rubber composition

Abstract

The present invention provides a rubber composition comprising: (a) a first elastomer comprising one or more styrene-butadiene copolymers having a glass transition temperature Tg in the range of -40 to -15°C; (b) a second elastomer comprising natural rubber; and (c) a hydrocarbon polymer additive component comprising: (i) a first hydrocarbon polymer additive which is a partially hydrogenated C5 resin; and (ii) a second hydrocarbon polymer additive which is a fully hydrogenated resin selected from the group consisting of hydrogenated C5 resin, hydrogenated C5 / C9 copolymer resin, hydrogenated C9 resin, and combinations thereof. The rubber composition is particularly suitable for use in the manufacture of tire components, particularly tire treads.

Description

[Technical Field]

[0001] The present invention relates to a rubber composition, a method for preparing the rubber composition, and the use of the rubber composition in the manufacture of vehicle tires and vehicle tire components. It also relates to vehicle tire components, particularly tire treads, made from the rubber composition.

[0002] More specifically, the present invention relates to a rubber composition comprising a rubber component containing a mixture of one or more styrene-butadiene rubbers having a high glass transition temperature (Tg) and natural rubber. The rubber component is compounded with a hydrocarbon polymer additive comprising a blend of partially hydrogenated and fully hydrogenated hydrocarbon resins. The particular blend of hydrocarbon resins advantageously improves the balance of wet performance, rolling resistance, and abrasion resistance of the rubber composition. [Background technology]

[0003] To reduce CO2 emissions, fuel-efficient automobiles are in demand. Automobile tires with low rolling resistance are desirable because they reduce fuel consumption. It is also important for tires to have good grip on both dry and wet surfaces, with wet performance being particularly important. High wear resistance is also an important factor for tire longevity. Wet performance (WET), rolling resistance (RR), and wear resistance (WEAR) are collectively known as the "magic triangle" of viscoelastic properties. There is a constant demand for manufacturing tires that offer an improved balance between these properties.

[0004] The components of rubber compositions used in tire manufacturing can be modified to adjust their dynamic and mechanical properties. In an attempt to achieve a better wet / relax / wear balance, the use of modified rubbers, rubber blends, and various reinforcing fillers has been proposed. However, improving any one of these properties of a rubber composition often adversely affects at least one other property. For example, it is difficult to improve a tire's wet performance without adversely affecting its rolling resistance and wear resistance. Increasing the amount of reinforcing filler improves wear performance while decreasing rolling resistance.

[0005] Hydrocarbon resins are widely used as processing aids to enhance the dispersion of different rubber components during rubber compounding. They are also used to modify the viscoelastic properties of rubber compositions, improving tire tread performance characteristics, such as wet grip and rolling resistance. A wide variety of hydrocarbon resins are known for use in the manufacture of tire tread rubber compositions, including aliphatic resins, aromatic resins, partially hydrogenated resins, and fully hydrogenated resins. Examples include C5 aliphatic resins, C9 aromatic resins, C5 / C9 mixed resins, aromatic pure monomer resins, dicyclopentadiene (DCPD) resins, aromatic-modified cycloaliphatic resins, coumarone-indene resins, rosin resins, terpene resins, modified terpene resins, terpene-phenolic resins, and their hydrogenated derivatives. Combinations of different hydrocarbon resins have been proposed to control blend morphology and filler distribution in rubber compositions. Different resins and resin combinations can differ in their chemical composition and / or molecular weight, which can affect their properties, such as the compatibility of a given rubber or rubber blend. For example, U.S. Patent Publication No. 2019 / 0092937 proposes blending a C5 aliphatic resin with a DCPD resin or an aromatic pure monomer resin to adjust the material properties of an immiscible blend of natural rubber and high-cis polybutadiene rubber. Summary of the Invention [Problem to be solved by the invention]

[0006] Styrene-butadiene rubber (SBR) is well known for its use in tire manufacturing, often as a blend with natural rubber. SBR has a high glass transition temperature (Tg) and can be used to increase the Tg of the overall rubber composition. A higher Tg in a composition leads to improved wet performance, but is accompanied by reduced rolling resistance and wear. Various attempts have been made to improve RR and WEAR while maintaining wet performance, such as increasing the vinyl content of SBR or introducing functional groups into the polymer chain. To date, the effect of hydrocarbon resins on the dynamic properties of rubber compositions containing blends of high-Tg SBR and natural rubber has not been studied.

[0007] There remains a need to provide tires with improved wet / rr / wear balance, particularly in rubber compositions that include blends of high Tg styrene-butadiene copolymers and natural rubber, that provide a good balance of these properties.

[0008] The inventors have surprisingly found that certain blends of partially and fully hydrogenated hydrocarbon resins can improve the WET / RR / WEAR balance of rubber compositions containing at least one high Tg styrene-butadiene copolymer and natural rubber.

[0009] The degree of improvement over each hydrocarbon resin used alone was unexpected and sufficiently counteracts the degradation in wet performance and rolling resistance that occurs when a reinforcing silica filler is incorporated, allowing the wear performance to be improved by increasing the filler content of the rubber composition without adversely affecting rolling resistance and wet performance. [Means for solving the problem]

[0010] In a first aspect, the present invention provides a rubber composition, the rubber composition comprising: (a) a first elastomer comprising one or more styrene-butadiene copolymers having a Tg of -40 to -15°C; (b) a second elastomer comprising natural rubber; and (c) a hydrocarbon polymer additive component, (i) a first hydrocarbon polymer additive that is a partially hydrogenated C5 resin; and (ii) a second hydrocarbon polymer additive which is a fully hydrogenated resin selected from the group consisting of hydrogenated C5 resin, hydrogenated C5 / C9 copolymer resin, hydrogenated C9 resin, and combinations thereof; the hydrocarbon polymer additive component comprising: Equipped with.

[0011] In another aspect, the present invention provides a process for making a rubber composition, the process comprising compounding components (a), (b), and (c) described herein.

[0012] In another aspect, the present invention provides a vulcanizable rubber composition comprising: (a) a first elastomer comprising one or more styrene-butadiene copolymers having a Tg of -40 to -15°C; (b) a second elastomer comprising natural rubber; and (c) a hydrocarbon polymer additive component, (i) a first hydrocarbon polymer additive that is a partially hydrogenated C5 resin; and (ii) a second hydrocarbon polymer additive which is a fully hydrogenated resin selected from the group consisting of hydrogenated C5 resin, hydrogenated C5 / C9 copolymer resin, hydrogenated C9 resin, and combinations thereof; the hydrocarbon polymer additive component comprising: Equipped with.

[0013] In another aspect, the present invention provides a vulcanized rubber composition, which is obtained, obtained directly, or obtainable by crosslinking the vulcanizable rubber composition described herein.

[0014] In another aspect, the present invention provides a process for producing a vulcanized rubber composition, the process comprising the steps of blending components (a), (b), and (c) as described herein to produce a vulcanizable rubber composition, and vulcanizing the vulcanizable rubber composition by heating it to a predetermined temperature for a predetermined time.

[0015] In another aspect, the present invention provides the use of the rubber composition described herein as or in the manufacture of a vehicle tire component.

[0016] In another aspect, the present invention provides vehicle tire components made from the rubber compositions described herein.

[0017] In another aspect, the present invention provides a vehicle tire comprising the vehicle tire components described herein.

[0018] According to a first aspect, the present invention provides a rubber composition comprising: (a) a first elastomer comprising one or more styrene-butadiene copolymers having a Tg of -40 to -15°C; (b) a second elastomer comprising natural rubber; and (c) a hydrocarbon polymer additive component, (i) a first hydrocarbon polymer additive that is a partially hydrogenated C5 resin; and (ii) a second hydrocarbon polymer additive which is a fully hydrogenated hydrocarbon resin selected from the group consisting of hydrogenated C5 resin, hydrogenated C5 / C9 copolymer resin, hydrogenated C9 resin, and combinations thereof; the hydrocarbon polymer additive component comprising: Equipped with.

[0019] As described herein, the rubber composition according to the present invention may contain other ingredients conventionally used in compounding rubber for use as tire treads, such as reinforcing fillers. Preferably, the rubber composition includes at least one reinforcing filler, such as silica.

