Ink jet printing method

Incremental printing of symbolic information – Ink jet – Medium and processing means

Reexamination Certificate

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C428S195100

Reexamination Certificate

active

06481843

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to an ink jet printing method, more particularly to a method using 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.
Inkjet 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.
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, the amount of the mordant to be used is up to 3% by weight of the hydrophobic polymer, which corresponds to a maximum amount of about 2-3% by weight of the total polymer mixture. There is a problem with using only 3% of the mordant as this low a level does not provide adequate water fastness, as will be shown hereafter.
It is an object of this invention to provide an ink jet printing method using a recording element which will provide improved ink uptake speed. Another objective of the invention is to provide an ink jet printing method using an ink jet recording element having a receiving layer that when printed upon has an excellent image quality. Still another objective of the invention is to provide an ink jet printing method using an ink jet recording element having a receiving layer wherein the printed image has improved water fastness.
SUMMARY OF THE INVENTION
These and other objects are provided by the present invention comprising ink jet printing method, comprising the steps of:
A) providing an ink jet printer that is responsive to digital data signals;
B) loading the printer with an ink jet recording element comprising a support having thereon an image-receptive layer capable of accepting an ink jet image, the layer comprising an open-pore membrane of a mixture of a water-insoluble polymer, a water-absorbent polymer and a mordant, the mixture containing at least about 25% by weight of the water-absorbent polymer, at least about 7% by weight of the mordant, and the balance being the water-insoluble polymer, the mordant comprising a polymer or copolymer containing a quatemized nitrogen moiety;
C) loading the printer with an ink jet ink composition; and
D) printing on the ink jet recording element using the ink jet ink in response to the digital data signals.
Using the invention, a recording element is obtained which will provide improved ink uptake speed 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 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 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), hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, methylcellulose, and mixtures thereof.
The mordant comprising a polymer or copolymer containing a quatemized nitrogen moiety used in the invention serves to improve the fixability of an ink jet image, thereby improving water fastness and smear. The mordant polymer can be a soluble polymer, or a crosslinked dispersed microparticle.
The mordant polymer or copolymer containing a quatemized nitrogen moiety which is useful in the invention can contain other comonomers such as, for example, styrenics, acrylates, imidazoles, vinylpyridines, etc. Examples of specific mordants include poly(styrene-co-1-vinylimidazole-co-1-vinyl-3-benzylimidazolium chloride), poly(styrene-co-1-vinylimidazole-co-1-vinyl-3-hydroxyethyl-imidazolium chloride), poly(styrene-co-1-vinylimidazole-co-1-vinyl-3-benzylimidazolium chloride-co-1-vinyl-3-hydroxyethylimidazolium chloride), poly(vinylbenzyltrimethylammonium chloride-co-divinylbenzene), poly(ethyl acrylate-co-1-vinylimidazole-co-1-vinyl-3-benzylimidazolium chloride), or poly(styrene-co-4-vinylpyridine-co-4-hydroxyethyl-1-vinylpyridinium chloride).
In a preferred embodiment of the invention, the quaternary nitrogen moiety is a salt of trimethylvinylbenzylammonium, benzyldimethylvinylbenzylammonium, dimethyloctadecylvinylbenzylammonium, 1-vinyl-3-benzylimidazolium, 1-vinyl-3-hydroxyethyli

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