PREPARATION OF APEX/BEAD COMPOSITE AND TIRE WITH PRE-APEXED BEAD

摘要

A method of preparing an apex/bead assembly is disclosed. The method comprises mixing a sulfur curable uncured rubber composition with a maximum mixing temperature in a range of from 140 to 180°C; and extruding the sulfur curable uncured rubber composition through a die to form and apply an uncured apex rubber strip (8) onto and circumferentially around the outer periphery of an annular bead (3) comprising an uncured rubber encapsulated plurality of wire cords; wherein the rubber composition of the uncured apex rubber strip (8) comprises:
(A) at least one diene-based elastomer comprising at least one of cis 1,4-polyisoprene, polybutadiene and styrene/butadiene rubber;
(B) from 1 to 10 parts by weight syndiotactic-1,2-polybutadiene per 100 part by weight of the elastomer(s), wherein the syndiotactic-1,2-polybutadiene has a melting point (MP) in a range of from 70°C to 130°C and at least 10°C below the maximum mixing temperature for the preparation of the sulfur curable uncured rubber composition; and
(C) from 30 to 120 phr of a reinforcing filler comprising:
(1) a carbon black, or
(2) a combination of a carbon black and silica together with a coupling agent for the silica having a moiety reactive with hydroxyl groups on the silica and another different moiety interactive with said diene-based elastomer(s).
Also, a respective pre-apexed annular tire bead is disclosed and a pneumatic tire comprising such a pre-apexed annular tire bead.