Compounding of sealing compounds
Twin screw extruders from Coperion are particularly suitable for the production of sealing compounds. Sealing compounds mainly describe chemically hardening single component systems in which the networking of the substrate is initiated by moisture in the air. This splits off reaction products. After fast formation of a surface skin, the networking continues inside the compound until complete hardening. Silicon sealing compounds (RTV) are distinguished from PUR sealing compounds for polymers.
Typical set-up of a plant for the production of sealing compounds
In the production of RTV compounds, the silicon polymer is fed gravimetrically into the first barrel of the twin screw extruder. This supports the feeding of the extremely light fumed silica which tends to fluidize into the second barrel. The other liquid components such as silicon oil, networker and catalyst are fed successively into the barrels downstream.
An atmospheric venting is provided after the first compounding zone and a vacuum degassing unit in the penultimate barrel to remove air. Discharge takes place through a melt pump with downstream heat exchanger into the cartridge filling station. The compounds can also be strained.