[0020] Unless otherwise specified, the terms "rubber composition," "compounded rubber," and "rubber compound" are used interchangeably herein to refer to rubber that has been blended or mixed (compounded) with various ingredients or materials, as such terms are well known and understood in the art. The present invention relates to rubber compositions, and relates to rubber compositions in both the raw state (i.e., before curing or vulcanization) and the cured or vulcanized state (i.e., after curing or vulcanization).

[0021] The rubber composition according to the present invention comprises a first elastomer and a second elastomer, as defined herein. The degree of miscibility of the first and second elastomers may be limited. When present as a mixture in the rubber composition, they may tend to produce regions where the first or second elastomer predominates. In some embodiments, the first and second elastomers may be immiscible and thus present in the rubber composition as an immiscible blend. The term "elastomer" is used herein to refer to a polymer or combination of polymers.

[0022] The first elastomer comprises at least one styrene-butadiene copolymer having a high glass transition temperature, Tg. The term "styrene-butadiene copolymer" means a synthetic rubber made by the polymerization of styrene and butadiene. Styrene-butadiene copolymer may be referred to herein as "styrene-butadiene rubber" or "SBR."

[0023] In one embodiment, the first elastomer comprises a blend of two or more styrene-butadiene copolymers. For example, it may comprise two different styrene-butadiene copolymers. When more than one styrene-butadiene copolymer is present in the rubber composition, each copolymer is considered to have a higher Tg, as defined herein. The glass transition temperature, Tg, is a second-order transition and is the temperature range over which an amorphous material reversibly changes from a hard, or "glassy," solid to a more flexible, or "rubbery," viscous state.

[0024] Tg can be determined by differential scanning calorimetry (DSC). Tg values ​​reported herein are determined using DSC with an onset temperature of -140°C and a temperature ramp rate of 15°C / min. Unless otherwise specified, all test methods described herein are performed at 23°C and 50% relative humidity.

[0025] By "high Tg" it is meant that the styrene-butadiene copolymer(s) used in the present invention have a Tg in the range of -40 to -15°C. In some embodiments, the Tg is in the range of -35 to -15°C, or -30 to -15°C, or -28 to -18°C, or -26 to -21°C.

[0026] In one embodiment, the first elastomer consists essentially of one or more styrene-butadiene copolymers as described herein. In another embodiment, the first elastomer consists essentially of such copolymers.

[0027] Styrene-butadiene rubber (SBR) is commonly used in the tire industry and can be produced by known methods, such as copolymerization of the corresponding monomers in emulsion, suspension, or solution. In one set of embodiments, the styrene-butadiene copolymer used in the present invention can be solution-polymerized styrene-butadiene rubber (SSBR) or emulsion-polymerized styrene-butadiene rubber (EDBR). "Emulsion-polymerized styrene-butadiene rubber" refers to the copolymerization of styrene and 1,3-butadiene in an aqueous emulsion. Such methods are well known and understood by those skilled in the art. Preferred for use in the present invention is SBR produced by solution polymerization. Styrene and butadiene monomers can be selected in appropriate ratios depending on the intended use and properties of the rubber composition. For example, styrene can be present in an amount of up to about 45 wt% (based on the total weight of comonomers). In some embodiments, the styrene content of the SBR may be 10 to 40 wt% (based on the weight of the SBR rubber), preferably 10 to 30 wt%, more preferably 15 to 25 wt%, and even more preferably 21 to 24 wt%, for example, about 21 wt%. The styrene content can be measured by H-NMR.

[0028] The styrene-butadiene copolymer(s) used in the present invention may be functionalized or unfunctionalized. In one embodiment, the styrene-butadiene copolymer is unfunctionalized, i.e., unmodified. In this embodiment, the styrene-butadiene copolymer does not contain any functional groups, particularly at the ends of the main chain.

[0029] Alternatively, the styrene-butadiene copolymer(s) used in the present invention may be functionalized. A "functionalized" styrene-butadiene copolymer refers to modification with one or more functional groups. When a styrene-butadiene copolymer is functionalized, one or more functional groups may be attached to either the polymer backbone, end groups, and / or side chains. These functional groups may be incorporated into the polymeric material during its manufacture, or they may be grafted onto the polymer subsequently. The choice of functionalized styrene-butadiene copolymer is determined by the intended use of the rubber compound described herein. Examples of functionalized styrene-butadiene copolymers include those containing one or more reactive groups, such as groups capable of reacting with silica coupling agents, sulfur-containing organosilicon compounds, etc. Representative functional groups include halogens such as Cl and Br; alkoxy groups such as methoxy; siloxy groups; and pseudohalogens such as -SCN. In one embodiment, the styrene-butadiene copolymer may be a siloxy-terminated copolymer. The functional groups may also include one or more interactive groups, such as amino groups, which may, for example, form hydrogen bonds within the rubber matrix of the composition.

[0030] A significant contribution to energy dissipation in tire treads, and therefore rolling resistance, comes from the presence of free polymer chain ends, and in embodiments containing filler systems such as silica fillers, this comes from degradation of the filler network formed by the silica filler. Advantageously, styrene-butadiene copolymers with functional groups at the ends and / or beginnings of the polymer chains, which allow them to physically or chemically attach to the filler surface, can therefore be employed in the present invention. These limit the mobility of the polymer chains, thereby reducing energy dissipation under dynamic stress. They also improve the dispersion of reinforcing fillers in the rubber composition, leading to a stronger filler network and therefore reduced rolling resistance.

[0031] In some embodiments, the styrene-butadiene copolymers used in the present invention are end-functionalized copolymers, which may have a synergistic and / or synergistic effect on the properties of the rubber composition, resulting in advantageous properties. Specifically, when a silica filler system is present, the interaction between the end-functionalized styrene-butadiene copolymer and the silica may be synergistic, potentially improving the dispersion of the filler system in the rubber composition and in products made from the rubber composition. "End-functionalized" SBR is sometimes referred to as "end-modified" SBR. In some embodiments, the styrene-butadiene copolymer may be end-functionalized SSBR. End-functionalized rubbers are well known in the art, and any rubber known for use in producing tire tread rubber compounds may be used in the present invention.

[0032] In one set of embodiments, the first elastomer is a blend of two or more styrene-butadiene copolymers, each having a high Tg, as defined herein. For example, it can be a blend of two such copolymers. In some embodiments, the first elastomer can be composed of two or more (e.g., two) SBR components of the same type, but the SBR components have different molecular weights (e.g., number average or weight average), are produced from different polymerization processes (e.g., solution-based or emulsion-based), or have different functionality (e.g., the location of functionalization (i.e., terminally functionalized or unfunctionalized) or different functional groups).

[0033] A suitable blend of styrene-butadiene copolymers can be readily selected by one skilled in the art, keeping in mind the intended use of the rubber composition. In one embodiment, the first elastomer comprises two different SBR polymers. For example, the first elastomer may comprise an SSBR and an ESBR. In one set of embodiments, the first elastomer may comprise an end-functionalized SBR and an unfunctionalized SBR. In some embodiments, the first elastomer comprises two SSBR polymers having different molecular weights. In some embodiments, the first elastomer comprises two SSBR polymers having different styrene contents.

[0034] The second elastomer comprises natural rubber. In one embodiment, the second elastomer consists essentially of natural rubber, for example, can consist of natural rubber.

[0035] Natural rubber is well known for its use in tire manufacturing. The natural rubber used in the present invention is not particularly limited and may be any natural rubber or combination of natural rubbers commonly used in the tire industry. Specific examples include Standard Malaysian Rubber (SMR), Standard Indonesian Rubber (SIR), Special Singapore Rubber (SSR), Standard Lankan Rubber (SLR), Thai Test Rubber (TTR), Nigerian Standard Rubber, etc.

[0036] In some embodiments, the first elastomer is present in an amount of from about 40 to about 90 phr, preferably from about 70 to about 90 phr, for example from about 80 to about 90 phr, per 100 phr of the rubber composition.

[0037] In some embodiments, the second elastomer is present in an amount of about 10 to about 60 phr, preferably about 10 to about 30 phr, more preferably about 15 to about 25 phr, for example about 20 to about 25 phr, per 100 phr of the rubber composition.

[0038] As used herein, the term "phr" means parts per million (by weight) of rubber. This is a term commonly used in the art and measures the components of a composition relative to the total rubber (i.e., elastomer) component. The total rubber component is defined as 100 phr, and the other components are defined as percentages of 100 parts rubber and expressed as "phr."

