Rubbery polymer and method for producing the same

A catalyst comprising a lithium-containing organic polymer which is obtained by a method comprising:

• providing a mixture of a first polymerizable material comprising at least one conjugated diene monomer and a second polymerizable material comprising at least one aromatic vinyl compound, said second polymerizable material containing at least one multi-vinyl aromatic compound having at least two vinyl groups, and
• adding an organolithium compound to said mixture of the first polymerizable material and the second polymerizable material, to thereby perform a reaction of the first polymerizable material and the second polymerizable material in the presence of said organolithium compound,
• wherein the content of said at least one multi-vinyl aromatic compound in said lithium-containing organic polymer is from 6.2 to 40% by weight,
• the weight average molecular weight of said lithium-containing organic polymer is from 500 to 20,000, and
• said lithium-containing organic polymer has an Mw/Mn ratio of from 1.2 to 3.5 wherein Mw represents the weight average molecular weight of said lithium-containing organic polymer and Mn represents the number average molecular weight of said lithium-containing organic polymer.

A method for producing a rubbery polymer, which comprises polymerizing at least one conjugated diene monomer in the presence of a catalyst in a hydrocarbon solvent,

• said catalyst comprising a lithium-containing organic polymer which is obtained by a method comprising:
• providing a mixture of a first polymerizable material comprising at least one conjugated diene monomer and a second polymerizable material comprising at least one aromatic vinyl compound, said second polymerizable material containing at least one multi-vinyl aromatic compound having at least two vinyl groups, and
• adding an organolithium compound to said mixture of the first polymerizable material and the second polymerizable material, to thereby perform a reaction of the first polymerizable material and the second polymerizable material in the presence of said organolithium compound,
• wherein the content of said at least one multi-vinyl aromatic compound in said lithium containing organic polymer is from 6.2 to 40% by weight,
• the weight average molecular weight of said lithium-containing organic polymer is from 500 to 20,000, and said lithium containing organic polymer has an Mw/Mn ratio
• of from 1.2 to 3.5 wherein Mw represents the weight average molecular weight of said lithium-containing organic polymer and Mn represents the number average molecular weight of said lithium-containing organic polymer,
• said rubbery polymer comprising a conjugated diene polymer having bonded thereto a lithium-detached residue of said lithium-containing organic polymer.