High-chroma orange pearl pigment
AssigneeMerck Patent Gesellschaft
InventorTamio Noguchi
Life of this patent
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Abstract
The present invention is directed to the development of a highly safe high-chroma orange pearl pigment replacing a cadmium pigment, in which a flaky substrate has surfaces coated with spherical metal oxide particles containing iron oxide, or spherical metal oxide particles obtained by adding thereto a specific proportion of one or more oxides selected from among aluminum, calcium and magnesium oxides, and a process for manufacturing the same, and uses thereof.
Claims15
An orange pearlescent pigment comprising a metal oxide containing iron oxide, coated on a flaky substrate, said metal oxide being fine spherical particles comprising said iron oxide in an amount of 40 to 300 parts by weight in terms of ferric oxide relative to 100 parts by weight of said flaky substrate, prepared by a process in which a sulfate and/or persulfate and/or polysulfate are added to a suspension of the flaky substrate prior to addition of iron salt.
An orange pearlescent pigment comprising a metal oxide containing iron oxide, coated on a flaky substrate, said metal oxide being fine spherical particles comprising said iron oxide in an amount of 40 to 300 parts by weight in terms of ferric oxide relative to 100 parts by weight of said flaky substrate, not more than 35% by weight of aluminum oxides in terms of Al2O3, and not more than 2% by weight of calcium oxides in terms of CaO, and/or not more than 2% by weight of magnesium oxides in terms of MgO, relative to said iron oxide in terms of ferric oxide.
A process for manufacturing an orange pearlescent pigment, comprising preparing an aqueous suspension of a flaky substrate, adding a sulfate and/or a persulfate and/or a polysulfate into said suspension, heating said suspension under stirring, adding a) an aqueous solution of a ferric salt, and b) an aqueous alkali solution into said suspension, while maintaining said suspension at a pH of 2 to 5, then adding aqueous alkali solution into said suspension until reaching a pH of 8 to 10.
A process for manufacturing an orange pearlescent pigment, comprising adding into an aqueous suspension of a flaky substrate and heating said suspension under stirring, a) an aqueous solution of a ferric salt and a magnesium salt and/or a calcium salt, and b) an aqueous alkali solution into said suspension, while maintaining it at a pH of 2 to 5, adding additional aqueous alkali solution into said suspension until achieving a pH of 8 to 10.
An orange pearlescent pigment comprising a metal oxide containing iron oxide, coated on a flaky substrate, said metal oxide being fine spherical particles comprising said iron oxide in an amount of 40 to 300 parts by weight in terms of ferric oxide relative to 100 parts by weight of said flaky substrate, not more than 2% by weight of calcium oxides in terms of CaO, and/or not more than 2% by weight of magnesium oxides in terms of MgO, relative to said iron oxide in terms of ferric oxide.
Dependencies are inferred from the claim text.