Improved rubber composition with recovered carbon black and plasma carbon black

Abstract

The subject matter of the present invention relates to a more environmentally friendly rubber mixture such that the mixture utilizes recovered carbon black and plasma carbon black as a sustainable reinforcing carbon black filler system with properties approaching that of a virgin carbon black reinforced elastomer and a method of producing such a mixture having improved electrical conductivity.

Description

Inventor: Xiaofeng Shaw Yang, Et al.Atorney Docket No,: 2024PAT00296USIMPROVED RUBBER COMPOSITION WITH RECOVERED CARBON BLACK AND PLASMA CARBON BLACKFIELD OF THE INVENTION

[0001] The subject matter of the present invention relates to an environmentally friendly rubber mixture such that the mixture utilizes the blending of recovered carbon black and plasma carbon black with properties approaching that of a virgin carbon black reinforced elastomer and a method of producing such a mixture having improved electrical conductivity thereby enhancing attractivity of utilization of the waste stream products of end-of-life tires.BACKGROUND OF THE INVENTION

[0002] Carbon black is a well-known filler used in elastomer compositions. Carbon black improves the rubber composition’s properties, such as reducing wear and improving strength of the rubber composition and as an enhancer of certain properties, it is deemed a “reinforcing” filler.

[0003] Carbon black is produced from incomplete combustion of a hydrocarbon containing substance. In a general sense, the carbon black is the soot, or dark component of smoke, and is usually produced by first producing an intensely hot combustion zone with a convenient fuel. Then a fossil fuel feedstock, in excess of stoichiometric quantities, is injected into that intensely hot zone. With this injection, carbon black will be produced, and various grades are obtained by adjusting the parameters and feed stock used to obtain the desired result. The carbon black may be made in a continuous process producing furnace grades or in a cyclical process to produce thermal grades of carbon black. The carbon particles thus produced are separated from the process gas stream or "smoke" by conventional means and pelletized to increase the bulk density. Carbon black obtained in such a fashion is referred to herein as “virgin carbon black”, referred to as “vCB” herein.

[0004] Since the virgin carbon black is produced with a fossil fuel feedstock, the process and product contribute to CO2 production and is considered a non-renewable component used in the production of tires. The use of carbon black from alternative more environmentally friendly sources is desirable, such as recycled carbon black.Inventor: Xiaofeng Shaw Yang, Et al.Atorney Docket No,: 2024PAT00296US

[0005] Recycled carbon black, sometimes also referred to as ‘'reclaimed carbon black” and herein referred to as “recovered carbon black” or “rCB” is obtained during the process of recycling end-of-life pneumatic tires. The end-of-life pneumatic tires is subjected to a pyrolysis process which produces rCB. It is known in the industry that rCB is devoid of functional groups upon the surface of the carbon black (A comparison of surface morphology and chemistry of pyrolytic carbon blacks with commercial carbon blacks, Pow der Technology 160 (2005) 190-193). It is also recognized that use of nonfunctionalized rCB as a replacement in conventional rubber mixes produces a rubber composition that presents many problems. In fact, it has been found that recovered carbon black from pyrolysis, for the same surface area, has a reinforcing strength that is low er than that of virgin carbon black and lacks electrical conductivity7normally found in rubbers comprised of virgin carbon black. Vehicles build up an electrical charge, particularly as they move. Such electrical conductivity of rubber in tires is important to provide electrical charge dissipation to ground through the vehicle tires. The lack of electrical conductivity7must be addressed for a use of rCB reinforced rubber to be a viable alternative to virgin carbon black reinforced rubber.

[0006] Plasma carbon black, referred to as “pCB” herein, is a ty pe of carbonaceous carbon black thought to be more environmentally friendly and potentially sustainable. Instead of combusting the feedstock through combustion as done to produce virgin carbon black, plasma carbon black superheats the feedstock w ith electricity7, thereby reducing or avoiding CO2 emissions. The products are carbon black and hydrogen. Its reinforcing properties and potential sustainability make it an atractive alternative to virgin carbon black, however the expense of manufacturing and desire to use end-of-life tires prevent it from becoming a singular vCB replacement. US patent publication US20230357021 Al describes pCB and the description of pCB is incorporated herein by reference.

