| Summary: | 碩士 === 嘉南藥理科技大學 === 化妝品科技研究所 === 96 === Due to the reduction of ozone layer, the increasing risk of human skin exposed to the sunlight had led to the development of suncreams both with high sun protection efficacy and less irritancy on the skin.This study was performed in order to reach such a suncream. For the study, the surfactants, the mixture of Span80 with Tween40, are selected as emulsifiers; they have been used in wide range of HLB(Hydrophile-Lipophile Balance) from 6.56 to 13.34. And some approved sunscreen agents like PMCX(Octyl Methoxy Cinnamate), P1789 (4-Tert-Butyl Methoxy Dibenzoyl Methane), Octocrylene, and Titanium Dioxide, as a different single one and a combination of two or more filters, are incorporated into the emulsion containing the mixed emulsifiers (Span80/ Tween40) during the production.
It is well-known that emulsion properties depend not only on physicochemical variables (nature of components composition and temperature) but also formulation methods the order of addition of the components. A suitable mixed emulsifiers is needed to obtain optimum suncreams and the suncreams are characterized by rheological measurement, partical size and distribution and stability tests. On the other hand, the effectiveness of the suncreams is determined instrumentally by in vitro SPF method.
From the results obtained, it was found that stability of the sunscreams was depent on some factors such as the HLB value of the mixed emulsifiers, different kinds of sunscreen agents, and thickeners. By selecting the right mixed emulsifiers and controlling the amounts and combinations of the emulsions constituents, the optimum formula of the sunscream with good storage stability have been attained. When the mixed emulsifiers is with 8.82 of HLB and Carbopol 940 is used as a thickener, the suncreams obtained have a good stability even in the presence of chemical sunscreen agents, but not in the presence of physical sunscreen agents. Instead of Carbopol 940, Carbopol 1342 can be used as a thickener to obtain better stability when titanium dioxide is included in the suncreams. In addition, it was also found that high viscosity and small droplet size favor stability because the rate of creaming is reduced.
The in vitro testing results show that the SPF effectiveness increases with the increase in amounts of sunscreen agents incorporated into emulsions. The relationship between SPF value and the concentiation of sunscreen agent used is linear.The correlation coeffient of linear regression were with the range 0.985~0.995. Importantly, a right combination of sunscreen filters makes it possible to attain suncreams with high SPF value and to result in synergistic effect on the sun protect efficacy. Therefore, when sunscreams are formulated it is important for optimizing them to consider formulation parameter and each composition .
Based on these findings , a desired formulation has been obtained . With high SPF of 49.89 and reasonable stability , it is composed of PMCX 10 , P1789 3 ,Octocrylene 10, TiO2 2, Span 80 3, Tween 40 2, IPP 5, Finsolv TN 6, Squalane 4,P.G 5, Germaben II 0.8, Carbopol 1342 0.3, and deioned water to 100g.
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