twelfth aspect, the acetone extractable amount of the granular rubber is greater than 3 wt% and less than 30 wt%, preferably greater than 3 wt% and less than 15 wt%, more preferably greater than 3 wt% and less than 10 wt%, relative to 100 wt% of the granular rubber.

[0137] According to a preferred embodiment of the twelfth aspect, the chloroform extract of the crumb rubber is greater than 3 wt% and less than 85 wt%, preferably greater than 3 wt% and less than 20 wt%, more preferably greater than 5 wt% and less than 15 wt%, relative to 100 wt% of the crumb rubber.

[0138] According to a preferred embodiment of the twelfth aspect, the crumb rubber has a chloroform extractable having a weight average molecular weight (Mw) of less than 10,000 g / mol, preferably less than 8,000 g / mol.

[0139] According to a preferred embodiment of the twelfth aspect, the weight ratio of the chloroform extractable to the acetone extractable in the crumb rubber is less than 1.5.

[0140] According to a preferred embodiment of the present invention, the crumb rubber of the rubber composition according to the present invention is treated to modify it. Such treatment may include chemical functionalization or devulcanization. Such treatment may also be thermomechanical treatment, thermochemical treatment, biological treatment, etc.

[0141] According to one embodiment of the present invention, the crumb rubber of the rubber composition according to the present invention exhibits a morphology modified by heat treatment, mechanical treatment, biological treatment, chemical treatment or a corresponding combination. Preferably, the acetone extractable content of the modified crumb rubber is greater than 5% by weight and less than 20% by weight, more preferably between 10% and 18% by weight. Similarly, preferably, the chloroform extractable content of the modified crumb rubber is greater than 15% by weight and less than 85% by weight, more preferably between 15% and 50% by weight. Preferably, the weight-average molecular weight (Mw) of the chloroform extractable content of the modified crumb rubber is greater than 10,000 g / mol, more preferably greater than 20,000 g / mol, and even more preferably greater than 30,000 g / mol. Preferably, the weight ratio of chloroform extractable content to acetone extractable content in the modified crumb rubber is greater than or equal to 1.5, preferably greater than 2.

[0142] The amount of acetone extract or chloroform extract can be measured by a Soxhlet type extractor according to standard ISO 1407. A test sample (greater than 500 mg and less than 5 g) can be introduced into the extraction chamber and then placed in the Soxhlet extraction tube. A volume of acetone or chloroform equal to two or three times the volume of the extraction tube can be placed in the Soxhlet collector. The Soxhlet can then be assembled and heated for 16 hours. After extraction, the sample can be weighed. The amount of acetone extract or chloroform extract can correspond to the weight loss of the sample relative to its initial weight during the extraction process.

[0143] The molecular weight can be determined by size exclusion chromatography according to the Moore calibration and according to standard ISO 16014. The weight average molecular weight (Mw) of the chloroform extract can be measured by size exclusion chromatography (SEC) with a refractive index (RI) detector. The system can consist of an Alliance 2695 line from Waters, a column oven from Waters, and an RI 410 detector from Waters. The chromatographic column set used can consist of two PL Gel Mixed D columns (300×7.5 mm, 5 μm) from Agilent followed by two PL Gel Mixed E columns (300×7.5 mm, 3 μm). These columns can be placed in a column oven thermostated at 35°C. The mobile phase used can be non-oxidized tetrahydrofuran. The flow rate of the mobile phase can be 1 ml / min. The RI detector can also be thermostated at 35°C. The chloroform extract can be dried under a stream of nitrogen. Subsequently, the dry extract can be dissolved in 250 ppm of non-antioxidant tetrahydrofuran at 1 g / l and stirred for 2 hours. The resulting solution can be filtered using a syringe and a disposable 0.45 μm PTFE syringe filter. 100 μl of the filtered solution can be injected into a conditioned chromatography system at 35°C at 1 ml / min. The Mw result can be provided by integrating the chromatographic peak above the value of 2000 g / mol detected by the RI detector. The Mw can be calculated by calibration using a polystyrene reference.

[0144] The total amount of reinforcing filler and crumb rubber in the rubber composition according to the invention is greater than 30 phr and less than 70 phr.

