Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
2000-11-10
2002-08-13
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
C347S106000, C347S096000
Reexamination Certificate
active
06431700
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 an 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.
In co-pending U.S. application Ser. No. 09/510,879, filed Feb. 23, 2000, mentioned above, ink jet compositions are described which provide excellent lightfastness when printed onto a porous ink jet receiver. However, the maximum density obtained with such prints could be improved.
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 porous ink-receptive layer;
C) loading the printer with an ink jet ink composition comprising a water-dispersible polymeric latex having contained therein a water-insoluble, salt-type dye; and
D) printing on the ink-receptive layer using the ink jet ink in response to the digital data signals.
DETAILED DESCRIPTION OF THE INVENTION
The support for the ink-receptive element employed in the invention 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 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 disclosed in U.S. Pat. Nos. 5,374,475 and 4,954,395.
A broad range of water-insoluble, salt-type dyes having a hydrophobic counterion may be used in the invention. In a preferred embodiment of the invention, the water-insoluble, salt-type dye having a hydrophobic counterion may be a cationic dye or an anionic dye. In another preferred embodiment of the invention, the cationic dye is an azo dye, such as a quaternized pyrazoleazoaniline dye as disclosed in U.S. patent application Ser. No. 09/643,281, filed Aug. 22, 2000, the disclosure of which is hereby incorporated by reference; a triarylmethane dye; an azine dye; a phthalocyanine dye; an oxazine dye or a thiazine dye.
Hydrophobic counterions for a cationic water-insoluble salt-type dye which may be used the invention include tetrafluoroborate, perchlorate, hexafluorophosphate and dodecyl sulfonate.
In another preferred embodiment of the invention, the water-insoluble, salt-type dye having a hydrophobic counterion may be an anionic dye such as a metal-complex dye, such as a transition metal complex of an 8-heterocyclylazo-5-hydroxyquinoline; an azo dye, such as C.I. Direct Yellow 132; a phthalocyanine dye such as C.I. Direct Blue 199; an anthraquinone dye, or an anthrapyridone dye. U.S. patent application Ser. No. 09/387,585, filed Aug. 31, 1999 of Erdtmann et al. discloses examples of the above dyes.
Hydrophobic counterions for an anionic water-insoluble salt-type dye which may be used the invention include quaternary ammonium, phosphonium and alkyl pyridinium.
The water-insoluble, salt-type dyes having a hydrophobic counterion used in the invention are not novel and may be prepared using techniques as described in U.S. Pat. No. 3,945,836 and EP 0534365 A1. The solubility in water of the water-insoluble, salt-type dyes having a hydrophobic counterion used in the invention should be <1% by weight, preferably <0.5% by weight, and more preferably <0.1% by weight.
The dye-containing polymeric latex employed in the invention can be prepared by dissolving the dye in a water-miscible organic solvent, mixing the solution with the latex 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 polymeric latex employed in the invention consists of water as a continuous phase and dye-containing polymeric latex as a dispersed phase. In a preferred embodiment of the invention, the polymeric latex meets the following test: At 25° C., the polymeric latex 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 latex 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 polymeric latex. In order to be useful in the ink, the latex should have an average particle size of <1 &mgr;m, preferably <0.5 &mgr;m.
Aqueous lattices can be prepared by free radical polymerization or by condensation polymerization. Emulsion polymerization is the preferred method of preparing polymer lattices. Monomers suitable to prepare the polymer lattices for this application include an acrylic acid, for example, acrylic acid, .alpha.-chloroacrylic acid, an .alpha.-alkylacrylic acid (such as methacrylic acid, etc.), etc., an ester or amide derived from an acrylic acid (for example, acrylamide, methacrylamide, n-butylacrylamide, t-butylacrylamide, diacetone acrylamide, methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, tert-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylat
Carroll-Lee Ann L.
Chen Huijuan D.
Erdtmann David
Evans Steven
Barlow John
Cole Harold E.
Eastman Kodak Company
Shah Manish S.
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