Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
  • C08K3/20—Oxides; Hydroxides
  • C08K3/22—Oxides; Hydroxides of metals
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C1/00—Tyres characterised by the chemical composition or the physical arrangement or mixture of the composition
  • B60C1/0025—Compositions of the sidewalls
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/01—Use of inorganic substances as compounding ingredients characterized by their specific function
  • C08K3/013—Fillers, pigments or reinforcing additives
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/02—Elements
  • C08K3/08—Metals
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/54—Silicon-containing compounds
  • C08K5/548—Silicon-containing compounds containing sulfur
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C19/00—Tyre parts or constructions not otherwise provided for
  • B60C2019/005—Magnets integrated within the tyre structure
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K2201/00—Specific properties of additives
  • C08K2201/01—Magnetic additives

Definitions

• Modern vehicles are often equipped with a Sidewall Torsional Sensor System which detects longitudinal and lateral forces acting upon the tires.
• the tires which contain magnetic particulate dispersed in the sidewall, provide a magnetic signal to the Sidewall Torsional Sensor System, which in turn provides the onboard vehicle computer with immediate information about the forces acting on the tires.
• the magnetic particulate is added in significant amounts. The presence of the magnetic particulates however results in significant loss of fatigue resistance and crack growth resistance .
• the present invention provides a composition useful for magnetic filled tires, particularly for tire sidewalls, which contains an organoxysilylsulfane coupling agent.
• the composition displays either improved fatigue resistance and preferably improved crack growth resistance.
• the sidewall composition is magnetizable to a magnetic field strength of preferably at least 0.1 Gauss, more preferably at least 0.5 Gauss, even more preferably at least 1 Gauss, even more preferably at least 10 Gauss, most preferably at least 25 Gauss, as measured at a distance of 8 mm for a 1 mm thick layer.
• the sidewall composition preferably 'has: the following physical properties: 1.
• the sidewall composition has two or more of the preceding physical properties.
• the sidewall composition comprises 100 parts rubber, magnetic particulate, organosilane and curing agents.
• the amounts of ingredients are based upon 100 parts rubber.
• the compositions contain: curing agents in an amount effective to cure the rubber; preferably from 1.2 to 3.75, more preferably from 1.35 to 3.45 even more preferably from 1.5 to 3.13 phr curing agents such as sulfur, more preferably 1.5 to 2.5 phr soluble sulfur and 1.88 to 3.13 oil treated sulfur; preferably from 30 to 350 phr, more preferably from 40 to 300 phr, most preferably from 50 to 250 phr magnetic particulate; and preferably from 0.5 phr to 30 phr, more preferably from 1 phr to 20 phr, most preferably from 2 to 10 phr organoxysilylsulfane.
• Conventional rubber additives are optionally added.
• the present invention also relates to methods of making tires, and to the tire itself.
• the sidewall composition is prepared by providing 100 parts rubber and preferably from 30 to 350 phr, more preferably from 40 to 300 phr, most preferably from 50 to 250 phr magnetic particulate; and preferably from 0.5 phr to 30 phr, more preferably from 1 phr to 20 phr, most preferably from 2 to 10 phr organoxysilylsulfane; combining the rubber with 15% to 50%, preferably 20% to 30%, more preferably 25% of the magnetic particulate to form a first mixture, then the first mixture is combined with 25%-75%, preferably 45% to 55%, more preferably 50% of the organoxysilylsulfane and 15%-50%, preferably 20% to 30%, more preferably 25% of the magnetic particulate to form a second mixture; then the remaining 25% to 75%, preferably 45% to 55%, more preferably 50% of the magnetic particulate, 25% to 75%,
• the sidewall composition is prepared by providing 100 parts rubber and preferably from 30 to 350 phr, more preferably from 40 to 300 phr, most preferably from 50 to 250 phr magnetic particulate; and preferably from 0.5 phr to 30 phr, more preferably from 1 phr to 20 phr, most preferably from 2 to 10 phr organosilane; combining the rubber with 50% to 100%, preferably 90% to 100% of the organoxysilylsulfane and 25% to 75%, preferably 45% to 55%, more preferably 50% of the magnetic particulate to the rubber to form a first mixture.
