Stock material or miscellaneous articles – Composite – Of addition polymer from unsaturated monomers
Reexamination Certificate
2002-09-30
2003-08-26
Pezzuto, Helen L. (Department: 1713)
Stock material or miscellaneous articles
Composite
Of addition polymer from unsaturated monomers
C524S706000, C524S710000, C526S264000, C526S265000, C526S274000, C526S287000, C526S288000, C526S303100, C526S304000, C526S307600, C526S307700, C526S328500, C526S329200
Reexamination Certificate
active
06610412
ABSTRACT:
FIELD OF INVENTION
The invention relates to a printing fluid additive which functions as a compatibilizer between the hydrophilic material coating a media surface and the hydrophobic thermal transfer overcoat (TTO) material used in a clear protective TTO overcoat.
BACKGROUND OF THE INVENTION
The use of digital 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 digital printers offer acceptable print quality for many commercial, business, and household 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 digital printer print quality, while further lowering cost to the consumer.
In a digital inkjet printer, an inkjet image is formed when a precise pattern of dots is ejected from a drop-generating device known as a “printhead” onto a printing medium.
Such inkjet images can be formed by either a thermal inkjet or piezoelectric inkjet system. In addition to inkjet, other systems also produce digital printed images. For example, electrostatic (laser) or electroacoustic printers are also used in to produce digital printed images.
The need exists to protect and stabilize digital printed images against, for example, scratch, abrasion, and water damage and against unwanted retransfer of ink from the digital printed image to other surfaces.
Tutt & Tunney (U.S. Pat. No. 5,847,738, issued on Jan. 8, 1999 and assigned to Eastman Kodak Co.) disclose a process for applying a protective overcoat on a digitally printed media. The protective overcoat is obtained through:
a) Charging the printed imaged element to a given polarity or applying a voltage across the surface of the element which is attracted to a conductive surface behind the element;
b) Applying colorless charged particles to the imaged element which causes them to be electrostatically attracted to the surface of the image layer; and
c) Heat-fusing the particles to obtain a protective overcoat over the entire surface of the image layer.
Colorless toner particles well-known in electrophotography are used in the coating process of Tutt & Tunney. Examples of materials mentioned in the patent are: chlorinated polyolefins, polyacrylic acid esters, cellulose derivatives, modified alkyd resins, polyesters, polyurethanes, poly(vinyl acetate), polyamides, ketone resins, polyvinylbutyral, copolymers of vinyl polymers with methacrylates or acrylates, low molecular weight polyethylene, copolymers with siloxanes, polyalkenes, and poly(styrene-co-butyl acrylate), etc.
Nagashima (U.S. Pat. No. 4,738,555 assigned to Toshiba) discloses the use of a thermal print ribbon to thermally transfer and laminate a transparent protective layer of wax, vinyl chloride, vinyl acetate, acrylic resin, styrene or epoxy on the printed image portion of a record substrate.
Tang et al. (U.S. Pat. No. 5,555,011 assigned to Eastman Kodak) disclose a method of laminating, using a thermally-transferable polymeric material, a transparent protective layer over an ink-printed image on a substrate.
Abe et al. (U.S. Pat. No. 5,954,906 assigned to Canon) discloses a method for protecting and covering a printed material on a substrate with a pressure-sensitive transferring protective covering material with at least (a) a first flexible substrate, (b) an adhesive layer, (c) a solid resin layer, and (d) a second flexible substrate, stacked in this order.
Malhotra (U.S. Pat. No. 5,612,777 assigned to Xerox) discloses a method of applying a clear, scratch-resistant, lightfast coating for a substrate having photocopied color images by first, depositing color toner images on a charge retentive surface; second, depositing a clear polymer toner material onto the charge retentive surface; and third, fusing the color toner images and clear polymer toner material onto a substrate.
Another Malhotra patent (U.S. Pat. No. 5,906,905 assigned to Xerox) discloses a method of creating photographic quality digital prints using imaging such as xerography or ink jet by, first, reverse reading toner images on a transparent substrate and then adhering the transparent substrate to a coated backing sheet, coated with a polymeric lightfastness material.
Typically, clear toner materials currently used in the industry are based on a few basic polymer types. In the table below are listed the advantages and disadvantages of these materials when used as an overcoat for digital printed images:
Toner based on:
Advantages
Disadvantages
Styrenated Acrylics
Good Elasticity
Poor Fusability (high
& Toughness
softening temperature); Poor
gloss and clarity
Low MW
Low melting
Very poor mechanical
Polyesters
temperature; low
properties (no flexibility and
melt viscosity; good
abrasion resistance); poor
clarity; fair gloss
resistance to digital printer
ink solvents
Polyolefins
Good fusibility;
Poor abrasion resistance;
good elasticity
Poor clarity and gloss; waxy
feel
Core/shell polymers are well-known; such polymers typically have a hydrophilic portion and a hydrophobic portion comprising a latex particle morphology consisting of an inner “core”, surrounded by an outer “shell”. Core/shell polymers are commonly used to disperse molecules or particles, such as pigments, which are ordinarily insoluble in water, but which, after association with the core/shell polymer, form stable dispersions in water. Encapsulation occurs when the hydrophobic portion of the polymer associates with the water-insoluble molecule, and the hydrophilic portion of the polymer disperses with water.
U.S. Pat. No. 4,597,794 discloses the dispersion of pigments in an aqueous vehicle, using aqueous binders comprising both hydrophilic and hydrophobic components. The dispersion of the pigment is followed by centrifugation to eliminate the non-dispersed components such as agglomerates. Examples of the hydrophilic component comprise polymers of monomers having a mainly additively polymerizable vinyl group, into which hydrophilic construction portions such as carboxylic acid groups, sulfonic acid groups, sulfate groups, etc. are introduced by using a predetermined amount of an alpha , beta-unsaturated monomer such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, itaconic acid monoester, maleic acid, maleic acid monoester, fumaric acid, fumaric acid monoester, vinyl sulfonic acid, sulfoethyl methacrylate, sulfopropyl methacrylate, sulfonated vinylnaphthalene, etc. Examples of the hydrophobic portion comprise polymers of monomers selected from the group consisting of styrene, styrene derivatives, vinylnaphthalene, vinylnaphthalene derivatives, and alpha , beta-ethylenic unsaturated carboxylate of aliphatic alcohol having C8-C18. In addition to the foregoing monomers, also included are acrylonitrile, vinylidene chloride, alpha, beta-ethylenic unsaturated carboxylate, vinyl acetate, vinyl chloride, acrylamide, methacrylamide, hydroxyethyl methacrylate, hydroxypropyl methacrylate, glycidyl methacrylate, N-methylol acrylamide, N-butoxymethyl acrylamide, etc.
U.S. Pat. No. 5,082,757 discloses encapsulated toner compositions comprising a core and a hydroxylated polyurethane microcapsule shell derived from the polycondensation of a polyisocyanate and a water soluble carbohydrate. The core comprises a polymer binder, pigment, dye, or mixtures thereof. Examples of the polymer binder include polymerized monomers selected from the group consisting of acrylates, methacrylates, and olefins including styrene and its derivatives.
U.S. Pat. No. 5,461,125 discloses waterborne core-shell latex polymers useful as adhesive films, rather than super-dispersion stability. The core comprises a (co)polymer comprising a (meth)acrylate ester, while the shell comprises a copolymer, the copolymer comprising (1) a nitrogen-bearing ethylenically-unsaturated free-radically polymerizable monomer, (2) at least one (meth)acrylate ester of about a C
Haymond W. Bradley
Hewlett--Packard Development Company, L.P.
Pezzuto Helen L.
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