Coating processes – Nonuniform coating – Applying superposed diverse coatings or coating a coated base
Reexamination Certificate
2002-01-15
2003-04-29
Beck, Shrive P. (Department: 1762)
Coating processes
Nonuniform coating
Applying superposed diverse coatings or coating a coated base
C427S288000, C427S411000, C427S412100
Reexamination Certificate
active
06555168
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an ink jet printing method which employs a porous receiver and an ink jet composition which provides improved light and dark stability.
BACKGROUND OF THE INVENTION
Ink jet printing is a non-impact method for producing images by the deposition of ink droplets on a substrate (paper, transparent film, fabric, etc.) in response to digital signals. Ink jet printers have found broad applications across markets ranging from industrial labeling to short run printing to desktop document and pictorial imaging. The inks used in ink jet printers are generally classified as either dye-based or pigment-based.
A dye is a colorant which is molecularly dispersed or solvated by a carrier. The carrier can be a liquid or a solid at room temperature. A commonly used carrier is water or a mixture of water and organic co-solvents. Each individual dye molecule is surrounded by molecules of the carrier. In dye-based inks, no particles are observable under the microscope. Although there have been many recent advances in the art of dye-based ink jet inks, such inks still suffer from deficiencies such as low optical densities on plain paper and poor light-fastness. When water is used as the carrier, such inks also generally suffer from poor water fastness.
U.S. Pat. Nos. 4,246,154 and 5,852,074 relate to an ink jet ink composition comprising a water-insoluble dye dispersed in a water-dispersible polymer. However, there is a problem with this ink in that when it is printed onto a conventional receiver, the dry time is slow.
U.S. Pat. No. 4,460,637 relates to a porous ink jet receiver element. However, there is a problem with this element in that when it is printed with a conventional aqueous dye-based ink, the printed image has poor light and dark stability.
It is an object of this invention to provide an ink jet printing method which provides an image which has a fast dry time. It is another object of this invention to provide an ink jet printing method which provides an image which has improved light and dark stability.
SUMMARY OF THE INVENTION
These and other objects are achieved in accordance with this invention which relates to an 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 ink-receptive elements comprising a support having thereon a continuous, coextensive porous ink-receptive layer,
C) loading the printer with an ink jet ink composition comprising an aqueous-dispersible polyester having contained therein a water-insoluble dye, and
D) printing on the ink-receptive element using the ink jet ink in response to the digital data signals.
DETAILED DESCRIPTION OF THE INVENTION
The support for the ink-receptive element can be paper or resin-coated paper, or plastics such as a polyester-type resin such as poly(ethylene. terephthalate), polycarbonate resins, polysulfone resins, methacrylic resins, cellophane, acetate plastics, cellulose diacetate, cellulose triacetate, vinyl chloride resins, poly(ethylene naphthalate), polyester diacetate, various glass materials, etc. The thickness of the support employed in the invention can be, for example, from about 12 to about 500 &mgr;m, preferably from about 75 to about 300 &mgr;m.
In a preferred embodiment of the invention the continuous, coextensive porous ink-receptive layer contains inorganic particles such as silica, alumina, titanium dioxide, clay, calcium carbonate, barium sulfate, or zinc oxide. In another preferred embodiment, the porous ink-receptive layer comprises from about 20% to about 90% inorganic particles and from about 10% to about 80% polymeric binder, such as gelatin, poly(vinyl alcohol), poly(vinyl pyrrolidinone) or poly(vinyl acetate). The porous ink-receptive layer can also contain polymer micro-porous structures without inorganic filler particles as shown in U.S. Pat. Nos. 5,374,475 and 4,954,395.
A broad range of water-insoluble dyes may be used in the invention such as an oil dye, a disperse dye, a solvent dye, as disclosed in U.S. Pat. Nos. 4,246,154 and 5,852,074, or a metal-complex dye, such as the water-insoluble analogues of those described in U.S. Pat. Nos. 5,997,622 and 6,001,161, i.e., a transition metal complex of an 8-heterocyclylazo-5-hydroxyquinoline.
