Modified Conjugated Diene Polymer, Polymerization Intitiator, Method of Producing the Same, and Rubber Composition

A polymerization initiator characterized by the following formula (V):

• (wherein R1, R2 and R3 are the same mining as mentioned above;
• Y2 is a substituted silyl group;
• a part of R1, R2, R3 and Y2 may be bonded to each other to form a cyclic structure;
• M1 is an alkali metal or an alkaline earth metal).

A polymerization initiator solution characterized by adding a diamine compound represented by the following formula (VI):

• (wherein R1 and R2 are independently an alkyl or aryl group having a carbon number of 1-20 or a hydrogen atom;
• R3 is the same meaning as mentioned above;
• a part of R1, R2 and R3 may be bonded to each other to form a cyclic structure) with a silyl compound represented by the following formula (VII):
• Y2—X2 (VII)
• (wherein Y2 is the same meaning as mentioned above;
• X2 is one selected from a halogen atom, a thioalkyl group having a carbon number of 1-20, cyano group and trifluoromethylsulfonyl group) and adding an organic alkali metal compound or an organic alkaline earth metal compound thereto.

A method of producing a modified conjugated diene polymer, characterized in that (i) the diamine compound of the formula (VI) is added with the silyl compound of the formula (VII) to form a silylated diamine compound of the formula (VIII);

• (ii) the silylated diamine compound is added with the organic alkali metal compound or the organic alkaline earth metal compound to form the polymerization initiator of the formula (V);
• (iii) the polymerization initiator is added to a solution containing a conjugated diene compound to produce a low molecular weight polymer represented by the following formula (IX):
• (wherein R1, R2, R3, Y2 and M1 are the same meaning as mentioned above;
• a part of R1, R2, R3 nd Y2 may be bonded to each other to form a cyclic structure;
• Oil is an oligomer or polymer portion formed by polymerizing 3-300 conjugated diene compounds);
• and
• (iv) the low molecular weight polymer is added to a solution containing a conjugated diene compound or a solution containing a conjugated diene compound and an aromatic vinyl compound.