Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
2000-04-20
2002-06-18
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
C347S100000, C347S095000
Reexamination Certificate
active
06406138
ABSTRACT:
FIELD OF INVENTION
The present invention generally relates to a polymer system useful in inkjet printing systems comprising a multi-pen inkset. The precipitant gel layer of this invention is created by the interaction of two or more fluids. In one embodiment, an ink containing a chitosan salt contacts a reactive, or fixer, fluid containing a polymer to form a gel precipitant. The gel forms a protective film on the medium substrate and provides permanence benefits, such as increased drytime, smearfastness, smudgefastness, and waterfastness.
BACKGROUND OF THE INVENTION
The use of ink-jet printing systems has grown dramatically in recent years. This growth may be attributed to substantial improvements in print resolution and overall print quality, coupled with appreciable reduction in cost. Today's ink-jet printers offer acceptable print quality for many industrial, commercial, business and residential applications at costs fully an order of magnitude lower than comparable products available just a few years ago. Notwithstanding their recent success, intensive research and development efforts continue toward improving the permanence issues of ink-jet images.
Ink jet printing involves ejection of droplets of ink on a media to produce images. Typically these images are not resistant to image degrading factors, such as mechanical abrasion, light, water, and solvents, such as those used in highlighter pens. Advancing inkjet printing technology and consumer demand requires that printing systems become faster with quick drying times, minimum media distortion (i.e., paper cockle), improved permanence, and high chromatic efficiency.
A variety of approaches have been used to address some of these issues. For example, a ‘fifth’ pen or ‘plain paper optimization’ strategy has been used in inkjet products with some success. Other approaches include polymers formulated into inks followed by post treatment with heat or fusion, deposition of toner by electrography, and special additives such as lamellae or vesicle forming surfactants. A need, however, remains for improved products to meet the above needs and deliver consumer satisfaction with inkjet printing.
DETAILED DESCRIPTION OF THE INVENTION
It has been found that by use of a chitosan salt coupled with an aqueous based, polymer can produce the desired effects of improved drytime, smearfastness, waterfastness, improved color, permanence and cockle control. Without being limited by theory, it is believed the chitosan salt and polymers combine to form a gelatinous film upon interaction. Water and colorant are trapped in the film. The chitosan salt can be added to an ink composition or to a fixer fluid, generally known as a 5
th
pen. The polymer should be added to another fluid in the inkset. Additionally, medium printed with the above ink and fixer can be further treated by hear or fusion (a combination of heat and pressure).
Definitions
Fluid—includes either or both the reactant fluid and ink compositions.
Reaction—means that the solubility or phase state of one or more components is changed as to immobilize the movement of at least one colorant on the print medium in the event that one fluid comes in contact with another fluid and interacts.
Reactant Fluid—also known as a 5
th
or 6
th
pen fluid or fixer fluid. A fluid that is typically substantially devoid of color (i.e., the reactant fluid may contain no colorant (e.g., dye or pigment), or it may contain a colorant that does not absorb visible light but may absorb in either or both the IR or UV spectrums). In one embodiment, the reactant fluid comprises a chitosan salt component that is reactive with a polymeric component in an ink, thus providing for enhanced image integrity of printed areas created with the ink, including, increased permanent (e.g. waterfastness, smearfastness, smudgefastness), improved color vibrancy, improved edge acuity, and reduced dry time. In the second embodiment, the chitosan salt is in the ink and the polymer in the 5
th
pen fluid. The ink and fixer fluid are printed at least partially on a same pre-determined area on a print medium, or on pre-determined areas adjacent one another on a print medium. The reactive fluid is reactive with at least one ink formulated according to the present invention. A further 6
th
pen clear fluid, which has additional protective properties, may be printed in addition to the color-containing fluids and the 5
th
pen fluid. Typical fixer fluids without the chitosan-polymer additives of this invention are known in the art.
Ink—a fluid containing at least one colorant, the ink absorbing in one or more regions (e.g., visible, IR, UV, etc.). Ink-jet printers typically contain an ink set with black, magenta, cyan, and yellow inks, commonly known as a 4-pen ink set. Additional pens with additional color inks may also be present, such as a light magenta, a second black, or specialty graphic colors.
The present invention is directed to fluid sets, in particular for use in coloring applications, and more particularly for use in ink-jet printing. The present fluid set combines the benefits of interactive fluids while utilizing pigments or dyes providing enhanced image integrity to the ink-jet formula. The fluid set may be used in many applications of aqueous-based printing inks, in particular ink-jet inks for use in commercially available ink-jet printers such as DESKJET® printers, manufactured by Hewlett-Packard Company, of Delaware; and other commercially available home or office ink-jet printers.
Aqueous inks of this invention comprise, by weight, from about 0.5 to about 20 wt % colorant, preferably from about 1 to about 10%, and more preferably from about 1 to about 6 wt % colorant; from about 0.1 to about 40 wt % of one or more organic solvents. Additional ingredients are independently selected from the group consisting of surfactants, buffers, biocides, and mixtures thereof.
BEST MODES FOR CARRYING OUT THE INVENTION
It has been found that chitosan (polyglucosamines, such as found in exoskeleton matter like crab shells) of approximately 5,000 MW (wt average) in solution can be combined with certain polymers to form a gel layer on a substrate, such as plain paper. Examples of suitable salts of chitosan include: chitosan acetate, chitosan lactate, and chitosan succinate. By “chitosan” or “chitosan salts” as used herein, is also meant the broader class of reactive polymers based on chitosan, polysaccharides, and oxidized glucose, including polyglucosamines, polysaccharides modifed with cationic functionalities, and polysaccharides modified with carboxylate or other anionic functionalities, e.g., carboxy methyl chitosan. Other suitable charged polysaccharides included under the general term “chitosan”, as used herein, include chondrotin sulfate, available from Vanson, Inc., Morristown, N.J. as Polychon™, carboxymethyl cellulose, hyaluronic acid-N-acetyl d-glucosamine and D-glucoronic acid polymer, alginats, alginic acid-1,4 linker polymer of D-mannonuronic acid (D-mannose is a saccharide), carrageenans (with a sulfate content of approximately 15%), and dextran sulfate. Suitable cationic polymers include diethyl aminoethyl cellulose (available as celquat H-100, L-200™ from National Starch Co.), dextran (DEZE™), cationic guars available from Celenese as Jaguars C-14s™, C-15™, and C-17™, Cationic starch, such as cato-72™, from National Starch, and cellulose/starch-dimethyldiallyl ammonium chloride copolymers, such as Floc-Aid 19™ from National Starch.
The chitosan salt, which may be employed alone or in any combination, are present in the ink or in the fixer fluid or fifth pen composition ranging from about 0.1 to 10 wt %. Less than about 5 wt % is preferred. More preferable the fluid contains from about 0.1 to about 1% by wt of chitosan salt. The reactive fluid, in addition to water and the chitosan salt described above, may also contain one or more of the same ingredients and in the same % amounts commonly formulated into inks. For instance, solvents, surfactants, amphiphiles, biocides, buffers may be present in the reactive fluids
Hewlett--Packard Company
Shah Manish S
LandOfFree
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