Ultra-bright passivated aluminum nano-flake pigments
Nano-thick flakes that are either flat, and specularly-reflective in visible light or that have microroughness intentionally controlled to disperse or interfere with visible light. Coatings and inks utilizing such flakes. Method for fabrication of such flakes in partial vacuum includes the repeated multiple times deposition of a release layer over a substrate surface and a flake layer over the release layer to form a multilayer structure further reduced to individual flakes. Reactive metal is passivated inline with the deposition of the flake layer for superior corrosion resistance. Chemically-functional materials are optionally added to the release material to transfer their functionality to the surface of flake layer to create unique functional properties on a flake surface before the multilayer structure is removed from the substrate.
1. A process for producing ultra-bright passivated flake elements, the process comprising:
a) flash evaporating in a vacuum environment a solid non-polymerizable organic layer that has a molecular weight in the range of 100 to 5000 onto a substrate, said non-polymerizable organic layer comprising an organic material that is dissolvable in a solvent;
b) depositing a layer of a first material on a surface of said solid non-polymerizable organic layer in the vacuum environment, said first material comprising metal;
c) passivating said layer of the first material comprising metal by plasma treatment in line with said depositing in the vacuum environment using a reactive gas comprising oxygen to form a non-hydrated metal oxide;
removing the metal layer from the substrate, by dissolving said solid non-polymerizable organic layer with the solvent, to form first material flake elements.
2. A process of claim 1 , further comprising repeating the steps a), b) and c) multiple times to form said multilayer structure that contains more than two layers.
3. A process of claim 1 , wherein the applying a solid non-polymerizable organic layer includes applying a solid non-polymerizable organic layer on a rotating drum.
4. A process of claim 1 , wherein the applying a solid non-polymerizable organic layer includes applying a solid non-polymerizable organic layer on a polymer web.
5. A process of claim 1 , wherein said depositing includes depositing the first material comprising aluminum.
6. A process of claim 1 , comprising applying to the substrate organic additives that are configured to react with a surface of the layer of the first material.
7. A process of claim 6 , wherein the applying includes applying said organic additives that are configured to react with the surface of the layer of the first material to cause effects that include reducing access of moisture to said surface.