Zinc Stearate
About This Product
Zinc stearate is the zinc salt of stearic acid, a white metallic soap supplied as a fine powder in 125, 200 and 325 mesh and as beads, flakes or granules for low-dust handling. Typical zinc content is 10.5-11.1% and free fatty acid is 0.5% maximum, or 1.5% maximum on the wide-tolerance grade. Vegetable-based, from palm-derived fatty acids. Zinc stearate is usually paired with calcium stearate rather than used alone: the zinc component is the primary heat stabiliser in a calcium-zinc PVC system, exchanging stearate for the labile chlorine atoms on the backbone, the sites from which dehydrochlorination propagates. That exchange leaves zinc chloride, a Lewis acid that accelerates degradation if it accumulates, which is why calcium scavenges the acid that the zinc chloride by-product would otherwise generate. Getting the ratio right is what determines the stabiliser's service life. Outside PVC it is used as a mould release, as a dusting agent to stop uncured rubber sheets sticking to each other, and as a sanding additive in coatings to prevent paper loading. Its melting point of 119-125C is materially lower than calcium stearate's, which matters when selecting a processing window. It is used in PVC heat stabilisation, as a mould release, as a rubber anti-tack dusting powder, as a coatings sanding additive and in masterbatch. Bio Green Chem supplies zinc stearate in 25 kg and 20 kg bags and jumbo bags to specification on mesh or bead form, zinc content, free fatty acid, melting point and heating loss.
