Radar frequency transparent effect pigment mixture, formulations and coatings thereof

A coating formulation comprising

• a binder, and
• an effect pigment mixture, the effect pigment mixture comprising:
• a silvery pearlescent pigment and platelet-like aluminum effect pigment, the aluminum effect pigment obtained by grinding of one or more of aluminum shot or aluminum based alloy shot, wherein the silvery pearlescent pigment comprises any one or more of:
• a) a pearlescent pigment comprising a transparent substrate coated with a high-refractive index layer having n>1.8 and comprising an iron-oxide including Fe(II)-ions,
• b1) a pearlescent pigment comprising a transparent substrate coated with a high-refractive index layer having n>1.8 and comprising a titanium suboxide,
• b2) a pearlescent pigment comprising a substrate including a high-refractive index layer having n>1.8 and comprising a titanium suboxide that is optionally coated with a high-refractive index layer having n>1.8,
• c) a pearlescent pigment comprising a transparent substrate coated with a high-refractive index layer having n>1.8 and comprising a titanium oxynitride,
• d) a pearlescent pigment comprising a transparent substrate coated with a layer comprising carbon, wherein the carbon is enclosed in a particulate form in another metal oxide layer or is formed as a separate, individual layer,
• e) a pearlescent pigment comprising a transparent substrate coated with a first layer comprising a mixture of oxides of titanium, iron and at least one of cobalt and chromium and a second layer on the first layer, wherein the second layer comprises an oxide of titanium, and
• f) a pearlescent pigment comprising any one of the coating layers mentioned in the pearlescent pigments a) to e),
• wherein the weight ratio of the pearlescent pigment to the aluminum effect pigment is in a range of 0.4 to 5.0;
• wherein the platelet-like aluminum effect pigment is coated with an anticorrosive coating comprising adsorbed additives based on one or more of a phosphonic acid and a phosphoric ester.

An effect pigment mixture comprising a silvery pearlescent pigment and platelet-like aluminum effect pigment, the aluminum effect pigment obtained by grinding of one or more of aluminum shot or aluminum based alloy shot, wherein the silvery pearlescent pigment comprises any one or more of:

• a) a pearlescent pigment comprising a transparent substrate coated with a high-refractive index layer having n>1.8 and comprising an iron-oxide including Fe(II)-ions,
• b1) a pearlescent pigment comprising a transparent substrate coated with a high-refractive index layer having n>1.8 and comprising a titanium suboxide,
• b2) a pearlescent pigment comprising a substrate including a high-refractive index layer having n>1.8 and comprising a titanium suboxide that is optionally coated with a high-refractive index layer having n>1.8,
• c) a pearlescent pigment comprising a transparent substrate coated with a high-refractive index layer having n>1.8 and comprising a titanium oxynitride,
• d) a pearlescent pigment comprising a transparent substrate coated with a layer comprising carbon, wherein the carbon is enclosed in a particulate form in another metal oxide layer or is formed as a separate, individual layer,
• e) a pearlescent pigment comprising a transparent substrate coated with a first layer comprising a mixture of oxides of titanium, iron and at least one of cobalt and chromium and a second layer on the first layer, wherein the second layer comprises an oxide of titanium, and
• f) a pearlescent pigment comprising any one of the coating layers mentioned in the pearlescent pigments a) to e),
• wherein the weight ratio of the pearlescent pigment to the aluminum effect pigment is in a range of 0.4 to 5.0;
• wherein the platelet-like aluminum effect pigment is coated with an anticorrosive coating comprising a metal oxide further modified by an organofunctional silane, aluminate, titanate or zirconate.