Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Reexamination Certificate
2000-02-28
2004-11-09
Dote, Janis L. (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Post imaging process, finishing, or perfecting composition...
C430S115000
Reexamination Certificate
active
06815136
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is generally directed to liquid toner and developer compositions and to imaging processes thereof. More specifically, the present invention relates to improved liquid developer compositions and improved development and imaging processes thereof arising from, for example, including an dispersion-redispersion promoting compound in the liquid developer. The present invention can provide, for example, improved image cake forming processes, improved image cake reconstitution processes, improved imaging processes, improved imaging apparatuses, and improved images.
In electrostatographic imaging processes liquid developers are commonly used. Conventional commercial liquid developers comprise, for example, a dispersion of a mixture of imaging particles including resin and pigment particles dispersed in a liquid hydrocarbon. Once the electrostatic latent image is formed on an imaging member, it can be transported, for example, through a bath of the liquid developer. When in contact with the liquid developer, the charged pigment particles in the liquid developer migrate to the electrostatic latent image and deposit thereon in conformance with the image. The imaging member may then be withdrawn from the liquid developer bath with the marking particles adhering to the electrostatic latent image in image configuration. A thin film of residual developer remains on the surface of the imaging member. In other liquid developer imaging processes there can be formed an intermediate image cake deposited, for example, on the latent image forming member or alternatively, on an intermediate transfer member which subsequently contacts a image forming member for selective developer transfer. The non-image or unused portion of the image cake is typically removed from the image forming member or the intermediate member and discarded.
A significant problem associated with prior art liquid developers, especially those concentrated liquid developers which are initially dispersed or “let-down” in a carrier liquid and then developed or deposited onto an intermediate or developer donor member and then only partially consumed in the given development-imaging cycle, is the inability to be readily recover and redisperse the unused developer material from the donor member for reuse in subsequent development-imaging forming cycles.
Another significant problem with these types of recovered and redispersed liquid developers is that they often do not or cannot redevelop properly and can result in poor development, image quality defects, and unnecessary waste or unusable developer. The foregoing problems are particularly pronounced for high speed liquid developer imaging processes where the amount of reclaimed and redispersed developer can be substantial. These and other problems are solved in embodiments of the present invention.
PRIOR ART
In U.S. Pat. No. 5,206,107, issued Apr. 27, 1993, to Pearlstine, there is disclosed a liquid developer that contains a liquid dispersion medium, marking particles, a polymeric surfactant, an optional colorant, and an optional charge control agent. The polymeric surfactant may be a siloxane surfactant, preferably a siloxane-alkene oxide block copolymer. To prepare the liquid developer, the surfactant may be added as a post additive to previously-formed developer.
In U.S. Pat. No. 5,698,616, issued Dec. 16, 1997, to Baker, et al., there is disclosed an organosol comprising a high molecular weight (co)polymeric steric stabilizer covalently bonded to an insoluble, high molecular weight thermoplastic (co)polymeric core which has the ability to form a three dimensional gel of controlled rigidity. The gel provides improved liquid ink or liquid electrophotographic or electrographic toner compositions by increasing sedimentation stability of the colorant, without compromising print quality or ink transfer performance. The gel is formed by manipulating the solubility parameter difference between the stabilizer and the solvent to achieve optimum performance of the dispersion.
In U.S. Pat. No. 5,306,590, Apr. 26, 1994, to Felder, there is disclosed a high solids replenishable electrostatic liquid developer concentrate that includes toner particles containing a carboxyl terminated polyester resin and a pigment, and a liquid toner dispersant. The solids content of the concentrate is above about 50%. A method for producing the concentrate includes the steps of blending particles containing a carboxyl terminated polyester and a pigment with a liquid toner dispersants to form a toner dispersant mixture and to increase the solids content of the toner dispersant mixture to more than about 90% solids. Toner solids in a liquid electrostatic developer are replenished by adding the toner particles to a toner solids depleted liquid electrostatic developer in a liquid electrostatographic printing machine.
In U.S. Pat. No. 5,254,424, issued Oct. 19, 1993, to Felder, there is disclosed a high solids replenishable electrostatic liquid developer concentrate which contains toner particles formed from a urethane modified polyester. This composition can be concentrated up to toner solids and subsequently sonicated to a working strength dilution.
In U.S. Pat. No. 5,304,451, issued Apr. 19, 1994, to Felder et al. there is disclosed a dry toner which is added to a liquid carrier to replenish a liquid developer in an electrostatographic printing machine.
In U.S. Pat. No. 4,659,640, issued Apr. 21, 1987, to Santilli, et al., there is disclosed a novel liquid electrographic developer containing a volatile, electrically insulating carrier liquid, polyester toner particles, and wax dispersed in the carrier is described. The wax-to-polyester weight ratio in the developer is sufficiently high, preferably above 0.25, thereby rendering the developer self-fixing at room temperature. A novel process for developing an electrostatic latent image on a smooth support using a self-fixing liquid developer is also described. Upon application of the developer to a latent image and evaporation of the liquid carrier from the image, the toner, aided by the wax at the indicated concentration level, is fixed to the surface without the need for externally applied heat.
In U.S. Pat. No. 4,052,325, issued Oct. 4, 1977, to Santilli, et al., there is disclosed a liquid developer containing redispersible, readily heat-fixable toner particles and a process for using the same. The developer is characterized by toner particles containing certain linear polyesters which are physically inert to the liquid carrier vehicle of the liquid developer and which, advantageously, have a melting point in the range of from about 40 to about 150 degrees C.
In U.S. Pat. No. 5,826,147, issued Oct. 20, 1998, to Liu, et al., there is disclosed a novel image development method and apparatus, wherein an imaging member having an imaging surface is provided with a layer of marking material thereon, and an electrostatic latent image is created in the layer of marking material. Image-wise charging of the layer of marking material is accomplished by a wide beam ion source such that free mobile ions are introduced in the vicinity of an electrostatic latent image associated with the imaging member having the layer of marking material coated thereon. The latent image associated with the imaging member causes the free mobile ions to flow in an image-wise ion stream corresponding to the latent image, which, in turn, leads to image-wise charging of the toner layer, such that the toner layer itself becomes the latent image carrier. The latent image carrying toner layer is subsequently developed and transferred to a copy substrate to produce an output document.
In U.S. Pat. No. 5,596,396, issued Jan. 21, 1997, to Landa, et al., there is disclosed an imaging apparatus including a first member having a first surface having formed thereon a latent electrostatic image, the latent electrostatic image including image regions at a first voltage and background regions at a second voltage, a second member charged to a third voltage interme
Kaplan Samuel
Pan David H.
Prest, Jr. William M.
Smith Thomas W.
Zhao Weizhong
Dote Janis L.
Fay Sharpe Fagan Minnich & McKee LLP
Palazzo, Esq. Eugene O.
Xerox Corporation
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