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Abstract

The present invention provides ultraviolet curable or electron beam curable fluorescent inks and ink concentrates, which cure upon exposure to ultraviolet or electron beam radiation. The synthesis of the fluorescent ink and ink concentrates does not involve the use of volatile organic solvents, so removal of solvents is not necessary during the manufacturing process. The fluorescent inks and ink concentrates display minimal, consistent color shift when cured. The cured fluorescent inks and ink concentrates are solvent resistant, particularly to methyl ethyl ketone, methanol, nonane, and sec butyl alcohol. The fluorescent ink and ink concentrate is comprised of: from about 20 to 90%, preferably from about 30 to 70%, more preferably from about 30 to 60% by weight of an oligomer, which is either a formaldehyde oligomer or a cyclic-aliphatic oligomer; from about 0.1 to 15%, preferably about 1 to 10%, of fluorescent dye; and from about 10 to 80%, preferably from about 30 to 70%, more preferably from about 35 to 60% of a photopolymerizable vehicle. The oligomer preferably has a weight average molecular weight of at least 400 g/mole. Preferably the oligomer has a molecular weight of from about 400 to 50,000 g/mole. The formaldehyde oligomer embodiment of the fluorescent ink preferably contains from about from 45% to 60% photopolymerizable vehicle, and from about 30 to 45%, oligomer. The formaldehyde oligomer contains from about 5% to 60%, preferably from about 15 to 45 % polymerized units of formaldehyde monomer and from about 40 to 95%, preferably about 55 to about 85%, polymerized units of an aromatic amide monomer. The cyclic-aliphatic oligomer embodiment preferably contains from about from 35% to 55% photopolymerizable vehicle, and from about 40 to 60%, oligomer. The cyclic-aliphatic oligomer contains polar groups and is comprised of polymerized units of from about 20 to 80%, preferably from about 30 to, 50% of cyclic monomers, and from about 80 to 20%, preferably from about 50 to about 70%, aliphatic monomers.

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First Claim