A non-aqueous ink for inkjet printing comprises an organic solvent, a binder resin, and a pigment as main components. As the binder resin, it is proposed to use resin particles having a core composed of C1-4 alkyl ester of a poly(meth)acrylic acid and a shell composed of C4-10 alkyl ester of a poly(meth)acrylic acid (Patent Document 1). The use of the resin particles achieves a higher solid content at a lower viscosity than the use of a binder resin dissolved in a solvent, improving fixing property of a pigment. However, the resin particles are not capable of dispersing a pigment. Consequently, a pigment dispersant should be used. However, the addition of a pigment dispersant to an ink causes the ink to wet a nozzle plate better, allowing more pigment particles to remain on the nozzle plate. The pigment particles stuck to the nozzle plate damage the nozzle plate when the nozzle plate is wiped in a cleaning process, resulting in degraded wiping durability. In addition, image density is lowered because less pigment particles are fixed on paper.
As a means to solve above problem, a resin particle having pigment dispersing capability is proposed, which resin particle is composed of a copolymer of C12-25 alkyl ester of poly(meth)acrylic acid with acrylic monomer having a specific group such as glycidyl group (Patent Document 2).
USPTO Backgrounds
USPTO Backgrounds