[0007] What is needed is a more environmentally friendly rubber composition than rubber compositions using virgin carbon black (also referred to as “virgin” carbon black or “industrial” carbon black) and method of making such a rubber formulation utilizing nonfunctionalized rCB having improved properties including improved conductivity.SUMMARY OF THE INVENTION

[0008] Aspects and advantages of the invention w ill be set forth in part in the follow ing description, or may be obvious from the description, or may be learned through practice of the invention.Inventor: Xiaofeng Shaw Yang, Et al.Atorney Docket No,: 2024PAT00296US

[0009] In one exemplar ' embodiment, a rubber composition for a tire is presented which is comprised of at least one diene elastomer, 40 to 120 phr of a sustainable carbon black filler system, the sustainable carbon black filler system consisting of a recovered carbon black and a plasma carbon black wherein the plasma carbon black represents 20% to 80% by weight of the sustainable carbon black filler system; and a vulcanizing system.

[0010] In another exemplar ' embodiment, a rubber composition for a tire is presented which is comprised of at least one diene elastomer, at least one of which is a natural rubber, 40 to 120 phr of a sustainable carbon black filler system, the sustainable carbon black filler system consisting of a recovered carbon black and a plasma carbon black wherein the plasma carbon black represents 20% to 80% by w eight of the sustainable carbon black filler system; and a vulcanizing system.

[0011] In another exemplary embodiment, a rubber composition for a tire is presented which is comprised of at least one diene elastomer, 50 to 100 phr of a sustainable carbon black filler system, the sustainable carbon black filler system consisting of a recovered carbon black and a plasma carbon black wherein the plasma carbon black represents 20% to 80% by weight of the sustainable carbon black filler system; and a vulcanizing system.

[0012] In another exemplary embodiment, a rubber composition for a tire is presented w hich is comprised of at least one diene elastomer, 60 to 80 phr of a sustainable carbon black filler system, the sustainable carbon black filler system consisting of a recovered carbon black and a plasma carbon black wherein the plasma carbon black represents 20% to 80% by weight of the sustainable carbon black filler system; and a vulcanizing system.

[0013] In another exemplary embodiment, having the composition of any one of the above embodiments wherein the plasma carbon black represents 25% to 75% of the w eight of the sustainable carbon black filler system.

[0014] In another exemplary embodiment, having the composition of any one of the above embodiments wherein the plasma carbon black represents a majority of the weight of the sustainable carbon black filler system.

[0015] In another exemplar ' embodiment, having the composition of any one of the above embodiments wherein the vulcanization system is comprised of an insoluble sulfur which is comprised of elemental sulfur with 20% by weight of an oil.

[0016] In another exemplary embodiment of an invention w herein any one of the above compositions is made by delaying the addition of the plasma carbon black during mixing the compositions until after the elastomer and the recovered carbon black mixing has begun.Inventor: Xiaofeng Shaw Yang, Et al.Atorney Docket No,: 2024PAT00296US

[0017] In another exemplary embodiment of an invention wherein any one of the above compositions is made by delaying the addition of the plasma carbon black until after the elastomer and recovered carbon black mixing has begun and the mix has reached 100 °C.

[0018] These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.DETAILED DESCRIPTION OF THE INVENTION

[0019] The present disclosure provides more environmentally friendly rubber composition than rubber compositions using only virgin carbon black and a method of making such a rubber formulation utilizing a sustainable carbon black filler system consisting of a recovered carbon black (“rCB”) and a plasma carbon black (“pCB”) having similar or improved properties. The rubber composition formulations are the result of mixing various components together at specific proportions and sequence and reacting them under controlled temperature conditions. As rubber compositions are highly dependent upon the chemical reactions that occur during and after mixing and processing, the end result of an experimental mixture can be unpredictable due to rubber formulation’s relationship to the chemical arts which are well established to be a member of the unpredictable arts. This invention is the result of a surprising discovery resulting in a more environmentally friendly rubber composition with similar performance to that of a rubber composition made with a carbon black produced using fossil fuel feedstock (“virgin carbon black”).

[0020] The invention specifically pertains to the use of a sustainable carbon black filler system consisting of rCB and pCB and having good electrical conductivity properties. It has been found that the use of rCB as a carbon black filler for elastomer compositions has a negative impact on energy dissipation, and hence rolling resistance, and rigidity, which affects wear performance, as well as electrical conductivity when rCB is used. The invention provides for a rubber composition where the rCB is blended with pCB to achieve material properties akin to elastomer compositions reinforced with vCB. Additionally, it has been found that surprisingly good conductivity is achieved by delaying the addition of the pCB until after the elastomer has been mixed with the rCB. Particularly it has been found that the delay of the pCB until after the elastomer has been mixed with the rCB andInventor: Xiaofeng Shaw Yang, Et al.Atorney Docket No,: 2024PAT00296USprior to the addition of the vulcanizing agents has produced a rubber composition with good mechanical properties as well as good electrical conductivity. It should be understood that when referred to a composition as “only containing” rCB and pCB as the “only” carbon black, a de minimis amount of virgin carbon black, such as for example 5 phr, may be present and still be within the scope of the claimed invention.