• the remaining 25% to 75%, preferably 45% to 55%, more preferably 50% of the magnetic particulate, and 0 to 50%, preferably 0% to 10% of the organoxysilylsulfane, are added to the first mixture to form a second mixture.
• the curing agents are added.
• Figure 1 is a graph showing the fatigue until failure, in cycles to failure, with two different extensions of the composition of
• Figure 2 is a graph showing the fatigue until failure, with two different extensions of the composition of Examples 1 to 4, compared to conventional compositions of Comparative Examples A and
• Figure 3 is a graph showing the Pierced DeMattia Crack Growth
• KC/mm represents kilocycles per millimeter. Kilocycles means thousand cycles of uploading and downloading; this number is divided by the length, in millimeters, of the resulting crack in the samples;
• Figure 4 is a graph showing the Pierced DeMattia Crack Growth
• Figure 5 is a graph showing the Fatigue resistance in cycles to failure, of the composition of Examples 5 and 6, compared to conventional compositions of Comparative Examples A and B;
• Figure 6 is a graph showing the Fatigue resistance in cycles to failure, of the composition of Examples 5 and 6, compared to conventional compositions of Comparative Examples A and B using normalized data;
• Figure 5 is a graph showing the Pierced DeMattia Crack Growth
• Figure 6 is a graph showing the Pierced DeMattia Crack Growth
• Figure 7 is shows a tire in cross section, with a sidewall veneer containing the sidewall composition.
• the present invention provides a composition useful for magnetic tires, particularly for magnetic tire sidewalls, which contains an organoxysilylsulfane coupling agent.
• the composition displays either improved fatigue resistance or either improved crack growth resistance or both.
• the sidewall composition preferably has: the following physical properties: 1. a fatigue to failure value at 101% extension of 142 cycles to failure or greater, more preferably 200 cycles to failure or greater, more preferably 266 cycles to failure or greater; 2. a fatigue to failure value at 136% extension of 47 cycles to failure or greater, more preferably 67 cycles to failure or greater, more preferably 100 cycles to failure or greater; 3. a pierced DeMattia resistance of 12 KC/mm or greater, more preferably 15 KC/mm or greater, even more preferably 29 KC/mm or greater.
• the sidewall composition has two or more of the preceding physical properties.
• the sidewall composition comprises rubber, magnetic particulate, organoxysilylsulfane and curing agents. Conventional additives are optionally added.
• the amounts of ingredients are based upon 100 parts rubber.
• the 100 parts rubber is comprised of from 20% to 70% natural rubber, from 20% to 70% butadiene rubber, 0% to 30%, preferably from 10% to 30 emulsion styrene butadiene rubber.
• the sidewall compositions contain: curing agents in an amount effective to cure the rubber. Preferably there is from 1.2 to 3.75, more preferably from 1.35 to 3.45, even more preferably from 1.5 to 3.13 phr curing agents such as sulfur, more preferably 1.5 to 2.5 phr soluble sulfur and 1.88 to 3.13 oil treated sulfur.
• the sidewall composition also contain preferably from 30 to 350 phr, more preferably from 40 to 300 phr, most preferably from 50 to 250 phr magnetic particulate and preferably from 0.5 phr to 30 phr, more preferably from 1 phr to 20 phr, most preferably from 2 to 10 phr organoxysilylsulfane.
• the sidewall composition contains from 0 to 100, preferably from 0.1 to 100, more preferably from 10 to 80, even more preferably from 15 to 70, most preferably from 25 to 60 phr carbon black.