[0039] In some embodiments, the rubber compositions described herein may include other elastomer components in addition to the first and second elastomers described herein. Other rubber components that may be present include butadiene rubber (BR), ethylene propylene diene monomer rubber (EPDM), butyl rubber (IIR), polyisobutylene rubber, epoxidized natural rubber (ENR), neoprene, synthetic polyisoprene (IR), and polyurethane.

[0040] The compositions described herein include a hydrocarbon polymer additive component. As used herein, the term "hydrocarbon polymer additive" refers to a hydrocarbon resin and is used interchangeably herein with "hydrocarbon resin."

[0041] The hydrocarbon polymer additive component includes a first hydrocarbon polymer additive that is a partially hydrogenated C5 resin and a second hydrocarbon polymer additive that is a fully hydrogenated resin selected from a hydrogenated C5 resin, a hydrogenated C5 / C9 resin, a hydrogenated C9 resin, and combinations thereof.

[0042] Additional resins may be present in the rubber composition, but in one embodiment the only resins present are the first and second hydrocarbon resins described herein.

[0043] Exemplary combinations of the first and second hydrocarbon polymer additives include a partially hydrogenated C5 resin and a fully hydrogenated C5 resin; a partially hydrogenated C5 resin and a fully hydrogenated C5 / C9 copolymer resin; a partially hydrogenated C5 resin and a fully hydrogenated C9 resin. A preferred combination of hydrocarbon polymer additives for use in the present invention is a partially hydrogenated C5 resin and a fully hydrogenated C9 resin.

[0044] As used herein, the term "hydrogenated resin" refers to a resin obtained by reductive hydrogenation of a resin. The hydrogenation can be partial, resulting in a "partially hydrogenated resin," or nearly complete, resulting in a "fully hydrogenated resin."

[0045] As used herein, the term "partially hydrogenated" refers to a resin component having an olefinic proton content of less than 100%. Partially hydrogenated resins are well known in the art and can have different degrees of hydrogenation. In some embodiments, the partially hydrogenated resin may contain less than 95% olefinic protons, more preferably less than 90% olefinic protons. In some embodiments, the partially hydrogenated resin may contain less than 75% olefinic protons, e.g., less than 50% olefinic protons. In some embodiments, the partially hydrogenated resin may contain less than 40% olefinic protons, less than 25% olefinic protons, less than 15% olefinic protons, or less than 10% olefinic protons. For example, it may contain less than 9%, less than 8%, less than 7%, or less than 6% olefinic protons. In one embodiment, the partially hydrogenated resin may contain about 5% or more olefinic protons. For example, it may contain 5 to 90% olefinic protons. In one embodiment, the partially hydrogenated resin may contain about 5% olefinic protons, i.e., it may be 95% hydrogenated.

[0046] As used herein, the term "fully hydrogenated" refers to a resin component having an olefinic proton content of less than 5%. In some embodiments, a fully hydrogenated resin may contain less than 4% olefinic protons, preferably less than 3%, more preferably less than 2%, e.g., less than 1%, less than 0.5%, or less than 0.1%, e.g., less than 0.05% olefinic protons. In one embodiment, a fully hydrogenated resin may contain 0 to about 3% olefinic protons, i.e., about 97 to 100% hydrogenated. In one embodiment, a fully hydrogenated resin may contain 0 to about 2% olefinic protons, i.e., about 98 to 100% hydrogenated. In one embodiment, a fully hydrogenated resin may contain 0 to about 1% olefinic protons, i.e., about 99 to 100% hydrogenated. In one embodiment, a fully hydrogenated resin may contain about 0% olefinic protons.

[0047] Hydrogenated resins include resins produced by reductive hydrogenation of resins containing aromatic components. It should be understood that references to olefinic protons herein are intended to include any protons that may be present as part of an aromatic ring system. With respect to the content of olefinic protons and the degree of hydrogenation, the percentages referred to herein refer to mol%.

[0048] For any selected combination of hydrocarbon resins used in the present invention, the degree of hydrogenation of the "fully hydrogenated" resin will be greater than the degree of hydrogenation of the "partially hydrogenated" resin, i.e., the "fully hydrogenated" resin will have a lower content of olefinic protons than the "partially hydrogenated" resin. Suitably, the difference in the degree of hydrogenation of different hydrocarbon resins used in the present invention may be small. For example, the mol% of the olefinic proton content of different resins may differ by less than 10 mol%, e.g., less than 8 mol%, less than 7 mol%, less than 6 mol%, less than 5 mol%, less than 5 mol%, or less than 3 mol%. In one embodiment, the mol% may differ by 1 to 10 mol%, e.g., 1 to 5 mol%.

[0049] The first hydrocarbon resin is a partially hydrogenated C5 resin. As used herein, the term "C5 resin" refers to a resin obtained by polymerization of a cracked naphtha feed containing C5 monomers. C5 monomers include olefins, linear conjugated diolefins, and cyclic conjugated diolefins. Other monomers may also be present in the feed, including, but not limited to, dicyclopentadiene (DCPD).

[0050] In one embodiment, the C5 resin used in the present invention can be obtained by copolymerization of a C5 monomer and a DCPD monomer. When a DCPD monomer is present, the DCPD monomer is generally provided in a low amount. For example, the DCPD content in the feed used to produce the resin can be less than about 5%, e.g., less than about 2%. In one embodiment, the C5 resin can include monomer units derived from a C5 monomer and DCPD.

[0051] In another embodiment, the feed used to produce the C5 resin can be stripped of DCPD monomer, which can be removed from the feed stream by methods commonly known in the art. In one embodiment, the C5 resin can therefore consist essentially of monomer units derived from C5 monomers.

[0052] To improve wet performance, the hydrogenated C5 resin used in the present invention has a high softening point, for example, a softening point higher than 110°C. As used herein, the term "softening point" refers to the temperature at which the resin flows. The softening point of the resin can be measured by the ring-ball method. Unless otherwise specified, the softening point referred to herein is the "ring-ball softening point," i.e., the temperature at which a ball falls when measuring the softening point using a ring-ball softening point measuring apparatus, in accordance with ASTM D 3461-76.

[0053] In a specific embodiment, the softening point of the C5 resin is 115°C or higher, preferably 118°C or higher, more preferably 121°C or higher, for example, 123°C or higher. For example, it is 125°C or higher, 127°C or higher, 128°C or higher, or 129°C or higher. From the viewpoint of suppressing an increase in tan δ at 0°C, the softening point of the hydrogenated C5 resin is preferably 145°C or lower. For example, the softening point may be 143°C or lower, 140°C or lower, 136°C or lower, 135°C or lower, or 133°C or lower.

[0054] From the viewpoint of compatibility between the resin and the rubber component, the weight average molecular weight of the partially hydrogenated C5 resin is generally in the range of 200 to 1200 g / mol. Unless otherwise specified, all references to molecular weight in this specification refer to the weight average molecular weight Mw. The weight average molecular weight is determined by gel permeation chromatography (GPC) against a polystyrene standard.

[0055] In some embodiments, the weight average molecular weight of the partially hydrogenated C5 resin may be 300 g / mol or more, preferably 500 g / mol or more, more preferably 700 g / mol or more, and even more preferably 750 g / mol or more. In other embodiments, the weight average molecular weight of the partially hydrogenated C5 resin may be 1150 g / mol or less, preferably 1100 g / mol or less, more preferably 950 g / mol or less, and even more preferably 930 g / mol or less, for example 900 g / mol or less.

[0056] In one embodiment, the partially hydrogenated C5 resin has a softening point greater than 100° C. and a weight average molecular weight of 200 to 1200 g / mol.

[0057] In one embodiment, the partially hydrogenated C5 resin has a glass transition temperature (Tg) in the range of 50 to 100°C, preferably 60 to 90°C, for example 70 to 80°C.

