Oce-nederland B.v.

Gerard J Van Lomm

Roelof Hendrik Everhardus

A multi-layered electrophotographic element providing significantly improved properties, and especially so for use as a 'permanent' master in transfer photocopying, comprises a conductive support carrying a photoconductive charge generating layer and on top of the photoconductive layer a charge transporting layer containing homogeneously distributed in an insulating binder a charge transporting agent selected from among certain azines which may comprise one or more alkylsubstituents and/or heterocyclic groups with at least one nitrogen atom and/or phenyl or naphthyl groups. The charge transporting layer may also contain to advantage an activator for the charge transporting agent. Particularly effective activators are terephthalal dimalonitrile (TDM) and 1,3,7- trinitro-dibenzothiophene-5,5-dioxide (DBTO). The charge transporting layer preferably is applied to a very thin charge generating layer formed on an endless support, and which contains the charge generating compound in molecularly divided form. Photocopying can be carried out with enhanced permanence of the usefulness of the element by charging the element for each copying operation to not more than about 70% of its maximum chargeable surface voltage.

Electrophotographic element and photocopying process making use of

An electrophotographic element that comprises an electrically conductive support and a photoconductive layer containing a photosensitive azo-compound dispersed in a film-forming polymeric binder is prepared by synthesizing the photosensitive azo-compound in situ, by reaction between a diazonium compound and an azo-coupling component, in the film-forming polymeric layer on the support. The azo-compounds thus synthetized are distributed in the binder layer in an almost perfectly homogeneous form. Under an electron microscope screen scan they are not distinguishable as separate particles, even at a ten thousand fold magnification. By forming a very thin photoconductive layer in this way and coating it with a charge transporting top layer, especially useful electrophotographic elements are obtained. The invention relates also to electrophotographic elements prepared according to the process.

Growing community of inventors

Tegelen, Netherlands

Gerard J Van Lomm