Claims
- 1. A process for stabilizing a metal oxide-coated mica pigment against light and moisture, comprising adding to an aqueous suspension of said metal oxide-coated mica pigment an aluminum compound at a rate of 0.001 to 0.07 mg Al per minute per gram of said metal oxide-coated mica to cause coating by hydrolysis so as to form on said metal oxide-coated mica pigment a hydrous aluminum oxide coating containing an amount of aluminum equal to about 0.1 to 0.8 wt % of the hydrous aluminum oxide-coated pigment.
- 2. The process of claim 1 wherein said adding an aluminum compound comprises simultaneously adding an aluminum salt solution and a basic solution.
- 3. The process of claim 2 in which the temperature is about 30.degree. to 90.degree. C. and the pH is maintained at about 4.5 to 6.5.
- 4. The process of claim 3 in which the temperature is about 40.degree. to 80.degree. C. and the pH is maintained at about 5 to 6.
- 5. The process of claim 2 in which the aluminum salt is aluminum chloride or aluminum sulfate.
- 6. The process of claim 1 wherein said adding an aluminum compound comprises simultaneously adding an aluminate solution and an acid solution.
- 7. The process of claim 1 in which the temperature is ambient to about 80.degree. C. and the pH is maintained at about 7 to 9.5.
- 8. The process of claim 7 in which the temperature is ambient to about 20.degree. to 65.degree. C. and the pH is maintained at about 8 to 9.
Parent Case Info
This is a division of application Ser. No. 07/491,728, filed Mar. 12, 1990, now U.S. Pat. No. 5,091,011.
US Referenced Citations (5)
Foreign Referenced Citations (2)
Number |
Date |
Country |
2311822 |
Dec 1976 |
FRX |
2-14819 |
Jan 1990 |
JPX |
Divisions (1)
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Number |
Date |
Country |
Parent |
491728 |
Mar 1990 |
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