Electrostatic ink compositions and scratch-off structures
Disclosed herein is an electrostatic ink composition comprising a component selected from a fatty acid ester having a plurality of hydroxyl substituents and a fatty acid amide having a plurality of hydroxyl substituents. Also described herein are scratch-off structures and methods for producing them.
1. A method for producing a scratch-off structure, the method comprising:
a. providing a substrate having a first layer showing information thereon, and a second layer overlying the first layer, the second layer comprising a polymeric film and being substantially transparent;
b. electrostatically printing a third layer over the second layer, the third layer comprising a transparent electrostatic ink, wherein the transparent electrostatic ink comprises a component selected from a fatty acid ester having a plurality of hydroxyl substituents or a fatty acid amide having a plurality of hydroxyl substituents; and
c. disposing a fourth layer on the third layer, the fourth layer being coloured.
2. The method of claim 1 , wherein the component selected from the fatty acid ester having the plurality of hydroxyl substituents or the fatty acid amide having the plurality of hydroxyl substituents constitutes at least 1 wt % of the solids of the electrostatic ink composition.
3. The method of claim 1 , wherein the component selected from the fatty acid ester having the plurality of hydroxyl substituents or the fatty acid amide having the plurality of hydroxyl substituents constitutes 30 wt % or less of the solids of the electrostatic ink composition.
4. The method of claim 1 , wherein the component selected from the fatty acid ester having the plurality of hydroxyl substituents or the fatty acid amide having the plurality of hydroxyl substituents comprises from 4 to 40 carbon atoms.
5. The method of claim 1 , wherein the component selected from the fatty acid ester having the plurality of hydroxyl substituents or the fatty acid amide having the plurality of hydroxyl substituents comprises a saturated fatty acid, an unsaturated fatty acid, a straight-chain fatty acid, a branched fatty acid, a cyclic fatty acid, or a mixture thereof.
6. The method of claim 1 , wherein the fatty acid ester is the product of esterification of a plurality of fatty acids with a polyol, wherein the plurality of fatty acids may be the same or different from one another.
7. The method of claim 1 , wherein the fatty acid ester is a mono-, di-, or triglyceride.
8. The method of claim 7 , wherein the fatty acid ester is a di- or triglyceride and each fatty acid chain comprises at least one hydroxyl substituent.
9. The method of claim 1 , wherein the component selected from the fatty acid ester having the plurality of hydroxyl substituents or the fatty acid amide having the plurality of hydroxyl substituents comprises a hydrogenated castor oil.
10. The method of claim 1 , wherein the transparent electrostatic ink further comprises:
a. a resin;
b. a carrier liquid; and
c. a charge director and/or charge adjuvant.
11. The method of claim 10 , wherein the resin is a thermoplastic resin having acidic side groups.
12. A scratch-off structure comprising the following layers in order:
a. a substrate having a first layer showing information thereon;
b. a second layer comprising a polymeric film and being substantially transparent;
c. a third layer comprising a transparent electrostatic ink, wherein the transparent electrostatic ink comprises a component selected from a fatty acid ester having a plurality of hydroxyl substituents or a fatty acid amide having a plurality of hydroxyl substituents; and
d. a fourth layer, wherein the fourth layer is coloured.
13. The scratch-off structure according to claim 12 , wherein the component selected from the fatty acid ester having the plurality of hydroxyl substituents or the fatty acid amide having the plurality of hydroxyl substituents comprises a hydrogenated castor oil.
14. The scratch-off structure of claim 12 , wherein the component selected from the fatty acid ester having the plurality of hydroxyl substituents or the fatty acid amide having the plurality of hydroxyl substituents constitutes at least 1 wt % of the solids of the electrostatic ink composition.
15. The scratch-off structure of claim 12 , wherein the component selected from the fatty acid ester having the plurality of hydroxyl substituents or the fatty acid amide having the plurality of hydroxyl substituents constitutes 30 wt % or less of the solids of the electrostatic ink composition.
16. The scratch-off structure of claim 12 , wherein the component selected from the fatty acid ester having the plurality of hydroxyl substituents or the fatty acid amide having the plurality of hydroxyl substituents comprises from 4 to 40 carbon atoms.
17. The scratch-off structure of claim 12 , wherein the component selected from the fatty acid ester having the plurality of hydroxyl substituents or the fatty acid amide having the plurality of hydroxyl substituents comprises a saturated fatty acid, an unsaturated fatty acid, a straight-chain fatty acid, a branched fatty acid, a cyclic fatty acid, or a mixture thereof.
18. The scratch-off structure of claim 12 , wherein the fatty acid ester is the product of esterification of a plurality of fatty acids with a polyol, wherein the plurality of fatty acids may be the same or different from one another.
19. The scratch-off structure of claim 12 , wherein the fatty acid ester is a mono-, di-, or triglyceride.
20. The scratch-off structure of claim 19 , wherein the fatty acid ester is a di- or triglyceride and each fatty acid chain comprises at least one hydroxyl substituent.
21. The scratch-off structure of claim 12 , wherein the transparent electrostatic ink further comprises:
a. a resin;
b. a carrier liquid; and
c. a charge director and/or charge adjuvant.
22. The scratch-off structure of claim 21 , wherein the resin is a thermoplastic resin having acidic side groups.