Formulating High SPF Sun Care Products With A - External Factor ...

SUN CARE
LIQUID-MINERAL UV FILTER
The inclusion of 3% Polysilicone-15 raises
the SPF from 18 to 30 (A and B) and
from 38 to 53 (C and D). This data are in
line with many other experiments where
it was found, that Polysilicone-15 exerts
synergistic effects when combined with
4-Methylbenzylidene Camphor (MBC),
Phenylbenzimidazol Sulfonic Acid (PBSA)
(19), Titanium Dioxide (TiO2). A possible explanation for these synergistic
effects can be found
1. In the film forming properties of Polysilicone-15
2. Reduction of the aggregation of the
traditional UV-filters
3. Reduction of the agglomeration of
pigments
and thus supporting a better distribution
of traditional UV-filters on the skin surface
(Fig. 7).
Thus, Polysilicone-15 can be used to exploit
more efficiently the UV-absorbing
potential of the traditional UV-filters.
Low performance of Polysilicone-15
in combination with EHMC
Table 3 shows the unexpectedly low in
vivo SPF results if EHMC is combined
with Polysilicone-15. If EHMC is added
to a standard sun care formulation with
SPF 30 containing 3.0% Polysilicone-15
the in vivo SPF decreased to 25. This initially
surprising result can be caused by
significant π-π interactions of the aromatic
chromophoric systems (14). This interactions
result from the similar structural
features of the benzalmalonate chromophore
and the EHMC chromophore
leading to a energetically favored aggregation.
As is known and has been discussed
above, these interactions reduce
the sun protection activity. Thus, it is not
recommended to combine Polysilicone-
15 with EHMC.
� Further unique characteristics
of Polysilicone-15
With the structure of Polysilicone-15 given,
some unique characteristics are implied
which can not be found with other
UV-filters, and which give additional
benefits for the products and the consumers.
Improved Sensorial Profile
Having a polysiloxane backbone in the
molecule, Polysilicone-15 exerts a silicone-like
feeling when applied on the
skin, especially compared to traditional
mineral UV-filters. This new technology
UV-filter shows specific advantages in
the sensorial profile and the reduced
residual whitening of the skin. To prove
this advantages two similar sun care formulations
were created (composition see
Table 4). Formulation A contained 6%
TiO 2 . In formulation B 3% of the TiO 2 was
replaced by 3% Polysilicone-15. Both
formulation achieved a comparable SPF
of 27 (A), respectively 28 (B). The replacement
of TiO 2 by Polysilicone-15 had
a considerable influence on the sensorial
profile. The two formulations were analyzed
at an external test institute where
12 trained panellists quantified the sen-
sorial profile of both formulations. Fig. 8
shows the parameters where the most
important differences were measured. It
can be seen that the speed of absorption,
the coolness, the melting and the ease of
spreading were almost all significantly
better for the formulation containing
Polysilicone-15. The whitening during and
after spreading was significantly reduced
when 3% TiO 2 was replaced by 3% Polysilicone-15.
The formulation containing
Polysilicone-15 exerts the same protection
of the skin as TiO 2 , but provides a
formulation with a much better sensorial
profile.
Increased consumer protection
The same two formulations as described
above were used for the following consumer
test at an external test institute:
Fig. 7 Synergistic effect of Polysilicone-15 in combination with other UV-filter
Fig. 8 Sensorial test: Comparison of application characteristics of a sun care
formulation with and without 3% Polysilicone-15
score
14
6 SÖFW-Journal | 131 | 7-2005