[0021] Thus the present invention relates to rubber composition particularly suited for use in a tire wherein the rubber composition is comprised of at least one diene elastomer, 40 to 120 phr of a sustainable carbon black fdler system, wherein the sustainable carbon black filler system consists of a recovered carbon black and a plasma carbon black and the plasma carbon black is at least 20% and up to 80% by weight of the sustainable carbon black filler system, and a vulcanizing system. Other components may be added as needed for processability or desired properties, such as antioxidants or other protectants, vulcanization agents, vulcanization accelerators, vulcanization retarders, processing aids, non-reinforcing fillers, white fillers, silanes, and / or covering agents.

[0022] The rubber compositions that are embodiments of the present invention may be produced in suitable mixers in a manner known to those having ordinary skill in the art. Typically, the mixing may occur using two successive preparation phases, a first phase of thermo-mechanical working at high temperature followed by a second phase of mechanical w orking at a lower temperature.

[0023] The first phase, sometimes referred to as a "non-productive" phase, includes thoroughly mixing, typically by kneading, the various ingredients of the composition but excluding some of the vulcanization system such as the vulcanization agents, the accelerators, the retarders, and the linking agents of the antiozonants. This first phase is carried out in a suitable kneading device, such as an internal mixer of the Banbury7type, until under the action of the mechanical working and the high shearing imposed on the mixture, a maximum temperature of generally between 120°C and 190°C is reached, indicating that the components are w ell dispersed.

[0024] After cooling the mixture, a second phase of mechanical working is implemented at a low er temperature. Sometimes referred to a "productive" phase, this finishing phase consists of incorporating some of the aforementioned vulcanization system that were not added in the “non-productive” phase, including the vulcanization agents, the accelerators, and the retarders using a suitable device, such as an open mill. It is performed for an appropriate time (typically, for example, betw een 1 and 30 minutes or between 2 andInventor: Xiaofeng Shaw Yang, Et al.Atorney Docket No,: 2024PAT00296US10 minutes), and at a sufficiently low temperature, i.e., lower than the vulcanization temperature of the mixture, so as to protect against premature vulcanization.

[0025] The rubber composition can be formed into useful articles, including tire components. Tire treads, for example, may be formed as tread bands and then later made a part of a tire or they be formed directly onto a tire carcass by, for example, extrusion and then cured in a mold. Other components such as those located in the bead area of the tire or in the sidewall may be formed and assembled into a green tire and then cured with the curing of the tire.

[0026] The resistivity was normalized to that of the vCB witness and was taken under a 5-volt potential at 23°C as the log(R), or the logarithm of the volume resistivity. This volume electrical resistivity' of cured rubber sample was conducted according to ASTM-D257-14-2021-el with circular specimen in an EE 04TF tester from Elastocon AB of Sweden.

[0027] Mooney viscosity' is an indicator of the processability of a rubber composition at uncured stage in forming an article, for example, a tire. In general, the lower the Mooney viscosity, the easier the uncured products are to be processed. Mooney viscosity is measured in accordance with ASTM Standard DI 646-2019a. In general, the composition in an uncured state is molded in a cylindrical enclosure and heated to 100°C. After 1 minute of preheating, the rotor turns within the test sample at 2 rpm, and the torque used for maintaining this movement is measured after 4 minutes of rotation. The Mooney viscosity (ML 1+4) is expressed in "Mooney units" (MU, with 1 MU = 0.83 Newtonmeter).

[0028] Mooney scorch is a descriptor for processing safety before vulcanization starts, and the longer the Mooney scorch, the safer the rubber composition in forming an article, for example, a tire. Mooney scorch is measured in accordance with ASTM Standard D1646-2019a at 115°C or 130°C. In general, Mooney scorch is reported as the time required for the viscosity to rise a set number of Mooney units above the minimum viscosity at the measured temperature.

[0029] The “modulus’", or moduli of elongation (MPa) were measured at 10% (MAI 0) at a temperature of 23 °C based on ASTM Standard D412-2006a on dumb bell test pieces. The measurements were taken in the second elongation; i.e., after an accommodation cycle. These measurements are secant moduli in MPa, based on the original cross section of the test piece. Generally, a material having a higher MAIO is a harder material and a materialInventor: Xiaofeng Shaw Yang, Et al.Atorney Docket No,: 2024PAT00296UShaving a lower MAI 0 is a softer material. For rubber goods, for example, tire components, some reasonably high rigidity is required for the application performances.

