Patent Description:
To improve sustainability in the tire industry, there is an ongoing effort to develop rubber tire compositions from renewable sources. However, sustainable compositions must behave in predicted ways for a tire to perform to its intended purpose. Therefore, a sustainable rubber composition is desired from which there is little to no compromise in rubber performance.

In rubber tire compounds, each material and additive are combined with elastomers to impart specific properties in the resulting tire. Presently, several materials - resin and carbon black being two among them - are derived from a fossil (also referred to herein as "hydrocarbon") fuel source (i.e., petroleum, coal, or natural gas). Emissions from the manufacture of these petroleum-derived materials include organics, sulfur compounds, carbon monoxide (CO), and other contaminants. To lessen the environmental impact of such emissions, there is a desire to reduce, or altogether exclude, from rubber compounds the materials that originate from fossil fuel sources. However, previous technologies have made it difficult for one, let alone a combination of, bio-derived alternative materials to replicate the performance of conventional materials in tire compounds.

To meet the challenge of providing a tire rubber composition from sustainable, bio-renewable, environmentally friendly, and non-fossil fuel sources, it is desired to evaluate a rubber composition formed from a combination of materials including resin derived from a renewable resource.

<CIT> describes a rubber composition for a tire using two different polymers together with a polyterpene resin, silica and carbon black. A similar rubber composition is also known from <CIT>.

The invention relates to a tire component in accordance with claim <NUM>. Dependent claims refer to preferred embodiment of the invention.

One embodiment of the disclosure relates to a tire component formed from a rubber composition comprising a majority weight percent of renewable materials. The rubber composition comprises, based on <NUM> parts per weight (phr) of elastomer:.

In the contemplated embodiment, the carbon black filler is derived from a bio-based feedstock prior to its addition to the rubber composition. The resin and the silica are also derived from renewable materials.

If an SSBR is used on the rubber composition, it may be functionalized or not functionalized.

The present disclosure relates to a rubber composition containing a majority weight percent of renewable content. The disclosure further relates to a tire component comprising said rubber composition.

As used herein, the terms "compounded rubber", "rubber compound" and "compound" refer to rubber compositions containing elastomers which have been compounded, or blended, with appropriate rubber compounding ingredients. The terms "rubber" and "elastomer" and "polymer" may be used interchangeably unless otherwise indicated.

As used herein, except where context requires otherwise, the term "comprise" and variations of the term, such as "comprising", "comprises" and "comprised", are not intended to exclude further additives, components, integers, or steps.

As used herein, the term "bio-based" or "bio-derived" refers to a material derived from a renewable or sustainable resource or natural source. It may include an industrial source when, for example, a byproduct or waste product is being captured and reused to reduce or eliminate emissions harmful to the environment. One example is the sequestration of carbon oxides for use as feedstock.

As used herein, "renewable" and "sustainable" are used interchangeably and hereafter comprises recycled material as well; "content" and "material" are used interchangeably.

It fully excludes radiocarbon and fossil carbon materials derived from petroleum, coal, or a natural gas source. Examples of resources from which the bio-based material can be derived include fresh (or from the fermentation of) biomass material, such as corn and vegetable oil.

A key aspect of the disclosure is the percent weight content of renewable content achieved using a combination of various renewable materials. A further aspect of the disclosed rubber composition is that the performance of a cured rubber composition with a majority weight percent of renewable content matches or improves on the tread (wet, wear, and rolling resistance) performance of conventional rubber compositions made from petroleum-derived materials.

In this application, the glass transition temperature Tg for polymers is determined as a peak midpoint by a differential scanning calorimeter (DSC) at a temperature rate of increase of <NUM> per minute, according to ASTM D3418-<NUM> or equivalent.

In this application, the glass transition temperature Tg for resins is determined as a peak midpoint by a differential scanning calorimeter (DSC) at a temperature rate of increase of <NUM> per minute, according to ASTM D6604 or equivalent.

In this application, the glass transition temperature Tg for oils is determined as a peak midpoint by a differential scanning calorimeter (DSC) at a temperature rate of increase of <NUM> per minute, according to ASTM E1356 or equivalent.

In this application, the softening point of hydrocarbon resins is determined according to ASTM E28 (or E28-58T), or equivalent, which might sometimes be referred to as a ring and ball softening point.

The disclosed rubber composition comprises a blend of at least two rubber, and more particularly conjugated diene-based, elastomers. In practice, various conjugated diene-based elastomers may be used for the rubber composition such as, for example, polymers and copolymers of at least one of isoprene and <NUM>,<NUM>-butadiene and of styrene copolymerized with at least one of isoprene and <NUM>,<NUM>-butadiene. Representative of such conjugated diene-based elastomers are, for example, comprised of at least one of cis <NUM> ,<NUM>-polyisoprene (natural and synthetic), cis <NUM>,<NUM>-polybutadiene, styrene/butadiene copolymers, medium vinyl polybutadiene having a vinyl <NUM> ,<NUM>-content in a range of <NUM> to <NUM> percent, isoprene/butadiene copolymers, and styrene/isoprene/butadiene terpolymers.

