Abstract: The invention provides electrophotographic apparatus for forming a subsequent toner image overlapping one or more toner images previously formed on a surface of an electrophotographic element.The apparatus includes means for electrically charging the surface and the previously formed toner image or images, and means for forming an electrostatic latent image overlapping the previously formed toner image or images on the surface by imagewise exposing the element, through the previously formed toner image or images. The latent image forming means provides actinic radiation of a wavelength outside the range of 400 to 700 nanometers with the density of the previously formed toner image or images to the actinic radiation being less than about 0.2. The apparatus further includes means for electrographically developing the electrostatic latent image to thereby form the subsequent toner image.

Abstract: The invention provides new crosslinked vinyl polymer particles, new coating compositions containing such particles, new liquid electrographic developers containing such particles, new electrographic elements containing one or more layers comprising such particles, and new electrographic records containing toner images and/or layers comprising such particles.The polymeric particles of the invention are characterized in that each particle has an average diameter less than one micrometer and comprises a crosslinked vinyl addition copolymer obtainable by aqueous emulsion polymerization of a mixture of monomers wherein:1.5-15 percent by weight of the mixture of monomers comprises polyfunctional vinyl addition-polymerizable monomers in order to form crosslinking structural units in the copolymer;85-98.5 percent by weight of the mixture of monomers comprises monofunctional vinyl addition-polymerizable monomers selected such that:A. 0-98.

Abstract: In plural-stage liquid development of electrostatic charge patterns, as in multicolor electro-photography, image defects occur in areas of the image which are undeveloped or background areas of a previous development stage. The method of the invention avoids such defects by rinsing the image with a polar liquid between development stages to remove counterions which are believed to cause the defects.

Abstract: 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.

Abstract: The invention provides an electrophotographic method of forming a subsequent toner image overlapping one or more toner images previously formed on a surface of an electrophotographic element.The method comprises the steps of:(a) electrically charging the surface and the previously formed toner image or images,(b) forming an electrostatic latent image overlapping the previously formed toner image or images on the surface by imagewise exposing the element, through the previously formed toner image or images, to actinic radiation of a wavelength outside the range of 400 to 700 nanometers; the density of the previously formed toner image or images to the actinic radiation being less than about 0.2, and(c) electrographically developing the electrostatic latent image to thereby form the subsequent toner image.

Abstract: Novel 1,4-bis aryl-azo derivatives of 2,3-naphthalenediol in which the aryl groups are substituted with alkoxy and with sulfonamide or fluorosulfonyl groups. These compounds are useful as neutral density pigments in electrophotographic developers and have good light stability.

Abstract: Bis aryl-azo compounds of the formula ##STR1## wherein R.sup.1 is lower alkyl and R.sup.2 is fluoro or amino. The compounds are useful as neutral density pigments in electrophotographic developers and have good light stability.

Abstract: A planar array of microcells is formed in a support. An electrostatic charge pattern is established on the support differentiating first and second interlaid sets of microcells. An electrographic imaging composition is introduced into the first set of microcells, and a second, differing imaging composition is introduced into the second set of microcells. Multicolor photographic elements, particularly dye image transfer photographic elements, can be prepared.

Abstract: Polyesterionomers having the structure ##STR1## wherein G.sup.1 represents a straight or branched chain alkylene having about 2 to 12 carbon atoms, or, substituted or unsubstituted cycloalkylene, cycloalkylenebis(oxyalkylene) or cycloalkylenedialkylene;G.sup.

Abstract: Liquid developers for electrography are provided containing soluble polymeric dispersing agents that comprise a phosphonate moiety. The phosphonate moiety comprises a phosphonic acid group, a half-ester of a phosphonic acid group, or a salt of either of these groups.

Abstract: Polyesterionomers useful as a binder in liquid electrophotographic developers having the structure are disclosed.

Abstract: Liquid developers for electrography are provided containing soluble polymeric dispersing agents that comprise a phosphonate moiety. The phosphonate moiety comprises a phosphonic acid group, a half-ester of a phosphonic acid group, or a salt of either of these groups.

Abstract: An electrographic liquid developer comprising a carrier liquid and a marking particle which comprises a dye compound having the formula: ##STR1## wherein: R.sup.1 is H, COOH, CONH.sub.2, --SO.sub.2 NH.sub.2 or --SO.sub.3 M where M is Na.sup.+ or NH.sub.4 ;R.sup.2 is a lower alkoxy radical, --OCH.sub.2 CONH.sub.2, or ##STR2##where each of R.sup.6 and R.sup.7 is a lower alkyl radical; andR.sup.3 is H, a lower alkyl radical, a lower alkoxy radical or NO.sub.2.

Abstract: 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.degree. to about 150.degree. C.