Abstract: [Problem] To provide a conjugated diene polymer cyclized product free from coloring, a conjugated diene polymer cyclized product that has a narrow molecular weight distribution and is free from coloring, and a method for producing these conjugated diene polymer cyclized products. [Means for Resolution] A conjugated diene polymer cyclized product having a Gardner color scale of not more than 3.0. A conjugated diene polymer cyclized product having a Gardner color scale of not more than 3.0 and a ratio of weight average molecular weight/number average molecular weight of not more than 1.5. A method for producing a conjugated diene polymer cyclized product includes adding water to a conjugated diene polymer solution obtained by polymerizing a conjugated diene in a solvent by using an organoalkali metal compound as an initiator, thereby terminating the polymerization and then subjecting the subject conjugated diene polymer to a cyclization reaction.

Abstract: [Problem] To provide a conjugated diene polymer cyclized product free from coloring, a conjugated diene polymer cyclized product that has a narrow molecular weight distribution and is free from coloring, and a method for producing these conjugated diene polymer cyclized products. [Means for Resolution] A conjugated diene polymer cyclized product having a Gardner color scale of not more than 3.0. A conjugated diene polymer cyclized product having a Gardner color scale of not more than 3.0 and a ratio of weight average molecular weight/number average molecular weight of not more than 1.5. A method for producing a conjugated diene polymer cyclized product includes adding water to a conjugated diene polymer solution obtained by polymerizing a conjugated diene in a solvent by using an organoalkali metal compound as an initiator, thereby terminating the polymerization and then subjecting the subject conjugated diene polymer to a cyclization reaction.

Abstract: A main object of the invention is to provide a polar-group-containing cyclized rubber making it possible to improve remarkable the adhesiveness between paint and a molded product made of a nonpolar polymer such as polypropylene or polyethylene, and a process for producing the same. In order to attain the object, the invention provides a polar-group-containing cyclized rubber which has a polar group at a terminal of a polymer chain thereof, has a weight-average molecular weight of 1000 to 1,000,000, and is obtained by cyclizing a conjugated diene polymer having the polar group at a terminal of a polymer chain thereof.

Abstract: A syndiotactic styrenic polymer having a narrow molecular weight distribution which is a (co)polymer comprising at least one structural unit represented by the following Formula (1): wherein C1 of a phenyl group thereof has a tacticity of 30% or more in terms of a racemic pentad determined by 13C-NMR, and Ra and m are as defined in the specification. The disclosure is also directed to a block copolymer comprising the above polymer as one segment, to a block graft polymer prepared by modifying one block of the above polymer with a nitrogen-containing aromatic polymer, and to a process for preparing a syndiotactic styrenic polymer in which a styrenic monomer is polymerized in the presence of a catalyst comprising a reaction product of a transition metal compound and at least one co-catalyst selected from organic aluminunoxy compounds.

Abstract: A main object of the invention is to provide a polar-group-containing cyclized rubber making it possible to improve remarkably the adhesiveness between paint and a molded product made of a nonpolar polymer such as polypropylene or polyethylene, and a process for producing the same. In order to attain the object, the invention provides a polar-group-containing cyclized rubber which has a polar group at a terminal of a polymer chain thereof, has a weight-average molecular weight of 1,000 to 1,000,000, and is obtained by cyclizing a conjugated diene polymer having the polar group at a terminal of a polymer chain thereof.

Abstract: A process for preparing olefinic living polymers having a molecular weight distribution (Mw/Mn) of 1 to 1.3, comprising polymerizing an olefinic monomer having 2 to 20 carbon atoms at low temperatures in the presence of a catalyst comprising (A) a hafnium or zirconium-containing compound having one or two cyclopentadienyl backbones, (B) a triphenyl boron compound or a tetraphenyl borate compound and optionally (C) a specific mono-, di- or trialkylaluminum compound. When the catalyst comprising the zirconium-containing compound is prepared by further using a titanium-containing compound (D), the polymerization temperature can be raised.

Abstract: A butadiene polymer (i) having a cis bond unit content of at least 50% based on the total butadiene units, a number average molecular weight (Mn) of 1,000 to 10,000,000, and at least 80%, based on the total molecular chains, of living chains containing a transition metal of group IV of the Periodic table at a terminal thereof; a polymer (ii) obtained by modifying terminals of the polymer (i); and a polymer (iii) obtained by coupling the polymers (i). These polymers (i), (ii) and (iii) are obtained by polymerizing a conjugated diene monomer alone or with a copolymerizable monomer at a specific temperature in the presence of a catalyst comprising a compound (A) of a transition metal of group IV of the periodic table having a cyclopentadienyl structure and a co-catalyst (B) selected from organoaluminum-oxy compound (a) and others and optionally further by contacting the resultant polymer with a terminal modifier or a coupling agent.

Abstract: A process for modifying a polymer of a conjugated diene, which comprises reacting a polymer of a conjugated diene containing at least one metal selected from alkali metals and alkaline earth metals with a compound having a linkage of the following formula ##STR1## wherein X represents an oxygen or sulfur atom, in the molecule.

Abstract: A process for making a diene polymer rubber which comprises reacting an active diene polymer rubber having alkali metal and/or alkaline earth metal terminals, which is obtained by polymerizing a conjugated diene monomer alone or together with an aromatic vinyl monomer in a hydrocarbon solvent, using an alkali metal and/or alkaline earth metal initiator, with(1) a tin compound expressed by the general formula R.sub.a S.sub.n X.sub.b (in which R stands for an alkyl, alkenyl, cycloalkenyl or aromatic hydrocarbon group; X is a halogen atom; a is an integer of 0-2, and b is an integer of 2-4), and(2) at least one organic compound selected from the group consisting of aminoaldehydes, aminoketones, aminothioaldehydes, aminothioketones and the organic compounds having in their molecules ##STR1## (in which A stands for an oxygen or sulfur atom).

Abstract: A process for making a diene copolymer rubber having improved rebound, which comprises polymerizing a conjugated diene monomer with an aromatic vinyl monomer in a hydrocarbon solvent in the presence of an alkali metal and/or alkaline earth metal initiator, to form a dienyl-metal terminated, conjugated diene-aromatic vinyl copolymer rubber, and thereafter reacting the copolymer rubber with at least one reactant selected from the group consisting of aminoaldehydes, aminoketones, aminothioaldehydes and aminothioketones.