• the sidewall composition also contains: from 0 to 8 , preferably from 0.1 to 8, more preferably from 0.2 to 2, even more preferably from 0.3 to 1.5 phr cure accelerators; from 0 to 40, preferably from 0.1 to 40, more preferably from 4 to 22, even more preferably from 8 to 20 phr processing oil; from 0 to 20, preferably from 0.1 to 20, more preferably from 1 to 12, even more preferably from 4 to 10 phr antidegradant ; from 0 to 16, preferably from 0.1 to 16, more preferably from 0.25 to 8, even more preferably from 2 to 6 phr waxes such as macrocrystalline waxes; from 0 to 16 preferably from 0.1 to 16, more preferably from 0.5 to 8, even more preferably from 2 to 6 phr zinc oxide; from 0 to 12, preferably from 0.1 to 12, more preferably from 0.25 to 4, even more preferably from 1 to 4 phr stearic acid; and from 0 to 16, preferably 0.1 to 16
• Rubbers used to form tire sidewalls such as natural rubber, butadiene rubber, styrene butadiene rubber ethylene propylene diene monomer halobutyl rubber, and mixtures thereof are employed.
• Polybutadiene is commercially available Taktene 1203G1 Bayer, Orange, Texas, Cisdene 1203 from American Synthetic Rubber, Louisville, KY, Budene 1208 from Goodyear Chemical, Beaumont, Texas and Buna CB25 from Bayer, Orange, Texas.
• silicone rubber is not employed.
• 100 parts of rubber are used.
• the 100 parts rubber is comprised of from 20% to 70% natural rubber, from 20% to 70% butadiene rubber, 0% to 30%, preferably from 10% to 30 emulsion styrene butadiene rubber.
• the magnetic particulate is a ferromagnetic material having a coercivity value, that is a resistance to demagnetization measured in Kiloamperes per meter hereinafter "KA/m" .
• the magnetic particulate preferably has a coercivity value of at least 30 KA/ , more preferably 50 KA/m, even more preferably at least 70 KA/m, most preferably at least 100 KA/m. Materials having a coercivity of less than 50 KA/m will readily demagnetize so that the tire no longer provides a signal to the Torsional Sensor System.
• the magnetic particulate is selected from ferromagnetic elements such as iron, cobalt, nickel, gadolinium, dysprosium and alloys and compounds thereof. Mixtures of magnetic particulates are also used.
• Preferred magnetic particulates are ferrites such as for example the following: NiFe 2 0 4 , Zn 0 .7Nio.3Fe 2 ⁇ 4, Zno. 2 no.sFe2. 2 O 4 , Co x Fe 3 _ x 0 4 , MnFe 2 0 4 , Cd x Ni 1 _ x Fe 2 0 4 , Lio.
• strontium ferrite even more particularly tetrahedral strontium ferrite and octahedral strontium ferrite.
• the magnetic particulate has a particle size from 0.25 to 25 microns, more preferably from 0.5 to 10 microns, even more preferably from 0.75 to 5 microns, most preferably from 1 to 1.5 microns.
• Good results have been obtained using 1.4 micron powdered strontium ferrite available under the trade name Starbond Ferrite Powder HM181 from Hoosier Magnetics, Washington, Indiana. While barium ferrite is suitable, it is less preferred due to environmental concerns. Iron powder is also less preferred due to its rapid oxidation. Iron oxides are much less preferred because they do not bond well with organosilanes and are have low coercivity that is they are easily demagnetized.
• the magnetic particulate is present in an amount sufficient to generate a signal detectable by Sidewall Torsional Sensor Systems .
• the sidewall composition is magnetizable to a magnetic field strength of preferably at least 0.1 Gauss, more preferably at least 0.5 Gauss, even more preferably at least 1 Gauss, even more preferably at least 10 Gauss, most preferably at least 25 Gauss, as measured at a distance of 8 mm for a 1 mm thick layer.
• the magnetic composition and the tire having a sidewall with the magnetic composition have a magnetic field strength of preferably at least 0.1 Gauss, more preferably at least 0.5 Gauss, even more preferably at least 1 Gauss, even more preferably at least 10 Gauss, most preferably at least 25 Gauss, as measured at a distance of 8 mm for a 1 mm thick layer.
• Magnetic field strength in a tire sidewall is measured by rotating the tire for example at 4096 points per revolution using a conventional sensor at a distance of 8 mm such as a Hall effect sensor.