In practice, the preferred rubber or elastomers are polyisoprene (natural or synthetic), polybutadiene and SBR. In further embodiment, the rubber elastomers are polyisoprene and polybutadiene. In one embodiment, the polybutadiene is present in a majority amount. In a preferred embodiment, the polyisoprene is present in a majority amount.

In one embodiment, the rubber composition comprises from <NUM> phr to <NUM> phr polybutadiene and, more preferably, from <NUM> phr to <NUM> phr of polybutadiene. In one embodiment, the rubber composition comprises up to <NUM>% weight percent of polybutadiene.

In practice, it is envisioned that the cis <NUM>,<NUM>-polybutadiene elastomer may be a neodymium catalyst prepared cis <NUM> ,<NUM>-polybutadiene rubber which may be prepared, for example, by polymerization of <NUM>,<NUM>-polybutadiene monomer in an organic solvent solution in the presence of a catalyst system comprised of neodymium compound. However, such <NUM>,<NUM>-polybutadiene can be prepared by organic solution nickel catalysis of cis <NUM>,<NUM>-budadiene rubber instead.

Representative of such neodymium catalyst prepared cis <NUM>,<NUM>-polybutdiene is, for example, BUD <NUM>™ from The Goodyear Tire & Rubber Company and CB25™ from Lanxess.

The cis <NUM>,<NUM>-polyisoprene and cis <NUM>,<NUM>-polyisoprene natural rubber are well known to those having skill in the rubber art. In practice, a second rubber polymer can include a polyisoprene. In one embodiment, the polyisoprene can be present in a minority amount. In another embodiment, the polyisoprene can be present in a majority amount. In practice, the preferred rubber or elastomers include polyisoprene (natural or synthetic) in some amount. In one embodiment, the rubber composition comprises up to <NUM> phr of polyisoprene, preferably in the form of natural rubber. In one embodiment, the rubber composition comprises at least <NUM> phr of polyisoprene, preferably in the form of natural rubber. In certain embodiments, the rubber composition comprises from <NUM> phr to <NUM> phr of polyisoprene in the form of natural rubber. In one embodiment, the rubber composition comprises from <NUM> to <NUM>% weight percent, and more preferably from <NUM> to <NUM>% weight percent, of polyisoprene.

In one contemplated embodiment, at least one rubber polymer includes a styrene-butadiene rubber. Styrene/butadiene copolymers include those prepared by aqueous emulsion polymerization (ESBR) and organic solvent solution polymerization (SSBR). In one embodiment, a solution polymerization prepared SBR (SSBR) is also contemplated, which typically has a bound styrene content in a range of <NUM> to <NUM> percent. However, embodiments are contemplated in which the SSBR has a bound styrene content of greater than <NUM> percent, such as <NUM>%.

The rubber composition can comprise up to <NUM> phr or up to <NUM> phr of the styrene-butadiene rubber. In one embodiment, the rubber composition comprises ESBR and SSBR. In one embodiment, the rubber composition comprises SSBR and excludes ESBR. For embodiments in which the blend of rubber polymers comprises SSBR, the SSBR may be present in an amount of from <NUM> phr to <NUM> phr and, more preferably, from <NUM> to <NUM> phr. In certain embodiments, the rubber composition comprises up to <NUM>% weight percent of SSBR.

The SSBR can be conveniently prepared, for example, by organo lithium catalyzation in the presence of an organic hydrocarbon solvent. In one embodiment, the SSBR is not functionalized. In one embodiment, at least one rubber polymer, such as the SSBR, can be functionalized.

Representative of functionalized elastomers are, for example, styrene/butadiene elastomers containing one or more functional groups comprising:.

For the functionalized elastomers, representatives of amine functionalized SBR elastomers are, for example, in-chain functionalized SBR elastomers described in <CIT>.

Representative of a combination of amino-siloxy functionalized SBR elastomers with one or more amino-siloxy groups connected to the elastomer is, for example, HPR355™ from JSR and amino-siloxy functionalized SBR elastomers described in <CIT>.

Representative styrene/butadiene elastomers end functionalized with a silane-sulfide group are, for example, described in <CIT> and <CIT>.

It is further contemplated that, in certain embodiments, the rubber elastomer may be a butyl type rubber, particularly copolymers of isobutylene with a minor content of diene hydrocarbon(s), such as, for example, isoprene and halogenated butyl rubber.

