Radiation curable inkjet ink compositions, printed articles, and thermal inkjet methods of using the same

1. A radiation curable inkjet ink composition, comprising:

(A) a mono-ethylenically unsaturated oligomer, wherein the mono-ethylenically unsaturated oligomer (A) is present in an amount of from 8 to 30 wt. %, based on a total weight of the radiation curable inkjet ink composition;

(B) a mono-ethylenically unsaturated monomer, wherein the mono-ethylenically unsaturated monomer (B) is present in an amount of from 20 to 50 wt. %, based on a total weight of the radiation curable inkjet ink composition; and

(C) a solvent;

wherein the radiation curable inkjet ink composition is substantially free of a photoinitiator;

wherein a total weight of the mono-ethylenically unsaturated oligomer (A) is less than or equal to a total weight of the mono-ethylenically unsaturated monomer (B), and

wherein a weight ratio of the mono-ethylenically unsaturated monomer (B) to the mono-ethylenically unsaturated oligomer (A) is 1:1 to 3:1.

2. The radiation curable inkjet ink composition of claim 1 , wherein the solvent (C) is present in an amount of from 30 to 65 wt. %, based on a total weight of the radiation curable inkjet ink composition.

3. The radiation curable inkjet ink composition of claim 1 , wherein the solvent (C) is an organic solvent, or a mixture of at least two organic solvents.

4. The radiation curable inkjet ink composition of claim 1 , further comprising (D) a poly-ethylenically unsaturated component.

5. The radiation curable inkjet ink composition of claim 4 , wherein the poly-ethylenically unsaturated component (D) is present in an amount of from 1 to 20 wt. %, based on a total weight of the radiation curable inkjet ink composition.

6. The radiation curable inkjet ink composition of claim 4 , wherein a weight ratio of the combined weight of the mono-ethylenically unsaturated monomer (B) and the poly-ethylenically unsaturated component (D) to the mono-ethylenically unsaturated oligomer (A) ((B+D)/A) is greater than 1:1 and up to 4:1.

7. The radiation curable inkjet ink composition of claim 4 , wherein the poly-ethylenically unsaturated component (D) is a poly-ethylenically unsaturated monomer (D1), a poly-ethylenically unsaturated oligomer (D2), or a mixture thereof.

8. The radiation curable inkjet ink composition of claim 1 , further comprising (E) an acrylate ester of a carboxylic acid ester of the following formula (I)

wherein R 1 , R 2 , and R 3 are each independently an alkyl, an aryl, an alkylaryl, an alkoxyaryl, or a cycloaliphatic group having 1 to 10 carbon atoms, and R 4 is a group selected from hydrogen, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, phenyl, and alkoxy phenyl.

9. The radiation curable inkjet ink composition of claim 8 , wherein the acrylate ester of a carboxylic acid ester of the formula (I) (E) is present in an amount of from 0.5 to 15 wt. %, based on a total weight of the radiation curable inkjet ink composition.

10. The radiation curable inkjet ink composition of claim 8 , wherein R 1 and R 2 combined have 6 to 8 carbon atoms, R 3 is methyl, and R 4 is hydrogen.

11. The radiation curable inkjet ink composition of claim 8 , wherein a combined weight of the mono-ethylenically unsaturated oligomer (A) and the acrylate ester of a carboxylic acid ester of the formula (I) (E) is less than or equal to a total weight of the mono-ethylenically unsaturated monomer (B).

12. The radiation curable inkjet ink composition of claim 1 , further comprising (F) an anti-kogation agent.

13. The radiation curable inkjet ink composition of claim 1 , further comprising:

(G) a colorant,

at least one additive (H) selected from the group consisting of a surfactant, a stabilizer, an adhesion promoter, and a security taggant, or

a combination thereof.

14. The radiation curable inkjet ink composition of claim 1 , which exhibits a migration level of less than 10 ppb after being cured on an article.

15. A printed article, comprising:

a substrate and a cured ink composition on the substrate, wherein the cured ink composition is Ruined from the radiation curable inkjet ink composition of claim 1 .

16. A method of forming an image on a substrate, comprising:

applying a radiation curable inkjet ink composition onto a surface of the substrate by a thermal inkjet printhead, wherein the radiation curable inkjet ink composition comprises:

(A) a mono-ethylenically unsaturated oligomer, wherein the mono-ethylenically unsaturated oligomer (A) is present in an amount of from 8 to 30 wt. %, based on a total weight of the radiation curable inkjet ink composition;

(B) a mono-ethylenically unsaturated monomer, wherein the mono-ethylenically unsaturated monomer (B) is present in an amount of from 20 to 50 wt. %, based on a total weight of the radiation curable inkjet ink composition; and

(C) a solvent,

wherein the radiation curable inkjet ink composition is substantially free of a photoinitiator,

wherein a total weight of the mono-ethylenically unsaturated oligomer (A) is less than or equal to a total weight of the mono-ethylenically unsaturated monomer (B); and

wherein a weight ratio of the mono-ethylenically unsaturated monomer (B) to the mono-ethylenically unsaturated oligomer (A) is 1:1 to 3:1, and

exposing the radiation curable inkjet ink composition to electron beam radiation to at least partially cure the radiation curable inkjet ink composition to form a cured ink composition on the surface of the substrate.

17. An ink tank, comprising the radiation curable inkjet ink composition of claim 1 .

18. The radiation curable inkjet ink composition of claim 1 , wherein the mono-ethylenically unsaturated oligomer (A) is at least one selected from the group consisting of an acrylate or methacrylate having a straight chain or branched chain, a cyclic alkyl alcohol, and an aromatic acrylic oligomer.

19. The radiation curable inkjet ink composition of claim 1 , wherein the mono-ethylenically unsaturated monomer (B) is at least one selected from the group consisting of an acrylate ester monomer having hydroxyl functionality, an aliphatic or aromatic acrylate ester monomer, and a vinyl ether monomer.

20. The radiation curable inkjet ink composition of claim 19 , wherein the aliphatic or aromatic acrylate ester monomer is at least one selected from the group consisting of an acrylate and (meth)acrylate having a straight chain or a branched chain and a cyclic alkyl alcohol.

21. The radiation curable inkjet ink composition of claim 20 , wherein the cyclic alkyl alcohol comprises from 1 to 20 carbon atoms.