When looking to prevent Infrared induced aging, Infraveil™ IT-100 is the answer. Infraveil ™ IT-100 is a physical shield that delivers instant skin protection from Infrared-A(IRA) rays. Infraveil™ IT-100 is based on patented dispersion technology which ensures that, despite the large particle size, it has minimal whitening on skin.
Particle and Dispersion Design
In designing an active that will act as a physical shield to protect against these damaging IRA rays, it was necessary to determine the ideal particle size for IRA Protection. Robb et al., utilised a computer program called ‘Mie theory’ to investigate TiO2 hard spheres1.
Mie theory predicts that as particle size is increased the scattering light is shifted to longer wavelenghts. From this theory it is observed that UV light is best scattered by particles of around 150nm in size and TiO2 pigment particles of 250nm diameter are very efficient at scattering visible light.
Croda has applied this theory to ascertain the optimal particle size for Infraveil IT-100. Figure 1 shows this theory and the prediction that a particle of approximately 1000nm size will offer the required IRA scattering.
Croda has applied it is Solaveil™ expertise in the design of InfraveilTM IT-100 dispersion. By controlling the particle size distrubution, it is possible to minimise the number of particles that scatter light in the visible region.
Croda’s technology also ensures the performance of the optimised particle carries through into final formulation. Dispersing the particle using Croda’s patented process maximises Performance and ensures that Infraveil™ IT-100 does not appear white on the skin, despite it is large particle size.
Appearance on Skin
Despite its large particle size, Infraveil™ IT-100 gives minimal whitening on skin compared to Solaveil XT-100. Infraveil IT-100 has also been compared to a pigmentary grade of TiO2 which is also a larger particle sizle TiO2. A prototype formulation containing 5% active TiO2 was prepared and applied to subjects at a level of 1.3mg/cm2. After applying the formulation, the subjects were instructed to rub the sample is until it was fully Absorbed. The skin was then left for 5 minutes before images were taken. Examples are shown in Figure 2 on a range of different skin prototypes.
Independent Validation
To further substantiate the IR shielding effect of Infraveil™ IT-100 independent testing was conducted. HelioScreen Labs (France) have developed an in-vitro method to offer the industy a framework for IR Protection claim substantiation. To achieve IR protection efficacy the criteria outlined in Table 1 must be met. % IRA and % IRB refer to the percentage of IR radiation blocked by sample. IRA-CW and IRB-CW refer to the Critical Wavelength and indicates the balance between UV, visible and IR radiation.
In this study three formulations were compared. A formulation containing Infraveil™ IT-100 alone, a formulation based on UV filters alone (Solaveil Spextra and Claurus), and a formulation based on UV filters in combination with Infraveil™ IT-100. All actives were included at 5% active.
The results from these independent assessment show that formulations containing Infraveil IT-100 demostrate IR protection efficacy. Formulations based solely on UV filters do not meet the IR protection criteria, but if Infraveil IT-100 is added to those formulations, IR protection can be achieved.
Sena Yegin
Sales Representative
Croda Kimya Tic. Ltd. Şti.
