Effect of Lewis Acid/Base Adducts as a Silanization Catalyst in Rubber Compositions Containing Silica

摘要

Silica-filled rubber compositions with good physical properties after curing, like those containing mercaptosilane, often have the problems about processability. So, it is one of the most important tasks to balance the curing properties and processability of the compositions to a high level. Controlling the silanization process is considered as one of key factors to solve the problems. Therefore this study has focused on the effective silanization by using Lewis acid/base adduct containing boron atom as the silanization catalyst. Blending the catalyst, triphenylphosphine-triphenylborane complex (PB-complex) or pyridine-triphenylborane complex (NB-complex), into the rubber compositions has been found to improve the tanδ balance at high and low temperature without aggravation of the processability. This result indicates that the effective silanization by using catalysts is important to balance the properties before and after curing; and the PB- and NB- complex can act as an effective silanization catalyst even in the mixing process. The acceleration of silanization by using the catalysts has been confirmed by the results of model reactions between silica and silane coupling agent in the presence or absence of the PB-complex in organic solvent.