• the sensor detects the amplitude and frequency; the amplitude is the magnetic field strength.
• a Helmholtz coil is used for calibration.
• a Hall effect sensor is available commercially for example from LDJ Electronics .
• the organooxysilyl sulfane is preferably an ethoxy silyl sulfane,more preferably a triethoxysilyl sulfane.
• the organoxysilylsulfane has the following structure: R 2
• Ri is and ethoxy methoxy or hydroxy group
• R 2 is H ethoxy methoxy or hydroxy group
• R 3 is H ethoxy methoxy or hydroxy group
• R 4 is an alkyl group having at least 1 carbon atom, preferably from
• R 5 is an alkyl group having at least 1 carbon atom, preferably from
• R 6 is H, ethoxy, methoxy, or hydroxy group
• R 7 is H, ethoxy, methoxy, or hydroxy group
• R 8 is H, ethoxy, methoxy, or hydroxy group; n is a number from 1 to 20, preferably 1 to 8, most preferably 1 to
• organoxysilylsulfane is nonpolymeric .
• organoxysilylsulfanes are triethoxysilylpropyl disulfane hereinafter also referred to as "TESPD" , shown below:
• TESPT Bis- ( triethoxysilylpropyl) tetrasulfane
• TESPT is commercially available as Activator X50S from: Degussa-Huels, AG, Kalsscheuren, Germany; Degussa Corp., Belpre, Ohio: and TESPD commercially available as Silquest A1589 from C. K. Witco, Organosilanes Group, Inchem Plant, Rock Hill, SC.
• the organoxysilylsulfane is added to the sidewall composition in an amount effective to improve fatigue resistance or crack propagation resistance or both.
• the ratio of the magnetic particulate to the organoxysilylsulfane is 10:1 to 100:1, preferably 25:1 to 75:1, more preferably 45:1 to 55:1.
• the curing agents are conventional in the rubber industry. Good results have been obtained with curing agents such as sulfur, for example soluble sulfur commercially available as Royal RM 90, 0.5% OT from Reagent Chemical, Middlesex, NJ or 20% oil treated sulfur available as Crystex HS OT 20 from Flexsys, Monongahela, PA.
• the Optional Additives are conventional in the rubber industry. Good results have been obtained with curing agents such as sulfur, for example soluble sulfur commercially available as Royal RM 90, 0.5% OT from Reagent Chemical, Middlesex, NJ or 20% oil treated sulfur available as Crystex HS OT 20 from Flexsys, Monongahela, PA.
• the optional additives are conventional in sidewall compositions.
• a variety of ingredients are typically, although not necessarily employed in sidewall composition such as, for example, processing oils to reduce viscosity, such as, for example, an aromatic oil available under the trade name Sundex 8125 from Sunoco, Inc., Tulsa, OK or napthenic oil, and antidegradants such as for example P-phenylenediamine antedegradants such as Flexzone 4L, from Uniroyal Chemical, Elmira, Ont, Canada and Santoflex 6PPD PST from Flexsys, Sauget, IL.
• processing oils to reduce viscosity such as, for example, an aromatic oil available under the trade name Sundex 8125 from Sunoco, Inc., Tulsa, OK or napthenic oil
• antidegradants such as for example P-phenylenediamine antedegradants such as Flexzone 4L, from Uniroyal Chemical, Elmira, Ont, Canada and Santoflex 6PPD PST from Flexsys,
• waxes such as macrocrystalline waxes, such as for example, Micro crystalline paraffin wax available under the trade name Okerin 2027 from Allied Signal Specialty Chemicals, Titusville, PA, and tackifying agents.
• tackifying agents are tackifying resins, such as for example phenolic resins such as the phenolic resin commercially available as HRJ 10420 from Schenectady International, Inc., Rotterdam Junction, NY and hydrocarbon resins Escorez 1102 from Exxon Mobil, Baton Rouge, LA, Norsolene S95 from Totalfina, Channelview, Texas and mixtures thereof.
