Black magnetic iron oxide particles having a specific dissolution of sulfur element
AssigneeToda Kogyo Corporation
InventorsShinji Uemoto, Naoki Uchida, Mamoru Kamigaki, Ryo Iwai, Hiromitsu Misawa, Koso Aoki
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Abstract
The present invention relates to a black magnetic iron oxide particles each having a polyhedral shape wherein when a percentage of dissolution of iron element based on a total amount of iron element contained in the black magnetic iron oxide particles is 50%, a percentage of dissolution of sulfur element based on a total amount of sulfur element contained in the black magnetic iron oxide particles is less than 40%.
Claims5
Black magnetic iron oxide particles having a particle size of 0.05 to 0.30 μm and each containing sulfur distributed therein, having a polyhedral shape and having such a property that when a percentage of dissolution of iron element based on a total amount of iron element contained in the black magnetic iron oxide particles is 50%, a percentage of dissolution of sulfur element based on a total amount of sulfur element contained in the black magnetic iron oxide particles is less than 40%.
Black magnetic iron oxide particles having a particle size of 0.05 to 0.30 μm and each containing sulfur distributed therein, having a polyhedral shape and having such a property that when a percentage of dissolution of iron element based on a total amount of iron element contained in the black magnetic iron oxide particles is 50%, a percentage of dissolution of sulfur element based on a total amount of sulfur element contained in the black magnetic iron oxide particles is less than 40%;
- wherein a coating film formed by using the black magnetic iron oxide particles exhibits an a* value of CIELAB color space of not more than 2 when a thickness of the coating film is 23 to 26 μm, and satisfies the following formulae:
- 1≦α≦1.5 and
- 1≦β≦2.0,
- wherein α=a*(I)/a*(II);
- and β=a*(I)/a*(III) in which a*(I) is an a* value of the coating film when a thickness of the coating film is 4 to 6 μm;
- a*(II) is an a* value of the coating film when a thickness of the coating film is 11 to 13 μm;
- and a*(III) is an a* value of the coating film when a thickness of the coating film is 23 to 26 μm.
Dependencies are inferred from the claim text.