64 SUN CARE Solvent Magnification Solvent Only 10% BODP


C12-15 Alkyl Benzoate


10x


Octyldodecanol


10x Figure 1: Optical microscope image of uncoated TiO2


particles also appear to be much more ordered when BODP is included in the solution. To test the effect of BODP on the pigment , solutions of 0, 1, 5 and 10% BODP


load of TiO2


were prepared in C12-15 alkyl benzoate. The solution was stirred by an overhead mixer and the pigment load was defined as the amount of pigment that rendered the solution to viscus to stir. The pigment loads are shown in Table 1. As seen in Table 1, the pigment load was


increased from 20% to 67% wt/wt but the incorporation of 10% BODP in C12-15 alkyl benzoate. Furthermore, the pigment load of TiO2 in octyldodecanol was increased from 50% wt/wt to 67% wt/wt with the incorporation of 10% BODP. As seen in Figure 2, the two dispersions are


very different. The dispersion of non-coated ZnO in C12-15 alkyl benzonate have a large amount of agglomeration. Large agglomeration or flocculation leads to a higher viscosity and more whitening when applied to the skin. The dispersion with 5% BODP, on the other hand, has much lower degree of agglomeration, leading to a lower viscosity and less whitening of the dispersion when applied to the skin.


Formulation of emulsion To test the film forming capabilities of BODP, an emulsion was prepared as seen in Table 3, both


Solvent BODP ZnO and TiO2 in C12 – C15 Alkyl Benzoate and octyldodecanol


TABLE 1: PIGMENT LOAD OF TIO2 ALKYL BENZOATE


0% INC12-15


C12-15 Alkyl Benzoate 1%


5% 10% Pigment Load 20% 39% 53% 67% are utilized as the actives of the formulation. The target SPF of formulation was 30.


In vivo SPF To test the SPF of the formulation, a three- subject in vivo SPF test was conducted at Advanced Science Laboratories Inc. The results of the in vivo test are shown in Table 3. As seen from the Table 3, the static SPF


was determined to be 39.9, and the SPF of the formulation after the water immersion was shown to be 31.0. In order to be considered water resistant, the SPF needs to retain at least 50% of its static SPF value after 80 minutes in a water bath.20,21


This result shows that the


formulation is considered to be very water resistant (VWR).


Application on wet skin ZnO particles have a tendency of agglomerating when the particles encounter water. Chen


Magnification Solvent Only


et al found that ZnO nanoparticles easy agglomerate and deteriorating a dispersion in ZnO composites.22


This leads to difficulty when


trying to apply sunscreen products when your skin is wet.


When the formulation is applied to skin that


has water on it, the particles agglomerate and become very difficult to spread evenly onto the skin. To test how coating the particles with BODP effects the spread on wet skin, a simple test was conducted. First, a forearm was wet with a spray bottle


containing tap water. Approximately 1.00 g of test product was applied to the forearm with a scoopula. The product was then rubbed into the skin for two minutes. Optical pictures are shown in Figure 3. As seen in Figure 3, the commercial product


containing ZnO became extremely white when applied to the skin. Along with the whitening, the formulation became very difficult to spread evenly on the skin. On the other hand, the formulation containing BODP had a drastically improved spread profile on the skin and showed minimal whitening. While these two tester formulations were not exactly the same, this simple test demonstrates that BODP can be used to prevent the particles from agglomerating in the presence of water.


5% BODP


C8-10


Triglyceride


10x Figure 2: Optical microscope image of uncoated ZnO in C12 – C15 Alkyl Benzoate and octyldodecanol PERSONAL CARE May 2023 www.personalcaremagazine.com


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88  |  Page 89  |  Page 90  |  Page 91  |  Page 92  |  Page 93  |  Page 94  |  Page 95  |  Page 96  |  Page 97  |  Page 98  |  Page 99  |  Page 100  |  Page 101  |  Page 102  |  Page 103  |  Page 104  |  Page 105  |  Page 106  |  Page 107  |  Page 108  |  Page 109  |  Page 110  |  Page 111  |  Page 112  |  Page 113  |  Page 114  |  Page 115  |  Page 116  |  Page 117  |  Page 118  |  Page 119