Copolymer, rubber composition, crosslinked rubber composition, and tire
Provided is a copolymer of a conjugated diene compound and a non-conjugated olefin, the copolymer being a tapered copolymer including: at least one of a block sequence including monomer units of the conjugated diene compound and a block sequence including monomer units of the non-conjugated olefin; and a random sequence including randomly arranged monomer units of the conjugated diene compound and monomer units of the non-conjugated olefin.
1. A copolymer of a conjugated diene compound and a non-conjugated olefin, comprising a copolymer including: at least one of a block sequence including monomer units of the conjugated diene compound and a block sequence including monomer units of the non-conjugated olefin; and a random sequence including randomly arranged monomer units of the conjugated diene compound and monomer units of the non-conjugated olefin,
wherein each of the block sequences includes conjugated diene compound block components or non-conjugated olefin block components having an absolute molecular weight of more than 10,000 and the random sequence includes conjugated diene compound block components or non-conjugated olefin block components having an absolute molecular weight of 10,000 or less, and
wherein the content of a long-chain non-conjugated olefin component having a number-average molecular weight (Mn) of 40,000 or more, which refers to the block sequence including monomer units of the non-conjugated olefin, is more than 1 mass % to 20 mass % of the total non-conjugated olefin component in the copolymer.
2. The copolymer according to claim 1 , wherein the conjugated diene compound unit has a cis-1,4 bond content of at least 30%.
3. The copolymer according to claim 2 , wherein the conjugated diene compound unit has a cis-1,4 bond content of at least 50%.
4. The copolymer according to claim 1 , wherein the conjugated diene compound unit has 1,2 adducts (including 3,4 adducts) content of 5% or less.
5. The copolymer according to claim 1 , wherein the non-conjugated olefin is contained over 0 mol % to 50 mol % or less.
6. The copolymer according to claim 5 , wherein the non-conjugated olefin is contained over 0 mol % to 40 mol % or less.
7. The copolymer according to claim 1 , wherein the copolymer has any one of the structures of (A-B) x , A-(B-A) x and B-(A-B) x ,
wherein A represents a random sequence including randomly arranged monomer units of the conjugated diene compound and the non-conjugated olefin, B represents one of a block sequence including monomer units of the conjugated diene compound and a block sequence including monomer units of the non-conjugated olefin, and x represents an integer of at least 1.
8. The copolymer according to claim 1 , comprising a copolymer having a molecular weight distribution (Mw/Mn) of 10 or less.
9. The copolymer according to claim 1 , wherein the non-conjugated olefin is an acyclic olefin.
10. The copolymer according to claim 1 , wherein the non-conjugated olefin has 2 to 10 carbon atoms.
11. The copolymer according to claim 9 , wherein the non-conjugated olefin is at least one selected from a group consisting of ethylene, propylene, and 1-butene.
12. The copolymer according to claim 11 , wherein the non-conjugated olefin is ethylene.
13. The copolymer according to claim 1 , wherein the conjugated diene compound is at least one selected from a group consisting of 1,3-butadiene and isoprene.
14. A rubber composition comprising the copolymer according to claim 1 .
15. The rubber composition according to claim 14 comprising the copolymer in a rubber component.
16. The rubber composition according to claim 14 , comprising, with respect to 100 parts by mass of the rubber component, a reinforcing filler by 5 parts by mass to 200 parts by mass and a crosslinking agent by 0.1 parts by mass to 20 parts by mass.
17. A crosslinked rubber composition obtained by crosslinking the rubber composition according to claim 14 .
18. A tire manufactured by using the rubber composition according to claim 14 .
19. A tire manufactured by using the crosslinked rubber composition according to claim 17 .
20. The copolymer according to claim 1 , wherein the copolymer is polymerized while adjusting the ratio of the concentration of the non-conjugated olefin to the concentration of the conjugated diene compound in the polymerization system.