[0058] The partially hydrogenated C5 resin used in the present invention is a resin produced by subjecting the C5 resin described herein to partial reductive hydrogenation. Examples of C5 resins include aliphatic petroleum resins, which are obtained by (co)polymerizing C5 fractions, which are obtained by thermal cracking of naphtha in the petrochemical industry. The C5 fraction typically contains olefin-based hydrocarbons such as 1-pentene, 2-pentene, 2-methyl-1-butene, 2-methyl-2-butene, and 3-methyl-1-butene; and diolefin-based hydrocarbons such as 2-methyl-1,3-butadiene, 1,2-pentadiene, 1,3-pentadiene, and 3-methyl-1,2-butadiene. As described herein, the C5 fraction may also contain other monomers, such as dicyclopentadiene (DCPD). When DCPD is present, it is generally present in low amounts, e.g., less than 5 wt. %, e.g., less than 2 wt. % of the C5-containing fraction. Any of these resins can be subjected to partial reductive hydrogenation to produce a partially hydrogenated C5 resin, e.g., one containing 3-9% olefinic protons, preferably 4-8% olefinic protons, and more preferably 4-6% olefinic protons. In one embodiment, the partially hydrogenated C5 resin contains about 5% olefinic protons.

[0059] Any commonly available partially hydrogenated C5 resin can be used, such as a resin with a softening point of about 130°C, a weight-average molecular weight (Mw) of about 840 g / mol, and a glass transition temperature (Tg) of about 75°C.

[0060] The second hydrocarbon resin is selected from a fully hydrogenated C5 resin, a fully hydrogenated C5 / C9 resin, a fully hydrogenated C9 resin, and combinations thereof.

[0061] To improve wet performance, the second hydrocarbon resin used in the present invention has a high softening point, for example, a softening point greater than 100°C.

[0062] In a specific embodiment, the softening point of the second hydrocarbon resin is 110° C. or higher, preferably 115° C. or higher, and more preferably 118° C. or higher. From the viewpoint of suppressing an increase in tan δ at 0° C., the softening point of the second hydrocarbon resin is preferably 145° C. or lower. For example, the softening point may be 143° C. or lower, 140° C. or lower, 136° C. or lower, 135° C. or lower, 133° C. or lower, or 130° C. or lower.

[0063] From the viewpoint of miscibility of the resin with the rubber component, the weight average molecular weight of the second hydrocarbon resin is generally in the range of 700 to 1500 g / mol. In some embodiments, the weight average molecular weight of the second resin may be 800 g / mol or more, preferably 900 g / mol or more, and more preferably 1000 g / mol or more. In other embodiments, the weight average molecular weight of the second hydrocarbon resin may be 1400 g / mol or less, preferably 1300 g / mol or less, and more preferably 1200 g / mol or less.

[0064] In one embodiment, the second hydrocarbon resin has a softening point greater than 100° C. and a weight average molecular weight of 700 to 1500 g / mol. More preferably, the second hydrocarbon resin is a fully hydrogenated C9 resin, has a softening point greater than 100° C. and a weight average molecular weight of 700 to 1500 g / mol.

[0065] The second hydrocarbon resin is prepared by subjecting the resin to near-complete (e.g., complete) reductive hydrogenation, and the resin used as the starting material is selected from a C5 resin, a C5 / C9 resin, a C9 resin, and combinations thereof.

[0066] Examples of C5 resins that can be used to produce fully hydrogenated C5 resins include aliphatic petroleum resins, which are obtained by (co)polymerization of C5 fractions, which are obtained by thermal cracking of naphtha in the petrochemical industry. C5 fractions typically contain olefin-based hydrocarbons, such as 1-pentene, 2-pentene, 2-methyl-1-butene, 2-methyl-2-butene, and 3-methyl-1-butene; diolefin-based hydrocarbons, such as 2-methyl-1,3-butadiene, 1,2-pentadiene, 1,3-pentadiene, and 3-methyl-1,2-butadiene. They may also contain other monomers, such as DCPD. Any commonly available C5 resin can be used.

[0067] The term "C5 / C9 resin" refers to synthetic C5 to C9 petroleum resins, examples of which include petroleum-derived C5 to C9 resins containing AlCl3. 11 Examples include distillates; solid polymers obtained by polymerization using Friedel-Crafts catalysts; and more specific examples include styrene, vinyltoluene, α-methylstyrene, indene, and copolymers based on these. From the perspective of compatibility with rubber components, resins with a low content of C9 or higher components are preferred as C5 / C9 resins. For example, the amount of C9 or higher components can be less than 50 wt% of the total resin, preferably less than 40 wt%. Any commonly available C5 / C9 resin can be used.

[0068] The term "C9 resin" refers to a C9 synthetic petroleum resin, such as those obtained by polymerization using Friedel-Crafts catalysts such as AlCl3 or BF3. Examples of C9 resins include indene, styrene-α-methylstyrene, vinyltoluene, or copolymers based on these. Any commonly available C9 resin can be used. Examples include resins with a softening point of approximately 118-128°C, a weight-average molecular weight (Mw) of approximately 1100 g / mol, and a glass transition temperature (Tg) of approximately 65-75°C.

[0069] The amount of hydrocarbon polymer additive component present in the rubber composition varies depending on the elastomer content. An appropriate amount can be readily selected by one skilled in the art. Generally, the total amount of hydrocarbon polymer additive component may range from about 5 to about 25 phr (per 100 phr of rubber composition), preferably from about 10 to about 20 phr, more preferably from about 12 to about 18 phr, for example, from about 14 to about 16 phr.

[0070] The amount of each of the first and second hydrocarbon resins may vary depending on the selection of the first and second elastomers and their relative amounts in the rubber composition, and appropriate amounts can be readily selected by one skilled in the art.

[0071] In one embodiment, the amount of the first hydrocarbon resin may range from about 2 to about 15 phr (per 100 phr of the rubber composition), preferably from about 3 to about 11 phr. In some embodiments, the amount of the first hydrocarbon resin may range from about 5 to about 10 phr, preferably from about 6 to about 9 phr, for example, from about 7 to about 8 phr.

[0072] In one embodiment, the amount of the second hydrocarbon resin may range from about 2 to 15 phr (per 100 phr of the rubber composition), preferably from about 3 to about 11 phr. In some embodiments, the amount of the second hydrocarbon resin may range from about 5 to about 10 phr, preferably from about 6 to about 9 phr, for example, from about 7 to about 8 phr.

[0073] Suitably, the weight ratio of the first hydrocarbon polymer additive to the second hydrocarbon polymer additive is in the range of 20:80 to 80:20, preferably 25:75 to 75:25, more preferably 30:70 to 70:30, for example 40:60 to 60:40. In a preferred embodiment, the weight ratio of the first and second hydrocarbon polymer additives may be about 50:50.

[0074] In some embodiments, the ratio of the first hydrocarbon polymer additive to the second hydrocarbon polymer additive ranges from 20:80 to 60:40, preferably from 25:75 to 50:50, and in some embodiments, a ratio of about 50:50 or about 25:75 may be preferred.

[0075] The rubber compositions described herein may contain other additives known to be commonly used in making rubber compositions, such as reinforcing fillers, other processing aids such as processing oils, crosslinking and cure systems, accelerators, and the like.

[0076] In one embodiment, the rubber composition further comprises a filler. The filler component can be selected from, for example, silica, carbon black, carbon nanotubes, short carbon, polyamide, polyester, natural fiber, calcium carbonate, clay, alumina, aluminosilicate, and any mixture thereof. The use of silica, carbon black, and blends of silica and carbon black is generally preferred.

[0077] The term "silica filler" as used herein refers to particulate silica. Any known particulate silica capable of reinforcing styrene-butadiene rubber-based compositions can be used. As will be appreciated, known silica materials typically contain other components in proportion (e.g., as impurities), but the primary component is silicon dioxide, i.e., SiO2. The silicon dioxide content is generally at least 90 wt%, preferably at least 95 wt%, e.g., at least 97 wt%.

[0078] Silica materials for use in the present invention are well known in the art and include, among others, precipitated amorphous silica, wet silica (hydrated silicic acid), dry silica (anhydrous silicic acid), fumed silica, calcium silicate, aluminum silicate, magnesium silicate (e.g., MgSiO4, MgSiO3), magnesium calcium silicate (CaMgSiO4), and aluminum calcium silicate (e.g., Al2O3, Ca2SiO2). A single silica or a combination of two or more types of silica can be used. The silica is used in the form of discrete particles, i.e., highly dispersed granules. It may be monodisperse in size and uniform in shape. Alternatively, it can be provided in the form of branched or linear clusters. Precipitated silica materials are preferred due to their ability to impart excellent rolling resistance and wet traction to tread components.