[0145] According to a preferred embodiment of the invention, the total amount of reinforcing filler and granular rubber in the rubber composition according to the invention is greater than or equal to 35 phr, preferably greater than 35 phr, more preferably greater than or equal to 40 phr, still more preferably greater than 40 phr, in particular greater than or equal to 45 phr, more in particular greater than 45 phr.

[0146] According to a preferred embodiment of the invention, the total amount of reinforcing filler and granular rubber in the rubber composition according to the invention is less than or equal to 65 phr, preferably less than 65 phr, more preferably less than or equal to 60 phr, still more preferably less than 60 phr, in particular less than or equal to 55 phr, more in particular less than 55 phr, still more in particular less than or equal to 50 phr, in particular less than 50 phr.

[0147] The weight ratio of the total amount of granular rubber to the total amount of reinforcing filler in the rubber composition according to the invention is greater than 0.20 and less than 2.50, preferably less than or equal to 2.00, more preferably less than 2.00, still more preferably less than or equal to 1.50, particularly less than 1.50, more particularly less than or equal to 1.00, yet more particularly less than 1.00.

[0148] The rubber composition according to the invention may be based on all or at least a portion of the common additives usually used in rubber compositions intended for rubber products (e.g. tires, footwear, conveyor belts or tracks), such as plasticizers (e.g. liquid plasticizers (e.g. oils), solid plasticizers (e.g. hydrocarbon resins with or without the characteristics of tackifying resins) or corresponding combinations), protective agents (e.g. anti-ozone waxes, chemical anti-ozonants, antioxidants or corresponding combinations), pigments, anti-fatigue agents, reinforcing resins, methylene acceptors (e.g. phenolic resins), methylene donors (e.g. hexamethylenetetramine (HMT), hexamethoxymethylmelamine (H3M) or corresponding combinations), treating acids, crosslinking (vulcanization) systems or corresponding combinations.

[0149] The thirteenth aspect of the present invention is a rubber composition according to any one of the first to twelfth aspects, wherein the rubber composition is also based on an anti-ozone wax, preferably, the total amount of the anti-ozone wax is greater than 1 phr to maintain or further improve the performance quality of ozone resistance.

[0150] The ozone resistance performance quality of a rubber composition can be measured according to the following method: 10 specimens of each rubber composition are prepared by curing in a bell press, cooling to ambient temperature for 1 day, and then placing in an oven at 77°C in air for 28 days. The 10 specimens of each rubber composition are placed on a trapezoidal shape at different elongations ranging from 10% to 100% in stages at 10% elongation. The specimens, designated "B15," are derived from MFTR (Monsanto) plates, which have two beads at the ends to hold the specimens. The "B15" specimens have the following dimensions: 78.5mm*15mm*1.5mm. After exposure to an ozone content of 50 parts per million (pphm) at a temperature of 38°C for 192 hours, the appearance of each specimen is recorded, along with the number and depth of cracks. This subjective rating ranges from 0 to 5 (0: no cracks; 1 to 4: cracks of increasing width and depth; 5: specimen fracture). This means that the lower the subjective rating, the better the performance quality with respect to ozone.

[0151] According to a preferred embodiment of the fourteenth aspect, the total amount of anti-ozonate wax in the rubber composition according to the present invention is greater than or equal to 1.1 phr, preferably greater than 1.1 phr, more preferably greater than or equal to 1.2 phr, still more preferably greater than 1.2 phr, in particular greater than or equal to 1.3 phr, more in particular greater than 1.3 phr.

[0152] Anti-ozon waxes are known as anti-ozon waxes and are well known to those skilled in the art as film-forming anti-ozon waxes. These film-forming anti-ozon waxes may be, for example, paraffin waxes, microcrystalline waxes or mixtures of paraffin waxes and microcrystalline waxes. They consist of a mixture of linear alkanes and non-linear alkanes (isoalkanes, cycloalkanes, branched alkanes) containing mainly chains of at least 20 carbon atoms, which are produced by oil refining or by catalytic hydrogenation of carbon monoxide (Fischer-Tropsch process).

[0153] All anti-ozonant waxes known to those skilled in the art can be used, including natural waxes, such as candelilla wax or carnauba wax. In addition, these waxes can also be used as mixtures.

