Asahi Kasei Kabushiki Kaisha

Hiromi Nakafutami

Ryo Suzuki

Shinichi Sekikawa

Koichi Hasebe

Takashi Sato

Akira Saito

Haruo Yamada

Miki Kyo

Jun Yonezawa

A modified conjugated diene-based polymer

Modified conjugated diene-based polymer, polymer composition, and rubber composition

A modified conjugated diene-based polymer according to the present invention has a weight average molecular weight of 20&#xd7;10or more and 300&#xd7;10or less, has a molecular weight distribution Mw/Mn of 1.6 or more and 4.0 or less, has a modification ratio of 30% by mass or more and 80% by mass or less with respect to a total amount of the conjugated diene-based polymer, and includes 5% by mass or more and 50% by mass or less of a component having a molecular weight of 1,000,000 or more and 5,000,000 or less in GPC (gel permeation chromatography), wherein a modification ratio of the component having a molecular weight of 1,000,000 or more and 5,000,000 or less is 90% by mass or more and 100% by mass or less.

The present invention provides a modified conjugated diene-based polymer having a weight-average molecular weight of 20&#xd7;10or more and 300&#xd7;10or less, in which the modified conjugated diene-based polymer having a molecular weight of 200&#xd7;10or more and 500&#xd7;10or less is comprised in an amount of 0.25% by mass or more and 30% by mass or less based on a total amount of the modified conjugated diene-based polymer, and a shrinking factor (g') is less than 0.64.

Modified conjugated diene-based polymer and production method therefor, rubber composition and tire

The present invention provides a diene rubber composition having excellent processability and being improved in both the balance between low rolling resistance and wet skid resistance, and strength properties. The composition according to the invention is a diene polymer rubber composition comprising (A) 100 parts by weight of a raw material rubber comprising (A-1) a diene rubbery polymer which is a conjugated diene rubbery polymer or a conjugated diene-styrene rubbery copolymer (1) containing a modified component in an amount exceeding 60 wt. %, which modified component is obtained by reacting an active end of the rubbery polymer with a polyfunctional compound having, in its molecule thereof, at least two epoxy groups, (2) having a molecular weight distribution Mw/Mn of 1.05 to 3.0, and (3) having a weight-average molecular weight of 100,000 to 2,000,000; and, based on 100 parts of the component (A), (B) 1 to 100 parts by weight of a rubber extension oil, (C) 25 to 100 parts by weight of reinforcing silica, and (D) 1.0 to 20 parts by weight in total of a vulcanizing agent and a vulcanizing accelerator.

Rubber compositions

A hydrogenated block copolymer which comprises at least two polymer blocks A each mainly comprising an aromatic vinyl hydrocarbon compound monomer unit and at least two hydrogenated polymer blocks B each mainly comprising a butadiene monomer unit, at least 90% of the olefinically unsaturated double bonds in said polymer block mainly comprising a butadiene monomer unit before hydrogenation having been hydrogenated, wherein at least one of the block at the terminal of the hydrogenated block copolymer is the polymer block B, wherein the proportion of the terminal polymer blocks B in the hydrogenated block copolymer is at least 0.1 wt % but less than 9.1 wt %, wherein the proportion of the aromatic vinyl hydrocarbon compound in the hydrogenated block copolymer exceeds 10 wt % but less than 25 wt %, wherein the 1,2-bond content of the polymer blocks mainly comprising a butadiene monomer unit before hydrogenation is, on average, at least 62 mole % but less than 99 mol %, and wherein the difference &Dgr;Tc (Tc1&minus;Tc2) between the crystallization initiating temperature (Tc1) of the isotactic homopolypropylene and the crystallization initiating temperature (Tc2) of a mixture thereof with the hydrogenated block copolymer is at least 1.5&deg; C.

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Tokyo, Japan

Hiromi Nakafutami