Without significantly impacting monomer conversion, the cis-1,4 mer content of conjugated diene mer in polymers can be increased by adding one or more Lewis bases to a catalyst composition that includes a Group 3 metal atom-containing carboxylate. This effect can be seen even at above average monomer concentrations.

The polymerization catalyst composition includes: Component (A): a rare earth element compound of formula (i): M-(NQ.sup.1)(NQ.sup.2)(NQ.sup.3) (where M is at least one selected from lanthanoid, scandium, and yttrium, and NQ.sup.1, NQ.sup.2 and NQ.sup.3 are amide groups and each have a M-N bond; Component (B): a hydrocarbyl aluminoxane compound having a C1-20 hydrocarbon group; and Component (C): a compound of formula (X): YR.sup.1.sub.aR.sup.2.sub.bR.sup.3.sub.c (where Y is a metal selected from groups 1, 2, 12 and 13 in a periodic table, R.sup.1 and R.sup.2 are C1-10 hydrocarbon groups or hydrogen atoms and R.sup.3 is a C1-10 hydrocarbon group).

The present invention provides a dental polymerizable composition that requires less discharging force, is easily formable, has low polymerization shrinkage stress during curing, and exhibits high stain resistance and surface gloss when cured. The present invention relates to a dental polymerizable composition including a (meth)acrylic block copolymer (A), a polymerizable monomer (B), and a polymerization initiator (C). The (meth)acrylic block copolymer (A) consists of a (meth)acrylic polymer block (a) having a curable functional group and a (meth)acrylic polymer block (b) having no curable functional group. The curable functional group has a partial structure represented by the following general formula (1):

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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.

The present invention provides 1,4-cis polybutadiene having high linearity with an −S/R value of 1 or greater at 100° C., and accordingly, is capable of reducing resistance properties, particularly rolling resistance, and greatly enhancing fuel efficiency properties when used in a rubber composition.

The present invention provides a catalyst composition exhibiting, by including a lanthanide rare earth element-containing compound; modified methylaluminoxane; a halogen compound; and an aliphatic hydrocarbon-based solvent, excellent catalytic activity even with a small main catalyst amount, capable of preparing a conjugated diene-based polymer having excellent catalytic activity and thereby having high cis-1,4-bond content ratio, high linearity, and narrow molecular weight distribution, and capable of reducing polymerization reaction time, and a method for preparing the same.

A continuous method for producing a diene elastomer is provided. The method comprises a polymerization reaction of a catalytic system with at least one conjugated diene monomer to be polymerized in solution in a solvent. The catalytic system is based on at least a rare earth organic salt and an alkylating agent, in at least two full polymerization reactors in series. A portion of the conjugated diene monomer to be polymerized is introduced into a polymerization reactor subsequent to the first polymerization reactor.

A method for manufacturing a conjugated diene polymer that can increase the robustness of a polymerization reaction system is provided. Also, a conjugated diene polymer, with a high cis-1,4-bond content, that is manufactured by this method for manufacturing is provided. A method for manufacturing a conjugated diene polymer includes polymerizing a conjugated diene monomer using a polymerization catalyst composition including a rare earth element compound and a compound having a cyclopentadiene skeleton, and a conjugated diene polymer manufactured with this method for manufacturing has a cis-1,4-bond content of 95% or greater.

A method for manufacturing a conjugated diene polymer that can increase the robustness of a polymerization reaction system is provided. Also, a conjugated diene polymer, with a high cis-1,4-bond content, that is manufactured by this method for manufacturing is provided. A method for manufacturing a conjugated diene polymer includes polymerizing a conjugated diene monomer using a polymerization catalyst composition including a rare earth element compound and a compound having a cyclopentadiene skeleton, and a conjugated diene polymer manufactured with this method for manufacturing has a cis-1,4-bond content of 95% or greater.

A method for producing highly reactive olefin polymers wherein at least 50 mol % of the polymer chains have terminal double bonds, and a novel polymerization initiating system for accomplishing the same includes contacting isobutene or an isobutene-containing monomer mixture, wherein a Lewis acid catalyst is complexed with an oxygen and/or sulfur-containing Lewis base, in an apolar solvent, and wherein an initiator is employed to initiate polymerization of the isobutene or isobutene-containing monomer mixture.