[0154] Commercially available anti-ozon waxes are, for example, Varazon 4959, Varazon 6500 and Varazon 6810 from Sasol, Ozoace 0355 from Nippon Seiro, Negozone 9343 from H&R and H3841 from Yanggu Huatai.

[0155] According to a preferred embodiment of the fourteenth aspect, the antiozon wax comprises 50 to 75 wt% of linear alkanes containing 30 to 38 carbon atoms, relative to the total amount of linear alkanes.

[0156] According to a preferred embodiment of the fourteenth aspect, the total amount of the anti-ozon wax is less than 3 phr to improve performance qualities with respect to weathering. Weathering is a phenomenon in which the anti-ozon wax exhibits a disadvantage of migrating toward the exterior of a rubber product comprising the rubber composition, thereby revealing off-white stains that detract from the aesthetics of the rubber product.

[0157] The weathering performance quality of the rubber composition can be measured according to the following method: after the operation of cutting the plate of the rubber composition in the cured state, a sample with a thickness of 2.5 mm is aged in air at 70 ° C for 12 hours. Subsequently, it is baked in air at 40 ° C for 4 weeks. After leaving the oven and being exposed to ambient temperature for 15 minutes, each sample is scratched with a metal blade to show the weathering of the anti-ozone wax. Subsequently, the degree of weathering (surface white) is evaluated by the value of the subjective scale representing the final appearance of the sample. The value of this subjective scale obtained for the sample can vary from 0 to 3, corresponding to "weathering grade". These values ​​ranging from 0 to 3 correspond to the following aspects of the sample:

[0158] 0: No weathering. The scratched surface remains black.

[0159] 1: Slightly weathered.

[0160] 2: Moderately weathered.

[0161] 3: Completely weathered. The scratched surface appears white.

[0162] The lower the value, the more impressive the weathering will appear, that is, the weaker the weathering will be.

[0163] According to a preferred embodiment of the above-mentioned preferred embodiment, the total amount of antiozonant wax in the rubber composition according to the invention is less than or equal to 2.8 phr, preferably less than 2.8 phr, more preferably less than or equal to 2.6 phr, still more preferably less than 2.6 phr, in particular less than or equal to 2.4 phr, more particularly less than 2.4 phr, still more particularly less than or equal to 2.2 phr, advantageously less than 2.2 phr, more advantageously less than or equal to 2.0 phr, yet more advantageously less than 2.0 phr, in particular less than or equal to 1.8 phr, more particularly less than 1.8 phr, yet more particularly less than or equal to 1.6 phr, in particular less than 1.6 phr, more particularly less than or equal to 1.4 phr.

[0164] According to a preferred embodiment of the invention, the rubber composition according to the invention is also based on a crosslinking system.

[0165] According to a more preferred embodiment of the above-mentioned preferred embodiment, the cross-linking system of the rubber composition according to the present invention comprises a vulcanizing agent, the vulcanizing agent is preferably selected from sulphur, sulphur donors, peroxides, bismaleimides and corresponding combinations, more preferably selected from sulphur and corresponding combinations. Vulcanizing agent is referred to as "vulcanizing agent", "hardener" or "curing agent". According to an even more preferred embodiment of the above-mentioned preferred embodiment, the sulphur donor is an alkylphenol disulfide (abbreviated as "APDS"), more preferably p-(tert-butyl)phenol disulfide. According to an even more preferred embodiment of the above-mentioned preferred embodiment, the total amount of vulcanizing agent is greater than 0.5phr and less than 10phr, preferably greater than 0.5phr and less than 3phr.

