Magnesium stearate

Chemical Properties: Magnesium stearate, also known as magnesium octadecanoate. Chemical formula: Mg(C₁₈H₃₅O₂). Molecular weight: 591.27. White, soft, glossy powder or lumps. Industrial products contain a small amount of oleic acid and 7% magnesium oxide and are odorless and tasteless. Slightly soluble in water, soluble in hot ethanol. Decomposes into stearic acid and the corresponding magnesium salt upon contact with strong acids. It is produced by reacting molten stearic acid with magnesium oxide or sodium stearate solution with dilute magnesium sulfate solution. It is used as a matting agent for paints, a powder mold for tablets, and a stabilizer for plastics. It is used in the manufacture of perfumes and cosmetics, as well as a drying agent for paints and lacquers. It also serves as an anti-caking agent, release agent, and emulsifier.

Uses: This product is used as a heat stabilizer for polyvinyl chloride, as an excipient and lubricant in cosmetic flours, emollient ointments, and pharmaceutical tablets. It is also used in wood flour to impart lubricity, gloss, and transparency, and as a transparent matting agent in the paint industry. The metal soaps used as polyvinyl chloride stabilizers are mostly higher fatty acid salts of cadmium, barium, calcium, zinc, and magnesium, based on salts of stearic acid and lauric acid. The performance of metal soap stabilizers varies depending on the type of metal and the acid radical, but the general pattern is as follows: Heat resistance: Cadmium and zinc soaps have good initial heat resistance; barium, calcium, magnesium, and strontium soaps have good long-term heat resistance, with lead soap falling in between. Weather resistance: Cadmium, zinc, lead, barium, and tin soaps are relatively good. Processability: Lead and cadmium soaps have good lubricity, but the acid radical also significantly affects lubricity. For the same metal, aliphatic soaps are better than aromatic ones, and in aliphatic acid radicals, longer molecular chains also improve lubricity. Barium, calcium, magnesium, and strontium soaps have poor lubricity but good gelation properties. Pressure Segregation: Barium, calcium, magnesium, and strontium soaps are prone to pressure segregation, while zinc, cadmium, and lead soaps are less prone to it. The longer the molecular chain of the fatty acid soap, the heavier the pressure segregation and the more severe the blooming. Lead and cadmium soaps are highly toxic and can cause sulfide contamination. Calcium and zinc soaps are often used in non-toxic formulations, while barium and zinc soaps are often used in formulations resistant to sulfide contamination. Magnesium stearate is considered non-toxic and is permitted for use in food contact products in the United States, Germany, and Japan, but its use as a heat stabilizer for polyvinyl chloride is not widespread. It is included in the Chinese Pharmacopoeia and some other national pharmacopoeias, which specify magnesium content, moisture, heavy metals, iron, sulfate, and chloride content.

Uses

Stabilizer; Lubricant; Pharmaceutical Tablet Raw Material. Magnesium stearate is a new pharmaceutical excipient used as a film-forming coating for solid dosage forms, a thickener for colloidal liquid preparations, and a suspension.