Tire with rubber component containing reinforcement comprised of precipitated silica and functionalized graphene

Abstract

This invention relates to a tire having a rubber component, such as a tread. with filler reinforcement containing surface modified graphene and precipitated silica which may be or may include pre-hydrophobated precipitated silica.

Claims

1. A tire with a component of a rubber composition which comprises, based upon parts by weight per 100 parts by weight rubber (phr): (A) 100 phr of at least one diene-based elastomer, (B) rubber reinforcing filler as a combination of rubber reinforcing carbon black, precipitated silica and graphene comprised of: (1) from about 0 to about 30 phr of rubber reinforcing carbon black, (2) from about 25 to about 125 phr of precipitated silica, with silica coupler for said precipitated silica having a moiety reactive with hydroxyl groups on the precipitated silica and another, different, moiety interactive with said diene-based elastomer(s), (3) about 0.5 to about 20 phr of graphene, treated with a phenylene ethynylene oligomer comprised of a conjugated hydrocarbon backbone and having a branched polysulfide moiety, wherein said oligomer is comprised of a compound of a chemical structure represented by at least one of Formula (1), (2) and (3): ##STR00004## wherein R is comprised of hydrocarbon, C.sub.nH.sub.2n+1; where n is in the range of 4 to 16, x is in a range of 0 to 10, y is in a range of 0 to 10; and z is in a range of 1 to 3; wherein at least one of x and y is at least 1; wherein R′ is a cyclic six member saturated ring comprised of sulfur and carbon atoms which contains from 2 through 5 connecting sulfur atoms and from 1 through 4 carbon atoms.

2. The tire of claim 1 wherein said graphene has an average thickness in a range of from about 1 to about 20 nanometers (nm) and a L/D (lateral length over thickness) dimensional ratio in a range of from about 10 to about 1000.

3. The tire of claim 1 where, for the tread rubber composition, the said diene-based elastomer is comprised of at least one polymer of at least one monomer selected from isoprene and 1,3-butadiene and from styrene copolymerized with at least one of isoprene and 1,3-butadiene.

4. The tire of claim 2 where, for the tread rubber composition, the said diene-based elastomer is comprised of at least one polymer of at least one monomer selected from isoprene and 1,3-butadiene and from styrene copolymerized with at least one of isoprene and 1,3-butadiene.

5. The tire of claim 1 where, for the tread rubber composition, the diene-based rubber is natural cis 1,4-polyisoprene rubber.

6. The tire of claim 1 where, for the tread rubber composition, the diene-based rubber is natural cis 1,4-polyisoprene rubber together with at least one synthetic rubber.

7. The tire of claim 1 wherein, for said tread rubber composition, at least one of said diene-based elastomer(s) is least one of tin coupled organic solution polymerization prepared styrene/butadiene copolymers, isoprene/butadiene copolymers, styrene/isoprene copolymers, polybutadiene and styrene/isoprene/butadiene terpolymers.

8. The tire of claim 7 wherein, for said tread rubber composition, said tin coupled diene-based elastomer is an organic solution polymerization prepared styrene/butadiene copolymer.

9. The tire of claim 1 wherein, for said rubber composition, the diene-based elastomer contains at least one functional group reactive with hydroxyl groups on a precipitated silica wherein said functional group is comprised of at least one of siloxy, amine, imine and thiol groups.

10. The tire of claim 8 wherein said tin coupled butadiene/styrene rubber contains at least one functional group reactive with hydroxyl groups on a precipitated silica wherein said functional group is comprised of at least one of siloxy, amine, imine and thiol groups.

11. The tire of claim 1 wherein said precipitated silica and silica coupler are provided as a composite of precipitated silica pre-reacted with said silica coupler and where said silica coupler is comprised of at least one of bis(3-trialkoxysilylpropyl) polysulfide containing an average of from about 2 to about 4 connecting sulfur atoms in its polysulfidic bridge and alkoxyorganomercaptosilane.

12. The tire of claim 11 wherein said composite of pre-reacted precipitated silica is the product of precipitated silica and bis(3-triethoxysilylpropyl) polysulfide.

13. The tire of claim 11 wherein said composite of pre-reacted precipitated silica is the product of precipitated silica and alkoxyorganomercaptosilane.