[0166] According to a more preferred embodiment of the above preferred embodiment, the crosslinking system of the rubber composition according to the present invention comprises a vulcanization accelerator, which is preferably a primary vulcanization accelerator, more preferably selected from sulfenamide accelerators, thiazole accelerators, thiuram accelerators, dithiocarbamate accelerators, and corresponding combinations, and more preferably selected from sulfenamide accelerators and corresponding combinations. According to an even more preferred embodiment of the above preferred embodiment, the sulfenamide accelerator is selected from N-cyclohexyl-2-benzothiazole sulfenamide (abbreviated as CBS), N-(tert-butyl)-2-benzothiazole sulfenamide (abbreviated as TBBS), N-(tert-butyl)-2-benzothiazole sulfenimide (abbreviated as TBSI), N-oxydiethyl-2-benzothiazole sulfenamide (abbreviated as MBS), N,N'-dicyclohexyl-2-benzothiazole sulfenamide (abbreviated as DCBS), and corresponding combinations. According to an even more preferred embodiment of the above-mentioned more preferred embodiment, the thiazole accelerator is selected from 2-mercaptobenzothiazole (abbreviated as MBT), 2-mercaptobenzothiazole disulfide (abbreviated as MBTS), 2-mercaptobenzothiazole zinc (abbreviated as ZMBT), 2-(morpholinothio)benzothiazole (abbreviated as MDB), and corresponding combinations. According to an even more preferred embodiment of the above-mentioned more preferred embodiment, the thiuram accelerator is selected from tetramethylthiuram disulfide (abbreviated as TMTD), tetraethylthiuram disulfide (abbreviated as TETD), tetrabutylthiuram disulfide (abbreviated as TBTD), tetrakis(2-ethylhexyl)thiuram disulfide (abbreviated as TOT-N), tetramethylthiuram monosulfide (abbreviated as TMTM), dipentamethylenethiuram tetrasulfide (abbreviated as DPTT), tetrabenzylthiuram disulfide (abbreviated as TBzTD), and corresponding combinations. According to an even more preferred embodiment of the above more preferred embodiment, the dithiocarbamate accelerator is selected from zinc dimethyldithiocarbamate (abbreviated as ZDMC), zinc diethyldithiocarbamate (abbreviated as ZDEC), zinc dibutyldithiocarbamate (abbreviated as ZDBC), zinc ethylphenyldithiocarbamate (abbreviated as ZEPC), zinc dibenzyldithiocarbamate (abbreviated as ZDBzC), zinc N-pentamethylenedithiocarbamate (abbreviated as ZPDC) and corresponding combinations. According to an even more preferred embodiment of the above more preferred embodiment, the total amount of the vulcanization accelerator is greater than 0.5 phr and less than 5.0 phr.

[0167] According to a more preferred embodiment of the above preferred embodiment, the crosslinking system of the rubber composition according to the present invention comprises a vulcanization retarder, such as N-cyclohexylthiophthalimide (abbreviated as CTP).

[0168] According to a more preferred embodiment of the above-mentioned preferred embodiment, the cross-linking system of the rubber composition according to the present invention comprises a vulcanization activator, and the vulcanization activator is preferably selected from zinc oxide, fatty acid, fatty acid ester zinc, guanidine derivatives or corresponding combinations. According to an even more preferred embodiment of the above-mentioned preferred embodiment, the fatty acid is stearic acid, lauric acid, palmitic acid, oleic acid, naphthenic acid or corresponding combinations. According to an even more preferred embodiment of the above-mentioned preferred embodiment, the fatty acid ester zinc is zinc stearate, zinc laurate, zinc palmitate, zinc oleate, zinc naphthenic acid or corresponding combinations. According to an even more preferred embodiment of the above-mentioned preferred embodiment, the guanidine derivative is diphenylguanidine.

[0169] The fourteenth aspect of the present invention is a rubber composition according to any one of the first to thirteenth aspects, wherein the rubber composition is also based on a cross-linking system comprising a vulcanization activator, and the vulcanization activator includes a guanidine derivative; preferably, the total amount of guanidine derivatives is greater than 0.5 weight% and less than 5 weight% relative to 100 weight% of silica in the reinforcing filler.

[0170] The rubber composition according to the present invention may be used alone or mixed with any other rubber composition that can be used to manufacture rubber products (ie, as a mixture).

[0171] Obviously, the present invention relates to rubber compositions as described above in the unvulcanized or uncrosslinked state or in the raw state (ie, before vulcanization) and in the vulcanized or crosslinked or vulcanized state (ie, after crosslinking or vulcanization).

