Stock material or miscellaneous articles – Structurally defined web or sheet – Discontinuous or differential coating – impregnation or bond
Reexamination Certificate
2000-11-30
2003-05-20
Schwartz, Pamela R. (Department: 1774)
Stock material or miscellaneous articles
Structurally defined web or sheet
Discontinuous or differential coating, impregnation or bond
Reexamination Certificate
active
06565953
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an ink jet recording element, more particularly to a porous ink jet recording element.
BACKGROUND OF THE INVENTION
In a typical ink jet recording or printing system, ink droplets are ejected from a nozzle at high speed towards a recording element or medium to produce an image on the medium. The ink droplets, or recording liquid, generally comprise a recording agent, such as a dye or pigment, and a large amount of solvent. The solvent, or carrier liquid, typically is made up of water, an organic material such as a monohydric alcohol, a polyhydric alcohol or mixtures thereof.
An ink jet recording element typically comprises a support having on at least one surface thereof an ink-receiving or image-forming layer. The ink-receiving layer may be a porous layer which imbibes the ink via capillary action or a polymer layer which swells to absorb the ink.
Ink jet prints, prepared by printing onto ink jet recording elements, are subject to environmental degradation. They are especially vulnerable to water smearing and light fade. For example, since ink jet dyes are water-soluble, they can migrate from their location in the image layer when water comes in contact with the receiver after imaging. Highly swellable hydrophilic layers can take an undesirably long time to dry, slowing printing speed, and will dissolve when left in contact with water, destroying printed images. Porous layers speed the absorption of the ink vehicle, but often suffer from insufficient gloss and severe light fade. Porous layers are also difficult to coat without cracking. The support for the ink receiving layers is typically either porous or non-porous. When it is porous, the support itself can absorb non-imaging ink components such as water, solvents, and humectants, so that the ink receiving layer thickness can be minimized. However, when the support itself is non-porous, the ink receiving layer thickness must be great enough to absorb all the ink rapidly in order to prevent degradation of the image by dye smear during printing.
EP 940,427 discloses a method for making a microporous film for an ink jet recording element in which a hydrophobic polymer and a second hydrophilic polymer or copolymer of N-vinylpyrrolidone is dissolved in a certain solvent system, partially dried, and then washed to extract at least 50% by weight of the second polymer. The amount of the hydrophobic polymer to the second hydrophilic polymer is stated as 2:1-1:3. This reference also discloses the addition of a mordant to the polymer mixture. However, this reference does not disclose the use of a fluid-absorbing layer, so that the element has a problem in that it has a limited ink-absorbing capacity.
U.S. Pat. Nos. 4,785,313 and 4,832,984 disclose a two-layer ink jet receiving element wherein the layer adjacent the support is an image receiving layer and the outermost layer is an ink-transporting layer. However, there is a problem with this receiving element due to the fact that the ink-retaining layer is underneath the ink-transporting layer, which would scatter light, thus lowering the optical density.
It is an object of this invention to provide an ink jet recording element which will provide improved ink uptake speed and capacity. Another object of the invention is to provide an ink jet recording element having a receiving layer that when printed upon has an excellent image quality. Still another object of the invention is to provide an ink jet recording element having a receiving layer wherein the printed image has improved water fastness. Yet still another object of the invention is to provide an ink jet recording element having improved ink absorbing capacity and drying rate when the support is non-porous or highly water resistant.
SUMMARY OF THE INVENTION
These and other objects are provided by the present invention comprising an ink jet recording element comprising a support having thereon in order:
a) a hydrophilic, fluid-absorbing layer, and
b) an image-receptive layer capable of retaining an ink jet image, the image-receptive layer comprising an open-pore membrane of a mixture of a water-insoluble polymer and a water-absorbent polymer, the mixture containing at least about 25% by weight of the water-absorbent polymer.
By use of the invention, a recording element is obtained which will provide improved ink uptake speed and capacity, and when printed upon, has an excellent image quality and improved water fastness.
DETAILED DESCRIPTION OF THE INVENTION
In order for the image-receptive layer of the invention to be sufficiently porous, the water-insoluble polymer must be coated from a solvent mixture combination such that an open-pore membrane structure will be formed when the solution is coated and dried, in accordance with the known technique of dry phase inversion. In a preferred embodiment, the formation of an open-pore membrane is accomplished by using a mixture of a good and poor solvent for the water-insoluble polymer. In this embodiment, the poor solvent has a boiling point that is higher than that of the good solvent. When the solution is coated or cast onto a support and dried, the good solvent evaporates faster than the poor solvent, forming the membrane structure of the layer when the polymer phase separates from the solvent mixture. The open-pore structure results when the good solvent and poor solvent are removed by drying.
The water-insoluble polymer that can be used in the image-receptive layer of the invention may be, for example, a cellulose ester such as cellulose diacetate, cellulose triacetate, cellulose acetate propionate or cellulose acetate butyrate, cellulose nitrate, polyacrylates such as poly(methyl methacrylate), poly(phenyl methacrylate) and copolymers with acrylic or methacrylic acid, or sulfonates, polyesters, polyurethanes, polysulfones, urea resins, melamine resins, urea-formaldehyde resins, polyacetals, polybutyrals, epoxies and epoxy acrylates, phenoxy resins, polycarbonates, vinyl acetate polymers and copolymers, vinyl chloride-vinyl acetate copolymers, vinyl chloride-vinyl acetate-vinyl-alcohol copolymers, vinyl chloride-vinyl acetate-maleic acid polymers, vinyl chloride-vinylidene chloride copolymers, vinyl chloride-acrylonitrile copolymers, acrylic ester-acrylonitrile copolymers, acrylic ester-vinylidene chloride copolymers, methacrylic ester-styrene copolymers, butadiene-acrylonitrile copolymers, acrylonitrile-butadiene-acrylic or methacrylic acid copolymers, or styrene-butadiene copolymers. Cellulose ester derivatives, such as cellulose diacetates and triacetates, cellulose acetate propionate, cellulose acetate butyrate, cellulose nitrate, and mixtures thereof are preferred.
The water-absorbent polymer that can be used in the image-receptive layer of the invention may be, for example, polyvinylpyrrolidone and vinylpyrrolidone-containing copolymers, polyethyloxazoline and oxazoline-containing copolymers, imidazole-containing polymers, polyacrylamides and acrylamide-containing copolymers, poly(vinyl alcohol) and vinyl-alcohol-containing copolymers, poly(vinyl methyl ether), poly(vinyl ethyl ether), poly(ethylene oxide), hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, methylcellulose, and mixtures thereof. As noted above, the water-absorbent polymer is present in an amount of at least about 25% by weight of the mixture. If the water-absorbent polymer is too high, for example, greater than about 75% by weight, then the open pore membrane structure is not formed. If the water-absorbent polymer is less than about 25% by weight, then poor image density is obtained.
The hydrophilic, fluid-absorbing layer useful in the invention may be gelatin, acetylated gelatin, phthalated gelatin, oxidized gelatin, chitosan, poly(alkylene oxide), a poly(vinyl alcohol), sulfonated polyester, partially hydrolyzed poly(vinyl acetate/vinyl alcohol), poly(acrylic acid), poly(1-vinyl pyrrolidone), poly(sodium styrene sulfonate), poly(2-acrylamido-2-methane sulfonic acid), polyacrylamide or mixtures thereof. In a preferred embodiment of th
Landry-Coltrain Christine J.
Teegarden David M.
Cole Harold E.
Eastman Kodak Company
Leipold Paul A.
Schwartz Pamela R.
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