Page 552 - Book Hosokawa Nanoparticle Technology Handbook

APPLICATIONS 25 DEVELOPMENT OF NEW COSMETICS BASED ON NANOPARTICLES
hydrophilic or hydrophobic groups, or to introduce 2. Use as compound particles
alkyl groups thereby enhancing the dispersion in oil
of the pigment and preparing lipsticks with strong (1) Color correction
hues. Further, by introducing glycerin residue, dual- Structural colors that give out color due to interfer-
purpose foundations having moisture retentivity that ence of light such as the colors in the wings of a but-
can be used both with and without water [12] have terfly are being used actively. It has been known that
been developed. blue moles or red moles such as nevus of Ota or vas-
cular neoplasm disappear giving a natural appear-
ance by the use of titanium dioxide coated mica
having interference color. However, since titanium
dioxide coated mica has gloss, it gives an unnatural
finish when used in a foundation. In order to
improve its shine, a compound particle was devel-
oped with the surface of titanium dioxide coated
mica covered with spherical particle of PMMA
(Fig. 25.5). While correcting the reflectivity of red
color using its red interference color, since the gloss
of titanium dioxide coated mica is controlled by the
diffused reflection of spherical PMMA particles, it
was possible to realize a fine makeup skin texture
having transparency as well.
An example of skin color correction using fluo-
rescence is reduced form of zinc oxide. The reflec-
500 nm tivity about 500 nm is increased due to the
500 nm
ultraviolet light present in sunlight or fluorescent
light thereby attempting to correct the reflectivity of
light in the blue to green region [13]. There are
Figure 25.3 items in which the reflectivity on the long wave-
An electron microscope photograph of flower petal shaped length side is increased using the fluorescence of
zinc oxide. carthamin.

Chemical vapor deposition

Particle Particle Particle
Cross-linking
polymerization Additional
reaction

Functional groups

Tetramethyl cyclo Networked methyl polysiloxane
tetrasiloxane

Figure 25.4
Schematic diagram of functional nanocoating.

524