Nippon Zeon Company, Ltd.

The Yokohama Rubber Co., Ltd.

Tokai Rubber Industries, Ltd.

Fumitoshi Suzuki

Shuichi Akita

Yoshihiro Chino

Masao Nakamura

Yasushi Kikuchi

Hideyuki Oishi

Hiroyuki Watanabe

Akio Ueda

Akihiro Shibahara

Masayoshi Daio

Kazuyoshi Kayama

Manabu Tomisawa

Tetsuo Oyama

Kiyoshi Tanaka

Rubber composition of two diene rubbers

Rubber composition

An abrasion-resistant rubber composition comprises as rubber components (A) 30-95 wt. % of an end-modified butadiene polymer and (B) 70-5 wt. % of a diene rubber other than the end-modified butadiene polymer (A). The end-modified butadiene polymer (A) is obtained by reacting at least one compound to active terminals of a starting butadiene polymer having a trans 1,4 bond content of 70-95 wt. %. The at least one compound is selected from N-substituted aminoketones, N-substituted thioaminoketones, N-substituted amino-aldehydes, N-substituted thioaminoaldehydes and compounds containing in the molecules thereof an atomic group represented by the following formula: ##STR1## in which M stands for an oxygen or sulfur atom.

Abrasion-resistant rubber compositions

There are provided a process for producing a diene polymer having markedly improved tensil strength and wear resistance and further having improved heat build-up, refound resilience, processability and wet skid resistance, as well as a rubber composition containing said diene polymer and having improved tensil strength, wear resistance, etc. Said diene polymer is produced by polymerizing a conjugated diene monomer or a mixture of the conjugated diene monomer and an aromatic vinyl monomer in a hydrocarbon solvent using a composite initiator containing an alkaline earth metal, and reacting active ends of the obtained active diene polymer with (a) a compound represented by the formula M.dbd.C.dbd.M (wherein M denotes an oxygen atom or a sulfur atom) or (b) N-substituted aminoketone, N-substituted thioaminoketone, N-substituted aminoaldehyde, N-substituted thioaminoaldehyde or a compound having an atomic group in a molecule represented by the formula --C(.dbd.M)--N&lt; in a molecule.

Process for producing diene polymer with alkaline earth metal

A rubber composition comprises as rubber components (A) 30-95 wt. % of an end-modified styrene-butadiene copolymer and (B) 70-5 wt. % of a diene rubber other than the end-modified styrene-butadiene copolymer (A). The end-modified styrene-butadiene copolymer (A) is obtained by reacting at least one compound to active terminals of a starting styrene-butadiene copolymer containing butadiene moieties, the trans-1,4 bond content of which is 70-95 wt. %, and having a styrene content of 5-60 wt. %. The at least one compound is selected from N-substituted aminoketones, N-substituted thioaminoketones, N-substituted aminoaldehydes, N-substituted thioaminoaldehydes and compounds containing in the molecules thereof an atomic group represented by the following formula: ##STR1## in which M stands for an oxygen or sulfur atom. The diene rubber (B) has a glass transition temperature higher than -60.degree. C.

Rubber compositions

A rubber composition comprising, as rubber components, 10-40 % by weight of (1) a styrene-butadiene copolymer rubber obtained by solution polymerization, having a styrene content of less than 20% by weight and a trans-1,4 bond content in butadiene portion, of more than 90% by weight and 60-90% by weight of (2) a diene rubber other than the styrene-butadiene copolymer rubber (1), having a glass transition temperature of -60.degree. C. or below.

A rubber composition for tire treads which comprises 100 parts by weight of a rubber component comprising 10 to 100 parts by weight of a styrene-butadiene copolymer rubber produced by a solution polymerization and 90 to 0 parts by weight of at least one of other diene rubbers having a glass transition temperature (Tg) of -60.degree. C. at lowest, and at least 70 parts by weight of a carbon black mixed in the rubber component, the styrene-butadiene copolymer rubber having a styrene content of 45 to 65% by weight, a content of butadiene derived vinyl groups of 20 to 70 parts by weight and a content of a styrene sequence consisting of not less than 8 bonded styrene monomer units of at largest 10% by weight of the above styrene content.

Rubber composition for tire tread

A rubber composition which gives a rubber vibration insulator having excellent low-temperature properties comprises as a main rubber component a blend composed of (a) 10 to 90 parts by weight of a tapered styrene/butadiene copolymer rubber which has an average bound styrene content of 10 to 40% by weight and a 1,2-bond content in the butadiene portion of at least 50% by weight and in which the bound styrene content increases or decreases in one direction along the copolymer molecular chain and (b) 90 to 10 parts by weight of natural rubber and/or synthetic polyisoprene rubber.

A rubber composition for tire tread, comprising a rubber mixture composed of two kinds of styrene-butadiene copolymer rubber different from each other in the styrene content and the vinyl bond content in butadiene, polybutadiene rubber, natural rubber and/or synthetic polyisoprene rubber.

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Yokohama, Japan

Fumitoshi Suzuki