rubber composition

Abstract

A rubber composition that enables an unexpectedly improved balance between hysteresis and processing performance quality is based on at least an elastomer matrix, a reinforcing filler, and a clam rubber, wherein the total amount of the reinforcing filler is less than 50 phr, and the reinforcing filler contains at least one type of carbon black and at least one type of silica, and the total amount of carbon black in phr units is less than the total amount of silica in phr units.

Description

[Technical Field]

[0001] The field of the present invention is rubber compositions, more specifically rubber compositions for rubber products, more specifically rubber compositions for rubber products that come into contact with the ambient air, and even more specifically rubber compositions for tires, footwear, rubber conveyor belts, or rubber crawlers, more specifically rubber compositions for tires, and even more specifically rubber compositions for tire sidewalls. [Background technology]

[0002] Generally, rubber compositions such as tires require multiple desirable properties for optimal performance. However, it is known that these properties, such as hysteresis and processability, are mutually exclusive. International Patent Application No. 2006 / 052035, a patent document, discloses a novel vinyl-cis-polybutadiene rubber composition for sidewalls, in which the matrix exhibits low swelling and excellent extrudeability, and can improve fuel efficiency. [Overview of the project]

[0003] The current objective of rubber product manufacturers is to improve the balance between hysteresis performance quality and processability. In the course of these research activities, the inventors discovered that a specific rubber composition intended for rubber products, more specifically for tires, footwear, conveyor belts, or rubber tracks, and even more specifically for tire sidewalls, enables an unexpectedly improved balance between hysteresis performance quality and processability. [Modes for carrying out the invention]

[0004] The expression "based on" or "composition based on" should be understood to mean a composition comprising a mixture of each of the base components used, the product of an in-situ reaction, or both thereof, wherein some of these components are at least partially reactive, intended to react, or intended to react and react with each other during each phase of the composition's manufacture or during subsequent curing, while modifying the composition as prepared at the start. Thus, the compositions used in the present invention may differ in their non-crosslinked and crosslinked (vulcanized) states. The term "phr" refers to parts by mass per 100 parts of elastomer in the context of the preparation of the composition before curing. In other words, if crumb rubber is present, the term "phr" refers to parts by mass per 100 parts of "new" elastomer, so the elastomer contained in the crumb rubber is excluded from the base 100. In this specification, unless otherwise explicitly stated, all percentages (%) expressed are mass percentages (mass%). The expression "elastomer matrix" is understood to mean all elastomers present in the rubber composition within a given composition. In this specification, unless otherwise explicitly stated, each TgDSC (glass transition temperature) is measured by a known method using DSC (differential scanning calorimetry) in accordance with standard ASTM D3418-08. Any numerical interval expressed as "between a and b" indicates a range of numbers greater than "a" and less than "b" (in other words, the limiting values ​​a and b are excluded), while any numerical interval expressed as "a to b" means a range of numbers from "a" to "b" (in other words, the strict limiting values ​​a and b are included). When referring to a “main” compound, in the sense of the present invention, this means that the compound is dominant among the compounds of its kind in the composition, in other words, it occupies the largest mass among the compounds of its kind, preferably more than 50% by mass, and more preferably more than 75% by mass. Thus, for example, the main polymer is the polymer that occupies the largest mass relative to the total mass of polymers in the composition. Similarly, the “main” filler is the one that occupies the largest mass among the fillers in the composition. For example, in a system containing only one polymer, the latter is dominant in the sense of “main” in the present invention, and in a system containing two polymers, the main polymer occupies more than half the mass of the polymers. Conversely, a “minor” compound is a compound that does not occupy the largest mass fraction among the compounds of its kind.

[0005] In the sense of the present invention, when referring to a “main” unit (or monomer) in a compound (or polymer) of the same type, it means that this unit (or monomer) is dominant among the units (or monomers) that form the compound (or polymer), in other words, that it occupies the largest mass fraction among the units (or monomers) that form the compound (or polymer). Thus, for example, a resin composed mainly of units derived from C5 monomers is a resin in which C5 units occupy the largest mass among all the units that constitute the resin. In other words, the “main” monomer or aggregate of “main” monomers is the monomer (or aggregate of monomers) that occupies the largest mass fraction in the polymer. Conversely, a “minor” monomer is a monomer that does not occupy the largest mole fraction of the polymer. The compounds referred to herein may be of fossil origin or bio-based origin. In the latter case, they may be partially or completely derived from biomass, or obtained from renewable starting materials derived from biomass. Polymers, plasticizers, fillers, and others are particularly relevant.

[0006] A first aspect of the present invention is a rubber composition based on at least an elastomer matrix, a reinforcing filler, and a clam rubber, wherein the total amount of the reinforcing filler is less than 50 phr, and the reinforcing filler contains at least one type of carbon black and at least one type of silica, and the total amount of carbon black is less than the total amount of silica. Certain rubber compositions enable an unexpectedly improved balance between hysteresis performance quality and processability. The following embodiments, examples, and alternative forms, including preferred ranges, materials, or each or both, may apply to any one of the other embodiments, other examples, other alternative forms of the present invention unless expressly indicated.

[0007] The rubber composition according to the present invention is based on an elastomer matrix. As is commonly practiced, the terms "elastomer" and "rubber" are interchangeable and are used interchangeably in this specification. A “diene” elastomer (or more conventionally, “rubber,” the two terms being considered synonyms) is, as is well known, understood to mean one (or more) elastomers obtained, at least partially (in other words, homopolymers or copolymers), from a diene monomer (a monomer having two conjugated or unconjugated carbon-carbon double bonds).

[0008] These diene elastomers can be classified into two categories: "substantially unsaturated" or "substantially saturated." Generally, the expression "substantially unsaturated" is understood to mean a diene elastomer obtained from a conjugated diene monomer in which the content of diene-derived (conjugated diene) units is at least partially greater than 15% (mol%). Therefore, diene elastomers such as butyl rubber or EPDM-based diene / α-olefin copolymers do not meet the definition described above and are sometimes specifically described as "substantially saturated" diene elastomers (in which the content of diene-derived units is low or very low, always less than 15%). In the category of "substantially unsaturated" diene elastomers, "highly unsaturated" diene elastomers are specifically understood to mean a diene elastomer in which the content of diene-derived (conjugated diene) units is greater than 50%. Although it applies to all types of diene elastomers, it is preferable to use it for substantially unsaturated diene elastomers.

[0009] In terms of these definitions, the expression "diene elastomer that can be used in the composition according to the present invention," specifically: - (a) Any homopolymer obtained by polymerizing conjugated diene monomers, preferably having 4 to 12 carbon atoms; - (b) Any copolymer obtained by copolymerizing one or more conjugated dienes with each other, or by copolymerizing one or more vinyl aromatic compounds having 8 to 20 carbon atoms. It is understood to mean... The following compounds: 1,3-butadiene, 2-methyl-1,3-butadiene, for example, 2,3-dimethyl-1,3-butadiene, 2,3-diethyl-1,3-butadiene and the like, 2,3-di(C1-C5 alkyl)-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 are particularly suitable as conjugated dienes. The following vinyl aromatic compounds, for example, styrene, ortho-methylstyrene, meta-methylstyrene or para-methylstyrene, commercially available "vinyl toluene" mixture, para-(tert-butyl)styrene, methoxystyrene, chlorostyrene, vinyl mesitylene, divinylbenzene or vinyl naphthalene are suitable.

[0010] A second aspect of the present invention is a rubber composition according to the first aspect, wherein the elastomer matrix comprises at least one elastomer selected from the group consisting of isoprene elastomers and butadiene elastomers. A third aspect of the present invention is a rubber composition according to the first or second aspect, wherein the elastomer matrix comprises at least one isoprene elastomer, preferably the total amount of isoprene elastomers is more than 30 phr and less than 70 phr. "Isoprene elastomer" is understood to mean all elastomers mainly composed of isoprene monomer.

[0011] According to a preferred embodiment of the second aspect or a preferred embodiment of the third aspect, the isoprene elastomer is selected from the group consisting of isoprene polymers, isoprene copolymers and similar combinations. 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 similar combinations. According to an even more preferred embodiment of the above-described more preferred embodiment, the isoprene content of the butadiene-isoprene copolymer (BIR) is greater than 50% by mass and less than 90% by mass per 100% by mass of the butadiene-isoprene copolymer (BIR). According to an even more preferred embodiment of the above more preferred embodiment, the TgDSC of the butadiene-isoprene copolymer (BIR) is -80°C to -40°C.

