Surface active agents (surfactants) were tested for hemolysis of rat erythrocytes and neutral red uptake using rabbit corneal cell (SIRC). The effects of hemolysis were manifested as the concentration of surfactants at 50% hemolysis of erythrocytes (HC-50 values). The effects of NR-uptake were manifested as the concentration of surfactants at 50% NR-uptake compared with untreated controls (NR-50 values). These results were compared with in vivo eye irritation score of surfactants obtained by Draize test.
Good correlations were seen between these inverse numbers of two results (HC-50 values and NR-50 values) and the Draize scores. The results suggest that both the hemolysis assay and the neutral red assay may be useful as an alternative to the Draize test as an in vitro method for detecting eye irritation.

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We developed new oil gelling agents composed of a long-chain dialkyl phosphate (DP) surfactant and aluminum ion or multinuclear aluminum ion (MAI) which provide the ideal oil-gel systems. One such gelling agent is the aluminum salt of DP (DP-Al) prepared as a precipitate by mixing DP with aluminum chloride in aqueous solutions. Addition of small amounts of the salt to nonpolar oils led to hardening of the oil solutions at temperature below the melting point of alkyl chain (Tc) of DP-Al. Results obtained by X-ray diffraction techniques and with scanning electron microscopy (SEM) revealed that linearly-polymerized assemblies of DP-Al expand in oils three-dimensionally, which suggests that the excellent stability of the gel systems arises from the highly ordered structure. The gelling agent of DP-Al offered the ideal rheological property of waxy cosmetic products such as lip sticks. The complexes of DP with MAI particles (1nm diameter) of aluminum chlorohydrate, Al₁₃O₄(OH)₂₄(H₂O)₁₂Cl₇, provided the ideal thixotropic behavior in non-polar oils. The DP-MAI particle complexes were found to weakly interact by cohesive forces which makes a highly ordered structure of the DP-MAI particle complexes. The DP-MAI particle complexes offered the excellent stability and transparency of cosmetic products such as W/O creams.

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A new method for preparation of ultrafine emulsions was developed. The ultrafine emulsions can be obtained easily by rapid cooling of the high temperature microemulsions, i.e., the swollen micellar solutions in the oil-water-nonionic surfactant systems, to room temperature. They are the thermodynamically unstable dispersions of which the mean droplet diameters are bellow 100nm, and look like so-called microemulsions, i.e., transparent or translucent. The droplet diameter was related to the ratio of oil to surfactant by a linear function. The droplet size of the ultrafine emulsions can thus be controlled by changing this ratio.
The stability of the ultrafine emulsions depends on the chemical nature of the oil and surfactant. The stability rises dramatically with increase in the carbon number of the oil, and decreases with increase in the polarity of the oil. The droplets of the liquid paraffin (Lp) and squalane (Sq) ultrafine emulsions do not practically change in size for over a year at 25°C. The addition of small quantities of a long-chain alkane to the disperse phase can have a profound effect on ultrafine emulshion stability. The unstable ultrafine emulsions of short-chain alkanes such as dodecane can be stabilized by added Lp or Sq. The results suggest that the main cause of instability in the ultrafine emulsions may be molecular diffusion (Ostwald ripening) rather than droplet coalesence. The stability of the ultrafine emulsions increases with the size of the surfactant molecule.
The ultrafine emulsions were prepared by using the commercial materials for the purpose of applying to the products of cosmetics. The transparent or translucent lotions containing oil components were obtained by using small quantities of the surfactants, and were very stable. Since this method can keep the droplet size under precise controll, the turbidity of the products can be controlled easily.

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We examined about relation between sensory test values and physical measurement values about properties of emulsions.
At first, 22 items were evaluated sensually by some experts, and degree of moisture and lipid quantity of skin surface were measured. The data was analyzed by principle component analisis, and sensory classification scale (light type-rich type) and skin effect classification scale (moist type-oily type) were abstracted. According to the classification by the skin effect scale, the moist feeling was correlated with the degree of moisture on the moist type emulsions.
Next, 12 items were measured their physical properties by tensipresser. And the data was correlated with sensory values. The measurement was carried by multi point biting method, and softness and viscosity were abstracted. From these physical parameters, the sensory properties of emulsions such as stickiness were briefly estimated, and it was suggested that automatic evaluation of emulsions would be possible by tensipresser.

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The solution behavior of new cationic surfactants, quaternary ammonium salts synthesized by using long-chain Guerbet alcohols, in water was investigtigated by a polarizing microscopic technique, differential scanning calorimetry, and electric conductivity measurements. These surfactants show the gel-liquid crystalline phase transition to be lower than 0°C and form lamellar liquid crystal even in cold water and at low concentrations of surfactants. The sorption of cationic surfactants from aqueous solutions onto hair was determined as a function of temperature. The effect of adsorbed cationic surfactants on the critical surface tension and kinetic frictional coefficients of hair surface have been investigated. These surface characteristics of hair treated with quaternary ammonium compounds derived from Guerbet alcohol found to be dramatically improved and this results can be explained by high ability of sorption onto hair. Hair rinses and conditioners having excellent ease of combing or brushing for wet and dry hair can be formulated by the application of those cationic surfactants.

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The transfer of drug dissolved in an oil vehicle into an aqueous solution was studied in vitro method with modified Sartorius Absorption Simulator. On the basis of previous study concerning the drug transfer at an early stage, the whole stage of the transfer was discussed by long-time measurement. The transfer behavier of drug from an oil vehicle to an aqueous solution was expressed by the equation Q=(a/b)(1-e^-bt) where Q is the total amount of drug transfered, t the time passed and a and b the transfer constants. The equation was theoretically derived from a drug transfer model.

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We studied the change in skin thickness of forehead and cheek with age for healthy male and female subjects using ultrasound method. Skin thickness decreased with ageing in forehead and cheek in both sex groups, and it was thicker at every age group in males than in females.
We also measured the skin thickness from twelve different sites at face in six healthy subjects. It was shown that skin thickness of eyelid was thinner than that of jaw or cheek.

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