[0030] Hysteresis loss HL60 is measured in percent by rebound at 60°C at the sixth impact in accordance with the following equation:HL60(%) = 100(VK0 - VK1) / W1 (Eql)where WO is the energy supplied and W1 is the energy restored.

[0031] Examples

[0032] Six inventive compounds (Fl, F2, F3, F4, F5 and F6) and two comparative compounds (W1 and W2) were prepared as show n in Table 1. The compounds have a composition that is typical for use in a pneumatic tire. It should be understood that the invention is not limited to these compositions or for a particular location within the tire.Table 1. Composition of examples in parts per hundred by weight of elastomer (phr).

[0033] For all inventive examples, a sustainable carbon black filler system is used. The sustainable carbon black filler system consists of recovered carbon black and plasma carbon black. The recovered carbon black, "rCB". represented the only ty pe of recovered carbon black used, “Bolder Black", available commercially from Bolder Industries. This ty pe of rCB is listed here as exemplary and not limiting and other types of recovered carbon black, including combinations of recovered carbon black are within contemplation of the embodiments of the invention. The plasma carbon black, “pCB’‘ represents the only type of plasma carbon black used, and is available commercially from Monolith Corp. This type of pCB is not meant to be limiting any other types of pCB that are anticipated to beInventor: Xiaofeng Shaw Yang, Et al.Atorney Docket No,: 2024PAT00296USwithin scope of the embodiments of the invention. Table 2 showed the properties of the rCB from Bolder Industries and the pCB “GreenBlack 7220” from Monolith Corporation.Table 2 Properties of rCB, pCB, and vCB (N772)<<

[0034] The amount of sustainable carbon black filler system used in the examples of Table 1 was 80 phr. The ratio of rCB to pCB varied from 25% to 75% with witnesses represented by 100% virgin carbon black, 100% rCB and 100% pCB. Other embodiments may include as litle as 20% and as much as 80% of rCB by weight of the sustainable carbon black filler system or as would be useful for rubber composition typical for automotive tire use. The invention disclosed herein is a rubber compound having a sustainable carbon black filler system present in the amount of 40 phr, in other examples the amount of sustainable carbon black filler system is 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115 or even 120 phr of sustainable carbon black filler system. In such examples as litle as 8 phr of plasma carbon black or as much as 96 phr of plasma carbon black, and likewise there may be as much of 96 phr of recovered carbon black or as litle as 8phr recovered carbon black.

[0035] The term "recovered carbon black" is meant herein to be a carbon black from a pyrolysis process of a material comprising at least one carbonaceous polymer and a carbon black, hereinafter "pyrolysis material” for example in the context of the recycling of such a material. The physical state in which the pyrolysis material is presented is irrelevant, whether in the form of powder, granule, strip, or any other form, cross-linked or noncrosslinked.

[0036] Preferably, the pyrolysis material can be recovered from manufactured items or products generated during their manufacture / production (such as by-products or offcuts); these manufactured items may be selected from the group consisting of pneumatic tires, non-pneumatic tires, industrial conveyor belts, transmission belts, rubber seals, rubber hoses, shoe soles and windshield wipers. More preferably, the recovered carbon black used in the context of the present invention is a carbon black obtained from a pyrolysis processInventor: Xiaofeng Shaw Yang, Et al.Atorney Docket No,: 2024PAT00296USwhose material to be pyrolyzed is derived from manufactured items selected from the group consisting of pneumatic tires and non-pneumatic tires.

[0037] Pyrolysis of recovered carbon black in the context of the present invention means any type of thermal decomposition in the absence of oxygen and whose raw material is the material to be pyrolyzed as defined above. Recovered carbon blacks are therefore distinguished from so-called industrial carbon blacks and / or ASTM grade, both also referred to as “virgin carbon black” in that the carbonaceous raw material used for pyrolysis is a material comprising at least one carbonaceous polymer and one carbon black and not materials from oil cuts or coal or oils of natural origin.

[0038] The recovered carbon blacks used in the context of the present invention differ from know n carbon blacks such as virgin carbon blacks, in particular carbon blacks called "furnace" carbon black, as recovered carbon blacks generally possess a higher ash content.

[0039] The recovered carbon black used in the context of the present invention has an ash content in a range ranging from 5 to 30% by weight, more typically from 8 to 25% by weight, most usually from 10% to 22% by weight, relative to the total weight of recovered carbon black.

[0040] The recovered carbon black used in the context of the present invention may have a sulfur content greater than 2% by weight, however, lower percentage sulfur content is preferred, for example generally 2 to 5% by weight, relative to the total weight of recovered carbon black.

