Lack of water in the stratum corneum results in dry and scaly skin. Skin hydration is an important function of cosmetic skincare products. It is important for skin hydration to hold water to the stratum corneum and to prevent the evaporation of water from the skin surface. The physico-chemical properties of a skin care base are closely related to these mechanisms, and a suitable formulation design leads to an excellent skin moisturizing effect. Humectants in those formulations play the most important role in the skin moisturizing effect. The skin-moisturizing effect of a humectant depends on the amount of adsorbed humectant in the stratum corneum. In order to enhance the penetration into the stratum corneum, the technique of blending with an aqueous phase an ingredient which raises distribution to the stratum corneum of a humectant is effective. In addition, α-gel emulsion can express a moisturizing effect with a small amount applied. A film of a hydrophobic ingredient such as hydrocarbon oil can prevent moisture evaporation from skin, and can hold moisture on the skin surface. Although the occlusion effect increases with an increase of the molecular weight of oil, it is important that the application film on the skin is homogeneous. As a new formulation technology having the occlusion effect and the penetration of a moisturizer, nanoemulsion of α-gel emulsion is introduced. In addition to these conventional techniques, new knowledge on restoration of the intercellular lipid structure in the stratum corneum is also discussed.

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Dextrin fatty acid esters are used for cosmetic ingredients as organic gelators or stabilizers of emulsions. The acyl group of dextrin fatty acid esters is properly selected according to the characteristic of oils. However, the organogel formation of dextrin fatty acid esters still remains to be characterized. The behavior and properties of the organogels have been studied through rheology, Transmission Electron Microscopy (TEM), Differential Scanning Calorimetry (DSC), and Synchrotron Radiation X-Ray Scattering with ultra small-angle X-ray Scattering (USAXS) and normal small-angle X-ray Scattering (n-SAXS). Dextrin palmitate (DP) was used at various concentrations between 1 and 30 wt% in the presence of Liquid Paraffin (LP). DP above 5 wt% formed viscous organogels in the presence of LP. It was found that organogels are not the structure of entangled polymer network seen in a typical polymer solution, since the results of rheology measurements were not in line with the Cox-Merz rule. TEM revealed the presence of aggregates of colloidal particles below about 1 μm in size. n-SAXS and USAXS confirmed the presence of lamellae in both the sol and gel state; however, the results of the rheological measurements showed that organogels weren't in the lamellar phase in this system. SAXS (including USAXS and n-SAXS) and viscosity measurements were simultaneously performed on organogels of 10 wt% DP, at different shear rates in the 0 and 100 s^-1. A Shear Induced (100 s^-1) USAXS pattern revealed anisotropy in the meridian direction, but the n-SAXS pattern did not change the lamellar rings. When rearranging the experimental results, it was proved that organogels are the aggregation of sheet structures with the lamellae composed of DP.

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A variety of twists and ideas in the fields of design, color and forming have been given to the formulation of make-up products and cosmetics packages to raise a sense of expectation for efficacy in consumers. However, few of such twists and ideas have been given to the formulation of skin care products. Therefore, we tried to develop and give skin care formulation an attractive appearance, aiming for consumers to have an impression that “my skin might improve as I want.” Firstly, a consumer survey was conducted focusing on the relationship between “appearance of formulation” and “the sense of expectation for efficacy” in skin care products. It was verified that consumers evoked different senses of expectation for efficacy toward the lotion formulations with different appearances, and that they could not evoke the sense of expectation for the improvement of skin radiance toward the lotions with conventional appearances. To solve this issue, we have successfully developed the lotion formulation with a luminous appearance like an aurora by the application of the light interference property of lamellar liquid crystal composed of surfactants, and verified that the prototype lotion did evoke the sense of expectation for the improvement of skin radiance in the consumers. We have found that appropriately fitting the appearance of formulation and the sense of expectation for efficacy could possibly lead consumers to the proper use of products, and could enhance the actual skin care effects.

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The key technology for hair-treatment products and hair-coloring products controls the permeability of product components into human hair to express their function effectively. It is necessary to obtain inside information about targeted human hair accurately for efficient pharmaceutical development, and to establish measurement methods for analyzing the permeability of product components into human hair directly and simply. We have evaluated the distribution of chemical composition (amide chemical-bond and CH chemical-bond) of the human hair cross section using infrared microspectroscopy and reported that the localization of product components was confirmed. In this study, we were able to obtain more detailed composition data on the human hair cross section than in previous reports as a result of changes in the optical system of SPring-8 BL43IR. Consequently, image mapping of amide chemical-bond provides a clearer outline of human hair than ever before, showing composition changes to protein inside the hair due to chemical damage. We aim to utilize this method more universally by further confirming the range of the targeted human hair for which this analytical method is applicable and by attempting to reduce measurement time.

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We have developed new methods to quantify cleansing oil's sensation of use by instrumental analysis. Firstly, a sensory evaluation was examined to identify the important sensation of use in the continuous movement when using cleansing oil. The result was then analyzed by principal component analysis. Based on the result, we secondly quantified “Spreadability” and “Stickiness after wash,” which showed higher principal component loadings. To evaluate the “Spreadability,” we measured the torque when a ball-jig slid on an artificial skin to apply the sample, with a dynamic viscoelasticity measuring device. To evaluate the “Stickiness after wash,” we measured the adhesion energy when separating a stage to which a sample had been applied and then washed off from a plunger with a creep meter. As a consequence, we have confirmed a correlation between the physical properties values and the sensory evaluation scores. This means we are now able to evaluate the important sensation of use regarding cleansing oil objectively and pluralistically. It will be useful for the future product development.

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Eye bags are cosmetically undesirable as they cast a shadow under the eyes. Accurate evaluation of efficacy of cosmetics to treat this problem is difficult with two-dimensional techniques using photographs and images as eye images are easily affected by the illumination conditions. In the present study we aimed to elucidate eye shape characteristics that have an influence on the impression of the eyes. We focused on the surface curvatures that express curve condition of the local curved surface in three-dimensional shape data and examined the relation between the surface curvatures and the impression of the eyes at every site. The relation between the surface curvatures of the eyes and the apparent age of test subjects suggested a correlation in eye bags and sulcus palpebromalaris. From this result we consider that a highly precise objective evaluation of eye impression is possible by using the surface curvatures of eye bags and sulcus palpebromalaris as an evaluation value.

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