Stearic acid

Stearic acid is characterised by the following properties:

• Melting point: approx. 69 to 70 °C.

• Hydrophobic properties: it is water-repellent but soluble in organic solvents.

• Stability: chemically stable under normal conditions.

• Lubricity: acts as a lubricant and release agent.

• Biodegradable: environmentally friendly and sustainable.

Stearic acid is obtained by hydrolysis of animal fats or vegetable oils. The raw material is split into glycerol and fatty acids at high temperatures and under pressure in the presence of a catalyst. The stearic acid is then isolated and purified by distillation or crystallisation.

There are different types of stearic acid, which differ in purity and origin:

Type	Properties	Typical applications
Technical stearic acid	Also contains palmitic acid and other fatty acids	Rubber industry, lubricants
Pure stearic acid	High purity (over 95%)	Cosmetics, pharmaceutical industry
Distilled stearic acid	Particularly high purity	Food additive, candle making

Stearic acid is used in many industries, including:

Rubber and plastics industry

• Vulcanisation activator: stearic acid acts as a catalyst in the crosslinking of rubber.

• Lubricant: improves the processability of plastics and rubber.

• Release agent: prevents materials from sticking to moulds.

Cosmetics and pharmaceutical industry

• Emulsifier: helps stabilise creams and lotions.

• Thickener: gives products a firm, smooth texture.

• Tablet production: serves as a lubricant in tablet manufacturing.

Candle and wax production

• Hardener: improves the dimensional stability of candles.

• Gloss agent: gives candles a smooth, glossy surface.

Using stearic acid offers numerous advantages:

• Versatility: can be used in a wide range of applications.

• Cost efficiency: inexpensive to produce and process.

• Environmental friendliness: biodegradable and sustainable.

• Availability: readily available from natural sources.

Despite its versatility, there are some challenges in using stearic acid:

• Compatibility: can be incompatible with certain materials or chemicals.

• Purity: certain applications require a high degree of purity, which can increase costs.

• Temperature dependence: melting point and stability can be limiting factors in heat-sensitive applications.

• Is stearic acid environmentally friendly? Yes, it is biodegradable and is often obtained from renewable raw materials.

• Can stearic acid be used in food? Yes, in pure form stearic acid is used as a food additive (E570).

• How is stearic acid used in the rubber industry? It serves as a vulcanisation activator and lubricant to improve the processing and properties of rubber.

• What alternatives to stearic acid are there? Depending on the application, other fatty acids or synthetic additives can be used, e.g. palmitic acid or special polymers.

Stearic acid is an indispensable ingredient in numerous industries, from rubber and plastics processing to cosmetics and food production. Its chemical and physical properties make it a versatile, cost-efficient additive. Despite some challenges in use, stearic acid remains an essential raw material in modern industry thanks to its availability, sustainability and versatility.