It is further contemplated that, in certain embodiments, the elastomer may comprise a halobutyl rubber comprising a blend consisting of clorobutyl rubber, bromobutyl rubber and mixtures thereof.

Tin coupled elastomers may also be used, such as, for example, tin coupled organic solution polymerization prepared styrene/butadiene co-polymers, isoprene/butadiene copolymers, styrene/isoprene copolymers, polybutadiene and styrene/isoprene/butadiene terpolymers including the aforesaid functionalized styrene/butadiene elastomers.

By desiring the rubber composition to contain fewer to no materials derived from petroleum, it is meant that the rubber composition will contain minimal, if any, petroleum-based processing oil. For example, it is desired that the rubber composition be limited to from zero to <NUM> phr of petroleum-based processing oil and, more preferably, less than <NUM> phr of rubber petroleum-based processing oil.

In one embodiment, the rubber composition may comprise up to <NUM> phr of rubber processing oil. In another embodiment, the rubber composition may comprise no less than <NUM> phr of rubber processing oil. In practice, the composition may comprise from <NUM> to <NUM> phr of rubber processing oil and, more preferably, from <NUM> to <NUM> phr of rubber processing oil. Processing oil may be included in the rubber composition as extending oil typically used to extend elastomers. Processing oil may also be included in the rubber composition by addition of the oil directly during rubber compounding. The processing oil used in the rubber composition may include both extending oil present in the elastomers and process oil added during compounding. Suitable process oils include various oils as are known in the art, including aromatic, paraffinic, naphthenic, vegetable triglyceride oils, and low PCA oils, such as MES, TDAE, SRAE and heavy naphthenic oils. Suitable low PCA oils include those having a polycyclic aromatic content of less than <NUM> percent by weight as determined by the IP346 method. Procedures for the IP346 method may be found in <NPL>.

A suitable vegetable triglyceride oil comprises a combination of saturated and unsaturated esters where the unsaturated esters comprise a combination of at least one of oleic acid ester, linoleate acid ester and linoleate acid ester. The saturated esters may comprise, for example, at least one of stearic acid ester and palmitic acid ester.

In one embodiment, the vegetable triglyceride oil comprises at least one of soybean oil, sunflower oil, rapeseed oil, and canola oil, which are in the form of esters containing a certain degree of unsaturation. Other suitable examples of vegetable triglyceride oil include corn, coconut, cottonseed, olive, palm, peanut, and safflower oils. In practice, the oil includes at least one of soybean oil and sunflower oil.

In the case of soybean oil, for example, the above represented percent distribution, or combination, of the fatty acids for the glycerol tri-esters, namely the triglycerides, is represented as being an average value and may vary somewhat depending primarily on the type, or source of the soybean crop, and may also depend on the growing conditions of a particular soybean crop from which the soybean oil was obtained. There are also significant amounts of other saturated fatty acids typically present, though these usually do not exceed <NUM> percent of the soybean oil.

The contemplated embodiment comprises between <NUM>% and <NUM>% weight percent of a bio-derived rubber processing oil in the composition. In one embodiment, the rubber processing oil material makes up from <NUM>% weight percent and <NUM>% weight percent of the composition.

An important aspect of the present disclosure is the use of a bio-derived resin material fully in place of a petroleum resin. Conventional resins are derived from petroleum. These type of resins include any hydrocarbon chemistry type resin (AMS, coumarone-indene, C5, C9, C5/C9, DCPD, DCPD/C9, others) & any modification thereof (phenol, C9, hydrogenation, recycled monomers, others). The embodiment employs a renewable biobased chemistry type resin & modification and mixture thereof. Representative resins can also include coumarone type resins, including coumarone-indene resins and mixtures of coumarone resins, naphthenic oils, phenol resins, and rosins. Other suitable resins include phenol-terpene resins such as phenol-acetylene resins, phenol-formaldehyde resins, alkyl phenol-formaldehyde resins, terpene-phenol resins, polyterpene resins, and xylene-formaldehyde resins.

Terpene-phenol resins may be used. Terpene-phenol resins may be derived by copolymerization of phenolic monomers with terpenes such as limonenes, pinenes and delta-<NUM>-carene. In one embodiment, the resin can be an alpha pinene resin characterized by a softening point Tg between <NUM> and <NUM>.

In one embodiment, the resin is a resin derived from rosin and derivatives. Representative thereof are, for example, gum rosin, wood rosin and tall oil rosin. Gum rosin, wood rosin and tall oil rosin have similar compositions, although the amount of components of the rosins may vary. Such resins may be dimerized, polymerized or disproportionated. Such resins may be in the form of esters of rosin acids and polyols such as pentaerythritol or glycol.

In one embodiment, said resin may be partially or fully hydrogenated.

