Coated powders having high photostability
A coating, powder technology, applied in the field of coated powder with high photostability, can solve the problem of compromising antioxidant stability and efficacy
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Embodiment 1
[0093] The above-mentioned TiO can be used 2 Light Stability Test to measure the improved light stability of coated powders. In this test, the pass condition is ΔE≤15 based on experience with spectrophotometric testing including selected antioxidants and ESR-based methods. The data in Table 1 below is based on a constant 40m 2 / g (35nm) rutile TiO 2 particles. Since the coating surface coverage is based on surface area, the mass fraction of coating components should be scaled to the specific surface area of the base particles. Modeling the response shows that the pass / fail condition shifts when A+B exceeds 2.5% for the following cases. Since in this case the common base particle is 40m 2 / g, pass / fail boundary expressed as 0.0625% / m for all particle types 2 / g. As shown in Table 1 below, ΔE≤15 for all compliant compositions.
[0094] Table 1: Light Stability Test Results
[0095]
[0096] Since the coating consists only of residual cross-linked polymer, the coati...
Embodiment 2
[0098] W / O formulations containing a physical UV filter (150 nm zinc oxide) were analyzed for the amount of UV-inducible free radicals using the following radical potential (RP) method.
[0099] The semi-stable spin probe PCA (2,2,5,5-tetramethylpyrrolidine N-oxy) was added to the test product, the sample was inserted into the capillary quartz tube, and before a defined dose of UV radiation and The concentration of the spin label was then monitored by ESR spectroscopy. The PCA spin probe is photostable and resistant to antioxidants, but it reacts rapidly with UV-generated free radicals (mainly lipid peroxides and lipid free radicals) inside the sample. The amount of UV-generated free radicals can be quantitatively detected from the calibration curve.
[0100] Materials and Methods
[0101] A water / EtOH solution of spin trap (PCA) was added to the W / O emulsion to obtain a final concentration of 0.01 mM PCA. Samples were inserted into ESR capillary quartz tubes (40 μL) before...
Embodiment 3
[0111] In the proposed test design, different photolabile antioxidants have been added to formulations containing ZnO with different coating techniques. The antioxidant activity of these formulations was determined using the AP method before and after UV irradiation of the formulations.
[0112] Antioxidants have been selected according to the following criteria: (1) the antioxidants used are suitable for use in cosmetic formulations, and (2) the 5 raw materials represent different classes of antioxidants with different molecular mechanisms, hydrophilic and lipophilic characteristics. The final concentration of each antioxidant is selected based on the antioxidant capacity of the raw materials. Based on EU guidelines, all concentrations were kept within the recommended ranges.
[0113] Antioxidants are oxidized when exposed to UV radiation, resulting in a decrease in antioxidant capacity (AP). Table 4 below shows the decrease in AP upon exposure to UV radiation. Information...
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