Bridgestone Corporation

Jsr Corporation

Hajime Kondou

Noriko Endou

Youichi Ozawa

Toshihiro Tadaki

Tomohisa Konno

Hiroshi Akema

Yoshiyuki Udagawa

Takafumi Fueki

A process for producing a conjugated diene-based polymer which comprises, in the first modification, modifying a conjugated diene-based polymer having active chain ends, which is obtained by polymerizing a diene-based monomer singly or with other monomers and has a content of a cis-1,4 unit of 75% by mole or greater in the conjugated diene portion of the main chain, by reacting the active chain ends with a hydrocarbyloxysilane compound and reacting the modified polymer with a specific compound such as a hydrocarbyloxysilane compound, and a rubber composition containing the polymer modified in accordance with the above process and, preferably, 10 to 100 parts by weight of silica and/or carbon black per 100 parts by weight of the rubber component containing the modified polymer, are provided. The rubber composition containing silica and/or carbon black exhibits improved fracture properties, abrasion resistance, low heat buildup property and excellent workability. A process for producing a conjugated diene-based polymer exhibiting improved cold flow, a polymer produced in accordance with the process, and a rubber composition and a tire using the polymer are also provided.

Conjugated diene polymer, process for its production and rubber compositions containing the same

This invention provides a modified natural rubber latex formed by charging a polar group-containing mercapto compound into a natural rubber latex to add the polar group-containing mercapto compound to a natural rubber molecule in the natural rubber latex, a modified natural rubber formed by coagulating and drying the modified natural rubber latex, and the rubber composition using the modified natural rubber and being excellent in the low loss factor, wear resistance and fracture characteristics.

Modified natural rubber latex and method for producing the same, modified natural rubber and method for producing the same, rubber composition and tire

The natural rubber latex of the present invention in which phospholipid contained in the latex is decomposed, particularly the natural rubber latex in which it is decomposed by enzyme treatment with lipase and/or phospholipase at a temperature of 70&#xb0; C. or lower is excellent in a processability, and in the natural rubber thereof and the rubber composition using the same, the physical properties such as an anti-aging characteristic, a tensile strength and an abrasion resistance are sufficiently maintained. Accordingly, the natural rubber of the present invention can be used as an excellent member for a tire.

Natural rubber latex, natural rubber, rubber composition and tire using the same

The present invention provides natural rubber latex in which glucans being polysaccharides contained in the latex are decomposed by treating the natural rubber latex with an &#x3b1;- and/or &#x3b2;-glucan decomposing enzyme such as amylase and cellulose and in which non-rubber components are subjected to suited enzyme treatment, and it provides natural rubber which is maintained in physical properties such as revelation of strain induced crystallization, an accelerating effect, an antioxidant effect and a vulcanization-accelerating effect and which is improved particularly in an abrasion resistance and a low hysteresis loss property, a production process for the same and a rubber composition and a tire using such natural rubber.

Natural rubber latex, natural rubber, rubber composition, and tire using the same

This invention provides a method for producing a modified natural rubber masterbatch, which comprises the step of mixing a modified natural rubber latex, which is formed by adding a polar group-containing monomer to a natural rubber latex to graft-polymerize the polar group-containing monomer onto a natural rubber molecule in the natural rubber latex, with a slurry solution formed by previously dispersing a filler into water, and a modified natural rubber masterbatch produced by the method and capable of highly improving a low loss factor, a wear resistance and fracture characteristics of a rubber composition.

Modified natural rubber masterbatch and method for producing the same as well as rubber composition and tire

Natural rubber obtained by a deproteinizing treatment of a natural rubber latex and has a total nitrogen content adjusted in the range of 0.12 to 0.30% by weight and a rubber composition and a pneumatic tire using the natural rubber. The processability of natural rubber can be improved without adverse effects on the physical properties proper to natural rubber. The rubber composition exhibits an improved low hysteresis loss property and improved abrasion resistance and can be advantageously used for the tire case members and the tire tread of pneumatic tires.

Natural rubber, rubber composition and pneumatic tire

Provided is a process for producing a modified polymer, characterized by carrying out primary modification in which a hydrocarbyloxysilane compound is reacted with the active site of a polymer having an active site of an organic metal type in a molecule and then carrying out secondary modification in which the hydrocarbyloxysilane compound is further reacted therewith. This makes it possible to provide a modified polymer which enhances interactions with silica and carbon black when used for both of silica-blended and carbon black-blended rubber compositions and which elevates the fracture characteristic, the abrasion resistance and the low heat buildup property at the same time and can exhibit a good workability.

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Tokyo, Japan

Hajime Kondou