14. The tire of claim 1 wherein precipitated silica is added to said rubber composition to react with said coupling agent in situ within the rubber composition.

15. The tire of claim 11 wherein precipitated silica is also added to said rubber composition to react with coupling agent in situ within the rubber composition.

16. The tire of claim 1 wherein said oligomer is comprised of the oligomer of Formula (1).

17. The tire of claim 1 wherein said oligomer is comprised of the oligomer of Formula (2).

18. The tire of claim 1 wherein said oligomer is comprised of the oligomer of Formula (3).

19. The tire of claim 1 wherein said component is a circumferential tread.

20. The tire of claim 10 wherein said component is a circumferential tread.

Description

EXAMPLE I

(1) An exemplary Control rubber Sample A, Comparative rubber Sample B, Experimental rubber Sample C and Comparative rubber Sample D are provided to illustrate preparation of rubber compositions.

(2) Control rubber Sample A is composed of diene-based elastomers and reinforcing filler as precipitated silica with a minimal content of carbon black.

(3) Comparative rubber Sample B is similar to Control rubber Sample A except that it contains the 5 phr of carbon nanotubes (CNT) pretreated with the poly(phenylene ethynylene) oligomer and reduced loading level of precipitated silica.

(4) Experimental rubber Sample C is similar to Comparative rubber Sample B except that it contained 5 phr graphene platelets pretreated with the poly(phenylene ethynylene) oligomer (GP) instead of the pretreated carbon nanotubes.

(5) Comparative rubber Sample D is similar to Experimental rubber Sample C except that it contained a significant content of rubber reinforcing carbon black instead of the graphene.

(6) In this example, the coupling agent used to pretreat the graphene is comprised of the chemical structure illustrated by Formula (3B) as a derivation of Formula (3A) were x equals zero:

(7) ##STR00003##

(8) wherein, x equals 0; y is in the range of 3 to 10, z is in the range of 1 to 3, and the cyclic R′ contains about 5 connecting sulfur atoms and 1 carbon atom, as illustrated by Formula (3B).

(9) The basic formulation for the rubber Samples is illustrated in the following Table 1 where the ingredients are expressed in terms of parts by weight per 100 parts of rubber (phr) unless otherwise indicated.

(10) The rubber compositions may be prepared, for example, by mixing the ingredients in at least two sequential preparatory (non-productive) mixing steps (e.g. NP1 and NP2) at an elevated temperature without sulfur and sulfur cure accelerators which are thereafter added in a final (productive) mixing step (PR) usually at a lower mixing temperature. The rubber composition may then sheeted out and cooled to below 50° C. between each of the non-productive mixing steps and prior to the productive mixing step. Rubber mixing steps involving non-productive and productive mixing steps are generally well known to those having skill in such art.

(11) TABLE-US-00001 TABLE 1 Parts (phr) Con- Com- Experi- Com- trol pound mental pound A B (CNT) C (GP) D Non-Productive Mixing Step (NP1) SSBR rubber (styrene/ 70 70 70 70 butadiene rubber).sup.1 Cis 1,4-polybutadiene rubber.sup.2 30 30 30 30 Carbon black, rubber 5.2 1.2 1.2 70 reinforcing (N120).sup.3 Precipitated silica.sup.4 65 50 50 0 Silica coupler.sup.5 5.2 4 4 0 Wax, crystalline and paraffin 1.5 1.5 1.5 1.5 Rubber processing oil 20 20 20 20 Antioxidant(s) 2.2 2.2 2.2 2.2 Graphene (pretreated) 0 0 5 0 Carbon nanotube (pretreated) 0 5 0 0 Zinc oxide 3.5 3.5 3.5 3.5 Fatty acid.sup.6 2 2 2 2 Productive Mixing Step (PR) Sulfur 1.7 1.7 1.7 1.7 Accelerator(s).sup.7 1.6 1.6 1.6 1.6 Diphenylguandine (DPG) 1.5 1.5 1.5 0 .sup.1Styrene/butadiene elastomer (SSBR) prepared by solvent solution polymerization, tin coupled and end-functionalized with what is understood to be alkoxy and a combination of amine and thiol functional groups and having a styrene content of about 21 percent rubber as SLR4606 ™ from Trinseo .sup.2Cis 1,4-polybutadiene rubber as BUD1223 ™ from The Goodyear Tire & Rubber Company .sup.3Rubber reinforcing carbon black as N120, an ASTM designation .sup.4Precipitated silica as Zeosil 1165MP ™ from Solvay .sup.5Silica coupler comprised of a bis(3-triethoxysilylpropyl) polysulfide containing an average from about 2 to about 2.6 connecting sulfur atoms in its polysulfidic bridge as Si266 ™ from Evonik .sup.6Mixture of fatty acids comprised of stearic, palmitic and oleic acids .sup.7Sulfenamide sulfur cure accelerator

