Alpha-alumina flakes

Abstract

The present invention relates to alumina flakes having a defined thickness and particle size distribution and to their use in varnishes, paints, automotive coatings, printing inks, masterbatches, plastics and cosmetic formulations and as substrate for effect pigments.

1 - 16 . (canceled) 
     
     
         17 . A blend comprising
 coated and/or uncoated Al 2 O 3  flakes having a particle thickness of less than 500 nm and a D 50 -value of 15-30 μm and a D 90 -value of 30-45 μm   and   one or more organic dyes, organic pigments, transparent pigments, opaque white pigments, colored pigments, black pigments, flake-form iron oxides, holographic pigments, liquid crystal polymers, or transparent, colored or black luster pigments based on metal oxide-coated mica or SiO 2  flakes or fillers.   
     
     
         18 . A blend according to  claim 17 , which consists of coated and/or uncoated Al 2 O 3  flakes having a particle thickness of less than 500 nm and a D 50 -value of 15-30 μm and a D 90 -value of 30-45 μm
 and 
 one or more organic dyes, organic pigments, transparent pigments, opaque white pigments, colored pigments, black pigments, flake-form iron oxides, holographic pigments, liquid crystal polymers, or transparent, colored or black luster pigments based on metal oxide-coated mica or SiO 2  flakes or fillers. 
 
     
     
         19 . A blend according to  claim 17 , which contains fillers, which are one or more of the following: natural or synthetic mica, nylon powder, pure or filled melamine resins, talc, SiO 2 , glasses, kaolin, oxides or hydroxides of aluminum, magnesium, calcium or zinc, BiOCl, barium sulfate, calcium sulfate, calcium carbonate, magnesium carbonate, carbon, or a physical or chemical combination thereof. 
     
     
         20 . A blend according to  claim 17 , wherein the Al 2 O 3  flakes have a particle thickness of 130-400 nm and a D 50 -value of 15-30 μm and a D 90 -value of 30-45 μm and a D 10 -value of <9.5 μm. 
     
     
         21 . A blend according to  claim 17 , wherein the Al 2 O 3  flakes are α-alumina flakes. 
     
     
         22 . A blend according to  claim 17 , wherein the Al 2 O 3  flakes have a standard deviation of thickness distribution of less than 80 nm. 
     
     
         23 . A blend according to  claim 17 , wherein the Al 2 O 3  flakes are doped with TiO 2 , ZrO 2 , SiO 2 , SnO 2 , In 2 O 3 , or ZnO or a combination thereof. 
     
     
         24 . A blend according to  claim 17 , wherein the Al 2 O 3  flakes are coated with at least one layer of a metal oxide, a mixture of at least two metal oxides, a metal, a metal sulphide, a titanium suboxide, a titanium oxynitride, FeO(OH), SiO 2 , a metal alloy or a rare earth compound, which form one or more coatings. 
     
     
         25 . A blend according to  claim 17 , wherein the Al 2 O 3  flakes are coated with at least one layer of a metal oxide or a mixture of at least two metal oxides. 
     
