This invention discloses a method for preparing rubber compositions that
exhibit unique combinations of properties that are desirable for tire
tread applications for enhanced snow/ice and wet traction, low rolling
resistance and increased treadwear performance in comparison with
conventional silica compounds. Specifically, a high reactively silane
coupling agent, such as a mercaptosilane, is used in combination with a
silane coupling typically used for silica tread compounds such as
bis(triethoxylsilylpropyl)disulfide to treat silica pellets in a
hydrocarbon solvent at elevated temperatures. The treated silica is then
blended with solution elastomer cement in a hydrocarbon solvent. The
deposited reactive silanes partially react with the elastomer molecules
forming a layer of polymer grafted on the silica surfaced. This structure
significantly improves the silica retention during the steam stripping
operation. Almost 100% (99+%) silica retention has been achieved by this
invention. After solvent removal from steam stripping, the treated
silica/elastomer mixer is dewatered and dried using conventional
equipment such as shaker screens, expellers and expanders to form a
well-dispersed silica masterbatch. This technique results in silica
compounds with excellent silica dispersion and increased filler-polymer
interaction, hence enhanced compound performance such as better physical
properties, more desirable dynamic properties (low hysteresis at high
temperatures and high hysteresis at low temperatures) and increased
abrasion resistance.