(12) The carbon nanotubes were obtained as Graphistrength C100™ a product from Arkema; the graphene as N002001-P™ a product from Angstron Materials and oligomer as Kentera™ a product from Zyvex.

(13) The following Table 2 represents the uncured and cured behavior and various physical properties of the rubber compositions based upon the basic formulation of Table 1 and reported for rubber Samples A, B, C and D.

(14) TABLE-US-00002 TABLE 2 Samples (phr) Con- Com- Experi- Com- trol pound mental pound A B (CNT) C (GP) D Non-Productive Mixing Step (NP1) SSBR elastomer 70 70 70 70 Cis 1,4-polybutadiene rubber 30 30 30 30 Rubber reinforcing carbon black 5.2 5.2 5.2 70 Precipitated silica 65 50 50 0 Graphene, pretreated 0 0 5 0 Carbon nanotube, pretreated 0 5 0 0 Silica coupler 5.2 4 4 0 Properties RPA test (Rubber Process Analyzer), 10% strain, 11 Hertz, 100° C. Storage modulus G′ (MPa) 2.03 2.28 1.76 3.47 Tan delta 0.12 0.09 0.07 0.17 Rebound (100° C.), (higher is better) 65 70 74 57 (percent) DIN abrasion (lower is better).sup.1 104 104 131 128 Stress-strain Tensile strength (MPa) 15 14 13 18 Elongation at break (%) 401 360 376 377 300% modulus, ring, (MPa) 11 12 11 15 Cure: MDR test, 150° C. Delta torque (dN-m) 15.6 16.9 16.2 17.3 T25 (minutes) 5.1 3.7 4.5 3.2 T90 (minutes) 10.2 6.9 7.6 6.2 Thermal Conductivity Thermal conductivity (W/m/K) 0.267 0.287 0.343 0.311 Thermal diffusivity (mm.sup.2/s) (transmission rate) 0.142 0.161 0.224 0.173 .sup.1DIN53516, relative volume loss

(15) It can be seen from Table 2 that the addition of 5 phr of the treated graphene in Experimental rubber Sample C to replace 15 phr of the precipitated silica of Control rubber Sample A (reduction of 65 to 50 phr of precipitated silica) significantly and beneficially reduced the hysteresis of the rubber composition as evidenced by the increased 100° C. rebound value of 74 percent from a value of 65 percent for Control rubber Sample A which is about a 14 percent beneficial improvement for Experimental rubber Sample C.

(16) It can further be seen from Table 2 that the addition of 5 phr of the treated graphene significantly and beneficially increased the thermal conductivity to a value of 0.343 for Experimental rubber Sample C as compared to a value of 0.267 for Control rubber Sample A which is about a 29 percent improvement.

(17) It is also seen that the treated graphene is much more effective in improving the thermal conductivity (Experimental rubber Sample C) than the carbon nanotube (Comparative rubber Sample C) and carbon black reinforcement (Comparative rubber Sample D).

(18) Therefore, it is concluded that rather minimal amount of addition of the pretreated graphene to the rubber composition can significantly and beneficially improve (increase) the hot rebound (100° C.) physical property of the rubber composition to therefore improve (reduce) predictive rolling resistance for a tire with tread of Experimental rubber Sample C as well as improve (increase) the rubber composition's thermal conductivity.

(19) While various embodiments are disclosed herein for practicing the invention, it will be apparent to those skilled in this art that various changes and modifications may be made therein without departing from the spirit or scope of the invention.