chapter  14
42 Pages

Inorganic Ultraviolet Filters

Evolution and Perspectives 240

Evolution of Inorganic Ultraviolet Filters 240

Titanium Dioxide and Zinc Oxide 241

Perspectives for Inorganic UV Filters 241

Physical and Chemical Properties of Titanium Dioxide and Zinc Oxide 242

General Properties 242

Titanium Dioxide 242

Zinc Oxide 243

Isoelectric Point 244

Photocatalytic Activity 244

Glycol Method 246

Vitamin Method 246

Optical Behaviors 246

Scattering 247

Absorption 247

Manufacturers of Inorganic Ultraviolet Filters 248

Production of Micronized Titanium Dioxide 249

Manufacturers of Micronized Titanium Dioxide 250

Typical Specifications of Micronized Titanium Dioxide 250

Production and Manufacturers of Micronized Zinc Oxide 250

Typical Specifications of Micronized Zinc Oxide 252

Surface Treatment 252

Background 252

Surface Properties of Micronized Pigments 253

Inorganic/Organic Surface Treatments 254 Popular Surface Treatments for Micronized Pigments 255

Surface Treatments of Micronized Titanium Dioxide or Zinc Oxide

for Use with Avobenzone 255

Hydrophilic Surface Treatments for Micronized Pigments 255

Selecting the Proper Surface Treatment 255

Influence of Particle Size on UV Attenuation by TiO2 and ZnO 256

Particle Size 256

Influence of Particle Size on UV Attenuation 257

Titanium Dioxide 257

Zinc Oxide 259

Characterization of TiO2 and ZnO Dispersions 261

Dispersion of Inorganic Ultraviolet Filters 264

Objectives of the Dispersion Process 264

Index of Agglomeration 265

Advantages of Dispersions 266

Incorporating Micronized Pigments and Dispersions into Formulations 266

Producers of Dispersions 266

Formulations 267

Guidelines 267

Emulsifiers and Additives 269

Determining Suitable Levels of Actives 269

Foundations and Daily UV Lotions 270

Formulating with Zinc Oxide 270

Obtaining Broad-Spectrum Protection 271

Sample Formulations 272

W/O Waterproof Sunscreen Formula SPF 30þ 272 O/W Sunscreen Lotion SPF 27 272 Sunscreen Cream Gel 273

Sprayable O/W Sunscreen SPF 15þ 274 Regulations, Claims, Toxicity, and Testing 275

Summary 276

References 276

EVOLUTION AND PERSPECTIVES

Evolution of Inorganic Ultraviolet Filters

The popularity of inorganic ultraviolet (UV) filters with consumers and formula-

tors results from their effectiveness and safety. It is disclosed in JP Application

No. 1981-161,881 that when 0.1-40% of ultrafinely divided titanium oxide with

a particle size of 10-30 nm, which has been rendered hydrophobic, is blended

into cosmetic base materials, it transmits visible light but reflects and scatters

the harmful UV rays (1).