Titanium Dioxide Particle vs. Sun Protection Performance

May 1, 2013 | Contact Author | By: S. Wiechers, PhD; P. Biehl; C. Luven; M. Maier, PhD; J. Meyer, PhD; J. Münzenberg, PhD; and C. Schulze-Isfort, PhD Evonik Industries AG; and P. Albers, PhD, Aqura GmbH
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Title: Titanium Dioxide Particle vs. Sun Protection Performance
sun carex titanium dioxidex inorganic (mineral) UV filterx microfine particlesx
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Keywords: sun care | titanium dioxide | inorganic (mineral) UV filter | microfine particles

Abstract: The article compares the performance of titanium dioxide as a UV filter in cosmetic formulations as a function of its primary particle size. It was found that with increasing primary particle size, even below 100 nm, the effectiveness of the inorganic (mineral) UV filter was clearly reduced.

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S. Wiechers et al, Titanium dioxide particle vs. sun protection performance, Cosm & Toil 128(5) 332-339

Market Data

  • Awareness among consumers about the harmful effects of UV boosted sun care sales by 6.5% in 2012 in the United States.
  • Sun care marketers are diversifying their product offerings; a common trend emerging is to include tint.
  • Although spray-on sun care products are popular, there are rising concerns associated with the inhalation of nanoparticles.
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Skin protection against ultraviolet (UV) radiation has become a necessity as the connection between serious skin conditions and a changed lifestyle has become more obvious in recent years. This has led formulators to use UV filters not only in sunscreens, but also in face care products. Modern sunscreen formulations with high sun protection factors (SPFs) often rely on a mixture of organic and inorganic UV filters. For UVB protection, titanium dioxide (TiO2)-based materials are an addition or alternative to organic UV filters as they efficiently help to prevent sunburn without the inherent drawbacks of organic UV filters, such as light degradation and in some cases, an unfavorable toxicological profile. Further, the German Federal Institute for Risk Assessment (BfR) has come to the conclusion that TiO2 UV filters do not penetrate the dermis and pose no risk for the consumer.

The article compares the performance of TiO2 as a UV filter in cosmetic formulations as a function of its primary particle size. It was found that with increasing primary particle size, even below 100 nm, the effectiveness of the inorganic (mineral) UV filter was clearly reduced.

Excerpt Only This is a shortened version or summary of the article you requested. To view the complete article, please log in or create an account. Registration is Free!

This is an excerpt of an article from GCI Magazine. The full version can be found here.

 

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Table 1. Particle sizes of commercial and experimental TiO2 UV absorbers produced by flame hydrolysis

Table 1. Particle sizes of commercial and experimental TiO2 UV absorbers produced by flame hydrolysis

Key characteristics of the surface modification process such as type and homogeneity were carefully controlled by process conditions. Main characteristics of the products generated by this process are summarized here.

Figure 1. TEM images of TiO2 UV absorbers

Figure 1. TEM images of TiO2 UV absorbers

TEM images of TiO2 UV absorbers produced by flame hydrolysis: a) commercial TiO2 UV filterf; b) experimental Product 1; c) experimental Product 2; d) experimental Product 3 and e) experimental Product 4

Figure 2. Whitening effect

Figure 2. Whitening effect

Whitening effect of commercial TiO2 UV filterf and experimental products 1–4 in the test formula

Figure 3. Results of in vitro SPF

Figure 3. Results of in vitro SPF

Results of in vitro SPF of commercial TiO2 UV filterf and experimental products 1–4 in test formula

Figure 4. SPF and critical wavelength

Figure 4. SPF and critical wavelength

SPF (in vitro) and critical wavelength λC are dependent upon the median primary particle size.

Footnotes [Wiechers 128(5)]

a A H-7500 100KV microscope manufactured by Hitachi, Tokyo, and calibrated against Mag*i*cal Nr. 641 from Norrox Scientific, Beaver Pond, Ontario, Canada was used in this study.

b The TGZ-3 graphical analyzer is a device from Zeiss, Germany.

c The Coulter LS 13320 diffraction granulometer is manufactured by Beckmann Colter, Inc., Indianapolis, USA.

d Tegosoft TN (INCI: C12-15 Alkyl Benzoate) is a product of Evonik Industries AG, Germany.

e The Polytron TT 3100 rotor stator equipped with a PT-DA 3020/2EC mixer is a device from Kinematica, Luzern, Switzerland.

f Tego Sun T 805 (INCI: Titanium Dioxide (and) Trimethoxycaprylylsilane) is a product of Evonik Industries AG, Germany.

g The Micro Color II colorimeter is a device from Hach-Lange.

h PMMA slides from Schönberg, roughness 2 μm, were used for this study.

j The UV-2000S transmittance analyzer from Labsphere was used for this study.

k Tegosoft DEC (INCI: Diethylhexyl Carbonate) is a product of Evonik Industries AG, Germany.

Formula 1. Sun care formulation for application tests

A. Ceteareth-15 (and) Glyceryl Stearate (Tego Care 215, Evonik AG) 3.5% w/w
Stearyl Alcohol (Tego Alkanol 18, Evonik AG) 0.5
Glyceryl Stearate (Tegin M Pellets, Evonik AG) 0.5
Diethylhexyl Carbonate (Tegosoft DEC, Evonik AG) 5.0
Cetearyl Ethylhexanoate (Tegosoft liquid, Evonik AG) 5.0
C12-15 Alkyl Benzoate (Tegosoft TN, Evonik AG) 5.0
Xanthan Gum 0.2
B. Respective TiO2 UV Filter 5.0
C. Water (Aqua) qs to 100.0
Glycerin 3.0
D. Carbomer (Tego Carbomer 141, Evonik AG) 0.2
Mineral Oil  0.8
E. Sodium Hydroxide 0.5
Phenoxyethanol (and) Ethylhexylglycerin 1.0
Procedure: Heat A to approx 80–85°C. Add B to A. Disperse for 2 min. Add C to AB without stirring. Homogenize. Cool with gentle stirring and add D below 40°C. Add E in order.

 

          

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