Bridgestone Corporation

Shigenaga Takano

Shojiro Kaita

Masaki Yoshida

Olivier Tardif

Yasuo Horikawa

Shinji Yamakawa

Kohtaro Osakada

Aya Yanagisawa

Yusuke Yamagata

Satoru Tamaki

Daisuke Takeuchi

Shigeki Oishi

Kyohei Kotani

Aya Hotta

The present disclosure provides a polyisoprene wherein: a vinyl bond content of the polyisoprene is 30 mol % or higher; and a ratio of the weight-average absolute molecular weight (Mw') determined by GPC-MALS with respect to the weight-average molecular weight (Mw) in terms of polystyrene determined by GPC, i.e., Mw′/Mw, is 0.850 or less. A rubber composition containing the polyisoprene is excellent in the fuel-saving performance and grip performance on a wet road surface, as compared with a rubber composition containing the conventional polyisoprene.

Polyisoprene, rubber composition, and tire

An object of the present disclosure is to provide a method for manufacturing a copolymer, wherein a crystal content and a vinyl bond content (or a glass transition temperature) of the copolymer can be controlled. Specifically, the present disclosure provides a method for manufacturing a copolymer, wherein the method comprises a process of copolymerizing ethylene with isoprene under the presence of a polymerization catalyst composition containing a half metallocene cation complex represented by following general formula (I) (In formula (I), M represents a lanthanoid element, scandium or yttrium; Cprepresents substituted cyclopentadienyl, substituted indenyl or substituted fluorenyl; X represents hydrogen atom, halogen atom, alkoxy, thiolate, amide, silyl, or a Cmonovalent hydrocarbon group; L represents a neutral Lewis base; w represents an integer in the range of 0 to 3; and [B]represents a non-coordinating anion), wherein Cpin general formula (I) has at least two substituent groups.

Method for manufacturing copolymer

Provided is novel polybutadiene having high isotacticity. The polybutadiene has a triad isotacticity (mm) of 72% or more.

Polybutadiene, method of producing polybutadiene, polybutadiene composition, tire, and resin member

To provide a method for producing a multicomponent copolymer with which a multicomponent copolymer having excellent rupture strength can be obtained, and a multicomponent copolymer, a rubber composition and a tire having excellent rupture strength. The method is a method for producing a multicomponent copolymer having a conjugated diene unit, a non-conjugated olefin unit and an aromatic vinyl unit, comprising adding a conjugated diene compound in divided portions into a reactor containing a catalyst and at least one selected from the group consisting of a non-conjugated olefin compound and an aromatic vinyl compound. The multicomponent copolymer is obtained with the production method. The rubber composition comprises the multicomponent copolymer as a rubber component. The tire uses the rubber composition.

Method for producing multicomponent copolymer, multicomponent copolymer, rubber composition, and tire

To provide a catalyst composition having high polymerization activity. To provide a polymer manufacturing method. To provide a polymer manufactured by the polymer manufacturing method. To provide a rubber composition including the polymer. To provide a tire using the rubber composition. A catalyst composition including a compound represented by Structural Formula I below, wherein the compound has an OH group at at least one position of the bipyridyl ring; M is a transition metal, a lanthanoid, scandium, or yttrium; Rand Rare a hydrocarbon group having one or more carbon atoms or a halogen atom; and Rand Rmay be the same or different from each other. A polymer manufacturing method including a step of polymerizing one or more selected from the group consisting of a conjugated diene compound and a compound having an ethylenically unsaturated double bond in the presence of the catalyst composition. A polymer manufactured by the manufacturing method. A rubber composition including the polymer. A tire using the rubber composition. 

Polymerization catalyst composition, polymer manufacturing method, polymer, rubber composition, and tire

It is an object of the disclosure to provide a production method for a copolymer in which a copolymer with a high content of cis-1,4 bonds of a conjugated diene portion can be obtained at a high yield even when a cyclic olefin compound is used as a monomer. In order to achieve the object, the present disclosure includes a step of polymerizing a conjugated diene compound and a cyclic olefin compound in the presence of a catalyst composition containing a rare-earth element compound represented by the following formula (I), at least one compound selected from the group consisting of an ionic compound and a halogen compound, a compound represented by the following formula (II), and a coordination compound that can be a ligand:M-(AQ)(AQ)(AQ)&#x2003;&#x2003;(I)YRRR&#x2003;&#x2003;(II).

Production method for copolymer, copolymer, rubber composition, and tire

An object of the present disclosure is to provide a copolymer containing at least an acyclic non-conjugated olefin unit and a conjugated diene unit and capable of improving an elastic modulus of a rubber composition. Specifically, the present disclosure provides a copolymer containing at least an acyclic non-conjugated olefin unit and a conjugated diene unit, wherein the difference (T&#x2212;T) between an extrapolated melting end temperature (T) as measured in accordance with JIS K7121 and an extrapolated melting initiation temperature (T) as measured in accordance with JIS K7121 is not higher than 60&#xb0; C.

Copolymer, production method for copolymer, rubber composition, and tire

To provide a method for producing a multicomponent copolymer with which a multicomponent copolymer having excellent rupture strength can be obtained, and a multicomponent copolymer, a rubber composition and a tire having excellent rupture strength. The method is a method for producing a multicomponent copolymer having a conjugated diene unit, a non-conjugated olefin unit and an aromatic vinyl unit, comprising adding continuously or intermittently continuously a conjugated diene compound into a reactor containing a catalyst and at least one selected from the group consisting of a non-conjugated olefin compound and an aromatic vinyl compound. The multicomponent copolymer is obtained with the production method. The rubber composition comprises the multicomponent copolymer as a rubber component. The tire uses the rubber composition.

An object of the present invention is to provide a multicomponent copolymer for use for producing a rubber composition and a rubber product having high abrasion resistance and wet performance. Further, the invention is to provide a rubber composition containing the multicomponent copolymer, a crosslinked rubber composition produced by crosslinking the rubber composition, and a tire and a rubber product using the rubber composition or the crosslinked rubber composition. The multicomponent copolymer of the invention contains a conjugated diene unit, a non-conjugated olefin unit and an aromatic vinyl unit, wherein the content of the aromatic vinyl unit is 5 mol % or more and less than 50 mol % of the whole multicomponent copolymer and the content of the non-conjugated olefin unit is more than 0 mol % and 50 mol % or less of the whole multicomponent copolymer.

Multi-component copolymer, rubber composition, crosslinked rubber composition, rubber product and tire

An object of the present disclosure is to provide a terminal-modified conjugated dime polymer capable of improving fracture resistance of a rubber article. Specifically, a terminal-modified conjugated diene polymer is characterized in that a content of catalyst residue therein derived from a catalyst used in polymerization is less than 60 ppm.

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Kodaira, Japan

Shigenaga Takano