Stock material or miscellaneous articles – Structurally defined web or sheet – Discontinuous or differential coating – impregnation or bond
Reexamination Certificate
1999-02-04
2002-09-24
Thibodeau, Paul (Department: 1773)
Stock material or miscellaneous articles
Structurally defined web or sheet
Discontinuous or differential coating, impregnation or bond
C428S209000, C428S458000, C428S461000, C427S152000, C427S541000, C101S457000, C101S463100, C101S465000, C101S466000
Reexamination Certificate
active
06455132
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a printable media, such as a lithographic printing member, and an ink jet printing process for production thereof. Lithographic printing members of the present invention exhibit good resolution and are suitable for press runs of over 100,000 copies.
BACKGROUND OF THE INVENTION
The offset lithographic printing process utilizes a planographic printing plate having oleophilic image areas and hydrophilic non-image areas. The plate is commonly dampened before or during inking with an oil-based ink composition. The dampening process utilizes an aqueous fountain solution such as those described in U.S. Pat. Nos. 3,877,372, 4,278,467 and 4,854,969. When water is applied to the plate, the water will form a film on the hydrophilic areas (i.e. the non-image areas of the plate) but will contract into tiny droplets on the oleophilic plate areas (i.e. the image areas). When a roller carrying an oil-based ink composition is passed over the dampened plate, it will be unable to ink the areas covered by the aqueous film (the non-image areas), but will emulsify the water droplets or the water repellant areas (the image areas) which will then adsorb ink. The resulting ink image is transferred (“offset”) onto a rubber blanket, which is then used to print a substrate such as paper.
Lithographic printing plates can be manufactured using a mask approach and a dye-based hot melt ink jet ink. For example, U.S. Pat. No. 4,833,486 discloses a dye-based hot melt ink composition which is jetted onto a conventional photopolymer plate. The deposited ink acts as a mask during plate exposure, and is removed from the plate together with the exposed photopolymer during development of the plate. This technique involves multiple processing steps such as UV-irradiation, chemical development and plate drying, which result in high production costs and environmental concerns.
It has been proposed to apply “direct” ink jet printing techniques to lithographic printing. For example, European Patent Publication No. 503,621 discloses a direct lithographic plate making method which includes jetting a photocuring ink onto the plate substrate, and exposing the plate to UV radiation to harden the image area. An oil-based ink may then be adhered to the image area for printing onto a printing medium. However, there is no disclosure of the resolution of ink drops jetted onto the substrate, or the durability of the lithographic printing plate with respect to printing runlength.
Canadian Patent No. 2,107,980 discloses an aqueous ink composition which includes a first polymer containing a cyclic anhydride or derivative thereof and a second polymer that contains hydroxyl sites. The two polymers are thermally crosslinked in a baking step after imaging of a substrate. The resulting matrix is said to be resistant to an acidic fountain solution of an offset printing process, and to be capable of providing a resolution (dot size) of 40 microns. The Examples illustrate production of imaged masters said to be capable of lithographic runlengths of from 35,000 to 65,000 copies, while a non-crosslinked imaged master exhibited a runlength of only 4,000 copies.
Both of these direct lithographic proposals require a curing step, and the Canadian patent illustrates the importance of this curing step to extended runlengths. The present invention eliminates the need for such a thermal or irradiation step while providing a direct lithographic master capable of a runlength of at least 100,000 copies.
Ink compositions intended for ink jet printers must be carefully formulated to satisfy demanding requirements, which include resistance to drying on the ink jet nozzles while stored in an ink jet print head, drying time, ink density and droplet spreading (expansion) once applied onto the printing substrate. These requirements can conflict. For example, the ink composition must not clog the small diameter nozzles of the ink jet printer over time. However, the ink must also be capable of rapid drying once it is applied to the printing substrate. In this regard, the drying time for a commercially available ink jet composition is less than one second, with an advertised resolution of 1,440 dots-per-inch. See generally, “Ink-jet Inks”,
The Printing Ink Manual
(5th ed. 1993).
It is known to improve the resolution of ink jet printers by applying an ink receiving layer to substrates such as metal, plastic, rubber, fabrics, leather, glass and ceramics, prior to printing thereon. See, for example, European Patent Publication No. 738,608 which discloses a thermally curable ink receiving layer containing a first water soluble high molecular weight compound having a cationic site in the main polymer chain and a second water soluble high molecular compound having a side chain containing a condensable functional site. Alternatively, the second high molecular weight compound may be replaced with a monomer or oligomer having at least two (meth)acryloyl sites, which results in a UV radiation curable ink receiving layer. In either case, the cationic site of the first polymer is said to permit an ink solvent to readily penetrate the ink receiving layer. The ink receiving layer of the present invention does not require either a thermal or an irradiation curing step.
U.S. Pat. No. 5,364,702 discloses an ink-jet recording medium which contains at least one of acetylene glycol, ethylene oxide addition product and acetylene glycol and acetylene alcohol, each of which have a triple bond in its molecule. The ink receiving layer may also contain an inorganic pigment, a water-soluble polymeric binder, and a cationic oligomer or polymer. The present invention is directed to lithographic masters and employs a copolymer having a plurality of amine sites, which are at least partially neutralized with an acid.
U.S. Pat. No. 4,781,985 discloses an ink jet transparency which includes a substantially transparent resinous support, and a substantially clear coating thereon which contains a specified fluorosurfactant which serves to prevent trailing of the ink-jet ink. The substantially clear coating may be about 2-15 microns thick. The present invention is directed to a lithographic master rather than an ink jet transparency, and may employ a desorbable fluorosurfactant pretreatment applied as a monolayer.
U.S. Pat. No. 5,820,932 discloses a process for the production of lithographic printing plates. Ink jet liquid droplets form an image upon the surface of a printing plate corresponding to digital information depicting the image as provided by a digital computer system which is in digital communication with the printer heads. The droplets from the printer head comprise resin forming reactants which polymerize on the plate surface, alone or in combination with reactant precoated on the plate, to form a printable hard resin image. The resin image so formed provides a lithographic printing plate useful for extended print runs. In contrast, the present invention does not require polymerization of the fluid composition jetted upon the printable media substrate.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a fluid composition which may be applied by an ink jet printing apparatus to directly image a substrate, and thereby produce a printable media.
Another object of the present invention is to provide a lithographic printing member capable of extended runlengths which exhibits good resolution and good ink transfer.
An advantage of the present invention is the elimination of the exposure and chemical development steps of conventional lithographic master printing plate manufacturing processes, thereby achieving lower production cost and an environmentally-friendly process.
In one aspect, the present invention relates to a fluid composition suitable for ink jetting upon a substrate, wherein the fluid composition includes a copolymer having a low surface energy and a plurality of tertiary amine sites, where the amine sites are at least partially neutralized with an acid; a nonionic or cationic surfactant; and water.
T
Aurenty Patrice M.
Keaveney William P.
Stone Edward
Baker & Botts L.L.P.
Jackson Monique R.
Kodak Polychrome Graphics LLC
Thibodeau Paul
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