Calcium stearates, which are recognized as physiologically safe, have become increasingly important in the last few years. They are insoluble in most solvents. They dissolve only slightly when heated in aromatic compounds, chlorinated hydrocarbons or vegetable and mineral oils and waxes. Calcium stearates are mainly used as lubricants, mold release agents and acid scavengers by the plastics industry. The pharmaceutical and cosmetics industry uses calcium stearate as an anti-caking additive for powders and granules and as an excipient for pressing tablets. The building industry uses it as hydrophobic agent for inhibiting moisture absorption and preservation of building materials and construction.
Calcium Stearate is used by the rubber and plastic industries as an effective elastomer processing aid and release agent. The low chloride content of Calcium Stearate allows for complete product dispersion in elastomers. Calcium Stearate reduces extruder pressure build-up of rigid PVC compounds when used as a processing aid during the manufacture of pipe, siding and injection molded fittings. The low chloride content of Calcium Stearate meets the quality and processing demands of polyolefin, polystyrene and polyester manufacture.
Zinc Stearate is a chemical substance that has a white, fluffy, powdered appearance and is usually formed from a combination of Stearic acid and zinc oxide. It does not have a strong odour, although traces of a slight fatty acid scent are not uncommon Zinc Stearate is a compound of long-chain fatty acids with Zinc attached to it. Zinc Stearates are insoluble in polar solvents (like alcohol & ethers), but more soluble in in aromatic compounds and chlorinated hydrocarbons when heated.
It is the most powerful release agent among all metal soaps. It contains no electrolyte and has a hydrophobic effect. Because of this versatility, this substance is used by many different types of companies, from plastic industries to concrete manufacturers. It is used extensively in colour concentrates as a dispersion aid.
Its main application areas are the plastics and rubber industry where it is used as a releasing agent and lubricant which can be easily incorporated. These applications exploit its “non-stick” properties. In cosmetics, zinc stearate is a lubricant and thickening to improve texture. It is an “activator” for rubber vulcanization by sulphur and accelerators.
