Zinc Stearate CAS 557-05-1

Zinc Stearate – Versatile Metallic Soap for Plastics, Rubber, and Cosmetics

Basic Information

• CAS Number: 557-05-1

• Molecular Formula: Zn(C₁₇H₃₅COO)₂

• Appearance: White to off-white fine powder

• Odor: Practically odorless

• Density: ~1.09–1.20 g/cm³

• Melting Point: 120–130°C (softens; decomposition occurs at higher temperatures)

• Solubility: Insoluble in water; soluble in hot organic solvents (benzene, toluene)

• Hydrophobicity: Highly hydrophobic

• Storage: Store in a dry, cool place, protected from moisture and humidity

Overview
Zinc stearate is the zinc salt of stearic acid, belonging to the class of metallic soaps. It combines lipophilic (fatty acid) and hydrophobic properties, making it an effective lubricant, release agent, and stabilizer in various industrial applications. Its fine particle size and white color allow it to be used in a wide range of products without affecting appearance. It is widely employed in plastics, rubber, cosmetics, and pharmaceutical formulations.

Applications

• Lubricant and release agent: Used in injection molding, powder metallurgy, and as an anti-blocking agent for films and coatings.

• PVC stabilizer: Prevents thermal degradation of polyvinyl chloride during processing, improving heat stability and color retention.

• Rubber industry: Acts as an activator for vulcanization and as a processing aid in rubber compounding.

• Cosmetics and personal care: Used in powders, talcum products, and as a thickening agent in creams and lotions; also as a drying agent in dermatological preparations.

• Pharmaceuticals: Employed as a lubricant in tablet compression and as a glidant in powder formulations.

• Paints and coatings: Used as a matting agent and to improve water resistance.

• Construction materials: Added to cement and concrete to improve water repellency.

Key Benefits

• Excellent lubricity and anti-adhesive properties.

• Effective heat stabilizer for PVC and other thermoplastics.

• Improves processing efficiency and surface finish.

• Hydrophobic, providing water resistance.

• Non-toxic and safe for use in food-contact applications (subject to regulations).

• Cost-effective and widely available.

• Compatible with many polymers and formulations.

Safety and Handling

• Generally regarded as safe at recommended use levels.

• May cause mild irritation upon skin contact or inhalation of dust; use appropriate personal protective equipment (gloves, safety goggles, dust mask).

• Avoid contact with strong oxidizers and high temperatures (>250°C) to prevent decomposition.

• Store in a dry place, protected from moisture and heat.

• Shelf life: typically 24 months under recommended storage conditions.

Quality Assurance
Each batch is tested for zinc content, moisture, free fatty acid content, and particle size to ensure consistent quality.