Stock material or miscellaneous articles – Ink jet stock for printing – Plural ink receptive layers
Reexamination Certificate
2001-07-19
2004-01-13
Hess, Bruce H. (Department: 1774)
Stock material or miscellaneous articles
Ink jet stock for printing
Plural ink receptive layers
C428S032300, C428S032340, C428S032370
Reexamination Certificate
active
06677006
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a recording material for ink-jet printing process. In particular, the invention is concerned with an ink-jet recording material that can ensure very excellent light-resistant properties in images recorded therein and can provide images of excellent coloration quality when ink-jet printing in color is done thereon by the use of not only dye ink but also pigment ink.
BACKGROUND OF THE INVENTION
Ink-jet recording methods can easily achieve full-color recording and reduction of printing noises. In recent years, therefore, the utilization of ink-jet recording methods has been spreading at a rapid rate. According to such a method, fine drops of ink are jetted from nozzles at a high speed so as to direct toward a recording material, and a large quantity of solvent is contained in the ink used. As a result, recording materials for ink-jet recording are required to absorb ink promptly.
The recent years have also seen rapid proliferation of personal computers and digital cameras. Under these circumstances, printers as apparatus for outputting such digital image information have come to be required to produce images having qualities on a level similar to those attained by silver salt photography. Thus, it has also become necessary for ink-jet recording materials used in such printers to ensure colors of higher densities, higher resolution and more excellent color reproduction than usual in the images printed thereon.
On the other hand, the storage stability of recorded images has come to assume greater importance as significant improvements in image quality have been made. In the ink-jet process, acid dyes and direct dyes have been prevailingly used in printing ink, because they cause no clogging of a printing head and provide color images of high saturation. Under current circumstances, therefore, it is not always possible to choose dyes having satisfactory water resistance and light resistance For the purpose of ensuring both water resistance and light resistance for printed images, Tokkai Sho 59-198188 (the term “Tokkai” as used herein means an “unexamined published Japanese patent application) discloses the use of specified cationic resins, such as quaternary compounds of polyethylenimine, in the ink-receiving layer of an ink-jet recording material, Tokkai Sho 60-260377 discloses the use of cationic colloidal silica, Tokkai Sho 61-146591 discloses the use of hindered amine compounds, and Tokkai Sho 61-284478 discloses the use of quaternary ammonium salts of polyoxyalkylenated amine monocarboxylic acid esters.
However, the use of those compounds cannot impart sufficient light resistance to printed images, although it is certain that appreciable improvements in water resistance are observed. Such being the case, ink-jet recording materials successful in attaining compatibility between water resistance and light resistance have not been developed yet.
As to improvement of light resistance, it is disclosed to add an ultraviolet absorbent and an antioxidant to recording layers in Tokkai Sho 57-87988 and Tokkai sho 57-87989 respectively. Although the light resistance is improved for a certainty by addition of such agents, the improvement achieved is still insufficient from the practical point of view, and besides, the added agents create problems of printed image quality. More specifically, serious reduction in color densities of printed images is caused in the former case, so the printed images cannot have qualities comparable to those of photographs from the very beginning of a printing operation. In the latter case, on the other hand, the antioxidant itself turns brown with a lapse of time, so the keeping quality in white areas of recording paper becomes a problem.
As mentioned above, traditional arts cannot provide ink-jet recording materials capable of forming images comparable to photographic images in appearance and, what is more, retarding deterioration caused in image quality by exposure to light, water or gas, and being free of discoloration in the white areas, namely having high keeping quality.
More specifically, the addition of chemicals for improvement of keeping quality to a recording layer or the formation of a protective layer containing such chemicals on a recording layer in ordinary manners cannot bring about desirable results. After all, it is impracticable to form a protective layer outside the ink-receiving layer since the ink-jet recording process consists in forming images by directing a jet of ink at the recording layer surface. In addition, the coloring materials used for the ink are direct dyes and acid dyes. Although these dyes are superior in hue, they are liable to discolor or lose their colors through cleavage of the double bonds in the dye structures by ultraviolet rays or oxidative gases. In addition, they are susceptible to other chemical reagents also, and so the addition of chemical reagents to the coloration layer tends to produce negative effect directly on coloration.
As a result of intensive study to solve those difficulties, to our surprise, we have found that the addition of a light resistance-imparting chemical prepared by mixing 1 to 10 parts by weight of an ultraviolet absorbent of benzotriazole type, 1 to 8 parts by weight of magnesium sulfate and 1 to 10 parts by weight of zinc oxide to a layer arranged just under a coloration layer to receive ink directly can produce significant improvement in light resistance, and besides, can completely preclude negative influences of chemicals on coloration of dyes, which has so far been a problem in need of solution, thereby achieving the present invention.
SUMMARY OF THE INVENTION
Therefore, an object of the invention is to provide a recording material on which images having high color density, excellent color reproduction and photographic quality can be printed, particularly by means of a high-resolution ink-jet printer, and besides, the images printed have excellent light resistance and undergo no changes in hue upon storage.
The aforementioned object is attained with an ink-jet recording material having on a support at least an ink-receiving layer, characterized in that the ink-receiving layer is comprised of a light resistance-imparting layer as a lower layer and a coloration layer as an upper layer, the light resistance-imparting layer comprises 100 parts by weight of ink absorbing pigments, and a light resistance-imparting chemical constituted of 1 to 10 parts by weight of a benzotriazole ultraviolet absorbent, 1 to 8 parts by weight of magnesium sulfate and 1 to 10 parts by weight of zinc oxide, and the coloration layer is a layer free of light resistance-imparting chemicals.
Further, it has been ascertained that the present recording material ensured more excellent coloration than ever in images printed with pigment ink as well as dye ink.
DETAILED DESCRIPTION OF THE INVENTION
The major function of the present coloration layer consists in receiving ink and fixing dyes in ink to form ink images therein. The specific composition of this layer may be selected appropriately from those of hitherto known ink-receiving layers depending on the intended quality level of images; however, it is of primary importance to the invention to formulate the coloration layer so to be free of light resistance-imparting chemicals. As suitable examples of ingredients mainly constituting the coloration layer, mention may be made of a pigment having high oil absorption, that is, high ink receptivity, a binder for the pigment and a cationic high polymer capable of fixing dyes and enhancing water resistance. The coloration layer may be a single layer or a multiple layer.
The main function of the present light resistance-imparting layer consists in absorbing and fixing a vehicle of ink passing through the coloration layer. Therefore, it is appropriate that the light resistance-imparting layer be constituted mainly of a pigment having high oil absorption and a binder for the pigment, although the composition thereof should be selected depending on the kind of ink to be
Kondo Noboru
Onishi Hiroyuki
Ono Atsushi
Otani Teiichi
Shibatani Masaya
Hess Bruce H.
Millen White Zelano & Branigan P.C.
Nippon Paper Industries Co. Ltd.
Shewareged B.
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