[0012] According to an even more preferred embodiment of the above-described more preferred embodiment, the styrene content of the styrene-isoprene copolymer (SIR) is greater than 5% by mass and less than 50% by mass per 100% by mass of the styrene-isoprene copolymer (SIR). According to an even more preferred embodiment of the above-described more preferred embodiment, the TgDSC of the styrene-isoprene copolymer (SIR) is greater than -50°C and less than -25°C.

[0013] According to an even more preferred embodiment of the above-described more preferred embodiment, the isoprene content of the styrene-butadiene-isoprene copolymer (SBIR) is greater than the content of styrene and butadiene. According to an even more preferred embodiment of the above-described more preferred embodiment, the isoprene content of the styrene-butadiene-isoprene copolymer (SBIR) is greater than 50% by mass and less than 60% by mass per 100% by mass of the styrene-butadiene-isoprene copolymer (SBIR). According to a preferred embodiment of the second or third embodiment, the isoprene elastomer is selected from the group consisting of natural rubber, synthetic polyisoprene, and combinations thereof, and preferably the isoprene elastomer is made of natural rubber. According to a more preferred embodiment of the preferred embodiment, the synthetic polyisoprene is synthetic polyisoprene, preferably having a cis-1,4-bond content (mol%) of more than 90%, more preferably more than 95%, and even more preferably more than 98%.

[0014] A fourth aspect of the present invention is a rubber composition according to any one of the first to third aspects, wherein the elastomer matrix comprises at least one butadiene elastomer, preferably the total amount of butadiene elastomers being greater than 30 phr and less than 70 phr. "Butadiene elastomer" is understood to refer to all elastomers that are primarily composed of butadiene monomers. According to a preferred embodiment of the second or fourth embodiment, the butadiene elastomer is selected from the group consisting of butadiene polymers, butadiene copolymers and similar combinations, and is preferably selected from the group consisting of polybutadiene (BR), styrene-butadiene copolymer (SBR) and similar combinations. In a more preferred embodiment, the butadiene elastomer is selected from the group consisting of polybutadiene (BR) and similar combinations.

[0015] According to an even more preferred embodiment of the above more preferred embodiment, the content (mol%) of 1,2-units of polybutadiene is greater than 4% and less than 80%. According to an even more preferred embodiment of the above-described more preferred embodiment, the cis-1,4- content (mol%) of polybutadiene is greater than 80%. 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 similar combinations. According to a more preferred embodiment of the above-described more preferred embodiment, the butadiene copolymer is selected from the group consisting of styrene-butadiene copolymer (SBR) and similar combinations.

[0016] According to specific embodiments of the more preferred embodiments described above, 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, even more preferably greater than -70°C and less than 0°C, and particularly greater than -60°C and less than -10°C. According to a specific embodiment of the more preferred embodiment described above, the styrene content of the styrene-butadiene copolymer (SBR) is more than 5% by mass and less than 60% by mass per 100% by mass of styrene-butadiene copolymer (SBR), more specifically more than 20% by mass and less than 50% by mass. According to a particular embodiment of the more preferred embodiment described above, the content (mol%) of 1,2-bonds in the butadiene portion of the styrene-butadiene copolymer (SBR) is greater than 4% and less than 75%, and the content (mol%) of trans-1,4-bonds is greater than 10% and less than 80%.

[0017] According to a more preferred embodiment of the above-described more preferred embodiment, the butadiene copolymer is selected from the group consisting of butadiene-isoprene copolymers (BIRs) and similar combinations. According to a specific preferred embodiment of the more preferred embodiment described above, the isoprene content of the butadiene-isoprene copolymer (BIR) is greater than 5% by mass and less than 50% by mass per 100% by mass of butadiene-isoprene copolymer (BIR). According to specific embodiments of the more preferred embodiments described above, the TgDSC of the butadiene-isoprene copolymer (BIR) is in the range of -80°C to -40°C. According to a more preferred embodiment of the above-described more preferred embodiment, the butadiene copolymer is selected from the group consisting of styrene-butadiene-isoprene copolymer (SBIR) and similar combinations. The butadiene content of the styrene-butadiene-isoprene copolymer (SBIR) is greater than the content of styrene and isoprene.

[0018] A fifth aspect of the present invention is a rubber composition according to any one of the first to fourth aspects, wherein the elastomer matrix comprises at least one isoprene elastomer and at least one butadiene elastomer, preferably the total amount of isoprene elastomers being greater than 30 phr and less than 70 phr, and the total amount of butadiene elastomers being greater than 30 phr and less than 70 phr. According to the preferred embodiment of the third aspect or the preferred embodiment of the fifth aspect, the total amount of isoprene elastomer is 65 phr or less, preferably less than 65 phr, more preferably 60 phr or less, even more preferably less than 60 phr, particularly 55 phr or less, and more specifically less than 55 phr. According to the preferred embodiment of the third aspect or the preferred embodiment of the fifth aspect, the total amount of isoprene elastomer is 35 phr or more, preferably more than 35 phr, more preferably 40 phr or more, even more preferably more than 40 phr, particularly 45 phr or more, and more specifically more than 45 phr.

[0019] According to the preferred embodiment of the fourth or fifth embodiment, the total amount of butadiene elastomer is 65 phr or less, preferably less than 65 phr, more preferably 60 phr or less, even more preferably less than 60 phr, particularly 55 phr or less, and more specifically less than 55 phr. According to the preferred embodiment of the fourth aspect or the preferred embodiment of the fifth aspect, the total amount of butadiene elastomer is 35 phr or more, preferably more than 35 phr, more preferably 40 phr or more, even more preferably more than 40 phr, particularly 45 phr or more, and more specifically more than 45 phr. According to a preferred embodiment of the present invention, the elastomer matrix in the rubber composition according to the present invention consists of an isoprene elastomer and a butadiene elastomer. According to another preferred embodiment of the present invention, the elastomer matrix in the rubber composition according to the present invention comprises another elastomer or an elastomer other than isoprene elastomer and butadiene elastomer.

[0020] Any elastomer known to those skilled in the art that is not defined above as isoprene elastomer or butadiene elastomer may also be used. The rubber composition according to the present invention is based on a reinforcing filler, and the total amount of the reinforcing filler is less than 50 phr, preferably 45 phr or less, more preferably less than 45 phr, even more preferably 40 phr or less, and particularly less than 40 phr. A 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 fillers is greater than 5 phr, preferably 10 phr or more, more preferably greater than 10 phr, even more preferably greater than 15 phr or more, particularly greater than 15 phr, more specifically greater than 20 phr or more, even more specifically greater than 20 phr, advantageously greater than 25 phr or more, more advantageously greater than 25 phr, even more advantageously greater than 30 phr or more, specifically greater than 30 phr, more specifically greater than 35 phr or more, even more specifically greater than 35 phr.

[0021] All kinds of reinforcing fillers known to have the ability to reinforce rubber compositions usable in the manufacture of rubber products, such as organic reinforcing fillers, such as at least one type of carbon black, or inorganic reinforcing fillers, such as silica (SiO2), alumina (Al2O3), or a combination thereof, can be used, in which at least one coupling agent is combined in a known manner. The reinforcing filler in the rubber composition according to the present invention contains at least one type of carbon black. A seventh aspect of the present invention is a rubber composition according to any one of the first to sixth aspects, wherein the total amount of carbon black in the reinforcing filler is greater than 0 phr, preferably 1 phr or more, more preferably greater than 1 phr, even more preferably 2 phr or more, specifically greater than 2 phr, and more specifically 3 phr or more, and the total amount of carbon black in the reinforcing filler is less than 20 phr, preferably 15 phr or less, more preferably less than 15 phr, even more preferably 10 phr or less, specifically less than 10 phr, more specifically 5 phr, and even more specifically less than 5 phr.

