LIQUID CRYSTAL MAKE-UP REMOVER 27 " '" "'"' •""•' ,: ..:.!,-:' ::...,, ..... . Rinsing-off treatment ß ß . •-. '• •:j.. . -4! - ß . .. ,,.. , ./ Wiping-off treatment Figure 4. Skin textures of rinsing-off and wiping-off treatments. • 0.2 • 0.15 O IS •- 0.1 oi E ,,k- 0.05 O c o IS • 0 ß EOD-5 EOD-10 ß EO-20• EHCO-60 ß ESMS-20 EMGS-15• ß I •oo_•o ß •sTo-•o , I • 0.15 o E •- 0.1 .i .i E 0 0.05 c o E ß EOD-5 EOD-10 ß EOD-15 ß EOD-25 EOD-20 4 6 8 10 12 14 16 0 5 10 15 20 25 30 HLB Number Number of ethylene oxide units (a) (b) Figure 5. Amounts of remaining remover: (a) different types of surfactants (b) various EO chain lengths.

28 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS formation of liquid crystals (13,14), whereas the hydrophilic surfactants at around 20 EO mols are more suitable for improved results in the rinsing-off process (Figure 5b). In order to obtain the expected character, it is desirable for the surfactant to be rather lipophilic at first for the liquid crystal formation and then hydrophilic at the rinsing-off process. Therefore, a nonionic surfactant with a longer EO chain, which is better for the rinsing off, was chosen. Then the system was made lipophilic by using a polyol. It is already known that the addition of some kinds of polyols such as glycerol and/or sorbitol depresses the cloud point (15,16), which diminishes hydrophilic property. The effect of addition of glycerol on a EOD-20/TGO/water system in a phase diagram is shown in Figure 6. Partial replacement of water by glycerol shifts the mutual solubility curve of oil and water to the left, and the one-phase solubilization area to the lower concentrations of surfactant. When the water was replaced by 70 wt% glycerol, the one-phase region projected toward the oil apex and the majority of the region became lamellar liquid crystal. This result is attributed to the effect of glycerol on the HLB of the surfactant. That is, glycerol depressed the hydrophilic property of the surfactant and Oil (tgO) Oil (tgO) 4O 40 (,• 40 ( o 40 tim 0 ioo 0 Water EOD-20 17% Gly EOD-20 at 25øC Oil (TGO} o (c) o •o 4(I 70% Gly oil (TGO) i• o i½•1 "i-• (d) ..... EOD-20 98% Gly EOD-20 D2 : Lameliar Liquid Cryatal D1 : Surfactant (Solid) O :Oil W :Water L1 : Micell Solution Gly: Glycerol Hex: Hexagonal Liquid Crystal Figure 6. Phase diagrams of pseudo-three-component systems of EOD-20/TOO/water/glycerol.