Modified conjugated diene-based polymer, method for producing the same, modified conjugated diene-based polymer composition, and tire

1. A modified conjugated diene-based polymer having a silyl group substituted with one or more alkoxy groups, and one or more nitrogen atoms on the chain ends of the conjugated diene-based polymer,

the modified conjugated diene-based polymer being obtained by polymerizing a conjugated diene compound, or copolymerizing a conjugated diene compound with an aromatic vinyl compound,

by using a polyfunctional anionic polymerization initiator prepared from a polyvinyl aromatic compound and an organolithium compound in a range of a molar ratio (the polyvinyl aromatic compound/the organolithium compound) of from 0.05 to 1.0, so as to obtain the conjugated diene-based polymer, and

by reacting a living polymer end of the conjugated diene-based polymer with a compound having a silyl group substituted with two or more alkoxy groups, and one or more nitrogen atoms.

2. The modified conjugated diene-based polymer according to claim 1 , wherein a modification ratio determined by an amount adsorbed onto a column of gel permeation chromatography measurement using silica particle-packed column is 78% by mass or more.

3. The modified conjugated diene-based polymer according to claim 1 , wherein a molar ratio of the polyvinyl aromatic compound to the organolithium compound is in a range of from 0.1 to 0.45.

4. The modified conjugated diene-based polymer according to claim 1 , wherein the compound having the silyl group substituted with two or more alkoxy groups, and one or more nitrogen atoms is represented by the following formula (1):

wherein each of R 1 and R 2 independently represents an alkyl group having 1 to 20 carbon atoms, or an aryl group; R 3 represents an alkylene group having 1 to 20 carbon atoms; R 4 and R 5 , may be identical or different from each other, represent a hydrocarbon group having 1 to 6 carbon atoms, and form a 5 or more-membered ring structure together with two adjacent N; R 6 represents a hydrocarbon group having 1 to 20 carbon atoms, a hydrocarbon group substituted with a heteroatom having no active hydrogen and having 1 to 20 carbon atoms, or a triorgano-substituted silyl group; and m is an integer of 2 or 3, or, by the following formula (2):

wherein the definitions of R 1 to R 6 and m are the same as in the formula (1) described above; and R 7 represents a hydrocarbon group having 1 to 20 carbon atoms, a hydrocarbon group which may be substituted with a heteroatom having no active hydrogen and having 1 to 20 carbon atoms, or a triorgano-substituted silyl group.

5. A modified conjugated diene-based polymer, wherein in gel permeation chromatography measurement using a polystyrenic gel-packed column,

the peak area on the lowest molecular weight side accounts for 20 to 50% of an area of a whole chromatogram; and

a modification ratio determined by an amount adsorbed onto a column used in gel permeation chromatography measurement using a silica particle-packed column is 78% by mass or more.

6. A method for producing a modified conjugated diene-based polymer, comprising the steps of:

reacting a polyvinyl aromatic compound with an organolithium compound to prepare a polyfunctional anionic polymerization initiator in a range of a molar ratio of the polyvinyl aromatic compound to the organolithium compound of from 0.05 to 1.0;

polymerizing a conjugated diene compound, or copolymerizing a conjugated diene compound with an aromatic vinyl compound by using the polyfunctional anionic polymerization initiator, so as to obtain a conjugated diene-based polymer; and

reacting a living polymer end of the conjugated diene-based polymer with a compound having a silyl group substituted with two or more alkoxy groups, and one or more nitrogen atoms.

7. The method for producing the modified conjugated diene-based polymer according to claim 6 , wherein a molar ratio of the polyvinyl aromatic compound to the organolithium compound is in a range of from 0.1 to 0.45.

8. The method for producing the modified conjugated diene-based polymer according to claim 6 , wherein the compound having a silyl group substituted with two or more alkoxy groups, and one or more nitrogen atoms is represented by the following formula (1):

wherein each of R 1 and R 2 independently represents an alkyl group having 1 to 20 carbon atoms, or an aryl group; R 3 represents an alkylene group having 1 to 20 carbon atoms; R 4 and R 5 , may be identical or different from each other, represent a hydrocarbon group having 1 to 6 carbon atoms, and form a 5 or more-membered ring structure together with two adjacent N; R 6 represents a hydrocarbon group having 1 to 20 carbon atoms, a hydrocarbon group substituted with a heteroatom having no active hydrogen and having 1 to 20 carbon atoms, or a triorgano-substituted silyl group; and m is an integer of 2 or 3, or, by the following formula (2):

wherein the definitions of R 1 to R 6 and m are the same as in the formula (1) described above; and R 7 represents a hydrocarbon group having 1 to 20 carbon atoms, a hydrocarbon group which may be substituted with a heteroatom having no active hydrogen and having 1 to 20 carbon atoms, or a triorgano-substituted silyl group.

