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| High Solids® and High SpeedTM Dispersions |
| Kobo Dispersion Technologies |
| Attenuation grades of titanium dioxide or zinc oxide are dispersed to achieve the highest possible percent solids and then milled to a specific particle size. These dispersions provide high transparency and SPF or yield an optimal efficacy against both UVA and / or UVB. Pigmentary grades of iron oxides, titanium dioxide, organic and other pigments are dispersed for full color development and ease of use. |
| .... Presentation slide show |
| TiO2 Attenuation Grade Dispersions |
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As a sunscreen agent, attenuation grade titanium dioxide with much smaller
primary particle sizes than pigmentary grade
TiO2 must be used
to minimize skin whitening. These very small primary particles tend to aggregate more than
ten fold and powders supplied frequently contain aggregates over one micron.
Therefore, proper grinding is necessary.
With optimal grinding conditions, smaller primary particle (10-15nm) size
TiO2
always provides better transparency and UVB protection while
TiO2 of a larger primary
particle (35nm) size will give a better UVA protection. Therefore, the selection of
TiO2 will be based on the
SPF and PFA values intended for the finished formula, as well as use level. Surface activity of attenuation grade TiO2, either its photo-catalytic activity or chemical activity towards other ingredients like vitamin C and Avobenzone in the formula, must be considered. Larger size TiO2 has a smaller surface area and also can be readily coated, making the particle very stable. Surface treating micronized TiO2 has been show to make it less reactive. Kobo offers High SpeedTM Dispersions, fluid and ultrafine dispersions for higher UV protection and easier use. |
| View List of Recommended Attenuation Grade TiO2 Dispersions and Download Specs & MSDSs |
| ZnO Attenuation Grade Dispersions |
| Zinc Oxide is used in cosmetics primarily as a skin protectant and for UV attenuation. They are grades of different primary particle sizes available between 25 and 120 nanometers. The degree of aggregation is a function of the primary particle size and manufacturing process, similar to the case with TiO2. When properly ground, the ZnO with smaller primary particle will give better transparency and better attenuation of both UVA and UVB. However, due to its low refractive index, the whitening of ZnO is less of a concern, especially when the use level is under four percent. In in-vitro studies, larger size ZnO was found to score a higher critical wavelength than finer ZnO but gives lower PFA when tested in-vivo. This is a great concern in the USA where a PFA testing method has yet to be officially adopted. |
| View List of Recommended Attenuation Grade ZnO Dispersions and Download Specs & MSDSs |
| Pigmentary Grade Dispersions |
| Pigmentary grade titanium dioxides and iron oxides (red, yellow & black) are widely used for color cosmetics and have primary particle sizes greater than 0.2 microns. Pigmentary grade pigments also tend to aggregate in formulas. Color strength, gloss and opacity are related to the particle size of the aggregates. Theoretically, the color intensity is highest (or most opacity) is obtained when the dispersion particle size (in formulas) is closest to their primary particle size. Organic lakes dispersions are also available. |
| View List of Recommended Pigmentary Grade Dispersions and Download Specs & MSDSs |