In one embodiment, the rubber composition comprises from <NUM> to <NUM> phr of at least one resin and, more preferably, from <NUM> to <NUM> phr of a bio-derived resin, although embodiments are contemplated in which another resin of a different type can be added to the composition as well. In one embodiment, the rubber composition comprises no less than <NUM> phr of resin and, more preferably, no less than <NUM> phr of resin. In one embodiment, the rubber composition comprises no less than <NUM> phr of resin and no more than <NUM> phr of resin.

The contemplated embodiment comprises between <NUM>% and <NUM>% weight percent of a bio-resin material in the composition. In one embodiment, the resin material makes up from <NUM>% weight percent and <NUM>% weight percent of the composition.

The disclosed rubber composition comprises <NUM>-<NUM> phr of silica filler. In one embodiment, the composition comprises at least <NUM> phr of silica. In one embodiment, the composition comprises no less than <NUM> phr of silica.

In one embodiment, the silica comprises:.

In one embodiment the precipitated silica is derived from naturally occurring inorganic sand (e.g., SiO<NUM>, silicon dioxide, which may contain a trace mineral content). The inorganic sand is typically treated with a strong base such as, for example, sodium hydroxide, to form an aqueous silicate solution (e.g., sodium silicate). A synthetic precipitated silica is formed therefrom by controlled treatment of the silicate with an acid (e.g., a mineral acid and/or acidifying gas such as, for example, carbon dioxide). Sometimes an electrolyte (e.g., sodium sulfate) may be present to promote formation of precipitated silica particles. The recovered precipitated silica is an amorphous precipitated silica.

In a preferred embodiment, the silica is a rice husk derived precipitated silica. Such precipitated silica is from derived rice plant husks (e.g., burnt ashes from rice husks) which contain SiO<NUM>, silicon dioxide, and which may contain trace minerals from the soil in which the rice has been planted). In a similar methodology, the rice husks (e.g. rice husk ash) is typically treated with a strong base such as, for example, sodium hydroxide, to form an aqueous silicate solution (e.g. sodium silicate) following which a synthetic precipitated silica is formed therefrom by controlled treatment of the silicate with an acid (e.g. a mineral acid and/or acidifying gas such as, for example, carbon dioxide) in which an electrolyte (e.g. sodium sulfate) may be present to promote formation of precipitated silica particles derived from rice husks. The recovered precipitated silica is an amorphous precipitated silica. For example, see <CIT>. In a preferred embodiment, the rubber composition comprises between <NUM> and <NUM> weight percent of rice husk ash silica and, more preferably, between <NUM> and <NUM> weight percent of rice husk ash silica.

The precipitated silica, whether derived from the aforesaid silicon dioxide or rice husks, may, for example, have a BET surface area, as measured using nitrogen gas, in the range of, for example, <NUM> to <NUM>, and more usually in a range of <NUM> to <NUM> square meters per gram. The BET method of measuring surface area might be described, for example, in the <NPL>, as well as ASTM D3037. Such precipitated silicas may, for example, also have a dibutyl phthalate (DBP) absorption value, for example, in a range of <NUM> to <NUM>, and more usually <NUM> to <NUM> cc/<NUM>.

Other embodiments are contemplated in which the silica is used in combination with another filler, such as carbon black.

In one embodiment, the rubber composition optionally comprises, based on <NUM> parts by weight (phr) of elastomer, from <NUM> to <NUM> phr of carbon black. In one embodiment, the rubber composition comprises no more than <NUM> phr of carbon black. In another embodiment, the rubber composition comprises no less than <NUM> phr of carbon black and, in certain embodiments, no less than <NUM> phr of carbon black. In one embodiment, the rubber composition comprises from <NUM> to <NUM> phr of carbon black. The carbon black is a bio-based carbon black.

The ASTM-D6866 method to derive "bio-based" content is built on the same concepts as radiocarbon dating, but without use of the age equations. The method relies on determining a ratio of the amount of radiocarbon (<NUM>C) in an unknown sample to that of a modern reference standard. The ratio is reported as a percentage with the units "pMC" (percent modern carbon). If the material being analyzed is a mixture of present-day radiocarbon and fossil carbon (fossil carbon being derived from petroleum, coal or a natural gas source), then the obtained pMC value correlates directly to the amount of biomass material present in the sample.

The modern reference standard used in radiocarbon dating is a National Institute of Standards and Technology USA (NIST-USA) standard with a known radiocarbon content equivalent approximately to the year AD <NUM>, before excess radiocarbon was introduced into the atmosphere. AD <NUM> represents zero (<NUM>) years old and <NUM> pMC. Present day (fresh) biomass materials, and materials derived therefrom, give a radiocarbon signature near <NUM>.