[0022] The mass fraction of carbon black can be measured by thermal mass spectrometry (TGA) according to standard NF T-46-07 using a Mettler Toledo Model TGA / DSC1 instrument. Approximately 20 g of sample can be introduced into the thermal analyzer and subjected to a thermal program in an inert atmosphere at 25°C to 600°C (thermal decomposition phase), followed by an oxidizing atmosphere at 400°C to 750°C (oxidation phase). The sample mass can be measured continuously throughout the thermal program. The organic matter content can correspond to the mass loss measured during the thermal decomposition phase relative to the initial mass of the sample. The amount of carbon black can correspond to the mass loss measured during the oxidation phase relative to the initial mass of the sample. Suitable carbon blacks include all types of carbon black, particularly SAF, ISAF, HAF, FEF, GPF, HMF, SRF, and SRF series blacks, as well as reinforced carbon blacks that have been used in tires ("tire quality" blacks), such as ASTM grade 100, 200, or 300 series (e.g., N115, N134, N234, N326, N330, N339, N347, or N375 blacks), or high-grade carbon blacks, such as ASTM grade 500, 600, 700, 800, or 900 series (e.g., N550, N660, N683, N772, N774, N880, N990, N991 blacks).

[0023] According to a preferred embodiment of the present invention, carbon black is 80m 2 / g or more (for example, 80-160m) 2 (between / g), preferably 90m 2 / g or more (for example, 90-150m) 2 (between / g), comfortable 100m 2 / g or more (for example, 100-140m) 2 (between / g), even more comfortably 110m 2 / g or more (for example, 110-130m) 2The BET specific surface area (in accordance with standard ASTM D6556-10) during (between) / g is shown. According to a preferred embodiment of the present invention, the carbon black has a compression sample oil absorption value (COAN: Compression Oil Absorption Value) (in accordance with standard ASTM D3493-16) of more than 90 ml / 100 g (for example, between 90 and 120 ml / 100 g), preferably more than 95 ml / 100 g (for example, between 95 and 115 ml / 100 g), more preferably more than 100 ml / 100 g (for example, between 100 and 110 ml / 100 g).

[0024] The reinforcing filler in the rubber composition according to the present invention contains at least one kind of silica. The eighth aspect of the present invention is that the total amount of silica in the reinforcing filler is more than 20 phr, preferably 25 phr or more, more preferably more than 25 phr, even more preferably 30 phr or more, particularly more than 30 phr, and the total amount of silica in the reinforcing filler is less than 50 phr, preferably 45 phr or less, more preferably less than 45 phr, even more preferably 40 phr or less, particularly less than 40 phr, more specifically 35 phr or less, even more specifically less than 35 phr, and it is a rubber composition according to any one of the first to seventh aspects.

[0025] According to a preferred embodiment of the present invention, the silica is any reinforcing silica, specifically, both the BET specific surface area and the CTAB specific surface area are less than 450 m 2 / g, preferably 20 to 400 m 2 / g, more preferably 50 to 350 m 2 / g, even more preferably 100 to 300 m 2 / g, particularly 150 to 250 m 2This refers to any precipitated silica or fumed silica between / g. The BET specific surface area can be measured by gas adsorption according to a known method, in other words, according to the Brunauer-Emmett-Teller method described in the Journal of the American Chemical Society, Vol. 60, page 309, February 1938, more specifically by gas adsorption according to the French standard NF ISO9277 December 1996 (multipoint (5 points) volumetric method; here gas: nitrogen, degassing: 160°C for 1 hour, relative pressure p / p0 range: 0.05~0.17). The CTAB specific surface area can be measured according to the French standard NF T45-007 November 1987 (Method B).

[0026] According to a preferred embodiment of the present invention, the silica is formed in particles with a mass-average diameter of less than 1000 nm, preferably less than 500 nm, more preferably less than 200 nm, and even more preferably between 20 nm and 200 nm. The mass-average diameter can be measured by a known method after dispersion of the analytical packing material by ultrasonic deagglomeration in water (or an aqueous solution containing a surfactant) according to the following procedure, using an XDC (X-ray disk centrifuge) type centrifuge with X-ray detection, for example, sold by Brookhaven Instruments: a 3.2 g sample of the analytical inorganic packing material is suspended in 40 ml of water by operating a 1500 W ultrasonic probe (Vibracell 3 / 4 inch high-frequency device sold by Bioblock) at 60% power (60% of the highest "power control") for 8 minutes; after sonication, 15 ml of the suspension is introduced into a rotary disk; after 120 minutes of sedimentation, the mass distribution of particle size and the mass-average diameter dw of the particles are calculated using the software of the XDC sedimentation machine. The total content of carbon black in phr units in the reinforcing filler of the rubber composition according to the present invention is less than the total content of silica in phr units.

[0027] 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 mass, preferably less than 80% by mass, more preferably less than 70% by mass, even more preferably less than 60% by mass, particularly less than 50% by mass, more specifically less than 40% by mass, even more specifically less than 30% by mass, advantageously less than 20% by mass, and more advantageously less than 10% by mass. According to a preferred embodiment of the present invention, the rubber composition according to the present invention is based on a silane coupling agent. Silane coupling agents are intended to provide sufficient chemical bonding, sufficient physical bonding, or both between silica and an elastomer matrix. Silane coupling agents are defined as being at least bifunctional, but the simplified general formula "YAX" is... (In the formula, - Y can form physical bonds, chemical bonds, or both with silica. For example, it represents a functional group ("Y" functional group) that can form a bond between the silicon atom of a silane coupling agent and the surface silanol group of silica. - X represents a functional group ("X" functional group) that can form physical bonds, chemical bonds, or both with the elastomer matrix, for example, via a sulfur atom. - A represents a divalent group that enables the linkage between Y and X. It holds.

[0028] While difunctional organosilanes or polyorganosiloxanes are commonly used, they are generally silane polysulfides, referred to as "symmetrical" or "asymmetrical" depending on their specific structure, as described in a great deal of patent literature (see, for example, International Patent Application No. 03 / 002648, International Patent Application No. 03 / 002649, or International Patent Application No. 2004 / 033548).

[0029] The most widely used reminder is the following general formula (I): Z AS x -AZ(I) (In the formula, - x is an integer between 2 and 8 (preferably between 2 and 5), - A is a divalent hydrocarbon group, preferably C1-C 18 Alkylene group or C6-C 12 Arylene group, more specifically C1-C 10 Alkylenes, especially C1-C4 alkylenes, and especially propylene, are - Z is given by the following formula: [ka] (In the formula, - R a The groups are substituted or non-substituted, identical or different from each other, C1-C 18 Alkyl, C5-C 18 Cycloalkyl or C6-C 18 Represents an aryl group (preferably a C1-C6 alkyl, cyclohexyl, or phenyl group, specifically a C1-C4 alkyl group, more specifically a methyl, ethyl, or both group), - R b The groups are substituted or non-substituted, identical or different from each other, C1-C 18 Alkoxyl or C5-C 18 Representing a cycloalkoxyl group (preferably a group selected from C1-C8 alkoxyl and C5-C8 cycloalkoxyl, more preferably a group selected from C1-C4 alkoxyl, particularly methoxyl and ethoxyl), and particularly preferred, but not limited to the above definition. (corresponds to one of the following) This is the corresponding "symmetric" silane polysulfide.

[0030] In the case of a mixture of alkoxysilane polysulfides corresponding to the above formula (I), particularly in commonly available commercially, the average value of the "x" exponent is preferably between 2 and 5, more preferably a decimal of about 4. However, the present invention may also be advantageous to be carried out with, for example, alkoxysilane disulfide (x=2). More specifically, silane polysulfides, bis((C1-C4)alkoxyl(C1-C4)alkylsilyl(C1-C4)alkyl) polysulfides (especially disulfides, trisulfides, or tetrasulfides), such as bis(3-trimethoxysilylpropyl) or bis(3-triethoxysilylpropyl) polysulfide, may be mentioned as examples. Among these compounds, bis(3-triethoxysilylpropyl)tetrasulfide, abbreviated as TESPT and having the formula [(C2H5O)3Si(CH2)3S2]2, or bis(3-triethoxysilylpropyl)disulfide, abbreviated as TESPD and having the formula [(C2H5O)3Si(CH2)3S]2, are particularly used. Furthermore, preferred examples described in the patent application, International Patent Application No. 02 / 083782 (or U.S. Patent No. 7217751), include bis(mono(C1-C4)alkoxydi(C1-C4)alkylsilylpropyl) polysulfides (particularly disulfides, trisulfides, or tetrasulfides), and more specifically, bis(monoethoxydimethylsilylpropyl)tetrasulfide.

