A modifying conjugated diene-based polymer, a method for preparing the same and a method for preparing the same are disclosed, herein. The modified conjugated diene-based polymer has excellent affinity with a filler and may improve the compounding properties of the conjugated diene-based polymer. In some embodiments, a modified conjugated diene-based polymer including a repeating unit derived from a conjugated diene-based monomer and a functional group derived from a modifier represented by Formula 1 in at least one terminal thereof.

A method for producing a polydiene, the method comprising of combining a lanthanide compound, an alkylating agent, a halogen source, and optionally conjugated diene monomer to form an active preformed catalyst; independent of step (i), introducing an amine with conjugated diene monomer to be polymerized; independent of step (i), introducing the active preformed catalyst to the conjugated diene monomer to be polymerized to form an active polymerization mixture, where the active polymerization mixture includes less than 10% by weight, based on the total weight of the active polymerization mixture, of a solvent; and allowing the monomer to be polymerized to polymerize in the presence of the amine.

A method for producing a polydiene, the method comprising of combining a lanthanide compound, an alkylating agent, a halogen source, and optionally conjugated diene monomer to form an active preformed catalyst; independent of step (i), introducing an amine with conjugated diene monomer to be polymerized; independent of step (i), introducing the active preformed catalyst to the conjugated diene monomer to be polymerized to form an active polymerization mixture, where the active polymerization mixture includes less than 10% by weight, based on the total weight of the active polymerization mixture, of a solvent; and allowing the monomer to be polymerized to polymerize in the presence of the amine.

A modified conjugated diene-based polymer, and more particularly, a modified conjugated diene-based polymer having a unimodal molecular weight distribution curve measured by gel permeation chromatography (GPC), molecular weight distribution (PDI; MWD) of less than 1.7, and a Si content of 100 ppm or more based on weight, and including a repeating unit derived from an aromatic vinyl monomer in an amount of greater than 0 wt % and less than 15 wt %, and a rubber composition including the same.

The present invention relates to a modified polymerization initiator for a conjugated diene-based polymer, and a modified conjugated diene-based polymer including a functional group derived from the modified polymerization initiator.

An object of the present invention is to provide a rubber composition capable of producing a pneumatic tire with both excellent low rolling resistance and wet grip performance, and a pneumatic tire comprising the rubber composition. The rubber composition comprises: a diene-based rubber containing 10 mass % or greater of a modified diene polymer; and an aromatic modified terpene resin; wherein the modified diene polymer is a modified polymer obtained by modifying an unmodified diene polymer (A) with a nitrone compound (B) having a carboxy group; and a content of the aromatic modified terpene resin is from 0.1 to 50 parts by mass per 100 parts by mass of the diene-based rubber.

An object of the present invention is to provide a rubber composition capable of producing a pneumatic tire with both excellent low rolling resistance and wet grip performance, and a pneumatic tire comprising the rubber composition. The rubber composition comprises: a diene-based rubber containing 10 mass % or greater of a modified diene polymer; and an aromatic modified terpene resin; wherein the modified diene polymer is a modified polymer obtained by modifying an unmodified diene polymer (A) with a nitrone compound (B) having a carboxy group; and a content of the aromatic modified terpene resin is from 0.1 to 50 parts by mass per 100 parts by mass of the diene-based rubber.

This disclosure is to provide a method for preparing a terminal-modified conjugated diene polymer which achieves an extremely high compounding amount of cis-1,4 without complicated preparing conditions, a terminal-modified conjugated diene polymer obtained via the method, a rubber composition containing the terminal-modified conjugated diene polymer, and a tire using the rubber composition. This disclosure is A method for preparing a terminal-modified conjugated diene polymer comprising: polymerizing a conjugated diene compound by using a polymerization catalyst composition and modifying a polymer obtained via the polymerization by using a modifier, wherein the polymerization catalyst composition contains a rare earth element compound, and a coordination compound having a cyclopentadiene skeleton selected from substituted or unsubstituted cyclopentadienes, substituted or unsubstituted indenes, and substituted or unsubstituted fluorenes, and wherein the polymerization and modification is performed in a one-pot way.

A method for preparing a coupled polymer, the method comprising the steps of polymerizing monomer to form a reactive polymer and reacting the reactive polymer with a carboxylic or thiocarboxylic ester containing a nitro group, where the carboxylic or thiocarboxylic ester containing a nitro group includes a single nitro group.

A method for preparing a coupled polymer, the method comprising the steps of polymerizing monomer to form a reactive polymer and reacting the reactive polymer with a carboxylic or thiocarboxylic ester containing a nitro group, where the carboxylic or thiocarboxylic ester containing a nitro group includes a single nitro group.