Smooth finish UV ink system and method
A printing method includes steps of applying an ink-receptive coating to a substrate; printing an actinic radiation-curable ink jet ink over the coating; and curing the printed ink jet ink. An article printed by the method has a ink-receptive coating layer with a cured print. An apparatus for carrying out the method includes a coating station at which the ink-receptive coating is applied to a substrate, an ink jet printhead at which the energy-curable ink jet ink is applied, and a source of actinic radiation for curing the applied ink. The ink may be applied in sufficient amount to achieve a color density comparable to that obtained using other printing processes such as flexographic or gravure printing processes. The ink-receptive coating layer may be of a thickness sufficient to provide improve surface smoothness and/or reduced drop spread relative to an uncoated substrate.
1 . A printing method, comprising steps of
(a) applying an ink-receptive coating to a substrate;
(b) printing an actinic radiation-curable ink jet ink over the coating; and
(c) curing the printed ink jet ink.
2 . A printing method according to claim 1 , wherein the ink jet ink is printed in sufficient amount to achieve a color density comparable to that obtained using a flexographic or a gravure printing process.
3 . A printing method according to claim 1 , wherein the ink-receptive coating has a thickness sufficient to provide improve surface smoothness or reduced drop spread, or both, relative to an uncoated substrate.
4 . A printing method according to claim 1 , wherein the substrate is nonabsorbent or semi-nonabsorbent.
5 . A printing method according to claim 1 , wherein the ink-receptive coating comprises a member selected from the group consisting of highly porous silica, porous inorganic oxides, silica gels,, and combinations thereof.
6 . A printing method according to claim 1 , wherein the ink-receptive coating comprises an inorganic oxide having a pore volume of at least about 0.6 cc/g.
7 . A printing method according to claim 1 , wherein the ink-receptive coating comprises a microporous material having an average particle size in the range of 1 to 20 microns.
8 . A printing method according to claim 1 , wherein the ink-receptive coating is cured by exposure to actinic radiation.
9 . A printing method according to claim 8 , wherein photoinitiator in the coating increases the rate of cure or extent of cure, or both, of the ink
10 . A printing method according to claim 1 , wherein the ink-receptive coating is thermoset.
11 . A printing method according to claim 1 , wherein the ink-receptive coating vehicle provides a desired property selected from the group consisting of flexibility, durability, adhesion to the substrate, water resistance, solvent resistance and combinations thereof.
12 . A printing method according to claim 1 , comprising a further step of:
(d) applying over the cured ink jet ink a protective coating.
13 . A printing method according to claim 12 , wherein the protective coating is cured after being applied.
14 . A printing apparatus, comprising
a coating station at which an ink-receptive coating is applied to a substrate,
an ink jet printhead that applies an energy-curable ink jet ink on the coating, and
a source of actinic radiation for curing the applied ink.
15 . An apparatus according to claim 14 , wherein the coating station includes a source of actinic radiation for curing the coating.
16 . An apparatus according to claim 14 , wherein the coating station includes a heater for at least partially drying the coating.
17 . An apparatus according to claim 14 , comprising more than one ink jet printhead.
18 . An apparatus according to claim 17 , wherein one printhead applies a clear, radiation-curable ink jet ink.
19 . An apparatus according to claim 14 , further comprising a coating station that applies a clear, protective coating over applied the ink jet ink.
20 . An article printed by the method of claim 1.