• Curing accelerators such as 2-Benzothiazolesulfenamide, N- tert-butyl- also known as TBBS accelerator, commercially available as Delac NS Millipellets from Uniroyal Chemical, Geismer, LA and 2-Benzothiazolesulfenamide, N-cyclohexyl- also known as CBS accelerator, commercially available as Delac S Millipellets from Uniroyal Chemical, Geismer, LA are also optionally employed.
• Activators such as zinc stearate formed from the reaction of zinc oxide commercially available as Kadox 720 from Zinc Corporation of America, Monaca, PA and stearic acid commercially available as Industrene R Flake from Witco, Mapleton, IL, are optionally employed.
• Carbon black is also optionally added. Good results have been obtained using carbon black available under the designations N660 from Degussa, Aransas Pass, Texas, and Continex N550 from Alexandria Carbon Black Co, Alexandria, Egypt.
• the magnetic sidewall composition contains less than 10%, more preferably less than 5%, even more preferably less than 1% most preferably 0% silica fillers.
• the sidewall composition is prepared by providing 100 parts rubber and from 30 to 350, preferably from 40 to 300, more preferably from 50 to 250 phr magnetic particulate and from 0.5 to 30, preferably from 1 to 20, more preferably from 1 to 20 phr organoxysilylsulfane; combining the rubber with 15% to 50%, preferably 20% to 30%, more preferably 25% of the magnetic particulate to form a first mixture, then the first mixture is combined with 25%-75%, preferably 45% to 55%, more preferably 50% of the organoxysilylsulfane and 15%-50%, preferably 20% to 30%, more preferably 25% of the magnetic particulate to form a second mixture; then the remaining 25% to 75%, preferably 45% to 55%, more preferably 50% of the magnetic particulate, 25% to 75%, preferably 45% to 55%, more preferably 50% of the organoxysilylsulfane, are added to the second mixture.
• carbon black is added; the carbon black is added at any stage, preferably to the first mixture
• a side wall composition is prepared by providing 100 parts rubber and from 30 to 350, preferably from 40 to 300, more preferably from 50 to 250 phr magnetic particulate and from 0.5 to 30, preferably from 1 to 20, more preferably from 1 to phr organoxysilylsulfane; first forming a first masterbatach by adding the rubbers to a mixer. Good results have been obtained using a Banbury mixer at 50°C and at 77 to 116 rpm. Next, preferably from 5% to 75%, more preferably from 15% to 50%, most preferably from 20% to 30%, of the magnetic particulate, is added along with the tackifying resin, filler preferably carbon black, and the antidegradants, and then thoroughly mixing.
• the wax preferably microcrystallme wax, stearic acid, from 5% to 75%, more preferably from 15% to 50%, most preferably from 20% to 30%, of the magnetic particulate, and preferably from 20% to 80% more preferably from 30% to 70%, most preferably from 40% to 60% of the organosilane, are added and thoroughly mixed.
• the aromatic oil is then added and mixed. Good results have been obtained by discharging and cooling to provide a first masterbatch.
• a second masterbatch is formed by adding the first masterbatch, the remaining magnetic particulate and the remaining organosilane, and mixing. Good results have been obtained by discharging and cooling.
• the sidewall composition is prepared by providing 100 parts rubber and from 30 to 350, preferably from 40 to 300, more preferably from 50 to 250 phr magnetic particulate and from 0.5 to 30, preferably from 1 to 20, more preferably from 1 to 20 phr organoxysilylsulfane; combining the rubber with 50% to 100%, preferably 90% to 100% of the organoxysilylsulfane and 25% to 75%, preferably 45% to 55%, more preferably 50% of the magnetic particulate to the rubber to form a first mixture.
• the remaining 25% to 75%, preferably 45% to 55%, more preferably 50% of the magnetic particulate, and 0 to 50%, preferably 0% to 10% of the organoxysilylsulfane, are added to the first mixture to form a second mixture.
• the curing agents are added.
