Zinc Oxide (CI 77947)-Broad-Spectrum UV Filter CAS 1314-13-2

Zinc Oxide (ZnO) – Versatile Sunscreen Active, Skin Protectant, and Industrial Material

Basic Information

• CAS Number: 1314-13-2

• Chemical Formula: ZnO

• Molecular Weight: 81.38 g/mol

• INCI Name: Zinc Oxide (CI 77947)

• Appearance: White, fine, odorless powder

• Particle Size: Available in microfine (<100 nm) and conventional grades

• Solubility: Practically insoluble in water; dispersible in oils and organic solvents

• Melting Point: 1975°C

• pH (suspension): 7–8

Overview
Zinc oxide (ZnO) is an inorganic compound widely used across multiple industries due to its excellent UV protection, antimicrobial activity, biocompatibility, and durability. It is a broad-spectrum physical (mineral) UV filter absorbing both UVA and UVB radiation (280–400 nm), making it a key ingredient in sunscreens and other photoprotective formulations. Its anti-inflammatory, astringent, and antimicrobial properties also make it valuable in dermatology, pharmaceuticals, and personal care products.

Synthesis
Zinc oxide is produced through several industrial methods:

• French Process (Indirect): Zinc metal is vaporized and then oxidized to ZnO in a controlled atmosphere.

• American Process (Direct): Zinc ore or zinc-containing materials are roasted in the presence of carbon to produce zinc vapor, which is then oxidized.

• Chemical Precipitation: Zinc salts (e.g., zinc nitrate) are precipitated with alkali, followed by calcination.
  Microfine zinc oxide (nanoparticle grade) is produced using specialized techniques to achieve controlled particle sizes for transparent sunscreen applications.

Physicochemical Properties

• UV absorption: Effective broad-spectrum filter (280–400 nm).

• Photostability: Does not degrade upon UV exposure.

• Anti-inflammatory: Reduces skin irritation and redness.

• Antimicrobial: Active against bacteria and fungi.

• Astringent: Dries and soothes minor skin irritations.

• High refractive index: Provides opacity and whitening in formulations.

• Thermal stability: Stable up to ~1800°C.

• Non-comedogenic: Does not clog pores (microfine grades).

Applications

• Sunscreens: Face and body sunscreens, daily moisturizers with SPF – provides broad-spectrum UV protection with excellent photostability.

• Dermatology: Barrier creams, diaper rash ointments, anti-acne formulations – soothes, protects, and promotes healing.

• Personal care: Baby powders, dusting powders, anti-chafing products – provides soothing, antimicrobial, and drying effects.

• Color cosmetics: Foundations, powders, concealers – offers coverage, opacity, and UV protection.

• Industrial: Used in rubber manufacturing, ceramics, paints, coatings, plastics, adhesives, and electronics.

• Other: As a catalyst, filler, and pigment in various industrial applications.

Key Benefits

• Excellent broad-spectrum UV protection (UVA/UVB).

• Photostable – no degradation under sunlight.

• Safe and non-irritating – suitable for sensitive skin and children.

• Provides anti-inflammatory and antimicrobial benefits.

• Available in transparent microfine grades for elegant formulations.

• Versatile – used in skin care, sun care, color cosmetics, and dermatology.

• Can be combined with other UV filters for enhanced protection.

• Approved by global regulatory authorities (EU, FDA, TGA) for use in sunscreens.

Recommended Use
Typical usage levels:

• Conventional grade (opaque): 5–25% for high SPF formulations.

• Microfine/transparent grade: 5–15% for aesthetic sunscreens.

• For optimal dispersion, incorporate into the oil phase with high-shear mixing or use pre-dispersed pastes. Can be combined with other UV filters (organic or inorganic) for synergistic protection.

Safety and Handling

• Generally recognized as safe (GRAS) for use in cosmetics at recommended concentrations.

• Low irritation potential; well-tolerated by skin.

• Avoid inhalation of dust – use appropriate personal protective equipment (gloves, dust mask, safety goggles).

• Store in a cool, dry place, away from direct sunlight and moisture.

• Shelf life: typically 24–36 months under recommended storage conditions.

Quality Assurance
Each batch is tested for purity, particle size distribution, heavy metals (lead, cadmium, arsenic), and microbial contamination to ensure compliance with cosmetic, pharmaceutical, and industrial standards.