Factors to control the alignment of surface-treated titanium dioxide powders to maximize performance of sunscreens / Shoji Takekawa in INTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Vol. 45, N° 1 (02/2023)  

[article]  inINTERNATIONAL JOURNAL OF COSMETIC SCIENCE > Vol. 45, N° 1 (02/2023) . - p. 38-49 Titre : Factors to control the alignment of surface-treated titanium dioxide powders to maximize performance of sunscreens Type de document : document électronique Auteurs : Shoji Takekawa, Auteur ; Miwa Ohara, Auteur ; Taisuke Banno, Auteur ; Kouichi Asakura, Auteur Année de publication : 2023 Article en page(s) : p. 38-49 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Analyse spectrale Barrière cutanée Cosmétiques Dioxyde de titane Evaluation Formulation (génie chimique) -- Stabilité Peau -- Soins et hygiène Produits antisolaires Traîtements de surface Index. décimale : 668.5 Parfums et cosmétiques Résumé : - Objective : Titanium dioxide powders are contained in a large class of colour cosmetics and sunscreen formulas. When they are used, the formation of a uniform functional powder layer on the skin is an important factor to show their functionality, such as aesthetic and UV protection. Attempts were made to extract the factors that affect the UV shielding ability of the deposited powder layer. - Methods : Seven kinds of surface treatments were conducted on nano-sized titanium dioxide powder to modify the surface characteristics. Dispersion samples were prepared by mixing these powders with liquids, such as mixed solutions of cyclopentasiloxane, isododecane, coconuts alkane and dimethicone using a disperser and a bead mill. The dispersions were applied using an applicator on cellulose triacetate film, polycarbonate film and polymethyl pentene film. Laser microscope observation and micro-gloss glossmeter analysis were carried out to assess the flatness of the deposited powder layers, and the UV shielding ability was evaluated using SPF analyser. - Results : Factors whose influences on the structure and UV shielding ability of the deposited powder layer being analysed were pseudo-HLB of the powders, liquids for preparing the dispersions and material of the substrates. Higher UV shielding ability was attained when powders having pseudo-HLB at around 6 were employed independent from the kinds of liquids and substrates. Flatness of the deposited layer was found to enhance the UV shielding ability of the UV-B region, while that of the UV-A region was scarcely influenced by the flatness. Employing lower surface tension liquids for preparing the dispersions and materials exhibiting lower polar components of surface free energy as substrates tended to enhance the UV shielding ability. - Conclusion : Surface treatments conducted on the powders in this study were found to change UV shielding ability, especially UV-B shielding ability, and the relation between pseudo-HLB and UV shielding ability was scarcely influenced by the kinds of liquids. Both surface tension of liquids and the polar component of surface free energy of substrates affected the UV shielding ability. It was suggested that pseudo-HLB calculated based on chemical structure becomes useful information to choose optimum surface treatment to make uniform powder alignment independent from the surrounding environment. Note de contenu : - MATERIAL AND METHODS : Surface treatment - Preparation of dispersions and their application onto substrates - Evaluation of surface tension of liquids and surface free energy of each film - Characterization of UV shielding ability and surface structure of the applied layer - RESULTS AND DISCUSSION : Surface tension of mixed solutions and surface free energy of each film - Effect of surface tension of mixed solutions of D5 and ID on the UV shielding ability - Effect of cosmetic oils for the mixed solutions on the UV shielding ability - Effect of substrates on the UV shielding ability - Table 1 : Preparation of three types of mixed solution, II, III and IV, containing cosmetic oils, DM and CA, having the surface tension approximately at 20 mN/m, i.e. the surface tension of mixed solution of D5 and ID whose weight ratio is 0.50:0.50 (mixed solution I) - Table 2 : Mean contact angle of water and diiodomethane on the three kinds of films, mean temperature and mean three-phase point to evaluate surface free energy of each film and the dispersive and polar components - Table 3 : Surface free energy of CTA, PC and PMP film and the dispersive and polar components - Table 4 : Seven treated titanium dioxide powder samples employed for the experiments - Table 5 : 45-degree gloss value of deposited seven types of surface-treated titanium dioxide layer formed on CTA film DOI : https://doi.org/10.1111/ics.12816 En ligne : https://drive.google.com/file/d/1Dojnru5MAVRhG8HWAghnCSv5en47h7nv/view?usp=share [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=38818 [article]

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