• the sidewall composition is prepared by providing 100 parts rubber and from 30 to 350, preferably from 40 to 300, more preferably from 50 to 250 phr magnetic particulate and from 0.5 to 30, preferably from 1 to 20, more preferably from 1 to 20 phr organoxysilylsulfane; adding the rubbers to a mixer. Good results have been obtained using a Banbury mixer at 50°C and at 77 to 116 rpm. Next, from preferably from 20% to 80% more preferably from 30% to 70%, most preferably from 40% to 60% of the magnetic particulate and preferably from 80% to 100%, more preferably 100% of the organoxysilylsulfane are added and mixed.
• the filler preferably carbon black, the tackifying resin, microcrystalline paraffin wax, stearic acid, magnetic particulate, organoxysilylsulfane, were added and mixed. Then 50% of the aromatic oil was added, mixed, discharged and cooled.
• a second masterbatch is formed by adding the first masterbatch, then adding carbon black, zinc oxide, the remainder of the magnetic particulate and the remaining 50% of the aromatic oil and then mixed and discharged.
• the second masterbatch is added to the mixer and the curative agents are added. The material is discharged and cooled.
• the sidewall composition is then used to form a tire, preferably a veneer tire.
• a tire preferably a veneer tire.
• US Patent No. 5,895,854 issued April 20, 1999 to Thomas Becherer entitled "Vehicle Wheel Provided with a Pneumatic Tire having therein a Rubber Mixture Permeated with Magnetizable Particles”
• US Patent No. 5,923,240 to Drahne issued June 15, 1999 entitled “Method and Device for controlling Slip and/or for Determining the Longitudinal force or flex Work-Proportional Parameter and Vehicle Tire Therefore
• a vehicle tire 10 is shown in cross section having a tread 12, a shoulder 14 extending from the tread to sidewall 16.
• the bead 18 extends from the sidewall 16.
• Veneer 20 is present atop the inner sidewall 16a.
• the sidewall veneer is applied using conventional techniques such as for example lamination or co-extrusion.
• the veneer 18 is not present and the sidewall 16 is comprised of the sidewall composition.
• Example 1 A side wall composition was prepared by adding 40 phr natural rubber, 60 phr high cis polybutadiene rubber, within 15 seconds to a Banbury mixer 50 C 77rpm. Next, 50 phr, that is, one fourth of the strontium ferrite, 3 phr tackifying resin, 48 phr N660 carbon black, 2.2 phr, Flexzone 4L, N,N' -di- (1 , 4- dimethylpentyl) -p-phenylenediamine, and 7.4 phr Santoflex 6PPD PST, N- (1, 3 -dimethyl-butyl) -N' -phenyl-p-phenylenediamine (9.6 phr total antidegradants), 2.7 phr zinc oxide, were added at 1 minute between 77 and 116 rpms .
• TESPT triethoxy silyl propyl tetrasulfane
• a second masterbatch was formed by adding the first masterbatch, ramming down at 77 to 116 rpms, then adding 4 phr N660 Carbon black, 4 phr aromatic oil and 100 phr strontium ferrite and 2 phr TESPT at 1 minute and discharging at 149°C.
• the maximum mixing cycle was 4 minutes.
• the curative agents specifically 0.5 phr TBBS accelerator, and 1.92 phr soluble sulfur, were added followed by the remaining one half of the second masterbatch, added at 77 rpm.
• the material was rammed down by 30 seconds at 77 rpm.
• the material was discharged at 93.3°C.
• the maximum mixing cycle was 2.5 minutes .
• a side wall composition was formulated as in example 1, except that 3 phr TESPT rather than 2phr was added each time.
• a side wall composition was formulated as in example 1, except that 4 phr TESPT rather than 2phr was added each time.
• Example 4A side wall composition was formulated as in example 1, except that 2phr triethoxy silyl propyl disulfane hereinafter also "TESPD" was used instead of the TESPT.
• TESPD 2phr triethoxy silyl propyl disulfane
• Example 5 The composition was prepared by adding 40 phr natural rubber, 60 phr high cis polybutadiene rubber within 15 seconds to a Banbury mixer 50 °C, 77 rpm. Next, 100 phr strontium ferrite and 4 phr TESPD were added at 45 seconds between 77 and 116 rpm.
