Processing & partitioning aid

Imerys talc makes effective processing aids for improving viscosity, mold flow and chemical release in a range of rubber applications.

Ideal partitioning and flow agents for molded rubber

Our talcs* improve processability while maintaining mechanical properties and lowering compound costs in rubber. They are ideal for use as chemical release agents.


Our talcs are highly lamellar minerals. This platyness facilitates slippage between talc platelets and solid surfaces, making talc an excellent partitioning agent. Talc also functions as an internal lubricant improving the rheology and flow properties of rubber compounds.

In injection molding and extrusion applications, Imerys talc products:

  • Lower compound viscosities improving mold flow
  • Reduce nerve
  • Reduce mixing time by up to 20% – talc is organophilic and incorporates rapidly into the compound
  • Reduce surface defects such as shark skin
  • improve extrusion rates and surface finish
  • Minimize wear on processing equipment such as extruder screws and dies.

Used in addition to or as a partial replacement for carbon black, Imerys talcs such as our ImerFlex® grades reduce Mooney viscosity by up to 40% and improve mold flow and scorch without affecting cure rate. This combination of improved viscosity and scorch safety widens the processing window.

Chemical release agents

Talc is inherently platy and slippery, meaning it acts as an external lubricant. Imerys talc is an excellent anti-sticking agent in compound handling, processing and part manufacture.

Coarse and platy talc grades are ideal for use in powder form or as talc-water coatings to prevent unvulcanized rubber-to-rubber adhesion in tire demolding, and manufactured rubber goods and for cable insulation.

We recommend:

  • Luzenac 2 coarse grade for mechanical powdering
  • Luzenac 10M2 finer grade for water coatings

*Talc products are not available in the US and Canada. Contact us for an alternative range.