The radiocarbon dating isotope (14C) has a nuclear half-life of <NUM> years. Fossil carbon, depending upon its source, has very close to zero 14C content. By presuming that <NUM> pMC represents present day biomass materials and <NUM> pMC represents petroleum (fossil carbon) derivatives, the measured pMC value for a material will reflect the proportions of the two component types. Thus, a material derived <NUM>% from present day vegetable oil would give a radiocarbon signature near <NUM> pMC. If that material was diluted with <NUM>% petroleum derivatives, it would give a radiocarbon signature near <NUM> pMC.

A biomass content result is derived by assigning <NUM>% equal to <NUM> pMC and <NUM>% equal to <NUM> pMC. In this regard, a sample measuring <NUM> pMC will give an equivalent bio-based content result of <NUM>%. This value is referred to as the "mean biobased result" and assumes all the components within the analyzed material were either present day living or fossil in origin.

The results provided by the ASTM D6866 method are the mean biobased result and encompass an absolute range of <NUM>% (±<NUM>% on either side of the mean bio-based result) to account for variations in end-component radiocarbon signatures. It is presumed that all materials are present day or fossil in origin. The result is the amount of bio-based component "present" in the material-not the amount of bio-based material "used" in the manufacturing process.

In one embodiment, a tire component is formed from a rubber composition comprising a carbon black filler having a greater than one percent (<NUM>%) modern carbon content as defined by ASTM D6866. The carbon black is produced from a bio-based feedstock prior to its addition to the rubber composition. The carbon black is completely devoid of fossil carbon.

In one embodiment, the bio-based feedstock, from which the carbon black is derived, comprises at least one triglyceride vegetable oil, such as, for example, soybean oil, sunflower oil, canola oil, rapeseed oil, or combinations thereof. In one embodiment, the bio-based feedstock, from which the carbon black is derived, comprises at least one plant biomass, animal biomass and municipal waste biomass, or combinations thereof.

In one embodiment, the carbon black has at least <NUM>% modern carbon content. In one embodiment, the carbon black has at least <NUM>% and, more preferably, at least <NUM>% and, most preferably, at least <NUM>% modern carbon content. In one embodiment, the carbon black has a biomass content result of at least <NUM> pMC and, more preferably, at least <NUM> pMC. In one embodiment, the carbon black may have a biomass content result of at least <NUM> pMC.

Other embodiments are contemplated that employ a carbon-dioxide generated carbon reinforcing filler. Suitable carbon dioxide-generated carbon reinforcement may be produced using methods as described in <CIT>; <CIT>; and <CIT>.

Various combinations of carbon blacks can also be employed in the disclosed rubber composition. Representative examples of rubber reinforcing carbon blacks are, for example, and not intended to be limiting, referenced in<NPL> with their ASTM designations. Such rubber reinforcing carbon blacks may have iodine absorptions ranging from, for example, <NUM> to <NUM>/kg and DBP values ranging from <NUM> to <NUM> cc/<NUM>.

Representative of silica coupler for said precipitated silica are:.

Representative of such bis(<NUM>-trialkoxysilylalkyl) polysulfide comprises bis(<NUM>-triethoxysilylpropyl) polysulfide.

The silica, discussed supra, is desirably added to the rubber composition in combination with the bis(<NUM>-triethoxysilylpropyl) polysulfide for reaction thereof in situ within the rubber composition.

In one embodiment, the composition comprises between <NUM> phr and <NUM> phr of coupling agent and, more preferably, between from <NUM> phr and <NUM> phr of coupling agent.

Another aspect of the present disclosure is the addition of a bio-derived processing aid for the rubber composition. In a preferred embodiment, the processing aid can be a blend of bio-based fatty acid derivatives and/or bio-based fatty acid derivative(s). The processing aid can have a softening point (Tg) in the range of from <NUM> to <NUM>. Generally, from <NUM> to <NUM> phr and, more preferably, from <NUM> to <NUM> phr of processing aid may be comprised in the composition. In a contemplated embodiment, the processing aid be obtained as ZB <NUM> from Struktol® or others. In some embodiments, the processing aid can be used to promote coupling between a coupling agent, silica filler and/or moieties on the polymer to the network between the polymers.

It is readily understood by those having skill in the art that the rubber composition would be compounded by methods generally known in the rubber compounding art, such as mixing the various sulfur-vulcanizable constituent rubbers with various commonly used additive materials such as, for example, sulfur donors, curing aids, such as activators, accelerators and retarders and processing additives, fillers, pigments, fatty acid, zinc oxide, waxes, antioxidants and antiozonants and peptizing agents. As known to those skilled in the art, depending on the intended use of the sulfur vulcanizable and sulfur-vulcanized material (rubbers), the additives mentioned above are selected and commonly used in conventional amounts.

