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Patexia Research
Patent No. US 11059987
Issue Date Jul 13, 2021
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Patent 11059987 - Security printing inks for inkjet printers and method of manufacture > Claims

  • 1. A method of making a security ink comprising the steps: mixing two or more fluorescent materials selected from the group consisting of a UVC fluorescent dye at 15% by weight, a UVA fluorescent pigment at 15% by weight and a bi-fluorescent material at about 1% by weight with an IR upconverting pigment at about 15% to 20% by weight, to provide multiple different visible color emissions when exposed to respective different wavelengths of light, the fluorescent mixture being at 25% to 35% by weight of a pigment dispersion containing a dispersant at 4% to 10% by weight of the pigment dispersion, a deformer at 0.5% to 1% by weight of the pigment dispersion and deionized water;milling the pigment dispersion in a wet mill until the average particle size is below 300 nm; andadding the milled pigment dispersion to an inkjet ink formulation.
    • 2. The method of claim 1 wherein the pigment dispersion is at about 0.5% to 5% by weight of the security ink; and the inkjet ink contains: humectant at about 20% by weight of the security ink,surfactant at about 0.5% by weight of the security ink,polymer resin at about 1% by weight of the security ink, andbiocide at about 0.15% by weight of the security ink.
    • 3. The method of claim 1 wherein the milling step comprises milling the pigment dispersion until an average particle size of about 185 nm is achieved.
    • 4. The method of claim 1 wherein the milling step comprises milling the pigment dispersion until an average particle size less than 150 nm is achieved.
    • 5. The method of claim 1 further comprising measuring particle size of the pigment dispersion every hour until a desired size is achieved.
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