UV-VIS RADIATION CURABLE SECURITY INKS

Abstract

The present invention relates to the field of security inks suitable for printing security features on substrates, in particular, on security documents or articles, as well as security features made from such security inks, and security documents comprising a security feature made from such security inks. In particular, the invention provides UV-Vis cationicly curable security inks and UV-Vis hybrid curable security inks comprising an ink and pigment vehicle comprising a non-metallic or metallic flake substrate comprising one or more at least partial coating layers, and at least partial surface treatment layers made of one or more perfluoropolyether-based surface modifiers.

Claims

CLAIMS 1. A UV-Vis radiation-curable security ink characterized in that it comprises: i) from 75 wt% to 99 wt% of an ink vehicle having a viscosity between 200 and 2000 mPas at 25 °C and comprising: a) a1) from 45 wt% to 75 wt% of one or more cycloaliphatic epoxides and a2) from 2 wt% to 15 wt% of one or more cationic photoinitiators being onium salts, preferably selected from the group consisting of oxonium salts, iodonium salts, sulfonyl salts and mixtures thereof, or b1) from 45 wt% to 75 wt% of a mixture comprising one or more cycloaliphatic epoxides and one or more radically curable compounds selected from the group consisting of tri(meth)acrylates, tetra(meth)acrylates and mixtures thereof and b2) from 2% by weight to 15% by weight of a mixture of one or more cationic photoinitiators that are onium salts, preferably selected from the group consisting of oxonium salts,iodonium salts, sulfonyl salts and mixtures thereof and one or more free radical photoinitiators, preferably selected from the group consisting of hydroxyketones, alkoxyketones, acetophenones, benzophenones, ketosulfones, benzyl ketals, benzoin ethers, phosphine oxides, phenylglyoxylates, thioxanthones and mixtures thereof, more preferably selected from the group consisting of phosphine oxides, thioxanthones, alpha-hydroxyketones and mixtures thereof, the weight percentages of a) and b) being based on the total weight of the ink vehicle; and i) from 1 to 25% by weight of pigments comprising a non-metallic or metallic flake substrate, wherein said non-metallic or metallic substrate comprises one or more at least partial coating layers made independently of one or more metal oxides, one or more metal oxide hydrates,one or more metal suboxides or mixtures thereof and comprises an at least partial surface treatment layer facing outwards, which is in direct contact with the top layer of the one or more at least partial coating layers and made of one or more surface modifiers selected from perfluoropolyethers, said perfluoropolyethers being functionalized with one or more phosphorus-containing (P) groups or one or more silicon-containing (Si) groups, the weight percentage of i) and ii) being based on the total weight of UV-Vis radiation-curable security ink.

2. The UV-Vis radiation curable security ink according to claim 1, further characterized in that the ink vehicle comprises c) one or more vinyl ethers in an amount less than 20% by weight, or one or more oxethanes in an amount less than or equal to 30% by weight, or a combination of one or more vinyl ethers and one or more oxethanes in an amount less than or equal to 15% by weight, the weight percentages of a), b) and c) being based on the total weight of the ink vehicle.

3. The UV-Vis curable security ink according to claim 1 or 2, further characterized in that it is a UV-Vis curable screen printing security ink.

4. The UV-Vis cationicly curable security ink according to any of claims 1 to 3, further characterized in that the ink vehicle further comprises c) one or more vinyl ethers in an amount less than 20% by weight, or one or more oxethanes in an amount less than or equal to 30% by weight, or a combination of one or more vinyl ethers and one or more oxethanes, wherein said combination is present in an amount less than or equal to 15% by weight, the weight percentages of a), b) and c) being based on the total weight of the ink vehicle.

5. The UV-Vis cationicly curable security ink according to any of claims 1 to 4, further characterized in that the ink vehicle further comprises one or more polyhydroxy compounds, preferably one or more polyhydroxy compounds comprising more than two hydroxyl groups, wherein said one or more polyhydroxy compounds are present in an amount less than or equal to 25% by weight, the weight percentages being based on the total weight of the ink vehicle.

6. The UV-Vis cationicly curable security ink according to any of claims 1 to 5, further characterized in that the ink vehicle comprises 45 to 75% by weight of a mixture comprising one or more cycloaliphatic epoxides and one or more radically curable compounds selected from the group consisting of tri(meth)acrylates, tetra(meth)acrylates and mixtures thereof, wherein said one or more radically curable compounds are present in an amount less than or equal to 35.7% by weight, preferably less than or equal to 30.7% by weight, the weight percentages being based on the total weight of the ink vehicle.

7. The UV-Vis cationicly curable security ink according to any of claims 1 to 6, further characterized in that the pigments comprise a flake-shaped metallic substrate consisting of a multilayer comprising one or more metallic layers, preferably thin-film interference multilayers having a Fabry-Pérot absorber / dielectric / reflector / dielectric / absorbent structure, wherein said pigments comprise one or more at least partial coatings independently made of one or more metal oxides.

8. The UV-Vis cationicly curable security ink according to claim 7, further characterized in that the ink vehicle further comprises one or more machine-readable materials selected from the group consisting of magnetic materials.

9. The UV-Vis radiation cationicly curable security ink according to any of claims 1 to 6, further characterized in that the pigments comprise a non-metallic flake substrate made of one or more materials selected from the group consisting of natural micas, synthetic micas, and glasses.

10. The UV-Vis radiation cationicly curable security ink according to claim 9, further characterized in that the non-metallic substrate comprises one or more at least partial coatings made independently of one or more metal oxides.

11. The UV-Vis cationicly curable security ink according to claim 9 or 10, further characterized in that the ink vehicle further comprises one or more machine-readable materials selected from the group consisting of magnetic materials and infrared-absorbing materials.

12. The UV-Vis cationicly curable security ink according to any of claims 1 to 11, further characterized in that the perfluoropolyethers are functionalized with one or more phosphate-containing groups or one or more silane-containing groups.

13. Use of the UV-Vis cationicly curable security ink as claimed in any of claims 1 to 12 to manufacture one or more security features on a security document or article.

14. A security feature characterized in that it is made of UV-Vis radiation curable security ink as claimed in any of claims 1 to 12.

15. An article characterized in that it comprises a substrate, preferably a substrate selected from the group consisting of papers or other fibrous materials, materials containing paper, glasses, metals, ceramics, plastics and polymers, metallized plastics or polymers, composite materials and mixtures or combinations of two or more of the same, and a radiation-cured coating obtained by UV-Vis radiation curing of UV-Vis radiation-curable screen printing ink as claimed in any of claims 1 to 12.

16. A method for producing the article as claimed in claim 15, characterized in that it comprises the steps of: a. printing by a printing process selected from the group consisting of gravure processes, flexographic processes and screen printing processes, preferably by a screen printing process, the UV-Vis curable security ink as claimed in any of claims 1 to 12, onto the substrate, and b. curing the UV-Vis curable security ink, preferably with one or more light sources selected from the group consisting of mercury lamps, UV-LED lamps and sequences thereof, in order to form one or more security features.