[0172] According to a preferred embodiment of the invention, the rubber composition according to the invention is also based on a crosslinking system comprising a vulcanizing agent, a vulcanization accelerator, a vulcanization retarder, a vulcanization activator or a corresponding combination, and the rubber composition according to the invention is manufactured in a mixer using two consecutive production stages: a first stage of thermomechanical processing or kneading at high temperature (called the "non-productive" stage), the maximum temperature of which is greater than 110°C and less than 200°C, preferably greater than 110°C and less than 190°C, more preferably greater than 130°C and less than 180°C, followed by a second stage of mechanical processing at a lower temperature of less than or equal to 110°C, preferably greater than 40°C and less than 100°C, more preferably greater than 60°C and less than 100°C, during which the vulcanizing agent, vulcanization accelerator and vulcanization retarder or a combination thereof of the crosslinking system are introduced. According to a more preferred embodiment of the above preferred embodiment, the vulcanization activator is introduced during the first non-productive stage, during the productive stage or during both stages, preferably during the first non-productive stage.

[0173] According to a more preferred embodiment of the preferred embodiment described above, the first stage (non-productive stage) is carried out in a plurality of thermomechanical stages: during the first stage, the elastomeric matrix, the reinforcing filler and the granulated rubber (and optionally the plasticizer, other ingredients or respective combinations, except the vulcanizing agent, vulcanization accelerator, vulcanization retardant or combinations thereof in the crosslinking system) are introduced in a plurality of thermomechanical stages into a mixer (preferably an internal mixer) at a temperature of greater than 20° C. and less than 100° C., preferably greater than 25° C. and less than 100° C.; after a few minutes (preferably 0.5 to 2 minutes) and the temperature rising to 90° C. or higher (preferably 100° C.), During the kneading process of 20 seconds to several minutes, the elastomer matrix, other ingredients and combinations thereof (that is, the remaining elastomer matrix, other ingredients and combinations thereof if not all are introduced into the mixer in the first stage (non-productive stage)), excluding the vulcanizing agent, vulcanization accelerator, vulcanization retarder or combinations thereof in the crosslinking system, are added all at once or in batches; wherein, in the first stage (non-productive stage), the total duration of kneading at a temperature of less than or equal to 190° C., preferably less than or equal to 180° C., more preferably less than or equal to 170° C., is preferably greater than 1 minute and less than 15 minutes, more preferably greater than 2 minutes and less than 10 minutes.

[0174] According to the above preferred embodiment or an even more preferred embodiment of the above more preferred embodiment, after cooling the mixture thus obtained, the vulcanizing agent, vulcanization accelerator, vulcanization retarder or a combination thereof in the crosslinking system is subsequently introduced into an open mixer (preferably an open mill) at a low temperature (preferably less than or equal to 100° C., more preferably less than or equal to 90° C.); then all substances are mixed in the second stage (production stage) for a few minutes, preferably greater than 2 minutes and less than 15 minutes, more preferably greater than 5 minutes and less than 15 minutes.

[0175] According to the preferred embodiment described above, the more preferred embodiment described above or a specific embodiment of the even more preferred embodiment described above, the rubber composition thus obtained using two consecutive preparation stages in a mixer is subsequently calendered, for example, into the form of sheets or plates (in particular for laboratory characterizations), or extruded into the form of shaped rubber elements that can be used directly as rubber products (for example tire sidewalls, tire treads, soles for footwear, conveyor belt coverings and track treads made of rubber).

[0176] According to the above preferred embodiment, the above more preferred embodiment, the above even more preferred embodiment or a more specific embodiment of the above specific embodiment, the crosslinking (or curing) is carried out in a known manner under pressure at a temperature of greater than 110° C. and less than 200° C., preferably greater than 130° C. and less than 190° C., for a sufficient time, which may be, for example, between 5 minutes and 90 minutes, depending in particular on the curing temperature, the crosslinking system employed, the crosslinking kinetics of the rubber composition under consideration or the dimensions of the rubber product.

[0177] According to a preferred embodiment of the present invention, the rubber composition is a rubber composition for rubber products in contact with ambient air, in particular a rubber composition for tires, articles of footwear, conveyor belts or crawler tracks made of rubber, more particularly a rubber composition for tire sidewalls, tire treads, soles of articles of footwear, conveyor belt covers or crawler track treads made of rubber, still more particularly a rubber composition for tire sidewalls.