• a second masterbatch was firmed by adding the first masterbatch, ramming down at 77 to 116 rpm, then adding 4 phr carbon black, 2.7 phr zinc oxide, 100 phr strontium ferrite and the 4 phr aromatic oil at 35 to 45 seconds and discharging at 149°C.
• the maximum mixing cycle was 4 minutes.
• the second masterbatch was added to the mixer and curative agents, specifically 0.5 phr TBBS accelerator, and 1.92 phr soluble sulfur, were added at 77 rpm.
• curative agents specifically 0.5 phr TBBS accelerator, and 1.92 phr soluble sulfur, were added at 77 rpm.
• the material was rammed down by 30 seconds at 77 to 116 rpm.
• the material was discharged at 93.3°C.
• the maximum mixing cycle was 2.5 minutes.
• Example 6 A composition was prepared as in example 4, except that 6 TESPD was used each time instead of 4 phr.
• Example 7
• a composition was prepared as in example 4, except that 4 phr silica was also added.
• a composition was prepared as in example 4, except that 8 phr silica was also added and 3 phr rather than 2 phr TESPD was added.
• a composition was prepared as in example 5, except that 8 phr silica was also added and 3 phr rather than 2 phr was used.
• Comparative Example A A conventional sidewall composition was prepared according to example 1 except that the TESPT and strontium ferrite were not used and the other ingredients were present as follows: 55 phr natural rubber, 45 phr high cis br butadiene rubber, 52 phr N660 carbon black, 16 PHR aromatic oil, 3 phr tackifying resin, 4.8 phr antidegradants, 2.2 phr microcrystalline paraffin wax, 2.7 phr zinc oxide, 2 phr stearic acid, 0.5 phr TBBS accelerator and 1.92 soluble sulfur.
• a conventional side wall composition was formulated as in Example 1, except that no organoxysilylsulfane was used.
• a conventional side wall composition was formulated as in Example 5, except that no organoxysilylsulfane was used.
• Examples 1-9 The sidewall composition of Examples 1-9 was evaluated for rubber deterioration according to the "Monsanto Fatigue to Failure" test which is based on a modified ASTM D4482-85 test method entitled “Standard Test Method for Rubber Property - Extension Cycling and Fatigue” as described below.
• the material of Examples 1-9 was also evaluated for Pierced DeMattia test according to a modified ASTM D813 test procedure entitled “Standard Test Method Rubber Deterioration - Crack Growth” as described below.
• the "Monsanto Fatigue to Failure” test measures the fatigue life of cured rubber compounds when subjected to flexing at a known elongation.
• the equipment used is as follows, a Monsanto Fatigue to Failure Tester from Flexsys Co. formerly Monsanto, 2689 Wmdgate, Akron, OH ; model FF-1; a fatigue specimen mold according to ASTM D4482; a calibration rod 60 mm from Flexsys Co., 2689 Wmdgate, Akron, OH; a fatigue specimen clicking die (Type E) from Hudson Die Group, Memorial Drive, Avon, MA; and a laboratory mill. A 0.100 + .005" thick sheet was prepared from uncured sidewall compositions of the Examples.
• the sheet was passed in the same direction to obtain the effect of mill direction, to develop the grain direction parallel to the length of the sheeted stock.
• Samples measuring 3"+ 0.025" x 9.5"+ 0.025", with the 9.5" side parallel to the grain of the stock were prepared and placed in the mold to cure at cured for 23 minutes at 160 °C. Samples were conditioned at 73.4° + 5.4° F for at least 24 hours.
• the specimens for testing were prepared by die cutting at right angle to the grain (parallel to the 3" side) using Type "E" die. Samples were run at an extension of 101% or an extension ratio of 2.01 + .05 by mounting cam number 14 on the machine. Samples were run at an extension of 136% or an extension ratio of 2.36 + .08 by mounting cam number 24 on the machine. The cams were fitted with the machine unloaded and the springs at the ends of the beams disconnected. The dynamic beams were moved upward and locked in the static position by pulling out the beam locks on the left hand side of the machine. The rear cam was fitted with its major axis in line with the key on the drive shaft and the front cam is fitted so that it is physically 180° out of phase with the rear cam The rear cam is mounted so that its major axis is in line with the key.
