A catalyst composition capable of forming a conjugated diene-based polymer having a narrow molecular weight distribution by being used in polymerization of a conjugated diene-based monomer, a method of preparing the same, a method of preparing a conjugated diene-based polymer using the catalyst composition, and a conjugated diene-based polymer prepared by the method of preparing the polymer are provided. Since the catalyst composition according to the present invention includes a polymer having a number-average molecular weight of 3,000 g/mol to 10,000 g/mol and including a conjugated diene-based monomer-derived unit, the catalyst composition may be used in the polymerization of a conjugated diene-based monomer to prepare a conjugated diene-based polymer having a narrower molecular weight distribution in comparison to a conventional neodymium catalyst composition.

Embodiments of this disclosure are directed to polymerization process comprising contacting ethylene and optionally one or more α-olefins in solution in the presence of one or more catalyst systems and a chain transfer agent, wherein the catalyst system comprises a metal-ligand complex according to formula (I).

##STR00001##

A polymerization catalyst composition contains a rare earth element carboxylate, a phosphate ester represented by the following general formula (1):

##STR00001##

(wherein Rs are each independently an alkyl group having 5 to 20 carbon atoms), and water.

A polymerization catalyst composition contains a rare earth element carboxylate, a phosphate ester represented by the following general formula (1):

##STR00001##

(wherein Rs are each independently an alkyl group having 5 to 20 carbon atoms), and water.

A method for preparing a modified conjugated diene-based polymer is provided. The method is characterized in adding a polyoxyethylene phosphate ester-based compound having a specific structure together with sulfur chloride modifier during modification, by which modification reproducibility may be markedly improved, stable process may be performed, the changing degree of the physical properties, specifically a Mooney viscosity increasing ratio and the degree of branching of a modified conjugated diene-based polymer according to modification conditions may be anticipated, and the changing degree of a Mooney viscosity increasing ratio and the degree of branching may be easily controlled by controlling modification conditions.

The present invention relates to a method for preparing a modified conjugated diene-based polymer having excellent physical properties such as tensile properties and viscoelasticity properties with a high modification ratio.

The present invention provides a method for preparing a transition metal complex, including a step of preparing a dispersion including a transition metal salt or alkoxide, and a coordinating solvent; and a step of reacting an organic borate-based compound containing a carbon-based, silyl-based or amine-based cation and a borate-based bulky anion, with the dispersion, wherein the transition metal is one or more selected from the metals in group 7 to group 12.

The present invention provides a method for preparing a transition metal complex, including a step of preparing a dispersion including a transition metal salt or alkoxide, and a coordinating solvent; and a step of reacting an organic borate-based compound containing a carbon-based, silyl-based or amine-based cation and a borate-based bulky anion, with the dispersion, wherein the transition metal is one or more selected from the metals in group 7 to group 12.

Disclosed herein area process for preparing a modified high-cis polybutadiene polymer, a modified high-cis polybutadiene polymer, and tires having a component made using the modified high-cis polybutadiene polymer. The processes make use of a functionalizing compound of formula (I) to prepare the modified high-cis polybutadiene from a quantity of 1,3-butadiene monomer using a specified catalyst system.

Disclosed herein area process for preparing a modified high-cis polybutadiene polymer, a modified high-cis polybutadiene polymer, and tires having a component made using the modified high-cis polybutadiene polymer. The processes make use of a functionalizing compound of formula (I) to prepare the modified high-cis polybutadiene from a quantity of 1,3-butadiene monomer using a specified catalyst system.