[0178] The fifteenth aspect of the present invention is a rubber product comprising the rubber composition according to any one of the first to fourteenth aspects. Preferably, the rubber product includes a rubber component comprising the rubber composition according to any one of the first to fourteenth aspects. More preferably, the rubber product is a rubber tire, footwear, conveyor belt, or crawler track. More preferably, the rubber component is a rubber tire sidewall, tire tread, tire rim pad, footwear sole, conveyor belt cover, or crawler track tread. In particular, the rubber product is a tire comprising a rubber component, the rubber component being a tire sidewall comprising the rubber composition according to any one of the first to fourteenth aspects. The tire sidewall is one of the components of the tire and is intended to come into contact with the ambient air but not with the ground. The tread is one of the components of the tire and is intended to come into contact with both the ambient air and the ground. The tire rim pad is one of the components of the tire and is intended to come into contact with the tire rim and the ambient air but not with the ground. The conveyor belt is the conveying device of a belt conveyor system. The cover of a conveyor belt is one of the components of the conveyor belt (also called cover rubber or "rubber cover") and is intended to come into contact with the ambient air. A rubber track is a type of continuous track (also called a rubber track or rubber track belt or a rubber track intended to equip a tracked vehicle). The tread of a rubber track is one of the components of a rubber track and is intended to come into contact with the ambient air and the ground.

[0179] According to a preferred embodiment of the present invention, the tire comprises the rubber composition according to any one of the first to fourteenth aspects. Preferably, the tire includes a sidewall comprising the rubber composition according to any one of the first to fourteenth aspects.

[0180] The above tire of the present invention is particularly intended to equip passenger motor vehicles, including 4×4 (four-wheel drive) vehicles and SUV (Sports Utility Vehicle) vehicles, and industrial vehicles, in particular trucks and heavy utility vehicles (i.e. buses or heavy road transport vehicles (trucks, tractors, trailers)). DETAILED DESCRIPTION

[0181] The invention is further illustrated by the following non-limiting examples.

[0182] Example

[0183] To demonstrate the effects of the present invention, six rubber compositions (C1, C2, and C3: Examples according to the present invention, T1 and T2: Reference Examples, and T3: Comparative Example) were used. Each rubber composition was based on a diene elastomer (a combination of natural rubber (abbreviated as NR) and polybutadiene rubber (abbreviated as BR) as the elastomer matrix) reinforced with a combination of carbon black and silica (as reinforcing fillers), with or without granulated rubber. The formulation of each rubber composition is shown in Table 1, where the amount of each product is expressed in phr.

[0184] Each rubber composition was prepared as follows: reinforcing filler, elastomeric matrix, ozone-resistant wax, granular rubber, plasticizer and various other ingredients except sulfur (as vulcanizing agent) and N-cyclohexyl-2-benzothiazole sulfenamide (abbreviated as CBS) (as vulcanization accelerator) in the crosslinking system were introduced sequentially into an internal mixer having an initial container temperature of about 60° C.; thus, the mixer was filled with about 70% (volume %). Subsequently, thermomechanical processing was carried out in a single stage (non-productive stage) for a total duration of about 3 to 4 minutes until a maximum "discharge" temperature of 165° C. was reached. The mixture thus obtained was recovered and cooled, and then the vulcanizing agent and vulcanization accelerator of the crosslinking system were introduced into an open mixer (homogenizer) at a temperature of 20 to 30° C., mixing all the substances (productive stage) for an appropriate time (e.g., greater than 5 minutes and less than 12 minutes).

[0185] The rubber composition thus obtained is subsequently calendered into the form of a rubber sheet (having a thickness of 2 to 3 mm) or a rubber thin sheet for measuring its physical or mechanical properties, or calendered into a form that can be used directly as a shaped element, for example, as a tire semi-finished product after cutting, assembling, or cutting and assembling into the desired size.

