Zinc Stearate

About This Product

Zinc stearate is made by reacting stearic acid with a zinc source, giving a metallic soap that is water-insoluble, hydrophobic and solid at ambient temperature. It is supplied at 10.5-11.1% zinc, free fatty acid 0.5% maximum, melting point 119-125C and heating loss 1.0% maximum, as 125, 200 or 325 mesh powder and as beads, flakes and granules for low-dust handling. Vegetable-based, from palm-derived fatty acids.

It is one of the highest-volume fatty acid derivatives after the acids themselves, and the reason is a hydrophobic surface combined with a low melting point. Compared with the calcium equivalent it melts around thirty degrees lower, at 119-125C, and carries roughly half again the metal content; those two differences govern which one a compounder reaches for, and many formulations use both together. The lower melting point means the soap softens and spreads at ordinary processing temperatures, laying down a continuous film at the tool face rather than sitting there as discrete particles, which is why it is the usual choice for release and anti-tack work. The higher metal content means more zinc is delivered per kilogram added. The same hydrophobicity keeps the powder from taking up moisture in store, but makes wetting and dispersion into a polar system the harder part of the job.

It is used in metallic soap manufacture, as a release and anti-tack agent, in fatty acid derivatives and in industrial compounding.

Bio Green Oleo supplies zinc stearate to specification on zinc content, free fatty acid, melting point, heating loss, mesh or granular form and packaging.