• the specimens were mounted and the retaining clip turned 90° to secure.
• the machine was started and run until 80-100 appeared on the counters. The machine was then stopped. With the hand crank, the cam was rotated until zero strain was obtained.
• each specimen was adjusted until it was subjected to a slight tension, then the tension was relieved until a slight bow in the specimen was just perceptible.
• the specimen has now been adjusted for permanent set. Then the machine was started. The application of zero strain and the tension were repeated every 24 hours until all specimens failed.
• the DeMattia Test evaluates the ability of vulcanized rubber to resist dynamic fatigue. Specifically, the DeMattia flexing machine determines crack growth of vulcanized rubber when subjected to repeated bending strain or flexing. The following equipment was used: DeMattia E-Flexing Machine from Testing Machine Inc. 400 Bayview Ametyville NY; piercing tool for puncturing specimens according to ASTM D-813; mold according to ASTM D813, a curing press capable of exerting a minimum force of 500 psi (3.45 Mpa) on the mold surface; a lab mill capable of maintaining a temperature +/-9°F (5 °C) of set point, Gauge block, 2.56 in. +/- 0.05 in. (65.0 mm +/- 1.3 mm) .
• the sidewall composition of the examples was formed into sheets having a thickness of .275 in. +/- 0.005 in. (7 mm +/- .1 mm). The sheets were conditioned at 73.4 °F +/- 5.4 °F (23 °C +/- 3 °C) for 1 to 24 hours. Die cut specimens, 6 in. x 1 in. (152.4 mm x 25.4 mm), weighing 30 +/- 2 grams were prepared with the grain direction running parallel to the 6" side of the die. The specimens were placed in a pre-heated mold, cured for 24 minutes at 160°C under a pressure of at least 500 psi (3.45 Mpa) on the mold surface. Full pressure was applied and released three times to allow trapped air to escape.
• the specimens were removed from the mold, and submerged in tap water to cool. The edges of each specimen were trimmed to remove any overflow Specimens having a groove surface free of irregularities or defects were selected. Thickness of the specimen is measured within 0.25 in. (6.4 mm) of the groove area and was .250 in. +/- .005 in. (6.4 mm +/- .1 mm). The specimens were then conditioned at room temperature for 12 hours. The specimens were pierced in the center of the groove and sample sides using the piercing tool to provide a hole 2.54 millimeters in diameter. The machine was set up with distance between the stationary and moving grips was 075 in + .01 in.
• the sidewall compositions of examples 5 and 6 were evaluated as above and compared to the composition of Comparative Examples A and C. As shown in Figures 5 and 6, , the organoxysilylsulfane significantly improves the fatigue life of the composition. As shown in Figures 7 and 8, there is also an improvement in the growth crack resistance with the TESPD. The sidewall composition of Examples 7 to 9 was also evaluated but the results indicated that the presence of silica was less preferred.
• Example 2 The sidewall composition of Example 2 was used to form a 2 mil veneer coextruded onto a blackwall of an otherwise conventional 15 inch diameter tire, specifically a p235/75rl5 extra load grapper tire using conventional techniques.
• the 4 tires were subjected to a 72,000 kilometer test on a vehicle.
• the front tires were inflated to 26 psi; the rear tires were inflated to 35 psi and loaded to maximum.
• the tires were periodically examined for the appearance of cracks.
• Three tires completed the test; one tire was removed for unrelated reasons. None of the tires displayed any cracks.
• One tire sidewall experienced a cut due to a road hazard at 18,000 km; no cracks propagated from this cut throughout the test.
• Example 7 The sidewall composition of Example 7 was also evaluated; the fatigue properties were not as good as the other examples suggesting a competition between the silica and strontium ferrite for the organosilane thiosester.
• organoxysilylsulfane has potential binding sites on the strontium ferrite as indicated below:

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