[0041] Typically, the recovered carbon black used in the context of the present invention may have a zinc content greater than or equal to 2% by weight, and more specifically in the range of 2.5 to 8% by weight, relative to the total weight of recovered carbon black.

[0042] Preferably, the recovered carbon black used in the context of the present invention may have a specific surface area STSA measured according to ASTM D 6556-2021 in a range ranging from 20 to 200 m2 / g, more preferably ranging from 30 to 90 m2 / g.

[0043] Preferably, the recovered carbon black used in the context of the present invention may have a void volume measured according to ASTM D7854-21 (2021) and at a pressure of 50 MPa in a range ranging from 30 to 60 ml / 100g, more preferably ranging from 35 to 55 ml / 100g.

[0044] The iodine adsorption number as described herein, or simply “Iodine” number is measured according to the method of ASTM D1510-2021.Inventor: Xiaofeng Shaw Yang, Et al.Atorney Docket No,: 2024PAT00296US

[0045] BET measures the surface area of the particles according to a known method, that is, by gas adsorption using the Brunauer-Emmet-Teller method described in "The Journal of the American Chemical Society", Vol. 60, page 309, February 1938, and more specifically, in accordance with French standard NF ISO 9277 of December 1996 (multipoint volumetric method (5 points); where gas: nitrogen, degassing: 1 hour at 160°C, relative pressure range p / po: 0.05 to 0.17).

[0046] STSA measures the surface area of the particles of carbon black. STSA specific surface area measured according to the ASTM D6556-2021.

[0047] The ash content is determined by calcination in platinum capsules in a muffle furnace at 825°C according to the following protocol. One capsule is previously identified before each measurement series and is set to the nearest 0.1 mg and the mass is denoted P0. In the capsule, 5 g of recovered carbon black sample is introduced which is weighed precisely to the nearest 0.1 mg; this mass is denoted Pl. The crucible and its contents are pre-calcined using a Bunsen burner until fumes appear and ignition of the product. Once the product has completely combusted, the crucible and its contents are introduced into a muffle oven heated to 825 °C for 1 h. After 1 hour, the crucible is removed from the oven and immediately introduced into a moisture analyzer at room temperature. When the crucible and ash have returned to room temperature, the crucible is weighed again to obtain the P2 mass. Finally, it is possible to obtain the ash content (% ash) using the formula below:% ash = (P2 - P0) / (Pl - P0) x 100 (1)

[0048] The zinc content in the recovered carbon black is carried out after calcination of the sample, then recovery of the ash in an acidic medium and determination by ICP-AES (inductively coupled plasma atomic emission spectroscopy). The ash is obtained by carrying out the above protocol Approximately 100 mg of ash (test portion) is taken and introduced into a PFA (perfluoroalkoxy) tube for HotBlock hot plate. Then added 8 mL of 37% concentrated hydrochloric acid, 3 mL of 65% concentrated nitric acid and 0.5 mL of 40% hydrofluoric acid. Close the tube with its cap and heat to 130 ° C for 2 hours. After cooling, the contents are then transferred with ultrapure water to a 100 mL PTFE (polytetrafluoroethylene) volumetric flask already containing 2 g of boric acid (to neutralize hydrofluoric acid). It is completed with ultrapure water up to the gauge. The solution obtained is diluted by 100, taking 1 mL from a 100 mL vial of PFTE, previouslyInventor: Xiaofeng Shaw Yang, Et al.Atorney Docket No,: 2024PAT00296UScontaining 8 mL of 37% concentrated hydrochloric acid, 3 mL of 65% concentrated nitric acid, 0.5 mL of 40% hydrofluoric acid and 2 g of boric acid. This dilute solution is then filtered on a 0.45 gm GHP syringe filter before being analyzed by atomic emission spectrometry - inductively coupled plasma (ICP-AES). Prior to the analysis of the dilute solution, at least 5 standards are analyzed by ICP-AES at zinc concentrations of 0, 0.5, 1, 2 and 5 mg / L. These standards were prepared in 100 mL volumetric flasks by diluting a certified commercial solution to a zinc concentration of 1 g / L.