[0079] The rubber compositions described herein can use any known silica filler or different types of silica. Silica can be selected based on its specific surface area. The average specific surface area of ​​silica can be determined by nitrogen adsorption and cetyltrimethylammonium bromide (CTAB) adsorption using the Brunauer-Emmett-Teller (BET) method. The CTAB specific surface area is the external surface. The Brunauer-Emmett-Teller (BET) method is described in the Journal of the American Chemical Society, Vol. 60, page 309, February 1938, and corresponds to standard NF ISO 5794-1, Appendix D (June 2010). The cetyltrimethylammonium bromide (CTAB) adsorption method corresponds to ASTM D6845. The silica used in the present invention may have a BET specific surface area of ​​50 to 350 cm. 2 / g, preferably 60 to 320 cm 2 / g, e.g., 60-310 cm 2 The silica may have a CTAB specific surface area of ​​55 to 285 cm 2 / g, preferably 60 to 275 cm2 / g, e.g., 65-270cm 2 / g.

[0080] The silica used in the present invention may be functionalized or non-functionalized. The term "functionalized silica" refers to particulate silica having a surface modified with at least one functional group. The term "non-functionalized silica" should be interpreted accordingly. References herein to surface functionalization or the absence of surface functionalization of silica refer to the nature of the particulate silica added to the elastomer component in preparing the rubber composition of the present invention. Thus, "surface-functionalized" silica refers to "pre-functionalized" silica. Similarly, "non-functionalized" silica refers to silica that is not "pre-functionalized." Any silica used herein may be employed with one or more silane coupling agents, as described herein, which assist in bonding the silica to the elastomer component or components of the rubber composition.

[0081] In some embodiments, the silica used in the present invention may be non-functionalized. Commercial grades of this type are widely available from suppliers such as Solvay. These include silica materials supplied by Solvay under the trade names Zeosil® 1085GR and Zeosil® Premium SW MP. Zeosil® 1085GR has a BET specific surface area of ​​90 m 2 / g±20m 2 / g, and the CTAB specific surface area is 80m 2 / g±15m 2 / g. The BET specific surface area of ​​Zeosil® Premium SW MP is 260 m 2 / g, CTAB specific surface area is 250m 2 / g.

[0082] In some embodiments, the silica used in the present invention may be functionalized. The functional groups may be non-polar or polar in nature, and appropriate groups can be readily selected by one skilled in the art. For example, the silica may be surface-treated to reduce filler-filler interactions during compounding, thereby improving dispersibility in the rubber matrix. Suitable compatibilizers (also known as "covering agents") for this purpose are well known in the art and include, but are not limited to, monofunctional silanes such as hexadecyltrimethoxysilane or propyltriethoxysilane. As described herein, such coatings can be introduced during compounding of the various components to form the rubber composition. Other non-polar species that may adhere to the surface of the silica particles include aromatic groups and saturated aliphatic hydrocarbons. In some embodiments, the silica surface may be functionalized with one or more polar functional groups, such as those containing amine or carboxyl groups.

[0083] In one set of embodiments, the functionalized silica may comprise silica surface-functionalized with one or more carboxyl groups. The carboxyl groups may be present as carboxylic acids and / or as derivatives such as salts or esters. Examples of such functionalized silica materials can be found in WO 2015 / 12133, the entire contents of which are incorporated herein by reference.

[0084] Other functionalized silicas may be known in the art or prepared using methods known in the art. The specific method depends on the nature of the functional group and can be easily selected by one skilled in the art. When the silica is functionalized with one or more carboxyl groups, the carboxyl groups can be derivatized by reacting the silica with one or more carboxylic acids to form the functionalized silica. Typically, this method involves a precipitation reaction to produce the silica, i.e., the silica becomes precipitated silica. The synthesis of silica functionalized with one or more carboxyl groups can be found, for example, in WO 2015 / 121333.

[0085] When carbon black is present, it can be carbon black or modified carbon black. For example, it can be furnace black, channel black, or lamp black. For example, the carbon black can be one or more selected from the following group: super ablation furnace (SAF) black, high ablation furnace (HAF) black, high-speed extrusion furnace (FEF) black, fine harness (FF) black, intermediate super ablation furnace (ISAF) black, semi-reinforcing furnace (SRF) black, medium processing channel black, hard processing channel black, and conductive channel black. Another usable carbon black is acetylene black. The carbon black can be in pelletized form or in a non-pelletized flocculent mass. A specific example of carbon black for use in the rubber composition of the present invention is CORAX® N234 from Orion Engineered Carbons.

[0086] In one embodiment, the filler used in the present invention may be a blend of silica and carbon black.

[0087] The rubber composition according to the present invention can be prepared using methods known in the art for preparing rubber compositions, such as compounding with other ingredients. These additional ingredients can include additional polymers, additional processing aids (e.g., oils, waxes, and plasticizers), cure systems (e.g., vulcanizing agents, vulcanization accelerators, and vulcanization accelerator coagents), antidegradants (e.g., antioxidants or antiozonants), pigments, fillers (e.g., silica and / or carbon black fillers described herein), compatibilizers for fillers (e.g., silane coupling agents or coating agents described herein), fibers, and the like. Those skilled in the art can readily select the combination of vulcanizable rubber compounds and the amounts of each for subsequent mixing and vulcanization depending on the particular rubber product desired.

[0088] The methods for preparing the rubber compositions described herein form further aspects of the invention. In another aspect, the invention therefore provides a process for producing a rubber composition, the process comprising the steps of compounding components (a), (b) and (c) as described herein.

[0089] In some embodiments, in addition to the first and second elastomers and hydrocarbon polymer additive components described herein, the vulcanizable composition can include one or more of the following: processing aids (e.g., oils), vulcanization activators (e.g., zinc oxide, stearic acid, etc.), vulcanizing agents (e.g., sulfur or sulfur-donating compounds, etc.), vulcanization accelerators, antidegradants (e.g., antioxidants, antiozonants, etc.), pigments, reinforcing fillers, compatibilizers, and silane coupling agents. Zinc oxide and stearic acid reduce vulcanization time and act as activators in the vulcanization process, affecting the length and number of crosslinks formed in the rubber matrix during cure or vulcanization. These additives can be selected and used in conventional amounts depending on the intended use of the sulfur vulcanizate.

[0090] Processing aids improve the processability of the composition and include oils such as mineral oils, vegetable oils, synthetic oils, or mixtures thereof. These can be used in amounts of about 5 to 75 phr, preferably about 10 to 50 phr. Typical processing aids contain oils such as aromatic oils. Examples of such oils include treated distillate aromatic extract (TDAE), residual aromatic extract (RAE), mild extract solvate (MES), and bio-based oilseed derivatives. The oil used in the rubber composition of the present invention is not particularly limited and may be any oil known to those skilled in the art. For example, the oil may be one or more selected from the group consisting of processing oils such as aromatic oils, naphthenic oils, and paraffinic oils, vegetable oils such as coconut oil, and synthetic oils such as alkylbenzene oils and castor oil. Preferably, the oil is an aromatic oil, such as residual aromatic extract oil.

[0091] The vulcanizing agent for the rubber composition is not particularly limited and may be any commonly known agent in the art. For example, the vulcanizing agent may be sulfur. The amount of vulcanizing agent is not particularly limited, and one skilled in the art can easily select an amount effective to achieve satisfactory cure of the composition. The vulcanizing agent (e.g., sulfur) may be used in an amount ranging from about 0.1 to 10 phr, preferably from about 0.1 to 5 phr, for example, from about 0.2 to about 3 phr. For example, the rubber composition may contain 0.2 to 2 phr, preferably 0.5 to 1.5 phr, for example, 0.5 to 1 phr, of the vulcanizing agent.

