Silane Crosslinking Technologies - Grafting and Shaping

Sioplas^® process

The Sioplas^® process was developed in 1968 by Midland Silicones. The essential step is peroxide-activated grafting of the vinylsilane onto the polymer chains. This step is usually carried out in compounding units such as co-kneaders or twin-screw extruders. The silane/peroxide mixture is added to the polymer melt by means of membrane or piston pumps, giving a grafted granular product. The grafted compound can be shaped on conventional extruders. The catalyst masterbatch, which increases crosslinking speed, needs to be added in this step.

Silane copolymers

Crosslinkable polymers can also be obtained by copolymerization of ethylene vinyltrimethoxysilane. Such grades are supplied directly by polymer producers. The final shaping step is carried out in a way comparable to the Sioplas process on standard extrusion equipment. The addition of a catalyst and further additives (e.g. stabilizers) in the shaping step is crucial.

Monosil^® process

The Monosil^® process developed by BICC and Maillefer in 1974 combines grafting, the addition of the catalyst and shaping into one step. This signifi cantly challenging process combination requires special extrusion equipment. Crucial aspects of the equipment are the screw design and the technology for feeding the additives.