Getting to the core: Pre-treatment of silica by Molecular Layer Deposition

Description

Silica-silane filler systems are essential in the rubber industry, in particular in tire manufacturing. Their use has many advantages such as reduction of rolling resistance and improvement of wet grip when used in passenger car tire treads. However, this technology also has its shortcomings: The mixing process takes longer compared to a carbon black filled compound due to the additional silanization step, and ethanol is generated requiring additional safety measures. These drawbacks can be mitigated by the use of silica pre-treated with silane. However, here the drawback is the lacking silane coverage of the inner surface of the silica clusters. A promising technical solution to overcome this problem is a pre-treatment in the gaseous phase.
Molecular Layer Deposition (MLD) was successfully used to modify highly dispersible precipitated silica with a thioester moiety in a fluidized-bed reactor. This modification was accomplished in a two-step reaction: In the first step, 3-mercaptopropyl-triethoxysilane (MPTES) was deposited, followed in the second step by deposition of octanoyl choride (OC) and its reaction with the mercapto group of MPTES.
This filler was tested in a sSBR and in a NR compound. As expected, mixing time could be reduced considerably in both cases, as the silanzation step was redundant. In the sSBR compound, noticeable improvements in cure behaviour and mechanical properties were observed compared to the rubber with in-situ modified silica. In a NR compound, the pre-treated filler resulted in better dispersion, longer scorch time and higher reinforcing effect.

Period	2 Jul 2024
Event title	German Rubber Conference, DKT 2024
Event type	Conference
Location	Nuremberg, GermanyShow on map
Degree of Recognition	International