SHEET-SHAPED CERIUM OXIDE AND PETAL-SHAPED CERIUM OXIDE POWDER WHICH IS AGGREGATE OF THE SHEET-SHAPED CERIUM OXIDE, PROCESS FOR PRODUCTION OF THE SHEET-SHAPED CERIUM OXIDE AND THE PETAL-SHAPED CERIUM OXIDE POWDER, COATED SHEET-SHAPED CERIUM OXIDE AND PETAL-SHAPED CERIUM OXIDE POWDER WHICH IS AGGREGATE OF THE COATED SHEET-SHAPED CERIUM OXIDE, AND COSMETIC

摘要

[Problem] To provide: sheet-shaped cerium oxide having an average particle diameter of less than 20 µm; a petal-shaped cerium oxide powder which is an aggregate of the sheet-shaped cerium oxide; a process for producing the sheet-shaped cerium oxide and the petal-shaped cerium oxide powder; and a cosmetic which is produced by adding the sheet-shaped cerium oxide or the petal-shaped cerium oxide powder which is an aggregate of the sheet-shaped cerium oxide to a cosmetic to thereby impart a high ultraviolet ray blocking effect and an excellent feeling upon application to the cosmetic. [Solution] Sheet-shaped cerium oxide having an average particle diameter of less than 20 µm and an average aspect ratio of 2-80 and a petal-shaped cerium oxide powder which is an aggregate of the sheet-shaped cerium oxide can be produced by preparing an aqueous solution comprising cerium nitrate or cerium chloride, sodium hydrogen carbonate or sodium carbonate and water so that the molar ratio of carbonate ions to cerium ions falls within the range of 1.5-5, maintaining the aqueous solution at a temperature falling within the range of 0-40°C to cause the precipitation of cerium carbonate particles from the aqueous solution, and then burning the cerium carbonate particles.