Compositions: coating or plastic – Coating or plastic compositions – Marking
Reexamination Certificate
2000-12-13
2003-01-14
Klemanski, Helene (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
Marking
C106S031590, C106S031680, C106S031890
Reexamination Certificate
active
06506240
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink composition which can yield highquality printed images.
2. Background Art
Ink jet recording is a recording method wherein droplets of ink are ejected through fine nozzles to form letters or figures on the surface of recording media. various properties are required of inks used in such ink jet recording, and examples thereof include good dispersion stability, ejection stability, and rubbing/scratch resistance of prints.
Inks comprising various watersoluble dyes dissolved in aqueous media have generally been used. Further, inks comprising pigments dispersed in aqueous media have also been provided. Inks comprising pigments dispersed in aqueous media are advantageously superior to inks using watersoluble dyes in waterfastness and lightfastness of printed images.
On the other hand, inks for ink jet recording are required to satisfy property requirements such that, for example, properties remain unchanged during storage for a long period of time, the ink does not clog fine nozzles, prints have high density and high sharpness, and prints yielded by the inks have good storage stability, for example, in terms of waterfastness and lightfastness. In particular, in the case of pigment-based inks, storage stability (that is, stable dispersion of the pigment for a long period of time) and freedom from nozzle clogging during printing or at the time of restarting after interruption of printing are required.
The following pigmentbased inks have been proposed. For example, Japanese Patent Publication No. 1426/1987 proposes an ink comprising a pigment and a resin emulsion dispersed in water. The claimed advantage of using an emulsion comprising a waterinsoluble synthetic resin is to improve the storage stability of the pigment ink.
Japanese Patent LaidOpen No. 157668/1980 proposes that the dispersion of a pigment in a waterinsoluble resin emulsion dispersion enables the dispersion stability to be maintained even at relatively low viscosity. Japanese Patent LaidOpen No. 217088/1989 describes that the use of an emulsion having a specific filmforming temperature can improve the storage stability and fluidity of the ink. Likewise, inks using a resin emulsion are proposed in Japanese Patent Laid-Open Nos. 160068/1991 and 18462/1992. Japanese Patent LaidOpen No. 18427/1990 proposes the addition of inositol to the ink to alleviate nozzle clogging. Japanese Patent LaidOpen No. 214785/1990 proposes the addition of maltitol to the ink to improve the anti-drying properties of the ink.
SUMMARY OF THE INVENTION
The present inventors have now found that an ink composition containing a mixture of saccharides can realize good printed images. In particular, the present inventors have found that this ink composition, when used in an ink jet recording method, can be stably ejected, does not cause nozzle clogging, can realize stable printing, and thus can realize excellent images. The present invention has been made based on such finding.
Accordingly, it is an object of the present invention to provide an ink composition which can realize good images, especially an ink composition which, when used in an ink jet recording method, can be stably ejected and can realize good image quality.
According to one aspect of the present invention, there is provided an ink composition comprising: a colorant; water; a watersoluble organic solvent; and a mixture of saccharides, wherein said mixture of saccharides comprises (a) a monosaccharide and/or a derivative thereof, (b) a disaccharide and/or a derivative thereof, and (c) a tri or higher polysaccharide and/or a derivative thereof.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Ink composition
The ink composition according to the present invention is used in recording methods using ink compositions, for example, ink jet recording, recording method using writing utensils, such as pens, and other various printing methods. Particularly preferably, the ink composition according to the present invention is used in the ink jet recording method.
Mixture of saccharides
The ink composition according to the present invention contains a mixture of saccharides. The mixture of saccharides comprises a monosaccharide and/or a derivative thereof, a disaccharide and/or a derivative thereof, and a tri- or higher polysaccharide and/or a derivative thereof. The addition of the mixture of saccharides and/or derivatives thereof to the ink composition can effectively prevent nozzle clogging, and consequently can produce excellent printed images by virtue of excellent ejection stability.
Specific examples of monosaccharides include threose, erythrulose, erythrose, arabinose, ribulose, ribose, xylose, xylulose, lyxose, glucose, fructose, mannose, idose, sorbose, gulose, talose, tagatose, galactose, allose, psicose, and altrose. Among them, glucose and xylose are preferred.
Specific examples of disaccharides include maltose, isomaltose, cellobiose, lactose, sucrose, trehalose, isotrehalose, gentiobiose, melibiose, turanose, sophorose, and isosaccharose. Among them, maltose and isomaltose are preferred.
Tri- or higher polysaccharides include: homoglycans, such as glucan, fructan, mannan, xylan, galacturonane, mannuronane, and N-acetylglucosamine polymer; and heteroglycans, such as diheteroglycan and triheteroglycan. Specific examples of such polysaccharides include maltotriose, isomaltotriose, panose, maltotetraose, and maltopentaose. Among them, maltotriose and isomaltotriose are preferred.
According to a preferred embodiment of the present invention, reducing branched oligosaccharides may be mentioned as disaccharides or tri- or higher polysaccharides. According to the present invention, the “reducing branched oligosaccharide” refers to an oligosaccharide which is constituted by about 2 to 10 monosaccharides, preferably 2 to 5 monosaccharides, has a branched structure, and a reducing capability. The oligosaccharide may be either a homo-oligosaccharide or a hetero-oligosaccharide with the homo-oligosaccharide being preferred.
According to a preferred embodiment of the present invention, the reducing branched oligosaccharide comprises at least two glucoses bonded to each other through an &agr;1, 6 glucoside linkage and has a branched structure. This type of oligosaccharide is preferably prepared from one member or a mixture of two or more members selected from the group consisting of starch, amylopectin, and glycogen. The reducing branched oligosaccharide may be prepared from the above compound(s) by a commonly used conventional method. Among others, an example of preferred methods is hydrolysis. Further, according to the present invention, besides the hydrolysis of polysaccharides, glucoside linkage of glucose or isomerization of maltose may be used for the preparation of the reducing branched oligosaccharide.
According to a preferred embodiment of the present invention, the reducing branched oligosaccharide is one member or a mixture of two or more members selected from the group consisting of isomaltose, panose, and isomaltotriose.
Further, according to the present invention, commercially available reducing branched oligosaccharides may also be used. Specific examples thereof include HS300 and HS500 (tradenames; manufactured by Hayashibara Co., Ltd.) and PO300 and PO500 (tradenames; manufactured by Towa Chemical Industry Co., Ltd.).
Derivatives of saccharides include sugar alcohols, sugar acids, amino sugars, and thiosugars. Among them, sugar alcohols and amino sugars are preferred.
The sugar alcohol is preferably selected from the group consisting of monosaccharides-derived sugar alcohols, disaccharides-derived sugar alcohols, and tri- or higher polysaccharides-derived sugar alcohols. monosaccharides-derived sugar alcohols include glycerin, threitol, erythritol, arabitol, ribitol, xylitol, lyxitol, sorbitol (glucitol), mannitol, iditol, gulitol, talitol, galactitol, allitol, and altritol. Among them, xylitol, sorbitol, and glycerin are preferred.
Disaccharides-derived sugar alcohols include maltitol, isomaltito
Kubota Kazuhide
Takemoto Kiyohiko
Faison Veronica F.
Klemanski Helene
Ladas & Parry
Seiko Epson Corporation
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