Low ZOT Latex

Manufacturer: We have been having latex stability problem after compounding for months and was advised by some experts to use "High ZOT" latex. Can you please tell us more about ZOT?

John Woon (Senior Latex Consultant): Sometimes the common test such as MST is not very useful when accessing the suitability of the latex for production use after compounding with curatives, particularly, ZnO.

"ZOT" refers to a test on the degree of increase in viscosity of the latex compound after adding a given amount of ZnO, sometimes also referred to as "Zinc Oxide Thickening Test".


Although there is a British Standard Zinc Stability test (ZST) you can easily design your own ZOT test for your own purpose by adding some amount of ZnO (depending on the level you used in your compound  formulation) followed by stirring and allowing to stand for a given period at room temperature and also at elevated temperatures (e.g. 45 to 60C) before measuring the viscosity using Brookfield viscometer.

Low ZOT can be overcome by proper use of stabilisers and alkali.