Vol.3 No.2 2010

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Research paper : Products and evaluation device of cosmetics for UV protection (Y. Takao et al.)−146−Synthesiology - English edition Vol.3 No.2 (2010) (boron nitride), hollow or solid grain of titania nanoparticles, and swelling grain that can include and discharge water can be fabricated[1][21].The above morphological control can be conducted by appropriate selection of the control elements in the solid, liquid, and gas phase methods described in chapters 2 and 3, such as the parallel use of static hetero-aggregation and homo-repulsion in the solution and the particle packing model[1][2][14]-[21].Figure 10 shows the result of achieving both the UV protection and transparency as material characteristics. In the current product shown in Fig. 10(b), the light transmissivity does not decrease in the UV range of about 400 nm or less. Not only is the blocking of UV insufficient, but also the transmissivity drops exceedingly in the visible light range of 400 nm or over, and this decreases the transparency. On the other hand, in the product developed by the composite particle method in Fig. 10(a), the decrease in low transmissivity of the UV range to achieve high blocking capability and the decrease in transmissivity in the visible light range were controlled to achieve the high transparency as shown in Fig. 10(c)[1]. For the three issues of cosmetics - (1) UV protection, (2) transparency, and (3) texture - the (1) high blocking of UV only and (2) high visible light transmissivity were achieved. One of the reasons for realizing the specific blocking of the UV range only was because the controllability of color tone improved due to the prevention of segregation between the planar ceramic unit particle (sericite) of nanoparticles, and the particles could be arranged with “controlled anisotropy” on the top or edge of the surface of the material particle[21].4.2 Quantification of lubriciousness and good texture-feel achieved simultaneouslyFigure 11 shows the graph of the normal and side-grinding forces evaluated by the LS approximation model shown in Fig. 5 and 8, for the (3) high lubriciousness, the remaining technological element of the UV-protective cosmetics. The current product shown in Fig. 11(b) has poor texture-feel due to the increased gradient of the normal and side-grinding forces, or the angle of internal friction, compared to the raw material unit shown in Fig. 11(c). In the developed product in Fig. 11(a), the internal friction angle is reduced to achieve high lubriciousness or good texture-feel.One of the reasons for good texture-feel was the realization of the extremely small amount of sericite and nanoparticles used due to the controlled segregation of nanoparticles among the sericite, as they were deposited only on the surface of the material powder.The effect of controlling the excessive use of the material corresponds to the reduction or resource-saving of 3R (reduce, reuse, and recycle), and presents the contribution to the mission of the Materials Research Institute for Sustainable Development: “to promote innovation and effective use of resource for the development of materials that enable sustainable development”[1][2][14]-[21].Fig. 10 Technological result: Achievement of both UV protection and visible light transmissivity(a) Developed composite particle: Corresponds to static friction and reproduces the consolidation state in the hopper (ideal condition).(b) Product of other company: UV protectiveness increases but transmissivity (transparency) decreases due to the aggregation of nanoparticles, and the face may look “powdery”.(c) Raw material mica powder: Transmissivity of visible light (transparency) is high but has no UV protection function.Transmissivity (%)Wavelength (nm)Developed composite particleProduct of other companyRaw material, mica790690590490390290100806040200(a)(b)(c)(c)(a)(b)Fig. 11 Technological result: In addition to the optical property (Fig. 10), quantifications of lubriciousness and good texture-feel (skin-touch) are both achieved(a) Developed composite particle: Angle of internal friction is minimum value.(b) Product of other company: UV protection function increases, but lubriciousness or texture-feel decreases due to nanoparticle aggregation, and angle of internal friction increases.(c) Angle of internal friction of the mica particle (median of the two composites).Shear force (N/cm2)Normal stress (N/cm2)Developed composite particleProduct of other companyRaw material, mica2515105453212000(a)(b)(c)(c)(a)(b)

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