Polyhydroxystearic Acid (PHSA)

Polyhydroxystearic Acid (PHSA) – Polymeric Dispersant for Pigments in Cosmetics

Basic Information

• Product Name: Polyhydroxystearic acid

• CAS Numbers: 58128-22-6; 27924-99-8

• Molecular Formula: C₁₈H₃₆O₃

• Relative Molecular Mass: 300.48 g/mol

• Appearance: Amber to brown viscous liquid

• Relative Density: 0.91–0.93 g/cm³

• Solubility: Insoluble in water

Overview
Polyhydroxystearic acid (PHSA) is a polymeric dispersant specifically designed for the stabilization of pigments and particulates in non‑aqueous systems. It is widely used in cosmetic and sunscreen formulations to improve color development, dispersion stability, and overall product performance.

Mechanism of Action
PHSA contains multiple hydroxyl groups and a long hydrophobic fatty chain, which allow it to adsorb onto pigment surfaces and provide steric stabilization. This prevents flocculation, sedimentation, and agglomeration of pigments in oil‑based or solvent‑based media.

Applications

• Lip products: Lipsticks, lip glosses, and lip balms – ensures even color distribution and smooth application.

• Face makeup: Liquid foundations, concealers, and blush – enhances pigment wetting and improves coverage.

• Eye makeup: Eyeshadows, eyeliners, and mascara – provides stable dispersion for intense, long‑lasting color.

• Sunscreen: Stabilizes mineral UV filters (e.g., zinc oxide, titanium dioxide) in suncare formulations.

• General cosmetics: Useful in any anhydrous or oil‑based pigmented system.

Recommended Usage
When preparing a dispersion, first dissolve the dispersant in the carrier liquid, then add the pigment. The optimal amount of dispersant varies with each pigment grade; a starting level of approximately 25% above the minimum required for viscosity reduction is recommended. Final dosage should be optimized using equipment that simulates the production process.

Key Benefits

• Excellent pigment wetting and stabilization.

• Improves color strength and reduces settling.

• Compatible with oils, esters, and hydrocarbon solvents.

• Provides smooth texture and even film formation.

• Enhances long‑term stability of cosmetic formulations.

Handling and Storage

• Store in a dry, cool, well‑ventilated place, away from heat and direct sunlight.

• Keep containers tightly sealed to prevent contamination and moisture ingress.

• Do not store or transport with flammable, explosive, or toxic materials.

• Dispose of waste materials in accordance with local environmental regulations.

Packaging
Available in 25 kg drums, or custom packaging upon request.

Quality Assurance
Each batch is tested for acid value, color, viscosity, and dispersing performance to ensure consistent quality.