[0031] In particular, as coupling agents other than alkoxysilane polysulfides, for example, difunctional POS (polyorganosiloxane) or hydroxysilane polysulfide (Rb=OH in formula (I) above) described in the patent applications International Patent Application No. 02 / 30939 (or U.S. Patent No. 6,774,255) and International Patent Application No. 02 / 31041 (or U.S. Patent Application No. 2004 / 051210), or silanes or POS having an azodicarbonyl functional group described in, for example, the patent applications International Patent Application No. 2006 / 125532, International Patent Application No. 2006 / 125533 and International Patent Application No. 2006 / 125534, etc., may be mentioned.

[0032] Other examples of silane sulfides include, for example, silanes having at least one thiol (-SH) functional group (also called mercaptosilanes), silanes with at least one thiol functional group masked, or both, as described in U.S. Patent No. 6,849,754, International Patent Application No. 99 / 09036, International Patent Application No. 2006 / 023815, International Patent Application No. 2007 / 098080, International Patent Application No. 2008 / 055986, and International Patent Application No. 2010 / 072685, etc.

[0033] Naturally, as specifically described in the aforementioned patent application, International Patent Application No. 2006 / 125534, a mixture of the silane-based coupling agents can also be used. In a more preferred embodiment, the amount of silane coupling agent in the rubber composition according to the present invention is between 5% and 20% by mass per 100% by mass of silica. According to a preferred embodiment of the present invention, the amount of the silane coupling agent is between 1 and 10 phr, preferably between 1 and 5 phr. The rubber composition according to the present invention is based on clam rubber (hereinafter abbreviated as "clam" in this specification).

[0034] 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 clam rubber is greater than 0 phr, preferably 1 phr or more, more preferably greater than 1 phr, even more preferably greater than 2 phr or more, specifically greater than 2 phr, more specifically greater than 3 phr or more, and even more specifically greater than 3 phr, and the total amount of clam rubber is less than 50 phr, preferably 40 phr or less, more preferably less than 40 phr, even more preferably less than 30 phr or less, particularly less than 30 phr, more specifically less than 20 phr, advantageously less than 15 phr, more advantageously less than 15 phr, and even more advantageously less than 10 phr, specifically less than 10 phr. A tenth aspect of the present invention is a rubber composition according to any one of the first to ninth aspects, wherein the total amount of clam rubber in phr units is greater than the total amount of carbon black in phr units, and the total amount of clam rubber in phr units is less than the total amount of silica in phr units.

[0035] Clam rubber is a finely granulated, optionally converted rubber sheet. Typically, clam rubber is derived from the crushing or pulverization of vulcanized rubber compositions that have already been used for their initial applications, such as tires, and is a recycled material product. Clam rubber can be obtained by grinding worn tires or other rubber into fine particles from which reinforcing materials, such as steel or fiber, and any other contaminants, such as dust, glass, or rock, have been removed. The book "Rubber Chemistry and Technology" discloses numerous methods for grinding vulcanized rubber or crosslinked rubber to obtain clam rubber. According to a preferred embodiment of the present invention, the clam rubber is produced from a worn tire.

[0036] According to a preferred embodiment of the present invention, the clam rubber is in the form of fine particles. The term "microparticles" is understood to mean particles that have size, i.e., their diameter if they are spherical, or their maximum dimension if they are asymmetrical, which is several microns, tens of microns, or hundreds of microns. An eleventh aspect of the present invention is a rubber composition according to any one of the first to tenth aspects, wherein the clam rubber does not contain clam rubber particles remaining on a 40-mesh screen, or the clam rubber contains clam rubber particles remaining on a 40-mesh screen, and the total amount of clam rubber particles remaining on the 40-mesh screen is less than 10% by mass per 100% by mass of clam rubber, preferably the clam rubber does not contain clam rubber particles remaining on a 60-mesh screen, or the clam rubber contains clam rubber particles remaining on a 60-mesh screen, and the total amount of clam rubber particles remaining on the 60-mesh screen is less than 10% by mass per 100% by mass of clam rubber, and more preferably the clam rubber does not contain clam rubber particles remaining on an 80-mesh screen, or the clam rubber contains clam rubber particles remaining on an 80-mesh screen, and the total amount of clam rubber particles remaining on the 80-mesh screen is less than 10% by mass per 100% by mass of clam rubber.

[0037] The total amount of clam rubber particles remaining on the 40-mesh screen is less than 10% by mass per 100% by mass of clam rubber, which means that more than 90% by mass of clam rubber particles per 100% by mass of clam rubber can pass through the 40-mesh screen. The total mass of crumb rubber particles in the crumb rubber of the rubber composition according to the present invention can be obtained from the particle size distribution of the crumbs measured in accordance with the standard ASTM-D5644-01. In another form, the particle size distribution of crambs, in other words, the mass distribution of cramb particles, can be measured by laser particle size analysis using a Malvern Mastersizer 3000 instrument. The measurement can be performed via a liquid route, which involves pretreatment with ultrasound for one minute followed by dilution with alcohol to ensure particle dispersion. The measurement can be performed according to standard ISO-13320-1, and in particular, it may be possible to measure D10 and D50, in other words, particles smaller than the average diameter that may constitute 10% and 50% by mass of the entire group of particles, respectively.

[0038] According to a preferred embodiment of the present invention, the clam rubber in the rubber composition according to the present invention is mechanically processed, or processed under cryogenic conditions, or processed mechanically and under cryogenic conditions, in other words, the clam rubber is ground using a mechanical grinding process, a cryogenic process, or both processes. In both processes, the steel component is removed using a magnetic separator and the fibrous component is separated by an air classifier or other separation equipment. The mechanical grinding process mechanically breaks the rubber into small particles using various grinding techniques, such as cracking mills and granulators. In the cryogenic process, the shredded rubber is frozen at a cryogenic temperature and then broken into small particles.

[0039] According to a more preferred embodiment of the above preferred embodiment, the clam rubber is processed at cryogenic temperatures in accordance with the atomization processes described in U.S. Patent Nos. 7,445,170 and 7,861,958. Examples of commercially available clam rubbers include PolyDyne 40, PolyDyne 80, PolyDyne 140, or PolyDyne 200 from Lehigh Technologies. The clam rubber in the rubber composition according to the present invention may consist of a composition based on all of the raw materials commonly used in rubber compositions for rubber products.

[0040] According to a preferred embodiment of the present invention, the clam rubber in the rubber composition according to the present invention consists of an elastomer-based composition. According to a more preferred embodiment of the above preferred embodiment, the clam rubber comprises an elastomer comprising more than 30% by mass, preferably more than 35% by mass, and more preferably more than 40% by mass, per 100% by mass of the clam rubber, the percentage of which is measured according to standard ASTM E1131-03. According to the preferred embodiment described above, or a more preferred embodiment of the more preferred embodiment described above, the clam rubber comprises a diene elastomer, or preferably an elastomer comprising a diene elastomer.

[0041] According to a particular embodiment of the more preferred embodiment described above, the diene elastomer in the clam rubber is selected from the group consisting of polybutadiene and polyisoprene, including natural rubber, butadiene copolymer and isoprene copolymer. According to a specific embodiment of the more preferred embodiment described above, the molar content of diene-derived (conjugated diene) units present in the diene elastomer in the crumb rubber is greater than 50%, preferably greater than 50% and less than 70%. According to a preferred embodiment of the present invention, the clam rubber in the rubber composition according to the present invention consists of a filler-based composition. According to a more preferred embodiment of the above preferred embodiment, the amount of filler in the clam rubber is more than 5% by mass and less than 80% by mass per 100% by mass of clam rubber, preferably more than 10% by mass and less than 75% by mass, and more preferably more than 15% by mass and less than 70% by mass of filler, and the percentage is measured in accordance with standard ASTM E1131-03.

[0042] In this specification, the term “filler” refers to any type of filler, whether it is a reinforcing filler (generally having nanometer particles with a mass-average diameter preferably less than 500 nm, specifically greater than 20 nm and less than 200 nm) or a non-reinforcing or inert filler (generally having micrometer particles with a mass-average diameter preferably greater than 1 μm, for example greater than 2 μm and less than 200 μm). The mass-average diameter of nanometer particles is measured by methods well known to those skilled in the art (for example, in accordance with Chapter 1.1 of the patent application, International Patent Application No. 2009 / 083160). The mass-average diameter of micrometer particles can be measured by mechanical sieving. According to a more preferred embodiment of the above preferred embodiment, the filler in the crumb rubber includes a reinforcing filler, preferably an organic reinforcing filler, an inorganic reinforcing filler, or a combination thereof. All kinds of reinforcing fillers known to have the ability to reinforce rubber compositions usable in the manufacture of rubber products, such as organic reinforcing fillers, such as at least one type of carbon black, or inorganic reinforcing fillers, such as silica (SiO2), alumina (Al2O3), or a combination thereof, can be used, in which at least one coupling agent is combined in a known manner.

