Non-aqueous ink

Abstract

[Problem to be solved] A non-aqueous ink, which has excellent pigment dispersion stability and can achieve reduction or elimination of print-through, thereby achieving high print density, is disclosed.[Solution] The non-aqueous ink contains at least a pigment and an organic solvent, wherein the organic solvent contains a five-membered heterocyclic compound having a C═O bond in an amount of 50 mass % or more of the organic solvent, and the content of a polymer component in the ink is 20 mass % or less relative to the pigment.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a non-aqueous ink that is suitable for use with an inkjet recording system, and more particularly to a non-aqueous ink that provides an excellent effect of reducing or eliminating print-through (striking-through), thereby achieving high print density.[0003]2. Description of the Related Art[0004]An inkjet recording system ejects a highly fluid inkjet ink as an ink particle from a very thin head nozzle to record an image on printing paper, which is positioned to face the nozzle. Because of low noise and ability of high-speed printing, the inkjet recording systems are rapidly becoming widely used in recent years. As inks for use with the inkjet recording systems, various types of so-called non-aqueous pigment inks, which are formed by finely dispersing a pigment in a non-water-soluble solvent, are proposed.[0005]For example, the applicant of the present application has proposed, in Japanese...

AI Technical Summary

Benefits of technology

[0007]However, in the case where the polymer component is added in the ink, the pigment tends to penetrate into the printing paper together with the polymer component after the ink is transferred onto the printing paper, because of high affinity between the pigment and the polymer component or bonding between the pigment and the polymer component. This may result in low print density on the surface of the printing paper and print-through of the ink. That is, in the case where the dispersion of the pigment is achieved by using the polymer, an attempt to increase the pigment dispersibility increases tendency of the low print density and the print-through, and an attempt to increase the print density and reduce the print-through decreases the pigment dispersibility, i.e., there is a trade-off between the pigment dispersibility and the reduction of print-through.

[0008]In view of the above-described circumstances, the present invention is directed to providing a non-aqueous ink that has excellent pigment dispersion stability and can reduce or eliminate the print-through of the ink, thereby achieving high print density.

[0019]The non-aqueous ink of the invention contains a five-membered heterocyclic compound having a C═O bond in an amount of 50 mass % or more of the organic solvent. Therefore, even the ink contains a polymer component, which provides high pigment dispersibility, in an amount of 20 mass % or less relative to the pigment, both the pigment dispersion stability and the reduction or elimination of print-through can be achieved, and the improved reduction or elimination of print-through provides a non-aqueous ink that achieves high print density.

Problems solved by technology

This may result in low print density on the surface of the printing paper and print-through of the ink.