[0049] These volumetric vials previously contain 8 mL of 37% concentrated hydrochloric acid, 3 mL of 65% concentrated nitric acid, 0.5 mL of 40% hydrofluoric acid and 2 g of boric acid. Standard solutions are analyzed by ICP-AES at a wavelength ol'ZZn = 202.613 nm. For each standard concentration (c), the signal strength of zinc IZn is plotted on a graph IZn = f(c), which corresponds to the calibration line (type y = ax + b). The sample solution (dilute solution) of unknown concentration is then measured under the same conditions as the standards. The measured intensity is related to the concentration thanks to the calibration line obtained previously. The concentration [c]ash in % by mass is thus obtained directly by the software, because the test portion and the volume have been previously recorded. The concentration of zinc in recovered black [c]black in % by weight is obtained by the following equation:[c] black = [c]ash * 100 * % ash (2)

[0050] The determination of the sulfur content in recovered carbon blacks is carried out by LECO furnace. LECO sulfur analyzers are designed to measure, inter alia, the sulfur content in organic and / or inorganic materials by combustion and non-dispersive infrared detection. Before measuring the sulfur content on the sample, the crucible are cleaned and the furnace calibrated. The LECO oven crucibles are cleaned beforehand: the empty crucible must be analyzed, under the same conditions as the samples. The preparation of the calibration curve is done from a commercial standard called "BBOT" whose purity is greater than 99.99% and whose content of carbon (C). hydrogen (H), nitrogen (N), oxygen (O) and sulfur (S) is guaranteed. This grade is C%: 72.52; H% 6.09; N% 6.51; 0% 7.43 and S% 7.44. Approximately 10 ± 3, 20 ± 3 and 40 ± 3 mg of BBOT are weighed in a basket. The standard / crucible assembly is fed into the combustion furnace, regulated at 1350 °C under pure oxygen. The combination of furnace temperature and analysis rate causes the sample to bum and release sulfur and / or carbon as S02(g). After a time of 20 s,Inventor: Xiaofeng Shaw Yang, Et al.Atorney Docket No,: 2024PAT00296USoxygen begins to circulate through the "lance" to accelerate the combustion of hard-to-bum materials. Sulfur and / or carbon, in the form of SO2(g), are carried by a flow of oxygen through the sensing infrared cells. The instrument software plots a line connecting the introduced standard mass and the observed response (area) on the detector. This results in a calibration line. After thoroughly cleaning the sampling material, approximately 80 ± 5 mg of recovered carbon black is weighed and fed into a LECO oven crucible. The area of the observed SO2 peak is related to the concentration thanks to the calibration line. The instrument software then calculates the mass of sulfur in the sample through the sample mass.

[0051] Recovered carbon blacks are marketed for example by the company BlackBear under the reference BBCT30, P550 by the company Scandinavian Enviro Systems, BolderBlack by Bolder Industries.

[0052] The second component of the sustainable carbon black filler system is a plasma carbon black. In the exemplary embodiments shown in Table 1, the plasma carbon black is present in a complementary amount representing 20% to 80% by weight of the sustainable carbon black filler system. In the embodiments shown, the plasma carbon black represents 25%, 50% and 75% of the sustainable carbon black filler system. In the embodiments shown, no virgin carbon black is present in the rubber compositions. In other embodiments a de minimis amount of virgin carbon black may be present, meaning that 5phr or less of virgin carbon black may be present.

[0053] A vulcanization package was added to the rubber compound to crosslink the elastomer chains and cure the rubber as noted in the examples. The vulcanization package in the examples above consist of 3 phr of zinc oxide (“ZNO”), 1 phr of a fatty acid, specifically stearic acid, 1.3 phr of insoluble sulfur, and 1.3 phr of a vulcanization accelerator, used particularly here was N-cyclohexyl-2-benzothiazole sulfenamide (“CBS’7). The insoluble sulfur was comprised of 80% elemental sulfur and 20% oil by weight.

[0054] It is well known that if unprotected, ozone in the environment will atack the surface of rubber which is generally formulated with highly unsaturated elastomers, particularly if the rubber is under strain during usage. This ozone atack will result in small cracks on the surface of the rubber, which could develop into deep and large cracks. The small cracks diminish the cosmetic aesthetics while deep and large cracks may shorten the service life of the rubber articles such as tires.Inventor: Xiaofeng Shaw Yang, Et al.Atorney Docket No,: 2024PAT00296US

[0055] To combat ozone atack, various antiozonants have been developed and commercialized to slow down the formation of the ozone cracks under static and dynamic conditions. For example, waxes of various characteristics have been developed and used in rubbers against static ozone atack by forming a film barrier on the surface, though such film will break and lose ozone protection under dynamic conditions. For dynamic protection, various chemical antiozonants are developed and commercially available, with one of the well-known and widely used groups being the substituted phenyl-p-phenylenediamines, or PPDs. These PPDs may include N-isopropyl-N'-phenyl- / ?-phenylene (IPPD), N-l,3-dimethylbutyl-N'-phenyl-jO-phenylendiamine (6PPD), N, N'-bis-(1 ,4-dimethylpentyl)-p-phenylenediamine (77PD), N-cyclohexyl-N'-phenyl-p-phenylenediamine (CHPPD), and N,N'-diphenyl-p-phenylenediamine (DPPD). Other protectants such as hindered phenols and or TMQ may be used alternatively or additionally. A protection system totaling 2 phr was also added to the rubber compositions in the examples used herein. In particular, 6PPD was used as an anti oxi dant / anti-degradant. Other protective agents may also be used and still be within the scope of the invention, including other anti degradants or passive protective agents like waxes such as paraffin.

