Stock material or miscellaneous articles – Ink jet stock for printing – Plural ink receptive layers
Reexamination Certificate
2003-05-20
2004-11-23
Shewareged, B. (Department: 1774)
Stock material or miscellaneous articles
Ink jet stock for printing
Plural ink receptive layers
C428S032270, C428S032280, C428S032300, C428S032310, C428S032380
Reexamination Certificate
active
06821584
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an ink-jet recording medium and in more detail to a swelling type ink-jet recordings medium which exhibits excellent ink fixability against water, ink absorbability, glossiness, and discoloration resistance.
BACKGROUND
Ink-jet recording is a quiet recording method, and is capable of achieving high speed printing as well as easily achieving multicolor recording by utilizing a plurality of nozzles. As a result, in recent years, ink-jet recording has increasingly been applied to image information output apparatuses used for computers. Further, in its application fields, employed as recording media are transparent film and glossy resin coated paper, and the output images are expanding into texts, drawings, color block copies requiring image quality approaching conventional photography, and various design images.
From the aspect of safety and recording characteristics, mainly employed as ink for ink-jet recording is aqueous ink comprised of water and water-soluble organic solvents as main components, whereby it is intended to minimize clogging of the ink as well as to enhance ink ejection characteristics. Further, conventionally employed as ink-jet recording media (hereinafter also referred to simply as recording media) have been plain paper sheets and recording sheets, called ink-jet recording paper, which comprise a support having thereon a porous ink absorptive layer.
However, since such conventional recording media result in marked ink bleeding and exhibit low glossiness, they are not capable of meeting the demand for higher image quality in recent years. Further, when a conventional porous ink absorptive layer is applied onto transparent film or glossy resin coated paper, problems occur in which transparency or glossiness is degraded due to low light transmission of the porous ink absorptive layer. Further, when the ink absorptive layer is not porous, light transmission increases. However, problems occur in which after printing of the images, ink remains on the surface of the recording medium for an extended period of time due to low ink adsorption whereby drying and fixing time increases.
In order to overcome such problems, it is proposed that gelatin be employed to prepare an ink absorbing layer which exhibits high light transmission as well as excellent aqueous ink adsorption. For example, Japanese Patent Application Open to Public Inspection No. 62-263084 proposes a receiving layer which is prepared employing an aqueous gelatin solution having a specified pH, Japanese Patent Application Open to Public Inspection No. 1-146784 proposes the use of a mixture consisting of gelatin and surfactants, and Japanese Patent Application Open to Public Inspection No. 6-64306 proposes a recording sheet which is prepared in such a manner that after coated gelatin is temporality modified into a gel state, the resulting gel is dried employing a freeze dry method.
Such receiving layers employing gelatin certainly exhibit excellent ink adsorption as well as high light transmission. However, ink drying and fixing take from several minutes to several tens of minutes. When printed images are touched or come into contact with other paper sheets soon after printing, problems occur in which these are stained with ink or the images themselves are degraded.
Generally, ink absorbability of the recording media employing gelatin in the ink absorbing layer depends markedly on the characteristics of polymers employed in the ink absorbing layer. Known as a polymer which has been employed as a polymer exhibiting high ink absorbability is polyvinyl alcohol. However, the use of polyvinyl alcohol causes problems in which ink fixability (water resistance) is degraded. On the other hand, ink fixability is improved by employing cationic water-soluble polymers. However, the use of the cationic water-soluble polymers results in a decrease in glossiness. Currently, a means remains to be found to simultaneously achieve compatibility of excellent ink fixability and high glossiness.
On the other hand, ink-jet recording images result in problems in which discoloration tends to occur due to harmful gases. Specifically, water-soluble phthalocyanine based dyes, which are employed in common jet printers, tend to cause such discoloration. Discoloration mechanism is not yet fully understood. However, it is assumed that a minute amount of active harmful gasses such as ozone, oxidants, So
x
and NO
x
in ambient air decompose these dyes.
SUMMARY
In order to overcome the aforesaid problems, the present invention was achieved. An object of the present invention is to provide a swelling type ink-jet recording medium which exhibits excellent water resistance of a printed image, ink absorbability, glossiness, and discoloration resistance.
The object of the present invention is achieved employing the embodiments described below.
One structure of the present invention is an ink-jet recording sheet comprising a support having thereon in the following order:
(i) a first ink absorbing layer comprising gelatin and a first cationic polymer; and
(ii) a second ink absorbing layer comprising gelatin and a second cationic polymer,
wherein the first cationic polymer has a larger ink adsorption ratio A
i
than the second cationic polymer, the ink adsorption ratio A
i
being defined by the following equation:
A
i
(%)=((an optical density of a print after immersion in water)/(an optical density of a print before immersion in water))×100.
Another structure of the present invention is an ink-jet recording sheet comprising a support having at least two ink absorbing layers thereon,
wherein at least one of the two ink absorbing layers comprises gelatin and a polyvinyl alcohol; the ink absorbing layers comprise the polyvinyl alcohol having a saponification degree of not more than 92% and a weight-average molecular weight of not less than 2000 in an amount of not less than 10 weight % based on the total weight of the polyvinyl alcohol in all of the ink absorbing layers; the outermost ink absorbing layer has a largest weight content ratio of the polyvinyl alcohol among all of the ink absorbing layers; and the outermost ink absorbing layer comprises the polyvinyl alcohol having a saponification degree of not more than 92% and a weight-average molecular weight of not less than 2000.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The present invention will now be detailed.
One of the embodiments of the present invention is characterized in that in an ink-jet recording medium which has a support having thereon ink absorbing layers, at least one of the aforesaid ink absorbing layers comprises gelatin, a cationic polymer, and a cellulose derivative.
In ink-jet recording media, by employing cationic polymers, the fixability of coloring materials is enhanced. However, problems occur in which ink absorbability decreases. On the other hand, by employing cellulose derivativees, ink absorbability is enhanced. However, problems occur the fixability of coloring materials is degraded. By employing the cationic polymers and those derived from the cellulose derivative which exhibit incompatible characteristics with each other, it is possible to achieve some compatibility between fixability of the coloring materials and ink absorbability. However, in the pursuit of quality to equal silver halide photography, the resulting quality has been unsatisfactory. In addition, it was found that new problems occurred in which the resulting glossiness was degraded. The inventors of the present invention performed diligent investigations to overcome the aforesaid problems. As a result, it was discovered that compatibility between fixability of the coloring materials and ink absorbability was satisfied, and in addition, it was possible to enhance glossiness.
In another embodiment of the present invention according, it is preferable that in recording media comprising gelatin, cationic polymers, and the cellulose derivative, employed as the cellulose derivative are cellulose derivatives having a carboxylic acid group.
Polymers such
Hiyama Kunimasa
Ito Junji
Nishijima Toyoki
Suzuki Shin'ichi
Tashiro Kouji
Konica Corporation
Shewareged B.
Squire Sanders & Dempsey
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