Radiation curable inkjet fluids and inks improved for photoyellowing

1. A radiation curable inkjet fluid comprising:

a radiation curable composition including at least 25 wt % of a vinylether acrylate and at least 15 wt % of a polymerizable compound including at least three acrylate groups, each wt % being based upon a total weight of the radiation curable composition; and

a photoinitiator including a tertiary amine group and 0 to 3 wt % of isopropylthioxanthone based upon a total weight of the radiation curable inkjet fluid.

2. The radiation curable inkjet fluid according to claim 1 , wherein the vinylether acrylate is a radiation curable monomer represented by Formula (I):

wherein,

R 1 represents hydrogen, or a substituted or unsubstituted alkyl group;

L represents a linking group including at least one carbon atom;

X represents O, S, or NR 2 wherein R 2 has the same meaning as R 1 ; when X =NR 2 , L

and R 2 may form together a ring system; and

n and m independently represent a value from 1 to 5.

3. The radiation curable inkjet fluid according to claim 2 , wherein R 1 represents hydrogen, X represents O, and n represents a value of 1.

4. The radiation curable inkjet fluid according to claim 3 , wherein the radiation curable monomer represented by Formula (I) is:

5. The radiation curable inkjet fluid according to claim 1 , wherein the polymerizable compound including the at least three acrylate groups is trimethylolpropane triacrylate.

6. The radiation curable inkjet fluid according to claim 1 , wherein the polymerizable compound includes 4, 5, or 6 acrylate groups.

7. The radiation curable inkjet fluid according to claim 1 , wherein the photoinitiator including the tertiary amine group includes at least one morpholino group.

8. The radiation curable inkjet fluid according to claim 1 , wherein the photoinitiator including the tertiary amine group includes at least one α-aminoalkylphenone group.

9. A radiation curable inkjet ink comprising:

the radiation curable inkjet fluid according to claim 1 ; and

a pigment dispersion including a pigment and a polymeric dispersant.

10. The radiation curable inkjet ink according to claim 9 , wherein the pigment includes a β-copper phthalocyanine pigment.

11. The radiation curable inkjet ink according to claim 9 , wherein the pigment includes a white pigment.

12. An inkjet printing method comprising the steps of:

providing the radiation curable inkjet fluid according to claim 1 ; and

applying the radiation curable inkjet fluid to a substrate.