Liquid ink containing polytetrafluoroethylene wax emulsion

Abstract

An example of a liquid ink includes a pigment dispersion, a polyurethane dispersion, a polytetrafluoroethylene wax emulsion, a co-solvent, and a balance of water. A particle diameter of a polytetrafluoroethylene wax in the polytetrafluoroethylene wax emulsion is less than 50 nm. Examples of the liquid ink may be incorporated into a thermal inkjet printing system.

1 .- 8 . (canceled) 
     
     
         9 . An over-print varnish, comprising:
 a polyurethane dispersion;   a polytetrafluoroethylene wax emulsion, wherein a particle diameter of a polytetrafluoroethylene wax in the polytetrafluoroethylene wax emulsion is less than 50 nm;   a co-solvent; and   a balance of water.   
     
     
         10 . The over-print varnish as defined in  claim 9  wherein the polytetrafluoroethylene wax emulsion is present in the over-print varnish in an amount ranging from about 0.25% actives to about 1% actives. 
     
     
         11 . The over-print varnish as defined in  claim 9  wherein
 the polyurethane dispersion is selected from the group consisting of an aromatic polyether polyurethane dispersion, an aliphatic polyether polyurethane dispersion, an aromatic polyester polyurethane dispersion, an aliphatic polyester polyurethane dispersion, an aromatic polycaprolactam polyurethane dispersion, an aliphatic polycaprolactam polyurethane dispersion, a vinyl-urethane hybrid polymer dispersion, an acrylic-urethane hybrid polymer dispersion, a dispersion of co-polymers thereof, and a combination thereof. 
 
     
     
         12 . The over-print varnish as defined in  claim 9 , further comprising
 a surfactant in an amount ranging from about 0.25 wt % to about 4 wt %.   
     
     
         13 .- 15 . (canceled) 
     
     
         16 . The over-print varnish as defined in  claim 12  wherein the surfactant includes:
 a phosphate surfactant present in an amount ranging from about 0.25 wt % to about 2 wt %; and 
 an acetylenic surfactant present in an amount ranging from about 0.25 wt % to about 2 wt %. 
 
     
     
         17 . The over-print varnish as defined in  claim 9  wherein the polyurethane dispersion is present in the over-print varnish in an amount ranging from about 1 actives to about 15% actives. 
     
     
         18 . The over-print varnish as defined in  claim 9  wherein the co-solvent is a glycol ether, a humectant, or a combination thereof. 
     
     
         19 . The over-print varnish as defined in  claim 9  wherein the co-solvent is present in the over-print varnish in an amount ranging from about 2 wt % to about 20 wt %. 
     
     
         20 . The over-print varnish as defined in  claim 9 , further comprising an additive selected from the group consisting of an antimicrobial agent, an anti-kogation agent, or a combination thereof. 
     
     
         21 . The over-print varnish as defined in  claim 9  wherein the particle diameter of the polytetrafluoroethylene wax ranges from about 10 nm to less than 50 nm. 
     
     
         22 . The over-print varnish as defined in  claim 9  wherein the over-print varnish is free of a colorant. 
     
     
         23 . A thermal inkjet printing system, comprising:
 an over-print varnish including:
 a polyurethane dispersion; 
 a polytetrafluoroethylene wax emulsion, wherein a particle diameter of a polytetrafluoroethylene wax in the polytetrafluoroethylene wax emulsion is less than 50 nm; 
 a co-solvent; and 
 a balance of water; and 
   a thermal inkjet printhead including at least one thermal inkjet print nozzle.   
     
     
         24 . The thermal inkjet printing system as defined in  claim 23  wherein the polytetrafluoroethylene wax emulsion of the over-print varnish is present in the over-print varnish is an amount ranging from about 0.25% actives to about 1% actives. 
     
     
         25 . The thermal inkjet printing system as defined in  claim 23  wherein the thermal inkjet printhead contains the over-print varnish. 
     
     
         26 . The thermal inkjet printing system as defined in  claim 23  wherein the particle diameter of the polytetrafluoroethylene wax ranges from about 10 nm to less than 50 nm. 
     
     
         27 . The thermal inkjet printing system as defined in  claim 23  wherein the polyurethane dispersion of the over-print varnish is selected from the group consisting of an aromatic polyether polyurethane dispersion, an aliphatic polyether polyurethane dispersion, an aromatic polyester polyurethane dispersion, an aliphatic polyester polyurethane dispersion, an aromatic polycaprolactam polyurethane dispersion, an aliphatic polycaprolactam polyurethane dispersion, a vinyl-urethane hybrid polymer dispersion, an acrylic-urethane hybrid polymer dispersion, a dispersion of co-polymers thereof, and a combination thereof, and wherein the polyurethane dispersion is present in the over-print varnish in an amount ranging from about 1% actives to about 15% actives. 
     
     
         28 . The thermal inkjet printing system as defined in  claim 23  wherein the over-print varnish is free of a colorant. 
     
     
         29 . The thermal inkjet printing system as defined in  claim 23  wherein the co-solvent of the over-print varnish is a glycol ether, a humectant, or a combination thereof, and wherein the co-solvent is present in the over-print varnish in an amount ranging from about 2 wt % to about 20 wt %. 
     
     
         30 . The thermal inkjet printing system as defined in  claim 23  wherein the over-print varnish further includes a surfactant in an amount ranging from about 0.25 wt % to about 4 wt % 
     
     
         31 . The thermal inkjet printing system as defined in  claim 23  wherein the over-print varnish further includes an additive selected from the group consisting of an antimicrobial agent, an anti-kogation agent, or a combination thereof.