According to one embodiment, an inkjet ink includes a non-conductive metal pigment, a resin, and a solvent, and the surface of the non-conductive metal pigment is coated with an alkoxide including an alkoxysilane, and the coating film has a crosslinked structure.
1. An inkjet ink, comprising a non-conductive metal pigment, a resin, and a solvent, wherein
the average particle diameter of the non-conductive metal pigment is 0.4 or more and less than 0.95 μm,
the surface of the non-conductive metal pigment is coated with a coating film made of an alkoxide including an organoalkoxysilane having a structure represented by the following general formula (2a) and an organoalkoxysilane having a structure represented by the following general formula (2b),
the coating film has a crosslinked structure,
a glossiness of an image on a medium obtained by printing is in the range from 352 to 435 at an incident angle of 20,
an average number of print missing lines at ±2 V is in the range from 0.2 to 2, and
a fixability to a printed media is equal to the state that the print is partially erased at a rubbing test for color fastness;
R 1 —Si—(OR 3 ) 3 (2a)
wherein R 1 in the general formula (2a) represents a monovalent group having a (meth)acryl group, R 3 in the general formula (2a) represents a monovalent alkyl group having 1 to 4 carbon atoms,
R 1 —Si—(OR 3 ) 3 (2b)
wherein R 1 in the general formula (2b) represents a monovalent group having a functional group selected from a glycidoxy group, and an epoxycycloalkyl group having 5 or 6 carbon atoms, R 3 in the general formula (2b) represents a monovalent alkyl group having 1 to 4 carbon atoms.
2. The ink according to claim 1 , wherein the ratio of the addition amount of the resin to that of the non-conductive metal pigment is from 0.3 to 1 part with respect to 1 part of the pigment.
3. The ink according to claim 1 , wherein the alkoxide further includes organoalkoxysilane having a structure represented by the following general formula (2):
R 1 R 2 a —Si—(OR 3 ) 3-a (2)
wherein R 1 in the general formula 2 represents a monovalent group having a hydrogen atom or a functional group selected from an alkyl group, an alkenyl group, an amino group, a mercapto group, and an isocyanate group; R 2 represents a group selected from an alkyl group having 1 to 4 carbon atoms and a phenyl group; R 3 represents a monovalent alkyl group having 1 to 4 carbon atoms; and a represents 0, 1, or 2.
4. The ink according to claim 3 , wherein the non-conductive metal pigment has an electrical conductivity of 10 −13 (Ω·cm) −1 or less.
5. The ink according to claim 3 , wherein the addition amount of the alkoxide is 1 to 3 times the smallest amount for coating the surface of the metal pigment, which is taken as 1.
6. The ink according to claim 3 , wherein the resin is at least one resin selected from an acrylic resin, a polyester resin, a phenolic resin, a polyamide, polyvinyl butyral, cellulose acetate butyrate, a nitrocellulose resin, a polyurethane, a vinyl chloride-vinyl acetate copolymer, and a resin emulsion thereof.
7. The ink according to claim 3 , wherein the non-conductive metal pigment is a metal composed mainly of aluminum.
8. The ink according to claim 3 , wherein the non-conductive metal pigment has a scaly shape.
9. The ink according to claim 3 , wherein the addition amount of the resin is from 0.3 mass % to 1 mass %.
10. The ink according to claim 3 , wherein the addition amount of the non-conductive metal pigment is at least 0.5 mass % or more.
11. The ink according to claim 3 , wherein the alkoxide further includes a metal alkoxide represented by the following general formula (3):
wherein M represents an atom of Ti, Zr or Al; R 4 represents an alkyl group having 1 to 10 carbon atoms; b represents 0 or 1; and n represents a number of 1 to 20.
12. The ink according to claim 11 , wherein the addition amount of the alkoxide is 1 to 3 times the smallest amount for coating the surface of the metal pigment, which is taken as 1.
13. The ink according to claim 3 , wherein the solvent is an organic solvent having no active hydrogen, and is at least one organic solvent selected from an aliphatic hydrocarbon, an aromatic hydrocarbon, a halogenated hydrocarbon, an organic acid ester, an ether, and a ketone.
14. The ink according to claim 13 , wherein the non-conductive metal pigment has an electrical conductivity of 10 −13 (Ω·cm) −1 or less.
15. The ink according to claim 13 , wherein the addition amount of the alkoxide is 1 to 3 times the smallest amount for coating the surface of the metal pigment, which is taken as 1.