[0043] According to a more preferred embodiment of the more preferred embodiment described above, the reinforcing filler in the crumb rubber includes an organic reinforcing filler, preferably at least one type of carbon black, more preferably occupying more than 50% by mass, even more preferably more than 60% by mass, particularly more than 70% by mass, more specifically more than 80% by mass, even more specifically more than 90% by mass, and advantageously more than 100% by mass, per 100% by mass of the reinforcing filler. According to an even more preferred embodiment of the above more preferred embodiment, the reinforcing filler in the crumb rubber includes an organic reinforcing filler, preferably at least one type of carbon black, more preferably occupying 20% ​​to 40% by mass, and even more preferably 25% to 35% by mass, per 100% by mass of the crumb rubber. The mass fraction of carbon black can be measured by thermal mass spectrometry (TGA) according to standard NF T-46-07 using a Mettler Toledo Model TGA / DSC1 instrument. Approximately 20 g of sample can be introduced into the thermal analyzer and subjected to a thermal program under an inert atmosphere at 25°C to 600°C (thermal decomposition phase), followed by an oxidizing atmosphere at 400°C to 750°C (oxidation phase). The sample mass can be measured continuously throughout the thermal program. The organic matter content can correspond to the mass loss measured during the thermal decomposition phase relative to the initial mass of the sample. The amount of carbon black can correspond to the mass loss measured during the oxidation phase relative to the initial mass of the sample.

[0044] Suitable carbon blacks include all types of carbon black, particularly SAF, ISAF, HAF, FEF, GPF, HMF, SRF, and SRF series blacks, as well as reinforced carbon blacks that have been used in tires ("tire quality" blacks), such as ASTM grade 100, 200, or 300 series (e.g., N115, N134, N234, N326, N330, N339, N347, or N375 blacks), or high-grade carbon blacks, such as ASTM grade 500, 600, 700, 800, or 900 series (e.g., N550, N660, N683, N772, N774, N880, N990, N991 blacks). According to a more preferred embodiment of the above preferred embodiment, the filler in the clam rubber includes a non-reinforcing filler, preferably chalk, kaolin, or a similar combination. The clam rubber in the rubber composition according to the present invention may consist of a composition based on conventional additives generally used in rubber compositions intended for rubber products. The additives may also react during the manufacturing of the composition or during the crosslinking process of the composition in which the clam rubber is obtained, and may therefore be found in the clam rubber in the form of residues or derivatives. The crumb rubber in the rubber composition according to the present invention may be a simple pulverized / micronized rubber material that has not undergone any other processing.

[0045] A twelfth aspect of the present invention is a rubber composition according to any one of the first to eleventh aspects, wherein the clam rubber has not undergone any modification by a treatment selected from the group consisting of heat treatment, mechanical treatment, biological treatment and chemical treatment and combinations thereof. According to a preferred embodiment of the twelfth aspect, the clam rubber expresses an acetone extract in an amount of more than 3% by mass and less than 30% by mass, preferably more than 3% by mass and less than 15% by mass, and more preferably more than 3% by mass and less than 10% by mass, per 100% by mass of the clam rubber. According to a preferred embodiment of the twelfth aspect, the clam rubber expresses a chloroform extract in an amount of more than 3% by mass and less than 85% by mass, preferably more than 3% by mass and less than 20% by mass, and more preferably more than 5% by mass and less than 15% by mass, per 100% by mass of the clam rubber.

[0046] According to a preferred embodiment of the twelfth aspect, the clam rubber expresses a chloroform extract, and its mass-average molecular weight (Mw) is less than 10,000 g / mol, preferably less than 8,000 g / mol. According to a preferred embodiment of the twelfth aspect, the mass ratio of chloroform extract to acetone extract in the crumb rubber is less than 1.5. According to a preferred embodiment of the present invention, the clam rubber in the rubber composition according to the present invention is treated for modification. This treatment may consist of chemical functionalization or desulfurization. It may also be a treatment such as thermomechanical treatment, thermochemical treatment, or biological treatment. According to one embodiment of the present invention, the clam rubber of the rubber composition according to the present invention exhibits a modified form by heat treatment, mechanical treatment, biotreatment, chemical treatment, or a combination thereof. Preferably, the modified clam rubber expresses more than 5% by mass and less than 20% by mass, more preferably 10% to 18% by mass of acetone extract. Similarly, preferably, the modified clam rubber expresses more than 15% by mass and less than 85% by mass, more preferably 15% to 50% by mass of chloroform extract. Preferably, the mass-average molecular weight (Mw) of the chloroform extract of the modified clam 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 mass ratio of chloroform extract to acetone extract in the modified clam rubber is 1.5 or greater, preferably greater than 2.

[0047] The amount of acetone or chloroform extract can be measured using a Soxhlet extractor according to standard ISO 1407. A test sample (more than 500 mg but less than 5 g) is introduced into the extraction chamber and then into the Soxhlet extractor tube. A volume of acetone or chloroform equal to twice or three times the volume of the extractor tube can be added to the Soxhlet collector. The Soxhlet is then assembled and heated for 16 hours. The sample can be weighed after extraction. The amount of acetone or chloroform extract can correspond to the mass loss of the sample during extraction relative to its initial mass. Molecular weight can be measured by size exclusion chromatography according to Moore calibration and in accordance with standard ISO 16014. The mass-average molecular weight (Mw) of the chloroform extract can be measured by size exclusion chromatography (SEC) with a differential refractive index (RI) detector. The system consists of a Waters Alliance 2695 line, a Waters column oven, and a Waters RI 410 detector. The column set used may consist of two PL Gel Mixed D columns (300 × 7.5 mm, 5 μm) followed by two Agilent PL Gel Mixed E columns (300 × 7.5 mm, 3 μm). These columns may be placed in a column oven controlled to 35°C by a thermostat. The mobile phase used may be non-antioxidized tetrahydrofuran. The mobile phase flow rate may be 1 ml / min. The RI detector may also be controlled to 35°C by a thermostat. The chloroform extract may be dried under a nitrogen stream. Next, the dried extract may be redissolved in non-antioxidant tetrahydrofuran at 250 ppm per 1 g / l for 2 hours with stirring. 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 chromatographic system prepared at 1 ml / min and 35°C. The Mw result can be obtained by the integration of chromatographic peaks, which are detected by an RI detector when the value exceeds 2000 g / mol. Mw can be calculated by calibration performed using a polystyrene reference.

[0048] The total amount of reinforcing filler and clam rubber in the rubber composition according to the present invention is greater than 30 phr and less than 70 phr. According to a preferred embodiment of the present invention, the total amount of reinforcing filler and clam rubber in the rubber composition according to the present invention is 35 phr or more, preferably more than 35 phr, more preferably 40 phr or more, even more preferably more than 40 phr, particularly 45 phr or more, and more specifically more than 45 phr. According to a preferred embodiment of the present invention, the total amount of reinforcing filler and clam rubber in the rubber composition according to the present invention is 65 phr or less, preferably less than 65 phr, more preferably 60 phr or less, even more preferably less than 60 phr, specifically 55 phr or less, more specifically less than 55 phr, even more specifically 50 phr or less, and particularly less than 50 phr.

