Silver-colored luster pigment

Abstract

The present invention relates to silver-colored luster pigments based on multiply coated platelet-shaped substrates, which has at least one layer sequence of TiO 2 , a colorless coating and another TiO 2 layer. The pigment can optionally have an outer protective layer. These luster pigments are useful and to the use thereof in paints, coatings, printing inks, including security printing inks, plastics, ceramic materials, glasses, cosmetic formulations and for producing pigment preparations and dry product forms such as granules, chips, pellets and briquettes.

1 . A silver-colored luster pigment comprising a multiply coated platelet-shaped substrate and at least one layer sequence of 
 layer (A) a high refractive coating consisting of TiO 2  which has a thickness of 5-200 nm,    layer (B) a colorless coating having a refractive index n≦1.8 and a thickness of 10-300 nm, and    layer (C) a high refractive coating consisting of TiO 2  which has a thickness of 5-200 nm, and optionally    layer (D) an outer, protective layer.    
     
     
         2 . A luster pigment according to  claim 1 , wherein the platelet-shaped substrate is a sheet silicate.  
     
     
         3 . A luster pigment according to  claim 1 , wherein the platelet-shaped substrate is a natural mica, a synthetic mica, talc, kaolin, a platelet-shaped iron oxide, a platelet-shaped aluminum oxide, a glass platelet, SiO 2  platelets, TiO 2  platelets, Al 2 O 3  platelets, a graphite platelet, a synthetic support-free platelet, titanium nitride, titanium silicide, a liquid crystal polymer, a holographic pigment, BiOCl, platelet-shaped mixed oxides of FeTiO 3  or FeTiO 5 .  
     
     
         4 . A luster pigment according to  claim 1 , wherein layer (B) comprises silicon dioxide, aluminum oxide, AlO(OH), B 2 O 3 , MgSiO 3 , magnesium fluoride or mixtures thereof.  
     
     
         5 . A luster pigment according to  claim 1 , wherein layer (B) comprises silicon dioxide.  
     
     
         6 . A luster pigment according to  claim 1 , comprising a layer sequence of (A)+(B)+(C)+(B)+(C).  
     
     
         7 . A luster pigment according to  claim 1 , comprising a layer sequence of (A)+(B )+(C)+(B )+(C)+(B)+(C).  
     
     
         8 . A luster pigment according to  claim 1 , comprising a layer sequence of (A)+(B)+(C)+(B)+(C)+(B)+(C)+(B)+(C).  
     
     
         9 . A luster pigment according to  claim 1 , wherein the platelet-shaped substrates are 0.005 to 10 μm in thickness, and 1 to 500 μm in length.  
     
     
         10 . A luster pigment according to  claim 9 , wherein the platelet-shaped substrates are 0.5 to 5 μm in thickness, and independently of the thickness, 2 to 200 μm in length.  
     
     
         11 . A luster pigment according to  claim 9 , wherein the platelet-shaped substrates are 5 to 60 μm in length.  
     
     
         12 . A luster pigment according to  claim 1 , wherein layers (A) and (C) each independently of one another are 10 to 100 nm thick.  
     
     
         13 . A luster pigment according to  claim 1 , wherein layers (A) and (C) each independently of one another are 20 to 70 nm thick.  
     
     
         14 . A luster pigment according to  claim 1 , wherein layer (B)is 20 to 100 nm thick.  
     
     
         15 . A luster pigment according to  claim 1 , wherein layer (B) is 30 to 80 nm thick.  
     
     
         16 . A luster pigment according to  claim 1 , wherein the total thickness of all the layers on the substrate is at most 3 μm.  
     
     
         17 . A luster pigment according to  claim 8 , wherein the total thickness of all the layers on the substrate is at most 3 μm.  
     
     
         18 . A process for preparing a luster pigment of  claim 1 , wherein a substrate is coated wet chemically by hydrolytic decomposition of metal salts in an aqueous medium, or is gas phase coated in a fluidized bed reactor.  
     
     
         19 . A method of coloring a paint, a coating, a painting ink, a security printing ink, a plastic, a ceramic material, glasses, a cosmetic formulation, a nail varnish, a lipstick, a compact powder, a gel, a lotion, a soap, a toothpaste, an automotive coating, an industrial coating, a powder coating, or a window by adding or applying a luster pigment of  claim 1 .  
     
     
         20 . A pigment preparation comprising at least one luster pigment according to  claim 1 , at least one binder, and optionally at least one additive.  
     
     
         21 . A pigment preparation according to  claim 20  further comprising an organic dye, another pigment than a pigment according to  claim 1 , a liquid crystal polymer, a platelet-shaped iron oxide, a filler or mixtures thereof.  
     
     
         22 . A paint, a coating, a painting ink, a security printing ink, a plastic, a ceramic material, glasses, a cosmetic formulation, a nail varnish, a lipstick, a compact powder, a gel, a lotion, a soap, a toothpaste, an automotive coating, an industrial coating, a powder coating, or a window colored by the method according to  claim 18 , in the form of granules, chips, pellets and/or briquettes.