11.11.2020 A synergy by a zinc oxide active and a processing aid

A synergy by a zinc oxide active and a processing aid

This study explores the use of two additives in synergy

  • Zinc oxide active as: CS AZO by PCC Taiwan
  • Processing aid with lower zinc content as: Polyplastol SF 45

The ZnO releases into the aquatic ecosystem through domestic or industrial wastewater . It has the potential to induce harmful  effects on fish and other organisms.

To overcome these barriers, our approach was to develop a rapid product as processing aid that requires a minimal amount of ZnO material.

In the present study we compared the effect in combination with an Low zinc content processing aid with  Zinc oxide active .

The compound has been selected using

  1. NR (CV 60)
  2. SBR (1502)
  3. BR (60)
  4. SILICA VN3 ( 70 PHR)

In  the first compounds has been added

  • ZnO French process: 5 PHR
  • Zinc soap: 2 PHR

Many studies dealt with the causes of difficulty in extruding high silica compounds. In the case of a 100% silica compound, the risk to reach the maximum potentiality of Mooney viscosity was very high, even considering that most of the mixing problems could  occur inside the internal mixer causing many troubles to the inner rotors. The gears suffered  devastating effects having to work at maximum effort in order to mix a high content of solids and fine powders . The addition of 5 PHR of French process Zinc Oxide didn’t help the blending of all components causing a pre scorch activity in many lots. This due to the increasing of inner temperature and the addition of activators that  activated a pre curing action . The filler dispersion and distribution were  not satisfactory in spite of the presence some standard lubricants (2 PHR of a common Zinc soap). The compound was too stiff to be extrudable.

In order to overcome the mixing difficulty with the present work we have included in the second  compound . Rest of the receipt was kept as first compound

  • 3 PHR of CS AZO by PCC (instead of 5 PHR of French Process Zinc Oxide)
  • 2 PHR Polyplastol SF 45 (instead of 2 PHR of common Zinc soap)

These additives significantly facilitated the incorporation, distribution, and dispersion of the filler. Even with a reduction of the standard quantities of ZnO. The resulting compounds was   soft enough to be extruded. The curing system has not been changed but thanks to the reduction of ZnO and thanks to the CS AZO feature we could stop problems of pre scorch and getting a shorten vulcanization time of about 5-10%.   The total Zinc amount has been dramatically reduced and the new blend of unsaturated fatty acid mixture could reach a better shear during the first raw materials mixing. The extrudate surfaces were smooth and free of dots .

The output of the extrusion has increased due to a significant reduction of viscosity inside the head of the extruder.


Zinc oxide active named: CS AZO is a product coming from a  recent study by one of our Principal that is  Pan Chemical Continental CO Ltd, that accordingly to the current new rules on uses of French process Zinc oxide they started  to invite many customers to  reduce zinc level improving dispersibility of ZnO and enhancing the formation of free zinc.

The new role of CS AZO is to have first a controllable structure reducing the surface energy and polarity.

CS AZO has an high activity improving even physical properties.

With CS AZO the release of metal zinc is reduced by lower 50% of solid waste and wastewater.

Being also an easy processing product it can works better with a lubricant effect processing aid.

Polyplastol® SF 45 by E&V

This a processing aid based on a balance between two metal oxided

Polyplastol SF 45 if included in a mix primarily , reduces the time and energy requires in breaking down the polymers.

It contains a minimal zinc oxide quantity and thanks to a new blend of unsaturated fatty acid and low impact metal oxide can help as physical peptizer for Natural rubber.

Thanks to its low solubility  can prevent from sticking to mill or calendar rolls.

The dropping point has been designed to be  assigned in the first mixing phase, in order to avoid the slipperiness of the ingredients due to a premature melting of the processing aid.