Natural rubber compounds with silica and use with tires
A rubber composition including guayule rubber and 15 to 90 phr silica. The rubber can be cis-1,4 polyisoprene and include 15 to 90 phr silica and contain less than 20% of the proteins associated with Hevea rubber and further include at least a trace of resins present in other natural rubbers. The rubber can be cis-1,4 polyisoprene and further include between at least a trace and 3% by weight of resins present in guayule rubber. The rubber composition can further be comprised of a synthetic rubber and include between about 40-100 phr of guayule rubber, and silica. The silica can be hydrophobated.
1. A rubber composition comprising guayule rubber, 15 to 90 phr silica, at least one of an oil and a resin, and a synthetic rubber, said silica including a silane coupling agent.
2. The rubber composition of claim 1 wherein the silane coupling agent is selected from the group including bis(triethoxysilypropyl)tetrasulfide (TESPT), bis(triethoxysilypropyl-y)disulfide (TESPD), 3-mercaptopropyl trimethoxy silane (A-189), and 3-mercaptopropyl triethoxy silane (A-1891).
3. The rubber composition of claim 1 wherein the silica is pretreated with the silane coupling agent prior to mixing with the rubber.
4. A rubber composition of claim 1 wherein the surface area of the silica is between 175 and 90 m 2 /gm.
5. The rubber composition of claim 1 comprising between about 40-100 phr of guayule rubber.
6. The rubber composition of claim 1 including carbon black at a lesser amount than said silica.
7. The rubber composition of claim 1 including about 20 to 80 phr silica.
8. The rubber composition of claim 1 comprising between 50-80 phr silica.
9. Finished rubber articles containing the rubber composition of claim 1 .
10. A tire containing the rubber composition of claim 1 .
11. A tread component of a tire containing the rubber composition of claim 1 .
12. A tread component of a truck tire containing the rubber composition of claim 1 .
13. A tread component of an aircraft tire containing the rubber composition of claim 1 .
14. The composition of claim 1 wherein the guayule rubber is non-functionalized.