Stock material or miscellaneous articles – Ink jet stock for printing – Particles present in ink receptive layer
Reexamination Certificate
2002-08-29
2004-08-17
Shewareged, B. (Department: 1774)
Stock material or miscellaneous articles
Ink jet stock for printing
Particles present in ink receptive layer
C428S032300
Reexamination Certificate
active
06777040
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a recording sheet for an ink jet printer, and in particular, relates to a recording sheet for an ink jet printer, in which printing density is high; printing is vivid; ink absorptivity is superior; light resistance, ozone resistance, and moisture resistance are superior; and ink is quickly absorbed. The recording sheet satisfies future high speed printing technique requirements.
2. Description of the Related Art
The use of ink jet printers has continued to increase in recent years because they have characteristics such as vividness of recorded images, quiet operation, ease of coloring, and the like. In order to prevent the jet nozzle thereof from being blocked due to drying of ink, an ink which is difficult to dry must be used in the ink jet printers. As ink having this property, water-soluble ink which is dissolved or dispersed with adhesive, dye, solvent, additives, or the like, in water, is generally employed. However, a symbol or an image formed on a recording sheet by employing the water-soluble ink is inferior to that of printed matter or silver halide photographs due to the use of pigment-type inks, from the viewpoint of light resistance, ozone resistance, and moisture resistance.
In recent years, as ink jet printers become inexpensive and printing images having high vividness and colorfulness are easily obtained, the requirements for ink absorptivity and color reproducibility have increased, and further improvement of printing density or further vivid coloring is thereby desired. In addition, the requirements for shelf life such as light resistance, ozone resistance, etc., are becoming severe. Therefore, completely satisfying these various requirements is an essential goal for recording sheets for ink jet printers.
In consideration of this present situation, improvements of recording sheets for ink jet printers have been researched. A method for improving color reproducibility and ink absorptivity by adding amino acids, for example, typified by Japanese Patent Applications, Publications No. 8-295075 and No. 7-276791, have been proposed. In addition, a method for improving light resistance of the images by using additives such as polyphenol, etc., has also been proposed. However, it has been confirmed that the addition of only these amino acids produces disadvantages such as decrease of vividness of images, reduction of light resistance and moisture resistance, etc., and that the addition of polyphenol produces yellowing over time, and all of the properties of printing density, vividness of images, and shelf life have not yet been sufficiently improved.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a recording sheet for an ink jet printer which can improve recording properties such as vividness of images, printing density, etc., and shelf life such as light resistance of images, ozone resistance, etc.
According to the results that the inventors have obtained from various research with regard to a recording sheet for an ink jet printer, the recording properties such as vividness of images, printing density, etc., and the shelf life such as light resistance of images, ozone resistance, etc., are improved very effectively by including an oligosaccharide and divalent metallic salt in the recording sheet for an ink jet printer, and the inventors have thereby attained the present invention. In other words, the recording sheet for an ink jet printer according to the present invention is characterized in that an ink receiving layer is provided on at least one side of a base material, and at least one of the ink receiving layer and the base material includes an oligosaccharide and divalent metallic salt. Furthermore, in the recording sheet for an ink jet printer of the present invention, it is preferable that the oligosaccharide and the divalent metallic salt be included in the ink receiving layer. In the following, the preferred embodiments according to the present invention will be explained in detail.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The recording sheet for an ink jet printer according to the present invention is a laminated sheet in which at least one ink receiving layer is provided on at least one surface of a base material by a providing means such as a coating method, or the like. The ink receiving layer may be provided as two layers or more. In the following, materials which compose the base material and the ink receiving layer will be explained. The recording sheet for an ink jet printer of the present invention can exhibit superior recording properties and shelf life properties if the oligosaccharide and the divalent metallic salt are included not only in the ink receiving layer but also in any layer of the recording sheet for an ink jet printer; however, in the following, an embodiment which includes the oligosaccharide and the divalent metallic salt in the ink receiving layer will be explained.
(1) Base Material
As a base material provided for coating an ink receiving layer thereon according to the present invention, a base paper in which is mixed wood pulp such as chemical pulp such as LBKP, NBKP, or the like; mechanical pulp such as GP, PGW, RMP, TMP, CTMP, CMP, CGP, or the like; recycled pulp such as DIP, or the like; etc.; or synthetic fiber pulp such as that of polyethylene fiber, or lo the like, as a primary component, with pigment, sizing agent, fixer, yield improving agent, strengthening agent, or the like, alone or in combination, as necessary, and which is produced by using any type of apparatus such as a fourdrinier paper machine, cylinder paper machine, twin wire paper machine, or the like; can be preferably employed. In addition, a base paper provided with starch, polyvinyl alcohol, or the like using a size press; and a coated paper such as art paper, coated paper, cast coat paper, or the like, in which a coat layer is provided on these base papers, can be preferably employed. These base papers and coated papers may support an ink receiving layer directly, and in order to control smoothness of the surface thereof, a calender apparatus may be used such as a machine calender, TG calender, soft calender, or the like, before coating the ink receiving layer.
As a base material, a polyolefin resin layer may be provided on the surface of the above-described base paper, and film material of synthetic resin such as polyethylene, polypropylene, polyester, nylon, rayon, polyurethane, or the like; film material comprised of a mixture with these; and fiber-formed sheets of these synthetic resins may be employed.
(2) Ink Receiving Layer
The ink receiving layer in the recording sheet for an ink jet printer of the present invention is formed by a primary component comprising pigment and binder resin and various additives which are added as necessary, and in the present invention, it is preferable that the ink receiving layer contain divalent metallic salt in addition to oligosaccharide, so as to attain superior light resistance and ozone gas resistance. In the following, materials which can be employed in the ink receiving layer will be explained.
(A) Pigment
In an ink receiving layer according to the present invention, generally used pigments which are insoluble or slightly soluble in water can be employed alone or in combination. For example, a white inorganic pigment such as precipitated calcium carbonate, heavy calcium carbonate, kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, aluminum silicate, diatomite, calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, colloidal alumina, pseudo-boehmite, aluminum hydroxide, alumina, lithopone, zeolite, hydrolytic halloysite, magnesium carbonate, magnesium hydroxide, or the like; an organic pigment such as styrene-type plastic pigment, acrylic-type plastic pigment, polyethylene, microcapsules, urea resin, melamine resin, or the like, etc., can be employed.
Of these pigments, as a white pigment
Asai Shigeki
Katagiri Kazushige
Kubota Nobuhiro
Tatsuhashi Fumikazu
Tsuchida Minoru
Arent & Fox PLLC
Shewareged B.
Tomoegawa Paper Co., LTD
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