Coating composition for producing magnetically induced images
View Patent ↗The present invention is related to a coating composition for the production of a magnetically induced image, consisting of volatile components (S) and non-volatile components, the latter consisting of an ink vehicle (I) and magnetically orientable optically variable interference pigment (P), to a process for manufacturing the coating composition, and to the use of the composition for the production of a magnetically induced image coating on a substrate with the help of applied magnetic fields. Said magnetically induced image coating may be used as a security device on value- or identity documents, brand protection labels and the like.
1. Coating composition for producing a magnetically induced image, consisting of volatile components (S) and nonvolatile components, the non-volatile components consisting of an ink vehicle (I) and magnetically orientable optically variable interference pigment (P), wherein the ratio of the volume of the ink vehicle (V(I)) to the volume of the pigment (V(P)) is higher than 5.0, and that said coating composition is a printing ink selected from the group consisting of flexographic printing inks, gravure printing inks, silkscreen printing inks and roller coating inks.
2. Coating composition according to claim 1 , wherein said non-volatile components are present in an amount greater than 50% per weight of the total composition.
3. Coating composition according to claim 1 , wherein said non-volatile components are present in an amount greater than 80% per weight of the total composition.
4. Coating composition according to claim 1 , wherein said volatile components are selected from the group consisting of organic solvents, water, and mixtures thereof.
5. Coating composition according to claim 1 , wherein said magnetically orientable optically variable pigment is selected from the group consisting of vacuum deposited magnetic thin film interference pigments, interference coated metallic pigments, interference coated non-metallic pigments, magnetic liquid crystal pigments, and mixtures thereof.
6. Coating composition according to claim 5 , wherein said magnetically orientable interference pigment is selected from the group consisting of five-layer and seven-layer vacuum deposited magnetic thin film interference pigment.
7. Coating composition according to claim 1 , wherein said magnetically orientable interference pigment has a mean diameter d50 in the range of 5 μm to 40 μm.
8. Coating composition according to claim 1 , wherein said magnetically orientable interference pigment has a mean diameter d50 in the range of 15 μm to 25 μm.
9. Coating composition according to claim 1 , wherein said magnetically orientable interference pigment has a thickness in the range of 0.1 μm to 6 μm.
10. Coating composition according to claim 1 , wherein said magnetically orientable interference pigment has a thickness in the range of 0.5 μm to 3 μm.
11. Process for manufacturing a coating composition for producing a magnetically induced image according to claim 1 , said process comprising of mixing together volatile components (S), and non-volatile components, the non-volatile components consisting of an ink vehicle (I) and of magnetically orientable optically variable interference pigment (P), wherein the ratio of the volume of the ink vehicle (V(I)) to the volume of the pigment (V(P)) is higher than 5.0, and that said coating composition is a printing ink selected from the group consisting of flexographic printing inks, gravure printing inks, silkscreen printing inks and roller coating inks.
12. Process according to claim 11 , wherein said nonvolatile components are present in an amount greater than 50% per weight of the total composition.
13. Process according to claim 11 , wherein said nonvolatile components are present in an amount greater than 80% per weight of the total composition.
14. Process according to claim 11 , wherein said volatile components (S) are selected from the group consisting of organic solvents, water, and mixtures thereof.
15. Process according to claim 11 , wherein said magnetically orientable optically variable pigment is selected from the group consisting of vacuum deposited magnetic thin film interference pigments, interference coated metallic pigments, interference coated non-metallic pigments, magnetic liquid crystal pigments, and mixtures thereof.
16. Process according to claim 15 , wherein said magnetically orientable interference pigment is selected from the group consisting of five-layer and seven-layer vacuum deposited magnetic thin film interference pigment.
17. Process according to claim 11 , wherein said magnetically orientable interference pigment has a mean diameter d50 in the range of 5 μm to 40 μm.
18. Process according to claim 11 , wherein said magnetically orientable interference pigment has a mean diameter d50 in the range of 15 μm to 25 μm.
19. Process according to claim 11 , wherein said magnetically orientable interference pigment has a thickness in the range of 0.1 μm to 6 μm.
20. Process according to claim 11 , wherein said magnetically orientable interference pigment has a thickness in the range of 0.5 μm to 3 μm.
21. Process of producing a magnetically induced image comprising (a) applying a coating composition according to claim 1 to a substrate surface, (b) orienting the magnetic pigment particles in the applied coating composition of (a) by applying a magnetic field, and (c) curing/drying the oriented coating composition of step (b) to fix the particles in the oriented positions.
22. Process according to claim 21 , wherein said orienting (b) is performed simultaneously with said applying a coating (a).
23. Process according to claim 21 , wherein said orienting (b) is performed subsequently to said applying a coating (a).
24. Process according to claim 21 , wherein said curing/drying (c) is carried out by a process selected from the group consisting of physical evaporation of volatile compounds, UV-curing, oxidative reticulation, chemical crosslinking, electron beam curing, or any combination thereof.