The present invention relates to a modified conjugated diene-based polymer having excellent wet skid resistance and abrasion resistance in a balanced way, and a rubber composition comprising the same, and the modified conjugated diene-based polymer is characterized in including: a repeating unit derived from a conjugated diene-based monomer; and a functional group derived from a modifier, wherein, if measured by differential scanning calorimetry (DSC) through controlling the microstructure of the polymer, a difference between a glass transition onset temperature (T.sub.g-on) and a glass transition offset temperature (T.sub.g-off), which arise glass transition, is 10° C. to 30° C., thereby having excellent wet skid resistance and running resistance in a balanced way and improved effects of abrasion resistance, simultaneously.

The present invention relates to a modified conjugated diene-based polymer having excellent wet skid resistance and abrasion resistance in a balanced way, and a rubber composition comprising the same, and the modified conjugated diene-based polymer is characterized in including: a repeating unit derived from a conjugated diene-based monomer; and a functional group derived from a modifier, wherein, if measured by differential scanning calorimetry (DSC) through controlling the microstructure of the polymer, a difference between a glass transition onset temperature (T.sub.g-on) and a glass transition offset temperature (T.sub.g-off), which arise glass transition, is 10° C. to 30° C., thereby having excellent wet skid resistance and running resistance in a balanced way and improved effects of abrasion resistance, simultaneously.

A method for producing a modified conjugated diene-based polymer includes polymerizing a monomer including a conjugated diene compound in the presence of an alkali metal compound or an alkali earth metal compound to obtain a polymer having an active terminal; (a modification) reacting the polymer having an active terminal with a compound [M] having a plurality of hydrocarbyloxysilyl groups to obtain a modified polymer; and a mixing the modified polymer with at least one compound [C] selected from a compound [N] having one hydrocarbyloxysilyl group and an alcohol having 6 to 20 carbon atoms.

A method for producing a modified conjugated diene-based polymer includes polymerizing a monomer including a conjugated diene compound in the presence of an alkali metal compound or an alkali earth metal compound to obtain a polymer having an active terminal; (a modification) reacting the polymer having an active terminal with a compound [M] having a plurality of hydrocarbyloxysilyl groups to obtain a modified polymer; and a mixing the modified polymer with at least one compound [C] selected from a compound [N] having one hydrocarbyloxysilyl group and an alcohol having 6 to 20 carbon atoms.

Disclosed herein are highly active dilithio initiators prepared from high molecular weight dienes (C≧6) and methods for the preparation of such compounds. These dilithio initiators result in greater control over polymer microstructure and provide useful polymers and oligomers with low vinyl incorporation.

A bimetallic catalytic system consists of the metallic components of formulae RLi and Ca(AR′.sub.y).sub.2(L).sub.x in which: R represents a substituted or unsubstituted C.sub.1-C.sub.10 aliphatic radical, a substituted or unsubstituted C.sub.6-C.sub.20 aromatic radical or a substituted or unsubstituted C.sub.1-C.sub.10 heteroaliphatic radical; A denotes N or C; y has the value 2 when A is N and the value 3 when A is C; each R′ represents a hydrogen atom, a substituted or unsubstituted C.sub.5-C.sub.10 aliphatic radical, a substituted or unsubstituted C.sub.6-C.sub.20 aromatic radical, a substituted or unsubstituted silyl radical, a C.sub.1-C.sub.10 aliphatic radical substituted by at least one substituted or unsubstituted silyl radical, a C.sub.6-C.sub.20 aromatic radical substituted by at least one substituted or unsubstituted silyl radical; L represents a ligand; and x is a number ranging from 0 to 4.

The disclosure relates to rubber latex formed from any of: branched block copolymers derived from alkenyl aromatic hydrocarbon—1,3-diene monomer system, and branched polyisoprene homopolymers derived from isoprene. The polymers in embodiments are obtained by polymerization in the presence of an anionic initiator; at a temperature from 0° C. to 100° C.; followed by coupling with a multifunctional coupling agent of formula (R.sup.1O).sub.3Si—Y—Si(OR.sup.2).sub.3, wherein R.sub.1 and R.sub.2 are independently C.sub.1-C.sub.6 alkyl groups; and Y is a C.sub.2-C.sub.8 alkylene group. The polymers are obtained as rubber cements having high solids content and low zero shear viscosities. The rubber cements are valuable for making latices for further applications.

The disclosure relates to rubber latex formed from any of: branched block copolymers derived from alkenyl aromatic hydrocarbon—1,3-diene monomer system, and branched polyisoprene homopolymers derived from isoprene. The polymers in embodiments are obtained by polymerization in the presence of an anionic initiator; at a temperature from 0° C. to 100° C.; followed by coupling with a multifunctional coupling agent of formula (R.sup.1O).sub.3Si—Y—Si(OR.sup.2).sub.3, wherein R.sub.1 and R.sub.2 are independently C.sub.1-C.sub.6 alkyl groups; and Y is a C.sub.2-C.sub.8 alkylene group. The polymers are obtained as rubber cements having high solids content and low zero shear viscosities. The rubber cements are valuable for making latices for further applications.

A catalytic system based at least on a preformation monomer selected from the group consisting of 1,3-dienes, ethylene, α-olefins and their mixtures, on a metallocene of formula {P(Cp)(Flu)LnG} and on an organometallic compound as cocatalyst is provided. In the formula, Ln denotes a metal atom which is a rare earth metal, G denotes a group comprising the borohydride BH.sub.4 unit or denotes a halogen atom X selected from the group consisting of chlorine, fluorine, bromine and iodine, Cp denotes a cyclopentadienyl group of formula C.sub.5H.sub.4, Flu denotes a fluorenyl group of formula C.sub.13H.sub.8, P being a group bridging the two Cp and Flu groups and comprising a silicon or carbon atom. Such a catalytic system exhibits an improved stability of the catalytic activity over time, in particular on storage.

A catalytic system based at least on a preformation monomer which is ethylene or a mixture of ethylene and of a conjugated diene, on a metallocene of formula {P(Cp.sup.1)(Cp.sup.2)Y} or Cp.sup.3Cp.sup.4Y and on an organometallic compound as cocatalyst, Y denoting a group comprising a metal atom which is a rare earth metal, the Cp.sup.1, Cp.sup.2, Cp.sup.3 and Cp.sup.4 groups, which are identical or different, being selected from the group consisting of fluorenyl groups, cyclopentadienyl groups and indenyl groups, the groups being substituted or unsubstituted, and P being a group bridging the two Cp.sup.1 and Cp.sup.2 groups and comprising a silicon or carbon atom, is provided. Such a catalytic system exhibits an improved stability of the catalytic activity over time, in particular on storage.