Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1998-10-20
2001-04-24
Jagannathan, Vasu (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C523S161000, C106S031600
Reexamination Certificate
active
06221932
ABSTRACT:
TECHNICAL FIELD
The present invention relates to ink-jet ink compositions that comprise pigment particles (macromolecular chromophores) having both functional groups attached for water solubility and polymer chains covalently attached to the pigments by nucleophilic substitution. These pigmented inks have enhanced smearfastness, enhanced print quality, improved bleed control, and improved resistance to water when applied to the media, and are more soluble in organic solvents. Moreover, inks formulated with these polymers are characterized with good viscosity and surface tension and are useful in ink-jet printing, including thermal ink jet printing, piezoelectric ink jet printing, and continuous ink jet printing.
BACKGROUND ART
Ink-jet printers offer a low cost, high quality, and comparatively noise-free option to other types of printers commonly used with computers. Such printers employ a resistor element in a chamber provided with an egress for ink to enter from a plenum. The plenum is connected to a reservoir for storing the ink. A plurality of such resistor elements are arranged in a particular pattern, called a primitive, in a printhead. Each resistor element is associated with a nozzle in a nozzle plate, through which ink is expelled toward a print medium. The entire assembly of printhead and reservoir comprise an ink-jet pen.
On operation, each resistor element is connected via a conductive trace to a microprocessor, where current-carrying signals cause one or more selected elements to heat up. The heating creates a bubble of ink in the chamber, which is expelled through the nozzle toward the print medium. In this way, firing of a plurality of such resistor elements in a particular order in a given primitive forms alphanumeric characters, performs area-fill, and provides other print capabilities on the medium.
Ink-jet inks used in thermal ink-jet printing typically comprise a colorant and a vehicle, with the vehicle often containing water and other relatively low surface tension liquids.
There are two general classifications of colorants: dye-base and pigment-based. Dyes have the advantage of being water-soluble. However, problems with dyes include poor waterfastness, poor smearfastness, poor bleed control between colors, and poor lightfastness. Pigments are generally water-insoluble and require a dispersant or other means to make it soluble in water.
Although the relevant art contains many examples of ink-jet ink formulations using these colorants, a need still exists for ink compositions comprising stable, water soluble pigments which provide improved smearfastness, waterfastness, improved print quality, improved bleed control, and optical density.
DISCLOSURE OF INVENTION
In accordance with the invention, an ink-jet ink composition is provided which comprises a colorant that is both water-soluble and contains polymers covalently attached to the colorant by nucleophilic substitution or acylation reactions. The colorants used herein comprise pigment particles, the surface of which are treated with functional groups to provide water-solubility as well as polymers to give exceptional properties in an ink formulation. Such treated pigments are called macromolecular chromophores (MMC). Inks comprising these MMCs are very effective in reducing smear and have increased waterfastness, bleed control, optical density and improved print quality. Bleed control is defined as the invasion of one colored ink printed substantially, simultaneously and adjacently to a second colored ink. Inks containing these MMCs are very effective in reducing smear and has increased waterfastness, optical density and improved print quality. Furthermore, the pigments of this invention are more soluble in organic solvents and provide better bleed control on the print media. The ink may contain further components to aid in providing improved print quality and performance in an ink-jet printer.
Additionally, a method of ink-jet printing which uses the disclosed inks and exploits the inks' properties is provided.
All concentrations herein are in weight percent, unless otherwise indicated. The purity of all components is that employed in normal commercial practice for ink-jet inks. All references are hereby incorporated by reference.
BEST MODES FOR CARRYING OUT THE INVENTION
The MMCs for use in the present ink formula comprises chemical modifications to impart water solubility to the particle. Under typical chemical processes, the resulting surface of the MMC consists of carboxylate, phosphate, and/or sulfonate functionalities for anionic chromophores, and ammonium, quaternary ammonium, or phosphonium functionalities for cationic chromophores.
The MMC colorant particles of the present invention preferably have a useful mean diameter ranging from 0.005 to 12 um. Colorants of this type result from chemical reactions where solvent-accessible functional groups are derivatized to provide solubilizing groups that render the colorant soluble in water. The resulting macromolecular chromophore (MMC) is water-soluble, with its solubility being similar to that of well-known, commercially used water-soluble acidic and basic dyes.
These water-soluble black chromophores are made from commercially available pigments obtained from colorant vendors such as Cabot Corp. and Orient Chemical. Many pigments are useful in the practice of this invention. The following pigments comprise a partial list of useful colorants in this invention.
Paliogen® Orange, Heliogen® Blue L 6901F, Heliogen® Blue NBD 7010, Heliogen® Blue K 7090, Heliogen® Blue L 7101F, Paliogen® Blue L 6470, Heliogen® Green K 8683, and Heliogen® Green L 9140, are all available from BASF Corp.
The following pigments are available from Cabot: Monarch® 1400, Monarch® 1300, Monarch® 1100, Monarch® 1000, Monarch® 900, Monarch® 880, Monarch® 800, and Monarch® 700.
The following pigments are available from Ciga-Geigy: Chromophtal® Yellow 3G, Chromophtal® Yellow GR, Chromophtal® Yellow 8G, Igrazin® Yellow 5GT, Igralite® Rubine 4BL, Monastral® Magenta, Monastralt® Scarlet, Monastral® Violet R, Monastral® Red B, and Monastral® Violet Maroon B.
The following pigments are available from Columbian: Raven 7000, Raven 5750, Raven 5250, Raven 5000, and Raven 3500. The following pigments are available from Degussa: Color Black FW 200, Color Black FW 2, Color Black FW 2V, Color Black FW 1, Color Black FW 18, Color Black S160, Color Black FW S170, Special Black 6, Special Black 5, Special Black 4A, Special Black 4, Printex U, Printex 140U, Printex V, and Printex 140V. Tipure® R-101 is available from Dupont. The following pigments are available from Heubach: Dalamar® Yellow YT-858-D and Heucophthal® Blue G XBT 583D. The following pigments are available from Hoechst: Permanent Yellow GR, Permanent Yellow G, Permanent Yellow NCG-71, Permanent Yellow GG, Hansa Yellow RA, Hansa Brillant Yellow 5GX-02, Hansa Yellow-X, Novoperm® Yellow HR, Novoperm® Yellow FGL, Hansa Brilliant Yellow 10GX, Permanent Yellow G3R-01, Hostaperm® Yellow H4G, Hostaperm® Yellow H3G, Hostaperm® Orange GR, Hostaperm® Scarlet GO, and Permanent Rubine F6B. The following pigments are available from Mobay: Quindo® Magenta, Indofast® Brilliant Scarlet, Quindo® Red R6700, Quindo® Red R6713, Indofast® Violet. The following pigments are available from Sun Chem: L74-1357 Yellow, L75-1331 Yellow, and L75-2577 Yellow.
Modification imparting Water-solubility—The MMCs herein are modified by the addition of one or more organic groups comprising at least one aromatic group or a C1-C12 alkyl group and at least one ionic group or ionizable group. The ionizable group is one that forms in ionic groups in the aqueous medium. The ionic group may be anionic or cationic. The aromatic groups may be further substituted or unsubstituted. Examples include phenyl or a napthyl groups and the ionic group is sulfonic acid, sulfinic acid, phosphonic acid, carboxylic acid, ammonium, quaternary ammonium, or phosphonium group.
Depending on the process selected, the MMC can either be anionic or cationic in character. As commercially available, the
Moffatt John R.
Tsang Joseph W.
Hewlett--Packard Company
Jagannathan Vasu
Jones Michael D.
Shosho Callie E.
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