Monoalkyl phosphates (MAPs) and other various anionic surfactants were evaluated as skin cleansers from the viewpoints of both dermatology and interface science. Of the surfactants examined, it was found that monosodium monolauryl phosphate (C₁₂MAP1Na) exhibited a considerably higy safety on the human skin because of neutral pH, low skin irritation and small elution amount of natural moisturizing factors such as amino acids from the stratum corneum. These characteristics of C₁₂MAP1Na contribute to low skin roughness. In addition, C₁₂MAP1Na showed excellent foaming and sebum removal properties in comparison with typical anionic surfactants such as alkyl sulfates and soaps.
On the basis of these results, a new type of skin cleanser mainly composed of C₁₂MAP1Na was developed. The striking characteristic of this skin cleanser formula is the stable system which in the fine crystals of C₁₂MAP1Na are homogeneously dispersed with the presence of larger amount of inorganic salt. It was confirmed by the use test that the skin cleanser not only had a good foaming power but gave a good feeling to the skin and relatively fast recovery to casual pH level on the skin after washing face.
Thus, since MAPs were found to be innovative surfactants, it expected that they will be useful for a wider range of application including skin cleansers.

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Decomposition of isopropanol over inorganic pigments was measured by a microcatalytic reactor. The decomposed products of isopropanol suggested that pigments were able to be classified into the following four groups.
Group 1. The type of pigments which mainly produces propylene.
Group 2. What mainly produces acetone.
Group 3. What forms both acetone and propylene.
Group 4. What does not decompose isopropanol.
Through our present study on the decomposition mechanism of isopropanol, it was found that propylene was formed mainly at acidic sites, and acetone was formed mainly at basic sites on the pigments. Further investigation was made on the effect of alkali treatment of kaolinite which have acidic sites, and the dehydration of isopropanol over treated kaolinite was analyzed by Arrhenius equation. The results showed that the apparent activation energy became larger and the reaction proceeded unsatisfactorily, at the amount of sodium carbonate increased.

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Butyl P-hydroxybenzoate (BP), widely used as a preservative for foods, drugs, and cosmetics, has been known to easily bind to surfactant micelles, and it has been also pointed out that its antimicrobial activity is reduced in nonionic surfactant solution.
Therefore, the antimicrobial activity of BP in the colloidal system was studied in relation to its solubilization behavior by nonionic surfactant. The equilibrium dialysis technique was used to determine both the concentration of BP solubilized (bound) within surfactant micelles and that the free (unbound) state.
We found that the antimicrobial activity of BP in combination with various nonionic suractants differed according to the type of microorganisms. The concentration of free (unbound) BP contributed its antimicrobial activity against Candida albicans, while the total concentration of BP added to the system contributed its antimicrobial activity against Pseudomonas aeruginosa.
These phenomena were well related to the lowering of the cloud point of surfactant due to the addition of BP; the more hydophodic the added surfactant, the more the interaction between the polyoxyethylene chain of surfactant and BP.
The addition of glycols, inorganic salts, amino acids, or polar oils to this system, was found to change the antimicrobial activity of BP and the solubilized state. Owing to the salting-in effect, glycols were found to strengthen the antimicrobial activity of BP due to the increase of its free concentration and the raise of the cloud point of surfactant. However, inorganic salts or amino acids were found to decrease the antimicrobial activity of BP by reducing its free concentration and by lowering the cloud point of surfactant due to the salting-out effect.
On the other hand, the addition of some polar oils was found to decrease the antimicrobial activity of BP by reducing its free concentration, however raising the cloud point of surfactant. It is considered that the addition of polar oils contributes to move the solubilization locus of BP within surfactant micelles from the polyoxyethylene mantle to the hydrophobic core.

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A considerable amount of energy which is normally wasted in the commercial processing of cosmetic and pharmaceutical emulsions can be saved by using Low-Energy Emulsification (LEE) technique proposed by Lin (1). When correctly executed, the quality of emulsion prepared by LEE is virtually indistinguishable from that of emulsions manufactured by the conventional hot method (2).
By supplying energy only when and where it is needed, LEE often allows conservation of over 50% of the thermal energy normally expended in commercial processing. LEE application in high α range can, sometimes, completely eliminate the necessity for the time-consuming cooling operation and result in an increase of production efficiency of over 100% (3).
Further research on LEE revealed that one of the key variables which significantly affects the emulsion quality is the emulsification temperature as well as the temperature of the concentrate prior to simultaneous dilution and cooling. In some systems, a higher temperature favors formation of fine droplets; whereas in others, the opposite may be true. By a careful control of the temperature through the use of solubilization chart, the mean diameter of the emulsion droplets can be controlled to produce desired emulsion.
The result of this finding can be applied to manufacturing fine cosmetic emulsions with very little energy consumption and greatly improved efficiency

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New series of water-in-oil (w/o) type surface active agents are presented: N-(3-alkyloxy-2-hydroxypropyl)-alkanolamines and N-(3-alkyloyloxy-2-hydroxypropyl) alkanolamines.
The noticeable features of the new surfactants were found to consist particularly of superior emulsifying ability and dispersing power. Their relatively higher HLB values (average: 6-7) and water numbers (20-30) compared with those of conventional w/o surfactants and the participation of a nitrogen atom present in the hydrophilic group seemed to account for these properties.
Of the new surfactants, those that possess unsaturated bond (s) in lipophilic chain constituted one of classes capable of formation of stable w/o emulsions. The dynamic behavior of these substances and their model compounds in reversed micellar state was characterized by ¹³C-NMR to find an explanation for their distinctive nature. Measurement of ¹³C spin-lattice relaxation times (T₁′s) demonstrated that the segmental motion around the doublebonded carbons in lipophilic group was rather restricted and that the mobility of carbons at hydprohilic position was also extremely reduced. The results suggested that the mobility of surfactant molecules may correlate with the stability of w/o emulsions. In addition, it was elucidated that neither the presence of double bond (s) nor the peculiar cis-configuration is a principal factor involved in the occurrence of such superior properties with which oleyl system, for instance, is provided.
Utilizing the new surface active agents, we could readily obtain not only w/o type cream or liquid emulsion with high water content but also liquid foundation containing pigments.
Upon investigation of physiological action of these new compounds, it was revealed that they neither cause particular skin irritation and allergy nor exhibit toxicity, thereby substantiating their physiological safety.

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As emulsions are non-equilibrium state, the technique of emulsification greatly affects the droplet size and the distribution of emulsions. When it is tried to form stable O/W emulsions by nonionic surfactants, the agent-in-oil method dissolving the surfactants in the oil phase is generally adopted.
In this paper, the reasons, which this method is desirable for forming homogeneous O/W emulsions, were investigated from the solubility state of suractants-water-oil system.
As the results, it was shown that homogeneous O/W emlsions were formed under the conditions appearing oil cotinuous phase-liquid crystalline phase-white gel emulsion-O/W emulsion in the process of emulsification. And it was indicated the possibility to decrease the difference of quality due to manufacturers by utilizing this emulsification method.
The structures of the liquid crystal and the gel which exsist in the process of emulsification were detemined by X-ray low angle diffractometer and electron microscope. And the mechanism forming a homogenious O/W emulsion was elucidated.

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