Rubber composition and pneumatic tire using said rubber composition

Abstract

The present invention provides a rubber composition and a pneumatic tire using the rubber composition. The rubber composition which comprises: a rubber component comprising a styrene-butadiene copolymer rubber or a blend of the styrene-butadiene copolymer rubber and another conjugated diene base rubber with the styrene-butadiene copolymer rubber being 70% by weight or more of the entire blend, and the entire content of styrene is 30 to 40% by weight of the entire rubber component; silica in an amount of 10 to 60 parts by weight per 100 parts by weight of the rubber component; a specific silane coupling agent, i.e., a bis (alkoxysilylalkyl)polysulfide having a polysulfide chain in which the distribution of sulfur is specified, in an amount of 1 to 20% by weight of the amount of silica; and carbon black, the sum of the amount of silica and carbon black being 60 to 130 parts by weight per 100 parts by weight of the rubber component. The pneumatic tire has excellent wet skid resistance, excellent grip performance on a dry road surface, and excellent abrasion resistance.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a rubber composition and to a pneumatic tire using the rubber composition, and more particularly, to a rubber composition and to a pneumatic tire using the rubber composition in which wet skid resistance and grip performance on a dry road surface are excellent and abrasion resistance can be improved.[0003]2. Description of the Related Art[0004]Heretofore, silica has been used for the rubber composition of a tire so as to improve the performances thereof.[0005]For example, Japanese Patent Application Laid-Open (hereinafter, “JP-A”) No. Sho-63-270751 and JP-A No. Sho-64-9248 disclose a rubber composition compounded with a predetermined amount of silica in order to obtain a high performance tire.[0006]Further, JP-A No. Hei-3-252431, JP-A No. Hei-3-252433, and JP-A No. Hei-3-25431 disclose a pneumatic tire in which a rubber composition compounded with silica, silane coupling agent, and a spe...

AI Technical Summary

Benefits of technology

[0014]Accordingly, an object of the present invention is to provide a rubber composition and a pneumatic tire using the rubber composition in which gelation of a polymer due to a silane coupling agent during mixing at high temperatures of 150° C. or more is suppressed without a deterioration in workability, in which wet skid resistance and grip performance on a dry road surface are excellent, and in which abrasion resistance can be improved.

Problems solved by technology

When dispersion of silica particles into rubber is insufficient, a problem arises in that processability in processes such as extrusion and the like deteriorates due to the increase in the Mooney viscosity.

Therefore, there are problems in that basic substances used as vulcanization accelerators are absorbed such that vulcanization is not carried out sufficiently, and a sufficient modulus of elasticity is not obtained.

However, the use of a silane coupling agent as a reinforcing material is still insufficient for improving fracture properties, workability, and processability of a rubber composition to high standards.

However, this method of using a combination of silica and silane coupling agent as a reinforcing material has a drawback in that flow of the uncured compounded rubber is markedly inferior and workability and processability deteriorate, although reinforcement of the compounded rubber can be remarkably improved and fracture properties are improved.

The drawbacks of the conventional technologies in which silane coupling agents are used arise due to the following mechanism.

When the mixing temperature of rubber is low, the silanol group on the surface of the silica does not react sufficiently with the silane coupling agent, and as a result, the sufficient reinforcing effect is not obtained.

Thus, processing in later stages becomes impossible in actuality.

Therefore, when a silane coupling agent is used in combination with silica, a multistep mixing must be conducted at a temperature lower than 150° C., and marked decrease in productivity is inevitable.

When the mixing is conducted at a low temperature, dispersion of silica and carbon black into the rubber is insufficient and abrasion resistance deteriorates.