[0092] The vulcanization accelerator used in the rubber composition is not particularly limited, and any accelerator generally known in the art may be used, including thiazole-based, dithiocarbamate-based, thiuram-based, guanidine-based, and sulfonamide-based accelerators. Examples of suitable accelerators include thiazole-based accelerators such as 2-mercaptone benzothiazole (MBT), dibenzothiazyl disulfide (MBTS), N-cyclohexyl-2-benzothiazyl sulfenamide (CBS), and N-tert-butyl-2-benzothiazolylsulfenamide (TBBS); guanidine-based accelerators such as 1,3-diphenylguanidine; thiuram-based accelerators such as tetramethylthiuram disulfide, tetrabutylthiuram disulfide, tetradodecylthiuram disulfide, tetraoctylthiuram disulfide, and tetrabenzylthiuram disulfide; and dithiocarbamate compounds such as zinc dithiocarbamate; and other dialkyldithiophosphates. Preferably, the vulcanization accelerator may be a combination of dibenzothiazyl disulfide (MBTS), N-cyclohexyl-2-benzothiazyl sulfenamide (CBS), and 1,3-diphenylguanidine (DPG). The amount of the vulcanization accelerator used in the composition is not particularly limited and may be, for example, about 0.5 to about 10 phr, preferably about 1 to about 8 phr, and more preferably about 2 to about 6 phr. Preferably, the vulcanization accelerator may contain 1 to 2 phr of dibenzothiazyl disulfide (MBTS), 0.5 to 2 phr of N-cyclohexyl-2-benzothiazyl sulfenamide (CBS), and 1 to 3 phr of 1,3-diphenylguanidine (DPG).

[0093] The auxiliary vulcanization accelerator used in the rubber composition is not particularly limited and may be any known to those skilled in the art. For example, the auxiliary vulcanization accelerator may be zinc oxide (ZnO) and a fatty acid. The fatty acid may be saturated or unsaturated, straight-chain or branched. The number of carbon atoms in the fatty acid is also not particularly limited, but may be 1 to 3 or 15 to 30. For example, the fatty acid may be one or more selected from the following group: saturated fatty acids such as cyclohexanoic acid (cyclohexanecarboxylic acid), naphthenic acids with side chains such as alkylcyclopentane, hexanoic acid, and octanoic acid; unsaturated fatty acids such as decanoic acid (including branched carboxylic acids such as neodecanoic acid), dodecanoic acid, tetradecanoic acid, hexadecanoic acid, and octadecanoic acid (stearic acid); unsaturated fatty acids such as oleic acid, linoleic acid, and linolenic acid; and resin acids such as rosin, tall oil acid, and abietic acid. Preferably, the auxiliary vulcanization accelerator of the present invention is zinc oxide (ZnO) and stearic acid. The total amount of auxiliary vulcanization accelerators is not particularly limited, but can be 1 to 10 phr, preferably 1.5 to 7 phr, for example, 2 to 5 phr. Zinc oxide can be used in an amount of about 1 to about 10 phr, preferably about 2 to about 5 phr, more preferably about 2 to about 3 phr. Stearic acid can be used in an amount of about 1 to about 5 phr, preferably about 1.5 to about 3 phr.

[0094] As described herein, additional reinforcing fillers such as silica and carbon black may also be present in the rubber compositions of the present invention. In some embodiments, the rubber composition further comprises a silica filler, in the range of 50 to 110 phr, preferably 55 to 90 phr, for example, 60 to 80 phr or 60 to 70 phr, or 60 to 65 phr.

[0095] The amount of carbon black that can be present is not particularly limited, but can range from 0.1 to 10 phr, such as from 0.5 to 5 phr, or from 1 to 4 phr, such as from 2 to 3 phr.

[0096] The rubber composition may contain fillers known to those skilled in the art. For example, the rubber composition may contain one or more selected from the following group: aluminum hydroxide, talc, alumina (Al2O3), aluminum hydrate (Al2O3.H2O), aluminum hydroxide (Al(OH)3), aluminum carbonate (Al2(CO3)2), magnesium aluminum oxide (MgOAl2O3), pyrophyllite (Al2O3.4SiO2.H2O), bentonite (Al2O3.4SiO2.2H2O), mica, kaolin, glass balloons, glass beads, calcium oxide, etc. The fillers may include calcium (CaO), calcium hydroxide (Ca(OH)2), calcium carbonate (CaCO3), magnesium carbonate, magnesium hydroxide (Mg(OH)2), magnesium oxide (MgO), magnesium carbonate (MgCO3), potassium titanate, barium sulfate, zirconium oxide (ZrO2), zirconium hydroxide (Zr(OH)2nH2O), zirconium carbonate (Zn(CO3)2), crystalline aluminosilicates, reinforced grade zinc oxide (i.e., toughened zinc oxide), etc. If present, the amount of additional fillers may be 5 to 200 phr, e.g., 10 to 150 phr or 25 to 100 phr.

[0097] The antidegradant used in the rubber composition of the present invention is not particularly limited and may be any known to those skilled in the art. The antidegradant may be an antioxidant and / or an antiozonant. For example, the antidegradant may include one or more selected from the following group, such as N-(1,3-dimethylbutyl)N'-phenyl-p-phenylenediamine (6PPD) and 2,2,4-trimethyl-1,2-dihydroquinoline polymer (TMQ). Preferably, the antidegradant is a combination of N-(1,3-dimethylbutyl)N'-phenyl-p-phenylenediamine (6PPD) and 2,2,4-trimethyl-1,2-dihydroquinoline polymer (TMQ). The amount of each antidegradant may be 0.1 to 3 phr, preferably 0.2 to 2 phr. The amount of the antidegradant may be 0.1 to 5 phr, preferably 1 to 3 phr.

[0098] A coating agent can be used to inhibit the formation of silica aggregates during formulation. When present, the coating agent can be used in an amount of up to 5 phr, preferably about 1 to about 3 phr. In one embodiment, no additional coating agent is present. The coating agent is not particularly limited and can be any known in the art. Suitable silica-based coating agents include silanes such as alkylalkoxysilanes, e.g., hexadecyltrimethoxysilane, octyltriethoxysilane, and hexyltrimethoxysilane. In one embodiment, the coating agent can be pre-grafted onto the polymer. The coating agent can be used in a free state (i.e., not pre-grafted) or grafted onto the surface of the silica.

[0099] A coupling agent may be present to bind to the silanol groups of the silica to inhibit silica agglomeration and to covalently bond the silica filler to the styrene-butadiene copolymer. The appropriate amount of coupling agent can be determined by one skilled in the art, taking into account factors such as the molecular weight, number of functional groups, and reactivity. Most coupling agents can be used in equimolar amounts based on the amount of silica. The coupling agent used in the rubber composition of the present invention is not particularly limited and can be any known to those skilled in the art. In one embodiment, the coupling agent may be pre-grafted onto the polymer. It may also be used in a free state (i.e., not pre-grafted) or grafted to the surface of the silica.

[0100] Typically, the coupling agent is a silane coupling agent, such as a bifunctional silane. For example, the silane coupling agent may comprise one or more selected from the following group: bis(3-triethoxysilylpropyl)tetrasulfide, bis(3-triethoxysilylpropyl)trisulfide, bis(3-triethoxysilylpropyl)disulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, 3-trimethoxysilylpropyl-N'N-dimethylthiocarbamoyltetrasulfide, 3-triethoxy ... Examples of silane coupling agents include silane propyl-N'N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N'N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropyl benzothiazolyl tetrasulfide, 3-triethoxysilylpropyl benzothiazolyl tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, bis(3-diethoxymethylsilylpropyl)tetrasulfide, 3-mercaptopropyldimethoxymethylsilane, dimethoxymethylsilylpropyl-N'N-dimethylthiocarbamoyl tetrasulfide, and dimethoxymethylsilylpropyl benzothiazolyl tetrasulfide. Preferably, the silane coupling agent is bis(3-triethoxysilylpropyl)tetrasulfide. A specific example of a silane coupling agent used in the present invention is Si69® from Evonik Industries AG. The amount of the silane coupling agent is not particularly limited, but can be 2 to 20 phr, preferably 5 to 18 phr, more preferably 7 to 16 phr, for example 9 to 15 phr.

[0101] Rubber compositions according to the present invention can be prepared by methods known in the art by mixing (i.e., compounding) the first elastomer, the second elastomer, the hydrocarbon polymer additive component, and any other components described herein to produce a rubber composition for subsequent vulcanization.

[0102] According to a further aspect, the present invention provides a method for producing a rubber article, the method comprising the steps of compounding a rubber composition as described herein to form a rubber compound, forming (e.g., molding) the rubber compound into a desired shape, and vulcanizing the rubber compound.

[0103] In preparing the rubber composition of the present invention, the method of compounding each component is not particularly limited, and any method known in the art may be used. To mold the rubber composition into a desired shape, a molding machine such as an extruder or a press molding machine can be used.