[0186] The dynamic properties of the rubber composition (G': shear dynamic elastic modulus (or dynamic modulus), G": viscous shear modulus, tan δ: loss factor, G*: complex modulus) were measured on a test specimen bonded with the cured rubber composition using a VA4000 viscometer analyzer from Metravib. For example, the test specimen described in Figure X2.1 (circular shape) in the standard ASTM D 5992-96 (first adopted in 1996 and published in September 2006) was used. The diameter "d" of the test specimen was 10 mm (so its circular cross section was 78.5 mm). 2 ), the thickness "L" of each part of the rubber mixture is 2 mm, which gives a "d / L" ratio of 5 (different from the standard ISO 2856 mentioned in section X2.4 of the ASTM standard, which recommends a d / L value of 2). The response of a specimen of the vulcanized rubber composition subjected to a simple alternating sinusoidal shear load at a frequency of 10 Hz at a stable temperature of 23°C is recorded. The specimen is loaded symmetrically around its equilibrium position. The scan involves a strain amplitude from 0.1% to 50% (peak-to-peak: outward cycle; 12 measurement points) and then from 50% to 0.1% (peak-to-peak; return cycle; 11 measurement points). After each data acquisition, the shear dynamic elastic modulus (G') and the viscous shear modulus (G") on the return cycle and the loss factor (tan δ) corresponding to the G" / G' ratio are calculated. Similarly, the complex modulus (G*) is defined as the absolute value of the complex sum of the elastic modulus (G') and the viscous modulus (G"): G*=(G' 2 +G” 2 ) 0.5 .

[0187] Each G" value at a frequency of 10 Hz, a temperature stabilized at 23°C and a strain of 10% represents the hysteresis performance quality of each rubber composition, and in the case of a tire, conveyor belt or crawler made of rubber containing the rubber composition, it represents the rolling resistance performance quality.

[0188] The results (hysteresis performance quality) are expressed on a base of 100, i.e., a value of 100 is arbitrarily assigned to the reference example (T1), and then the values ​​of the examples according to the present invention (C1, C2, and C3), other reference examples (T2), and comparative examples (T3) are shown in Table 2. The values ​​corresponding to "G" (T1, 10 Hz, 23°C, 10%) / G" (X, 10 Hz, 23°C, 10%) x 100 were calculated, where X is C1, C2, C3, T1, T2, or T3. The higher the value, the lower the hysteresis loss, which means the better the hysteresis performance quality.

[0189] To test the processability, each sample made of the rubber composition was subjected to a temperature condition of 90°C in a barrel, a capillary die having a diameter of 1 mm, a capillary die length of 10 mm and a shear rate of 80 s. -1 In the case of , extrusion was performed according to method A (capillary die matrix) in standard ISO 11443:2014, and the matrix expansion degree was calculated using "extrudate diameter / capillary die diameter".

[0190] The results (processability) are expressed on a base of 100, i.e., a value of 100 is arbitrarily assigned to the reference example (T2). The values ​​for the examples according to the present invention (C1, C2, and C3), other reference examples (T1), and comparative examples (T3) are shown in Table 2. The values ​​corresponding to the degree of matrix expansion (T2, 10 Hz, 23°C) / the degree of matrix expansion (X, 10 Hz, 23°C) × 100 were calculated, where X is C1, C2, C3, T1, T2, or T3. The higher the value, the lower the degree of matrix expansion, which means better processability.

[0191] The results in Table 2 show that the examples according to the present invention (C1, C2 and C3) have a better balance between hysteresis performance quality and processability than the reference and comparative examples (T1, T2 and T3).

[0192] In summary, the rubber composition according to the invention surprisingly enables an improved balance between hysteresis performance qualities and processability.

[0193] [Table 1]

[0194]

[0195]

[0196] (1) Natural rubber;

[0197] (2) Nd butadiene rubber;

[0198] (3) Carbon black (ASTM N234 grade from Cabot, BET (according to standard ASTM D6556-10): 119 m 2 / g, COAN (according to standard ASTM D3493-16): 102 ml / 100 g);

[0199] (4) Silicon dioxide (from Evonik 7000GR);

[0200] (5) Crumb rubber (Polydyne 80 from Lehigh Technologies);

[0201] (6) Oleic sunflower oil (Lubrirob Tod 1880 from Novance);

[0202] (7) Silane coupling agent TESPT (Si69 from Evonik);

