Silver compositions and methods for making biocidal currency
View Patent ↗Compositions and methods for making biocidal currency are disclosed. The compositions of the within invention contain biocidal silver or silver compounds, which include elemental silver, nanoparticulate silver, colloidal silver, inorganic silver, including silver oxide, silver compounds and silver salts, that exhibit antibacterial and/or antiviral properties. Ink formulations that are used in the printing of currency, such as offset printing and intaglio printing, which incorporate the biocidal silver are also disclosed. In addition, the biocidal silver is formulated within pulp mixtures during the currency paper or linen-making processes. Methods of employing the biocidal silver or silver compounds of this invention include high pressure engravement printing where the silver impregnates the fiber, being cellulosic fiber, cotton or linen, forming a permanent biocidal layer within or on the surface of the currency, and offset printing.
1 . A gravure printing ink composition, comprising:
a non-aqueous vehicle;
a colorant;
wherein the non-aqueous vehicle comprises a hydrocarbon solvent, wherein the hydrocarbon solvent is present in about 47% by weight with respect to the total content of the ink composition, wherein said colorant comprises channel carbon, wherein the channel carbon is present in about 57% by weight with respect to the total solids content of the ink composition, and said biocidal silver is present.
2 . The gravure printing ink composition of claim 1 , wherein said ink composition comprises about 0.2 ppm to about 100 ppm biocidal silver after drying, measured as the weight of silver.
3 . The gravure printing ink composition of claim 2 , wherein said ink composition comprises about 5 ppm to about 15 ppm biocidal silver after drying, measured as the weight of silver.
4 . An intaglio printing ink composition, comprising:
a non-aqueous vehicle;
an optional co-solvent;
a colorant;
the improvement which comprises adding to said composition a biocidally effective amount of biocidal silver, said biocidal silver being selected from the group consisting of elemental silver, nanoparticulate silver, colloidal silver, and inorganic silver and silver ions; wherein
said biocidally effective amount of biocidal silver is an amount of biocidal silver that results in an amount of silver being present on the surface of a currency substrate after printing that neutralizes or destroys bacteria and viruses;
and wherein said non-aqueous vehicle comprises a hydrocarbon solvent, wherein the hydrocarbon solvent is present in about 47% by weight with respect to the total content of the ink, said colorant comprises channel carbon, wherein the channel carbon is present in about 57% by weight with respect to the total solids content of the ink, and wherein said biocidal silver is present in an amount of from about 0.1 ppm to about 50 ppm measured as the weight of silver.
5 . The intaglio printing ink composition of claim 4 , wherein said ink composition comprises about 0.2 ppm to about 100 ppm biocidal silver after drying, measured as the weight of silver.
6 . The intaglio printing ink composition of claim 5 , wherein said ink composition comprises about 5 ppm to about 15 ppm biocidal silver after drying, measured as the weight of silver.