[0049] The mass ratio of the total amount of clam rubber to the total amount of reinforcing filler in the rubber composition according to the present invention is greater than 0.20 and less than 2.50, preferably 2.00 or less, more preferably less than 2.00, even more preferably 1.50 or less, specifically less than 1.50, more specifically 1.00 or less, and even more specifically less than 1.00. The rubber composition of the present invention may be based in whole or in part on common additives commonly used in rubber compositions intended for rubber products (e.g., tires, footwear, conveyor belts, or crawlers), such as plasticizers (e.g., liquid plasticizers (e.g., oils), solid plasticizers (e.g., hydrocarbon resins having or not having the characteristics of tackifying resins), or similar combinations), protective agents (e.g., anti-ozone waxes, chemical anti-ozone agents, antioxidants, or similar combinations), pigments, anti-fatigue agents, reinforcing resins, methylene acceptors (e.g., phenolic novolac resins), methylene donors (e.g., hexamethylenetetramine (HMT), hexamethoxymethylmelamine (H3M), or similar combinations), treatment acids, crosslinking (vulcanization) systems, or similar combinations. A 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 further based on an anti-ozone wax, and preferably the total amount of anti-ozone wax is greater than 1 phr in order to maintain or further improve the performance quality of the ozone resistance.

[0050] The ozone resistance performance quality of rubber compositions can be measured according to the following process: Ten test samples of each rubber composition are prepared by curing in a bell press, cooling to ambient temperature for one day, and then placing them in an oven at 77°C in air for 28 days. The ten test samples of each rubber composition are placed in a trapezoidal shape at different elongations ranging from 10% to 100% at the 10% elongation stage. The test sample designated "B15" originates from an MFTR (known as Monsanto) plate, and the two beads located at its edge are used to hold the test sample. The dimensions of the "B15" test sample are as follows: 78.5 mm * 15mm * The specimen has a thickness of 1.5 mm. After exposure to a temperature of 38°C and an ozone content of 50 pphm (parts per hundred million) for 192 hours, each surface of the test specimen is recorded as a function of the number and depth of cracks. This subjective evaluation ranges from 0 to 5 (0: no cracks present; 1-4: cracks present that are spreading and deepening; 5: fracture of the test specimen). A lower subjective classification indicates better performance quality against ozone. According to a preferred embodiment of the 14th aspect, the total amount of anti-ozone wax in the rubber composition according to the present invention is 1.1 phr or more, preferably greater than 1.1 phr, more preferably 1.2 phr or more, even more preferably greater than 1.2 phr, specifically 1.3 phr or more, and more specifically greater than 1.3 phr.

[0051] Anti-ozone waxes are also called anti-ozone waxes, but are well known to those skilled in the art as film-forming anti-ozone waxes. These film-forming anti-ozone waxes may be, for example, paraffin wax, microcrystalline wax, or a mixture of paraffin and microcrystalline wax. They consist mainly of mixtures of linear alkanes and non-linear alkanes (isoalkanes, cycloalkanes, branched alkanes) containing chains of at least 20 carbon atoms, obtained by oil refining or catalytic hydrogenation with carbon monoxide (Fischer-Tropsch process). For example, all anti-ozone waxes known to those skilled in the art, including natural waxes such as candelilla wax or carnauba wax, can be used. These waxes can also be used as mixtures.

[0052] Examples of commercially available anti-ozone waxes include Sasol's Varazon 4959, Varazon 6500, and Varazon 6810, Nippon Seiro's Ozoace 0355, H&R's Negozone 9343, and Yanggu Huatai's H3841. According to a preferred embodiment of the 14th aspect, the anti-ozone wax contains 50% to 75% by mass of a chain alkane having 30 to 38 carbon atoms, relative to the total amount of chain alkanes. According to a preferred embodiment of the 14th aspect, the total amount of anti-ozone wax is less than 3 phr in order to improve the performance quality of efflorescence. Efflorescence is a phenomenon in which the anti-ozone wax migrates to the outside of the rubber product containing the rubber composition, resulting in the appearance of off-white stains that impair the aesthetics of the rubber product.

[0053] The efflorescence performance quality of rubber compositions can be measured according to the following process. After cutting a plate of the cured rubber composition, test samples with a thickness of 2.5 mm are baked in air at 70°C for 12 hours. Next, they are heated and dried in air at 40°C for 4 weeks. After being removed from the oven and exposed to ambient temperature for 15 minutes, each test sample is scraped with a metal blade to expose the efflorescence of the anti-ozone wax. The degree of efflorescence (surface whitening) is then evaluated using a subjective scale of values ​​representing the final appearance of the sample. The values ​​obtained for each test sample may vary from 0 to 3 and correspond to the "efflorescence classification." These values ​​in the range of 0 to 3 correspond to the following aspects of the sample: 0: No efflorescence. The scraped surface remains black. 1: Slight white efflorescence. 2: Moderate efflorescence. 3: Complete efflorescence. The scraped surface is white.

[0054] The lower the value, the better the appearance of efflorescence; in other words, the less efflorescence there is. According to a preferred embodiment of the above-described preferred embodiment, the total amount of anti-ozone wax in the rubber composition according to the present invention is 2.8 phr or less, preferably less than 2.8 phr, more preferably less than 2.6 phr, even more preferably less than 2.6 phr, specifically 2.4 phr or less, more specifically less than 2.4 phr, even more specifically 2.2 phr or less, advantageously less than 2.2 phr, more advantageously less than 2.0 phr, even more advantageously less than 2.0 phr, specifically 1.8 phr or less, even more specifically less than 1.8 phr, even more specifically 1.6 phr or less, specifically less than 1.6 phr, and even more specifically 1.4 phr or less. According to a preferred embodiment of the present invention, the rubber composition according to the present invention is further based on a crosslinking system.

[0055] According to a more preferred embodiment of the above preferred embodiment, the crosslinking system in the rubber composition according to the present invention includes a vulcanizing agent, preferably selected from the group consisting of sulfur, sulfur donor, peroxide, bismaleimide and similar combinations, and more preferably selected from the group consisting of sulfur and similar combinations. The vulcanizing agent is also referred to as a "vulcanization agent," "hardening agent," or "curing agent." According to a yet more preferred embodiment of the above preferred embodiment, the sulfur donor is alkylphenol disulfide (abbreviated as "APDS"), more preferably para-(tert-butyl)phenol disulfide. According to a yet more preferred embodiment of the above preferred embodiment, the total amount of vulcanizing agent is greater than 0.5 phr and less than 10 phr, preferably greater than 0.5 phr and less than 3 phr.

[0056] According to a more preferred embodiment of the above preferred embodiment, the crosslinking system in the rubber composition according to the present invention is selected from the group consisting of a vulcanization accelerator, preferably a primary vulcanization accelerator, more preferably a sulfenamide-based accelerator, a thiazole-based accelerator, a thiuram-based accelerator, a dithiocarbamate-based accelerator and similar combinations, and more preferably a sulfenamide-based accelerator and similar combinations. According to a yet more preferred embodiment of the above preferred embodiment, the sulfenamide-based accelerator is selected from the group consisting of 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-oxydiethylene-2-benzothiazole sulfenamide (abbreviated as MBS), N,N'-dicyclohexyl-2-benzothiazole sulfenamide (abbreviated as DCBS) and similar combinations. According to an even more preferred embodiment of the above-described more preferred embodiment, the thiazole-based promoter is selected from the group consisting of 2-mercaptobenzothiazole (abbreviated as MBT), 2-mercaptobenzothiadyl disulfide (abbreviated as MBTS), zinc 2-mercaptobenzothiazole (abbreviated as ZMBT), 2-(morpholinothio)benzothiazole (abbreviated as MDB), and similar combinations. According to an even more preferred embodiment of the above-mentioned more preferred embodiment, the thiram-based accelerator is selected from the group consisting of tetramethylthiram disulfide (abbreviated as TMTD), tetraethylthiram disulfide (abbreviated as TETD), tetrabutylthiram disulfide (abbreviated as TBTD), tetrakis(2-ethylhexyl)thiram disulfide (abbreviated as TOT-N), tetramethylthiram monosulfide (abbreviated as TMTM), dipentamethylenethiram tetrasulfide (abbreviated as DPTT), tetrabenzylthiram disulfide (abbreviated as TBzTD), and similar combinations.According to a more preferred embodiment of the above-mentioned more preferred embodiment, the dithiocarbamate-based accelerator is selected from the group consisting of 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 similar combinations. According to a more preferred embodiment of the above-mentioned more preferred embodiment, the total amount of the vulcanization accelerator is greater than 0.5 phr and less than 5.0 phr.

[0057] According to a more preferred embodiment of the above preferred embodiment, the crosslinking system in the rubber composition according to the present invention includes a vulcanization retarder, for example, N-cyclohexylthiophthalimide (abbreviated as CTP).

