Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
2003-01-21
2004-06-01
Meier, Stephen (Department: 2853)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
C347S101000, C101S457000, C101S466000
Reexamination Certificate
active
06742886
ABSTRACT:
BACKGROUND OF THE INVENTION
The art of lithographic printing is based on the immiscibility of ink and water. A lithographic printing plate is composed of ink receptive regions, commonly referred to as the “image area,” generated on a hydrophilic surface of a substrate. When the surface of the printing plate is moistened with water and printing ink is applied, exposed portions of the hydrophilic surface retain the water and repel the printing ink, and the oleophilic image area accepts the printing ink and repels the water. The printing ink retained on the oleophilic image area may then be transferred to the surface of a material upon which the image is to be reproduced. Typically, the ink is first transferred to an intermediate blanket, which in turn transfers the ink to the desired surface.
One method for forming or generating an oleophilic image area on a substrate is by coating the substrate with a radiation-sensitive layer, and then exposing a portion of the layer to IR or UV radiation. The unexposed portion of the coated substrate (negative-working plates) or the exposed portion of the coated substrate (positive-working plates) then undergoes chemical development to form the oleophilic image area. One drawback to using printing plates incorporating this method of producing an oleophilic image area is that, after exposing the radiation-sensitive layer to radiation, the plates must be subjected to chemical processing (e.g., development in an alkaline solution) to form the image area.
An alternative method for forming an oleophilic image area on a substrate is by imagewise applying an ink jettable composition onto the substrate. Ink jetting of an oleophilic image area may be desirable because it requires no chemical processing prior to use. There are a variety of oleophilic materials suitable for ink jetting onto a substrate to form an oleophilic image area. Generally, these materials are soluble in either aqueous or organic carriers. For example, U.S. Pat. Nos. 6,359,056 and 6,131,514, and PCT Published Applications WO /0037254 and WO 01/34934 all report ink jettable materials that are soluble or form dispersions in aqueous solutions. However, for certain applications, it may be desirable to employ an oleophilic material that is soluble in an organic carrier.
SUMMARY OF THE INVENTION
In one embodiment, the present invention provides a method of preparing a printing plate. An ink jettable composition composed of an oleophilic polymer in substantially organic solvent is imagewise applied onto a substrate. The oleophilic polymer is then adhered to the substrate. Oleophilic polymers for use in this invention contain polar moieties, with the exception of nitrogen-containing heterocyclic moieties, and the moieties are essentially chemically unchanged when adhered to the substrate. Methods of adhering the oleophilic polymer include air or oven drying the printing plate and/or exposing the printing plate to UV light.
The oleophilic polymer used in the ink jettable composition of the present invention may be film-forming and adhere to the surface of the substrate to form an oleophilic image area. The oleophilic polymer generally contains polar moieties and is compatible with suitable organic solvents. Suitable oleophilic polymers include polyester resins, diazonium compounds, acrylic acid polymer derivatives, acetal resins, polyamide resins and phenolic resins. Suitable organic solvents include benzyl alcohol, 2-phenoxyethanol, diethyl ketone/methyl lactate/water, 1-methoxypropan-2-ol and ethyl-3-ethoxypropanol.
In another embodiment, the present invention provides a method of forming an image on a substrate. An ink jettable composition composed of an oleophilic polymer in substantially organic solvent is imagewise applied onto a substrate. The oleophilic polymer has polar moieties, with the exception of nitrogen-containing heterocyclic moieties.
In yet another embodiment, the present invention provides a lithographic printing plate composed of a substrate and an oleophilic image area. The oleophilic image area is composed of an oleophilic polymer and may contain other nonvolatile components or additives of the ink jettable composition. The oleophilic polymer includes polar moieties with the exception of nitrogen-containing heterocyclic moieties.
The ink jettable composition of the present invention has several characteristics beneficial for forming oleophilic image areas. First, the composition is suitably oleophilic to uptake ink to provide an inked image, but may readily transfer the inked image to a desired medium. Second, the composition forms a thin-film that adheres well to a variety of substrates to form a durable image area. Third, oleophilic image areas formed by the ink jettable composition of the present invention require no additional chemical processing prior to use.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides an ink jettable composition capable of forming oleophilic image areas on a substrate for use in a variety of printing plate applications. In one embodiment, an ink jettable composition according to the present invention includes an oleophilic polymer having polar moieties in a substantially organic solvent.
Suitable oleophilic polymers according to the present invention adhere effectively to a substrate and include polar moieties. In certain embodiments, the polymer may be composed of a polymeric backbone with one or more polar moieties. Suitable polar moieties may include carboxyl, hydroxyl, carbonyl, amine, amide, ammonium or sulfate groups. However, the polymer is free of nitrogen-containing heterocyclic moieties.
Examples of suitable polymers having polar moieties include derivatives of polyester resins, diazonium compounds, acrylic acid polymers, acetal resins, phenolic resins, polyamide resins and combinations thereof.
Suitable polyester resin derivatives include, for example, polyester acrylate, polyester resins having a phenolic hydroxyl group, and polyesters formed from p-hydroxybenzoic acid containing hydroxyl and carboxylate moieties. In one embodiment, the polyester resin is formed as a reaction product of diethyl-p-phenylenediacrylate and 1,4-bis(&bgr;-hydroxyethoxy)-cyclohexane, referred to hereinafter as Polymer A.
Other suitable resins include polymeric diazonium compounds or a mixture of polymeric diazonium compounds. A variety of these materials are known. These compounds may be prepared, for example, by condensation of monomers, such as monomers described in DE 2024244, with a condensation agent, such as formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, isobutyraldehyde or benzaldehyde. Furthermore, mixed condensation products may be used which, apart from the diazonium salt units, comprise other non-photosensitive units which are derived from condensable compounds, in particular from aromatic amines, phenols, phenol ethers, aromatic thioethers, aromatic hydrocarbons, aromatic heterocycles or organic acid amides.
Especially useful polymeric diazonium compounds are reaction products of diphenylamine-4-diazonium salts, optionally having a methoxy group in the phenyl group bearing the diazonium salt units, with formaldehyde or 4,4-bis-methoxy-methyl diphenyl ether. Dihydrogen phosphate, hexafluorophosphate, hexafluoroantimonate, hexafluoroarsenate, tetrafluoroborate, and aromatic sulfonates such as 4-tolyl-sulfonate or mesitylene sulfonate are particularly suitable counterions for these polymeric diazo resins.
In one embodiment, the diazonium compound is derived from the condensation of 3-methoxy-diphenylamine-4-diazonium sulfate and 4,4′-bis-methoxymethyldiphenylether isolated as the mesitylene sulfonate salt and is available under the tradename NEGA 107 from Panchim, Lisses, France.
Suitable acrylic acid polymer derivatives may include acrylic resins containing one or more monomers having an acidic group, for example polyhydroxystyrene, polyhalogenated hydroxystyrene, N-(4-hydroxyphenyl)methacrylamide, hydroquinone monomethacrylate, N-(sulfamoylphenyl)methacrylamide, N-phenylsulfonylmethacrylamide, N-phen
Faegre & Benson LLP
Kodak Polychrome Graphics LLE
Meier Stephen
Shah Manish
LandOfFree
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