Rubber composition improved in charging property and pneumatic tire produced by making use of the same

A rubber composition having an improved charging property comprising 100 parts by weight of rubber component comprising a copolymer of an aromatic vinyl hydrocarbon and a diene monomer, wherein the amount to the aromatic vinyl hydrocarbon is about 30 to 70 parts by weight;

• the diene vinyl content is less than 20%;
• Mn value is 250,000 or more;
• and polydispersity index Mw/Mn is less than 2.5, a white filler, a coupling agent, which comprises silane, of 1 to 15 weight % based on the weight of the white filler, and a nonionic surfactant represented by the following formula (VII):
• R.sup.8 --R.sup.9 (VII)
• wherein R.sup.8 represents a hydrophilic group, and R.sup.9 represents a substituted or non-substituted aryl group.

A rubber composition having an improved charging property, comprsing:

• (a) 50 to 100 parts by weight of a solution polymerized diene polymer or copolymer having a carbon-metal bond in the main chain,
• (b) 0 to 50 parts by weight of an elastic polymer selected from the group consisting of 1,4-polyisoprene (1,4-IR), 3,4-polyisoprene (3,4-IR), polybutadiene (BR), natural rubber (NR), epoxidized natural rubber (ENR), styrene-butadiene rubber (SBR), and the mixtures thereof,
• (c) a filler comprising a white filler or the mixture of carbon black and the white filler,
• (d) a coupling agent, which comprises silane, of 0.5 to 10 weight % based on the weight of the white filler, and
• (e) a nonionic surfactant represented by the following formula (VII):
• R.sup.8 --R.sup.9 (VII)
• wherein R.sup.8 represents a hydrophilic group, and R.sup.9 represents a substituted or non-substituted aryl group.