Low-gloss ink-jet ink
Non-visible ink jet printing ink composition for marking a substrate, having at least one marking compound absorbing light outside the visible wavelength range of about 400-700 nm, and which contains a hydrocarbon compound, having two to six carbon atoms carrying two or three hydroxyl groups, as a non-particulate matting agent, so as to adapt the gloss of the ink-jet printed marking to the gloss of the substrate.
1. Inkjet printing ink composition, comprising
a. at least one binder in an amount between 4 to 20 wt-% of the overall composition;
b. at least one non-particulate matting compound in an amount between 1 to 8 wt-% of the overall composition;
c. at least one fast-drying solvent in an amount from 70 to 90 wt-% of the overall composition; and
d. at least one marking compound absorbing light outside the visible range in an amount from 0.001 to 5 wt-%;
wherein the matting compound has a higher boiling point than the fast drying solvent, and wherein the binder is insoluble in the matting compound and is selected from the group of polymers selected from the group consisting of vinyl chloride- and vinyl acetate copolymers, nitrocellulose and polyvinyl butyral.
2. Inkjet printing ink composition according to claim 1 , wherein the matting compound is selected from the group consisting of the diols and triols of short chain alkyl compounds having a chain length of two to six carbon atoms, said group consisting of pentanediol, butanediol, ethylenediol, propanediol, glycerol, and their corresponding isomers.
3. Inkjet printing ink composition according to claim 1 , wherein the fast-drying solvent is selected from the group of ketones consisting of acetone and methyl ethyl ketone.
4. Inkjet printing ink composition according to claim 1 , wherein the ink is free of water.
5. Inkjet printing ink composition according to claim 1 , wherein the marking compound is selected from the group of dyes which do not show absorbance in the visible range of the electromagnetic spectrum, said group consisting of UV markers, optical brighteners, rare earth chelates, NIR dyes and laser NIR dyes.
6. Substrate carrying a security marking printed with an inkjet printing ink composition according to claim 1 .