[0056] Other components may be used such as non-reinforcing or reinforcing fillers such as bentonite, talc, chalk kaolin, aluminosilicate, fiber, or coal graphene, graphite, zeolite, and so forth.

[0057] The examples above are devoid of silica, however, silica may be used to augment the reinforcing filler system. The silica (SiO2) that may be used are known to a person skilled in the art to be those that are suitable in particular as reinforcing inorganic fillers. The silica used may be, in particular, any precipitated or pyrogenic silica. The silica may be a highly dispersible precipitated silicas (“HDSs'’). for example, of the Ultrasil 7000 and Ultrasil 7005 silicas from Degussa, the Zeosil 1165MP. 1135MP and 1115MP silicas from Rhodia, the Hi-Sil EZ150G silica from PPG, for example.

[0058] Silane coupling agents are well know n and are sulfur-containing organosilicon compounds that react with the silanol groups of the silica during mixing and with the elastomers during vulcanization to provide improved properties of the cured rubber composition. While silane is not shown to be used in the examples herein, embodiments of the invention may contain silane coupling agents, particularly where an inorganic reinforcing filler is also added. Any of the organosilicon compounds that contain sulfur and are known to one having ordinary skill in the art are useful for practicing embodimentsInventor: Xiaofeng Shaw Yang, Et al.Atorney Docket No,: 2024PAT00296USof the present invention. Examples of suitable silane coupling agents having two atoms of silicon in the silane molecule include 3,3'-bis(triethoxysilylpropyl) disulfide and 3,3'-bis(tri ethoxy -silylpropyl) tetrasulfide (known as Si69). Both of these are available commercially from Evonik as X75-S and X50-S respectively, though not in pure form. Evonik reports the molecular weight of the X50-S to be 532 g / mole and the X75-S to be 486 g / mole. Both of these commercially available products include the active component mixed 50-50 by weight with aN330 carbon black.

[0059] Other examples of suitable silane coupling agents having two atoms of silicon in the silane molecule include 2,2'-bis(triethoxysilylethyl) tetrasulfide, 3,3'-bis(tri-t-butoxy-silylpropyl) disulfide and 3,3'-bis(di t-butylmethoxysilylpropyl) tetrasulfide. Examples of silane coupling agents having just one silicon atom in the silane molecule include, for example, 3,3'(triethoxysilylpropyl) disulfide and 3,3' (triethoxy -silylpropyl) tetrasulfide. The amount of silane coupling agent can vary over a suitable range as known to one having ordinary skill in the art. Typically the amount added is between 7 wt. % and 15 wt. % or alternatively between 8 wt. % and 12 wt. % or between 9 wt. % and 11 wt. % of the total weight of silica added to the rubber composition.

[0060] The rubber components shown in table 1, except sulfur and accelerator in the vulcanization package, were mixed in a Banbury mixer. The witness mixes, W3 along with embodiments Fl, F3, and F5 had plasma carbon black added at the same time with the recovered carbon black during the nonproductive phase of mixing. Embodiments F2, F4, and F6 had the plasma carbon black added after mixing began and was delayed until the mix reached 100 °C while mixing during the nonproductive phase of the mixing process. In other words, the non-productive stage was done in a Banbury mixer, where everything but sulfur and accelerator was added. In this stage, the mixer started at low7temperature, e.g., 60 °C. In general, everything (including elastomer, carbon blacks, ZnO, stearic acid, 6PPD) was added at the beginning. The temperature rises due to the heat generation during mixing. However, in F2 / F4 / F6, the pCB was delayed (by opening the mixer door) when the mixer temperature reached 100 °C. All mixes continued mixing until a temperature of between 150 °C and 170 °C was reached.

[0061] Alternatively delay of the pCB could occur when the mix reaches 90 °C or alternatively wait until the mix reaches 110 °C as opposed to waiting until it reaches 100 °C as was done in the inventive mixes herein. Alternatively, a different temperature may be chosen, such as a temperature between 90 °C to 110 °C. In yet another alternative the delay of the pCB may wait for a period of time after the nonproductive phase of mixingInventor: Xiaofeng Shaw Yang, Et al.Atorney Docket No,: 2024PAT00296USbegins and the pCB is added, such as adding the pCB 0.2 to 0.5 minutes after the initiation of the mixing and addition of the rCB.