[0203] (8) a combination of two antioxidants ((N-(1,3-dimethylbutyl)-N-phenyl-p-phenylenediamine (Santoflex 6-PPD from Flexsys) and 2,2,4-trimethyl-1,2-dihydroquinolone (TMQ from Lanxess));

[0204] (9) Anti-ozon wax (Varazon 4959 from Sasol);

[0205] (10) diphenylguanidine (Perkacit DPG from Flexsys);

[0206] (11) stearic acid (Pristerene 4931 from Uniqema);

[0207] (12) Zinc oxide (technical grade, from Umicore);

[0208] (13) N-cyclohexyl-2-phenylthiazolesulfenamide (Santocure CBS from Flexsys).

[0209] [Table 2]

[0210]

Claims

1. A rubber composition, said rubber composition being based at least on: - an elastomeric matrix; - reinforcing fillers; and - granular rubber; The total amount of the reinforcing filler is less than 50 phr; The reinforcing filler comprises at least one carbon black and at least one silica; and The total amount of carbon black in phr is less than the total amount of silica. 2 . The rubber composition according to claim 1 , wherein the elastomeric matrix comprises at least one elastomer selected from the group consisting of isoprene elastomers and butadiene elastomers.

3. The rubber composition according to claim 1 or claim 2, wherein the elastomeric matrix comprises at least one isoprene elastomer, preferably the total amount of isoprene elastomer is greater than 30 phr and less than 70 phr. 4 . The rubber composition according to claim 1 , wherein the elastomeric matrix comprises at least one butadiene elastomer, preferably in a total amount greater than 30 phr and less than 70 phr.

5. The rubber composition according to claim 1 , wherein the elastomeric matrix comprises at least one isoprene elastomer and at least one butadiene elastomer, preferably the total amount of isoprene elastomer being greater than 30 phr and less than 70 phr, and the total amount of butadiene elastomer being greater than 30 phr and less than 70 phr. 6 . The rubber composition according to claim 1 , wherein the total amount of reinforcing fillers is greater than 5 phr. 7 . The rubber composition according to claim 1 , wherein the total amount of carbon black in the reinforcing filler is greater than 0 phr and less than 20 phr. 8 . The rubber composition according to claim 1 , wherein the total amount of silica in the reinforcing filler is greater than 20 phr and less than 50 phr. 9 . The rubber composition according to claim 1 , wherein the total amount of the crumb rubber is greater than 0 phr and less than 50 phr.

10. The rubber composition according to any one of claims 1 to 9, the total amount of crumb rubber in phr being greater than the total amount of carbon black, and the total amount of crumb rubber in phr being less than the total amount of silica.

11. The rubber composition according to any one of claims 1 to 10, wherein the crumb rubber does not contain any crumb rubber particles retained on a 40-mesh sieve, or the crumb rubber contains crumb rubber particles retained on a 40-mesh sieve, and the total amount of crumb rubber particles retained on the 40-mesh sieve is less than 10% by weight relative to 100% by weight of the crumb rubber.

12. The rubber composition according to any one of claims 1 to 11, the crumb rubber not having been subjected to any modification by a treatment selected from the group consisting of thermal treatment, mechanical treatment, biological treatment, chemical treatment and respective combinations.

13. The rubber composition according to any one of claims 1 to 12, further based on an ozone-resistant wax.

14. Rubber composition according to any one of claims 1 to 13, further based on a crosslinking system comprising a vulcanization activator containing a guanidine derivative, preferably in a total amount greater than 0.5% by weight relative to 100% by weight of silica in the reinforcing filler.

15. A rubber product comprising the rubber composition according to any one of claims 1 to 14, preferably comprising a rubber component comprising the rubber composition according to any one of claims 1 to 14, more preferably, the rubber product is a tire, an article of footwear, a conveyor belt or a crawler track made of rubber, still more preferably, the rubber component is a tire sidewall, a tire tread, a tire rim pad, a sole of an article of footwear, a conveyor belt cover or a crawler track tread made of rubber, in particular, the rubber product is a tire comprising a rubber component, the rubber component being a tire sidewall comprising the rubber composition according to any one of claims 1 to 14.

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