Representative examples of sulfur donors include elemental sulfur (free sulfur), an amine disulfide, polymeric polysulfide and sulfur olefin adducts. Preferably, the sulfur-vulcanizing agent is elemental sulfur. The sulfur-vulcanizing agent may be used in an amount ranging from <NUM> to <NUM> phr, with a range of from <NUM> to <NUM> phr being preferred. Typical amounts of antioxidants comprise <NUM> to <NUM> phr. Representative antioxidants may be, for example, polymerized trimethyl dihydroquinoline, mixture of aryl-p-phenylene diamines, and others, such as, for example, those disclosed in <NPL>. In the preferred embodiment, the antioxidant is a lignin-based antioxidant. Typical amounts of antiozonants comprise <NUM> to <NUM> phr. A non-limiting representative antiozonant can be, for example, N-(<NUM>,<NUM> dimethyl butyl)-n'-phenyl-p-phenylenediamine. Typical amounts of fatty acids, if used, which can include stearic acid as an example, can comprise <NUM> to <NUM> phr. Typical amounts of zinc oxide comprise <NUM> to <NUM> phr. In a preferred embodiment, the zinc oxide is derived from recycled content. Typical amounts of waxes comprise <NUM> to <NUM> phr. Often microcrystalline waxes are used, but refined paraffin waxes or combinations of both can be used. Typical amounts of peptizers comprise <NUM> to <NUM> phr. Typical peptizers may be, for example, pentachlorothiophenol and dibenzamidodiphenyl disulfide.

Accelerators are used to control the time and/or temperature required for vulcanization and to improve the properties of the vulcanizate. In one embodiment, a single accelerator system may be used, i.e., primary accelerator. The primary accelerator(s) may be used in total amounts ranging from <NUM> to <NUM>, preferably <NUM> to <NUM> phr. In another embodiment, combinations of a primary and a secondary accelerator might be used with the secondary accelerator being used in total amounts ranging from <NUM> to <NUM>, preferably <NUM> to <NUM> phr. , in order to activate and to improve the properties of the vulcanizate. Combinations of these accelerators might be expected to produce a synergistic effect on the final properties and are somewhat better than those produced by use of either accelerator alone. In addition, delayed action accelerators may be used which are not affected by normal processing temperatures but produce a satisfactory cure at ordinary vulcanization temperatures. Vulcanization retarders might also be used. A nonlimiting example of a retarder can be N-cyclohexylthiophthalimide (CTP). Suitable types of accelerators that may be used in the present invention are amines, disulfides, guanidines, thioureas, thiazoles, thiurams, sulfenamides, dithiocarbamates and xanthates. Preferably, the primary accelerator is a sulfenamide, such as, for example, N-cyclohexyl-<NUM>-benzothiazolesulfenamide (CBS). If a second accelerator is used, the secondary accelerator is preferably a guanidine (such as diphenyl guanidine (DPG)), dithiocarbamate (such as zinc dimethyl di-thiocarbamate or zinc dibenzyl di-thiocarbamate) or thiuram compound.

The mixing of the rubber composition can be accomplished by methods known to those having skill in the rubber mixing art. For example, the ingredients are typically mixed in at least two stages, namely, at least one non-productive stage followed by a productive mix stage. The final curatives including sulfur-vulcanizing agents are typically mixed in the final stage which is conventionally called the "productive" mix stage in which the mixing typically occurs at a temperature, or ultimate temperature, lower than the mix temperature(s) than the preceding non-productive mix stage(s). The rubber composition may be subjected to a thermomechanical mixing step. The thermomechanical mixing step generally comprises a mechanical working in a mixer or extruder for a period of time suitable in order to produce a rubber temperature between <NUM> and <NUM>. The appropriate duration of the thermomechanical working varies as a function of the operating conditions, and the volume and nature of the components. For example, the thermomechanical working may be from <NUM> to <NUM> minutes.

Vulcanization of a pneumatic tire of the present invention is generally carried out at conventional temperatures ranging from <NUM> to <NUM>. Preferably, the vulcanization is conducted at temperatures ranging from <NUM> to <NUM>. Any of the usual vulcanization processes may be used such as heating in a press or mold, heating with superheated steam or hot air. Such tires can be built, shaped, molded and cured by various methods which are known and will be readily apparent to those having skill in such art.

The disclosure contemplates a tire component formed from such method. Similarly, the tire component may be incorporated in a tire. The tire component can be ground contacting or non-ground contacting. The tire can be pneumatic or non-pneumatic. In one embodiment, the tire component can be a tread.

The tire of the present disclosure may be a race tire, passenger tire, aircraft tire, agricultural, earthmover, off-the-road, or truck tire or passenger tire. Preferably, the tire is a passenger tire or truck tire. The tire may also be a radial or bias, with a radial being preferred.

