非イオン性乳化剤を用いたO/Wエマルションの遠心による安定性試験とHLB

抄録

The stability against separation of oil phase from 25% liquid petrolatum-water emulsions stabilized with 0.5% mixed surfactants of sorbitan-fatty acid monoesters and polyoxyethylene sorbitan-fatty acid monoesters was evaluated by centrifugation. Reproducibility of the centrifugal test was very good. Result of the test after aging was closely related to the induction period of oil phase separation and the quantity of separated oil phase after a long-time storage of the emulsions. Change of the specific interfacial area with time revealed that the stabilizing effect is better for a single hydrophilic surfactant with maximum hydrophile-lypophile balance (HLB) than for any mixed surfactant in the relation of HLB value with stability. It thus appears that the so-called "optimum HLB value" determines the best dispersibility, because the specific interfacial area immediately after emulsification shows a maximum value at the "optimum HLB value" while the best stabilizing effect is not attained.