Conditioning Agents for Hair and Skin

218 O'LenIck
irritating to the eyes when evaluated by FHSLS 16 CFR 1500.41 for primary
eye irritation, giving values of zero. They are nontoxic when evaluated by FHSLS
16 CFR 1500.41 for acute oral toxicity, having LD50 values above 5 g^g. They
are also noncomedogenic when evaluated using a standard comedogenicity
assay. This profile suggests that these materials are outstanding candidates for
personal care applications.
b. SPFEnhancement. Dimethiconecopolyol phosphate has been demonstrated
to boost the SPF of chemical sunscreens by as much as 47%, and nonchemical
or pigmented sunscreen systems by as much as 17% (23). It has been
postulated that the superior wetting properties of the dimethicone copolyol
phosphate allows the sunscreening materials to cover the skin more efficiently,
in a thinner, more uniform film.
c. Typical Formulations. Silicone phosphate esters find applications in
a variety of personal care products. Their properties as outlined above
make them excellent additives for hair care, skin care, and other personal care
applications.
K. Other Silicone Esters
1. Structure/Background
Two new classes of silicone based esters have recently been prepared. The first
class of materials is prepared by the esterification reaction of a dimethiconol
and a fatty acid (24). These dimethiconol esters contain both a fatty group and
a silicone polymer group. They conform to the following structure:
Me Me Me
I I I
CHj(CH2),-C(0)-0~Si—0-(-Si—O).—SI-0-C(OHCH2)iCH3
I I I
Me Me Me
The second class results from the reaction of a dimethicone copolyol with
a fatty acid (25). The dimethicone copolyol group initially contains a silicone
group and a polyoxyethylene group. The incorporation of the fatty group by
the esterification reaction results in a product that has a water-soluble, a silicone-soluble,
and a fatty-soluble group present in one molecule. This class of
compounds conforms to the following structure: