Modified conjugated diene-based polymer and rubber composition thereof, and tire

1. A modified conjugated diene-based polymer

having a weight average molecular weight of 20×10 4 or more and 300 ×10 4 or less, and

having a star-branched structure with a conjugated diene-based polymer chain bonded to a modifier residue,

wherein the modifier residue has at least 4 silicon atoms, and alkoxy groups and/or hydroxyl groups and

the conjugated diene-based polymer chain is bonded to the silicon atom,

wherein the number of the alkoxy groups and/or the hydroxyl groups in the modifier residue is larger than the number of the silicon atoms on average, and

the modified conjugated diene-based polymer is represented by the following general formula (2);

wherein P 1 to P 3 each independently represent a conjugated diene-based polymer chain; R 3 , R 4 , R 7 R 12 and R 13 each independently represent an alkylene group having 1 to 20 carbon atoms; R 2 , R 5 and R 8 each independently represent an alkyl group having 1 to 20 carbon atoms; R 1 , R 6 and R 9 each independently represent a hydrogen atom or an alkyl group having 1 to 20 carbon atoms; and R 10 and R 11 each independently represent a hydrogen atom or an alkyl group having 1 to 20 carbon atoms; x, y and z each independently represent an integer of 1 to 2; p and t each independently represent an integer of 1 to 2; q, s and u each independently represent an integer of 0 to 3; r represents an integer of 0 to 6; the number of the conjugated diene-based polymer chain ((x×p)+(y×r)+(z×t)) is an integer of 3 to 20; ((q×p)+(s×r)+(u×t)) exceeds the number of the silicon atoms, and a ratio ((q×p)+(s×r) +(u×t))/((x×p)+(y×r) +(z x t)) exceeds 0.5.

2. The modified conjugated diene-based polymer according to claim 1 , wherein the number of the alkoxy groups and/or the hydroxyl groups in the modifier residue is 1.2 times or more of the number of the silicon atoms on average.

3. The modified conjugated diene-based polymer according to claim 2 , wherein the modifier residue has at least 2 nitrogen atoms and at least 4 silicon atoms.

4. A rubber composition comprising:

a rubber component and 5.0 parts by mass or more and 150 parts by mass or less of a filler based on 100 parts by mass of the rubber component,

wherein the rubber component comprises 10% by mass or more of the modified conjugated diene-based polymer according to claim 3 based on a total amount of the rubber component.

5. A tire comprising the rubber composition according to claim 4 .

6. The modified conjugated diene-based polymer according to claim 2 , represented by the following general formula (2);

wherein P 1 to P 3 each independently represent a conjugated diene-based polymer chain; R 3 , R 4 , R 7 R 12 and R 13 each independently represent an alkylene group having 1 to 20 carbon atoms; R 2 , R 5 and R 8 each independently represent an alkyl group having 1 to 20 carbon atoms; R 1 , R 6 and R 9 each independently represent a hydrogen atom or an alkyl group having 1 to 20 carbon atoms; and R 10 and R 11 each independently represent a hydrogen atom or an alkyl group having 1 to 20 carbon atoms; x, y and z each independently represent an integer of 1 to 2; p and t each independently represent an integer of 1 to 2; q, s and u each independently represent an integer of 0 to 3; r represents an integer of 0 to 6; the number of the conjugated diene-based polymer chain ((x×p)+(y×r)+(z×t)) is an integer of 3 to 20; ((q×p)+(s×r)+(u×t)) exceeds the number of the silicon atoms, and a ratio ((q×p)+(s×r) +(u×t))/((x×p)+(y×r)+(z×t)) exceeds 0.5.

7. A rubber composition comprising:

a rubber component and 5.0 parts by mass or more and 150 parts by mass or less of a filler based on 100 parts by mass of the rubber component,

wherein the rubber component comprises 10% by mass or more of the modified conjugated diene-based polymer according to claim 6 based on a total amount of the rubber component.

8. A tire comprising the rubber composition according to claim 7 .

9. The modified conjugated diene-based polymer according to claim 1 , wherein the modifier residue has at least 2 nitrogen atoms and at least 4 silicon atoms.

10. An oil-extended modified conjugated diene-based polymer comprising:

100 parts by mass of the modified conjugated diene-based polymer according to claims 1 , and

1 to 60 parts by mass of an extender oil.

11. A rubber composition comprising:

a rubber component and 5.0 parts by mass or more and 150 parts by mass or less of a filler based on 100 parts by mass of the rubber component,

wherein the rubber component comprises 10% by mass or more of the modified conjugated diene-based polymer according to claim 1 based on a total amount of the rubber component.

12. A tire comprising the rubber composition according to claim 11 .

13. The modified conjugated diene-based polymer according to claim 1 , wherein a modification ratio of the modified conjugated diene-based polymer is 30% by mass or more.

14. The modified conjugated diene-based polymer according to claim 1 , wherein a modification ratio of the modified conjugated diene-based polymer is 50% by mass or more.

15. The modified conjugated diene-based polymer according to claim 1 , wherein a modification ratio of the modified conjugated diene-based polymer is 70% by mass or more.

16. The modified conjugated diene-based polymer according to claim 1 , wherein the modified conjugated diene-based polymer comprises an oil-extended modified conjugated diene-based polymer in which an extender oil is added to the modified conjugated diene-based polymer.

17. The modified conjugated diene-based polymer according to claim 16 , wherein the extender oil comprises an aroma oil, a naphthenic coil and a paraffin oil.