1. Field of the Invention
The present invention relates to a printing apparatus and a printed material manufacturing method.
2. Description of the Related Art
In conventional inkjet recording apparatuses, it is difficult to improve throughput for high-speed printing because a shuttle head that shuttles in a width direction of a recording medium, such as a sheet of paper or a film, is generally used. Therefore, in recent years, to cope with the high-speed printing, a single-pass system has been proposed, in which a plurality of heads are arranged so as to cover the entire width of the recording medium and enable printing with the heads at once.
However, while the single-pass system is advantageous to increase print speed, a time interval between dropping of adjacent dots is short and an adjacent dot is dropped before the ink of a previously-dropped dot penetrates into the recording medium. Therefore, coalescence of the adjacent dots (in other words, droplet interference) occurs, so that beading or bleed may occur with which the image quality is reduced.
Furthermore, if an inkjet printing apparatus prints an image on an impermeable medium or a low-permeable medium, such as a film or a coated paper, adjacent dots move and coalesce together, resulting in an image failure, such as beading or bleed. As a conventional technology to solve the above situations, some methods have been proposed; for example, a method to apply primer to a recording medium in advance to improve the cohesiveness and the fixability of ink and a method to use ultraviolet (UV) curable ink.
However, in the method to apply primer to the print media in advance, it is necessary to evaporate and dry moisture of the primer in addition to moisture of the ink. Therefore, a longer drying time or a larger drying device is needed. Furthermore, because the primer is a supply, printing costs increase. Moreover, if a treatment liquid is a highly acidic liquid, irritating odor of the liquid may become a problem. In the method to use the UV curable ink, the cost for the UV curable ink is higher than the cost for aqueous ink, so that printing costs further increase. Furthermore, the UV curable ink itself initiates a chemical reaction and is cured; therefore, while the weather resistance and the resistance against flaking can be improved, the reaction needs to be controlled with higher accuracy and handling becomes difficult.