1. Technical Field
The present invention relates to a photocurable ink composition, an ink jet recording method using the same, and a recorded material.
2. Related Art
A photocurable ink composition is used for manufacture of a color filter, printing on a printed board, printing on a plastic card, a vinyl sheet or a plastic component, printing of a large-sized signboard or an indoor/outdoor advertisement, or printing of a barcode or a date.
Japanese Unexamined Patent Application No. 2004-99796 discloses a photocurable ink composition including dendrimer which is a kind of dendritic polymer. The dendritic polymer has a molecule structure in which a functional group is dense in the surface with high density compared with a general linear polymer and thus is expected as a functional polymer nano material.
However, if the dendritic polymer is added to the ink composition, the viscosity of an ink is significantly increased and thus, even in view of storage stability, a discharge failure of an ink jet head may occur due to the increase of the viscosity. In order to suppress the increase of the viscosity, the reduction of the addition amount of the dendritic polymer has a tradeoff relation with the characteristic improvement due to the adding of the dendritic polymer.
As a general method of preventing the high viscosity of the ink, there is a method of using a low-viscosity polymerizable compound as a diluted monomer. However, the low-viscosity monomer generally has a low molecular weight, a low flash point, and problems in stability, such as odor and skin irritability. As another method, water or an organic solvent without polymerizable functional group as a low-viscosity dilution agent is added. However, when a component which does not contribute to a curing reaction is added, a drying process should be performed by a heating or ventilating unit as a pre-process of the curing reaction, or a special process of providing an absorbing layer on a recording medium needs to be performed. Accordingly, a process load is undesirably increased. When the curing reaction is performed in a state in which the drying process is insufficient, a residual solvent or residual moisture is foamed by heat of polymerization or is extruded from a cured material, is bled out and is left on the surface of the cured film, thereby causing tackiness (stickiness).