Calcium stearate

Description

Calcium stearate is carboxylate of calcium that is found in some lubricants and surfactants. It is a white waxy powder. It is formed as "scum" when SOAP, containing the soluble salt sodium octadecanoate, is mixed with hard water containing calcium ions.

Chemical properties

Calcium stearate occurs as a fine, white to yellowish-white, bulky powder having a slight, characteristic odor. It is unctuous and free from grittiness. It is found in some lubricants and surfactants.

The Uses of Calcium stearate

Calcium stearate is a fatty acid calcium complex preparation, which functions as an anticaking agent, binder, and emulsifier. For waterproofing fabrics, cement, stucco, explosives; as a releasing agent for plastic molding powders; as a stabilizer for polyvinyl chloride resins; lubricant; in pencils and wax crayons. Food grade calcium stearate, derived from edible tallow, is used as a conditioning agent in certain food and pharmaceutical products. It is used in garlic salt, dry molasses, vanilla and vanilla-vanillin powder, salad dressing mix, and meat tenderizer. it can be used for mold release in the tableting of pressed candies.

Production Methods

Calcium stearate is prepared by the reaction of calcium chloride with a mixture of the sodium salts of stearic and palmitic acids. The calcium stearate formed is collected and washed with water to remove any sodium chloride.

Preparation

Calcium stearate is produced by heating stearic acid, a fatty acid, and calcium oxide:
2C₁₇H₃₅COOH + CaO→(C₁₇H₃₅COO)₂Ca + H₂O
It is also the main component of soap scum, a white solid that forms when soap is mixed with hard water. Unlike soaps containing sodium and potassium, calcium stearate is insoluble in water and does not lather well . Commercially it is sold as a 50 % dispersion in water or as a spray dried powder. As a food additive it is known by the generic E number E470. .

Pharmaceutical Applications

Calcium stearate is primarily used in pharmaceutical formulations as a lubricant in tablet and capsule manufacture at concentrations up to 1.0% w/w. Although it has good antiadherent and lubricant properties, calcium stearate has poor glidant properties.
Calcium stearate is also employed as an emulsifier, stabilizing agent, and suspending agent, and is also used in cosmetics and food products.

Safety Profile

A nuisance dust. When heated to decomposition it emits acrid smoke and irritating fumes.

Safety

Calcium stearate is used in oral pharmaceutical formulations and is generally regarded as a relatively nontoxic and nonirritant material.

storage

Calcium stearate is stable and should be stored in a well-closed container in a cool, dry place.

Regulatory Status

GRAS listed. Included in the FDA Inactive Ingredients Database (oral capsules and tablets). Included in nonparenteral medicines licensed in the UK. Included in the Canadian List of Acceptable Non-medicinal Ingredients.