9. A modified conjugated diene-based polymer composition, comprising 0.5 to 300 parts by mass of a silica-based inorganic filler with respect to 100 parts by mass of a rubber component comprising 20 parts by mass or more of the modified conjugated diene-based polymer according to claim 1 .

10. The modified conjugated diene-based polymer composition according to claim 9 , further comprising 0.5 to 100 parts by mass of carbon black with respect to 100 parts by mass of the rubber component comprising 20 parts by mass or more of the modified conjugated diene-based polymer.

11. The modified conjugated diene-based polymer composition according to claim 9 , wherein the silica-based inorganic filler has a nitrogen adsorption specific surface area of 170 m 2 /g or more.

12. A tire comprising the modified conjugated diene-based polymer composition according to claim 9 .

13. The modified conjugated diene-based polymer according to claim 2 , wherein a molar ratio of the polyvinyl aromatic compound to the organolithium compound is in a range of from 0.1 to 0.45.

14. The modified conjugated diene-based polymer according to claim 2 , wherein the compound having the silyl group substituted with two or more alkoxy groups, and one or more nitrogen atoms is represented by the following formula (1):

wherein each of R 1 and R 2 independently represents an alkyl group having 1 to 20 carbon atoms, or an aryl group; R 3 represents an alkylene group having 1 to 20 carbon atoms; R 4 and R 5 , may be identical or different from each other, represent a hydrocarbon group having 1 to 6 carbon atoms, and form a 5 or more-membered ring structure together with two adjacent N; R 6 represents a hydrocarbon group having 1 to 20 carbon atoms, a hydrocarbon group substituted with a heteroatom having no active hydrogen and having 1 to 20 carbon atoms, or a triorgano-substituted silyl group; and m is an integer of 2 or 3, or, by the following formula (2):

wherein the definitions of R 1 to R 6 and m are the same as in the formula (1) described above; and R 7 represents a hydrocarbon group having 1 to 20 carbon atoms, a hydrocarbon group which may be substituted with a heteroatom having no active hydrogen and having 1 to 20 carbon atoms, or a triorgano-substituted silyl group.

15. The method for producing the modified conjugated diene-based polymer according to claim 7 , wherein the compound having a silyl group substituted with two or more alkoxy groups, and one or more nitrogen atoms is represented by the following formula (1):

wherein each of R 1 and R 2 independently represents an alkyl group having 1 to 20 carbon atoms, or an aryl group; R 3 represents an alkylene group having 1 to 20 carbon atoms; R 4 and R 5 , may be identical or different from each other, represent a hydrocarbon group having 1 to 6 carbon atoms, and form a 5 or more-membered ring structure together with two adjacent N; R 6 represents a hydrocarbon group having 1 to 20 carbon atoms, a hydrocarbon group substituted with a heteroatom having no active hydrogen and having 1 to 20 carbon atoms, or a triorgano-substituted silyl group; and m is an integer of 2 or 3, or, by the following formula (2):

wherein the definitions of R 1 to R 6 and m are the same as in the formula (1) described above; and R 7 represents a hydrocarbon group having 1 to 20 carbon atoms, a hydrocarbon group which may be substituted with a heteroatom having no active hydrogen and having 1 to 20 carbon atoms, or a triorgano-substituted silyl group.

16. A modified conjugated diene-based polymer composition, comprising 0.5 to 300 parts by mass of a silica-based inorganic filler with respect to 100 parts by mass of a rubber component comprising 20 parts by mass or more of the modified conjugated diene-based polymer according to claim 2 .

17. The modified conjugated diene-based polymer composition according to claim 16 , further comprising 0.5 to 100 parts by mass of carbon black with respect to 100 parts by mass of the rubber component comprising 20 parts by mass or more of the modified conjugated diene-based polymer.

18. The modified conjugated diene-based polymer composition according to claim 16 , wherein the silica-based inorganic filler has a nitrogen adsorption specific surface area of 170 m 2 /g or more.

19. A tire comprising the modified conjugated diene-based polymer composition according to claim 16 .