Bridgestone Corporation

Bridgestone Sports Co., Ltd.

Satoru Tamaki

Shojiro Kaita

Takashi Ohira

Tsuyoshi Nakajima

Hideo Takeichi

Yuichiro Ozawa

Yusuke Yamagata

Junko Matsushita

Teppei Mori

Olivier Tardif

Shigenaga Takano

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

Provided is a rubber composition including a rubber component. The rubber component contains at least a polymer that is a synthesized polyisoprene or an isoprene copolymer and that has 20% or less gel fraction.

Rubber composition and tire containing rubber composition

An isoprene polymerization catalyst composition includes: Component (a): a rare earth element compound having a rare earth element-oxygen bond or a rare earth element-sulfur bond; Component (b): an ionic compound; and Component (c): at least one compound selected from the group consisting of a compound of formula (X): YRRRand a compound having a repeating unit of formula (Y): (&#x2014;Y(R)O&#x2014;) (where Y is a metal selected from groups 1, 2, 12 and 13 in a periodic table, Rand Rare C1-10 hydrocarbon groups or hydrogen atoms and Ris a C1-10 hydrocarbon group).

Isoprene polymerization catalyst composition, method for producing synthetic polyisoprene, and synthetic polyisoprene

The polymerization catalyst composition includes: Component (A): a rare earth element compound of formula (i): M-(NQ)(NQ)(NQ) (where M is at least one selected from lanthanoid, scandium, and yttrium, and NQ, NQand NQare 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): YRRR(where Y is a metal selected from groups 1, 2, 12 and 13 in a periodic table, Rand Rare C1-10 hydrocarbon groups or hydrogen atoms and Ris a C1-10 hydrocarbon group).

Polymerization catalyst composition, method for producing synthetic polyisoprene, and synthetic polyisoprene

A copolymer having properties (durability (fracture resistance, abrasion resistance, and crack-growth resistance)) similar to those of natural rubber and a method of producing the copolymer are provided. An isoprene copolymer has a styrene block or a butadiene block at a terminal thereof, wherein styrene monomers account for less than 5 mol % of all monomers forming the isoprene copolymer having the styrene block; butadiene monomers account for 10 mol % or less of all monomers forming the isoprene copolymer having the butadiene block; and cis-1,4 bond content of a portion derived from isoprene accounts for at least 95% in total.

Isoprene copolymer and method of producing the same

An object of the present invention is to provide a polymer composition having properties resembling those of natural rubber, e.g. good durability (fracture resistance, wear resistance, and crack growth resistance), and a method for manufacturing the polymer composition. Specifically, the present invention provides a method for manufacturing a polymer composition including a mixture of polyisoprene and polystyrene/polybutadiene, comprising: polymerizing styrene monomer or butadiene monomer in the presence of a catalyst to synthesize polystyrene or polybutadiene; adding isoprene monomer to the polystyrene or polybutadiene thus synthesized, to synthesize polyisoprene and thus generate said mixture, wherein content of the styrene monomer or the butadiene monomer is set to be 10 mol % or less with respect to the total quantity of the styrene monomer/the butadiene monomer and the isoprene monomer.

Method for manufacturing polymer composition and the polymer composition

The polymer of the present invention is a synthesized polyisoprene or an isoprene copolymer. The polymer has a number average molecular weight (Mn) of 1.5 million or more when measured by using gel permeation chromatography (GPC).

Polymer and method for producing same, rubber composition containing polymer, and tire having rubber composition

Provided are: a polymer capable of providing a crosslinked rubber composition with improved durability (i.e., breaking resistance, abrasion resistance, and crack growth resistance) and a method for producing the same, a rubber composition containing the polymer, a crosslinked rubber composition obtained by crosslinking the rubber composition, and a tire having the crosslinked rubber composition. The polymer is either a synthesized polyisoprene or an isoprene copolymer, and contains a residual catalyst in an amount of 300 ppm or less.

Polymer, rubber composition containing polymer, crosslinked rubber composition obtained by crosslinking rubber composition, and tire having crosslinked rubber composition

The present invention provides a method for synthesizing a polybutadiene more efficiently and stably which is possible to obtain a rubber composition and a tire excellent in durability (fracture resistance, wear resistance and crack growth resistance). A method for producing a polybutadiene, where a butadiene monomer is polymerized with the existence of rare-earth element compounds represented by the following formula (i):M-(NQ)(NQ)(NQ)&#x2003;&#x2003;(i)(in the formula, M is at least one selected from lanthanides, scandium and yttrium; (NQ), (NQ)and (NQ)are amide groups which may be the same or different to each other, and have M-N bonds).

Method for producing polybutadiene, polybutadiene, rubber composition and tire

A polymerization catalyst composition that, without accompanying excessive gelation, allows efficient synthesis of high molecular weight polyisoprene under industrial conditions is provided. The polymerization catalyst composition contains:

A golf ball having a good rebound and excellent flight performance can be obtained using a golf ball composition which contains a diene polymer having an aluminum catalyst residue content of not more than 650 ppm.

Golf ball composition and golf ball

A golf ball having a good rebound and excellent flight performance can be obtained using a golf ball composition which includes a diene polymer containing not more than 1.5% of components having a molecular weight of 30,000 or less.

A golf ball having a good rebound and excellent flight performance can be obtained using a golf ball composition which includes a diene polymer having a molecular weight distribution (Mw/Mn) of less than 1.9.

A golf ball endowed with a good rebound and an excellent flight performance can be obtained using a golf ball composition of good workability which contains a diene polymer having a peak top molecular weight (Mp) on a molecular weight distribution curve measured using gel permeation chromatography (GPC) of at least 40&#xd7;10and not more than 100&#xd7;10.

A golf ball having a good rebound and excellent flight performance can be obtained using a golf ball composition which contains a diene polymer having a smallest molecular weight value of at least 3,000.

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Kodaira, Japan

Satoru Tamaki