[0058] According to a more preferred embodiment of the above preferred embodiment, the crosslinking system in the rubber composition according to the present invention comprises a vulcanizing activator, preferably selected from the group consisting of zinc oxide, fatty acids, zinc fatty acid esters, guazinine derivatives, or similar combinations. According to a yet more preferred embodiment of the above preferred embodiment, the fatty acid is stearic acid, lauric acid, palmitic acid, oleic acid, naphthenic acid, or similar combinations. According to a yet more preferred embodiment of the above preferred embodiment, the zinc fatty acid ester is zinc stearic acid, zinc lauric acid, zinc palmitic acid, zinc oleic acid, zinc naphthenic acid, or similar combinations. According to a yet more preferred embodiment of the above preferred embodiment, the guazinine derivative is diphenylguazinine.

[0059] A 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 further based on a crosslinking system containing a vulcanizing activator containing a guazinine derivative, and preferably the total amount of the guazinine derivative is more than 0.5% by mass and less than 5% by mass per 100% by mass of silica in the reinforcing filler. The rubber composition of the present invention can be used alone or as a mixture (in other words, as a blend) with any other rubber composition that can be used in the manufacture of rubber products. It is clear that the present invention relates to the above-mentioned rubber composition in both an unvulcanized state, an uncrosslinked state, or even an unprocessed state (in other words, before vulcanization) and a vulcanized state, a crosslinked state, or even a vulcanized state (in other words, after the crosslinking process or after vulcanization).

[0060] According to a preferred embodiment of the present invention, the rubber composition according to the present invention is further based on a crosslinking system comprising a vulcanizing agent, a vulcanization accelerator, a vulcanization retarder, a vulcanization activator, or a combination thereof, and is manufactured in a mixer using two consecutive preparation phases: a first phase (referred to as the "non-production" phase) of thermomachining or kneading at a high temperature of over 110°C and less than 200°C, preferably over 110°C and less than 190°C, more preferably over 130°C and less than 180°C, followed by a second phase (referred to as the "production" phase) of machining at a low temperature of 110°C or less, preferably over 40°C and less than 100°C, more preferably over 60°C and less than 100°C, during which a finishing phase, which is a vulcanizing agent, a vulcanization accelerator, a vulcanization retarder, or a combination thereof, is introduced into the crosslinking system. According to a more preferred embodiment of the above preferred embodiment, the vulcanization activator is introduced during the first non-production phase, during the production phase, or during the two phases, preferably during the first non-production phase.

[0061] According to a more preferred embodiment of the above preferred embodiment, the first phase (non-production phase) is carried out in multiple thermomechanical steps. During the first of the multiple thermomechanical steps, the elastomer matrix, reinforcing filler and clam rubber (and optionally plasticizers, other raw materials or similar combinations, except for crosslinking vulcanizing agents, vulcanization accelerators, vulcanization retarders or combinations thereof) are introduced into a mixer (preferably an internal mixer) at a temperature of over 20°C and below 100°C, preferably over 25°C and below 100°C. After a few minutes, preferably 0.5 to 2 minutes, the temperature rises to 90°C or above (preferably 100°C), and then all of the elastomer matrix, other raw materials and combinations thereof (in other words, what remains if not all of them were introduced into the mixer in the first phase (non-production phase)), except for crosslinking vulcanizing agents, vulcanization accelerators, vulcanization retarders or combinations thereof, are added all at once or in small amounts during kneading over a period of 20 seconds to several minutes. The total mixing time in the first phase (non-production phase) is preferably more than 1 minute and less than 15 minutes, more preferably more than 2 minutes and less than 10 minutes, at a temperature of 190°C or lower, preferably 180°C or lower, more preferably 170°C or lower.

[0062] According to the above preferred embodiment or a more preferred embodiment of the above more preferred embodiment, after the mixture thus obtained is cooled, the crosslinking vulcanizing agent, vulcanization accelerator, vulcanization retarder, or a combination thereof is then introduced into an external mixer, preferably into an open mill, at a low temperature, preferably 100°C or below, more preferably 90°C or below, and then mixed together in a second phase (production phase) for several minutes, preferably more than 2 minutes but less than 15 minutes, more preferably more than 5 minutes but less than 15 minutes. According to specific embodiments of the above preferred embodiments, more preferred embodiments, or even more preferred embodiments, the rubber composition thus obtained in a mixer using two consecutive preparation phases can then be calendered, for example, into sheet or plate form, particularly for laboratory characterization, or extruded into the shape of rubber products, such as rubber tire sidewalls, tire treads, footwear soles, conveyor belt covers, and crawler treads, which can be used directly.

[0063] According to the above preferred embodiments, more preferred embodiments, even more preferred embodiments, or more specific embodiments of the above particular embodiments, the crosslinking process (or curing) can be carried out in a known manner under pressure at a temperature greater than 110°C and less than 200°C, preferably greater than 130°C and less than 190°C, for a sufficient time, for example, between 5 and 90 minutes, taking into consideration the curing temperature, the crosslinking system used, the kinetics of crosslinking of the rubber composition, and also taking into consideration the size of the rubber product. According to a preferred embodiment of the present invention, the rubber composition is a rubber composition for rubber products that come into contact with ambient air, particularly for rubber tires, footwear, conveyor belts or crawlers, more specifically for rubber tire sidewalls, tire treads, footwear soles, conveyor belt coverings or crawler treads, and even more specifically for tire sidewalls.

[0064] A fifteenth aspect of the present invention is a rubber product comprising a rubber composition according to any one of the first to fourteenth aspects, preferably the rubber product comprising a rubber portion comprising a rubber composition according to any one of the first to fourteenth aspects, more preferably the rubber product being a rubber tire, footwear, conveyor belt or crawler, and more preferably the rubber portion being a rubber tire sidewall, tire tread, tire rim cushion, footwear sole, conveyor belt covering or crawler tread, and more particularly the tire comprising a rubber portion which is a tire sidewall comprising a rubber composition according to any one of the first to fourteenth aspects. The tire sidewall is part of the tire and is intended to be in contact with the surrounding air but not with the ground. The tread is part of the tire and is intended to be in contact with the surrounding air and the ground. The rim cushion of the tire is part of the tire and is intended to be in contact with the tire rim and the surrounding air but not with the ground. The conveyor belt is a conveying means of a belt conveyor system. The covering material of a conveyor belt is part of the conveyor belt and is also known as the covering rubber or "rubber covering material," and is intended to come into contact with the surrounding air. A rubber crawler is a type of continuous crawler and is also known as a rubber crawler, rubber crawler belt, or rubber crawler, intended to be equipped on a crawler vehicle. The tread of a rubber crawler is part of the rubber crawler and is intended to come into contact with the surrounding air and the ground.

[0065] According to a preferred embodiment of the present invention, the tire comprises a rubber composition according to any one of the first to fourteenth embodiments, and preferably the tire comprises a sidewall comprising a rubber composition according to any one of the first to fourteenth embodiments. The tires described above in the present invention are specifically intended to be fitted to passenger cars, such as 4x4 (four-wheel drive) vehicles and SUV (sports utility vehicle) vehicles, and industrial vehicles, in particular vans and heavy-duty multi-purpose vehicles (in other words, buses or heavy-duty land transport vehicles (cargo trucks, tractors, trailers)). The present invention can also be illustrated by the following non-limiting embodiments. [Examples]

[0066] To confirm the effects of the present invention, six types of rubber compositions were used (I1, I2, and I3: examples according to the present invention, C1 and C2: reference examples, and C3: comparative examples). Each of the rubber compositions is 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 a reinforcing filler), with or without the use of clam rubber. The formulations of each rubber composition are shown in Table 1, along with the amount of each product expressed in phr units.

[0067] Each rubber composition was manufactured as follows: Except for the crosslinking sulfur (as a vulcanizing agent) and N-cyclohexyl-2-benzothiazole sulfenamide (abbreviated as CBS) (as a vulcanization accelerator), reinforcing fillers, elastomer matrix, anti-ozone wax, clam rubber, plasticizers, and various other raw materials were continuously introduced into an internal mixer with an initial temperature of approximately 60°C, thus filling the mixer to approximately 70% (% volume). Next, a thermomachining process (non-production phase) was carried out in a single stage, which was completed in a total of approximately 3 to 4 minutes until the maximum "drop" temperature of 165°C was reached. After the mixture thus obtained was recovered and cooled, the crosslinking vulcanizing agent and vulcanization accelerator were introduced into an external mixer (homofinisher) at a temperature of 20°C to 30°C and mixed for an appropriate time (e.g., more than 5 minutes and less than 12 minutes) (production phase). Next, the rubber compositions thus obtained were calendered into either sheet form (2-3 mm thick) or thin rubber sheets for measuring their physical or mechanical properties, or into the shape of semi-finished molded parts for tires, for example, which can be used directly after being cut to desired dimensions, assembled, or both.

