Magnetic pigments and process of enhancing magnetic properties
AssigneeSun Chemical Corporation
InventorsAaron M. Hollman, Philippe Schottland
Life of this patent
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Abstract
A pearlescent pigment and a process for enhancing the magnetic properties of a pearlescent pigment. The pearlescent pigment has a layer with regions of γ-Fe2O3 and regions of α-Fe2O3. The magnetic properties of a pearlescent pigment may be enhanced by the steps of: providing a platelet pigment with a layer of Fe2O3, with a magnetic susceptibility less than 0.1×10−5 m3/kg; reducing some or all of the Fe2O3 to Fe3O4; and oxidizing some or all of the Fe3O4 to γ-Fe2O3. The color difference (ΔE*) between the provided pigment and the resultant pigment is not more than about 5.
Claims24
A pigment comprising a substrate and a layer, wherein the layer has regions of γ-Fe2O3 and α-Fe2O3.
A process for enhancing the magnetic properties of pigments comprising the steps of:
- 1) providing a substrate with an layer comprising Fe2O3, with a magnetic susceptibility less than 0.1×10−5 m3/kg;
- 2) reducing some or all of the Fe2O3 to Fe3O4;
- 3) subsequently oxidizing some or all of the Fe3O4 to γ-Fe2O3.
A pigment formed by the steps comprising:
- 1) providing a platelet pigment;
- 2) increasing the magnetic mass susceptibility;
- wherein the color difference (ΔE*) between the provided pigment and the resultant pigment of step 2 is not more than about 5.
Dependencies are inferred from the claim text.