GB944345A - Development of electrostatic images - Google Patents

Abstract

944,345. Electrophotographic developing. KALLE A.G. July 18, 1960 [July 23,1959], No. 24970/60. Heading G2H. [Also in Division H1] A process for producing a developer element for use in developing electrostatic images, e.g. electrophotographic charge images, comprises charging a photoconductive coating on a conducting support, the coating containing 3 to 20% by weight of a wax reckoned on the weight of photoconductive material, completely discharging the coating or partially discharging it to a uniform extent and then applying an electrically charged toner to the coating. Preferably the photoconductive coating comprises one or more known organic photoconductors such as oxadiazoles, triazoles, oxazoles, imidazolones, pyrazolones, pyrazolines tetrahydroimidazole, benzanthrene, chrysene, stilbene derivatives,triphenyl derivatives of fluorene, thiophene or pyrrole, triphenylamine and its alkyl derivatives, and polymers such as polyvinyl carbazole, polyindene, polyvinyl naphthalene or quinoline, polyacenaphthene; and in addition to the wax which may be animal, vegetable, mineral or synthetic, the layer may also contain natural or synthetic resins such as colophony shellac, vinyl polymers, polyolefines, polyamides, polyesters, chlorinated rubber or condensation resins from formaldehyde and phenol, urea, melamine, or ketones. As an alternative to inclusion in the coating the wax may be applied as a thin film e.g. 0. 5 to 20Á, over the photoconductive layer. The conductive support may be any material having a resistivity not greater than 10<SP>12</SP> ohm-cms and may thus be of metal, paper, regenerated cellulose, polyvinyl alcohol, polyamides, polyurethanes or insulating synthetic plastic materials coated with or containing electrically conductive materials. The developer element may be used to develop an electrostatic image by simply pressing the element on to the image. The used element may be regenerated by blowing or brushing off the residual toner and again charging, exposing, and dusting with toner.