[0062] The vulcanization package was added during the second phase on a mill. The rubber formulations were cured at between 140 °C and 170 °C and a duration such that the formulations were fully cured. The formulations were then tested to measure their properties, the results of which are shown in tables herein.

[0063] Table 3. Test Results.

[0064] Comparison of the witness compositions reveal an increased electrical resistivity inherent with the use of rCB (W2) in lieu of virgin carbon black (Wl) as well as an increase in hysteresis with both 100% rCB (W2) and use of 100% pCB (W3). Test results show comparable properties between the witnesses (Wl, W2 and W3) with respect to the modulus of elasticity measured as MAIO. A marked increase in hy steresis (HL60) and to a lesser extent the modulus of elongation (MAIO) of both the rCB (W2) and the pCB (W3).

[0065] Comparing the effects of a blend of both rCB and pCB identifies a synergistic effect of the combination of the two forming the sustainable carbon black filler system. With each of the embodiments of the invention (Fl. F2. F3. F4. F5 and F6) a remarkable decrease of the hysteresis is observed compared to either the rCB (W2) or the pCB (W3) alone approaching that of the hysteresis of vCB (Wl). Likewise, the modulus of the inventive compounds is similar that of the virgin carbon black compared to the mild increase in modulus values of the 100% rCB (W2) or the 100% pCB (W3) witness compounds.

[0066] The resistivity, measured with a 5-volt potential and shown as a normalized value compared to 100% vCB (Wl) compound, shows comparable values to the witness (W2) with 25% plasma carbon black (Fl, F2) and a marked decrease in resistivity with higher percentage of the pCB represented in the sustainable carbon black filler system as shown in the inventive compounds F3, F4, F5 and F6.Inventor: Xiaofeng Shaw Yang, Et al.Atorney Docket No,: 2024PAT00296US

[0067] Surprisingly there was a positive effect on a reduction of the resistivity of the compounds generally observed when the plasma carbon black delivered to the mix at a time after the elastomer and recovered carbon black was mixed. In the embodiments F2, F4 and F6, the pCB portion of the sustainable carbon black filler system was delayed until after the elastomer and rCB was mixed for a period of time. In the examples, the addition of the pCB occurred once the mix reached 100 °C in inventive compounds F2, F4 and F6. In higher loadings of pCB in exemplary inventive mix F6, a noticeable reduction of resistivity’ is observed compared to the mix where the addition of the pCB is not delayed (F5).

[0068] The terms "a," "an," and the singular forms of words shall be taken to include the plural form of the same words, such that the terms mean that one or more of something is provided. The terms "at least one" and "one or more" are used interchangeably. Ranges that are described as being "between a and b" are inclusive of the values for "a" and "b."

[0069] The citation of any document is not an admission that it is prior art with respect to any invention disclosed or claimed herein or that it alone, or in any combination with any other reference or references, teaches, suggests or discloses any such invention.Further, to the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall govern.

Claims

Inventor: Xiaofeng Shaw Yang, Et al.Atorney Docket No,: 2024PAT00296USNote for inventor names: Xiaofeng Shaw Yang, Kacey Christine Hall, Chantal Smith WHAT IS CLAIMED IS:

1. A rubber composition comprising:a diene elastomer;40 to 120 phr of a sustainable carbon black filler system, the sustainable carbon black filler system consisting of a recovered carbon black and a plasma carbon black wherein the plasma carbon black represents 20% to 80% by weight of the sustainable carbon black filler system; anda vulcanizing system.

2. The rubber composition of claim 1 wherein the diene elastomer comprises a blend of two or more diene elastomers.

3. The rubber composition of claim 1 or claim 2 wherein the sustainable carbon black filler system is present in an amount of 50 to 100 phr.

4. The rubber composition of claim 1 or claim 2 wherein the sustainable carbon black filler system is present in an amount of 60 to 80 phr.

5. The rubber composition of any one of the above claims wherein the plasma carbon black present is in an amount of 25% to 75% of the weight of the sustainable carbon black filler system.

6. The rubber composition of any one of the above claims further comprising silica.

7. The rubber composition of any one of the above claims further comprising a virgin carbon black.

8. The rubber composition of any one of the above claims further comprising a protection system.

9. The rubber composition of any one of the above claims further comprising a vulcanization retardant.

10. The rubber composition of any one of the above claims wherein the vulcanization system comprising insoluble sulfur.

11. A tire comprising the rubber composition of any one of the above claims.

12. A tire tread comprising the rubber composition of any one of claims 1-10.

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