Japan Synthetic Rubber Co., Ltd.

Bridgestone Tire Company Limited

Masao Yoshizawa

Mitsuhiko Sakakibara

Iwakazu Hattori

Fumio Tsutsumi

Masaki Ogawa

Yasushi Hirata

Shigeru Tomihira

A process for producing a modified conjugated diene polymer which comprises the steps of (I) polymerizing a conjugated diene in an inert organic solvent in the presence of a catalyst comprising (a) a lanthanum series rare earth element compound, (b) an organoaluminum compound represented by the general formula, AlR.sup.1 R.sup.2 R.sup.3 (wherein R.sup.1, R.sup.2 and R.sup.3 which may be same or different, are hydrogen atoms or hydrocarbon groups of 1 to 8 carbon atoms and at least one of R.sup.1, R.sup.2 and R.sup.3 is said hydrocarbon group) and, if necessary, at least one member selected from the group consisting of (c) a Lewis acid and/or (d) a Lewis base, and then (II) modifying the resulting reactive polymer with a modifying compound of the general formula, R.sup.4.sub.n MX.sub.4-n (wherein R.sup.4 is an alkyl group of 1 to 20 carbon atoms or an aryl group, M is a tin atom, X is a halogen atom, and n is an integer of 1 to 3).

Preparation of conjugated diene polymers modified with an organo-tin or

A process for producing a modified conjugated diene polymer which comprises the steps of (I) polymerizing a conjugated diene in an inert organic solvent in the presence of a catalyst comprising (a) a lanthanum series rare earth element compound, (b) an organoaluminum compound represented by the general formula, Alr.sup.1 R.sup.2 R.sup.3 (wherein R.sup.1, R.sup.2 and R.sup.3 which may be same or different, are hydrogen atoms or hydrocarbon groups of 1 to 8 carbon atoms and at least one of R.sup.1, R.sup.2 and R.sup.3 is said hydrocarbon group) and, if necessary, at least one member selected from the group consisting of (c) a Lewis acid and/or (d) a Lewis base, and then (II) modifying the resulting reactive polymer with a modifying compound selected from the group consisting of the following components (e), (f) and (g): (e) an organometal halide compound represented by the general formula, R.sub.n .sup.4 MX.sub.4-n (wherein R.sup.4 is an alkyl group of 1 to 20 carbon atoms or an aryl group, M is a tin or germanium atom, X is a halogen atom, and n is an integer of 1 to 3), (f) a heterocumulene compound or a three-membered heterocyclic compound having, in the molecule, a bond represented by the general formula, ##STR1## (wherein X.sup.1 is a carbon, nitrogen, oxygen or sulfur atom, Y is a carbon or sulfur atom, Z is a nitrogen, oxygen or sulfur atom, and X.sup.2 is a nitrogen, oxygen or sulfur atom), and (g) a halogen compound having, in the molecule, a bond represented by the general formula, ##STR2## (wherein Y.sup.1 is a nitrogen or oxygen atom and X is a halogen atom). Said modified conjugated diene polymer has excellent characteristics in wear resistance, heat generation, mechanical properties, etc.

Modified conjugated diene polymer and process for production thereof

A rubber composition having improved wet skid resistance and rolling resistance is disclosed, which comprises (A) 10-90% by weight of polybutadiene rubber having a content of cis-1,4-bond at least 80% and an average chain length of cis-1,4-bond of not less than 110, and (B) 10-90% by weight of random styrene-butadiene copolymer rubber obtained by copolymerization in the presence of an organic metal catalyst and having a content of bound styrene of not more than 40% by weight and a content of 1,2-bond in total butadiene unit of 30-95%.

Rubber compositions

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Kameyama, Japan

Masao Yoshizawa