The dye-containing aqueous-dispersible polyester used in the invention can be prepared by dissolving the dye in a water-miscible organic solvent, mixing the solution with the aqueous-dispersible polyester and then removing the solvent. Useful water-miscible organic solvents are water-miscible alcohols, ketones and amides, tetrahydrofuran, N-methyl-2-pyrrolidone, dimethylsulfoxide and mixtures thereof, such as acetone, ethyl alcohol, methyl alcohol, isopropyl alcohol, dimethylformamide, methyl-ethyl ketone etc.
The ink jet ink containing the water-dispersible polyester employed in the invention consists of water as a continuous phase and dye-containing polyester as a dispersed phase. In a preferred embodiment of the invention, the aqueous-dispersible polyester meets the following test: At 25° C., the aqueous-dispersible polyester must: (a) be capable of forming a stable dispersion with water at a concentration of from 0.2 to 50 percent by weight, preferably 1 to 20 percent by weight, and (b) when 100 ml of the aqueous-dispersible polyester is then mixed in an equal volume of the water-miscible organic solvent described above, stirred and allowed to stand for 10 minutes exhibit no observable coagulation of the aqueous-dispersible polyester. In order to be useful in the ink, the aqueous-dispersible polyester should have an average particle size of <1 &mgr;m, preferably <0.2 &mgr;m.
In a preferred embodiment of the invention, the water-dispersible polyester contains dicarboxylic acid recurring units and diol recurring units consistent with the following general formula:
wherein:
R
1
and R
2
each independently represents a saturated or unsaturated divalent hydrocarbon, or aromatic or aliphatic group or contains both aromatic and aliphatic groups, such as 1,2-phenylene, 1,3-phenylene, 1,4-phenylene, 1,4-naphthylene, 2,6-naphthylene, 4,4′-oxydiphenylene, 1,4-cyclohexylene, 1,2-ethylene, 1,4-butylene, and the like;
Z represents an ionic moiety derived from a sulfonic acid.
x represents a mole fraction from about 0.05 to about 0.8;
R
3
represents S; an alkylene group of 1 to about 16 carbon atoms, a cycloalkylene group of 5 to about 20 carbon atoms; a cyclobisalkylene group of about 8 to about 20 carbon atoms; a bi- or tri-cycloalkylene group of about 7 to about 16 carbon atoms; a bi- or tri-cyclobisalkylene group of about 9 to about 18 carbon atoms; an arylenebisalkylene group of from 8 to about 20 carbon atoms or an arylene group of 6 to about 12 carbon atoms; or a carbinol-teiminated polydimethylsiloxane segment,
R
4
and R
5
each independently represents H, a substituted or unsubstituted alkyl group of 1 to about 6 carbon atoms or a substituted or unsubstituted aryl group of about 6 to about 12 carbon atoms; and
m and n each independently represents an integer from 0-4.
In a preferred embodiment of the invention, the dicarboxylic acid recurring units contain an ionic moiety derived from a sulfonic acid and includes the following:
wherein:
M
+
represents alkali metals, such as Li, Na and K; ammonium groups such as ammonium, trimethylammonium, triethylammonium, tetraalkylammonium, aryltrialkylammonium, hydroxyalkylammonium, etc., phosphonium groups such as triphenylphosphonium or tetrabutylphosphonium; heteroaromatic ammonium groups such as pyridinium, imidazolium or N-methylammonium; sulfonium groups; guanidinium groups; amidinium groups, etc. Preferably, M
+
is an alkali metal, for example Na
+
.
In a preferred embodiment of the invention, the nonionic dicarboxylic acid recurring unit is isophthalic acid, and is present in a mole fraction from approximately 0.2 to approximately 0.95, more preferably from approximately 0.6 to approximately 0.90.
In another preferred embodiment of the invention, the
Chen Huijuan
Evans Steven
Reczek James
Beck Shrive P.
Cole Harold E.
Eastman Kodak Company
Jolley Kirsten Crockford
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