32. JOURNAL OF COSMETIC SCIENCE 30°C for 10 min. The color longevity effect was also tested as described above. The optimal concentration of gl ycolic acid was investigated at a specific pH of 3. 5. Color longevity was also tested as described above. The pH dependence of the color brightness of the hair colorant of Sample B in Table I, which contains 1.6% glycolic acid, was also investigated. The pH was adjusted to 2.3-4.1 with sodium lactate. The tresses (2 g) were treated with hair colorant (10 g) by the same method at 30 °C for 10 min. FORMATION OF DYE�METAL ION COMPLEX The formation of a dye-metal ion complex was observed by a microscope with a polar­ izing filter (BX50, Olympus, Tokyo). AlC1 3 ·6H2O (0.5 g) was dissolved in 100 ml of water. Acid orange 7 (0.1 g) was dissolved in 100 ml of the mixture of benzyl alcohol (8%) and water. The separated benzyl alcohol phase containing acid orange 7 was collected by a pasture pipette. One drop of the benzyl alcohol phase was put on a preparation, and one drop of the water phase was put next to the benzyl alcohol phase. The boundary face between benzyl alcohol phase and water phase was observed by the microscope with a polarizing filter. The condition for foaming dye-metal ion complex was studied in a simple-solution system that was prepared by dissolving acid orange 7 (0.5%), A1Cl 3 ·6H2O (0.5%), and benzyl alcohol (8%, 5%, 3%, 2%, 1 %, or 0%) in water. The separation of benzyl alcohol was also observed in a simple-solution system that was prepared by dissolving acid orange 7 (0.05%), A1Cl 3 ·6H2O (0.5%), benzyl alcohol (8%), and ethyl alcohol (20%, 15%, 10%, 5%, or 0%) into water. SELECTION OF MET AL ION A test sample was formulated of Sample A in Table I. Four mmol/1 of acid orange 7 and 0.02 mol/1 of metal ion (ZrC1 4 , A1Cl 3 ·6H2O, ZnC12 , FeCl2 ·4H2O, CaCl2 ·2H2O, MgCl2 ·6H2O, CuSO4 ·5H2O, FeSO4 ·7H2O, BaC12 ·2H2O, MnCl2 ·4H2O, NaCl or KCl) were added into the mixture of benzyl alcohol, ethyl alcohol, and water. The pH was adjusted to 3.0 using HCl. After being treated with the simple-solution system (50 ml) at room temperature for 20 min, the tress was rinsed with water and dried. The color of each sample tress was measured by a color analyzer (Color-Eye7000, Sakata Inx, Tokyo). The dyeing ability was expressed as the degree of color change (LiE) before and after the treatment (LiE d y ed ha ir- The dyed tresses were then soaked in 2% SDS water solution overnight. After washing and drying, the colors of the tresses were measured again (LiE washed haiJ The optimal concentration of AlC1 3 ·6H2O was investigated with the hair colorant described above. The tresses (2 g) were treated with the hair colorant (10 g) described above at 30 °C for 10 min. MICROSCOPIC OBSERVATION OF CROSS SECTION OF HUMAN HAIR The hair colorant of Sample C in Table I was obtained as described above. Tresses (2 g) were treated with the hair colorant (10 g) at 30 °C for 30 min. The dyed human hair

NOVEL ACID-TYPE HAIR COLOR TECHNOLOGY 33 was embedded in polyvinyl alcohol gel (Tissue-Tek®, Sakura Finetechnical, Tokyo), which was cooled and solidified. The solidified sample was sliced to a thickness of 5 µm by a microtome (Microtome CM3050, Leika, Postfach, Germany). The cross sections were observed by a microscope (VH-2450, Keyence, Osaka). VERIFICATION OF THE FORMATION OF DYE-METAL ION COMPLEX The key technology of formation of a dye-metal ion complex inside the hair was verified by an EDTA extraction study. The hair colorant of Sample C in Table I was prepared. Tresses of human hair were dyed with the hair color at 30 °C for 30 min. The dyed tresses (1.5 g) were dipped in 100 ml of 0% to 2% of EDTA·2Na water solution. After the tresses were washed in an ultrasonic bath (W-21 OR, Honda Electronics, Aichi, Japan) for 30 min, the outer solution was collected and filtrated through a filter paper. The UV spectrum of the solution was measured by a spectrophotometer (V-550, J asco, Tokyo). FLUORESCENT X-RAY ANALYSIS OF THE STATE OF THE ALUMINUM ION OF DYE-METAL COMPLEX To obtain the complex of A1Cl 3 ·6H 2 0, hair protein (this tress sample was called Al-Hair) and acid orange 7 (Al-Hair-Dye), the tresses (2 g) were dipped in the sample (100 ml) in Table II for 30 min. After being rinsed with water, the tresses were air-dried. This process was repeated three times. To obtain the complex of A1Cl 3 ·6H20 and acid orange 7 (Al-Dye), 0.5% A1Cl 3 ·6H20 was added to 1 % acid orange 7 solution. A deposit, which was considered to be a complex of aluminum chloride and acid orange 7 appeared in the mixed solution. The deposit was collected and dried. To analyze the state of the aluminum ion of the samples, the K 13 spectrum of the aluminum ion (Al-K 13 ) was measured by a fluorescent X-ray analyzer (Philips PW2400, Eindhoven, Netherlands). The measurement was performed under these conditions: analyzing crystal, PET voltage, 24 kV current, 125 mA scanning angle (20), 128.5°- 137.50 . NMR ANALYSIS OF THE STATE OF BOND The complex of aluminum ion and acid orange 7 (Al-Dye) obtained as described above was analyzed by NMR. Proton NMR spectra were recorded at 400.13 MHz, without spinning, on an ECP-400 spectrometer CTeol, Tokyo). The solvent used in the measure- Table II Formulation of Experimental Samples (w/w % ) Al-Hair* Al-Dye Al-Hair-Dye Benzyl alcohol 8 8 Ethyl alcohol 20 20 A1Cl 3 ·6H20 0.5 0.5 0.5 Acid orange 7 Ion-exchanged water Up to 100 Up to 100 Up to 100 * Al-Hair, Al-Dye, and Al-Hair-Dye represents complex of AlCL3 ·6H 2 0 with hair protein A1Cl3 ·6H20 and acid orange 7 and A1Cl3 ·6H20, hair protein, and acid orange 7, respectively.