Method and media for printing aqueous ink jet inks on plastic surfaces
View Patent ↗Single coatings onto non-absorbent substrates on which aqueous ink jet inks are jetted with subsequent application of heat, without the use of reactive species in the ink and in the media used as a substrate coating. The heating rapidly drives the water of the ink into the coating, with the rest of the water from the ink being lost by evaporation. The material is then subject to immediate application of a sealing lacquer, which is preferably water-based and which may be dried and possibly cross-linked by heat to give a very resistant surface.
1. A method of producing ink jet printed images with high resistance to physical and chemical damage on plastic surfaces, comprising the steps of:
a. providing a plastic object;
b. coating at least part of the surface of the plastic object with an under-coating solution that does not contain a reactive species;
c. evaporating off the volatile part of the under-coated solution, thus depositing a solid film on the surface of the plastic object;
d. providing at least one ink-jet ink comprising a colorant and aqueous carrier;
e. jetting the ink by means of an ink-jet system onto the surface of the under-coating on the plastic object;
f. warming the printed surface to drive part of the water in the ink into the under-coating and to evaporate the remaining part of the water;
g. over-coating the dried surface with a water-based coating; and
h. heating the over-coating to dry or cure it and to seal-in the previously deposited ink and under-coating.
2. The method of claim 1 , wherein the under-coating solution contains a mixture of hydrophilic polymer or polymers together with a hydrophobic polymer; and
wherein none of the polymers in the undercoating react with other polymers in the undercoating.
3. The method of claim 1 , wherein the ink-jet ink colorant is a dye or a pigment.
4. The method of claim 1 , wherein the plastic object is a card or a bottle.
5. The method of claim 1 where the plastic object is composed of a polyester or polyvinyl chloride.
6. The method of claim 1 , wherein said water-based coating for over-coating comprises water-soluble amino-plasts and acid catalysts.
7. The method of claim 1 , wherein said water-based coating for over-coating comprises water-based emulsions or a water-based emulsion plus alkali.
8. The method of claim 1 , performed as a single composite action, which is automated to the extent that at no stage involves human handling.
9. The method according to claim 8 , wherein a plastic bottle is under-coated, imaged and over-coated.
10. The method according to claim 1 , wherein no chemical reaction occurs.
11. The method according to claim 1 , wherein the under-coating is dried in sheet form for subsequent imaging and over-coating.
12. The method according to claim 11 , wherein a plastic card is under-coated, imaged and over-coated.
13. The method according to claim 1 , wherein a plastic card is coated and imaged.
14. The method according to claim 1 , wherein a plastic bottle is coated and imaged.
15. The method according to claim 14 , wherein said ink-jet image comprises a color image, additionally comprising a white under-layer, said color image viewable without influence of any contents of said bottle.
16. An object imaged according to the method of claim 1 , wherein the image surface is resistant to at least 100 strokes of the Crockmeter, dry or in contact with solvents, thus exhibiting high physical and chemical resistance.