Crosslinked rubber, member for tires, vibration-proofing member, member for belts, and rubber composition
A cross-linked rubber exhibits high strength and excellent abrasion resistance as compared with a known cross-linked rubber. The cross-linked rubber is obtained by cross-linking a rubber composition that includes a hydrogenated conjugated diene-based polymer, an olefin-based rubber, and a cross-linking agent, the hydrogenated conjugated diene-based polymer being a hydrogenated product of a polymer that includes a structural unit derived from butadiene, and including at least one of an amino group and a hydrocarbyloxysilyl group at one terminal or each terminal.
1. A pneumatic tire having a tread portion and a sidewall portion,
wherein at least one of the tread portion and the sidewall portion comprises a cross-linked rubber obtained by cross-linking a rubber composition that comprises a hydrogenated conjugated diene-based polymer, an olefin-based rubber, and a cross-linking agent,
wherein the hydrogenated conjugated diene-based polymer is a hydrogenated product of a polymer that comprises a structural unit derived from butadiene and at least one of an amino group and a hydrocarbyloxysilyl group at one terminal or each terminal of the polymer, and
wherein the hydrogenated conjugated diene-based polymer is a random copolymer comprising a structural unit derived from butadiene and a structural unit derived from an aromatic vinyl compound.
2. The pneumatic tire according to claim 1 , wherein the structural unit derived from butadiene that is comprised in the hydrogenated conjugated diene-based polymer has a hydrogenation rate of 70% or more.
3. The pneumatic tire according to claim 1 , wherein a content of a chain that comprises eight or more consecutive structural units derived from an aromatic vinyl compound in the hydrogenated conjugated diene-based polymer is 10 mass % or less based on a total content of the structural units derived from the aromatic vinyl compound.
4. The pneumatic tire according to claim 1 , wherein the aromatic vinyl compound is one or more compounds selected from styrene and α-methylstyrene.
5. The pneumatic tire according to claim 1 , wherein the hydrogenated conjugated diene-based polymer further comprises a structural unit derived from a conjugated diene-based compound other than butadiene.
6. The pneumatic tire according to claim 5 , wherein the conjugated diene-based compound other than butadiene is isoprene.
7. The pneumatic tire according to claim 1 , wherein the hydrogenated conjugated diene-based polymer comprises a polyisoprene block.
8. The pneumatic tire according to claim 7 , wherein a 1,4-bond/3,4-bond ratio in the polyisoprene block is 60/40 to 98/2.
9. The pneumatic tire according to claim 1 , wherein the hydrogenated conjugated diene-based polymer is a polymer produced by polymerizing monomers that comprise 50 to 90 parts by mass of butadiene, 10 to 50 parts by mass of an aromatic vinyl compound, and 0 to 40 parts by mass of a conjugated diene-based compound other than butadiene.
10. The pneumatic tire according to claim 1 , wherein the structural unit derived from butadiene that is comprised in the hydrogenated conjugated diene-based polymer has a 1,2-vinyl content of 5 to 70%.
11. The pneumatic tire according to claim 1 , wherein the at least one of the tread portion and the sidewall portion further comprises one or more additional components selected from the group consisting of a silica, a silane coupling agent and a carbon black.
12. The pneumatic tire according to claim 1 , wherein the hydrogenated conjugated diene-based polymer is a hydrogenated product of a polymer that comprises a structural unit derived from butadiene, and comprising at least one of an amino group and a hydrocarbyloxysilyl group of formula (1) at one terminal or each terminal, wherein the terminal of the polymer at which the hydrocarbyloxysilyl group is bonded is a butadiene block:
wherein A 1 is a monovalent functional group that includes a nitrogen atom, does not include active hydrogen, and is bonded to R 5 through the nitrogen atom,
R 3 and R 4 are each independently a linear or branched alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms,
R 5 is a linear or branched alkanediyl group having 1 to 20 carbon atoms, a cycloalkylene group having 3 to 20 carbon atoms, or an arylene group having 6 to 20 carbon atoms, and
n is an integer from 0 to 2.
13. The pneumatic tire according to claim 12 , wherein the hydrogenated conjugated diene-based polymer is a random copolymer comprising structural units of butadiene and styrene, and optionally isoprene.