Stock material or miscellaneous articles – Structurally defined web or sheet – Discontinuous or differential coating – impregnation or bond
Reexamination Certificate
2000-07-27
2002-12-24
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
06497941
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
Reference is made to commonly-assigned, copending U.S. patent application Ser. No. 09/627,052, filed of even date herewith, of Landry-Coltrain et al. entitled “Ink Jet Printing Method”, the teachings of which are incorporated herein by reference.
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.
U.S. Pat. No. 4,849,457 discloses a porous membrane for use as a recording medium for ink jet printing comprising a mixture of two water-insoluble polymers and about 9% of polyvinylpyrrolidone. However, there is a problem with this element in that the density obtained with an element having less than about 25% by weight of a water-absorbent polymer is too low, as will be shown hereafter. Further, this membrane is made by coating the two materials from a solvent, and then passing the coated element through a nonsolvent bath. The porous membrane employed in this invention is formed solely upon drying of the coated solution without the need for a nonsolvent bath.
JP95040647A discloses a porous membrane for use as a recording medium for ink jet printing comprising a mixture of a hydrophobic binder containing cationic conductive macromolecules. However, there is a problem with this element in that the density and dye lightfastness obtained with an element having less than about 25% by weight of a water-absorbent polymer is too low, as will be shown hereafter.
U.S. Pat. No. 5,374,475 discloses a porous layer for ink jet printing comprising a thermoplastic polymer free of filler. However, there is a problem with this element in that the density obtained with an element without a water-absorbent polymer is too low, as will be shown hereafter.
U.S. Pat. No. 5,759,639 discloses a printing medium for ink jet printing which uses a polymeric dope solution. A porous layer is formed using a phase inversion technique. Although a second polymer is used in the process, most of it is washed out in a coagulation step. There is a problem with this element in that the density obtained with an element having less than about 25% by weight of a water-absorbent polymer is too low, as will be shown hereafter.
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. There is a problem with the elements formed by this process in that a separate washing step is employed which adds to the complexity of the coating process.
It is an object of this invention to provide an ink jet recording element which will provide improved ink uptake speed. Another objective of the invention is to provide an ink jet recording element having a receiving layer that when printed upon has an excellent image quality.
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 an image-receptive layer capable of accepting an ink jet image, said 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, the image-receiving layer being made by dissolving the mixture of polymers in a solvent mixture, the solvent mixture comprising at least one solvent which is a good solvent for the water-insoluble polymer and at least one poor solvent for the water-insoluble polymer, the poor solvent having a higher boiling point than the good solvent, coating the dissolved mixture on the support, and then drying to remove approximately all of the solvents to obtain the open-pore membrane.
Using the invention, a recording element is obtained which will provide improved ink uptake speed and when printed upon has an excellent image quality.
DETAILED DESCRIPTION OF THE INVENTION
In order for the image-receptive layer 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. The formation of an open-pore membrane is accomplished by using a mixture of a good and poor solvent for the water-insoluble polymer. As noted above, 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 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 is used in 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), hydroxyethylcellu
Franklin Linda M.
Hoffman Christopher R.
Landry-Coltrain Christine
Teegarden David M.
Cole Harold E.
Eastman Kodak Company
Schwartz Pamela R.
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