Stearic acid is a high-grade saturated fatty acid. The pure product is a shiny white soft flake. Relative density 0.9408 (20℃), melting point 69-71℃, boiling point 383℃, refractive index 1.4299 (80℃).
Industrial products are white or slightly yellow granules, a mixture of stearic acid and palmitic acid, and contain a small amount of oleic acid, with a slight butter-like smell. It is very slightly soluble in cold water, easily soluble in benzene, toluene, chloroform, carbon tetrachloride, carbon disulfide, amyl acetate, etc., and also soluble in ethanol and acetone. Industrial products are divided into first-grade products (or 200 type, formerly known as three-pressed stearic acid, after three squeezes), second-grade products (or 400 type, formerly known as two-pressed stearic acid, after two squeezes) and third-grade products (or 800 type, formerly known as one-pressed stearic acid, after one squeeze or without squeeze). First-grade and second-grade products are white waxy solids, and third-grade products are light yellow waxy solids. Stearic acid rarely exists alone in nature. It often exists in the form of glycerol esters, such as tristearate. It exists in the oils of most animals and plants, especially in butter, where it is most abundant. Stearic acid is an organic acid that can react with alkali to form sodium stearate, a soap.
Stearic acid has a wide range of uses. In the cosmetics industry, it is an indispensable raw material for the manufacture of general emulsified products. It is used to prepare vanishing creams, cold creams, foundation creams, shaving creams, hair creams and skin care lotions. In the rubber industry, it is a vulcanization activator for natural rubber, synthetic rubber and latex, and is also used as a softener. In the plastics industry, it is used as a plasticizer, stabilizer and lubricant. In the textile industry, it is used as a yarn lubricant and a softener for making mercerizing pastes. It is also used to make release agents, polishing pastes, defoamers, metal flotation agents, paint matting agents, wax paper polishing agents, textile waterproofing agents and other products. It is a solvent for oil-soluble pigments. It is also the raw material for manufacturing stearic acid methyl ester, stearic acid glyceryl ester, calcium stearate, potassium stearate, lead stearate and other stearic acid esters and stearates.