Provided are a method for preparing a conjugated diene-based polymer and a method for preparing a graft copolymer including the same. The method for preparing a conjugated diene-based polymer includes enlarging a first conjugated diene-based polymer in multiple stages to prepare a second conjugated diene-based polymer, wherein the multi-stage enlargement includes a primary enlargement stage and a secondary enlargement stage, and a weight ratio of acids added in the primary enlargement stage and the secondary enlargement stage is 70:30 to 90:10. A graft copolymer prepared by the above-described method can be used to form a thermoplastic resin molded article excellent in all of plating characteristics, mechanical properties, surface characteristics, colorability, and processability.

The present invention provides a catalyst composition including a functionalizing agent of the following Formula 1 together with a rare earth metal compound, an alkylating agent, and a halogen compound, having good catalytic activity and polymerization reactivity and useful for the preparation of a conjugated diene-based polymer having high linearity and excellent processability, and a conjugated diene-based polymer prepared using the catalyst composition.

(X.sub.1).sub.aN(X.sub.2).sub.3-a[Formula 1]

In Formula 1, a, X.sub.1, and X.sub.2 are the same as defined in the disclosure.

The present invention provides a catalyst composition including a functionalizing agent of the following Formula 1 together with a rare earth metal compound, an alkylating agent, and a halogen compound, having good catalytic activity and polymerization reactivity and useful for the preparation of a conjugated diene-based polymer having high linearity and excellent processability, and a conjugated diene-based polymer prepared using the catalyst composition.

(X.sub.1).sub.aN(X.sub.2).sub.3-a[Formula 1]

In Formula 1, a, X.sub.1, and X.sub.2 are the same as defined in the disclosure.

A method of preparing a conjugated diene-based polymer by continuous polymerization using two or more reactors is provided. The method of preparing a conjugated diene-based polymer includes a conjugated diene-based polymer having excellent cis 1,4 bond content and linearity, by adjusting the ratio of a polymer and a monomer in each reactor and by adjusting the retention time in a second reactor and resolving the deterioration phenomenon of physical properties, while improving productivity by reducing the contamination of the reactors.

Process for the preparation of (co) polymers of conjugated dienes comprising polymerizing at least one conjugated diene in the presence of a catalytic system comprising at least one vanadium bis-imine complex having the general formula (I): wherein: m is 0 or 1; Z represents a CR.sub.5R.sub.6 group wherein R.sub.5 and R.sub.6, equal to or different from each other, represent a hydrogen atom; or a C.sub.1-C.sub.20 alkyl group, preferably C.sub.1-C.sub.15, linear or branched; or a bivalent aromatic group optionally substituted; R.sub.1 and R.sub.2 equal to or different from each other, represent a hydrogen atom; or they are selected from C.sub.1-C.sub.20 alkyl groups, preferably C.sub.1-C.sub.15, linear or branched, optionally halogenated, cycloalkyl groups optionally substituted; or R.sub.1 and R.sub.2, may be optionally bound each other so as to form, together with the other atoms which they are bound to, a cycle containing from 4 to 6 carbon atoms, saturated, unsaturated, or aromatic, optionally substituted by C.sub.1-C.sub.20 alkyl groups, preferably C.sub.1-C.sub.15, linear or branched, said cycle optionally containing heteroatoms such as, for example, oxygen, sulfur, nitrogen, silicon, phosphorus, selenium; R.sub.3 and R.sub.4, equal to or different from each other, represent a hydrogen atom; or they are selected from C.sub.1-C.sub.20 alkyl groups, preferably C.sub.1-C.sub.15, linear or branched, optionally halogenated, cycloalkyl groups optionally substituted, aryl groups optionally substituted; or R.sub.2 and R.sub.4, may be optionally bound each other so as to form, together with the other atoms which they are bound to, a cycle containing from 3 to 6 carbon atoms, saturated, unsaturated, or aromatic, optionally substituted by C.sub.1-C.sub.20 alkyl groups, preferably C.sub.1-C.sub.15, linear or branched, said cycle optionally containing other heteroatoms such as, for example, oxygen, sulfur, nitrogen, silicon, phosphorus, selenium; or R.sub.1 and R.sub.3, may be optionally bound each other so as to form, together with other atoms which they are bound to, a cycle containing from 3 to 6 carbon atoms, saturated, unsaturated, or aromatic, optionally substituted by C.sub.1-C.sub.20 alkyl groups, preferably C.sub.1-C.sub.1, linear or branched, said cycle optionally containing other heteroatoms such as oxygen, sulfur, nitrogen, silicon, phosphorus, selenium; X.sub.1, X.sub.2 and X.sub.3, equal to or different from each other, represent a halogen atom such as, for example, chlorine, bromine, iodine, preferably chlorine; or they are selected from C.sub.1-C.sub.20 alkyl groups, preferably C.sub.1-C.sub.15, linear or branched, OCOR.sub.7 groups or OR.sub.7 gro

The present invention provides a catalyst composition including a functionalizing agent of the following Formula 1 together with a rare earth metal compound, an alkylating agent, and a halogen compound, having good catalytic activity and polymerization reactivity and useful for the preparation of a conjugated diene-based polymer having high linearity and excellent processability, and a conjugated diene-based polymer prepared using the catalyst composition.
(X.sub.1).sub.aN(X.sub.2).sub.3-a[Formula 1] In Formula 1, a, X.sub.1, and X.sub.2 are the same as defined in the disclosure.

The present invention provides a catalyst composition including a functionalizing agent of the following Formula 1 together with a rare earth metal compound, an alkylating agent, and a halogen compound, having good catalytic activity and polymerization reactivity and useful for the preparation of a conjugated diene-based polymer having high linearity and excellent processability, and a conjugated diene-based polymer prepared using the catalyst composition.
(X.sub.1).sub.aN(X.sub.2).sub.3-a[Formula 1] In Formula 1, a, X.sub.1, and X.sub.2 are the same as defined in the disclosure.

A method for preparing a functionalized polymer, the method comprising the steps of preparing a reactive polymer and reacting the reactive polymer with a heterocyclic nitrile compound.

A method for preparing a functionalized polymer, the method comprising the steps of preparing a reactive polymer and reacting the reactive polymer with a heterocyclic nitrile compound.

The present invention provides a catalyst composition including a functionalizing agent of the following Formula 1 together with a rare earth metal compound, an alkylating agent, and a halogen compound, having good catalytic activity and polymerization reactivity and useful for the preparation of a conjugated diene-based polymer having high linearity and excellent processability, and a conjugated diene-based polymer prepared using the catalyst composition.
(X.sub.1).sub.a-M.sub.1-([Y-M.sub.2-(X.sub.2).sub.n-1]).sub.m-a[Formula 1] In Formula 1, a, m, n, M.sub.1, M.sub.2, X.sub.1, X.sub.2 and Y are the same as defined in the disclosure.