[0068] The dynamic properties of the rubber composition were measured using a Metravib VA4000 viscoanalyzer on test samples bonded from the cured rubber composition (G': shear dynamic modulus (or dynamic modulus), G'': viscous shear modulus, tanδ: loss coefficient, and G * The complex modulus of elasticity was obtained. The test specimen described in Figure X2.1 (circular) of standard ASTM D5992-96 (September 2006 edition, first approved in 1996) was used. The diameter "d" of the test specimen was 10 mm (therefore 78.5 mm). 2 The rubber composition had a circular cross-section, and the thickness of each part of the rubber composition was 2 mm with a "L" of 2 mm and a "d / L" ratio of 5 (unlike the ASTM standard, which recommends a d / L value of 2, and the standard ISO 2856 mentioned in Chapter X2.4). The response of test specimens of the vulcanized rubber composition was recorded when subjected to a simple alternating sinusoidal shear load at a frequency of 10 Hz and a temperature stabilized at 23 °C. The test specimens were mounted symmetrically around their equilibrium positions. The scanning strain amplitude was 0.1% to 50% (peak-peak: outward cycle; 12 measurement points) followed by 50% to 0.1% (peak-peak; return cycle; 11 measurement points). After acquiring each data, the shear dynamic modulus (G') and viscous shear modulus (G'') in the return cycle, and further the loss factor (tanδ) corresponding to the G'' / G' ratio were calculated. Similarly, the complex modulus (G * ) is the elastic modulus (G') and the viscous modulus (G''): G * =( G' 2 +G'' 2 ) 0.5 It is defined as the absolute value of the complex sum of and .

[0069] The frequency of 10 Hz, the temperature stabilized at 23°C, and the G'' value at 10% strain are representative of the hysteresis performance quality of each rubber composition, and are also representative of the rolling resistance performance quality when rubber tires, conveyor belts, or crawlers contain the rubber composition. The results (hysteresis performance quality) are expressed with a base of 100, meaning that the value 100 is intentionally assigned to the reference example (C1), and the values ​​for the embodiments according to the present invention (I1, I2, and I3), the values ​​for other reference examples (C2), and the values ​​for comparative example (C3) are shown in Table 2. A value corresponding to each of the formulas G''(C1, 10Hz, 23℃, 10%) / G''(X, 10Hz, 23℃, 10%) × 100 (wherein X is I1, I2, I3, C1, C2, or C3) is calculated. A higher value indicates lower hysteresis loss and better hysteresis performance quality. In the processability test, each sample produced from the rubber composition was subjected to a barrel temperature of 90°C under the standard ISO 11443:2014 Method A (Capillary Die Matrix) conditions, with a capillary die diameter of 1 mm, a capillary die length of 10 mm, and a process time of 80 seconds. -1 It was extruded at a shear rate of [value missing]. The degree of matrix swelling is calculated using "extruder diameter / capillary die diameter".

[0070] The results (processability) are expressed with a base of 100, meaning that the value 100 is intentionally assigned to reference example (C2). The values ​​for the embodiments according to the present invention (I1, I2, and I3), the values ​​for other reference examples (C1), and the values ​​for comparative example (C3) are shown in Table 2. A value corresponding to each of the following is calculated: Matrix swelling degree (C2, 10Hz, 23℃) / Matrix swelling degree (X, 10Hz, 23℃) × 100 (where X is I1, I2, I3, C1, C2, or C3). A higher value indicates a lower matrix swelling degree and better processability. The results in Table 2 show that the examples according to the present invention (I1, I2, and I3) have a better balance between hysteresis performance quality and processability than the reference examples and comparative examples (C1, C2, and C3). In conclusion, the rubber composition according to the present invention enables an unexpectedly improved balance between hysteresis performance quality and processability.

[0071] [Table 1] (1) Natural rubber; (2) Nd-butadiene rubber; (3) Carbon black (Cabot ASTM N234 grade, BET (compliant with standard ASTM D6556-10): 119 m 2 / g, COAN (according to standard ASTM D3493-16): 102 ml / 100 g); (4) Silica (Evonik Ultrasil® 7000GR; (5) Clam rubber (Polydyne 80 manufactured by Lehigh Technologies); (6) Oleic sunflower oil (Lubrirob Tod 1880, manufactured by Novance); (7) Silane coupling agent TESPT (Si69 manufactured by Evonik); (8) A combination of two antioxidants ((N-(1,3-dimethylbutyl)-N-phenyl-para-phenylenediamine (Santoflex 6-PPD from Flexsys) and 2,2,4-trimethyl-1,2-dihydroquinolone (TMQ from Lanxess) from Lanxess); (9) Anti-ozone wax (Varazon 4959 manufactured by Sasol); (10) Diphenylguazinine (Perkacit DPG manufactured by Flexsys); (11) Stearic acid (Pristerene 4931 manufactured by Uniqema); (12) Zinc oxide (industrial grade, manufactured by Umicore); (13) N-cyclohexyl-2-benzothiazole sulfenamide (Santocure CBS manufactured by Flexsys).

[0072] [Table 2]

Claims

1. at least, - Elastomer matrix, - Reinforcing filler, and - Clam Lover A rubber composition based on, The total amount of reinforcing filler is less than 50 phr. The reinforcing filler comprises at least one type of carbon black and at least one type of silica. A rubber composition in which the total amount of carbon black in phr units is less than the total amount of silica in phr units.

2. The rubber composition according to claim 1, wherein the elastomer 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 2, wherein the elastomer matrix comprises at least one isoprene elastomer, preferably the total amount of isoprene elastomers is greater than 30 phr and less than 70 phr.

4. The rubber composition according to any one of claims 1 to 3, wherein the elastomer matrix comprises at least one butadiene elastomer, preferably the total amount of butadiene elastomers is greater than 30 phr and less than 70 phr.

5. The rubber composition according to any one of claims 1 to 4, wherein the elastomer matrix comprises at least one isoprene elastomer and at least one butadiene elastomer, preferably the total amount of isoprene elastomers is greater than 30 phr and less than 70 phr, and the total amount of butadiene elastomers is greater than 30 phr and less than 70 phr.

6. The rubber composition according to any one of claims 1 to 5, wherein the total amount of reinforcing filler is greater than 5 phr.

7. The rubber composition according to any one of claims 1 to 6, 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 any one of claims 1 to 7, 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 any one of claims 1 to 8, wherein the total amount of clam rubber is greater than 0 phr and less than 50 phr.

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

11. The rubber composition according to any one of claims 1 to 10, wherein the clam rubber does not contain clam rubber particles that remain on the 40-mesh screen, or the clam rubber contains clam rubber particles that remain on the 40-mesh screen, and the total amount of clam rubber particles that remain on the 40-mesh screen is less than 10% by mass per 100% by mass of the clam rubber.

12. The rubber composition according to any one of claims 1 to 11, wherein the clam rubber has not been modified by any treatment selected from the group consisting of heat treatment, mechanical treatment, biological treatment and chemical treatment and combinations thereof.

13. The rubber composition according to any one of claims 1 to 12, wherein the rubber composition further comprises an anti-ozone wax base.

14. A rubber composition according to any one of claims 1 to 13, further comprising a crosslinking system containing a vulcanizing activator containing a guazinine derivative, wherein preferably the total amount of guazinine derivatives is more than 0.5% by mass per 100% by mass of silica in the reinforcing filler.

15. A rubber product comprising the rubber composition according to any one of claims 1 to 14, wherein the product preferably comprises a rubber portion comprising the rubber composition according to any one of claims 1 to 14, more preferably the rubber product is a rubber tire, footwear, conveyor belt or crawler, and even more preferably the rubber portion is a rubber tire sidewall, tire tread, tire rim cushion, footwear sole, conveyor belt covering or track tread, and in particular the rubber product is a tire comprising a rubber portion which is a tire sidewall comprising the rubber composition according to any one of claims 1 to 14.

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