The rubber composition itself, depending largely upon the selection and levels of renewable materials, may also be useful as a tire sidewall or other tire components or in rubber tracks, conveyor belts or other industrial product applications, such as windshield wiper blades, brake diaphragms, washers, seals, gaskets, hoses, conveyor belts, power transmission belts, shoe soles, shoe foxing and floor mats for buildings or automotive applications.

The following examples are presented for the purposes of illustrating the present invention. All parts are parts by weight unless specifically identified otherwise.

In these examples, the effects of the disclosed combinations of renewable content on the performance of a rubber compound are illustrated. Rubber compositions were mixed in a multi-step mixing procedure following the recipes in Tables <NUM>-<NUM>.

Control rubber compound Samples A, D, F, K, N and Q were formed of equal amounts of like ingredients. These Control Samples were formed using a blend of polybutadiene BR, emulsion polymerized styrene butadiene copolymer ESBR and solution polymerized styrene butadiene polymer SSBR with additive materials including oil (soybean), a carbon black filler, a bio-based silane coupling agent, waxes, antiozonant, a lignin-based antioxidant, a blend of bio-based fatty acid derivatives, and a recycled zinc oxide. The Controls were also formed using alpha methyl styrene resin, which is derived from petroleum. Standard curing techniques were also used.

Experimental Samples B and C are shown in Table <NUM>. In Samples B and C, the petroleum resin is replaced with a bio-derived resin - more particularly, alpha pinene resin. Sample C also contains an eight percent (<NUM>%) increase in sulfur and an accelerator over Control A, with all other ingredients and amounts being the same.

The rubber compounds were then cured and tested for various properties including, inter alia, wear, wet traction, and rolling resistance, etc..

The basic formulations are shown in the following Table <NUM>, which is presented in parts per <NUM> parts by weight of elastomer (phr). Table <NUM> also compares the cured properties of Control Sample A and Experimental Samples B and C.

Table <NUM> displays a slight directional shift to lower stiffness between Experimental Sample B and Control A when the petroleum-derived resin is replaced with a bio-derived resin. An increase in sulfur and an accelerator between Experimental Sample C and Experimental Sample B - both formed using the bio-derived resin - was made to adjust for the change. This improved the delta torque value of Sample C, which is a better match to Control A.

Altogether, similar performance indicators were observed between the Experimental Samples B and C and Control A. It is concluded that compound performance is not impacted with a sustainably sourced resin in used place of a petroleum-based resin.

Experimental Sample E is shown in Table <NUM>. In Sample E, the conventional petroleum-derived carbon black is replaced with a bio-derived carbon black. Sample E contains a greater amount of carbon black over Control D, with all other amounts being the same.

The basic formulations are shown in the following Table <NUM>, which is presented in parts per <NUM> parts by weight of elastomer (phr). Table <NUM> also compares the cured properties of Control Sample D and Experimental Sample E.

Table <NUM> displays an increase in low strain stiffness between Experimental Sample E and Control D when the petroleum-derived carbon black is replaced with a bio-derived carbon black.

Altogether, the bio-derived carbon black was shown to have no noticeable impact on compound properties. It is concluded that the bio-derived carbon black can be used as a colorant without significantly impacting compound performance.

Experimental Samples G-J are shown in Table <NUM>. In Samples G-J, the ESBR is replaced with natural rubber along with a reduction in SSBR. Sample G uses the conventional petroleum-derived resin with the modified rubber blend. Samples H-J replace the petroleum-derived resin with the bio-derived resin material. Samples I and J use an increased amount of the bio-derived resin material over Sample H. Sample J also increases the amount of silica filler over samples F-I. Minor cure adjustments were made between Samples H, I, and J, with all other ingredient amounts remaining the same.

The rubber compounds were then cured and tested for various properties including, inter alia, wear, wet traction, and rolling resistance.

The basic formulations are shown in the following Table <NUM>, which is presented in parts per <NUM> parts by weight of elastomer (phr). Table <NUM> also compares the cured properties of Control Sample F and Experimental Samples G-J.

In Example <NUM>, the rubber polymer blend was adjusted to shift to a lower polymer Tg. The Experimental Samples G-J were tested to evaluate the impact of the bio-derived resin and/or silica at increasing levels on predicted performance.

By switching to natural rubber, Sample H demonstrated an increase in low strain stiffness. The shift to the lower polymer Tg resulted in a negative impact to wet indicators, but showed improved wear, snow and rolling resistance indicators.

By doubling the amount of bio-derived resin, Sample I demonstrated a significant improvement in wet indicators, but at the expense of rolling resistance. The increase in plasticizer level was directionally beneficial for the snow indicator. Overall, the compound stiffness was reduced.

