Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Reexamination Certificate
2001-02-06
2002-02-12
Goodrow, John (Department: 1753)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Post imaging process, finishing, or perfecting composition...
Reexamination Certificate
active
06346357
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention is generally directed to liquid developer compositions and processes thereof and wherein there can be generated improved developed images thereof in bipolar ion charging processes, and reverse charge imaging and printing development (RCP) processes, reference U.S. Pat. No. 5,826,147, the disclosure of which is totally incorporated herein by reference, and wherein the developer contains no charge director, or wherein the developer contains substantially no charge director. More specifically, the liquid developer of the present invention is clear in color and is comprised of a resin, a hydrocarbon carrier, and a charge acceptor component with, for example, a high dielectric constant, and yet more specifically, wherein the charge acceptor component is comprised of an alumina, especially neutral, acid, or basic aluminas with a nanoparticle size, such as zirconates, like calcium zirconate, metal tungstates, calcium titanates, barium titanates, and the like.
The present invention is also specifically directed to a electrostatographic imaging process wherein an electrostatic latent image bearing member containing a layer of marking material, toner particles, or liquid developer as illustrated herein and containing a charge acceptance additive, which additive may be coated on the developer, is selectively charged in an imagewise manner to create a secondary latent image corresponding to the electrostatic latent image on the imaging member. Imagewise charging can be accomplished by a wide beam charge source for introducing free mobile charges or ions in the vicinity of the electrostatic latent image coated with the layer of marking material or toner particles. The latent image causes the free mobile charges or ions to flow in an imagewise ion stream corresponding to the latent image. These charges or ions, in turn, are accepted by the marking material or toner particles, leading to imagewise charging of the marking material or toner particles with the layer of marking material or toner particles itself becoming the latent image carrier. The latent image carrying toner layer is subsequently developed by selectively separating and transferring image areas of the toner layer to a copy substrate for producing an output document.
The present invention also relates to an imaging apparatus wherein an electrostatic latent image, including image and non-image areas, is formed in a layer of marking material, and further wherein the latent image can be developed by selectively separating portions of the latent image bearing layer of the marking material such that the image areas reside on a first surface and the non-image areas reside on a second surface. In a simple embodiment, the invention can be defined as an image development apparatus, comprising a system for generating a first electrostatic latent image on an imaging member, wherein the electrostatic latent image includes image and non-image areas having distinguishable charge potentials, and a system for generating a second electrostatic latent image on a layer of marking materials situated adjacent the first electrostatic latent image on the imaging member, wherein the second electrostatic latent image includes image and non-image areas having distinguishable charge potentials of a polarity opposite to the charge potentials of the charged image and non-image areas in the first electrostatic latent image.
The liquid developers and processes of the present invention possess a number of advantages including the development and generation of images with excellent image quality, the avoidance of a charge director, the use of the developers in a reverse charging development process, excellent, for example, about 90 to about 98 percent image transfer, and the avoidance of complex chemical charging of the developer. Poor transfer can, for example, result in poor solid area coverage if insufficient toner is transferred to the final substrate and can also cause image defects such as smears and hollowed fine features. Overcharging the toner particles can result in low reflective optical density images or poor color richness or chroma since only a few very highly charged particles can discharge all the charge on the dielectric receptor causing too little toner to be deposited. To overcome or minimize such problems, the liquid toners, or developers and processes of the present invention were arrived at after extensive research. Other advantages are as illustrated herein and also include minimal or no image blooming, the generation of excellent solid area images, minimal or no developed image character defects, the enablement of clear, or colorless liquid developers, excellent image resolution, and the like.
PRIOR ART
A latent electrostatic image can be developed with toner particles dispersed in an insulating nonpolar liquid. These dispersed materials are known as liquid toners or liquid developers. The latent electrostatic image may be generated by providing a photoconductive imaging member or layer with a uniform electrostatic charge, and developing the image with a liquid developer, or colored toner particles dispersed in a nonpolar liquid which generally has a high volume resistivity in excess of 10
9
ohm-centimeters, a low dielectric constant, for example below about 3, and a moderate vapor pressure. Generally, the toner particles are less than about 30 &mgr;m (microns) average by area size as measured with the Malvern 3600E particle sizer.
U.S. Pat. No. 5,019,477, the disclosure of which is totally incorporated herein by reference, discloses a liquid electrostatic developer comprising a nonpolar liquid, thermoplastic resin particles, and a charge director. The ionic or zwitterionic charge directors illustrated may include both negative charge directors, such as lecithin, oil-soluble petroleum sulfonates and alkyl succinimide, and positive charge directors such as cobalt and iron naphthanates. The thermoplastic resin particles can comprise a mixture of (1) a polyethylene homopolymer or a copolymer of (i) polyethylene and (ii) acrylic acid, methacrylic acid or alkyl esters thereof, wherein (ii) comprises 0.1 to 20 weight percent of the copolymer; and (2) a random copolymer (iii) of vinyl toluene and styrene and (iv) butadiene and acrylate.
U.S. Pat. No. 5,030,535, the disclosure of which is totally incorporated herein by reference, discloses a liquid developer composition comprising a liquid vehicle, a charge additive and toner pigmented particles. The toner particles may contain pigment particles and a resin selected from the group consisting of polyolefins, halogenated polyolefins and mixtures thereof. The liquid developers can be prepared by first dissolving the polymer resin in a liquid vehicle by heating at temperatures of from about 80° C. to about 120° C., adding pigment to the hot polymer solution and attriting the mixture, and then cooling the mixture whereby the polymer becomes insoluble in the liquid vehicle, thus forming an insoluble resin layer around the pigment particles.
Moreover, in U.S. Pat. No. 4,707,429, the disclosure of which is totally incorporated herein by reference, there are illustrated, for example, liquid developers with an aluminum stearate charge adjuvant. Liquid developers with charge directors are also illustrated in U.S. Pat. No. 5,045,425. Further, of interest with respect to liquid developers are U.S. Pat. Nos. 5,034,299; 5,066,821 and 5,028,508, the disclosures of which are totally incorporated herein by reference.
Illustrated in U.S. Pat. No. 5,306,591, the disclosure of which is totally incorporated herein by reference, is a liquid developer comprised of a liquid component, thermoplastic resin; an ionic or zwitterionic charge director, or directors soluble in a nonpolar liquid, and a charge additive, or charge adjuvant comprised of an imine bisquinone; in U.S. Statutory Invention Registration No. H1483 there is described a liquid developer comprised of thermoplastic resin particles, and a charge director comprised of an ammonium AB diblock copolymer, and in U.S. P
Knapp Christopher M.
Pan David H.
Zhao Weizhong
Goodrow John
Palazzo E. O.
Xerox Corporation
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