[0104] The mixing of the components is usually carried out in stages in which the components can be added. To optimize the dispersion of the silica filler system, a multi-step mixing process is generally preferred and may involve the use of multiple mixers, e.g., different mixers arranged in series. For example, when mixing a tire tread compound, the mixing process may include an initial mix stage to prepare a masterbatch, followed by one or more additional non-productive mix stages, and finally a productive mix stage to add the curatives (i.e., sulfur or sulfur donors and accelerator(s)). Mixers that can be used are well known in the art and include, for example, open mills or Banbury-type mixers with tangential or cross-reversing rotors.

[0105] Typically, the first and second elastomers, hydrocarbon polymer additive component, filler (if present), additional processing aids (if present), zinc oxide, stearic acid, antidegradants (e.g., antioxidants, antiozonants), pigments, compatibilizers, and coupling agents (if present) are mixed to produce an initial masterbatch. The initial masterbatch may be followed by a non-productive mix stage in which no additional components are added. The non-productive mix stage may be used to further disperse components (e.g., fillers) within the rubber or to further reduce the viscosity of the mixed rubber compound.

[0106] During mixing, the temperature is maintained below a predetermined level to avoid premature crosslinking of the composition. Typically, the temperature can be maintained below 150°C, preferably below 140°C. For the preparation of the initial masterbatch, mixing can be carried out at a temperature of, for example, about 80 to about 110°C, e.g., about 100°C. During the non-productive mixing stage, the temperature can be increased to, for example, about 150°C, e.g., 130°C. If additional compatibilizer is added during mixing, mixing at a higher temperature is required to ensure reaction with the silica surface (if silica filler is present). Mixing times vary but can be easily determined by one skilled in the art based on the composition of the mixture and the type of mixer used. Generally, a mixing time of at least 1 minute, preferably 2 to 30 minutes, is sufficient to obtain the desired homogeneous composition.

[0107] The final mix stage includes the addition of curatives, including accelerators and antidegradants. The temperature during this mix stage is generally low, for example in the range of about 40° C. to about 60° C., e.g., 50° C. This final mix may be followed by a non-productive mix stage in which no additional ingredients are added.

[0108] To obtain a vulcanizable rubber compound, the most appropriate type of mixing can be easily selected. The mixing speed can be easily determined, but can be, for example, in the range of about 20 to 100 rpm, for example, about 30 to about 80 rpm, preferably about 50 rpm.

[0109] The vulcanizable rubber compound may be provided as an uncured (so-called "green") tire component for the final granules to be cured. Curing to crosslink the rubber component can be carried out by known methods. In the tire industry, for example, uncured rubber (so-called "green body") is produced and then cured in a press mold to crosslink the rubber component while simultaneously molding the component into the final tire. Vulcanization cures the rubber by crosslinking, primarily via sulfur crosslinking. Vulcanization methods and conditions for curing rubber compositions are well known to those skilled in the art. Suitable vulcanization conditions typically include heating to a temperature in the range of 120 to 200°C, e.g., 140 to 180°C, for 5 to 180 minutes, e.g., 5 to 120 minutes.

[0110] A vulcanizable rubber composition forms a further aspect of the present invention. In another aspect, the present invention therefore provides a vulcanizable rubber composition comprising: (a) a first elastomer comprising one or more styrene-butadiene copolymers having a Tg in the range of -40 to -15°C; (b) a second elastomer comprising natural rubber; and (c) a hydrocarbon polymer additive component, (i) a first hydrocarbon polymer additive that is a partially hydrogenated C5 resin; and (ii) a second hydrocarbon polymer additive which is a fully hydrogenated hydrocarbon resin selected from the group consisting of hydrogenated C5 resin, hydrogenated C5 / C9 copolymer resin, hydrogenated C9 resin, and combinations thereof; the hydrocarbon polymer additive component comprising Equipped with.

[0111] Vulcanizable rubber compounds obtained, directly obtained or obtainable by crosslinking the vulcanizable rubber compositions according to the invention also form part of the present invention.

[0112] Methods for producing vulcanized rubber compositions also form part of the invention. In another aspect, the present invention therefore provides a process for producing a vulcanized rubber composition, the process comprising the steps of compounding components (a), (b), and (c) as described herein, and subjecting the vulcanizable rubber composition to vulcanization by heating to a predetermined temperature and for a predetermined time. The process comprises compounding components (a), (b), and (c) as described herein, thereby producing a vulcanizable rubber composition, and vulcanizing the vulcanizable rubber composition by heating to a predetermined temperature and for a predetermined time.

[0113] The rubber compositions described herein find particular use in the manufacture of vehicle tires, and particularly in the manufacture of tire components such as tire treads. While the tire treads can be used in tires for any vehicle, they find particular use in the manufacture of automobile tire treads. Other uses for the rubber compounds include vibration dampers, sidewall rubber, innerliner rubber, bead filler rubber, body ply rubber, skim shock absorbers, and tread rubber.

[0114] In another aspect, the present invention therefore provides the use of a rubber composition as or in the manufacture of a vehicle tire component as described herein.

[0115] In another aspect, the present invention provides vehicle tire components, such as tire treads, made from the rubber compositions as described herein. Vehicle tires comprising the vehicle tire components also form part of this invention.

[0116] Methods for assembling and manufacturing tire components are well known in the art. Assembly of the "green" tire is followed by compression molding in a suitable mold where it is vulcanized to produce the finished tire.

[0117] The rubber compounds according to the invention may also be used in applications other than tires, such as the manufacture of hoses and seals.

[0118] The present invention can be further illustrated by the following non-limiting examples and accompanying figures. [Brief explanation of the drawings]

[0119] [Figure 1] Modulus of elasticity (E') at 30° C. of rubber compositions B, C, D and F according to the invention and of reference compositions A and E. All results are given as % increase / decrease relative to reference composition A. [Figure 2] Tan δ at 0° C. of rubber compositions B, C, D and F according to the invention and of reference compositions A and E. All results are given as % increase / decrease relative to reference composition A. [Figure 3] Tan δ at 60° C. of rubber compositions B, C, D and F according to the invention and of reference compositions A and E. All results are given as % increase / decrease relative to reference composition A. [Figure 4] Abrasion resistance of rubber compositions B, C, D and F according to the invention and of reference compositions A and E. All results are given as % increase / decrease relative to reference composition A. [Figure 5] 1 is a graph showing the WEAR resistance as a function of wet braking in tire tests carried out on a rubber composition C according to the invention and on reference compositions A and E. All results are given as a % increase / decrease relative to reference composition A. The results for rubber compositions A and C are based on tests carried out on real tires. The results for rubber composition E have been extrapolated by comparing available tire data and test results.

[0120] (Test Procedure) 1. Elastic modulus (E') The elastic modulus (E') is used to evaluate grip performance. Dynamic physical testing for measuring E' at 30°C was performed according to ISO 4664.

[0121] 2. Loss factor (Tanδ) Loss factor (Tangent δ or Tan δ) at different temperatures is used to evaluate rolling resistance and wet traction. Tan δ at low temperatures is an indicator of wet traction. An increase in Tan δ at low temperatures correlates with improved wet traction of a tread compound compared to a control compound. When developing a rubber composition for a tire tread to improve tire rolling resistance, the loss factor (Tan δ) at around 60°C is generally considered as an indicator. Using a tread rubber with a low Tan δ at around 60°C in a rubber composition can suppress tire heat generation, reduce rolling resistance, and therefore improve tire fuel economy. Therefore, Tan δ at 60°C is an indicator of rolling resistance (RR). A lower result compared to a control compound indicates reduced rolling resistance. Dynamic physical tests for measuring Tan δ were performed in accordance with ISO 4664.

[0122] 4. Abrasion resistance Abrasion resistance was determined according to ISO 4649.

[0123] 5. Tire testing The tire data is obtained from testing vehicles fitted with tires having tire treads made using the rubber compositions. Three different tire specifications are manufactured, each differing only in the tread rubber formulation; all other variables are held constant. The vehicles are driven at least 1000 km over the road surface, and the extent of wear (in mm) is measured (reduced groove depth). The wear life extension is determined by comparing the wear resistance of tread compound C according to the invention with reference compounds A and C.

