Description
Aluminium stearate is an aluminium salt of stearic acid, known chemically as aluminium tristearate, with the formula
Al(C
18
H
35
O
2
)
3
Al(C
18
H
35
O
2
)
3
or
C
54
H
105
AlO
6
C
54
H
105
AlO
6
. It is a fine, white, water-insoluble powder widely used for its lubricating, thickening, gelling, and water-repellent properties in a range of industrial and commercial applications.
Chemical Properties and Composition
Chemical Formula:
Al(C
18
H
35
O
2
)
3
Al(C
18
H
35
O
2
)
3
.
Molecular Weight: 877.39 g/mol.
Appearance: Fine, white, odourless and fluffy powder.
Melting Point: Typically 135–170°C.
Solubility: Insoluble in water and ethanol; soluble in benzene, turpentine, mineral oils, and hot organic solvents; soluble in alkali.
Stability: Stable, but decomposes in hot, strong acids.
Uses
Lubricant and Thickener: Commonly used in the plastics, rubber, and grease industries as an internal and external lubricant, and as a thickener in lubricants and greases for stability under heat and mechanical stress.
Paints and Coatings: Functions as a water-repellent, viscosity modifier, pigment dispersant, and gelling agent in alkyd paints and varnishes, improving their durability and performance.
Waterproofing and Cements: Serves as a waterproofing additive for fabrics, ropes, and cements.
Pharmaceuticals and Cosmetics: Employed as a thickening agent, binder, stabilizer, and emulsifier in cosmetic creams, ointments, lotions, and pharmaceutical tablets.
Other Industrial Uses: Used as a defoaming agent in drilling fluids, as a retarder for dental impression materials, a flatting agent, and as a water-repellent soap for treating stone and bricks.
Technical and Safety Highlights
Form/Handling: Forms a plastic mass when heated; safe under normal handling but should be avoided in high concentrations or ingestion.
Ash Content: Varies by grade, typically 7.5–11.5% for technical products.
Additional Properties: High hydrophobicity, mild antiseptic/aesthetic properties, and good compatibility with other formulation ingredients.
Aluminium stearate is valued for its versatility, stability, and multifaceted utility across industries such as plastics, cosmetics, paints, and construction materials.