Method for producing modified conjugated diene based (co)polymer, modified conjugated diene based (co)polymer, and rubber composition

A method for producing a modified conjugated diene based (co)polymer, comprising:

• (a) obtaining a primarily modified polymer by carrying out a primary modification reaction wherein at least one member selected from the group consisting of an alkoxysilane compound and a silanol compound is introduced into the active alkali metal terminal of a conjugated diene based (co)polymer having an active alkali metal terminal, wherein the conjugated diene based (co)polymer is obtained by subjecting at least a diene monomer to anionic polymerization in a hydrocarbon solvent comprising an alkali metal-based initiator, and
• (b) subjecting the above-obtained primarily modified polymer to reactions comprising (b1) and (b2) to obtain a secondarily modified polymer (a modified conjugated diene based (co)polymer),
• (b1):
• a reaction with a condensation accelerator comprising a metal element, and
• (b2):
• a reaction with at least one member selected from the group consisting of inorganic acids and metal halides.