[0124] (Preparation of Rubber Composition) material Rubber: Functionalized S-SBR 1 Non-functionalized S-SBR 2 natural rubber Hydrocarbon polymer additives (resins): Partially hydrogenated C5 / DCPD resin3 Fully hydrogenated C9 resin 4 Silica: Zeosil® Premium Super Wear MP 5 (Premium SW MP) (Solvay) Zeosil® 1085GR 6 (Manufactured by Solvay) Carbon Black: Corax® N234 (Orion Engineered Carbons, Luxembourg) Silane coupling agents: Si69® Low Tg oil: Octyl Oleate sulfur 1,3-diphenylguanidine (DPG) Dibenzothiazyl disulfide (MBTS) N-Cyclohexyl-2-benzothiazylsulfenamide (CBS) stearic acid Zinc oxide (ZnO) 1 Solution-polymerized, dried silica-functionalized styrene-butadiene random copolymer. 2 Solution polymerized, oil-extended styrene-butadiene random copolymer. Extended in 47.5 phr TDAE oil. 3 Partially hydrogenated C5 / DCPD copolymer resin with a softening point of 130°C, Tg of 75°C, and Mw of 840 g / mol. Approximately 95% hydrogenated. 4 Fully hydrogenated C9 resin with a softening point of 119-128°C, Tg of 65-75°C, and Mw of 1100g / mol. 98-100% hydrogenated. 5 BET specific surface area 260m 2 / g, CTAB specific surface area 250m 2 / g of non-functionalized silica, Zeosil® Premium Super Wear MP. 6 BET specific surface area 90m2 / g, CTAB specific surface area 80m 2 / g of non-functionalized silica, Zeosil® 1085GR.

[0125] Rubber compositions A through E were prepared by blending the ingredients shown in Table 1. The amounts in Table 1 are in parts by weight based on 100 parts by weight of rubber composition (PHR). The total amount of hydrocarbon polymer additive is constant for each composition, but the amount of each resin component varies. Compositions B, C, D, and F are rubber compositions according to the present invention and contain a first and a second hydrocarbon polymer additive. Composition F is identical to composition C, but further contains 6 phr of silica filler (and an increased amount of silane coupling agent). Compositions A and E are reference compositions. Composition A contains only the first hydrocarbon polymer additive, and composition B contains only the second hydrocarbon polymer additive.

[0126] [Table 1]

[0127] The ingredients shown in Table 1 are formulated according to the following general procedure. Non-productive mix stage: All ingredients except the vulcanization system are added to an intermesh Banbury mixer and mixed with the polymer base. During mixing, the temperature is initially maintained between 110-130°C and then increased to between 150-160°C. Productive Mix Stage: The mixture prepared in the non-productive mix stage is mixed with a vulcanization system at a temperature between 90 and 110°C to vulcanize the rubber composition.

[0128] (Rubber composition testing) Rubber compositions A through F were subjected to the test methods described herein. The results are shown in accompanying Figures 1 through 5, which illustrate the effect of the hydrocarbon polymer additive component (normalized to composition A) on the dynamic and wear performance of the rubber.

[0129] Figure 1 shows the modulus (E' at 30°C), a measure of stiffness, of each rubber composition. Reference compositions A and E show significantly higher moduli than inventive rubber compositions C and D, respectively. The lower moduli of compositions C and D indicate reduced rubber stiffness, improved grip, and improved wet performance. The results for inventive compositions C and D show a higher than expected additive effect of the two resins, thus demonstrating a synergistic effect.

[0130] Figure 2 shows the Tan δ at 0°C for each rubber composition. Reference compositions A and E have lower Tan δ at 0°C than compositions C and D of the present invention. The increase in Tan δ at 0°C indicates that the composition has superior wet performance due to the hysteresis effect. The results for compositions C and D of the present invention are higher than the expected additive effect of the two resins, thus indicating a synergistic effect.

[0131] FIG. 3 shows the Tan δ at 60°C of each rubber composition. Tan δ at 60°C indicates rolling resistance. Reference compositions A and E have higher Tan δ at 60°C than compositions C and D of the present invention. A lower Tan δ at 60°C indicates better rolling resistance performance due to the hysteresis effect. The effect of the composition of the present invention is higher than the expected additive effect of the two resins, thus indicating a synergistic effect.

[0132] Figure 4 shows the abrasion resistance of each rubber composition. The results show that the resin blend specification has little effect on abrasion resistance compared to reference compositions A and E, which contain only a single resin. Thus, resin blends can be used to adjust other properties (e.g., stiffness and hysteresis) without adversely affecting abrasion resistance.

[0133] It can also be seen from Figure 4 that the addition of an additional 6 phr of silica (composition F) improves wear resistance. Because the use of the blended resin significantly improves other dynamic properties of the rubber composition (Figures 1-3), additional silica can be added without adversely affecting the overall WET / WEAR / RR properties.

[0134] Figure 5 shows the WEAR resistance as a function of WET braking in tire tests carried out on the inventive composition C and the reference compositions A and E, respectively, confirming the improved balance of WEAR and WET performance for the inventive compositions.

Claims

1. A rubber composition comprising: (a) a first elastomer comprising one or more styrene-butadiene copolymers having a glass transition temperature Tg in the range of −40 to −15° C.; (b) a second elastomer comprising natural rubber; and (c) a hydrocarbon polymer additive component, (i) Partially hydrogenated C containing 5 mol % or more of olefinic protons ５ a first hydrocarbon polymer additive that is a resin; and (ii) Hydrogenated C ５ Resin, hydrogenated C ５ / C ９ Copolymer Resin, Hydrogenated C ９ a second hydrocarbon polymer additive which is a fully hydrogenated resin containing 0 to 3 mol % olefinic protons selected from the group consisting of resins and combinations thereof; the hydrocarbon polymer additive component comprising A rubber composition comprising:

2. 2. The rubber composition according to claim 1, wherein the first elastomer is present in an amount of 40 to 90 phr per 100 phr of the rubber composition.

3. 2. The rubber composition according to claim 1, wherein the second elastomer is present in an amount of 10 to 60 phr per 100 phr of the rubber composition.

4. 10. The rubber composition of claim 1, wherein the hydrocarbon polymer additive component is present in an amount of 5 to 25 phr, based on 100 phr of the rubber composition.

5. 10. The rubber composition of claim 1, wherein a weight ratio of said first hydrocarbon polymer additive to said second hydrocarbon polymer additive ranges from 20:80 to 80:

20.

6. 6. The rubber composition of claim 5, wherein the weight ratio of the first hydrocarbon polymer additive to the second hydrocarbon polymer additive ranges from 20:80 to 60:

40.

7. The rubber composition of claim 6 , wherein the weight ratio of the first hydrocarbon polymer additive to the second hydrocarbon polymer additive is 50:50 or 25:

75.

8. The rubber composition of claim 1, further comprising at least one reinforcing filler.

9. 9. The rubber composition according to claim 8, wherein the reinforcing filler comprises one or more silica fillers, and the one or more silica fillers are present in an amount ranging from 50 to 110 phr per 100 phr of the rubber composition.

10. 10. The rubber composition of claim 1, wherein the difference in olefinic proton content of the first and second hydrocarbon polymer additives is less than 10 mol%.

11. 2. The rubber composition of claim 1, wherein the first hydrocarbon polymer additive is a partially hydrogenated C ５ A rubber composition comprising a hydroxybenzoate / dicyclopentadiene (DCPD) copolymer.

12. The rubber composition of claim 1 , wherein the first hydrocarbon polymer additive comprises 5 mol % olefinic protons.

13. The rubber composition according to claim 1, wherein the first hydrocarbon polymer additive has a weight average molecular weight of 200 to 1200 g / mol and / or a softening point above 110°C.

14. 2. The rubber composition of claim 1, wherein the second hydrocarbon polymer additive is a fully hydrogenated C ９ A rubber composition that is a resin.

15. 10. The rubber composition of claim 1, wherein the second hydrocarbon polymer additive comprises 0 to 2 mol % olefinic protons.

16. The rubber composition according to claim 1, wherein the second hydrocarbon polymer additive has a weight average molecular weight of 700 to 1500 g / mol and / or a softening point above 100°C.

17. The rubber composition of claim 1, wherein the first elastomer component comprises at least one solution-polymerized styrene-butadiene copolymer (S-SBR).

18. The rubber composition of claim 1 , wherein the rubber composition is vulcanizable.

19. 20. A vulcanized rubber compound obtained, directly obtained or obtainable by crosslinking the rubber composition of claim 18.

20. A tire component made from the rubber composition of any one of claims 1 to 18 or the vulcanized rubber compound of claim 19.

21. A vehicle tire comprising the tire component of claim 20.

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