Stock material or miscellaneous articles – Structurally defined web or sheet – Discontinuous or differential coating – impregnation or bond
Reexamination Certificate
1999-10-21
2002-11-26
Hess, Bruce H. (Department: 1774)
Stock material or miscellaneous articles
Structurally defined web or sheet
Discontinuous or differential coating, impregnation or bond
C428S323000, C428S325000, C428S328000, C428S331000
Reexamination Certificate
active
06485812
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink jet recording sheet. More particularly, it relates to a high quality ink jet recording sheet which is excellent in water resistance and scratch resistance and free from beading and has good transportability and which is free from an acetic acid odor. Further, it relates to an ink jet recording sheet which is excellent also in blocking resistance while suppressing image bleeding under a high temperature high humidity condition.
2. Discussion of Background
The ink jet recording system is a system wherein fine droplets of ink are jetted by various operational principles such as a deflection, cavity, thermojetting, bubble jetting, thermal ink jetting, slit jetting or spark jetting system, and deposited on an ink jet recording sheet such as a paper sheet to form a record of images or letters. By virtue of its merits such as high speed, low noise, easiness to produce multi-color images, applicability to a wide variety of recording patterns and unnecessity of development or fixation, it has found a wide range of applications in various recording apparatus for figures including Chinese characters and for color images.
Further, images formed by an ink jet recording system using multi-color inks each containing a coloring material of yellow, magenta, cyan or black contained in a solvent such as water or a hydrophilic solvent, are capable of providing a record which is comparable to multi-color printed images by a printing plate system. Still further, when only a small number of prints are required, the ink jet recording system is inexpensive as compared with the development of silver salt photography, and it is being widely used also in the full color image recording field.
The ink jet recording system has been applied to various uses, as a result of developments in technique in recent years. When the use is limited for the output as a hard copy, it can be roughly classified into (1) one for general use (home use and for hobby), (2) one for office use (office automation) and (3) one for business use (EA and factory automation). Particularly for business use, a high quality hard copy of at least 400 dpi (16 dots/mm) is required, and the ink jet recording system is increasingly used.
A high quality hard copy obtainable by the ink jet recording system is prospective also as a substitute for a silver salt photograph. As disclosed, for example, in JP-A-1-95091, JP-A-2-276670, JP-A-3-285814, JP-A-3-285815, JP-A-4-37576, JP-A-5-32037, U.S. Pat. No. 4,879,166 and U.S. Pat. No. 5,104,730, many inventions have been made with respect to an ink jet recording sheet having an ink-receiving layer which comprises alumina hydrate and a binder resin. Such an ink jet recording sheet employing alumina hydrate has merits such that since such alumina hydrate is needle, plate or strand-form fine particles of from a few tens to a few hundreds nm, it has high gloss and transparency, and as it has a positive charge, fixing of a colorant in the ink is good, whereby an excellent optical density can be obtained.
However, such an ink-receiving layer employing alumina hydrate has had the following problems, and by overcoming these problems, it will be possible to provide for the first time an ink jet recording sheet wherein the merits of the alumina hydrate are adequately utilized.
1) Water resistance and scratch resistance may be mentioned as problems relating to an ink-receiving layer employing alumina hydrate. Concerning the water resistance, there has been a problem that when water drops are attached to the surface of the ink-receiving layer or when the ink jet recording sheet is immersed in water, the binder resin in the ink-receiving layer undergoes swelling, or in some cases, the binder resin will be dissolved, whereby the ink-receiving layer will be destroyed. On the other hand, concerning the scratch resistance, there has been a problem such that a mark of a feed roll of an ink jet recording printer is impressed on the surface of the ink-receiving layer, or scratch marks are imparted to the surface of the ink-receiving layer during handling by a user, or in some cases, a part of the layer is peeled off.
To solve such problems, for example, JP-A-7-76161 proposes an alumina sol coating fluid comprising alumina hydrate, polyvinyl alcohol and boric acid or a borate. However, no adequate film strength has been obtained merely by crosslinking polyvinyl alcohol by means of boric acid or a borate, and the resulting film tended to be swelled or was susceptible to scratching, and thus scratch resistance was also inadequate.
Further, JP-A-7-76162 discloses a recording sheet having a silica gel layer having a thickness of from 0.1 to 30 &mgr;m on a pseudo boehmite porous layer for the purpose of improving the abrasion resistance of the recording layer. The mark of a feed roll of an ink jet recording printer can thereby be reduced, but scratch marks are still likely to be imparted during the handling, and thus, there is a room for improvement. Besides, the water resistance has not been improved at all, and swelling or dissolution of the ink-receiving layer by deposition of water can not be avoided. In addition to these methods, various inventions have been made, such as a method wherein a silanol-modified polyvinyl alcohol is employed, and a method wherein as a curing agent for a water-soluble binder resin, a water-soluble polyisocyanate compound, a water-soluble aziridine compound, a water-soluble melamine resin, a water-soluble urea resin, or an aqueous oxazoline resin, is, for example, employed (JP-A-9-76628), or an epoxy or amino-modified compound is incorporated. However, no adequate effects for improvement have been obtained.
2) Along with a recent progress for high image quality of ink jet recording, the ink jetting amount to an ink jet recording sheet is increasing. Especially when an ink having a so-called colorant concentration reduced, such as light cyan or light magenta, is used for the purpose of reducing the granularity of a full color image, higher ink absorptivity is required for an ink jet recording sheet. If adequate ink absorptivity can not be secured, ink is likely to be flooded on the surface of the ink-receiving layer, and also in the interior of the ink-receiving layer, ink drops are likely to be localized and become non-uniform, whereby beading is likely to result.
Heretofore, various inventions have been made to overcome beading in the ink-receiving layer employing alumina hydrate. For example, JP-A-4-263983 proposes to apply a surfactant such as dodecylbenzenesulfonic acid, sodium lauryl sulfate, potassium oleate, sodium stearate, sodium alkylbenzenesulfonate or sodium polyoxyethylenenonylphenylether sulfonate, to a pseudo boehmite surface. Further, JP-A-9-76628 discloses an ink-receiving layer formed by coating a dispersion comprising alumina hydrate surface-treated with a coupling agent, and a binder resin or a polymer compound, followed by drying, or by polymerizing the above-mentioned polymerizable compound. Further, JP-A-7-232474 proposes to employ alumina hydrate containing from 0.01 to 1.00 wt % of titanium dioxide.
However, none of these methods have been able to adequately overcoming beading.
Further, for the purpose of improving not only scratch resistance of the ink-receiving layer but also transportability, it has been proposed to form an overcoating layer containing fine particles of e.g. silica gel, for example, in JP-A-8-2087 or JP-A-8-3497. In either case, although the transportability can be improved by forming an overcoating layer, beading tends to deteriorate, whereby it is impossible to satisfy both properties. Namely, by forming an overcoating layer, the ink tends to diffuse in a transverse direction in the overcoating layer, whereby beading is accelerated.
Whereas, JP-A-9-76628 discloses an invention which comprises polymerizing or coating and drying on a support a dispersion containing alumina hydrate surface-treated with a coupling agent and a binder or a polymerizable compound
Hess Bruce H.
Mitsubishi Paper Mills Limited
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Shewareged B.
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