Method and apparatus for wet trapping with energy-curable flexographic liquid inks
AssigneeSun Chemical Corporation
InventorsMikhail Laksin, Subhankar Chatterjee
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Abstract
The present invention is for a method and associated apparatus whereby low viscosity flexograhic printing inks having a viscosity controlling diluent are used in implementing wet trapping of sequentially applied ink layers by controlling the time between ink layer applications such that sufficient diluent evaporates from an applied layer to increase the first applied layer viscosity sufficiently to wet trap a subsequently applied superposed ink layer.
Claims36
A method for applying multiple ink layers on a substrate, said method comprising:
- A. applying onto said substrate at least one ink layer of an energy curable liquid ink having a viscosity of less than about 4000 cps and comprised of a non-reactive diluent, with each of said at least one applied ink layer having a first viscosity;
- B. evaporating at least a portion of said non-reactive diluent in each of said at least one applied energy curable ink layer, thereby increasing the viscosity of each of said at least one applied energy curable ink layer;
- C. applying onto a last said previously applied ink layer of said energy curable liquid ink, of increased viscosity, at least one layer of a non-energy curable liquid ink having a viscosity lower than said increased viscosity of said last previously applied energy curable ink layer;
- and
- D. fixing each of said applied energy curable and non-energy curable ink layers onto said substrate.
A method for applying multiple ink layers on a substrate, said method comprising:
- A. applying onto said substrate an ink layer of an energy curable liquid ink having a viscosity of less than about 4000 cps and comprised of a non-reactive diluent, said applied ink layer having a first viscosity;
- B. evaporating at least a portion of said non-reactive diluent in said applied energy curable ink layer, thereby increasing the viscosity of said applied energy curable ink layer;
- C. applying onto said previously applied ink layer of said energy curable liquid ink, of increased viscosity, another layer of an energy curable liquid ink having a viscosity lower than said increased viscosity of said previously applied energy curable ink layer;
- and
- D. fixing each said applied energy curable ink layer onto said substrate.
16 The method according to claim 10 further comprising repeating steps B and C one or more times, each time using a different radiant energy curable liquid ink having a viscosity less than about 4,000 cps, to apply an ink layer over a previously applied ink layer, said different ink having a viscosity lower than said increased previously applied ink layer viscosity.
A method for printing multiple ink layers on a substrate, said method comprising selecting a first and a second radiant energy curable liquid flexographic ink, each containing a viscosity controlling diluent comprising water in an amount of about between 5% and 50% by weight, each having a viscosity between about 30 and 70 cps, and sequentially applying said first and said second radiant energy curable liquid flexographic inks on a substrate to form first and second ink layers having superposed portions, wherein said second ink is applied after at least a portion of said diluent in said first ink layer has evaporated.
Apparatus for sequentially applying multiple superposed ink layers on a substrate, the apparatus comprising:
- a substrate path and a substrate drive for driving said substrate along said path;
- a plurality of ink applying stations spaced along said path, said ink applying stations adapted to apply an ink comprising a diluent and having a viscosity less than 2000 cps onto said substrate;
- a control system controlling said substrate transport along said path so that a first liquid ink layer applied onto said substrate at one of said ink stations, increases in viscosity through evaporation of at least some of said diluent from said first ink layer to a viscosity higher than a viscosity of a second ink applied over said first ink layer in a subsequent ink station spaced from said first ink station, to a viscosity sufficient to wet trap said second liquid ink as said substrate is transported between said ink stations.
Dependencies are inferred from the claim text.