8 NOVEL ACID-TYPE HAIR COLOR TECHNOLOGY 5 3 2 1 Concentration of benzyl alcohol (%) 0 Precipitation of Al-Dye complex 37 Figure 2. Formation of dye-metal ion complex. The concentration of benzyl alcohol was adjusted to 8%, 5%, 3%, 2%, 1 % and 0% (from left to right) in the solution of A1Cl 3 ·6H20 (0.5%) and acid orange 7 (0.5%). A1Cl 3 ·6H20 and acid orange 7 form a light precipitate (Al-Dye complex) with benzyl alcohol at 2% or less. With more than 3% of benzyl alcohol, no complex was observed. 20 15 10 5 0 Concentration of ethyl alcohol (%) Benzyl alcohol phase Figure 3. Separation of the benzyl alcohol phase. The concentration of ethanol was adjusted to 20%, 15%, 10%, 5%, and 0% (from left to right) in the solution of A1Cl3 ·6H20 (0.5%), acid orange 7 (0.05%), and benzyl alcohol (8%). The benzyl alcohol phase was dissolved evenly in the system under the presence of ethyl alcohol greater than 20%. as the final formula of the "permanent" acid-type hair color. A1Cl 3 ·6H 2 0 (0.5%) and glycolic acid (1.6%) were formulated in an acid-type hair colorant that can give the best performance of color brightness and color longevity. The pH of "permanent" acid-type hair color was adjusted to 3.5 with sodium lactate. The tresses (2 g) were created with the hair colorant (10 g) obtained as described in the Methods section at 30°C for 30 min. The color brightness and color longevity effects were investigated as described in the method.

38 A1Cl3 ·6H2O ZnC1 2 FeCl2 ·4H2O CaC12 ·2H2O MgC12 ·6H2O CuSO4·5H2O FeSO4·7H2O BaCl2 ·2H 2 O MnC12 ·4H 2 O NaCl KCl Control JOURNAL OF COSMETIC SCIENCE Table VI Longevity Due to Dye-Metal Ion Complex Color longevity effect (%) 91.47 77.65 71.93 78.19 76.54 81.87 74.88 77.26 77.28 63.53 75.04 74.05 The color longevity effect is represented by the following formula: Color longevity effect = Lldycd h ajLlEwashed ha ir x 100 Error range (mean +/- S.D.) 89.84-93.10 74.07-81.23 65.82-78.04 71.26-85.12 74.11-78.97 79.03-84.71 72.84-76.92 7 4.19-80.33 74.94-79.62 60.08-66.98 67 .05-83.03 69.73-78.37 where LlEdyed h air and LlEwashed hair are the degree of color change after dyeing and washing. The range was calculated by using the mean value and the standard deviation (S.D.). The result indicates that certain metal ions affect longevity at pH 3.0. AlC13 ·6H2O was substantially superior to the other metal ions in producing a longer-lasting hair color. 40 35 w 30 25 20 0 0.4 0.8 1.2 1.6 Concentration of AICl3·6H2O (%) Figure 4. The optimal concentration of AlCL, ·6H2O was investigated at pH 3.0. The closed circle (e) indicates the degree of color change (LlE) of the dyed tress (n=3). Figure 6 shows the result of (A) red fashion color and (B) brown-for-gray coverage. Both Figure 6A and 6B show that the color brightness and the color longevity effect of the "permanent" acid-type hair color were improvements over those of conventional acid­ type hair color. Figure 6A shows that the color brightness effect of conventional acid­ type hair color with this dye formulation was originally better than that of the conven-