Stock material or miscellaneous articles – Structurally defined web or sheet – Discontinuous or differential coating – impregnation or bond
Reexamination Certificate
2001-01-03
2003-05-20
Hess, Bruce H. (Department: 1774)
Stock material or miscellaneous articles
Structurally defined web or sheet
Discontinuous or differential coating, impregnation or bond
C428S522000, C428S523000
Reexamination Certificate
active
06565952
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a material for recording paper, and more particularly to an ink-jet recording sheet which develops an excellent preventive effect on overall degradation by light such as degradation of image clarity, and decrease in density or change of tone by using it as an ink-receiving layer or glossy layer of ink-jet recording media, and a resin compositions for ink-jet recording media used in the formation thereof.
BACKGROUND ART
In recent years, ink-jet printers have been increasingly spread because they have such features that bright or clear recording is achieved, noises are little, and color images can be formed with ease.
The ink-jet printers require to use inks hard to dry for the purpose of preventing clogging of jet nozzles by drying of ink. As inks having such properties, there are generally used water-based inks in which a binder, a dye, a solvent, additives and the like are dissolved or dispersed in water. However, characters, images and/or the like formed in a recording medium by using such a water-based ink tend to cause degradation by light by room light (fluorescent lamp), direct sunshine or the like. Under the circumstances, the.characters, images and the like formed with the water-based ink are liable to undergo deterioration of image clarity, and decrease in density or change of tone-compared with prints with a pigment ink and silver salt photographs.
According as ink-jet printers have become cheaper, and the excellent definition or sharpness and coloration of images in the ink-jet printers have become close to one in recent years, strict requirements for light fastness and the like have been gradually enhanced.
Accordingly, under the circumstances, the perfect prevention of the overall degradation by light of these images now becomes an essential requisite to ink-jet recording media.
With the foregoing circumstances in view, investigations have been made as to the prevention of the degradation by, light of ink-jet recording media. For example, a great number of patents related to the fact that a metallic compound such as magnesiumoxide, magnesium carbonate, calcium oxide or calcium carbonate is added to an ink-receiving layer, thereby developing a preventive effect on degradation by light have been proposed. However, it has been found that the addition of these metallic compounds not only has no sufficient effect, but also brings a greater evil effect that the image clarity is degraded. As described above, the addition of the metallic compounds has a fear that the evil effect of degrading the image clarity becomes greater than the preventive effect on the degradation by light. However, the investigation as to this problem centers on additives to ink-receiving layers and the like under the circumstances, and an investigation as to resin compositions for ink-jet recording media having a preventive effect on degradation by light is not very made.
The general investigation as to the prevention of degradation by light of the ink-jet recording media is only made on room light, and any invention having a sufficient effect on overall degradation by light is not yet made.
Accordingly, the present invention has carried on investigations as to resin compositions for ink-jet recording media, and it is an object of the present invention to provide an ink-jet recording sheet having an excellent preventive effect on degradation by light such as degradation of image clarity, and decreasing in density or change of tone of an image, and a resin composition for ink-jet recording media, which is suitable for use in the formation of such a sheet.
DISCLOSURE OF THE INVENTION
The present inventors have carried out various investigations as to resin compositions for ink-jet recording media. As a result, it has been found that when a resin composition comprising a water-soluble acrylic resin synthesized under specified conditions is used in an ink-receiving layer of an ink-jet recording medium, the overall degradation by light such as degradation of image clarity, and decreasing in density or change of tone is extremely effectively prevented, thus leading to completion of the present invention.
An ink-jet recording sheet according to the present invention is characterized by comprising a substrate and as an ink-receiving layer provided on the substrate, a layer containing an acrylic resin comprising, as copolymerizable monomers, (a) a dialkylaminoalkyl methacrylate, (b) acrylamide and (c) at least one monomer selected from among an alkoxypolyethylene glycol methacrylate, a 2hydroxyalkyl methacrylate and a 2-hydroxyalkyl acrylate.
A resin composition for ink-jet recording media according to the present invention, which is used for formation of the ink-jet recording sheet described above, is characterized by comprising a solvent and an acrylic resin dissolved in the solvent and comprising, as copolymerizable monomers, (a) a dialkylaminoalkyl methacrylate, (b) acrylamide and (c) at least one monomer selected from among an alkoxypolyethylene glycol methacrylate, a 2-hydroxyalkyl methacrylate and a 2-hydroxyalkyl acrylate, wherein the solvent is a mixed solvent of water/alcohol.
BEST MODE FOR CARRYING OUT THE INVENTION
The preferred mode for carrying out the present invention will hereinafter be described.
The resin composition for ink-jet recording media according to the present invention serves to impart a preventive effect on degradation by light, such as degradation of image clarity, and decreasing in density or change of tone, to an ink-jet recording sheet by using it in the formation of an ink-receiving layer of such a sheet.
With respect to the acrylic resin contained in the ink-receiving layer of the ink-jet recording sheet according to the present invention, the raw materials, synthetic conditions and other various conditions will hereinafter be described.
(A) Raw Materials (monomers) of Acrylic Resin
The acrylic resin in the present invention is an acrylic copolymer synthesized by using, as raw materials, two monomers of a dialkylaminoalkyl methacrylate and an acrylamide as a component that is considered to impart miscibility with a pigment used in the ink-receiving layer and stability of a coating material to the resin, and at least one monomer selected from among an alkoxy-polyethylene ,glycol methacrylate, a 2-hydroxyalkyl methacrylate and a 2-hydroxyalkyl acrylate as a component that is considered to impart image clarity to the resulting acrylic resin.
Specific raw materials (monomers) of the acrylic resin will hereinafter be described.
No particular limitation is imposed on the dialkylaminoalkyl methacrylate that is considered to impart water solubility, miscibility with pigments and stability to the acrylic resin. However, examples thereof include dimethylaminomethyl methacrylate, diethylaminomethyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, dipropylaminomethyl methacrylate and dipropylaminoethyl methacrylate.
Among these monomers, dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate are most preferred in view of points of the degree of water solubility (water resistance) of an ink-receiving layer comprising an acrylic resin synthesized therefrom as a binder, the degree of activity at an amino site taking prevention of degradation by light into consideration, the degree of miscibility with a pigment contained in the ink-receiving layer, and the like.
In the present invention, acrylamide is used in combination as a monomer for finely adjusting the water solubility of the resulting acrylic resin and lowering the copolymerization ratio of the dialkylaminoalkyl methacrylate as much as possible to prevent degradation by light.
No particular limitation is imposed on the alkoxypolyethylene glycol methacrylate that is considered to impart water solubility and transparency (i.e., clarity of a printed image) to the resulting acrylic resin. However, examples thereof include those having the following structural formula, and specific examples thereof include methoxypolyethylene glycol methacrylat
Ishikawa Takayuki
Iwamoto Kiyoshi
Kobayashi Shin-ichiro
Kubota Nobuhiro
Onishi Hiroyuki
Grendzynski Michael E.
Hess Bruce H.
Tomoegawa Paper Co. Ltd.
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