Ink system for cure under low-energy conditions
View Patent ↗UV-curable ink formulations are provided that are capable of being cured under low-energy conditions, such as with a conventional mercury vapor lamp operating at half or less of the lamp's nominal wattage. Methods for forming a printed ink image on a substrate using the ink are also provided, which permit maintenance of relatively high line speeds while consuming less energy due to the use of lower-wattage lamp settings.
1. A UV-curable ink composition comprising:
a monomer system comprising at least one monofunctional monomer and at least one multifunctional monomer;
an oligomer system comprising at least one urethane acrylate oligomer and at least one mercapto modified polyester acrylate;
an acrylate polymer resin;
a pigment; and
an initiator system comprising at least one phosphine oxide photoinitiator, at least one ketone photoinitiator, at least one titanocene photoinitator and at least one amine co-initiator,
wherein said UV-curable ink composition is capable of being cured by exposure to UV light emitted from a lamp operating at 100 W or less at a line speed of at least 50 ft/min.
2. The UV-curable ink composition of claim 1 , said UV-curable ink composition further comprising fumed silica.
3. The UV-curable ink composition of claim 1 , said UV-curable ink composition further comprising methyl diethanolamine (MDEA).
4. The UV-curable ink composition of claim 1 , wherein said monomer system is comprised of mono-, di-, and trifunctional acrylate monomers.
5. The UV-curable ink composition of claim 1 , wherein acrylate polymer resin is a methyl methacrylate/n-butyl methacrylate copolymer resin.
6. The UV-curable ink composition of claim 1 , wherein said monomer system comprises from about 20% to about 60% by weight of said UV-curable ink composition.
7. The UV-curable ink composition of claim 1 , wherein said oligomer system comprises from about 10% to about 40% by weight of said UV-curable ink composition.
8. The UV-curable ink composition of claim 1 , wherein said initiator system comprises from about 2% to about 12% by weight of said UV-curable ink composition.
9. The UV-curable ink composition of claim 1 , said UV-curable ink composition comprising an amide wax.
10. A method for creating an article having a printed ink image thereon comprising the steps of:
printing an ink image onto a substrate using a UV-curable ink composition to form a printed substrate, said UV-curable ink composition comprising—
a monomer system comprising at least one monofunctional monomer and at least one multifunctional monomer;
an oligomer system comprising at least one mercapto modified polyester acrylate;
and an initiator system comprising one or more members selected from the group consisting of phosphine oxide photoinitiators, ketone photoinitiators, and titanocene photoinitators;
passing said printed substrate through a curing station at a rate of at least 50 linear feet per minute to form said article, said curing station comprising at least one lamp that has a rated wattage of at least 200 W, said lamp being operated at 50% or below of its rated wattage while said printed substrate is being passed through said curing station.
11. The method of claim 10 , wherein said monomer system is comprised of mono-, di-, and trifunctional acrylate monomers.
12. The method of claim 10 , wherein said monomer system comprises from about 20% to about 60% by weight of said UV-curable ink composition.
13. The method of claim 10 , wherein said oligomer system further comprises at least one urethane acrylate oligomer.
14. The method of claim 10 , wherein oligomer system comprises between about 10% to about 40% by weight of said UV-curable ink composition.
15. The method of claim 10 , wherein said initiator system comprises between about 2% to about 12% by weight of said UV-curable ink composition.
16. The method of claim 10 , wherein said lamp comprises a mercury-vapor lamp.
17. The method of claim 10 , wherein said step of passing said printed substrate through a curing station exposes said ink composition to an energy level of from about 30 to about 125 mJ.
18. The method of claim 10 , wherein said step of passing said printed substrate through a curing station exposes said ink composition to a power level of from about 400 to about 800 mW.
19. A UV-curable ink composition comprising:
a monomer system comprising at least one monofunctional monomer and at least one multifunctional monomer;
an oligomer system comprising at least one urethane acrylate oligomer and at least one mercapto modified polyester acrylate;
an acrylate polymer resin;
a pigment;
an initiator system comprising at least one phosphine oxide photoinitiator, at least one ketone photoinitiator, at least one titanocene photoinitator and at least one amine co-initiator; and
fumed silica.
20. A UV-curable ink composition comprising:
a monomer system comprising at least one monofunctional monomer and at least one multifunctional monomer;
an oligomer system comprising at least one urethane acrylate oligomer and at least one mercapto modified polyester acrylate;
an acrylate polymer resin;
a pigment;
an initiator system comprising at least one phosphine oxide photoinitiator, at least one ketone photoinitiator, at least one titanocene photoinitator and at least one amine co-initiator; and
methyl diethanolamine (MDEA).
21. A UV-curable ink composition comprising:
a monomer system comprising at least one monofunctional monomer and at least one multifunctional monomer;
an oligomer system comprising at least one urethane acrylate oligomer and at least one mercapto modified polyester acrylate;
a methyl methacrylate/n-butyl methacrylate copolymer resin;
a pigment; and
an initiator system comprising at least one phosphine oxide photoinitiator, at least one ketone photoinitiator, at least one titanocene photoinitator and at least one amine co-initiator.