CONDUCTIVE INK COMPOSITION

Abstract

A conductive ink composition is disclosed comprising conductive solids and a medium, wherein the conductive solids comprise glass flakes coated with an electrically conductive coating. Optionally, the electrically conductive coating may comprise a conductor selected from the group comprising silver, nickel, gold, metal nanoparticles, indium tin oxide, fluorine doped tin oxide. The conductive ink composition may comprise a percentage by weight of glass flakes coated with an electrically conductive coating less than or equal to 50%. Also disclosed is a method of manufacturing the conductive ink composition, a printed article, and a method of manufacturing the printed article.

Claims

1.-16. (canceled)

17. A conductive ink composition comprising conductive solids and a medium, wherein the conductive solids comprise glass flakes coated with an electrically conductive coating.

18. The conductive ink composition of claim 17, wherein the boiling or sublimation temperature of the medium is greater than 10° C. and the melting point of the medium is less than 55° C.

19. The conductive ink composition of claim 17, wherein the medium comprises water or an organic solvent.

20. The conductive ink composition of claim 17, wherein the medium comprises an organic solvent selected from the group consisting of DCM, chloroform, toluene, benzene, an ether, and an alcohol.

21. The conductive ink composition of claim 17, wherein the glass flakes have an aspect ratio of average diameter divided by average thickness of greater than or equal to three.

22. The conductive ink composition of claim 17, wherein the glass flakes have average diameter 10 μm to 540 μm, preferably 30 μm to 400 μm, more preferably 50 μm to 150 μm.

23. The conductive ink composition of claim 17, wherein the glass flakes have an average thickness in a range from 0.1 μm to 8 μm.

24. The conductive ink composition of claim 17, wherein the electrically conductive coating comprises a conductor selected from the group consisting of silver, nickel, gold, metal nanoparticles, indium tin oxide, and fluorine doped tin oxide.

25. The conductive ink composition of claim 17, wherein the conductive ink composition comprises a second conductive particulate material.

26. The conductive ink composition of claim 17, wherein the conductive ink composition comprises a second conductive particulate material selected from the group consisting of graphite, graphene, carbon nanoparticles, and metal nanoparticles.

27. The conductive ink composition of claim 17, wherein the conductive ink composition comprises a binder resin.

28. The conductive ink composition of claim 17, wherein the conductive ink composition comprises a percentage by weight of glass flakes coated with an electrically conductive coating less than or equal to 50%, preferably less than or equal to 30%, more preferably less than or equal to 15%, yet more preferably less than or equal to 10%, even more preferably less than or equal to 5%.

29. A printed article comprising a substrate and a mark, wherein the mark comprises conductive solids, and wherein the conductive solids comprise glass flakes provided with a conductive coating.

30. The printed article of claim 29, wherein the mark is a conductive track.

31. A process of manufacturing a conductive ink composition, comprising steps: a. providing a medium; b. providing conductive solids; and c. dispersing the conductive solids in the medium to provide a conductive ink composition, wherein the conductive solids comprise glass flakes coated with a conductive coating.

32. A process of manufacturing a printed article comprising a substrate and a mark, comprising the steps: a. providing a substrate; b. providing a conductive ink composition comprising a medium and conductive solids; c. marking the substrate with the conductive ink composition; and d. evaporating a portion of the medium to form a printed article bearing a conductive ink residue; wherein the conductive solids comprise glass flakes coated with a conductive coating.

33. The conductive ink composition of claim 17, wherein the glass flakes have an average diameter of from 50 μm to 150 μm and the conductive ink composition comprises a percentage by weight of glass flakes coated with an electrically conductive coating greater than 0 and less than or equal to 30%.

34. The conductive ink composition of claim 17, wherein the glass flakes have an average diameter of from 50 μm to 150 μm and the conductive ink composition comprises a percentage by weight of glass flakes coated with an electrically conductive coating greater than 0 and less than or equal to 5%.

35. The conductive ink composition of claim 33, wherein the glass flakes have an average diameter of 80 μm.

36. The conductive ink composition of claim 34, wherein the glass flakes have an average diameter of 80 μm.

Description

[0052] Preferably, following or during the evaporation of the conductive ink composition medium the ink residue is cured. Preferably, the curing process is sufficient to improve the adherence of the residue to the substrate, the conductive properties of the residue, or a combination of the two. Preferably, the residue is cured using a heat treatment, UV light, or a combination. Heat treatment is a cost effective method of curing the ink residue. Preferably, the heat treatment is between 50° C. and 200° C., more preferably between 80° C. and 120° C. Higher temperature of heat treatment may denature the ink residue or reduce the structural integrity of the substrate. Lower temperature of heat treatment may reduce the effectiveness of the curing process. Preferably, the UV light is produced using a lamp providing UVA radiation, UVB radiation or a combination. Preferably, the curing process is between 4 minutes and 90 minutes. A shorter time may reduce the effectiveness of the curing process. A longer time may reduce the structural integrity of the substrate.

[0053] FIG. 1 shows a graph of the influence of a percentage by weight of glass flakes coated with an electrically conductive coating in the conductive ink composition on the sheet resistance of a glass sheet provided with a coating of the cured conductive ink composition examples.

[0054] FIG. 2 shows surface microscopy images for example 5 (upper left quadrant, A), example 7 (upper right quadrant, B), example 9 (lower left quadrant, C) and example 13 (lower right quadrant, D)

TABLE-US-00001 TABLE 1 Examples of conductive ink compositions Mass % Mass % 30 μm Mass % 80 μm Sheet Graphite Silver coated Silver Coated Resistance Example Ink glass flakes Glass Flakes (ohm/sq) 1 100.00 4.37 2 97.56 2.44 3.34 3 95.24 4.76 2.05 4 90.91 9.09 3.03 5 90.91 9.09 1.86 6 83.33 16.67 2.29 7 83.33 16.67 1.38 8 76.92 23.08 1.33 9 76.92 23.08 0.88 10 71.43 28.57 0.68 11 71.43 28.57 0.59 12 66.67 33.33 0.65 13 66.67 33.33 0.56

[0055] Examples 1 to 13 were prepared by the following process: graphite ink (Gwent Electronic Materials Ltd., Pontypool, UK—Carbon Graphite Ink), silver coated glass flakes (NGF Europe), acetone (1 cm.sup.3) were combined and stirred, solvent evaporated overnight. A glass slide (22 cm wide, 9 cm length) was prepared with two sections of tape (120 μm thick) forming a trough 5 cm in width. A marked slide was produced by the bar casting method, wherein the ink composition comprising graphite particles and silver coated glass flake (2.5 g) was placed on the edge of a glass slide at one end of the trough, and pulled along the trough using a glass rod. Excess ink was removed and the glass plate heated on a hot plate (140 C, 1 hour). Table 1 shows the sheet resistance of the coated glass plate, measured using a four point probe.