     
         26 . A blend according to  claim 17 , wherein the Al 2 O 3  flakes are coated with the following layer sequence:
 Al 2 O 3  flake+TiO 2      Al 2 O 3  flake+TiO 2 /Fe 2 O 3      Al 2 O 3  flake+Fe 2 O 3      Al 2 O 3  flake+TiO 2 +Fe 2 O 3      Al 2 O 3  flake+TiO 2 +Fe 3 O 4      Al 2 O 3  flake+TiO 2 +SiO 2 +TiO 2      Al 2 O 3  flake+Fe 2 O 3 +SiO 2 +TiO 2      Al 2 O 3  flake+TiO 2 /Fe 2 O 3 +SiO 2 +TiO 2      Al 2 O 3  flake+TiO 2 +SiO 2 +TiO 2 /Fe 2 O 3      Al 2 O 3  flake+TiO 2 +SiO 2      Al 2 O 3  flake+TiO 2 +SiO 2 /Al 2 O 3      Al 2 O 3  flake+TiO 2 +Al 2 O 3      Al 2 O 3  flake+SnO 2      Al 2 O 3  flake+SnO 2 +TiO 2      Al 2 O 3  flake+SnO 2 +Fe 2 O 3      Al 2 O 3  flake+SiO 2      Al 2 O 3  flake+SiO 2 +TiO 2      Al 2 O 3  flake+SiO 2 +TiO 2 /Fe 2 O 3      Al 2 O 3  flake+SiO 2 +Fe 2 O 3      Al 2 O 3  flake+SiO 2 +TiO 2 +Fe 2 O 3      Al 2 O 3  flake+SiO 2 +TiO 2 +Fe 3 O 4      Al 2 O 3  flake+SiO 2 +TiO 2 +SiO 2 +TiO 2      Al 2 O 3  flake+SiO 2 +Fe 2 O 3 +SiO 2 +TiO 2      Al 2 O 3  flake+SiO 2 +TiO 2 /Fe 2 O 3 +SiO 2 +TiO 2      Al 2 O 3  flake+SiO 2 +TiO 2 +SiO 2 +TiO 2 /Fe 2 O 3      Al 2 O 3  flake+SiO 2 +TiO 2 +SiO 2      Al 2 O 3  flake+SiO 2 +TiO 2 +SiO 2 /Al 2 O 3      Al 2 O 3  flake+SiO 2 +TiO 2 +Al 2 O 3      Al 2 O 3  flake+TiO 2 +Prussian Blue or   Al 2 O 3  flake+TiO 2 +Carmine Red.   
     
     
         27 . A blend according to  claim 17 , wherein the Al 2 O 3  flakes are coated with TiO 2  in the rutile modification. 
     
     
         28 . A blend according to  claim 17 , wherein the Al 2 O 3  flakes are coated with TiO 2  in the anatase modification. 
     
     
         29 . A blend according to  claim 17 , wherein the Al 2 O 3  flakes are coated, and which coated flakes consist of 40-90 wt. % of Al 2 O 3  flakes and 10-60 wt. % of the one or more coatings. 
     
     
         30 . A blend according to  claim 17 , wherein the Al 2 O 3  flakes have a D 10 -value of <9.2 μm. 
     
     
         31 . A blend according to  claim 17 , wherein the Al 2 O 3  flakes have a D 10 -value of 8.8 to 9.2 μm. 
     
     
         32 . A blend according to  claim 17 , wherein the Al 2 O 3  flakes have a particle thickness of 200-250 nm. 
     
     
         33 . A blend according to  claim 17 , wherein the Al 2 O 3  flakes have a particle thickness of 130-400 nm and a D 50 -value of 15-30 μm and a D 90 -value of 30-45 μm and a D 10 -value of 8.8 to <9.5 μm. 
     
     
         34 . A composition containing the blend according to  claim 17 , and at least one component selected from the group consisting of water, polyols, polar oils, nonpolar oils, fats, waxes, film formers, polymers, copolymers, surfactants, free-radical scavengers, antioxidants, stabilisers, odour enhancers, silicone oils, emulsifiers, solvents, preservatives, thickeners, rheological additives, fragrances, colorants, effect pigments, UV absorbers, surface-active assistants, cosmetic active compounds, fillers, binders, pearlescent pigments, color pigments and organic dyes. 
     
     
         35 . A product selected from the group consisting of base material for effect pigments, paints, coatings, automobile coatings, automotive finishing, industrial coatings, powder coatings, printing inks, security printing inks, plastics, ceramic materials, cosmetics, glasses, paper, paper coating, toners for electrophotographic printing processes, seeds, greenhouse sheeting, tarpaulins, thermally conductive self-supporting electrically insulating flexible sheets for the insulation of machines or devices, absorber in the laser marking of paper and plastics, absorber in the laser welding of plastics, pigment pastes with water, organic solvents, aqueous solvents, pigment preparations and dry preparations, comprising the blend according to  claim 17 .