By adding more silica in combination with the other changes, Sample J demonstrated that the stiffness was recovered. The snow indicator was also shown to be equivalent to the Control F.

It is concluded that performance characteristics can be controllably impacted, and the percent of renewable/sustainable content can be adjusted, by increasing the amount of bio-derived resin material and silica in a tire. Such polymer composition can be incorporated into a tire tread.

Experimental Sample L, shown in Table <NUM>, modifies sample J (which used an increased amount of bio-derived resin material), supra, by further replacing the petroleum-derived carbon black with equal parts of bio-derived carbon black. In Sample M, the non-functionalized SSBR of Control K and Sample L is replaced with a functionalized SSBR. Soybean oil levels were also adjusted accordingly to maintain the plasticizer level of the oil-extended SSBR of Samples K and L.

Minor cure adjustments were made between Samples H, I, and J, with all other ingredient amounts remaining the same. All other ingredients and amounts of Sample L are the same as Sample J, which comprises the bio-derived resin over the petroleum resin of Control K and a greater amount of silica filler. Minor cure adjustments were also made to Sample K.

The basic formulations are shown in the following Table <NUM>, which is presented in parts per <NUM> parts by weight of elastomer (phr). Table <NUM> also compares the cured properties of Control Sample K and Experimental Samples L and M.

Example <NUM> showed no impact on compound properties when petroleum-derived carbon black is replaced with bio-derived carbon black. Here the combination of bio-derived carbon black and bio-derived resin material is tested with the high silica content and a functionalized SBR. The use of the functionalized SBR in place of non-functionalized SBR demonstrated an improved rolling resistance. Minimal impact was observed to other performance indicators. Thus, it is concluded that a functionalized polymer can be used in a tire tread rubber composition with multiple other bio-derived materials.

Experimental Sample O is the same formula as Sample M, supra. Sample P adjusts the polymer ratio of Sample O, with all other ingredients and amounts being the same. This change led to an increase in the percent amount of renewable material (content) in the composition.

The basic formulations are shown in the following Table <NUM>, which is presented in parts per <NUM> parts by weight of elastomer (phr). Table <NUM> also compares the cured properties of Control Sample N and Experimental Samples O and P.

Prior to this example, Sample M demonstrated the most favorable performance results. In Example <NUM>, the ratio blend of the three polymers were adjusted and compared to Sample M. This adjustment resulted in a polymer Tg shift (FOX calculation) from -<NUM> to -<NUM>.

The increase in the natural rubber content of Experimental Sample P demonstrated an increase in compound stiffness and true tensile. Sample P improved wet, wear and snow indicators compared to Control N while also containing a substantial percent increase in renewable material content. The rolling resistance indicators were also equivalent to or improved on Control N and Sample O.

Experimental Sample R is the same formula as Sample P, supra. In Sample S, the ESBR was replaced with a greater amount of natural rubber. All other ingredients and amounts remained the same. This change led to a further increase in the percent amount of renewable material (content) in the composition.

The basic formulations are shown in the following Table <NUM>, which is presented in parts per <NUM> parts by weight of elastomer (phr). Table <NUM> also compares the cured properties of Control Sample Q and Experimental Samples R and S.

To further test an increase to the percent amount of renewable content in a tread, the SBR was removed and replaced with additional natural rubber. Also, in this example the natural rubber made up the majority content, at a substantial increase, of rubber polymer in the blend. This resulted in a polymer Tg (FOX calculation) shift from -<NUM> to -<NUM>.

The polymer adjustments resulted in a slight decrease in compound stiffness.

The increase in natural rubber level increased the percent of renewable content in the rubber composition from <NUM>% weight (Control Q) to <NUM>% weight (Experimental Sample S). Sample S showed improved wet and snow indicators over Control Q, and it also indicated an equivalent rolling resistance.

Claim 1:
A tire component formed from a rubber composition comprising a majority weight percent of bio-renewable materials excluding fossil or radiocarbon materials derived from petroleum, coal or a natural gas source, the rubber composition comprising, based on <NUM> parts per weight (phr) of elastomer:
a blend of at least two rubber elastomers selected from a group consisting of:
from <NUM> phr to <NUM> phr polybutadiene;
up to <NUM> phr of one or more styrene-butadiene copolymer(s);
up to <NUM> phr of natural rubber;
a bio-derived resin material excluding fossil or radiocarbon materials derived from petroleum, coal or a natural gas source; and
a bio-derived filler comprising silica and carbon black filler, the bio-derived filler excluding fossil or radiocarbon materials derived from petroleum, coal or a natural gas source, wherein said carbon black filler is derived from a bio-based feedstock excluding fossil carbon prior to its addition to the rubber composition.