What Is Stearic Acid?
Stearic acid is a high-level saturated fatty acid, purely made of white soft tablets with gloss. The relative density is 0.9408 (20 °C), melting point 69–71 °C, boiling point 383 °C, and refractive index 1.4299 (80 °C).
Commercial Grades
Its industrial products are white or slightly yellow granules - a mixture of stearic acid and palmitic acid containing a small amount of oleic acid, with a slight butter-like smell. Very slightly soluble in cold water, easily soluble in benzene, toluene, chloroform, carbon tetrachloride, carbon disulfide and amyl acetate, and also soluble in ethanol and acetone. Industrial products are divided into:
- First-grade products (type 200, formerly known as triple-pressed stearic acid) - pressed three times.
- Second-grade products (type 400, formerly double-pressed) - pressed twice.
- Third-grade products (type 800) - pressed once or not.
The first- and second-grade products are white waxy solids; the third grade is a light yellow waxy solid. Stearic acid is rarely found alone in nature and often exists in the form of glycerides, such as glyceryl tristearate, which is found in most animal and plant oils and fats - especially butter, where it is most abundant. Stearic acid is an organic acid that can react with alkali to produce sodium stearate - a soap.
Main Uses
- Cosmetics industry: an indispensable raw material for general emulsified products - sauce cream, cold cream, foundation cream, shaving cream, hair cream and skin care lotion.
- Rubber industry: a vulcanizing active agent for natural rubber, synthetic rubber and latex, and also used as a softener.
- Plastics industry: a plasticizer, stabilizer and lubricant.
- Textile industry: a yarn lubricant and a softener for mercerizing paste.
- Other products: mold release agents, polishing pastes, defoaming agents, metal flotation agents, paint flattening agents, wax-paper polishing agents and textile waterproofing agents.
- Chemical derivatives: a solvent for oil-soluble pigments, and a raw material for fatty acid esters and stearates such as methyl stearate, glyceryl stearate, calcium stearate, potassium stearate and lead stearate.
How is stearic acid manufactured?
Stearic acid is made from hydrogenated cottonseed oil, palm oil, tallow and mutton fat, hydrolyzed in the presence of a decomposition agent (a sulfonated mixture of benzene, naphthalene and similar materials), and then produced by distillation, pressing (or without pressing), pickling and decolorization.