Calcium Stearate
About This Product
Calcium stearate is the calcium salt of stearic acid, a white metallic soap supplied as a fine powder in 125, 200 and 325 mesh and as beads or granules for low-dust handling. It melts at 149-155C, typical calcium content is 6.5-7.1% and free fatty acid is 0.5% maximum, or 1.5% maximum on the wide-tolerance grade. Vegetable-based, from palm-derived fatty acids. Calcium stearate does several jobs at once in a polymer compound, which is why it appears in so many formulations. It scavenges the hydrogen chloride released as PVC degrades, and because dehydrochlorination is autocatalytic, removing HCl as it forms breaks the loop that would otherwise build the conjugated polyene sequences that discolour the resin. It acts as an internal lubricant, migrating between polymer chains to reduce melt viscosity rather than sitting at the metal interface as an external lubricant does. And it neutralises acidic catalyst residues in polyolefins, which would otherwise attack tooling and shorten resin life. Particle size is the specification that usually matters most in practice: a finer mesh disperses faster and gives a more uniform compound, but is dustier and harder to handle, while the coarser grades and the bead form trade dispersion speed for cleaner handling. It is used in PVC stabilisation, polyolefin acid scavenging, as an internal lubricant and mould release, and in rubber and masterbatch. Bio Green Chem supplies calcium stearate in 20 kg bags and jumbo bags to specification on mesh or bead form, calcium content, free fatty acid, melting point and heating loss.
