OW MICROEMULSION IN SUNSCREENS 459 C•2-C•e alkylbenzoate 32.7% ethanol 16. 3% cvclornethicone 21% 4-methylbenzylidencamphor 30% / \ / \ / / \ ^ ß crystals Water/ A_.-•/• \ 1,2.hexanediol =•----•-•o • •i • •! Decylpolyglucose 67% Figure 7. Ternary diagram of the complex mixtures with C•2_•5 alkylbenzoate, ethanol, cyclomethicone, 4-methylbenzylidene camphor, soya lecithin, decylpolyglucose, water, and 1,2-hexanediol. Table III W/W Percentages of Components of Microemulsions With 4-Methylbenzylidene Camphor (MBC), Soya Lecithin (SL)/Decylpolyglucose (DPG)/C•2_• 5 Alkylbenzoate (CAB)/Cyclomethicone (CMC)/Ethanol/ Water and 1,2-Hexanediol (HD) or Water and 2-Methyl, 2,4-Propanediol (MPD) Total Surfactant/lipid Dilution HD water DPG SL CAB Ethanol CMC MBC 60/40 50/50 16.67 42.38 11.05 9.90 6.54 3.26 4.20 6.00 60/40 60/40 20.00 47.24 8.84 7.92 5.23 2.61 3.36 4.80 70/30* 50/50* 16.67' 43.88* 12.90' 11.55' 4.91' 2.44* 3.15' 4.50* 80/20 50/50 16.67 45.39 14.74 13.20 3.27 1.63 2.10 3.00 80/20 90/10 30.00 62.41 2.95 2.64 0.65 0.33 0.42 0.60 MPD 60/40 50/50 14.29 44.76 11.05 9.90 6.54 3.26 4.20 6.00 60/40 90/10 25.71 66.10 2.21 1.98 1.31 0.65 0.84 1.20 70/30 90/10 25.71 66.40 2.58 2.31 0.98 0.49 0.63 0.90 80/20 50/50 14.29 47.77 14.74 13.20 3.27 1.63 2.10 3.00 80/20 90/10 25.71 66.70 2.95 2.64 0.65 0.33 0.42 0.60 In the most stable system,* no crystals of methylbenzylidene camphor formed over time, but over time sedimentation occurred, and so 2.5% 1,2-hexanediol was replaced by 2.5% ethanol. With 2-methyl-2,4- pentanediol, the stability of the systems appeared to increase. C: 4-methylbenzylidene camphor 4.5 %, cyclomethicone 3.15 %, ethanol 2.44%, C•2_•5 alkylbenzoate 4.91%, decylpolyglucose 23.45 %, soyalecithin 11.55 %, 1,2-hexanediol 16.67%, water 33.33%. D: octylmethoxycinnamate 6.0%, cyclomethicone 2.7%, ethanol 1.26%, C•2_•5 alkyl- benzoate 5.04%, decylpolyglucose 23.45%, soyalecithin 11.55%, 1,2-hexanediol 16.67%, water 33.33%. System C was modified by adding allantoin, menthol, and stearyl methicone so as to produce a fresh, waterproof, and moisturizing product: E: 4-methylbenzilidene camphor 3.0%, cyclomethicone 3.24%, ethanol 2.52%, C•2_•5 alkylbenzoate 5.04%, menthol 0.40%, stearyl methicone 0.80%, decylpolyglucose

460 JOURNAL OF COSMETIC SCIENCE C•2-C•= alkylbenzoate 33.6% ethanol 8.4% cyclomethicone 18% Octylm etho xycinnamate 4O% 1,2heWxaat•er/dlol ,. ,ecithin 33% 2/1 •i •i • • Decylpolyglucose 67% Figure 8. Ternary diagram of the complex mixtures with C•2_•5 alkylbenzoate, ethanol, cyclomethicone, octylmethoxycinnamate, soya lecithin, decylpolyglucose, water, and 1,2 hexanediol. Table IV W/W Percentages of Components of Microemulsions With Octylmethoxycinnamate (OMC), C•2_•5 Alkylbenzoate (CAB)/Cyclomethicone (CMC)/Soya Lecithin (SL)/Decylpolyglucose (DPG), and Ethanol/1,2-Hexanediol (HD)/Water or Ethanol/2-Methyl-2,4-Pentanediol (MPD)/Water Total Surfactant/lipid Dilution HD water DPG SL CAB Ethanol CMC OMC 60/40 40/60 13.33 37.52 13.27 11.88 8.06 2.02 4.32 9.60 70/30 50/50 16.67 43.88 12.90 11.55 5.04 1.26 2.70 6.00 70/30* 90/10' 30.00* 62.11' 2.58* 2.31' 1.01' 0.25* 0.54* 1.20' 80/20 60/40 20.00 49.66 11.79 10.56 2.69 0.67 1.44 3.20 80/20 90/10 30.00 62.41 2.95 2.64 0.67 0.17 0.36 0.80 MPD 70/30 50/50 14.29 46.26 12.90 11.55 5.04 1.26 2.70 6.00 70/30 90/10 25.71 64.40 25.80 2.31 1.01 0.25 0.54 1.20 80/20 50/50 14.29 47.77 14.74 13.20 3.36 0.84 1.80 4.00 80/20 90/10 25.71 66.70 2.95 2.64 0.67 0.17 0.36 0.80 * Best microemulsion. 23.45%, soya lecithin 11.55%, 1,2-hexanediol 14.00%, allantoin 0.17%, ethanol 2.50%, water 33.30%. The addition of stearyl methicone and menthol to the lipid phase of the microemulsion with 4-methylbenzilidene camphor produced a system in which the amount of sunscreen agent was reduced from 4.5% to 3.0%, to compensate for a proportional increase in cyclomethicone, ethanol, and C•2_•5 alkylbenzoate. System D was modified by adding stearyl methicone, allantoin, and menthol to give: F: octylmethoxycinnamate 5.44%, cyclomethicone 2.45%, ethanol 1.14%, C•2_•5 al- kylbenzoate 4.57%, menthol 0.40%, stearyl methicone 1.00%, decylpolyglucose 23.45%, soya lecithin 11.55%, 1,2-hexanediol 16.50%, allantoin 0.17%, water 33.30%. This system did not show phase separation under optical microscope. Dilution with water was possible, producing a sunscreen percentage (2.72%) comparable to that