Iridescent pigment having high brilliance and high chroma

Abstract

An iridescent multilayer pigment having at least two or more layers of metal oxides containing one or more metals selected from Ce, Sn, Ti, Fe, Zn and Zr which are coated onto the surface of thin platelet-like substrates. The inventive pigments show high brilliance and high chroma, in particular in cases in which thin platelet-like substrates having a fine average particle diameter are used. The pigment is useful in paints, printing inks, lacquers, plastics, dopants for laser marking, non-dusting pigment products, non-dusting pigment granules or cosmetics.

1 . The method according to  claim 10 , wherein the iridescent pigment comprises a platelet shaped substrate and coated thereon at least two layers of metal oxides, each of said metal oxide layers comprising one or more of Ce, Sn, Ti, Fe, Zn and Zr.  
   
   
       2 . The method according to  claim 1 , wherein a layer adjacent to the substrate is a metal oxide layer comprising one or more metals selected from the group consisting of Ce, Sn and Fe, and wherein said pigment comprises one or more repeating set of metal oxide layers of Sn followed by Ti.  
   
   
       3 . The method according to  claim 1 , wherein a layer adjacent to the substrate is a metal oxide layer comprising Sn, and the layer thereon is a metal oxide layer comprising Ti.  
   
   
       4 . The method according to  claim 1 , wherein a metal oxide layer comprises an alkali metal and/or an alkaline earth metal.  
   
   
       5 . The method according to  claim 4 , wherein the alkaline earth metal is Mg and/or Ca.  
   
   
       6 . The method according to  claim 1 , wherein the specific surface area of the pigment is 10 m 2 /g or less.  
   
   
       7 . The method according to  claim 1 , wherein the pigment has a pore amount of 0.006 ml or less for each 1 m 2  of the surface area of the platelet shaped substrate.  
   
   
       8 . The method according to  claim 1 , wherein the pigment has a specific surface area is 10 m 2 /g or less and the pore amount of 0.006 ml or less for each 1 m 2  of the surface area of the platelet shaped substrate.  
   
   
       9 . The method according to  claim 1 , wherein the platelet shaped substrate is mica, synthetic mica, silica flakes, alumina flakes, glass flakes, thin platelet-like iron oxide or metal flakes.  
   
   
       10 . A method for preparing an iridescent pigment comprising preparing a suspension, said suspension comprising platelet shaped substrates and one or more water-soluble polymers and/or water-soluble nitrogen compounds, followed by coating a metal hydrate layer onto the surface of the substrates by adding one or more metal salts and a basic aqueous solution to said suspension.  
   
   
       11 . A method according to  claim 10  comprising adding to the suspension one or more alkali metal compounds and/or alkaline earth metal compounds, optionally said one or more alkali metal compounds and/or alkaline earth metal compounds are in an aqueous solution when added to the suspension.  
   
   
       12 . A method according to  claim 10 , wherein the water-soluble polymer is polyethylene glycol.  
   
   
       13 . A method according to  claim 10 , wherein the water-soluble polymer is a water-soluble surfactant.  
   
   
       14 . (canceled)  
   
   
       15 . (canceled)  
   
   
       16 . The method according to  claim 1 , wherein the average particle diameter of the substrate is 30 μm or less.  
   
   
       17 . The method according to  claim 1 , wherein the average particle diameter of the substrate is 20 μm or less.  
   
   
       18 . The method according to  claim 1 , wherein the average particle diameter of the substrate is 10 μm or less.  
   
   
       19 . The method according to  claim 10 , wherein the water-soluble nitrogen compound is urea, buret, guanidine or a water-soluble amine.  
   
   
       20 . A method according to  claim 10 , wherein the basic compound is sodium hydroxide or potassium hydroxide.  
   
   
       21 . The method according to  claim 3 , wherein the pigment comprises one or more repeating metal oxide layers of Sn followed by Ti.  
   
   
       22 . The method according to  claim 1 , wherein the pigment comprises a layer sequence of metal oxide layers of Sn—Ti—Sn.  
   
   
       23 . A method according to  claim 10 , wherein the metal salt is a secondary tin salt and no oxidizing agent is added to the suspension.  
   
   
       24 . The method according to  claim 1 , wherein the pigment comprises a layer sequence of metal oxide layers of Fe—Sn—Ti—Sn—Ti.  
   
   
       25 . The method according to  claim 1 , wherein the pigment comprises a layer sequence of metal oxide layers of Fe—Sn—Fe/Ti.  
   
   
       26 . (canceled)